The potential of carbon and nitrogen isotopes to conservatively discriminate between subsoil sediment sources

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick; Olley, Jon

2013-04-01

Moreton Bay, in South East Queensland, Australia, is a Ramsar wetland of international significance. A decline of the bay's ecosystem health has been primarily attributed to sediments and nutrients from catchment sources. Sediment budgets for three catchments indicated gully erosion dominates the supply of sediment in Knapp Creek and the Upper Bremer River whereas erosion from cultivated soils is the primary sediment source in Blackfellow Creek. Sediment tracing with fallout-radionuclides confirmed subsoil erosion processes dominate the supply of sediment in Knapp Creek and the Upper Bremer River whereas in Blackfellow Creek cultivated and subsoil sources contribute >90% of sediments. Other sediment properties are required to determine the relative sediment contributions of channel bank, gully and cultivated sources in these catchments. The potential of total organic carbon (TOC), total nitrogen (TN), and carbon and nitrogen stable isotopes (δ13C, δ15N) to conservatively discriminate between subsoil sediment sources is presented. The conservativeness of these sediment properties was examined through evaluating particle size variations in depth core soil samples and investigating whether they remain constant in source soils over two sampling occasions. Varying conservative behavior and source discrimination was observed. TN in the

Estimation of different source contributions to sediment organic matter in an agricultural-forested watershed using end member mixing analyses based on stable isotope ratios and fluorescence spectroscopy.

PubMed

Derrien, Morgane; Kim, Min-Seob; Ock, Giyoung; Hong, Seongjin; Cho, Jinwoo; Shin, Kyung-Hoon; Hur, Jin

2018-03-15

The two popular source tracing tools of stable isotope ratios (δ 13 C and δ 15 N) and fluorescence spectroscopy were used to estimate the relative source contributions to sediment organic matter (SeOM) at five different river sites in an agricultural-forested watershed (Soyang Lake watershed), and their capabilities for the source assignment were compared. Bulk sediments were used for the stable isotopes, while alkaline extractable organic matter (AEOM) from sediments was used to obtain fluorescent indices for SeOM. Several source discrimination indices were fully compiled for a range of the SeOM sources distributed in the catchments of the watershed, which included soils, forest leaves, crop (C3 and C4) and riparian plants, periphyton, and organic fertilizers. The relative source contributions to the river sediment samples were estimated via end member mixing analysis (EMMA) based on several selected discrimination indices. The EMMA based on the isotopes demonstrated that all sediments were characterized by a medium to a high contribution of periphyton ranging from ~30% to 70% except for one site heavily affected by forest and agricultural fields with relatively high contributions of terrestrial materials. The EMMA based on fluorescence parameters, however, did not show similar results with low contributions from forest leaf and periphyton. The characteristics of the studied watershed were more consistent with the source contributions determined by the isotope ratios. The discrepancy in the EMMA capability for source assignments between the two analytical tools can be explained by the limited analytical window of fluorescence spectroscopy for non-fluorescent dissolved organic matter (FDOM) and the inability of AEOM to represent original bulk particulate organic matter (POM). Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding Stream Channel Sediment Source Contributions For The Paradise Creek Watershed In Northern Idaho

NASA Astrophysics Data System (ADS)

Rittenburg, R.; Boll, J.; Brooks, E. S.

2013-12-01

Excess sediment from agricultural areas has been a major source of impairment for water bodies, resulting in the implementation of mitigation measures across landscapes. Watershed scale reductions often target upland erosion as key non-point sources for sediment loading. Stream channel dynamics, however, also play a contributing role in sediment loading in the form of legacy sediments, channel erosion and deposition, and buffering during storm events. In-stream contributions are not well understood, and are a potentially important consideration for Total Maximum Daily Loads (TMDLs). The objective of this study is to differentiate stream bank and stream bed sediment contributions and better understand the role of legacy sediments. The study area is the Paradise Creek Watershed in northern Idaho. We modeled sediment yield to the channel system using the Water Erosion Prediction Project (WEPP) model, and subsequent channel erosion and deposition using CONCEPTs. Field observations of cross-sections along the channel system over a 5-year period were collected to verify model simulations and to test the hypothesis that the watershed load was composed predominantly of legacy sediments. Our modeling study shows that stream channels contributed to 39% of the total annual sediment load for the basin, with a 19-year time lag between sediments entering the stream to leaving the watershed outlet. Observations from long-term cross sectional data in the watershed, and a sediment fingerprinting analysis will be presented to better understand sediment contributions from within the stream channel system.

Quantifying stream channel sediment contributions for the Paradise Creek Watershed in northern Idaho

NASA Astrophysics Data System (ADS)

Rittenburg, R.; Squires, A.; Boll, J.; Brooks, E. S.

2012-12-01

Excess sediment from agricultural areas has been a major source of impairment for water bodies around the world, resulting in the implementation of mitigation measures across landscapes. Watershed scale reductions often target upland erosion as key non-point sources for sediment loading. Stream channel dynamics, however, also play a contributing role in sediment loading in the form of legacy sediments, channel erosion and deposition, and buffering during storm events. Little is known about in-stream contributions, a potentially important consideration for Total Maximum Daily Loads (TMDLs). The objective of this study is to identify where and when sediment is delivered to the stream and the spatial and temporal stream channel contributions to the overall watershed scale sediment load. The study area is the Paradise Creek Watershed in northern Idaho. We modeled sediment yield to the channel system using the Water Erosion Prediction Project (WEPP) model, and subsequent channel erosion and deposition using CONCEPTs. Field observations of cross-sections along the channel system over a 5-year period were collected to verify model simulations and to test the hypothesis that the watershed load was made up predominantly of legacy sediments. Our modeling study shows that stream channels contributed to 50% of the total annual sediment load for the basin, with a 19 year time lag between sediments entering the stream to leaving the watershed outlet. Observations from long-term data in the watershed will be presented to indicate if the main source of the sediment is from either rural and urban non-point sources or the channel system.

Variability in source sediment contributions by applying different statistic test for a Pyrenean catchment.

PubMed

Palazón, L; Navas, A

2017-06-01

Information on sediment contribution and transport dynamics from the contributing catchments is needed to develop management plans to tackle environmental problems related with effects of fine sediment as reservoir siltation. In this respect, the fingerprinting technique is an indirect technique known to be valuable and effective for sediment source identification in river catchments. Large variability in sediment delivery was found in previous studies in the Barasona catchment (1509 km 2 , Central Spanish Pyrenees). Simulation results with SWAT and fingerprinting approaches identified badlands and agricultural uses as the main contributors to sediment supply in the reservoir. In this study the <63 μm sediment fraction from the surface reservoir sediments (2 cm) are investigated following the fingerprinting procedure to assess how the use of different statistical procedures affects the amounts of source contributions. Three optimum composite fingerprints were selected to discriminate between source contributions based in land uses/land covers from the same dataset by the application of (1) discriminant function analysis; and its combination (as second step) with (2) Kruskal-Wallis H-test and (3) principal components analysis. Source contribution results were different between assessed options with the greatest differences observed for option using #3, including the two step process: principal components analysis and discriminant function analysis. The characteristics of the solutions by the applied mixing model and the conceptual understanding of the catchment showed that the most reliable solution was achieved using #2, the two step process of Kruskal-Wallis H-test and discriminant function analysis. The assessment showed the importance of the statistical procedure used to define the optimum composite fingerprint for sediment fingerprinting applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Alternative method to trace sediment sources in a subtropical rural catchment of southern Brazil by using near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Tiecher, Tales; Caner, Laurent; Gomes Minella, Jean Paolo; Henrique Ciotti, Lucas; Antônio Bender, Marcos; dos Santos Rheinheimer, Danilo

2014-05-01

Conventional fingerprinting methods based on geochemical composition still require a time-consuming and critical preliminary sample preparation. Thus, fingerprinting characteristics that can be measured in a rapid and cheap way requiring a minimal sample preparation, such as spectroscopy methods, should be used. The present study aimed to evaluate the sediment sources contribution in a rural catchment by using conventional method based on geochemical composition and on an alternative method based on near-infrared spectroscopy. This study was carried out in a rural catchment with an area of 1,19 km2 located in southern Brazil. The sediment sources evaluated were crop fields (n=20), unpaved roads (n=10) and stream channels (n=10). Thirty suspended sediment samples were collected from eight significant storm runoff events between 2009 and 2011. Sources and sediment samples were dried at 50oC and sieved at 63 µm. The total concentration of Ag, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Sr, Ti, Tl, V and Zn were estimated by ICP-OES after microwave assisted digestion with concentrated HNO3 and HCl. Total organic carbon (TOC) was estimated by wet oxidation with K2Cr2O7 and H2SO4. The near-infrared spectra scan range was 4000 to 10000 cm-1 at a resolution of 2 cm-1, with 100 co added scans per spectrum. The steps used in the conventional method were: i) tracer selection based on Kruskal-Wallis test, ii) selection of the best set of tracers using discriminant analyses and finally iii) the use of a mixed linear model to calculate the sediment sources contribution. The steps used in the alternative method were i) principal component analyses to reduce the number of variables, ii) discriminant analyses to determine the tracer potential of the near-infrared spectroscopy, and finally iii) the use of past least square based on 48 mixtures of the sediment sources in various weight proportions to calculate the sediment sources contribution. Both conventional and alternative methods were capable to discriminate 100% of the sediment sources. Conventional fingerprinting method provided a sediment sources contribution of 33±19% by crop fields, 25±13% by unpaved roads and 42±19% by stream channels. The contribution of sediment sources obtained by alternative fingerprinting method using near-infrared spectroscopy was 71±22% of crop fields, 21±12% of unpaved roads and 14±19% of stream channels. No correlation was observed between source contribution assessed by the two methods. Notwithstanding, the average contribution of the unpaved roads was similar by both methods. The highest difference in the average contribution of crop fields and stream channels estimated by the two methods was due to similar organic matter content of these two sediment sources which hampers their discrimination by assessing the near-infrared spectra, where much of the bands are highly correlated with the TOC levels. Efforts should be taken to try to combine both the geochemical composition and near-infrared spectroscopy information on a single estimative of the sediment sources contribution.

Stream Sediment Sources in Midwest Agricultural Basins with Land Retirement along Channel.

PubMed

Williamson, T N; Christensen, V G; Richardson, W B; Frey, J W; Gellis, A C; Kieta, K A; Fitzpatrick, F A

2014-09-01

Documenting the effects of agricultural land retirement on stream-sediment sources is critical to identifying management practices that improve water quality and aquatic habitat. Particularly difficult to quantify are the effects from conservation easements that commonly are discontinuous along channelized streams and ditches throughout the agricultural midwestern United States. Our hypotheses were that sediment from cropland, retired land, stream banks, and roads would be discernible using isotopic and elemental concentrations and that source contributions would vary with land retirement distribution along tributaries of West Fork Beaver Creek in Minnesota. Channel-bed and suspended sediment were sampled at nine locations and compared with local source samples by using linear discriminant analysis and a four-source mixing model that evaluated seven tracers: In, P, total C, Be, Tl, Th, and Ti. The proportion of sediment sources differed significantly between suspended and channel-bed sediment. Retired land contributed to channel-bed sediment but was not discernible as a source of suspended sediment, suggesting that retired-land material was not mobilized during high-flow conditions. Stream banks were a large contributor to suspended sediment; however, the percentage of stream-bank sediment in the channel bed was lower in basins with more continuous retired land along the riparian corridor. Cropland sediments had the highest P concentrations; basins with the highest cropland-sediment contributions also had the highest P concentrations. Along stream reaches with retired land, there was a lower proportion of cropland material in suspended sediment relative to sites that had almost no land retirement, indicating less movement of nutrients and sediment from cropland to the channel as a result of land retirement. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Stream sediment sources in midwest agricultural basins with land retirement along channel

USGS Publications Warehouse

Williamson, Tanja N.; Christensen, Victoria G.; Richardson, William B.; Frey, Jeffrey W.; Gellis, Allen C.; Kieta, K. A.; Fitzpatrick, Faith A.

2014-01-01

Documenting the effects of agricultural land retirement on stream-sediment sources is critical to identifying management practices that improve water quality and aquatic habitat. Particularly difficult to quantify are the effects from conservation easements that commonly are discontinuous along channelized streams and ditches throughout the agricultural midwestern United States. Our hypotheses were that sediment from cropland, retired land, stream banks, and roads would be discernible using isotopic and elemental concentrations and that source contributions would vary with land retirement distribution along tributaries of West Fork Beaver Creek in Minnesota. Channel-bed and suspended sediment were sampled at nine locations and compared with local source samples by using linear discriminant analysis and a four-source mixing model that evaluated seven tracers: In, P, total C, Be, Tl, Th, and Ti. The proportion of sediment sources differed significantly between suspended and channel-bed sediment. Retired land contributed to channel-bed sediment but was not discernible as a source of suspended sediment, suggesting that retired-land material was not mobilized during high-flow conditions. Stream banks were a large contributor to suspended sediment; however, the percentage of stream-bank sediment in the channel bed was lower in basins with more continuous retired land along the riparian corridor. Cropland sediments had the highest P concentrations; basins with the highest cropland-sediment contributions also had the highest P concentrations. Along stream reaches with retired land, there was a lower proportion of cropland material in suspended sediment relative to sites that had almost no land retirement, indicating less movement of nutrients and sediment from cropland to the channel as a result of land retirement.

Estimation of sediment sources using selected chemical tracers in the Perry lake basin, Kansas, USA

USGS Publications Warehouse

Juracek, K.E.; Ziegler, A.C.

2009-01-01

The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. In an investigation of sources of fine-grained sediment (clay and silt) within the Perry Lake Basin in northeast Kansas, representative samples of channel-bank sources, surface-soil sources (cropland and grassland), and reservoir bottom sediment were collected, chemically analyzed, and compared. The samples were sieved to isolate the <63 ?? m fraction and analyzed for selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, and the radionuclide cesium-137 (137Cs). On the basis of substantial and consistent compositional differences among the source types, total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and 137Cs were selected for use in the estimation of sediment sources. To further account for differences in particle-size composition between the sources and the reservoir bottom sediment, constituent ratio and clay-normalization techniques were used. Computed ratios included TOC to TN, TOC to TP, and TN to TP. Constituent concentrations (TN, TP, TOC) and activities (137Cs) were normalized by dividing by the percentage of clay. Thus, the sediment-source estimations involved the use of seven sediment-source indicators. Within the Perry Lake Basin, the consensus of the seven indicators was that both channel-bank and surface-soil sources were important in the Atchison County Lake and Banner Creek Reservoir subbasins, whereas channel-bank sources were dominant in the Mission Lake subbasin. On the sole basis of 137Cs activity, surface-soil sources contributed the most fine-grained sediment to Atchison County Lake, and channel-bank sources contributed the most fine-grained sediment to Banner Creek Reservoir and Mission Lake. Both the seven-indicator consensus and 137Cs indicated that channel-bank sources were dominant for Perry Lake and that channel-bank sources increased in importance with distance downstream in the basin. ?? 2009 International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research.

Sediment sources in a small agricultural catchment: A composite fingerprinting approach based on the selection of potential sources

NASA Astrophysics Data System (ADS)

Zhou, Huiping; Chang, Weina; Zhang, Longjiang

2016-08-01

Fingerprinting techniques have been widely used as a reasonable and reliable means for investigating sediment sources, especially in relatively large catchments in which there are significant differences in surface materials. However, the discrimination power of fingerprint properties for small catchments, in which the surface materials are relatively homogeneous and human interference is marked, may be affected by fragmentary or confused source information. Using fingerprinting techniques can be difficult, and there is still a need for further studies to verify the effectiveness of such techniques in these small catchments. A composite fingerprinting approach was used in this study to investigate the main sources of sediment output, as well as their relative contributions, from a small catchment (30 km2) with high levels of farming and mining activities. The impact of the selection of different potential sediment sources on the derivation of composite fingerprints and its discrimination power were also investigated by comparing the results from different combinations of potential source types. The initial source types and several samples that could cause confusion were adjusted. These adjustments improved the discrimination power of the composite fingerprints. The results showed that the composite fingerprinting approach used in this study had a discriminatory efficiency of 89.2% for different sediment sources and that the model had a mean goodness of fit of 0.90. Cultivated lands were the main sediment source. The sediment contribution of the studied cultivated lands ranged from 39.9% to 87.8%, with a mean of 76.6%, for multiple deposited sediment samples. The mean contribution of woodlands was 21.7%. Overall, the sediment contribution from mining and road areas was relatively low. The selection of potential sources is an important factor in the application of fingerprinting techniques and warrants more attention in future studies, as is the case with other uncertainty factors.

Combining sediment fingerprinting and a conceptual model for erosion and sediment transfer to explore sediment sources in an Alpine catchment

NASA Astrophysics Data System (ADS)

Costa, A.; Stutenbecker, L.; Anghileri, D.; Bakker, M.; Lane, S. N.; Molnar, P.; Schlunegger, F.

2017-12-01

In Alpine basins, sediment production and transfer is increasingly affected by climate change and human activities, specifically hydropower exploitation. Changes in sediment sources and pathways significantly influence basin management, biodiversity and landscape evolution. We explore the dynamics of sediment sources in a partially glaciated and highly regulated Alpine basin, the Borgne basin, by combining geochemical fingerprinting with the modelling of erosion and sediment transfer. The Borgne basin in southwest Switzerland is composed of three main litho-tectonic units, which we characterised following a tributary-sampling approach from lithologically characteristic sub-basins. We analysed bulk geochemistry using lithium borate fusion coupled with ICP-ES, and we used it to discriminate the three lithologic sources using statistical methods. Finally, we applied a mixing model to estimate the relative contributions of the three sources to the sediment sampled at the outlet. We combine results of the sediment fingerprinting with simulations of a spatially distributed conceptual model for erosion and transport of fine sediment. The model expresses sediment erosion by differentiating the contributions of erosional processes driven by erosive rainfall, snowmelt, and icemelt. Soil erodibility is accounted for as function of land-use and sediment fluxes are linearly convoluted to the outlet by sediment transfer rates for hillslope and river cells, which are a function of sediment connectivity. Sediment connectivity is estimated on the basis of topographic-hydraulic connectivity, flow duration associated with hydropower flow abstraction and permanent storage in hydropower reservoirs. Sediment fingerprinting at the outlet of the Borgne shows a consistent dominance (68-89%) of material derived from the uppermost, highly glaciated reaches, while contributions of the lower part (10-25%) and middle part (1-16%), where rainfall erosion is predominant, are minor. This result is confirmed by the model simulation which shows that, despite the large flow abstraction (about 90%), the upstream reaches contribute the most of the sediments. This study shows how combining geochemical techniques and sediment erosion models provides insight in the dynamics of sediment sources.

Use of sediment source fingerprinting to assess the role of subsurface erosion in the supply of fine sediment in a degraded catchment in the Eastern Cape, South Africa.

PubMed

Manjoro, Munyaradzi; Rowntree, Kate; Kakembo, Vincent; Foster, Ian; Collins, Adrian L

2017-06-01

Sediment source fingerprinting has been successfully deployed to provide information on the surface and subsurface sources of sediment in many catchments around the world. However, there is still scope to re-examine some of the major assumptions of the technique with reference to the number of fingerprint properties used in the model, the number of model iterations and the potential uncertainties of using more than one sediment core collected from the same floodplain sink. We investigated the role of subsurface erosion in the supply of fine sediment to two sediment cores collected from a floodplain in a small degraded catchment in the Eastern Cape, South Africa. The results showed that increasing the number of individual fingerprint properties in the composite signature did not improve the model goodness-of-fit. This is still a much debated issue in sediment source fingerprinting. To test the goodness-of-fit further, the number of model repeat iterations was increased from 5000 to 30,000. However, this did not reduce uncertainty ranges in modelled source proportions nor improve the model goodness-of-fit. The estimated sediment source contributions were not consistent with the available published data on erosion processes in the study catchment. The temporal pattern of sediment source contributions predicted for the two sediment cores was very different despite the cores being collected in close proximity from the same floodplain. This highlights some of the potential limitations associated with using floodplain cores to reconstruct catchment erosion processes and associated sediment source contributions. For the source tracing approach in general, the findings here suggest the need for further investigations into uncertainties related to the number of fingerprint properties included in un-mixing models. The findings support the current widespread use of ≤5000 model repeat iterations for estimating the key sources of sediment samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Floodplains as a source of fine sediment in grazed landscapes: Tracing the source of suspended sediment in the headwaters of an intensively managed agricultural landscape

NASA Astrophysics Data System (ADS)

Yu, Mingjing; Rhoads, Bruce L.

2018-05-01

The flux of fine sediment within agricultural watersheds is an important factor determining the environmental quality of streams and rivers. Despite this importance, the contributions of sediment sources to suspended sediment loads within intensively managed agricultural watersheds remain poorly understood. This study assesses the provenance of fine suspended sediment in the headwater portion of a river flowing through an agricultural landscape in Illinois. Sediment source samples were collected from five sources: croplands, forested floodplains, grasslands, upper grazed floodplains, and lower grazed floodplains. Event-based and aggregated suspended sediment samples were collected from the stream at the watershed outlet. Quantitative geochemical fingerprinting techniques and a mixing model were employed to estimate the relative contributions of sediment from the five sources to the suspended sediment loads. To account for possible effects of small sample sizes, the analysis was repeated with only two sources: grazed floodplains and croplands/grasslands/forested floodplains. Results based on mean values of tracers indicate that the vast majority of suspended sediment within the stream (>95%) is derived from erosion of channel banks and the soil surface within areas of grazed floodplains. Uncertainty analysis based on Monte Carlo simulations indicates that mean values of tracer properties, which do not account for sampling variability in these properties, probably overestimate contributions from the two major sources. Nevertheless, this analysis still supports the conclusion that floodplain erosion accounts for the largest percentage of instream sediment (≈55-75%). Although grazing occurs over only a small portion of the total watershed area, grazed floodplains, which lie in close proximity to the stream channel, are an important source of sediment in this headwater steam system. Efforts to reduce fluxes of fine sediment in this intensively managed landscape should focus on eroding floodplain surfaces and channel banks within heavily grazed reaches of the stream.

Ascribing soil erosion of hillslope components to river sediment yield.

PubMed

Nosrati, Kazem

2017-06-01

In recent decades, soil erosion has increased in catchments of Iran. It is, therefore, necessary to understand soil erosion processes and sources in order to mitigate this problem. Geomorphic landforms play an important role in influencing water erosion. Therefore, ascribing hillslope components soil erosion to river sediment yield could be useful for soil and sediment management in order to decrease the off-site effects related to downstream sedimentation areas. The main objectives of this study were to apply radionuclide tracers and soil organic carbon to determine relative contributions of hillslope component sediment sources in two land use types (forest and crop field) by using a Bayesian-mixing model, as well as to estimate the uncertainty in sediment fingerprinting in a mountainous catchment of western Iran. In this analysis, 137 Cs, 40 K, 238 U, 226 Ra, 232 Th and soil organic carbon tracers were measured in 32 different sampling sites from four hillslope component sediment sources (summit, shoulder, backslope, and toeslope) in forested and crop fields along with six bed sediment samples at the downstream reach of the catchment. To quantify the sediment source proportions, the Bayesian mixing model was based on (1) primary sediment sources and (2) combined primary and secondary sediment sources. The results of both approaches indicated that erosion from crop field shoulder dominated the sources of river sediments. The estimated contribution of crop field shoulder for all river samples was 63.7% (32.4-79.8%) for primary sediment sources approach, and 67% (15.3%-81.7%) for the combined primary and secondary sources approach. The Bayesian mixing model, based on an optimum set of tracers, estimated that the highest contribution of soil erosion in crop field land use and shoulder-component landforms constituted the most important land-use factor. This technique could, therefore, be a useful tool for soil and sediment control management strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Glacial and nonglacial sediment contributions to Wisconsin episode loess in the Central United States

USGS Publications Warehouse

Grimley, D.A.

2000-01-01

The relative contributions of various glacial and nonglacial sediments to Wisconsin Episode loess units along the lower Illinois and central Mississippi Valleys are estimated on the basis of a comparison of magnetic susceptibility and silt and clay mineralogy. A mathematical method of source area calculation, using four compositional parameters, was guided by current knowledge of the regional glacial history. On the basis of this technique, the Roxana Silt, along the Illinois and Mississippi River Valleys, is composed of significant Superior lobe sediment (35%-40%) as well as Wadena or Des Moines lobe sediment (about 35%). This can account for its high magnetic susceptibility, feldspar content, kaolinite content, and pink hue. Lower Peoria Silt contains about 25%-35% Lake Michigan lobe sediment with reduced contributions of the other sources. After the Mississippi River's diversion (20.4 ka), the supply of Superior, Des Moines, and Wadena lobe sediment was cut off from the Illinois Valley in favor of Lake Michigan lobe sediment (75%- 80% contribution). This major source area shift accounts for higher dolomite and illite contents and a more yellow hue in approximately the upper two-thirds of Peoria Silt in the study area. In loess south of St. Louis, less pronounced compositional shifts occur because Superior lobe sediment was not cut off and because Des Moines lobe, Wadena lobe, and Missouri River sediments, having more intermediate composition, compose 40%-50% of the loess, thereby diluting other source area changes. Nonglacial sediment, from fluvial and periglacial sources, is estimated to compose 10%-40% of loess in both regions.

Cyclic Sediment Trading Between Channel and River Bed Sediments

NASA Astrophysics Data System (ADS)

Haddadchi, A.

2015-12-01

Much of the previous work on sediment tracing has focused on determining either the initial sources of the sediment (soils derive from a particular rock type) or the erosion processes generating the sediment. However, alluvial stores can be both a source and sink for sediment transported by streams. Here geochemical and fallout radionuclide tracing of river-bed and alluvial sediments are used to determine the role of secondary sources, sediment stores, as potential sources of sediment leaving Emu Creek catchment, southeastern Queensland, Australia. Activity concentrations of 137Cs on the river sediments are consistent with channel erosion being the dominant source at all sites sampled along the river. To characterise the deposition and remobilisation cycles in the catchment, a novel geochemical tracing approach was used. Successive pockets of alluvium were treated as discrete sink terms within geochemical mixing models and their source contributions compared with those of river bed sediments collected adjacent to each alluvial pocket. Three different size fractions were examined; silts and clays (<10 μm), silts (10-63 μm), and fine sands (63-212 μm). The contribution of the initial soil/rock type sources to river bed and alluvial sediments at each sampling site was identical for all three different size fractions, but varied along the stream. Combining these findings it is concluded that proximal alluvial stores dominated the supply of sediment to the river at each location, with this being particularly evident at the catchment outlet. Identical contribution of rock type sources to both river bed and alluvial pockets together with the dominant erosion being from channel banks indicates a high degree of 'trading' between the fluvial space and the alluvial space. Hence, management works aimed at primarily reducing the supply of sediments to the outlet of Emu Creek should focus on rehabilitation of channel banks in the lower catchment.

Suspended sediments from upstream tributaries as the source of downstream river sites

NASA Astrophysics Data System (ADS)

Haddadchi, Arman; Olley, Jon

2014-05-01

Understanding the efficiency with which sediment eroded from different sources is transported to the catchment outlet is a key knowledge gap that is critical to our ability to accurately target and prioritise management actions to reduce sediment delivery. Sediment fingerprinting has proven to be an efficient approach to determine the sources of sediment. This study examines the suspended sediment sources from Emu Creek catchment, south eastern Queensland, Australia. In addition to collect suspended sediments from different sites of the streams after the confluence of tributaries and outlet of the catchment, time integrated suspended samples from upper tributaries were used as the source of sediment, instead of using hillslope and channel bank samples. Totally, 35 time-integrated samplers were used to compute the contribution of suspended sediments from different upstream waterways to the downstream sediment sites. Three size fractions of materials including fine sand (63-210 μm), silt (10-63 μm) and fine silt and clay (<10 μm) were used to find the effect of particle size on the contribution of upper sediments as the sources of sediment after river confluences. And then samples were analysed by ICP-MS and -OES to find 41 sediment fingerprints. According to the results of Student's T-distribution mixing model, small creeks in the middle and lower part of the catchment were major source in different size fractions, especially in silt (10-63 μm) samples. Gowrie Creek as covers southern-upstream part of the catchment was a major contributor at the outlet of the catchment in finest size fraction (<10 μm) Large differences between the contributions of suspended sediments from upper tributaries in different size fractions necessitate the selection of appropriate size fraction on sediment tracing in the catchment and also major effect of particle size on the movement and deposition of sediments.

Source Apportionment of Suspended Sediment Sources using 137Cs and 210Pbxs

NASA Astrophysics Data System (ADS)

Lamba, J.; Karthikeyan, K.; Thompson, A.

2017-12-01

A study was conducted in the Pleasant Valley Watershed (50 km 2) in South Central Wisconsin to better understand sediment transport processes using sediment fingerprinting technique. Previous studies conducted in this watershed showed that resuspension of fine sediment deposited on the stream bed is an important source of suspended sediment. To better understand the role of fine sediment deposited on the stream bed, fallout radionuclides,137Cs and 210Pbxs were used to determine relative contribution to suspended sediment from in-stream (stream bank and stream bed) and upland sediment sources. Suspended sediment samples were collected during the crop growing season. Potential sources of suspended sediment considered in this study included cropland, pasture and in-stream (stream bed and stream bank). Suspended sediment sources were determined at a subwatershed level. Results of this study showed that in-stream sediment sources are important sources of suspended sediment. Future research should be conducted to better understand the role of legacy sediment in watershed-level sediment transport processes.

Topographic filtering simulation model for sediment source apportionment

NASA Astrophysics Data System (ADS)

Cho, Se Jong; Wilcock, Peter; Hobbs, Benjamin

2018-05-01

We propose a Topographic Filtering simulation model (Topofilter) that can be used to identify those locations that are likely to contribute most of the sediment load delivered from a watershed. The reduced complexity model links spatially distributed estimates of annual soil erosion, high-resolution topography, and observed sediment loading to determine the distribution of sediment delivery ratio across a watershed. The model uses two simple two-parameter topographic transfer functions based on the distance and change in elevation from upland sources to the nearest stream channel and then down the stream network. The approach does not attempt to find a single best-calibrated solution of sediment delivery, but uses a model conditioning approach to develop a large number of possible solutions. For each model run, locations that contribute to 90% of the sediment loading are identified and those locations that appear in this set in most of the 10,000 model runs are identified as the sources that are most likely to contribute to most of the sediment delivered to the watershed outlet. Because the underlying model is quite simple and strongly anchored by reliable information on soil erosion, topography, and sediment load, we believe that the ensemble of simulation outputs provides a useful basis for identifying the dominant sediment sources in the watershed.

A new approach of using multiple composite fingerprints to apportion sediment sources

USDA-ARS?s Scientific Manuscript database

Sediment source fingerprinting provides an essential means for estimating sediment source contributions, which are needed not only for soil conservation planning but also for erosion model evaluation and refinement. A single optimum composite fingerprint has been widely used in the literature to es...

Historical record of lead accumulation and source in the tidal flat of Haizhou Bay, Yellow Sea: Insights from lead isotopes.

PubMed

Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang

2016-05-15

In order to investigate the historical records of lead contamination and source in coastal region of Haizhou Bay, Yellow Sea, a sediment core was collected from tidal flat, dated by (210)Pb and (137)Cs. Lead and its stable isotopic ratios were determined. The profiles of enrichment factor (EF) and Pb isotope ratios showed increasing trend upward throughout the core, correlating closely with the experience of a rapid economic and industrial development of the catchment. According to Pb isotopic ratios, coal combustion emission mainly contributed to the Pb burden in sediments. Based on end-member model, coal combustion emission dominated anthropogenic Pb sources in recent decades contributing from 48% to 67% in sediment. And the contribution of leaded gasoline was lower than 20%. A stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined recently, with the phase-out of leaded gasoline in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimation of Sediment Sources Using Selected Chemical Tracers in the Perry Lake and Lake Wabaunsee Basins, Northeast Kansas

USGS Publications Warehouse

Juracek, Kyle E.; Ziegler, Andrew C.

2007-01-01

In Kansas and nationally, stream and lake sediment is a primary concern as related to several important issues including water quality and reservoir water-storage capacity. The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. To investigate sources of sediment within the Perry Lake and Lake Wabaunsee Basins of northeast Kansas, representative samples of channel-bank sources, surface-soil sources (cropland and grassland), and reservoir bottom sediment were collected, analyzed, and compared. Subbasins sampled within the Perry Lake Basin included Atchison County Lake, Banner Creek Reservoir, Gregg Creek, Mission Lake, and Walnut Creek. The samples were sieved to isolate the less than 63-micron fraction (that is, the silt and clay) and analyzed for selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, and the radionuclide cesium-137 (137Cs). To determine which of the 30 constituents provided the best ability to discriminate between channel-bank and surface-soil sources in the two basins, four selection criteria were used. To be selected, it was required that the candidate constituent (1) was detectable, (2) had concentrations or activities that varied substantially and consistently between the sources, (3) had concentration or activity ranges that did not overlap between the sources, and (4) had concentration or activity differences between the sources that were statistically significant. On the basis of the four selection criteria, total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and 137Cs were selected. Of the four selected constituents, 137Cs likely is the most reliable indicator of sediment source because it is known to be conservative in the environment. Trace elements were not selected because concentrations in the channel-bank and surface-soil sources generally were similar or did not vary in a consistent manner. To further account for differences in particle-size composition between the sources and the reservoir bottom sediment prior to the sediment-source estimations, constituent ratio and clay-normalization techniques were used. Computed ratios included the ratio of TOC to TN, TOC to TP, and TN to TP. Constituent concentrations (TN, TP, TOC) and activities (137Cs) were normalized by dividing by the percentage of clay. Thus, the sediment-source estimations involved the use of seven sediment-source indicators (that is, three constituent ratios and the clay-normalized concentration or activity for four constituents). Sediment-source estimation for each reservoir was based on a comparison between the reservoir bottom sediment and the end member channel-bank and surface-soil sources. Within the Perry Lake Basin, the seven-indicator consensus indicated that both channel-bank and surface-soil sources were important contributors of the sediment deposited in Atchison County Lake and Banner Creek Reservoir, whereas channel-bank sources were the dominant source of sediment for Mission Lake. On the sole basis of 137Cs activity, surface-soil sources contributed the most sediment to Atchison County Lake, and channel-bank sources contributed the most sediment to Banner Creek Reservoir and Mission Lake. For Perry Lake, both the seven-indicator consensus and 137Cs indicated that channel-bank sources were dominant and that channel-bank sources increased in importance with distance downstream in the Perry Lake Basin. For Lake Wabaunsee, the seven-indicator consensus and 137Cs indicated that both channel-bank and surface-soil sources were important. Given that the relative contribution of sediment from channel-bank and surface-soil sources can vary within and between basins and over time, basin-specific strategies for sediment management and monitoring are appropriate.

A fingerprinting mixing model approach to generate uniformly representative solutions for distributed contributions of sediment sources in a Pyrenean drainage basin

NASA Astrophysics Data System (ADS)

Palazón, Leticia; Gaspar, Leticia; Latorre, Borja; Blake, Will; Navas, Ana

2014-05-01

Spanish Pyrenean reservoirs are under pressure from high sediment yields in contributing catchments. Sediment fingerprinting approaches offer potential to quantify the contribution of different sediment sources, evaluate catchment erosion dynamics and develop management plans to tackle the reservoir siltation problems. The drainage basin of the Barasona reservoir (1509 km2), located in the Central Spanish Pyrenees, is an alpine-prealpine agroforest basin supplying sediments to the reservoir at an annual rate of around 350 t km-2 with implications for reservoir longevity. The climate is mountain type, wet and cold, with both Atlantic and Mediterranean influences. Steep slopes and the presence of deep and narrow gorges favour rapid runoff and large floods. The ability of geochemical fingerprint properties to discriminate between the sediment sources was investigated by conducting the nonparametric Kruskal-Wallis H-test and a stepwise discriminant function analysis (minimization of Wilk's lambda). This standard procedure selects potential fingerprinting properties as optimum composite fingerprint to characterize and discriminate between sediment sources to the reservoir. Then the contribution of each potential sediment source was assessed by applying a Monte Carlo mixing model to obtain source proportions for the Barasona reservoir sediment samples. The Monte Carlo mixing model was written in C programming language and designed to deliver a user-defined number possible solutions. A Combinatorial Principals method was used to identify the most probable solution with associated uncertainty based on source variability. The unique solution for each sample was characterized by the mean value and the standard deviation of the generated solutions and the lower goodness of fit value applied. This method is argued to guarantee a similar set of representative solutions in all unmixing cases based on likelihood of occurrence. Soil samples for the different potential sediment sources of the drainage basin were compared with samples from the reservoir using a range of different fingerprinting properties (i.e. mass activities of environmental radionuclides, elemental composition and magnetic susceptibility) analyzed in the < 63 μm sediment fraction. In this case, the 100 best results from 106 generated iterations were selected obtaining a goodness of fit higher than 0.76. The preliminary results using this new data processing methodology for samples collected in the reservoir allowed us to identify cultivated fields and badlands as main potential sources of sediments to the reservoir. These findings support the appropriate use of the fingerprinting methodology in a Spanish Pyrenees basin, which will enable us to better understand the basin sediment production of the Barasona reservoir.

Streambank alluvial unit contributions to suspended sediment and total phosphorus loads, Walnut Creek, Iowa, USA

USDA-ARS?s Scientific Manuscript database

Streambank erosion may represent a significant source of sediment and P to overall watershed loads, however, watershed-scale quantification of contributions are rare. In addition, streambanks are often comprised of highly-variable stratigraphic source materials (e.g., alluvial deposits), which may d...

Identifying sediment sources in the sediment TMDL process

USGS Publications Warehouse

Gellis, Allen C.; Fitzpatrick, Faith A.; Schubauer-Berigan, Joseph P.; Landy, R.B.; Gorman Sanisaca, Lillian E.

2015-01-01

Sediment is an important pollutant contributing to aquatic-habitat degradation in many waterways of the United States. This paper discusses the application of sediment budgets in conjunction with sediment fingerprinting as tools to determine the sources of sediment in impaired waterways. These approaches complement monitoring, assessment, and modeling of sediment erosion, transport, and storage in watersheds. Combining the sediment fingerprinting and sediment budget approaches can help determine specific adaptive management plans and techniques applied to targeting hot spots or areas of high erosion.

Targeting sediment management strategies using sediment quantification and fingerprinting methods

NASA Astrophysics Data System (ADS)

Sherriff, Sophie; Rowan, John; Fenton, Owen; Jordan, Phil; hUallacháin, Daire Ó.

2016-04-01

Cost-effective sediment management is required to reduce excessive delivery of fine sediment due to intensive land uses such as agriculture, resulting in the degradation of aquatic ecosystems. Prioritising measures to mitigate dominant sediment sources is, however, challenging, as sediment loss risk is spatially and temporally variable between and within catchments. Fluctuations in sediment supply from potential sources result from variations in land uses resulting in increased erodibility where ground cover is low (e.g., cultivated, poached and compacted soils), and physical catchment characteristics controlling hydrological connectivity and transport pathways (surface and/or sub-surface). Sediment fingerprinting is an evidence-based management tool to identify sources of in-stream sediments at the catchment scale. Potential sediment sources are related to a river sediment sample, comprising a mixture of source sediments, using natural physico-chemical characteristics (or 'tracers'), and contributions are statistically un-mixed. Suspended sediment data were collected over two years at the outlet of three intensive agricultural catchments (approximately 10 km2) in Ireland. Dominant catchment characteristics were grassland on poorly-drained soils, arable on well-drained soils and arable on moderately-drained soils. High-resolution (10-min) calibrated turbidity-based suspended sediment and discharge data were combined to quantify yield. In-stream sediment samples (for fingerprinting analysis) were collected at six to twelve week intervals, using time-integrated sediment samplers. Potential sources, including stream channel banks, ditches, arable and grassland field topsoils, damaged road verges and tracks were sampled, oven-dried (<40oC) and sieved (125 microns). Soil and sediment samples were analysed for mineral magnetics, geochemistry and radionuclide tracers, particle size distribution and soil organic carbon. Tracer data were corrected to account for particle size and organic matter selectivity processes. Contributions from potential sources type groups (channel - ditches and stream banks, roads - road verges and tracks, fields - grassland and arable topsoils) were statistically un-mixed using FR2000, an uncertainty-inclusive algorithm, and combined with sediment yield data. Results showed sediment contributions from channel, field and road groups were 70%, 25% and 5% in the poorly-drained catchment, 59%, 22% and 19% in the well-drained catchment, and 17%, 74% and 9% in the moderately-drained catchment. Higher channel contributions in the poorly-drained catchment were attributed to bank erosion accelerated by the rapid diversion of surface runoff into channels, facilitated by surface and sub-surface artificial drainage networks, and bank seepage from lateral pressure gradients due to confined groundwater. Despite the greatest proportion of arable soils in the well-drained catchment, this source was frequently hydrologically disconnected as well-drained soils largely infiltrated rainfall and prevented surface soil erosion. Periods of high and intense rainfall were associated with greater proportions of field losses in the well-drained catchment likely due to infiltration exceeding the saturated hydraulic conductivity of soils and establishment of surface hydrological connectivity. Losses from field topsoils dominated in the moderately-drained catchment as antecedent soil wetness maintained surface flow pathways and coincided with low groundcover on arable soils. For cost-effective management of sediment pressures to aquatic ecosystems, catchment specific variations in sediment sources must be considered.

First post-fire flush in a Mediterranean temporary stream: source ascription in bed sediments

NASA Astrophysics Data System (ADS)

Estrany Bertos, Joan; García-Comendador, Julián; Fortesa, Josep; Calsamiglia, Aleix; Garcias, Francesca

2017-04-01

First flushes can be of great importance for suspended-sediment transport in fluvial systems of drylands, being temporary streams a characteristic feature of Mediterranean basins. After a wildfire, storm flows may enhance runoff delivery to channels and then increasing the first-flush effect. 137Cs and 210Pbex were used as tracers for recognizing the first post-fire flush effect in the source ascription of bed sediments temporarily stored in a Mediterranean temporary stream severely affected by a wildfire. Thirty potential sediment source samples were collected along the main stem of a catchment located in Mallorca (Spain) during a field campaign developed some weeks after the wildfire. The sample collection was designed considering the wildfire affection, and also distinguishing between soil surface and channel bank. To quantify the relative source contribution to the bed sediment temporarily stored, five sediment samples -deposited during the first storm occurred three months after the wildfire- were collected into the bed stream of the main channel. The 137Cs and 210Pbex concentrations were measured by gamma spectrometry. Then, a linear mixing model was used to establish the relative contribution of each source type to the bed sediments discerning between the most upstream and the downstream parts of the catchment. Post-fire first-flush effect was generated by a torrential event with a suspended-sediment concentration peak ca. 33,618 mg L-1, although transmission losses under a very low runoff coefficient (1%) promoted sediment deposition. Significant differences were observed in fallout radionuclide concentrations between burned surface soil and channel bank samples (p < 0.05), as well as between burned and unburned sources at the downstream part of the catchment (p < 0.01). The radioactivity concentrations in bed sediments samples were statistically similar (p > 0.05). Source ascription in bed sediments in the middle stream shows that 67% was generated in burned hillslopes, reaching 75% in the downstream part because downstream propagation of the sediment derived from the burned area. Bed sediments were mostly generated in burned hillslopes because of the fire effects on soils and sediment availability, high intensity rainfall and limited contribution of channel banks that are fixed by dry-stone walls. This hydro-sedimentary response indicates an association between driven sediment transport factors and sediment availability, generating an effective slope-to-channel sediment connectivity. Long-term sediment sources monitoring will elucidate if the most effective period of the window of disturbance at catchment scale is further extended (i.e., ≈5 years).

Source apportionment of PAH in Hamilton Harbour suspended sediments: comparison of two factor analysis methods.

PubMed

Sofowote, Uwayemi M; McCarry, Brian E; Marvin, Christopher H

2008-08-15

A total of 26 suspended sediment samples collected over a 5-year period in Hamilton Harbour, Ontario, Canada and surrounding creeks were analyzed for a suite of polycyclic aromatic hydrocarbons and sulfur heterocycles. Hamilton Harbour sediments contain relatively high levels of polycyclic aromatic compounds and heavy metals due to emissions from industrial and mobile sources. Two receptor modeling methods using factor analyses were compared to determine the profiles and relative contributions of pollution sources to the harbor; these methods are principal component analyses (PCA) with multiple linear regression analysis (MLR) and positive matrix factorization (PMF). Both methods identified four factors and gave excellent correlation coefficients between predicted and measured levels of 25 aromatic compounds; both methods predicted similar contributions from coal tar/coal combustion sources to the harbor (19 and 26%, respectively). One PCA factor was identified as contributions from vehicular emissions (61%); PMF was able to differentiate vehicular emissions into two factors, one attributed to gasoline emissions sources (28%) and the other to diesel emissions sources (24%). Overall, PMF afforded better source identification than PCA with MLR. This work constitutes one of the few examples of the application of PMF to the source apportionment of sediments; the addition of sulfur heterocycles to the analyte list greatly aided in the source identification process.

Quantifying sediment provenance using multiple composite fingerprints in a small watershed in Oklahoma

USDA-ARS?s Scientific Manuscript database

Quantitative information on sediment provenance is badly needed for calibration and validation of process-based soil erosion models. However, sediment source data are rather limited due to difficulties in direct measurement of various source contributions at a watershed scale. The objectives are t...

Fingerprinting of bed sediment in the Tay Estuary, Scotland: an environmental magnetism approach

NASA Astrophysics Data System (ADS)

Jenkins, Pierre A.; Duck, Rob W.; Rowan, John S.; Walden, John

Sediment fingerprinting is commonly used for sediment provenance studies in lakes, rivers and reservoirs and on hillslopes and floodplains. This investigation explores the mixing of terrestrial and marine-derived sediment in the Tay Estuary, Scotland, using mineral magnetic attributes for fingerprinting. Samples representative of the estuary sediments and of four sources (end-members) were subjected to a suite of magnetic susceptibility and remanence measurements. Sediment samples from the beds of the Rivers Tay and Earn represented fluvial inputs while samples from the Angus and Fife coasts represented marine input. Multivariate discriminant and factor analysis showed that the sources could be separated on the basis of six magnetic parameters in a simple multivariate unmixing model to identify source contributions to estuarine bed sediments. Multi-domain magnetite signatures, characteristic of unweathered bedrock, dominate the magnetic measurements. Overall contributions of 3% from the River Earn, 17% from the River Tay, 29% from the Angus coast and 51% from the Fife coast source end-members, demonstrated the present-day regime of marine sediment derivation in the Tay Estuary. However, this conceals considerable spatial variability both along-estuary and in terms of sub-environments, with small-scale variations in sediment provenance reflecting local morphology, particularly areas of channel convergence.

Fine-grained suspended sediment source identification for the Kharaa River basin, northern Mongolia

NASA Astrophysics Data System (ADS)

Rode, Michael; Theuring, Philipp; Collins, Adrian L.

2015-04-01

Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on the water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (<10 microns) sediment in the 15 000 km2 Kharaa River basin in northern Mongolia. Five field sampling campaigns in late summer 2009, and spring and late summer in both 2010 and 2011, were conducted directly after high water flows, to collect an overall total of 900 sediment samples. The work used a statistical approach for sediment source discrimination with geochemical composite fingerprints based on a new Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal-Wallis H-test and Principal Component Analysis. The composite fingerprints were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin) with the pattern generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of riverbank erosion was shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the general applicability and associated uncertainties of an approach for fine-grained sediment source investigation in large scale semi-arid catchments. The combined application of source fingerprinting and catchment modelling approaches can be used to assess whether tracing estimates are credible and in combination such approaches provide a basis for making sediment source apportionment more compelling to catchment stakeholders and managers.

Modeling the source contribution of heavy metals in surficial sediment and analysis of their historical changes in the vertical sediments of a drinking water reservoir

NASA Astrophysics Data System (ADS)

Wang, Guoqiang; A, Yinglan; Jiang, Hong; Fu, Qing; Zheng, Binghui

2015-01-01

Increasing water pollution in developing countries poses a significant threat to environmental health and human welfare. Understanding the spatial distribution and apportioning the sources of pollution are important for the efficient management of water resources. In this study, ten types of heavy metals were detected during 2010-2013 for all ambient samples and point sources samples. A pollution assessment based on the surficial sediment dataset by Enrichment Factor (EF) showed the surficial sediment was moderately contaminated. A comparison of the multivariate approach (principle components analysis/absolute principle component score, PCA/APCS) and the chemical mass balance model (CMB) shows that the identification of sources and calculation of source contribution based on the CMB were more objective and acceptable when source profiles were known and source composition was complex. The results of source apportionment for surficial heavy metals, both from PCA/APCS and CMB model, showed that the natural background (30%) was the most dominant contributor to the surficial heavy metals, followed by mining activities (29%). The contribution percentage of the natural background was negatively related to the degree of contamination. The peak concentrations of many heavy metals (Cu, Ba, Fe, As and Hg) were found in the middle layer of sediment, which is most likely due to the result of development of industry beginning in the 1970s. However, the highest concentration of Pb appeared in the surficial sediment layer, which was most likely due to the sharp increase in the traffic volume. The historical analysis of the sources based on the CMB showed that mining and the chemical industry are stable sources for all of the sections. The comparing of change rates of source contribution versus years indicated that the composition of the materials in estuary site (HF1) is sensitive to the input from the land, whereas center site (HF4) has a buffering effect on the materials from the land through a series of complex movements. These results provide information for the development of improved pollution control strategies for the lakes and reservoirs.

Source apportionment of trace metals in river sediments: A comparison of three methods.

PubMed

Chen, Haiyang; Teng, Yanguo; Li, Jiao; Wu, Jin; Wang, Jinsheng

2016-04-01

Increasing trace metal pollution in river sediment poses a significant threat to watershed ecosystem health. Identifying potential sources of sediment metals and apportioning their contributions are of key importance for proposing prevention and control strategies of river pollution. In this study, three advanced multivariate receptor models, factor analysis with nonnegative constraints (FA-NNC), positive matrix factorization (PMF), and multivariate curve resolution weighted-alternating least-squares (MCR-WALS), were comparatively employed for source apportionment of trace metals in river sediments and applied to the Le'an River, a main tributary of Poyang Lake which is the largest freshwater lake in China. The pollution assessment with contamination factor and geoaccumulation index suggested that the river sediments in Le'an River were contaminated severely by trace metals due to human activities. With the three apportionment tools, similar source profiles of trace metals in sediments were extracted. Especially, the MCR-WALS and PMF models produced essentially the same results. Comparatively speaking, the weighted schemes might give better solutions than the unweighted FA-NNC because the uncertainty information of environmental data was considered by PMF and MCR-WALS. Anthropogenic sources were apportioned as the most important pollution sources influencing the sediment metals in Le'an River with contributions of about 90%. Among them, copper tailings occupied the largest contribution (38.4-42.2%), followed by mining wastewater (29.0-33.5%), and agricultural activities (18.2-18.7%). To protect the ecosystem of Le'an River and Poyang Lake, special attention should be paid to the discharges of mining wastewater and the leachates of copper tailing ponds in that region. Copyright © 2015 Elsevier Ltd. All rights reserved.

δ 13C and δD identification of sources of lipid biomarkers in sediments of Lake Haruna (Japan)

NASA Astrophysics Data System (ADS)

Chikaraishi, Yoshito; Naraoka, Hiroshi

2005-07-01

Organic materials in lacustrine sediments are from multiple terrestrial and aquatic sources. In this study, carbon (δ 13C) and hydrogen isotopic compositions (δD) of phytol, various sterols, and major n-fatty acids in sediments at Lake Haruna, Japan, were determined in their solvent-extractable (free) and saponification-released forms (bound). The δ 13C-δD distributions of these lipid molecules in sediments are compared with those of terrestrial C3 and C4 plants, aquatic C3 plants, and plankton to evaluate their relative contributions. δ 13C-δD of free phytol in sediments is very close to that of phytol in plankton samples, whereas δ 13C-δD of bound phytol in sediments is on a mixing line between terrestrial C3 plant and plankton material. Unlike phytol, no significant δ 13C-δD difference between free and bound forms was found in sterols and n-fatty acids. δ 13C-δD values of algal sterols such as 24-methylcholesta-5,22-dien-3β-ol in sediments are close to those of plankton, whereas δ 13C-δD of multiple-source sterols such as 24-ethylcholest-5-en-3β-ol and of major n-fatty acids such as n-hexadecanoic acid in sediments are between those of terrestrial C3 plants and plankton samples. Thus, δ 13C-δD distributions clearly indicate the specific source contributions of biomarkers preserved in a lacustrine environment. Free phytol and algal sterols can be attributed to phytoplankton, and bound phytol, multiple source sterols, and major n-fatty acids are contributed by both terrestrial C3 plants and phytoplankton.

Investigating the sources of sediment in a Canadian agricultural watershed using a colour-based fingerprinting technique

NASA Astrophysics Data System (ADS)

Barthod, Louise; Lobb, David; Owens, Philip; Martinez-Carreras, Nuria; Koiter, Alexander; Petticrew, Ellen; McCullough, Gregory

2014-05-01

The development of beneficial management practises to minimize adverse impacts of agriculture on soil and water quality requires information on the sources of sediment at the watershed scale. Sediment fingerprinting allows for the determination of sediment sources and apportionment of their contribution within a watershed, using unique physical, radiochemical or biogeochemical properties, or fingerprints, of the potential sediment sources. The use of sediment colour as a fingerprint is an emerging technique that can provide a rapid and inexpensive means of investigating sediment sources. This technique is currently being utilized to determine sediment sources within the South Tobacco Creek Watershed, an agricultural watershed located in the Canadian prairies (south-central Manitoba). Suspended sediment and potential source (topsoil, channel bank and shale bedrock material) samples were collected between 2009 and 2011 at six locations along the main stem of the creek. Sample colour was quantified from diffuse reflectance spectrometry measurements over the visible wavelength range using a spectroradiometer (ASD Field Spec Pro, 400-2500 nm). Sixteen colour coefficients were derived from several colour space models (CIE XYZ, CIE xyY, CIE Lab, CIE Luv, CIE Lch, Landsat RGB, Redness Index). The individual discrimination power of the colour coefficients, after passing several prerequisite tests (e.g., linearly additive behaviour), was assessed using discriminant function analysis. A stepwise discriminant analysis, based on the Wilk's lambda criterion, was then performed in order to determine the best-suited colour coefficient fingerprints which maximized the discrimination between the potential sources. The selected fingerprints classified the source samples in the correct category 86% of the time. The misclassification is due to intra-source variability and source overlap which can lead to higher uncertainty in sediment source apportionment. The selected fingerprints were then included in a Bayesian mixing model using Monte-Carlo simulation (Stable Isotope Analysis in R, SIAR) in order to apportion the contribution of the different sources to the sediment collected at each location. A switch in the dominant sediment source between the headwaters and the outlet of the watershed is observed. Sediment is enriched with shale bedrock and depleted of topsoil sources as the stream crosses and down-cuts through the Manitoba Escarpment. The switch in sources highlights the importance of the sampling location in relation to the scale and geomorphic connectivity of the watershed. Although the results include considerable uncertainty, they are consistent with the findings from a classical fingerprinting approach undertaken in the same watershed (i.e., geochemical and radionuclide fingerprints), and confirm the potential of sediment colour parameters as suitable fingerprints.

Investigating the distribution and sources of organic matter in surface sediment of Coombabah Lake (Australia) using elemental, isotopic and fatty acid biomarkers

NASA Astrophysics Data System (ADS)

Dunn, R. J. K.; Welsh, D. T.; Teasdale, P. R.; Lee, S. Y.; Lemckert, C. J.; Meziane, T.

2008-10-01

Extensive physical and biological measurements were made of the surface sediments within the shallow, semi-urbanised Coombabah Lake in southern Moreton Bay, Australia. Sediment bulk parameters (C/N ratios, δ13C and δ15N) and fatty acid biomarkers were used to determine distributions and sources of organic matter in the intertidal sediments. The determination of organic matter sources within coastal and estuarine settings is important in understanding the roles of organic matter as energy and nutrient sources. Spatial variability of biomarker values within the sediments were interpreted by thematic maps employing the Krigging algorithm. Grain size analysis indicated the lake was dominated by mud (<63 μm) in the southern (landward) and sand (>63 μm) in the northern (seaward) lake regions, respectively. Surface sediment organic C and N values ranged from 0.12% to 1.76% and 0.01% to 0.12% dry weight, respectively, and C/N ratios averaged 16.3±3.19%. Sedimentary δ13C values ranged from -26.1‰ to -20.9‰, with an average value of -23.9±1.0‰. Sedimentary δ15N values ranged from +1.7‰ to +4.8‰, with an average value of +2.8±0.8‰. Bulk sediment parameters suggested that sedimentary organic matter is provided predominantly by allochthonous sources in the form of fringing mangroves. Thirty-nine individual fatty acids were identified using gas chromatography-mass spectrometry. The mean contributions of long chain fatty acids (LCFAs), polyunsaturated fatty acids (PUFAs), saturated fatty acids (SAFAs) and bacterial fatty acids (BAFAs) were, respectively, 13.9±11.4%, 7.6±4.1%, 53.6±8.6% and 18.2±4.6% of the identified fatty acid methyl esters (FAMEs), with BAFAs occurring in all sampled sediments. Fatty acid compositions varied throughout lake sediments, which indicated spatial differences in autochthonous and allochthonous organic matter sources, including terrestrial and planktonic (i.e. zooplankton, diatoms and other algal species) sources. The contribution of organic matter from shoreline mangroves was confirmed by the presence of LCFAs and 18:2 ω6 and 18:3 ω3, which are markers for mangroves in this ecosystem. BAFAs were identified in increased proportions in sediments adjacent to urban developments and dominated by mud. Grain size was identified as a dominant factor in the fatty acid compositions and contributing values to FAME pool. Spatial patterns of C/N ratios, δ13C and δ15N values, and fatty acid biomarker contributions illustrated that there is a greater contribution of autochthonous and labile organic matter to the sedimentary organic matter pool in the northern (marine entrance) sediments compared to the more allochthonous sourced organic matter of the southern region of the lake. This study details the distribution and sources of organic matter within Coombabah Lake and illustrates the usefulness of a multiple biomarker approach in discriminating organic matter sources within estuarine environments.

Transport and sources of sediment in the Missouri River between Garrison Dam and the headwaters of Lake Oahe, North Dakota, May 1988 through April 1991

USGS Publications Warehouse

Berkas, Wayne R.

1995-01-01

Sediment data were collected on and along the Missouri River downstream from Garrison Dam during May 1988, May 1989, and April 1991 to characterize sediment transport in the river. Specific study objectives were to (1) identify erosional and depositional reaches during two steady-state low-flow periods and one steady-state high-flow period; (2) determine if the reaches are consistently eroding or depositing, regardless of streamflow; and (3) determine the sources of suspended sediment in the river. Erosional and depositional reaches differed between the two low-flow periods, indicating that slight changes in the channel configuration between the two periods caused changes in erosional and depositional patterns. Erosional and depositional reaches also differed between the low-flow periods and the high-flow period, indicating that channel changes and increased streamflow velocities affect erosional and depositional reaches. The significant sources of suspended sediment in the Missouri River are the riverbed and riverbanks. The riverbed contributes to the silt and sand load in the river, and the riverbanks contribute to the clay, silt, and sand load. The contribution from tributaries to the suspendedsediment load in the Missouri River usually is small. Occasionally, during low-flow periods on the Missouri River, the Knife River can contribute significantly to the suspended-sediment load in the Missouri River.

Varying sediment sources (Hudson Strait, Cumberland Sound, Baffin Bay) to the NW Labrador Sea slope between and during Heinrich events 0 to 4

USGS Publications Warehouse

Andrews, John T.; Barber, D.C.; Jennings, A.E.; Eberl, D.D.; Maclean, B.; Kirby, M.E.; Stoner, J.S.

2012-01-01

Core HU97048-007PC was recovered from the continental Labrador Sea slope at a water depth of 945 m, 250 km seaward from the mouth of Cumberland Sound, and 400 km north of Hudson Strait. Cumberland Sound is a structural trough partly floored by Cretaceous mudstones and Paleozoic carbonates. The record extends from ∼10 to 58 ka. On-board logging revealed a complex series of lithofacies, including buff-colored detrital carbonate-rich sediments [Heinrich (H)-events] frequently bracketed by black facies. We investigate the provenance of these facies using quantitative X-ray diffraction on drill-core samples from Paleozoic and Cretaceous bedrock from the SE Baffin Island Shelf, and on the < 2-mm sediment fraction in a transect of five cores from Cumberland Sound to the NW Labrador Sea. A sediment unmixing program was used to discriminate between sediment sources, which included dolomite-rich sediments from Baffin Bay, calcite-rich sediments from Hudson Strait and discrete sources from Cumberland Sound. Results indicated that the bulk of the sediment was derived from Cumberland Sound, but Baffin Bay contributed to sediments coeval with H-0 (Younger Dryas), whereas Hudson Strait was the source during H-events 1–4. Contributions from the Cretaceous outcrops within Cumberland Sound bracket H-events, thus both leading and lagging Hudson Strait-sourced H-events.

Carbon-13 natural abundance signatures of long-chain fatty acids to determinate sediment origin: A case study in northeast Austria

NASA Astrophysics Data System (ADS)

Mabit, Lionel; Gibbs, Max; Meusburger, Katrin; Toloza, Arsenio; Resch, Christian; Klik, Andreas; Swales, Andrew; Alewell, Christine

2016-04-01

- Several recently published information from scientific research have highlighted that compound-specific stable isotope (CSSI) signatures of fatty acids (FAs) based on the measurement of carbon-13 natural abundance signatures showed great promises to identify sediment origin. The authors have used this innovative isotopic approach to investigate the sources of sediment in a three hectares Austrian sub-watershed (i.e. Mistelbach). Through a previous study using the Cs-137 technique, Mabit et al. (Geoderma, 2009) reported a local maximum sedimentation rate reaching 20 to 50 t/ha/yr in the lowest part of this watershed. However, this study did not identify the sources. Subsequently, the deposited sediment at its outlet (i.e. the sediment mixture) and representative soil samples from the four main agricultural fields - expected to be the source soils - of the site were investigated. The bulk delta carbon-13 of the samples and two long-chain FAs (i.e. C22:0 and C24:0) allowed the best statistical discrimination. Using two different mixing models (i.e. IsoSource and CSSIAR v1.00) and the organic carbon content of the soil sources and sediment mixture, the contribution of each source has been established. Results suggested that the grassed waterway contributed to at least 50% of the sediment deposited at the watershed outlet. This study, that will require further validation, highlights that CSSI and Cs-137 techniques are complementary as fingerprints and tracers for establishing land sediment redistribution and could provide meaningful information for optimized decision-making by land managers.

Sediment source fingerprinting as an aid to catchment management: A review of the current state of knowledge and a methodological decision-tree for end-users

USGS Publications Warehouse

Collins, A.L; Pulley, S.; Foster, I.D.L; Gellis, Allen; Porto, P.; Horowitz, A.J.

2017-01-01

The growing awareness of the environmental significance of fine-grained sediment fluxes through catchment systems continues to underscore the need for reliable information on the principal sources of this material. Source estimates are difficult to obtain using traditional monitoring techniques, but sediment source fingerprinting or tracing procedures, have emerged as a potentially valuable alternative. Despite the rapidly increasing numbers of studies reporting the use of sediment source fingerprinting, several key challenges and uncertainties continue to hamper consensus among the international scientific community on key components of the existing methodological procedures. Accordingly, this contribution reviews and presents recent developments for several key aspects of fingerprinting, namely: sediment source classification, catchment source and target sediment sampling, tracer selection, grain size issues, tracer conservatism, source apportionment modelling, and assessment of source predictions using artificial mixtures. Finally, a decision-tree representing the current state of knowledge is presented, to guide end-users in applying the fingerprinting approach.

Distribution and origins of n-alkanes, hopanes, and steranes in rivers and marine sediments from Southwest Caspian coast, Iran: implications for identifying petroleum hydrocarbon inputs.

PubMed

Shirneshan, Golshan; Bakhtiari, Alireza Riyahi; Memariani, Mahmoud

2016-09-01

The occurrence of n-alkanes and biomarkers (hopane and sterane) in surface sediments from Southwestern coasts of Caspian Sea and 28 rivers arriving to this lake, determined with a gas chromatography-mass spectrometry method, was used to assess the impacts of anthropogenic activities in the studied area. The concentrations of total n-alkanes (Σ21 n-alkane) in costal and riverine sediments varied from 249.2 to 3899.5 and 56 to 1622.4 μg g(-1), respectively. An evaluation of the source diagnostic indices indicated that petroleum related sources (petrogenic) were mainly contributed to n-alkanes in costal and most riverine sediments. Only the hydrocarbons in sediment of 3 rivers were found to be mainly of biogenic origin. Principal component analysis using hopane diagnostic ratios in costal and riverine sediments, and Anzali, Turkmenistan, and Azerbaijan oils were used to identify the sources of hydrocarbons in sediments. It was indicated that the anthropogenic contributions in most of the costal sediment samples are dominated with inputs of oil spills from Turkmenistan and Azerbaijan countries.

Reconstruction of historical lead contamination and sources in Lake Hailing, Eastern China: a Pb isotope study.

PubMed

Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang; Jiang, Tingchen

2016-05-01

The history records of lead and its stable isotopic ratios were determined in a sediment core to receive anthropogenic impacts on the Lake Hailing in eastern China. The sediment core was dated based on (210)Pb, (137)Cs, and (239+240)Pu. The historical changes of Pb/Al and Pb isotope ratios showed increasing trend upward throughout the core, suggesting changes in energy usage and correlating closely with the experience of a rapid economic and industrial development of the catchment, Linyi City, in eastern China. Based on the mixing end member model of Pb isotope ratios, coal combustion emission dominated anthropogenic Pb sources in the half part of the century contributing 13 to 43 % of total Pb in sediment. Moreover, contributions of chemical and organic fertilizer were 1-13 and 5-14 %, respectively. In contrast, the contribution of leaded gasoline was low than 8 %. The results indicated that historical records of Pb contamination predominantly sourced from coal combustion and chemical and organic fertilizer in the catchment. In addition, an increase of coal combustion source and fertilizers was found throughout the sediment core, whereas the contribution of leaded gasoline had declined after 2000s, which is attributed to the phaseout of leaded gasoline in China.

Biomarkers in sedimentary sequences: Indicators to track sediment sources over decadal timescales

NASA Astrophysics Data System (ADS)

Chen, F. X.; Fang, N. F.; Wang, Y. X.; Tong, L. S.; Shi, Z. H.

2017-02-01

Long-term sedimentary sequence research can reveal how human activities and climate interact to affect catchment vegetation, flooding, soil erosion, and sediment sources. In this study, a biomarker sediment fingerprinting technique based on n-alkanes was used to identify long timescale (decadal) sediment sources in a small agricultural catchment. However, the highly saline carbonate environment and bacterial and algal activities elevated the levels of even-chain n-alkanes in the sediments, leading to an obvious even-over-odd predominance of short and middle components (C15-C26). Therefore, by analyzing three odd, long-chain n-alkanes (C27, C29 and C31) in 27 source samples from cropland, gully, and steep slope areas and one sediment sequence (one cultivated horizon and 47 flood couplets), a composite fingerprinting method and genetic algorithm optimization were applied to find the optimal source contributions to sediments. The biomarker fingerprinting results demonstrated that the primary sediment source is gullies, followed by cropland and steep slope areas. The average median source contributions associated with 47 flood couples collected from sediment core samples ranged from 0 ± 0.1% to 91.9 ± 0.4% with an average of 45.0% for gullies, 0 ± 0.4% to 95.6 ± 1.6% with an average of 38.2% for cropland, and 0 ± 2.1% to 60.7 ± 0.4% with an average of 16.8% for steep slopes. However, because farmers were highly motivated to manage the cropland after the 1980s, over half the sediments were derived from cropland in the 1980s. Biomarkers have significant advantages in the identification of sediments derived from different landscape units (e.g., gully and steep slope areas), and n-alkanes have considerable potential in high-resolution research of environmental change based on soil erosion in the hilly Loess Plateau region.

Design, implementation, and initial results from a water-quality monitoring network for Atlanta, Georgia, USA

USGS Publications Warehouse

Horowitz, A.J.; Elrick, K.A.; Smith, J.J.

2005-01-01

In cooperation with the City of Atlanta, Georgia, the US Geological Survey has designed and implemented a water-quantity and quality monitoring network that measures a variety of biological and chemical constituents in water and suspended sediment. The network consists of 20 long-term monitoring sites and is intended to assess water-quality trends in response to planned infrastructural improvements. Initial results from the network indicate that nonpoint-source contributions may be more significant than point-source contributions for selected sediment associated trace elements and nutrients. There also are indications of short-term discontinuous point-source contributions of these same constituents during baseflow.

Late Eocene to present isotopic (Sr-Nd-Pb) and geochemical evolution of sediments from the Lomonosov Ridge, Arctic Ocean: Implications for continental sources and linkage with the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Stevenson, Ross; Poirier, André; Véron, Alain; Carignan, Jean; Hillaire-Marcel, Claude

2015-09-01

New geochemical and isotopic (Sr, Nd, Pb) data are presented for a composite sedimentary record encompassing the past 50 Ma of history of sedimentation on the Lomonosov Ridge in the Arctic Ocean. The sampled sediments encompass the transition of the Arctic basin from an enclosed anoxic basin to an open and ventilated oxidized ocean basin. The transition from anoxic basin to open ventilated ocean is accompanied by at least three geochemical and isotopic shifts and an increase in elements (e.g., K/Al) controlled by detrital minerals highlighting significant changes in sediment types and sources. The isotopic compositions of the sediments prior to ventilation are more variable but indicate a predominance of older crustal contributions consistent with sources from the Canadian Shield. Following ventilation, the isotopic compositions are more stable and indicate an increased contribution from younger material consistent with Eurasian and Pan-African crustal sources. The waxing and waning of these sources in conjunction with the passage of water through Fram Strait underlines the importance of the exchange of water mass between the Arctic and North Atlantic Oceans.

Distributions of clay minerals in surface sediments of the middle Bay of Bengal: Source and transport pattern

NASA Astrophysics Data System (ADS)

Li, Jingrui; Liu, Shengfa; Shi, Xuefa; Feng, Xiuli; Fang, Xisheng; Cao, Peng; Sun, Xingquan; Wenxing, Ye; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2017-08-01

The clay mineral contents in 110 surface sediment samples collected from the middle of the Bay of Bengal were analyzed by X-ray diffraction (XRD) to investigate the provenance and transport patterns. The illite content was highest, followed by chlorite, kaolinite and then smectite, with average weight percent distributions of 52%, 22%, 14% and 12%, respectively. Illite and chlorite had similar distribution pattern, with higher contents in the northern and central areas and lower contents in the southern area, whereas smectite showed the opposite distribution pattern. Kaolinite show no obvious higher or lower areas and the southern ;belt; was one of the highest content areas. Based on the spatial distribution characteristics and cluster analysis results, the study area can be classified into two provinces. Province I covers the southwestern area and contains high concentrations of illite and smectite sediments. Province II covers most sites and is also characterized by high concentrations of illite, but the weight percent of smectite is only half of that of province I. According to a quantitative estimate using end-member clay minerals contents, the relative contributions from the Himalayan source and the Indian source are 63% and 37% on average, respectively. Integrative analysis indicates that the hydrodynamic environment in the study area, especially the turbidity and surface monsoonal circulation, plays an important role in the spatial distribution and dispersal of the clay fraction in the sediments. The sediments in province I are mainly from the Indian source transported by the East Indian Coastal Current (EICC) and the surface monsoon circulation with minor contributions from the Himalayan source while the sediments in province II are mainly from the Himalayan source transported by turbidity and surface monsoonal circulation with little contribution from Indian river materials.

Using geochemical fingerprinting to track the dispersion of radioactive contamination along coastal catchments of the Fukushima Prefecture

NASA Astrophysics Data System (ADS)

Lepage, Hugo; Laceby, J. Patrick; Evrard, Olivier; Onda, Yuichi; Caroline, Chartin; Lefèvre, Irène; Bonté, Philippe; Ayrault, Sophie

2015-04-01

Several coastal catchments located in the vicinity of the Fukushima Dai-Ichi Power Plant were impacted contaminated fallout in March 2011. Following the accident, typhoons and snowmelt runoff events transfer radiocesium contamination through the coastal floodplains and ultimately to the Pacific Ocean. Therefore it is important to understand the location and relative contribution of different erosion sources in order to manage radiocesium transfer within these coastal catchments and the cumulative export of radiocesium to the Pacific Ocean. Here we present a sediment fingerprinting approach to determine the relative contributions of sediment from different soil types to sediment transported throughout two coastal riverine systems. The sediment fingerprinting technique presented utilizes differences in the elemental geochemistry of the distinct soil types to determine their relative contributions to sediment sampled in riverine systems. This research is important as it furthers our understanding of dominant erosion sources in the region which will help with ongoing decontamination and monitoring efforts pertaining to the management of fallout radiocesium migration in the region.

Identification of in-sewer sources of organic solids contributing to combined sewer overflows.

PubMed

Ahyerre, M; Chebbo, G

2002-09-01

Previous research has shown that combined sewer systems are the main source of particle and organic pollution during rainfall events contributing to combined sewer overflow. The aim of this article is to identify in an urban catchment area called "Le Marais", in the center of Paris, the types of sediments that are eroded and contribute to the pollution of combined sewer overflow. Three sediment types are considered: granular material found in the inverts of pipes, organic biofilms and organic sediment at the water bed interface, identified as an immobile layer in the "Le Marais" catchment area. The method used consist, firstly, of sampling and assessing the organic pollutant loads and metallic loads of the particles in each type of sediment. Then, the mass of each type of sediment is assessed. The mass and the characteristics of each type of sediment is finally compared to the mass and characteristics of the particles eroded in the catchment area, estimated by mass balances, in order to find the source of eroded particles. The only identified type of deposit that can contribute to combined sewer overflows is the organic layer. Indeed, the solids of this layer have mean and metallic loads that are of the same order of magnitude as the eroded particles. Moreover, the mass of the organic layer considered over different time scales is of the same order of magnitude as the eroded masses during rainfall events and an erosion experiment showed that the organic layer is actually eroded.

Fingerprinting the main erosion processes delivering sediment to hillside reservoirs: Case of Kamech catchment in Cape Bon, Tunisia

NASA Astrophysics Data System (ADS)

Ben Slimane, A.; Raclot, D.; Evrard, O.; Sanaa, M.; Lefèvre, I.; Ahmadi, M.; Le Bissonnais, Y.

2011-12-01

About 74% of agricultural soils are affected by water erosion in Tunisia. This intense soil degradation threatens the sustainability of food production in the country. It also leads to the siltation of the numerous hillslide reservoirs that were constructed in the 1990s to protect downstream villages against floods and provide a source of water in cultivated areas. Very dense gully systems are observed in Tunisian agricultural land and in other Mediterranean regions, but their contribution to contemporary sediment supply to hillside reservoirs has not been quantified yet. Still, there is a need to quantify the sediment sources in this region in order to guide the implementation of erosion control measures. Sediment can be supplied by gully systems but it can also be provided by erosion of the superficial layer of cultivated soil. We propose a methodology to estimate the relative contribution of gully erosion vs. interrill erosion to the sediment accumulated in hillside reservoirs. This work was conducted in a pilot catchment (i.e., Kamech catchment, 263ha, Cape Bon, Tunisia) to define guidelines on the number and the location of sediment core samples to collect in the reservoirs, in order to provide relevant information on the evolution of sediment sources throughout the last two decades. Once validated, this methodology will be applied to other catchments of the Tunisian Ridge. We applied the sediment fingerprinting method, which consists in measuring conservative and stable properties in both sources and sinks of sediment to outline their origin. Sampling efforts were concentrated on the field surface (cropland and grassland), gullies and channel banks. Thirteen sediment cores were collected along an upstream-downstream transect across Kamech hillside reservoir, in order to estimate the contribution of each potential sediment source to the material accumulated at the outlet, and to investigate the potential spatial differences of sediment origin across the reservoir. Concentration in two types of tracers (i.e., radionuclides and organic matter) was analyzed in all samples to provide potential fingerprinting properties, and a Monte Carlo mixing model was applied. Among the 11 potential tracers, 137Cs, total nitrogen and total organic carbon were selected. Application of the mixing model outlined that a mean homogenized sample provided similar information on the sediment origin as the analysis of all successive sediment layers observed in the core. We subsequently focused on the interpretation of the results obtained for those "mean" homogenised core samples. Those results showed that the dominant sources varied along the reservoir transect. However, the overall dominant source of sediment was interrill erosion. Soil conservation measures need therefore to be applied on cultivated land of Kamech catchment to limit siltation.

Sediment source fingerprinting as an aid to catchment management: A review of the current state of knowledge and a methodological decision-tree for end-users.

PubMed

Collins, A L; Pulley, S; Foster, I D L; Gellis, A; Porto, P; Horowitz, A J

2017-06-01

The growing awareness of the environmental significance of fine-grained sediment fluxes through catchment systems continues to underscore the need for reliable information on the principal sources of this material. Source estimates are difficult to obtain using traditional monitoring techniques, but sediment source fingerprinting or tracing procedures, have emerged as a potentially valuable alternative. Despite the rapidly increasing numbers of studies reporting the use of sediment source fingerprinting, several key challenges and uncertainties continue to hamper consensus among the international scientific community on key components of the existing methodological procedures. Accordingly, this contribution reviews and presents recent developments for several key aspects of fingerprinting, namely: sediment source classification, catchment source and target sediment sampling, tracer selection, grain size issues, tracer conservatism, source apportionment modelling, and assessment of source predictions using artificial mixtures. Finally, a decision-tree representing the current state of knowledge is presented, to guide end-users in applying the fingerprinting approach. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

A sediment budget from a glaciated catchment: reconciling subglacial and periglacial erosion on short timescales

NASA Astrophysics Data System (ADS)

Delaney, Ian; Gindraux, Saskia; Weidmann, Yvo; Bauder, Andreas

2017-04-01

Glaciated catchments are known to expel great amounts of sediment, particularly during periods of climatic perturbation. Sediment in these catchments either originates subglacially, where it is eroded by pressurized water below the glacier, or from periglacial areas, which are commonly comprised of easily erodible, unconsolidated material no longer buttressed and held in place by ice. To better forecast sediment dynamics and erosion rates in to the future, contributions of subglacial and periglacial sediment must be quantified, and the processes controlling erosion in these respective sources described. To determine the relative contributions of these sources, we examine the Griesgletscher catchment in the Swiss Alps. Its rather simplistic geometry, as well as, the presence of a proglacial reservoir that serves as a sediment trap, provides an unusually constrained environment to directly measure sediment sources and sinks in the catchment. Subtraction of three digital elevation models created from structure-from-motion and photogrammetric techniques over a one year period, from October 2015 to October 2016, were used to measured sediment flux from the proglacial area. Furthermore, comparison of bathymetries collected from the proglacial reservoir in fall of 2015 and 2016 determined total sediment flux from the entire catchment over this 10 km2time period. Data from a turbidity meter, installed below the reservoir outflow, suggest that negligible amounts of sediment leave the reservoir. Thus comparison of reservoir bathymetry and sediment fluxes from the proglacial area give estimates of the relative contribution of proglacial and subglacial sediment erosion to total catchment sedimentation. Analysis of this data suggest that while the proglacial area experiences a greater erosion rate, it is likely more sediment originates subglacially. As proglacial areas are expected to grow in area and partially stabilize, and glacial areas are predicted to shrink and possibly loose erosive capacity, these competing processes must be reconciled.

Quantifying the origin of different sediment types in a catchment of the Southern French Alps by combining hydro-sedimentary records and fingerprinting

NASA Astrophysics Data System (ADS)

Evrard, Olivier; Navratil, Oldrich; Ayrault, Sophie; Esteves, Michel; Legout, Cédric; Némery, Julien; Lefèvre, Irène; Bonté, Philippe

2013-04-01

Soil erosion and subsequent sediment supply to rivers are particularly massive and episodic in mountainous environments, such as in the Southern French Alps. Those processes typically lead to an increase in water turbidity and a rapid filling of reservoirs in downstream areas. This situation is particularly problematic in regions where reservoirs are used to provide clear water to hydroelectric power plants. Sediment source areas must first be delineated and sediment fluxes between hillslopes and the river system must be better understood to implement efficient sediment management. We therefore combined traditional monitoring techniques (i.e., installation of river gauges and sediment samplers in several subcatchments) and sediment fingerprinting using elemental geochemistry and fallout radionuclides as potential discriminant properties to quantify the supply of sediment provided by different lithological sources (i.e., black marls, marly limestones, conglomerates, Quaternary deposits) to the River Bléone (905 km²). Those analyses were conducted on different material types collected within the catchment (i.e. suspended and riverbed sediment), and at the catchment outlet (i.e. on a sequence of sections of a 3-m long sediment core). Sediment exports at the river catchment outlet (330±100 t km-2 yr-1) were mainly driven (80%) by the occurrence of widespread rainfall events (long duration, low intensities). In contrast, heavy, local and short duration storms generated high peak discharges and suspended sediment concentrations, but they were restricted to small upstream torrents. Our study (2007-2009) confirmed the important contribution of black marls (up to 70% at the flood scale) to sediment transported in rivers, although this substrate only occupies c. 10% of the total catchment surface. However, the contribution of other lithological sources varied at both intra- and inter-flood scales. Sediment exports generated by local convective storms were dominated by black marls/marly limestones. In contrast, widespread flood events that generate the bulk of annual sediment supply at the outlet were characterized by a more stable lithologic composition and by a larger contribution of limestones, Quaternary deposits and conglomerates, which corroborated the analysis of riverbed sediment. Finally, we found that black marls and marly limestone sources provided the main fraction of sediment analysed throughout the outlet core sequence (40 and 22 %, respectively, for the period 1962-2009). However, we also found evidence for the occurrence of major floods carrying large quantities of sediment originating from Quaternary deposits and conglomerates (25 and 16 %, respectively). The variability of sediment sources throughout the sequence may reflect the spatial variability of rainfall within the catchment, which in turn reflects its origin. This study emphasizes the importance of using archival data to validate the results of sediment fingerprinting studies conducted during short contemporary monitoring programmes.

Differentiating the sources of fine sediment, organic matter and nitrogen in a subtropical Australian catchment.

PubMed

Garzon-Garcia, Alexandra; Laceby, J Patrick; Olley, Jon M; Bunn, Stuart E

2017-01-01

Understanding the sources of sediment, organic matter and nitrogen (N) transferred from terrestrial to aquatic environments is important for managing the deleterious off-site impacts of soil erosion. In particular, investigating the sources of organic matter associated with fine sediment may also provide insight into carbon (C) and N budgets. Accordingly, the main sources of fine sediment, organic matter (indicated by total organic carbon), and N are determined for three nested catchments (2.5km 2 , 75km 2 , and 3076km 2 ) in subtropical Australia. Source samples included subsoil and surface soil, along with C 3 and C 4 vegetation. All samples were analysed for stable isotopes (δ 13 C, δ 15 N) and elemental composition (TOC, TN). A stable isotope mixing model (SIAR) was used to determine relative source contributions for different spatial scales (nested catchments), climatic conditions and flow stages. Subsoil was the main source of fine sediment for all catchments (82%, SD=1.15) and the main N source at smaller scales (55-76%, SD=4.6-10.5), with an exception for the wet year and at the larger catchment, where surface soil was the dominant N source (55-61%, SD=3.6-9.9), though contributions were dependent on flow (59-680m 3 /s). C 3 litter was the main source of organic C export for the two larger catchments (53%, SD=3.8) even though C 4 grasses dominate the vegetation cover in these catchments. The sources of fine sediment, organic matter and N differ in subtropical catchments impacted by erosion, with the majority of C derived from C 3 leaf litter and the majority of N derived from either subsoil or surface soil. Understanding these differences will assist management in reducing sediment, organic matter and N transfers in similar subtropical catchments while providing a quantitative foundation for testing C and N budgets. Copyright © 2016 Elsevier B.V. All rights reserved.

Sediment source apportionment in Laurel Hill Creek, PA, using Bayesian chemical mass balance and isotope fingerprinting

USGS Publications Warehouse

Stewart, Heather; Massoudieh, Arash; Gellis, Allen C.

2015-01-01

A Bayesian chemical mass balance (CMB) approach was used to assess the contribution of potential sources for fluvial samples from Laurel Hill Creek in southwest Pennsylvania. The Bayesian approach provides joint probability density functions of the sources' contributions considering the uncertainties due to source and fluvial sample heterogeneity and measurement error. Both elemental profiles of sources and fluvial samples and 13C and 15N isotopes were used for source apportionment. The sources considered include stream bank erosion, forest, roads and agriculture (pasture and cropland). Agriculture was found to have the largest contribution, followed by stream bank erosion. Also, road erosion was found to have a significant contribution in three of the samples collected during lower-intensity rain events. The source apportionment was performed with and without isotopes. The results were largely consistent; however, the use of isotopes was found to slightly increase the uncertainty in most of the cases. The correlation analysis between the contributions of sources shows strong correlations between stream bank and agriculture, whereas roads and forest seem to be less correlated to other sources. Thus, the method was better able to estimate road and forest contributions independently. The hypothesis that the contributions of sources are not seasonally changing was tested by assuming that all ten fluvial samples had the same source contributions. This hypothesis was rejected, demonstrating a significant seasonal variation in the sources of sediments in the stream.

Estimation of Polychlorinated Biphenyl Sources in Industrial Port Sediments Using a Bayesian Semifactor Model Considering Unidentified Sources.

PubMed

Anezaki, Katsunori; Nakano, Takeshi; Kashiwagi, Nobuhisa

2016-01-19

Using the chemical balance method, and considering the presence of unidentified sources, we estimated the origins of PCB contamination in surface sediments of Muroran Port, Japan. It was assumed that these PCBs originated from four types of Kanechlor products (KC300, KC400, KC500, and KC600), combustion and two kinds of pigments (azo and phthalocyanine). The characteristics of these congener patterns were summarized on the basis of principal component analysis and explanatory variables determined. A Bayesian semifactor model (CMBK2) was applied to the explanatory variables to analyze the sources of PCBs in the sediments. The resulting estimates of the contribution ratio of each kind of sediment indicate that the existence of unidentified sources can be ignored and that the assumed seven sources are adequate to account for the contamination. Within the port, the contribution ratio of KC500 and KC600 (used as paints for ship hulls) was extremely high, but outside the port, the influence of azo pigments was observable to a limited degree. This indicates that environmental PCBs not derived from technical PCBs are present at levels that cannot be ignored.

Reconstructed Sediment Mobilization Processes in a Large Reservoir Using Short Sediment Cores

NASA Astrophysics Data System (ADS)

Cockburn, J.; Feist, S.

2014-12-01

Williston Reservoir in northern British Columbia (56°10'31"N, 124°06'33") was formed when the W.A.C. Bennett Dam was created in the late 1960s, is the largest inland body of water in BC and facilitates hydroelectric power generation. Annually the reservoir level rises and lowers with the hydroelectric dam operation, and this combined with the inputs from several river systems (Upper Peace, Finlay, Parsnip, and several smaller creeks) renews suspended sediment sources. Several short-cores retrieved from shallow bays of the Finlay Basin reveal near-annual sedimentary units and distinct patterns related to both hydroclimate variability and the degree to which the reservoir lowered in a particular year. Thin section and sedimentology from short-cores collected in three bays are used to evaluate sediment mobilization processes. The primary sediment sources in each core location is linked to physical inputs from rivers draining into the bays, aeolian contributions, and reworked shoreline deposits as water levels fluctuate. Despite uniform water level lowering across the reservoir, sediment sequences differed at each site, reflecting the local stream inputs. However, distinct organic-rich units, facilitated correlation across the sites. Notable differences in particle size distributions from each core points to important aeolian derived sediment sources. Using these sedimentary records, we can evaluate the processes that contribute to sediment deposition in the basin. This work will contribute to decisions regarding reservoir water levels to reduce adverse impacts on health, economic activities and recreation in the communities along the shores of the reservoir.

Comparing geological and statistical approaches for element selection in sediment tracing research

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick; McMahon, Joe; Evrard, Olivier; Olley, Jon

2015-04-01

Elevated suspended sediment loads reduce reservoir capacity and significantly increase the cost of operating water treatment infrastructure, making the management of sediment supply to reservoirs of increasingly importance. Sediment fingerprinting techniques can be used to determine the relative contributions of different sources of sediment accumulating in reservoirs. The objective of this research is to compare geological and statistical approaches to element selection for sediment fingerprinting modelling. Time-integrated samplers (n=45) were used to obtain source samples from four major subcatchments flowing into the Baroon Pocket Dam in South East Queensland, Australia. The geochemistry of potential sources were compared to the geochemistry of sediment cores (n=12) sampled in the reservoir. The geochemical approach selected elements for modelling that provided expected, observed and statistical discrimination between sediment sources. Two statistical approaches selected elements for modelling with the Kruskal-Wallis H-test and Discriminatory Function Analysis (DFA). In particular, two different significance levels (0.05 & 0.35) for the DFA were included to investigate the importance of element selection on modelling results. A distribution model determined the relative contributions of different sources to sediment sampled in the Baroon Pocket Dam. Elemental discrimination was expected between one subcatchment (Obi Obi Creek) and the remaining subcatchments (Lexys, Falls and Bridge Creek). Six major elements were expected to provide discrimination. Of these six, only Fe2O3 and SiO2 provided expected, observed and statistical discrimination. Modelling results with this geological approach indicated 36% (+/- 9%) of sediment sampled in the reservoir cores were from mafic-derived sources and 64% (+/- 9%) were from felsic-derived sources. The geological and the first statistical approach (DFA0.05) differed by only 1% (σ 5%) for 5 out of 6 model groupings with only the Lexys Creek modelling results differing significantly (35%). The statistical model with expanded elemental selection (DFA0.35) differed from the geological model by an average of 30% for all 6 models. Elemental selection for sediment fingerprinting therefore has the potential to impact modeling results. Accordingly is important to incorporate both robust geological and statistical approaches when selecting elements for sediment fingerprinting. For the Baroon Pocket Dam, management should focus on reducing the supply of sediments derived from felsic sources in each of the subcatchments.

Novel MixSIAR fingerprint model implementation in a Mediterranean mountain catchment

NASA Astrophysics Data System (ADS)

Lizaga, Ivan; Gaspar, Leticia; Blake, William; Palazón, Leticia; Quijano, Laura; Navas, Ana

2017-04-01

Increased sediment erosion levels can lead to degraded water and food quality, reduced aquatic biodiversity, decrease reservoir capacity and restrict recreational usage but determining soil redistribution and sediment budgets in watersheds is often challenging. One of the methods for making such determinations applies sediment fingerprinting methods by using sediment properties. The fingerprinting procedure tests a range of source material tracer properties to select a subset that can discriminate between the different potential sediment sources. The present study aims to test the feasibility of geochemical and radioisotopic fingerprint properties to apportion sediment sources within the Barués catchment. For this purpose, the new MixSIAR unmixing model was implemented as statistical tool. A total of 98 soil samples from different land cover sources (Mediterranean forest, pine forest scrubland, agricultural and subsoil) were collected in the Barués catchment (23 km2). This new approach divides the catchment into six different sub-catchments to evaluate how the sediment provenance varies along the river and the percentage of its sources and not only the contribution at the end. For this purpose, target sediments were collected at the end of each sub-catchment to introduce the variation along the entire catchment. Geochemistry and radioisotopic activity were analyzed for each sample and introduced as input parameters in the model. Percentage values from the five sources were different along the different subcatchments and the variations of all of them are summarized at the final target sample located at the end of the catchment. This work represents a good approximation to the fine sediment provenance in Mediterranean agricultural catchments and has the potential to be used for water resource control and future soil management. Identifying sediment contribution from different land uses offers considerable potential to prevent environmental degradation and the decrease in food production and quality.

An investigation of upland erosion and sources of fine-sediment using aerial and terrestrial LiDAR, mineralogy, geochemistry, and particle-size, Humbug Creek and Malakoff Diggings State Historic Park, California

NASA Astrophysics Data System (ADS)

Curtis, J.; Alpers, C. N.; Howle, J.; Monohan, C.; Ward, J.; Bailey, T. L.; Walck, C.

2015-12-01

One of the largest hydraulic mines (1.6 km2) is located in California's Sierra Nevada within the Humbug Creek watershed and Malakoff Diggins State Historic Park (MDSHP). Previous work indicates typical annual discharge from Humbug Creek of > 500,000 kg of sediment and > 100 g of mercury. This study uses photogrammetry and repeat high-resolution topographic surveys to quantify erosion rates and geomorphic processes, and sediment "fingerprinting" to quantify contributions of fine-sediment sources. The headwaters of Humbug Creek are underlain by volcanic mudflows, whereas MDSHP's denuded and dissected landscape is composed of weathered auriferous sediments susceptible to chronic rill and gully erosion with block failures and debris flows occurring in more cohesive terrain. Aerial LiDAR (November 2014) was used to create a 1-meter digital elevation model (DEM); photogrammetry will be used to create a pre-1997 DEM from historic aerial photographs. DEM differencing will provide an integrated estimate of long-term erosion averaged over ~20 years in unvegetated areas. Finer-resolution (1-cm) terrestrial LiDAR (T-LiDAR) scans were made in late 2014 at four pit locations and will be repeated in the fall of 2015 and 2016. The T-LiDAR time series will provide annual erosion rates under modern conditions, allowing assessment of relative contributions from shallow surface processes and deeper gravity-driven processes. In 2014‒15 we collected storm runoff and in-situ hillslope samples. Sediment fingerprints (mineralogy, major elements, trace elements, and particle size) for source sediments will be used to assess relative contributions from fine-sediment sources using a statistical mixing model. We will present our approach, preliminary results, and discuss how this study supports selection and implementation of management and remediation strategies to ameliorate the discharge of sediment and mercury and mitigate downstream water-quality impacts.

Diffusive flux of PAHs across sediment-water and water-air interfaces at urban superfund sites.

PubMed

Minick, D James; Anderson, Kim A

2017-09-01

Superfund sites may be a source of polycyclic aromatic hydrocarbons (PAHs) to the surrounding environment. These sites can also act as PAH sinks from present-day anthropogenic activities, especially in urban locations. Understanding PAH transport across environmental compartments helps to define the relative contributions of these sources and is therefore important for informing remedial and management decisions. In the present study, paired passive samplers were co-deployed at sediment-water and water-air interfaces within the Portland Harbor Superfund Site and the McCormick and Baxter Superfund Site. These sites, located along the Willamette River (Portland, OR, USA), have PAH contamination from both legacy and modern sources. Diffusive flux calculations indicate that the Willamette River acts predominantly as a sink for low molecular weight PAHs from both the sediment and the air. The sediment was also predominantly a source of 4- and 5-ring PAHs to the river, and the river was a source of these same PAHs to the air, indicating that legacy pollution may be contributing to PAH exposure for residents of the Portland urban center. At the remediated McCormick and Baxter Superfund Site, flux measurements highlight locations within the sand and rock sediment cap where contaminant breakthrough is occurring. Environ Toxicol Chem 2017;36:2281-2289. © 2017 SETAC. © 2017 SETAC.

Polycyclic aromatic hydrocarbons in ocean sediments from the North Pacific to the Arctic Ocean.

PubMed

Ma, Yuxin; Halsall, Crispin J; Xie, Zhiyong; Koetke, Danijela; Mi, Wenying; Ebinghaus, Ralf; Gao, Guoping

2017-08-01

Eighteen polycyclic aromatic hydrocarbons (PAHs) were measured in surficial sediments along a marine transect from the North Pacific into the Arctic Ocean. The highest average Σ 18 PAHs concentrations were observed along the continental slope of the Canada Basin in the Arctic (68.3 ± 8.5 ng g -1 dw), followed by sediments in the Chukchi Sea shelf (49.7 ± 21.2 ng g -1 dw) and Bering Sea (39.5 ± 11.3 ng g -1 dw), while the Bering Strait (16.8 ± 7.1 ng g -1 dw) and Central Arctic Ocean sediments (13.1 ± 9.6 ng g -1 dw) had relatively lower average concentrations. The use of principal components analysis with multiple linear regression (PCA/MLR) indicated that on average oil related or petrogenic sources contributed ∼42% of the measured PAHs in the sediments and marked by higher concentrations of two methylnaphthalenes over the non-alkylated parent PAH, naphthalene. Wood and coal combustion contributed ∼32%, and high temperature pyrogenic sources contributing ∼26%. Petrogenic sources, such as oil seeps, allochthonous coal and coastally eroded material such as terrigenous sediments particularly affected the Chukchi Sea shelf and slope of the Canada Basin, while biomass and coal combustion sources appeared to have greater influence in the central Arctic Ocean, possibly due to the effects of episodic summertime forest fires. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anthropogenic influence on trace element geochemistry of healing mud (peloid) from Makirina Cove (Croatia)

NASA Astrophysics Data System (ADS)

Miko, S.; Koch, G.; Mesić, S.; Šparica-Miko, M.; Šparica, M.; Čepelak, R.; Bačani, A.; Vreča, P.; Dolenec, T.; Bergant, S.

2008-08-01

Due to their balneotherapeutic features, the organic-rich sediments in Makirina Cove are an important source of healing mud. An environmental geochemistry approach using normalization techniques was applied to evaluate the anthropogenic contribution of trace metals to sediments used as healing mud. Sediment geochemistry was found to be associated with land-use change and storm events, as well as with proximity of a road with heavy traffic in the summer months. Local valley topography preferentially channels lithogenic and pollutant transport to the cove. Concentrations and distribution of trace metals indicate lithogenic (Ni, Cr, Co) and anthropogenic (Pb, Cu, Zn and Se) contributions to the sediments. The calculation of enrichment factors indicates a moderate (EFs between 2-3.5) input of anthropogenic Cu and Pb in surficial sediments to a depth of 10 cm. Patients using the Makirina Cove sediments as healing mud could be to some extent exposed to enhanced uptake of metals from anthropogenic sources via dermal contact.

Characterization and source apportionment of PAHs from a highly urbanized river sediments based on land use analysis.

PubMed

Huang, Yanping; Liu, Min; Wang, Ruiqi; Khan, Saira Khalil; Gao, Dengzhou; Zhang, Yazhou

2017-10-01

The city-scale land use/land cover change derived by urbanization on the fates of PAHs is of great concerns recently. This study evaluated spatiotemporal variations and sources of PAHs from a highly urbanized river sediments in the Huangpu River, Shanghai. Results indicated that the concentrations of PAHs in the sediments varied greatly across locations and seasons. The concentration of Σ 16 PAHs in the dry season were 6 times higher than that in wet season. The mainstream and midstream of the Huangpu River were identified as the hotspots in both dry and wet seasons. However, 4-ring PAH compounds were dominated, contributing 42.41% ± 6.81% and 44.70 ± 7.73% in the dry and wet seasons, respectively. Multivariate statistical and land use analysis suggested that the main sources of PAHs derived from the cultivation, traffic and commercial activities. Buffer radii (<750 m) area with cultivated land, road/street and transportation and commercial and business facilities contributed significantly the PAHs in the sediment of the Huangpu River. Population density was also an important variable regulating the PAHs concentrations less than 750 m in the wet season. Risk assessment results revealed that the PAHs toxicity in the sediments was higher in dry season than in wet season. Overall, severe land use changes caused by rapid urbanization can contribute more amount of PAHs emission and complicated sources of PAHs, thus provide insights into the importance of land use types in indicating PAHs source. Copyright © 2017 Elsevier Ltd. All rights reserved.

Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

PubMed

Mauad, Cristiane R; Wagener, Angela de L R; Massone, Carlos G; Aniceto, Mayara da S; Lazzari, Letícia; Carreira, Renato S; Farias, Cássia de O

2015-02-15

Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnitudes and Sources of Catchment Sediment: When A + B Doesn't Equal C

NASA Astrophysics Data System (ADS)

Simon, A.

2015-12-01

The export of land-based sediments to receiving waters can cause degradation of water quality and habitat, loss of reservoir capacity and damage to reef ecosystems. Predictions of sources and magnitudes generally come from simulations using catchment models that focus on overland flow processes at the expense of gully and channel processes. This is not appropriate for many catchments where recent research has shown that the dominant erosion sources have shifted from the uplands and fields following European Settlement, to the alluvial valleys today. Still, catchment models which fail to adequately address channel and bank processes are still the overwhelming choice by resource agencies to help manage sediment export. These models often utilize measured values of sediment load at the river mouth to "calibrate" the magnitude of loads emanating from uplands and fields. The difference between the sediment load at the mouth and the simulated upland loading is then proportioned to channel sources.Bank erosion from the Burnett River (a "Reef Catchment" in eastern Queensland) was quantified by comparisons of bank-top locations and by numerical modeling using BSTEM. Results show that bank-derived sediment contributes between 44 and 73% of the sediment load being exported to the Coral Sea. In comparison reported results from a catchment model showed bank contributions of 8%. In absolute terms, this is an increase in the reported average, annual rate of bank erosion from 0.175 Mt/y to 2.0 Mt/y.In the Hoteo River, New Zealand, a rural North Island catchment characterized by resistant cohesive sediments, bank erosion was found to contribute at least 48% of the total specific yield of sediment. Combining the bank-derived, fine-grained loads from some of the major tributaries gives a total, average annual loading rate for fine material of about 10,900 t/y for the studied reaches in the Hoteo River System. If the study was extended to include the lower reaches of the main stem channel and other tributary reaches, this percentage would be higher. Similar studies in the United States using combinations of empirical and numerical modeling techniques have also disclosed that bank-derived sediment can be the major source of sediment in many catchments. An approach to improve the accuracy of predictions is proposed.

Determination of sediment provenance by unmixing the mineralogy of source-area sediments: The "SedUnMix" program

USGS Publications Warehouse

Andrews, John T.; Eberl, D.D.

2012-01-01

Along the margins of areas such as Greenland and Baffin Bay, sediment composition reflects a complex mixture of sources associated with the transport of sediment in sea ice, icebergs, melt-water and turbidite plumes. Similar situations arise in many contexts associated with sediment transport and with the mixing of sediments from different source areas. The question is: can contributions from discrete sediment (bedrock) sources be distinguished in a mixed sediment by using mineralogy, and, if so, how accurately? To solve this problem, four end-member source sediments were mixed in various proportions to form eleven artificial mixtures. Two of the end-member sediments are felsic, and the other two have more mafic compositions. End member and mixed sediment mineralogies were measured for the < 2. mm sediment fractions by quantitative X-ray diffraction (qXRD). The proportions of source sediments in the mixtures then were calculated using an Excel macro program named SedUnMix, and the results were evaluated to determine the robustness of the algorithm. The program permits the unmixing of up to six end members, each of which can be represented by up to 5 alternative compositions, so as to better simulate variability within each source region. The results indicate that we can track the relative percentages of the four end members in the mixtures. We recommend, prior to applying the technique to down-core or to other provenance problems, that a suite of known, artificial mixtures of sediments from probable source areas be prepared, scanned, analyzed for quantitative mineralogy, and then analyzed by SedUnMix to check the sensitivity of the method for each specific unmixing problem. ?? 2011 Elsevier B.V..

Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

PubMed

Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

2016-09-15

To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Phase I Source Investigation, Heckathorn Superfund Site, Richmond, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohn, Nancy P; Evans, Nathan R

This report represents Phase I of a multi-phase approach to a source investigation of DDT at the Heckathorn Superfund Site, Richmond, California, the former site of a pesticide packaging plant, and the adjacent waterway, the Lauritzen Channel. Potential identified sources of contamination were from sloughed material from undredged areas (such as side banks) and from outfall pipes. Objectives of Phase I included the (1) evaluation of pesticide concentrations associated with discharge from outfalls, (2) identification of additional outfalls in the area, (3) identification of type, quantity, and distribution of sediment under the Levin pier, (4) quantification of pesticide concentrations inmore » sediment under the pier, and (5) evaluation of sediment structure and slope stability under the pier. Field operations included the collection of sediment directly from inside the mouths of outfall pipes, when possible, or the deployment of specially designed particle traps where direct sampling was problematic. Passive water samplers were placed at the end of known outfall pipes and analyzed for DDT and other pesticides of concern. Underwater dive surveys were conducted beneath the Levin pier to document type, slope, and thickness of sediment. Samples were collected at locations of interest and analyzed for contaminants. Also sampled was soil from bank areas, which were suspected of potentially contributing to continued DDT contamination of the Lauritzen Channel through erosion and groundwater leaching. The Phase I Source Investigation was successful in identifying significant sources of DDT contamination to Lauritzen Channel sediment. Undredged sediment beneath the Levin pier that has been redistributed to the channel is a likely source. Two outfalls tested bear further investigation. Not as well-defined are the contributions of bank erosional material and groundwater leaching. Subsequent investigations will be based on the results of this first phase.« less

Catch and Release: A dense, longitudinal array of water quality sondes reveals spatial and temporal complexities in suspended sediment flux

NASA Astrophysics Data System (ADS)

Guilinger, J. J.; Crosby, B. T.

2017-12-01

Excessive suspended sediment in streams is one of the most common causes for industrial, ecological and recreational stream impairment in the US. Identifying the primary geomorphic or anthropogenic sources of sediment is a key step in the effective mitigation of impairment. This study seeks to identify sources of suspended sediment in an agriculturally impaired watershed, Marsh Creek, in southeast Idaho. We employ thirteen multi-parameter water quality sensors to simultaneously measure stage, turbidity, temperature and conductivity every 15 minutes over a full calendar year. Examined at both the event and annual scale, these data enable mass balance calculations for mainstem and tributary contributions. Revealed in this monitoring is an approximately eight-fold longitudinal increase in sediment flux over 74 km that is largely augmented by eroding mainstem banks in reaches with higher stream power in the lower 30 km, with less than 20% contributed from tributaries. Independent data confirming the bank source were acquired through cost-effective sediment fingerprinting using 15N and C:N signatures from potential soil endmembers. Additionally, Google Street View-type longitudinal imagery of banks was collected via a kayak survey to confirm the spatial extent and magnitude of bank erosion along Marsh Creek. These data converge on bank erosion as the primary source of fine sediment. Sediment load at various hierarchical temporal and spatial scales is impacted by in-stream storage and remobilization, especially over shorter timescales ranging from daily to seasonal periods. Once averaged over the annual scale, local, temporary in-channel storage is overcome and these data reveal source reaches that can be prioritized for restoration and mitigation projects.

Origin and effect factors of sedimentary organic carbon in a karst groundwater-fed reservoir, South China.

PubMed

Huang, Siyu; Pu, Junbing; Cao, Jianhua; Li, Jianhong; Zhang, Tao; Jiang, Feng; Li, Li; Wu, Feihong; Pan, Moucheng; Bai, Bing

2018-03-01

Reservoirs are commonly recharged by groundwater that is rich in bicarbonate ions in karst regions of South China, and the recharge of this groundwater to the reservoir can affect the biogeochemical processes of carbon sedimentation at the reservoir bottom. In this study, Dalongdong Reservoir, which is mainly recharged by two subterranean streams, was investigated based on a 42-cm-thick sedimentary core and the 210 Pb/ 137 Cs dating technique and isotope analyses to understand the sedimentary history and identify the carbon sources. The 210 Pb/ 137 Cs age model showed that the sediments were accumulated over the last 60 years. The annual increase precipitation and temperature showed no obvious change compared with trends of δ 13 C in total organic carbon (δ 13 C org ), δ 15 N values in total nitrogen, and the carbon and nitrogen ratio (C/N). This shows that climate was not the main control of the variation in sediment factors. Based on δ 13 C org , δ 15 N, C/N, and isotopic mixing modeling, sources of organic carbon in the sediments were derived from plankton (60.84%), soil (22.93%), waste water (14.56%), and terrestrial plants (1.67%). From 1958 to 1978, reservoir establishment and leakage affected the contribution of the four sources. The contribution of the plankton source increased from 1978 to 2015, resulting from change of water level and continued input of external nitrogen. However, because of the revegetation supplied by an economic aid project the contribution of soil showed a considerable decreasing trend from 1978 to 2002. After 2002, For "Grain for Green" project, the contribution from soil further decreased. After reservoir construction, the contribution of waste water stabilized. The contribution of terrestrial plants started increased rapidly after 2002. Karst groundwater, which contains more dissolved inorganic carbon containing lower δ 13 C DIC than the water sources of other lakes or reservoirs, makes the δ 13 C org value of sediment more negative by phytoplankton photosynthesis in the reservoir.

Comparative phosphorus sorption by marine sediments and agricultural soils in a tropical environment.

PubMed

Fox, Robert L; Fares, Ali; Wan, Y; Evensen, Carl I

2006-01-01

The influence of soil phosphorus (P) sources on P sorption characteristics of marine sediments was investigated for Pearl Harbor and off shore Molokai in Hawaii. Estuary sediments were sampled in seven locations; these represented different soils and on-shore activities. The soil samples included nine major soils that contributed sediment to the Harbor and coastal sediments near the island of Molokai. Sediment and soil samples were equilibrated for 6 days in 0.01 M CaCl(2) solution and synthetic seawater containing differing amounts of P. Phosphorus sorption curves were constructed. The equilibrated solution P, with no P added, ranged from 0.01 to 0.2 mg L(-1); P sorption by sediments at standard solution concentration 0.2 mg L(-1), ranged from 0 to 230 mg kg(-1). Sediment P sorption corresponded closely with soil sorption characteristics. Soils contributing sediments to the west reach of Pearl Harbor are highly weathered Oxisols with high standard P sorption values while those in the southeast of the Harbor were Vertisols and Mollisols which sorb little P. The influence of source materials on sediment P sorption was also observed for off-shore sediments near Molokai. Sediments serve as both source and sink for P in Pearl Harbor and in this role can be a stabilizing influence on P concentration in the water column. Phosphorus sorption curves in conjunction with water quality data can help to understand P dynamics between sediments and the water column and help evaluate concerns about P loading to a water body. For Pearl Harbor, solution P in equilibrium with sediments from the Lochs was 0.021 mg L(-1); a value unlikely to produce an algal bloom. (Measured total P in the water columns (mean) was 0.060.).

Quantifying and identifying the sources of fine sediment input in a typical Mongolian river basin, the Kharaa River case study

NASA Astrophysics Data System (ADS)

Theuring, Phillip

2013-04-01

Mongolia is facing a tremendous change of land-use intensification due to expansions in the agricultural sector, an increase of cattle and livestock and a growth of urban settlements by migration of the rural population to the cities. With most of its area located in a semiarid to arid environment, Mongolia is vulnerable to climatic changes that are expected to lead to higher temperatures and increased evapotranspiration. It is expected that this may lead to unfavorable changes in surface water quality caused by increased nutrients and sediment bound pollutants emissions. Increased fine sediment load is associated with nutrient, heavy metal and pollutant input and therefore affects water quality. Previous studies using radionuclide fallout isotope sediment source fingerprinting investigations identified riverbank erosion as the main source of suspended sediment in the Kharaa River. Erosion susceptibility calculations in combination with suspended sediment observations showed strong seasonal and annual variabilities of sediment input and in-stream transport, and a strong connection of erosional behaviour with land-use.The objective of this study is to quantify the current water quality threats by fine sediment inputs in the 15,000 km2 Kharaa River basin in Northern Mongolia by delineating the sources of the fine sediments and estimating the sediment budget.To identify the spatial distribution of sediment sources within the catchment, more than 1000 samples from the river confluences at the outlet of each sub basin into the main tributary were collected during 5 intensive grab sediment sampling campaigns in 2009-11. The fine sediment fraction (<10μm) has been analysed using geochemical tracer techniques for spatial source identification, based on major elements (e.g. Si, Al, Mg, Fe, Na, K, P) and trace elements (e.g. Ba, Pb, Sr, Zn). The contribution of suspended sediment of each sub basin in the main tributary has been evaluated with help of a mixing model. To asses sediment sources the RUSLE based sediment budget model (SedNet) was employed to estimate surface erosion and sediment budget. The spatial origin of the fine sediment in the catchment could be identified by geochemical fingerprinting techniques. This shows that only some subcatchments contribute considerably to the fine sediment load, especially areas with high grazing intensity and degraded riparian vegetation. The estimated average soil loss in the catchment is 0.2 t×ha-1•a-1. The model results reveal a strong influence of the landuse in the catchment on surface erosion and fine sediment input, which will increase with the intensification of agriculture in the catchment.

Application of quantitative composite fingerprinting technique to identify the main sediment sources in two small catchments of Iran

NASA Astrophysics Data System (ADS)

Kouhpeima, A.; Feiznia, S.; Ahmadi, H.; Hashemi, S. A.; Zareiee, A. R.

2010-09-01

The targeting of sediment management strategies is a key requirement in developing countries including Iran because of the limited resources available. These targeting is, however hampered by the lack of reliable information on catchment sediment sources. This paper reports the results of using a quantitative composite fingerprinting technique to estimate the relative importance of the primary potential sources within the Amrovan and Royan catchments in Semnan Province, Iran. Fifteen tracers were first selected for tracing and samples were analyzed in the laboratory for these parameters. Statistical methods were applied to the data including nonparametric Kruskal-Wallis test and Differentiation Function Analysis (DFA). For Amrovan catchment three parameters (N, Cr and Co) were found to be not significant in making the discrimination. The optimum fingerprint, comprising Oc, PH, Kaolinite and K was able to distinguish correctly 100% of the source material samples. For the Royan catchment, all of the 15 properties were able to distinguish between the six source types and the optimum fingerprint provided by stepwise DFA (Cholorite, XFD, N and C) correctly classifies 92.9% of the source material samples. The mean contributions from each sediment source obtained by multivariate mixing model varied at two catchments. For Amrovan catchment Upper Red formation is the main sediment sources as this sediment source approximately supplies 36% of the reservoir sediment whereas the dominant sediment source for the Royan catchment is from Karaj formation that supplies 33% of the reservoir sediments. Results indicate that the source fingerprinting approach appears to work well in the study catchments and to generate reliable results.

Sediment Sources Change for the Past 42 Years in a Small Watershed Located in the Black Soil Region of Northeastern China Based on Fingerprinting Method

NASA Astrophysics Data System (ADS)

Du, P.; Huang, D.; Ning, D.

2017-12-01

The temporal change of sediment source in watershed is very helpful for evaluating the adopted soil conservation measures and the implemented land management practices. For this purpose, a sediment profile from Hebei watershed outlet and 59 samples from the three potential sediment sources were collected. The rediounuclide Pb-210 was then measured to obtain sedimentation rate for the past 42 years. Generally, the sedimentation rate was gradually decreased from 10.83 cm yr-1 in the 1970's to 1.50 cm yr-1in the 2010's. Taken the radiounulide Cs-137 as a fingerprinting identifying tracer, the mean contribution of sediment from cultivated lands, woodlands, and channel banks were 50.60%, 22.26%, and 26.74%, while the ranges varying from 20.16% to 84.02%, from 2.22% to 36.85%, and from 11.61% to 53.28%, respectively. The percentage of sediment sources from cultivated lands was decreased, whereas the percentages from woodlands and channel banks were both increased in the past 42 years. The results indicate that soil conservation measures adopted in the cultivated lands have been played a very important role in reducing erosion, however, more attention on land management practices implementation should be paid to maintain current woodland and to control serious gully erosion in the black soil region. (This paper is a contribution to the project of National Natural Science Foundation of China (No. 41501299), and the non-profit project of Ministry of Water Resources of China (No. 201501045).)

How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

PubMed Central

Watanabe, Kenta; Kuwae, Tomohiro

2015-01-01

Carbon captured by marine organisms helps sequester atmospheric CO2, especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air–sea CO2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10–30. Phytoplankton-derived POC dominated the water column POC (65–95%) within this salinity range; however, it was minor in the sediments (3–29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49–78% and 19–36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15–30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They function at different timescales, depending on the salinity, and OC sources. PMID:25880367

Sources, Transport, and Storage of Sediment at Selected Sites in the Chesapeake Bay Watershed

USGS Publications Warehouse

Gellis, Allen C.; Hupp, Cliff R.; Pavich, Milan J.; Landwehr, Jurate M.; Banks, William S.L.; Hubbard, Bernard E.; Langland, Michael J.; Ritchie, Jerry C.; Reuter, Joanna M.

2009-01-01

The Chesapeake Bay Watershed covers 165,800 square kilometers and is supplied with water and sediment from five major physiographic provinces: Appalachian Plateau, Blue Ridge, Coastal Plain, Piedmont, and the Valley and Ridge. Suspended-sediment loads measured in the Chesapeake Bay Watershed showed that the Piedmont Physiographic Province has the highest rates of modern (20th Century) sediment yields, measured at U.S. Geological Survey streamflow-gaging stations, and the lowest rates of background or geologic rates of erosion (~10,000 years) measured with in situ beryllium-10. In the agricultural and urbanizing Little Conestoga Creek Watershed, a Piedmont watershed, sources of sediment using the 'sediment-fingerprinting' approach showed that streambanks were the most important source (63 percent), followed by cropland (37 percent). Cesium-137 inventories, which quantify erosion rates over a 40-year period, showed average cropland erosion of 19.39 megagrams per hectare per year in the Little Conestoga Creek Watershed. If this erosion rate is extrapolated to the 13 percent of the watershed that is in cropland, then cropland could contribute almost four times the measured suspended-sediment load transported out of the watershed (27,600 megagrams per hectare per year), indicating that much of the eroded sediment is being deposited in channel and upland storage. The Piedmont has had centuries of land-use change, from forest to agriculture, to suburban and urban areas, and in some areas, back to forest. These land-use changes mobilized a large percentage of sediment that was deposited in upland and channel storage, and behind thousands of mill dams. The effects of these land-use changes on erosion and sediment transport are still being observed today as stored sediment in streambanks is a source of sediment. Cropland is also an important source of sediment. The Coastal Plain Physiographic Province has had the lowest sediment yields in the 20th Century and with sandy soils, contributes little fine-grained sediment. In the agricultural Pocomoke River Watershed, a Coastal Plain watershed, cesium-137 mass-balance results indicate that erosion and deposition are both occurring on cropland fields. Sources of sediment using the sediment-fingerprinting approach for the Pocomoke River were distributed as follows: cropland (46 percent), ditch beds (34 percent), ditch banks and streambanks (7 percent), and forest (13 percent). Cropland was a source of sediment for the two largest peak flow events, which occurred during harvesting when the ground may have been bare. The Pocomoke River Watershed is heavily ditched and channelized, conditions that are favorable for ditch bed and bank erosion. In the mixed land use (forested, agricultural, and urbanizing) Mattawoman Creek Watershed, a Coastal Plain watershed, sources of sediment using the sediment-fingerprinting approach were distributed as follows: streambanks (30 percent), forest (29 percent), construction (25 percent), and cropland (17 percent). Mattawoman Creek Watershed drains a rapidly developing region with 182 hectares (approximately 1.26 percent of the watershed) under construction. Sediment from construction sites was also determined as a source of sediment in the Mattawoman Creek Watershed. The sediment-fingerprinting source results for the three watersheds analyzed, show that in all watersheds, both the stream corridor and agriculture were significant sources of sediment. Forest as a source of sediment in the Mattawoman Creek Watershed may indicate that these forests are being disturbed and forest soils are eroding. Bare ground can be an important sediment source. Spatial analysis of bare ground in the Little Conestoga Creek Watershed using satellite imagery between 2000 and 2005 showed that the majority of bare ground was classified as pasture. Bare ground was correlated to the growing season with the highest percentages occurring in the early spring (April, 34 percent) and a

Sources and dispersal of land-based runoff from small Hawaiian drainages to a coral reef: Insights from geochemical signatures

NASA Astrophysics Data System (ADS)

Takesue, Renee K.; Storlazzi, Curt D.

2017-03-01

Land-based sediment and contaminant runoff is a major threat to coral reefs, and runoff reduction efforts would benefit from knowledge of specific runoff sources. Geochemical signatures of small drainage basins were determined in the fine fraction of soil and sediment, then used in the nearshore region of a coral reef-fringed urban embayment on southeast Oahu, Hawaii, to describe sources and dispersal of land-based runoff. The sedimentary rare earth element ratio (La/Yb)N showed a clear distinction between the two main rock types in the overall contributing area, tholeiitic and alkalic olivine basalt. Based on this geochemical signature it was apparent that the majority of terrigenous sediment on the reef flat originated from geologically old tholeiitic drainages. Sediment from one of five tholeiitic drainages had a distinct geochemical signature, and sediment with this signature was dispersed on the reef flat 2 km west and 150 m offshore of the contributing basin. Sediment and the anthropogenic metals Cd, Pb, and Zn were entrained in runoff from the most heavily urbanized region of the watershed. Although anthropogenic Cd and Zn had localized distributions close to shore, anthropogenic Pb was found associated with fine sediment on the westernmost part of the reef flat and 400 m offshore, illustrating how trade-wind-driven sediment transport can increase the scale of runoff impacts to nearshore communities. Our findings show that sediment geochemical signatures can provide insights about the source and dispersal of land-based runoff in shallow coastal environments. The application of such knowledge to watershed management and habitat remediation efforts can aid in the protection and restoration of runoff-impacted coastal ecosystems worldwide.

Sources and dispersal of land-based runoff from small Hawaiian drainages to a coral reef: Insights from geochemical signatures

USGS Publications Warehouse

Takesue, Renee K.; Storlazzi, Curt

2017-01-01

Land-based sediment and contaminant runoff is a major threat to coral reefs, and runoff reduction efforts would benefit from knowledge of specific runoff sources. Geochemical signatures of small drainage basins were determined in the fine fraction of soil and sediment, then used in the nearshore region of a coral reef-fringed urban embayment on southeast Oahu, Hawaii, to describe sources and dispersal of land-based runoff. The sedimentary rare earth element ratio (La/Yb)N showed a clear distinction between the two main rock types in the overall contributing area, tholeiitic and alkalic olivine basalt. Based on this geochemical signature it was apparent that the majority of terrigenous sediment on the reef flat originated from geologically old tholeiitic drainages. Sediment from one of five tholeiitic drainages had a distinct geochemical signature, and sediment with this signature was dispersed on the reef flat 2 km west and 150 m offshore of the contributing basin. Sediment and the anthropogenic metals Cd, Pb, and Zn were entrained in runoff from the most heavily urbanized region of the watershed. Although anthropogenic Cd and Zn had localized distributions close to shore, anthropogenic Pb was found associated with fine sediment on the westernmost part of the reef flat and 400 m offshore, illustrating how trade-wind-driven sediment transport can increase the scale of runoff impacts to nearshore communities. Our findings show that sediment geochemical signatures can provide insights about the source and dispersal of land-based runoff in shallow coastal environments. The application of such knowledge to watershed management and habitat remediation efforts can aid in the protection and restoration of runoff-impacted coastal ecosystems worldwide.

From deposition to erosion: Spatial and temporal variability of sediment sources, storage, and transport in a small agricultural watershed

USGS Publications Warehouse

Florsheim, J.L.; Pellerin, B.A.; Oh, N.H.; Ohara, N.; Bachand, P.A.M.; Bachand, Sandra M.; Bergamaschi, B.A.; Hernes, P.J.; Kavvas, M.L.

2011-01-01

The spatial and temporal variability of sediment sources, storage, and transport were investigated in a small agricultural watershed draining the Coast Ranges and Sacramento Valley in central California. Results of field, laboratory, and historical data analysis in the Willow Slough fluvial system document changes that transformed a transport-limited depositional system to an effective erosion and transport system, despite a large sediment supply. These changes were caused by a combination of factors: (i) an increase in transport capacity, and (ii) hydrologic alteration. Alteration of the riparian zone and drainage network pattern during the past ~ 150 years included a twofold increase in straightened channel segments along with a baselevel change from excavation that increased slope, and increased sediment transport capacity by ~ 7%. Hydrologic alteration from irrigation water contributions also increased transport capacity, by extending the period with potential for sediment transport and erosion by ~ 6 months/year. Field measurements document Quaternary Alluvium as a modern source of fine sediment with grain size distributions characterized by 5 to 40% fine material. About 60% of an upland and 30% of a lowland study reach incised into this deposit exhibit bank erosion. During this study, the wet 2006 and relatively dry 2007 water years exhibited a range of total annual suspended sediment load spanning two orders of magnitude: ~ 108,500 kg/km2/year during 2006 and 5,950 kg/km2/year during 2007, only 5% of that during the previous year. Regional implications of this work are illustrated by the potential for a small tributary such as Willow Slough to contribute sediment – whereas large dams limit sediment supply from larger tributaries – to the Sacramento River and San Francisco Bay Delta and Estuary. This work is relevant to lowland agricultural river–floodplain systems globally in efforts to restore aquatic and riparian functions and where water quality management includes reducing fine sediment contributions that can couple with other pollutants.

Sources of heavy metals in urban wastewater in Stockholm.

PubMed

Sörme, L; Lagerkvist, R

2002-10-21

The sources of heavy metals to a wastewater treatment plant was investigated. Sources can be actual goods, e.g. runoff from roofs, wear of tires, food, or activities, e.g. large enterprises, car washes. The sources were identified by knowing the metals content in various goods and the emissions from goods to sewage or stormwater. The sources of sewage water and stormwater were categorized to enable comparison with other research and measurements. The categories were households, drainage water, businesses, pipe sediment (all transported in sewage water), atmospheric deposition, traffic, building materials and pipe sediment (transported in stormwater). Results show that it was possible to track the sources of heavy metals for some metals such as Cu and Zn (110 and 100% found, respectively) as well as Ni and Hg (70% found). Other metals sources are still poorly understood or underestimated (Cd 60%, Pb 50%, Cr 20% known). The largest sources of Cu were tap water and roofs. For Zn the largest sources were galvanized material and car washes. In the case of Ni, the largest sources were chemicals used in the WTP and drinking water itself. And finally, for Hg the most dominant emission source was the amalgam in teeth. For Pb, Cr and Cd, where sources were more poorly understood, the largest contributors for all were car washes. Estimated results of sources from this study were compared with previously done measurements. The comparison shows that measured contribution from households is higher than that estimated (except Hg), leading to the conclusion that the sources of sewage water from households are still poorly understood or that known sources are underestimated. In the case of stormwater, the estimated contributions are rather well in agreement with measured contributions, although uncertainties are large for both estimations and measurements. Existing pipe sediments in the plumbing system, which release Hg and Pb, could be one explanation for the missing amount of these metals. Large enterprises were found to make a very small contribution, 4% or less for all metals studied. Smaller enterprises (with the exception of car washes) have been shown to make a small contribution in another city; the contribution in this case study is still unknown.

Clay mineralogy indicates the muddy sediment provenance in the estuarine-inner shelf of the East China Sea

NASA Astrophysics Data System (ADS)

Zhao, Yifei; Zou, Xinqing; Liu, Qing; Wang, Chenglong; Ge, Chendong; Xu, Min

2018-02-01

The estuarine-inner shelf mud regions of the East China Sea (ECS) are valuable for studying the source-to-sink processes of fluvial sediments deposited since the Holocene. In this study, we present evidence of the provenance and environmental evolution of two cores (S5-2 and JC07) from the estuarine-inner shelf regions of the ECS over the past 100 years based on 210Pb dating, high-resolution grain size measurements and clay mineral analyses. The results indicate that the clay mineral assemblages of cores S5-2 and JC07 are dominated by illite, followed by kaolinite and chlorite, and present scarce amounts of smectite. A comparison of these clay mineral assemblages with several major sources reveals that the fine sediments on the estuarine-inner shelf of the ECS represent a mixture of provenances associated with the Yangtze and Yellow Rivers, as well as smaller rivers. However, the contribution of each provenance has varied greatly over the past hundred years, as indicated by the down-core variability due to strong sediment reworking and transport on the inner shelf and the reduction of the sediment load from the Yangtze River basin. In the mud region of the Yangtze River estuary, the sediment from 1930 to 1956 was primarily derived from the Yangtze River, although the Yellow River was also an important influence. From 1956 to 2013, the Yellow River contribution decreased, whereas the Yangtze River contribution correspondingly increased. In the Zhe-Min mud region, the Yangtze River contributed more sediment than did other rivers from 1910 to 1950; however, the Yangtze River contribution gradually decreased from 1950 to 2013. Moreover, the other small rivers accounted for minor contributions, and the East Asian winter monsoon (EAWM) played an important role in the sediment transport process in the ECS. Our results indicate that the weakening/strengthening of the EAWM and a decrease in the sediment load of the Yangtze River influenced the transport and fate of sediment on the estuarine-inner shelf of the ECS.

Distinguishing spatiotemporal variability of sediment sources in small urbanized catchment as a response to urban expansion

NASA Astrophysics Data System (ADS)

Belyaev, Vladimir; Feoktistov, Artem; Huygens, Dries; Shamshurina, Eugenia; Golosov, Valentin

2014-05-01

Understanding hydrological response and geomorphic behavior of small catchments in urban environments, especially those experiencing urban expansion, represents serious and important problem which has not yet been given an adequate research attention. Urbanization exerts profound and diverse impacts on catchment characteristics, particularly by increasing surface runoff coefficients, peak flow discharges and rates of flash flood waves propagation as a result of widespread appearance of buildings and paved surfaces with practically zero infiltration capacities. Another essential influence of urbanization on small catchment hydrological regimes is associated with significant changes of natural topography (from relatively minor modifications such as grading of steeper slopes to complete transformations including total filling of gullies and small valleys, transfer of small streams from surface into underground pipes or collectors, etc.) combined with creation of systems of concrete-protected surface drainages and underground storm flow sewages. Such activities can result in substantial changes of runoff- and sediment-contributing areas for the remaining gullies and small valleys in comparison to the pre-urbanization conditions, causing dramatic increase of fluvial activity in some of those and much lower flow discharges in others. In addition, gullies and small valleys in urban settlements often become sites of dumping for both dry and liquid domestic and industrial wastes, thus being major pathways for dissolved and particle-bound pollutant transfer into perennial streams and rivers. All the problems listed require detailed hydrological and geomorphic investigations in order to provide sound basis for developing appropriate measures aimed to control and decrease urban erosion, sediment redistribution, pollution of water bodies, damage to constructions and communications. Recent advances in sediment tracing and fingerprinting techniques provide promising opportunities for distinguishing contributions of different sediment sources into catchment sediment budgets on a reliable quantitative basis. In combination with microstratigraphic differentiation and dating of sediment in continuous deposition zones by 137Cs depth distribution curves and available land use records, spatial and temporal variability of sediment sources and sinks can be reconstructed for the last several decades. That is especially important for catchments which experienced profound land use changes such as transition from pristine or agriculture-dominated to urbanized environment. The example presented here describes the results of reconstruction of changing sediment source types, contributions and spatial patterns for small reservoir catchment within the city of Kursk (Sredenerusskaya Upland, Central European Russia). Combination of compound specific stable isotopes, 137Cs, sediment grain size composition, land use information for several time intervals and daily rainfall record for the Kursk meteorological station (conveniently located within the study catchment) have been employed in order to evaluate major sediment sources within the catchment, their spatial pattern and temporal changes and compare those to history of reservoir sedimentation. The reservoir is situated on the Kur River - small river which gave its name to the city itself. The dam and reservoir were constructed and put into operation in 1969, thus the beginning of its infill is located stratigraphically later than the main peak of the global 137Cs fallout. It has been found that transition from dominantly agricultural land use to urbanized conditions caused decrease of contribution of soil erosion from cultivated land and increase of that of the active gullies into reservoir sedimentation. However, it is important to note that during extreme runoff events contribution of sediment originated from soil erosion on arable land still remains dominant, even though its area within the catchment recently became very limited.

Contaminant loading to Puget Sound from two marinas. Puget Sound estuary program. Final report, June 1988-October 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crecelius, E.A.; Fortman, T.J.; Kiesser, S.L.

1989-07-01

Concentrations of Cu, Pb, Zn, PAH's, TBT and FC bacteria were measured in surface sediment, sediment-trap, and water-column samples at two marinas in Puget Sound during summer of 1988. Levels of contaminants inside the marinas were compared with levels outside. TBT had greatest elevation in marina sediments compared to reference sediments. Few of sediments exceeded Puget Sound AET sediment quality values but most did exceed PSDDA screening levels for in-water disposal of dredged sediment. All marinas estimated to contribute less than one percent of total mass loading of Cu, Pb and Zn to main basin of Puget Sound. Contribution ofmore » TBT may be much more significant if antifouling paints are the major source for Puget Sound.« less

Assessing contribution of DOC from sediments to a drinking-water reservoir using optical profiling

USGS Publications Warehouse

Downing, Bryan D.; Bergamaschi, Brian A.; Evans, David G.; Boss, Emmanuel

2008-01-01

Understanding the sources of dissolved organic carbon (DOC) in drinking-water reservoirs is an important management issue because DOC may form disinfection by-products, interfere with disinfection, or increase treatment costs. DOC may be derived from a host of sources-algal production of DOC in the reservoir, marginal production of DOC from mucks and vascular plants at the margins, and sediments in the reservoir. The purpose of this study was to assess if release of DOC from reservoir sediments containing ferric chloride coagulant was a significant source of DOC to the reservoir. We examined the source-specific contributions of DOC using a profiling system to measure the in situ distribution of optical properties of absorption and fluorescence at various locations in the reservoir. Vertical optical profiles were coupled with discrete water samples measured in the laboratory for DOC concentration and optical properties: absorption spectra and excitation emission matrix spectra (EEMs). Modeling the in situ optical data permitted estimation of the bulk DOC profile in the reservoir as well as separation into source-specific contributions. Analysis of the source-specific profiles and their associated optical characteristics indicated that the sedimentary source of DOC to the reservoir is significant and that this DOC is labile in the reservoir. We conclude that optical profiling is a useful technique for understanding complex biogeochemical processes in a reservoir.

Mapping watershed potential to contribute phosphorus from geologic materials to receiving streams, southeastern United States

USGS Publications Warehouse

Terziotti, Silvia; Hoos, Anne B.; Harned, Douglas; Garcia, Ana Maria

2010-01-01

As part of the southeastern United States SPARROW (SPAtially Referenced Regressions On Watershed attributes) water-quality model implementation, the U.S. Geological Survey created a dataset to characterize the contribution of phosphorus to streams from weathering and erosion of surficial geologic materials. SPARROW provides estimates of total nitrogen and phosphorus loads in surface waters from point and nonpoint sources. The characterization of the contribution of phosphorus from geologic materials is important to help separate the effects of natural or background sources of phosphorus from anthropogenic sources of phosphorus, such as municipal wastewater or agricultural practices. The potential of a watershed to contribute phosphorus from naturally occurring geologic materials to streams was characterized by using geochemical data from bed-sediment samples collected from first-order streams in relatively undisturbed watersheds as part of the multiyear U.S. Geological Survey National Geochemical Survey. The spatial pattern of bed-sediment phosphorus concentration is offered as a tool to represent the best available information at the regional scale. One issue may weaken the use of bed-sediment phosphorus concentration as a surrogate for the potential for geologic materials in the watershed to contribute to instream levels of phosphorus-an unknown part of the variability in bed-sediment phosphorus concentration may be due to the rates of net deposition and processing of phosphorus in the streambed rather than to variability in the potential of the watershed's geologic materials to contribute phosphorus to the stream. Two additional datasets were created to represent the potential of a watershed to contribute phosphorus from geologic materials disturbed by mining activities from active mines and inactive mines.

Underestimated effects of sediments on enhanced startup performance of biofilm systems for polluted source water pretreatment.

PubMed

Lv, Zheng-Hui; Wang, Jing; Yang, Guang-Feng; Feng, Li-Juan; Mu, Jun; Zhu, Liang; Xu, Xiang-Yang

2018-02-01

In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH 4 + -N removal rate of 0.35 mg L -1 h -1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH 4 + -N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at  phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.

The occurrence and distribution of uronic acids and sugar methyl ethers in sediment trap materials and sediments of two coastal marine environments

NASA Astrophysics Data System (ADS)

Bergamaschi, Brian A.; Walters, Jeffrey S.; Hedges, John I.

1999-02-01

Although recent research has indicated that bacteria may contribute an important fraction of biochemical residues in terrestrial and marine environments, it is difficult for geochemists to identify contributions from these ubiquitous and biochemically diverse organisms. Previous studies have suggested uronic acids and O-methyl sugars may be useful indicators of microbial abundance and activity, but have been limited primarily to analyses of a small number of isolated samples. We report here comparative distributions of O-methyl sugars, uronic acids, and aldoses in sediment trap material and sediments from Dabob Bay, WA and nearby Saanich Inlet, BC, where temporal and spatial trends may be used together with well-established patterns in other biochemicals to identify bacterial contributions against the background of other carbohydrate sources. O-methyl sugars and uronic acids were important contributors to the overall flux and burial of polysaccharide material in Dabob Bay and Saanich Inlet, composing ≤12 wt% of the total carbohydrate yields from sediment trap and sediment samples. O-methyl sugars accounted for an average of 5% of the carbohydrate yields from sediment trap materials and sediments, but were found rarely and only in low abundance in vascular plant tissues, phytoplankton, and kelp. In contrast, uronic acids were abundant products of sediment trap material and sediments, as well as vascular plant tissues, where in some cases they predominated among all carbohydrates. Uronic acid abundance in sediment trap material averaged 3% and ranged to >6% of total carbohydrate yields. The persistence of total minor sugar yields in water column collections from Dabob Bay throughout the seasonal cycle indicated they had a primary source that was not directly related to plankton bloom cycles nor pulsed inputs of vascular plant remains. Subsurface maxima in total minor sugar yields (and several individual components) within sediment cores from both sites indicate in situ sedimentary sources. Taken together, the observed environmental distributions strongly suggest that the minor sugar abundances in Dabob Bay and Saanich Inlet were controlled by in situ microbial production.

Polycyclic Aromatic Hydrocarbons in Coastal Sediment of Klang Strait, Malaysia: Distribution Pattern, Risk Assessment and Sources

PubMed Central

Tavakoly Sany, Seyedeh Belin; Hashim, Rosli; Salleh, Aishah; Rezayi, Majid; Mehdinia, Ali; Safari, Omid

2014-01-01

Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia). The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions), with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait. PMID:24747349

Arsenic in sediments, groundwater, and streamwater of a glauconitic Coastal Plain terrain, New Jersey, USA-Chemical " fingerprints" for geogenic and anthropogenic sources

USGS Publications Warehouse

Barringer, J.L.; Reilly, P.A.; Eberl, D.D.; Blum, A.E.; Bonin, J.L.; Rosman, R.; Hirst, B.; Alebus, M.; Cenno, K.; Gorska, M.

2011-01-01

Glauconite-bearing deposits are found worldwide, but As levels have been determined for relatively few. The As content of glauconites in sediments of the Inner Coastal Plain of New Jersey can exceed 100mg/kg, and total As concentrations (up to 5.95??g/L) found historically and recently in streamwaters exceed the State standard. In a major watershed of the Inner Coastal Plain, chemical " fingerprints" were developed for streambed sediments and groundwater to identify contributions of As to the watershed from geologic and anthropogenic sources. The fingerprint for streambed sediments, which included Be, Cr, Fe and V, indicated that As was predominantly of geologic origin. High concentrations of dissolved organic C, nutrients (and Cl-) in shallow groundwater indicated anthropogenic inputs that provided an environment where microbial activity released As from minerals to groundwater discharging to the stream. Particulates in streamwater during high flow constituted most of the As load; the chemical patterns for these particulates resembled the geologic fingerprint of the streambed sediments. The As/Cr ratio of these suspended particles likely indicates they derived not only from runoff, but from groundwater inputs, because As contributed by groundwater is sequestered on streambed sediments. Agricultural inputs of As were not clearly identified, although chemical characteristics of some sediments indicated vehicle-related inputs of metals. Sediment sampling during dry and wet years showed that, under differing hydrologic conditions, local anthropogenic fingerprints could be obscured but the geologic fingerprint, indicating glauconitic sediments as an As source, was robust. ?? 2011.

Analyzing sources to sedimentary organic carbon in the Gulf of Urabá, southern Caribbean, using carbon stable isotopes

NASA Astrophysics Data System (ADS)

Rúa, Alex; Liebezeit, Gerd; Grajales, Heazel; Palacio, Jaime

2017-10-01

Carbon stable isotopes analysis serve reconstruction of the origin of organic matter (OM) deposited onto sediments. They also allow tracing vegetation change at different time scales. This study weighs the contribution of both marine and terrestrial sources to sedimentary organic carbon (OC) from a southwestern Caribbean Gulf partly surrounded by large Musa acuminata (banana) croplands. The δ13C values in three sediment cores from the gulf have slightly decreased over 1000 yrs BP, indicating enhanced terrestrial input of detrital carbon owing to river discharge. A two-end mixing model fed with these δ13C values showed that averaged terrestrial contribution of OC to sediment was 52.0% at prodelta, 76.4% at delta front, and 64.2% at Colombia Bay. This agrees well with sediment dynamics. The main source of sedimentary OC within the gulf was terrestrial instead of marine. In fact, a distorted trend in δ13C values for one of the coring sites could be the result of banana crop expansion through the 20th century.

Element geochemical analysis of the contribution of aeolian sand to suspended sediment in desert stream flash floods.

PubMed

Jia, Xiaopeng; Wang, Haibing

2014-01-01

The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream.

Element Geochemical Analysis of the Contribution of Aeolian Sand to Suspended Sediment in Desert Stream Flash Floods

PubMed Central

Wang, Haibing

2014-01-01

The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream. PMID:25089295

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mouser, Paula J.; N'Guessan, A. Lucie; Qafoku, Nikolla

The capacity for subsurface sediments to sequester metal contaminants, such as uranium (U), and retain them after bioremediation efforts are completed is critical to site stewardship. Sediments enriched in natural organic matter are capable of sequestering significant quantities of U, but may also serve as sources to the aquifer, contributing to plume persistence. Two types of sediments were compared to better understand the mechanisms contributing to the sequestration and release of U in the presence of organic matter. Artificially bioreduced sediments were retrieved from a field experimental plot previously stimulated with acetate while naturally bioreduced sediments were collected from amore » location enriched in organic matter but never subject to acetate amendment. Batch incubations demonstrated that the artificially bioreduced sediments were primed to rapidly remove uranium from the groundwater whereas naturally bioreduced sediments initially released a sizeable portion of sediment U before U(VI)-removal commenced. Column experiments confirmed that U release persisted for 65 pore volumes in naturally bioreduced sediments, demonstrating the sink-source behavior of this sediment. Acetate addition to artificially bioreduced sediments shifted the microbial community from one dominated by sulfate-reducing bacteria within Desulfobacteraceae to the iron-reducing family Geobacteraceae and Firmicutes during U(VI) reduction. In contrast, initial Geobacteraceae communities innaturally reduced sediments were replaced by clone sequences with similarity to opportunistic Pseudomonas spp. during U release, while U(VI) removal occurred concurrent with enrichment of Firmicutes. These investigations stress the importance of characterizing zones with heterogeneous carbon pools at U contaminated sites prior to the determination of a remedial strategy.« less

Clay mineralogy of surface sediments as a tool for deciphering river contributions to the Cariaco Basin (Venezuela)

NASA Astrophysics Data System (ADS)

Bout-Roumazeilles, V.; Riboulleau, A.; du Châtelet, E. Armynot; Lorenzoni, L.; Tribovillard, N.; Murray, R. W.; Müller-Karger, F.; Astor, Y. M.

2013-02-01

The mineralogical composition of 95 surface sediment samples from the Cariaco Basin continental shelf and Orinoco delta was investigated in order to constrain the clay-mineral main provenance and distribution within the Cariaco Basin. The spatial variability of the data set was studied using a geo-statistical approach that allows drawing representative clay-mineral distribution maps. These maps are used to identify present-day dominant sources for each clay-mineral species in agreement with the geological characteristics of the main river watersheds emptying into the basin. This approach allows (1) identifying the most distinctive clay-mineral species/ratios that determine particle provenance, (2) evaluating the respective contribution of local rivers, and (3) confirming the minimal present-day influence of the Orinoco plume on the Cariaco Basin sedimentation. The Tuy, Unare, and Neveri Rivers are the main sources of clay particles to the Cariaco Basin sedimentation. At present, the Tuy River is the main contributor of illite to the western part of the southern Cariaco Basin continental shelf. The Unare River plume, carrying smectite and kaolinite, has a wide westward propagation, whereas the Neveri River contribution is less extended, providing kaolinite and illite toward the eastern Cariaco Basin. The Manzanares, Araya, Tortuga, and Margarita areas are secondary sources of local influence. These insights shed light on the origin of present-day terrigenous sediments of the Cariaco Basin and help to propose alternative explanations for the temporal variability of clay mineralogy observed in previously published studies.

Measuring fallout radionuclides to constrain the origin and the dynamics of suspended sediment in an agricultural drained catchment (Loire River basin, France)

NASA Astrophysics Data System (ADS)

Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

2015-04-01

Soil erosion reaches problematic levels in agricultural areas of Northwestern Europe where tile drains may accelerate sediment transfer to rivers. This supply of large quantities of fine sediment to the river network leads to the degradation of water quality by increasing water turbidity, filling reservoirs and transporting contaminants. Agricultural patterns and landscapes features have been largely modified by human activities during the last century. To investigate erosion and sediment transport in lowland drained areas, a small catchment, the Louroux (24 km²), located in the French Loire River basin was selected. In this catchment, channels have been reshaped and more than 220 tile drains outlets have been installed after World War II. As a result, soil erosion and sediment fluxes strongly increased. Sediment supply needs to be better understood by quantifying the contribution of sources and the residence times of particles within the catchment. To this end, a network of river monitoring stations was installed, and fallout radionuclides (Cs-137, excess Pb-210 and Be-7) were measured in rainwater (n=3), drain tile outlets (n=4), suspended sediment (n=15), soil surface (n=30) and channel bank samples (n=15) between January 2013 and February 2014. Cs-137 concentrations were used to quantify the contribution of surface vs. subsurface sources of sediment. Results show a clear dominance of particles originating from surface sources (99 ± 1%). Be-7 and excess Pb-210 concentrations and calculation of Be-7/excess Pb-210 ratios in rainfall and suspended sediment samples were used to estimate percentages of recently eroded sediment in rivers. The first erosive winter storm mainly exported sediment depleted in Be-7 that likely deposited on the riverbed during the previous months. Then, during the subsequent floods, sediment was directly eroded and exported to the catchment outlet. Our results show the added value of combining spatial and temporal tracers to characterize and quantify sources of sediment and particle transport processes within an agricultural catchment.

What is the Source? Post-glacial sediment flux from the Waipaoa Catchment, New Zealand

NASA Astrophysics Data System (ADS)

Bilderback, E. L.; Pettinga, J. R.; Litchfield, N. J.; Quigley, M.; Marden, M.

2011-12-01

In the Waipaoa, and for much of the eastern North Island, the shift from the last glacial coldest period to the current interglacial climatic regime resulted in Late Pleistocene-Holocene catchment-wide channel incision (Berryman et al., 2000; Litchfield and Berryman, 2005). Only ~25% of the total post 18 ka sediment yield for the Waipaoa Catchment can be accounted for by channel incision, one of the most widespread and most effective erosive processes in the catchment (Orpin et al., 2006; Marden et al., 2008). We find that deep-seated landslides, which are pervasive, cannot make up this apparent source area sediment deficit. This presents a challenge to our current understanding of the Waipaoa Sedimentary System. New high resolution topographic data sets (lidar and photogrammetry) combined with tephrochronology and field mapping have enabled us to approximate the sediment flux from post 18 ka deep-seated landslides. The sediment delivered to the offshore sink from these upper Waipaoa landslides is likely to be less than 20% of the sediment volume calculated for channel incision. A further GIS analysis of the ~2500 km2 Waipaoa catchment using work from Crosby and Whipple (2006) delineating relict topography and Marden et al. (2008) accounting for river incision and slopes stabilized behind terrace remnants indicates that only about half of the available catchment area could have contributed additional large volumes of sediment to the offshore post 18 ka sink. The presence of tephra cover older than 18 ka on landforms ranging from flat ridgelines to steep (>30 degree) slopes in this remaining terrestrial source area suggests that it has not been eroded en mass. The apparent source deficit remains even though many of the major erosive processes available to fill this deficit have been studied and the potentially contributing catchment area is dramatically reduced by these studies. This analysis raises questions about erosive processes and our ability to balance large scale sediment budgets. Does costal erosion contribute a significant volume to the offshore sink? Was sediment from other catchments trapped in the Poverty Bay postglacial shelf basin? Are the uncertainties in any of these source and sink calculations large enough that the previous questions are essentially irrelevant? We believe that it is an achievable goal to account for the major processes that generate sediment in the Waipaoa Sedimentary System and that this budget tuning can inform our understanding of active landscapes.

The influence of a semi-arid sub-catchment on suspended sediments in the Mara River, Kenya

PubMed Central

2018-01-01

The Mara River Basin in East Africa is a trans-boundary basin of international significance experiencing excessive levels of sediment loads. Sediment levels in this river are extremely high (turbidities as high as 6,000 NTU) and appear to be increasing over time. Large wildlife populations, unregulated livestock grazing, and agricultural land conversion are all potential factors increasing sediment loads in the semi-arid portion of the basin. The basin is well-known for its annual wildebeest (Connochaetes taurinus) migration of approximately 1.3 million individuals, but it also has a growing population of hippopotami (Hippopotamus amphibius), which reside within the river and may contribute to the flux of suspended sediments. We used in situ pressure transducers and turbidity sensors to quantify the sediment flux at two sites for the Mara River and investigate the origin of riverine suspended sediment. We found that the combined Middle Mara—Talek catchment, a relatively flat but semi-arid region with large populations of wildlife and domestic cattle, is responsible for 2/3 of the sediment flux. The sediment yield from the combined Middle Mara–Talek catchment is approximately the same as the headwaters, despite receiving less rainfall. There was high monthly variability in suspended sediment fluxes. Although hippopotamus pools are not a major source of suspended sediments under baseflow, they do contribute to short-term variability in suspended sediments. This research identified sources of suspended sediments in the Mara River and important regions of the catchment to target for conservation, and suggests hippopotami may influence riverine sediment dynamics. PMID:29420624

Badlands as a major source of petrogenic particulate Organic Carbon and sediments to the Gulf of Lion (NW Mediterranean Sea)

NASA Astrophysics Data System (ADS)

Copard, Y.; Eyrolle-Boyer, F.; Radakovitch, O.; Poirel, A.; Raimbault, P.; Gairoard, S.; Di-Giovanni, C.

2017-12-01

Rivers feed the marine environments both in term of sediments and nutrients and consequently, the characterization of their nature, sources and changes over a different spatial and time ranges is a critical for many scientific (e.g. biogeochemical cycles, contaminants transfer, geomorphology, ecology) and societal issues (e.g. food security, catastrophic floods). Specifically, continental sources showing some high erosion rates deserve to be studied since their fingerprint can be significant for the rivers fluxes. These included some sedimentary rocks (e.g. marls) forming badlands and containing a significant amount of petrogenic particulate organic carbon (pPOC) for which its contribution to the Rivers still remains evasive. Our study focuses on the Mediterranean area considered as very sensitive to the Global Change and particularly the Gulf of Lion mainly fed by the Rhône River, one of the major conveyors of sediments to this Sea. Based on radiocarbon data performed on a set of riverine samples and time series analyses from monitoring stations from French CZOs, we (i) update the POC flux of the Rhône River, (ii) determine the pPOC content and flux in suspended sediments and (iii) estimate the badlands contribution from the Durance catchment (a major tributary of the Rhône River) to the pPOC flux and to sediment discharge. Sediment discharge by the Rhône River to the Sea is 6.5 ± 4.3 Tg yr-1 (period 1990-2014) , its POC discharge reaches 0.145 ± 0.095 Tg yr-1 (period 2007-2014) while pPOC (0.44 wt. %) contributes to 30 % of this POC flux. Despite their insignificant surfaces (0.2 %) regarding the Rhône catchment area, badlands presently in erosion from the Durance catchment provide respectively, 16, 5 and 20 % of the pPOC, POC and sediment fluxes to the Rhône River. Consequently, badlands can be considered as a major source of sediments and pPOC for the NW Mediterranean Sea. We suggest that river-dominated ocean margins, such as the Rhône River, with badlands in erosion in their catchment could export a significant amount of sediments and pPOC to the oceans. According to the natural climate variability and more recently to the anthropogenic (LULUCF) disorders occurring in continental surfaces, such contributions had to and will strongly vary with times (from the geological times to the next decades scales).

Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)

NASA Astrophysics Data System (ADS)

Hindshaw, Ruth S.; Tosca, Nicholas J.; Piotrowski, Alexander M.; Tipper, Edward T.

2018-03-01

The identification of sediment sources to the ocean is a prerequisite to using marine sediment cores to extract information on past climate and ocean circulation. Sr and Nd isotopes are classical tools with which to trace source provenance. Despite considerable interest in the Arctic Ocean, the circum-Arctic source regions are poorly characterised in terms of their Sr and Nd isotopic compositions. In this study we present Sr and Nd isotope data from the Paleogene Central Basin sediments of Svalbard, including the first published data of stream suspended sediments from Svalbard. The stream suspended sediments exhibit considerable isotopic variation (ɛNd = -20.6 to -13.4; 87Sr / 86Sr = 0.73421 to 0.74704) which can be related to the depositional history of the sedimentary formations from which they are derived. In combination with analysis of the clay mineralogy of catchment rocks and sediments, we suggest that the Central Basin sedimentary rocks were derived from two sources. One source is Proterozoic sediments derived from Greenlandic basement rocks which are rich in illite and have high 87Sr / 86Sr and low ɛNd values. The second source is Carboniferous to Jurassic sediments derived from Siberian basalts which are rich in smectite and have low 87Sr / 86Sr and high ɛNd values. Due to a change in depositional conditions throughout the Paleogene (from deep sea to continental) the relative proportions of these two sources vary in the Central Basin formations. The modern stream suspended sediment isotopic composition is then controlled by modern processes, in particular glaciation, which determines the present-day exposure of the formations and therefore the relative contribution of each formation to the stream suspended sediment load. This study demonstrates that the Nd isotopic composition of stream suspended sediments exhibits seasonal variation, which likely mirrors longer-term hydrological changes, with implications for source provenance studies based on fixed end-members through time.

Determining the sources of suspended sediment in a Mediterranean groundwater-dominated river: the Na Borges basin (Mallorca, Spain).

NASA Astrophysics Data System (ADS)

Estrany, Joan; Martinez-Carreras, Nuria

2013-04-01

Tracers have been acknowledged as a useful tool to identify sediment sources, based upon a variety of techniques and chemical and physical sediment properties. Sediment fingerprinting supports the notion that changes in sedimentation rates are not just related to increased/reduced erosion and transport in the same areas, but also to the establishment of different pathways increasing sediment connectivity. The Na Borges is a Mediterranean lowland agricultural river basin (319 km2) where traditional soil and water conservation practices have been applied over millennia to provide effective protection of cultivated land. During the twentieth century, industrialisation and pressure from tourism activities have increased urbanised surfaces, which have impacts on the processes that control streamflow. Within this context, source material sampling was focused in Na Borges on obtaining representative samples from potential sediment sources (comprised topsoil; i.e., 0-2 cm) susceptible to mobilisation by water and subsequent routing to the river channel network, while those representing channel bank sources were collected from actively eroding channel margins and ditches. Samples of road dust and of solids from sewage treatment plants were also collected. During two hydrological years (2004-2006), representative suspended sediment samples for use in source fingerprinting studies were collected at four flow gauging stations and at eight secondary sampling points using time-integrating sampling samplers. Likewise, representative bed-channel sediment samples were obtained using the resuspension approach at eight sampling points in the main stem of the Na Borges River. These deposits represent the fine sediment temporarily stored in the bed-channel and were also used for tracing source contributions. A total of 102 individual time-integrated sediment samples, 40 bulk samples and 48 bed-sediment samples were collected. Upon return to the laboratory, source material samples were oven-dried at 40° C, disaggregated using a pestle and mortar, and dry sieved to

Targeted versus statistical approaches to selecting parameters for modelling sediment provenance

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick

2017-04-01

One effective field-based approach to modelling sediment provenance is the source fingerprinting technique. Arguably, one of the most important steps for this approach is selecting the appropriate suite of parameters or fingerprints used to model source contributions. Accordingly, approaches to selecting parameters for sediment source fingerprinting will be reviewed. Thereafter, opportunities and limitations of these approaches and some future research directions will be presented. For properties to be effective tracers of sediment, they must discriminate between sources whilst behaving conservatively. Conservative behavior is characterized by constancy in sediment properties, where the properties of sediment sources remain constant, or at the very least, any variation in these properties should occur in a predictable and measurable way. Therefore, properties selected for sediment source fingerprinting should remain constant through sediment detachment, transportation and deposition processes, or vary in a predictable and measurable way. One approach to select conservative properties for sediment source fingerprinting is to identify targeted tracers, such as caesium-137, that provide specific source information (e.g. surface versus subsurface origins). A second approach is to use statistical tests to select an optimal suite of conservative properties capable of modelling sediment provenance. In general, statistical approaches use a combination of a discrimination (e.g. Kruskal Wallis H-test, Mann-Whitney U-test) and parameter selection statistics (e.g. Discriminant Function Analysis or Principle Component Analysis). The challenge is that modelling sediment provenance is often not straightforward and there is increasing debate in the literature surrounding the most appropriate approach to selecting elements for modelling. Moving forward, it would be beneficial if researchers test their results with multiple modelling approaches, artificial mixtures, and multiple lines of evidence to provide secondary support to their initial modelling results. Indeed, element selection can greatly impact modelling results and having multiple lines of evidence will help provide confidence when modelling sediment provenance.

Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata

USGS Publications Warehouse

Lee, J.-S.; Lee, B.-G.; Yoo, H.; Koh, C.-H.; Luoma, S.N.

2001-01-01

A laboratory bioassay determined the relative contribution of various pathways of Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata exposed to moderately contaminated sediments. Juvenile worms were exposed for 25 d to experimental sediments containing 5 different reactive sulfide (acid volatile sulfides, AVS) concentrations (1 to 30 ??mol g-1), but with constant Ag, Cd, and Zn concentrations of 0.1, 0.1 and 7 ??mol g-1, respectively. The sediments were supplemented with contaminated food (TetraMin??) containing 3 levels of Ag-Cd-Zn (uncontaminated, 1?? or 5??1 metal concentrations in the contaminated sediment). The results suggest that bioaccumulation of Ag, Cd and Zn in the worms occurred predominantly from ingestion of contaminated sediments and contaminated supplementary food. AVS or dissolved metals (in porewater and overlying water) had a minor effect on bioaccumulation of the 3 metals in most of the treatments. The contribution to uptake from the dissolved source was most important in the most oxic sediments, with maximum contributions of 8% for Ag, 30% for Cd and 20% for Zn bioaccumulation. Sediment bioassays where uncontaminated supplemental food is added could seriously underestimate metal exposures in an equilibrated system; N. arenaceodentata feeding on uncontaminated food would be exposed to 40-60% less metal than if the food source was equilibrated (as occurs in nature). Overall, the results show that pathways of metal exposure are dynamically linked in contaminated sediments and shift as external geochemical characteristics and internal biological attributes vary.

Fingerprinting Sources of Suspended Sediment in a Canadian Agricultural Watershed Using the MixSIAR Bayesian Unmixing Model

NASA Astrophysics Data System (ADS)

Smith, J. P.; Owens, P. N.; Gaspar, L.; Lobb, D. A.; Petticrew, E. L.

2015-12-01

An understanding of sediment redistribution processes and the main sediment sources within a watershed is needed to support watershed management strategies. The fingerprinting technique is increasingly being recognized as a method for establishing the source of the sediment transported within watersheds. However, the different behaviour of the various fingerprinting properties has been recognized as a major limitation of the technique, and the uncertainty associated with tracer selection needs to be addressed. There are also questions associated with which modelling approach (frequentist or Bayesian) is the best to unmix complex environmental mixtures, such as river sediment. This study aims to compare and evaluate the differences between fingerprinting predictions provided by a Bayesian unmixing model (MixSIAR) using different groups of tracer properties for use in sediment source identification. We used fallout radionuclides (e.g. 137Cs) and geochemical elements (e.g. As) as conventional fingerprinting properties, and colour parameters as emerging properties; both alone and in combination. These fingerprinting properties are being used (i.e. Koiter et al., 2013; Barthod et al., 2015) to determine the proportional contributions of fine sediment in the South Tobacco Creek Watershed, an agricultural watershed located in Manitoba, Canada. We show that the unmixing model using a combination of fallout radionuclides and geochemical tracers gave similar results to the model based on colour parameters. Furthermore, we show that a model that combines all tracers (i.e. radionuclide/geochemical and colour) gave similar results, showing that sediment sources change from predominantly topsoil in the upper reaches of the watershed to channel bank and bedrock outcrop material in the lower reaches. Barthod LRM et al. (2015). Selecting color-based tracers and classifying sediment sources in the assessment of sediment dynamics using sediment source fingerprinting. J Environ Qual. Doi:10.2134/jeq2015.01.0043 Koiter AJ et al. (2013). Investigating the role of connectivity and scale in assessing the sources of sediment in an agricultural watershed in the Canadian prairies using sediment source fingerprinting. J Soils Sediments, 13, 1676-1691.

Provenance, tectonic setting and age of the sediments of the Upper Disang Formation in the Phek District, Nagaland

NASA Astrophysics Data System (ADS)

Imchen, Watitemsu; Thong, Glenn T.; Pongen, Temjenrenla

2014-07-01

Integrated petrographic and geochemical studies of sandstones, and geochemical studies of shales of turbidites from the Upper Disang Formation, Phek district, Nagaland have been carried out to determine their provenance, weathering conditions and tectonic setting. Paleomagnetic studies were carried out for magnetostratigraphic purposes. Studies indicate that most of these sediments were derived from felsic and mafic sources with minor contribution from low to medium grade metamorphic rocks. Most of the felsic components have been transported from distant sources as evidenced from extensive reworking of grains. The most likely source rocks are the granite/granite gneiss of the Karbi Anglong crystalline complex to the west of the study area. However, the bulk of the sediments have been contributed from nearby basic and ultrabasic sources. This would correspond to the fast rising Naga Ophiolite, which probably emerged above sea level during the Mid-Eocene. Prevailing high temperatures and humid climate caused intense chemical weathering of the source rocks. The sediments from the west were transported great distances by turbidity currents into an easterly deepening basin. Sediments from the nearby east were rapidly dumped on the seafloor causing rapid mixing, leading to textural and chemical immaturity. Paleomagnetic studies endorse published paleontological evidence to indicate that most of the sediments of the Upper Disang Formation were deposited during the Late Eocene. Deposition took place in a westward-migrating accretionary-prism complex in an active-margin setting at the convergence of the Indian and Burma plates. This was a rapidly-closing basin where anoxic conditions prevailed. Towards the end of the Eocene this basin closed completely with the destruction of the Tethyan Ocean.

Primary sources and toxicity of PAHs in Milwaukee-area streambed sediment

USGS Publications Warehouse

Baldwin, Austin K.; Corsi, Steven R.; Lutz, Michelle A.; Ingersoll, Christopher G.; Dorman, Rebecca A.; Magruder, Christopher; Magruder, Matthew

2017-01-01

High concentrations of polycyclic aromatic hydrocarbons (PAHs) in streams can be a significant stressor to aquatic organisms. To understand the likely sources and toxicity of PAHs in Milwaukee-area streams, streambed sediment samples from 40 sites and parking lot dust samples from 6 sites were analyzed for 38 parent PAHs and 25 alkylated PAHs. Diagnostic ratios, profile correlations, principal components analysis, source-receptor modeling, and mass fractions analysis were used to identify potential PAH sources to streambed sediment samples, and land-use analysis was used to relate streambed sediment PAH concentrations to different urban-related land uses. On the basis of this multiple lines-of-evidence approach, coal-tar pavement sealant was indicated as the primary source of PAHs in a majority of streambed sediment samples, contributing an estimated 77% of total PAHs to samples, on average. Comparison to the Probable Effect Concentrations and (or) the Equilibrium Partitioning Sediment Benchmark indicates that 78% of stream sediment samples are likely to cause adverse effects to benthic organisms. Laboratory toxicity tests on a 16-sample subset of the streambed sites using the amphipod Hyalella azteca (28-day) and the midge Chironomus dilutus (10-day) measured significant reductions in one or more biological endpoints, including survival, in 75% of samples, with H. azteca more responsive than C. dilutus.

A preliminary assessment of the spatial sources of contemporary suspended sediment in the Ohio River basin, United States, using water quality data from the NASQAN programme in a source tracing procedure

USGS Publications Warehouse

Zhang, Y.-S.; Collins, A.L.; Horowitz, A.J.

2012-01-01

Reliable information on catchment scale suspended sediment sources is required to inform the design of management strategies for helping abate the numerous environmental issues associated with enhanced sediment mobilization and off-site loadings. Since sediment fingerprinting techniques avoid many of the logistical constraints associated with using more traditional indirect measurement methods at catchment scale, such approaches have been increasingly reported in the international literature and typically use data sets collected specifically for sediment source apportionment purposes. There remains scope for investigating the potential for using geochemical data sets assembled by routine monitoring programmes to fingerprint sediment provenance. In the United States, routine water quality samples are collected as part of the US Geological Survey's revised National Stream Quality Accounting Network programme. Accordingly, the geochemistry data generated from these samples over a 10-year period (1996-2006) were used as the basis for a fingerprinting exercise to assess the key tributary sub-catchment spatial sources of contemporary suspended sediment transported by the Ohio River. Uncertainty associated with the spatial source estimates was quantified using a Monte Carlo approach in conjunction with mass balance modelling. Relative frequency weighted means were used as an alternative way of summarizing the spatial source contributions, thereby avoiding the need to use confidence limits. The results should be interpreted in the context of the routine, but infrequent nature, of the suspended sediment samples used to assemble geochemistry as a basis for the sourcing exercise. Nonetheless, the study demonstrates how routine monitoring samples can be used to provide some preliminary information on sediment provenance in large drainage basins. ?? 2011 John Wiley & Sons, Ltd.

Storms, channel changes, and a sediment budget for an urban-suburban stream, Difficult Run, Virginia, USA

USGS Publications Warehouse

Gellis, Allen C.; Myers, Michael; Noe, Gregory; Hupp, Cliff R.; Shenk, Edward; Myers, Luke

2017-01-01

Determining erosion and deposition rates in urban-suburban settings and how these processes are affected by large storms is important to understanding geomorphic processes in these landscapes. Sediment yields in the suburban and urban Upper Difficult Run are among the highest ever recorded in the Chesapeake Bay watershed, ranging from 161 to 376 Mg/km2/y. Erosion and deposition of streambanks, channel bed, and bars and deposition of floodplains were monitored between 1 March 2010 and 18 January 2013 in Upper Difficult Run, Virginia, USA. We documented the effects of two large storms, Tropical Storm Lee (September 2011), a 100-year event, and Super Storm Sandy (October 2012) a 5-year event, on channel erosion and deposition. Variability in erosion and deposition rates for all geomorphic features, temporally and spatially, are important conclusions of this study. Tropical Storm Lee was an erosive event, where erosion occurred on 82% of all streambanks and where 88% of streambanks that were aggrading before Tropical Storm Lee became erosional. Statistical analysis indicated that drainage area explains linear changes (cm/y) in eroding streambanks and that channel top width explains cross-sectional area changes (cm2/y) in eroding streambanks and floodplain deposition (mm/y). A quasi-sediment budget constructed for the study period using the streambanks, channel bed, channel bars, and floodplain measurements underestimated the measured suspended-sediment load by 61% (2130 Mg/y). Underestimation of the sediment load may be caused by measurement errors and to contributions from upland sediment sources, which were not measured but estimated at 36% of the gross input of sediment. Eroding streambanks contributed 42% of the gross input of sediment and accounted for 70% of the measured suspended-sediment load. Similar to other urban watersheds, the large percentage of impervious area in Difficult Run and direct runoff of precipitation leads to increased streamflow and streambank erosion. This study emphasizes the importance of streambanks in urban-suburban sediment budgets but also suggests that other sediment sources, such as upland sources, which were not measured in this study, can be an important source of sediment.

Influence of coal-tar sealcoat and other carbonaceous materials on polycyclic aromatic hydrocarbon loading in an urban watershed

USGS Publications Warehouse

Yang, Y.; Van Metre, P.C.; Mahler, B.J.; Wilson, J.T.; Ligouis, B.; Razzaque, M.; Schaeffer, D.J.; Werth, C.J.

2010-01-01

Carbonaceous material (CM) particles are the principal vectors transporting polycyclic aromatic hydrocarbons (PAHs) into urban waters via runoff; however, characteristics of CM particles in urban watersheds and their relative contributions to PAH contamination remain unclear. Our objectives were to identify the sources and distribution of CM particles in an urban watershed and to determine the types of CMs that were the dominant sources of PAHs in the lake and stream sediments. Samples of soils, parking lot and street dust, and streambed and lake sediment were collected from the Lake Como watershed in Fort Worth, Texas. Characteristics of CM particles determined by organic petrography and a significant correlation between PAH concentrations and organic carbon in coal tar, asphalt, and soot indicate that these three CM particle types are the major sources and carriers of PAHs in the watershed. Estimates of the distribution of PAHs in CM particles indicate that coal-tar pitch, usedinsomepavementsealcoats, isadominant source of PAHs in the watershed, and contributes as much as 99% of the PAHs in sealed parking lot dust, 92% in unsealed parking lot dust, 88% in commercial area soil, 71% in streambed sediment, and 84% in surficial lake sediment. ?? 2010 American Chemical Society.

Effects of nutrient load on microbial activities within a seagrass-dominated ecosystem: Implications of changes in seagrass blue carbon.

PubMed

Liu, Songlin; Jiang, Zhijian; Wu, Yunchao; Zhang, Jingping; Arbi, Iman; Ye, Feng; Huang, Xiaoping; Macreadie, Peter Ian

2017-04-15

Nutrient loading is a leading cause of global seagrass decline, triggering shifts from seagrass- to macroalgal-dominance. Within seagrass meadows of Xincun Bay (South China Sea), we found that nutrient loading (due to fish farming) increased sediment microbial biomass and extracellular enzyme activity associated with carbon cycling (polyphenol oxidase, invertase and cellulase), with a corresponding decrease in percent sediment organic carbon (SOC), suggesting that nutrients primed microorganism and stimulated SOC remineralization. Surpisingly, however, the relative contribution of seagrass-derived carbon to bacteria (δ 13 C bacteria ) increased with nutrient loading, despite popular theory being that microbes switch to consuming macroalgae which are assumed to provide a more labile carbon source. Organic carbon sources of fungi were unaffected by nutrient loading. Overall, this study suggests that nutrient loading changes the relative contribution of seagrass and algal sources to SOC pools, boosting sediment microbial biomass and extracellular enzyme activity, thereby possibly changing seagrass blue carbon. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tracking sediment through the Holocene: Determining anthropogenic contributions to a sediment-rich agricultural system, north-central USA

NASA Astrophysics Data System (ADS)

Gran, Karen; Belmont, Patrick; Finnegan, Noah

2013-04-01

Management and restoration of sediment-impaired streams requires quantification of sediment sources and pathways of transport. Addressing the role of humans in altering the magnitude and sources of sediment supplied to a catchment is notoriously challenging. Here, we explore how humans have amplified erosion in geomorphically-sensitive portions of the predominantly-agricultural Minnesota River basin in north-central USA. In the Minnesota River basin, the primary sources of sediment are classified generally as upland agricultural field vs. near-channel sources, with near-channel sources including stream banks, bluffs, and ravines. Using aerial lidar data, repeat terrestrial lidar scans of bluffs, ravine monitoring, historic air photo analyses, and sediment fingerprinting, we have developed a sediment budget to determine the relative importance of each source in a tributary to the Minnesota River, the Le Sueur River. We then investigate how these sources have changed through time, from changes evident over the past few decades to changes associated with valley evolution over the past 13,400 years. The Minnesota River valley was carved ~13,400 years ago through catastrophic drainage of glacial Lake Agassiz. As the Minnesota River valley incised, knickpoints have migrated upstream into tributaries, carving out deep valleys where the most actively eroding near-channel sediment sources occur. The modern sediment budget, closed for the time period 2000 to 2010, shows that the majority of the fine sediment load in the Le Sueur River comes from bluffs and other near-channel sources in the deeply-incised knick zone. Numerical modeling of valley evolution constrained by mapped and dated strath terraces cut into the glacial till presents an opportunity to compare the modern sediment budget to that of the river prior to anthropogenic modification. This comparison reveals a natural background or "pre-agriculture" rate of erosion from near-channel sources to be 3-5 times lower than modern near-channel erosion rates. Notably, depositional records from a naturally-dammed lake downstream on the upper Mississippi River show a more dramatic 10-fold increase in deposition rates from pre-agricultural times to the present. Sediment fingerprinting shows that pre-agriculture sediment loads were dominated by near-channel sediment sources. As deposition rates rose in the late 1800s and early 1900s, the sources shifted increasingly to agricultural soil erosion. In the past few decades, deposition rates have remained high, but sediment fingerprinting indicates yet another significant shift back to near-channel sources. On-going changes in basin hydrology, from both installation of agricultural drainage systems and on-going climate change have put more water in the rivers, increasing rates of near-channel bank and bluff erosion. This most recent shift in sediment sources has significant implications for turbidity management in the Minnesota River basin.

Quantifying sediment source contributions in coastal catchments impacted by the Fukushima nuclear accident with carbon and nitrogen elemental concentrations and stable isotope ratios

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick; Huon Huon, Sylvain; Onda, Yuichi; Evrard, Olivier

2016-04-01

The Fukushima Dai-ichi Nuclear Power Plant accidental release of radioactive contaminants resulted in the significant fallout of radiocesium over several coastal catchments in the Fukushima Prefecture. Radiocesium, considered to be the greatest risk to the short and long term health of the local community, is rapidly bound to fine soil particles and thus is mobilized and transported during soil erosion and runoff processes. As there has been a broad-scale decontamination of rice paddy fields and rural residential areas in the contaminated region, one important long term question is whether there is, or may be, a downstream transfer of radiocesium from forests that covered over 65% of the most contaminated region. Accordingly, carbon and nitrogen elemental concentrations and stable isotope ratios are used to determine the relative contributions of forests and rice paddies to transported sediment in three contaminated coastal catchments. Samples were taken from the three main identified sources: cultivated soils (rice paddies and fields, n=30), forest soils (n=45), and subsoils (channel bank and decontaminated soils, n = 25). Lag deposit sediment samples were obtained from five sampling campaigns that targeted the main hydrological events from October 2011 to October 2014. In total, 86 samples of deposited sediment were analyzed for particulate organic matter elemental concentrations and isotope ratios, 24 from the Mano catchment, 44 from the Niida catchment, and 18 from the Ota catchment. Mann-Whitney U-tests were used to examine the source discrimination potential of this tracing suite and select the appropriate tracers for modelling. The discriminant tracers were modelled with a concentration-dependent distribution mixing model. Preliminary results indicate that cultivated sources (predominantly rice paddies) contribute disproportionately more sediment per unit area than forested regions in these contaminated catchments. Future research will examine if there are areas in particular where forest sources have elevated concentrations and may require some attention in the decontamination and monitoring of potential radiocesium downstream transfers.

Sediment Quality and Comparison to Historical Water Quality, Little Arkansas River Basin, South-Central Kansas, 2007

USGS Publications Warehouse

Juracek, Kyle E.; Rasmussen, Patrick P.

2008-01-01

The spatial and temporal variability in streambed-sediment quality and its relation to historical water quality was assessed to provide guidance for the development of total maximum daily loads and the implementation of best-management practices in the Little Arkansas River Basin, south-central Kansas. Streambed-sediment samples were collected at 26 sites in 2007, sieved to isolate the less than 63-micron fraction (that is, the silt and clay), and analyzed for selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, and the radionuclides beryllium-7, cesium-137, lead-210, and radium-226. At eight sites, streambed-sediment samples also were collected and analyzed for bacteria. Particulate nitrogen, phosphorus, and organic carbon concentrations in the streambed sediment varied substantially spatially and temporally, and positive correlations among the three constituents were statistically significant. Along the main-stem Little Arkansas River, streambed-sediment concentrations of particulate nitrogen and phosphorus generally were larger at and downstream from Alta Mills, Kansas. The largest particulate nitrogen concentrations were measured in samples collected in the Emma Creek subbasin and may be related to livestock and poultry production. The largest particulate phosphorus concentrations in the basin were measured in samples collected along the main-stem Little Arkansas River downstream from Alta Mills, Kansas. Particulate nitrogen, phosphorus, and organic carbon content in the water and streambed-sediment samples typically decreased as streamflow increased. This inverse relation may be caused by an increased contribution of sediment from channel-bank sources during high flows and (or) increased particle sizes transported by the high flows. Trace element concentrations in the streambed sediment varied from site to site and typically were less than threshold-effects guidelines for possible adverse biological effects. The largest copper, lead, silver, and zinc concentrations, measured for a sample collected from Sand Creek downstream from Newton, Kansas, likely were related to urban sources of contamination. Radionuclide activities and bacterial densities in the streambed sediment varied throughout the basin. Variability in the former may be indicative of subbasin differences in the contribution of sediment from surface-soil and channel-bank sources. Streambed sediment may be useful for reconnaissance purposes to determine sources of particulate nitrogen, phosphorus, organic carbon, and other sediment-associated constituents in the basin. If flow conditions prior to streambed-sediment sampling and during water-quality sampling are considered, it may be possible to use streambed sediment as an indicator of water quality for nitrogen, phosphorus, and organic carbon. Flow conditions affect sediment-associated constituent concentrations in streambed-sediment and water samples, in part, because the sources of sediment (surface soils, channel banks) can vary with flow as can the size of the particles transported.

Combined use of radiocarbon and stable carbon isotope to constrain the sources and cycling of particulate organic carbon in a large freshwater lake, China.

PubMed

Chen, Jingan; Yang, Haiquan; Zeng, Yan; Guo, Jianyang; Song, Yilong; Ding, Wei

2018-06-01

The concentrations and isotopic compositions of dissolved inorganic carbon (DIC) and particulate organic carbon (POC) were measured in order to better constrain the sources and cycling of POC in Lake Fuxian, the largest deep freshwater lake in China. Model results based on the combined δ 13 C and Δ 14 C, showed that the average lake-wide contributions of autochthonous POC, terrestrial POC, and resuspended sediment POC to the bulk POC in Lake Fuxian were 61%, 22%, and 17%, respectively. This indicated autochthonous POC might play a dominant role in sustaining large oligotrophic lake ecosystem. A mean 17% contribution of resuspended sediment POC to the bulk POC implied that sediment might have more significant influence on aquatic environment and ecosystem than previously recognized in large deep lakes. The contributions of different sources POC to the water-column POC were a function of the initial composition of the source materials, photosynthesis, physical regime of the lake, sediment resuspension, respiration and degradation of organic matter, and were affected indirectly by environmental factors such as light, temperature, DO, wind speed, turbidity, and nutrient concentration. This study is not only the first systematic investigation on the radiocarbon and stable isotope compositions of POC in large deep freshwater lake in China, but also one of the most extensive radiocarbon studies on the ecosystem of any great lakes in the world. The unique data constrain relative influences of autochthonous POC, terrestrial POC, and resuspended sediment POC, and deepen the understanding of the POC cycling in large freshwater lakes. This study is far from comprehensive, but it serves to highlight the potential of combined radiocarbon and stable carbon isotope for constraining the sources and cycling of POC in large lake system. More radiocarbon investigations on the water-column POC and the aquatic food webs are necessary to illuminate further the fate of autochthonous POC, terrestrial POC, and resuspended sediment POC, and their eco-environmental effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimating Sediment Losses Generated from Highway Cut and Fill Slopes in the Lake Tahoe Basin

DOT National Transportation Integrated Search

2014-12-01

Lake Tahoes famed water clarity has gradually declined over the last 50 years, partially as a result of fine sediment particle (FSP, < 16 micrometers in diameter) contributions from urban stormwater. Of these urban sources, highway cut and fill sl...

Study of sediment movement in an irrigated maize-cotton system combining rainfall simulations, sediment tracers and soil erosion models

NASA Astrophysics Data System (ADS)

Guzmán, Gema; Laguna, Ana; Cañasveras, Juan Carlos; Boulal, Hakim; Barrón, Vidal; Gómez-Macpherson, Helena; Giráldez, Juan Vicente; Gómez, José Alfonso

2015-05-01

Although soil erosion is one of the main threats to agriculture sustainability in many areas of the world, its processes are difficult to measure and still need a better characterization. The use of iron oxides as sediment tracers, combined with erosion and mixing models opens up a pathway for improving the knowledge of the erosion and redistribution of soil, determining sediment sources and sinks. In this study, magnetite and a multivariate mixing model were used in rainfall simulations at the micro-plot scale to determine the source of the sediment at different stages of a furrow-ridge system both with (+T) and without (-T) wheel tracks. At a plot scale, magnetite, hematite and goethite combined with two soil erosion models based on the kinematic wave approach were used in a sprinkler irrigation test to study trends in sediment transport and tracer dynamics along furrow lengths under a wide range of scenarios. In the absence of any stubble cover, sediment contribution from the ridges was larger than the furrow bed one, almost 90%, while an opposite trend was observed with stubble, with a smaller contribution from the ridge (32%) than that of the bed, at the micro-plot trials. Furthermore, at a plot scale, the tracer concentration analysis showed an exponentially decreasing trend with the downstream distance both for sediment detachment along furrows and soil source contribution from tagged segments. The parameters of the distributed model KINEROS2 have been estimated using the PEST Model to obtain a more accurate evaluation. Afterwards, this model was used to simulate a broad range of common scenarios of topography and rainfall from commercial farms in southern Spain. Higher slopes had a significant influence on sediment yields while long furrow distances allowed a more efficient water use. For the control of runoff, and therefore soil loss, an equilibrium between irrigation design (intensity, duration, water pattern) and hydric needs of the crops should be defined in order to establish a sustainable management strategy.

The relative contribution of near-bed vs. intragravel horizontal transport to fine sediment accumulation processes in river gravel beds

NASA Astrophysics Data System (ADS)

Casas-Mulet, Roser; Lakhanpal, Garima; Stewardson, Michael J.

2018-02-01

Understanding flow-sediment interactions is important for comprehending river functioning. Fine sediment accumulation processes, in particular, have key implications for ecosystem health. However, the amount of fines generated by intragravel flows and later accumulated in gravel streambeds may have been underestimated, as the hydraulic-related driving transport mechanisms in play are not clearly identified. Specifically, the relative contribution of fines from upper vs. lower sediment layers in gravel beds is not well understood. By recreating flooded and dewatered conditions in an experimental flume filled with natural sediment, we estimated such contributions by observing and collecting intragravel transported fines that were later accumulated into a void in the middle of the sediment matrix. Near-bed transport in the upper sediment layers (named Brinkman load) during flooded conditions accounted for most (90%) of the accumulated fines. Intragravel transport in the lower sediment layers (named Interstitial load) was the sole source of transport and accumulation during dewatered conditions with steeper hydraulic gradients. Interstitial load accounted for 10% of the total transport during flooded conditions. Although small, such estimations demonstrate that hydraulic-gradient transport in the lower sediment layers occurs in spite of the contradicting analytical assessments. We provide a case study to challenge the traditional approaches of assessing intragravel transport, and a useful framework to understand the origin and relative contribution of fine sediment accumulation in gravel beds. Such knowledge will be highly useful for the design of monitoring programs aiding river management, particularly in regulated rivers.

Large shift in source of fine sediment in the upper Mississippi River

USGS Publications Warehouse

Belmont, P.; Gran, K.B.; Schottler, S.P.; Wilcock, P.R.; Day, S.S.; Jennings, C.; Lauer, J.W.; Viparelli, E.; Willenbring, J.K.; Engstrom, D.R.; Parker, G.

2011-01-01

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land use that alter the drivers of sediment supply. Previous studies in Lake Pepin, a natural lake on the Mississippi River, indicate that sediment supply to the lake has increased 10-fold over the past 150 years. Herein we combine geochemical fingerprinting and a suite of geomorphic change detection techniques with a sediment mass balance for a tributary watershed to demonstrate that, although the sediment loading remains very large, the dominant source of sediment has shifted from agricultural soil erosion to accelerated erosion of stream banks and bluffs, driven by increased river discharge. Such hydrologic amplification of natural erosion processes calls for a new approach to watershed sediment modeling that explicitly accounts for channel and floodplain dynamics that amplify or dampen landscape processes. Further, this finding illustrates a new challenge in remediating nonpoint sediment pollution and indicates that management efforts must expand from soil erosion to factors contributing to increased water runoff. ?? 2011 American Chemical Society.

Biomarkers and isotopic fingerprinting to track sediment origin and connectivity at Baldegg Lake (Switzerland)

NASA Astrophysics Data System (ADS)

Lavrieux, Marlène; Meusburger, Katrin; Birkholz, Axel; Alewell, Christine

2017-04-01

Slope destabilization and associated sediment transfer are among the major causes of aquatic ecosystems and surface water quality impairment. Through land uses and agricultural practices, human activities modify the soil erosive risk and the catchment connectivity, becoming a key factor of sediment dynamics. Hence, restoration and management plans of water bodies can only be efficient if the sediment sources and the proportion attributable to different land uses and agricultural practices are identified. Several sediment fingerprinting methods, based on the geochemical (elemental composition), color, magnetic or isotopic (137Cs) sediment properties, are currently in use. However, these tools are not suitable for a land-use based fingerprinting. New organic geochemical approaches are now developed to discriminate source-soil contributions under different land-uses: The compound-specific stable isotopes (CSSI) technique, based on the biomarkers isotopic signature (here, fatty acids δ13C) variability within the plant species, The analysis of highly specific (i.e. source-family- or even source-species-specific) biomarkers assemblages, which use is until now mainly restricted to palaeoenvironmental reconstructions, and which offer also promising prospects for tracing current sediment origin. The approach was applied to reconstruct the spatio-temporal variability of the main sediment sources of Baldegg Lake (Lucern Canton, Switzerland), which suffers from a substantial eutrophication, despite several restoration attempts during the last 40 years. The sediment supplying areas and the exported volumes were identified using CSSI technique and highly specific biomarkers, coupled to a sediment connectivity model. The sediment origin variability was defined through the analysis of suspended river sediments sampled at high flow conditions (short term), and by the analysis of a lake sediment core covering the last 130 years (long term). The results show the utility of biomarkers and CSSI to track organic sources in contrasted land-use settings. Associated to other fingerprinting methods, this approach could in the future become a decision support tool for catchments management.

Characterisation of organic matter source and sediment distribution in Ashtamudi Estuary, southern India

NASA Astrophysics Data System (ADS)

Kumar, Prem; Ankit, Yadav; Mishra, Praveen K.; Jha, Deepak Kumar; Anoop, Ambili

2017-04-01

In the present study we have focussed on the surface sediments of Ashtamudi Estuary (southern India) to understand (i) the fate and sources of organic matter by investigating lipid biomarker (n-alkanes) distribution in modern sediments and vegetation samples and (ii) the processes controlling the sediment distribution into the lake basin using end-member modelling approach. The sediment n-alkanes from the Ashtamudi Estuary exhibit a pronounced odd over even predominance with maxima at C29 and C31 chain length indicative of a dominant terrestrial contribution. A number of n-alkane indices have been calculated to illustrate the variability in space by considering separately the river dominated northern reaches and tidal influenced southern part of Ashtamudi Estuary. The highest terrigenous organic contents were found in sediments from the river and upper bay sites, with smaller contributions to the lower parts of the estuary. The Paq and TAR (terrigenous/aquatic ratio) indices demonstrate maximum aquatic productivity (plankton growth and submerged macrophytes) in the tidal dominated region of the Ashtamudi Estuary. The carbon preference index (CPI) and average chain length (ACL) provide evidence for high petrogenic organic inputs in the tidal zone, whereas dominant biogenic contribution have been observed in the riverine zone. In addition, the end member modeling of the grain size distribution of the surface sediment samples enabled us to decipher significant sedimentological processes affecting the sediment distribution in the estuarine settings. The end-member distribution showing highest loading with the coarser fraction is maximum where estuary debouches into the sea. However, the samples near the mouth of the river shows finer fraction of the end-member.

Sediment tracing in the upper Hunter catchment using elemental and mineralogical compositions: Implications for catchment-scale suspended sediment (dis)connectivity and management

NASA Astrophysics Data System (ADS)

Fryirs, Kirstie; Gore, Damian

2013-07-01

River bed colmation layers clog the interstices of gravel-bed rivers, impeding the vertical exchange of water and nutrients that drives ecosystem function in the hyporheic zone. In catchments where fine-grained sediment supply has increased since human disturbance, understanding sediment provenance and the (dis)connectivity of supply allows practitioners to target sediment source problems and treat them within catchment management plans. Release of alluvial fine-grained sediment from channel bank erosion since European settlement has resulted in the formation of a colmation layer along the upper Hunter River at Muswellbrook, eastern Australia. X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD) are used to determine the elemental and mineralogical signatures of colmation layer and floodplain sediment sources across this 4480 km2 catchment. This sediment tracing technique is used to construct a picture of how suspended sediment supply and (dis)connectivity operates in this catchment. In this system, the primary source areas are subcatchments in which sediments are stored largely in partly confined floodplain pockets, but from which sediment supply is unimpeded and directly connected to the receiving reach. Subcatchments in which alluvial sediment storage is significant — and which contain large, laterally unconfined valleys — are essentially 'switched off' or disconnected from the receiving reach. This is because large sediment sinks act to trap fine-grained sediment before it reaches the receiving reach, forming a buffer along the sediment conveyor belt. Given the age structure of floodplains in the receiving reach, this pattern of source area contributions and (dis)connectivity must have occurred throughout the Holocene.

Organic matter in sediment layers of an acidic mining lake as assessed by lipid analysis. Part II: Neutral lipids.

PubMed

Poerschmann, Juergen; Koschorreck, Matthias; Górecki, Tadeusz

2017-02-01

Natural neutralization of acidic mining lakes is often limited by organic matter. The knowledge of the sources and degradability of organic matter is crucial for understanding alkalinity generation in these lakes. Sediments collected at different depths (surface sediment layer from 0 to 1 cm and deep sediment layer from 4 to 5cm) from an acidic mining lake were studied in order to characterize sedimentary organic matter based on neutral signature markers. Samples were exhaustively extracted, subjected to pre-chromatographic derivatizations and analyzed by GC/MS. Herein, molecular distributions of diagnostic alkanes/alkenes, terpenes/terpenoids, polycyclic aromatic hydrocarbons, aliphatic alcohols and ketones, sterols, and hopanes/hopanoids were addressed. Characterization of the contribution of natural vs. anthropogenic sources to the sedimentary organic matter in these extreme environments was then possible based on these distributions. With the exception of polycyclic aromatic hydrocarbons, combined concentrations across all marker classes proved higher in the surface sediment layer as compared to those in the deep sediment layer. Alkane and aliphatic alcohol distributions pointed to predominantly allochthonous over autochthonous contribution to sedimentary organic matter. Sterol patterns were dominated by phytosterols of terrestrial plants including stigmasterol and β-sitosterol. Hopanoid markers with the ββ-biohopanoid "biological" configuration were more abundant in the surface sediment layer, which pointed to higher bacterial activity. The pattern of polycyclic aromatic hydrocarbons pointed to prevailing anthropogenic input. Pyrolytic makers were likely to due to atmospheric deposition from a nearby former coal combustion facility. The combined analysis of the array of biomarkers provided new insights into the sources and transformations of organic matter in lake sediments. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of suspended-sediment concentrations and radioisotope levels in the Wild Rice River basin, northwestern Minnesota, 1973-98

USGS Publications Warehouse

Brigham, Mark E.; McCullough, Carolyn J.; Wilkinson, Philip M.

2001-01-01

We examined historical suspended-sediment data and activities of fallout radioisotopes (lead-210 [210Pb], cesium-137 [137Cs], and beryllium-7 [7Be]) associated with suspended sediments and source-area sediments (cultivated soils, bank material, and reference soils) in the Wild Rice River Basin, a tributary to the Red River of the North, to better understand sources of suspended sediment to streams in the region. Multiple linear regression analysis of suspended-sediment concentrations from the Wild Rice River at Twin Valley, Minnesota indicated significant relations between suspended-sediment concentrations and streamflow. Flow-adjusted sediment concentrations tended to be slightly higher in spring than summer-autumn. No temporal trends in concentration were observed during 1973-98. The fallout radioisotopes were nearly always detectable in suspended sediments during spring-summer 1998. Mean 210Pb and 7Be activities in suspended sediment and surficial, cultivated soils were similar, perhaps indicating little dilution of suspended sediment from low-isotopic-activity bank sediments. In contrast, mean 137Cs activities in suspended sediment indicated a mixture of sediment originating from eroded soils and from eroded bank material, with bank material being a somewhat more important source upstream of Twin Valley, Minnesota; and approximately equal fractions of bank material and surficial soils contributing to the suspended load downstream at Hendrum, Minnesota. This study indicates that, to be effective, efforts to reduce sediment loading to the Wild Rice River should include measures to control soil erosion from cultivated fields.

MERCURY IN METAL ORE DEPOSITS: AN UNRECOGNIZED, WIDESPREAD SOURCE TO LAKE SUPERIOR SEDIMENTS, CONTRIBUTION #1072

EPA Science Inventory

Mining operations have worked the rich mineral resources of the Lake Superior Basin for over 150 years, leaving industrially impacted regions with tailing piles and smelters. In Lake Superior sediments, mercury and copper inventories increase towards shorelines and are highly cor...

Effect of topographic characteristics on compound topographic index for identification of gully channel initiation locations

USDA-ARS?s Scientific Manuscript database

Sediment loads from gully erosion can be a significant sediment source within watershed resulting in major contributions to water quality problems, reduction of crop productivity by removal of nutrient rich top soil, and damaging downstream ecosystems. Areas containing a high probability of forming ...

Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China.

PubMed

Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

2016-03-07

Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively.

Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

NASA Astrophysics Data System (ADS)

Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

2016-03-01

Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively.

Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011-2015)

NASA Astrophysics Data System (ADS)

Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Wakiyama, Yoshifumi; Jaegler, Hugo; Lefèvre, Irène

2016-10-01

Fallout from the Fukushima Dai-ichi nuclear power plant accident resulted in a 3000-km2 radioactive contamination plume. Here, we model the progressive dilution of the radiocesium contamination in 327 sediment samples from two neighboring catchments with different timing of soil decontamination. Overall, we demonstrate that there has been a ~90% decrease of the contribution of upstream contaminated soils to sediment transiting the coastal plains between 2012 (median - M - contribution of 73%, mean absolute deviation - MAD - of 27%) and 2015 (M 9%, MAD 6%). The occurrence of typhoons and the progress of decontamination in different tributaries of the Niida River resulted in temporary increases in local contamination. However, the much lower contribution of upstream contaminated soils to coastal plain sediment in November 2015 demonstrates that the source of the easily erodible, contaminated material has potentially been removed by decontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean.

Use of Composite Fingerprinting Technique to Determine Contribution of Paria River Sediments to Dam-Release Flood Deposits in Marble Canyon, Grand Canyon, Az

NASA Astrophysics Data System (ADS)

Chapman, K.; Parnell, R. A.; Smith, M. E.; Grams, P. E.; Mueller, E. R.

2015-12-01

The 1963 closure of Glen Canyon Dam drastically reduced the downstream sediment supply and altered daily flow regimes of the Colorado River through Grand Canyon, resulting in significant sandbar erosion downstream of the dam. Dam-release floods, known as High Flow Experiments (HFEs), have occurred six times since 1996 and are intended to rebuild Grand Canyon sandbars using tributary-supplied sediment. In Marble Canyon (first 100 km of Grand Canyon) the targeted tributary is the Paria River which supplies approximately 90% of the annual suspended sediment flux through Marble Canyon; the same input contributed less than 6% prior to the dam. Annual topographic surveys have established that HFEs are effective at rebuilding sandbars. However, the long-term viability of using HFEs for sandbar maintenance is dependent on a sustainable source of sediments comprising HFE deposits. Significant use of non-tributary, main-stem sediments (i.e. pre-dam sand stored in eddies or the channel bed) in HFE deposits would indicate reliance on a limited resource, and diminishing returns in the ability of HFEs to rebuild sandbars. In this study, we sampled vertically throughout 12 bars in Marble Canyon to document temporal and downstream changes in the proportion of sediment sourced from the Paria River during the 2013 and 2014 HFEs. Preliminary data suggest that heavy mineral compositions and concentrations of Ti, S, Cr and Rb, all of which are influenced by grainsize, could be sufficiently capable of differentiating Paria-derived and main-stem sediments when combined into a composite fingerprint (CF). A multivariate mixing model using these CFs quantitatively determines the contribution of Paria-derived sediment in each HFE deposit sample. Mixing model endmembers for non-Paria sand include pre-dam flood deposits in Glen and Marble Canyons, and Marble Canyon dredge samples. These results elucidate the role of contemporary versus legacy sediment in long-term sandbar maintenance.

Vertical profile, source apportionment, and toxicity of PAHs in sediment cores of a wharf near the coal-based steel refining industrial zone in Kaohsiung, Taiwan.

PubMed

Chen, Chih-Feng; Chen, Chiu-Wen; Ju, Yun-Ru; Dong, Cheng-Di

2016-03-01

Three sediment cores were collected from a wharf near a coal-based steel refining industrial zone in Kaohsiung, Taiwan. Analyses for 16 polycyclic aromatic hydrocarbons (PAHs) of the US Environmental Protection Agency priority list in the core sediment samples were conducted using gas chromatography-mass spectrometry. The vertical profiles of PAHs in the core sediments were assessed, possible sources and apportionment were identified, and the toxicity risk of the core sediments was determined. The results from the sediment analyses showed that total concentrations of the 16 PAHs varied from 11774 ± 4244 to 16755 ± 4593 ng/g dry weight (dw). Generally, the vertical profiles of the PAHs in the sediment cores exhibited a decreasing trend from the top to the lower levels of the S1 core and an increasing trend of PAHs from the top to the lower levels of the S2 and S3 cores. Among the core sediment samples, the five- and six-ring PAHs were predominantly in the S1 core, ranging from 42 to 54 %, whereas the composition of the PAHs in the S2 and S3 cores were distributed equally across three groups: two- and three-ring, four-ring, and five- and six-ring PAHs. The results indicated that PAH contamination at the site of the S1 core had a different source. The molecular indices and principal component analyses with multivariate linear regression were used to determine the source contributions, with the results showing that the contributions of coal, oil-related, and vehicle sources were 38.6, 35.9, and 25.5 %, respectively. A PAH toxicity assessment using the mean effect range-median quotient (m-ERM-q, 0.59-0.79), benzo[a]pyrene toxicity equivalent (TEQ(carc), 1466-1954 ng TEQ/g dw), and dioxin toxicity equivalent (TEQ(fish), 3036-4174 pg TEQ/g dw) identified the wharf as the most affected area. The results can be used for regular monitoring, and future pollution prevention and management should target the coal-based industries in this region for pollution reduction.

The contribution of particles washed from rooftops to contaminant loading to urban streams.

PubMed

Van Metre, P C; Mahler, B J

2003-09-01

Rooftops are both a source of and a pathway for contaminated runoff in urban environments. To investigate the importance of particle-associated contamination in rooftop runoff, particles washed from asphalt shingle and galvanized metal roofs at sites 12 and 102 m from a major expressway were analyzed for major and trace elements and PAHs. Concentrations and yields from rooftops were compared among locations and roofing material types and to loads monitored during runoff events in the receiving urban stream to evaluate rooftop sources and their potential contribution to stream loading. Concentrations of zinc, lead, pyrene, and chrysene on a mass per mass basis in a majority of rooftop samples exceeded established sediment quality guidelines for probable toxicity of bed sediments to benthic biota. Fallout near the expressway was greater than farther away, as indicated by larger yields of all contaminants investigated, although some concentrations were lower. Metal roofing was a source of cadmium and zinc and asphalt shingles a source of lead. The contribution of rooftop washoff to watershed loading was estimated to range from 6 percent for chromium and arsenic to 55 percent for zinc. Estimated contributions from roofing material to total watershed load were greatest for zinc and lead, contributing about 20 and 18 percent, respectively. The contribution from atmospheric deposition of particles onto rooftops to total watershed loads in stormwater was estimated to be greatest for mercury, contributing about 46 percent.

Distribution and Sources of Petroleum Hydrocarbons in Recent Sediments of the Imo River, SE Nigeria.

PubMed

Oyo-Ita, Inyang O; Oyo-Ita, Orok E; Dosunmu, Miranda I; Domínguez, Carmen; Bayona, Josep M; Albaigés, Joan

2016-02-01

The distribution of aliphatic and aromatic hydrocarbons in surface sediments of the lower course of the Imo River (Nigeria) was investigated to determine the sources and fate of these compounds. The aliphatic fraction is characterized by a widespread contribution of highly weathered/biodegraded hydrocarbon residues (reflected in the absence of prominent n-alkane peaks coupled with the presence of 17α(H),21β(H)-25-norhopane, an indicator of heavy hydrocarbon biodegradation) of Nigerian crude oils (confirmed by the occurrence of 18α(H)-oleanane, a compound characteristic of oils of deltaic origin). The concentrations of polycyclic aromatic hydrocarbons (PAHs) ranging from 48 to 117 ng/g dry weight (dw; ∑13PAHs) indicate a moderate pollution, possibly lowered by the sandy lithology and low organic carbon (OC) content of the sediments. Concentrations slightly decrease towards the estuary of the river, probably due to the fact that these stations are affected by tidal flushing of pollutants adsorbed on sediment particles and carried away by occasional storm to the Atlantic Ocean. A number of PAH ratios, including parent/alkylated and isomeric compounds, indicates a predominance of petrogenic sources, with a low contribution of pyrolytic inputs, particularly of fossil fuel combustion. On the basis of OC/ON (>10) and Per/ΣPAHpenta- (>10) values, a diagenetic terrigenous OC was proposed as a source of perylene to the river.

Sediment‐associated organic matter sources and sediment oxygen demand in a Special Area of Conservation (SAC): A case study of the River Axe, UK

PubMed Central

Zhang, Y.; McMillan, S.; Dixon, E. R.; Stringfellow, A.; Bateman, S.; Sear, D. A.

2017-01-01

Abstract Oxygen demand in river substrates providing important habitats for the early life stages of aquatic ecology, including lithophilous fish, can arise due to the oxidation of sediment‐associated organic matter. Oxygen depletion associated with this component of river biogeochemical cycling, will, in part, depend on the sources of such material. A reconnaissance survey was therefore undertaken to assess the relative contributions from bed sediment‐associated organic matter sources potentially impacting on the River Axe Special Area of Conservation (SAC), in SW England. Source fingerprinting, including Monte Carlo uncertainty analysis, suggested that the relative frequency‐weighted average median source contributions ranged between 19% (uncertainty range 0–82%) and 64% (uncertainty range 0–99%) for farmyard manures or slurries, 4% (uncertainty range 0–49%) and 35% (uncertainty range 0–100%) for damaged road verges, 2% (uncertainty range 0–100%) and 68% (uncertainty range 0–100%) for decaying instream vegetation, and 2% (full uncertainty range 0–15%) and 6% (uncertainty range 0–48%) for human septic waste. A reconnaissance survey of sediment oxygen demand (SOD) along the channel designated as a SAC yielded a mean SOD5 of 4 mg O2 g−1 dry sediment and a corresponding SOD20 of 7 mg O2 g−1 dry sediment, compared with respective ranges of 1–15 and 2–30 mg O2 g−1 dry sediment, measured by the authors for a range of river types across the UK. The findings of the reconnaissance survey were used in an agency (SW region) catchment appraisal exercise for informing targeted management to help protect the SAC. PMID:29527135

Normalized rare earth elements in water, sediments, and wine: identifying sources and environmental redox conditions

USGS Publications Warehouse

Piper, David Z.; Bau, Michael

2013-01-01

The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

Contribution of phytoplankton and benthic microalgae to inner shelf sediments of the north-central Gulf of Mexico

NASA Astrophysics Data System (ADS)

Grippo, M. A.; Fleeger, J. W.; Rabalais, N. N.; Condrey, R.; Carman, K. R.

2010-03-01

Marine sediment may contain both settled phytoplankton and benthic microalgae (BMA). In river-dominated, shallow continental shelf systems, spatial, and temporal heterogeneity in sediment type and water-column characteristics (e.g., turbidity and primary productivity) may promote spatial variation in the relative contribution of these two sources to the sediment organic matter pool available to benthic consumers. Here we use photosynthetic pigment analysis and microscopic examination of sediment microalgae to investigate how the biomass, composition, and degradation state of sediment-associated microalgae vary along the Louisiana (USA) inner shelf, a region strongly influenced by the Mississippi River. Three sandy shoals and surrounding muddy sediments with depths ranging from 4 to 20 m were sampled in April, August, and October 2007. Pigment composition suggested that sediment microalgae were primarily diatoms at all locations. We found no significant differences in sediment chlorophyll a concentrations (8-77 mg m -2) at the shoal and off-shoal stations. Epipelic pennate diatoms (considered indicative of BMA) made up a significantly greater proportion of sediment diatoms at sandy (50-98%) compared to more silty off-shoal stations (16-56%). The percentage of centric diatoms (indicators of settled phytoplankton) in the sediment was highest in August. Sediment total pheopigment concentrations on sandy stations (<20 mg m -2) were significantly lower than concentrations at nearby muddy stations (>40 mg m -2), suggesting differences in sediment microalgal degradation state. These observations suggest that BMA predominate in shallow sandy sediments and that phytodetritus predominates at muddy stations. Our results also suggest that the relative proportion of phytodetritus in the benthos was highest where phytoplankton biomass in the overlying water was greatest, independent of sediment type. The high biomass of BMA found on shoals suggests that benthic primary production on sandy sediments represents a potentially significant local source of sediment microalgal carbon that may be utilized by benthic consumers in continental shelf food webs.

The impact of catchment source group classification on the accuracy of sediment fingerprinting outputs.

PubMed

Pulley, Simon; Foster, Ian; Collins, Adrian L

2017-06-01

The objective classification of sediment source groups is at present an under-investigated aspect of source tracing studies, which has the potential to statistically improve discrimination between sediment sources and reduce uncertainty. This paper investigates this potential using three different source group classification schemes. The first classification scheme was simple surface and subsurface groupings (Scheme 1). The tracer signatures were then used in a two-step cluster analysis to identify the sediment source groupings naturally defined by the tracer signatures (Scheme 2). The cluster source groups were then modified by splitting each one into a surface and subsurface component to suit catchment management goals (Scheme 3). The schemes were tested using artificial mixtures of sediment source samples. Controlled corruptions were made to some of the mixtures to mimic the potential causes of tracer non-conservatism present when using tracers in natural fluvial environments. It was determined how accurately the known proportions of sediment sources in the mixtures were identified after unmixing modelling using the three classification schemes. The cluster analysis derived source groups (2) significantly increased tracer variability ratios (inter-/intra-source group variability) (up to 2122%, median 194%) compared to the surface and subsurface groupings (1). As a result, the composition of the artificial mixtures was identified an average of 9.8% more accurately on the 0-100% contribution scale. It was found that the cluster groups could be reclassified into a surface and subsurface component (3) with no significant increase in composite uncertainty (a 0.1% increase over Scheme 2). The far smaller effects of simulated tracer non-conservatism for the cluster analysis based schemes (2 and 3) was primarily attributed to the increased inter-group variability producing a far larger sediment source signal that the non-conservatism noise (1). Modified cluster analysis based classification methods have the potential to reduce composite uncertainty significantly in future source tracing studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geomorphic evolution of the Le Sueur River, Minnesota, USA, and implications for current sediment loading

USGS Publications Warehouse

Gran, K.B.; Belmont, P.; Day, S.S.; Jennings, C.; Johnson, Aaron H.; Perg, L.; Wilcock, P.R.

2009-01-01

There is clear evidence that the Minnesota River is the major sediment source for Lake Pepin and that the Le Sueur River is a major source to the Minnesota River. Turbidity levels are high enough to require management actions. We take advantage of the well-constrained Holocene history of the Le Sueur basin and use a combination of remote sensing, fi eld, and stream gauge observations to constrain the contributions of different sediment sources to the Le Sueur River. Understanding the type, location, and magnitude of sediment sources is essential for unraveling the Holocene development of the basin as well as for guiding management decisions about investments to reduce sediment loads. Rapid base-level fall at the outlet of the Le Sueur River 11,500 yr B.P. triggered up to 70 m of channel incision at the mouth. Slope-area analyses of river longitudinal profi les show that knickpoints have migrated 30-35 km upstream on all three major branches of the river, eroding 1.2-2.6 ?? 109 Mg of sediment from the lower valleys in the process. The knick zones separate the basin into an upper watershed, receiving sediment primarily from uplands and streambanks, and a lower, incised zone, which receives additional sediment from high bluffs and ravines. Stream gauges installed above and below knick zones show dramatic increases in sediment loading above that expected from increases in drainage area, indicating substantial inputs from bluffs and ravines.

Regional variations in the provenance of desert sedimentary systems: An example from the Paraná Basin, Brazil

NASA Astrophysics Data System (ADS)

Bertolini, G.; Marques, J. C.; Hartley, A. J.; Scherer, C.; Macdonald, D.; Hole, M.; Stipp Basei, M. A. A. S.; Frantz, J. C.; Rosa, A. A. S.

2017-12-01

Large desert basins (>1.000.000 km²) are likely to contain sediment derived from different sources due to variations in factors such as wind direction, sand availability, and sediment influx. Provenance analysis is key to determining sediment sources and to constrain the nature of the sediment fill in desert basins. The Cretaceous Botucatu Desert dunefield extended across a large area of the interior of the SW Gondwana and was then buried by extensive lava flows that covered the active erg. The onset of volcanic activity triggered climatic and topographic variations that changed the depositional setting, however, the aeolian system remained active during this time period. Twenty samples were collected along the southern border of the basin (Brazil and Uruguay). Heavy mineral (HM) and petrographic analyses indicate very mature sediment, with a high ZTR index and quartz dominated sandstones. Despite the regularity of high ZTR index, garnet input occurs in eastern samples. Ten samples were selected for MC-LA-ICP-MS zircon dating with the aim of comparing pre- and syn-volcanic sandstones. More than 800 detrital zircons (DZ) were analyzed and the results allowed the identification of 5 relevant peaks interpreted as: 1) Choiyoi volcanism; 2) Famatian Cycle; 3) Brazilian Cycle (BC); 4) Grenvillian Cycle (GC); 5) Transamazonic Cycle. The DZ ages from the pre and syn-volcanic sandstones show no significant variation. However, when comparing the provenance between the eastern and western areas, samples from the eastern border show a major BC contribution (61%), while the western samples contain 40%. The GC contribution is more significant in the western part of the basin (>18%), contrasting with 6% in eastern samples. The main conclusions are: 1) the DZ record reveals a distinct signature for sedimentary sources; 2) climatic and topographic changes caused by the onset of volcanic activity had no impact on DZ populations; 3) heavy mineral types are very similar in all samples, but the local presence of garnet suggests a more restricted contribution in eastern samples; 4) eastern samples also show differences in the DZ population with a more significant BC contribution. HM and DZ results show that proximal sources can modify sediment input character and changing provenance signatures in desert aeolian systems.

Distributions of polycyclic aromatic hydrocarbons in surface waters, sediments and soils of Hangzhou City, China.

PubMed

Chen, Baoliang; Xuan, Xiaodong; Zhu, Lizhong; Wang, Jing; Gao, Yanzheng; Yang, Kun; Shen, Xueyou; Lou, Baofeng

2004-09-01

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 17 surface water samples and 11 sediments of four water bodies, and 3 soils near the water-body bank in Hangzhou, China in December 2002. It was observed that the sum of PAHs concentrations ranged from 0.989 to 9.663 microg/L in surface waters, from 132.7 to 7343 ng/g dry weight in sediments, and from 59.71 to 615.8 ng/g dry weight in soils. The composition pattern of PAHs by ring size in water, sediment and soil were surveyed. Three-ring PAHs were dominated in surface waters and soils, meanwhile sediments were mostly dominated by four-ring PAHs. Furthermore, PAHs apparent distribution coefficients (K(d)) and solid f(oc)-normalized K(d) (e.g. K(oc)= K(d) / f(oc)) were calculated. The relationship between logK(oc) and logK(ow) of PAHs for field data on sediments and predicted values were compared. The sources of PAHs in different water bodies were evaluated by comparison of K (oc) values in sediments of the river downstream with that in soils. Hangzhou section of the Great Canal was heavily polluted by PAHs released from industrial wastewater in the past and now PAHs in sediment may serve as sources of PAHs in surface water. PAHs in Qiantang River were contributed from soil runoff. Municipal road runoff was mostly contributed to West Lake PAHs.

Test of a new stable isotopic fingerprinting technique (i.e. Compound Specific Stable Isotope) in an Austrian sub-catchment to establish agricultural soil source contribution to deposited sediment

NASA Astrophysics Data System (ADS)

Mbaye, Modou; Mabit, Lionel; Gibbs, Max; Meusburger, Katrin; Toloza, Arsenio; Resch, Christian; Klik, Andreas; Swales, Andrew; Alewell, Christine

2017-04-01

In order to test and refine the use of compound-specific stable isotope (CSSI) as a fingerprinting technique, an innovative study was conducted in a sub-catchment dominated by C3 plants located 60 km north of Vienna. This experimental site consists of 4 different contributing sources (i.e. 3 agricultural fields and one grassed waterway) and one sediment mixture in which the δ13C values of the bulk soil carbon and of various fatty acids (FAs) were analysed after a cost effective sampling strategy. Bi-scatterplots of all possible combinations of δ13C FAs including the bulk soil carbon δ13C showed that bulk soil carbon δ13C is a strong discriminant among the other FAs. Moreover, bulk soil carbon δ13C values highlighted the highest difference between the four sources and the δ13C values of C24 indicated significant differences for all sources while δ13C of C22 did not exhibit a significant difference between the two first sources. An additional correlation analysis revealed that the highest significant linear dependencies are between δ13C16 & δ13C18 > δ13C18 & δ13C24 > δ13C16 & δ13C24. Among the variables, the bulk soil carbon δ13C was found to be the least correlated parameter, confirming that it is the most reliable discriminator to determine the sediment origins in the mixture. To summarize, only the long chain FAs (i.e. C22 and C24) as well as the bulk soil carbon δ13C succeeded in fulfilling our multivariate statistical tests. These findings were confirmed by the mixing polygon tests and Principal Component Analysis. Using three different mixing models (i.e. Iso-source, CSSIAR v1.0 and MIXSIAR), the contribution of the different sources to the mixture were evaluated. All models highlighted that the third source (field having C3 and C4 plants in rotation) and the grassed waterway were the main contributing agricultural area representing 25-31% and 50-57% of the deposited sediment constituting the mixture, respectively.

Spatial and temporal variability of trace element concentrations in an urban subtropical watershed, Honolulu, Hawaii

USGS Publications Warehouse

Heinen, De Carlo E.; Anthony, S.S.

2002-01-01

Trace metal concentrations in soils and in stream and estuarine sediments from a subtropical urban watershed in Hawaii are presented. The results are placed in the context of historical studies of environmental quality (water, soils, and sediment) in Hawaii to elucidate sources of trace elements and the processes responsible for their distribution. This work builds on earlier studies on sediments of Ala Wai Canal of urban Honolulu by examining spatial and temporal variations in the trace elements throughout the watershed. Natural processes and anthropogenic activity in urban Honolulu contribute to spatial and temporal variations of trace element concentrations throughout the watershed. Enrichment of trace elements in watershed soils result, in some cases, from contributions attributed to the weathering of volcanic rocks, as well as to a more variable anthropogenic input that reflects changes in land use in Honolulu. Varying concentrations of As, Cd, Cu, Pb and Zn in sediments reflect about 60 a of anthropogenic activity in Honolulu. Land use has a strong impact on the spatial distribution and abundance of selected trace elements in soils and stream sediments. As noted in continental US settings, the phasing out of Pb-alkyl fuel additives has decreased Pb inputs to recently deposited estuarine sediments. Yet, a substantial historical anthropogenic Pb inventory remains in soils of the watershed and erosion of surface soils continues to contribute to its enrichment in estuarine sediments. Concentrations of other elements (e.g., Cu, Zn, Cd), however, have not decreased with time, suggesting continued active inputs. Concentrations of Ba, Co, Cr, Ni, V and U, although elevated in some cases, typically reflect greater proportions attributed to natural sources rather than anthropogenic input. ?? 2002 Elsevier Science Ltd. All rights reserved.

Mapping, Monitoring, and Modeling Geomorphic Processes to Identify Sources of Anthropogenic Sediment Pollution in West Maui, Hawai'i

NASA Astrophysics Data System (ADS)

Cerovski-Darriau, C.; Stock, J. D.; Winans, W. R.

2016-12-01

Episodic storm runoff in West Maui (Hawai'i) brings plumes of terrestrially-sourced fine sediment to the nearshore ocean environment, degrading coral reef ecosystems. The sediment pollution sources were largely unknown, though suspected to be due to modern human disturbance of the landscape, and initially assumed to be from visibly obvious exposed soil on agricultural fields and unimproved roads. To determine the sediment sources and estimate a sediment budget for the West Maui watersheds, we mapped the geomorphic processes in the field and from DEMs and orthoimagery, monitored erosion rates in the field, and modeled the sediment flux using the mapped processes and corresponding rates. We found the primary source of fine sands, silts and clays to be previously unidentified fill terraces along the stream bed. These terraces, formed during legacy agricultural activity, are the banks along 40-70% of the streams where the channels intersect human-modified landscapes. Monitoring over the last year shows that a few storms erode the fill terraces 10-20 mm annually, contributing up to 100s of tonnes of sediment per catchment. Compared to the average long-term, geologic erosion rate of 0.03 mm/yr, these fill terraces alone increase the suspended sediment flux to the coral reefs by 50-90%. Stakeholders can use our resulting geomorphic process map and sediment budget to inform the location and type of mitigation effort needed to limit terrestrial sediment pollution. We compare our mapping, monitoring, and modeling (M3) approach to NOAA's OpenNSPECT model. OpenNSPECT uses empirical hydrologic and soil erosion models paired with land cover data to compare the spatially distributed sediment yield from different land-use scenarios. We determine the relative effectiveness of calculating a baseline watershed sediment yield from each approach, and the utility of calibrating OpenNSEPCT with M3 results to better forecast future sediment yields from land-use or climate change scenarios.

Spatial and temporal variation of heavy metal risk and source in sediments of Dongting Lake wetland, mid-south China.

PubMed

Liang, Jie; Liu, Jiayu; Yuan, Xingzhong; Zeng, Guangming; Lai, Xu; Li, Xiaodong; Wu, Haipeng; Yuan, Yujie; Li, Fei

2015-01-01

Surface sediments of Dongting Lake wetland were collected from ten sites to investigate variation trend, risk and sources of heavy metal distribution in dry seasons of 2011∼2013. The three-year mean concentrations (mg/kg) of Cr, Cu, Pb, Cd, Hg and As were 91.33, 36.27, 54.82, 4.39, 0.19 and 25.67, respectively, which were all higher than the corresponding background values. Sediment quality guidelines (SQGs) and Geo-accumulation index (Igeo) were used for the assessment of pollution level of heavy metals. The pollution risk of Cd, Hg and As were great and that of Cr needed urgent attention because of its obvious increase. Pollution load index (PLI) and geographic information system (GIS) methods were conducted to assess spatial and temporal variation of heavy metal contamination. Results confirmed an increased contamination contribution inflow from Xiang River. Multivariate statistical analyses were applied to identify contribution sources of heavy metal, which showed anthropogenic origin mainly from mining, smelting, chemical industry and agricultural activity.

Sediment source fingerprinting to quantify fine sediment sources in forested catchments, Chile.

NASA Astrophysics Data System (ADS)

Schuller, P.; Walling, D. E.; Iroume, A.; Castillo, A.; Quilodran, C.

2012-04-01

A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrasting mean annual rainfall: Nacimiento (1,200 mm year-1) and Los Ulmos (2,500 mm year-1). Sediment source fingerprinting techniques are being used to document the primary fine sediment sources. In each catchment, three potential sediment sources were defined: clearcut slopes (Z1), forest roads (Z2) and the stream channel (Z3). In each catchment, multiple representative composite samples of the different potential source materials were collected before harvest operations from the upper 1 cm layer in Z1, Z2, and from the channel bank and bed for Z3. A time-integrating trap sampler installed in the discharge monitoring station constructed at the outlet of each catchment has been used to collect samples of the suspended sediment and these have been supplemented by sediment collected from the weir pools. Total suspended sediment load is been quantified in the monitoring stations using discharge records and integrated water sampling. Caesium-137 (137Cs), excess lead-210 (210Pbex) and other sediment properties are being used as fingerprints. After air-drying, oven-drying at 40°C and disaggregation, both the source material samples and the sediment samples collected in the discharge monitoring stations were sieved through a 63-μm sieve and the <63-μm fractions were used for subsequent analyses. For radionuclide assay, the samples were sealed in Petri dishes and after 4 weeks the mass activity density (activity concentration) of 137Cs and 210Pbex was determined by gamma analysis, using an ORTEC extended range Ge detector of 53% relative efficiency. The 137Cs and 210Pbex activity and organic carbon (Corg) concentration associated with potential source materials and the target sediment show that the two radionuclides used in combination with the Corg property provide effective source fingerprints. Additional work using a mixing model taking account of particle size effects is required to establish the relative contributions of the three sources to the fine sediment loads of the study catchments. This research is supported by the Chilean Government through FONDECYT Project 1090574 and by the IAEA through CRP D1.20.11 (Contract CHI-15531 and Technical Contract 15478) and the RLA 05/051 Project.

Impacts of transportation infrastructure on storm water and surfaces waters in Chittenden County, Vermont, USA.

DOT National Transportation Integrated Search

2014-06-01

Transportation infrastructure is a major source of stormwater runoff that can alter hydrology and : contribute significant loading of nutrients, sediment, and other pollutants to surface waters. These : increased loads can contribute to impairment of...

Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

PubMed Central

Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

2016-01-01

Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively. PMID:26947748

Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

NASA Astrophysics Data System (ADS)

Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

2014-05-01

Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (<10 km long), while sub-soils account for 90 to 100% of sediment entering and being transported in the remaining ~50 km of the system. This shift in dominant sediment source material coincided with a large increase in channel cross sectional area (~20 to >200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all areas apart from the upper catchment. The enlargement and entrenchment of the channel downstream has also resulted in lateral disconnection between the channel and floodplain. In this case, a rapid reduction in radionuclide concentrations downstream does coincide with hydrogeomorphic changes, supporting their use for studying short-term sediment dynamics. These findings highlight the importance of understanding hydrogeomorphic processes and connectivity when interpreting sediment source and tracer data.

Long-term assessment of runoff and sediment transport from grass and agroforestry buffers in corn/soybean watersheds using APEX

USDA-ARS?s Scientific Manuscript database

Existence of a claypan layer in soils at depths ranging from 4 to 37 cm restricts water movement and has contributed significantly to high rates of runoff, sediment transport, and other non-point source loadings from croplands in watersheds. The deposition of these pollutants in rivers, streams and...

Lead contamination and source in Shanghai in the past century using dated sediment cores from urban park lakes.

PubMed

Li, H B; Yu, S; Li, G L; Deng, H

2012-08-01

Lead contamination becomes of importance to urban resident health worldwide, especially for child health and growth. Undisturbed lake sediment cores are increasingly employed as a useful tool to backdate environmental contamination history. Five intact sediment cores collected from lakes in five urban parks were dated using (210)Pb and analyzed for total Pb content and isotope ratio to reconstruct the Pb contamination history over the last century in Shanghai, China. Total Pb content in the sediment cores increased by about 2- to 3-fold since 1900s. The profile of Pb flux in each sediment core revealed a remarkable increase of Pb contamination in Shanghai over the past century, especially in the latest three decades when China was experiencing a rapid economic and industrial development. Significant correlations were found between Pb fluxes in sediment cores and Pb emission from coal combustion in Shanghai. Coal combustion emission dominated anthropogenic Pb sources during the past century contributing from 52% to 69% of total Pb in cores, estimated by a three-end member model of Pb isotope ratios. Leaded gasoline emission generally contributed <30% of total Pb, which was banned by 1997 in the Shanghai region. Our results implicate that coal combustion-based energy consumption should be replaced, or at least partially replaced, to reduce health risks of Pb contamination in Shanghai. Copyright © 2012 Elsevier Ltd. All rights reserved.

Potential bioavailability assessment, source apportionment and ecological risk of heavy metals in the sediment of Brisbane River estuary, Australia.

PubMed

Duodu, Godfred Odame; Goonetilleke, Ashantha; Ayoko, Godwin A

2017-04-15

A weak acid extraction was used to mobilize the loosely bound metals in estuary sediment samples. More than 30% of Ag, As, Ca, Cd, Co, Cu, Hg, Mn Ni, Pb and Zn were leached from the sediment showing that these metals are significantly present in the bioavailable form. PCA/APCS identified three sources of the metals, namely: lithogenic accounting for 72%, shipping related contributing 15% and traffic related representing 13% of the total load. Application of pollution index (PI) and modified pollution index (MPI) revealed that the sediment range from unpolluted to heavily polluted while ecological risk index (RI) classifies the sediment as posing low ecological risk modified ecological risk index (MRI) suggests considerable to very high ecological risk. To provide holistic insights into the ecological risks posed by metals, enrichment factor, MPI and MRI are recommended for the assessment of sediment in complex environments such as estuaries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gross Nitrogen Mineralization in Surface Sediments of the Yangtze Estuary

PubMed Central

Liu, Min; Li, Xiaofei; Yin, Guoyu; Zheng, Yanling; Deng, Fengyu

2016-01-01

Nitrogen mineralization is a key biogeochemical process transforming organic nitrogen to inorganic nitrogen in estuarine and coastal sediments. Although sedimentary nitrogen mineralization is an important internal driver for aquatic eutrophication, few studies have investigated sedimentary nitrogen mineralization in these environments. Sediment-slurry incubation experiments combined with 15N isotope dilution technique were conducted to quantify the potential rates of nitrogen mineralization in surface sediments of the Yangtze Estuary. The gross nitrogen mineralization (GNM) rates ranged from 0.02 to 5.13 mg N kg-1 d-1 in surface sediments of the study area. The GNM rates were generally higher in summer than in winter, and the relative high rates were detected mainly at sites near the north branch and frontal edge of this estuary. The spatial and temporal distributions of GNM rates were observed to depend largely on temperature, salinity, sedimentary organic carbon and nitrogen contents, and extracellular enzyme (urease and L-glutaminase) activities. The total mineralized nitrogen in the sediments of the Yangtze Estuary was estimated to be about 6.17 × 105 t N yr-1, and approximately 37% of it was retained in the estuary. Assuming the retained mineralized nitrogen is totally released from the sediments into the water column, which contributed 12–15% of total dissolved inorganic nitrogen (DIN) sources in this study area. This result indicated that the mineralization process is a significant internal nitrogen source for the overlying water of the Yangtze Estuary, and thus may contribute to the estuarine and coastal eutrophication. PMID:26991904

Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011–2015)

PubMed Central

Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Wakiyama, Yoshifumi; Jaegler, Hugo; Lefèvre, Irène

2016-01-01

Fallout from the Fukushima Dai-ichi nuclear power plant accident resulted in a 3000-km2 radioactive contamination plume. Here, we model the progressive dilution of the radiocesium contamination in 327 sediment samples from two neighboring catchments with different timing of soil decontamination. Overall, we demonstrate that there has been a ~90% decrease of the contribution of upstream contaminated soils to sediment transiting the coastal plains between 2012 (median – M – contribution of 73%, mean absolute deviation – MAD – of 27%) and 2015 (M 9%, MAD 6%). The occurrence of typhoons and the progress of decontamination in different tributaries of the Niida River resulted in temporary increases in local contamination. However, the much lower contribution of upstream contaminated soils to coastal plain sediment in November 2015 demonstrates that the source of the easily erodible, contaminated material has potentially been removed by decontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean. PMID:27694832

A mass balance mercury budget for a mine-dominated lake: Clear Lake, California

USGS Publications Warehouse

Suchanek, T.H.; Cooke, J.; Keller, K.; Jorgensen, S.; Richerson, P.J.; Eagles-Smith, Collin A.; Harner, E.J.; Adam, D.P.

2009-01-01

The Sulphur Bank Mercury Mine (SBMM), active intermittently from 1873–1957 and now a USEPA Superfund site, was previously estimated to have contributed at least 100 metric tons (105 kg) of mercury (Hg) into the Clear Lake aquatic ecosystem. We have confirmed this minimum estimate. To better quantify the contribution of the mine in relation to other sources of Hg loading into Clear Lake and provide data that might help reduce that loading, we analyzed Inputs and Outputs of Hg to Clear Lake and Storage of Hg in lakebed sediments using a mass balance approach. We evaluated Inputs from (1) wet and dry atmospheric deposition from both global/regional and local sources, (2) watershed tributaries, (3) groundwater inflows, (4) lakebed springs and (5) the mine. Outputs were quantified from (1) efflux (volatilization) of Hg from the lake surface to the atmosphere, (2) municipal and agricultural water diversions, (3) losses from out-flowing drainage of Cache Creek that feeds into the California Central Valley and (4) biotic Hg removal by humans and wildlife. Storage estimates include (1) sediment burial from historic and prehistoric periods (over the past 150–3,000 years) from sediment cores to ca. 2.5m depth dated using dichloro diphenyl dichloroethane (DDD), 210Pb and 14C and (2) recent Hg deposition in surficial sediments. Surficial sediments collected in October 2003 (11 years after mine site remediation) indicate no reduction (but a possible increase) in sediment Hg concentrations over that time and suggest that remediation has not significantly reduced overall Hg loading to the lake. Currently, the mine is believed to contribute ca. 322–331 kg of Hg annually to Clear Lake, which represents ca. 86–99% of the total Hg loading to the lake. We estimate that natural sedimentation would cover the existing contaminated sediments within ca. 150–300 years.

Identification of multiple mercury sources to stream sediments near Oak Ridge, TN, USA

DOE PAGES

Donovan, Patrick M.; Blum, Joel D.; Demers, Jason D.; ...

2014-03-03

In this paper, sediments were analyzed for total Hg concentration (THg) and isotopic composition from streams and rivers in the vicinity of the Y-12 National Security Complex (Y12) in Oak Ridge, TN (USA). In the stream directly draining Y12, where industrial releases of mercury (Hg) have been documented, high THg (3.26 to 60.1 μg/g) sediments had a distinct Hg isotopic composition (δ 202Hg of 0.02 ± 0.15‰ and Δ 199Hg of -0.07 ± 0.03‰; mean ± 1SD, n=12) compared to sediments from relatively uncontaminated streams in the region (δ 202Hg = -1.40 ± 0.06‰ and Δ 199Hg of –0.26 ±more » 0.03‰; mean ± 1SD, n=6). Additionally, several streams that are nearby but do not drain Y12 had sediments with intermediate THg (0.06 to 0.21 μg/g) and anomalous δ 202Hg (as low as -5.07‰). We suggest that the low δ 202Hg values in these sediments provide evidence for the contribution of an additional Hg source to sediments, possibly derived from atmospheric deposition. In sediments directly downstream of Y12 this third Hg source is not discernible and the Hg isotopic composition can be largely explained by the mixing of low THg sediments with high THg sediments contaminated by Y12 discharges.« less

The rare earth element compositions of the Changjiang (Yangtze) and Huanghe (Yellow) river sediments

NASA Astrophysics Data System (ADS)

Yang, Shou Ye; Jung, Hoi Soo; Choi, Man Sik; Li, Cong Xian

2002-07-01

Thirty-four samples from the Changjiang and Huanghe were analyzed to characterize their rare earth element (REE) compositions. Although REE concentrations in the Changjiang sediments are higher than those of the Huanghe sediments, the former are less variable. Bulk samples and acid-leachable fractions have convex REE patterns and middle REE enrichments relative to upper continental crust, whereas flat patterns are present in the residual fractions. Source rock composition is the primary control on REE composition, and weathering processes play a minor role. Grain size exerts some influence on REE composition, as demonstrated by the higher REE contents of clay minerals in sediments from both rivers. Heavy minerals contribute about 10-20% of the total REE in the sediments. Apatite is rare in the river sediments, and contributes less than 2% of the REE content, but other heavy minerals such as sphene, allanite and zircon are important reservoirs of residual REE fractions. The Fe-Mn oxides phase accounts for about 14% of bulk REE content in the Changjiang sediments, which could be one of the more important factors controlling REE fractionation in the leachable fraction.

A method for separation of heavy metal sources in urban groundwater using multiple lines of evidence.

PubMed

Hepburn, Emily; Northway, Anne; Bekele, Dawit; Liu, Gang-Jun; Currell, Matthew

2018-06-11

Determining sources of heavy metals in soils, sediments and groundwater is important for understanding their fate and transport and mitigating human and environmental exposures. Artificially imported fill, natural sediments and groundwater from 240 ha of reclaimed land at Fishermans Bend in Australia, were analysed for heavy metals and other parameters to determine the relative contributions from different possible sources. Fishermans Bend is Australia's largest urban re-development project, however, complicated land-use history, geology, and multiple contamination sources pose challenges to successful re-development. We developed a method for heavy metal source separation in groundwater using statistical categorisation of the data, analysis of soil leaching values and fill/sediment XRF profiling. The method identified two major sources of heavy metals in groundwater: 1. Point sources from local or up-gradient groundwater contaminated by industrial activities and/or legacy landfills; and 2. contaminated fill, where leaching of Cu, Mn, Pb and Zn was observed. Across the precinct, metals were most commonly sourced from a combination of these sources; however, eight locations indicated at least one metal sourced solely from fill leaching, and 23 locations indicated at least one metal sourced solely from impacted groundwater. Concentrations of heavy metals in groundwater ranged from 0.0001 to 0.003 mg/L (Cd), 0.001-0.1 mg/L (Cr), 0.001-0.2 mg/L (Cu), 0.001-0.5 mg/L (Ni), 0.001-0.01 mg/L (Pb), and 0.005-1.2 mg/L (Zn). Our method can determine the likely contribution of different metal sources to groundwater, helping inform more detailed contamination assessments and precinct-wide management and remediation strategies. Copyright © 2018 Elsevier Ltd. All rights reserved.

A combined experimental-modelling method for the detection and analysis of pollution in coastal zones

NASA Astrophysics Data System (ADS)

Limić, Nedzad; Valković, Vladivoj

1996-04-01

Pollution of coastal seas with toxic substances can be efficiently detected by examining toxic materials in sediment samples. These samples contain information on the overall pollution from surrounding sources such as yacht anchorages, nearby industries, sewage systems, etc. In an efficient analysis of pollution one must determine the contribution from each individual source. In this work it is demonstrated that a modelling method can be utilized for solving this latter problem. The modelling method is based on a unique interpretation of concentrations in sediments from all sampling stations. The proposed method is a synthesis consisting of the utilization of PIXE as an efficient method of pollution concentration determination and the code ANCOPOL (N. Limic and R. Benis, The computer code ANCOPOL, SimTel/msdos/geology, 1994 [1]) for the calculation of contributions from the main polluters. The efficiency and limits of the proposed method are demonstrated by discussing trace element concentrations in sediments of Punat Bay on the island of Krk in Croatia.

Assessing the potential of amino acid 13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

NASA Astrophysics Data System (ADS)

Larsen, T.; Bach, L. T.; Salvatteci, R.; Wang, Y. V.; Andersen, N.; Ventura, M.; McCarthy, M. D.

2015-08-01

Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. It is uncertain whether archaea may have contributed to sedimentary δ13CAA patterns we observe, and controlled culturing studies will be needed to investigate whether δ13CAA patterns can differentiate bacterial from archeal sources. Further research efforts are also needed to understand how closely δ13CAA patterns derived from hydrolyzable amino acids represent total sedimentary proteineincous material, and more broadly sedimentary organic nitrogen. Overall, however, both our culturing and sediment studies suggest that δ13CAA patterns in sediments will represent a novel proxy for understanding both primary production sources, and the direct bacterial role in the ultimate preservation of sedimentary organic matter.

Clay-mineral suites, sources, and inferred dispersal routes: Southern California continental shelf

USGS Publications Warehouse

Hein, J.R.; Dowling, J.S.; Schuetze, A.; Lee, H.J.

2003-01-01

Clay mineralogy is useful in determining the distribution, sources, and dispersal routes of fine-grained sediments. In addition, clay minerals, especially smectite, may control the degree to which contaminants are adsorbed by the sediment. We analyzed 250 shelf sediment samples, 24 river-suspended-sediment samples, and 12 river-bed samples for clay-mineral contents in the Southern California Borderland from Point Conception to the Mexico border. In addition, six samples were analyzed from the Palos Verdes Headland in order to characterize the clay minerals contributed to the offshore from that point source. The <2 ??m-size fraction was isolated, Mg-saturated, and glycolated before analysis by X-ray diffraction. Semi-quantitative percentages of smectite, illite, and kaolinite plus chlorite were calculated using peak areas and standard weighting factors. Most fine-grained sediment is supplied to the shelf by rivers during major winter storms, especially during El Nin??o years. The largest sediment fluxes to the region are from the Santa Ynez and Santa Clara Rivers, which drain the Transverse Ranges. The mean clay-mineral suite for the entire shelf sediment data set (26% smectite, 50% illite, 24% kaolinite+chlorite) is closely comparable to that for the mean of all the rivers (31% smectite, 49% illite, 20% kaolinite+chlorite), indicating that the main source of shelf fine-grained sediments is the adjacent rivers. However, regional variations do exist and the shelf is divided into four provinces with characteristic clay-mineral suites. The means of the clay-mineral suites of the two southernmost provinces are within analytical error of the mineral suites of adjacent rivers. The next province to the north includes Santa Monica Bay and has a suite of clay minerals derived from mixing of fine-grained sediments from several sources, both from the north and south. The northernmost province clay-mineral suite matches moderately well that of the adjacent rivers, but does indicate some mixing from sources in adjacent provinces.

Using rare earth elements to trace wind-driven dispersion of sediments from a point source

NASA Astrophysics Data System (ADS)

Van Pelt, R. Scott; Barnes, Melanie C. W.; Strack, John E.

2018-06-01

The entrainment and movement of aeolian sediments is determined by the direction and intensity of erosive winds. Although erosive winds may blow from all directions, in most regions there is a predominant direction. Dust emission causes the removal preferentially of soil nutrients and contaminants which may be transported tens to even thousands of kilometers from the source and deposited into other ecosystems. It would be beneficial to understand spatially and temporally how the soil source may be degraded and depositional zones enriched. A stable chemical tracer not found in the soil but applied to the surface of all particles in the surface soil would facilitate this endeavor. This study examined whether solution-applied rare earth elements (REEs) could be used to trace aeolian sediment movement from a point source through space and time at the field scale. We applied erbium nitrate solution to a 5 m2 area in the center of a 100 m diameter field 7854 m2 on the Southern High Plains of Texas. The solution application resulted in a soil-borne concentration three orders of magnitude greater than natively found in the field soil. We installed BSNE sampler masts in circular configurations and collected the trapped sediment weekly. We found that REE-tagged sediment was blown into every sampler mast during the course of the study but that there was a predominant direction of transport during the spring. This preliminary investigation suggests that the REEs provide a viable and incisive technique to study spatial and temporal variation of aeolian sediment movement from specific sources to identifiable locations of deposition or locations through which the sediments were transported as horizontal mass flux and the relative contribution of the specific source to the total mass flux.

Mechanisms of Sediment Transport to an Abandoned Distributary Channel on the Huanghe (Yellow River) Delta, China

NASA Astrophysics Data System (ADS)

Kumpf, L. L.; Kineke, G. C.; Carlson, B.; Mullane, M.

2017-12-01

Avulsions on the fine-grained Huanghe delta have left it scarred with traces of abandoned distributary channels that become intertidal systems, open to water and sediment exchange with the sea. In 1996, an engineered avulsion of the Huanghe left a 30 km long abandoned channel to the south of the modern active river channel. Though all fluvial input was cut off, present-day sedimentation on the new tidal flats has been observed at rates around 2 cm/yr. The source must be suspended-sediment from the Bohai Sea conveyed by the tidal channel network, but the mechanisms promoting sediment import are unknown. Possible mechanisms include (A) import sourced from the sediment-rich buoyant coastal plume, (B) wave resuspension on the shallow shelf, (C) reverse-estuarine residual circulation in the tidal channel, and (D) tidal asymmetry in the channel. Over three summers, in situ measurements of current velocity, suspended-sediment concentration (SSC), and wave climate were made on the delta front, and measurements of velocity, SSC, and salinity were made within the tidal channel. Results suggest that the buoyant plume from the active Huanghe channel can transport sediment south toward the tidal channel mouth (A). Additionally, wave resuspension (B) takes place on the subaqueous topset beds when the significant wave height exceeds 1 m, providing potential sources of suspended-sediment to the tidal channel. Within the abandoned channel, the tidal channel can become hypersaline and exhibit reverse-estuarine circulation (C), which would promote import of turbid coastal water near the surface. Time-series of velocity in the tidal channel indicate that ebb currents are consistently higher than flood currents through the spring-neap cycle (D), with maximum velocities exceeding 1 m/s and corresponding maximum SSC reaching 2 g/L during spring tide. While ebb dominance would typically tend to flush the system of its sediment over time, sediment supplied to the tidal flats may not be removed during the ebb, leading to net accumulation. Flocculation may also enhance settling over the inundated mudflats, contributing to the observed sedimentation. If import and sedimentation proceed at current rates, this abandoned channel may eventually anneal, contributing to the stability of the Huanghe delta.

An evaluation of petrogenic hydrocarbons in northern Gulf of Alaska continental shelf sediments - The role of coastal oil seep inputs

USGS Publications Warehouse

Short, J.W.; Kolak, J.J.; Payne, J.R.; Van Kooten, G. K.

2007-01-01

We compared hydrocarbons in water, suspended particulate matter (SPM), and riparian sediment collected from coastal watersheds along the Yakataga foreland with corresponding hydrocarbons in Gulf of Alaska benthic sediments. This comparison allows an evaluation of hydrocarbon contributions to marine sediments from natural oil seeps, coal and organic matter (e.g., kerogen) associated with eroding siliciclastic rocks. The samples from oil seeps show extensive loss of low-molecular weight n-alkanes (

Influence of Wetland and Channel Sediments on Strontium-90 Transport in the Borschi Stream, near Chernobyl

NASA Astrophysics Data System (ADS)

Freed, R.; Smith, L.; Bugai, D.

2001-12-01

In the Borschi watershed, 3 km south of the Chernobyl nuclear power plant, we have found the transfer of 90Sr in wetlands pore waters to surface waters and the subsequent flow of wetland surface waters to the stream, largely effect the concentration of 90Sr in the Borschi channel. In Borschi, we have observed that during most of the year, wetlands are the main source of 90Sr contributing to the Borschi stream and channel bottom sediments are a secondary source. Wetland pore waters have at least an order of magnitude higher concentration of 90Sr than all other surface and subsurface waters. Pore water data obtained using peepers shows the 90Sr diffusion gradient is high in near-surface wetland sediments while the 90Sr diffusion gradient is moderate to insignificant in near-surface channel sediments. Channel and wetland sediments are highly depleted in 90Sr compared with immobile nuclear fission products such as europium-154 and can account for all of the 90Sr removed by the stream since the accident. While channel sediments are largely depleted in exchangeable 90Sr, wetland sediments represent a large source of exchangeable 90Sr. Removal of 90Sr by the stream from the wetland and channel sediments is on the same order as mass loss by decay.

The Influence of Erosional Hotspots on Watershed-scale Phosphorus Dynamics in Intensively Managed Agricultural Landscapes

NASA Astrophysics Data System (ADS)

Baker, A.; Finlay, J. C.; Gran, K. B.; Karwan, D. L.; Engstrom, D. R.; Atkins, W.; Muramoto-Mathieu, M.

2017-12-01

The Minnesota River Basin is an intensively-managed agricultural watershed which contributes disproportionately to downstream sediment and nutrient loading. The Le Sueur River, an actively eroding tributary to the Minnesota River, has been identified as a disproportionate contributor of sediment and nutrients to this system. In an effort to identify best practices for reduction of phosphorus (P) in the context of intensifying agriculture and climate change pressure, we coupled investigation of source sediment P chemistry with an existing fine sediment budget to create a watershed mass balance for sediment-associated P. Sediments collected from primary source areas including agricultural fields, glacial till bluffs, alluvial streambanks, ravines, and agricultural ditches were analyzed for total- and extractable-P, and sorptive properties. Preliminary integration of these data into a mass-balance suggests that less than a quarter of the total-P exported from this watershed can be attributed directly to sediment inputs, likely due to the low P concentration of most sediment sources. While sediment may supply less than 25% of the total-P exiting the Le Sueur, a high proportion of total-P load ( 66% on average) is in particulate form. This finding indicates that sorption of dissolved-P from upstream sources onto fine sediment plays a major role in determining the form and reactivity of P in the watershed. Sorption processes convert dissolved-P into particulate-P, and may substantially alter the fate and reactivity of P in downstream channels and lakes. In highly erosive rivers, as the Le Sueur, where inputs of sediment from deep soil horizons are dominant, the dynamic relationship between sediment and dissolved-P must be evaluated and incorporated into models to forecast potential for P retention and export from the landscape. By incorporating results of this mass balance and analysis of sediment sorptive properties into existing models, we can develop strategies that most effectively address both of these interwoven pollutants to aquatic ecosystems.

The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in South Africa

NASA Astrophysics Data System (ADS)

Foster, Ian D. L.; Boardman, John; Collins, Adrian L.; Copeland-Phillips, Ruth; Kuhn, Nikolaus J.; Mighall, Tim M.; Pulley, Simon; Rowntree, Kate M.

2017-03-01

Several research projects undertaken by the authors and others over the last 14 years have used fallout and geogenic radionuclides for understanding erosion processes and sediment yield dynamics in South Africa over the last 100-200 years as European settlers colonised the interior plains and plateaux of the country and imported new livestock and farming techniques to the region. These projects have used two fallout radionuclides (210Pb and 137Cs) to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans and floodouts and have used other fallout nuclides (7Be) and long-lived geogenic radionuclides (e.g. 40K, 235U) as part of a composite fingerprint exploring contemporary sediment sources and changes to sources through time. While successful in many parts of the world, applying these techniques in Southern Africa has posed a number of challenges often not encountered elsewhere. Here we explore some of the benefits and challenges in using gamma-emitting radionuclides, especially 137Cs, in these landscapes. Benefits include the potential for discriminating gully sidewall from topsoil sources, which has helped to identify contemporary gully systems as sediment conduits, rather than sources, and for providing a time-synchronous marker horizon in a range of sedimentary environments that has helped to develop robust chronologies. Challenges include the spatial variability in soil cover on steep rocky hillslopes, which is likely to challenge assumptions about the uniformity of initial fallout nuclide distribution, the paucity of stable (non-eroding) sites in order to estimate atmospheric fallout inventories, and the limited success of 210Pb dating in some rapidly accumulating high altitude catchments where sediments often comprise significant amounts of sand and gravel. Despite these challenges we present evidence suggesting that the use of gamma-emitting radionuclides can make a significant contribution to our understanding of erosion processes and sediment yield dynamics. Future research highlighted in the conclusion will try to address current challenges and outline new projects established to address them more fully.

ArcAPEX modeling of optimum widths and placement of grass and agroforestry buffers to reduce runoff and sediment transport in claypan watersheds

USDA-ARS?s Scientific Manuscript database

Existence of a claypan layer in soils at depths ranging from 4 to 37 cm restricts vertical water movement and has contributed significantly to high rates of runoff, sediment transport, and other non-point source loadings from croplands in watersheds. The deposition of these pollutants in rivers, st...

Multivariate Statistical Approach Applied to Sediment Source Tracking Through Quantification and Mineral Identification, Cheyenne River, South Dakota

NASA Astrophysics Data System (ADS)

Valder, J.; Kenner, S.; Long, A.

2008-12-01

Portions of the Cheyenne River are characterized as impaired by the U.S. Environmental Protection Agency because of water-quality exceedences. The Cheyenne River watershed includes the Black Hills National Forest and part of the Badlands National Park. Preliminary analysis indicates that the Badlands National Park is a major contributor to the exceedances of the water-quality constituents for total dissolved solids and total suspended solids. Water-quality data have been collected continuously since 2007, and in the second year of collection (2008), monthly grab and passive sediment samplers are being used to collect total suspended sediment and total dissolved solids in both base-flow and runoff-event conditions. In addition, sediment samples from the river channel, including bed, bank, and floodplain, have been collected. These samples are being analyzed at the South Dakota School of Mines and Technology's X-Ray Diffraction Lab to quantify the mineralogy of the sediments. A multivariate statistical approach (including principal components, least squares, and maximum likelihood techniques) is applied to the mineral percentages that were characterized for each site to identify the contributing source areas that are causing exceedances of sediment transport in the Cheyenne River watershed. Results of the multivariate analysis demonstrate the likely sources of solids found in the Cheyenne River samples. A further refinement of the methods is in progress that utilizes a conceptual model which, when applied with the multivariate statistical approach, provides a better estimate for sediment sources.

Sediment processes modelling below hydraulic mining: towards environmental impact mitigation

NASA Astrophysics Data System (ADS)

Chalov, Sergey R.

2010-05-01

Placer mining sites are located in the river valleys so the rivers are influenced by mining operations. Frequently the existing mining sites are characterized by low contribution to the environmental technologies. Therefore hydraulic mining alters stream hydrology and sediment processes and increases water turbidity. The most serious environmental sequences of the sediment yield increase occur in the rivers populated by salmon fish community because salmon species prefer clean water with low turbidity. For instance, the placer mining in Kamchatka peninsula (Far East of Russia) which is regarded to be the last global gene pool of wild salmon Oncorhynchus threatens the rivers ecosystems. System of man-made impact mitigation could be done through the exact recognition of the human role in hydrological processes and sediment transport especially. Sediment budget of rivers below mining sites is transformed according to the appearance of the man-made non-point and point sediment sources. Non-point source pollution occurs due to soil erosion on the exposed hillsides and erosion in the channel diversions. Slope wash on the hillsides is absent during summer days without rainfalls and is many times increased during rainfalls and snow melting. The nearness of the sources of material and the rivers leads to the small time of suspended load increase after rainfalls. The average time of material intake from exposed hillsides to the rivers is less than 1 hour. The main reason of the incision in the channel diversion is river-channel straightening. The increase of channel slopes and transport capacity leads to the intensive incision of flow. Point source pollution is performed by effluents both from mining site (mainly brief effluents) and from settling ponds (permanent effluents), groundwater seepage from tailing pits or from quarries. High rate of groundwater runoff is the main reason of the technological ponds overfilling. Intensive filtration from channel to ponds because of their nearness determines the water mass increase inside mining site. The predictive models were suggested to assess each of the mane-made processes contribution into the total sediment budget of the rivers below mining sites. The empirical data and theoretical and laboratory-derived correlations were used to obtain the predictive models for each processes of sediment supply. It was challenging to estimate specific erosion rate of washed exposed hillsides, channel incision, water supply conditions. Climatic and anthropogenic changes of water runoff also were simulated to decrease uncertainty of the proposed model. Application of the given approach to the hydraulic platinum-mining located in the Kamchatka peninsula (Koryak plateau, tributaries of the Vivenka River) gave the sediment budget of the placer-mined rivers and the total sediment yield supplied into the ocean from river basin. Polluted placer-mined rivers contribute about 30 % of the whole sediment yield of the Vivenka River. At the same time the catchment area of these rivers is less than 0,03 % from the whole Vivenka catchment area. Based on the sediment transport modeling the decision making system for controlling water pollution and stream community preservation was developed. Due to exposed hillside erosion prevention and settling pond system optimization the total decrease of sediment yield was up to 75 %.

The impact of a hydroelectric power plant on the sediment load in downstream water bodies, Svartisen, northern Norway.

PubMed

Bogen, J; Bønsnes, T E

2001-02-05

When the Svartisen hydroelectric power plant was put into operation, extensive sediment pollution was observed in the downstream fjord area. This paper discusses the impact of the power plant and the contribution from various sources of sediment. Computation of the sediment load was based on samples collected one to four times per day. Grain size distribution analyses of suspended sediments were carried out and used as input in a routing model to study the movement of sediments through the system. Suspended sediment delivered to the fjord before the power station was constructed was measured as 8360 metric tons as an annual mean for a 12-year period. During the years 1995-1996 when the power plant was operating, the total suspended load through the power station was measured as 32609 and 30254 metric tons, respectively. Grain size distribution analyses indicate a major change in the composition of the sediments from 9% clay before the power plant was operative to 50-60% clay afterwards. This change, together with the increase in sediment load, is believed to be one of the main causes of the drastic reduction in secchi depths in the fjord. The effect of the suspended sediment load on the fjord water turbidity was evaluated by co-plotting secchi depth and power station water discharge. Measurements during 1995 and 1996 showed that at the innermost of these locations the water failed to attain the minimum requirement of 2 m secchi depth. In later years secchi depths were above the specified level. In 1997 and 1998 the conditions improved. At the more distal locality, the conditions were acceptable with only a few exceptions. A routing model was applied to data acquired at a location 2 km from the power station in order to calculate the contributions from various sediment sources. This model indicated that the contribution from reservoir bed erosion dominated in 1994 but decreased significantly in 1995. Future operation of the power station will mostly take place with a high water level in the reservoir and is likely to result in acceptable water quality in the fjord. However, during periods of low drawdown, sediment pollution may again become a problem.

Source-to-Sink Methods by Hyperspectral Imaging: a Case Study of the Laminated Sediments of Lake Linné (Svalbard).

NASA Astrophysics Data System (ADS)

Van Exem, A.; Debret, M.; Copard, Y.; Verpoorter, C.; Sorrel, P.; de Wet, G.; Werner, A.; Roof, S.; Laignel, B.; Retelle, M.

2016-12-01

Laminated sediments contained valuable information recorded on a micrometric scale. Information about sediments flux and origins require high-resolution source tracking analysis. Quick and non-destructive, hyperspectral imaging provides contiguous reflectance datasets into 2 dimensions with a spatial resolution of 0.02 mm. Located on the west of the Spitzbergen, Lake Linné is the largest lake in the region. Erosion is mainly driven by glacier fluctuations and three different bedrocks are potential sediment sources. Organic matter (coal) is only found in some carboniferous rocks. Four cores recovered from different parts of the lake contain millimeter scale laminae. Two approaches were compared: (i) measurement of statistical correlations between the sediments and source samples, (ii) extraction of extreme spectral signatures from the VNIR hyperspectral images. Total Organic Carbon (TOC) values of all samples were also given by bulk geochemistry (RE6 ® pyrolyzer). Consequently, the measured similarity between the hyperspectral image and the field samples illustrates the sources contribution within the core. Three sample clusters and three equivalent spectral signatures were found. TOC values from the archive show good correlation (r=0.86, p<0.001, n=73) with the hyperspectral signature relative to TOC content. A least-squares regression (r²=0.74) was used to extrapolate TOC values in order to represent their distribution at 0.02 mm resolution. This is the first source-to-sink study based on imaging spectroscopy. Our results indicate that hyperspectral imagery is a useful tool to (i) identify sediment sources, (ii) perform continuous paleo-environmental reconstruction at high resolution, and (iii) can provide quantitative results (TOC values) validated by destructive analyses.

Minor soil erosion contribution to denudation in Central Nepal Himalaya.

NASA Astrophysics Data System (ADS)

Morin, Guillaume; France-Lanord, Christian; Gallo, Florian; Lupker, Maarten; Lavé, Jérôme; Gajurel, Ananta

2013-04-01

In order to decipher river sediments provenance in terms of erosion processes, we characterized geochemical compositions of hillslope material coming from soils, glaciers and landslide, and compared them to rivers sediments. We focused our study on two South flank Himalayan catchments: (1) Khudi khola, as an example of small High Himalayan catchment (150 km2), undergoing severe precipitation, and rapid erosion ≈ 3.5 mm/yr [A] and (2) the Narayani-Gandak Transhimalayan basin (52000 km2) that drains the whole central Nepal. To assess the question, systematic samplings were conducted on hillslope material from different erosion processes in the basins. River sediment include daily sampling during the 2010 monsoon at two stations, and banks samples in different parts of the basins. Source rocks, soil and landslide samples, are compared to river sediment mobile to immobile element ratios, completed by hydration degree H2O+ analysis[2]. Data show that soils are clearly depleted in mobile elements Na, K, Ca, and highly hydrated compared to source rocks and other erosion products. In the Khudi basin, the contrast between soil and river sediment signatures allow to estimate that soil erosion represents less than 5% of the total sediment exported by the river. Most of the river sediment therefore derives from landslides inputs and to a lesser extent by barren high elevation sub-basins. This is further consistent with direct observation that, during monsoon, significant tributaries of the Khudi river do not export sediments. Considering that active landslide zones represent less than 0.5% of the total watershed area, it implies that erosion distribution is highly heterogeneous. Landslide erosion rate could reach more than 50 cm/yr in the landslide area. Sediments of the Narayani river are not significantly different from those of the Khudi in spite of more diverse geomorphology and larger area of the basin. Only H2O+ and Total Organic Carbon concentrations normalised to Al/Si ratios show distinctly higher values. This suggests that contribution of soil erosion is higher than in the Khudi basin. Nevertheless, soil erosion remains a minor source of sediments implying that more physical processes such as landslide and glaciers dominate the erosional flux. In spite of high deforestation and agricultural land-use [B], soil erosion does not represent an important source of sediments in Nepal Himalaya. [A] Gabet et al. (2008) Earth and Planetary Science Letters 267, 482-494. [B] Gardner et al. (2003) Applied Geography 23, 23-45.

Reconnaissance sediment budget for selected watersheds of West Maui, Hawai‘i

USGS Publications Warehouse

Stock, Jonathan D.; Falinski, Kim A.; Callender, Tova

2016-01-12

Episodic runoff brings suspended sediment to the nearshore waters of West Maui, Hawaiʻi. Even small rainfalls create visible plumes over a few hours. We used mapping, field experiments, and analysis of recent (July 19–20, 2014) and historic rainfall to estimate sources of land-based pollution for two watersheds in West Maui: Honolua, and Honokōwai. Former agricultural fields and some unimproved roads are plausible sources for polluted runoff, but have saturated hydraulic conductivities greater than the 10–15 millimeters per hour (mm/hr) rainfalls of July 2014. These fields and roads showed minor evidence for storm runoff, and could not have contributed substantially to July 2014 plume generation. Since 1978, rain at intensities capable of causing runoff from former agricultural fields sustained for 1–2 hours is also rare; such intensities have 2–5 year recurrence rates in the north, and greater than 25 year recurrence rates to the south near Lahaina. Streambanks now eroding into historic terraces of sands, silts, and clays are a more plausible source. Although past large storms contributed to sediment loading, annual plume generation is now caused by smaller rainfalls eroding these near-stream legacy deposits. Treatments of former agricultural fields, roads, and reserve forests are consequently not likely to measurably affect sediment pollution from smaller, more frequent storms. Increased runoff from the development of West Maui has the potential to exacerbate sediment plumes from such storms unless there is an effective strategy to reduce bank erosion. Uncertainties in the extent and erosion rate of historic terraces, however, limit our ability to plan mitigation.

Sediment provenance in contractional orogens: The detrital zircon record from modern rivers in the Andean fold-thrust belt and foreland basin of western Argentina

NASA Astrophysics Data System (ADS)

Capaldi, Tomas N.; Horton, Brian K.; McKenzie, N. Ryan; Stockli, Daniel F.; Odlum, Margaret L.

2017-12-01

This study analyzes detrital zircon U-Pb age populations from Andean rivers to assess whether active synorogenic sedimentation accurately records proportional contributions from varied bedrock source units across different drainage areas. Samples of modern river sand were collected from west-central Argentina (28-33°S), where the Andes are characterized by active uplift and deposition in diverse contractional provinces, including (1) hinterland, (2) wedge-top, (3) proximal foreland, and (4) distal broken foreland basin settings. Potential controls on sediment provenance were evaluated by comparing river U-Pb age distributions with predicted age spectra generated by a sediment mixing model weighted by relative catchment exposure (outcrop) areas for different source units. Several statistical measures (similarity, likeness, and cross-correlation) are employed to compare how well the area-weighted model predicts modern river age populations. (1) Hinterland basin provenance is influenced by local relief generated along thrust-bounded ranges and high zircon fertility of exposed crystalline basement. (2) Wedge-top (piggyback) basin provenance is controlled by variable lithologic durability among thrust-belt bedrock sources and recycled basin sediments. (3) Proximal foreland (foredeep) basin provenance of rivers and fluvial megafans accurately reflect regional bedrock distributions, with limited effects of zircon fertility and lithologic durability in large (>20,000 km2) second-order drainage systems. (4) In distal broken segments of the foreland basin, regional provenance signatures from thrust-belt and hinterland areas are diluted by local contributions from foreland basement-cored uplifts.

The dominant erosion processes supplying fine sediment to three major rivers in tropical Australia, the Daly (NT), Mitchell (Qld) and Flinders (Qld) Rivers

NASA Astrophysics Data System (ADS)

Caitcheon, Gary G.; Olley, Jon M.; Pantus, Francis; Hancock, Gary; Leslie, Christopher

2012-05-01

The tropics of northern Australia have received relatively little attention with regard to the impact of soil erosion on the many large river systems that are an important part of Australia's water resource, especially given the high potential for erosion when long dry seasons are followed by intense wet season rain. Here we use 137Cs concentrations to determine the erosion processes supplying sediment to two major northern Australian Rivers; the Daly River (Northern Territory), and the Mitchell River (Queensland). We also present data from five sediment samples collected from a 100 km reach of the Cloncurry River, a major tributary of the Flinders River (Queensland). Concentrations of 137Cs in the surface soil and subsurface (channel banks and gully) samples were used to derive 'best fit' probability density functions describing their distributions. These modelled distributions are then used to estimate the relative contribution of these two components to the river sediments. Our results are consistent with channel and gully erosion being the dominant source of sediment, with more than 90% of sediment transported along the main stem of these rivers originating from subsoil. We summarize the findings of similar studies on tropical Australian rivers and conclude that the primary source of sediment delivered to these systems is gully and channel bank erosion. Previously, as a result of catchment scale modelling, sheet-wash and rill erosion was considered to be the major sediment source in these rivers. Identifying the relative importance of sediment sources, as shown in this paper, will provide valuable information for land management planning in the region. This study also reinforces the importance of testing model predictions before they are used to target investment in remedial action.

Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

USGS Publications Warehouse

Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

2015-01-01

Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

Distribution and sources of aliphatic hydrocarbons and fatty acids in surface sediments of a tropical estuary south west coast of India (Cochin estuary).

PubMed

Gireeshkumar, T R; Deepulal, P M; Chandramohanakumar, N

2015-03-01

Surface sediments samples from the Cochin estuary were measured for elemental, stable isotopic and molecular biomarkers (aliphatic hydrocarbons and fatty acids) to study the sources and distribution of sedimentary organic matter. Concentrations of total organic carbon (TOC), total nitrogen (TN) and stable isotopic ratios of carbon (δ(13)C) ranged from 0.62 to 2.74 %, 0.09 to 0.25 % and -27.5 to 21.7 ‰, respectively. Sedimentary n-alkanes ranged from 6.03 to 43.23 μg g(-1) with an average of 16.79 μg g(-1), while total fatty acids varied from 22.55 to 440.69 μg g(-1). The TOC/TN ratios and δ(13)C suggest a mixture of marine- and terrestrial-derived organic matter in the surface sediments with increasing contributions from marine-derived organic matter towards the seaward side. Long-chain n-alkanes derived from higher plants predominated the inner part of the estuary, while short-chain n-alkanes derived from planktonic sources predominated the bar mouth region. The even carbon preference of the C12-C22 n-alkanes may refer to the direct biogenic contribution from bacteria, fungi and yeast species and to the potential direct petroleum inputs. The presence of odd mid-chain n-alkanes in the sediments indicates the organic matter inputs from submerged and floating macrophytes (water hyacinth). Various molecular indices such as carbon preference index, terrestrial to aquatic ratio, average chain length and the ratios of mid-chain n-alkanes support the aforementioned inferences. The high contribution of odd and branched chain fatty acids along with very low contribution of polyunsaturated fatty acids, suggest the effective utilisation of algae-derived organic matter by bacteria and the effective recycling of labile organic matter in whole settling and deposition processes. The distributional variability of n-alkanes and fatty acids reveals the preferential utilisation of marine-derived organic matter and the selective preservation of terrestrial-derived organic matter in surface sediments of the Cochin estuary.

Evidence for only minor contributions from bacteria to sedimentary organic carbon

NASA Technical Reports Server (NTRS)

Hartgers, W. A.; Sinninghe Damste, J. S.; Requejo, A. G.; Allan, J.; Hayes, J. M.; de Leeuw, J. W.

1994-01-01

Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.

Deriving spatial and temporal patterns of coastal marsh aggradation from hurricane storm surge marker beds

NASA Astrophysics Data System (ADS)

Hodge, Joshua; Williams, Harry

2016-12-01

This study uses storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in marsh sedimentation on the McFaddin National Wildlife Refuge in Southeastern Texas. Fourteen sediment cores were collected along a transect extending 1230 m inland from the Gulf coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils and 137Cs dating. The hurricane-derived sediment beds facilitate assessment of changes in marsh sedimentation from nearshore to inland locations and over decadal to annual timescales. Spatial variation along the transect reflects varying contributions from three prevailing sediment sources: flooding, overwash and organic sedimentation from marsh plants. Over about the last decade, hurricane overwash has been the predominant sediment source for nearshore locations because of large sediment inputs from Hurricanes Rita and Ike. Farther inland, hurricane inputs diminish and sedimentation is dominated by deposition from flood waters and a larger organic component. Temporal variations in sedimentation reflect hurricane activity, changes in marsh surface elevation and degree of compaction of marsh sediments, which is time-dependent. There was little to no marsh sedimentation in the period 2008-2014, firstly because no hurricanes impacted the study area and secondly because overwash sedimentation prior to 2008 had increased nearshore marsh surface elevations by up to 0.68 m, reducing subsequent inputs from flooding. Marsh sedimentation rates were relatively high in the period 2005-2008, averaging 2.13 cm/year and possibly reflecting sediment contributions from Hurricanes Humberto and Gustav. However, these marsh sediments are highly organic and largely uncompacted. Older, deeper marsh deposits formed between 1961 and 2005 are less organic-rich, more compacted and have an average annual sedimentation rate of 0.38 cm/year, which is closely comparable to long-term sedimentation rates in similar marsh settings nearby. These results demonstrate the utility of using hurricane storm surge marker beds to investigate marsh sedimentation, provide insights into the sedimentary response of coastal marshes to hurricanes and provide useful guidance to public policy aimed at combating the effects of sea-level rise on coastal marshes along the northern Gulf of Mexico.

Remobilization Rates and Cumulative Contributions of Floodplains and Legacy Sediments from Piedmont Tributaries

NASA Astrophysics Data System (ADS)

Miller, A. J.; Donovan, M.; Baker, M. E.; Gellis, A.

2014-12-01

The disparity between watershed erosion rates and downstream sediment delivery has been an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a frequent focus. In the Piedmont province of the eastern US, post-settlement upland deforestation and agricultural land use led to accumulation of thick packages of overbank sediment ("legacy deposits") in valley bottoms. Previous authors have argued that legacy sediment is a potentially important source of sediment being remobilized by lateral migration of channels. We seek to address 1) How rapidly sediment is remobilized from floodplains by channel migration and bank erosion, 2) the proportion of streambank sediment derived from legacy sediment, and 3) the potential contributions of net stream bank erosion and legacy sediments to downstream sediment yields within the Piedmont of Baltimore County, Maryland. We measured gross erosion and deposition rates over 45 years within the fluvial corridor along 30 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Measured deposition within channel and point bars accounted for an average of 46% (28-75%) of gross erosion, with deposition increasingly important in larger drainages. Legacy sediments accounted for 6-90% of bank erosion at individual study segments, represented about 60% of bank height at most exposures, and accounted for 57% of the measured gross erosion. Extrapolating the results indicated that first- and second-order streams account for 62% of total stream bank erosion from northern Baltimore County. After accounting for estimated redeposition, extrapolated net stream bank sediment yields (72 Mg/km2/yr) are equivalent to 70% of average Piedmont watershed yield (104 Mg/km2/yr) cited in studies by previous authors. The results suggest stream bank sediments are a large source of sediment from Piedmont tributaries to the Chesapeake Bay. It is important to note that upland erosion rates have been reported with equivalent and greater magnitude for forested and cropland areas within the Maryland Piedmont (Gellis et al. 2009; Smith et al. 2011).

Citizen-volunteer and professional monitoring to identify fecal sources of contamination in southwestern Puerto Rico

EPA Science Inventory

High concentrations of nutrients, fecal microorganisms, and sediments in surface waters can be a public health threat and can impact fringing coral reefs in Guánica Bay in southwestern Puerto Rico. Yet, the main factors and sources contributing to water quality degradation...

Temperature signal in suspended sediment export from an Alpine catchment

NASA Astrophysics Data System (ADS)

Costa, Anna; Molnar, Peter; Stutenbecker, Laura; Bakker, Maarten; Silva, Tiago A.; Schlunegger, Fritz; Lane, Stuart N.; Loizeau, Jean-Luc; Girardclos, Stéphanie

2018-01-01

Suspended sediment export from large Alpine catchments ( > 1000 km2) over decadal timescales is sensitive to a number of factors, including long-term variations in climate, the activation-deactivation of different sediment sources (proglacial areas, hillslopes, etc.), transport through the fluvial system, and potential anthropogenic impacts on the sediment flux (e.g. through impoundments and flow regulation). Here, we report on a marked increase in suspended sediment concentrations observed near the outlet of the upper Rhône River Basin in the mid-1980s. This increase coincides with a statistically significant step-like increase in basin-wide mean air temperature. We explore the possible explanations of the suspended sediment rise in terms of changes in water discharge (transport capacity), and the activation of different potential sources of fine sediment (sediment supply) in the catchment by hydroclimatic forcing. Time series of precipitation and temperature-driven snowmelt, snow cover, and ice melt simulated with a spatially distributed degree-day model, together with erosive rainfall on snow-free surfaces, are tested to explore possible reasons for the rise in suspended sediment concentration. We show that the abrupt change in air temperature reduced snow cover and the contribution of snowmelt, and enhanced ice melt. The results of statistical tests show that the onset of increased ice melt was likely to play a dominant role in the suspended sediment concentration rise in the mid-1980s. Temperature-driven enhanced melting of glaciers, which cover about 10 % of the catchment surface, can increase suspended sediment yields through an increased contribution of sediment-rich glacial meltwater, increased sediment availability due to glacier recession, and increased runoff from sediment-rich proglacial areas. The reduced extent and duration of snow cover in the catchment are also potential contributors to the rise in suspended sediment concentration through hillslope erosion by rainfall on snow-free surfaces, and increased meltwater production on snow-free glacier surfaces. Despite the rise in air temperature, changes in mean discharge in the mid-1980s were not statistically significant, and their interpretation is complicated by hydropower reservoir management and the flushing operations at intakes. Overall, the results show that to explain changes in suspended sediment transport from large Alpine catchments it is necessary to include an understanding of the multitude of sediment sources involved together with the hydroclimatic conditioning of their activation (e.g. changes in precipitation, runoff, air temperature). In addition, this study points out that climate signals in suspended sediment dynamics may be visible even in highly regulated and human-impacted systems. This is particularly relevant for quantifying climate change and hydropower impacts on streamflow and sediment budgets in Alpine catchments.

Free, esterified and residual bound sterols in Black Sea Unit I sediments

NASA Astrophysics Data System (ADS)

de Leeuw, J. W.; Rijpstra, W. Irene C.; Schenck, P. A.; Volkman, J. K.

1983-03-01

Detailed compositional data for the sterols isolated from a surface, Unit I, sediment from the Black Sea are reported. A procedure based on digitonin precipitation has been used to separate the more abundant free sterols from those occurring in esterified forms. Saponification of the solvent extracted sediment residue liberated only a small quantity of residual bound sterols in contrast to studies of other sediments. 4-Methylsterols are much more abundant than 4-desmethylsterols in both the free and esterified sterol fractions which we attribute to a major dinoflagellate input, as in deeper Unit II sediment. The desmethylsterol fraction appears to derive from a variety of sources including dinoflagellates, coccolithophores, diatoms, terrigenous detritus and perhaps invertebrates. 5α(H)-Stanols are particularly abundant in the free sterol fraction. An analysis of the stanol/stenol ratios suggests that the 4-desmethyl-5α(H)-stanols are the result of specific microbial reductions of Δ 5-sterols and/or the reflection of a contribution of stanol containing source organisms.

Climate-driven shifts in sediment chemistry enhance methane production in northern lakes.

PubMed

Emilson, E J S; Carson, M A; Yakimovich, K M; Osterholz, H; Dittmar, T; Gunn, J M; Mykytczuk, N C S; Basiliko, N; Tanentzap, A J

2018-05-04

Freshwater ecosystems are a major source of methane (CH 4 ), contributing 0.65 Pg (in CO 2 equivalents) yr -1 towards global carbon emissions and offsetting ~25% of the terrestrial carbon sink. Most freshwater CH 4 emissions come from littoral sediments, where large quantities of plant material are decomposed. Climate change is predicted to shift plant community composition, and thus change the quality of inputs into detrital food webs, with the potential to affect CH 4 production. Here we find that variation in phenol availability from decomposing organic matter underlies large differences in CH 4 production in lake sediments. Production is at least 400-times higher from sediments composed of macrophyte litter compared to terrestrial sources because of inhibition of methanogenesis by phenol leachates. Our results now suggest that earth system models and carbon budgets should consider the effects of plant communities on sediment chemistry and ultimately CH 4 emissions at a global scale.

Distribution characteristics and sources of trace metals in sediment cores from a trans-boundary watercourse: An example from the Shima River, Pearl River Delta.

PubMed

Gao, Lei; Wang, Zhuowei; Shan, Jiju; Chen, Jianyao; Tang, Changyuan; Yi, Ming; Zhao, Xinfeng

2016-12-01

Metal pollution in sediments from the Shima River, a typical transboundary watercourse in the Pearl River Delta area, was investigated. Sediment cores were collected at eight sites from the upper to the lower reaches crossing Shenzhen, Dongguan and Huizhou cities. Sediment physicochemical properties and the total concentrations of trace metals (V, Cr, Co, Ni, Cu, Zn, As, Cd and Pb) were determined. The results showed that riverine sediment was significantly polluted by Cr (content range: 13.8-469mgkg -1 ), Ni (14.1-257mgkg -1 ), Cu (10.8-630mgkg -1 ), Zn (50.2-1700mgkg -1 ) and Cd (0.172-2.26mgkg -1 ). The geoaccumulation indices (I geo ) of trace metals decreased in the order Cd>Zn>Ni>Cu>Co>Cr>Pb>As>V. The pollution load indices and potential ecological risk indices (RI) at the sampling sites were similar, with more severe pollution and greater risk presenting in the upper and middle reaches (S1-S6) compared with the lower reaches (S7 and S8). Cd contributed significantly (77.2-87.6%) to the RI. Source identification based on multivariate statistical techniques, including principal component analysis (PCA), correlation analysis (CA) and hierarchical cluster analysis (HACA), was performed to differentiate the origins of trace metals. PCA and CA yielded similar results, indicating that As and V originated from natural sources (e.g., parent materials) and that the other metals were related to anthropogenic activities. HACA based on the I geo showed that Cd was associated mainly with fertilizers, and the origins of Cr, Ni, Cu and Zn were probably industrial effluents, whereas Co and Pb were related to traffic activities. HACA of sediment cores suggested that Dongguan and Shenzhen cities contribute large quantities of metals to the riverine sediment, whereas few metals were discharged from Huizhou City. Copyright © 2016 Elsevier Inc. All rights reserved.

Global Drainage Patterns to Modern Terrestrial Sedimentary Basins and its Influence on Large River Systems

NASA Astrophysics Data System (ADS)

Nyberg, B.; Helland-Hansen, W.

2017-12-01

Long-term preservation of alluvial sediments is dependent on the hydrological processes that deposit sediments solely within an area that has available accomodation space and net subsidence know as a sedimentary basin. An understanding of the river processes contributing to terrestrial sedimentary basins is essential to fundamentally constrain and quantify controls on the modern terrestrial sink. Furthermore, the terrestrial source to sink controls place constraints on the entire coastal, shelf and deep marine sediment routing systems. In addition, the geographical importance of modern terrestrial sedimentary basins for agriculture and human settlements has resulted in significant upstream anthropogenic catchment modification for irrigation and energy needs. Yet to our knowledge, a global catchment model depicting the drainage patterns to modern terrestrial sedimentary basins has previously not been established that may be used to address these challenging issues. Here we present a new database of 180,737 global catchments that show the surface drainage patterns to modern terrestrial sedimentary basins. This is achieved by using high resolution river networks derived from digital elevation models in relation to newly acquired maps on global modern sedimentary basins to identify terrestrial sinks. The results show that active tectonic regimes are typically characterized by larger terrestrial sedimentary basins, numerous smaller source catchments and a high source to sink relief ratio. To the contrary passive margins drain catchments to smaller terrestrial sedimentary basins, are composed of fewer source catchments that are relatively larger and a lower source to sink relief ratio. The different geomorphological characteristics of source catchments by tectonic setting influence the spatial and temporal patterns of fluvial architecture within sedimentary basins and the anthropogenic methods of exploiting those rivers. The new digital database resource is aimed to help the geoscientific community to contribute further to our quantitative understanding of source-to-sink systems and its allogenic and autogenic controls, geomorphological characteristics, terrestrial sediment transit times and the anthropogenic impact on those systems.

Sources of sedimentary PAHs in tropical Asian waters: differentiation between pyrogenic and petrogenic sources by alkyl homolog abundance.

PubMed

Saha, Mahua; Togo, Ayako; Mizukawa, Kaoruko; Murakami, Michio; Takada, Hideshige; Zakaria, Mohamad P; Chiem, Nguyen H; Tuyen, Bui Cach; Prudente, Maricar; Boonyatumanond, Ruchaya; Sarkar, Santosh Kumar; Bhattacharya, Badal; Mishra, Pravakar; Tana, Touch Seang

2009-02-01

We collected surface sediment samples from 174 locations in India, Indonesia, Malaysia, Thailand, Vietnam, Cambodia, Laos, and the Philippines and analyzed them for polycyclic aromatic hydrocarbons (PAHs) and hopanes. PAHs were widely distributed in the sediments, with comparatively higher concentrations in urban areas (Sigma PAHs: approximately 1000 to approximately 100,000 ng/g-dry) than in rural areas ( approximately 10 to approximately 100g-dry), indicating large sources of PAHs in urban areas. To distinguish petrogenic and pyrogenic sources of PAHs, we calculated the ratios of alkyl PAHs to parent PAHs: methylphenanthrenes to phenanthrene (MP/P), methylpyrenes+methylfluoranthenes to pyrene+fluoranthene (MPy/Py), and methylchrysenes+methylbenz[a]anthracenes to chrysene+benz[a]anthracene (MC/C). Analysis of source materials (crude oil, automobile exhaust, and coal and wood combustion products) gave thresholds of MP/P=0.4, MPy/Py=0.5, and MC/C=1.0 for exclusive combustion origin. All the combustion product samples had the ratios of alkyl PAHs to parent PAHs below these threshold values. Contributions of petrogenic and pyrogenic sources to the sedimentary PAHs were uneven among the homologs: the phenanthrene series had a greater petrogenic contribution, whereas the chrysene series had a greater pyrogenic contribution. All the Indian sediments showed a strong pyrogenic signature with MP/P approximately 0.5, MPy/Py approximately 0.1, and MC/C approximately 0.2, together with depletion of hopanes indicating intensive inputs of combustion products of coal and/or wood, probably due to the heavy dependence on these fuels as sources of energy. In contrast, sedimentary PAHs from all other tropical Asian cities were abundant in alkylated PAHs with MP/P approximately 1-4, MPy/Py approximately 0.3-1, and MC/C approximately 0.2-1.0, suggesting a ubiquitous input of petrogenic PAHs. Petrogenic contributions to PAH homologs varied among the countries: largest in Malaysia whereas inferior in Laos. The higher abundance of alkylated PAHs together with constant hopane profiles suggests widespread inputs of automobile-derived petrogenic PAHs to Asian waters.

Aliphatic hydrocarbons and triterpenes of the Congo deep-sea fan

NASA Astrophysics Data System (ADS)

Méjanelle, Laurence; Rivière, Béatrice; Pinturier, Laurence; Khripounoff, Alexis; Baudin, François; Dachs, Jordi

2017-08-01

Hydrocarbons were analyzed in sediments from the Congo River deep-sea fan, from the Congo River, and in sinking particles collected by sediment traps 40 m above the sediment. Studied sites encompassed three lobes of decreasing age of formation along the canyon: sites A, F and C and a another lobe system, disconnected from the active channel since 4 ka, Site E. Terrestrial long-chain odd n-alkanes were dominant in all sediments of the lobe system. Unsaturated terpenoids sourced by higher plants, such as gammacerene, lupene, ursene and oleanene, were also detected. At site C, characterized by high accumulation rates (10-20 cm yr-1), the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations 10-17 μg gOC-1) evidenced recent terrestrial and phytoplanktonic remains reworked in anaerobic conditions. In these sediments, organic carbon-normalized concentrations of terrestrial alkanes and terpenoids were several fold higher than in the lobe sediments with lower accumulation rates (sites A and F), arguing for a more rapid degradation of terrestrial hydrocarbons than bulk organic carbon in the first steps of pre-diagenesis. Ample variations in the contributions of biomarkers from higher plants, ferns, bacteria and angiosperms, indicate an heterogeneous contribution of the soil and vegetation detritus delivered to the Congo lobe sediments. Lower concentrations in terrestrial hydrocarbons at site E, 45 km away from the active canyon, indicated that river particles are still admixed to the dominant marine organic matter. Diploptene and hop-7(21)-ene have a dual origin, from terrestrial and marine microorganisms. Scatter in their relationship to gammacerene argues for a contribution of marine microorganisms, in addition to soils-sourced microorganisms. The close distribution patterns of diploptene, hop-21-ene, hop-7(21)ene and neohop-13(18)-ene is in line with the hypothesis of sequential clay-catalyzed isomerisation of bacterial hopenes. Terrestrial biomarker accumulation fluxes at site C are one order of magnitude higher than vertical pelagic flux, demonstrating the magnitude of the inputs delivered through turbiditic transport in the submarine canyon. Crude oil contamination was evidenced at the disconnected site E (UCM, C21 to C26 tricyclic diterpanes, CPI) and, in smaller amounts, in some sediments from sites A and C. It may be related to marine crude oil extraction and transport. A short-chain mode of alkanes with an even predominance is evidenced in sediments of the lobe complex and likely sources, crude oil, microorganisms and ferns, are discussed.

Terrigenous sediment supply along the Chilean continental margin: modern regional patterns of texture and composition

NASA Astrophysics Data System (ADS)

Lamy, F.; Hebbeln, D.; Wefer, G.

The regional patterns of texture and composition of modern continental slope and pelagic sediments off Chile between 25°S and 43°S reflect the latitudinal segmentation of geological, morphological, and climatic features of the continental hinterland. Grain-size characteristics are controlled by the grain-size of source rocks, the weathering regime, and mode of sediment input (eolian off northern Chile vs fluvial further south). Bulk-mineral assemblages reveal a low grade of maturity. Regional variations are governed by the source-rock composition of the different geological terranes and the relative source-rock contribution of the Coastal Range and Andes, as controlled by the continental hydrology. The relative abundance of clay minerals is also predominantly influenced by the source-rock composition and partly by continental smectite neoformation. Latitudinal variations of illite crystallinities along the Chilean continental slope (and west of the Peru-Chile trench) clearly reflect modifications of the weathering regime which correspond to the strong climatic zonation of Chile.

Quantifying the seasonal variations in fluvial and eolian sources of terrigenous material to Cariaco Basin, Venezuela

NASA Astrophysics Data System (ADS)

Elmore, Aurora C.; Thunell, Robert C.; Styles, Richard; Black, David; Murray, Richard W.; Martinez, Nahysa; Astor, Yrene

2009-02-01

The varved sediments that accumulate in the Cariaco Basin provide a detailed archive of the region's climatic history, including a record of the quantity of fluvial and wind-transported material. In this study, we examine the sedimentological characteristics (clay mineralogy and grain size) of both surface sediments and sinking lithogenic material collected from sediment trap samples over a three-year period from 1997 to 2000. Data from biweekly sediment trap samples show a tri-modal particle size distribution, with prominent peaks at 2, 22 and 80 μm, indicating sediment contributions from both eolian and fluvial sources. The clay mineralogy of the water column samples collected from 1997 to 1999 also shows distinctive characteristics of eolian and fluvial material. An examination of surface sediment samples from the Cariaco Basin indicates that the Unare River is the main source of riverine sediments to the eastern sub-basin. By combining these sedimentological proxies, we estimate that ˜10% of the terrigenous material delivered to the Cariaco Basin is eolian, while ˜90% is fluvial. This represents an annual dust accumulation rate of ˜0.59 mg/cm 2/yr. Since aerosols are closely linked to climate variability, the ability to quantify paleo-dust fluxes using sedimentological characteristics will be a useful tool for future paleoclimate studies looking at sub-Saharan aridity and latitudinal migration of the Intertropical Convergence Zone.

Low-maturity Kulthieth Formation coal: A possible source of polycyclic aromatic hydrocarbons in benthic sediment of the northern Gulf of Alaska

USGS Publications Warehouse

Van Kooten, G. K.; Short, J.W.; Kolak, J.J.

2002-01-01

The successful application of forensic geology to contamination studies involving natural systems requires identification of appropriate endmembers and an understanding of the geologic setting and processes affecting the systems. Studies attempting to delineate the background, or natural, source for hydrocarbon contamination in Gulf of Alaska (GOA) benthic sediments have invoked a number of potential sources, including seep oils, source rocks, and coal. Oil seeps have subsequently been questioned as significant sources of hydrocarbons present in benthic sediments of the GOA in part because the pattern of relative polycyclic aromatic hydrocarbon (PAH) abundance characteristic of benthic GOA sediments is inconsistent with patterns typical of weathered seep oils. Likewise, native coal has been dismissed in part because ratios of labile hydrocarbons to total organic carbon (e.g. PAH:TOC) for Bering River coal field (BRCF) sources are too low - i.e. the coals are over mature - to be consistent with GOA sediments. We present evidence here that native coal may have been prematurely dismissed, because BRCF coals do not adequately represent the geochemical signatures of coals elsewhere in the Kulthieth Formation. Contrary to previous thought, Kulthieth Formation coals east of the BRCF have much higher PAH: TOC ratios, and the patterns of labile hydrocarbons in these low thermal maturity coals suggest a possible genetic relationship between Kulthieth Formation coals and nearby oil seeps on the Sullivan anticline. Analyses of low-maturity Kulthieth Formation coal indicate the low maturity coal is a significant source of PAH. Source apportionment models that neglect this source will underestimate the contribution of native coals to the regional background hydrocarbon signature. ?? Published by Elsevier Science Ltd. on behalf of AEHS.

Application of hierarchical Bayesian unmixing models in river sediment source apportionment

NASA Astrophysics Data System (ADS)

Blake, Will; Smith, Hugh; Navas, Ana; Bodé, Samuel; Goddard, Rupert; Zou Kuzyk, Zou; Lennard, Amy; Lobb, David; Owens, Phil; Palazon, Leticia; Petticrew, Ellen; Gaspar, Leticia; Stock, Brian; Boeckx, Pacsal; Semmens, Brice

2016-04-01

Fingerprinting and unmixing concepts are used widely across environmental disciplines for forensic evaluation of pollutant sources. In aquatic and marine systems, this includes tracking the source of organic and inorganic pollutants in water and linking problem sediment to soil erosion and land use sources. It is, however, the particular complexity of ecological systems that has driven creation of the most sophisticated mixing models, primarily to (i) evaluate diet composition in complex ecological food webs, (ii) inform population structure and (iii) explore animal movement. In the context of the new hierarchical Bayesian unmixing model, MIXSIAR, developed to characterise intra-population niche variation in ecological systems, we evaluate the linkage between ecological 'prey' and 'consumer' concepts and river basin sediment 'source' and sediment 'mixtures' to exemplify the value of ecological modelling tools to river basin science. Recent studies have outlined advantages presented by Bayesian unmixing approaches in handling complex source and mixture datasets while dealing appropriately with uncertainty in parameter probability distributions. MixSIAR is unique in that it allows individual fixed and random effects associated with mixture hierarchy, i.e. factors that might exert an influence on model outcome for mixture groups, to be explored within the source-receptor framework. This offers new and powerful ways of interpreting river basin apportionment data. In this contribution, key components of the model are evaluated in the context of common experimental designs for sediment fingerprinting studies namely simple, nested and distributed catchment sampling programmes. Illustrative examples using geochemical and compound specific stable isotope datasets are presented and used to discuss best practice with specific attention to (1) the tracer selection process, (2) incorporation of fixed effects relating to sample timeframe and sediment type in the modelling process, (3) deriving and using informative priors in sediment fingerprinting context and (4) transparency of the process and replication of model results by other users.

Sources and contamination rate of port sediments: evidences from dimensional, mineralogical, and chemical investigations

NASA Astrophysics Data System (ADS)

Lucchetti, Gabriella; Cutroneo, Laura; Carbone, Cristina; Consani, Sirio; Vagge, Greta; Canepa, Giuseppe; Capello, Marco

2017-04-01

Ports are complex environments due to their complicated geometry (quays, channels, and piers), the presence of human activities (vessel traffic, yards, industries, and discharges), and natural factors (stream and torrent inputs, sea action, and currents). Due to the many activities that take place in a port, sediments and waters are often contaminated by different kinds of chemicals, such as hydrocarbons, dioxins, pesticides, nutrients, and metals. The contamination rate of a port basin is site specific and depends on the sources of contamination in the nearby urban system as well as the port system itself, such as city discharges and sewers, river intake, vessel traffic, factories (Taylor and Owens, 2009). Moreover, two important sources and vehicles of contaminants are: a) anthropogenic road deposited sediments derived from the runoff of the port and city area, and natural road deposited sediments derived from rivers and torrents, and b) airborne particulate matter and sediments (Taylor and Owens, 2009). The Port of Genoa is situated at the apex of the Ligurian Sea in the north western Mediterranean Sea and is characterised by the presence of several commercial activities that have contributed, over the years, and still contribute today, to the contaminant accumulation in both the water column and the bottom sediments. This port basin includes the mouth of several streams and the mouth of the Bisagno and the Polcevera Torrents, along the banks of which can be found several small towns, quarries, factories, and the suburbs of the city of Genoa, a ferry terminal, different container terminals, marinas, dry docks, the coal power plant of Genoa, and different wastewater treatment plant discharges. Starting from these considerations, we have examined the marine environment of a port from the point of view of the water mass circulation, hydrological characteristics, distribution of the sediment grain size, mineralogical characteristics, and metal concentrations of the bottom sediments. Our results show that, in the case of the Port of Genoa (north western Italy), both the impact of the human activities (such as coal power plant, oil depots, yards, dredging of the bottom sediments, etc.) and the natural processes (such as currents, fresh water and sediment inputs from the torrents), together with the morphology of the basin, are important factors in sediment, water and metal distributions and give rise to a complex environment. Taylor, K.G., Owens, P.N., 2009. Sediments in urban river basins: a review of sediment contaminant dynamics in an environmental system conditioned by human activities. Journal of Soils and Sediments 9: 281-303.

Natural thorium isotopes in marine sediment core off Labuan port

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.

2014-02-12

Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. Themore » sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.« less

Spatial and temporal dynamics of sediment in contrasted mountainous watersheds (Mexican transvolcanic belt and French Southern Alps) combining river gauging, elemental geochemistry and fallout radionuclides

NASA Astrophysics Data System (ADS)

Evrard, O.; Navratil, O.; Gratiot, N.; Némery, J.; Duvert, C.; Ayrault, S.; Lefèvre, I.; Legout, C.; Bonté, P.; Esteves, M.

2009-12-01

In mountainous environments, an excessive fine sediment supply to the rivers typically leads to an increase in water turbidity, contaminant transport and a rapid filling of reservoirs. This situation is particularly problematic in regions where water reservoirs are used to provide drinking water to large cities (e.g. in central Mexico) or where stream water is used to run hydroelectric power plants (e.g. in the French Southern Alps). In such areas, sediment source areas first need to be delineated and sediment fluxes between hillslopes and the river system must be better understood before implementing efficient erosion control measures. In this context, the STREAMS (« Sediment Transport and Erosion Across MountainS ») project funded by the French National Research Agency (ANR) aims at understanding the spatial and temporal dynamics of sediment at the scale of mountainous watersheds (between 500 - 1000 km2) located in contrasted environments. This 3-years study is carried out simultaneously in a volcanic watershed located in the Mexican transvolcanic belt undergoing a subhumid tropical climate, as well as in a sedimentary watershed of the French Southern Alps undergoing a transitional climate with Mediterranean and continental influences. One of the main specificities of this project consists in combining traditional monitoring techniques (i.e. installation of river gauges, turbidimeters and sediment samplers in several sub-catchments) and sediment fingerprinting using elemental geochemistry (measured by Instrumental Neutron Activation Analysis - INAA - and Inductively Coupled Plasma - Mass Spectrometry - ICP-MS) and fallout radionuclides (measured by gamma spectrometry). In the French watershed, geochemical analysis allows outlining different sediment sources (e.g. the contribution of calcareous vs. marl-covered sub-watersheds). Radionuclide ratios (e.g.Be-7/Cs-137) allow identifying the dominant erosion processes occurring within the watershed. Areas mostly affected by gully erosion, rill or sheet erosion have been delineated. Furthermore, the measurement of radionuclide content in suspended sediment after the snowmelt suggests that most of this sediment consists in resuspended material rather than on newly eroded soil. In the Mexican watershed, a different contribution of andisols and acrisols to erosion is suspected. Overall, the bulk of erosion is generated by rather small areas within the watershed. In this region characterised by a succession of wet and dry seasons, the Be-7 content in rainfall and sediment has been measured at the scale of a 2.5 km2 sub-watershed in order to better understand the erosion transfer between hillslopes and rivers during the rainy season. This outlines the contribution of individual storms to seasonal erosion. Overall, this study brings important insights about sediment sources and fluxes within these watersheds located in contrasted environments. A further step consists in comparing experimental results with model outputs, and to evaluate the impact of on-going erosion mitigation measures.

Pu and 137Cs in the Yangtze River estuary sediments: distribution and source identification.

PubMed

Liu, Zhiyong; Zheng, Jian; Pan, Shaoming; Dong, Wei; Yamada, Masatoshi; Aono, Tatsuo; Guo, Qiuju

2011-03-01

Pu isotopes and (137)Cs were analyzed using sector field ICP-MS and γ spectrometry, respectively, in surface sediment and core sediment samples from the Yangtze River estuary. (239+240)Pu activity and (240)Pu/(239)Pu atom ratios (>0.18) shows a generally increasing trend from land to sea and from north to south in the estuary. This spatial distribution pattern indicates that the Pacific Proving Grounds (PPG) source Pu transported by ocean currents was intensively scavenged into the suspended sediment under favorable conditions, and mixed with riverine sediment as the water circulated in the estuary. This process is the main control for the distribution of Pu in the estuary. Moreover, Pu is also an important indicator for monitoring the changes of environmental radioactivity in the estuary as the river basin is currently the site of extensive human activities and the sea level is rising because of global climate changes. For core sediment samples the maximum peak of (239+240)Pu activity was observed at a depth of 172 cm. The sedimentation rate was estimated on the basis of the Pu maximum deposition peak in 1963-1964 to be 4.1 cm/a. The contributions of the PPG close-in fallout Pu (44%) and the riverine Pu (45%) in Yangtze River estuary sediments are equally important for the total Pu deposition in the estuary, which challenges the current hypothesis that the riverine Pu input was the major source of Pu budget in this area.

Crushing of Subglacial Lake Sediment as a Source of Bio-utilisable Gases.

NASA Astrophysics Data System (ADS)

Gill Olivas, B.; Telling, J.; Michaud, A. B.; Skidmore, M. L.; Priscu, J. C.; Tranter, M.

2017-12-01

Recent research has shown microbial ecosystems exist under glaciers and ice sheets. The sources of energy to support these ecosystems are still not fully understood, particularly beneath the Antarctic Ice Sheet, where direct access to the atmosphere and in-washed organic matter and oxidising agents does not occur. Hence, sub-ice sheet energy sources are restricted to those in subglacial environments, except for ice-margin environments. This study focuses on sediments from Subglacial Lake Whillans (SLW), the first subglacial lake to be directly and cleanly sampled. Sediment from three depths in a shallow core extracted from SLW were used to assess the possible energy contributions from mechanochemical reactions to this subglacial ecosystem. To do this, the samples were crushed under an anoxic atmosphere using a ball mill. The sediments were then transferred into serum bottles under anoxic conditions. They were wetted and the headspace gas was subsequently sampled and analysed during a 40 day incubation. Results show the release of substantial amounts of hydrogen, which could potentially serve as an abiotic source of energy to microbes, in particular, methanogenic archaea. Significant amounts of short chain hydrocarbons (including methane and ethylene), possibly from the reactivation of ancient organic carbon, were also observed. Crushed samples showed a significant concentration of hydrogen peroxide produced on contact with water, as well as significant amounts of Si radicals, showing comminution of these sediments unlocks the potential for a wide range of redox conditions and reactions to develop within glacially eroded sediment under ice. This in turn provides a previously overlooked source of nutrients and energy for microbes to utilise.

Contributions of human activities to suspended sediment yield during storm events from a small, steep, tropical watershed

NASA Astrophysics Data System (ADS)

Messina, A. M.; Biggs, T. W.

2016-07-01

Suspended sediment concentrations (SSC) and yields (SSY) were measured during storm and non-storm periods from undisturbed and human-disturbed portions of a small (1.8 km2), mountainous watershed that drains to a sediment-stressed coral reef. Event-wise SSY (SSYEV) was calculated for 142 storms from measurements of water discharge (Q), turbidity (T), and SSC measured downstream of three key sediment sources: undisturbed forest, an aggregate quarry, and a village. SSC and SSYEV were significantly higher downstream of the quarry during both storm- and non-storm periods. The human-disturbed subwatershed (10.1% disturbed) accounted for an average of 87% of SSYEV from the watershed. Observed sediment yield (mass) to the coast, including human disturbed subwatersheds, was 3.9× the natural background. Specific SSY (mass/area) from the disturbed quarry area was 49× higher than from natural forest compared with 8× higher from the village area. Similar to mountainous watersheds in semi-arid and temperate climates, SSYEV from both the undisturbed and disturbed watersheds correlated closely with maximum event discharge (Qmax), event total precipitation and event total Q, but not with the Erosivity Index. Best estimates of annual SSY varied by method, from 45 to 143 tons/km2/yr from the undisturbed subwatershed, 441-598 tons/km2/yr from the human-disturbed subwatershed, and 241-368 tons/km2/yr from the total watershed. Sediment yield was very sensitive to disturbance; the quarry covers 1.1% of the total watershed area, but contributed 36% of SSYEV. Given the limited access to gravel for infrastructure development, sediment disturbance from local aggregate mining may be a critical sediment source on remote islands in the Pacific and elsewhere. Identification of erosion hotspots like the quarry using rapid, event-wise measures of suspended sediment yield will help efforts to mitigate sediment stress and restore coral reefs.

Sources and turnover of organic carbon and methane in fjord and shelf sediments off northern Norway

NASA Astrophysics Data System (ADS)

Sauer, Simone; Hong, Wei-Li; Knies, Jochen; Lepland, Aivo; Forwick, Matthias; Klug, Martin; Eichinger, Florian; Baranwal, Soma; Crémière, Antoine; Chand, Shyam; Schubert, Carsten J.

2016-10-01

To better understand the present and past carbon cycling and transformation processes in methane-influenced fjord and shelf areas of northern Norway, we compared two sediment cores from the Hola trough and from Ullsfjorden. We investigated (1) the organic matter composition and sedimentological characteristics to study the sources of organic carbon (Corg) and the factors influencing Corg burial, (2) pore water geochemistry to determine the contribution of organoclastic sulfate reduction and methanogenesis to total organic carbon turnover, and (3) the carbon isotopic signature of hydrocarbons to identify the carbon transformation processes and gas sources. High sedimentation and Corg accumulation rates in Ullsfjorden support the notion that fjords are important Corg sinks. The depth of the sulfate-methane-transition (SMT) in the fjord is controlled by the supply of predominantly marine organic matter to the sediment. Organoclastic sulfate reduction accounts for 60% of the total depth-integrated sulfate reduction in the fjord. In spite of the presence of ethane, propane, and butane, we suggest a purely microbial origin of light hydrocarbons in the sediments based on their low δ13C values. In the Hola trough, sedimentation and Corg accumulation rates changed during the deglacial-to-post-glacial transition from approximately 80 cm ka-1 to erosion at present. Thus, Corg burial in this part of the shelf is presently absent. Low organic matter content in the sediment and low rates of organoclastic sulfate reduction (only 3% of total depth-integrated sulfate reduction) entail that the shallow depth of the SMT is controlled mostly by ascending thermogenic methane from deeper sources.

A mixing-model approach to quantifying sources of organic matter to salt marsh sediments

NASA Astrophysics Data System (ADS)

Bowles, K. M.; Meile, C. D.

2010-12-01

Salt marshes are highly productive ecosystems, where autochthonous production controls an intricate exchange of carbon and energy among organisms. The major sources of organic carbon to these systems include 1) autochthonous production by vascular plant matter, 2) import of allochthonous plant material, and 3) phytoplankton biomass. Quantifying the relative contribution of organic matter sources to a salt marsh is important for understanding the fate and transformation of organic carbon in these systems, which also impacts the timing and magnitude of carbon export to the coastal ocean. A common approach to quantify organic matter source contributions to mixtures is the use of linear mixing models. To estimate the relative contributions of endmember materials to total organic matter in the sediment, the problem is formulated as a constrained linear least-square problem. However, the type of data that is utilized in such mixing models, the uncertainties in endmember compositions and the temporal dynamics of non-conservative entitites can have varying affects on the results. Making use of a comprehensive data set that encompasses several endmember characteristics - including a yearlong degradation experiment - we study the impact of these factors on estimates of the origin of sedimentary organic carbon in a saltmarsh located in the SE United States. We first evaluate the sensitivity of linear mixing models to the type of data employed by analyzing a series of mixing models that utilize various combinations of parameters (i.e. endmember characteristics such as δ13COC, C/N ratios or lignin content). Next, we assess the importance of using more than the minimum number of parameters required to estimate endmember contributions to the total organic matter pool. Then, we quantify the impact of data uncertainty on the outcome of the analysis using Monte Carlo simulations and accounting for the uncertainty in endmember characteristics. Finally, as biogeochemical processes can alter endmember characteristics over time, we investigate the effect of early diagenesis on chosen parameters, an analysis that entails an assessment of the organic matter age distribution. Thus, estimates of the relative contributions of phytoplankton, C3 and C4 plants to bulk sediment organic matter depend not only on environmental characteristics that impact reactivity, but also on sediment mixing processes.

Diploptene: an indicator of terrigenous organic carbon in Washington coastal sediments

NASA Technical Reports Server (NTRS)

Prahl, F. G.; Hayes, J. M.

1992-01-01

The pentacyclic triterpene 17 beta(H),21 beta(H)-hop-22(29)-ene (diploptene) occurs in sediments throughout the Columbia River drainage basin and off the southern coast of Washington state in concentrations comparable to long-chain plantwax n-alkanes. The same relationship is evident for diploptene and long-chain n-alkanes in soils from the Willamette Valley. Microorganisms indigenous to soils and soil erosion are indicated as the biological source and physical process, respectively, for diploptene in coastal sediments. Similarity between the stable carbon isotopic composition (delta 13CPDB) of diploptene isolated from soil in the Willamette Valley (-31.2 +/- 0.3%) and from sediments deposited throughout the Washington coastal environment (-31.2 +/- 0.5%) supports this argument. Values of delta for diploptene in river sediments are variable and 8-17% lighter, indicating that an additional biological source such as methane-oxidizing bacteria makes a significant contribution to the diploptene record in river sediments. Selective biodegradation resulting from a difference in the physicochemical association within eroded particles can explain the absence of the more-13C-depleted form of diploptene in Washington coastal sediments, but this mechanism remains unproven.

(dis)connectivity in Catchment-Scale Sediment Cascades: Forecasting Responses in Sediment Flux Associated with Various Forms of Environmental Change

NASA Astrophysics Data System (ADS)

Fryirs, K.

2010-12-01

Fluvial systems are key elements that drive Earth surface change because they convey most of the global fluxes of water and sediment from land to oceans. Fluvial fluxes of water and sediment also drive a significant proportion of the terrestrial biochemical cycling of carbon, nutrients and pollutants. Understanding the internal dynamics of the sediment cascade is therefore critical to forecasting how environmental change, whether driven by extrinsic climate change, or intrinsic human-disturbance, might affect biochemical fluxes. To understand the internal dynamics of sediment flux requires a framework that can incorporate the various processes involved in the movement of sediment from the source area through the basin system to the outlet, and can take account of spatial variability within the system and the timeframes over which these processes operate. Traditionally a sediment budget approach has been used to quantify the sediment being supplied, transported and stored in various parts of catchments. In more recent years, a more sophisticated approach to analysis of catchment linkages and (dis)connectivity has been developed that incorporates both spatial and temporal variability in the operation of the sediment cascade. This framework is based on an understanding of longitudinal, lateral and vertical linkages in sediment flux in catchments, and where blockages occur to disrupt these linkages. These blockages have been termed buffers, barriers and blankets (Fryirs et al 2007). Depending on the position of these blockages, and their sediment residence time, various parts of catchment may be actively contributing sediment to the catchment sediment cascade and be switched on, or inactive and switched off. The degree of spatial connectivity determines the effective catchment area. The breaching capacity of buffers, barriers and blankets determines the effective timescale over which certain parts of a catchment are switched on. The sediment residence time and thresholds of stability dictate the timeframe over which certain parts of catchments are actively contributing sediment to the cascade. The manifestation of geomorphic change, and response times to disturbance can be modeled within such a framework. The notion that certain sediment sources and transport mechanisms may be switched on or switched off under various climate change scenarios can also be examined using this framework. Fryirs, K., Brierley, G. J., Preston, N. J. and Kasai, M. 2007. Buffers, barriers and blankets: The (dis)connectivity of catchment-scale sediment cascades. Catena, 70, 49-67

Sources, spatial variation, and speciation of heavy metals in sediments of the Tamagawa River in Central Japan.

PubMed

Shikazono, N; Tatewaki, K; Mohiuddin, K M; Nakano, T; Zakir, H M

2012-01-01

Sediments of the Tamagawa River in central Japan were studied to explain the spatial variation, to identify the sources of heavy metals, and to evaluate the anthropogenic influence on these pollutants in the river. Sediment samples were collected from 20 sites along the river (five upstream, four midstream, and 11 downstream). Heavy metal concentrations, viz. chromium, nickel, copper, zinc, lead, cadmium, and molybdenum, in the samples were measured using inductively coupled plasma-mass spectroscopy. The chemical speciations of heavy metals in the sediments were identified by the widely used five-step Hall method. Lead isotopes were analyzed to identify what portion is contributed by anthropogenic sources. The total heavy metal concentrations were compared with global averages for continental crust (shale) and average values for Japanese river sediments. The mean heavy metal concentrations were higher in downstream sediments than in upstream and midstream samples, and the concentrations in the silt samples were higher than those in the sand samples. Speciation results demonstrate that, for chromium and nickel, the residual fractions were dominant. These findings imply that the influence of anthropogenic chromium and nickel contamination is negligible, while copper, zinc, and lead were mostly extracted in the non-residual fraction (metals in adsorbed/exchangeable/carbonate forms or bound to amorphous Fe oxyhydroxides, crystalline Fe oxides, or organic matter), indicating that these elements have high chemical mobility. The proportion of lead (Pb) isotopes in the downstream silt samples indicates that Pb accumulation is primarily derived from anthropogenic sources.

Geochemical and Sr-Nd-Pb-Li isotopic characteristics of volcanic rocks from the Okinawa Trough: Implications for the influence of subduction components and the contamination of crustal materials

NASA Astrophysics Data System (ADS)

Guo, Kun; Zhai, Shikui; Yu, Zenghui; Wang, Shujie; Zhang, Xia; Wang, Xiaoyuan

2018-04-01

The Okinawa Trough is an infant back-arc basin developed along the Ryukyu arc. This paper provides new major and trace element and Sr-Nd-Pb-Li isotope data of volcanic rocks in the Okinawa Trough and combines the published geochemical data to discuss the composition of magma source, the influence of subduction component, and the contamination of crustal materials, and calculate the contribution between subduction sediment and altered oceanic crust in the subduction component. The results showed that there are 97% DM and 3% EMI component in the mantle source in middle trough (MS), which have been influenced by subduction sediment. The Li-Nd isotopes indicate that the contribution of subduction sediment and altered oceanic crust in subduction component are 4 and 96%, respectively. The intermediate-acidic rocks suffer from contamination of continental crust material in shallow magma chamber during fractional crystallization. The acidic rocks in south trough have experienced more contamination of crustal material than those from the middle and north trough segments.

Petroleum pollution in surface sediments of Daya Bay, South China, revealed by chemical fingerprinting of aliphatic and alicyclic hydrocarbons

NASA Astrophysics Data System (ADS)

Gao, Xuelu; Chen, Shaoyong

2008-10-01

Nine surface sediments collected from Daya Bay have been Soxhlet-extracted with 2:1 (v/v) dichloromethane-methanol. The non-aromatic hydrocarbon (NAH) fraction of solvent extractable organic matter (EOM) and some bulk geochemical parameters have been analyzed to determine petroleum pollution of the bay. The NAH content varies from 32 to 276 μg g -1 (average 104 μg g -1) dry sediment and accounts for 5.8-64.1% (average 41.6%) of the EOM. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and petrogenic sources in varying proportions. The contribution of marine authigenic input to the sedimentary n-alkanes is lower than the allochthonous input based on the average n-C 31/ n-C 19 alkane ratio. 25.6-46.5% of the n-alkanes, with a mean of 35.6%, are contributed by vascular plant wax. Results of unresolved complex mixture, isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. There is strong evidence of a common petroleum contamination source in the bay.

Plant Wax n-Alkane and n-Alkanoic Acid Signatures Overprinted by Microbial Contributions and Old Carbon in Meromictic Lake Sediments

NASA Astrophysics Data System (ADS)

Makou, Matthew; Eglinton, Timothy; McIntyre, Cameron; Montluçon, Daniel; Antheaume, Ingrid; Grossi, Vincent

2018-01-01

Specific n-alkanes and n-alkanoic acids are commonly used as biomarkers in paleoenvironmental reconstruction, yet any individual homologue may originate from multiple biological sources. Here we improve source and age controls for these compounds in meromictic systems by measuring the radiocarbon (14C) ages of specific homologues preserved in twentieth century Lake Pavin (France) sediments. In contrast to many studies, 14C ages generally decreased with increasing carbon chain length, from 7.3 to 2.6 ka for the C14-C30 n-alkanoic acids and from 9.2 to 0.3 ka for the C21-C33 n-alkanes. Given a known hard water effect, these values suggest that aquatic microbial sources predominate and contributed to most of the homologues measured. Only the longest chain n-alkanes exclusively represent inputs of higher plant waxes, which were previously sequestered in soils over centennial to millennial timescales prior to transport and deposition. These findings suggest that biomarker source and age should be carefully established for lacustrine settings.

Hydrocarbons in recent sediment of the Monterey Bay National Marine Sanctuary

USGS Publications Warehouse

Kvenvolden, K.A.; Hostettler, F.D.; Rosenbauer, R.W.; Lorenson, T.D.; Castle, W.T.; Sugarman, S.

2002-01-01

A complex mixture of hydrocarbons is present in the recent sediment of the Monterey Bay National Marine Sanctuary. Eighteen samples from the continental shelf between San Francisco and Monterey contain aliphatic and aromatic hydrocarbons showing biological contributions from both marine and terrigenous sources, with the terrigenous indicators more pronounced near Monterey. Of particular interest, however, is a low-level background of petroleum-related compounds, including 28,30-bisnorhopane and 18??+??(H)-oleanane, which are characteristic of many crude oils from the Monterey Formation of California. Thus, the sediments are overprinted by a regional chemical signature which may be derived from eroded Monterey Formation rocks and from onshore and offshore seeps releasing petroleum from Monterey Formation source rocks. ?? 2002 Elsevier Science B.V. All rights reserved.

Sediment Budgets and Sources Inform a Novel Valley Bottom Restoration Practice Impacted by Legacy Sediment: The Big Spring Run, PA, Restoration Experiment

NASA Astrophysics Data System (ADS)

Walter, R. C.; Merritts, D.; Rahnis, M. A.; Gellis, A.; Hartranft, J.; Mayer, P. M.; Langland, M.; Forshay, K.; Weitzman, J. N.; Schwarz, E.; Bai, Y.; Blair, A.; Carter, A.; Daniels, S. S.; Lewis, E.; Ohlson, E.; Peck, E. K.; Schulte, K.; Smith, D.; Stein, Z.; Verna, D.; Wilson, E.

2017-12-01

Big Spring Run (BSR), a small agricultural watershed in southeastern Pennsylvania, is located in the Piedmont Physiographic Province, which has the highest nutrient and sediment yields in the Chesapeake Bay watershed. To effectively reduce nutrient and sediment loading it is important to monitor the effect of management practices on pollutant reduction. Here we present results of an ongoing study, begun in 2008, to understand the impact of a new valley bottom restoration strategy for reducing surface water sediment and nutrient loads. We test the hypotheses that removing legacy sediments will reduce sediment and phosphorus loads, and that restoring eco-hydrological functions of a buried Holocene wetland (Walter & Merritts 2008) will improve surface and groundwater quality by creating accommodation space to trap sediment and process nutrients. Comparisons of pre- and post-restoration gage data show that restoration lowered the annual sediment load by at least 118 t yr-1, or >75%, from the 1000 m-long restoration reach, with the entire reduction accounted for by legacy sediment removal. Repeat RTK-GPS surveys of pre-restoration stream banks verified that >90 t yr-1 of suspended sediment was from bank erosion within the restoration reach. Mass balance calculations of 137Cs data indicate 85-100% of both the pre-restoration and post-restoration suspended sediment storm load was from stream bank sources. This is consistent with trace element data which show that 80-90 % of the pre-restoration outgoing suspended sediment load at BSR was from bank erosion. Meanwhile, an inventory of fallout 137Cs activity from two hill slope transects adjacent to BSR yields average modern upland erosion rates of 2.7 t ha-1 yr-1 and 5.1 t ha-1 yr-1, showing modest erosion on slopes and deposition at toe of slopes. We conclude that upland farm slopes contribute little soil to the suspended sediment supply within this study area, and removal of historic valley bottom sediment effectively reduced bank erosion and sediment and phosphorus loads. Enhanced deposition further contributed to load reductions; prior to restoration, there was no deposition on tile pads on the 1.5 m-high legacy sediment "floodplain" terrace, whereas after restoration deposition on the low, restored floodplain showed net accumulation of 0.009 ± 0.012 m yr-1.

Sediment contributions from floodplains and legacy sediments to Piedmont streams of Baltimore County, Maryland

NASA Astrophysics Data System (ADS)

Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen

2015-04-01

Disparity between watershed erosion rates and downstream sediment delivery has remained an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a common focus. In the Piedmont Province of the eastern USA, upland deforestation and agricultural land use following European settlement led to accumulation of thick packages of overbank sediment in valley bottoms, commonly referred to as legacy deposits. Previous authors have argued that legacy deposits represent a potentially important source of modern sediment loads following remobilization by lateral migration and progressive channel widening. This paper seeks to quantify (1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, (2) proportions of streambank sediment derived from legacy deposits, and (3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We calculated measurable gross erosion and deposition rates within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 in Baltimore County, Maryland. We compared stream channel and floodplain morphology from lidar-based digital elevation data collected in 2005 with channel positions recorded on 1:2400 scale topographic maps from 1959-1961 in order to quantify 44-46 years of channel change. Sediment bulk density and particle size distributions were characterized from streambank and channel deposit samples and used for volume to mass conversions and for comparison with other sediment sources. Average annual lateral migration rates ranged from 0.04 to 0.19 m/y, which represented an annual migration of 2.5% (0.9-4.4%) channel width across all study segments, suggesting that channel dimensions may be used as reasonable predictors of bank erosion rates. Gross bank erosion rates varied from 43 to 310 Mg/km/y (median = 114) and were positively correlated with drainage area. Measured deposition within channels accounted for an average of 46% (28-75%) of gross erosion, with deposition increasingly important in larger drainages. Legacy sediments accounted for 6-90% of bank erosion at individual study segments, represented about 60% of bank height at most exposures, and accounted for 57% (± 16%) of the measured gross erosion. Extrapolated results indicated that first- and second-order streams accounted for 62% (± 38%) of total streambank erosion from 1005 km2 of northern Baltimore County. After accounting for estimated redeposition, extrapolated net streambank sediment yields (72 Mg/km2/y) constituted 70% of estimated average Piedmont watershed yields (104 Mg/km2/y). The results suggest that streambank sediments are a relatively large source of sediment from Piedmont tributaries to the Chesapeake Bay.

Sediment contributions from floodplains and legacy sediments to Piedmont streams of Baltimore County, Maryland

USGS Publications Warehouse

Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen C.

2015-01-01

Disparity between watershed erosion rates and downstream sediment delivery has remained an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a common focus. In the Piedmont Province of the eastern USA, upland deforestation and agricultural land use following European settlement led to accumulation of thick packages of overbank sediment in valley bottoms, commonly referred to as legacy deposits. Previous authors have argued that legacy deposits represent a potentially important source of modern sediment loads following remobilization by lateral migration and progressive channel widening. This paper seeks to quantify (1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, (2) proportions of streambank sediment derived from legacy deposits, and (3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont.We calculated measurable gross erosion and deposition rates within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 in Baltimore County, Maryland. We compared stream channel and floodplain morphology from lidar-based digital elevation data collected in 2005 with channel positions recorded on 1:2400 scale topographic maps from 1959–1961 in order to quantify 44–46 years of channel change. Sediment bulk density and particle size distributions were characterized from streambank and channel deposit samples and used for volume to mass conversions and for comparison with other sediment sources.Average annual lateral migration rates ranged from 0.04 to 0.19 m/y, which represented an annual migration of 2.5% (0.9–4.4%) channel width across all study segments, suggesting that channel dimensions may be used as reasonable predictors of bank erosion rates. Gross bank erosion rates varied from 43 to 310 Mg/km/y (median = 114) and were positively correlated with drainage area. Measured deposition within channels accounted for an average of 46% (28–75%) of gross erosion, with deposition increasingly important in larger drainages. Legacy sediments accounted for 6–90% of bank erosion at individual study segments, represented about 60% of bank height at most exposures, and accounted for 57% (± 16%) of the measured gross erosion. Extrapolated results indicated that first- and second-order streams accounted for 62% (± 38%) of total streambank erosion from 1005 km2 of northern Baltimore County. After accounting for estimated redeposition, extrapolated net streambank sediment yields (72 Mg/km2/y) constituted 70% of estimated average Piedmont watershed yields (104 Mg/km2/y). The results suggest that streambank sediments are a relatively large source of sediment from Piedmont tributaries to the Chesapeake Bay.

Processes affecting the spatial distribution of seagrass meadow sedimentary material on Yao Yai Island, Thailand

NASA Astrophysics Data System (ADS)

Quak, Michelle S. Y.; Ziegler, Alan D.; Benner, Shawn G.; Evans, Sam; Todd, Peter A.; Gillis, Lucy G.; Vongtanaboon, Sukanya; Jachowski, Nick; Bouma, Tjeerd J.

2016-12-01

Many islands throughout SE Asia are experiencing rapid development and land-cover conversion that potentially threaten sensitive coastal ecosystems, such as seagrasses, through increased loading of sediment and nutrients originating from disturbed catchments draining to the sea. To evaluate this threat for one such island in Southern Thailand (Yao Yai), we perform sediment source tracing via end-member mixing analysis using stable isotopes δ13C and δ15N in organic matter to explore sediment loading in a seagrass meadow. The analysis indicates that sedimentary material in the meadow originates mostly from ocean-associated sources (∼62% from seagrass detritus, seston, and ocean sediments). Terrestrial material comprises ∼19% of the organic material found in the seagrass meadow, with another 20% originating from an adjacent mangrove forest. Approximately one-fourth of the seagrass meadow material (24%) is detritus that has been (re)deposited internally. The high contribution of terrestrial-derived organic matter deposited near the river mouth demonstrates that substantial quantities of sediment are being transferred from upslope erosion sources into the seagrass meadow. However, only a small amount of this material is deposited throughout the entire bay because much of the terrestrial- and mangrove-derived sediment is transferred to the open ocean via channels that are periodically dredged to allow boat access to two small inland harbours. This positive affect of dredging has not received very much attention in existing literature. River water flowing to the channels during falling tide delivers sediment to these efficient pathways, where much of it bypasses the seagrass meadow at periods of time when sediment deposition would normally be the greatest. There is growing concern that ongoing land-cover changes and planned urbanization related to tourism and agriculture on the island may boost sediment/nutrients above a critical threshold, beyond that revealed in our baseline survey. Our tracer-based sediment source approach did not corroborate our observations of substantial erosion and land degradation in the upper catchment-but this could be a result of sediment flushing through the dredged channels. We encourage others to combine such methods with sediment budgeting approaches to triangulate results for consistency. Finally, from an ecological perspective, the high presence of seagrass detritus we found in bay sediments suggests seagrass is potentially a key source of nutrients for the meadow itself, as well as other connected ecosystems.

Organic carbon sources across salinity gradients in Chilean Fjords: Reloncaví Fjord ( 41°S) and Southern Patagonian ice fields area ( 48°S)

NASA Astrophysics Data System (ADS)

Placencia, Juan; Llanos, Gustavo; Contreras, Sergio

2017-04-01

The organic matter preserved in marine sediments contains contributions of allochthonous and autochthonous and variable source inputs. Allochthonous sources are terrestrial erosion (including anthropogenic material) of relatively labile and refractory material, while autochthonous sources including marine phytoplankton. In order to establish the sources of the organic matter (allochthonous/autochthonous) and how organic carbon is distributed along a salinity gradient, on this study we examined of organic Carbon/Nitrogen molar ratios (C:N), isotopic composition (δ13C) and n-alkanes (n-C24 to n-C34) in surface sediments from two continuous systems: river-fjord-ocean in Northern Patagonia (41°S-43°S), and glacier-fjord-ocean in central Patagonia (47°S-50°S). The continental inner fjord areas are characterized with sediment enriched in allochthonous organic carbon and high C:N (8-12) and low δ13C values (-23‰ to -26‰). Towards the Pacific Ocean, low C:N (6-7) and high δ13C values (-20‰ to -22‰) suggest prevalent autochthonous marine sources. Estuarine waters with salinity between 2 psu and 30 psu were associated with high C:N and low δ13C values together with odd over even long-chain n-alkane predominance (n-C31, n-C29 and n-C27) in surface sediments. All geochemical proxies suggest a great contribution of terrigenous input by glacier origin rivers, mainly from terrestrial plants in both areas. Our study provides a framework to guide future researches on environmental and climate change on these systems. This study was supported by the Chilean Navy's Hydrographic and Oceanographic Service, the Chilean National Oceanographic Committee through the Grants CONA C19F1308 and C20F1404, and the Research Office at Universidad Católica de la Ssma. Concepción.

Sources of mercury in sediments, water, and fish of the lakes of Whatcom County, Washington

USGS Publications Warehouse

Paulson, Anthony J.

2004-01-01

Concerns about mercury (Hg) contamination in Lake Whatcom, Washington, were raised in the late 1990s after a watershed protection survey reported elevated concentrations of Hg in smallmouth bass. The U.S. Geological Survey, the Whatcom County Health Department, and the Washington State Department of Ecology (Ecology) cooperated to develop a study to review existing data and collect new data that would lead to a better understanding of Hg deposition to Lake Whatcom and other lakes in Whatcom County, Washington. A simple atmospheric deposition model was developed that allowed comparisons of the deposition of Hg to the surfaces of each lake. Estimates of Hg deposition derived from the model indicated that the most significant deposition of Hg would have occurred to the lakes north of the City of Bellingham. These lakes were in the primary wind pattern of two municipal waste incinerators. Of all the lakes examined, basin 1 of Lake Whatcom would have been most affected by the Hg emissions from the chlor-alkali plant and the municipal sewage-sludge incinerator in the City of Bellingham. The length-adjusted concentrations of Hg in largemouth and smallmouth bass were not related to estimated deposition rates of Hg to the lakes from local atmospheric sources. Total Hg concentrations in the surface sediments of Lake Whatcom are affected by the sedimentation of fine-grained particles, whereas organic carbon regulates the concentration of methyl-Hg in the surface sediments of the lake. Hg concentrations in dated sediment core samples indicate that increases in Hg sedimentation were largest during the first half of the 20th century. Increases in Hg sedimentation were smaller after the chlor-alkali plant and the incinerators began operating between 1964 and 1984. Analysis of sediments recently deposited in basin 1 of Lake Whatcom, Lake Terrell, and Lake Samish indicates a decrease in Hg sedimentation. Concentrations of Hg in Seattle precipitation and in tributary waters were used to calculate current (2002-03) loadings of Hg to Lake Whatcom. Hg in tributaries contributed 59 percent of the total Hg, whereas non-local atmospheric deposition was estimated to have contributed 41 percent of the 303 grams of Hg entering Lake Whatcom each year. However, these inputs cannot be verified without a better understanding of the sources of sediment to Lake Whatcom.

[Distribution and sources of polycyclic aromatic hydrocarbons in sediments from rivers of Pearl River Delta and its nearby South China Sea].

PubMed

Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian; Zeng, Yong-Ping; Sheng, Guo-Ying; Fu, Jia-Mo

2005-07-01

Polycyclic aromatic hydrocarbons (PAHs) are measured in surface sediments from rivers and estuary of Pearl River Delta and its nearby South China Sea. Total PAH concentration varied from 255.9 - 16 670.3 ng/g and a moderate to low level compare to relevant areas worldwide. The order of PAHs concentration in sediments was: rivers of Pearl River Delta > estuary > South China Sea, and the most significant PAH contamination was at Guangzhou channel of Zhujiang river. A decrease trend for PAHs concentration with distance from estuary to open sea can be sees in South China Sea. Coal and biomass combustion is the major source of PAHs in nearshore of South China Sea, and petroleum combustion is the main source of pyrolytic PAHs in rivers and estuary of Pearl River Delta according to PAHs diagnostic ratios. Petroleum PAHs are revealed have a high contribution to PAHs in Xijiang River, estuary and some stations in Zhujiang River. A comparison of data from study in 1997 with data from present study indicates that there is no clear change in the PAH concentration over time but the source of PAHs in Pearl River Delta have been change from a main coal combustion to petroleum combustion and being reflect in the sediments in rivers and estuary of Pearl River Delta where there have high sedimentation rate.

Assessment of heavy metal enrichment and its human impact in lacustrine sediments from four lakes in the mid-low reaches of the Yangtze River, China.

PubMed

Bing, Haijian; Wu, Yanhong; Liu, Enfeng; Yang, Xiangdong

2013-07-01

Sediments from four lakes in the mid-low reaches of the Yangtze River, Taibai Lake, Longgan Lake, Chaohu Lake and Xijiu Lake, were chosen to evaluate their enrichment state and history. The state of heavy metal enrichment was at a low level in the sediment of Taibai Lake and Longgan Lake. The enrichment state of Co, Cr and Ni was also low in the sediment of Chaohu Lake and Xijiu Lake, while Cu, Pb and Zn enrichment reached a higher level. Mass accumulation fluxes were calculated to quantitatively evaluate the anthropogenic contribution to heavy metals in the sediment. The anthropogenic accumulation fluxes were lower in the sediment of Taibai Lake and Longgan Lake compared with the other two lakes, where heavy metals, especially Cu, Pb and Zn, were mainly from anthropogenic sources. Heavy metal accumulation did not vary greatly in the sediment of Taibai Lake and Longgan Lake, while that in Chaohu Lake and Xijiu Lake increased since the 1950s and substantially increased since the 1980s, although a decrease occurred since 2000 AD in Xijiu Lake. Heavy metal enrichment was strongly related to human activities in the catchment. The development of urbanization and industrialization was much more rapid in the catchments of Chaohu Lake and Xijiu Lake than of the other two lakes, and thus large amounts of anthropogenically sourced heavy metals were discharged into the lakes, which resulted in a higher contamination risk. However, human activities in the Longgan Lake and Taibai Lake catchments mainly involved agriculture, which contributed a relatively small portion of heavy metals to the lakes.

Shoreline erosion and decadal sediment accumulation in the Tar-Pamlico estuary, North Carolina, USA: A source-to-sink analysis

NASA Astrophysics Data System (ADS)

Eulie, Devon O.; Corbett, D. Reide; Walsh, J. P.

2018-03-01

Estuaries contain vital habitats and it is important to understand how these areas respond to human activities and natural processes such as sea-level rise and wave attack. As estuarine shorelines erode or become modified with hard structures, there is potential for significantly altering the availability of sediment and the filling of coastal systems. This study used a source-to-sink approach and quantified rates of shoreline erosion in the Tar-Pamlico sub-estuary, a tributary of the larger Albemarle-Pamlico Estuarine System (APES). The average shoreline change rate (SCR) determined using an end-point method was -0.5 ± 0.9 m yr-1 for the Tar-Pamlico. Incorporating bulk density estimates, this contributes 0.6 × 105 tons of fine sediment to the system annually, or after accounting for fluvial input, about 40% of the total sediment supply to the sub-estuary. The role of the Tar-Pamlico as a sink for these sediments was addressed using the radionuclide tracers 210Pb and 137Cs. Radionuclide activities and sediment accumulation rates identified several depositional regions, in particular in the middle of the estuary. Linear sediment accumulation rates ranged from 0.10 ± 0.02 to 0.38 ± 0.02 g cm-2 yr-1, and total storage of fine sediment in the system was 1.6 × 105 t yr-1. It was not possible to confidently discern a change in the rate of shoreline erosion or seabed accumulation. A preliminary budget for fine sediments (grain-size <63 μm) was then calculated to compare erosional sources with sedimentary sinks. Almost all (∼93.0%) of the fine sediment entering the system was accumulated and stored, while only about 7.0% was exported to Pamlico Sound.

The role of livestock-poached pasture as a sediment source

NASA Astrophysics Data System (ADS)

Greenwood, Philip; Walling, Desmond; Quine, Timothy

2015-04-01

Historically, the occurrence of sediment-laden runoff has almost exclusively been associated with cultivated hillslopes and particularly with arable land. This association was commonly accompanied by the presumption that, in comparison with cultivated slopes, erosion from intensively-managed lowland pasture was relatively low. Recent developments in sediment source tracing and fingerprinting techniques have, however, challenged these assumptions by demonstrating that soil loss from grasslands may be greater than previously assumed. In attempting to identify potential source areas within grassland environments, attention has frequently focused on areas of livestock poaching where herd animals tend to congregate. However, the role of poached grassland as a sediment-source remains uncertain. Reasons include the difficulties associated with accurately documenting the movement or redistribution of small quantities of fine sediment over relevant spatial and temporal scales. Motivated by an urgent need for such information, this communication presents preliminary results from a tracing study aimed at measuring sediment redistribution within areas of poached pasture over short (i.e. event-based) timescales using the artificial radionuclides, caesium-134 (134Cs) and cobalt-60 (60Co). The approach involved labelling six small areas (0.2 * 0.2 m) of poached soil, each with a contrasting gradient, with either 134Cs or 60Co, and then measuring changes in the radiometric inventory at predetermined points before and after periods of rainfall. Each labelled area of poached pasture was measured on three separate occasions over a 65 day period. At the end of the monitoring phase, the mean net soil redistribution depth (mm) was negative for all plots, with values ranging from -6.8 mm to -15.2 mm. This is interpreted as evidence of the removal, or erosion, of surface material. The findings indicate that areas of livestock-poached pasture can act as significant sediment sources. These findings are discussed with regard to the potential contribution of poaching to the off-site transfer of fine-sediment from affected grasslands, and to the implications for the water quality of receiving streams.

Persistence of deeply sourced iron in the Pacific Ocean

PubMed Central

Horner, Tristan J.; Williams, Helen M.; Hein, James R.; Saito, Mak A.; Burton, Kevin W.; Halliday, Alex N.; Nielsen, Sune G.

2015-01-01

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe−Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface. PMID:25605900

Persistence of deeply sourced iron in the Pacific Ocean.

PubMed

Horner, Tristan J; Williams, Helen M; Hein, James R; Saito, Mak A; Burton, Kevin W; Halliday, Alex N; Nielsen, Sune G

2015-02-03

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe-Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface.

Comparing Bayesian stable isotope mixing models: Which tools are best for sediments?

NASA Astrophysics Data System (ADS)

Morris, David; Macko, Stephen

2016-04-01

Bayesian stable isotope mixing models have received much attention as a means of coping with multiple sources and uncertainty in isotope ecology (e.g. Phillips et al., 2014), enabling the probabilistic determination of the contributions made by each food source to the total diet of the organism in question. We have applied these techniques to marine sediments for the first time. The sediments of the Chukchi Sea and Beaufort Sea offer an opportunity to utilize these models for organic geochemistry, as there are three likely sources of organic carbon; pelagic phytoplankton, sea ice algae and terrestrial material from rivers and coastal erosion, as well as considerable variation in the marine δ13C values. Bayesian mixing models using bulk δ13C and δ15N data from Shelf Basin Interaction samples allow for the probabilistic determination of the contributions made by each of the sources to the organic carbon budget, and can be compared with existing source contribution estimates based upon biomarker models (e.g. Belicka & Harvey, 2009, Faux, Belicka, & Rodger Harvey, 2011). The δ13C of this preserved material varied from -22.1 to -16.7‰ (mean -19.4±1.3‰), while δ15N varied from 4.1 to 7.6‰ (mean 5.7±1.1‰). Using the SIAR model, we found that water column productivity was the source of between 50 and 70% of the organic carbon buried in this portion of the western Arctic with the remainder mainly supplied by sea ice algal productivity (25-35%) and terrestrial inputs (15%). With many mixing models now available, this study will compare SIAR with MixSIAR and the new FRUITS model. Monte Carlo modeling of the mixing polygon will be used to validate the models, and hierarchical models will be utilised to glean more information from the data set.

Patterns and Sources of Sediment and Particulate Organic Carbon in Lake Melville, Labrador, Canada: Inferences from 210Pb, 137Cs, and δ13C

NASA Astrophysics Data System (ADS)

Kamula, C. M.

2016-12-01

Modern sedimentological processes, sources and distribution of sediment and organic carbon (OC) were investigated in recently deposited sediment from Lake Melville, Labrador, Canada to better understand the impacts of anthropogenic and climatic changes to the system over the last 100-150 years. Fifteen sediment cores collected across Lake Melville in 2013 and 2014 were analysed for 210Pb and 137Cs while stable isotope δ13Corg and percentage OC were measured down select cores and surface sediment. Mass accumulation rates (MARs) were established by fitting 210Pbex profiles to a two-layer advection diffusion model and validated with 137Cs. MARs varied between 0.04 and 0.41 g cm-2 yr-1 and decreased with distance from the Churchill River, the greatest source of sediment to the system. MARs were greatest in western Lake Melville immediately east of Goose Bay, reflecting the combined contributions of fine material carried eastward in the Churchill River plume and coarser particles from the Kenamu River. The sources of sediment were investigated by comparing inventories of 137Cs and excess 210Pb (210Pbex) to expected atmospheric inputs, which suggested sediment in Lake Melville is largely sourced from the watershed. In the eastern end of Lake Melville, an elevated 210Pbex inventory was associated with particle scavenging of dissolved 210Pb from inflowing marine water and is likely linked to increased primary production in the area. Surface sediment δ13Corg values (mean = -26.2 ± 1.75‰ SD) support a mixture of both terrestrial and marine organic carbon to the system. Using a transient tracer mixing model, the depth in each core corresponding to 90% sediment deposited pre and post hydroelectric development at Churchill Falls (1970) was established and applied to profiles of δ13Corg. This approach revealed an increase of terrestrial OC to Lake Melville post 1970 which we interpret to reflect change in climate and/or hydrology of the Churchill River.

Effects of pollution on the geochemical properties of marine sediments across the fringing reef of Aqaba, Red Sea.

PubMed

Al-Rousan, Saber; Al-Taani, Ahmed A; Rashdan, Maen

2016-09-15

The Gulf of Aqaba is of significant strategic and economic value to all gulf-bordering states, particularly to Jordan, where it provides Jordan with its only marine outlet. The Gulf is subject to a variety of impacts posing imminent ecological risk to its unique marine ecosystem. We attempted to investigate the status of metal pollution in the coastal sediments of the Jordanian Gulf of Aqaba. The distribution of Cd, Cr, Zn, Cu, Pb, Al, Fe, and Mn concentrations were determined in trapped and bottom-surface sediments at three selected sites at different depths. In addition, monthly sedimentation rates at varying water depths were also estimated at each sampling site using sediment traps. The high concentrations of Cd, Cr, Zn were recorded at the Phosphate Loading Birth (PLB) site followed by the Industrial Complex (IC) site indicating their dominant anthropogenic source (i.e., the contribution of industrial activities). However, Fe, Al, and Mn contents were related to inputs from the terrigenous (crustal) origin. Except for Al, Fe and Mn at the PLB site, the concentrations of metals exhibited a decreasing trend with increasing water depth (distance from the shoreline). The PLB site also showed the highest sedimentation rate which decreased with increasing water depth. The Enrichment factors (EFs) showed that Cd was the most enriched element in the sediment (indicating that Cd pollution is widespread), whereas the least enriched metal in sediments was Cu. EF values suggested that the coastal area is impacted by a combination of human and natural sources of metals, where the anthropogenic sources are intense in the PLB site (north of Gulf of Aqaba). The MSS area is potentially the least polluted, consistent with being a marine reserve. The IC sediments have been found to be impacted by human activities but less intensely compared to the PLB area. These results suggested that there are two sources of metals in sediments; the primary source is likely closer to PLB, while the secondary is nearby the IC. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distribution and sources of organic matter in surface marine sediments across the North American Arctic margin

NASA Astrophysics Data System (ADS)

Goñi, Miguel A.; O'Connor, Alison E.; Kuzyk, Zou Zou; Yunker, Mark B.; Gobeil, Charles; Macdonald, Robie W.

2013-09-01

As part of the International Polar Year research program, we conducted a survey of surface marine sediments from box cores along a section extending from the Bering Sea to Davis Strait via the Canadian Archipelago. We used bulk elemental and isotopic compositions, together with biomarkers and principal components analysis, to elucidate the distribution of marine and terrestrial organic matter in different regions of the North American Arctic margin. Marked regional contrasts were observed in organic carbon loadings, with the highest values (≥1 mg C m-2 sediment) found in sites along Barrow Canyon and the Chukchi and Bering shelves, all of which were characterized by sediments with low oxygen exposure, as inferred from thin layers (<2 cm) of Mn oxihydroxides. We found strong regional differences in inorganic carbon concentrations, with sites from the Canadian Archipelago and Lancaster Sound displaying elevated values (2-7 wt %) and highly depleted 14C compositions consistent with inputs from bedrock carbonates. Organic carbon:nitrogen ratios, stable carbon isotopes, and terrigenous organic biomarkers (lignin phenols and cutin acids) all indicate marked regional differences in the proportions of marine and terrigenous organic matter present in surface sediments. Regions such as Barrow Canyon and the Mackenzie River shelf were characterized by the highest contributions of land-derived organic matter, with compositional characteristics that suggested distinct sources and provenance. In contrast, sediments from the Canadian Archipelago and Davis Strait had the smallest contributions of terrigenous organic matter and the lowest organic carbon loadings indicative of a high degree of post-depositional oxidation.

Contribution of PAHs from coal-tar pavement sealcoat and other sources to 40 U.S. lakes

USGS Publications Warehouse

Van Metre, Peter C.; Mahler, Barbara J.

2010-01-01

Contamination of urban lakes and streams by polycyclic aromatic hydrocarbons (PAHs) has increased in the United States during the past 40 years. We evaluated sources of PAHs in post-1990 sediments in cores from 40 lakes in urban areas across the United States using a contaminant mass-balance receptor model and including as a potential source coal-tar-based (CT) sealcoat, a recently recognized source of urban PAH. Other PAH sources considered included several coal- and vehicle-related sources, wood combustion, and fuel-oil combustion. The four best modeling scenarios all indicate CT sealcoat is the largest PAH source when averaged across all 40 lakes, contributing about one-half of PAH in sediment, followed by vehicle-related sources and coal combustion. PAH concentrations in the lakes were highly correlated with PAH loading from CT sealcoat (Spearman's rho=0.98), and the mean proportional PAH profile for the 40 lakes was highly correlated with the PAH profile for dust from CT-sealed pavement (r=0.95). PAH concentrations and mass and fractional loading from CT sealcoat were significantly greater in the central and eastern United States than in the western United States, reflecting regional differences in use of different sealcoat product types. The model was used to calculate temporal trends in PAH source contributions during the last 40 to 100 years to eight of the 40 lakes. In seven of the lakes, CT sealcoat has been the largest source of PAHs since the 1960s, and in six of those lakes PAH trends are upward. Traffic is the largest source to the eighth lake, located in southern California where use of CT sealcoat is rare.

Patterns and contributions of floodplain and legacy sediments remobilized from Piedmont streams of the mid-Atlantic U.S.

NASA Astrophysics Data System (ADS)

Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen

2015-04-01

The perceived role of streambank erosion as a contributor to watershed sediment yield is an important driver of policy decisions for managing downstream impacts in the United States. In the Piedmont physiographic province of the eastern U.S. and in other regions of the south and midwest, the issue of 'legacy' sediment stored in stream valleys has long been recognized as a consequence of rapid deforestation and erosive agricultural practices following European settlement. Remobilization of stored floodplain sediment by bank erosion is frequently cited as a dominant component of watershed sediment budgets, with legacy sediment comprising the largest portion of this source. However there are few published studies documenting spatially extensive measurements of channel change throughout the drainage network on time scales of more than a few years. In this study we document 1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, 2) proportions of streambank sediment derived from legacy deposits, and 3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont. We measured gross erosion and channel deposition rates over 45 years within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 by comparing stream channel and floodplain morphology from LiDAR-based digital elevation data collected in 2005 with channel positions recorded on 1:2400-scale topographic maps from 1959-1961. Results were extrapolated to estimate contributions to watershed sediment yield from 1005 km2 of northern Baltimore County. Results indicate that legacy sediment is a dominant component (62%) of the sediment derived from bank erosion and that its relative importance is greater in larger valleys with broader valley floors and lower gradients. Although mass of sediment remobilized per unit channel length is greater in these downstream valleys, a majority of remobilized sediment (62%) is coming from first- and second-order tributaries because they represent the largest fraction of cumulative channel length in the drainage network. Floodplain segments are discontinuous along low-order tributaries but sediment contributions reported here are adjusted to account for the percent valley length bordered by floodplain sediments. Average annual lateral migration rates ranged from 0.04-0.19 m/y with higher rates along larger streams; however, when scaled by channel width, we find that on average streams are migrating 2.5% of channel width across all drainage areas. Direct measurements reported here account for in-channel deposition, but not floodplain deposition. Other studies in the region have demonstrated that redeposition on floodplains is an important component of the sediment budget and are necessary to avoid overestimating streambank erosion contributions to watershed sediment yield. We therefore adjust our measured sediment contributions by estimating the mass of sediment redeposited on floodplains within our study area. With this adjustment, extrapolated net stream bank sediment yields (72 Mg/km2/yr) are equivalent to 70% of the estimated average Piedmont watershed yield (104 Mg/km2/yr) cited by previous authors. Furthermore, our results demonstrate that measurements over adequate spatial and temporal scales- rather than short-term, localized observations- are required to accurately capture and measure patterns of streambank erosion across the drainage network. It is important to note that upland erosion rates- not measured here- have been reported with equivalent and greater magnitude for forested and cropland areas within the Maryland Piedmont and therefore should not be assumed to contribute only 30% of the total.

Suspended Sediment Loads and Tributary Inputs in the Mississippi River below St. Louis, MO, 1990-2013 Compared With Earlier Results

NASA Astrophysics Data System (ADS)

Allison, M. A.; Biedenharn, D. S.; Dahl, T. A.; Kleiss, B.; Little, C. D.

2017-12-01

Annual suspended sediment loads and water discharges were calculated in the Mississippi River mainstem channel, and at the most downstream gaging station for major tributaries, from below the Missouri confluence near St. Louis, MO to Belle Chasse, LA, as well as down the Atchafalaya distributary for water years 1990 to 2013. The purpose of the present study was to assess changes in the Mississippi River sediment budget over the past half century, and to examine the continuing role that anthropogenic (e.g., dams, river control works, soil conservation practices) and natural (e.g., rainfall and denudation rates) factors have in controlling these changes. Sixteen of the 17 measured Mississippi River tributaries decreased in total suspended sediment load) from 1970-1978 to 1990-2013. The largest decreases occurred in the 2nd (Ohio River, 41% of 1970-1978) and 4th (Arkansas River, 45% of 1970-1978) largest water sources to the Mississippi. The Missouri River remains the largest Mississippi River tributary in terms of average annual suspended sediment flux; its relative contribution increased from 38% to 51% of the total flux from the 17 measured tributaries, even as its total suspended flux declined by 13%. Averaged over the period of study (WY 1990-2013), water flux increased by 468% and sediment flux increased by 37,418% downstream from the Gavin's Point Dam to the confluence with the Mississippi. Possible reasons for this disproportional increase in suspended sediment load downstream include sediment-rich contributions from 2nd order rivers below the dams and channel incision. Suggested station improvements to the system include improved monitoring of the Upper Mississippi and Arkansas River tributaries, establishing additional mainstem stations in the reach between Thebes, IL and Arkansas City, AR, and standardization of laboratory and field methodologies to eliminate a major source of station-to-station and time-series variability in the sediment budgeting.

Apportionment of polycyclic aromatic hydrocarbon sources in lower Fox River, USA, sediments by a chemical mass balance model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, M.C.; Christensen, E.R.; Karls, J.F.

Four sediment cores were collected from the lower Fox River, Wisconsin, USA, to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) using a chemical mass balance model. The cores, which were obtained in 1995 from areas close to Green Bay, Wisconsin, USA, had total PAH concentrations between 19.3 and 0.34 ppm. To determine historical trends of PAH inputs, {sup 210}Pb and {sup 137}Cs dating was used, and elemental carbon particle analysis was done to characterize particles from the combustion of coal, wood, and petroleum. Source fingerprints were taken from the literature. Their results indicate that coke oven emissions, highway dust,more » coal gasification, and wood burning are likely sources of PAHs in the lower Fox River. Coke oven emissions are in the range of 40 to 90% of total PAHs, and this fraction decreases from 1930 to 1990, except in core Fox River-A (FR-A). The overall highway dust (HWY) contribution is between 10 and 75%, and this fraction increases from 1930 to present, except in core FR-A. The wood burning (WB) contribution is less than 7% in cores FR-B, FR-C, and FR-D. In core FR-A, a maximum ({approximately}23%) is found around 1960. The contribution of wood burning has changed from less than 6% in 1950 to between 3 and 10% in 1995. Evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene, with a half-life of approximately 0.5 years has been found at the site of core FR-D, which is the shallowest (1.1 m) of the four core sites.« less

A non-deltaic clinoform wedge fed by multiple sources off São Sebastião Island, southeastern Brazilian Shelf

NASA Astrophysics Data System (ADS)

Vieira, Ivo; Lobo, Francisco José; Montoya-Montes, Isabel; Siegle, Eduardo; Passos, Jorge Luiz; De Mahiques, Michel Michaelovitch

2018-02-01

São Sebastião Island (SSI) marks the latitudinal boundary between two sedimentological and geochemical provinces in the São Paulo Bight, an arc-shaped sector of the southeastern Brazilian Shelf. The island is separated from the continent by the narrow, deep São Sebastião Channel (SSC). A relatively thick sediment wedge—the São Sebastião Wedge (SSW)—has been formed offshore SSI. This study explores the possible genetic and evolutionary mechanisms of the wedge, bearing in mind that clinoform wedges can form at considerable distances from major fluvial sources. For that, a marine geological database has been interpreted comprising high-resolution seismic data, a surficial sediment map and several sediment cores, from which radiocarbon dates were obtained and sedimentation rates deduced. A wave model was also applied to obtain the dominant wave directions. The SSW is a wedge-shaped deposit, and its internal structure presents three seismic units. The two lowest are wedge shaped and arranged in a backstepping pattern. The most recent unit is mostly aggradational and can be divided into three seismic subunits. Sedimentological data show that at least the most recent unit is composed of a mixture of sands and silts. Modeled wave conditions indicate a major influence from southerly waves that are able to remobilize shelf sediments and to create a bypass sediment zone until the foreset of the deposit is reached at the water depths where the SSW is found. Taken together, these data suggest that the SSW formed through contributions from different sediment sources, and should be regarded as an intermediate case of a non-deltaic clinoform wedge. Sand transport in the area involves wind-driven currents passing through the SSC and sediment remobilization by energetic southerly waves. Fine-grained sediment is derived mostly from the joint contributions of many minor catchments located north of the island, and this sediment is later transported southwestward by the prevailing surface currents. The morphological obstacle presented by the island leads to current veering and subsequent sediment deposition. The internal architecture of the wedge indicates that its deposition was probably initiated during the last part of the postglacial transgression, but its present-day morphology is mostly a product of episodic highstand sedimentation that began under conditions of gently falling sea levels during the last 5 ka, after the Holocene glacio-eustatic maximum.

Tracing subducted sediment inputs to the Ryukyu arc-Okinawa Trough system: Evidence from thallium isotopes

NASA Astrophysics Data System (ADS)

Shu, Yunchao; Nielsen, Sune G.; Zeng, Zhigang; Shinjo, Ryuichi; Blusztajn, Jerzy; Wang, Xiaoyuan; Chen, Shuai

2017-11-01

Sediments are actively subducted in virtually every arc worldwide. However, quantifying their contributions to arc lavas and thereby establishing budgets of how sediments participate in slab-mantle interaction is challenging. In this contribution we use thallium (Tl) abundances and isotopic compositions of lavas from the Ryukyu arc (including south Kyushu) and its back-arc basin, Okinawa Trough, to investigate the influence of sediments from arc to back-arc. We also present extensive geochemical data for sediments and altered oceanic crust (AOC) outboard of the northern (DSDP Sites 296, 442B, 443 and 444) and central (DSDP Sites 294 and 295) part of the Ryukyu arc. The Tl isotopic compositions of sediments change systematically from lighter outboard of northern Ryukyu arc to heavier outboard of central Ryukyu arc. The feature reflects the dominance of terrigenous material and pelagic sedimentation outboard of the northern and central Ryukyu arc, respectively. Central and northern sections of Ryukyu arc and Okinawa Trough display larger range of Tl isotopic variation than southern section, which is consistent with more pelagic provenance for sediments outboard of central and northern Ryukyu arcs than that of expected sediments outboard of southern Ryukyu arc. Identical Tl, Sr, Nd and Pb isotope variations are found when comparing arc and back arc lavas, which indicates that sediments fluxes also account for the Tl isotopic variations in the Okinawa Trough lavas. Two-end-member mixing models of Tl with Pb, Sr and Nd isotopes require sediment inputs of< 1%, 0.1-1% and 0.3-2% by weight to the depleted mantle source to account for all these isotopic compositions of lavas from northern, central and southern portion of the Ryukyu arc and Okinawa Trough. Bulk mixing between mantle and sediment end members predict very similar sediment fluxes when using Tl, Sr, Nd and Pb isotopes, which indicates that fractionation of these elements must have happened after mixing between mantle and sediments. This conclusion is corroborated by model calculations of mixing between sediment melts with fractionated Sr/Nd ratios and mantle wedge, which show that no arc lava plot on such mixing lines. Thus bulk sediment mixing, rather than sediment melt, is required for the generation of the lavas from the Ryukyu arc and Okinawa Trough. The requirement of bulk sediment mixing occurring before trace element fractionation in the sub-arc mantle is consistent with models where mélange layers form at the top of the slab and are the principle source material for arc lavas. In addition, the fact that sediment components observed in the Ryukyu arc and Okinawa Trough lavas are similar, suggests that transport of mélange material to the source regions of the arc and back arc is equally efficient. This feature is most readily explained if mélange material is transported from the slab as diapirs.

GOM Deepwater Horizon Oil Spill: A Time Series Analysis of Variations in Spilled Hydrocarbons

NASA Astrophysics Data System (ADS)

Palomo, C. M.; Yan, B.

2013-12-01

An estimated amount of 210 million gallons of crude oil was released into the Gulf of Mexico (GOM) from April 20th to July 15th 2010 during the Deepwater Horizon oil rig explosion. The spill caused a tremendous financial, ecological, environmental and health impact and continues to affect the GOM today. Variations in hydrocarbons including alkanes, hopanes and poly-cyclic aromatic hydrocarbons (PAHs) can be analyzed to better understand the oil spill and assist in oil source identification. Twenty-one sediment samples*, two tar ball samples and one surface water oil sample were obtained from distinct locations in the GOM and within varying time frames from May to December 2010. Each sample was extracted through the ASE 200 solvent extractor, concentrated down under nitrogen gas, purified through an alumina column, concentrated down again with nitrogen gas and analyzed via GC X GC-TOF MS. Forty-one different hydrocarbons were quantified in each sample. Various hydrocarbon 'fingerprints,' such as parental :alkylate PAH ratios, high molecular weight PAHs: low molecular weight alkane ratios, and carbon preference index were calculated. The initial objective of this project was to identify the relative hydrocarbon contributions of petrogenic sources and combustion sources. Based on the calculated ratios, it is evident that the sediment core taken in October of 2010 was greatly affected by combustion sources. Following the first month of the spill, oil in the gulf was burned in attempts to contain the spill. Combustion related sources have quicker sedimentation rates, and hydrocarbons from a combustion source essentially move into deeper depths quicker than those from a petrogenic source, as was observed in analyses of the October 2010 sediment. *Of the twenty-one sediment samples prepared, nine were quantified for this project.

Heavy Minerals in Palaeotsunami Deposits: Assemblages, Spatial Distribution and Microtextural Imprints

NASA Astrophysics Data System (ADS)

Costa, P. J.; Andrade, C.; Cascalho, J.; Dawson, A. G.; Freitas, M. C.; Dawson, S.; Mahaney, W. C.

2013-12-01

The sedimentological record provides a database useful to characterize and evaluate recurrence of tsunamis, which contributes to assessing the vulnerability of any coastal area to this natural hazard. Thus, the enhancement of our ability to recognize signatures specific of tsunami activity imprinted in coastal sediments is of unquestionable interest. The aim of this study is to discuss and further contribute to the improvement of the characterization of (palaeo)tsunami deposits, and of their source materials. With that purpose the vertical and horizontal distribution of heavy mineral (HM) assemblages in sand-sized tsunamigenic deposits from six locations exhibiting a varied suite of coastal contexts and corresponding to three inundation events -(8200yrs BP - Scotland, 1500yrs BP - Scotland, AD 1755 - Portugal) were studied. In general, results from paleotsunami sediments show that site-specific effects prevent 'blind' extrapolations; instead, the bulk of the HM assemblages reflect local specificities related with the regional geology. In the Portuguese sediments (Martinhal, Boca do Rio and Salgados) ca. 90% of the non-opaque HM population consists of tourmaline, andalusite and staurolite, whereas amphiboles are dominant (> 90% of the assemblage) in the Scottish sediments (Scasta Voe, Basta Voe and Whale Firth). Principal Components Analyses revealed that the first 2 components explain more than 2/3 of the total variance found in each site. Horizontal and vertical variations in the HM were observed and especially in the heavier mineral species. Although, in some of the studied cases, the deposit was macroscopically massive, data on HM allowed the distinction of backwash layer(s), related with incorporation of inland materials. In what concerns sources, results indicate that palaeotsunami sediments share fewer compositional similarities with present-day inshore and offshore materials and more resemblances with dune and beach sediment, thus indicating these as the more likely source areas. In addition, preliminary results of SEM analysis of microtextural features imprinted in the surface of heavy minerals indicate an increase in the number of mechanical marks in the surface of palaeotsunami grains when compared with potential source materials (beach, dune, inshore and offshore samples). This work further reveals the potential to use heavy minerals as a complementary sedimentological tool in the study of palaeotsunami deposits.

Origin of particulate organic matter exported during storm events in a forested headwater catchment.

NASA Astrophysics Data System (ADS)

Jeanneau, Laurent; Rowland, Richard D.; Inamdar, Shreeram P.

2016-04-01

Particulate organic matter (POM) plays an important biogeochemical role towards ecology, ecotoxicology and carbon cycle. Moreover POM within the fluvial suspended sediment load during infrequent high flows can comprise a larger portion of long-term flux than dissolved species. It is well documented that storm events that constituted only 10-20% of the year contributed to >80% of POC exports. But the origin and composition of POM transferred during those hot moments remained unclear. In order to improve our knowledge on this topic we explore the variability in storm event-transported sediments' POM content and source down a continuum of catchment drainage locations. Wetland, upland and forest O horizons, litter, river banks and bed sediments were analyzed for their content in organic C, isotopic (13C) and molecular (thermochemiolysis-gas chromatography-mass spectrometry) fingerprints. The isotopic and molecular fingerprints recorded in suspended and deposited (differentiated into fine, medium and coarse particles) sediments sampled during different storm events down a continuum of catchment drainage locations (12 and 79 ha). This study highlights compositional differences between the catchment size (12 versus 79 ha), the particle size of deposited sediment (fine versus medium versus coarse) and the sampling time during a storm event (rising limb versus peak flow versus falling limb). Two sampling strategies were used. Suspended sediments sampled at a specific time during flood events allow evaluating changes along the hydrograph, while deposited sediments that integrate the entire event allow making comparisons with drainage scale. For deposited sediments, the proportion of OM coming from the endmembers wetland, litter and Forest O horizon decreases from the 12ha to the 79ha catchment, which exhibited a higher proportion of OM coming from stream bed sediment and river banks. For both catchments, from fine to coarse particles, the influence of stream bed sediments and river banks decreases while the influence of Forest O horizon increases. For suspended sediments, the evolution during storm events were opposite in the 12ha and the 79ha catchments. In the 12ha catchment, during the rising limb of the hydrograph, POM seems to be inherited from stream bed sediments and river banks, while from the rising limb to the peak flow, the influence of litter and/or wetland increases. This influence decreases during the falling limb. The opposite trend was observed in the 79ha catchment, with an increasing contribution of stream bed sediments to the OM exported during a storm event. What is the information to take away? First POM transferred in headwater catchments has multiple sources. Secondly, the combination of those sources is different along the size continuum of particles. Then, down a continuum of catchment drainage locations, the combination of sources changes both along the size continuum and during storm events. This information is critical for identifying the various drivers and mechanisms behind POM transport and for understanding the impacts of POM on aquatic metabolism and downstream water quality.

A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system

USGS Publications Warehouse

Rosenbauer, Robert J.; Foxgrover, Amy C.; Hein, James R.; Swarzenski, Peter W.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

A diverse suite of geochemical tracers, including 87Sr/86Sr and 143Nd/144Nd isotope ratios, the rare earth elements (REEs), and select trace elements were used to determine sand-sized sediment provenance and transport pathways within the San Francisco Bay coastal system. This study complements a large interdisciplinary effort (Barnard et al., 2012) that seeks to better understand recent geomorphic change in a highly urbanized and dynamic estuarine-coastal setting. Sand-sized sediment provenance in this geologically complex system is important to estuarine resource managers and was assessed by examining the geographic distribution of this suite of geochemical tracers from the primary sources (fluvial and rock) throughout the bay, adjacent coast, and beaches. Due to their intrinsic geochemical nature, 143Nd/144Nd isotopic ratios provide the most resolved picture of where sediment in this system is likely sourced and how it moves through this estuarine system into the Pacific Ocean. For example, Nd isotopes confirm that the predominant source of sand-sized sediment to Suisun Bay, San Pablo Bay, and Central Bay is the Sierra Nevada Batholith via the Sacramento River, with lesser contributions from the Napa and San Joaquin Rivers. Isotopic ratios also reveal hot-spots of local sediment accumulation, such as the basalt and chert deposits around the Golden Gate Bridge and the high magnetite deposits of Ocean Beach. Sand-sized sediment that exits San Francisco Bay accumulates on the ebb-tidal delta and is in part conveyed southward by long-shore currents. Broadly, the geochemical tracers reveal a complex story of multiple sediment sources, dynamic intra-bay sediment mixing and reworking, and eventual dilution and transport by energetic marine processes. Combined geochemical results provide information on sediment movement into and through San Francisco Bay and further our understanding of how sustained anthropogenic activities which limit sediment inputs to the system (e.g., dike and dam construction) as well as those which directly remove sediments from within the Bay, such as aggregate mining and dredging, can have long-lasting effects

Dioxin-like biological activity of organic extracts from sediments and fish livers sampled along the Israeli Mediterranean and Red Sea coasts.

PubMed

Yudkovski, Yana; Herut, Barak; Shefer, Edna; Tom, Moshe

2015-09-15

This study provides, for the first time, a baseline evaluation of dioxin-like biological activity in sediments and fish sampled in- and adjacent to anchorages along the Mediterranean and Red Sea coasts of Israel. It indicates the effect of past pollution, still present in the sediments of older Israeli harbors, with putative contribution of still existing sources of pollution. A commercial reporter gene bioassay was used to evaluate the biological activity of dioxin-like compounds extracted from the samples. HRGC/HRMS analysis of several samples contributed a profile of dioxin-like compounds in sediments and fish. The results point out 1,2,3,4,6,7,8-HeptaCDD, 2,3,4,6,7,8-HexaCDF, 1,2,3,4,6,7,8-HeptaCDF, РСВ-126 and РСВ-118 as major contributors to the dioxin-like activity in sediments. It indicates polychlorinated biphenyls non-selective absorption in fish livers, in contrary to a biased accumulation of poorly chlorinated and more potent dibenzodioxins and dibenzofurans. Copyright © 2015 Elsevier Ltd. All rights reserved.

Erosion, storage, and transport of sediment in two subbasins of the Rio Puerco, New Mexico

USGS Publications Warehouse

Gellis, A.C.; Pavich, M.J.; Ellwein, A.L.; Aby, S.; Clark, I.; Wieczorek, M.E.; Viger, R.

2012-01-01

Arroyos in the American Southwest proceed through cut-and-fill cycles that operate at centennial to millennial time scales. The geomorphic community has put much effort into understanding the causes of arroyo cutting in the late Quaternary and in the modern record (late 1800s), while little effort has gone into understanding how arroyos fill and the sources of this fill. Here, we successfully develop a geographic information system (GIS)-modeled sediment budget that is based on detailed field measurements of hillslope and channel erosion and deposition. Field measurements were made in two arroyo basins draining different lithologies and undergoing different land disturbance (Volcano Hill Wash, 9.30 km2; Arroyo Chavez, 2.11 km2) over a 3 yr period. Both basins have incised channels that formed in response to the late nineteenth-century incision of the Rio Puerco. Large volumes of sediment were generated during arroyo incision, equal to more than 100 yr of the current annual total sediment load (bed load + suspended load) in each basin. Downstream reaches in both arroyos are presently aggrading, and the main source of the sediment is from channel erosion in upstream reaches and first- and second-order tributaries. The sediment budget shows that channel erosion is the largest source of sediment in the current stage of the arroyo cycle: 98% and 80% of the sediment exported out of Volcano Hill Wash and Arroyo Chavez, respectively. The geomorphic surface most affected by arroyo incision and one of the most important sediment sources is the valley alluvium, where channel erosion, gullying, soil piping, and grazing all occur. Erosion rates calculated for the entire Volcano Hill Wash (-0.26 mm/yr) and Arroyo Chavez (-0.53 mm/yr) basins are higher than the modeled upland erosion rates in each basin, reflecting the large contributions from channel erosion. Erosion rates in each basin are affected by a combination of land disturbance (grazing) and lithology--erodible sandstones and shales in Arroyo Chavez compared with basalt for Volcano Hill Wash. Despite these differences, hillslope sediment yields are similar to long-term denudation rates. As the arroyo fills over time from mouth to headwaters, hillslope sediment becomes a more significant sediment source.

Mercury contaminated sediment sites-an evaluation of remedial options.

PubMed

Randall, Paul M; Chattopadhyay, Sandip

2013-08-01

Mercury (Hg) is a naturally-occurring element that is ubiquitous in the aquatic environment. Though efforts have been made in recent years to decrease Hg emissions, historically-emitted Hg can be retained in the sediments of aquatic bodies where they may be slowly converted to methylmercury (MeHg). Consequently, Hg in historically-contaminated sediments can result in high levels of significant exposure for aquatic species, wildlife and human populations consuming fish. Even if source control of contaminated wastewater is achievable, it may take a very long time, perhaps decades, for Hg-contaminated aquatic systems to reach relatively safe Hg levels in both water and surface sediment naturally. It may take even longer if Hg is present at higher concentration levels in deep sediment. Hg contaminated sediment results from previous releases or ongoing contributions from sources that are difficult to identify. Due to human activities or physical, chemical, or biological processes (e.g. hydrodynamic flows, bioturbation, molecular diffusion, and chemical transformation), the buried Hg can be remobilized into the overlying water. Hg speciation in the water column and sediments critically affect the reactivity (i.e. conversion of inorganic Hg(II) to MeHg), transport, and its exposure to living organisms. Also, geochemical conditions affect the activity of methylating bacteria and its availability for methylation. This review paper discusses remedial considerations (e.g. key chemical factors in fate and transport of Hg, source characterization and control, environmental management procedures, remediation options, modeling tools) and includes practical case studies for cleaning up Hg-contaminated sediment sites. Published by Elsevier Inc.

Historic brownfields and industrial activity in Kingston, Ontario: assessing potential contributions to mercury contamination in sediment of the Cataraqui River.

PubMed

Manion, N C; Campbell, L; Rutter, A

2010-04-01

The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activities for over a century. More than 40 industries have existed within the inner harbour, and while many of these industries are no longer present, the properties that they operated on remain as potential sources of persistent contamination to the present day, including mercury. To assess the extent and distribution of total mercury (THg) contamination, 21 sediment cores as well as pore water samples were collected within the inner harbour of Kingston. The spatial distribution of THg in the surface sediment is not homogenous; with concentrations in the surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater (p<0.01) than the rest of the inner harbour, and were above the Federal severe effect limit (>2000 microg/kg;) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in the surface sediment (0-5 cm). THg was not found in storm sewer discharges, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 microg/kg. Significant [THg] was detected in runoff draining from contaminated shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to the sediment. It can be concluded that there is an increased risk over time to surrounding ecosystems where properties with historical contamination are not remediated until they are developed. (c) 2010 Elsevier B.V. All rights reserved.

Water-quality trends for selected sampling sites in the upper Clark Fork Basin, Montana, water years 1996-2010

USGS Publications Warehouse

Sando, Steven K.; Vecchia, Aldo V.; Lorenz, David L.; Barnhart, Elliott P.

2014-01-01

A large-scale trend analysis was done on specific conductance, selected trace elements (arsenic, cadmium, copper, iron, lead, manganese, and zinc), and suspended-sediment data for 22 sites in the upper Clark Fork Basin for water years 1996–2010. Trend analysis was conducted by using two parametric methods: a time-series model (TSM) and multiple linear regression on time, streamflow, and season (MLR). Trend results for 1996–2010 indicate moderate to large decreases in flow-adjusted concentrations (FACs) and loads of copper (and other metallic elements) and suspended sediment in Silver Bow Creek upstream from Warm Springs. Deposition of metallic elements and suspended sediment within Warm Springs Ponds substantially reduces the downstream transport of those constituents. However, mobilization of copper and suspended sediment from floodplain tailings and stream banks in the Clark Fork reach from Galen to Deer Lodge is a large source of metallic elements and suspended sediment, which also affects downstream transport of those constituents. Copper and suspended-sediment loads mobilized from within this reach accounted for about 40 and 20 percent, respectively, of the loads for Clark Fork at Turah Bridge (site 20); whereas, streamflow contributed from within this reach only accounted for about 8 percent of the streamflow at Turah Bridge. Minor changes in FACs and loads of copper and suspended sediment are indicated for this reach during 1996–2010. Clark Fork reaches downstream from Deer Lodge are relatively smaller sources of metallic elements than the reach from Galen to Deer Lodge. In general, small decreases in loads and FACs of copper and suspended sediment are indicated for Clark Fork sites downstream from Deer Lodge during 1996–2010. Thus, although large decreases in FACs and loads of copper and suspended sediment are indicated for Silver Bow Creek upstream from Warm Springs, those large decreases are not translated to the more downstream reaches largely because of temporal stationarity in constituent transport relations in the Clark Fork reach from Galen to Deer Lodge. Unlike metallic elements, arsenic (a metalloid element) in streams in the upper Clark Fork Basin typically is mostly in dissolved phase, has less variability in concentrations, and has weaker direct relations with suspended-sediment concentrations and streamflow. Arsenic trend results for 1996–2010 indicate generally moderate decreases in FACs and loads in Silver Bow Creek upstream from Opportunity. In general, small temporal changes in loads and FACs of arsenic are indicated for Silver Bow Creek and Clark Fork reaches downstream from Opportunity during 1996–2010. Contribution of arsenic (from Warm Springs Ponds, the Mill-Willow bypass, and groundwater sources) in the Silver Bow Creek reach from Opportunity to Warm Springs is a relatively large source of arsenic. Arsenic loads originating from within this reach accounted for about 11 percent of the load for Clark Fork at Turah Bridge; whereas, streamflow contributed from within this reach only accounted for about 2 percent of the streamflow at Turah Bridge.

Integrating isotopic tracer techniques with Bayesian modelling for improved assessment and management of sedimentation problems in the Gilgel-Gibe catchment, Ethiopia

NASA Astrophysics Data System (ADS)

Dume, Bayu; Amsalu, Nebiyu; Bode, Samuel; Mtei, Kelvin; Munishi, Linus; Navas, Ana; Semmens, Brice; Smith, Hugh; Stock, Brian; Blake, Will; Boeckx, Pascal

2017-04-01

Soil erosion and associated downstream siltation of dams and lakes is becoming serious threat to catchment ecosystem services supporting water, food and energy security in Ethiopia. Sediments originate on catchment hillslopes but mobilisation processes vary depending on land use and terrain. The Gilgel Gibe hydroelectric dam is one of a series of development projects launched by the Federal Government of Ethiopia. The catchment is characterised by erodible, deforested agricultural land which is also overgrazed. Siltation and nutrient enrichment are significant issues given 'hotspot' sheet erosion estimates of 2210 ton per square km. The annual contribution of sediment from the Gilgel Gibe River to the dam was estimated at 277 thousand tons per year leading to accumulations of 3.75 x 107 cubic metres per year of silt behind the dam. The primary driver for mobilisation and translocation to downstream is believed to be erosion on agricultural lands and collapse of steep banks, through landsliding into river channels in the highland headwaters. The relative importance of specific sources of siltation are unknown and sediment source apportionment has been identified as a first essential step before soil conservation measures can be implemented. Knowledge of sediment source and transfer dynamics is critical to inform management policy decisions to maintain and enhance future food, water and energy security To test the applicability of a new combination of Bayesian unmixing modelling with sediment fingerprinting in this terrain (IMIXSED approach) a demonstration sub-catchment was selected through field assessment in the upper Gilgel-Gibe water-supply catchments (Unta River) and sampling strategies designed. Accordingly, sources, i.e. soil samples from landslides (n=40), eroding channel bank (n = 5), cultivated land (n = 30), grasslands (n = 30), wooded areas (n = 10), homestead plots (n = 10) were collected alongside 10 spatially-integrated sediment deposits from the receptor cobble bed river after the 2016 rainy season. In order to extract reliable information on the sources of fine sediment delivered into rivers and dam, new isotopic techniques (e.g., Compound Specific Stable Isotopes (CSSIs)) combined with other isotopic techniques (fallout radionuclides) and geochemical tracer properties (via WD-XRF) were employed to quantify sediment sources. Results from this demonstration catchment are discussed in the context of the wider sediment pressures on the Hydro-Electric Power infrastructure of the Gilgel Gibe system.

Numerical simulations of sand production in interbedded hydrate-bearing sediments during depressurization

USGS Publications Warehouse

Uchida, Shun; Lin, Jeen-Shang; Myshakin, Evgeniy; Seol, Yongkoo; Collett, Timothy S.; Boswell, Ray

2017-01-01

Geomechanical behavior of hydrate-bearing sediments during gas production is complex, involving changes in hydrate-dependent mechanical properties. When interbedded clay layers are present, the complexity is more pronounced because hydrate dissociation tends to occur preferentially in the sediments adjacent to the clay layers due to clay layers acting as a heat source. This would potentially lead to shearing deformation along the sand/clay contacts and may contribute to solid migration, which hindered past field-scale gas production tests. This paper presents a near-wellbore simulation of sand/clay interbedded hydrate-bearing sediments that have been subjected to depressurization and discusses the effect of clay layers on sand production.

Time series of suspended-solids concentration, salinity, temperature, and total mercury concentration in San Francisco Bay during water year 1998

USGS Publications Warehouse

Ruhl, Catherine A.; Schoellhamer, David H.

2001-01-01

The transport and fate of suspended sediments are important factors in determining the transport and fate of constituents adsorbed on the sediments. For example, the concentration of suspended particulate chromium in the bay appears to be controlled primarily by sediment resuspension (Abu-Saba and Flegal, 1995). Concentrations of dissolved trace elements are greater in South Bay than elsewhere in San Francisco Bay, and bottom sediments are believed to be a significant source (Flegal et al., 1991). The sediments on the bay bottom provide habitat for benthic communities that can ingest these substances and introduce them into the food web (Luoma et al., 1985; Brown and Luoma, 1995, Luoma 1996). Bottom sediments also are a reservoir of nutrients that contribute to the maintenance of estuarine productivity (Hammond et al., 1985).

Interplay between spatially explicit sediment sourcing, hierarchical river-network structure, and in-channel bed material sediment transport and storage dynamics

NASA Astrophysics Data System (ADS)

Czuba, Jonathan A.; Foufoula-Georgiou, Efi; Gran, Karen B.; Belmont, Patrick; Wilcock, Peter R.

2017-05-01

Understanding how sediment moves along source to sink pathways through watersheds—from hillslopes to channels and in and out of floodplains—is a fundamental problem in geomorphology. We contribute to advancing this understanding by modeling the transport and in-channel storage dynamics of bed material sediment on a river network over a 600 year time period. Specifically, we present spatiotemporal changes in bed sediment thickness along an entire river network to elucidate how river networks organize and process sediment supply. We apply our model to sand transport in the agricultural Greater Blue Earth River Basin in Minnesota. By casting the arrival of sediment to links of the network as a Poisson process, we derive analytically (under supply-limited conditions) the time-averaged probability distribution function of bed sediment thickness for each link of the river network for any spatial distribution of inputs. Under transport-limited conditions, the analytical assumptions of the Poisson arrival process are violated (due to in-channel storage dynamics) where we find large fluctuations and periodicity in the time series of bed sediment thickness. The time series of bed sediment thickness is the result of dynamics on a network in propagating, altering, and amalgamating sediment inputs in sometimes unexpected ways. One key insight gleaned from the model is that there can be a small fraction of reaches with relatively low-transport capacity within a nonequilibrium river network acting as "bottlenecks" that control sediment to downstream reaches, whereby fluctuations in bed elevation can dissociate from signals in sediment supply.

Particle size and chemical control of heavy metals in bed sediment from the Rouge River, southeast Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, K.S.; Cauvet, D.; Lybeer, M.

1999-04-01

Anthropogenic activities related to 100 years of industrialization in the metropolitan Detroit area have significantly enriched the bed sediment of the lower reaches of the Rouge River in Cr, Cu, Fe, Ni, Pb, and Zn. These enriched elements, which may represent a threat to biota, are predominantly present in sequentially extracted reducible and oxidizable chemical phases with small contributions from residual phases. In size-fractionated samples trace metal concentrations generally increase with decreasing particle size, with the greatest contribution to this increase from the oxidizable phase. Experimental results obtained on replicate samples of river sediment demonstrate that the accuracy of themore » sequential extraction procedure, evaluated by comparing the sums of the three individual fractions, is generally better than 10%. Oxidizable and reducible phases therefore constitute important sources of potentially available heavy metals that need to be explicitly considered when evaluating sediment and water quality impacts on biota.« less

Insights into the history and timing of post-European land use disturbance on sedimentation rates in catchments draining to the Great Barrier Reef.

PubMed

Bartley, Rebecca; Thompson, Chris; Croke, Jacky; Pietsch, Tim; Baker, Brett; Hughes, Kate; Kinsey-Henderson, Anne

2018-06-01

Sediment runoff has been cited as a major contributor to the declining health of the Great Barrier Reef (GBR), however, climate and land use drivers have not been jointly evaluated. This study used alluvial archives from fluvial benches in two tributaries of the Upper Burdekin catchment together with the best available land use history and climate proxy records to provide insights into the timing of depositional events in this region over the past 500 years. This study suggests that mining and the increased runoff variability in the latter half of the nineteenth century are the likely sources of the original excess sediment that was used to build the bench features in these catchments. Grazing also contributed to increased bench sedimentation prior to 1900, however, the contribution of grazing was likely more significant in the second half of the 20th century, and continues to be a dominant land use contributor today. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sources of polychlorinated biphenyls to Devils Swamp Lake near Baton Rouge, Louisiana

USGS Publications Warehouse

Van Metre, Peter C.; Wilson, Jennifer T.; Kimball, Briant A.

2006-01-01

Devils Swamp Lake near Baton Rouge, Louisiana, created in 1973 by dredging in Devils Swamp along the Mississippi River, is contaminated with polychlorinated biphenyls (PCBs) from historical industrial discharges. This study involved the investigation of the occurrence, distribution, and sources of PCBs in the lake, including the possible historical contribution of PCBs from a hazardous-chemical disposal facility by way of a wastewater drainage ditch that was used from 1971 to 1993. Six bed sediment cores from the lake and three bed sediment grab samples from the drainage ditch were collected; 61 subsamples from selected intervals in five of the six cores and the three grab samples from the ditch were analyzed for PCBs using an immunoassay screening method. Sixteen of the core subsamples and one ditch sample were analyzed for organochlorine pesticides, PCBs, polycyclic aromatic hydrocarbons (PAHs) (15 samples), and major and trace elements. PCB congener profiles and a factor analysis of congener composition indicate that PCBs in sediment from the drainage ditch and in lake sediment deposited near the canal since the mid-1980s are similar, which indicates the disposal facility, by way of the wastewater drainage ditch, is the source of the PCBs. Sediment from several hundred meters down the lake to the west, near where Bayou Baton Rouge enters the lake, had a different PCB composition and in a sample deposited in the early 1980s, a much higher concentration, indicating a second source of PCBs in the watershed of Bayou Baton Rouge. Large differences in PAHs and metals between sediment near the ditch and sediment near Bayou Baton Rouge support this conclusion. The identity of the Bayou Baton Rouge source(s) cannot be established using available data. The short duration and relatively high concentrations of PCBs from the bayou source indicate either a spill or a flood-related release-there was a large flood on the Mississippi River in 1983. Older (deeper) samples from cores near the drainage ditch (dated as deposited before the mid-1980s) had PCB compositions that indicate a mixture of sources (Bayou Baton Rouge and the drainage ditch). Elevated PCB concentrations in sediment from the drainage ditch and cores from near the mouth of the ditch in recent (post-2000) samples indicate that some PCB inputs from the ditch might still be occurring.

Seasonal variations and environmental risk assessment of trace elements in the sediments of Uppanar River estuary, southern India.

PubMed

Gopal, V; Nithya, B; Magesh, N S; Jayaprakash, M

2018-04-01

Twenty four surface sediments were gathered from the Uppanar river estuary, southern India to evaluate the trace element contamination risk in the sediments. The circulation of organic matter and calcium carbonate were controlled by algal blooms and shell fragments. Moreover, the concentrations of iron and manganese in the estuarine sediments were possibly contributed by riverine sources and geogenic processes. The geoaccumulation index, enrichment factor and contamination factor reveals that the sediments were contaminated by copper and chromium. The pollution load index recommends that the estuarine sediments have the risk of pollution. The sediment pollution index highlights that the majority of the sediments are low polluted sediments. The potential ecological risk index discloses that the Uppanar river estuary is under moderate risk. The statistical analysis reveals that the organic matter content is managed by fine fractions and the majority of the trace elements are associated with each other having similar origin. Copyright © 2018 Elsevier Ltd. All rights reserved.

Humic acids contribution to sedimentary organic matter on a shallow continental shelf (northern Adriatic Sea)

NASA Astrophysics Data System (ADS)

Giani, M.; Rampazzo, F.; Berto, D.

2010-12-01

The shallow northern Adriatic Sea receives large river runoff, predominantly from the Po River, which is the main allochthonous source of nutrients and organic matter. The origin and quality of organic matter deposited in the sediments can influence the degradation processes and oxygen consumption in the bottom waters as well as the fate of many pollutants. Therefore the humic acids (HA) were quantified in surface and sub-surface sediments collected in an area of the north-western Adriatic platform south of Po River. HA showed to have a relevant contribution to sedimentary organic matter. HA content in sediments were positively correlated with the organic carbon concentration and negatively with redox potential and pH, particularly in sub-surface reduced sediments, suggesting their important role in the diagenetic processes taking place in anoxic conditions. Elemental composition of HA extracted from surface and sub-surface sediments showed a wide range of variation of the C org/N ratios which could be due to a mixed (terrestrial and marine) origin and/or an elevated bacteria degradation of nitrogen during diagenesis processes in sediments. The spectroscopic ratios A 2/A 4 and A 4/A 6 of HA confirmed a mixed origin with a high degree of condensation of the HA extracted from sediments.

Radioactive fallout reconstruction from contemporary measurements of reservoir sediments.

PubMed

Krey, P W; Heit, M; Miller, K M

1990-11-01

The temporal history of atmospheric deposition to a watershed area can be preserved in the sediment of a lake or reservoir that is supplied by the watershed. The 137Cs and isotopic Pu concentrations with depth were determined in the sediments of two reservoirs, Enterprise and Deer Creek, which are located in widely separated regions of the state of Utah. Our data not only reconstruct the history of the total radioactive fallout in the area, but also permit estimating the contributions from global sources and from the Nevada Test Site detonations in the 1950s.

Use of spatial statistics and isotopic tracers to measure the influence of arsenical pesticide use on stream sediment chemistry in New England, USA

USGS Publications Warehouse

Robinson, G.R.; Ayuso, R.A.

2004-01-01

Arsenical pesticides and herbicides, principally Pb arsenate, Ca arsenate, and Na arsenate with lesser use of other metal-As pesticides, were widely applied on apple, blueberry, and potato crops in New England during the first half of the twentieth century. Agricultural census data for this time period is used to define an agricultural index that identifies areas that are inferred to have used arsenical pesticides extensively. Factor analysis on metal concentrations in 1597 stream sediment samples collected throughout New England, grouped by agricultural-index categories, indicate a positive association of areas with stream sediment sample populations that contain higher As and Pb concentrations than samples from the region as a whole with sample site settings having high agricultural-index values. Population statistics for As and Pb concentrations and factor scores for an As-Pb factor all increase systematically and significantly with increasing agricultural-index intensity in the region, as tested by Kruskal-Wallis analysis. Lead isotope compositions for 16 stream sediments from a range of agricultural-index settings generally overlap the observed variation in rock sulfides and their weathering products; however, sediments collected from high agricultural-index settings have slightly more radiogenic Pb compositions, consistent with an industrial Pb contribution to these samples. Although weathering products from rocks are likely to be the dominant source of As and metals to most of the stream sediment samples collected in the region, the widespread use of arsenical pesticides and herbicides in New England during the early 1900-1960s appears to be a significant anthropogenic source of As and metals to many sediments in agricultural areas in the region and has raised background levels of As in some regions. Elevated concentrations of As in stream sediments are of concern for two reasons. Stream sediments with elevated As concentrations delineate areas with elevated background concentrations of As from both natural rock and anthropogenic sources that may contribute As to groundwater systems used for drinking water supplies. Conversion of agricultural land contaminated with arsenical pesticide residues to residential development may increase the likelihood that humans will be exposed to As. In addition, many stream sediment sites have As concentrations that exceed sediment quality guidelines established for freshwater ecosystems. Thirteen percent of the New England sediment sample sites exceed 9.79 mg/kg As, the threshold effects concentration (TEC), below which harmful effects are unlikely to be observed. Arsenic concentrations exceed 33 mg/kg, the probable effects concentration (PEC), above which harmful effects on sediment-dwelling organisms are expected to occur frequently, at 1.25% of the sediment sample sites. The sample sites that exceed the PEC value occur predominately in agricultural areas that used arsenical pesticides.

Pollutant Source Tracking (PST) Technical Guidance

DTIC Science & Technology

2011-12-01

in the context of heavy metals (lead, copper), is considered to be a minor process contribution to the source fingerprint. 3.7 RAPID SCREENING...limits (summarized in Table 2) support the use of ICP-AES (ICP-OES) for heavy metal determination in soils , sediments, wastewater and other matrices...are included here. Isotopic ratios of stable isotopes of the metal of interest can be used for source identification and apportionment in complex

Discharge modulates stream metabolism dependence on fine particulate organic carbon in a Mediterranean WWTP-influenced stream

NASA Astrophysics Data System (ADS)

Drummond, J. D.; Bernal, S.; Meredith, W.; Schumer, R.; Martí Roca, E.

2017-12-01

Waste water treatment plant (WWTP) effluents constitute point source inputs of fine sediment, nutrients, carbon, and microbes to stream ecosystems. A range of responses to these inputs may be observed in recipient streams, including increases in respiration rates, which augment CO2 emissions to the atmosphere. Yet, little is known about which fractions of organic carbon (OC) contribute the most to stream metabolism in WWTP-influenced streams. Fine particulate OC (POC) represents ca. 40% of the total mass of OC in river networks, and is generally more labile than dissolved OC. Therefore, POC inputs from WWTPs could contribute disproportionately to higher rates of heterotrophic metabolism by stream microbial communities. The aim of this study was to investigate the influence of POC inputs from a WWTP effluent on the metabolism of a Mediterranean stream over a wide range of hydrologic conditions. We hypothesized that POC inputs would have a positive effect on respiration rates, and that the response to POC availability would be larger during low flows when the dilution capacity of the recipient stream is negligible. We focused on the easily resuspended fine sediment near the sediment-water interface (top 3 cm), as this region is a known hot spot for biogeochemical processes. For one year, samples of resuspended sediment were collected bimonthly at 7 sites from 0 to 800 m downstream of the WWTP point source. We measured total POC, organic matter (OM) content (%), and the associated metabolic activity of the resuspended sediment using the resazurin-resorufin smart tracer system as a proxy for aerobic ecosystem respiration. Resuspended sediment showed no difference in total POC over the year, while the OM content increased with decreasing discharge. This result together with the decreasing trend of total POC observed downstream of the point source during autumn after a long dry period, suggests that the WWTP effluent was the main contributor to stream POC. Furthermore, there was a positive relationship between aerobic ecosystem respiration and OM content in resuspended sediments. Our results suggest that WWTP effluents can be important sources of POC to recipient streams, and that the increased availability of POC enhances aerobic ecosystem respiration, especially when the dilution capacity of the recipient streams is low.

Understanding the Role of the Co-Play between Land Use and Climate on Sediment Flux Laws in Intensively Managed Landscapes

NASA Astrophysics Data System (ADS)

Abban, B. K.; Papanicolaou, T.; Wilson, C. G.; Giannopoulos, C.; Sivapalan, M.

2017-12-01

In intensively managed landscapes (IMLs), changes in the land cover from what were previously grasslands, and their associated management practices, have led to a high degree of spatial heterogeneity and temporal variability in landscape processes that were absent pre-settlement. This has fundamentally altered terrestrial and instream sediment flux characteristics in regards to net amounts and proportions of source contributions, at shorter time scales. Sediment flux laws are now highly impacted by event-based dynamics. Whereas some events result in highly intermittent fluxes, others result in fluxes that largely propagate in the form of waves. This behavior is governed by the extent of land cover at the given time of the season, as well as the magnitude of the storm event. In addition, flux behavior changes as one moves from the plot scale to the watershed scale, and also with crop rotation. Thus, fluxes are now non-stationary due to continued human activity and its co-play with climate. The goal of this study is to develop a better understanding of the non-stationarity in sediment flux laws that arise from the co-play between land use and climate. Our approach involves the development of a modeling framework that considers all the exchanges between terrestrial and instream sources and addresses the issue of equifinality regarding terrestrial and instream source contributions on net sediment fluxes. The modeling framework couples an established terrestrial erosion model with an established in-stream sediment transport model. As a first step, our study focuses on the Clear Creek Watershed, IA, which is part of the Critical Zone Observatory for Intensively Managed Landscapes. We complement our modeling efforts with extensive terrestrial and instream field observations gathered at different times of the growing season, and in different years. We also used Bayesian sediment sourcing techniques to determine the provenance of transported material as well as the uncertainty related to the travel times and delivery of material across the different spatial scales. Findings from this study will shed light on the dominant factors governing fluxes laws and how they change over the course of a season, as well as the factors that control the changes in the flux laws across space.

Distribution and sources of carbon, nitrogen, phosphorus and biogenic silica in the sediments of Chilika lagoon

NASA Astrophysics Data System (ADS)

Nazneen, Sadaf; Raju, N. Janardhana

2017-02-01

The present study investigated the spatial and vertical distribution of organic carbon (OC), total nitrogen (TN), total phosphorus (TP) and biogenic silica (BSi) in the sedimentary environments of Asia's largest brackish water lagoon. Surface and core sediments were collected from various locations of the Chilika lagoon and were analysed for grain-size distribution and major elements in order to understand their distribution and sources. Sand is the dominant fraction followed by silt + clay. Primary production within the lagoon, terrestrial input from river discharge and anthropogenic activities in the vicinity of the lagoon control the distribution of OC, TN, TP and BSi in the surface as well as in the core sediments. Low C/N ratios in the surface sediments (3.49-3.41) and cores (4-11.86) suggest that phytoplankton and macroalgae may be major contributors of organic matter (OM) in the lagoon. BSi is mainly associated with the mud fraction. Core C5 from Balugaon region shows the highest concentration of OC ranging from 0.58-2.34%, especially in the upper 30 cm, due to direct discharge of large amounts of untreated sewage into the lagoon. The study highlights that Chilika is a dynamic ecosystem with a large contribution of OM by autochthonous sources with some input from anthropogenic sources as well.

Lead concentration distribution and source tracing of urban/suburban aquatic sediments in two typical famous tourist cities: Haikou and Sanya, China.

PubMed

Dong, Zhicheng; Bao, Zhengyu; Wu, Guoai; Fu, Yangrong; Yang, Yi

2010-11-01

The content and spatial distribution of lead in the aquatic systems in two Chinese tropical cities in Hainan province (Haikou and Sanyan) show an unequal distribution of lead between the urban and the suburban areas. The lead content is significantly higher (72.3 mg/kg) in the urban area than the suburbs (15.0 mg/kg) in Haikou, but quite equal in Sanya (41.6 and 43.9 mg/kg). The frequency distribution histograms suggest that the lead in Haikou and in Sanya derives from different natural and/or anthropogenic sources. The isotopic compositions indicate that urban sediment lead in Haikou originates mainly from anthropogenic sources (automobile exhaust, atmospheric deposition, etc.) which contribute much more than the natural sources, while natural lead (basalt and sea sands) is still dominant in the suburban areas in Haikou. In Sanya, the primary source is natural (soils and sea sands).

Tracing organic matter sources in a tropical lagoon of the Caribbean Sea

NASA Astrophysics Data System (ADS)

Alonso-Hernández, Carlos M.; Garcia-Moya, Alejandro; Tolosa, Imma; Diaz-Asencio, Misael; Corcho-Alvarado, Jose Antonio; Morera-Gomez, Yasser; Fanelli, Emanuela

2017-09-01

The natural protected lagoon of Guanaroca, located between Cienfuegos Bay and the Arimao River, Cuba, has been heavily impacted by human-induced environmental changes over the past century. Sources of organic matter in the Guanaroca lagoon and concentrations of radioisotopes (210Pb, 226Ra, 137Cs and 239,240Pu), as tracers of anthropogenic impacts, were investigated in a 78 cm sediment core. Variations in total organic carbon (TOC), total nitrogen (TN), stable isotopic composition (δ13C and δ15N) and ratio of total organic carbon to total nitrogen (C/N) were analysed. On such a basis, environmental changes in the lagoon were revealed. Down core variation patterns of the parameters representing sources of organic matter were predominantly related to the impacts of human activities. Up to the nineteenth century, the principal sources of organic matter to sediments (more than 80%) were a mixing of terrestrial vascular plants ( 48%) and freshwater phytoplankton ( 8%), with minimal contribution from the marine component ( 16%). In the period 1900-1980, due to the strong influence of human activities in the catchment area, the water exchange capacity of the lagoon declined substantially, as indicated by the relatively high proportion of organic matter originated from human activities (58%). Since 1980, as a result of management actions in the protected area, the lagoon has regained gradually its capability to exchange freshwater, showing sources of organic matter similar to the natural conditions recorded previous to 1900, although an indication of human impact (treated sewage contributed for 26% to the organic matter in sediments) was still observed and further management measures would be required.

Distributions and contamination assessment of heavy metals in the surface sediments of western Laizhou Bay: Implications for the sources and influencing factors.

PubMed

Zhang, Pan; Hu, Rijun; Zhu, Longhai; Wang, Peng; Yin, Dongxiao; Zhang, Lianjie

2017-06-15

Heavy metals (Cu, Pb, Cr, Cd and As) contents in surface sediments from western Laizhou Bay were analysed to evaluate the spatial distribution pattern and their contamination level. As was mainly concentrated in the coastal area near the estuaries and the other metals were mainly concentrated in the central part of the study area. The heavy metals were present at unpolluted levels overall evaluated by the sediment quality guidelines and geoaccumulation index. Principal component analysis suggest that Cu, Pb and Cd were mainly sourced from natural processes and As was mainly derived from anthropogenic inputs. Meanwhile, Cr originated from both natural processes and anthropogenic contributions. Tidal currents, sediments and human activities were important factors affecting the distribution of heavy metals. The heavy metal environment was divided into four subareas to provide a reference for understanding the distribution and pollution of heavy metals in the estuary-bay system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessing temporal variations in connectivity through suspended sediment hysteresis analysis

NASA Astrophysics Data System (ADS)

Sherriff, Sophie; Rowan, John; Fenton, Owen; Jordan, Phil; Melland, Alice; Mellander, Per-Erik; hUallacháin, Daire Ó.

2016-04-01

Connectivity provides a valuable concept for understanding catchment-scale sediment dynamics. In intensive agricultural catchments, land management through tillage, high livestock densities and extensive land drainage practices significantly change hydromorphological behaviour and alter sediment supply and downstream delivery. Analysis of suspended sediment-discharge hysteresis has offered insights into sediment dynamics but typically on a limited selection of events. Greater availability of continuous high-resolution discharge and turbidity data and qualitative hysteresis metrics enables assessment of sediment dynamics during more events and over time. This paper assesses the utility of this approach to explore seasonal variations in connectivity. Data were collected from three small (c. 10 km2) intensive agricultural catchments in Ireland with contrasting morphologies, soil types, land use patterns and management practices, and are broadly defined as low-permeability supporting grassland, moderate-permeability supporting arable and high-permeability supporting arable. Suspended sediment concentration (using calibrated turbidity measurements) and discharge data were collected at 10-min resolution from each catchment outlet and precipitation data were collected from a weather station within each catchment. Event databases (67-90 events per catchment) collated information on sediment export metrics, hysteresis category (e.g., clockwise, anti-clockwise, no hysteresis), numeric hysteresis index, and potential hydro-meteorological controls on sediment transport including precipitation amount, duration, intensity, stream flow and antecedent soil moisture and rainfall. Statistical analysis of potential controls on sediment export was undertaken using Pearson's correlation coefficient on separate hysteresis categories in each catchment. Sediment hysteresis fluctuations through time were subsequently assessed using the hysteresis index. Results showed the numeric hysteresis index varied over time in all three catchments. The exact response was catchment specific reflecting changing sediment availability and connectivity through time as indicated by dominant controls. In the low-permeability grassland catchment, proximal sources dominated which was consistent with observations of active channel bank erosion. Seasonal increases in rainfall increased the erosion potential but continuous grassland cover mitigated against hillslope sediment contributions despite high hydrological connectivity and surface pathways. The moderate-permeability arable catchment was dominated by events with a distal source component but those with both proximal and distal sediment sources yielded the highest sediment quantities. These events were driven by rainfall parameters suggesting sediment were surface derived and the hillslope was hydrologically connected during most events. Through time, a sustained period of rainfall increased the magnitude of negative hysteresis, likely demonstrating increasing surface hydrological connectivity due to increased groundwater saturation. Where increased hydrological connectivity coincided with low groundcover, the largest sediment exports were recorded. Events in the high permeability catchment indicated predominantly proximal sediments despite abundant distal sources from tilled fields. The infiltration dominated high permeability soils hydrologically disconnected these field sources and limited sediment supply. However, the greatest sediment export occurred in this catchment suggesting thresholds existed, which when exceeded during higher magnitude events, resulted in efficient conveyance of sediments. Hysteresis analysis offers wider utility as a tool to understand sediment pathways and connectivity issues with applications to catchment management strategies.

Spatial variability of primary organic sources regulates ichthyofauna distribution despite seasonal influence in Terminos lagoon and continental shelf of Campeche, Mexico

NASA Astrophysics Data System (ADS)

Romo Rios, J. A.; Aguíñiga-García, S.; Sanchez, A.; Zetina-Rejón, M.; Arreguín-Sánchez, F.; Tripp-Valdéz, A.; Galeana-Cortazár, A.

2013-05-01

Human activities have strong impacts on coastal ecosystems functioning through their effect on primary organic sources distributions and resulting biodiversity. Hence, it appears to be of utmost importance to quantify contribution of primary producers to sediment organic matter (SOM) spatial variability and its associated ichthyofauna. The Terminos lagoon (Gulf of Mexico) is a tropical estuary severely impacted by human activities even though of primary concern for its biodiversity, its habitats, and its resource supply. Stable isotope data (d13C, d15N) from mangrove, seaweed, seagrass, phytoplankton, ichthyofauna and SOM were sampled in four zones of the lagoon and the continental shelf through windy (November to February), dry (March to June) and rainy (July to October) seasons. Stable Isotope Analysis in R (SIAR) mixing model were used to determine relative contributions of the autotrophic sources to the ichthyofauna and SOM. Analysis of variance of ichthyofauna isotopic values showed significant differences (P < 0.001) in the four zones of lagoon despite the variability introduced by the windy, dry and rainy seasons. In lagoons rivers discharge zone, the mangrove contribution to ichthyofauna was 40% and 84% to SOM. Alternative use of habitat by ichthyofauna was evidenced since in the deep area of the lagoon (4 m), the contribution of mangrove to fish is 50%, and meanwhile contribution to SOM is only 77%. Although phytoplankton (43%) and seaweed (41%) contributions to the adjacent continental shelf ichthyofauna were the main organic sources, there was 37% mangrove contribution to SOM, demonstrating conspicuous terrigenous influence from lagoon ecosystem. Our results point toward organic sources spatial variations that regulate fish distribution. In Terminos lagoon, significant correlation (p-value = 0.2141 and r=0.79) of Ariopsis felis and Sphoeroides testudineus abundances and seaweed and seagrasses contributions (30-35%) during both dry and rainy seasons, evidence that spatial variability organic sources could be central for the state of equilibrium of ecosystems. Keywords: sediment organic matter, mangrove, ecosystems, mixing model, trophic structure

Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: fatty acids.

PubMed

Poerschmann, Juergen; Koschorreck, Matthias; Górecki, Tadeusz

2012-01-01

Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5 cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far. Combined FA concentrations in the surface sediment were higher compared to those in the deep sediment (497 vs. 127 μg g(-1)d.w., respectively). This was related to deposition of autochthonous biomass and higher terrestrial plants onto the surface sediment, as well as--to lesser extent--with higher bacterial activity on the sediment-water interface. The FA distribution in both sediments was characterized by a strong even-over-odd preference and was bimodal in nature: there was a cluster at nC(14)-nC(18) characteristic of chiefly autochthonous (algal and bacterial) SOM production, and another cluster at nC(22-28) related to input from higher plants. The FA distribution in the surface sediment pointed to higher terrestrial input compared to autochthonous contribution to SOM (67%:33%) as an estimate. Fingerprinting of viable bacteria was accomplished through signature FA markers including branched C(15) and C(17) surrogates, cyclopropanoic acids, 3-hydroxy (OH) acids and monounsaturated surrogates with unusual double bond localization. The abundance of Gram-negative bacteria was higher in the surface sediment as evidenced by total diagnostic 3-OH-fatty acids (37 μg g(-1) versus 25 μg g(-1)). Potential source taxa in both sediment layers included acidophilic iron- and sulfur-oxidizing bacteria including Acidithiobacillus ferrooxidans. High abundances of terminally branched C(15) and C(17) surrogates in both sediments pointed to sulfate- and iron-reducing bacteria. Signature FAs characteristic of methanotrophs were virtually lacking in both sediments. Copyright © 2011 Elsevier B.V. All rights reserved.

Water quality assessment of the San Joaquin--Tulare basins, California; analysis of available data on nutrients and suspended sediment in surface water, 1972-1990

USGS Publications Warehouse

Kratzer, Charles R.; Shelton, Jennifer L.

1998-01-01

Nutrients and suspended sediment in surface water of the San Joaquin-Tulare basins in California were assessed using 1972-1990 data from the U.S. Geological Survey's National Water Information System and the U.S. Environmental Protection Agency's STOrage and RETrieval database. Loads of nutrients and suspended sediment were calculated at several sites and the contributions from point and nonpoint sources were estimated. Trends in nutrient and suspended-sediment concentrations were evaluated at several sites, especially at the basin outlet on the San Joaquin River. Comparisons of nutrient and suspended sediment concentrations were made among three environmental settings: the San Joaquin Valley--west side, the San Joaquin Valley--east side, and the Sierra Nevada.

Wetland biogeochemistry and ecological risk assessment

NASA Astrophysics Data System (ADS)

Bai, Junhong; Huang, Laibin; Gao, Haifeng; Zhang, Guangliang

2017-02-01

Wetlands are an important ecotone between terrestrial and aquatic ecosystems and can provide great ecological service functions. Soils/sediments are one of the important components of wetland ecosystems, which support wetland plants and microorganisms and influence wetland productivity. Moreover, wetland soils/sediments serve as sources, sinks and transfers of carbon, nitrogen, phosphorus and chemical contaminants such as heavy metals. In natural wetland ecosystems, wetland soils/sediments play a great role in improving water quality as these chemical elements can be retained in wetland soils/sediments for a long time. Moreover, the biogeochemical processes of the abovementioned elements in wetland soils/sediments can drive wetland evolution and development, and their changes will considerably affect wetland ecosystem health. Therefore, a better understanding of wetland soil biogeochemistry will contribute to improving wetland ecological service functions.

Clay mineralogy and source-to-sink transport processes of Changjiang River sediments in the estuarine and inner shelf areas of the East China Sea

NASA Astrophysics Data System (ADS)

Zhao, Yifei; Zou, Xinqing; Gao, Jianhua; Wang, Chenglong; Li, Yali; Yao, Yulong; Zhao, Wancang; Xu, Min

2018-02-01

We examined the source-to-sink sediment transport processes from the Changjiang River to the estuarine coastal shelf area by analyzing the clay mineral assemblages in suspended sediment samples from the Changjiang River catchment and surface samples from the estuarine coastal shelf area following the impoundment of the Three Gorges Dam (TGD) in 2003. The results indicate that the clay mineral compositions throughout the study area are dominated by illite, with less abundant kaolinite and chlorite and scarce smectite. The clay minerals display distinct differences in the tributaries and exhibit obvious changes in the trunk stream compared with the periods before 2003, and the source of sediment has largely shifted to the mid- to lower reaches of the river after 2003. Spatially, the clay mineral assemblages in the estuarine area define two compositionally distinct provinces. Province I covers the mud area of the Changjiang River estuary and the Zhe-Min coastal region, where sediment is primarily supplied by the Changjiang River. Province II includes part of the Changjiang River estuary and the southeastern portion of the study area, where the sediment is composed of terrestrial material from the Changjiang River and re-suspended material from the Huanghe River carried by the Jiangsu coastal current. Moreover, the other smaller rivers in China (including the Oujiang and Minjiang rivers of mainland China and the rivers of West Taiwan) also contribut sediments to the estuarine and inner shelf areas. In general, the clay mineral assemblages in the Changjiang River estuarine area are have mainly been controlled by sediment supplied from upstream of the Changjiang River tributaries. However, since the completion of the TGD in 2003, the mid- to downstream tributaries have become the main source of sediments from the Changjiang catchment into the East China Sea. These analyses further demonstrate that the coastal currents and the decrease in the sediment load of the river have the greatest impacts on the distribution and transport of clay minerals assemblages in the sediments.

Sediment Tracking Using Carbon and Nitrogen Stable Isotopes

NASA Astrophysics Data System (ADS)

Fox, J. F.; Papanicolaou, A.

2002-12-01

As landscapes are stripped of valuable, nutrient rich topsoils and streams are clouded with habitat degrading fine sediment, it becomes increasingly important to identify and mitigate erosive surfaces. Particle tracking using vegetative derived carbon (C) and nitrogen (N) isotopic signatures and carbon/nitrogen (C/N) atomic ratios offer a promising technique to identify such problematic sources. Consultants and researchers successfully use C, N, and other stable isotopes of water for hydrologic purposes, such as quantifying groundwater vs. surface water contribution to a hydrograph. Recently, C and N isotopes and C/N atomic ratios of sediment were used to determine sediment mass balance within estuarine environments. The current research investigates C and N isotopes and C/N atomic ratios of source sediment for two primary purposes: (1) to establish a blueprint methodology for estimating sediment source and erosion rates within a watershed using this isotopic technology coupled with mineralogy fingerprinting techniques, radionuclide transport monitoring, and erosion-transport models, and (2) to complete field studies of upland erosion processes, such as, solifluction, mass wasting, creep, fluvial erosion, and vegetative induced erosion. Upland and floodplain sediment profiles and riverine suspended sediment were sampled on two occasions, May 2002 and August 2002, in the upper Palouse River watershed of northern Idaho. Over 300 samples were obtained from deep intermountain valley (i.e. forest) and rolling crop field (i.e. agriculture) locations. Preliminary sample treatment was completed at the Washington State University Water Quality Laboratory where samples were dried, removed of organic constituents, and prepared for isotopic analysis. C and N isotope and C/N atomic ratio analyses was performed at the University of Idaho Natural Resources Stable Isotope Laboratory using a Costech 4010 Elemental Combustion System connected with a continuous flow inlet system to the Finnigan MAT Delta Plus isotope ratio mass spectrometer. Results indicate distinct N isotopic signatures and C/N atomic ratios for forest and agriculture sediment sources. In addition, unique C and N isotopic signatures and C/N atomic ratios exist within floodplain and upland surfaces, and within the 10 centimeter profiles of erosion and deposition locations. Suspended sediment analyses are preliminary at this time. Conclusions indicate that sediment C and N isotopic signature and C/N atomic ratio are dependent upon land use and soil moisture conditions, and will serve as a useful technique in quantifying erosive source rates and understanding upland erosion processes.

Anthropogenic activities have contributed moderately to increased inputs of organic materials in marginal seas off China.

PubMed

Liu, Liang-Ying; Wei, Gao-Ling; Wang, Ji-Zhong; Guan, Yu-Feng; Wong, Charles S; Wu, Feng-Chang; Zeng, Eddy Y

2013-10-15

Sediment has been recognized as a gigantic sink of organic materials and therefore can record temporal input trends. To examine the impact of anthropogenic activities on the marginal seas off China, sediment cores were collected from the Yellow Sea, the inner shelf of the East China Sea (ECS), and the South China Sea (SCS) to investigate the sources and spatial and temporal variations of organic materials, i.e., total organic carbon (TOC) and aliphatic hydrocarbons. The concentration ranges of TOC were 0.5-1.29, 0.63-0.83, and 0.33-0.85%, while those of Σn-C14-35 (sum of n-alkanes with carbon numbers of 14-35) were 0.08-1.5, 0.13-1.97, and 0.35-0.96 μg/g dry weight in sediment cores from the Yellow Sea, ECS inner shelf, and the SCS, respectively. Terrestrial higher plants were an important source of aliphatic hydrocarbons in marine sediments off China. The spatial distribution of Σn-C14-35 concentrations and source diagnostic ratios suggested a greater load of terrestrial organic materials in the Yellow Sea than in the ECS and SCS. Temporally, TOC and Σn-C14-35 concentrations increased with time and peaked at either the surface or immediate subsurface layers. This increase was probably reflective of elevated inputs of organic materials to marginal seas off China in recent years, and attributed partly to the impacts of intensified anthropogenic activities in mainland China. Source diagnostics also suggested that aliphatic hydrocarbons were mainly derived from biogenic sources, with a minority in surface sediment layers from petroleum sources, consistent with the above-mentioned postulation.

Tectonic isolation from regional sediment sourcing of the Paradox Basin

NASA Astrophysics Data System (ADS)

Smith, T. M.; Saylor, J.; Sundell, K. E.; Lapen, T. J.

2017-12-01

The Appalachian and Ouachita-Marathon mountain ranges were created by a series of tectonic collisions that occurred through the middle and late Paleozoic along North America's eastern and southern margins, respectively. Previous work employing detrital zircon U-Pb geochronology has demonstrated that fluvial and eolian systems transported Appalachian-derived sediment across the continent to North America's Paleozoic western margin. However, contemporaneous intraplate deformation of the Ancestral Rocky Mountains (ARM) compartmentalized much of the North American western interior and mid-continent. We employ lithofacies characterization, stratigraphic thickness, paleocurrent data, sandstone petrography, and detrital zircon U-Pb geochronology to evaluate source-sink relationships of the Paradox Basin, which is one of the most prominent ARM basins. Evaluation of provenance is conducted through quantitative comparison of detrital zircon U-Pb distributions from basin samples and potential sources via detrital zircon mixture modeling, and is augmented with sandstone petrography. Mixing model results provide a measure of individual source contributions to basin stratigraphy, and are combined with outcrop and subsurface data (e.g., stratigraphic thickness and facies distributions) to create tectonic isolation maps. These maps elucidate drainage networks and the degree to which local versus regional sources influence sediment character within a single basin, or multiple depocenters. Results show that despite the cross-continental ubiquity of Appalachian-derived sediment, fluvial and deltaic systems throughout much of the Paradox Basin do not record their influence. Instead, sediment sourcing from the Uncompahgre Uplift, which has been interpreted to drive tectonic subsidence and formation of the Paradox Basin, completely dominated its sedimentary record. Further, the strong degree of tectonic isolation experienced by the Paradox Basin appears to be an emerging, yet common feature among other intraplate, tectonically active basins.

Fingerprinting selection for agroenvironmental catchment studies: EDXRF analysis for solving complex artificial mixtures

NASA Astrophysics Data System (ADS)

Torres Astorga, Romina; Velasco, Hugo; Dercon, Gerd; Mabit, Lionel

2017-04-01

Soil erosion and associated sediment transportation and deposition processes are key environmental problems in Central Argentinian watersheds. Several land use practices - such as intensive grazing and crop cultivation - are considered likely to increase significantly land degradation and soil/sediment erosion processes. Characterized by highly erodible soils, the sub catchment Estancia Grande (12.3 km2) located 23 km north east of San Luis has been investigated by using sediment source fingerprinting techniques to identify critical hot spots of land degradation. The authors created 4 artificial mixtures using known quantities of the most representative sediment sources of the studied catchment. The first mixture was made using four rotation crop soil sources. The second and the third mixture were created using different proportions of 4 different soil sources including soils from a feedlot, a rotation crop, a walnut forest and a grazing soil. The last tested mixture contained the same sources as the third mixture but with the addition of a fifth soil source (i.e. a native bank soil). The Energy Dispersive X Ray Fluorescence (EDXRF) analytical technique has been used to reconstruct the source sediment proportion of the original mixtures. Besides using a traditional method of fingerprint selection such as Kruskal-Wallis H-test and Discriminant Function Analysis (DFA), the authors used the actual source proportions in the mixtures and selected from the subset of tracers that passed the statistical tests specific elemental tracers that were in agreement with the expected mixture contents. The selection process ended with testing in a mixing model all possible combinations of the reduced number of tracers obtained. Alkaline earth metals especially Strontium (Sr) and Barium (Ba) were identified as the most effective fingerprints and provided a reduced Mean Absolute Error (MAE) of approximately 2% when reconstructing the 4 artificial mixtures. This study demonstrates that the EDXRF fingerprinting approach performed very well in reconstructing our original mixtures especially in identifying and quantifying the contribution of the 4 rotation crop soil sources in the first mixture.

Fertilisation of the Southern Atlantic: Ephemeral River Valleys as a replenishing source of nutrient-enriched mineral aerosols

NASA Astrophysics Data System (ADS)

Dansie, Andrew; Wiggs, Giles; Thomas, David

2016-04-01

Oceanic dust deposition provides biologically important iron and macronutrients (Phosphorus (P) and Nitrogen-based (N) compounds) that contribute to phytoplankton growth, marine productivity and oceanic atmospheric CO2 uptake. Research on dust emission sources to date has largely focused on the northern hemisphere and on ephemeral lakes and pans. Our work considers the ephemeral river valleys of the west coast of Namibia as an important yet overlooked source of ocean-fertilizing dust. Dust plumes are frequently emitted from the river valleys by strong easterly winds during the Southern Hemisphere winter, when the upwelling of the Benguela Current is at its weakest. We present field data from dust emission source areas along the main river channels near the coastal termini of the Huab, Kuiseb and Tsauchab river valleys. Collected data include erodible surface sediment, wind-blown flux, and associated meteorological data. Extensive surface sediment sampling was also undertaken throughout the combined 34,250 km2 extent of each river valley catchment with samples collected from within the main river channels, the main branches of each river system, selected tributaries, and into the upper watersheds. Geochemical data show valley sediment and wind-blown flux material have high concentrations of bioavailable Fe, P and N, exceeding that measured at the major dry lake basin dust sources in southern Africa. The contribution of fertilising deposition material is enhanced by both the spatial proximity of the source areas to the ocean and enrichment of source material by ephemeral fluvial accumulation and desiccation. Results show that geographical factors within each watershed play a key role in the nutrient composition of the emitting fluvial deposits in the river valleys. Analysis explores potential relationships between land use, geology, climate and precipitation in the upper watersheds and their influence on bioavailability of Fe, P and N compounds in wind-erodible valley sediments. MODIS data for dust plume identification and chlorophyll concentration in the southern Atlantic is utilised to investigate associations between recorded dust emission events and phytoplankton growth in the ocean surface waters.

The impacts of tracer selection and corrections for organic matter and particle size on the results of quantitative sediment fingerprinting. A case study from the Nene basin, UK.

NASA Astrophysics Data System (ADS)

Pulley, Simon; Ian, Foster; Paula, Antunes

2014-05-01

In recent years, sediment fingerprinting methodologies have gained widespread adoption when tracing sediment provenance in geomorphological research. A wide variety of tracers have been employed in the published literature, with corrections for particle size and organic matter applied when the researcher judged them necessary. This paper aims to explore the errors associated with tracer use by a comparison of fingerprinting results obtained using fallout and lithogenic radionuclides, geochemical, and mineral magnetic tracers in a range of environments located in the Nene basin, UK. Specifically, fingerprinting was undertaken on lake, reservoir and floodplain sediment cores, on actively transported suspended sediment and on overbank and channel bed sediment deposits. Tracer groups were investigated both alone and in combination to determine the differences between their sediment provenance predictions and potential causes of these differences. Additionally, simple organic and particle size corrections were applied to determine if they improve the agreement between the tracer group predictions. Key results showed that when fingerprinting contributions from channel banks to actively transported or recently deposited sediments the tracer group predictions varied by 24% on average. These differences could not be clearly attributed to changes in the sediment during erosion or transport. Instead, the most likely cause of differences was the pre-existing spatial variability in tracer concentrations within sediment sources, combined with highly localised erosion. This resulted in the collected sediment source samples not being representative of the actual sediment sources. Average differences in provenance predictions between the different tracer groups in lake, reservoir and floodplain sediment cores were lowest in the reservoir core at 19% and highest in some floodplain cores, with differences in predictions in excess of 50%. In these latter samples organic enrichment of the sediment, selective transport of fine particles and post-depositional chemical changes to the sediment were determined to be the likely cause of the differences. It was determined that organic and particle size corrections made the differences between tracer groups larger in most cases, although differences between tracer group predictions were reduced in two of the four floodplain cores.

Evaluating the provenance of fine sediment in degraded Freshwater Pearl Mussel habitats.

NASA Astrophysics Data System (ADS)

Blake, Will; Haley, Steve; Goddard, Rupert; Stone, Peter; Broadhead, Kat

2015-04-01

Freshwater Pearl Mussels (FWPM), Margaritifera margaritifera, are among the most critically threatened freshwater bivalves worldwide. In addition to their important roles in particle processing, nutrient release, and sediment mixing, they also serve as an ideal target species for evaluation of aquatic ecosystem functioning especially in the context of their symbiotic relationship with Atlantic salmon Salmo salar and brown or sea trout Salmo trutta. Poor water quality, particularly eutrophication, and siltation are considered major contributory factors in the decline of the species hence management of diffuse water pollution from agriculture (DWPA) is a key priority in catchments that host FWPM habitats. Against this background, this study adopted a combined monitoring, surveying and sediment fingerprinting approach to determine the principal sources of fine sediment impacting FWPM habitats in the River Clun, a Special area of Conservation (SAC) for FWPMs in central western UK. Potential sediment production hotspot areas in the ca 200 km2 catchment area upstream of FWPM habitats were initially evaluated using the SCIMAP risk mapping tool. Suspended sediment monitoring was undertaken on the main stem channel where FWPM habitats are located and wet weather catchment walkover surveys undertaken along the upstream river and stream network. Within this monitoring framework, sediment fingerprinting was undertaken at two levels. The first level aimed to link primary catchment sources (cultivated and uncultivated soil, channel bank erosion, and material transported via roads and tracks) to suspended sediment output from each main tributary upstream of the FWPM beds. The second level linked silt in the FWMP beds to the main tributaries, as integrated source end-members, with the inclusion of main channel bank erosion, a notable feature of walkover surveys as an additional source. Geochemical fingerprints, determined by XRF spectroscopy, were dominated by conservative mineral-bound elements and results indicated the importance of mainstem channel bank erosion as a sediment source to the FWMP beds, in line with catchment walkover observations. In addition, broad subcatchment discrimination and subsequent sediment apportionment showed agreement with SCIMAP risk analysis for more intensively farmed areas. Fingerprinting results also suggested, however, an unexpected contribution from upland grazed areas, categorised as lower risk by SCIMAP. Detailed evaluation of primary sources in these areas was undertaken to evaluate this discrepancy and test the hypothesised importance of channel bank erosion at the subcatchment scale. The results highlight the benefits of adopting a combined monitoring, modelling and tracing approach to support targeted management of fine sediment problems. .

Using Elemental Abundances and Petrophysical Properties to Trace Sediment Transport in the Hudson River

NASA Astrophysics Data System (ADS)

Chang, C.; Kenna, T. C.; Nitsche, F. O.

2016-12-01

The IPCC predicts that the frequency and severity of storms worldwide will increase due to climate change, a growing concern for the highly populated coastal areas near the Hudson River estuary. Storms have the potential to change the river's sediment budget, and it is necessary to update the current understanding of the effect of storms on sediment dynamics. In 2011, Tropical Storm Lee and Hurricane Irene delivered over 2.7 million tons of sediment to the Hudson River including over 1.5 million tons from the Mohawk River, a freshwater tributary, in addition to record amounts contributed from other major tributaries. The goals of this project are to use sediment elemental compositions to trace the major tributaries contributing to this storm-deposited sediment and to determine where sediment is accumulating as a result of storm activity. Chemical analysis of over 800 archived sediment samples are compiled to provide a pre-storm background level. These samples are compared to newly deposited sediment and material from specific tributaries. Elemental abundances (K, Ca, Ti, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Zr, Pb, and U) are measured using a field portable X-Ray Fluorescence (XRF) unit and core scanning XRF unit. Bulk matrix density is measured using a pycnometer. The measurements are used to identify elemental signatures from tributary sediment and to trace the influence of specific tributaries on deposition through the river. Our results suggests measureable signatures in sediment from individual tributaries. The Mohawk River contributes high concentrations of Ca due to the calcite deposits in its watershed. XRF measurements also show the effect of human activity on sediment deposition; variations in Rb and Zr indicate changes in deposition due to dredging in Haverstraw Bay. The salt wedge front, where ocean and fresh water meets is evident in areas of below average matrix density. This project shows significant geochemical variability between sediment from different areas of the river, and indicates that XRF can be used to track sediment sources and deposition.

Origins of etioporphyrins in sediments - Evidence from stable carbon isotopes

NASA Technical Reports Server (NTRS)

Boreham, Christopher J.; Fookes, Christopher J. R.; Popp, Brian N.; Hayes, J. M.

1989-01-01

In samples of the Julia Creek and Condor oil shales (Australia, Albian, and early Tertiary, respectively) etioporphyrin III is significantly depleted in C-13 (4 per mil) relative to porphyrins derived from chlorophylls. This isotopic difference suggests a large contribution from some independent source. The haem group found in cytochromes derived from microbial sources is the most likely candidate.

VARIABILITY IN THE DISTRIBUTION OF LIPID BIOMARKERS AND THEIR MOLECULAR ISOTOPIC COMPOSITION IN ALTAMAHA ESTUARINE SEDIMENTS: IMPLICATIONS FOR THE RELATIVE CONTRIBUTION OF ORGANIC MATTER FROM VARIOUS SOURCES

EPA Science Inventory

The estuarine mixing zone is an effective trap for particulate and dissolved organic matter From many sources, and thus greatly affects transport and deposition of organic matter between the land and ocean. This study examined sedimentary distributions of various fatty acids and ...

Contribution of the upper river, the estuarine region, and the adjacent sea to the heavy metal pollution in the Yangtze Estuary.

PubMed

Yin, Su; Wu, Yuehan; Xu, Wei; Li, Yangyang; Shen, Zhenyao; Feng, Chenghong

2016-07-01

To determine whether the discharge control of heavy metals in the Yangtze River basin can significantly change the pollution level in the estuary, this study analyzed the sources (upper river, the estuarine region, and the adjacent sea) of ten heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) in dissolved and particulate phases in the surface water of the estuary during wet, normal, and dry seasons. Metal sources inferred from section fluxes agree with those in statistical analysis methods. Heavy metal pollution in the surface water of Yangtze Estuary primarily depends on the sediment suspension and the wastewater discharge from estuary cities. Upper river only constitutes the main source of dissolved heavy metals during the wet season, while the estuarine region and the adjacent sea (especially the former) dominate the dissolved metal pollution in the normal and dry seasons. Particulate metals are mainly derived from sediment suspension in the estuary and the adjacent sea, and the contribution of the upper river can be neglected. Compared with the hydrologic seasons, flood-ebb tides exert a more obvious effect on the water flow directions in the estuary. Sediment suspension, not the upper river, significantly affects the suspended particulate matter concentration in the estuary. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of heavy metals contamination in sediments from three adjacent regions of the Yellow River using metal chemical fractions and multivariate analysis techniques.

PubMed

Ma, Xiaoling; Zuo, Hang; Tian, Mengjing; Zhang, Liyang; Meng, Jia; Zhou, Xuening; Min, Na; Chang, Xinyuan; Liu, Ying

2016-02-01

Metal chemical fractions obtained by optimized BCR three-stage extraction procedure and multivariate analysis techniques were exploited for assessing 7 heavy metals (Cr, Pb, Cd, Co, Cu, Zn and Ni) in sediments from Gansu province, Ningxia and Inner Mongolia Autonomous Regions of the Yellow River in Northern China. The results indicated that higher susceptibility and bioavailability of Cr and Cd with a strong anthropogenic source were due to their higher availability in the exchangeable fraction. A portion of Pb, Cd, Co, Zn, and Ni in reducible fraction may be due to the fact that they can form stable complexes with Fe and Mn oxides. Substantial amount of Pb, Co, Ni and Cu was observed as oxidizable fraction because of their strong affinity to the organic matters so that they can complex with humic substances in sediments. The high geo-accumulation indexes (I(geo)) for Cr and Cd showed their higher environmental risk to the aquatic biota. Principal component analysis (PCA) revealed that high toxic Cr and Cd in polluted sites (Cd in S10, S11 and Cr in S13) may be contributed to anthropogenic sources, it was consistent with the results of dual hierarchical clustering analysis (DHCA), which could give more details about contributing sources. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluvial sediment in the environment: a national challenge

USGS Publications Warehouse

Larsen, Matthew C.; Gellis, Allen C.; Glysson, G. Douglas; Gray, John R.; Horowitz, Arthur J.

2010-01-01

Sediment and sediment-associated constituents can contribute substantially to water-quality impairment. In the past, sediment was viewed mainly as an engineering problem that affected reservoir storage capacity, shipping channel maintenance, and bridge scour, as well as the loss of agricultural soil. Sediment is now recognized as a major cause of aquatic system degradation in many rivers and streams as a result of light attenuation, loss of spawning substrate due to fine-grained sediment infilling, reduction in primary productivity, decreases in biotic diversity, and effects from sediment-associated chemical constituents. Recent advances in sediment measurement, assessment, source-identification, and analytical protocols provide new capabilities to quantify sediment and solid-phase chemical fluxes in aquatic systems. Developing, maintaining, and augmenting current sediment- and water-quality-monitoring networks is essential for determining the health of U.S. waterways and for evaluating the effectiveness of management actions in reducing sediment-related problems. The application of new scientific capabilities that address the adverse effects of sediment and sediment- associated constituents represents a major step in managing the Nation’s water quality. A robust Federal, national-scale eff rt, in collaboration with vested stakeholders, is needed to address these sediment-related water-quality issues across the United States.

Heavy minerals in the 2011 Tohoku-oki tsunami deposits—insights into sediment sources and hydrodynamics

NASA Astrophysics Data System (ADS)

Jagodziński, Robert; Sternal, Beata; Szczuciński, Witold; Chagué-Goff, Catherine; Sugawara, Daisuke

2012-12-01

The 2011 Tohoku-oki tsunami left sand and mud deposits more than 4 km inland on the coastal plain of Sendai, Japan. The tsunami deposits, pre-tsunami soils and beach sediments were analysed for grain size, and heavy mineral content and assemblages to test the applicability of heavy mineral analyses in the identification of tsunami deposits and interpretation of associated sedimentation processes. Heavy minerals comprised on average 35% of the tsunami deposit in the 0.125-0.25 mm grain size fraction. The most common were orthopyroxenes, clinopyroxenes, amphiboles, limonites and opaque minerals. Heavy mineral concentrations and assemblages were similar in the tsunami deposits, beach and pre-tsunami soils and sediments and thus tsunami deposits could not simply be identified based on their heavy minerals. Sediment provenance analysis revealed that tsunami deposits left within 1.5 km of the shoreline were mostly eroded from the beach, dune and local soils, while deposits farther inland (> 1.5 km) were mostly derived from local soil erosion. No evidence was found for a significant contribution of offshore sediments. Detailed analyses revealed that the lowermost portion of tsunami deposits was mostly of local origin, while the sediment source of the upper portion was variable. A comparison with a previous study of heavy minerals in 2004 IOT deposits confirms that heavy minerals in tsunami deposits are mostly source-dependent and may represent a useful supplementary tool in studies of tsunami deposits. However, the interpretation must always be placed in the local geological context and corroborated with other "tsunami proxies".

Environmental characteristics and changes of sediment pore water dissolved organic matter in four Chinese lakes.

PubMed

Mostofa, Khan M G; Li, Wen; Wu, Fengchang; Liu, Cong-Qiang; Liao, Haiqing; Zeng, Li; Xiao, Min

2018-01-01

Sediment pore waters were examined in four Chinese lakes (Bosten, Qinghai, Chenghai and Dianchi) to characterise the sources of dissolved organic matter (DOM) and their microbial changes in the sediment depth profiles. Parallel factor (PARAFAC) modelling on the sample fluorescence spectra confirmed that the pore water DOM was mostly composed of two components with a mixture of both allochthonous and autochthonous fulvic acid-like substances in three lakes, except Lake Dianchi, and protein-like components in Lake Bosten. However, DOM in Lake Dianchi was composed of three components, including a fulvic acid-like, and two unidentified components, which could originate from mixed sources of either sewerage-impacted allochthonous or autochthonous organic matter (OM). Dissolved organic carbon (DOC) concentrations were typically high (583-7410 μM C) and fluctuated and increased vertically in the depth profile. The fluorescence intensity of the fulvic acid-like substance and absorbance at 254 nm increased vertically in the sediment pore waters of three lakes. A significant relationship between DOC and the fluorescence intensity of the fulvic acid-like component in the sediment pore waters of three lakes, except Lake Dianchi, suggested that the fulvic acid-like component could significantly contribute to total DOM and could originate via complex microbial processes in early diagenesis on OM (ca. phytoplankton, terrestrial plant material) in these lakes. Pore water DOM components could therefore be a useful indicator to assess the DOM sources of the lake sediment during sedimentation over the past several decades, which have been heavily affected by ambient terrestrial vegetation and human activities.

Iron and nutrient content of wind-erodible sediment in the ephemeral river valleys of Namibia

NASA Astrophysics Data System (ADS)

Dansie, A. P.; Wiggs, G. F. S.; Thomas, D. S. G.

2017-08-01

Research concerning the global distribution of aeolian dust sources has principally focussed on salt/clay pan and desiccated lacustrine emission areas. In southern Africa such sources are identified as Etosha Pan in northern Namibia and Makgadikgadi Pans in northern Botswana. Dust emitting from ephemeral river valleys, however, has been largely overlooked. Rivers are known nutrient transport pathways and the flooding regimes of ephemeral river valleys frequently replenish stores of fine sediment which, on drying, can become susceptible to aeolian erosion. Such airborne sediment may be nutrient rich and thus be significant for the fertilisation of marine waters once deposited. This study investigates the dust source sediments from three ephemeral river valleys in Namibia in terms of their particle size distribution and their concentrations of bioavailable N, P and Fe. We compare the nutrient content of these sediments from the ephemeral river valleys to those collected from Etosha and Makgadikgadi Pans and consider their relative ocean fertilising potential. Our results show that the ephemeral river valleys contain fine grained sediment similar in physical character to Etosha and Makgadikgadi Pans yet they have up to 43 times greater concentrations of bioavailable iron and enriched N and P macronutrients that are each important for ocean fertilisation. The known dust-emitting river valleys of Namibia may therefore be contributing a greater fertilisation role in the adjacent marine system than previously considered, and not-yet investigated. Given this finding a re-assessment of the potential role of ephemeral river valleys in providing nutrient-rich sediment into the aeolian and marine systems in other dryland areas is necessary.

Evaluating the importance of faecal sources in human-impacted waters.

PubMed

Schoen, Mary E; Soller, Jeffrey A; Ashbolt, Nicholas J

2011-04-01

Quantitative microbial risk assessment (QMRA) was used to evaluate the relative contribution of faecal indicators and pathogens when a mixture of human sources impacts a recreational waterbody. The waterbody was assumed to be impacted with a mixture of secondary-treated disinfected municipal wastewater and untreated (or poorly treated) sewage, using Norovirus as the reference pathogen and enterococci as the reference faecal indicator. The contribution made by each source to the total waterbody volume, indicator density, pathogen density, and illness risk was estimated for a number of scenarios that accounted for pathogen and indicator inactivation based on the age of the effluent (source-to-receptor), possible sedimentation of microorganisms, and the addition of a non-pathogenic source of faecal indicators (such as old sediments or an animal population with low occurrence of human-infectious pathogens). The waterbody indicator density was held constant at 35 CFU 100 mL(-1) enterococci to compare results across scenarios. For the combinations evaluated, either the untreated sewage or the non-pathogenic source of faecal indicators dominated the recreational waterbody enterococci density assuming a culture method. In contrast, indicator density assayed by qPCR, pathogen density, and bather gastrointestinal illness risks were largely dominated by secondary disinfected municipal wastewater, with untreated sewage being increasingly less important as the faecal indicator load increased from a non-pathogenic source. The results support the use of a calibrated qPCR total enterococci indicator, compared to a culture-based assay, to index infectious human enteric viruses released in treated human wastewater, and illustrate that the source contributing the majority of risk in a mixture may be overlooked when only assessing faecal indicators by a culture-based method. Published by Elsevier Ltd.

The contribution of sediment from forested areas of the Chesapeake Bay Watershed

NASA Astrophysics Data System (ADS)

Gellis, A.; Brakebill, J.

2012-12-01

Fine-grained sediment is a major pollutant in the Chesapeake Bay and its receiving waters. Sediment budget studies have been conducted in small basins draining to the Bay over the last decade to understand the important sources of fine-grained sediment, quantify erosion rates, and determine sediment yields. Sediment budget approaches include modeling (SPARROW), sediment fingerprinting, and quantifying upland rates of erosion (Cesium-137). SPARROW model results indicate that forests deliver between 2 to 8% of the total sediment to the Bay. Sediment-fingerprinting results from small watershed studies indicate that forests contribute between 13 to 29 % of the sediment. The Cesium-137 technique was used to quantify soil redistribution (erosion and deposition) rates for forested areas in the Linganore Creek (146 km2) watershed which drains the Piedmont Physiographic Province. Average forest erosion rates measured in 2009 for Linganore Creek using Cesium-137 were 2.6 t/ha/yr. With 27% of the Linganore Creek watershed in forest, over 10,300 may be eroded off of forested lands which is more than the average annual suspended-sediment load (8,050 Mg/yr) in Linganore Creek, indicating that much of the eroded forest sediment goes in storage. Most of the forested areas in the Chesapeake Bay watershed were cut down for agriculture between the time of European colonization and the early 20th Century. In the late 20th century forested lands show an increase in areal extent. Although studies have not been conducted to understand why these secondary growth forests are eroding, it may involve that these forests have not fully recovered from deforestation. Soil profiles are thin, and runoff and sediment relations may have been altered, leading to high rates of erosion.

A catchment-integrated approach to determine the importance of secondary sources of contaminated sediment

NASA Astrophysics Data System (ADS)

Andres Lopez-Tarazon, Jose; Byrne, Patrick; Mullan, Donal; Smith, Hugh

2015-04-01

Water pollution has been identified as one of the most important environmental challenges of the early 21st Century. The Water Framework Directive (WFD) (2008/105/EC) explicitly recognises the risk to water resources posed by sediment-associated contaminants in European river basins. The potential impacts on water supply and the biodiversity of aquatic ecosystems from sediment and associated contaminants may be further exacerbated by climate change pressures on water resources, as highlighted in the 2009 EU White Paper "Adapting to climate change: Towards a European framework for action" (SEC(2009) 386, 387, 388). Despite these concerns, the role of floodplains and other storage areas as secondary sources of contaminated sediment (i.e. metals) in river basins affected by historic industrial or mining pollution has been largely overlooked. Thereby, besides the sediment which is transported by the river, secondary sources of contaminants represent a credible threat to achieving EU water quality targets set by the WFD. This project addresses this issue by developing a catchment-based approach looking at metal geochemistry from source to sink (i.e., from sediment generation at slopes, passing through sediment transported by the river system, to sediment deposition at the storage areas to the outlet) and develop a geochemical model to predict the chemical aspects of metals transport and transformation. This approach will allow us to quantify (i) the sediment fluxes and associated contaminants flowing through the river, (ii) the storage areas contributions to downstream contaminated sediment fluxes, (ii) the timescales for the storage and removal of contaminated sediment in the sinks, and (iv) the transformation and bioavailability of the pollutants (i.e. metals) along the basin. Both physical and chemical aspects of metal transport will be considered by looking at metal geochemistry, mobility and bioavailability, hence producing information on chemical metal transport and transformation from source to sink. Different metal species rather than bulk metals will be investigated providing information on potential metal mobility (and what environmental processes might force mobility) and bioavailability. Biological work (i.e. macroinvertebrates samplings, PCA and CCA techniques) will also carried out to apply contaminant-ecosystem models and determine the affectation of pollutants over the biology/ecology. Finally, catchment-based hydro-sedimentological models will be applied to study how different global-change scenarios could alter sediment (and hence) metals transport. This way, present work will generate better understanding of the environmental risk derived from sediment mobility in contaminated systems, a critical information which will provide river basin managers with the means to assess the potential impact of the secondary sources of water pollution in European rivers.

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

PubMed Central

Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

2018-01-01

In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere. PMID:29349299

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf

USGS Publications Warehouse

Sparrow, Katy J.; Kessler, John D.; Southon, John R.; Garcia-Tigreros, Fenix; Schreiner, Kathryn M.; Ruppel, Carolyn D.; Miller, John B.; Lehman, Scott J.; Xu, Xiaomei

2018-01-01

In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

Geochemical compositions of Neoproterozoic to Lower Palaeozoic (?) shales and siltstones in the Volta Basin (Ghana): Constraints on provenance and tectonic setting

NASA Astrophysics Data System (ADS)

Amedjoe, Chiri G.; Gawu, S. K. Y.; Ali, B.; Aseidu, D. K.; Nude, P. M.

2018-06-01

Many researchers have investigated the provenance and tectonic setting of the Voltaian sediments using the geochemistry of sandstones in the basin. The shales and siltstones in the basin have not been used much in the provenance studies. In this paper, the geochemistry of shales and siltstones in the Kwahu Group and Oti Group of the Voltaian Supergroup from Agogo and environs in the southeastern section of the basin has constrained the provenance and tectonic setting. Trace element ratios La/Sc, Th/Sc and Cr/Th and REEs sensitive to average source compositions revealed sediments in the shales and siltstones may mainly be from felsic rocks, though contributions from old recycled sediments and some andesitic rock sediments were identified. The felsic rocks may be granites and/or granodiorites. Some intermediate rocks of andesitic composition are also identified, while the recycled sediments were probably derived from the basement metasedimentary rocks. The enrichment of light REE (LaN/YbN c. 7.47), negative Eu anomalies (Eu/Eu* c. 0.59), and flat heavy REE chondrite-normalized patterns, denote an upper-continental-crustal granitic source materials for the sediments. Trace-element ternary discriminant diagrams reveal passive margin settings for sediments, though some continental island arc settings sediments were also depicted. Mixing calculations based on REE concentrations and modeled chondrite-normalized REE patterns suggest that the Birimian basement complex may be the source of detritus in the Voltaian Basin. REEs are more associated with shales than siltstones. On this basis chondrite-normalized REE patterns show that shale lithostratigraphic units may be distinguished from siltstone lithostratigraphic units. The significant variability in shales elemental ratios can therefore be used to distinguish between shales of the Oti Group from that of the Kwahu Group.

Terrigenous helium in deep-sea sediments

NASA Astrophysics Data System (ADS)

Marcantonio, Franco; Higgins, Sean; Anderson, Robert F.; Stute, Martin; Schlosser, Peter; Rasbury, E. Troy

1998-05-01

We have measured the isotope ratios of helium contained in various terrigenous materials that contribute to deep-sea sediments. These materials include ice-rafted debris from the North Atlantic, Chinese Loess, and sediment collected at or near the mouths of three large rivers: the Amazon, the Ganges, and the Yangtze. We observe terrigenous 3He/ 4He ratios that vary from 1.8 × 10 -9 to 4.6 × 10 -7, i.e., values that are higher than the theoretically-derived range of 10 -9 to 10 -8. Atlantic and Pacific deep-sea sediment 3He/ 4He ratios can be explained by mixing of helium from similar extraterrestrial but different terrigenous sources. Terrigenous sources for North Atlantic and North Pacific sediments are characterized by 3He and 4He contents that are higher, and 3He/ 4He ratios that are lower, than those for central and eastern equatorial Pacific sediments. This is consistent with the supply to the North Atlantic and North Pacific oceans of older cratonic continental material that contains high amounts of in situ-produced nucleogenic and radiogenic helium. Terrigenous material transported to central and eastern equatorial Pacific sediments contains lower amounts of 3He and 4He and higher 3He/ 4He ratios, indicative of supply from a more juvenile Andean source. In the equatorial Atlantic (core V31-135), we have used previously-published 230Th data to determine an extraterrestrial 3He flux of (1.16 ± 0.15) × 10 -12 cm 3STP · cm -2 · ka -1, within error of that previously determined in sediments from the equatorial Pacific Ocean ([0.78 ± 0.29] × 10 -13 cm 3STP · cm -2 · ka -1; Marcantonio et al., 1996).

Quantifying the sources and the transit times of sediment using fallout radionuclides (7Be, 137Cs, 210Pbxs) in contrasted cultivated catchments across the world

NASA Astrophysics Data System (ADS)

Evrard, O.; Le Gall, M.; Laceby, J. P.; Foucher, A.; Lefèvre, I.; Salvador-Blanes, S.; Morera, S.; Ribolzi, O.

2017-12-01

Soil erosion and fine sediment supply to rivers are exacerbated in intensively cultivated catchments. Information on the sediment sources and transit times in rivers is required to improve our understanding of these processes and to guide the implementation of effective conservation measures. Accordingly, natural (7Be, 210Pb) and artificial (137Cs) fallout radionuclide concentrations were measured in overland flow and suspended sediment collected during the erosive season in contrasted cultivated catchments. In Laos, samples were collected in a steep catchment (Houay Pano, 12 km²) covered with cropland and teak plantations during the first flood of the monsoon in 2014. Cropland surface sources dominated the supply of sediment at the upstream sampling location (55%), whereas subsurface sources (channel, landslides) contributed the majority of material at the outlet (60%). Furthermore, the material exported from the catchment mainly consisted of re-suspended sediment. In Central France, the study was conducted in a flat and drained cultivated catchment (Louroux, 25 km²) during a sequence of winter events in 2013-2014 and 2016. Only surface material enriched in 137Cs was found to transit through the river during floods. The results demonstrated the initial re-suspension of material accumulated in the river channel during the first winter flood before the direct supply of sediment recently eroded from the hillslopes during the next events. In Peru, sediment was collected during a series of summer flood events (2017) in a river draining páramos (Ronquillo, 42 km²) that were recently put in cultivation. Preliminary results show that subsurface re-suspended material dominates the exports from this catchment. These results confirmed the utility of coupling continuous river monitoring and fallout radionuclide measurements on sediment collected in both tropical and temperate rivers to better understand sediment dynamics in these endangered habitats. The main challenges for the future application of this technique are related to the availability of detectors to analyze a large set of samples rapidly after collection, as well as the access to ultra-low background gamma spectrometry facilities.

Importance of clay size minerals for Fe(III) respiration in a petroleum-contaminated aquifer

USGS Publications Warehouse

Shelobolina, Evgenya S.; Anderson, Robert T.; Vodyanitskii, Yury N.; Sivtsov, Anatolii V.; Yuretich, Richard; Lovely, Derek R.

2004-01-01

The availability of Fe(III)-bearing minerals for dissimilatory Fe(III) reduction was evaluated in sediments from a petroleum-contaminated sandy aquifer near Bemidji, Minnesota (USA). First, the sediments from a contaminated area of the aquifer, in which Fe(III) reduction was the predominant terminal electron accepting process, were compared with sediments from a nearby, uncontaminated site. Data from 0.5 m HCl extraction of different size fractions of the sediments revealed that the clay size fraction contributed a significant portion of the ‘bio-available’ Fe(III) in the background sediment and was the most depleted in ‘bio-available’ Fe(III) in the iron-reducing sediment. Analytical transmission electron microscopy (TEM) revealed the disappearance of thermodynamically unstable Fe(III) and Mn(IV) hydroxides (ferrihydrite and Fe vernadite), as well as a decrease in the abundance of goethite and lepidocrocite in the clay size fraction from the contaminated sediment. TEM observations and X-ray diffraction examination did not provide strong evidence of Fe(III)-reduction-related changes within another potential source of ‘bio-available’ Fe(III) in the clay size fraction – ferruginous phyllosilicates. However, further testing in the laboratory with sediments from the methanogenic portion of the aquifer that were depleted in microbially reducible Fe(III) revealed the potential for microbial reduction of Fe(III) associated with phyllosilicates. Addition of a clay size fraction from the uncontaminated sediment, as well as Fe(III)-coated kaolin and ferruginous nontronite SWa-1, as sources of poorly crystalline Fe(III) hydroxides and structural iron of phyllosilicates respectively, lowered steady-state hydrogen concentrations consistent with a stimulation of Fe(III) reduction in laboratory incubations of methanogenic sediments. There was no change in hydrogen concentration when non-ferruginous clays or no minerals were added. This demonstrated that Fe(III)-bearing clay size minerals were essential for microbial Fe(III) reduction and suggested that both potential sources of ‘bio-available’ Fe(III) in the clay size fraction, poorly crystalline Fe(III) hydroxides and structural Fe(III) of phyllosilicates, were important sources of electron acceptor for indigenous iron-reducing microorganisms in this aquifer.

Influence of the Portuguese Bend landslide on the character of the effluent-affected sediment deposit, Palos Verdes margin, southern California

USGS Publications Warehouse

Kayen, R.E.; Lee, H.J.; Hein, J.R.

2002-01-01

Historic accretion of sediment on the Palos Verdes margin off Los Angeles County, CA, is dominated by two sources, effluent from Whites Point outfall and sediment eroded from the toe of Portuguese Bend landslide. In this paper, we document the recent history of sedimentation from these non-marine sources from 1937 until the late 1990s, and attempt to estimate the amount of material preserved on the shelf. Toward that end, we characterized offshore sediment by physical and geotechnical testing, using non-destructive gamma-ray whole-core logging techniques and conventional geotechnical strength tests, and X-ray diffraction. Results are reported within a geographic information system framework that allows for: (1) the evaluation of the spatial variability of the measured properties, and (2) assessment of the influence of these properties on processes affecting the effluent-affected Sediment layer. In the inner shelf, material eroded by wave action from the toe of the Portuguese Bend landslide since 1956 has contributed 5.7-9.4 million metric tons (Mmt) of sediment, from a total eroded mass of 12.1 Mmt. A lesser fraction (???2.7Mmt) of sediment is incorporated into the mid- and outer-shelf effluent-affected sediment layer. Evidence from X-ray diffractograms clearly indicates that landslide material has mixed with the mid- and outer-shelf effluent. From 1937-1987, it is estimated that 3.8 Mmt of solid anthropogenic effluent was discharged into the water column and onto the Palos Verdes Shelf.

Subsoil erosion dominates the supply of fine sediment to rivers draining into Princess Charlotte Bay, Australia.

PubMed

Olley, Jon; Brooks, Andrew; Spencer, John; Pietsch, Timothy; Borombovits, Daniel

2013-10-01

The Laura-Normanby River (catchment area: 24,350 km(2)), which drains into Princess Charlotte Bay, has been identified in previous studies as the third largest contributor of sediment to the Great Barrier Reef World Heritage Area. These catchment scale modelling studies also identified surface soil erosion as supplying >80% of the sediment. Here we use activity concentrations of the fallout radionuclides (137)Cs and (210)Pbex to test the hypothesis that surface soil erosion dominates the supply of fine (<10 μm) sediment in the river systems draining into Princess Charlotte Bay. Our results contradict these previous studies, and are consistent with channel and gully erosion being the dominant source of fine sediment in this catchment. The hypothesis that surface soil erosion dominates the supply of fine sediment to Princess Charlotte Bay is rejected. River sediment samples were collected using both time-integrated samplers and sediment drape deposits. We show that there is no detectable difference in (137)Cs and (210)Pbex activity concentrations between samples collected using these two methods. Two methods were also used to collect samples to characterise (137)Cs and (210)Pbex concentrations in sediment derived from surface soil erosion; sampling of surface-wash deposits and deployment of surface runoff traps that collected samples during rain events. While there was no difference in the (137)Cs activity concentrations for samples collected using these two methods, (210)Pbex activity concentrations were significantly higher in the samples collected using the runoff traps. The higher (210)Pbex concentrations are shown to be correlated with loss-on-ignition (r(2) = 0.79) and therefore are likely to be related to higher organic concentrations in the runoff trap samples. As a result of these differences we use a three end member mixing model (channel/gully, hillslope surface-wash and hillslope runoff traps) to determine the relative contribution from surface soil erosion. Probability distributions for (137)Cs and (210)Pbex concentrations were determined for each of the end members, with these distributions then used to estimate the surface soil contribution to each of the collected river sediment samples. The mean estimate of contribution of surface derived sediment for all river samples (n = 70) is 16 ± 2%. This study reinforces the importance of testing model predictions before they are used to target investment in remedial action and adds to the body of evidence that the primary source of sediment delivered to tropical river systems is derived from subsoil erosion. Copyright © 2013 Elsevier Ltd. All rights reserved.

Direct atmospheric deposition of 210Pb to rivers determined through 210Pb (210Po) disequilibrium and implications to sediment source apportionment

NASA Astrophysics Data System (ADS)

Blumentritt, D. J.; Shottler, S.; Engstrom, D. R.

2011-12-01

Atmospheric radioisotopes such as 210Pb can be an effective tool for determining sediment source types in rivers and streams. Pb-210 is ubiquitous in deposition from atmospheric washout and is highly particle reactive, so sediments derived from a surface with prolonged exposure to rainfall, such as farm fields, are enriched in atmospheric 210Pb. Conversely, sediment sources that are not readily exposed to rainfall (i.e. streambanks) are absent of any appreciable 210Pb. Many sediment source apportionment studies have used 210Pb to quantify the proportion of sediment loads from the two source types, field and non-field. These studies, however, primarily take place in smaller watersheds where 210Pb that falls directly onto the surface of the water is assumed negligible. Lake Pepin is a riverine lake located in southeastern Minnesota with a 122,000 km2 watershed composed of three major rivers, the Minnesota, headwaters Mississippi, and St. Croix. The sediment load in Lake Pepin has increased by an order of magnitude since Euro-American settlement in the region. Most of the sediment (>80%) is transported to Lake Pepin from the highly agricultural Minnesota River basin. Extensive sediment fingerprinting work has been done on Lake Pepin sediments, but a source of significant uncertainty still exists: How much of the 210Pb measured in Lake Pepin is directly deposited to the surface of the contributing water bodies and did not enter on eroded particles? To answer this important question, we have developed a method to quantify the amount of directly deposited 210Pb. Alpha spectrometry is used to measure 210Po, a daughter product of 210Pb decay. Because 210Po has a short half-life (138 days), it takes approximately one year to reach equilibrium with 210Pb on sediment particles. If deposition of 210Pb directly from the atmosphere to the water surface is significant, there will be disequilibrium between the two radioisotopes and the activity of 210Po will increase as an inverse exponential function, with respect to time, following sample collection. The magnitude of this increase is the amount of directly deposited 210Pb. Samples were collected at four locations, corresponding to gauging stations, on the Minnesota/Mississippi River system above Lake Pepin. Three measurements were made on each sample over the course of a year after collection. Based on those three measurements, the activity of 210Po was modeled for time zero and for the equilibrium concentration, revealing the amount of 210Pb from direct atmospheric deposition. These estimates were flow-weighted over the course of the year, providing a critical correction to the source apportionment model.

Origins of sediment-associated contaminants to the Marais Vernier, the Seine Estuary, France

USGS Publications Warehouse

Van Metre, P.C.; Mesnage, V.; Laignel, B.; Motelay, A.; Deloffre, J.

2008-01-01

The Marais Vernier is the largest freshwater wetland in the Seine Estuary in northern France. It is in a heavily urbanized and industrialized region and could be affected by atmospheric deposition and by fluvial input of contaminants in water diverted from the Seine River. To evaluate contaminant histories in the wetland and the region, sediment cores were collected from two open-water ponds in the Marais Vernier: the Grand-Mare, which was connected to the Seine by a canal from 1950 to 1996, and the Petite Mare, which has a small rural watershed. Diversions from the Seine to the Grand-Mare increased sedimentation rates but mostly resulted in low contaminant concentrations and loading rates, indicating that the sediment from the Seine was predominantly brought upstream by tidal currents from the estuary and was not from the watershed. Atmospheric sources of metals dominate inputs to the Petite Mare; however, runoff of metals from vehicle-related sources in the watershed might contribute to the upward trends in concentrations of Cr, Cu, and Zn. Estimates of atmospheric deposition using the Petite Mare core are consistent with measured deposition in the region and are mixed (similar for Hg and Pb; larger for Cd, Cu, and Zn) compared with deposition estimated from sediment cores in the northeastern United States. A local source of PAHs in the watershed of the Petite Mare is indicated by higher concentrations, higher accumulation rates, and a different, more petrogenic, PAH assemblage than in the Grand-Mare. The study illustrates how diverse sources and transport pathways can affect wetlands in industrial regions and can be evaluated using sediment cores from the wetland ponds. ?? 2008 Springer Science+Business Media B.V.

Determination and Distribution of Polycyclic Aromatic Hydrocarbons in Rivers, Sediments and Wastewater Effluents in Vhembe District, South Africa

PubMed Central

Edokpayi, Joshua N.; Odiyo, John O.; Popoola, Oluwaseun E.; Msagati, Titus A. M.

2016-01-01

Polycyclic aromatic hydrocarbons are very toxic and persistent environmental contaminants. This study was undertaken to assess the concentrations and possible sources of 16 PAHs (Polycyclic aromatic hydrocarbons) classified by the United State Environmental Protection Agency as priority pollutants in water and sediments of the Mvudi and Nzhelele Rivers. Effluents from Thohoyandou wastewater treatment plant and Siloam waste stabilization ponds were also investigated. Diagnostic ratios were used to evaluate the possible sources of PAHs. PAHs in the water samples were extracted using 1:1 dichloromethane and n-hexane mixtures, while those in the sediment samples were extracted with 1:1 acetone and dichloromethane using an ultrasonication method. The extracts were purified using an SPE technique and reconstituted in n-hexane before analyses with a gas chromatograph time of flight—mass spectrometer. The results obtained indicate the prevalence of high molecular weight PAHs in all the samples. PAHs concentrations in water and sediment samples from all the sampling sites were in the range of 13.174–26.382 mg/L and 27.10–55.93 mg/kg, respectively. Combustion of biomass was identified as the major possible source of PAHs. Effluents from wastewater treatment facilities were also considered as major anthropogenic contributions to the levels of PAHs found in both river water and sediments. Mvudi and Nzhelele Rivers show moderate to high contamination level of PAHs. PMID:27043597

Sedimentary organic matter sources, benthic consumption and burial in west Spitsbergen fjords - Signs of maturing of Arctic fjordic systems?

NASA Astrophysics Data System (ADS)

Zaborska, Agata; Włodarska-Kowalczuk, Maria; Legeżyńska, Joanna; Jankowska, Emilia; Winogradow, Aleksandra; Deja, Kajetan

2018-04-01

Mature ecosystems sequester little organic carbon (Corg) in sediments, as the complex and effective food webs consume most available organic matter within the water column and sediment, in contrast to young systems, where a large proportion of Corg is buried in deeper sediment layers. In this paper we hypothesize that "warmer" Atlantic water influenced fjord exhibits the 'mature' system features as compared to "cooler" Arctic water influenced fjord. Corg concentrations, sources and burial rates, as well as macrobenthic community standing stocks, taxonomic and functional composition and carbon demand, were compared in two west Spitsbergen fjords that are to different extents influenced by Atlantic water and can be treated as representing a cold one (Hornsund) and a warm one (Kongsfjorden). Water, sediments and macrofauna were collected at three stations in the central basin of each fjord. Corg, Ntot, δ13Corg and δ15N were measured in suspended matter, sediment cores and possible organic matter sources. The composition of sources of sedimentary organic matter was modeled by Mix-SIAR Bayesian stable isotope mixing models. The 210Pb method was used to calculate sediment accumulation rates, Corg accumulation and burial rates. The sedimentary Corg concentration and accumulation rate were larger in Hornsund than in Kongsfjorden. The contributions of pelagic sources to the Corg in sediments were similar in both fjords, macroalgal detritus had a higher importance in Kongsfjorden, while terrestrial sources were more important in Hornsund. Similar density and species richness were noted in both fjords, but higher biomass, individual biomass, production and carbon demand of benthic communities were noted in Kongsfjorden despite the lower amounts of Corg in sediments, indicating that macrobenthos responds to quality rather than quantity of available food. Subsurface tube-building conveyer belt detritus feeders (maldanids and oweniids) were responsible for higher standing stocks and carbon consumption in Kongsfjorden. As a result of the lower Corg pool and higher benthic mineralization, the burial rates in Kongsfjorden were much lower (15 g of Corg m- 2 yr- 1) than in Hornsund (38 g of Corg m- 2 yr- 1). Our study indicates that warming of the high latitude fjordic environments may reshape the relative proportions of organic carbon sources and induce maturing of the sea bottom systems, in terms of development of stable, biologically accommodated benthic communities which more efficiently mineralize organic matter and consequently lower sequestration of organic matter in deeper sediments.

Tracing crop-specific sediment sources in agricultural catchments

NASA Astrophysics Data System (ADS)

Blake, William H.; Ficken, Katherine J.; Taylor, Philip; Russell, Mark A.; Walling, Desmond E.

2012-02-01

A Compound Specific Stable Isotope (CSSI) sediment tracing approach is evaluated for the first time in an agricultural catchment setting against established geochemical fingerprinting techniques. The work demonstrates that novel CSSI techniques have the potential to provide important support for soil resource management policies and inform sediment risk assessment for the protection of aquatic habitats and water resources. Analysis of soil material from a range of crop covers in a mixed land-use agricultural catchment shows that the carbon CSSI signatures of particle-reactive fatty acids label surface agricultural soil with distinct crop-specific signatures, thus permitting sediment eroded from each land-cover to be tracked downstream. High resolution sediment sampling during a storm event and analysis for CSSI and conventional geochemical fingerprints elucidated temporal patterns of sediment mobilisation under different crop regimes and the specific contribution that each crop type makes to downstream sediment load. Pasture sources (65% of the catchment area) dominated the sediment load but areal yield (0.13 ± 0.02 t ha - 1 ) was considerably less than that for winter wheat (0.44 ± 0.15 t ha - 1 ). While temporal patterns in crop response matched runoff and erosion response predictions based on plot-scale rainfall simulation experiments, comparison of biomarker and geochemical fingerprinting data indicated that the latter overestimated cultivated land inputs to catchment sediment yield due to inability to discriminate temporary pasture (in rotation) from cultivated land. This discrepancy, however, presents an opportunity since combination of the two datasets revealed the extremely localised nature of erosion from permanent pasture fields in this system (estimated at up to 0.5 t ha - 1 ). The novel use of CSSI and geochemical tracers in tandem provided unique insights into sediment source dynamics that could not have been derived from each method alone. Research into CSSI signature development (plant and soil processes) and the influence of cultivation regimes are required to support future development of this new tool.

Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier

PubMed Central

Rime, Thomas; Hartmann, Martin; Frey, Beat

2016-01-01

Rapid disintegration of alpine glaciers has led to the formation of new terrain consisting of mineral debris colonized by microorganisms. Despite the importance of microbial pioneers in triggering the formation of terrestrial ecosystems, their sources (endogenous versus exogenous) and identities remain elusive. We used 454-pyrosequencing to characterize the bacterial and fungal communities in endogenous glacier habitats (ice, sub-, supraglacial sediments and glacier stream leaving the glacier forefront) and in atmospheric deposition (snow, rain and aeolian dust). We compared these microbial communities with those occurring in recently deglaciated barren soils before and after snow melt (snow-covered soil and barren soil). Atmospheric bacteria and fungi were dominated by plant-epiphytic organisms and differed from endogenous glacier habitats and soils indicating that atmospheric input of microorganisms is not a major source of microbial pioneers in newly formed soils. We found, however, that bacterial communities in newly exposed soils resembled those of endogenous habitats, which suggests that bacterial pioneers originating from sub- and supraglacial sediments contributed to the colonization of newly exposed soils. Conversely, fungal communities differed between habitats suggesting a lower dispersal capability than bacteria. Yeasts putatively adapted to cold habitats characteristic of snow and supraglacial sediments were similar, despite the fact that these habitats were not spatially connected. These findings suggest that environmental filtering selects particular fungi in cold habitats. Atmospheric deposition provided important sources of dissolved organic C, nitrate and ammonium. Overall, microbial colonizers triggering soil development in alpine environments mainly originate from endogenous glacier habitats, whereas atmospheric deposition contributes to the establishment of microbial communities by providing sources of C and N. PMID:26771926

Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier.

PubMed

Rime, Thomas; Hartmann, Martin; Frey, Beat

2016-07-01

Rapid disintegration of alpine glaciers has led to the formation of new terrain consisting of mineral debris colonized by microorganisms. Despite the importance of microbial pioneers in triggering the formation of terrestrial ecosystems, their sources (endogenous versus exogenous) and identities remain elusive. We used 454-pyrosequencing to characterize the bacterial and fungal communities in endogenous glacier habitats (ice, sub-, supraglacial sediments and glacier stream leaving the glacier forefront) and in atmospheric deposition (snow, rain and aeolian dust). We compared these microbial communities with those occurring in recently deglaciated barren soils before and after snow melt (snow-covered soil and barren soil). Atmospheric bacteria and fungi were dominated by plant-epiphytic organisms and differed from endogenous glacier habitats and soils indicating that atmospheric input of microorganisms is not a major source of microbial pioneers in newly formed soils. We found, however, that bacterial communities in newly exposed soils resembled those of endogenous habitats, which suggests that bacterial pioneers originating from sub- and supraglacial sediments contributed to the colonization of newly exposed soils. Conversely, fungal communities differed between habitats suggesting a lower dispersal capability than bacteria. Yeasts putatively adapted to cold habitats characteristic of snow and supraglacial sediments were similar, despite the fact that these habitats were not spatially connected. These findings suggest that environmental filtering selects particular fungi in cold habitats. Atmospheric deposition provided important sources of dissolved organic C, nitrate and ammonium. Overall, microbial colonizers triggering soil development in alpine environments mainly originate from endogenous glacier habitats, whereas atmospheric deposition contributes to the establishment of microbial communities by providing sources of C and N.

Source identification and ecological impact evaluation of PAHs in urban river sediments: A case study in Taiwan.

PubMed

Tu, Y T; Ou, J H; Tsang, D C W; Dong, C D; Chen, C W; Kao, C M

2018-03-01

The Love River and Ho-Jin River, two major urban rivers in Kaohsiung City, Taiwan, are moderately to heavily polluted because different types of improperly treated wastewaters are discharged into the rivers. In this study, sediment and river water samples were collected from two rivers to investigate the river water quality and accumulation of polycyclic aromatic hydrocarbons (PAHs) in sediments. The spatial distribution, composition, and source appointment of PAHs of the sediments were examined. The impacts of PAHs on ecological system were assessed using toxic equivalence quotient (TEQ) of potentially carcinogenic PAHs (TEQ carc ) and sediment quality guidelines. The average PAHs concentrations ranged from 2161 ng/g in Love River sediment to 160 ng/g in Ho-Jin River sediment. This could be due to the fact that Love River Basin had much higher population density and pyrolytic activities. High-ring PAHs (4-6 rings) contributed to 59-90% of the total PAHs concentrations. Benzo(a)pyrene (BaP) had the highest toxic equivalence quotient (up to 188 ng TEQ/g). Moreover, the downstream sediments contained higher TEQ of total TPHs than midstream and upstream sediment samples. The PAHs were adsorbed onto the fine particles with high organic content. Results from diagnostic ratio analyses indicate that the PAHs in two urban river sediments might originate from oil/coal combustion, traffic-related emissions, and waste combustion (pyrogenic activities). Future pollution prevention and management should target the various industries, incinerators, and transportation emission in this region to reduce the PAHs pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Organic markers as source discriminants and sediment transport indicators in south San Francisco Bay, California

USGS Publications Warehouse

Hostettler, F.D.; Rapp, J.B.; Kvenvolden, K.A.; Samuel, N L.

1989-01-01

Sediment samples from nearshore sites in south San Francisco Bay and from streams flowing into that section of the Bay have been characterized in terms of their content of biogenic and anthropogenic molecular marker compounds. The distributions, input sources, and applicability of these compounds in determining sediment movement are discussed. By means of inspection and multivariate analysis, the compounds were grouped according to probable input sources and the sampling stations according to the relative importance of source contributions. A suite of polycyclic aromatic hydrocarbons (PAHs) dominated by pyrene, fluoranthene and phenanthrene, typical of estuarine environments worldwide, and suites of mature sterane and hopane biomarkers were found to be most suitable as background markers for the Bay. A homologous series of long-chain n-aldehydes (C12-C32) with a strong even-over-odd carbon number dominance in the higher molecular weight range and the ubiquitous n-alkanes (n-C24-C34) with a strong odd-over-even carbon number dominance were utilized as terrigenous markers. Several ratios of these terrigenous and Bay markers were calculated for each station. These ratios and the statistical indicators from the multivariate analysis point toward a strong terrigenous signal in the terminus of South Bay and indicate net directional movement of recently introduced sediment where nontidal currents had been considered to be minimal or nonexistent and tidal currents had been assumed to be dominant. ?? 1989.

Source identification, environmental risk assessment and human health risks associated with toxic elements present in a coastal industrial environment, India.

PubMed

Satapathy, Shreemayee; Panda, C R

2018-03-26

This study investigated the source and contamination levels of toxic elements (Cd, Cr, As, Pb, Ni and Hg) present in a coastal environment, Paradip-an industrial hub of the east coast of India. The ecological risk assessment indices and human exposure models were used to evaluate the pollution status. Enrichment factor indicated that all the metal(loid)s found in the sediment are mostly derived from the anthropogenic source. According to the sediment quality quotient, 8.33% of sediments have crossed the ERM limit for Ni that can be fatal to biota. Meanwhile, 66.66, 41.66 and 8.33% of sediments have exceeded PEL range for Cr, Ni and As, respectively, that can register frequent lethal toxicity to benthic biota. As had the highest potential ecological harm coefficient (Er f  > 80), and Hg had moderate ecological harm coefficient (40 < Er f  < 80). Summarily, the sediment quality of this site is moderate to heavily toxic to benthic organisms. The concentration of toxic metals in seawater was below the permissible limit (CCC and CMC) set by USEPA indicating that water is relatively safer for free floating aquatic biota. The health risk index of toxic metal (loid)s present in soils of the residential sites has confirmed that there is a severe non-carcinogenic threat for children (HI child > 1) and a borderline carcinogenic risk for both adult and children. THQ Cr possesses highest non-carcinogenic threat, which contributed approximately 50% to HI followed by THQ As . The contribution of carcinogenic risk of chromium (CR Cr ) to TCR is approximately 60%. Cr is the significant contaminant of this site that has highest health effects. Highest exposure risks were associated with ingestion pathway accounting for about 85% of the total for most of the elements.

Holocene provenance shift of suspended particulate matter in the Amazon River basin

NASA Astrophysics Data System (ADS)

Höppner, Natalie; Lucassen, Friedrich; Chiessi, Cristiano M.; Sawakuchi, André O.; Kasemann, Simone A.

2018-06-01

The strontium (Sr), neodymium (Nd) and lead (Pb) isotope signatures of suspended particulate matter (SPM) in rivers reflect the radiogenic isotope signatures of the rivers' drainage basin. These signatures are not significantly affected by weathering, transport or depositional cycles, but document the sedimentary contributions of the respective sources. We report new Sr, Nd and Pb isotope ratios and element concentrations of modern SPM from the Brazilian Amazon River basin and document the past evolution of the basin by analyzing radiogenic isotopes of a marine sediment core from the slope off French Guiana archiving the last 40 kyr of Amazon River SPM, and the Holocene section of sediment cores raised between the Amazon River mouth and the slope off French Guiana. The composition of modern SPM confirms two main source areas, the Andes and the cratonic Shield. In the marine sediment core notable changes occurred during the second phase of Heinrich Stadial 1 (i.e. increased proportion of Shield rivers SPM) and during the last deglaciation (i.e. increased proportion of Madeira River SPM) together with elsewhere constant source contributions. Furthermore, we report a prominent offset in Sr and Nd isotopic composition between the average core value (εNd: -11.7 ± 0.9 (2SD), 87Sr/86Sr: 0.7229 ± 0.0016 (2SD)) and the average modern Amazon River SPM signal (εNd: -10.5 ± 0.5 (2SD), 87Sr/86Sr: 0.7213 ± 0.0036 (2SD)). We suggest that a permanent change in the Amazon River basin sediment supply during the late Holocene to a more Andean dominated SPM was responsible for the offset.

Total nitrogen and suspended-sediment loads and identification of suspended-sediment sources in the Laurel Hill Creek watershed, Somerset County, Pennsylvania, water years 2010-11

USGS Publications Warehouse

Sloto, Ronald A.; Gellis, Allen C.; Galeone, Daniel G.

2012-01-01

Laurel Hill Creek is a watershed of 125 square miles located mostly in Somerset County, Pennsylvania, with small areas extending into Fayette and Westmoreland Counties. The upper part of the watershed is on the Pennsylvania Department of Environmental Protection 303(d) list of impaired streams because of siltation, nutrients, and low dissolved oxygen concentrations. The objectives of this study were to (1) estimate the annual sediment load, (2) estimate the annual nitrogen load, and (3) identify the major sources of fine-grained sediment using the sediment-fingerprinting approach. This study by the U.S. Geological Survey (USGS) was done in cooperation with the Somerset County Conservation District. Discharge, suspended-sediment, and nutrient data were collected at two streamflow-gaging stations—Laurel Hill Creek near Bakersville, Pa., (station 03079600) and Laurel Hill Creek at Ursina, Pa., (station 03080000)—and one ungaged stream site, Laurel Hill Creek below Laurel Hill Creek Lake at Trent (station 03079655). Concentrations of nutrients generally were low. Concentrations of ammonia were less than 0.2 milligrams per liter (mg/L), and concentrations of phosphorus were less than 0.3 mg/L. Most concentrations of phosphorus were less than the detection limit of 0.02 mg/L. Most water samples had concentrations of nitrate plus nitrite less than 1.0 mg/L. At the Bakersville station, concentrations of total nitrogen ranged from 0.63 to 1.3 mg/L in base-flow samples and from 0.57 to 1.5 mg/L in storm composite samples. Median concentrations were 0.88 mg/L in base-flow samples and 1.2 mg/L in storm composite samples. At the Ursina station, concentrations of total nitrogen ranged from 0.25 to 0.92 mg/L in base-flow samples; the median concentration was 0.57 mg/L. The estimated total nitrogen load at the Bakersville station was 262 pounds (lb) for 11 months of the 2010 water year (November 2009 to September 2010) and 266 lb for the 2011 water year. Most of the total nitrogen loading was from stormflows. The stormflow load accounted for 76.6 percent of the total load for the 2010 water year and 80.6 percent of the total load for the 2011 water year. The estimated monthly total nitrogen loads were higher during the winter and spring (December through May) than during the summer (June through August). For the Bakersville station, the estimated suspended-sediment load (SSL) was 17,700 tons for 11 months of the 2010 water year (November 2009 to September 2010). The storm beginning January 24, 2010, provided 34.4 percent of the annual SSL, and the storm beginning March 10, 2010, provided 31.9 percent of the annual SSL. Together, these two winter storms provided 66 percent of the annual SSL for the 2010 water year. For the 2011 water year, the estimated annual SSL was 13,500 tons. For the 2011 water year, the SSLs were more evenly divided among storms than for the 2010 water year. Seven of 37 storms with the highest SSLs provided a total of 65.7 percent of the annual SSL for the 2011 water year; each storm provided from 4.6 to 12.3 percent of the annual SSL. The highest cumulative SSL for the 2010 and 2011 water years generally occurred during the late winter. Stormflows with the highest peak discharges generally carried the highest SSL. The sediment-fingerprinting approach was used to quantify sources of fine-grained suspended sediment in the watershed draining to the Laurel Hill Creek near Bakersville streamflow-gaging station. Sediment source samples were collected from five source types: 20 from cropland, 9 from pasture, 18 from forested areas, 20 from unpaved roads, and 23 from streambanks. At the Bakersville station, 10 suspended-sediment samples were collected during 6 storms for sediment-source analysis. Thirty-five tracers from elemental analysis and 4 tracers from stable isotope analysis were used to fingerprint the source of sediment for the 10 storm samples. Statistical analysis determined that cropland and pasture could not be discriminated by the set of tracers and were combined into one source group—agriculture. Stepwise discriminant function analysis determined that 11 tracers best described the 4 sources. An "unmixing" model applied to the 11 tracers showed that agricultural land (cropland and pasture) was the major source of sediment, contributing an average of 53 percent of the sediment for the 10 storm samples. Streambanks, unpaved roads, and forest contributions for the 10 storm samples averaged 30, 17, and 0 percent, respectively. Agriculture was the major contributor of sediment during the highest sampled stormflows. The highest stormflows also produced the highest total nitrogen and suspended-sediment loads.

Anthropogenic Sources of Arsenic and Copper to Sediments of a Suburban Lake, 1964-1998

NASA Astrophysics Data System (ADS)

Rice, K. C.; Conko, K. M.; Hornberger, G. M.

2002-05-01

Nonpoint-source pollution from urbanization is becoming a widespread problem. Long-term monitoring data are necessary to document geochemical processes in urban settings and changes in sources of chemical contaminants over time. In the absence of long-term data, lake-sediment cores can be used to reconstruct past processes, because they serve as integrators of sources of pollutants from the contributing airshed and catchment. Lake Anne is a 10.9-ha man-made lake in a 235-ha suburban catchment in Reston, Virginia, with a population density of 1,116 people/km2. Three sediment cores, collected in 1996 and 1997, indicate increasing concentrations of arsenic and copper since 1964, when the lake was formed. The cores were compared to a core collected from a forested catchment in the same airshed that showed no increases in concentrations of these elements. Neither an increase in atmospheric deposition nor diagenesis and remobilization were responsible for the trends in the Lake Anne cores. Mass balances of sediment, arsenic, and copper were calculated using 1998 data on precipitation, streamwater, road runoff, and a laboratory leaching experiment on pressure-treated lumber. Sources of arsenic to the lake in 1998 were in-lake leaching of pressure-treated lumber (52%) and streamwater (47%). Road runoff was a greater (93%) source of copper than leaching of pressure-treated lumber (4%). Atmospheric deposition was an insignificant source (<3%) of both elements. Urbanization of the catchment was confirmed as a major cause of the increasing arsenic and copper in the lake cores through an annual historical reconstruction of the deposition of sediment, arsenic, and copper to the lake for 1964-1997. Aerial photography indicated that the area of roads and parking lots in the catchment increased to 26% by 1997 and that the number of docks on the lake also increased over time. The increased mass of arsenic and copper in the lake sediments corresponded to the increased amount of pressure-treated lumber in the lake, and the mass of copper also corresponded to the increase in paved surfaces in the catchment.

Detrital thermochronology of Rhine, Elbe and Meuse river sediment (Central Europe): implications for provenance, erosion and mineral fertility

NASA Astrophysics Data System (ADS)

Glotzbach, C.; Busschers, F. S.; Winsemann, J.

2018-03-01

Here we present detrital apatite fission track (AFT), zircon fission track (ZFT) and a few apatite (U-Th)/He (AHe) data of Middle Pleistocene to modern Rhine, Meuse and Elbe river sediments in order to resolve processes that control detrital age distributions (provenance, erosion and mineral fertility). We used a modelling approach to compare observed with theoretically predicted age distributions from an interpolated in situ AFT and ZFT age map. In situ cooling ages do show large differences in the Rhine drainage basin, facilitating the differentiation between different source regions. Inconsistencies between observed and theoretical age distributions of the Meuse and Elbe samples can be explained by mixing and reworking of sediments with different provenances (Meuse Middle Pleistocene terrace sediment) and a yet unexplored source region with old AFT ages (Elbe samples). Overall, the results show that detrital thermochronology is capable of identifying the provenance of Middle Pleistocene to modern sediments. The AFT age distributions of Rhine sediments are dominated ( 70%) by AFT ages representing the Alps. A possible explanation is higher erosion rates in the Alps as compared to areas outside the Alps. A Late Pleistocene sample from the Upper Rhine Graben contains apatite grains from the Molasse and Hegau volcanics, which we explain with a shift of the headwaters of the Rhine to the north as a result of intense Middle Pleistocene Riss glaciation. Contrary to the observed dominance of Alpine-derived AFT ages in Rhine sediments, the relative contribution of zircon ages with sources in the Alps is lower and significantly decreases downstream, suggesting a major source of zircons outside the Alps. This can be explained by increased zircon fertility of sediments derived from the Rhenish massif. Therefore, we conclude that erosion and mineral fertility are the main processes controlling detrital AFT and ZFT age distributions of the sampled river sediment. In case of the Rhine samples, AFT age distributions are mainly controlled by differences in erosion rates, whereas this impact is completely balanced by differences in mineral fertility for the ZFT data.

n-Alkanes in sediments from the Yellow River Estuary, China: Occurrence, sources and historical sedimentary record.

PubMed

Wang, Shanshan; Liu, Guijian; Yuan, Zijiao; Da, Chunnian

2018-04-15

A total of 21 surface sediments from the Yellow River Estuary (YRE) and a sediment core from the abandoned Old Yellow River Estuary (OYRE) were analyzed for n-alkanes using gas chromatography-mass spectrometry (GC-MS). n-Alkanes in the range C 12 -C 33 and C 13 -C 34 were identified in the surface sediments and the core, respectively. The homologous series were mainly bimodal distribution pattern without odd/even predominance in the YRE and OYRE. The total n-alkanes concentrations in the surface sediments ranged from 0.356 to 0.572mg/kg, with a mean of 0.434mg/kg on dry wt. Evaluation of n-alkanes proxies indicated that the aliphatic hydrocarbons in the surface sediments were derived mainly from a petrogenic source with a relatively low contribution of submerged/floating macrophytes, terrestrial and emergent plants. The dated core covered the time period 1925-2012 and the mean sedimentation rate was ca. 0.5cm/yr. The total n-alkanes concentrations in the core ranged from 0.0394 to 0.941mg/kg, with a mean of 0.180mg/kg. The temporal evolution of n-alkanes reflected the historical input of aliphatic hydrocarbons and was consistent with local and regional anthropogenic activity. In general, the investigation on the sediment core revealed a trend of regional environmental change and the role of anthropogenic activity in environmental change. Copyright © 2017 Elsevier Inc. All rights reserved.

Multivariate analysis for source identification of pollution in sediment of Linggi River, Malaysia.

PubMed

Elias, Md Suhaimi; Ibrahim, Shariff; Samuding, Kamarudin; Rahman, Shamsiah Ab; Wo, Yii Mei; Daung, Jeremy Andy Dominic

2018-03-29

Rapid socioeconomic development in the Linggi River Basin has contributed to the significant increase of pollution discharge into the Linggi River and its adjacent coastal areas. The toxic element contents and distributions in the sediment samples collected along the Linggi River were determined using neutron activation analysis (NAA) and inductively coupled plasma-mass spectrometry (ICP-MS) techniques. The measured mean concentration of As, Cd, Pb, Sb, U, Th and Zn is relatively higher compared to the continental crust value of the respective element. Most of the elements (As, Cr, Fe, Pb, Sb and Zn) exceeded the freshwater sediment quality guideline-threshold effect concentration (FSQG-TEC) value. Downstream stations of the Linggi River showed that As concentrations in sediment exceeded the freshwater sediment quality guideline-probable effect concentration (FSQG-PEC) value. This indicates that the concentration of As will give an adverse effect to the growth of sediment-dwelling organisms. Generally, the Linggi River sediment can be categorised as unpolluted to strongly polluted and unpolluted to strongly to extremely polluted. The correlation matrix of metal-metal relationship, principle component analysis (PCA) and cluster analysis (CA) indicates that the pollution sources of Cu, Ni, Zn, Cd and Pb in sediments of the Linggi River originated from the industry of electronics and electroplating. Elements of As, Cr, Sb and Fe mainly originated from motor-vehicle workshops and metal work, whilst U and Th originated from natural processes such as terrestrial runoff and land erosion.

Sources of the transuranic elements plutonium and neptunium in arctic marine sediments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, L. W.; Kelley, J. M.; Bond, L. A.

2000-01-01

We report here thermal ionization mass spectrometry measurements of {sup 239}Pu, {sup 240}Pu, {sup 241}Pu, {sup 242}Pu, and {sup 237}Np isolated from oceanic, estuarine, and riverine sediments from the Arctic Ocean Basin. {sup 238}Pu/{sup 239+240}Pu activity ratios are also reported for alpha spectrometric analyses undertaken on a subset of these samples. Our results indicate that the Pu in sediments on the Alaskan shelf and slope, as well as that in the deep basins (Amerasian and Eurasian) of the Arctic Ocean, has its origin in stratospheric and tropospheric fallout. Sediments from the Ob and Yenisei Rivers show isotopic Pu signatures thatmore » are distinctly different from those of northern-hemisphere stratospheric fallout and indicate the presence of weapons-grade Pu originating from nuclear fuel reprocessing wastes generated at Russian facilities within these river catchments. Consequently, sediments of the Eurasian Arctic Ocean, particularly those in the Barents and Kara Seas, probably contain a mixture of Pu from stratospheric fallout, tropospheric fallout, and fuel-reprocessing wastes of riverine origin. In particular, the {sup 241}Pu/{sup 239}Pu ratios observed in these sediments are inconsistent with significant contributions of Pu to the arctic sediments studied from western European reprocessing facilities, principally Sellafield in the UK. Several other potential sources of Pu to arctic sediments can also be excluded as significant based upon the transuranic isotope ratios presented.« less

Source to Sink Transport of Terrestrial Biomarkers in a Monsoon-driven Fluvial System

NASA Astrophysics Data System (ADS)

Kirkels, F.; Zwart, H. M.; Usman, M.; Basu, S.; Martes, C.; Eglinton, T. I.; Peterse, F.

2016-12-01

Rivers are an important link in global organic carbon (OC) cycling by connecting soils and marine sediments. Whereas deposition of terrestrial carbon in marine settings may form a large OC sink, the extent of OC loss during river transport by CO2 outgassing is highly uncertain. In this context, it is crucial to better constrain the composition and sources of OC in rivers. The Godavari River in Central India is very dynamic with intense rainfall and high soil erosion rates during the monsoon and low transport during the dry period, representative of low frequency, high-impact erosion events expected worldwide due to climate change. In this study, we did a high-resolution sampling of soils, river sediments (bulk and < 63 um) and suspended particulate matter (SPM) during the monsoon and dry season. Source-to-sink tracing of concentration and compositional variations in branched glycerol dialkyl glycerol tetraethers (brGDGTs) as soil-specific biomarkers allowed us to follow soil OC transport through the river basin. Spatial trends in weight-normalized GDGT patterns reveal marked changes during the monsoon and dry season from upstream tributaries towards the delta. Evolution of GDGT signatures along the course of the river shows that SPM during the monsoon carries a primarily soil-derived signal contributed by the northern headwaters. Dominance of the recently discovered 6-methyl isomer indicates a year-round aquatic contribution from the western tributaries. River water isotopic composition and GDGT signatures show that northern tributaries dominate modern OC export from the Godavari basin, providing new information for the interpretation of paleorecords derived from cores taken in the Bay of Bengal. More detailed insights in OC sources in the Godavari basin will derive from (bulk) δ13C and ultimately 14C analyses of soils and river sediments. Further research into provenance of the mineral fraction will reveal if sediment and OC transport is (de)coupled.

Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

NASA Astrophysics Data System (ADS)

Lin, Xianbiao; Liu, Min; Hou, Lijun; Gao, Dengzhou; Li, Xiaofei; Lu, Kaijun; Gao, Juan

2017-10-01

Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. Here potential rates of N losses, and their contributions and controlling factors, were investigated in surface sediments during six cruises from 429 sites of the East China Sea. The potential rates of denitrification, anammox, and N2O production varied both spatially and seasonally, but the contribution of anammmox to total N2 production (%anammox) and N2O:N2 ratio only varied spatially. Both organic carbon and nitrate (NO3-) were important factors controlling N losses, N2O:N2 ratio, and %anammox. Our results also showed that marine organic carbon induced by eutrophication plays an important role in stimulating reactive N removal and increasing N2O production in warm seasons. The sediment N loss caused by denitrification, anammox, and N2O production in the study area were estimated at 2.2 × 106 t N yr-1, 4.6 × 105 t N yr-1, and 8 × 103 t N yr-1, respectively. Although sediments remove large quantities of reactive N, they act as an important source of N2O in this region influenced by NO3--laden rivers.

Metal pollution investigation of Goldman Park, Middletown Ohio: Evidence for steel and coal pollution in a high child use setting.

PubMed

Dietrich, Matthew; Huling, Justin; Krekeler, Mark P S

2018-03-15

A geochemical investigation of both ballfield sediment and street sediment in a park adjacent to a major steel manufacturing site in Middletown, Ohio revealed Pb, Cu, Cr and Zn exceeded background levels, but in heterogeneous ways and in varying levels of health concern. Pb, Sn, and Zn had geoaccumulation values>2 (moderate to heavy pollutants) in street sediment samples. Cr had a geoaccumulation value>1, while Ni, W, Fe and Mn had geoaccumulation values between 1 and 0 in street sediment. Street sediment contamination factors for respective elements are Zn (10.41), Sn (5.45), Pb (4.70), Sb (3.45), Cr (3.19), W (2.59), and Mn (2.43). The notable elements with the highest factors for ball fields are Zn (1.72), Pb (1.36), Cr (0.99), V (0.95), and Mn (1.00). High correlation coefficients of known constituents of steel, such as Fe and Mo, Ni and Cr, W and Co, W and V, as well as particulate steel and coal spherule fragments found by SEM suggest probable sourcing of some of the metals from the AK Steel facility directly adjacent to the park. However, overall extensive heterogeneity of metal pollutants in the area points to the difficulties in sourcing pollutant metals, with many outside sources likely contributing as well. This study demonstrates that different sediment media can be impacted by significantly different metal pollutants even when in very close proximity to a single source and points to unrecognized complexity in urban pollution processes in the region. This study pertains to large-scale regional importance, as Middletown, Ohio is indicative of a typical post-industrial Midwestern U.S. city where limited investigation has been conducted regarding urban pollution and sourcing of materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Distribution of Escherichia coli and Enterococci in water, sediments, and bank soils along North Shore Channel between Bridge Street and Wilson Avenue, Metropolitan Water Reclamation District of Greater Chicago

USGS Publications Warehouse

Byappanahalli, Muruleedhara; Whitman, Richard L.; Shively, Dawn; Przybyla-Kelly, Katarzyna; Lukasik, Ashley M.

2010-01-01

The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) wished to know the distribution and potential sources of fecal indicator bacteria, E. coli and enterococci, in water, sediments, and upland soils along an upstream and downstream portion of the North Shore Channel (NSC) that is the receiving stream for the District’s North Side Water Reclamation Plant (NSWRP) outfall. Biweekly water and sediment samples were collected between August and October 2008 and included the following locations upstream of the outfall: Bridge Street (UPS-1), Oakton Street (UPS-2), the NSWRP outfall (OF), and downstream: Foster Avenue (DNS-1), and Wilson Avenue (DNS-2). E. coli and enterococci were consistently found in water and sediments at all sampling locations, with bacterial densities in water increasing below the NSWRP outfall; bacterial densities in sediment were more variable. On a relative measurement basis (i.e., 100 ml=100 g), both E. coli and enterococci densities were significantly higher in sediments than water. E. coli and enterococci were consistently recovered from bank soil along wooded, grassy, erosional, and depositional areas at two recreational parks, as well as other riparian areas along the river. Thus, soils along the river basin are likely sources of these bacteria to the NSC channel, introduced through runoff or other physical processes. Tributaries, such as the North Branch of the Chicago River (NBCR) that flow into NSC near Albany Ave, may provide a constant source of E. coli and enterococci to the NSC. Additionally, storm sewer outfalls may increase E. coli loadings to NSC during wet weather conditions. Our findings suggest that the abundance of nonpoint sources contributing to the overall fecal indicator bacteria (FIB) load in the NSC channel may complicate bacteria source determination and remediation efforts to protect the stream water quality.

Multiple-source tracking: Investigating sources of pathogens, nutrients, and sediment in the Upper Little River Basin, Kentucky, water years 2013–14

USGS Publications Warehouse

Crain, Angela S.; Cherry, Mac A.; Williamson, Tanja N.; Bunch, Aubrey R.

2017-09-20

The South Fork Little River (SFLR) and the North Fork Little River (NFLR) are two major headwater tributaries that flow into the Little River just south of Hopkinsville, Kentucky. Both tributaries are included in those water bodies in Kentucky and across the Nation that have been reported with declining water quality. Each tributary has been listed by the Kentucky Energy and Environment Cabinet—Kentucky Division of Water in the 303(d) List of Waters for Kentucky Report to Congress as impaired by nutrients, pathogens, and sediment for contact recreation from point and nonpoint sources since 2002. In 2009, the Kentucky Energy and Environment Cabinet—Kentucky Division of Water developed a pathogen total maximum daily load (TMDL) for the Little River Basin including the SFLR and NFLR Basins. Future nutrient and suspended-sediment TMDLs are planned once nutrient criteria and suspended-sediment protocols have been developed for Kentucky. In this study, different approaches were used to identify potential sources of fecal-indicator bacteria (FIB), nitrate, and suspended sediment; to inform the TMDL process; and to aid in the implementation of effective watershed-management activities. The main focus of source identification was in the SFLR Basin.To begin understanding the potential sources of fecal contamination, samples were collected at 19 sites for densities of FIB (E. coli) in water and fluvial sediment and at 11 sites for Bacteroidales genetic markers (General AllBac, human HF183, ruminant BoBac, canid BacCan, and waterfowl GFD) during the recreational season (May through October) in 2013 and 2014. Results indicated 34 percent of all E. coli water samples (n=227 samples) did not meet the U.S. Environmental Protection Agency 2012 recommended national criteria for primary recreational waters. No criterion currently exists for E. coli in fluvial sediment. By use of the Spearman’s rank correlation test, densities of FIB in fluvial sediments were observed to have a statistically significant positive correlation with drainage area. As drainage area increased, so did the densities of FIB in the fluvial sediments. There was no statistically significant correlation between drainage area and FIB in water. The human-associated marker (HF183) was found above the detection limit in 26 percent of the samples (n=120 samples); a higher proportion of positive samples was in the NFLR Basin. The ruminant-associated marker (BoBac) was above the detection limit in 65 percent of samples; a higher proportion of positive samples was in the headwaters of the SFLR Basin.Nutrient yields differed between the SFLR and NFLR Basins. Comparatively, the SFLR Basin produced the largest estimated mean yields of total nitrogen (16,000 pounds per year per square mile (lb/yr/mi2) and nitrite plus nitrate nitrogen (12,500 lb/yr/mi2), and the NFLR Basin produced the largest estimated mean yields of ammonia plus organic nitrogen (4,700 lb/yr/mi2), total phosphorus (1,100 lb/yr/mi2), and orthophosphorus (590 lb/yr/mi2).Nitrate sources in surface water were assessed in both basins using dual-nitrate isotope (nitrogen and oxygen) ratios. Data from the different land uses in the SFLR Basin showed differences in nitrate concentrations and overlapping, but moderately distinct, isotopic signatures. Predominantly forested sites consistently had low nitrate concentrations (median = 0.233 milligrams per liter) with minimal variability, and agricultural sites had the highest nitrate concentrations (median = 7.55 milligrams per liter) with the greatest variability. The median nitrate concentration for sites with mixed land use was 2.66 milligrams per liter. Dual-isotope data for forested sites plotted within ranges characteristic of soil-derived nitrate with possible but minimal influence from recycled atmospheric nitrate. Ranges of dual-isotope data for sites with agricultural and mixed land uses were characteristic of possible mixtures of chemical fertilizer, soil-derived nitrate, and manure and septic wastes. In the NFLR Basin, a positive linear relation was observed between nitrate concentrations and nitrogen isotope ratios (δ15NNO3) (R2=0.56; p-value <0.001) that potentially suggests the NFLR Basin has a higher proportion of δ15NNO3-enriched sources, such as manure and sewage. However, mixing of other nitrate-derived sources cannot be excluded, because many values of δ15NNO3 and concentrations of nitrate showed minimal variation and plotted within dual-nitrate isotope ranges characteristic of fertilizer and soil-derived nitrate sources.A sediment-fingerprinting approach was used to quantify the relative contribution of four upland sources in the SFLR Basin (agricultural, pasture, riparian/forest, and streambank) to understand how land management affects suspended-sediment concentration. Carbon isotope ratios (δ13C), together with calcium and carbon concentrations, were the best indicators of sediment source; the uncertainty was less than 11 percent. Fine-sediment samples collected at the SFLR Basin outlet indicated streambanks as the largest source of the fine sediment to the stream followed by cropland and riparian/forest-source areas, respectively; pasture was a minor contributing source. Streambanks and cropland were essentially equal contributors of fine sediment at the NFLR Basin outlet.

Identifying fecal sources in a selected catchment reach using multiple source-tracking tools

USGS Publications Warehouse

Vogel, J.R.; Stoeckel, D.M.; Lamendella, R.; Zelt, R.B.; Santo, Domingo J.W.; Walker, S.R.; Oerther, D.B.

2007-01-01

Given known limitations of current microbial source-tracking (MST) tools, emphasis on small, simple study areas may enhance interpretations of fecal contamination sources in streams. In this study, three MST tools - Escherichia coli repetitive element polymerase chain reaction (rep-PCR), coliphage typing, and Bacteroidales 16S rDNA host-associated markers - were evaluated in a selected reach of Plum Creek in sooth-central Nebraska. Water-quality samples were collected from six sites. One reach was selected for MST evaluation based on observed patterns of E. coli contamination. Despite high E. coli concentrations, coliphages were detected only once among water samples, precluding their use as a MST tool in this setting. Rep-PCR classification of E. coli isolates from both water and sediment samples supported the hypothesis that cattle and wildlife were dominant sources of fecal contamination, with minor contributions by horses and humans. Conversely, neither ruminant nor human sources were detected by Bacteroidales markers in most water samples. In bed sediment, ruminant- and human-associated Bacteroidales markers were detected throughout the interval from 0 to 0.3 m, with detections independent of E. coli concentrations in the sediment. Although results by E. coli-based and Bacteroidales-based MST methods led to similar interpretations, detection of Bacteroidales markers in sediment more commonly than in water indicates that different tools to track fecal contamination (in this case, tools based on Bacteroidales DNA and E. coli isolates) may have varying relevance to the more specific goal of tracking the sources of E. coli in watersheds. This is the first report of simultaneous, toolbox approach application of a library-based and marker-based MST analyses to lowing surface water. ?? ASA, CSSA, SSSA.

Importance of diffuse pollution control in the Patzcuaro Lake Basin in Mexico.

PubMed

Carro, Marco Mijangos; Dávila, Jorge Izurieta; Balandra, Antonieta Gómez; López, Rubén Hernández; Delgadillo, Rubén Huerto; Chávez, Javier Sánchez; Inclán, Luís Bravo

2008-01-01

In the catchment area of the Lake Patzcuaro in Central Mexico (933 km2) the apportionments of erosion, sediment, nutrients and pathogen coming from thirteen micro basins were estimated with the purpose of identifying critical areas in which best management practices need to be implemented in order to reduce their contribution to the lake pollution and eutrophication. The ArcView Generalized Watershed Loading Functions model (AV-GWLF) was applied to estimate the loads and sources of nutrients. The main results show that the total annual contribution of nitrogen from point sources were 491 tons and from diffuse pollution 2,065 tons, whereas phosphorus loads where 116 and 236 tons, respectively during a thirty year simulation period. Micro basins with predominant agricultural and animal farm land use (56% of the total area) accounts for a high percentage of nitrogen load 33% and phosphorus 52%. On the other hand, Patzcuaro and Quiroga micro basins which comprise approximately 10% of the total catchment area and are the most populated and visited towns by tourist 686,000 people every year, both contributes with 10.1% of the total nitrogen load and 3.2% of phosphorus. In terms of point sources of nitrogen and phosphorus the last towns contribute with 23.5% and 26.6% respectively. Under this situation the adoption of best management practices are an imperative task since the sedimentation and pollution in the lake has increased dramatically in the last twenty years. Copyright (c) IWA Publishing 2008.

Distribution characteristics and source identification of polychlorinated dibenzo-p-dioxin and dibenzofurans, and dioxin-like polychlorinated biphenyls in the waters from River Kanzaki, running through Osaka urban area, Japan.

PubMed

Kishida, Masao

2013-03-01

This is the first to elucidate the distribution and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs), and dioxin-like polychlorinated biphenyls in the waters from Kanzaki River, which is one of the most heavily polluted rivers in Japan. The World Health Organization (WHO)-toxic equivalent quantities (TEQs) in waters from the mainstream exceeded the Japanese environmental standard (1.0 pg-TEQ/L). The PCDD/PCDFs were dominated by highly chlorinated DFs, which predominantly contributed to the WHO-TEQs, suggesting that the main causes would be the incineration-related wastes. To find the sources, the dioxin congener concentrations in water and sediment samples from its tributary small waterways were determined. Abnormally high WHO-TEQs were detected in a water (50 pg-TEQ/L) and a sediment sample (41,000 ng-TEQ/kg dry weight) near the industrial solid waste incinerators (ISWIs). The PCDD/PCDF characteristics agreed well with those of the incinerator-related wastes as seen in the mainstream. These facts indicate that the dioxin pollution in the mainstream could be largely related to the industrial wastes from the ISWIs. Here, a TEQ apportionment method was used to understand the contribution of the pyrogenic sources to the WHO-TEQs. The average contribution ratios of the pyrogenic sources to WHO-TEQs were more than 80% for river waters from the mainstream, indicating that the elevated WHO-TEQs in the mainstream had been largely caused by the ISWIs.

Comparison of sediments and organisms in identifying sources of biologically available trace metal contamination

USGS Publications Warehouse

Thomson, E.A.; Luoma, S.N.; Johansson, C.E.; Cain, D.J.

1984-01-01

Sediments and an indicator organism (Macoma balthica, a deposit-feeding bivalve) were used to assess the relative importance of secondary sewage, urban runoff, a landfill containing metal-enriched ash wastes and a yacht harbor in contributing to Ag, Cu and Zn enrichment in South San Francisco Bay. Spatial gradients in sediments and organisms showed Cu and Ag enrichment originated from sewage discharge, whereas Zn enrichment originated from both sewage and urban runoff. Elevated concentrations of Cu in the sediments of the yacht harbor resulted from a high abundance of fine particles. The biological availability of Cu, Ag and Zn did not coincide with metal enrichment in sediments. The availability of Cu and Ag was greatest nearest the sewage outfall and greater in winter and spring than in summer. The availability of Zn in urban runoff appeared to be lower than the availability of Zn associated with sewage.

A Transformational Journey: Compositional Changes in Organic Matter during Desorption from Sediments

NASA Astrophysics Data System (ADS)

Matiasek, S. J.; Pellerin, B. A.; Spencer, R.; Bergamaschi, B. A.; Hernes, P.

2016-12-01

The release of organic matter (OM) from suspended particles via desorption is a critical component of OM cycling since dissolved OM (DOM) fuels aquatic ecosystems and is a precursor for disinfection by-products formation. This study assessed the elemental and molecular composition of DOM desorbed abiotically from sediments and soils of an irrigated agricultural watershed of northern California. Relative to mineral-bound OM, the released DOM was nitrogen-poor (lower carbon:nitrogen ratios) and depleted in amino acids and lignin phenols (lower carbon-normalized yields). Water-extracted DOM appeared substantially more degraded than its parent particulate OM with increased molar contributions of acidic amino acids, non-protein amino acids, and acidic lignin phenols, all molecular indicators of a more extensively processed OM pool. Desorption processes also significantly altered lignin compositional ratios which help distinguish vascular-plant sources of DOM. Specific optical parameters, including spectral slope, specific UV absorbance at 254 nm (SUVA254), and fluorescence index (FI), did not constitute useful proxies for the desorbed DOM pool, while absorption coefficients and fluorescence peak intensities were strongly correlated with extracted DOM concentrations and composition. This study highlights the profound impact of desorption on DOM composition which, if unaccounted for, could lead to misinterpretations of common biomarkers and optical proxies used to predict DOM sources and reactivity. Our findings suggest that sediments contribute a biogeochemically distinct source of DOM to surface waters, with potential impacts on aquatic health and drinking water quality.

Sources of phosphorus in stormwater and street dirt from two urban residential basins in Madison, Wisconsin, 1994-95

USGS Publications Warehouse

Waschbusch, Robert J.; Selbig, W.R.; Bannerman, Roger T.

1999-01-01

Street-dirt samples were collected using industrial vacuum equipment. Leaves in these samples were separated out and the remaining sediment was sieved into >250 mm, 250-63 mm, 63-25 mm, <25 mm size fractions and were analyzed for total phosphorus. Approximately 75 percent of the sediment mass resides in the >250 mm size fractions. Less than 5 percent of the mass can be found in the particle sizes less than 63 mm. The >250 mm size fraction also contributed nearly 50 percent of the total-phosphorus mass and the leaf fraction contributed an additional 30 percent. In each particle size, approximately 25 percent of the total-phosphorus mass is derived from leaves or other vegetation.

210Pb as a tool for establishing sediment chronologies: examples of potentials and limitations of conventional dating models.

PubMed

Kirchner, Gerald

2011-05-01

For aquatic sediments, the use of (210)Pb originating from the decay of atmospheric (222)Rn is a well-established methodology to estimate sediment ages and sedimentation rates. Traditionally, the measurement of (210)Pb in soils and sediments involved laborious and time-consuming radiochemical separation procedures. Due to the recent development of advanced planar ('n-type') semi-conductors with high efficiencies in the low-energy range which enable the gamma-spectrometric analysis of the 46.5 keV decay line of (210)Pb, sediment dating using this radionuclide has gained renewed interest. In this contribution, potentials and limitations of the (210)Pb methodology and of the models used for estimating sediment ages and sedimentation rates are discussed and illustrated by examples of freshwater and marine sediments. Comparison with the use of (137)Cs shows that the information which may be gained by these two tracers is complementary. As a consequence, both radionuclides should be used in combination for dating of recent sediments. It is shown that for various sedimentation regimes additional information from other sources (e.g. sediment lithology) may be needed to establish a reliable chronology. A strategy for sediment dating using (210)Pb is recommended. Copyright © 2010 Elsevier Ltd. All rights reserved.

Verifying Sediment Fingerprinting Results with Known Mixtures

NASA Astrophysics Data System (ADS)

Gellis, A.; Gorman-Sanisaca, L.; Cashman, M. J.

2017-12-01

Sediment fingerprinting is a widely used approach to determine the specific sources of fluvial sediment within a watershed. It relies on the principle that potential sediment sources can be identified using a set of chemical tracers (or fingerprints), and comparison of these source fingerprints with fluvial (target) sediment allows for source apportionment of the fluvial sediment. There are numerous source classifications, fingerprints, and statistical approaches used in the literature to apportion sources of sediment. However, few of these studies have sought to test the method by creating controls on the ratio of sources in the target sediment. Without a controlled environment for inputs and outputs, such verification of results is ambiguous. Here, we generated artificial mixtures of source sediment from an agricultural/forested watershed in Virginia, USA (Smith Creek, 246 km2) to verify the apportionment results. Target samples were established from known mixtures of the four major sediment sources in the watershed (forest, pasture, cropland, and streambanks). The target samples were sieved to less than 63 microns and analyzed for elemental and isotopic chemistry. The target samples and source samples were run through the Sediment Source Assessment Tool (Sed_SAT) to verify if the statistical operations provided the correct apportionment. Sed_SAT uses a multivariate parametric approach to identify the minimum suite of fingerprints that discriminate the source areas and applies these fingerprints through an unmixng model to apportion sediment. The results of this sediment fingerprinting verification experiment will be presented in this session.

Contributions of human activities to suspended-sediment yield during storm events from a steep, small, tropical watershed, American Samoa

NASA Astrophysics Data System (ADS)

Messina, A. T.; Biggs, T. W.

2014-12-01

Anthropogenic watershed disturbance by agriculture, deforestation, roads, and urbanization can alter the timing, composition, and mass of sediment loads to adjacent coral reefs, causing enhanced sediment stress on corals near the outlets of impacted watersheds like Faga'alu, American Samoa. To quantify the increase in sediment loading to the adjacent priority coral reef experiencing sedimentation stress, suspended-sediment yield (SSY) from undisturbed and human-disturbed portions of a small, steep, tropical watershed was measured during baseflow and storm events of varying magnitude. Data on precipitation, discharge, turbidity, and suspended-sediment concentration (SSC) were collected over three field campaigns and continuous monitoring from January 2012 to March 2014, which included 88 storm events. A combination of paired- and nested-watershed study designs using sediment budget, disturbance ratio, and sediment rating curve methodologies was used to quantify the contribution of human-disturbed areas to total SSY. SSC during base- and stormflows was significantly higher downstream of an open-pit aggregate quarry, indicating the quarry is a key sediment source requiring sediment discharge mitigation. Comparison of event-wise SSY from the upper, undisturbed watershed, and the lower, human-disturbed watershed showed the Lower watershed accounted for more than 80% of total SSY on average, and human activities have increased total sediment loading to the coast by approximately 200%. Four storm characteristics were tested as predictors of event SSY using Pearson's and Spearman's correlation coefficients. Similar to mountainous watersheds in semi-arid and temperate watersheds, SSY from both the undisturbed and disturbed watersheds had the highest correlation with event maximum discharge, Qmax (Pearson's R=0.88 and 0.86 respectively), and were best fit by a power law relationship. The resulting model of event-SSY from Faga'alu is being incorporated as part of a larger project investigating relationships and interactions between terrigenous sediment, water circulation over the reef, and the spatial distribution of sediment accumulation under various conditions in a linked watershed and fringing-reef embayment.

Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China.

PubMed

Tang, Qiang; Bao, Yuhai; He, Xiubin; Fu, Bojie; Collins, Adrian L; Zhang, Xinbao

2016-04-01

Since the launch of the Three Gorges Dam on the Yangtze River, a distinctive reservoir fluctuation zone has been created and significantly modified by regular dam operations. Sediment redistribution within this artificial landscape differs substantially from that in natural fluvial riparian zones, due to a specific hydrological regime comprising steps of water impoundment with increasing magnitudes and seasonal water level fluctuation holding a range of sediment fluxes. This study reinterpreted post-dam sedimentary dynamics in the reservoir fluctuation zone by stratigraphy determination of a 345-cm long sediment core, and related it to impact of the hydrological regime. Seasonality in absolute grain-size composition of suspended sediment was applied as a methodological basis for stratigraphic differentiation. Sedimentary laminations with relatively higher proportions of sandy fractions were ascribed to sedimentation during the dry season when proximal subsurface bank erosion dominates source contributions, while stratigraphy with a lower proportion of sandy fractions is possibly contributed by sedimentation during the wet season when distal upstream surface erosion prevails. Chronology determination revealed non-linear and high annual sedimentation rates ranging from 21.7 to 152.1cm/yr. Although channel geomorphology may primarily determine the spatial extent of sedimentation, seasonal sedimentary dynamics was predominantly governed by the frequency, magnitude, and duration of flooding. Summer inundation by natural floods with enhanced sediment loads produced from upstream basins induced higher sedimentation rates than water impoundment during the dry season when distal sediment supply was limited. We thus conclude that flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone, though little impact on total sediment retention rate was detected. Ongoing reductions in flow and sediment supply under human disturbance may have profound implications in affecting sedimentary equilibrium in the reservoir fluctuation zone. The results herein provide insights of how big dams have disrupted the sediment conveyance processes of large scale fluvial systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Preliminary use of compound-specific stable isotope (CSSI) technique to identify and apportion sediment origin in a small Austrian catchment

NASA Astrophysics Data System (ADS)

Mabit, Lionel; Gibbs, Max; Chen, Xu; Meusburger, Katrin; Toloza, Arsenio; Resch, Christian; Klik, Andreas; Eder, Alexander; Strauss, Peter; Alewell, Christine

2015-04-01

The overall impacts of climate change on agriculture are expected to be negative, threatening global food security. In the agricultural areas of the European Union, water erosion risk is expected to increase by about 80% by the year 2050. Reducing soil erosion and sedimentation-related environmental problems represent a key requirement for mitigating the impact of climate change. A new forensic stable isotope technique, using the compound specific stable isotope (CSSI) signatures of inherent soil organic biomarkers, can discriminate and apportion the source soil contribution from different land uses. Plant communities label the soil where they grow by exuding organic biomarkers. Although all plants produce the same biomarkers, the stable isotopic signature of those biomarkers is different for each plant species. For agri-environmental investigation, the CSSI technique is based on the measurement of carbon-13 (13-C) natural abundance signatures of specific organic compounds such as natural fatty acids (FAs) in the soil. By linking fingerprints of land use to the sediment in deposition zones, this approach has been shown to be a useful technique for determining the source of eroded soil and thereby identifying areas prone to soil degradation. The authors have tested this innovative stable isotopic approach in a small Austrian agricultural catchment located 60 km north of Vienna. A previous fallout radionuclide (i.e. 137-Cs) based investigation established a sedimentation rate of 4 mm/yr in the lowest part of the study site. To gain knowledge about the origin of these sediments, the CSSI technique was then tested using representative samples from the different land-uses of the catchment as source material. Values of 13-C signatures of specific FAs (i.e. C22:0 = Behenic Acid ; C24:0 = Lignoceric Acid) and the bulk 13-C of the sediment mixture and potential landscape sources were analyzed with the mixing models IsoSource and CSSIAR v1.00. Using both mixing models, preliminary results highlighted that about 50-55% of the sediment located in the deposition area originated from the main grassed waterway of the catchment.

Sedimentary record and anthropogenic pollution of a complex, multiple source fed dam reservoirs: An example from the Nové Mlýny reservoir, Czech Republic.

PubMed

Sedláček, Jan; Bábek, Ondřej; Nováková, Tereza

2017-01-01

While numerous studies of dam reservoirs contamination are reported world-wide, we present a missing link in the study of reservoirs sourced from multiple river catchments. In such reservoirs, different point sources of contaminants and variable composition of their sedimentary matrices add to extremely complex geochemical patterns. We studied a unique, step-wise filled Nové Mlýny dam reservoir, Czech Republic, which consists of three interconnected sub-basins. Their source areas are located in units with contrasting geology and different levels and sources of contamination. The aim of this study is to provide an insight into the provenance of the sediment, including lithogenic elements and anthropogenic pollutants, to investigate the sediment dispersal across the reservoir, and to assess the heavy metal pollution in each basin. The study is based on multi-proxy stratigraphic analysis and geochemistry of sediment cores. There is a considerable gradient in the sediment grain size, brightness, MS and geochemistry, which reflects changing hydrodynamic energy conditions and primary pelagic production of CaCO 3 . The thickness of sediments generally decreases from proximal to distal parts, but underwater currents can accumulate higher amounts of sediments in distal parts near the thalweg line. Average sedimentation rates vary over a wide range from 0.58cm/yr to 2.33cm/yr. In addition, the petrophysical patterns, concentrations of lithogenic elements and their ratios made it possible to identify two main provenance areas, the Dyje River catchment (upper basin) and the Svratka and Jihlava River catchments (middle and lower basin). Enrichment factors (EF) were used for distinguishing the anthropogenic element contribution from the local background levels. We found moderate Zn and Cu pollution (EF ~2 to 5) in the upper basin and Zn, Cu and Pb (EF ~2 to 4.5) in the middle basin with the peak contamination in the late 1980s, indicating that the two basins have different contamination histories. Copyright © 2016 Elsevier B.V. All rights reserved.

Sediments in Arctic sea ice: Implications for entrainment, transport and release

USGS Publications Warehouse

Nurnberg, D.; Wollenburg, I.; Dethleff, D.; Eicken, H.; Kassens, H.; Letzig, T.; Reimnitz, E.; Thiede, Jorn

1994-01-01

Despite the Arctic sea ice cover's recognized sensitivity to environmental change, the role of sediment inclusions in lowering ice albedo and affecting ice ablation is poorly understood. Sea ice sediment inclusions were studied in the central Arctic Ocean during the Arctic 91 expedition and in the Laptev Sea (East Siberian Arctic Region Expedition 1992). Results from these investigations are here combined with previous studies performed in major areas of ice ablation and the southern central Arctic Ocean. This study documents the regional distribution and composition of particle-laden ice, investigates and evaluates processes by which sediment is incorporated into the ice cover, and identifies transport paths and probable depositional centers for the released sediment. In April 1992, sea ice in the Laptev Sea was relatively clean. The sediment occasionally observed was distributed diffusely over the entire ice column, forming turbid ice. Observations indicate that frazil and anchor ice formation occurring in a large coastal polynya provide a main mechanism for sediment entrainment. In the central Arctic Ocean sediments are concentrated in layers within or at the surface of ice floes due to melting and refreezing processes. The surface sediment accumulation in central Arctic multi-year sea ice exceeds by far the amounts observed in first-year ice from the Laptev Sea in April 1992. Sea ice sediments are generally fine grained, although coarse sediments and stones up to 5 cm in diameter are observed. Component analysis indicates that quartz and clay minerals are the main terrigenous sediment particles. The biogenous components, namely shells of pelecypods and benthic foraminiferal tests, point to a shallow, benthic, marine source area. Apparently, sediment inclusions were resuspended from shelf areas before and incorporated into the sea ice by suspension freezing. Clay mineralogy of ice-rafted sediments provides information on potential source areas. A smectite maximum in sea ice sediment samples repeatedly occurred between 81??N and 83??N along the Arctic 91 transect, indicating a rather stable and narrow smectite rich ice drift stream of the Transpolar Drift. The smectite concentrations are comparable to those found in both Laptev Sea shelf sediments and anchor ice sediments, pointing to this sea as a potential source area for sea ice sediments. In the central Arctic Ocean sea ice clay mineralogy is significantly different from deep-sea clay mineral distribution patterns. The contribution of sea ice sediments to the deep sea is apparently diluted by sedimentary material provided by other transport mechanisms. ?? 1994.

An integrated suspended sediment budgeting of the agricultural Can Revull catchment (Mallorca, Spain)

NASA Astrophysics Data System (ADS)

Estrany, J.; Garcia, C.

2012-04-01

The Mediterranean region of Europe has a long history of human settlement and human impacts. The very high spatial and temporal variability of fluvial processes in the region also creates problems for measurement and monitoring and for assessment of effects. Extensive rainfed herbaceous crops are one of the most representative agricultural elements of this region, which should be one of the major factor affecting erosion processes. Although land use is commonly seen as resulting in increased sediment yields, the implementation of soil and water conservation practices can have the reverse effect. Sediment budgets offer a means to assess the sources, storage, rates of transport, yields, and efficiency of delivery of sediment for a range of catchment scales. Field measurements were conducted in Can Revull, a small agricultural catchment (1.03 km2) on the island of Mallorca. This study uses 137Cs measurements, sediment source fingerprinting and continuous turbidity records of four hydrological years (2004-2005 to 2007-2008) to quantify the individual components of the budget. A large proportion of the material mobilized from cultivated fields without conservation practices (gross erosion was 775 t yr-1; 1,270 t km-2 yr-1) was, however, subsequently deposited either within the field of origin (112 t yr-1; 180 t km-2 yr-1) or at intermediate locations between the source field and the channel network (field-to-channel conveyance loss was 591 t yr-1; 1,090 t km-2 yr-1). The estimates of sediment accumulation rates on the floodplain in the lower reaches of the catchment indicate that the mean sedimentation rate was 0.47 g cm-2 yr-1. This value was extrapolated to the total area of the floodplain to estimate a total annual conveyance loss or storage of 150 t yr-1. Monitoring at the catchment outlet over the study period indicated a mean annual suspended sediment yield of 7 t km-2 yr-1. The sum of the estimates of sediment yield and floodplain storage (157 t yr-1) was taken to represent the total annual input of suspended sediment to the channel system. This value was subsequently apportioned using the information provided by the fingerprinting investigation, to estimate the mass of sediment reaching the channel network from cultivated fields and from eroding channel banks. Thus the annual contribution from channel banks was estimated to be 84 t yr-1. In the case of the contributions from cultivated fields, the estimates obtained were, as expected, significantly less than the values of net soil loss from these zones provided by the 137Cs measurements due to conveyance losses associated to field-to-channel conveyance loss. The overall sediment delivery ratios (<1%) indicate that approximately 99% of the sediment mobilized by erosion within the Can Revull catchment is subsequently deposited before reaching the monitoring station. As such, the low sediment outputs from the study catchment should be seen as reflecting the importance of conveyance losses and storage rather than a lack of sediment mobilization from the catchment surface, although part of the catchment headwaters was modified historically by means of terraces and transverse walls to prevent erosion.

Comparison of Radiocarbon Ages of Sediments, Plants, and Shells From Coastal Lakes in North Florida

NASA Astrophysics Data System (ADS)

Wang, Y.; Das, O.; Liu, J.; Xu, X.; Roy, R.; Donoghue, J. F.; Means, G. H.

2017-12-01

Coastal lakes sediments are valuable archives of paleo-hurricanes and environmental changes during the late Quaternary provided that they can be accurately dated. Here, we report new radiocarbon (14C) dates derived from various organic and inorganic substrates, including bulk sediment organic matter, plants, shells, particulate organic matter (POM) and dissolved organic matter (DOM), from three coastal lakes in Florida, and compare these ages to evaluate the "reservoir effect" on 14C dating of both organic and inorganic carbon in these lakes. Bulk sediment organic matter yielded consistently older 14C ages than contemporaneous plants and shell fragments, indicating significant radiocarbon deficiencies in sedimentary organic matter in these coastal lakes, caused by influx of old organic carbon from terrestrial sources (such as soils and ancient peat deposits) in the watershed. Several reversals are observed in the 14C ages of bulk sediment organic matter in sediment cores from these lakes, indicating that input of aged organic matter from terrestrial sources into these lakes can vary considerably over time. DOM and POM samples collected at different times also yielded variable 14C signatures, further confirming the temporal variability in the contribution of old organic carbon from terrestrial sources to the lakes. The 14C age discrepancy between bulk sediment organic matter and co-occurring plant fragments or shells varies from less than one hundred years to nearly three thousand years in sediment cores examined in this study. The results show that 14C ages obtained from bulk sediment organic matter in these coastal lakes are unreliable. Analyses of both modern and fossil shells from one of the lakes suggest that the 14C reservoir effect on inorganic carbon in the lake is small and thus freshwater shells (if preserved in the sediment cores) may serve as a good substrate for 14C dating in the absence of plant fragments. However, unidentifiable shell fragments, especially those associated with sand pockets (or sand layers), in coastal lake sediment cores are not suitable for 14C dating as they are likely of marine origin and affected by significant marine 14C reservoir effect.

Sediment Source Analysis at Malakoff Diggins State Historic Park, California

NASA Astrophysics Data System (ADS)

Ward, A. J., IV; Monohan, C.; Matiasek, S. J.; Alpers, C. N.; Curtis, J.; Campbell, K. M.; Roth, D. A.; Howle, J.

2016-12-01

This study aims to identify the sources of suspended sediment and trace metals which are discharged during storm events into Humbug Creek from Malakoff Diggins State Historic Park (MDSHP) in Nevada County, California. MDSHP includes a pit where approximately 32,000,000 cubic meters of auriferous Eocene gravel was mined by hydraulic and dredging methods during 1866-1884 and 1893-1910. High erosion rates within the pit contribute to water-quality impairment downstream; Humbug Creek is listed as an impaired water body under section 303(d) of the Clean Water Act because of suspended sediment, copper, mercury, and zinc. Sediment fingerprinting techniques (mineralogy and geochemistry) are being used to identify stratigraphic units in the pit responsible for delivering the greatest volume of sediment to the pit drain at Hiller Tunnel, which flows to Humbug Creek. In-situ sediment samples were collected in 2015 along four vertical transects located in the mine pit. Additionally, surface water samples were collected during 2015 and 2016 within the pit and Hiller Tunnel, targeting drainage networks below the in-situ sampling sites. In-situ and suspended sediment samples were analyzed for grain-size distribution, X-ray diffraction (XRD) to obtain quantitative mineralogy, inductively coupled plasma - mass spectrometry (ICP-MS) for trace elements, and inductively coupled plasma - optical emission spectroscopy (ICP-OES) for major elements. Preliminary XRD data indicate that the fine suspended sediment in Hiller Tunnel is composed predominantly of kaolinite and halloysite, with minor smectite, illite, and muscovite. Kaolinite is abundant in many of the samples from the in-situ vertical transects, but relatively few stratigraphic units have abundant halloysite. Quantitative erosion rates from a time series of terrestrial LiDAR measurements (2014-16) and from historical aerial photos will help to refine possible scenarios regarding sediment sources within the pit. Chemical and physical characterization of the in-situ sediments may reveal key indicators, or fingerprints, which will allow for a more efficient application of mitigation efforts in MDSHP by identifying which stratigraphic units are delivering high amounts of sediment to Humbug Creek.

Metagenomics in methane seep detection and studies of the microbial methane sediment filter

NASA Astrophysics Data System (ADS)

Gunn Rike, Anne; Håvelsrud, Othilde Elise; Haverkamp, Thomas; Kristensen, Tom; Jakobsen, Kjetill

2013-04-01

Metanotrophic prokaryotes with their capacity to oxidize methane to biomass and CO2 contribute considerably in reduction of the global methane emission from oceans. Metagenomic studies of seabed sediments represent a new approach to detect marine methane seeps and to study whether the inhabiting microbial consortium represent a microbial methane filter. We have used next generation high throughput DNA sequencing technology to study microbial consortia and their potential metabolic processes in marine sediment samples from the Håkon Mosby mud volcano (HMMV) in the Barents Sea, the Tonya Seep in the Coal Oil Point area in California and from the pockmarked area at the Troll oil and gas field in the North Sea. Annotation of archaeal reads from the HMMV metagenome resulted in hits to all enzymes supposed to be involved in the anaerobic oxidation of methane (AOM) carried out by anaerobic methanotrophic archaea (ANME). The presence of several ANME taxa at HMMV has previously been well described (1). The stratification analysis of the Tonya seep sediment showed that both aerobic and anaerobic methanotrophs were present at both layers investigated, although total archaea, ANME-1, ANME-2 and ANME-3 were overabundant in the deepest layer. Several sulphate reducing taxa (possibly syntrophic ANME partners) were detected. The Tonya Seep sediment represent a robust methane filter where presently dominating methanotrophic taxa could be replaced by less abundant methanotrophs should the environmental conditions change (2). In the Troll pockmarked sediments several methanotrophic taxa including ANME-1, ANME-2 and candidate division NC10 were detected although there was an overabundance of autotrophic nitrifiers (e.g. Nitrosopumilis, Nitrococcus, Nitrospira) using CO2 as the carbon source. Methane migrating upwards through the sediments is probably oxidized to CO2 in AOM resulting in an upward CO2 flux. The CO2 entering the seafloor may contribute to maintain the pockmark structure and represent a carbon source for the autotrophic nitrifying community. In this way the sediments at Troll probably contributes to reduce the methane emissions to the water body and further to the atmosphere (3). References: 1) Niemann H, Lösekann T, Boetius A, Kort R, Amann R. Diversity and distribution of methanotrophic archaea at cold seeps. Appl Environ Microbiol 2005, 71(1), 467-479. 2) Håvelsrud, O. E., Haverkamp, T.H.A., Kristensen, T., Jakobsen, K.S. and Rike A.G. Metagenomic study of methane oxidation in Coal Oil Point seep sediments. BMC Microbiology 2011, 11:221 3) Håvelsrud OE, Haverkamp THA., Kristensen T, Jakobsen KS and Rike AG. Metagenomic and geochemical characterization of pockmarked sediments overlaying the Troll petroleum reservoir in the North Sea. BMC Microbiology 2012, 12:203

Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years.

PubMed

de Rezende, Júlia Rosa; Kjeldsen, Kasper Urup; Hubert, Casey R J; Finster, Kai; Loy, Alexander; Jørgensen, Bo Barker

2013-01-01

Patterns of microbial biogeography result from a combination of dispersal, speciation and extinction, yet individual contributions exerted by each of these mechanisms are difficult to isolate and distinguish. The influx of endospores of thermophilic microorganisms to cold marine sediments offers a natural model for investigating passive dispersal in the ocean. We investigated the activity, diversity and abundance of thermophilic endospore-forming sulfate-reducing bacteria (SRB) in Aarhus Bay by incubating pasteurized sediment between 28 and 85 °C, and by subsequent molecular diversity analyses of 16S rRNA and of the dissimilatory (bi)sulfite reductase (dsrAB) genes within the endospore-forming SRB genus Desulfotomaculum. The thermophilic Desulfotomaculum community in Aarhus Bay sediments consisted of at least 23 species-level 16S rRNA sequence phylotypes. In two cases, pairs of identical 16S rRNA and dsrAB sequences in Arctic surface sediment 3000 km away showed that the same phylotypes are present in both locations. Radiotracer-enhanced most probable number analysis revealed that the abundance of endospores of thermophilic SRB in Aarhus Bay sediment was ca. 10(4) per cm(3) at the surface and decreased exponentially to 10(0) per cm(3) at 6.5 m depth, corresponding to 4500 years of sediment age. Thus, a half-life of ca. 300 years was estimated for the thermophilic SRB endospores deposited in Aarhus Bay sediments. These endospores were similarly detected in the overlying water column, indicative of passive dispersal in water masses preceding sedimentation. The sources of these thermophiles remain enigmatic, but at least one source may be common to both Aarhus Bay and Arctic sediments.

Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years

PubMed Central

de Rezende, Júlia Rosa; Kjeldsen, Kasper Urup; Hubert, Casey R J; Finster, Kai; Loy, Alexander; Jørgensen, Bo Barker

2013-01-01

Patterns of microbial biogeography result from a combination of dispersal, speciation and extinction, yet individual contributions exerted by each of these mechanisms are difficult to isolate and distinguish. The influx of endospores of thermophilic microorganisms to cold marine sediments offers a natural model for investigating passive dispersal in the ocean. We investigated the activity, diversity and abundance of thermophilic endospore-forming sulfate-reducing bacteria (SRB) in Aarhus Bay by incubating pasteurized sediment between 28 and 85 °C, and by subsequent molecular diversity analyses of 16S rRNA and of the dissimilatory (bi)sulfite reductase (dsrAB) genes within the endospore-forming SRB genus Desulfotomaculum. The thermophilic Desulfotomaculum community in Aarhus Bay sediments consisted of at least 23 species-level 16S rRNA sequence phylotypes. In two cases, pairs of identical 16S rRNA and dsrAB sequences in Arctic surface sediment 3000 km away showed that the same phylotypes are present in both locations. Radiotracer-enhanced most probable number analysis revealed that the abundance of endospores of thermophilic SRB in Aarhus Bay sediment was ca. 104 per cm3 at the surface and decreased exponentially to 100 per cm3 at 6.5 m depth, corresponding to 4500 years of sediment age. Thus, a half-life of ca. 300 years was estimated for the thermophilic SRB endospores deposited in Aarhus Bay sediments. These endospores were similarly detected in the overlying water column, indicative of passive dispersal in water masses preceding sedimentation. The sources of these thermophiles remain enigmatic, but at least one source may be common to both Aarhus Bay and Arctic sediments. PMID:22832348

Multivariate geostatistical analysis and source identification of heavy metals in the sediment of Poyang Lake in China.

PubMed

Dai, Lijun; Wang, Lingqing; Li, Lianfang; Liang, Tao; Zhang, Yongyong; Ma, Chuanxin; Xing, Baoshan

2018-04-15

Heavy metals in lake sediment have become a great concern because their remobilization has frequently occurred under hydrodynamic disturbance in shallow lakes. In this study, heavy metals (Cr, Cu, Cd, Pb, and Zn) concentrations in the surface and core sediments of the largest freshwater lake in China, Poyang Lake, were investigated. Geostatistical prediction maps of heavy metals distribution in the surface sediment were completed as well as further data mining. Based on the prediction maps, the ranges of Cr, Cu, Cd, Pb, and Zn concentrations in the surface sediments of the entire lake were 96.2-175.2, 38.3-127.6, 0.2-2.3, 22.5-77.4, and 72.3-254.4mg/kg, respectively. A self-organizing map (SOM) was applied to find the inner element relation of heavy metals in the sediment cores. K-means clustering of the self-organizing map was also completed to define the Euclidian distance of heavy metals in the sediment cores. The geoaccumulation index (I geo ) for Poyang Lake indicated a varying degree of heavy metal contamination in the surface sediment, especially for Cu. The heavy metal contamination in the sediment profiles had similar pollution levels as those of surface sediment, except for Cd. Correlation matrix mapping and principal component analysis (PCA) were used to support the idea that Cr, Pb, and Zn may be mainly derived from both lithogenic and human activities, such as atmospheric and river inflow transportation, whereas Cu and Cd may be mainly contributed from anthropogenic sources, such as mining activities and fertilizer application. Copyright © 2017 Elsevier B.V. All rights reserved.

Sources and timing of anthropogenic pollution in the Ensenada de San Simon (inner Ria de Vigo), Galicia, NW Spain: an application of mixture-modelling and nonlinear optimization to recent sedimentation.

PubMed

Howarth, Richard J; Evans, Graham; Croudace, Ian W; Cundy, Andrew B

2005-03-20

The Ensenada de San Simon is the inner part of the Ria de Vigo, one of the major mesotidal rias of the Galician coast, NW Spain. The geochemistry of its bottom sediments can be accounted for in terms of both natural and anthropogenic sources. Mixture-modelling enables much of the Cr, Ni, V, Cu, Pb and Zn concentrations of the bottom and subaqueous sediments to be explained by sediment input from the river systems and faecal matter from manmade mussel rafts. The compositions and relative contributions of additional, unknown, sources of anomalous heavy-metal concentrations are quantified using constrained nonlinear optimization. The pattern of metal enrichment is attributed to: material carried in solution and suspension in marine water entering the Ensenada from the polluted industrial areas of the adjacent Ria de Vigo; wind-borne urban dusts and/or vehicular emissions from the surrounding network of roads and a motorway road-bridge over the Estrecho de Rande; industrial and agricultural pollution from the R. Redondela; and waste from a former ceramics factory near the mouth of the combined R. Oitaben and R. Verdugo. Using (137)Cs dating, it is suggested that heavy metal build-up in the sediments since the late 1970s followed development of inshore fisheries and introduction of the mussel rafts (ca. 1960) and increasing industrialisation.

Biological and physical controls on the flux and characteristics of sinking particles on the Northwest Atlantic margin

NASA Astrophysics Data System (ADS)

Hwang, Jeomshik; Manganini, Steven J.; Park, JongJin; Montluçon, Daniel B.; Toole, John M.; Eglinton, Timothy I.

2017-06-01

matter characteristics and radiocarbon contents of organic carbon (OC) were examined on sinking particle samples intercepted at three nominal depths of 1000 m, 2000 m, and 3000 m (˜50 m above the seafloor) during a 3 year sediment trap program on the New England slope in the Northwest Atlantic. We have sought to characterize the sources of sinking particles in the context of vertical export of biogenic particles from the overlying water column and lateral supply of resuspended sediment particles from adjacent margin sediments. High aluminum (Al) abundances and low OC radiocarbon contents indicated contributions from resuspended sediment which was greatest at 3000 m but also significant at shallower depths. The benthic source (i.e., laterally supplied resuspended sediment) of opal appears negligible based on the absence of a correlation with Al fluxes. In comparison, CaCO3 fluxes at 3000 m showed a positive correlation with Al fluxes. Benthic sources accounted for 42 ˜ 63% of the sinking particle flux based on radiocarbon mass balance and the relationship between Al flux and CaCO3 flux. Episodic pulses of Al at 3000 m were significantly correlated with the near-bottom current at a nearby hydrographic mooring site, implying the importance of current variability in lateral particle transport. However, Al fluxes at 1000 m and 2000 m were coherent but differed from those at 3000 m, implying more than one mode of lateral supply of particles in the water column.

GLORIA side-scan imagery of Aleutian basin, Bering Sea slope and Abyssal plain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, P.R.; Cooper, A.K.; Gardner, J.V.

1987-05-01

During July-September 1986, about 700,000 km/sup 2/ of continental slope and abyssal plain of the Aleutian basin, Bering Sea, were insonified with GLORIA (Geological Long Range Inclined Asdic) side-scane sonar. A sonar mosaic displays prominent geomorphic features including the massive submarine canyons of the Beringian and the northern Aleutian Ridge slopes and shows well-defined sediment patterns including large deep-sea channels and fan systems on the Aleutian basin abyssal plain. Dominant erosional and sediment transport processes on both the Beringian and the Aleutian Ridge slopes include varieties of mass movement that range from small debris flows and slides to massive slidesmore » and slumps of blocks measuring kilometers in dimension. Sediment-flow patterns that appear to be formed by sheet flow rather than channelized flow extend basinward from the numerous canyons and gullies that incise the slopes of the Beringian margin and of Bowers Ridge and some places along the Aleutian Ridge. These Beringian and Bowers canyon sediment sources, however, appear to have contributed less modern sediment to the Aleutian basin than the large, well-defined channel systems that emanate from Bering, Umnak, and Amchitka submarine canyons and extend for several hundred kilometers across the abyssal plain. This GLORIA imagery emphasizes the important contribution of the Aleutian Ridge to modern sedimentation in the deep Bering Sea.« less

Understanding sediment sources in a peri-urban Mediterranean catchment using geochemical tracers

NASA Astrophysics Data System (ADS)

Ferreira, Carla; Walsh, Rory; Kikuchi, Ryunosuke; Blake, Will

2016-04-01

One of the main physical environmental impacts of urbanization is an increase in suspended sediment concentrations and loads, particularly in the constructional phase. Impacts in peri-urban catchments characterized by a mosaic of urban and non-urban landscape elements with varying roles in acting as sources and sinks of overland flow and slope wash have received little attention, particularly in Mediterranean environments. The present study uses a sediment 'fingerprinting' approach to determine the main sediment sources in the peri-urban Ribeira dos Covões catchment (6.2km2) in Portugal and how they change during storm events following contrasting antecedent weather. The catchment, rural until 1972, underwent discontinuous urbanization in 1973-1993, followed by an urban consolidation phase. Currently, its land-use is a complex mosaic of woodland (56%), urban (40%) and agricultural (4%) land parcels. Distinct urban patterns include some well-defined urban residential centres, but also areas of discontinuous urban sprawl. Since 2010, a major road was built and an enterprise park has been under construction, covering 1% and 5% of the catchment, respectively. The catchment has a Mediterranean climate. The geology comprises sandstone (56%), limestone (41%) and alluvial deposits (3%). Soils are generally deep (>3.0m), but shallow (<0.4m) on steeper limestone terrain. The catchment has an average slope of 9° , but includes steep slopes of up to 46° . The sediment fingerprinting methodology involved characterizing the chemical properties of sediments from individual upstream sub-catchments and comparing these to the properties of downstream transported fluvial material. Three fine bed-sediment sampling surveys were carried out after (i) a long dry period (21/09/2012), (ii) a winter storm of relatively high rainfall intensity (23.2mm day-1) (19/02/2015), and (iii) after several storms in Spring (22/04/2015). All samples were oven-dried (at 38° C) and sieved to obtain different particle size fractions (0.125-2.000mm, 0.063-0.125mm and <0.063mm). Seventeen stream sites were sampled plus a sample of sediment from a road surface immediately it entered the stream network. The elemental composition (40 elements) of each size fraction was assessed using a Niton X-ray fluorescence elemental analyser. Results show that rock type has a profound influence on the geochemical properties of bed-sediments. Catchment outlet sediment collected after the summer and a storm of high rainfall intensity following dry weather displayed geochemical properties closer to those of sediment from sandstone sub-catchments, and in particularly sediment from the enterprise park under construction. After the storm that followed very wet weather, however, limestone areas became of much greater significance as sediment sources, probably because of the high soil saturation. At limestone stream sites receiving runoff from the newly constructed road, fine bed-sediment geochemistry was found to be similar to that of road sediment, indicating a high contribution of this source. These results are supported by spatio-temporal differences in streamflow and suspended sediment concentrations at instrumented monitoring stations. It is concluded that this methodology represents a potentially useful tool to enable river managers to detect and assess sediment sources in urbanized and partly urbanized catchments, and to supporting them in designing and implementing effective land-use mosaics and site-specific measures to mitigate erosion.

Quantifying the provenance of aeolian sediments using multiple composite fingerprints

NASA Astrophysics Data System (ADS)

Liu, Benli; Niu, Qinghe; Qu, Jianjun; Zu, Ruiping

2016-09-01

We introduce a new fingerprinting method that uses multiple composite fingerprints for studies of aeolian sediment provenance. We used this method to quantify the provenance of sediments on both sides of the Qinghai-Tibetan Railway (QTR) in the Cuona Lake section of the Tibetan Plateau (TP), in an environment characterized by aeolian and fluvial interactions. The method involves repeatedly solving a linear mixing model based on mass conservation; the model is not limited to spatial scale or transport types and uses all the tracer groups that passed the range check, Kruskal-Wallis H-test, and a strict analytical solution screening. The proportional estimates that result from using different composite fingerprints are highly variable; however, the average of these fingerprints has a greater accuracy and certainty than any single fingerprint. The results show that sand from the lake beach, hilly surface, and gullies contribute, respectively, 48%, 31% and 21% to the western railway sediments and 43%, 33% and 24% to the eastern railway sediments. The difference between contributions from various sources on either side of the railway, which may increase in the future, was clearly related to variations in local transport characteristics, a conclusion that is supported by grain size analysis. The construction of the QTR changed the local cycling of materials, and the difference in provenance between the sediments that are separated by the railway reflects the changed sedimentary conditions on either side of the railway. The effectiveness of this method suggests that it will be useful in other studies of aeolian sediments.

Characteristics of bioavailable organic phosphorus in sediment and its contribution to lake eutrophication in China.

PubMed

Ni, Zhaokui; Wang, Shengrui; Wang, Yuemin

2016-12-01

This study aims to establish the relative importance of sediment organic phosphorus (P o ) to the total P and the major classes of organic molecules that contribute to sediment P o , determined by measuring their susceptibility to enzymatic hydrolysis, across a suite of lakes ranging from oligotrophic to eutrophic status. The results showed that P o accounted for 21-60% of total P, and bioavailable P o accounted for 9-34% of P o in the sediments. The bioavailable P o includes mainly labile (H 2 O-P o ) and moderately labile (NaOH-P o ) P forms. For H 2 O-P o (accounting for only1.4% of P o ), 53% (average) was labile monoester P, 28% was diester P and 17% was phytate-like P. For NaOH-P o (accounting for 9-33% of P o ), 32% was labile monoester P, 33% was phytate-like P and 18% was diester P. The composition of bioavailable P o , determined by enzyme assays, was related to the lake nutrient levels, which implies that sediment bioavailable P o could act as an effective indicator for lake eutrophic status. With the increase of lake nutrient levels, bioavailable P o content and alkaline phosphatase activity in the sediment all increased, indicating that P o represents an important and bioavailable source of P that increases with eutrophication, and could contribute to internal loading and resistance of eutrophic lakes to remediation. This implies that eutrophic lakes would maintain long-term eutrophic status and algal bloom phenomena even after the external input of P was controlled and the total P concentration of water has declined. Thus, in order to reduce the release risk of sediment P more efficiently and effectively, sediment P control technique should focus not only on reducing the total P and inorganic P, but should also pay close attention to the removal of bioavailable P o . Copyright © 2016 Elsevier Ltd. All rights reserved.

Distribution, behavior, and transport of inorganic and methylmercury in a high gradient stream

USGS Publications Warehouse

Flanders, J.R.; Turner, R.R.; Morrison, T.; Jensen, R.; Pizzuto, J.; Skalak, K.; Stahl, R.

2010-01-01

Concentrations of Hg remain elevated in physical and biological media of the South River (Virginia, USA), despite the cessation of the industrial use of Hg in its watershed nearly six decades ago, and physical characteristics that would not seem to favor Hg(II)-methylation. A 3-a study of inorganic Hg (IHg) and methylmercury (MeHg) was conducted in physical media (soil, sediment, surface water, porewater and soil/sediment extracts) to identify non-point sources, transport mechanisms, and potential controls on Hg(II)-methylation. Data collected from surface water and sediment indicate that the majority of the non-point sources of IHg to the South River are within the first 14. km downstream from the historic point source. Partitioning data indicate that particle bound IHg is introduced in this reach, releasing dissolved and colloidal bound IHg, which is transported downstream. Extraction experiments revealed that floodplain soils released a higher fraction of their IHg content in aqueous extractions than fine-grained sediment (FGS). Based on ultrafiltration [<5000 nominal molecular weight cutoff (NMWC)] the majority of soil IHg released was colloidal in nature, providing evidence for the continued evolution of IHg for Hg(II)-methylation from soil. Strong seasonal patterns in MeHg concentrations were observed in surface water and sediment. The highest concentrations of MeHg in surface water were observed at moderate temperatures, suggesting that other factors limit net Hg(II)-methylation. Seasonal changes in sediment organic content and the fraction of 1. N KOH-extractable THg were also observed and may be important factors in controlling net Hg(II)-methylation rates. Sulfate concentrations in surface water are low and the evidence suggests that Fe reduction may be an important Hg(II)-methylation process. The highest sediment MeHg concentrations were observed in habitats with large amounts of FGS, which are more prevalent in the upper half of the study area due to the lower hydrologic gradient and agricultural impacts. Past and present land use practices and other geomorphologic controls contribute to the erosion of banks and accumulation of fine-grained sediment in this section of the river, acting as sources of IHg. ?? 2010 Elsevier Ltd.

Level, source identification, and risk analysis of heavy metal in surface sediments from river-lake ecosystems in the Poyang Lake, China.

PubMed

Zhang, Hua; Jiang, Yinghui; Ding, Mingjun; Xie, Zhenglei

2017-09-01

The concentrations, sources, and risks of heavy metals (Fe, Al, Mn, Cr, Co, Ni, Cu, Zn, As, Cd, W, Pb, and Tl) in sediments in five river-lake ecosystems in the Poyang Lake region were studied. The concentrations of the heavy metals varied spatially, with most of the highest concentrations in the Raohe river-lake ecosystem (RH). All heavy metals except As, Cd, W, and Tl were enriched in sediments possessing high total organic carbon contents or in finer sediments. Based on enrichment factors and statistical methods, it was found that Cd in sediments in the Xiushui (XS), Ganjiang (GJ), Xinjiang (XJ) river-lake ecosystems, and RH; Mn in the XS, GJ, and RH; and W in the XS and GJ were greatly affected by anthropogenic inputs. Moreover, the origins of Cu, Zn, and As require more attention due to the high concentrations found. The high enrichment factor of Cd in the sediments indicated that this metal might cause significant pollution in the environment. The results of the modified potential ecological risk index revealed that the XS, GJ, RH, and XJ were at considerable ecological risk, while the sediments in the Fuhe river-lake ecosystem (FH) were at moderate ecological risk, with Cd contributing the highest proportion of risk. The hazard score fundamentally validated the modified potential ecological risk analysis and revealed a mean toxicity of 57.80% to the benthic organisms in the RH.

Geochemical characteristics of Holocene laminated sapropel (unit II) and underlying lacustrine unit III in the Black Sea

USGS Publications Warehouse

Dean, Walter E.; Arthur, Michael A.

2011-01-01

eg 1 of the 1988 R/V Knorr expeditions to the Black Sea recovered 90 gravity and box cores. The longest recovery by gravity cores was about 3 meters, with an average of about 2.5 meters, recovering all of the Holocene and upper Pleistocene sections in the Black Sea. During the latest Pleistocene glaciation, sea level dropped below the 35-meters-deep Bosporus outlet sill of the Black Sea. Therefore throughout most of its history the Black Sea was a lake, and most of its sediments are lacustrine. The oldest sediments recovered (older than 8,000 calendar years) consist of massive to coarsely banded lacustrine calcareous clay designated as lithologic Unit III, generally containing less than 1 percent organic carbon (OC). The base of overlying Unit II marks the first incursion of Mediterranean seawater into the Black Sea, and the onset of bottom-water anoxia about 7,900 calendar years. Unit II contains as much as 15 percent OC in cores from the deepest part of the Black Sea (2,200 meters). The calcium carbonate (CaCO3) remains of the coccolith Emiliania huxleyi form the distinctive white laminae of overlying Unit I. The composition of Unit III and Unit II sediments are quite different, reflecting different terrigenous clastic sources and increased contributions from hydrogenous and biogenic components in anoxic Unit II sapropel. In Unit II, positive covariance between OC and three trace elements commonly concentrated in OC-rich sediments where sulfate reduction has occurred (molybdenum, nickel, and vanadium) and a nutrient (phosphorus) suggest a large marine source for these elements although nickel and vanadium also have a large terrigenous clastic source. The marine sources may be biogenic or hydrogenous. A large biogenic source is also suggested for copper and cobalt. Because abundant pyrite forms in the water column and sediments of the Black Sea, we expected to find a large hydrogenous iron component, but a strong covariance of iron with aluminum suggests that the dominant source of iron is from terrigenous clastic material. Most elements in lacustrine Unit III sediments have a strong covariance with Al indicating a very dominant terrigenous source. In Unit II, some elements, especially nickel, molybdenum, vanadium, and zinc, do not correlate with aluminum and have concentrations well above terrigenous clastic material, indicating a marine source.

Isotopic identification of natural vs. anthropogenic lead sources in marine sediments from the inner Ría de Vigo (NW Spain).

PubMed

Álvarez-Iglesias, P; Rubio, B; Millos, J

2012-10-15

San Simón Bay, the inner part of the Ría de Vigo (NW Spain), an area previously identified as highly polluted by Pb, was selected for the application of Pb stable isotope ratios as a fingerprinting tool in subtidal and intertidal sediment cores. Lead isotopic ratios were determined by inductively coupled plasma mass spectrometry on extracts from bulk samples after total acid digestion. Depth-wise profiles of (206)Pb/(207)Pb, (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb and (208)Pb/(207)Pb ratios showed, in general, an upward decrease for both intertidal and subtidal sediments as a consequence of the anthropogenic activities over the last century, or centuries. Waste channel samples from a nearby ceramic factory showed characteristic Pb stable isotope ratios different from those typical of coal and petrol. Natural isotope ratios from non-polluted samples were established for the study area, differentiating sediments from granitic or schist-gneiss sources. A binary mixing model employed on the polluted samples allowed estimating the anthropogenic inputs to the bay. These inputs represented between 25 and 98% of Pb inputs in intertidal samples, and 9-84% in subtidal samples, their contributions varying with time. Anthropogenic sources were apportioned according to a three-source model. Coal combustion-related emissions were the main anthropogenic source Pb to the bay (60-70%) before the establishment of the ceramic factory in the area (in the 1970s) which has since constituted the main source (95-100%), followed by petrol-related emissions. The Pb inputs history for the intertidal area was determined for the 20th century, and, for the subtidal area, the 19th and 20th centuries. Copyright © 2012 Elsevier B.V. All rights reserved.

Long-term controls on the composition of particulate organic carbon buried offshore from the Waipaoa River, North Island, New Zealand

NASA Astrophysics Data System (ADS)

Leithold, E. L.; Blair, N. E.; Childress, L. B.; Brulet, B.

2009-12-01

In the Waipaoa watershed on the North Island of New Zealand, as in many small mountainous watersheds around the world, high sediment yields are accommodated by the weathering and mass wasting of bedrock as well as of its mantle of soil and vegetation. Investigation of both the contemporary Waipaoa system and the sedimentary record preserved in adjacent marine depocenters reveals that these three sources of sediment have also been the primary sources of riverine POC throughout the watershed’s Holocene history, but that their relative roles have varied as a function of environmental perturbations. Mass balance calculations using stable and radiogenic carbon isotopic ratios of organic matter associated with both bulk sediments and clay-sized isolates point to a large and persistent contribution of kerogen to POC in the Waipaoa system. This material has accumulated on the continental margin along with terrestrial plant-derived OC, much of which apparently had a short residence time in the watershed. The accelerated contribution of OC-poor volcanic tephra to the Waipaoa sediment load beginning about 4000 years ago led to dilution of both the kerogen and plant fraction, and ultimately to enhanced marine OC burial on the shelf via production of new mineral surface area and sorption from porewaters. Beginning around 700 years BP, anthropogenic influences have left their mark on the watershed and offshore record, including the introduction of a pulse of fine-grained charcoal from biomass burning. Deforestation of the headwaters has led to more widespread shallow landsliding and to the development of large gully complexes incised into tectonically crushed mudstones. The increased kerogen flux due to chronic gully erosion is apparent in the offshore record, but its impact on the composition and age of OC buried on the continental shelf is muted compared to the increase in riverine sediment discharge and sediment accumulation observed on the margin.

An analysis of organic matter sources for surface sediments in the central South Yellow Sea, China: evidence based on macroelements and n-alkanes.

PubMed

Zhang, Shengyin; Li, Shuanglin; Dong, Heping; Zhao, Qingfang; Lu, Xinchuan; Shi, Ji'an

2014-11-15

By analyzing the composition of n-alkane and macroelements in the surface sediments of the central South Yellow Sea of China, we evaluated the influencing factors on the distribution of organic matter. The analysis indicates that the distribution of total organic carbon (TOC) was low in the west and high in the east, and TOC was more related to Al2O3 content than medium diameter (MD). The composition of n-alkanes indicated the organic matter was mainly derived from terrestrial higher plants. Contributions from herbaceous plants and woody plants were comparable. The comprehensive analysis of the parameters of macroelements and n-alkanes showed the terrestrial organic matter in the central South Yellow Sea was mainly from the input of the modern Yellow River and old Yellow River. However, some samples exhibited evident input characteristics from petroleum sources, which changed the original n-alkanes of organic matter in sediments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mineralogical and geochemical features of alluvial sediments from the Lobo watershed (Southern Cameroon): Implications for rutile exploration

NASA Astrophysics Data System (ADS)

Nyobe, Jules Mbanga; Sababa, Elisé; Bayiga, Elie Constantin; Ndjigui, Paul-Désiré

2018-03-01

This paper is focused on the morphological, mineralogical, and geochemical features of alluvial sediments from the Neoproterozoic Pan-African belt to explore rutile. The fine-grained sediments, which contain a large proportion of rutile, are made up of quartz, rutile, zircon, brookite, tourmaline, andalusite, and kyanite. The high SiO2 and TiO2 contents highlight the predominance of silica minerals in the alluvia from the humid tropical zone. La/Sc, La/Co, Th/Sc and Zr/Cr ratios reflect the contribution of felsic and mafic sources. The highest Ti contents, which occur at the outlet of the Lobo watershed, indicate the resistance of rutile. The REE distribution could be linked to the heavy mineral sorting. The low (La/Yb)N ratios and high Zr contents are attributed to the high proportion of zircon. Chondrite-normalized REE patterns indicate high felsic sources, which are the regional rocks. Ultimately, the Yaoundé Group constitutes a favorable potential target for further rutile exploration.

Sources markers in aerosols, oceanic particles and sediments

NASA Astrophysics Data System (ADS)

Saliot, A.

2009-02-01

This review presents some diagnostic criteria used for identifying and quantifying terrestrial organic matter inputs to the ocean. Coupled to the isotopic composition of total organic carbon, the analysis of stable biomarkers permits to trace higher plant contributions in aerosols, dusts, sedimenting particles and dissolved phase in the water column and ultimately in recent and ancient sediments and soils. Some applications are presented, based on the analysis of n-alkyl compounds by a combination of gas chromatography and mass spectrometry (n-alkanes, n-alkanols, n-alkanoic acids and wax esters). Another approach has been developed using the analysis of macromolecular compounds present in higher plants. Abundances of the phenolic compounds from lignin, benzene carboxylic acids obtained during cupric oxide oxidation, Curie pyrolysis are used to characterise terrestrial organic matter sources and inputs. Finally due to the importance of biomass burning in continent-ocean transfers, biomarkers are presented in the polycyclic aromatic hydrocarbon class and for monosaccharide derivatives from the breakdown of cellulose.

Baseline study on trace and rare earth elements in marine sediments collected along the Namibian coast.

PubMed

Orani, Anna Maria; Vassileva, Emilia; Wysocka, Irena; Angelidis, Michael; Rozmaric, Martina; Louw, Deon

2018-06-01

Namibia is a fast-growing country with extensive mineral extraction activities used in diamond, fluorspar, uranium, and metals production. To assess the impact of land based human activities on the Namibian coastal marine environment, 25 elements were analyzed in 22 surface sediments samples collected along the coast. After applying a variety of pollution assessment indices (Enrichment Factor, Igeo and Pollution Load Indexes) was concluded that As, Cd and Sb were considerably enriched in the sediments from several sites, while Cu, Pb and Zn showed very high enrichment near the Walvis Bay harbor. Pearson's correlation and Principal Component Analysis were used to investigate common metal sources. Additionally, the determination of Pb isotope ratios confirmed the contribution of land based human activities at Walvis Bay and Lüderitz as sources of pollution. The analysis of REEs did not reveal any important enrichment due to anthropogenic activities, but provides a needed baseline for further investigations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Trends in polychlorinated biphenyl concentrations in Hudson River water five years after elimination of point sources

USGS Publications Warehouse

Schroeder, R.A.; Barnes, C.R.

1983-01-01

Industrial discharge of polychlorinated biphenyls (PCBs) to the Hudson River from 1950 to the mid-1970 's has resulted in serious degradation of the water. Contaminated river-bottom sediments continue to contribute PCBs to the river water. Concentrations in the sediment range from several hundred micrograms per gram near the outfall to less than 10 micrograms per gram in the lower estuary. PCBs are supplied by bottom sediments to the overlying water by two mechanisms--desorption and resuspension. Because desorption is a relatively constant process, concentrations of PCBs decrease as water discharge increases. At high flow, however, scouring by turbulence causes resuspension of PCB-laden sediment. Transport rates indicate that most PCBs enter the water from the most contaminated sediments, which are within 20 kilometers of the outfall. Mean daily transport from the upper river (except during high discharges) has decreased from 10 kilograms in 1976 to 5 kilograms in the late 1970 's and to 1 kilogram in 1981. This decrease probably results from the burial of highly contaminated sediments by cleaner sediments originating upstream. (USGS)

Alkenone radiocarbon stratigraphy at high resolution continental marigin sites

NASA Astrophysics Data System (ADS)

Mollenhauer, G.; Eglinton, T.; Freudenthal, T.; Lamy, F.

2003-04-01

Radiocarbon stratigraphy is an essential tool for high resolution Late Quaternary paleoceanographic studies. For this purpose, radiocarbon ages of foraminifera have been extensively measured. Age models based on these measurements are commonly applied to a wide range of sediment proxy information, including the investigation of temporal leads and lags. The critical assumption made in these studies is that temporal coupling between foraminifera and other sediment constituents, including specific biomarkers of marine phytoplankton, e.g. alkenones, is maintained in the sediments. A recent study using coupled foraminifera and alkenone ages was conducted at a high sedimentation rate site situated at the Bermuda Rise sediment drift body. Ages of formanifera and alkenones differed by up to 8000 years. As an interpreation of these data, it was suggested that sediment constituents residing in different grain size fractions may have different current transport properties and may thus originate from different source areas separated by large geographical distances. Sediment retrieved from a site influenced by lateral advection would thus have to be regarded as a mixture of material from different sources. The time span between production and final deposition may be site dependent and remains largely unknown. Continental margins underlying high productivity areas are sites of high sediment accumulation. The major part of this sediment is believed to be biogenic and is produced in the overlying water column. Sediment particles are expected to be deposited rapidly at or near the site of production regardless of their size. To evaluate this premise, we have measured coupled radiocarbon ages of foraminifera, TOC and alkenones in samples taken from sediment cores retreived from three continental margin high accumulation rate sites. Cores from the Benguela upwelling system, the North West African upwelling system and from the Chilean margin high productivity area were chosen. All sites are characterized by high sedimentation rates (>15 cm/kyr). Variable current regimes prevailing at the individual sites may provide insight as to the factors controlling the sedimentation of fine grained particles as well as concerning source areas and residence time in bottom nepheloid layers. Paired foraminifera and alkenone ages provide important constraints on the interpretation of the proxy data obtained from each of the proxy carriers. In the future, alkenone temperatures combined with alkenone ages may thus also contribute to reconstruction of current regimes and trajectories.

Modern Sedimentation along the SE Bangladesh Coast Reveal Surprisingly Low Accumulation Rates

NASA Astrophysics Data System (ADS)

McHugh, C.; Mustaque, S.; Mondal, D. R.; Akhter, S. H.; Iqbal, M.

2016-12-01

Recent sediments recovered along the SE coast of Bangladesh, from Teknaf to Cox's Bazar and drainage basin analyses reveal sediment sources and very low sedimentation rates of 1mm/year. These low rates are surprisingly low given that this coast is adjacent to the Ganges-Brahmaputra Delta with a yearly discharge of 1GT. The Teknaf anticline (elevation 200 m), part of the western Burma fold-thrust belt dominates the topography extending across and along the Teknaf peninsula. It is thought to have begun evolving since the Miocene (Alam et al. 2003 & Allen et al. 2008). Presently the anticline foothills on the west are flanked by uplifted terraces, the youngest linked to coseismic displacement during the 1762 earthquake (Mondal et al. 2015), and a narrow beach 60-200 m in width. Petrography, semi-quantitative bulk mineralogy and SEM/EDX analyses were conducted on sediments recovered along the west coast from 1-4 m deep trenches and three 4-8 m deep drill holes. GIS mapping of drainage basins and quartz-feldspar-lithic (QFL) ternary plots based on grain counting show mixing of sediments from multiple sources: Himalayan provenance of metamorphic and igneous origin (garnet-mostly almandine, tourmaline, rutile, kyanite, zircon, sillimanite and clinopyroxene) similar to Uddin et al. (2007); Brahmaputra provenance of igneous and metamorphic origin (amphibole, epidote, plagioclase 40% Na and 60% Ca, apatite, ilmenite, magnetite, Cr-spinel and garnet-mostly grossular,) as indicated by Garzanti et al. (2010) & Rahman et al. (2016) and Burmese sources (cassiterite and wolframite) (Zaw 1990 & Searle et al. 2007). Low sedimentation rates are the result of two main factors: 1. Strong longshore currents from the south-east that interact with high tidal ranges as evidenced by the morphology of sand waves and ridge and runnel landforms along the beach. 2. Streams draining the Teknaf anticline are dry during the winter and during summer monsoon rains, the sediments bypass the narrow beach and are washed out offshore. These sedimentation patterns together with the offshore reversing monsoon circulation are shaping the coast by contributing to erosion, mixing of sediments and transporting minerals from the Burma drainage basin in the south.

Recycling Revisited: Where did all the Subducted Sediments go?

NASA Astrophysics Data System (ADS)

Hofmann, A. W.; Chauvel, C.; Lewin, E.; Kelemen, P. B.; Hacker, B. R.

2016-12-01

Several lines of reasoning have revived the idea [1] that subduction has recycled continent-derived sediments into the mantle on a massive scale. For example, well-known peaks in zircon ages have been reinterpreted as reflecting variable rates of crust destruction via erosion and sediment subduction [2]. In addition, assessment of the trace element budgets of subducted sediments and arc volcanics, as well as geological and geophysical studies of accretionary wedges have led to estimates that about one mass of present-day continental crust has been returned to the mantle [3]. If these ideas are correct, then recycled sedimentary components should be present in MORB and OIB sources. As previously established, Nb/U and 87Sr/86Sr are negatively correlated in all EM2-type OIBs, clearly indicating continental/sedimentary input. However, the MORB source reservoir, being depleted in incompatible elements, is particularly susceptible to "pollution" by subducted sediments. Chauvel et al. [4] modeled the Hf-Nd isotopic array of MORBs+OIBs and concluded that it requires the addition of up to 6 % subducted sediment. We revisit this issue and show that global MORBs show no decrease in Nb/U with increasing 87Sr/86Sr, ruling out extensive addition of recycled sediment into global MORB sources. Instead, the Hf-Nd array can be obtained by recycled alkali basalts derived from subducted seamounts and ocean islands, rather than sediments. Moreover, mantle plumes with clearly identifiable sediment input contribute less than 20% of the total plume flux. We conclude that most of the subducted sediment flux is not returned to the convecting mantle. Instead, its most plausible fate is to be underplated beneath existing continental crust via "relamination" [5]. These results imply that continental recycling is subordinate and the growth of the continental crust has been largely irreversible. [1] Armstrong, 1968, Rev. Geophys. 6, 175. [2] Hawkesworth et al., 2009, Science 323, 49. [3] Porter & White, 2009, Geochem. Geophys. Geosyst., 10, Q12016. Scholl & von Huene, 2007, GSA Memoir 200. [4] Chauvel et al., 2008, Nature Geosci. 1, 64. [5] Hacker et al., 2011, EPSL 307, 501. Kelemen & Behn, 2016 Nature Geosci. 9, 197.

Improvement of a free software tool for the assessment of sediment connectivity

NASA Astrophysics Data System (ADS)

Crema, Stefano; Lanni, Cristiano; Goldin, Beatrice; Marchi, Lorenzo; Cavalli, Marco

2015-04-01

Sediment connectivity expresses the degree of linkage that controls sediment fluxes throughout landscape, in particular between sediment sources and downstream areas. The assessment of sediment connectivity becomes a key issue when dealing with risk mitigation and priorities of intervention in the territory. In this work, the authors report the improvements made to an open source and stand-alone application (SedInConnect, http://www.sedalp.eu/download/tools.shtml), along with extensive applications to alpine catchments. SedInConnect calculates a sediment connectivity index as expressed in Cavalli et al. (2013); the software improvements consisted primarily in the introduction of the sink feature, i.e. areas that act as traps for sediment produced upstream (e.g., lakes, sediment traps). Based on user-defined sinks, the software decouples those parts of the catchment that do not deliver sediment to a selected target of interest (e.g., fan apex, main drainage network). In this way the assessment of sediment connectivity is achieved by taking in consideration effective sediment contributing areas. Sediment connectivity analysis has been carried out on several catchments in the South Tyrol alpine area (Northern Italy) with the goal of achieving a fast and objective characterization of the topographic control on sediment transfer. In addition to depicting the variability of sediment connectivity inside each basin, the index of connectivity has proved to be a valuable indicator of the dominant process characterizing the basin sediment dynamics (debris flow, bedload, mixed behavior). The characterization of the dominant process is of great importance for the hazard and risk assessment in mountain areas, and for choice and design of structural and non-structural intervention measures. The recognition of the dominant sediment transport process by the index of connectivity is in agreement with evidences arising from post-event field surveys and with the application of morphometric indexes, such as the Melton ruggedness number, commonly used for discriminating debris-flow catchments from bedload catchments. References: Cavalli, M., Trevisani, S., Comiti, F., Marchi, L., 2013. Geomorphometric assessment of spatial sediment connectivity in small Alpine catchments. Geomorphology 188,31-41. doi:10.1016/j.geomorph.2012.05.007

Recent Approaches to Modeling Transport of Mercury in Surface Water and Groundwater - Case Study in Upper East Fork Poplar Creek, Oak Ridge, TN - 13349

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bostick, Kent; Daniel, Anamary; Tachiev, Georgio

2013-07-01

In this case study, groundwater/surface water modeling was used to determine efficacy of stabilization in place with hydrologic isolation for remediation of mercury contaminated areas in the Upper East Fork Poplar Creek (UEFPC) Watershed in Oak Ridge, TN. The modeling simulates the potential for mercury in soil to contaminate groundwater above industrial use risk standards and to contribute to surface water contamination. The modeling approach is unique in that it couples watershed hydrology with the total mercury transport and provides a tool for analysis of changes in mercury load related to daily precipitation, evaporation, and runoff from storms. The modelmore » also allows for simulation of colloidal transport of total mercury in surface water. Previous models for the watershed only simulated average yearly conditions and dissolved concentrations that are not sufficient for predicting mercury flux under variable flow conditions that control colloidal transport of mercury in the watershed. The transport of mercury from groundwater to surface water from mercury sources identified from information in the Oak Ridge Environmental Information System was simulated using a watershed scale model calibrated to match observed daily creek flow, total suspended solids and mercury fluxes. Mercury sources at the former Building 81-10 area, where mercury was previously retorted, were modeled using a telescopic refined mesh with boundary conditions extracted from the watershed model. Modeling on a watershed scale indicated that only source excavation for soils/sediment in the vicinity of UEFPC had any effect on mercury flux in surface water. The simulations showed that colloidal transport contributed 85 percent of the total mercury flux leaving the UEFPC watershed under high flow conditions. Simulation of dissolved mercury transport from liquid elemental mercury and adsorbed sources in soil at former Building 81-10 indicated that dissolved concentrations are orders of magnitude below a target industrial groundwater concentration beneath the source and would not influence concentrations in surface water at Station 17. This analysis addressed only shallow concentrations in soil and the shallow groundwater flow path in soil and unconsolidated sediments to UEFPC. Other mercury sources may occur in bedrock and transport though bedrock to UEFPC may contribute to the mercury flux at Station 17. Generally mercury in the source areas adjacent to the stream and in sediment that is eroding can contribute to the flux of mercury in surface water. Because colloidally adsorbed mercury can be transported in surface water, actions that trap colloids and or hydrologically isolate surface water runoff from source areas would reduce the flux of mercury in surface water. Mercury in soil is highly adsorbed and transport in the groundwater system is very limited under porous media conditions. (authors)« less

Fluvial sediment transport in a glacier-fed high-mountain river (Riffler Bach, Austrian Alps)

NASA Astrophysics Data System (ADS)

Morche, David; Weber, Martin; Faust, Matthias; Schuchardt, Anne; Baewert, Henning

2017-04-01

High-alpine environments are strongly affected by glacier retreat since the Little Ice Age (LIA). Due to ongoing climate change the hydrology of proglacial rivers is also influenced. It is expected that the growing proportions of snow melt and rainfall events will change runoff characteristics of proglacial rivers. Additionally, the importance of paraglacial sediment sources in recently deglaciating glacier forefields is increasing, while the role of glacial erosion is declining. Thus complex environmental conditions leading to a complex pattern of fluvial sediment transport in partly glaciated catchments of the European Alps. Under the umbrella of the joint PROSA-project the fluvial sediment transport of the river Riffler Bach (Kaunertal, Tyrol, Austria) was studied in 3 consecutive ablation seasons in order to quantify sediment yields. In June 2012 a probe for water level and an automatic water sampler (AWS) were installed at the outlet of the catchment (20km2). In order to calculate annual stage-discharge-relations by the rating-curve approach, discharge (Q) was repeatedly measured with current meters and by salt dilution. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In total 564 (2012: 154, 2013: 209, 2014: 201) water samples were collected and subsequently filtered to quantify suspended sediment concentrations (SSC). Q-SSC-relations were calculated for single flood events due to the high variability of suspended sediment transport. The results show a high inter- and intra-annual variability of solid fluvial sediment transport, which can be explained by the characteristics of suspended sediment transport. Only 13 of 22 event-based Q-SSC-relations show causal dependency. In 2012, during a period with multiple pluvial-induced peak discharges most sediment was transported. On the contrary the importance of snow melt for sediment transport was indicated during the ablation season 2013. In total 3582 t of sediment were exported out of the Riffler Bach catchment in 2012, which is almost twice the solid sediment load of the ablation season 2013 (1953 t). Total solid load of the Riffler Bach River was 3511 t in 2014 Suspended sediment load was dominant in all ablation seasons. The result of additional DEM analysis reveals that 37 % of the catchment do not contribute or only contribute to a lesser amount to the fluvial sediment export out of the catchment. The findings of the grain size analysis imply glacigenic origin of the transported particles. Thus, the results indicate that solid sediment transport is not only a function of discharge. Also availability of sediment and the systems state of (dis-)connectivity, e.g. coupling of sediment sources to the river, need to be considered.

Discharge of debris from ice at the margin of the Greenland ice sheet

USGS Publications Warehouse

Knight, P.G.; Waller, R.I.; Patterson, C.J.; Jones, A.P.; Robinson, Z.P.

2002-01-01

Sediment production at a terrestrial section of the ice-sheet margin in West Greenland is dominated by debris released through the basal ice layer. The debris flux through the basal ice at the margin is estimated to be 12-45 m3 m-1 a-1. This is three orders of magnitude higher than that previously reported for East Antarctica, an order of magnitude higher than sites reported from in Norway, Iceland and Switzerland, but an order of magnitude lower than values previously reported from tidewater glaciers in Alaska and other high-rate environments such as surging glaciers. At our site, only negligible amounts of debris are released through englacial, supraglacial or subglacial sediment transfer. Glacio-fluvial sediment production is highly localized, and long sections of the ice-sheet margin receive no sediment from glaciofluvial sources. These findings differ from those of studies at more temperate glacial settings where glaciofluvial routes are dominant and basal ice contributes only a minor percentage of the debris released at the margin. These data on debris flux through the terrestrial margin of an outlet glacier contribute to our limited knowledge of debris production from the Greenland ice sheet.

Thallium isotopes as tracers of recycled materials in subduction zones: Review and new data for lavas from Tonga-Kermadec and Central America

NASA Astrophysics Data System (ADS)

Nielsen, Sune G.; Prytulak, Julie; Blusztajn, Jerzy; Shu, Yunchao; Auro, Maureen; Regelous, Marcel; Walker, Jim

2017-06-01

Sediment is actively being subducted in every convergent margin worldwide. Yet, geochemical data for arc lavas from several subduction zones, such as Northern Tonga and Costa Rica have revealed either attenuated or limited evidence for sediment in their mantle source regions. Here we use thallium (Tl) isotopes to trace slab components in lavas from the Tonga-Kermadec and Central American arcs. In general, both arcs display Tl isotope data that are most compatible with addition of sediment to the sub-arc mantle from the subducting slab. This evidence is particular strong in the Tonga-Kermadec arc where pelagic clays dominate the Tl budget along the entire arc. Contributions from altered oceanic crust as well as the Louisville Seamount chain that subducts underneath Northern Tonga are not visible in Tl isotopes, which is likely due to the very high Tl concentrations found in pelagic sediments outboard of the Tonga-Kermadec arc. Lavas from Central America reveal variable and systematic Tl isotope compositions along-strike. In particular, lavas from Nicaragua are dominated by contributions from sediments, whereas Costa Rican samples reveal a significant altered oceanic crust component with little influence from sediments on thallium isotope composition. The absence of a sediment signature in Costa Rica corresponds with the Cocos Ridge and the seamount province subduction, which results in a thinner sediment cover. Furthermore, the subducted sediment is dominated by carbonates with very low Tl concentrations and, therefore, small amounts of carbonate sediment added to the mantle wedge do not contribute significantly to the overall Tl budget. A review of Tl isotope and concentration data from the Aleutians, Marianas, Tonga-Kermadec and Central American arcs demonstrate that pelagic sediments are detectable in most arcs, whereas altered oceanic crust components only become appreciable when sediment Tl concentrations are very low (e.g. carbonate) or if sediments are no longer a significant component of the subducting slab (e.g. slab melting in Western Aleutians). As such, Tl isotopes are a promising tool to trace sediment subduction although this requires at least some pelagic sediment is present in the subducted sediment package. We suggest that thallium partitioning between the slab and mantle wedge is most likely controlled by retention in phengite or by partitioning into fluids. Residual phengite likely produces high Cs/Tl ratios because Tl should be more compatible in phengite than is Cs, however, this conclusion needs experimental verification. The stability of phengite is lower at higher fluid contents, which results in hyperbolic relationships between Cs/Tl and possible indicators of fluids such as Sr/Nd and Ba/Th. Thus, combined Tl isotopic and elemental systematics not only provide detailed information about the specific slab components that contribute to arc lavas, but also potentially shed light on the mineralogy and physical conditions of subducting slabs.

Spatial distribution and trends in trace elements, polycyclic aromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls in Lake Worth sediment, Fort Worth, Texas

USGS Publications Warehouse

Harwell, Glenn Richard; Van Metre, Peter C.; Wilson, Jennifer T.; Mahler, Barbara J.

2003-01-01

In spring 2000, the Texas Department of Health issued a fish consumption advisory for Lake Worth in Fort Worth, Texas, because of elevated concentrations of polychlorinated biphenyls (PCBs) in fish. In response to the advisory and in cooperation with the U.S. Air Force, the U.S. Geological Survey collected 21 surficial sediment samples and three gravity core sediment samples to assess the spatial distribution and historical trends of selected hydrophobic contaminants, including PCBs, and to determine, to the extent possible, sources of hydrophobic contaminants to Lake Worth. Compared to reference (background) concentrations in the upper lake, elevated PCB concentrations were detected in the surficial sediment samples collected in Woods Inlet, which receives surface runoff from Air Force facilities and urban areas. Gravity cores from Woods Inlet and from the main part of the lake near the dam indicate that the concentrations of PCBs were three to five times higher in the 1960s than in 2000. A regression method was used to normalize sediment concentrations of trace elements for natural variations and to distinguish natural and anthropogenic contributions to sediments. Concentrations of several trace elements—cadmium, chromium, copper, lead, and zinc—were elevated in sediments in Woods Inlet, along the shoreline of Air Force facilities, and in the main lake near the dam. Concentrations of these five trace elements have decreased since 1970. Polycyclic aromatic hydrocarbons also were elevated in the same areas of the lake. Concentrations of total polycyclic aromatic hydrocarbons, normalized with organic carbon, were mostly stable in the upper lake but steadily increased near the dam, except for small decreases since 1980. The Woods Inlet gravity core showed the largest increase of the three core sites beginning about 1940; total polycyclic aromatic hydrocarbon concentrations in post-1940 sediments from the core showed three apparent peaks about 1960, 1984, and 2000. The concentrations of organochlorine pesticides were low relative to consensus-based sediment-quality guidelines and either decreased or remained constant since 1970. The two likely sources of hydrophobic contaminants to the lake are urban areas around the lake and the drainage area of Meandering Road Creek that contributes runoff to Woods Inlet and includes Air Force facilities.

Sources and relative reactivities of amino acids, neutral sugars, and lignin in an intermittently anoxic marine environment

NASA Astrophysics Data System (ADS)

Cowie, Gregory L.; Hedges, John I.; Calvert, Stephen E.

1992-05-01

A sediment-trap sample, representing an annual average particle flux at 50 m in Saanich Inlet, British Columbia, was analyzed for its elemental, amino acid, neutral sugar, and lignin composition. Amino acid analyses also were performed on underlying sediments which were analyzed previously for organic carbon, nitrogen, neutral sugars, and lignin. The results uniformly indicate primarily marine organic matter sources for all samples, although relatively higher terrigenous contributions are evident in the sediments. The δ13C values of trap materials also point to primarily autochthonous particle fluxes. Comparison of annual average water-column fluxes to sediment accumulation rates indicates under-sampling of sinking particles due to lateral sediment inputs at depth. The anoxic benthic interface appears to be an important site of diagenesis, and selective removal is observed both at compound-class and molecular levels. Cinnamyl and syringyl phenols are selectively removed relative to vanillyl phenols and loss patterns of the monosaccharides, and to a lesser degree the amino acids, strongly indicate preferential preservation of diatom cell-wall materials. Low flux ratios displayed by the nonprotein amino acids are consistent with their diagenetic origin. Preferential loss of marine organic material is indicated by the calculated δ13C value and biochemical composition of the substrate. Concentrations of all measured organic constituents decreased with depth in the uniformly varved 0-14 cm sediment interval, and suggest in situ degradation. Relative reactivities of the biochemical classes indicate a change in diagenetic substrate from that utilized above and at the benthic interface. With the exception of the amino acids, however, diagenesis is generally less selective in the sediments. The amino acid utilization pattern differs from that observed across the benthic interface, and down-core changes in protein and nonprotein amino acid compositions clearly indicate in situ degradation. The sedimentary degraded fraction also appears to be predominantly marine, but lignin yields and sugar compositions suggest a relative increase in the utilization of vascular plant remains. Protein, polysaccharide, and lignin contributions to total organic carbon decrease from 37% in the sediment-trap sample to 22% at the bottom of the 0-14 cm sediment interval. These biochemicals represent over 40 and 50-60% of the degraded carbon and nitrogen, respectively, and thus are important nutrients for the benthic and water-column communities.

Impacts of Mesopotamian wetland re-flooding on the lipid biomarker distributions in sediments

NASA Astrophysics Data System (ADS)

Rushdi, Ahmed I.; DouAbul, Ali A. Z.; Al-Maarofi, Sama S.; Simoneit, Bernd R. T.

2018-03-01

Shallow sediment core samples from two locales in the Mesopotamian marshlands of Iraq were analyzed to characterize the extractable organic (lipid) compounds, and their sources and distributions after hydrological restoration by re-flooding of the marshes. Dried samples were extracted with a dichloromethane/methanol mixture before analysis by gas chromatography-mass spectrometry (GC-MS). The major compounds were n-alkanes, fatty acids and alcohols, steroids, terpenoids, hopanes, steranes, unresolved complex mixture (UCM), and plasticizers. The lipid compounds in Kurmashia (Al-Hammar marshes) were generally higher in concentration than in Abu Zirig (Central marshes), and decreased with core depths for both sites. This concentration decrease with core depth is attributed to transformation, biodegradation and variable input processes. The distribution patterns of the lipids in the sediment cores indicated that the Abu Zirig area was drier than Kurmashia before the re-flooding process. Furthermore, the concentration of the compounds in the surface sediment the Abu Zirig core was as high and similar to that in Kurmashia, reflecting the re-flooding impacts on the marsh and the revival of the wetland. The major sources of these lipids were from natural terrestrial vegetation (35-66% for Abu Zirig; 40-49% for Kurmashia), microbial (plankton) residues and bacteria (27-52% for Abu Zirig; 39-43% for Kurmashia), with a minor contribution from anthropogenic sources including plastic wastes and petroleum (6-13% for Abu Zirig; 9-18% for Kurmashia).

Modeling Mitigation Activities in North Carolina Watersheds

NASA Astrophysics Data System (ADS)

Garcia, A. M.

2017-12-01

Nutrient enrichment and excessive sediment loadings have contributed to the degradation of rivers, lakes and estuaries in North Carolina. The North Carolina Department of Environmental Quality (NCDEQ) has implemented several basin-wide nutrient and sediment management strategies, yet gaps remain in understanding the impact of these strategies given the complexities in quantifying the processes that govern the transport of nutrient and sediment. In particular, improved assessment of the status of nutrient and sediment loadings to lakes and estuaries throughout the state is needed, including characterizing their sources and describing the relative contributions of different areas. The NCDEQ Division of Mitigation Services (DMS) uses watershed planning to identify and prioritize the best locations to implement stream, wetland, and riparian-buffer restoration to improve water quality. To support better decision-making for watershed restoration activities we are developing a SPARROW (SPAtially Referenced Regressions On Watershed attributes) model framework specifically for North Carolina. The SPARROW analysis (developed by the U.S. Geological Survey) relates water-quality monitoring data to better understand the effects of human activities and natural processes on surface-water quality. The core of the model consists of using a nonlinear-regression equation to describe the non-conservative transport of contaminants from point and nonpoint sources on land to rivers, lakes and estuaries through the stream and river network. In this presentation, preliminary total Nitrogen, total Phosphorus, and Total Suspended Solids (TSS) NC-SPARROW models are described that illustrate the SPARROW modeling framework incorporating specific restoration datasets and activity metrics, such as extent of riparian buffer and easements.

A manual to identify sources of fluvial sediment

USGS Publications Warehouse

Gellis, Allen C.; Fitzpatrick, Faith A.; Schubauer-Berigan, Joseph

2016-01-01

Sediment is an important pollutant of concern that can degrade and alter aquatic habitat. A sediment budget is an accounting of the sources, storage, and export of sediment over a defined spatial and temporal scale. This manual focuses on field approaches to estimate a sediment budget. We also highlight the sediment fingerprinting approach to attribute sediment to different watershed sources. Determining the sources and sinks of sediment is important in developing strategies to reduce sediment loads to water bodies impaired by sediment. Therefore, this manual can be used when developing a sediment TMDL requiring identification of sediment sources.The manual takes the user through the seven necessary steps to construct a sediment budget:Decision-making for watershed scale and time period of interestFamiliarization with the watershed by conducting a literature review, compiling background information and maps relevant to study questions, conducting a reconnaissance of the watershedDeveloping partnerships with landowners and jurisdictionsCharacterization of watershed geomorphic settingDevelopment of a sediment budget designData collectionInterpretation and construction of the sediment budgetGenerating products (maps, reports, and presentations) to communicate findings.Sediment budget construction begins with examining the question(s) being asked and whether a sediment budget is necessary to answer these question(s). If undertaking a sediment budget analysis is a viable option, the next step is to define the spatial scale of the watershed and the time scale needed to answer the question(s). Of course, we understand that monetary constraints play a big role in any decision.Early in the sediment budget development process, we suggest getting to know your watershed by conducting a reconnaissance and meeting with local stakeholders. The reconnaissance aids in understanding the geomorphic setting of the watershed and potential sources of sediment. Identifying the potential sediment sources early in the design of the sediment budget will help later in deciding which tools are necessary to monitor erosion and/or deposition at these sources. Tools can range from rapid inventories to estimate the sediment budget or quantifying sediment erosion, deposition, and export through more rigorous field monitoring. In either approach, data are gathered and erosion and deposition calculations are determined and compared to the sediment export with a description of the error uncertainty. Findings are presented to local stakeholders and management officials.Sediment fingerprinting is a technique that apportions the sources of fine-grained sediment in a watershed using tracers or fingerprints. Due to different geologic and anthropogenic histories, the chemical and physical properties of sediment in a watershed may vary and often represent a unique signature (or fingerprint) for each source within the watershed. Fluvial sediment samples (the target sediment) are also collected and exhibit a composite of the source properties that can be apportioned through various statistical techniques. Using an unmixing-model and error analysis, the final apportioned sediment is determined.

Methane Production and Transport within the Marsh Biome of Biosphere 2

NASA Technical Reports Server (NTRS)

Molnar, Jennifer; Goodridge, Kelven

1997-01-01

In recent decades, the concentration of methane in the earth's atmosphere increased 1-2% annually. It's rate of increases, combined with methane's effectiveness as a greenhouse gas, has led to an intensive research effort to determine the sources and sinks of the gas in the environment. Biosphere 2 offers a unique opportunity to contribute to the effort because it lacks a major photochemical sink present in the Earth's atmosphere. Researchers can therefore concentrate on biological processes involved in methane cycles. Wetlands are a large source of atmospheric methane, due to anoxic conditions in the sediments and the abundance of organic materials. In order to determine if these conditions in Biosphere 2 also promote methane production, this study looked for the fluxes of methane and methods of transport of the gas from from the water and sediments to the atmosphere in the Marsh Biome. Fluxes of methane from the sediments and waters were measured using static chambers, peepers, and leaf bags. Fluxes and vertical profiles of methane in the sediments show that substantial amounts of methane are being produced in the marsh and are being transported into the Biosphere 2 environment.

Reconstructing Early Industrial Contributions to Legacy Trace Metal Contamination in Southwestern Pennsylvania.

PubMed

Rossi, Robert J; Bain, Daniel J; Hillman, Aubrey L; Pompeani, David P; Finkenbinder, Matthew S; Abbott, Mark B

2017-04-18

Early industrial trace metal loadings are poorly characterized but potentially substantial sources of trace metals to the landscape. The magnitude of legacy contamination in southwestern Pennsylvania, the cradle of North American fossil fuel industrialization, is reconstructed from trace metal concentrations in a sediment core with proxies including major and trace metal chemistry, bulk density, and magnetic susceptibility. Trace metal chemistry in this sediment record reflects 19th and 20th century land use and industry. In particular, early 19th century arsenic loadings to the lake are elevated from pesticides used by early European settlers at a lakeside tannery. Later, sediment barium concentrations rise, likely reflecting the onset of acidic mine drainage from coal operations. Twentieth century zinc, cadmium, and lead concentrations are dominated by emissions from the nearby, infamous Donora Zinc Works yet record both the opening of a nearby coal-fired power plant and amendments to the Clean Air Act. The impact of early industry is substantial and rivals more recent metal fluxes, resulting in a significant potential source of contaminated sediments. Thus, modern assessments of trace metal contamination cannot ignore early industrial inputs, as the potential remobilization of legacy contamination would impact ecosystem and human health.

Streambanks: A net source of sediment and phosphorus to streams and rivers.

PubMed

Fox, Garey A; Purvis, Rebecca A; Penn, Chad J

2016-10-01

Sediment and phosphorus (P) are two primary pollutants of surface waters. Many studies have investigated loadings from upland sources or even streambed sediment, but in many cases, limited to no data exist to determine sediment and P loading from streambanks on a watershed scale. The objectives of this paper are to review the current knowledge base on streambank erosion and failure mechanisms, streambank P concentrations, and streambanks as P loading sources and then also to identify future research needs on this topic. In many watersheds, long-term loading of soil and associated P to stream systems has created a source of eroded soil and P that may interact with streambank sediment and be deposited in floodplains downstream. In many cases streambanks were formed from previously eroded and deposited alluvial material and so the resulting soils possess unique physical and chemical properties from adjacent upland soils. Streambank sediment and P loading rates depend explicitly on the rate of streambank migration and the concentration of P stored within bank materials. From the survey of literature, previous studies report streambank total P concentrations that consistently exceeded 250 mg kg(-1) soil. Only a few studies also reported water soluble or extractable P concentrations. More research should be devoted to understanding the dynamic processes between different P pools (total P versus bioavailable P), and sorption or desorption processes under varying hydraulic and stream chemistry conditions. Furthermore, the literature reported that streambank erosion and failure and gully erosion were reported to account for 7-92% of the suspended sediment load within a channel and 6-93% of total P. However, significant uncertainty can occur in such estimates due to reach-scale variability in streambank migration rates and future estimates should consider the use of uncertainty analysis approaches. Research is also needed on the transport rates of dissolved and sediment-bound P through the entire stream system of a watershed to identify critical upland and/or near-stream conservation practices. Extensive monitoring of the impact of restoration/rehabilitation efforts on reducing sediment and P loading are limited. From an application standpoint, streambank P contributions to streams should be more explicitly accounted for in developing total maximum daily loads in watersheds. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemical markers of sedimentary organic matter in Todos os Santos Bay, Bahia - Brazil. Indicators of sources and preservation.

PubMed

de Souza, José Roberto Bispo; do Rosário Zucchi, Maria; Costa, Alexandre Barreto; de Azevedo, Antonio Expedito Gomes; Spano, Saulo

2017-06-30

Natural stable isotopes, such as carbon (C) and nitrogen (N), are modern tools to assess geochemical processes. C and N in organic matter can carry fingerprints of their hydrologic flows and sedimentary processes, including any anthropogenic modification on the natural system. This study focuses on the determination of aliphatic and polycyclic aromatic hydrocarbons and isotopic ratio in the sediment of Todos os Santos Bay (TSB). The isotopic results of the total organic matter indicate varied contribution marine and terrigenous. Typical rates of PAHs mainly indicate a pyrogenic source and mixture between pyrogenic and petrogenic sources. Typical ratios for the n-alkanes indicate the presence of petroleum hydrocarbons. The isotopic composition of n-alkanes suggests a mixture of sources, with the possible contribution of petrogenic. Copyright © 2017. Published by Elsevier Ltd.

Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

USGS Publications Warehouse

Pohlman, J.W.; Bauer, J.E.; Canuel, E.A.; Grabowski, K.S.; Knies, D.L.; Mitchell, C.S.; Whiticar, Michael J.; Coffin, R.B.

2009-01-01

Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon (14C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ??13C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14C mass balance approach using fossil methane and 14C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

Prediction and forecast of Suspended Sediment Concentration (SSC) on the Upper Yangtze basin

NASA Astrophysics Data System (ADS)

Matos, José Pedro; Hassan, Marwan; Lu, Xixi; Franca, Mário J.

2017-04-01

Sediment transport in suspension may represent 90% or more of the global annual flux of sediment. For instance, more than 99% of the sediment supplied to the sea by the Yangtze River is suspended load. Suspended load is an important component for understanding channel dynamics and landscape evolution. Sediments transported in suspension are a major source of nutrients for aquatic organisms in riparian and floodplain habitats, and play a beneficial role acting as a sink in the carbon cycle. Excess of fine sediments may also have adverse effects. It can impair fish spawning by riverbed clogging, disturb foraging efficiency of hunting of river fauna, cause algae and benthos scouring, reduce or inhibit exchanges through the hyporheic region. Accumulation of fine sediments in reservoirs reduces storage capacity. Although fine sediment dynamics has been the focus of many studies, the current knowledge of sediment sources, transfer, and storage is inadequate to address fine sediment dynamics in the landscape. The theoretical derivation of a complete model for suspended sediment transport at the basin scale, incorporating small scale processes of production and transport, is hindered because the underlying mechanisms are produced at different non-similar scales. Availability of long-term reliable data on suspended sediment dynamics is essential to improve our knowledge on transport processes and to develop reliable sediment prediction models. Over the last 60 years, the Yangtze River Commission has been measuring the daily Suspended Sediment Concentration (SSC) at the Pingshan station. This dataset provides a unique opportunity to examine temporal variability and controls of fine sediment dynamics in the Upper Yangtze basin. The objective of this study is to describe temporal variation of fine sediment dynamics at the Pingshan station making use of the extensive sediment monitoring program undertaken at that location. We test several strategies of prediction and forecast applied to the long time series of SSC and streamflow. By changing the base variables between strategies, we improve our understanding of the phenomena driving SSC. Prediction and forecasts are obtained from the various input data sets based on a novel probabilistic data-driven technique, the Generalized Pareto Uncertainty (GPU), which requires very little parametrization. Addressing uncertainty explicitly, this methodology recognizes the stochastic nature of SSC. The GPU was inspired in machine learning concepts and benefits from advances in multi-objective optimization techniques to discard most explicit assumptions about the nature of the uncertainty being modeled. Assumptions that do remain are the need to specify a model for eventual non-stationarity of the series and that there are enough observations to conveniently model the uncertainty. In this contribution, several models are tested with conditioned inputs to focus on specific processes leading affecting SSC. For example, the influence of seasonal and local contributions to SSC can be separated by conditioning the probability estimation on seasonal and local drivers. Probabilistic forecasting models for SSC that account for different drivers of the phenomena are discussed.

Bulk organic δ 13C and C/N as indicators for sediment sources in the Pearl River delta and estuary, southern China

NASA Astrophysics Data System (ADS)

Yu, Fengling; Zong, Yongqiang; Lloyd, Jeremy M.; Huang, Guangqing; Leng, Melanie J.; Kendrick, Christopher; Lamb, Angela L.; Yim, Wyss W.-S.

2010-05-01

Preservation of organic matter in estuarine and coastal areas is an important process in the global carbon cycle. This paper presents bulk δ 13C and C/N of organic matter from source to sink in the Pearl River catchment, delta and estuary, and discusses the applicability of δ 13C and C/N as indicators for sources of organic matter in deltaic and estuarine sediments. In addition to the 91 surface sediment samples, other materials collected in this study cover the main sources of organic material to estuarine sediment. These are: terrestrial organic matter (TOM), including plants and soil samples from the catchment; estuarine and marine suspended particulate organic carbon (POC) from both summer and winter. Results show that the average δ 13C of estuarine surface sediment increases from -25.0 ± 1.3‰ in the freshwater environment to -21.0 ± 0.2‰ in the marine environment, with C/N decreasing from 15.2 ± 3.3 to 6.8 ± 0.2. In the source areas, C 3 plants have lower δ 13C than C 4 plants (-29.0 ± 1.8‰ and -13.1 ± 0.5‰ respectively). δ 13C increases from -28.3 ± 0.8‰ in the forest soil to around -24.1‰ in both riverbank soil and mangrove soil due to increasing proportion of C 4 grasses. The δ 13C POC increases from -27.6 ± 0.8‰ in the freshwater areas to -22.4 ± 0.5‰ in the marine-brackish-water areas in winter, and ranges between -24.0‰ in freshwater areas and -25.4‰ in brackish-water areas in summer. Comparison of the δ 13C and C/N between the sources and sink indicates a weakening TOM and freshwater POC input in the surface sedimentary organic matter seawards, and a strengthening contribution from the marine organic matter. Thus we suggest that bulk organic δ 13C and C/N analysis can be used to indicate sources of sedimentary organic matter in estuarine environments. Organic carbon in surface sediments derived from anthropogenic sources such as human waste and organic pollutants from industrial and agricultural activities accounts for less than 10% of the total organic carbon (TOC). Although results also indicate elevated δ 13C of sedimentary organic matter due to some agricultural products such as sugarcane, C 3 plants are still the dominant vegetation type in this area, and the bulk organic δ 13C and C/N is still an effective indicator for sources of organic matter in estuarine sediments.

Agriculture in the Mississippi River Basin; effects on water quality, aquatic biota, and watershed conservation.

USDA-ARS?s Scientific Manuscript database

Agriculture has been identified as a potential leading source of nutrients (nitrogen and phosphorus) and sediment enrichment of water bodies within the Mississippi River basin (MRB) and contributes to impaired water quality and biological resources in the MRB and the northern Gulf of Mexico (GOM). T...

Extreme methane emissions from a Swiss hydropower reservoir: contribution from bubbling sediments.

PubMed

Delsontro, Tonya; McGinnis, Daniel F; Sobek, Sebastian; Ostrovsky, Ilia; Wehrli, Bernhard

2010-04-01

Methane emission pathways and their importance were quantified during a yearlong survey of a temperate hydropower reservoir. Measurements using gas traps indicated very high ebullition rates, but due to the stochastic nature of ebullition a mass balance approach was crucial to deduce system-wide methane sources and losses. Methane diffusion from the sediment was generally low and seasonally stable and did not account for the high concentration of dissolved methane measured in the reservoir discharge. A strong positive correlation between water temperature and the observed dissolved methane concentration enabled us to quantify the dissolved methane addition from bubble dissolution using a system-wide mass balance. Finally, knowing the contribution due to bubble dissolution, we used a bubble model to estimate bubble emission directly to the atmosphere. Our results indicated that the total methane emission from Lake Wohlen was on average >150 mg CH(4) m(-2) d(-1), which is the highest ever documented for a midlatitude reservoir. The substantial temperature-dependent methane emissions discovered in this 90-year-old reservoir indicate that temperate water bodies can be an important but overlooked methane source.

A preliminary investigation of the environmental impact of a thermal power plant in relation to PCB contamination.

PubMed

Gedik, Kadir; Imamoglu, Ipek

2011-07-01

The most significant application of polychlorinated biphenyls (PCBs) is in transformers and capacitors. Therefore, power plants are important suspected sources for entry of PCBs into the environment. In this context, the levels and distribution of PCBs in sediment, soil, ash, and sludge samples were investigated around Seyitömer thermal power plant, Kütahya, Turkey. Moreover, identity and contribution of PCB mixtures were predicted using the chemical mass balance (CMB) receptor model. United States Environmental Protection Agency methods were applied during sample preparation, extraction (3540C), cleanup (3660B, 3665A, 3630C), and analysis (8082A). ΣPCB concentrations in the region ranged from not detected to 385 ng/g dry weight, with relatively higher contamination in sediments in comparison to soil, sludge, and ash samples collected from around the power plant. Congener profiles of the sediment and soil samples show penta-, hexa-, and hepta-chlorobiphenyls as the major homolog groups. The results from the CMB model indicate that PCB contamination is largely due to Clophen A60/A40 and Aroclor 1254/1254(late)/1260 release into the sediment and sludge samples around the thermal power plant. Since there are no other sources of PCBs in the region and the identity of PCB sources estimated by the CMB model mirrors PCB mixtures contained in transformers formerly used in the plant, the environmental contamination observed especially in sediments is attributed to the power plant. Release of PCBs over time, as indicated by the significant concentrations observed even in surface samples, emphasizes the importance of the need for better environmental management.

Stable carbon isotope ratios of intact GDGTs indicate heterogeneous sources to marine sediments

NASA Astrophysics Data System (ADS)

Pearson, Ann; Hurley, Sarah J.; Walter, Sunita R. Shah; Kusch, Stephanie; Lichtin, Samantha; Zhang, Yi Ge

2016-05-01

Thaumarchaeota, the major sources of marine glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), are believed to fix the majority of their carbon directly from dissolved inorganic carbon (DIC). The δ13C values of GDGTs (δ13CGDGT) may be powerful tools for reconstructing variations in the ocean carbon cycle, including paleoproductivity and water mass circulation, if they can be related to values of δ13CDIC. To date, isotope measurements primarily are made on the C40 biphytane skeletons of GDGTs, rather than on complete tetraether structures. This approach erases information revealed by the isotopic heterogeneity of GDGTs within a sample and may impart an isotopic fractionation associated with the ether cleavage. To circumvent these issues, we present δ13C values for GDGTs from twelve recent sediments representing ten continental margin locations. Samples are purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values by Spooling Wire Microcombustion (SWiM)-isotope ratio mass spectrometry (IRMS) with 1σ precision and accuracy of ±0.25‰. Using this approach, we confirm that GDGTs, generally around -19‰, are isotopically ;heavy; compared to other marine lipids. However, measured δ13CGDGT values are inconsistent with predicted values based on the 13C content of DIC in the overlying water column and the previously-published biosynthetic isotope fractionation for a pure culture of an autotrophic marine thaumarchaeon. In some sediments, the isotopic composition of individual GDGTs differs, indicating multiple source inputs. The data appear to confirm that crenarchaeol primarily is a biomarker for Thaumarchaeota, but its δ13C values still cannot be explained solely by autotrophic carbon fixation. Overall the complexity of the results suggests that both organic carbon assimilation (ca. 25% of total carbon) and multiple source(s) of exogenous GDGTs (contributing generally <30% of input to sediments) are necessary to explain the observed δ13CGDGT values. The results suggest caution when interpreting the total inputs of GDGTs to sedimentary records. Biogenic or open-slope sediments, rather than clastic basinal or shallow shelf sediments, are preferred locations for generating minimally-biased GDGT proxy records.

Using sediment 'fingerprints' to assess sediment-budget errors, north Halawa Valley, Oahu, Hawaii, 1991-92

USGS Publications Warehouse

Hill, B.R.; DeCarlo, E.H.; Fuller, C.C.; Wong, M.F.

1998-01-01

Reliable estimates of sediment-budget errors are important for interpreting sediment-budget results. Sediment-budget errors are commonly considered equal to sediment-budget imbalances, which may underestimate actual sediment-budget errors if they include compensating positive and negative errors. We modified the sediment 'fingerprinting' approach to qualitatively evaluate compensating errors in an annual (1991) fine (<63 ??m) sediment budget for the North Halawa Valley, a mountainous, forested drainage basin on the island of Oahu, Hawaii, during construction of a major highway. We measured concentrations of aeolian quartz and 137Cs in sediment sources and fluvial sediments, and combined concentrations of these aerosols with the sediment budget to construct aerosol budgets. Aerosol concentrations were independent of the sediment budget, hence aerosol budgets were less likely than sediment budgets to include compensating errors. Differences between sediment-budget and aerosol-budget imbalances therefore provide a measure of compensating errors in the sediment budget. The sediment-budget imbalance equalled 25% of the fluvial fine-sediment load. Aerosol-budget imbalances were equal to 19% of the fluvial 137Cs load and 34% of the fluval quartz load. The reasonably close agreement between sediment- and aerosol-budget imbalances indicates that compensating errors in the sediment budget were not large and that the sediment-budget imbalance as a reliable measure of sediment-budget error. We attribute at least one-third of the 1991 fluvial fine-sediment load to highway construction. Continued monitoring indicated that highway construction produced 90% of the fluvial fine-sediment load during 1992. Erosion of channel margins and attrition of coarse particles provided most of the fine sediment produced by natural processes. Hillslope processes contributed relatively minor amounts of sediment.

Contribution of different sources to the pollution of wet weather flows in combined sewers.

PubMed

Gromaire, M C; Garnaud, S; Saad, M; Chebbo, G

2001-02-01

Experiments performed on "Marais" catchment, in central Paris, aimed to follow up the quality of wet weather flows from the entry to the exit of a combined sewer network. SS, VSS, COD, BOD5, Cd, Cu, Pb, Zn concentrations were measured for an important number of rain events in roof, yard, street runoff, as well as in dry and wet weather flows at the catchment outlet. Mass entry-exit totals, at the scale of the catchment, were calculated over 31 rain events in order to evaluate the contribution of different types of runoff, of sanitary sewage and of sewer sediments to the total wet weather pollutant loads at the catchment outlet. The erosion of in-sewer pollutant stocks was found to be the main source of particles and of organic matter in wet weather flows, whereas heavy metal loads mainly originated from roof runoff, due to the corrosion of metallic roofs. Particles eroded inside the sewer during rain events were found to be quite different from the particles constituting the main part of sewer sediments: they are organic and biodegradable, with rather important settling velocities and seem to accumulate during dry weather periods. A change of the chemical form of heavy metals was noticed during the transport in the sewer and it is suspected that a fraction of the dissolved metals from the runoff is adsorbed on sewer sediments.

Geochemistry of southern Pagan Island lavas, Mariana arc: The role of subduction zone processes

USGS Publications Warehouse

Marske, J.P.; Pietruszka, A.J.; Trusdell, F.A.; Garcia, M.O.

2011-01-01

New major and trace element abundances, and Pb, Sr, and Nd isotopic ratios of Quaternary lavas from two adjacent volcanoes (South Pagan and the Central Volcanic Region, or CVR) located on Pagan Island allow us to investigate the mantle source (i.e., slab components) and melting dynamics within the Mariana intra-oceanic arc. Geologic mapping reveals a pre-caldera (780-9.4ka) and post-caldera (<9.4ka) eruptive stage for South Pagan, whereas the eruptive history of the older CVR is poorly constrained. Crystal fractionation and magma mixing were important crustal processes for lavas from both volcanoes. Geochemical and isotopic variations indicate that South Pagan and CVR lavas, and lavas from the northern volcano on the island, Mt. Pagan, originated from compositionally distinct parental magmas due to variations in slab contributions (sediment and aqueous fluid) to the mantle wedge and the extent of mantle partial melting. A mixing model based on Pb and Nd isotopic ratios suggests that the average amount of sediment in the source of CVR (~2.1%) and South Pagan (~1.8%) lavas is slightly higher than Mt. Pagan (~1.4%) lavas. These estimates span the range of sediment-poor Guguan (~1.3%) and sediment-rich Agrigan (~2.0%) lavas for the Mariana arc. Melt modeling demonstrates that the saucer-shaped normalized rare earth element (REE) patterns observed in Pagan lavas can arise from partial melting of a mixed source of depleted mantle and enriched sediment, and do not require amphibole interaction or fractionation to depress the middle REE abundances of the lavas. The modeled degree of mantle partial melting for Agrigan (2-5%), Pagan (3-7%), and Guguan (9-15%) lavas correlates with indicators of fluid addition (e.g., Ba/Th). This relationship suggests that the fluid flux to the mantle wedge is the dominant control on the extent of partial melting beneath Mariana arc volcanoes. A decrease in the amount of fluid addition (lower Ba/Th) and extent of melting (higher Sm/Yb), and an increase in the sediment contribution (higher Th/Nb, La/Sm, and Pb isotopic ratios) from Mt. Pagan to South Pagan could reflect systematic cross-arc or irregular along-arc melting variations. These observations indicate that the length scale of compositional heterogeneity in the mantle wedge beneath Mariana arc volcanoes is small (~10km).

Surficial deposits in the Bear Lake Basin

USGS Publications Warehouse

Reheis, Marith C.; Laabs, Benjamin J.C.; Forester, Richard M.; McGeehin, John P.; Kaufman, Darrell S.; Bright, Jordon

2005-01-01

Mapping and dating of surficial deposits in the Bear Lake drainage basin were undertaken to provide a geologic context for interpretation of cores taken from deposits beneath Bear Lake, which sometimes receives water and sediment from the glaciated Bear River and sometimes only from the small drainage basin of Bear Lake itself. Analyses of core sediments by others are directed at (1) constructing a high-resolution climate record for the Bear Lake area during the late Pleistocene and Holocene, and (2) investigating the sources and weathering history of sediments in the drainage basin. Surficial deposits in the upper Bear River and Bear Lake drainage basins are different in their overall compositions, although they do overlap. In the upper Bear River drainage, Quaternary deposits derived from glaciation of the Uinta Range contain abundant detritus weathered from Precambrian quartzite, whereas unglaciated tributaries downstream mainly contribute finer sediment weathered from much younger, more friable sedimentary rocks. In contrast, carbonate rocks capped by a carapace of Tertiary sediments dominate the Bear Lake drainage basin.

Extreme erosion response after wildfire in the Upper Ovens, south-east Australia: Assessment of catchment scale connectivity by an intensive field survey

NASA Astrophysics Data System (ADS)

Box, Walter; Keestra, Saskia; Nyman, Petter; Langhans, Christoph; Sheridan, Gary

2015-04-01

South-eastern Australia is generally regarded as one of the world's most fire-prone environments because of its high temperatures, low rainfall and flammable native Eucalyptus forests. Modifications to the landscape by fire can lead to significant changes to erosion rates and hydrological processes. Debris flows in particular have been recognised as a process which increases in frequency as a result of fire. This study used a debris flow event in the east Upper Ovens occurred on the 28th of February 2013 as a case study for analysing sediment transport processes and connectivity of sediment sources and sinks. Source areas were identified using a 15 cm resolution areal imagery and a logistic regression model was made based on fire severity, aridity index and slope to predict locations of source areas. Deposits were measured by making cross-sections using a combination of a differential GPS and a total station. In total 77 cross-sections were made in a 14.1 km2 sub-catchment and distributed based on channel gradient and width. A more detailed estimation was obtained by making more cross-sections where the volume per area is higher. Particle size distribution between sources and sink areas were obtained by combination of field assessment, photography imagery analyses and sieve and laser diffraction. Sediment was locally eroded, transported and deposited depending on factors such as longitude gradient, stream power and the composition of bed and bank material. The role of headwaters as sediment sinks changed dramatically as a result of the extreme erosion event in the wildfire affected areas. Disconnected headwaters became connected to low order streams due to debris flow processes in the contributing catchment. However this redistribution of sediment from headwaters to the drainage network was confined to upper reaches of the Ovens. Below this upper part of the catchment the event resulted in redistribution of sediment already existing in the channel through a combination of debris flows and hyperconcentrated flows. These results indicate that there is a stepwise outflow of sediment influencing long-term erosion rates and landform development.

Jack Dymond's "Fingerprints" on Sediment Chemistry, Biogeochemical Fluxes, and my Career

NASA Astrophysics Data System (ADS)

Leinen, M.

2004-12-01

I first met Jack Dymond as a graduate student at Oregon State University. He wasn't my thesis advisor. He wasn't even on my committee. But his ever so gentle counsel and his low key advice did much to shape my career, as a student, as a scientist, and later as an administrator of science. At the time, Jack was wading through the analysis of a very large number of surface sediment samples from the Nazca Plate as part of an IDOE project. The number and density of sampling was extraordinary for the time and his work showed that the geochemistry of the sediments could be deconvolved to understand the contributions of sediment sources over the entire plate. I had been planning to analyze DSDP samples from the equatorial Pacific to understand the history of siliceous sedimentation in that region and I began to talk with Jack about how I could use geochemical signatures to estimate the non-biogenic fraction of the sediment. When Jack's Nazca Plate paper came out, Debra Stakes and I decided to analyze all of my sample residues for the same elements that Jack had studied. In the only piece of bad advice that he ever gave me, Jack told me that it was a waste of time because there wouldn't be high enough concentrations of transition metals in the calcareous and siliceous sediments to measure. We insisted and Jack, in typical fashion, agreed to pay for reagents and give us instrument time without charge anyway. The larger than expected concentrations, and the even more surprising match between the accumulation rates of some the metals and the accumulation rates of biogenic sediment were the subject of many discussions, all of which ended in the need for more information on the composition, fluxes and transformations of biogenic sediment in the water column and in recent sediments. This, of course, became another of Jack's specialties: his designs for sediment traps were important contributions to the evolution of this important sampling device. His studies of fluxes in a wide variety of environments - from hydrothermal vent fields to Crater Lake --were critical to the development of modern biogeochemical cycling experiments and thinking. And this, of course, was only one of the fields in which he made major contributions.

Modes of cross-shore sediment transport on the shoreface of the Middle Atlantic Bight

USGS Publications Warehouse

Wright, L.D.; Boon, John D.; Kim, S.C.; List, J.H.

1991-01-01

The mechanisms responsible for onshore and offshore sediment fluxes across the shoreface zone seaward of the surf zone were examined in a 3-year field study. The study was conducted in the southern part of the Middle Atlantic Bight in the depth region 7–17 m using instrumented tripods supporting electromagnetic current meters, pressure sensors, suspended sediment concentration sensors, and sonar altimeters. The observations embraced fairweather, moderate energy, swell-dominated, and storm conditions. Cross-shore mean flows ranged from near zero during fairweather to > 20 cm s−1 during the storm; oscillatory flows were on the order of 10 cm s−1 during fairweather and 100 cm s−1 during the storm. Suspended sediment concentrations at about 10 cm above the bed were < 0.1 kg m−3 under fairweather conditions, 1–2 kg m−3 under moderate swell conditions, and > 5 kg m−3 during the storm.Three methods were applied to evaluate the relative importance of incident waves, long-period oscillations, mean flows and gravity in effecting shoreward or seaward sediment flux: (1) an energetics transport model was applied to instantaneous near-bottom velocity data, (2) higher moments of near-bottom flows were estimated and compared, and (3) suspended sediment fluxes were estimated directly from the instantaneous products of cross-shore velocity and suspended sediment concentration. The results show that measurable contributions were made by all four of the processes. Most significantly, mean flows were seen to dominate and cause offshore fluxes during the storm and to contribute significantly to onshore and offshore flux during fairweather and moderate energy. Incident waves were, in all cases, the major source of bed shear stress but also caused shoreward as well as seaward net sediment advection. Low-frequency effects involving wave groups and long-period waves made secondary contributions to cross-shore sediment flux. Contrary to expectations, low-frequency fluxes were just as often shoreward as seaward. Whereas cross-correlations between suspended sediment concentration and the instantaneous near-bottom current speed were high and in phase under storm conditions, they were weak and out of phase during fairweather conditions. This suggests that simple energetics models are probably inadequate for predicting fairweather transport of suspended sediment.

Radionuclide contamination of sediment deposits in the Ob and Yenisey estuaries and areas of the Kara Sea.

PubMed

Standring, W J F; Stepanets, O; Brown, J E; Dowdall, M; Borisov, A; Nikitin, A

2008-04-01

The Ob and Yenisey rivers are major contributors to total riverine discharge to the Arctic Ocean. Several large nuclear facilities discharge into these rivers, which could affect actual and potential discharges of radionuclides to the Arctic region. This article presents new radionuclide concentration and grain-size data resulting from analyses of several sediment samples collected during research cruises in the Ob and Yenisey estuaries and adjacent areas during 2000 and 2001. Results indicate that discharges from the main nuclear facilities do not constitute a major contribution to the level of radioactive contamination in the marine areas studied, though Co-60 was detected at low concentrations in some sediment horizons. However, the aggregate contamination from different sources is not radioecologically significant in sediments within the study area, maximum Cs-137 levels being approximately 80 Bq kg(-1) dry weight.

A statistical approach to the interpretation of aliphatic hydrocarbon distributions in marine sediments

USGS Publications Warehouse

Rapp, J.B.

1991-01-01

Q-mode factor analysis was used to quantitate the distribution of the major aliphatic hydrocarbon (n-alkanes, pristane, phytane) systems in sediments from a variety of marine environments. The compositions of the pure end members of the systems were obtained from factor scores and the distribution of the systems within each sample was obtained from factor loadings. All the data, from the diverse environments sampled (estuarine (San Francisco Bay), fresh-water (San Francisco Peninsula), polar-marine (Antarctica) and geothermal-marine (Gorda Ridge) sediments), were reduced to three major systems: a terrestrial system (mostly high molecular weight aliphatics with odd-numbered-carbon predominance), a mature system (mostly low molecular weight aliphatics without predominance) and a system containing mostly high molecular weight aliphatics with even-numbered-carbon predominance. With this statistical approach, it is possible to assign the percentage contribution from various sources to the observed distribution of aliphatic hydrocarbons in each sediment sample. ?? 1991.

Atmospheric mercury deposition during the last 270 years--A glacial ice core record of natural and anthropogenic sources

USGS Publications Warehouse

Schuster, Paul F.; Krabbenhoft, David P.; Naftz, David L.; Cecil, L. DeWayne; Olson, Mark L.; DeWild, John F.; Susong, David D.; Green, Jaromy R.; Abbott, Michael L.

2002-01-01

Mercury (Hg) contamination of aquatic ecosystems and subsequent methylmercury bioaccumulation are significant environmental problems of global extent. At regional to global scales, the primary mechanism of Hg contamination is atmospheric Hg transport. Thus, a better understanding of the long-term history of atmospheric Hg cycling and quantification of the sources is critical for assessing the regional and global impact of anthropogenic Hg emissions. Ice cores collected from the Upper Fremont Glacier (UFG), Wyoming, contain a high-resolution record of total atmospheric Hg deposition (ca. 1720−1993). Total Hg in 97 ice-core samples was determined with trace-metal clean handling methods and low-level analytical procedures to reconstruct the first and most comprehensive atmospheric Hg deposition record of its kind yet available from North America. The record indicates major atmospheric releases of both natural and anthropogenic Hg from regional and global sources. Integrated over the past 270-year ice-core history, anthropogenic inputs contributed 52%, volcanic events 6%, and background sources 42%. More significantly, during the last 100 years, anthropogenic sources contributed 70% of the total Hg input. Unlike the 2−7-fold increase observed from preindustrial times (before 1840) to the mid-1980s in sediment-core records, the UFG record indicates a 20-fold increase for the same period. The sediment-core records, however, are in agreement with the last 10 years of this ice-core record, indicating declines in atmospheric Hg deposition.

A Manual to Identify Sources of Fluvial Sediment | Science ...

EPA Pesticide Factsheets

Sedimentation is one of the main causes of stream/river aquatic life use impairments in R3. Currently states lack standard guidance on appropriate tools available to quantify sediment sources and develop sediment budgets in TMDL Development. Methods for distinguishing sediment types for TMDL development will focus stream restoration and soil conservation efforts in strategic locations in a watershed and may better target appropriate BMPs to achieve sediment load reductions. Properly identifying sediment sources in a TMDL will also help focus NPDES permitting, stream restoration activities and other TMDL implementation efforts. This project will focus on developing a framework that will be published as a guidance document that outlines steps and approaches to identify the significant sources of fine-grained sediment in 303D listed watersheds. In this framework, the sediment-fingerprinting and sediment budget approaches will be emphasized. This project will focus on developing a framework that will be published as a guidance document that outlines steps and approaches to identify the significant sources of fine-grained sediment in 303D listed watersheds. In this framework, the sediment-fingerprinting and sediment budget approaches will be emphasized.

Sources of mercury to San Francisco Bay surface sediment as revealed by mercury stable isotopes

USGS Publications Warehouse

Gehrke, Gretchen E.; Blum, Joel D.; Marvin-DePasquale, Mark

2011-01-01

Mercury (Hg) concentrations and isotopic compositions were examined in shallow-water surface sediment (0–2 cm) from San Francisco (SF) Bay to determine the extent to which historic Hg mining contributes to current Hg contamination in SF Bay, and to assess the use of Hg isotopes to trace sources of contamination in estuaries. Inter-tidal and wetland sediment had total Hg (HgT) concentrations ranging from 161 to 1529 ng/g with no simple gradients of spatial variation. In contrast, inter-tidal and wetland sediment displayed a geographic gradient of δ202Hg values, ranging from -0.30% in the southern-most part of SF Bay (draining the New Almaden Hg District) to -0.99% in the northern-most part of SF Bay near the Sacramento–San Joaquin River Delta. Similar to SF Bay inter-tidal sediment, surface sediment from the Alviso Slough channel draining into South SF Bay had a δ202Hg value of -0.29%, while surface sediment from the Cosumnes River and Sacramento–San Joaquin River Delta draining into north SF Bay had lower average δ202Hg values of -0.90% and -0.75%, respectively. This isotopic trend suggests that Hg-contaminated sediment from the New Almaden Hg District mixes with Hg-contaminated sediment from a low δ202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ202Hg values of -0.37 and +0.03%, respectively, showing that Hg calcination fractionates Hg isotopes resulting in Hg contamination from Hg(II) mine waste products with higher δ202Hg values than metallic Hg(0) produced from Hg mines. Thus, there is evidence for at least two distinct isotopic signals for Hg contamination in SF Bay: Hg associated with calcine waste materials at Hg mines in the Coast Range, such as New Almaden and New Idria; and Hg(0) produced from these mines and used in placer gold mines and/or in other industrial processes in the Sierra Nevada region and SF Bay area.

Year-round N2O production by benthic NOx reduction in a monomictic south-alpine lake

NASA Astrophysics Data System (ADS)

Freymond, C. V.; Wenk, C. B.; Frame, C. H.; Lehmann, M. F.

2013-12-01

Nitrous oxide (N2O) is a potent greenhouse gas, generated through microbial nitrogen (N) turnover processes, such as nitrification, nitrifier denitrification, and denitrification. Previous studies quantifying natural sources have mainly focused on soils and the ocean, but the potential role of terrestrial water bodies in the global N2O budget has been widely neglected. Furthermore, the biogeochemical controls on the production rates and the microbial pathways that produce benthic N2O in lakes are essentially unknown. In this study, benthic N2O fluxes and the contributions of the microbial pathways that produce N2O were assessed using 15N label flow-through sediment incubations in the eutrophic, monomictic south basin of Lake Lugano in Switzerland. The sediments were a significant source of N2O throughout the year, with production rates ranging between 140 and 2605 nmol N2O h-1 m-2, and the highest observed rates coinciding with periods of water column stratification and stably anoxic conditions in the overlying bottom water. Nitrate (NO3-) reduction via denitrification was found to be the major N2O production pathway in the sediments under both oxygen-depleted and oxygen-replete conditions in the overlying water, while ammonium oxidation did not contribute significantly to the benthic N2O flux. A marked portion (up to 15%) of the total NO3- consumed by denitrification was reduced only to N2O, without complete denitrification to N2. These fluxes were highest when the bottom water had stabilized to a low-oxygen state, in contrast with the notion that stable anoxia is particularly conducive to complete denitrification without accumulation of N2O. This study provides evidence that lake sediments are a significant source of N2O to the overlying water and may produce large N2O fluxes to the atmosphere during seasonal mixing events.

Water-quality assessment of the Kentucky River basin, Kentucky; nutrients, sediments, and pesticides in streams, 1987-90

USGS Publications Warehouse

Haag, K.H.; Porter, S.D.

1995-01-01

The U.S. Geological Survey investigated the water quality of the Kentucky River Basin in Kentucky as part of the National Water Quality Assessment program. Data collected during 1987-90 were used to describe the spatial and temporal variability of nutrients, suspended sediment, and pesticides in streams. Concentrations of phosphorus were signifi- cantly correlated with urban and agricultural land use. The high phosphorus content of Bluegrass Region soils was an important source of phosphorus in streams. At many sites in urban areas, all of the stream nitrogen load was attributable to wastewater- treatment-plant effluent. Tributary streams affected by agricultural sources of nutrients contained higher densities of phytoplankton than streams that drained forested areas. Data indicate that a consid- erable percentage of total nitrogen was transported as algal biomass during periods of low discharge. Average suspended-sediment concentrations for the study period were positively correlated with dis- charge. There was a downward trend in suspended- sediment concentrations downstream in the Kentucky River main stem during the study. Although a large amount of suspended sediment originates in the Eastern Coal Field Region, contributions of suspended sediment from the Red River and other tributary streams of the Knobs Region also are important. The most frequently detected herbicides in water samples were atrazine, 2,4-D, alachlor, metolachlor, and dicamba. Diazinon, malathion, and parathion were the most frequently detected organo- phosphate insecticides in water samples. Detectable concentrations of aldrin, chlordane, DDT, DDE, dieldrin, endrin, endosulfan, heptachlor, heptachlor epoxide, and lindane were found in streambed- sediment samples.

Sediment-contact fish embryo toxicity assay with Danio rerio to assess particle-bound pollutants in the Tietê River Basin (São Paulo, Brazil).

PubMed

Rocha, Paula Suares; Bernecker, Conny; Strecker, Ruben; Mariani, Carolina Fiorillo; Pompêo, Marcelo Luiz Martins; Storch, Volker; Hollert, Henner; Braunbeck, Thomas

2011-10-01

The Tietê River and its tributary Pinheiros River receive a highly complex organic and inorganic pollutants load from sanitary sewage and industrial sources, as well as agricultural and agroindustrial activities. The aim of the present study was to evaluate the embryotoxic and teratogenic effects of sediments from selected locations in the Tietê River Basin by means of the sediment contact embryo toxicity assay with Danio rerio, in order to provide a comprehensive and realistic insight into the bioavailable hazard potential of these sediment samples. Lethal and sub-lethal effects were recorded, and high embryo toxicity could be found in the samples not only in the vicinity of the megacity São Paulo (Billings reservoir and Pinheiros River samples), but also downstream (in the reservoirs Barra Bonita, Promissão and Três Irmãos). Results confirm that most toxicity is due to the discharges of the metropolitan area of São Paulo. However, they also indicate additional sources of pollutants along the river course, probably from industrial, agricultural and agroindustrial residues, which contribute to the degradation of each area. The sediment contact fish embryo test showed to be powerful tool to detect embryo toxicity in sediments, not only by being a sensitive method, but also for taking into account bioavailability. This test provides an ecological highly realistic and relevant exposure scenario, and should therefore be added in ecotoxicological sediment quality assessments. Copyright © 2011 Elsevier Inc. All rights reserved.

Estimation of Ravine Sediment production using MIKE 11 model, in the lower Le Sueur Watershed, Minnesota

NASA Astrophysics Data System (ADS)

Azmera, L. A.; Miralles-Wilhelm, F. R.; Melesse, A. M.; Belmont, P.; Jennings, C. E.; Thomas, A.; Khalif, F.

2008-12-01

A study of sediment dynamics in the Le Sueur River basin, southern Minnesota has been initiated with the goal of developing an integrated sediment budget. Preliminary analysis of the sediment load to the Minnesota River has shown that the Le Sueur River contributes substantial amount of the sediment transport and deposition. Many deeply incised ravines exist, especially towards the lower Le Sueur River. The ravines are believed to be one of the major sediment producing sources in the river basin. Hence the ravine sediment production should be accounted for in the sediment budget. This study concentrates on the hydrology of the ravines and evaluates the sediment budget at the ravine scale. Field observations from summer 2008 show that most of the bluffs along the main stem of both ravines are actively eroding. Also, landsliding of the steep ravine valley walls and rapid incision of the fluvial channels within the ravine are producing sediment. Several large fill terraces are present along the main stem, towards the mouth of the ravines. Recent incision through these extensive fill terraces may be another sediment producing source. Sediment storage in the ravines also occurs, behind woody debris jams as well as in locations where local baselevel has been raised by the insertion of a culvert. The sediment budget of the ravines would be quantified as the difference between the storage of sediment and the sum of sediments loads derived from the uplands, as well as the bluffs and terraces inside the ravines. Primary locations of major bluffs, terraces, gullies and drainage tiles in the gauged ravines were mapped using GPS. A database of major bluff, terraces, and drainage tiles was built in ArcGIS. Sediment samples from ravine heads, bluffs, terraces and ravine mouth were collected to study the grain size distribution and stratigraphy of major bluffs along the ravines. Sediment transport in the ravines will be modeled using MIKE 11 (DHI group), a dynamic, one-dimensional modeling tool. The model will use data on sediment grain diameter and standard deviation of grain size, soil cover, precipitation and the high resolution LiDAR digital elevation model of the ravines, to quantify the total sediment transport. Key words: Le Sueur River, sediment budget, ravine, Mike11, GIS, Minnesota

Relative Contributions of the Saharan and Sahelian Sources to the Atmospheric Dust Load Over the North Atlantic

NASA Technical Reports Server (NTRS)

Ginoux, Paul; Chin, M.; Torres, O.; Prospero, J.; Dubovik, O.; Holben, B.; Einaudi, Franco (Technical Monitor)

2000-01-01

It has long been recognized that Saharan desert is the major source for long range transport of mineral dust over the Atlantic. The contribution from other natural sources to the dust load over the Atlantic has generally been ignored in previous model studies or been replaced by anthropogenically disturbed soil emissions. Recently, Prospero et.at. have identified the major dust sources over the Earth using TOMS aerosol index. They showed that these sources correspond to dry lakes with layers of sediment deposed in the late Holocene or Pleistocene. One of the most active of these sources seem to be the Bodele depression. Chiapello et al. have analyzed the mineralogical composition of dust on the West coast of Africa. They found that Sahelian dust events are the most intense but are less frequent than Saharan plumes. This suggests that the Bodele depression could contribute significantly to the dust load over the Atlantic. The relative contribution of the Sahel and Sahara dust sources is of importance for marine biogeochemistry or atmospheric radiation, because each source has a distinct mineralogical composition. We present here a model study of the relative contributions of Sahara and Sahel sources to the atmospheric dust aerosols over the North Atlantic. The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate dust distribution in 1996-1997. Dust particles are labeled depending on their sources. In this presentation, we will present the comparison between the model results and observations from ground based measurements (dust concentration, optical thickness and size distribution) and satellite data (TOMS aerosol index). The relative contribution of each source will then be analyzed spatially and temporally.

High methylmercury production under ferruginous conditions in sediments impacted by sewage treatment plant discharges.

PubMed

Bravo, Andrea G; Bouchet, Sylvain; Guédron, Stéphane; Amouroux, David; Dominik, Janusz; Zopfi, Jakob

2015-09-01

Sewage treatment plants (STPs) are important point sources of mercury (Hg) to the environment. STPs are also significant sources of iron when hydrated ferric oxide (HFO) is used as a dephosphatation agent during water purification. In this study, we combined geochemical and microbiological characterization with Hg speciation and sediment amendments to evaluate the impact of STP's effluents on monomethylmercury (MMHg) production. The highest in-situ Hg methylation was found close to the discharge pipe in subsurface sediments enriched with Hg, organic matter, and iron. There, ferruginous conditions were prevailing with high concentrations of dissolved Fe(2+) and virtually no free sulfide in the porewater. Sediment incubations demonstrated that the high MMHg production close to the discharge was controlled by low demethylation yields. Inhibition of dissimilatory sulfate reduction with molybdate led to increased iron reduction rates and Hg-methylation, suggesting that sulfate-reducing bacteria (SRB) may not have been the main Hg methylators under these conditions. However, Hg methylation in sediments amended with amorphous Fe(III)-oxides was only slightly higher than control conditions. Thus, in addition to iron-reducing bacteria, other non-SRB most likely contributed to Hg methylation. Overall, this study highlights that sediments impacted by STP discharges can become local hot-spots for Hg methylation due to the combined inputs of i) Hg, ii) organic matter, which fuels bacterial activities and iii) iron, which keeps porewater sulfide concentration low and hence Hg bioavailable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ecotoxicological and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Short-Neck Clam (Paphia undulata) and Contaminated Sediments in Malacca Strait, Malaysia.

PubMed

Keshavarzifard, Mehrzad; Zakaria, Mohamad Pauzi; Sharifi, Reza

2017-10-01

The distribution, sources, and human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediment and the edible tissue of short-neck clam (Paphia undulata) from mudflat ecosystem in the west coast of Malaysia were investigated. The concentrations of ∑ 16 PAHs varied from 347.05 to 6207.5 and 179.32 to 1657.5 ng g -1 in sediment and short-neck clam samples, respectively. The calculations of mean PEL quotients (mean-PELQs) showed that the ecological risk of PAHs in the sediment samples was low to moderate-high level, whereas the total health risk through ingestion and dermal contact was considerably high. The PAHs biota sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. The source apportionment of PAHs in sediment using positive matrix factorization model indicated that the highest contribution to the PAHs was from diesel emissions (30.38%) followed by oil and oil derivate and incomplete coal combustion (23.06%), vehicular emissions (16.43%), wood combustion (15.93%), and natural gas combustion (14.2%). A preliminary evaluation of human health risk using chronic daily intake, hazard index, benzo[a]pyrene-equivalent (BaP eq ) concentration, and the incremental lifetime cancer risk indicated that PAHs in short-neck clam would induce potential carcinogenic effects in the consumers.

Role of wildfire in controlling the source and flux of particulate organic carbon from a small, mountainous, semi-arid watershed

NASA Astrophysics Data System (ADS)

Hatten, J. A.; Goni, M. A.; Gray, A. B.; Pasternack, G. B.; Warrick, J. A.; Watson, E.; Wheatcroft, R. A.

2016-12-01

The delivery of particulate organic carbon (POC) from rivers to marine sediments is the major long-term sink of CO2 on Earth and a net source of oxygen over millennial time scales. Small mountainous river systems (SMRS) may be responsible for half of the POC delivery to global oceans. The flux of POC in semi-arid SMRS has been thought to be regulated by hydro-geomorphic factors, such as runoff, tectonic uplift rates, and bedrock geology. Fire has been shown to be very important for the flux of suspended sediment from chaparral dominated watersheds, therefore the same should be true for carbon associated with sediment. To date, the role of landscape disturbances such as fire has not been investigated. A large wildfire (2008) in the chaparral-dominated Arroyo Seco watershed, a smaller watershed within the Salinas River basin, provided a unique opportunity to examine the effects of fire on POC source and flux at the watershed-scale. Suspended sediments were collected from the Arroyo Seco for 2 years post fire, and 1 year pre- and 3 years post-fire in the Salinas River. We analyzed these sediments for C, N, 13C, 15N, ad CuO oxidation products (e.g. lignin, char). We found there was an increase in POC flux that is largely a function of elevated sediment flux, but elemental, stable isotope, and biomarker analyses show that both burned and unburned organic matter has contributed to the elevated carbon flux as a result of enhanced surface erosion processes. While these fire-flood events may be rare, sediment associated constituent yield will be greatly underestimated if these events are not considered. Fire-flood events may be especially important to consider in light of shifting fire regimes and more frequent extreme precipitation events predicted as a result of climate change.

Tracing metal sources in core sediments of the artificial lake An-Dong, Korea: Concentration and metal association.

PubMed

Choi, Mansik; Park, Jongkyu; Cho, Dongjin; Jang, Dongjun; Kim, Miseon; Choi, Jongwoo

2015-09-15

The concentration and source of trace metals in the artificial lake An-Dong, which has widespread abandoned mines and a Zn smelter upstream of the drainage basin, were investigated. Soils (18ea), stream waters (15ea) and sediments (15ea) in the main channel and five tributaries downstream of the Zn smelter towards the lake (~ 50 km downstream) were collected. And two core sediments were also taken from the middle of the lake. All samples were analyzed for trace metals in bulk and in a 1N HCl-leached fraction. Although the soil and stream sediments consisted mostly of sand-sized grains, concentrations of metals (Cu, Zn, Cd and Pb) were very high in all samples, including soils, stream waters and sediments at sites near the Zn smelter. However the metal concentrations decreased rapidly downstream, suggesting that the area of impact of the smelter lies within 5 km. Highly enriched metal concentrations were also found in dated core sediments from the lake; while the highest concentrations of Co, Ni, As, Cu, Zn, Cd and Pb were detected in the bottom of the sediment core (dated 1980) they decreased towards 2000, and only Cu, Zn and Cd concentrations increased again in present-day samples. Since the temporal variation in metal concentrations appeared consistent with historical variation in ore mining and Zn smelter production rates, a model combining the production rates of each was developed, which estimated 3%, 12% and 7% contributions from Zn smelter compared to ore mining production rate to levels of Cu, Cd and Zn, respectively, suggesting the different pathways by different sources. In addition, analysis of Cd/Zn and Cu/Zn ratios showed that contamination from ore mining decreased from 1980 to 2000, and smelting processes were most likely responsible for metal enrichment (Cu, Cd and Zn) from 2000 to the present. Copyright © 2015 Elsevier B.V. All rights reserved.

Passive sampling methods for contaminated sediments: Risk assessment and management

PubMed Central

Greenberg, Marc S; Chapman, Peter M; Allan, Ian J; Anderson, Kim A; Apitz, Sabine E; Beegan, Chris; Bridges, Todd S; Brown, Steve S; Cargill, John G; McCulloch, Megan C; Menzie, Charles A; Shine, James P; Parkerton, Thomas F

2014-01-01

This paper details how activity-based passive sampling methods (PSMs), which provide information on bioavailability in terms of freely dissolved contaminant concentrations (Cfree), can be used to better inform risk management decision making at multiple points in the process of assessing and managing contaminated sediment sites. PSMs can increase certainty in site investigation and management, because Cfree is a better predictor of bioavailability than total bulk sediment concentration (Ctotal) for 4 key endpoints included in conceptual site models (benthic organism toxicity, bioaccumulation, sediment flux, and water column exposures). The use of passive sampling devices (PSDs) presents challenges with respect to representative sampling for estimating average concentrations and other metrics relevant for exposure and risk assessment. These challenges can be addressed by designing studies that account for sources of variation associated with PSMs and considering appropriate spatial scales to meet study objectives. Possible applications of PSMs include: quantifying spatial and temporal trends in bioavailable contaminants, identifying and evaluating contaminant source contributions, calibrating site-specific models, and, improving weight-of-evidence based decision frameworks. PSM data can be used to assist in delineating sediment management zones based on likelihood of exposure effects, monitor remedy effectiveness, and, evaluate risk reduction after sediment treatment, disposal, or beneficial reuse after management actions. Examples are provided illustrating why PSMs and freely dissolved contaminant concentrations (Cfree) should be incorporated into contaminated sediment investigations and study designs to better focus on and understand contaminant bioavailability, more accurately estimate exposure to sediment-associated contaminants, and better inform risk management decisions. Research and communication needs for encouraging broader use are discussed. Integr Environ Assess Manag 2014;10:224–236. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:24343931

Depositional history of organic contaminants on the Palos Verdes Shelf, California

USGS Publications Warehouse

Eganhouse, R.P.; Pontolillo, J.

2000-01-01

During more than 60 years, sedimentation on the Palos Verdes Shelf has been dominated by time-varying inputs of municipal wastewater from the Los Angeles County Sanitation Districts (LACSD) and debris from the Portuguese Bend Landslide (PBL). The present study examines the depositional history of wastewater-derived organic contaminants at a site approximately 6-8 km downcurrent from the outfall system. Sediments at this location are impacted by contributions from both sources, but the relative influence of the sources has changed over time. Two classes of hydrophobic organic contaminants (chlorinated hydrocarbons, long-chain alkylbenzenes) were determined in sediment cores collected in 1981 and 1992. Using molecular stratigraphy, we determined average sedimentation rates (cm/year) and mass accumulation rates (g cm-2 year-1) for the following periods: 1955-1965, 1965-1971, 1971-1981 and 1981-1992. The results show that sedimentation and mass accumulation rates increased from 1955 to 1971 and decreased from 1971 to 1981. These trends are consistent with historical information on the emission of suspended solids from the outfall system, indicating that the discharge of wastes dominated sedimentation at the site during this period. In the 1980s and early 1990s, however, mass accumulation rates increased in spite of continually decreasing emissions of wastewater solids. Several lines of evidence indicate that this increase was due to mobilization of debris from the PBL during and after unusually strong winter storms in the 1980s. As a result, heavily contaminated sediments deposited during the years of greatest waste emissions (i.e. 1950-1970) have been buried to greater sub-bottom depths, thereby reducing their availability for mobilization to the overlying water column. These results highlight the dynamic nature of sedimentation in contaminated coastal ecosystems and its importance to the long-term fate and effects of toxic substances.

Using sediment particle size distribution to evaluate sediment sources in the Tobacco Creek Watershed

NASA Astrophysics Data System (ADS)

Liu, Cenwei; Lobb, David; Li, Sheng; Owens, Philip; Kuzyk, ZouZou

2014-05-01

Lake Winnipeg has recently brought attention to the deteriorated water quality due to in part to nutrient and sediment input from agricultural land. Improving water quality in Lake Winnipeg requires the knowledge of the sediment sources within this ecosystem. There are a variety of environmental fingerprinting techniques have been successfully used in the assessment of sediment sources. In this study, we used particle size distribution to evaluate spatial and temporal variations of suspended sediment and potential sediment sources collected in the Tobacco Creek Watershed in Manitoba, Canada. The particle size distribution of suspended sediment can reflect the origin of sediment and processes during sediment transport, deposition and remobilization within the watershed. The objectives of this study were to quantify visually observed spatial and temporal changes in sediment particles, and to assess the sediment source using a rapid and cost-effective fingerprinting technique based on particle size distribution. The suspended sediment was collected by sediment traps twice a year during rainfall and snowmelt periods from 2009 to 2012. The potential sediment sources included the top soil of cultivated field, riparian area and entire profile from stream banks. Suspended sediment and soil samples were pre-wet with RO water and sieved through 600 μm sieve before analyzing. Particle size distribution of all samples was determined using a Malvern Mastersizer 2000S laser diffraction with the measurement range up to 600μm. Comparison of the results for different fractions of sediment showed significant difference in particle size distribution of suspended sediment between snowmelt and rainfall events. An important difference of particle size distribution also found between the cultivated soil and forest soil. This difference can be explained by different land uses which provided a distinct fingerprint of sediment. An overall improvement in water quality can be achieved by managing sediment according to the identified sediment sources in the watershed.

Links between sediment consolidation and Cascadia megathrust slip behaviour

NASA Astrophysics Data System (ADS)

Han, Shuoshuo; Bangs, Nathan L.; Carbotte, Suzanne M.; Saffer, Demian M.; Gibson, James C.

2017-12-01

At sediment-rich subduction zones, megathrust slip behaviour and forearc deformation are tightly linked to the physical properties and in situ stresses within underthrust and accreted sediments. Yet the role of sediment consolidation at the onset of subduction in controlling the downdip evolution and along-strike variation in megathrust fault properties and accretionary wedge structure is poorly known. Here we use controlled-source seismic data combined with ocean drilling data to constrain the sediment consolidation and in situ stress state near the deformation front of the Cascadia subduction zone. Offshore Washington where the megathrust is inferred to be strongly locked, we find over-consolidated sediments near the deformation front that are incorporated into a strong outer wedge, with little sediment subducted. These conditions are favourable for strain accumulation on the megathrust and potential earthquake rupture close to the trench. In contrast, offshore Central Oregon, a thick under-consolidated sediment sequence is subducting, and is probably associated with elevated pore fluid pressures on the megathrust in a region where reduced locking is inferred. Our results suggest that the consolidation state of the sediments near the deformation front is a key factor contributing to megathrust slip behaviour and its along-strike variation, and it may also have a significant role in the deformation style of the accretionary wedge.

Coarse-grained sediment delivery and distribution in the Holocene Santa Monica Basin, California: Implications for evaluating source-to-sink flux at millennial time scales

USGS Publications Warehouse

Romans, B.W.; Normark, W.R.; McGann, M.M.; Covault, J.A.; Graham, S.A.

2009-01-01

Utilizing accumulations of coarse-grained terrigenous sediment from deep-marine basins to evaluate the relative contributions of and history of controls on sediment flux through a source-to-sink system has been difficult as a result of limited knowledge of event timing. In this study, six new radiocarbon (14C) dates are integrated with five previously published dates that have been recalibrated from a 12.5-m-thick turbidite section from Ocean Drilling Program (ODP) Site 1015 in Santa Monica Basin, offshore California. This borehole is tied to high-resolution seismic-reflection profiles that cover an 1100 km2 area of the middle and lower Hueneme submarine fan and most of the basin plain. The resulting stratigraphic framework provides the highest temporal resolution for a thick-bedded Holocene turbidite succession to date, permitting an evaluation of source-to-sink controls at millennial (1000 yr) scales. The depositional history from 7 ka to present indicates that the recurrence interval for large turbidity-current events is relatively constant (300-360 yr), but the volume of sediment deposited on the fan and in the basin plain has increased by a factor of 2 over this period. Moreover, the amount of sand per event on the basin plain during the same interval has increased by a factor of 7. Maps of sediment distribution derived from correlation of seismic-reflection profiles indicate that this trend cannot be attributed exclusively to autogenic processes (e.g., progradation of depocenters). The observed variability in sediment accumulation rates is thus largely controlled by allogenic factors, including: (1) increased discharge of Santa Clara River as a result of increased magnitude and frequency of El Ni??o-Southern Oscillation (ENSO) events from ca. 2 ka to present, (2) an apparent change in routing of coarse-grained sediment within the staging area at ca. 3 ka (i.e., from direct river input to indirect, littoral cell input into Hueneme submarine canyon), and (3) decreasing rates of sea-level rise (i.e., rate of rise slowed considerably by ca. 3 ka). The Holocene history of the Santa Clara River-Santa Monica Basin source-to-sink system demonstrates the ways in which varying sediment flux and changes in dispersal pathways affect the basinal stratigraphic record. ?? 2009 Geological Society of America.

On the distribution and inventories of radionuclides in dated sediments around the Swedish coast.

PubMed

Olszewski, Grzegorz; Andersson, Pål; Lindahl, Patric; Eriksson, Mats

2018-06-01

The activity concentrations and distribution of 137 Cs, 238 Pu, 239+240 Pu, 241 Am, and 210 Pb was determined by the analysis of six sediment cores from the Baltic Sea and Kattegat. The chronology of the sediment cores has been used to evaluate the origin and time trend of the radionuclide sources in these sediments. The sediment cores were dated with a 210 Pb model and the results were validated with fallout peaks, assumed to originate from the global nuclear weapons testing and the Chernobyl accident. Source identification, using the isotopic and radionuclide activity ratios, showed that the Chernobyl accident is the main source of 137 Cs in the Baltic Sea; for 239+240 Pu and 241 Am the dominant source was shown to be fallout from nuclear weapons tests. For 238 Pu and 241 Am the Chernobyl accident had a significant impact on the direct fallout into the Baltic Proper, with up to a 65% contribution in the sediment slices dated to 1986. In these sediment slices the maximum activity ratios of 238 Pu/ 239+240 Pu and 241 Am/ 239+240 Pu were 0.314 ± 0.008 and 1.29 ± 0.06, respectively. The ratios clearly deviate from the corresponding ratios for global nuclear weapons fallout (around 0.028 and 0.54, respectively). Calculated inventories were 63-175 Bq·m -2 for 239+240 Pu, 2.8-7.8 for 238 Pu Bq·m -2 and 0.92-44.4 kBq·m -2 for 137 Cs. Different fallout patterns for 137 Cs and plutonium isotopes from the Chernobyl accident were confirmed through depth profiles analyses. The maximum inventory of 137 Cs was observed in the Bothnian Sea, while Chernobyl-derived plutonium was found to be mostly present in Northern Baltic Proper. The radionuclides distribution in the depth profiles shows how contaminated water affects the sediment as it passes sampling stations according to the current circulation pattern in the Baltic Sea. Additionally, the effect of increased activity concentrations from of river discharges in the most contaminated area in the Bothnian Sea was observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

In-depth molecular characterization and biodegradability of water-extractable organic nitrogen in Erhai Lake sediment.

PubMed

Zhang, Li; Wang, Shengrui; Yang, Jiachun; Xu, Kechen

2018-05-08

Dissolved organic nitrogen (DON) constitutes a significant fraction of the total dissolved nitrogen content of most aquatic systems and is thus a major nitrogen source for bacteria and phytoplankton. The present work applied Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to a compound-level analysis of the depth-dependent molecular composition of water-extractable organic nitrogen (WEON) in lake sediment. The study focused on Erhai Lake, China. It was found that a large portion (from 16.33 ± 7.87 to 39.54 ± 5.77%) of the WEON in the lake sediment was reactive under cultivation by algal or bacteria. The WEON in the mid-region of Erhai sediment particularly exhibited a lower bioavailability, having been less affected by the basin environment. The FT-ICR MS results revealed the presence of thousands of compounds in the Erhai Lake sediment samples collected at different depths, with the N-containing compounds accounting for 28.3-34.4% of all the compounds. The WEON molecular weight was also observed to increase with increasing sediment depth. A van Krevelen diagram showed that the lignin-type components were dominant (~ 56.2%) in the sediment WEON, contributing to its stabilization and reducing the risk of sediment nutrient release. The FT-ICR MS results further revealed 204 overlapping formulas of WEON for each core sediment sample, attributable to the presence of refractory components. It was observed that 78.4% of the formulas were within the lignin-like region, suggesting unique allochthonous DON sources. The aliphatic component proportion of all the unique formulas was also found to increase with increasing sediment depth. This indicates that, with the development and evolution of the Erhai Basin, the more labile WEON components were transformed into more stable lignin-like substrates, with a positive effect on the Lake Erhai ecosystem. Graphical abstract ᅟ.

Methane flux from coastal salt marshes

NASA Technical Reports Server (NTRS)

Bartlett, K. B.; Harriss, R. C.; Sebacher, D. I.

1985-01-01

It is thought that biological methanogenesis in natural and agricultural wetlands and enteric fermentation in animals are the dominant sources of global tropospheric methane. It is pointed out that the anaerobic soils and sediments, where methanogenesis occurs, predominate in coastal marine wetlands. Coastal marine wetlands are generally believed to be approximately equal in area to freshwater wetlands. For this reason, coastal marine wetlands may be a globally significant source of atmospheric methane. The present investigation is concerned with the results of a study of direct measurements of methane fluxes to the atmosphere from salt marsh soils and of indirect determinations of fluxes from tidal creek waters. In addition, measurements of methane distributions in coastal marine wetland sediments and water are presented. The results of the investigation suggest that marine wetlands provide only a minor contribution to atmospheric methane on a global scale.

Occurrence and Risk Assessment of PAHs in Surface Sediments from Western Arctic and Subarctic Oceans

PubMed Central

Lin, Yan; Cai, Minggang; Zhang, Jingjing; Zhang, Yuanbiao; Kuang, Weiming; Liu, Lin; Huang, Peng; Ke, Hongwei

2018-01-01

In the fourth Chinese National Arctic Research Expedition (from July to September, 2010), 14 surface sediment samples were collected from the Bering Sea, Chukchi Sea, and Canadian Basin to examine the spatial distributions, potential sources, as well as ecological and health risk assessment of polycyclic aromatic hydrocarbons (PAHs). The ∑PAH (refers to the sum of 16 priority PAHs) concentration range from 27.66 ng/g to 167.48 ng/g (dry weight, d.w.). Additionally, the concentrations of ∑PAH were highest in the margin edges of the Canadian Basin, which may originate from coal combustion with an accumulation of Canadian point sources and river runoff due to the surface ocean currents. The lowest levels occurred in the northern of Canadian Basin, and the levels of ∑PAH in the Chukchi Sea were slightly higher than those in the Being Sea. Three isomer ratios of PAHs (Phenanthrene/Anthracene, BaA/(BaA+Chy), and LMW/HMW) were used to investigate the potential sources of PAHs, which showed the main source of combustion combined with weaker petroleum contribution. Compared with four sediment quality guidelines, the concentrations of PAH are much lower, indicating a low potential ecological risk. All TEQPAH also showed a low risk to human health. Our study revealed the important role of the ocean current on the redistribution of PAHs in the Arctic. PMID:29649142

Multi-scale constraints of sediment source to sink systems in frontier basins: a forward stratigraphic modeling case study of the Levant region

NASA Astrophysics Data System (ADS)

Hawie, Nicolas; Deschamps, Remy; Granjeon, Didier; Nader, Fadi-Henri; Gorini, Christian; Müller, Carla; Montadert, Lucien; Baudin, François

2015-04-01

Recent scientific work underlined the presence of a thick Cenozoic infill in the Levant Basin reaching up to 12 km. Interestingly; restricted sedimentation was observed along the Levant margin in the Cenozoic. Since the Late Eocene successive regional geodynamic events affecting Afro-Arabia and Eurasia (collision and strike slip deformation)induced fast marginal uplifts. The initiation of local and long-lived regional drainage systems in the Oligo-Miocene period (e.g. Lebanon versus Nile) provoked a change in the depositional pattern along the Levant margin and basin. A shift from carbonate dominated environments into clastic rich systems has been observed. Through this communication we explore the importance of multi-scale constraints (i.e.,seismic, well and field data) in the quantification of the subsidence history, sediment transport and deposition of a Middle-Upper Miocene "multi-source" to sink system along the northernLevant frontier region. We prove through a comprehensive forward stratigraphic modeling workflow that the contribution to the infill of the northern Levant Basin (offshore Lebanon) is split in between proximal and more distal clastic sources as well as in situ carbonate/hemipelagic deposition. In a wider perspective this work falls under the umbrella of multi-disciplinary source to sink studies that investigate the impact of geodynamic events on basin/margin architectural evolutions, consequent sedimentary infill and thus on petroleum systems assessment.

Magmagenesis at Soufriere volcano St Vincent, Lesser Antilles Arc

USGS Publications Warehouse

Heath, E.; Macdonald, R.; Belkin, H.; Hawkesworth, C.; Sigurdsson, Haraldur

1998-01-01

Soufriere volcano of St Vincent (3 wt %, whereas various projections onto phase diagrams are more consistent with relatively anhydrous magmas. Primary magmas at Soufriere were generated by around 15% melting of mid-ocean ridge basalt type mantle sources which had been modified by addition of fluids released from the slab containing contributions from subducted sediments and mafic crust.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Page, D.S.; Boehm, P.D.; Douglas, G.S.

Advanced hydrocarbon fingerprinting methods and improved analytical methods make possible the quantitative discrimination of the multiple sources of hydrocarbons in the benthic sediments of Prince William Sound (PWS) and the Gulf of Alaska. These methods measure an extensive range of polycyclic aromatic hydrocarbons (PAH) at detection levels that are as much as two orders of magnitude lower than those obtained by standard Environmental Protection Agency methods. Nineteen hundred thirty six subtidal sediment samples collected in the sound and the eastern Gulf of Alaska in 1989, 1990, and 1991 were analyzed. Fingerprint analyses of gas chromatography-mass spectrometry data reveal a naturalmore » background of petrogenic and biogenic PAH. Exxon Valdez crude, its weathering products, and diesel fuel refined from Alaska North Slope crude are readily distinguished from the natural seep petroleum background and from each other because of their distinctive PAH distributions. Mixing models were developed to calculate the PAH contributions from each source to each sediment sample. These calculations show that most of the seafloor in PWS contains no detectable hydrocarbons from the Exxon Valdez spill, although elevated concentrations of PAH from seep sources are widespread. In those areas where they were detected, spill hydrocarbons were generally a small increment to the natural petroleum hydrocarbon background. Low levels of Exxon Valdez crude residue were present in 1989 and again in 1990 in nearshore subtidal sediments off some shorelines that had been heavily oiled. By 1991 these crude residues were heavily degraded and even more sporadically distributed. 58 refs., 18 figs., 5 tabs.« less

Source and sink of fluid in pelagic siliceous sediments along a cold subduction plate boundary

NASA Astrophysics Data System (ADS)

Yamaguchi, Asuka; Hina, Shoko; Hamada, Yohei; Kameda, Jun; Hamahashi, Mari; Kuwatani, Tatsu; Shimizu, Mayuko; Kimura, Gaku

2016-08-01

Subduction zones where old oceanic plate underthrusting occurs are characterized by thick pelagic sediments originating from planktonic ooze as well as cold thermal conditions. For a better understanding of dehydration from pelagic sediments and fluid behavior, which would play a key role in controlling the dynamics in the shallow portion of the subduction zone, as observed in the 2011 Tohoku earthquake and tsunami, we investigate cherts in a Jurassic accretionary complex in Japan. The microstructure and microchemistry of these cherts indicate dissolution of SiO2 from a pressure solution seam and precipitation of SiO2 to the ;white chert layer,; which would act as a fluid conduit. The amount of water necessary to precipitate SiO2 in the white chert is 102 times larger than that produced by compaction and silica/clay diagenesis. Other fluid sources, such as hydrated oceanic crust or oceanic mantle, are necessary to account for this discrepancy in the fluid budget. A large amount of external fluid likely contributed to rising pore pressure along cold plate boundaries.

Long term net gains in coastal blue carbon stocks: A search for terrestrial drivers?

NASA Astrophysics Data System (ADS)

Clarke, Jessica; Austin, William; Smeaton, Craig; Winterton, Cathy; Bresnan, Eileen; Davidson, Keith; Lo Giudice Cappelli Lo Giudice Cappelli, Elena; Green, Jade

2017-04-01

Peat and Organic soils covers nearly 66% of Scotland, representing over 50% of the UK's soil carbon stocks. Natural processes such as peatland erosion are accelerated by human activities, such as land management and potentially by the impacts of climate change. We present evidence from the isle of Shetland's west coast voes (sea lochs or fjords) to suggest this process may have accelerated since medieval times. This work is supported by the analyses of short sediment Craib cores (triplicate coring) recovered from 17 sites. We present preliminary chronologies supported by radiocarbon dating and sediment characteristics that highlight both changes in the rate of accumulation and source of sedimentary organic carbon to the west coast Shetland voes during the late Holocene. Scottish coastal sediments contain a significant blue carbon stock, a significant proportion of which derives directly from terrestrial sources. The loss of peatland carbon represents a potentially important contribution (i.e. net gain) in refractory carbon within the marine environment and we present preliminary estimates to assess the significance of these large scale transfers and the subsidy of carbon to the coastal ocean.

Contaminant fate and transport in the Venice Lagoon: results from a multi-segment multimedia model.

PubMed

Sommerfreund, J K; Gandhi, N; Diamond, M L; Mugnai, C; Frignani, M; Capodaglio, G; Gerino, M; Bellucci, L G; Giuliani, S

2010-03-01

Contaminant loadings to the Venice Lagoon peaked from 1950s-1980s and although they have since declined, contaminant concentrations remain elevated in sediment and seafood. In order to identify the relative importance of contaminant sources, inter-media exchange and removal pathways, a modified 10-segment fugacity/aquivalence-based model was developed for octachlorodibenzodioxin/furan (OCDD/F), PCB-180, Pb and Cu in the Venice Lagoon. Results showed that in-place pollution nearby the industrial area, current industrial discharges, and tributary loadings were the main sources of contaminants to the lagoon, with negligible contributions from the atmosphere. The fate of these contaminants was governed by sediment-water exchange with simultaneous advective transport by water circulation. Contaminants circulated amongst the northern and central basins with a small fraction reaching the far southern basin and the Chioggia inlet. As a consequence, we estimated limited contaminant transfer to the Adriatic Sea, trapping the majority of contaminants in the sediment in this "average" circulation scenario which does not account for periodic flooding events. (c) 2009 Elsevier Inc. All rights reserved.

Long-range transport of pollutants to the Falkland Islands and Antarctica: evidence from lake sediment fly ash particle records.

PubMed

Rose, Neil L; Jones, Vivienne J; Noon, Philippa E; Hodgson, Dominic A; Flower, Roger J; Appleby, Peter G

2012-09-18

(210)Pb-dated sediment cores taken from lakes on the Falkland Islands, the South Orkney Islands, and the Larsemann Hills in Antarctica were analyzed for fly ash particles to assess the temporal record of contamination from high temperature fossil-fuel combustion sources. Very low, but detectable, levels were observed in the Antarctic lakes. In the Falkland Island lakes, the record of fly ash extended back to the late-19th century and the scale of contamination was considerably higher. These data, in combination with meteorological, modeling, and fossil-fuel consumption data, indicate most likely sources are in South America, probably Chile and Brazil. Other southern hemisphere sources, notably from Australia, contribute to a background contamination and were more important historically. Comparing southern polar data with the equivalent from the northern hemisphere emphasizes the difference in contamination of the two circumpolar regions, with the Falkland Island sites only having a level of contamination similar to that of northern Svalbard.

Spatial variations in geochemical characteristics of the modern Mackenzie Delta sedimentary system

NASA Astrophysics Data System (ADS)

Vonk, Jorien E.; Giosan, Liviu; Blusztajn, Jerzy; Montlucon, Daniel; Graf Pannatier, Elisabeth; McIntyre, Cameron; Wacker, Lukas; Macdonald, Robie W.; Yunker, Mark B.; Eglinton, Timothy I.

2015-12-01

The Mackenzie River in Canada is by far the largest riverine source of sediment and organic carbon (OC) to the Arctic Ocean. Therefore the transport, degradation and burial of OC along the land-to-ocean continuum for this riverine system is important to study both regionally and as a dominant representative of Arctic rivers. Here, we apply sedimentological (grain size, mineral surface area), and organic and inorganic geochemical techniques (%OC, δ13C-OC and Δ14C-OC, 143Nd/144Nd, δ2H and δ18O, major and trace elements) on particulate, bank, channel and lake surface sediments from the Mackenzie Delta, as well as on surface sediments from the Mackenzie shelf in the Beaufort Sea. Our data show a hydrodynamic sorting effect resulting in the accumulation of finer-grained sediments in lake and shelf deposits. A general decrease in organic carbon (OC) to mineral surface area ratios from river-to-sea furthermore suggests a loss of mineral-bound terrestrial OC during transport through the delta and deposition on the shelf. The net isotopic value of the terrestrial OC that is lost en route, derived from relationships between δ13C, OC and surface area, is -28.5‰ for δ13C and -417‰ for Δ14C. We calculated that OC burial efficiencies are around 55%, which are higher (∼20%) than other large river systems such as the Amazon. Old sedimentary OC ages, up to 12 14C-ky, suggest the delivery of both a petrogenic OC source (with an estimated contribution of 19 ± 9%) as well as a pre-aged terrestrial OC source. We calculated the 14C-age of this pre-aged, biogenic, component to be about 6100 yrs, or -501‰, which illustrates that terrestrial OC in the watershed can reside for millennia in soils before being released into the river. Surface sediments in lakes across the delta (n = 20) showed large variability in %OC (0.92-5.7%) and δ13C (-30.7‰ to -23.5‰). High-closure lakes, flooding only at exceptionally high water levels, hold high sedimentary OC contents (>2.5%) and young biogenic OC with a terrestrial or an autochthonous source whereas no-closure lakes, permanently connected to a river channel, hold sediments with pre-aged, terrestrial OC. The intermediate low-closure lakes, flooding every year during peak discharge, display the largest variability in OC content, age and source, likely reflecting variability in for example the length of river-lake connections, the distance to sediment source and the number of intermediate settling basins. Bank, channel and suspended sediment show variable 143Nd/144Nd values, yet there is a gradual but distinct spatial transition in 143Nd/144Nd (nearly three ε units; from -11.4 to -13.9) in the detrital fraction of lake surface sediments from the western to the eastern delta. This reflects the input of younger Peel River catchment material in the west and input of older geological source material in the east, and suggests that lake sediments can be used to assess variability in source watershed patterns across the delta.

Trends in the sediment yield of the Sacramento River, California, 1957-2001

USGS Publications Warehouse

Wright, Scott A.; Schoellhamer, David H.

2004-01-01

Human activities within a watershed, such as agriculture, urbanization, and dam building, may affect the sediment yield from the watershed. Because the equilibrium geomorphic form of an estuary is dependent in part on the sediment supply from the watershed, anthropogenic activities within the watershed have the potential to affect estuary geomorphology. The Sacramento River drains the northern half of California’s Central Valley and is the primary source of sediment to San Francisco Bay. In this paper, it is shown that the delivery of suspended-sediment from the Sacramento River to San Francisco Bay has decreased by about one-half during the period 1957 to 2001. Many factors may be contributing to the trend in sediment yield, including the depletion of erodible sediment from hydraulic mining in the late 1800s, trapping of sediment in reservoirs, riverbank protection, altered land-uses (such as agriculture, grazing, urbanization, and logging), and levees. This finding has implications for planned tidal wetland restoration activities around San Francisco Bay, where an adequate sediment supply will be needed to build subsided areas to elevations typical of tidal wetlands as well as to keep pace with projected sea-level rise. In a broader context, the study underscores the need to address anthropogenic impacts on watershed sediment yield when considering actions such as restoration within downstream depositional areas.

Stable isotope tracing of trout hatchery carbon to sediments and foodwebs of limestone spring creeks.

PubMed

Hurd, Todd M; Jesic, Slaven; Jerin, Jessica L; Fuller, Nathan W; Miller, David

2008-11-01

Limestone springs support productive ecosystems and fisheries, yet aquaculture may modify or impair these ecosystems. We determined trout hatchery organic contribution to spring creek sediments and foodwebs with natural abundance stable isotope methods. Hatchery feed, waste, and trout were significantly enriched in delta(13)C relative to autotrophs and wild fish. Spring creek sediments were enriched in delta(13)C toward the hatchery endmember relative to reference streams without hatcheries and relative to a larger larger-order, spring-influenced stream. Contribution of hatchery C to spring creek sediments was greatest during March and associated with greatest sediment %C. Contribution of hatchery C to pollution-tolerant isopod diet was 39-51% in a stream receiving limestone spring water via hatchery effluent. Isopods of one spring creek also relied on hatchery-derived C within one month of hatchery closure. Four years later, less pollution pollution-tolerant amphipods dominated and consumed non-vascular over vascular autotrophs (86%). Isopods of a second spring creek with an active hatchery did not appear to be using hatchery matter directly, but were enriched in delta(34)S relative to a spring creek tributary with no hatchery influence. Isopods in both of these streams were relatively enriched in delta(15)N, indicating general nutrient enrichment from surrounding agricultural land use. The contribution of hatchery vs. wild fish in diet of herons and egrets was traced with delta(13)C of guano. These birds were strongly dependent on stocked trout in a spring creek with a recently closed state trout hatchery, and also near another large, state-run hatchery. Heron dependence on hatchery fish in the spring creek decreased with time since hatchery closure. Use of stable isotope natural abundance techniques in karst spring creeks can reveal stream impairment due to aquaculture, specific C sources to bio-indicating consumers, losses of farmed fish to predation, and potential exposure of higher order consumers to contaminants associated with aquaculture.

Forestry best management practices relationships with aquatic and riparian fauna: A review

USGS Publications Warehouse

Warrington, Brooke M.; Aust, W. Michael; Barrett, Scott M.; Ford, W. Mark; Dolloff, C. Andrew; Schilling, Erik B.; Wigley, T. Bently; Bolding, M. Chad

2017-01-01

Forestry best management practices (BMPs) were developed to minimize water pollution from forestry operations by primarily addressing sediment and sediment transport, which is the leading source of pollution from silviculture. Implementation of water quality BMPs may also benefit riparian and aquatic wildlife, although wildlife benefits were not driving forces for BMP development. Therefore, we reviewed literature regarding potential contributions of sediment-reducing BMPs to conservation of riparian and aquatic wildlife, while realizing that BMPs also minimize thermal, nutrient, and chemical pollution. We reached five important conclusions: (1) a significant body of research confirms that forestry BMPs contribute to the protection of water quality and riparian forest structure; (2) data-specific relationships between forestry BMPs and reviewed species are limited; (3) forestry BMPs for forest road construction and maintenance, skid trails, stream crossings, and streamside management zones (SMZs) are important particularly for protection of water quality and aquatic species; (4) stream crossings should be carefully selected and installed to minimize sediment inputs and stream channel alterations; and (5) SMZs promote retention of older-age riparian habitat with benefits extending from water bodies to surrounding uplands. Overall, BMPs developed for protection of water quality should benefit a variety of riparian and aquatic species that are sensitive to changes in water quality or forest structure.

[Sources of Methane in the Boreal Region

NASA Technical Reports Server (NTRS)

1998-01-01

In determining the global methane budget the sources of methane must be balanced with the sinks and atmospheric inventory. The approximate contribution of the different methane sources to the budget has been establish showing the major terrestrial inputs as rice, wetlands, bogs, fens, and tundra. Measurements and modeling of production in these sources suggest that temperature, water table height and saturation along with substratum composition are important in controlling methane production and emission. The isotopic budget of 13 C and D/H in methane can be used as a tool to clarify the global budget. This approach has achieved success at constraining the inputs. Studies using the isotopic approach place constraints on global methane production from different sources. Also, the relation between the two biogenic production pathways, acetate fermentation and CO2 reduction, and the effect of substratum composition can be made using isotope measurements shows the relation between the different biogenic, thermogenic and anthropogenic sources of methane as a function of the carbon and hydrogen isotope values for each source and the atmosphere, tropospheric composition. Methane emissions from ponds and fens are a significant source in the methane budget of the boreal region. An initial study in 1993 and 1994 on the isotopic composition of this methane source and the isotopic composition in relation to oxidation of methane at the sediment surface of the ponds or fen was conducted as part of our BOREAS project. The isotopic composition of methane emitted by saturated anoxic sediment is dependent on the sediment composition and geochemistry, but will be influenced by in situ oxidation, in part, a function of rooted plant activity. The influence of oxidation mediated by rooted plant activities on the isotopic composition of methane is not well known and will depend on the plant type, sediment temperature, and numerous other variables. Information on this isotopic composition is important in both understanding the bio-geochemistry of the system and also in determining the regional and global inputs for the methane isotope budget. In determining the destruction of methane for balancing the atmospheric methane budget soil oxidation must be considered.

U-Pb Detrital Zircon Geochronologic Constraints on Depositional Age and Sediment Source Terrains of the Late Paleozoic Tepuel-Genoa Basin

NASA Astrophysics Data System (ADS)

Griffis, N. P.; Montanez, I. P.; Isbell, J.; Gulbranson, E. L.; Wimpenny, J.; Yin, Q. Z.; Cúneo, N. R.; Pagani, M. A.; Taboada, A. C.

2014-12-01

The late Paleozoic Ice Age (LPIA) is the longest-lived icehouse of the Phanerozoic and the only time a metazoan dominated and vegetated world transitioned from an icehouse climate into a greenhouse. Despite several decades of research, the timing, extent of glaciation and the location of ice centers remain unresolved, which prohibits reconstruction of ice volume. The Permo-Carboniferous sediments in the Tepuel-Genoa Basin, Patagonia contains a near complete record of sedimentation from the lower Carboniferous through lower Permian. Outsized clasts, thin pebble-rich diamictites and slumps represent the last of the late Paleozoic glacially influenced deep-water marine sediments in the Mojón de Hierro Fm. and the Paleozoic of Patagonia. U-Pb analysis of detrital zircons separated from slope sediments reveal groupings (20 myr bins, n≥5 zircons) with peak depositional ages of 420, 540 to 660 and 1040 Ma. Zircon age populations recovered from the Mojón de Hierro Fm. compare well with bedrock ages of the Deseado Massif of SE Patagonia, suggesting this may be a potential source of sediments. The maximum depositional age of the sediments is 306.05 ± 3.7 Ma (2σ) as determined by the median age of the two youngest concordant zircons that overlap in error. The youngest zircon from the analysis yields a 238U/206Pb age of 301.3 ± 4.5 Ma (2σ; MSWD = 2.3). Younger zircons from the analysis compare well with the age of granite bedrock exposed along the basin margin to the E-NE suggesting they may reflect a more proximal source. These data, which indicate a maximum age of late Carboniferous for the Mojón de Hierro Fm, provide the first geochemical constraints for the timing of final deposition of glaciomarine sediments in the Tepuel-Genoa Basin, and contributes to the biostratigraphic correlation of the late Paleozoic succession in Patagonia with other key LPIA basins that has thus far been hindered by faunal provincialism.

Understanding catchment scale sediment sources using geochemical tracers

NASA Astrophysics Data System (ADS)

Ferreira, Carla S. S.; Walsh, Rory P. D.; Shakesby, Richard A.; Steenhuis, Tammo S.; Ferreira, António J. D.; Coelho, Celeste O. A.

2013-04-01

It is well-established that urbanization leads to increased erosion (at least locally) as well as enhanced overland flow and streamflow peaks. Less is known about how the spatial distribution of erosion sources and scale of increases in erosion vary with the nature of urbanization in different climatic and socio-economic settings. This is important in order to prevent or reduce adverse impacts of erosion on downstream sedimentation, channel siltation and shifting, and river pollution. This paper adopts a sediment fingerprinting approach to assess the impact of partial urbanization and associated land-use change on sediment sources within a peri-urban catchment (6 km2), Ribeira dos Covões on the outskirts of the city of Coimbra in central Portugal. Urban land-use has increased from just 6% in 1958 to 30% in 2009. The urban pattern includes some well-defined urban residential centres, but also areas of discontinuous urban sprawl, including educational, health and small industrial facilities, numerous new roads and an enterprise park is under construction on the upper part of the catchment. The catchment has a wet Mediterranean climate and the lithology comprises sandstone in the west and limestone in the east. Soil depth is generally >40cm. The average slope angle is 8° (maximum 47°). Altitude ranges from 30m to 205m. A sediment fingerprinting approach was adopted to help establish the relative importance of sediment inputs from different urban areas. During September 2012 current bed-sediment samples (0-3 cm depth) were collected from 11 channel sites along the main stream and in different tributaries. At sites where bed-sediment was deeper, additional samples were taken at 3cm intervals to a maximum depth of around 42cm. In addition, overbank sediment samples (0-3cm depth) were collected at 11 locations around the catchment. All samples were oven-dried (at 38°C) and different particle size fractions (0.125-2mm, 0.063-0.125mm and <0.063mm) obtained, where the <0.063mm fraction was considered equivalent to the suspended sediment load during storm events. The elemental composition (33 elements) of each fraction was assessed using a Niton X-ray fluorescence analyzer. The results were used to identify distinctive composite signatures of each tributary catchment and their influence on the geochemistry of the catchment outlet bed-sediment was explored. An unmixing model was applied to estimate the relative contribution of each tributary to channel-stored sediment at the catchment outlet. Many of the chemical elements analysed, including Zr, Sr, Zn and Ti, showed significant differences between sandstone and limestone areas. The closeness of values at the catchment outlet to those of sandstone stream bed-sediment indicates that most of the current catchment erosion is derived from the sandstone area. This is supported by the higher measured discharges and suspended sediment concentrations in storm events from the latter. Eroded sediments from urban areas still under construction also showed distinctive characteristics. It is concluded that this methodology represents a potentially useful tool for river managers and policy-makers to detect and assess sediment sources in urbanized catchments.

Influence of sediment storage on downstream delivery of contaminated sediment

USGS Publications Warehouse

Malmon, Daniel V.; Reneau, Steven L.; Dunne, Thomas; Katzman, Danny; Drakos, Paul G.

2005-01-01

Sediment storage in alluvial valleys can strongly modulate the downstream migration of sediment and associated contaminants through landscapes. Traditional methods for routing contaminated sediment through valleys focus on in‐channel sediment transport but ignore the influence of sediment exchanges with temporary sediment storage reservoirs outside the channel, such as floodplains. In theory, probabilistic analysis of particle trajectories through valleys offers a useful strategy for quantifying the influence of sediment storage on the downstream movement of contaminated sediment. This paper describes a field application and test of this theory, using 137Cs as a sediment tracer over 45 years (1952–1997), downstream of a historical effluent outfall at the Los Alamos National Laboratory (LANL), New Mexico. The theory is parameterized using a sediment budget based on field data and an estimate of the 137Cs release history at the upstream boundary. The uncalibrated model reasonably replicates the approximate magnitude and spatial distribution of channel‐ and floodplain‐stored 137Cs measured in an independent field study. Model runs quantify the role of sediment storage in the long‐term migration of a pulse of contaminated sediment, quantify the downstream impact of upstream mitigation, and mathematically decompose the future 137Cs flux near the LANL property boundary to evaluate the relative contributions of various upstream contaminant sources. The fate of many sediment‐bound contaminants is determined by the relative timescales of contaminant degradation and particle residence time in different types of sedimentary environments. The theory provides a viable approach for quantifying the long‐term movement of contaminated sediment through valleys.

Molecular characterization of lake sediment WEON by Fourier transform ion cyclotron resonance mass spectrometry and its environmental implications.

PubMed

Zhang, Li; Wang, Shengrui; Xu, Yisheng; Shi, Quan; Zhao, Haichao; Jiang, Bin; Yang, Jiachun

2016-12-01

The compositional properties of water-extractable organic nitrogen (WEON) affect its behavior in lake ecosystems. This work is the first comprehensive study using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for the characterization of the molecular composition of WEON in lake sediment. In sediments of Erhai Lake in China, this study found complex WEON species, with N-containing compounds in the northern, central, and southern regions contributing 34.47%, 42.44%, and 40.6%, respectively, of total compounds. Additionally, a van Krevelen diagram revealed that lignin components were dominant in sediment WEON structures (68% of the total), suggesting terrestrial sources. Furthermore, this study applied ESI-FT-ICR-MS to the examination of the environmental processes of lake sediment WEON on a molecular level. The results indicated that sediment depth impacted WEON composition and geochemical processes. Compared with other ecosystems, the double bond equivalent (DBE) value was apparently lower in Erhai sediment, indicating the presence of relatively fewer and smaller aromatic compounds. In addition, the presence of a large number of N-containing species and abundant oxidized nitrogen functional compounds that were likely to biodegrade may have further increased the potential releasing risk of WEON from Erhai sediment under certain environmental conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Role of land use change in landslide-related sediment fluxes in tropical mountain regions

NASA Astrophysics Data System (ADS)

Guns, M.; Vanacker, V.; Demoulin, A.

2012-04-01

Tropical mountain regions are characterised by high denudation rates. Landslides are known to be recurrent phenomena in active mountain belts, but their contribution to the overall sedimentary fluxes is not yet well known. Previous studies on sedimentary cascades have mostly focused on natural environments, without considering the impact of human and/or anthropogenic disturbances on sedimentary budgets. In our work, we hypothesise that human-induced land use change might alter the sediment cascade through shifts in the landslide magnitude-frequency relationship. We have tested this assumption in the Virgen Yacu catchment (approximately 11km2), in the Ecuadorian Cordillera Occidental. Landslide inventories and land use maps were established based on a series of sequential aerial photos (1963, 1977, 1984 and 1989), a HR Landsat image (2001) and a VHR WorldView2 image (2010). Aerial photographs were ortho-rectified, and coregistred with the WorldView2 satellite image. Field campaigns were realised in 2010 and 2011 to collect field-based data on landslide type and geometry (depth, width and length). This allowed us to establish an empirical relationship between landslide area and volume, which was then applied to the landslide inventories to estimate landslide-related sediment production rates for various time periods. The contribution of landslides to the overall sediment flux of the catchment was estimated by comparing the landslide-related sediment production to the total sediment yield. The empirical landslide area-volume relationship established here for the Ecuadorian Andes is similar to that derived for the Himalayas. It suggests that landslides are the main source of sediment in this mountainous catchment. First calculations indicate that human-induced land use change alters the magnitude-frequency relationship through strong increase of small landslides.

Diatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)

NASA Astrophysics Data System (ADS)

Zúñiga, Diana; Santos, Celia; Froján, María; Salgueiro, Emilia; Rufino, Marta M.; De la Granda, Francisco; Figueiras, Francisco G.; Castro, Carmen G.; Abrantes, Fátima

2017-03-01

The objective of the current work is to improve our understanding of how water column diatom's abundance and assemblage composition is seasonally transferred from the photic zone to seafloor sediments. To address this, we used a dataset derived from water column, sediment trap and surface sediment samples recovered in the NW Iberian coastal upwelling system. Diatom fluxes (2.2 (±5.6) 106 valves m-2 d-1) represented the majority of the siliceous microorganisms sinking out from the photic zone during all studied years and showed seasonal variability. Contrasting results between water column and sediment trap diatom abundances were found during downwelling periods, as shown by the unexpectedly high diatom export signals when diatom-derived primary production achieved their minimum levels. They were principally related to surface sediment remobilization and intense Minho and Douro river discharge that constitute an additional source of particulate matter to the inner continental shelf. In fact, contributions of allochthonous particles to the sinking material were confirmed by the significant increase of both benthic and freshwater diatoms in the sediment trap assemblage. In contrast, we found that most of the living diatom species blooming during highly productive upwelling periods were dissolved during sinking, and only those resistant to dissolution and the Chaetoceros and Leptocylindrus spp. resting spores were susceptible to being exported and buried. Furthermore, Chaetoceros spp. dominate during spring-early summer, when persistent northerly winds lead to the upwelling of nutrient-rich waters on the shelf, while Leptocylindrus spp. appear associated with late-summer upwelling relaxation, characterized by water column stratification and nutrient depletion. These findings evidence that the contributions of these diatom genera to the sediment's total marine diatom assemblage should allow for the reconstruction of different past upwelling regimes.

Sources, transport and deposition of terrestrial organic material: A case study from southwestern Africa

NASA Astrophysics Data System (ADS)

Herrmann, Nicole; Boom, Arnoud; Carr, Andrew S.; Chase, Brian M.; Granger, Robyn; Hahn, Annette; Zabel, Matthias; Schefuß, Enno

2016-10-01

Southwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific δ13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific δ13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific δ13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific δ13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent.

A summary of total mercury concentrations in flora and fauna near common contaminant sources in the Gulf of Mexico.

PubMed

Lewis, M; Chancy, C

2008-02-01

Total mercury concentrations are summarized for environmental media and biota collected from near-coastal areas, several impacted by contaminant sources common to the Gulf of Mexico. Water, sediment, fish, blue crabs, oysters, clams, mussels, periphyton and seagrasses were collected during 1993-2002 from targeted areas affected by point and non-point source contaminants. Mean concentrations in water and sediment were 0.02 (+/-1 standard deviation=0.06) microg l(-1) and 96.3 (230.8) ng g(-1) dry wt, respectively. Mean total mercury concentrations in fish, blue crabs, brackish clams and mussels were significantly greater than those in sediment, seagrass, colonized periphyton and oysters. Concentrations (ng g(-1) dry wt) averaged 23.1 (two seagrass species), 220.1 (oysters), 287.8 (colonized periphyton), 604.0 (four species of freshwater mussels), 772.4 (brackish clam), 857.9 (blue crabs) and 933.1 (nine fish species). Spatial, intraspecific and interspecific variability in results limited most generalizations concerning the relative mercury contributions of different stressor types. However, concentrations were significantly greater for some biota collected from areas receiving wastewater discharges and golf course runoff (fish), agricultural runoff (oysters) and urban stormwater runoff (colonized periphyton and sediment). Marine water quality criteria and proposed sediment quality guidelines were exceeded in 1-12% of total samples. At least one seafood consumption guideline, criteria or screening value were exceeded in edible tissues of blue crabs (6% total samples) and nine fish species (8-33% total samples) but all residues were less than the US Federal Drug Administration action limit of 1.0 ppm and the few reported toxic effect concentrations available for the targeted biota.

Sediment Fingerprinting Using Carbon and Nitrogen Stable Isotopes in the Upper Palouse Watershed, Northwestern Idaho

NASA Astrophysics Data System (ADS)

Fox, J. F.; Papanicolaou, A. T.

2003-12-01

Unwarranted soil erosion creates detrimental problems for watershed users and for habitats and human infrastructure that experience increased suspended sediment in surface water. Identification and mitigation of erosion prone uplands relies on the realization that land uses (i.e. agriculture, forest, industrial, pasture, etc.) "produce sediment differently" at the watershed scale. Quantification of sediment production from various land uses is deemed feasible by using sediment-particle fingerprinting. This technique utilizes vegetative derived carbon (C) and nitrogen (N) stable isotopes and the carbon/nitrogen (C/N) atomic ratio of sediments to identify sediment producing land uses. Past research has established differences between C and N isotopic signatures and C/N ratios for soils under forest vs. agriculture (i.e. grasses and wheat) land cover. The current research rigorously examines these distinct signatures through isotopic analysis of field soils from the Palouse River Watershed of Northwestern Idaho preceded with statistical analyses to establish soil uniqueness. In addition, stream sediments are preliminarily analyzed to identify their origin with the goal of establishing a blueprint methodology for estimating sediment source and erosion rates within the watershed. Prior to field sampling of source soils, a statistical-experimental design was established with the intent to capture spatial and temporal variations and random errors of C and N isotopic signatures and C/N ratios within the forest and agriculture land uses. Factors including, elevation, slope topography, and season, were assessed by excavating over 300 samples during 4 seasons (i.e. May 2002, August 2002, November 2002, and March 2003) and at numerous locations throughout the watershed. Atomic analyses was performed at the University of Idaho Natural Resources Stable Isotope Laboratory using a Costech 4010 Elemental Combustion System connected with a continuous flow inlet system to the Finnigan MAT Delta Plus isotope ratio mass spectrometer. The statistical analysis of variance (ANOVA) with C and N isotopic signatures and C/N ratios as three independent response variables was administered to identify the agriculture and forested uniqueness, and discriminant analysis was used to create an organic fingerprint parameter which weights the contribution of C and N isotopic signatures and C/N ratios to the land cover separation. Results indicate uniqueness of the N isotope C/N ratio for the forest and agriculture sediment sources and little distinction possible for the C isotope signature. The organic fingerprint parameter was then calculated and coupled with in-stream sediment isotopic data using a simple end-member model. Preliminary results indicate that C and N isotopic signatures and C/N ratios will serve as a useful technique in quantifying erosive source rates and understanding upland erosion processes.

Contribution of sediment fluxes and transformations to the summer nitrogen budget of an Upper Mississippi River backwater system

USGS Publications Warehouse

James, W.F.; Richardson, W.B.; Soballe, D.M.

2008-01-01

Routing nitrate through backwaters of regulated floodplain rivers to increase retention could decrease loading to nitrogen (N)-sensitive coastal regions. Sediment core determinations of N flux were combined with inflow-outflow fluxes to develop mass balance approximations of N uptake and transformations in a flow-controlled backwater of the Upper Mississippi River (USA). Inflow was the dominant nitrate source (>95%) versus nitrification and varied as a function of source water concentration since flow was constant. Nitrate uptake length increased linearly, while uptake velocity decreased linearly, with increasing inflow concentration to 2 mg l-1, indicating limitation of N uptake by loading. N saturation at higher inflow concentration coincided with maximum uptake capacity, 40% uptake efficiency, and an uptake length 2 times greater than the length of the backwater. Nitrate diffusion and denitrification in sediment accounted for 27% of the backwater nitrate retention, indicating that assimilation by other biota or denitrification on other substrates were the dominant uptake mechanisms. Ammonium export from the backwater was driven by diffusive efflux from the sediment. Ammonium increased from near zero at the inflow to a maximum mid-lake, then declined slightly toward the outflow due to uptake during transport. Ammonium export was small compared to nitrate retention. ?? 2007 Springer Science+Business Media B.V.

Maximum sedimentation ages and provenance of metasedimentary rocks from Tinos Island, Cycladic blueschist belt, Greece

NASA Astrophysics Data System (ADS)

Hinsken, Tim; Bröcker, Michael; Berndt, Jasper; Gärtner, Claudia

2016-10-01

U-Pb zircon ages of five metasedimentary rocks from the Lower Unit on Tinos Island (Cycladic blueschist belt, Greece) document supply of detritus from various Proterozoic, Paleozoic and Mesozoic source rocks as well as post-depositional metamorphic zircon formation. Essential features of the studied zircon populations are Late Cretaceous (70-80 Ma) maximum sedimentation ages for the lithostratigraphic succession above the lowermost dolomite marble, significant contributions from Triassic to Neoproterozoic source rocks, minor influx of detritus recording Paleoproterozoic and older provenance (1.9-2.1, 2.4-2.5 and 2.7-2.8 Ga) and a lack or paucity of zircons with Mesoproterozoic ages (1.1-1.8 Ga). In combination with biostratigraphic evidence, the new dataset indicates that Late Cretaceous or younger rocks occur on top of or very close to the basal Triassic metacarbonates, suggesting a gap in the stratigraphic record near the base of the metamorphic succession. The time frame for sediment deposition is bracketed by the youngest detrital zircon ages (70-80 Ma) and metamorphic overgrowths that are related to high-pressure/low-temperature overprinting in the Eocene. This time interval possibly indicates a significant difference to the sedimentation history of the southern Cyclades, where Late Cretaceous detrital zircons have not yet been detected.

Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas

USGS Publications Warehouse

Kuivila, Kathryn; Hladik, Michelle; Ingersoll, Christopher G.; Kemble, Nile E.; Moran, Patrick W.; Calhoun, Daniel L.; Nowell, Lisa H.; Gilliom, Robert J.

2012-01-01

A nationally consistent approach was used to assess the occurrence and potential sources of pyrethroid insecticides in stream bed sediments from seven metropolitan areas across the United States. One or more pyrethroids were detected in almost half of the samples, with bifenthrin detected the most frequently (41%) and in each metropolitan area. Cyhalothrin, cypermethrin, permethrin, and resmethrin were detected much less frequently. Pyrethroid concentrations and Hyalella azteca mortality in 28-d tests were lower than in most urban stream studies. Log-transformed total pyrethroid toxic units (TUs) were significantly correlated with survival and bifenthrin was likely responsible for the majority of the observed toxicity. Sampling sites spanned a wide range of urbanization and log-transformed total pyrethroid concentrations were significantly correlated with urban land use. Dallas/Fort Worth had the highest pyrethroid detection frequency (89%), the greatest number of pyrethroids (4), and some of the highest concentrations. Salt Lake City had a similar percentage of detections but only bifenthrin was detected and at lower concentrations. The variation in pyrethroid concentrations among metropolitan areas suggests regional differences in pyrethroid use and transport processes. This study shows that pyrethroids commonly occur in urban stream sediments and may be contributing to sediment toxicity across the country.

Historical record of polychlorinated biphenyls (PCBs) and special occurrence of PCB 209 in a shallow fresh-water lake from eastern China.

PubMed

Huo, Shouliang; Li, Chaocan; Xi, Beidou; Yu, Zhiqiang; Yeager, Kevin M; Wu, Fengchang

2017-10-01

Concentrations of polychlorinated biphenyls (PCBs) were measured in dated sediment cores collected from the fifth largest freshwater lake in China, Lake Chaohu, to investigate PCB temporal trends, accumulation, and environmental fate. Total PCB concentrations in Lake Choahu sediments ranged from 0.03 to 24.11 ng g -1 (d.w.). PCB 209 was the dominant congener, accounting for 45.5%-83.9% of total PCBs detected after the mid-20th century. All PCB congeners were positively correlated with total organic carbon (TOC) concentrations. TOC-normalized PCB concentrations exhibited three stages of variation over time: a slight increase from their emergence in the early 20th century, followed by a rapid increase since the late 1950s (peaking in the late 1980s), before a general decrease to the present. Both compositional PCB patterns and principal component analysis (PCA) indicated a source switch from commercial PCBs to other sources. Major contributions of PCB209 to total PCBs in Lake Chaohu sediments is a highlight of this study, with results showing that PCB209 was derived from the upstream city of Hefei, and the production of phthalocyanine-type pigments is the likely source of PCB209. Copyright © 2017 Elsevier Ltd. All rights reserved.

Apportioning carbon sources of authigenic carbonate of extremely 13C-depleted foraminifera from the western North Pacific sediments: Implication from the coupled 13C and 14C isotopic mass balance approach

NASA Astrophysics Data System (ADS)

Uchida, M.; Ohkushi, K.; Ahagon, N.; Kimoto, K.; Inagaki, F.; Shibata, Y.

2005-12-01

Recently, Uchida et al. (G-cubed, 2004) and Ohkushi et al. (G-cubed, 2005) interprete /delta 13C variations of planktonic and benthic foraminifera found in Last Glacial sediments in off Shimokita Peninsula and Tokachi as evidence for periodic releases of methane, arising from the dissociation of methane hydrate, and its subsequent oxidation in bottom- and/or surface-water environments. According to recent observations of anomalous bottom-simulating reflections, northwest Pacific marginal sediments around Japan main islands bear large abundances of methane hydrate. In this study, analyzed piston cores (42° 21.42' N, 144° 13.36' E) at a water depth 1066-m was retrieved from the off Tokachi continental slope in the Oyashio current region, where recently is found to bear immense amounts of methane hydrate. The piston core covered past 22 ka with high-resolution. Here we showed that carbon isotope signals indicated that planktonic and benthic foraminifera in several glacial sediment layers in the core were highly depleted in13 C; both the planktonic and benthic foraminiferal /delta 13C values ranged from about -10/permil to -2/permil. Most foraminiferal tests in these horizons were brown as a result of postdepositional alteration. Foraminiferal oxygen isotopes fluctuated abnormally in the glacial sediment layers, showing small (about 0.5/permil) positive shifts relative to normal glacial values. We attributed the positive shifts to authigenic carbonate formation in the foraminiferal tests. In order to decipher the relation between foraminifera carbon isotopic signal and methane release from the seafloor, we have apportioned carbon sources (methane from methane hydrate or not) of foraminiferal carbon isotopic anomalies using dual mass balance isotopic model (14C/ 12C and 13C/ 12C). It has been suggested that sulfate-dependent anaerobic methane oxidation (AOM) dominates carbon oxidation and attendant authigenic carbonate precipitation to foraminifera. To this assumption, we have quantified the relative contributions of dissolved carbon dioxide (/SigmaCO/_2) from oxidation of methane in anomaly foraminifera. At the layer of 17,840 years cal. age with planktonic foraminifera of dual isotopic data (/delta 13C: -8.1/permil and /Delta 14C: -847/permil) , relative contribution of carbon from authigenic carbonate was 17 percent of total carbonate and its /delta 13C was -48.1/permil, suggesting indirect records of enhanced incorporation of 13C-depleted CO2 formed by anaerobic methane oxidation process that use 12C-enriched methane as their main source of carbon. Moreover, biomarker and phylogenetic compositions were investigated in the light of the past activity of methanotrophic bacteria in the oxic-anoxic interface in the overlying water column and/or surface sediment. Mg/Ca ratios were also analyzed to evaluate foraminiferal 13C depleted carbonate precipitation in comparison with authigenic carbonate produced in the cold seep environment. In the conference, we discuss about what mechanism contribute to authigenic carbon precipitation in terms with carbon source with 13C-depleted foraminifera.

Suspended Sediment Load and Sediment Yield During Floods and Snowmelt Runoff In The Rio Cordon (northeastern Italy)

NASA Astrophysics Data System (ADS)

Lenzi, M. A.

Suspended sediment transport in high mountain streams display a grater time-space variability and a shorter duration (normally concentrated during the snowmelt period and the duration time of single floods) than in larger lowland rivers. Suspended sedi- ment load and sediment yield were analysed in a small, high-gradient stream of East- ern Italian Alps which was instrumented to measure in continuous water discharge and sediment transport. The research was conducted in the Rio Cordon, a 5 Km2 small catchment of the Dolomites. The ratio of suspended to total sediment yield and the re- lations between sediment concentration and water discharge were analysed for eleven floods which occurred from 1991 to 2001. Different patterns of hysteresis in the re- lation between suspended sediment and discharge were related to types and locations of active sediment sources. The within-storm variation of particle size of suspended sediment during a mayor flood (September 1994, 30 years

Relative contribution of iron reduction to sediments organic matter mineralization in contrasting habitats of a shallow eutrophic freshwater lake.

PubMed

Chen, Mo; Jiang, He-Long

2016-06-01

Iron reduction is one of the important organic matter (OM) mineralization pathway in sediments. Here we investigated the rates and the relative contribution of iron reduction to OM mineralization in Zhushan bay (ZSB, cyanobacterial bloom biomass (CBB)-dominated habitats) and East Taihu Lake (ETL, submerged macrophypes (SM)-dominated habitats) of Lake Taihu, China. Anaerobic microcosm incubation revealed that the rate of iron reduction at ZSB (4.42 μmol cm(-3) d(-1)) in summer was almost 1.5 times higher than at ETL (3.13 μmol cm(-3) d(-1)). Iron reduction accounted for 66.5% (ZSB) and 31.8% (ETL) of total anaerobic carbon mineralization, respectively. No detectable methanogenesis was found at ZSB, while methanogenesis was responsible for 16.7% of total anaerobic respiration in sediments of ETL. Geochemical analysis of solid phase constituents indicated that ZSB surface sediments experienced highly oxidizing conditions with much higher amorphous Fe(III) (71 mmol m(-2)) than ETL (11 mmol m(-2)). Conversely, AVS inventories at ETL (38 mmol m(-2)) were up to 30 times higher than at ZSB (1.27 mmol m(-2)), indicating significant sulfate reduction in sediments of ETL. Overall results suggested that varying carbon sources and distinct geochemical characterizations of the sediments in contrasting habitats significantly influenced the rate of iron reduction and the pathway of C mineralization in a large freshwater lake. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cenozoic North American Drainage Basin Evolution, Sediment Yield, and Accumulation in the Gulf of Mexico Basin

NASA Astrophysics Data System (ADS)

Galloway, W.; Ganey-Curry, P. E.

2010-12-01

The Cenozoic fill of the Gulf of Mexico basin contains a continuous record of sediment supply from the North American continental interior for the past 65 million years. Regional mapping of unit thickness and paleogeography for 18 depositional episodes defines patterns of shifting entry points of continental fluvial systems and quantifies the total volume of sediment supplied during each episode. Eight fluvio-deltaic depocenters, named for geographic similarities to entry points and drainage basins of modern rivers, are present. From southwest to northeast, they are the Rio Bravo, Rio Grande, Guadalupe, Colorado, Houston-Brazos, Red, Mississippi, and Tennessee axes. Sediment volume was calculated from hand-contoured unit thickness maps compiled from basin-wide well and seismic control. Using a GIS algorithm to sum volumes within polygons bounding interpreted North American river contribution, the total extant volume was then calculated. General compaction factors were used to convert modern volume to quantitative approximations of total grain volume. Grain volume rate of supply for each depositional episode was then calculated. Values vary by more than an order of magnitude. Supply rate has commonly varied by two-fold or more between successive depositional episodes. Sediment supply is a significant, independent variable in development of stratigraphic sequences within the Gulf basin. Paleogeographic maps of the continental interior for eleven Cenozoic time intervals display the evolving and complex interplay of intracontinental tectonism, climate change, and drainage basin evolution. Five tectono-climatic eras are differentiated: Paleocene late Laramide era; early to middle Eocene terminal Laramide era; middle Cenozoic (Late Eocene—Early Miocene) dry, volcanogenic era; middle Neogene (Middle—Late Miocene) arid, extensional era; and late Neogene (Plio—Pleistocene) monsoonal, epeirogenic uplift era. Sediment supply to the GOM reflects the interplay of (1) areal extent of river drainage basins, (2) source area relief, (3) climate of the source areas and tributary systems, (4) source lithology, and (5) sediment storage within the upper drainage basin. Climate has played an important and complex role in modulating supply. In wet tropical to temperate climate regimes, abundant runoff efficiently removed entrained sediment. Arid climate limited runoff; resultant transport-limited tributaries and trunk streams deposited aggradational alluvial aprons, storing sediment in the drainage basin even in the absence of a structural depression. Eolian deposition commonly accompanied such alluvial aggradation. In contrast, seasonality and consequent runoff variability favored erosion and efficient sediment evacuation from the upper parts of drainage basins. Tectonism has played a prominent but equally complex role. Elevation of uplands by compression, crustal heating, or extrusive volcanism created primary loci of erosion and high sediment yield. At the same time, accompanying subsidence sometimes created long-lived sediment repositories that intercepted and sequestered sediment adjacent to sources. Regional patterns of uplift and subsidence relocated drainage divides and redirected trunk stream paths to the Gulf margin.

Spatial variability in the abundance, composition, and age of organic matter in surficial sediments of the East China Sea

NASA Astrophysics Data System (ADS)

Wu, Ying; Eglinton, Timothy; Yang, Liyang; Deng, Bing; Montluçon, Daniel; Zhang, Jing

2013-12-01

the sources and fate of organic matter (OM) sequestered in continental margin sediments is of importance because the mode and efficiency of OM burial impact the carbon cycle and the regulation of atmospheric CO2 over long time scales. We carried out molecular (lignin-derived phenols from CuO oxidation), elemental, isotopic (δ13C, Δ14C), and sedimentological (grain size and mineral surface area) analyses in order to examine spatial variability in the abundance, source, age of surface sediments of the East China Sea. Higher terrigenous organic matter values were found in the main accumulating areas of fluvial sediments, including the Changjiang (Yangtze) Estuary and Zhejiang-Fujian coastal zone. Isotopic and biomarker data suggest that the sedimentary OM in the inner shelf region was dominated by aged (Δ14C = -423 ± 42‰) but relatively lignin-rich OM (Λ = 0.94 ± 0.57 mg/100 mg OC) associated with fine-grained sediments, suggesting important contributions from soils. In contrast, samples from the outer shelf, while of similar age (Δ14 C = -450 ± 99‰), are lignin poor (Λ = 0.25 ± 0.14 mg/100 mg OC) and associated with coarse-grained material. Regional variation of lignin phenols and OM ages indicates that OM content is fundamentally controlled by hydrodynamic sorting (especially, sediment redistribution and winnowing) and in situ primary production. Selective sorption of acid to aldehyde in clay fraction also modified the ratios of lignin phenols. The burial of lignin in East China Sea is estimated to be relatively efficient, possibly as a consequence of terrigenous OM recalcitrance and/or relatively high sedimentation rates in the Changjiang Estuary and the adjacent Zhejing-Fujian mud belt.

Microbial Communities Associated with Phosphorite-bearing Sediments

NASA Astrophysics Data System (ADS)

Zoss, R.; Bailey, J.; Flood, B.; Jones, D. S.

2016-12-01

Phosphorus is a limiting nutrient in the environment and is an important component of many biological molecules. Calcium phosphate mineral deposits known as phosphorites, are also the primary source of P for agriculture. Understanding phosphorite formation may improve management of P resources. However, the processes that mediate calcium phosphate mineral precipitation in certain marine pore waters remain poorly understood. Phosphogenesis occurs in sediments beneath some oceanic upwelling zones that harbor polyphosphate-accumulating giant sulfur bacteria (GSB). These bacteria may concentrate phosphate in sediment pore waters - creating supersaturated conditions with respect to apatite. However, the relationship between microbes and phosphogenesis is not fully resolved. To further study this relationship, we examined microbial communities from two sources: sediment cores recovered from the shelf of the Benguela region, and DNA extracted from washed phosphorites recovered from those same sediments. We used itag and clone library sequencing of the 16S rRNA gene to examine the microbial communities and their relationship with the environment. We found that many of our sediments shared large numbers of phylotypes with one another, and that the same metabolic guilds were represented at localities across the shelf. Sulfur-reducing bacteria and sulfur-oxidizing bacteria were abundant in our datasets. Phylotypes that are known to carry out nitrification and/or anammox (anaerobic ammonia oxidation) were also well-represented. Our phosphorite extraction, however, contained a distinct microbial community from those observed in the modern sediments. We observed both an enrichment of certain common microbial classes and a complete absence of others. These results could represent an ancient microbial assemblage that was present when the apatite precipitated. While these taxa may or may not have contributed to apatite precipitation, several groups represented in the phosphorite dataset have the genetic potential, as determined through the analysis of published genomes, to synthesize, and perhaps accumulate, polyphosphate.

Spatial variation and sources of polycyclic aromatic hydrocarbons influenced by intensive land use in an urbanized river network of East China.

PubMed

Bi, Chunjuan; Wang, Xueping; Jia, Jinpu; Chen, Zhenlou

2018-06-15

The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) in urbanized river networks are strongly influenced by intensive land use, industrial activities and population density. The spatial variations and their influencing factors of 16 priority PAHs were investigated in surface water, suspended particulate matter (SPM) and sediments among areas under different intensive land uses (industrial areas, agricultural areas, inner city, suburban towns and island areas) in the Shanghai river network, East China. Source apportionment was carried out using isomer ratios of PAHs and Positive Matrix Factorization (PMF). Total concentrations of 16 PAHs ranged from 105.2 to 400.5 ng/L, 108.1 to 1058.8 ng/L and 104.4 to 19,480.0 ng/g in water, SPM and sediments, respectively. The concentrations of PAHs in SPM and sediments varied significantly among areas (p < 0.05), with the highest concentrations in inner city characterized by highly intensive land use and high population density. The PAH concentrations in sediments were positively correlated with those in SPM and were more strongly correlated with black carbon than with total organic carbon, indicating a stronger influence of prolonged anthropogenic contamination than the recent surface input in sediments. Biomass and coal combustion contributed strongly to total PAHs, followed by natural gas combustion in water and SPM, and vehicular emissions in sediments. Vehicular emissions were the strongest contributors in SPM and sediments of the inner city, indicating the strong influence of vehicular transportation to PAHs pollution in the urbanized river network. Copyright © 2018 Elsevier B.V. All rights reserved.

Spatial distribution of polycyclic aromatic hydrocarbon and polychlorinated biphenyl sources in the Nakdong River Estuary, South Korea.

PubMed

Lee, Jun H; Woo, Han J; Jeong, Kap S; Kang, Jeong W; Choi, Jae U; Jeong, Eun J; Park, Kap S; Lee, Dong H

2017-10-15

Our research team investigated the elemental composition and the presence of various toxic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), in estuary surface sediments to trace the spatial distribution of the sources of pollution deposited in Nakdong River, Busan, South Korea. The spatial patterns of elemental composition and toxic organic compounds were determined from the measurements of total organic carbon (TOC), total nitrogen, total sulfur, PAHs, and PCBs. The sediments had TOC contents of between 0.02 and 1.80 wt% (avg. 0.34 wt%), depending on the amount of clay-sized particles. The concentrations of PAHs and PCBs (10.8-167.7 ng g -1 dry wt and 197.0-754.0 pg g -1 dry wt, respectively) in surface sediments revealed different spatial patterns for these compounds, suggesting that they partially originated from the combustion of fossil fuels and from the use of commercial PCB products at adjacent industrial complexes. Although these concentrations were far below the Sediment Quality Guideline (SQG) of the National Oceanic and Atmospheric Administration (NOAA), the sediments at one site contained PCBs at concentrations close to the response level (754.0 pg g -1 dry wt), and were dominated by low-molecular-weight PAHs. The PAHs and PCBs in Nakdong River Estuary sediments were likely to have originated from the combustion of fossil fuels and biomass at the adjacent industrial complexes. The primarily analyzed results determined that PAHs originated from the combustion of fossil fuels and biomass, and overall concentrations were related to the contributions of individual PAHs in most sediment samples. Based on the SQG of the NOAA, our results indicate that the anthropogenic activity should be considered on the future-sustainable management of this estuary system.

Linear alkylbenzenes as tracers of sewage-sludge-derived inputs of organic matter, PCBs, and PAHs to sediments at the 106-mile deep water disposal site

USGS Publications Warehouse

Lamoureux, E.M.; Brownawell, Bruce J.; Bothner, Michael H.

1996-01-01

Linear alkylbenzenes (LABs) are sensitive source-specific tracers of sewage inputs to the marine environment. Because they are highly particle reactive and nonspecifically sorbed to organic matter, LABs are potential tracers of the transport of both sludge-derived organic matter and other low solubility hydrophobic contaminants (e.g., PCBs and PAHs); sediment trap studies at the 106-Mile Site have shown LABs to be valuable in testing models of sludge deposition to the sea floor. In this study we report on the distributions of LABs, PCBs, PAHs, and Ag in surface sediments collected within a month of the complete cessation of dumping (July, 1992) in the vicinity of the dump site. Total LAB concentrations were lower than those measured by Takada and coworkers in samples from nearby sites collected in 1989. LABs from both studies appear to be significantly depleted (6 to 25-fold) in surface sediments relative to excess Ag (another sludge tracer) when compared to sewage sludge and sediment trap compositions. Comparison of LAB sediment inventories to model predictions of sludge particle fluxes supports the contention that LABs have been lost from the bed. The use of LABs to examine the short-or long-term fate of sludge derived materials in deep-sea sediments should be questioned. The causes of this LAB depletion are unclear at this point, and we discuss several hypotheses. The concentrations of total PCBs and PAHs are both correlated with sludge tracers, suggesting that there may be a measurable contribution of sludge-derived inputs on top of other nonpoint sources of these contaminant classes. This possibility is consistent with the composition of these contaminants determined in recent and historical analyses of sewage sludge.

Recent (1995-1998) Canadian research on contemporary processes of river erosion and sedimentation, and river mechanics

NASA Astrophysics Data System (ADS)

Ashmore, P.; Conly, F. M.; Deboer, D.; Martin, Y.; Petticrew, E.; Roy, A.

2000-06-01

Canadian research on contemporary erosion and sedimentation processes covers a wide range of scales, processes, approaches and environmental problems. This review of recent research focuses on the themes of sediment yield, land-use impact, fine-sediment transport, bed material transport and river morphology and numerical modelling of fluvial landscape development.Research on sediment yield and denudation has confirmed that Canadian rivers are often dominated by riparian sediment sources. Studies of the effects of forestry on erosion, in-stream sedimentation and habitat are prominent, including major field experimental studies in coastal and central British Columbia. Studies of fine-sediment transport mechanisms have focused on the composition of particles and the dynamics of flocculation. In fluvial dynamics there have been important contributions to problems of turbulence-scale flow structure and entrainment processes, and the characteristics of bedload transport in gravel-bed rivers. Although much of the work has been empirical and field-based, results of numerical modelling of denudational processes and landscape development also have begun to appear.The nature of research in Canada is driven by the progress of the science internationally, but also by the nature of the Canadian landscape, its history and resource exploitation. Yet knowledge of Canadian rivers is still limited, and problems of, for example, large pristine rivers or rivers in cold climates, remain unexplored. Research on larger scale issues of sediment transfer or the effects of hydrological change is now hampered by reductions in national monitoring programmes. This also will make it difficult to test theory and assess modelling results. Monitoring has been replaced by project- and issues-based research, which has yielded some valuable information on river system processes and opened opportunities for fluvial scientists. However, future contributions will depend on our ability to continue with fundamental fluvial science while fulfilling the management agenda.

Holocene and late glacial palaeoceanography and palaeolimnology of the Black Sea: Changing sediment provenance and basin hydrography over the past 20,000 years

USGS Publications Warehouse

Piper, David Z.; Calvert, S.E.

2011-01-01

The elemental geochemistry of Late Pleistocene and Holocene sediments of the Black Sea, recovered in box cores from the basin margins and a 5-m gravity core from the central abyssal region of the basin, identifies two terrigenous sediment sources over the last 20 kyrs. One source region includes Anatolia and the southern Caucasus; the second region is the area drained by rivers entering the Black Sea from Eastern Europe. Alkali metal:Al and heavy:light rare-earth element ratios reveal that the relative contribution of the two sources shifted abruptly every few thousand years during the late glacial and early Holocene lacustrine phase of the basin. The shifts in source were coeval with changes in the lake level as determined from the distribution of quartz and the heavy mineral-hosted trace elements Ti and Zr.The geochemistry of the abyssal sediments further recorded a sequence of changes to the geochemistry of the water column following the lacustrine phase, when high salinity Mediterranean water entered the basin beginning 9.3 kyrs BP. Bottom water that had been oxic throughout the lake phase became anoxic at approximately 8.4 kyrs BP, as recorded by the accumulation from the water column of several redox-sensitive trace metals (Mo, Re, U). The accumulation of organic carbon and several trace nutrients (Cd, Cu, Ni, Zn) increased sharply ca. 0.4 kyrs later, at 8.0 kyrs BP, reflecting an increase of primary productivity. Its increase was coeval with a shift in the dinoflagellate ecology from stenohaline to euryhaline assemblages. During this profound environmental change from the lacustrine to the marine phase, the accumulation rate of the lithogenous sediment fraction decreased as much as 10-fold in response to the rise of the water level in the basin from a low stand ca. 9.3 ka to its current level.

Holocene and late glacial palaeoceanography and palaeolimnology of the Black Sea: Changing sediment provenance and basin hydrography over the past 20,000 years

USGS Publications Warehouse

Piper, D.Z.; Calvert, S.E.

2011-01-01

The elemental geochemistry of Late Pleistocene and Holocene sediments of the Black Sea, recovered in box cores from the basin margins and a 5-m gravity core from the central abyssal region of the basin, identifies two terrigenous sediment sources over the last 20. kyrs. One source region includes Anatolia and the southern Caucasus; the second region is the area drained by rivers entering the Black Sea from Eastern Europe. Alkali metal:Al and heavy:light rare-earth element ratios reveal that the relative contribution of the two sources shifted abruptly every few thousand years during the late glacial and early Holocene lacustrine phase of the basin. The shifts in source were coeval with changes in the lake level as determined from the distribution of quartz and the heavy mineral-hosted trace elements Ti and Zr. The geochemistry of the abyssal sediments further recorded a sequence of changes to the geochemistry of the water column following the lacustrine phase, when high salinity Mediterranean water entered the basin beginning 9.3. kyrs BP. Bottom water that had been oxic throughout the lake phase became anoxic at approximately 8.4. kyrs BP, as recorded by the accumulation from the water column of several redox-sensitive trace metals (Mo, Re, U). The accumulation of organic carbon and several trace nutrients (Cd, Cu, Ni, Zn) increased sharply ca. 0.4. kyrs later, at 8.0. kyrs BP, reflecting an increase of primary productivity. Its increase was coeval with a shift in the dinoflagellate ecology from stenohaline to euryhaline assemblages. During this profound environmental change from the lacustrine to the marine phase, the accumulation rate of the lithogenous sediment fraction decreased as much as 10-fold in response to the rise of the water level in the basin from a low stand ca. 9.3. ka to its current level.

Distributions and potential sources of polycyclic aromatic hydrocarbons in surface sediments from an emerging industrial city (Xinxiang).

PubMed

Feng, Jinglan; Xi, Nannan; Zhang, Fei; Zhao, Jiahui; Hu, Pengtuan; Sun, Jianhui

2016-01-01

To investigate the distributions, degree, and possible sources of polycyclic aromatic hydrocarbons (PAHs) in bed sediments from four rivers of Xinxiang, 18 sediment samples were analyzed. The concentrations ranged from 4.45 × 10(3) to 29.0 × 10(3) ng/g for ∑15PAHs (sum of US Environmental Protection Agency (EPA) priority PAHs apart from naphthalene (Nap)) and 3.37 × 10(3) to 23.5 × 10(3) ng/g for ∑7carPAHs (including benzo[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DBA), and indeno[1,2,3-cd]pyrene (InP)) with average concentrations of 10.7 × 10(3) and 7.99 × 10(3) ng/g, respectively. Compared with those from other rivers in China, sediments from four rivers of Xinxiang were severely polluted with PAHs. Pearson correlation analysis showed that ∑15PAHs concentrations had a significant positive correlation with black carbon content. Four- to six-ring PAHs accounted for 83.4 % of total PAHs, which indicated that the main source of PAHs in the studied area could be pyrogenic contamination. Source apportionment using PCA/MLR and UNMIX revealed that coal and biomass combustion contributed 64.4-67.1 %, gasoline vehicle 23.2-27.2 %, and diesel vehicle 5.70-12.4 % of the total PAHs, respectively. The effects range low/effects range median (ERL/ERM) values showed that there was a high level of toxicity risk for BaA. The ecological risk assessment by mean effects range median quotients (mERMQ) revealed a medium ecological risk of ∑15PAHs in sediments from four rivers of Xinxiang, manifesting that a close attention should be paid to pollution of PAHs in the studied area.

Sources of polycyclic aromatic hydrocarbons in sediments of the Bharalu River, a tributary of the River Brahmaputra in Guwahati, India.

PubMed

Hussain, Karishma; Balachandran, S; Rafiqul Hoque, Raza

2015-12-01

Analysis of riverine sediments offers important information regarding anthropogenic activities in the adjacent watershed. In this study, we provide polycyclic aromatic hydrocarbon (PAH) levels, their possible sources and potential hazards in the Bharalu tributary of the Brahmaputra River flowing through Guwahati city in India. The USEPA's 16 priority PAHs were determined in river bank sediments during two distinct seasons viz. pre- and post-monsoon. The ∑PAHs concentrations varied between 338 and 23,100 ng g(-1) during post-monsoon and between 609 and 8620 ng g(-1) during pre-monsoon. Mean benzo(a)pyrene (BaP) levels were between 17.8 ± 12 and 21.9 ± 27 ng g(-1) during post- and pre-monsoon seasons respectively. Spatial variations were observed. Interestingly, bank sediment samples from the sites near the confluence of the Bharalu River with the Brahmaputra River were found to have maximum concentrations of PAHs during post-monsoon season. The profile of the PAHs was dominated by 3-, 4- and 6-ring compounds. We estimated hazards of PAHs as RQ∑PAHs, which showed seasonal variation: 3 times higher during post-monsoon than pre-monsoon. 3-and 4-ring PAHs were the major PAHs of concern. The Bharalu River sediment was found to pose medium to high hazards to ecosystem. The individual PAHs including Acy, Phen and Pyr were observed with RQ(MPCs) value >1 indicating severe hazards during post-monsoon and pre-monsoon season. A very high percentage of coefficient of variation (CV) for PAHs during post-monsoon also revealed great variation in hazards and sources in this season. The diagnostic ratios indicated both petrogenic and pyrogenic origin of the PAHs. The pyrogenic contributions were mainly attributed to emissions from diesel, gasoline and wood combustion which are mainly from anthropogenic sources. Copyright © 2015 Elsevier Inc. All rights reserved.

Parameterization of a complex landscape for a sediment routing model of the Le Sueur River, southern Minnesota

NASA Astrophysics Data System (ADS)

Belmont, P.; Viparelli, E.; Parker, G.; Lauer, W.; Jennings, C.; Gran, K.; Wilcock, P.; Melesse, A.

2008-12-01

Modeling sediment fluxes and pathways in complex landscapes is limited by our inability to accurately measure and integrate heterogeneous, spatially distributed sources into a single coherent, predictive geomorphic transport law. In this study, we partition the complex landscape of the Le Sueur River watershed into five distributed primary source types, bluffs (including strath terrace caps), ravines, streambanks, tributaries, and flat,agriculture-dominated uplands. The sediment contribution of each source is quantified independently and parameterized for use in a sand and mud routing model. Rigorous modeling of the evolution of this landscape and sediment flux from each source type requires consideration of substrate characteristics, heterogeneity, and spatial connectivity. The subsurface architecture of the Le Sueur drainage basin is defined by a layer cake sequence of fine-grained tills, interbedded with fluvioglacial sands. Nearly instantaneous baselevel fall of 65 m occurred at 11.5 ka, as a result of the catastrophic draining of glacial Lake Agassiz through the Minnesota River, to which the Le Sueur is a tributary. The major knickpoint that was generated from that event has propagated 40 km into the Le Sueur network, initiating an incised river valley with tall, retreating bluffs and actively incising ravines. Loading estimates constrained by river gaging records that bound the knick zone indicate that bluffs connected to the river are retreating at an average rate of less than 2 cm per year and ravines are incising at an average rate of less than 0.8 mm per year, consistent with the Holocene average incision rate on the main stem of the river of less than 0.6 mm per year. Ongoing work with cosmogenic nuclide sediment tracers, ground-based LiDAR, historic aerial photos, and field mapping will be combined to represent the diversity of erosional environments and processes in a single coherent routing model.

Characterizing the impacts of the 2006 New Year's flood in the Laguna de Santa Rosa floodplain, Sonoma County, CA

NASA Astrophysics Data System (ADS)

Flint, L. E.; Curtis, J. A.; Flint, A. L.

2006-12-01

The Laguna de Santa Rosa (Laguna), the largest tributary to the Russian River located in Sonoma County, California, occupies a relatively flat low-lying area west of the Santa Rosa Plain. From December 12, 2005 to January 6, 2006 the Laguna experienced heavy flooding, with peak flows on New Year's Day of over 185 m3/s, at a location that experiences median flows of less than 14 m3/s. The objectives of this study were to (1) analyze precipitation intensities and amounts for the region to establish the conditions under which flooding occurred, (2) measure and map inundation areas and floodplain sediment deposition, and (3) compare field data with a GIS sediment deposition potential map. Spatial variations in intensities and total volumes of precipitation correlate well with evidence of local flooding throughout the region, particularly in the mountains to the east and southeast of Santa Rosa. Total precipitation for the month of December was 200 percent of normal, and maximum hourly intensities reached 20 mm/hour during the storm. High water marks and floodplain deposition sites were mapped using kinematic GPS surveying with post-processed differential correction, and sediment deposition was measured. The surveyed data were superimposed on an available two-foot-interval contour map to create an inundation map and a GIS point coverage of sediment deposition. Landscape attributes relevant to floodplain sedimentation were assessed and a sediment deposition potential map was created at the 30-m scale using a matrix of landscape characteristics that included: land use; roughness (influenced by vegetation type and density); channel and hillslope sediment sources (influenced by soils, geology, and cutbank erosion); slope and topography; and geomorphic terrain type. A calculation of sediment deposition potential was developed within a GIS that accounts for all contributing factors and illustrates that floodplain deposition is dominated by localized sedimentation, reflecting the importance of sediment point sources, rather than extensive sedimentation throughout the floodplain. The data collected in this study will be used to constrain model simulations of recurrence-interval floods and provide information on patterns of hydrology and sedimentation for extreme events that will help refine conceptual models of floodplain processes.

Impact of methane flow through deformable lake sediments on atmospheric release

NASA Astrophysics Data System (ADS)

Scandella, B.; Juanes, R.

2010-12-01

Methane is a potent greenhouse gas that is generated geothermally and biologically in lake and ocean sediments. Free gas bubbles may escape oxidative traps and contribute more to the atmospheric source than dissolved methane, but the details of the methane release depend on the interactions between the multiple fluid phases and the deformable porous medium. We present a model and supporting laboratory experiments of methane release through “breathing” dynamic flow conduits that open in response to drops in the hydrostatic load on lake sediments, which has been validated against a high-resolution record of free gas flux and hydrostatic pressure in Upper Mystic Lake, MA. In contrast to previous linear elastic fracture mechanics analysis of gassy sediments, the evolution of gas transport in a deformable compliant sediment is presented within the framework of multiphase poroplasticity. Experiments address how strongly the mode and rate of gas flow, captured by our model, impacts the size of bubbles released into the water column. A bubble's size in turn determines how efficiently it transports methane to the atmosphere, and integrating this effect will be critical to improving estimates of the atmospheric methane source from lakes. Cross-sectional schematic of lake sediments showing two venting sites: one open at left and one closed at right. The vertical release of gas bubbles (red) at the open venting site creates a local pressure drop, which drives both bubble formation from the methane-rich pore water (higher concentrations shaded darker red) and lateral advection of dissolved methane (purple arrows). Even as bubbles in the open site escape, those at the closed site remain trapped.

Priority substances in sediments of the "Carska Bara" special nature reserve, a natural scientific research area on the UNESCO list.

PubMed

Grba, Nenad; Krčmar, Dejan; Isakovski, Marijana Kragulj; Jazić, Jelena Molnar; Maletić, Snežana; Pešić, Vesna; Dalmacija, Božo

2016-11-01

Surface sediments were subject to systematic long-term monitoring (2002-2014) in the Republic of Serbia (Province of Vojvodina). Eight heavy metals (Ni, Zn, Cd, Cr, Cu, Pb, As and Hg), mineral oils (total petroleum hydrocarbons), 16 EPA PAHs, selected pesticides and polychlorinated biphenyls (PCB) were monitored. As part of this research, this paper presents a sediment contamination spatial and temporal trend study of diverse pollution sources and the ecological risk status of the alluvial sediments of Carska Bara at three representative sampling sites (S1S3), in order to establish the status of contamination and recommend substances of interest for more widespread future monitoring. Multivariate statistical methods including factor analysis of principal component analysis (PCA/FA), Pearson correlation and several synthetic indicators were used to evaluate the extent and origin of contamination (anthropogenic or natural, geogenic sources) and potential ecological risks. Hg, Cd, As, mineral oils and PAHs (dominated by dibenzo(a,h)anthracene and benzo(a)pyrene, contributing 85.7% of the total) are derived from several anthropogenic sources, whereas Ni, Cu, Cr and Zn are convincingly of geogenic origin, and exhibit dual origins. Cd and Hg significantly raise the levels of potential ecological risk for all sampling locations, demonstrating the effect of long-term bioaccumulation and biomagnification. Pb is isolated from the other parameters, implying unique sources. This research suggests four heavy metals (Zn, Cr, Cu and As) and dibenzo(a,h)anthracene be added to the list of priority pollutants within the context of the application of the European Water Framework Directive (WFD), in accordance with significant national and similar environmental data from countries in the region. Copyright © 2016 Elsevier Ltd. All rights reserved.

Capturing sediment and nutrients in irrigated terraced landscapes

NASA Astrophysics Data System (ADS)

Slaets, Johanna; Schmitter, Petra; Hilger, Thomas; Piepho, Hans-Peter; Dercon, Gerd; Cadisch, Georg

2016-04-01

Terraces are often promoted as green filters in landscapes, buffering discharge and constituent peaks. For irrigated rice terraces, however, this mitigating potential has not been assessed at the landscape level. Additionally, sediment and nutrient inputs potentially affect soil fertility in agricultural terraces and therefore yield - the extent of the impact depending on the quality and quantity of the captured material. Quantifying such upland-lowland linkages is particularly important in intensely cultivated landscapes, as declining upland soil fertility could alter beneficial hydrological connectivity between terraces and surrounding landscapes. In this study, we therefore quantified the sediment, sediment-associated organic carbon and nitrogen inputs and losses for a 13 ha paddy rice area, surrounded by upland maize cultivation in Northwest Vietnam in 2010 and 2011. Turbidity sensors were used in combination with a linear mixed model in order to obtain continuous predictions of the constituent concentrations. Sediment texture was determined using mid-infrared spectroscopy. Uncertainty on annual load estimates was quantified by calculating 95% confidence intervals with a bootstrap approach. Sediment inputs from irrigation water to the rice area amounted to 48 Mg ha-1 a-1 and runoff during rainfall events contributed an additional 16 Mg ha-1 a-1. Export from the rice terraces equalled 63 Mg ha-1 a-1 of sediments, resulting in a net balance of 28 Mg ha-1 a-1 or a trapping of almost half of the annual sediment inputs. Runoff contributed one third of the sand inputs, while irrigated sediments were predominantly silty. As paddy outflow contained almost exclusively silt- and clay-sized material, 24 Mg ha-1 a-1 of captured sediments consisted of sand. The sediment-associated organic carbon resulted in a deposit of 1.09 Mg ha-1 a-1. For sediment-associated nitrogen, 0.68 Mg ha-1 a-1 was trapped in the terraces. Combining both sediment-associated and dissolved nitrogen, irrigation water provided a total input of 1.11 Mg ha-1 a-1, of which 54% was in the plant-available forms of ammonium and nitrate - an input larger than the recommended application of chemical fertilizer. Rice terraces were net traps for sediment and protected downstream areas by filtering coarse sediments. Combined with the importance of irrigation water as a source of organic carbon and nitrogen for the rice, this connectivity underscores the vulnerability of agricultural terraces to changes in surrounding land use.

ESR signals in quartz for the studies of earth surface processes

NASA Astrophysics Data System (ADS)

Toyoda, S.; Shimada, A., , Dr; Takada, M.

2017-12-01

Various ESR (electron spin resonance) signals are observed in quartz. As they are formed by natural radiation, the signals are useful in dating of geological events, such as volcanic eruption, faulting and sedimentation. It was also found that those paramagnetic defects can be fingerprints of sediments, to be used for studies in sediment provenance. The signal of the E1' center, unpaired electron at an oxygen vacancy, was first used for such studies. A method was proposed to estimate the number of the precursors (oxygen vacancies) from the E1' center intensity. The number of oxygen vacancies in quartz was found to have positive correlation with the crystallization age. Using this feature, studies were quite successful in aeolian dust. It was shown that the sources of aeolian dust deposited in northern part of Japanese Islands were different between in MIS1 and MIS 2. In combination with crystallinity index, the contributions of the dust components from three origins were quantitatively obtained. After these, the provenance studies on river sediments have started where the impurity centers in quartz were employed, which are the Al center, the Ti centers, and the Ge centers. Sediments of Kizu River, Mie to Nara prefectures in Central Japan are most extensively studied. Firstly, it was shown that each of possible sources of granitic quartz around the reaches has respective characteristics in the number of oxygen vacancies and the signal intensities of impurity centers. Secondary, by the artificial mixing experiments, the impurity signal intensities have the values consistent with the mixing ratio of the two samples of quartz with different intensities. At river junctions, the mixing ratios were calculated from the ESR signals. At some locations, the mixing ratio values obtained from one signal were consistent with the ones from another signal while at some locations they were not. The latter inconsistent results would indicate that the river sediments are inhomogeneous and complicated. Several results will be presented showing the source to sink changes in the ESR signal intensities along with the river. The signals are basically consistent with the possible sources in the river beds having the variation due to the inflow of the tributaries.

An assessment of injury to sediments and sediment-dwelling organisms in the Grand Calumet River and Indiana Harbor Area of Concern, USA.

PubMed

MacDonald, D D; Ingersoll, C G; Smorong, D E; Lindskoog, R A; Sparks, D W; Smith, J R; Simon, T P; Hanacek, M A

2002-08-01

This article is the first in a series of three that describe the results of a Natural Resource Damage Assessment (NRDA) conducted in the Grand Calumet River and Indiana Harbor Area of Concern (IHAOC). The assessment area is located in northwest Indiana and was divided into nine reaches to facilitate the assessment. This component of the NRDA was undertaken to determine if sediments and sediment-dwelling organisms have been injured due to exposure to contaminants that have accumulated in sediments as a result of discharges of oil or releases of other hazardous substances from industrial, municipal, and nonpoint sources. To support this assessment, information was compiled on the chemical composition of sediment and pore water; on the toxicity of whole sediments, pore water, and elutriates; and on the status of benthic invertebrate communities. The data on each of these indicators were compared to regionally relevant benchmarks to assess the presence and extent of injury to surface water resources ( i.e., sediments) or biological resources ( i.e., sediment-dwelling organisms). The results of this assessment indicate that sediment injury has occurred throughout the assessment area, with up to four distinct lines of evidence demonstrating injury within the various reaches. The primary contaminants of concern ( i.e., those substances that are present at concentrations that are sufficient to cause or substantially contribute to sediment injury) include metals, polycyclic aromatic hydrocarbons, and total polychlorinated biphenyls.

A Manual to Identify Sources of Fluvial Sediment

EPA Science Inventory

Sedimentation is one of the main causes of stream/river aquatic life use impairments in R3. Currently states lack standard guidance on appropriate tools available to quantify sediment sources and develop sediment budgets in TMDL Development. Methods for distinguishing sediment t...

Carbonate Formation And Diagenesis In Pastos Grandes Laguna (Bolivia): Modern Analog For The South Atlantic Cretaceous Presalt Travertinoid Deposits

NASA Astrophysics Data System (ADS)

Muller, E.; Ader, M.; Gérard, E.; Virgone, A.; Gaucher, E.; Bougeault, C.; Durlet, C.; Moreira, M. A.; Virgile, R.; Vennin, E.; Agogué, H.; Hugoni, M.

2017-12-01

The Cretaceous Presalt travertinoid deposits of the South Atlantic are usually considered as "strange deposits" having poor equivalents in modern environments. Pastos Grandes Laguna, which is located in a 2.9 Ma caldera on the andean-bolivian Altiplano (at 4450 m), is intersected by active faults with hydrothermal fluids and presents a spherulitic plateform with similar sedimentological facies to the Presalt: halite and bedded evaporites, shrub-shaped calcites, ooids, pisolites and various stromatolites. Pastos Grandes Laguna is certainly one of the best modern analog of the Presalt for investigating the on going processes of carbonate deposition and diagenesis and the influence of biology. During two expeditions, we recovered samples of gas, water and microbial mats from the hydrothermal sources to the evaporating zones on the spherulitic plateform. These samples are being analyzed to determine 1) the influence of the gases emitted at the hydrothermal sources (chemical and isotopic composition) on the chemistry of the Laguna and the mineralogy of its sediments and 2) the role of ecosystems that develop in this environment on carbonate formation. Preliminary results on gas composition, corrected for the atmospheric contribution, indicates a magmatic source of CO2 partly mantellic associated with a small crustal contribution. Other initial results have so far indicated that CO2 gas emissions, evaporation, as well as photosynthesis and respiration play a role on water chemistry and carbonate precipitation. This study will contribute to the overall understanding of the role of organisms in sedimentation and the predictive diagenetic evolution of hydrothermal and lacustrine deposits.

An Ocean Basin of Dirt? Using Molecular Biomarkers and Radiocarbon to Identify Organic Carbon Sources and their Preservation in the Arctic Ocean

NASA Astrophysics Data System (ADS)

Harvey, H.; Belicka, L. L.

2005-12-01

In the modern Arctic Ocean, primary production in waters over the broad continental shelves and under ice contributes an estimated 250 Mt/yr of POC to Arctic waters. The delivery of terrestrial material from large rivers, ice transport and through coastal erosion adds at least an additional 12 Mt/yr of POC. Although the marine organic carbon signal in Arctic Ocean exceeds that of terrestrial carbon by an order or magnitude or more, recent evidence suggests that this balance is not maintained and significant fractions of terrestrial carbon is preserved in sediments. Using an integrated approach combining lipid biomarkers and radiocarbon dating in particles and sediments, the process of organic carbon recycling and historical changes in its sources and preservation has been examined. A suite of lipid biomarkers in particles and sediments of western Arctic shelves and basins were measured and principle components analysis (PCA) used to allow a robust comparison among the 120+ individual compounds to assign organic sources and relative inputs. Offshore particles from the chlorophyll maximum contained abundant algal markers (e.g. 20:5 and 22:6 FAMEs), low concentrations of terrestrial markers (amyrins and 24-ethylcholest-5-en-3b-ol), and reflected modern 14C values. Particles present in deeper halocline waters also reflect marine production, but a portion of older, terrestrial carbon accompanies the sinking of the spring bloom. Surface and deeper sediments of basins contain older organic carbon and low concentrations of algal biomarkers, suggesting that marine carbon produced in surface waters is rapidly recycled. Taken together, these observations suggest that marine derived organic matter produced in shallow waters fuels carbon cycling, but relatively small amounts are preserved in sediments. As a result, the organic carbon preserved in sediments contrasts sharply to that typically observed in lower latitudes, with an increasing terrestrial signature with distance from land and potential for significant changes under a changing climate.

Sources and fate of sediment organic matter in Asia's largest brackish water lagoon and nearby mangrove ecosystem

NASA Astrophysics Data System (ADS)

Mukherjee, R.; Muduli, P. R.; Barik, S.; Kumar, S.

2017-12-01

Coastal lagoons and mangrove ecosystems regularly undergo natural (tidal) and anthropogenic (riverine inputs) forcings. After effects of these forcings cause coastal environments to sustain high biological production leading to high suspended organic matter (OM) and hence fast sedimentation and accumulation of OM in sediments.The different sources of OM and its burial in tropical lacustrine and mangrove systems have been rarely studied in detail with a few reports from Indian estuaries. The present study attempts to understand the sources and fate organic matter at two Ramsar sites, viz. Chilika Lake (Asia's largest brackish water lagoon) and nearby Bhitarkanika mangroves, located in the east coast of India. We measured nitrogen and carbon content (% N and % C) and isotopic composition (δ13Corg and δ15N) of OM at different depths in eight and three sediment cores collected from the Chilika lagoon and Bhitarkanika mangroves, respectively. Overall, the mean δ13Corg and % C in the lagoon were ‒21.10 ± 0.79 ‰ and 0.84 ± 0.47 %, respectively; whereas the same for mangrove cores were ‒24.56 ± 0.80 ‰ and 1.04 ± 0.26 %, respectively. Similarly, average δ15N and % N in the lagoon cores were 4.15 ± 0.63 ‰ and 0.11 ± 0.05 %, respectively; for mangrove cores the values were 4.28 ± 0.50 ‰ and 0.07 ± 0.01 %, respectively. Preliminary analysis of the isotopic composition (δ13Corg and δ15N) and elemental ratios indicates that organic carbon in the sediment at Bhitarkanika mangrove was of terrigenous, marine and in situ origin, whereas cores of Chilika lagoon showed predominantly marine signature. No relationship between δ13Corg of suspended and sediment in the Chilika lagoon indicates these two organic pools to be not directly coupled. End member mixing model in the mangrove ecosystem indicate on an average 50 % terrestrial contribution to the OM pool.

Terrestrial organic matter in surface sediments of the Baltic Sea, Northwest Europe, as determined by CuO oxidation

NASA Astrophysics Data System (ADS)

Miltner, Anja; Emeis, Kay-Christian

2001-04-01

We studied the distribution and composition of terrestrial organic matter in sediments of the Baltic Sea (Northwest Europe). To this end, surface sediments from all basins of the Baltic Sea were analyzed for their lignin oxidation product yields and compositions after CuO oxidation. Lignin oxidation product yields depend on the concentration of organic carbon and range from 0.4 to 10.2 mg g -1 total organic carbon (TOC). On the basis of an average of 13 mg g -1 TOC in two river sediments, we estimate that the upper limit of terrestrial organic matter in Baltic Sea sediments is 30% of TOC. The contribution of terrestrial organic matter differed between the individual basins, depending on the distance from runoff discharge areas and on the area occupied by each submarine catchment. Lignin composition showed a relative decrease of angiosperm tissue from the Southwest to the Northeast, reflecting the shift from temperate to boreal vegetation type. The Gotland and the Bornholm Seas, which have no significant river input, were characterized by high relative contributions of nonwoody, strongly altered material. The source may either be a mixture of pollen and peat being eroded from geologically older strata at the seafloor or laterally advected material from the other basins. However, the pronounced compositional differences between the basins indicated that interbasin transport of terrestrial organic matter is less important than direct river input, although river signals can only be traced at a few places in the Baltic Sea.

Concentrations, and estimated loads and yields of nutrients and suspended sediment in the Little River basin, Kentucky, 2003-04

USGS Publications Warehouse

Crain, Angela S.

2006-01-01

Nutrients, primarily nitrogen and phosphorus compounds, naturally occur but also are applied to land in the form of commercial fertilizers and livestock waste to enhance plant growth. Concentrations, estimated loads and yields, and sources of nitrite plus nitrate, total phosphorus, and orthophosphate were evaluated in streams of the Little River Basin to assist the Commonwealth of Kentucky in developing 'total maximum daily loads' (TMDLs) for streams in the basin. The Little River Basin encompasses about 600 square miles in Christian and Trigg Counties, and a portion of Caldwell County in western Kentucky. Water samples were collected in streams in the Little River Basin during 2003-04 as part of a study conducted in cooperation with the Kentucky Department of Agriculture. A total of 92 water samples were collected at four fixed-network sites from March through November 2003 and from February through November 2004. An additional 20 samples were collected at five synoptic-network sites during the same period. Median concentrations of nitrogen, phosphorus, and suspended sediment varied spatially and seasonally. Concentrations of nitrogen were higher in the spring (March-May) after fertilizer application and runoff. The highest concentration of nitrite plus nitrate-5.7 milligrams per liter (mg/L)-was detected at the South Fork Little River site. The Sinking Fork near Cadiz site had the highest median concentration of nitrite plus nitrate (4.6 mg/L). The North Fork Little River site and the Little River near Cadiz site had higher concentrations of orthophosphate in the fall and lower concentrations in the spring. Concentrations of orthophosphate remained high during the summer (June-August) at the North Fork Little River site possibly because of the contribution of wastewater effluent to streamflow. Fifty-eight percent of the concentrations of total phosphorus at the nine sites exceeded the U.S. Environmental Protection Agency recommended maximum concentration limit of 0.1 mg/L. Concentrations of suspended sediment were highest in the spring during runoff and lowest in the fall. The highest concentration of suspended sediment (1,020 mg/L) was observed at the Sinking Fork near Cadiz site. The median concentration of suspended sediment for all sites sampled was 12 mg/L. A nonparameteric statistical test (Wilcoxson rank-sum) showed that the median concentrations of suspended sediment were not different among any of the fixed-network sites. The Little River near Cadiz site contributed larger estimated mean annual loads of nitrite plus nitrate (2,500,000 pounds per year (lb/yr)) and total phosphorus (160,000 lb/yr) than the other three fixed-network sites. Of the two main upstream tributaries from the Little River near Cadiz site, the North Fork Little River was the greatest contributor of total phosphorus to the study area with an estimated mean annual load of 107,000 lb/yr or about 64 percent of the total estimated mean annual load at the Little River near Cadiz site. The other main upstream tributary, South Fork Little River, had an estimated mean annual load of total phosphorus that was about 20 percent of the mean annual load at the Little River near Cadiz site. Estimated loads of suspended sediment were largest at the Little River near Cadiz site, where the estimated mean annual load for 2003-04 was about 84,000,000 lb/yr. The North Fork Little River contributed an estimated 36 percent of the mean annual load of suspended sediment at the Little River near Cadiz site, while the South Fork Little River contributed an estimated 18 percent of the mean annual load at the Little River near Cadiz site. The North Fork Little River site had the largest estimated mean annual yield of total phosphorus (1,600 pounds per year per square mile (lb/yr/mi2)) and orthophosphate (1,100 lb/yr/mi2). A principal source of phosphorus for the North Fork Little River is discharge from wastewater-treatment facilities. The largest estimated mean annual yield of nitrite plus nitrate was observed at the South Fork Little River site. The North Fork Little River site had the largest estimated mean annual yield of suspended sediment (450,000 lb/yr/mi2). Inputs of nitrogen and phosphorus to streams from point and nonpoint sources were estimated for the Little River Basin. Commercial fertilizer and livestock-waste applications on row crops are a principal source of nutrients for most of the Little River Basin. Sources of nutrients in the urban areas of the basin mainly are from effluent discharge from wastewater-treatment facilities and fertilizer applications to lawns and golf courses.

Interpreting stream sediment fingerprints against primary and secondary source signatures in agricultural catchments

NASA Astrophysics Data System (ADS)

Blake, Will H.; Haley, Steve; Smith, Hugh G.; Taylor, Alex; Goddard, Rupert; Lewin, Sean; Fraser, David

2013-04-01

Many sediment fingerprinting studies adopt a black box approach to source apportionment whereby the properties of downstream sediment are compared quantitatively to the geochemical fingerprints of potential catchment sources without consideration of potential signature development or modification during transit. Working within a source-pathway-receptor framework, this study aimed to undertake sediment source apportionment within 6 subcatchments of an agricultural river basin with specific attention to the potential role of contaminants (vehicle emissions and mine waste) in development of stream sediment signatures. Fallout radionuclide (FRN) and geochemical fingerprinting methods were adopted independently to establish source signatures for primary sediment sources of surface and subsurface soil materials under various land uses plus reworked mine and 'secondary' soil material deposited, in transit, along road networks. FRN data demonstrated expected variability between surface soil (137Cs = 14 ± 3 Bq kg-1; 210Pbxs = 40 ± 7 Bq kg-1) and channel bank materials (137Cs = 3 ± 1 Bq kg-1; 210Pbxs = 24 ± 5 Bq kg-1) but road transported soil material was considerably elevated in 210Pbxs (up to 673 ± 51 Bq kg-1) due to sediment interaction with pluvial surface water within the road network. Geochemical discrimination between surface and subsurface soil materials was dominated by alkaline earth and alkali metals e.g. Ba, Rb, Ca, K, Mg which are sensitive to weathering processes in soil. Magnetic susceptibility and heavy metals were important discriminators of road transported material which demonstrated transformation of the signatures of material transported via the road network. Numerical unmixing of stream sediment indicated that alongside channel bank erosion, road transported material was an important component in some systems in accord with FRN evidence. While mining spoil also ranked as a significant source in an affected catchment, perhaps related to legacy sediment, the potential role of dissolved metal leaching and subsequent sediment-water interaction within the channel on signature modification remained unclear. Consideration of sediment signature modification en route from primary source to stream elucidated important information regarding sediment transfer pathways and dynamics relevant to sediment management decisions. Further work on sediment-water interactions and potential for signature transformation in the channel environment is required.

Sediment dynamics and post-glacial evolution of the continental shelf around the Blanes submarine canyon head (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Durán, Ruth; Canals, Miquel; Lastras, Galderic; Micallef, Aaron; Amblas, David; Pedrosa-Pàmies, Rut; Sanz, José Luis

2013-11-01

The Blanes submarine canyon (BC) deeply incises the Catalan continental shelf in the NW Mediterranean Sea. As a consequence of the closeness (only 4 km) of its head to the coastline and the mouth of the Tordera River, the canyon has a direct influence on the shelf dispersal system as it collects large amounts of sediment, mainly during high-energy events. Multibeam bathymetry, backscatter imagery and very-high resolution seismic reflection profiles have allowed characterizing the morphology of the continental shelf around the canyon head, also identifying sediment sources and transport pathways into the canyon. The morphological data have also been used to reconstruct the evolution of the continental shelf during the last sea-level transgression so that the current understanding of shelf-to-canyon sediment exchanges through time could be improved. The continental shelf surrounding the BC consists of both depositional and erosional or non-depositional areas. Depositional areas display prominent sediment bodies, a generally smooth bathymetry and variable backscatter. These include: (i) an area of modern coarse-grained sediment accumulation that comprises the inner shelf; (ii) a modern fine-grained sedimentation area on the middle shelf offshore Tossa de Mar; and (iii) a modern sediment depleted area that covers most of the middle and outer shelf to the west of the canyon head. Erosional and non-depositional areas display a rough topography and high backscatter, and occur primarily to the east of the canyon head, where the arrival of river-fed inputs is very small. In agreement with this pattern, the continental shelf north and west of the canyon head likely is the main source of shelf sediment into the canyon. To the north, a pattern of very high backscatter extends from the coastline to the canyon head, suggesting the remobilization and off-shelf export of fines. Additionally, relict near-shore sand bodies developed over the Barcelona shelf that extend to the canyon head rim constitute a source of coarse sediment. High-energy processes, namely river floods and coastal storms, are the main controls over the river-shelf-canyon sediment exchange. River floods increase the delivery of terrigenous particles to the coastal system. Storms, mainly from the east, remobilize the sediment temporarily accumulated on the shelf towards the canyon head, so that the finer fractions are preferentially removed and a coarse lag is normally left on the shelf floor. Exceptionally, very strong storms also remove the coarse fractions from the shelf drive them into the canyon. Processes like dense shelf water cascading, which is much more intense in canyons to the north of BC, and the Northern Current also contribute to the transport of suspended sediment from far distant northern sources. During the last post-glacial transgression the BC had a strong influence on the evolution of the inner continental margin, as it interrupted the shelf sediment dispersal system by isolating the shelves to its north and south, named La Planassa and Barcelona shelves, respectively. The detailed study of the geomorphology and uppermost sediment cover of the continental shelf surrounding the Blanes submarine canyon yields insight into the past and present shelf sediment dynamics and the shelf-to-canyon sediment exchanges. The continental shelf near the canyon head consists of mosaic where erosional, or non-depositional, and depositional zones coexist. East of the canyon and offshore Tossa de Mar, the modern sediment deposition is mostly confined to the inner and middle shelf, whilst most of the La Planassa shelf is sediment depleted with numerous relict morphosedimentary features cropping out. Rocky outcrops, narrow ridges and relict coarse sand deposits suggesting erosion or non-deposition of fine sediments in modern times occupy the middle and outer shelf floor east and northeast of the canyon head. In contrast, north and west of the canyon head, the middle and outer shelf comprises several large relict sand bodies that point out to long-term deposition. However, the lack of modern sediments on top of these bodies supports active erosion or by-pass in present times. The morphology of the continental shelf near the canyon head records the imprint of the main factors controlling the shelf sediment-dispersal system and provides evidence for the main sources and transport pathways of sediment from the shelf into the canyon. The depletion of fine sediments on the continental shelf, as evidenced by backscatter data, suggests that the Blanes Canyon acts as a sediment trap collecting the finest fractions resuspended primarily from the adjacent shelf to the north. The main processes that control the shelf-to-canyon transfer of sediment are eastern storms, which enhance the off-shelf export of mainly fine sediment from the shelf. Particularly severe storms are also able to remobilize and transport coarse sediment from the shelf and also from the relict sand bodies into the canyon. Other processes, such as DSWC and the Northern Current, contribute to a lesser extent to the transport of sediment along the shelf and into the canyon. During the last post-glacial transgression, the BC played a crucial role in the shaping of the continental shelf surrounding it by cutting the littoral drift of sediment between the shelf areas to the north and south, thus severely modifying the across- and along-shelf sediment pathways. As a result, to the east of the canyon, the poor development of transgressive deposits indicates the prevalence of erosion and non-deposition associated to a limited sediment supply and an effective action of the littoral drift leading to a south-westward transport of sediment towards the canyon head. To the north and west of the canyon the morphology of the continental shelf changed significantly during the sea-level rise. At the early stage of the transgression, the sediment supplied by the Tordera River was discharged directly into the canyon, thus preventing deposition over the shelf. Later, the progressive sea-level rise favoured the development of large depositional bodies on the Barcelona shelf favoured by the increase of accommodation space and the augmenting distance between the river mouth and the canyon head. A drastic change in the configuration of the shelf occurred when the sea-level raised enough to flood the entire continental shelf. The along-shelf sediment transport between the shelf areas to the north and south of the canyon head was then restored and new sediment bodies were formed between the coastline and the canyon tip. At present, these sediment bodies constitute the primary source of coarse sediment into the BC. These results confirm that the Blanes submarine canyon head is highly dynamic and sensitive to a variety of processes that enhance the transport of sediment from the shelf into the canyon, particularly during major storms.

Hydrology and sediment budget of Los Laureles Canyon, Tijuana, MX: Modelling channel, gully, and rill erosion with 3D photo-reconstruction, CONCEPTS, and AnnAGNPS

NASA Astrophysics Data System (ADS)

Taniguchi, Kristine; Gudiño, Napoleon; Biggs, Trent; Castillo, Carlos; Langendoen, Eddy; Bingner, Ron; Taguas, Encarnación; Liden, Douglas; Yuan, Yongping

2015-04-01

Several watersheds cross the US-Mexico boundary, resulting in trans-boundary environmental problems. Erosion in Tijuana, Mexico, increases the rate of sediment deposition in the Tijuana Estuary in the United States, altering the structure and function of the ecosystem. The well-being of residents in Tijuana is compromised by damage to infrastructure and homes built adjacent to stream channels, gully formation in dirt roads, and deposition of trash. We aim to understand the dominant source of sediment contributing to the sediment budget of the watershed (channel, gully, or rill erosion), where the hotspots of erosion are located, and what the impact of future planned and unplanned land use changes and Best Management Practices (BMPs) will be on sediment and storm flow. We will be using a mix of field methods, including 3D photo-reconstruction of stream channels, with two models, CONCEPTS and AnnAGNPS to constrain estimates of the sediment budget and impacts of land use change. Our research provides an example of how 3D photo-reconstruction and Structure from Motion (SfM) can be used to model channel evolution.

Long-term fertilization alters the relative importance of nitrate reduction pathways in salt marsh sediments

NASA Astrophysics Data System (ADS)

Peng, Xuefeng; Ji, Qixing; Angell, John H.; Kearns, Patrick J.; Yang, Hannah J.; Bowen, Jennifer L.; Ward, Bess B.

2016-08-01

Salt marshes provide numerous valuable ecological services. In particular, nitrogen (N) removal in salt marsh sediments alleviates N loading to the coastal ocean. N removal reduces the threat of eutrophication caused by increased N inputs from anthropogenic sources. It is unclear, however, whether chronic nutrient overenrichment alters the capacity of salt marshes to remove anthropogenic N. To assess the effect of nutrient enrichment on N cycling in salt marsh sediments, we examined important N cycle pathways in experimental fertilization plots in a New England salt marsh. We determined rates of nitrification, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) using sediment slurry incubations with 15N labeled ammonium or nitrate tracers under oxic headspace (20% oxygen/80% helium). Nitrification and denitrification rates were more than tenfold higher in fertilized plots compared to control plots. By contrast, DNRA, which retains N in the system, was high in control plots but not detected in fertilized plots. The relative contribution of DNRA to total nitrate reduction largely depends on the carbon/nitrate ratio in the sediment. These results suggest that long-term fertilization shifts N cycling in salt marsh sediments from predominantly retention to removal.

Improvements in Quantifying Bank Erosion for Sediment Budgets within the Chesapeake Bay Watershed by Integrating Structure-From-Motion Photogrammetry

NASA Astrophysics Data System (ADS)

Bell, J. M.; Cashman, M. J.; Nibert, L.; Jackson, S.

2017-12-01

Fine sediment is a major source of pollution due to its ability to attenuate light, smother habitat, and sorb and transport nutrients, such as phosphorus and nitrogen. Piedmont streams in the Mid-Atlantic region of the United States are frequently characterized as incised with steep, highly erodible banks of legacy sediment that can contribute to high sediment loads. Multiple sediment fingerprinting studies in this region have demonstrated that stream banks can contribute a large proportion of the total sediment load, but stream banks are frequently overlooked in sediment delivery models and Total Maximum Daily Load allocations. The direct quantification of bank erosion is therefore essential to producing accurate sediment budgets, which are needed to inform the targeted mitigation and remediation of degraded fluvial systems. This study contrasts the use of traditional bank pin measurements, structure-from-motion photogrammetric techniques, and aerial LIDAR at sites within Maryland, USA. Bank pin measurements, representing only single points in space, were found to be highly variable with subjective initial placement often missing nearby, large-scale bank failures. In contrast, photogrammetric techniques, using structure-from-motion, were able to capture a more spatially-complete streambank profile. Using a Nikon D810 camera, bank scans were able to reconstruct banks with a RMSE as low as 0.1mm and repeat scan alignment resolution of <2mm. However, during summer months, photogrammetry exhibited some coverage gaps in areas of high vegetation density. Difference-maps rendered from multiple UAV structure-from-motion scans provided an ability to rapidly assess changes to river channel morphology during leaf-off conditions. Additionally, UAV-derived scans were georeferenced over historical LIDAR data to evaluate historical bank-erosion over multi-year timescales. Future work will include difference mapping channel features at watershed scales. This photogrammetric approach of quantifying geomorphic change, when coupled with bank-sediment bulk density, has promise to accurately quantify volumetric change as well as sediment loads originating from bank erosion, and may provide valuable data of the quantification of bank erosion for incorporation into regional sediment models.

Inverse modelling of fluvial sediment connectivity identifies characteristics and spatial distribution of sediment sources in a large river network.

NASA Astrophysics Data System (ADS)

Schmitt, R. J. P.; Bizzi, S.; Kondolf, G. M.; Rubin, Z.; Castelletti, A.

2016-12-01

Field and laboratory evidence indicates that the spatial distribution of transport in both alluvial and bedrock rivers is an adaptation to sediment supply. Sediment supply, in turn, depends on spatial distribution and properties (e.g., grain sizes and supply rates) of individual sediment sources. Analyzing the distribution of transport capacity in a river network could hence clarify the spatial distribution and properties of sediment sources. Yet, challenges include a) identifying magnitude and spatial distribution of transport capacity for each of multiple grain sizes being simultaneously transported, and b) estimating source grain sizes and supply rates, both at network scales. Herein, we approach the problem of identifying the spatial distribution of sediment sources and the resulting network sediment fluxes in a major, poorly monitored tributary (80,000 km2) of the Mekong. Therefore, we apply the CASCADE modeling framework (Schmitt et al. (2016)). CASCADE calculates transport capacities and sediment fluxes for multiple grainsizes on the network scale based on remotely-sensed morphology and modelled hydrology. CASCADE is run in an inverse Monte Carlo approach for 7500 random initializations of source grain sizes. In all runs, supply of each source is inferred from the minimum downstream transport capacity for the source grain size. Results for each realization are compared to sparse available sedimentary records. Only 1 % of initializations reproduced the sedimentary record. Results for these realizations revealed a spatial pattern in source supply rates, grain sizes, and network sediment fluxes that correlated well with map-derived patterns in lithology and river-morphology. Hence, we propose that observable river hydro-morphology contains information on upstream source properties that can be back-calculated using an inverse modeling approach. Such an approach could be coupled to more detailed models of hillslope processes in future to derive integrated models of hillslope production and fluvial transport processes, which is particularly useful to identify sediment provenance in poorly monitored river basins.

Palaeomagnetism and geochemistry of Early Palaeozoic rocks of the Barrandian (Teplé-Barrandian Unit, Bohemian Massif): palaeotectonic implications

NASA Astrophysics Data System (ADS)

Patočka, F.; Pruner, P.; Štorch, P.

The Barrandian area (the Teplá-Barrandian unit, Bohemian Massif) provided palaeomagnetic results on Early Palaeozoic rocks and chemical data on siliciclastic sediments of both Middle Cambrian and Early Ordovician to Middle Devonian sedimentary sequences; an outcoming interpretation defined source areas of clastic material and palaeotectonic settings of the siliciclastic rock deposition. The siliciclastic rocks of the earliest Palaeozoic sedimentation cycle, deposited in the Cambrian Příbram-Jince Basin of the Barrandian, were derived from an early Cadomian volcanic island arc developed on Neoproterozoic oceanic lithosphere and accreted to a Cadomian active margin of northwestern Gondwana. Inversion of relief terminated the Cambrian sedimentation, and a successory Prague Basin subsided nearby since Tremadocian. Source area of the Ordovician and Early Silurian shallow-marine siliciclastic sediments corresponded to progressively dissected crust of continental arc/active continental margin type of Cadomian age. Since Late Ordovician onwards both synsedimentary within-plate basic volcanics and older sediments had been contributing in recognizable proportions to the siliciclastic rocks. The siliciclastic sedimentation was replaced by deposition of carbonate rocks throughout late Early Silurian to Early Devonian period of withdrawal of the Cadomian clastic material source. Above the carbonates an early Givetian flysch-like siliciclastic suite completed sedimentation in the Barrandian. In times between Middle Cambrian and Early/Middle Devonian boundary interval an extensional tectonic setting prevailed in the Teplá-Barrandian unit. The extensional regime was related to Early Palaeozoic large-scale fragmentation of the Cadomian belt of northwestern Gondwana and origin of Armorican microcontinent assemblage. The Teplá-Barrandian unit was also engaged in a peri-equatorially oriented drift of Armorican microcontinent assemblage throughout the Early Palaeozoic: respective palaeolatitudes of 58°S (Middle Cambrian) and 17°S (Middle Devonian) were inferred for the Barrandian rocks. The Middle Devonian flysch-like siliciclastics of the Prague Basin suggest a reappearance of the deeply dissected Cadomian source area in a proximity of the Barrandian due to early Variscan convergences and collisions of the Armorican microcontinents. Significant palaeotectonic rotations are palaeomagnetically evidenced to take place during oblique convergence and final docking of the Teplá-Barrandian microplate within the Variscan terrane mosaic of the Bohemian Massif.

Water-quality assessment of the Kentucky River Basin, Kentucky; distribution of metals and other trace elements in sediment and water, 1987-90

USGS Publications Warehouse

Porter, Stephen D.; White, Kevin D.; Clark, J.R.

1995-01-01

The U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program is designed to provide a nationally consistent description of the current status of water quality, to define water-quality trends, and to relate past and present water-quality conditions to natural features, uses of land and water, and other water-quality effects from human activities. The Kentucky River Basin is one of four NAWQA pilot projects that focused primarily on the quality of surface water. Water, sediment, and bedrock samples were collected in the Kentucky River Basin during 1987-90 for the purpose of (1) describing the spatial distribution, transport, and temporal variability of metals and other trace elements in streams of the basin; (2) estimating mean annual loads, yields, and trends of constituent concentrations and identifying potential causes (or sources) of spatial patterns; (3) providing baseline information for concentrations of metals in streambed and suspended sediments; (4) identifying stream reaches in the Kentucky River Basin with chronic water-quality problems; and (5) evaluating the merits of the NAWQA pilot study-approach for the assessment of metals and other trace elements in a river system. The spatial distribution of metals and other trace elements in streambed sediments of the Kentucky River Basin is associated with regional differences of geology, land use and cover, and the results of human activities. Median concentrations of constituents differed significantly among physiographic regions of the basin because of relations to bedrock geochemistry and land disturbance. Concentrations of potentially toxic metals were large in urban and industrial areas of the basin. Elevated concentrations of certain metals were also found in streambed sediments of the Knobs Region because of the presence of Devonian shale bedrock. Elevated concentrations of lead and zinc found in streambed sediments of the Bluegrass Region are likely associated with urban stormwater runoff, point-source discharges, and waste-management practices. Concentrations of cadmium, chromium, copper, mercury, and silver were elevated in streambed sediments downstream from wastewater-treatment plant discharges. Streambed-sediment concentrations of barium, chromium, and lithium were elevated in streams that receive brine discharges from oil production. Elevated concentrations of antimony, arsenic, molybdenum, selenium, strontium, uranium, and vanadium in streambed sediments of the Kentucky River Basin were generally associated with natural sources. Concentrations of metals and other trace elements in water samples from fixed stations (stations where water-quality samples were collected for 3.5 years) in the Kentucky River Basin were generally related to stream discharge and the concentration of suspended sediment, whereas constituent concentrations in the suspended-sediment matrix were indicative of natural and human sources. Estimated mean annual loads and yields for most metals and other trace elements were associated with the transport of suspended sediment. Land disturbance, such as surface mining and agriculture, contribute to increased transport of sediment in streams, thereby increasing concentrations of metals in water samples during periods of intense or prolonged rainfall and increased stream discharge. Concentrations of many metals and trace elements were reduced during low streamflow. Although total-recoverable and dissolved concentrations of certain metals and trace elements were large in streams affected by land disturbance, concentrations of constituents in the suspendedsediment matrix were commonly large in streams in the Knobs and Eastern Coal Field Regions (because of relations with bedrock geochemistry) and in streams that receive wastewater or oil-well-brine discharges. Concentrations and mean annual load estimates for aluminum, chromium, copper, iron, lead, manganese, and mercury were larger than those obtained from data collected by a State agency, probably because of differences in sample-collection methodology, the range of discharge associated with water-quality samples, and laboratory analytical procedures. However, concentrations, loads, and yields of arsenic, barium, and zinc were similar to those determined from the State data. Significant upward trends in the concentrations of aluminum, iron, magnesium, manganese, and zinc were indicated at one or more fixed stations in the Kentucky River Basin during the past 10 to 15 years. Upward trends for concentrations of aluminum, iron, and manganese were found at sites that receive drainage from coal mines in the upper Kentucky River Basin, whereas upward trends for zinc may be associated with urban sources. Water-quality criteria established by the U.S. Environmental Protection Agency (USEPA) or the State of Kentucky for concentrations of aluminum, beryllium, cadmium, chromium, copper, iron, manganese, nickel, silver, and zinc were exceeded at one or more fixed stations in the Kentucky River Basin. On a qualitative basis, dissolved concentrations of certain metals and trace elements were large during low streamflow at sites where (1) concentrations of these constituents in underlying streambed sediments were large, or (2) dissolvedoxygen concentrations were small. Concentrations of barium, lithium, and strontium were large during low streamflow, which indicates the influence of ground-water baseflows on the quality of surface water during low flow. The effects of point-source discharges, landfills, and other wastemanagement practices are somewhat localized in the Kentucky River Basin and are best indicated by the spatial distribution of metals and other trace elements in streambed sediments and in the suspended-sediment fraction of water samples at stream locations near the source. It was not possible to quantify the contribution of point sources to the total transport of metals and other trace elements at fixed stations because data were not available for wastewater effluents. Quantification of baseline concentrations of metals and other trace elements in streambed sediments provides a basis for the detection of water-quality changes that may result from improvements in wastewater treatment or the implementation of best-management practices for controlling contamination from nonpoint sources in the Kentucky River Basin.

Eolian and riverine contributions to central-Mediterranean sediments: a high-resolution Holocene record

NASA Astrophysics Data System (ADS)

Wu, Jiawang; Böning, Philipp; Pahnke, Katharina; Tachikawa, Kazuyo; De Lange, Gert

2017-04-01

Circum-Mediterranean climate variability is reflected in sediments deposited and preserved at the Mediterranean seafloor. Alternating depositions of organic-lean marls and organic-rich sapropel sediments in the eastern Mediterranean Sea (EMS) are clearly related to precessional hydroclimate variability. The exact origin for freshwater sources and related changes therein during sapropel formation are still debated. Here, Sr and Nd isotopes and high-resolution elemental ratios from core CP10BC are used to unravel and constrain different eolian and riverine supplies from North Africa and from northern borderlands to the central Mediterranean over the past 9.8 ka. Based on Sr and Nd isotopic and elemental compositions, the provenance for detrital sediments in the Levantine basin can be adequately described using 2-end-members. However, in the central Mediterranean, a three-endmember mixing system is required. The three endmember include Saharan Dust, Aegean/Nile, and Libyan Soil, which respectively represents the eolian supply from North Africa, the riverine inputs from the Aegean/Nile areas, and the riverine and shelf-derived fluxes from the Libyan-Tunisian margin. For the first time, robust and consistent evidence is given for important riverine supplies from the Libyan-Tunisian margin into the central Mediterranean during sapropel S1 time in particular. Considerable amounts of detrital materials and freshwater must have been delivered into the EMS through the fossil river/wadi systems, which were activated by intensified African monsoon precipitation. A west-east comparison of Sr-Nd isotope data between core CP10BC and 4 other cores throughout the EMS shows that, such detrital supplies originated mainly from western Libya and Tunisia, and were transported as far eastward as 25°E while being diluted by an increasing Nile contribution. The Nile contribution to the central-Mediterranean detrital sediment fraction appears to have been negligible. Moreover, elemental proxies (Ti/Al, K/Al, Y/Sc, Ce/Ni, and Zr/Cr) reflect concordant changes in the three endmembers at high resolution. These indicate that enhanced precipitation and associated detrital fluxes must have occurred not only from North Africa but also from the northern EMS borderlands. Changes in the Libyan-Tunisian riverine contribution show a close correspondence with hydroclimate evolution of NW Libya on the one hand, and with prominent riverine contribution from the northern EMS borderlands on the other (Wu et al., 2016). Wu, J., Böning, P., Pahnke, K., Tachikawa, K., De Lange, G.J., 2016. Unraveling North-African riverine and eolian contributions to central Mediterranean sediments during Holocene sapropel S1 formation. Quaternary Science reviews 152, 31-48.

Microbial methane formation in deep aquifers of a coal-bearing sedimentary basin, Germany

PubMed Central

Gründger, Friederike; Jiménez, Núria; Thielemann, Thomas; Straaten, Nontje; Lüders, Tillmann; Richnow, Hans-Hermann; Krüger, Martin

2015-01-01

Coal-bearing sediments are major reservoirs of organic matter potentially available for methanogenic subsurface microbial communities. In this study the specific microbial community inside lignite-bearing sedimentary basin in Germany and its contribution to methanogenic hydrocarbon degradation processes was investigated. The stable isotope signature of methane measured in groundwater and coal-rich sediment samples indicated methanogenic activity. Analysis of 16S rRNA gene sequences showed the presence of methanogenic Archaea, predominantly belonging to the orders Methanosarcinales and Methanomicrobiales, capable of acetoclastic or hydrogenotrophic methanogenesis. Furthermore, we identified fermenting, sulfate-, nitrate-, and metal-reducing, or acetogenic Bacteria clustering within the phyla Proteobacteria, complemented by members of the classes Actinobacteria, and Clostridia. The indigenous microbial communities found in the groundwater as well as in the coal-rich sediments are able to degrade coal-derived organic components and to produce methane as the final product. Lignite-bearing sediments may be an important nutrient and energy source influencing larger compartments via groundwater transport. PMID:25852663

The Holocene Records of Glycerol Dialkyl Glycerol Tetraethers From the Northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Park, Y.; Yamamoto, M.; Nam, S.; Polyak, L. V.

2013-12-01

We analyzed glycerol dialkyl glycerol tetraethers (GDGTs) in Cores HOTRAX 05-01 JPC5 and JPC 8, and ARA02B 01-GC in the northern Chukchi Sea. All of the three cores showed a similar changing pattern in GDGT composition during the Holocene. In the beginning of early Holocene, both isoprenoid and branched GDGT concentrations were low, and BIT and CBT were relatively high. The similar composition is found in modern sediments from the western Arctic Ocean north of 75°N, suggesting that the northern Chukchi Sea was covered by perennial sea ice. GDGT concentration increased, and BIT and CBT decreased during the early Holocene and reached the same level as those in modern sediments at 8 ka. TEX86 and CBT/MBT indices showed millennial-scale variation. We interpret that these proxies did not simply indicate temperatures but were affected by the relative contribution of different sediment sources. Millennial-scale variability likely reflected changes in sediment transport in the northern Chukchi Sea.

Freeze-thaw processes and intense winter rainfall: The one-two punch for high streambank legacy sediment and nutrient loads from Mid-Atlantic watersheds

NASA Astrophysics Data System (ADS)

Inamdar, S. P.; Johnson, E. R.; Rowland, R. D.; Walter, R. C.; Merritts, D.

2017-12-01

Historic and contemporary anthropogenic soil erosion combined with early-American milldams resulted in large deposits of legacy sediments in the valley bottoms of Piedmont watersheds of the eastern US. Breaching of milldams subsequently yielded highly incised streams with exposed vertical streambanks that are vulnerable to erosion. Streambank erosion is attributed to fluvial scouring, freeze-thaw processes and mass wasting. While streambanks represent a large reservoir of fine sediments and nutrients, there is considerable uncertainty about the contribution of these sources to watershed nonpoint source pollution. Using high-frequency hydrologic, sediment, and turbidity data we show that freeze-thaw events followed by intense winter rainstorms can export unusually high concentrations of suspended sediment and particulate nutrients from watersheds. Data from a 12 ha forested, Piedmont, stream following an intense rain event (54 mm) on February 2016 yielded suspended sediment and particulate nutrient (organic carbon and nitrogen) concentrations and exports that exceeded those from tropical storms Irene, Lee, and Sandy that had much greater rainfall and discharge amounts, but which occurred later in the year. A similar response was also observed with regards to turbidity data for USGS stream monitoring locations at Brandywine Creek (813 km2) and White Clay Creek (153 km2). We hypothesize that much of the sediment export associated with winter storms is likely due to erosion of streambank sediments and was driven by the coupled occurrence of freeze-thaw conditions and intense rainfall events. We propose that freeze-thaw erosion represents an important and underappreciated mechanism in streams that "recharges" the sediment supply, which then is available for flushing by moderate to large storms. Future climate projections indicate increased intensification of storm events and increased variability of winter temperatures. Freeze-thaw cycles coupled with winter rain events could increase erosion and transport of streambank sediments with detrimental consequences for water quality and health of downstream aquatic ecosystems. This study underscores the need to better understand the mechanisms of legacy sediment erosion and transport along with appropriate restoration strategies.

Tephrostratigraphy of the late Quaternary record from Lake Chalco, central México

NASA Astrophysics Data System (ADS)

Ortega-Guerrero, Beatriz; Caballero García, Lizeth; Linares-López, Carlos

2018-01-01

Lacustrine sequences in active volcanic settings preserve the record of fall-out products (tephras) from explosive volcanic activity from both proximal and distal sources. Sediments of Lake Chalco, located in the western part of the Trans Mexican Volcanic Belt, offer the opportunity to develop a detailed tephrostratigraphy of proximal and distal sources, and to provide stratigraphic marker horizons for the correlation of paleoclimate records. Here, we present major oxide glass and pumice data from 18 tephra layers interbedded in the lacustrine sediments of Chalco, from 11.5 to 31.3 cal ka BP. Tephra glass compositions range from basaltic trachyandesitic to rhyolitic. Two tephras were successfully correlated with the Tutti Frutti Plinian Eruption of Popocatépetl volcano; and two tephra layers from the Nevado de Toluca Plinian activity: the Upper Toluca Pumice and the Lower Toluca Pumice. Although the source of most of the tephras analyzed is unknown, their geochemical characterization, coupled with a robust chronology, contributes to establish a detailed tephrostratigraphy for the region. This tephra record also contributes to improving the estimated frequency of explosive volcanic activity for future hazards in the Basin of México and surrounding areas, where more than 29 million people live. Our findings estimate a recurrence interval of volcanic activity of ca. 1100 years in the interval between ca. 32 and 11.5 cal ka BP, shorter than previously estimated.

Contribution of bank erosion to the sediment budget of a drained agricultural lowland catchment

NASA Astrophysics Data System (ADS)

Cerdan, Olivier; Foucher, Anthony; Vandromme, Rosalie; Salvador-Blanes, Sébastien; Gay, Aurore; Landemaine, Valentin; Evrard, Olivier

2017-04-01

Following the shift towards more intensive agriculture in cultivated lowlands in Europe, field sizes have increased and stream valley meanderings have been removed and realigned along new straight field borders. These modifications have led to profound alterations of the hydromorphology of the streams. To test the impact of these modifications, the long-term and current volumes of sediment originating from stream banks were calculated as they provided potential sources of sediment in a large pond located at the outlet of a small agricultural lowland basin under strong anthropogenic pressure. Bank erosion was measured using several methodologies, i) over a short period using a set of erosion pins along a small stream (1400 m long) to quantify the material exported during a single winter season (2012/2013); ii) over the last 69 years using an original approach involving the comparison of a compilation of three-dimensional historical stream redesign plans from 1944 vs. new measurements conducted in 2013 (DGPS and LiDAR data); iii) over several decades by using tracers (137Cs) that can differentiate between surface and subsoil erosion. At the catchment scale, total sediment exports were estimated from 1945 to 2013 combining seismic imagery and core dating in the lake. Sediment exports decreased with time, from 300 t. km-2.yr-between 1954 and 1980 to 95 t. km-2.yr-1 between 1980 and 2013. Today, erosion rates recorded at the outlet of the catchment vary between 90-102 t.km-2.yr-1. Therefore, the order of magnitude of the mean export rate is approximately 180 t. km-2.yr-1 for the last 70 years. The contribution of channel banks to this sediment export was the highest ( 30%) between 1954 and 1980 when the ditches were constructed. For the entire period since the landscape modification, the contribution of bank erosion is lower but still reaches 20%. Bank erosion can therefore be considered as a significant contributor to the sediment budget of the lowland catchments that have been redesigned after the 2nd world war in Western Europe.

Biogeochemical cycling of permeable sediments in a shelf sea environment: Celtic Sea, a seasonal study.

NASA Astrophysics Data System (ADS)

Reynolds, S.; Klar, J. K.; Kitidis, V. A.; Chapman-Greig, L.; Panton, A.; Thompson, C.; Statham, P. J.; Fones, G. R.

2016-02-01

Shelf seas are globally important in contributing to the biogeochemical cycling of carbon and nutrients. Much of the benthic environment found in shelf seas comprise of relic permeable sands whereby advective pore-water flow processes govern the biogeochemical cycling within these sediments. To further elucidate our understanding of the biogeochemistry of these systems, flow-through reactors were employed during a field campaign as part of the UK led Shelf Sea Biogeochemistry Programme. Three cruises took place in the southern Celtic Sea in 2015 and were timed to sample pre-bloom, post-bloom and late summer conditions. Preliminary data show marked differences with the pre-bloom and late summer flow-through incubations when compared with the post-bloom. Pre-bloom and late summer oxygen consumption rates ranged between 0.18 mmol O2 m-3 d-1 and 0.15 mmol O2 m-3 d-1 respectively. However, post-bloom oxygen consumption rates were almost double at 0.29 mmol O2 m-3 d-1. Differences were also observed in the amount of iron (II) being released with no marked releases from the pre-bloom and late summer but with significant contributions of up to 140 nM during the post-bloom incubation. These initial findings demonstrate the seasonal variability and extent of the biogeochemical cycling of benthic permeable sediments. Additional measurements of inorganic nutrients, dissolved organic carbon and denitrification rates will contribute further to our understanding of sandy sediments in a shelf sea environment and their capacity to act as a carbon and nutrient source or sink.

Mercury transformations in resuspended contaminated sediment controlled by redox conditions, chemical speciation and sources of organic matter

NASA Astrophysics Data System (ADS)

Zhu, Wei; Song, Yu; Adediran, Gbotemi A.; Jiang, Tao; Reis, Ana T.; Pereira, Eduarda; Skyllberg, Ulf; Björn, Erik

2018-01-01

Mercury (Hg) contaminated sediments can be significant sources of Hg in aquatic ecosystems and, through re-emission processes, to the atmosphere. Transformation and release of Hg may be enhanced by various sediment perturbation processes, and controlling biogeochemical factors largely remain unclear. We investigated how rates of Hg transformations in pulp-fiber enriched sediment contaminated by Hg from chlor-alkali industry were controlled by (i) transient redox-changes in sulfur and iron chemistry, (ii) the chemical speciation and solubility of Hg, and (iii) the sources and characteristics of organic matter (OM). Sediment-bottom water microcosm systems were exposed to four combinations of air and nitrogen gas for a total time of 24 h. The treatments were: 24 h N2, 0.5 h air + 23.5 h N2, 4 h air + 20 h N2 and 24 h of air exposure. As a result of these treatments, microcosms spanned a wide range of redox potential, as reflected by the dissolved sulfide concentration range of ≤0.3-97 μM. Four different chemical species of inorganic divalent Hg (HgII) and methyl mercury (MeHg), enriched in different Hg isotope tracers, were added to the microcosms: 201Hg(NO3)2(aq), 202HgII adsorbed to OM (202HgII-OM(ads)), 198HgII as microcrystalline metacinnabar (β-198HgS(s)) and Me204HgCl(aq). Microcosm systems were composed of bottom water mixed with sediment taken at 0-2, 0-5 and 0-10 cm depth intervals. The composition of OM varied with sediment depth such that compared to deeper sediment, the 0-2 cm depth-interval had a 2-fold higher contribution of labile OM originating from algal and terrestrial inputs, serving as metabolic electron-donors for microorganisms. The potential methylation rate constant (kmeth) of Hg tracers and net formation of ambient MeHg (MeHg/THg molar ratio) increased up to 50% and 400%, respectively at intermediate oxidative conditions, likely because of an observed 2-fold increase in sulfate concentration stimulating the activity of sulfate reducing bacteria with a capability of methylating HgII. Due to differences in HgII water-sediment partitioning, kmeth varied by a factor of 11-70 for the different isotope-enriched Hg tracers. The chemical form of HgII was a major controlling factor for kmeth and its response to the resuspension-oxidation of the system. The β-198HgS(s) tracer had the lowest kmeth and it was mainly constrained by redox-driven HgII solubility. The 202HgII-OM(ads) tracer showed an intermediate value on kmeth. It was controlled by both HgII solubility and availability of electron donors and acceptors, regulating bacterial activity. The 201Hg(NO3)2(aq) tracer had the highest value on kmeth which was limited mainly by bacterial activity. The kmeth was up to a factor of 3 higher in the 0-2 cm sediment depth-interval than in 0-5 and 0-10 cm intervals due to a larger contribution of labile OM in the 0-2 cm sediment. Reduction of HgII to Hg0 followed by volatilization exclusively occurred at high sulfidic conditions in the top 0-2 cm sediment. Aromatic moieties of terrestrial OM, present mainly in the top sediment, is suggested to control the reduction of HgII. The Hg0 volatilization rate constant for the 202HgII-OM(ads) tracer exceeded that for β-198HgS(s) by one order of magnitude. Our results suggest that contaminated sediments posing a high risk for reactivation of legacy Hg following transient redox resuspension events are characterized by depletion of sulfate in the sediment porewater prior to resuspension, predominance of HgII species with solubility exceeding that of crystalline β-HgS(s), and conditions promoting in situ formation and/or import of labile OM from algal and terrestrial sources.

Geochemical characterization of Neogene sediments from onshore West Baram Delta Province, Sarawak: paleoenvironment, source input and thermal maturity

NASA Astrophysics Data System (ADS)

Togunwa, Olayinka S.; Abdullah, Wan H.

2017-08-01

The Neogene strata of the onshore West Baram Province of NW Borneo contain organic rich rock formations particularly within the Sarawak basin. This basin is a proven prolific oil and gas province, thus has been a subject of great interest to characterise the nature of the organic source input and depositional environment conditions as well as thermal maturation. This study is performed on outcrop samples of Lambir, Miri and Tukau formations, which are of stratigraphic equivalence to the petroleum bearing cycles of the offshore West Baram delta province in Sarawak. The investigated mudstone samples are organic rich with a total organic carbon (TOC) content of more than 1.0 wt.%. The integration of elemental and molecular analyses indicates that there is no significant variation in the source input between these formations. The investigated biomarkers parameters achieved from acyclic isoprenoids, terpanes and steranes biomarkers of a saturated hydrocarbon biomarkers revealed that these sediments contain high contribution of land plants with minor marine organic matter input that was deposited and preserved under relatively oxic to suboxic conditions. This is further supported by low total sulphur (TS), high TOC/TN ratios, source and redox sensitive trace elements (V, Ni, Cr, Co and Mo) concentrations and their ratios, which suggest terrigenous source input deposited under oxic to suboxic conditions. Based on the analysed biomarker thermal maturity indicators, it may be deduced that the studied sediments are yet to enter the maturity stage for hydrocarbon generation, which is also supported by measured vitrinite reflectance values of 0.39-0.48% Ro.

Use of stable isotopes of carbon and nitrogen to identify sources of organic matter to bed sediments of the Tualatin River, Oregon

USGS Publications Warehouse

Bonn, Bernadine A.; Rounds, Stewart A.

2010-01-01

The potential sources of organic matter to bed sediment of the Tualatin River in northwestern Oregon were investigated by comparing the isotopic fractionation of carbon and nitrogen and the carbon/nitrogen ratios of potential sources and bed sediments. Samples of bed sediment, suspended sediment, and seston, as well as potential source materials, such as soil, plant litter, duckweed, and wastewater treatment facility effluent particulate were collected in 1998-2000. Based on the isotopic data, terrestrial plants and soils were determined to be the most likely sources of organic material to Tualatin River bed sediments. The delta 13C fractionation matched well, and although the delta 15N and carbon/nitrogen ratio of fresh plant litter did not match those of bed sediments, the changes expected with decomposition would result in a good match. The fact that the isotopic composition of decomposed terrestrial plant material closely resembled that of soils and bed sediments supports this conclusion. Phytoplankton probably was not a major source of organic matter to bed sediments. Compared to the values for bed sediments, the delta 13C values and carbon/nitrogen ratios of phytoplankton were too low and the delta 15N values were too high. Decomposition would only exacerbate these differences. Although phytoplankton cannot be considered a major source of organic material to bed sediment, a few bed sediment samples in the lower reach of the river showed a small influence from phytoplankton as evidenced by lower delta 13C values than in other bed sediment samples. Isotopic data and carbon/nitrogen ratios for bed sediments generally were similar throughout the basin, supporting the idea of a widespread source such as terrestrial material. The delta 15N was slightly lower in tributaries and in the upper reaches of the river. Higher rates of sediment oxygen demand have been measured in the tributaries in previous studies and coupled with the isotopic data may indicate the presence of more labile organic matter in these areas. Results from this study indicate that strategies to improve oxygen conditions in the Tualatin River are likely to be more successful if they target sources of soil, leaf litter, and other terrestrially derived organic materials to the river rather than the instream growth of algae.

The Forgotten Legacy: Sediment From Historical Gold Mining Greatly Exceeds all Other Anthropogenic Sources in SE Australian Rivers

NASA Astrophysics Data System (ADS)

Rutherfurd, I.; Davies, P.; Macklin, M. G.; Grove, J. R.

2016-12-01

Coarse and fine sediment has been a major pollutant of Australian rivers and receiving waters since European settlement in 1788. Anthropogenic sediment budget models demonstrate that catchment and channel erosion has increased background sediment delivery by 10 to 20 times across SE Australia, but these estimates ignore the contribution of historical gold mining. Detailed historical records allow us to reconstruct the delivery of coarse and fine sediment (including contaminated sediment) to the fluvial system. Between 1851 and 1900 alluvial gold mining in the state of Victoria liberated between 1.2 billion and 1.4 billion m3 of coarse and fine sediment into streams. Catchment scale modelling demonstrates that this volume is at least twice the volume of all anthropogenic (post-European) erosion from hillslopes, river banks, and gullies. We map the deposition and remobilization of these contaminated legacy mining sediments down selected valleys, and find that many contemporary floodplains are blanketed with mining sediments (although mercury contamination is present but low), and discrete sediment-slugs can be recognized migrating down river beds. Overall, the impact of gold mining is one of the strongest indicators of the Anthropocene in the Australian landscape, and the level of impact on rivers is substantially greater than recognized in the past. Perhaps of most interest is the rapid recovery of many river systems from the substantial impacts of gold mining. The result is that these major changes to the landscape are largely forgotten.

Chemical characterization of sediment "Legacy P" in watershed streams - implications for P loading under land management

NASA Astrophysics Data System (ADS)

Audette, Yuki; O'Halloran, Ivan; Voroney, Paul

2016-04-01

Transfer of dissolved phosphorus (P) in runoff water via streams is regulated mainly by both stream sediment P adsorption and precipitation processes. The adsorption capacity of stream sediments acting as a P sink was a great benefit to preserving water quality in downstream lakes in the past, as it minimized the effects of surplus P loading from watershed streams. However, with long-term continued P loading the capacity of the sediments to store P has diminished, and eventually converted stream sediments from P sinks to sources of dissolved P. This accumulation of 'legacy P' in stream sediments has become the major source of dissolved P and risk to downstream water quality. Agricultural best management practices (BMP) for P typically attempt to minimize the transfer of P from farmland. However, because of the limitation in sediment P adsorption capacity, adoption of BMPs, such as reduction of external P loading, may not result in an immediate improvement in water quality. The goal of the research is to chemically characterize the P forms contributing to legacy P in stream sediments located in the watershed connecting to Cook's Bay, one of three basins of Lake Simcoe, Ontario, Canada. This watershed receives the largest amount of external P loading and has the highest rate of sediment build-up, both of which are attributed to agriculture. Water samples were collected monthly at six study sites from October 2015 for analysis of pH, temperature, dissolved oxygen, total P, dissolved reactive P, particulate P, total N, NH4-N, NO3-N, TOC and other elements including Al, Fe, Mn, Mg, Ca, S, Na, K and Zn. Sediment core samples were collected in November 2015 and will continue to be collected in March, July and October 2016. Various forms of P in five vertical sections were characterized by sequential fractionation and solution 31P NMR spectroscopy techniques. Pore water, sediment texture and clay identification were performed. The concentration of total P in water samples were ~equal or less than the Ontario Provincial Water Quality Objectives (PWQO) of 0.03 mg P L-1 except at a site located in the stream in the Holland Marsh, which was ~7 times greater. Forms and distribution of P varied with sediment section and sampling site. The range of total sediment-P was from ~0.8 to 2.5 g P kg-1 sediment, and at some sites the mobile P forms accounted for > 75% of the total sediment-P. The study will continue to examine the temporal spatial and vertical distribution of P forms to predict the rates of P release under varying water chemistries. This basic research provides a fundamental approach for characterization of the legacy P in stream sediments, ultimately providing a better understanding of the linkage between changes in agricultural management practices affecting P losses from terrestrial sources and observed changes in surface water quality.

Can marine bacteria be recruited from freshwater sources and the air?

PubMed Central

Comte, Jérôme; Lindström, Eva S; Eiler, Alexander; Langenheder, Silke

2014-01-01

There is now clear evidence that microorganisms present biogeographic patterns, yet the processes that create and maintain them are still not well understood. In particular, the contribution of dispersal and its exact impact on local community composition is still unclear. For example, dispersing cells may not thrive in recipient environments, but may still remain part of the local species pool. Here, we experimentally tested if marine bacteria can be retrieved from freshwater communities (pelagic and sediment) and the atmosphere by exposing bacteria from three lakes, that differ in their proximity to the Norwegian Sea, to marine conditions. We found that the percentage of freshwater taxa decreased with increasing salinities, whereas marine taxa increased along the same gradient. Our results further showed that this increase was stronger for lake and sediment compared with air communities. Further, significant increases in the average niche breadth of taxa were found for all sources, and in particular lake water and sediment communities, at higher salinities. Our results therefore suggests that marine taxa can readily grow from freshwater sources, but that the response was likely driven by the growth of habitat generalists that are typically found in marine systems. Finally, there was a greater proportion of marine taxa found in communities originating from the lake closest to the Norwegian Sea. In summary, this study shows that the interplay between bacterial dispersal limitation and dispersal from internal and external sources may have an important role for community recovery in response to environmental change. PMID:24906016

Distribution and source analysis of heavy metal pollutants in sediments of a rapid developing urban river system.

PubMed

Xia, Fang; Qu, Liyin; Wang, Ting; Luo, Lili; Chen, Han; Dahlgren, Randy A; Zhang, Minghua; Mei, Kun; Huang, Hong

2018-09-01

Heavy metal pollution of aquatic environments in rapidly developing industrial regions is of considerable global concern due to its potential to cause serious harm to aquatic ecosystems and human health. This study assessed heavy metal contamination of sediments in a highly industrialized urban watershed of eastern China containing several historically unregulated manufacturing enterprises. Total concentrations and solid-phase fractionation of Cu, Zn, Pb, Cr and Cd were investigated for 39 river sediments using multivariate statistical analysis and geographically weighted regression (GWR) methods to quantitatively examine the relationship between land use and heavy metal pollution at the watershed scale. Results showed distinct spatial patterns of heavy metal contamination within the watershed, such as higher concentrations of Zn, Pb and Cd in the southwest and higher Cu concentration in the east, indicating links to specific pollution sources within the watershed. Correlation and PCA analyses revealed that Zn, Pb and Cd were dominantly contributed by anthropogenic activities; Cu originated from both industrial and agricultural sources; and Cr has been altered by recent pollution control strategies. The GWR model indicated that several heavy metal fractions were strongly correlated with industrial land proportion and this correlation varied with the level of industrialization as demonstrated by variations in local GWR R 2 values. This study provides important information for assessing heavy metal contaminated areas, identifying heavy metal pollutant sources, and developing regional-scale remediation strategies. Copyright © 2018 Elsevier Ltd. All rights reserved.

IDENTIFICATION OF SEDIMENT SOURCE AREAS WITHIN A WATERSHED

EPA Science Inventory

Identification of sediment source areas is crucial for designing proper abatement strategies that reduce sediment and associated contaminant loading to receiving water downstream. In this study, two methodologies were developed to identify the source areas and their relative stre...

Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists?

PubMed

Hong, Seongjin; Lee, Junghyun; Lee, Changkeun; Yoon, Seo Joon; Jeon, Seungyeon; Kwon, Bong-Oh; Lee, Jong-Hyeon; Giesy, John P; Khim, Jong Seong

2016-06-01

Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g(-1) dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g(-1) dm) and outer regions (mean = 25 ng g(-1) dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relative importance of methylotrophic methanogenesis in sediments of the Western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Zhuang, Guang-Chao; Heuer, Verena B.; Lazar, Cassandre S.; Goldhammer, Tobias; Wendt, Jenny; Samarkin, Vladimir A.; Elvert, Marcus; Teske, Andreas P.; Joye, Samantha B.; Hinrichs, Kai-Uwe

2018-03-01

Microbial production of methane is an important terminal metabolic process during organic matter degradation in marine sediments. It is generally acknowledged that hydrogenotrophic and acetoclastic methanogenesis constitute the dominant pathways of methane production; the importance of methanogenesis from methylated compounds remains poorly understood. We conducted various biogeochemical and molecular genetic analyses to characterize substrate availability, rates of methanogenesis, and methanogen community composition, and further evaluated the contribution of different substrates and pathways for methane production in deltaic surface and subsurface sediments of the Western Mediterranean Sea. Major substrates representing three methanogenic pathways, including H2, acetate, and methanol, trimethylamine (TMA), and dimethylsulfide (DMS), were detected in the pore waters and sediments, and exhibited variability over depth and between sites. In accompanying incubation experiments, methanogenesis rates from various 14C labeled substrates varied as well, suggesting that environmental factors, such as sulfate concentration and organic matter quality, could significantly influence the relative importance of individual pathway. In particular, methylotrophic and hydrogenotrophic methanogenesis contributed to the presence of micromolar methane concentrations in the sulfate reduction zone, with methanogenesis from methanol accounting for up to 98% of the total methane production in the topmost surface sediment. In the sulfate-depleted zone, hydrogenotrophic methanogenesis was the dominant methanogenic pathway (67-98%), and enhanced methane production from acetate was observed in organic-rich sediment (up to 31%). Methyl coenzyme M reductase gene (mcrA) analysis revealed that the composition of methanogenic communities was generally consistent with the distribution of methanogenic activity from different substrates. This study provides the first quantitative assessment of methylotrophic methanogenesis in marine sediments and has important implications for marine methane cycling. The occurrence of methylotrophic methanogenesis in surface sediments could fuel the anaerobic oxidation of methane (AOM) in the shallow sulfate reduction zone. Release of methane produced from methylotrophic methanogenesis could be a source of methane efflux to the water column, thus influencing the benthic methane budgets.

Phosphorus regeneration and burial in near-shore marine sediments (the Gulf of Trieste, northern Adriatic Sea)

NASA Astrophysics Data System (ADS)

Ogrinc, N.; Faganeli, J.

2006-05-01

According to bioassay studies and high dissolved nutrient N/P ratios in the seawater column, phosphorus (P) is thought to control marine productivity in the northern Adriatic Sea. P in near-shore marine sediments of the Gulf of Trieste, the northernmost part of the Adriatic Sea, was investigated using pore water P distributions, and benthic P flux studies under oxic and anoxic conditions. The data show that P regeneration is up to three-fold more extensive in sediments overlain by oxygen-depleted waters and proceeds in parallel with Fe and Mn enhanced benthic fluxes. It appears from the incubation experiments that degradation of sedimentary organic matter is the main contribution to the flux of P at the sediment-water interface, while the release of phosphate adsorbed on the iron oxide surface is of minor importance. It appears that about 50% of P in the Gulf of Trieste is retained within in the sediments, probably bonded to clay minerals and carbonate grains or precipitated as fluoroapatite. In these sediments total P (P tot) is preserved preferentially over organic C (C org). P regenerated from surficial sediments contributes about 1/3 of the P that is assimilated by benthic microalgae. The phytoplankton P requirement should be entirely supplied from fresh-water sources. These results suggest that oxygen depletion in coastal areas caused by eutrophication enhances P regeneration from sediments, providing the additional P necessary for increased biological productivity. The development of anoxic bottom waters in coastal areas enhances the recycling of P, exacerbating the nutrient requirement in the area. A geochemical record of P burial in a longer sedimentary sequence revealed an increasing trend of P tot and organic P (P org) contents occurring approximately 50 years BP (after 1950), probably due to increasing use of inorganic fertilizers and detergents in the area.

What contribution do detergent fatty alcohols make to sewage discharges and the marine environment?

PubMed

Mudge, Stephen M; Meier-Augenstein, Wolfram; Eadsforth, Charles; DeLeo, Paul

2010-10-06

To investigate the potential sources of fatty alcohols arriving at a WWTP and entering the receiving waters, a study was conducted at Treborth North Wales using compound specific stable isotope mass spectrometry (¹³C and ²H). Samples were collected from soils, marine sediments, detergents used in the catchment and in the WWTP. Total fatty alcohol concentrations decreased in the liquid phases through the treatment works with the majority of the compounds accumulating in the sludge (biosolids). Natural plant based detergents have δ¹³C values between -26 and -32‰ while petroleum-based detergents occupy a range between -25 and -30‰. The corresponding δ²H values are -250‰ for natural sourced materials and -50‰ for oil-based detergents which enable these two sources to be separated. The influent to the WWTP contained fatty alcohols which originated mainly from faecal sources and natural surfactants (∼75%) with a smaller amount potentially derived from petroleum-based surfactants (∼25%). The effluents from the WWTP contained mainly short chain compounds with a chain length less than C¹⁶. Their δ²H stable isotope signature was different to the other potential sources examined and suggests bacterial synthesis during the treatment processes. The sludge had relatively high concentrations of fatty alcohols as would be expected from their low water solubility. The stable isotopic signatures were consistent with a mixture of faecal and detergent sources. The sludge in this area is routinely spread on agricultural land as a fertiliser and may find its way back into the sea via land runoff. On the basis of the mean discharge rates and the mean C₁₂ concentration in the effluent, this WWTP would contribute ∼300 g day⁻¹ to the receiving waters. The marine sediment samples had short chain fatty alcohols that are typical of marine production and with stable isotope values that indicate exclusive marine production for the C₁₄ potentially mixed with terrestrial sources for the C₁₆ and C₁₈ compounds. Therefore, the fatty alcohols in the marine sediments are not the same as those that were discharged in the liquid effluent and these fatty alcohols were not the ones that entered the works through the influent but were synthesised or recycled within the works.

Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

2013-12-01

We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition to organic carbon and nitrogen content with stable isotope (13C, 15N) and radiocarbon (14C) abundance to quantify OC/SA and organic carbon sources and mean age. We then use multivariate mixing model analysis to quantify the fractional contribution of each source end-member to each sample of suspended or deposited sediments. Last, we calculate a predicted OC/SA based on source end-member mixing and compare to the measured OC/SA to quantify net change in mineral complexed carbon. Aufdenkampe, A.K. et al. Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere. Frontiers Ecol. Environ. 9, 53-60 (2011). Walling, D. E. Tracing suspended sediment sources in catchments and river systems. Sci. Total Environ. 34, 159-184 (2005).

Spatially distributed rockfall activity inferred from talus deposits and corresponding rockwall areas in the Gradenbach catchment (Schober Mountains, Austria)

NASA Astrophysics Data System (ADS)

Götz, Joachim; Buckel, Johannes; Heckmann, Tobias

2013-04-01

The analysis of alpine sediment cascades requires the identification, differentiation and quantification of sediment sources, storages, and transport processes. This study deals with the origin of alpine sediment transfer and relates primary talus deposits to corresponding rockwall source areas within the Gradenbach catchment (Schober Mountains, Austrian Alps). Sediment storage landforms are based on a detailed geomorphological map of the catchment which was generated to analyse the sediment transfer system. Mapping was mainly performed in the field and supplemented by post-mapping analysis using LIDAR data and digital orthophotos. A fundamental part of the mapping procedure was to capture additional landform-based information with respect to morphometry, activity and connectivity. The applied procedure provides a detailed inventory of sediment storage landforms including additional information on surface characteristics, dominant and secondary erosion and deposition processes, process activity and sediment storage coupling. We develop the working hypothesis that the present-day surface area ratio between rockfall talus (area as a proxy for volume, backed by geophysical analysis of selected talus cones) and corresponding rockwall source area is a measure of rockfall activity since deglaciation; large talus cones derived from small rockwall catchments indicate high activity, while low activity can be inferred where rockfall from large rock faces has created only small deposits. The surface area ratio of talus and corresponding rockwalls is analysed using a landform-based and a process-based approach. For the landform-based approach, we designed a GIS procedure which derives the (hydrological) catchment area of the contact lines of talus and rockwall landforms in the geomorphological map. The process-based approach simulates rockfall trajectories from steep (>45°) portions of a DEM generated by a random-walk rockfall model. By back-tracing those trajectories that end on a selected talus landform, the 'rockfall contributing area' is delineated; this approach takes account of the stochastic nature of rockfall trajectories and is able to identify, for example, rockfall delivery from one rockwall segment to multiple talus landforms (or from multiple rockfall segments to the same deposit, respectively). Using both approaches, a total of 290 rockwall-talus-subsystems are statistically analysed indicating a constant relationship between rockfall source areas and corresponding areas of talus deposits of almost 1:1. However, certain rockwall-talus-subsystems deviate from this correlation since sediment storage landforms of similar size originate from varying rockwall source areas and vice versa. This varying relationship is assumed to be strongly controlled by morphometric parameters, such as rockwall slope, altitudinal interval, and aspect. The impact of these parameters on the surface area ratio will be finally discussed.