THE INFLUENCE OF MINERAL REACTIONS ON THE ENVIRONMENTAL FATE OF METALS IN SOILS AND SEDIMENTS

EPA Science Inventory

Significant progress has been made in elucidating sorption reactions that control the partitioning of metals from solution to mineral surfaces in contaminated soil/sediment systems. Surface complexation models have been developed to quantify the forward reaction, however, these ...

[Spatial Distribution and Potential Ecological Risk Assessment of Heavy Metals in Soils and Sediments in Shunde Waterway, Southern China].

PubMed

Cai, Yi-min; Chen, Wei-ping; Peng, Chi; Wang, Tie-yu; Xiao, Rong-bo

2016-05-15

Environmental quality of soils and sediments around water source area can influence the safety of potable water of rivers. In order to study the pollution characteristics, the sources and ecological risks of heavy metals Zn, Cr, Pb, Cu, Ni and Cd in water source area, surface soils around the waterway and sediments in the estuary of main tributaries were collected in Shunde, and ecological risks of heavy metals were assessed by two methods of potential ecological risk assessment. The mean contents of Zn, Cr, Pb, Cu, Ni and Cd in the surface soils were 186.80, 65.88, 54.56, 32.47, 22.65 and 0.86 mg · kg⁻¹ respectively, and they were higher than their soil background values except those of Cu and Ni. The mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in the sediments were 312.11, 111.41, 97.87, 92.32, 29.89 and 1.72 mg · kg⁻¹ respectively, and they were higher than their soil background values except that of Ni. The results of principal component analysis illustrated that the main source of Cr and Ni in soils was soil parent materials, and Zn, Pb, Cu and Cd in soils mainly came from wastewater discharge of local manufacturing industry. The six heavy metals in sediments mainly originated from industry emissions around the Shunde waterway. The results of potential ecological risk assessment integrating environmental bioavailability of heavy metals showed that Zn, Cu, Pb and Ni had a slight potential ecological risk. Cd had a slight potential ecological risk in surface soils, but a moderate potential ecological risk in surfaces sediments. Because the potential ecological risk assessment integrating environmental bioavailability of heavy metals took the soil properties and heavy metal forms into account, its results of risks were lower than those of Hakanson methods, and it could avoid overestimating the potential risks of heavy metals.

Determination of Martian soil mineralogy and water content using the Thermal Analyzer for Planetary Soils (TAPS)

NASA Technical Reports Server (NTRS)

Gooding, James L.; Ming, Douglas W.; Allton, Judith H.; Byers, Terry B.; Dunn, Robert P.; Gibbons, Frank L.; Pate, Daniel B.; Polette, Thomas M.

1992-01-01

Physical and chemical interactions between the surface and atmosphere of Mars can be expected to embody a strong cause-and-effect relationship with the minerals comprising the martian regolith. Many of the minerals in soils and sediments are probably products of chemical weathering (involving surface/atmosphere or surface/hydrosphere reactions) that could be expected to subsequently influence the sorption of atmospheric gases and water vapor. Therefore, identification of the minerals in martian surface soils and sediments is essential for understanding both past and present interactions between the Mars surface and atmosphere. Clearly, the most definitive mineral analyses would be achieved with well-preserved samples returned to Earth-based laboratories. In advance of a Mars sample return mission, however, significant progress could be made with in situ experiments that fill current voids in knowledge about the presence or abundance of key soil minerals such as clays (layered-structured silicates), zeolites, and various salts, including carbonates. TAPS is intended to answer that challenge by providing first-order identification of soil and sediment minerals.

MODELING UNCERTAINTY OF RUNOFF AND SEDIMENT YIELD IN TWO EXPERIMENTAL WATERSHEDS

EPA Science Inventory

Sediment loading from agriculture is adversely impacting surface water quality and ecological conditions. In this regard, the use of distributed hydrologic models has gained acceptance in management of soil erosion and sediment yield from agricultural watersheds. Soil infiltrati...

Heavy metal contamination from historic mining in upland soil and estuarine sediments of Egypt Bay, Maine, USA

NASA Astrophysics Data System (ADS)

Osher, L. J.; Leclerc, L.; Wiersma, G. B.; Hess, C. T.; Guiseppe, V. E.

2006-10-01

Concentrations of Cd, Cu, Pb and Zn in sediments of Egypt Bay in Hancock County, Maine, are elevated above background levels. The source of the contamination is Cu mining that occurred in the uplands adjacent to Egypt Stream between 1877 and 1885. Egypt Stream is a tributary to Egypt Bay. Egypt Bay is part of the Taunton Bay estuary system. The Hagan Mine was one of the mines extracting metals from the sulfide deposits in Downeast Maine north of Penobscot Bay. Metal concentrations were determined using ICP-AES after sample digestion with nitric acid. Soil collected from the coarse textured mine tailings pile contained elevated concentrations of Cd, Cu, Pb and Zn, but the majority of the surface soils at the Hagan Mine site were not contaminated. Estuary sediments from the surface to 100 cm depth were collected in four locations within Egypt Bay. Below 40 cm, metal concentrations in sediments were similar to those in uncontaminated upland soils. Metal concentrations in the estuary sediments between the surface and 26 cm were above background levels. According to 210Pb dating, the sediment at 26-34 cm depth was likely to have been deposited at the time the historic mines were in operation. Concentrations of Cd, Cu, Pb, and Zn in sediment from the 32-34 cm depth interval are similar to concentrations in the upland soil sample from the mine tailings pile. Elevated Pb concentrations in sediments from the surface to 24 cm are from atmospheric Pb deposition from anthropogenic sources. Sediment in the top 10 cm of the estuary has been mixed both by the polychaete worm Nereis virens and by those harvesting the worms for sale as fish bait.

Soil erosion under multiple time-varying rainfall events

NASA Astrophysics Data System (ADS)

Heng, B. C. Peter; Barry, D. Andrew; Jomaa, Seifeddine; Sander, Graham C.

2010-05-01

Soil erosion is a function of many factors and process interactions. An erosion event produces changes in surface soil properties such as texture and hydraulic conductivity. These changes in turn alter the erosion response to subsequent events. Laboratory-scale soil erosion studies have typically focused on single independent rainfall events with constant rainfall intensities. This study investigates the effect of multiple time-varying rainfall events on soil erosion using the EPFL erosion flume. The rainfall simulator comprises ten Veejet nozzles mounted on oscillating bars 3 m above a 6 m × 2 m flume. Spray from the nozzles is applied onto the soil surface in sweeps; rainfall intensity is thus controlled by varying the sweeping frequency. Freshly-prepared soil with a uniform slope was subjected to five rainfall events at daily intervals. In each 3-h event, rainfall intensity was ramped up linearly to a maximum of 60 mm/h and then stepped down to zero. Runoff samples were collected and analysed for particle size distribution (PSD) as well as total sediment concentration. We investigate whether there is a hysteretic relationship between sediment concentration and discharge within each event and how this relationship changes from event to event. Trends in the PSD of the eroded sediment are discussed and correlated with changes in sediment concentration. Close-up imagery of the soil surface following each event highlight changes in surface soil structure with time. This study enhances our understanding of erosion processes in the field, with corresponding implications for soil erosion modelling.

Installation Restoration Program. Phase I. Records Search, Hazardous Materials Disposal Sites. Myrtle Beach Air Force Base, South Carolina.

DTIC Science & Technology

1981-10-01

Geography 3-1 Topography 3-. Drainage 3-1 ii Page Surface Geology 3-3 Barrier Sediments 3-3 Myrtle Beach Backbarrier Sediments 3-3 soils 3-5 Subsurface...Beach AFB Surface Drainage and Surface Water Sampling Points 3-2 3.2 Myrtle Beach AFB Surface Soils 3-4 3.3 Myrtle Beach AFB Location of Geologic Cross...has created a potential contamination problem. This situation is compounded by the site’s sandy soil and shallow ground water table. b.) Weathering Pit

Relationship of pyrogenic polycyclic aromatic hydrocarbons contamination among environmental solid media.

PubMed

Kim, Dong Won; Kim, Seung Kyu; Lee, Dong Soo

2009-06-01

This study compared the contamination levels and compositional characteristics of PAHs in soil, SS and sediment to understand the cross media characteristics among the three solid media and ecological risk implications for the purpose to help manage in a more integrated manner the environmental quality objectives or the ecological risk in the media. The study area included urban (metropolis and industrial zone), suburban and rural sites. Seasonal samples were concurrently collected in surface soils, surface waters (dissolved and suspended solid (SS) phases separately) and sediments. The emission estimate and source characterizing PAH indices consistently indicated that PAHs were from pyrogenic sources. The level of total PAHs in soil declined along the wind direction from the urban areas to the rural areas. The sorption power of soil appeared distinctly different between the urban and rural areas. The contamination levels and PAH profiles in soil and sediment were closely related to each other while no such correlation was observed between SS and sediment or SS and soil. Comparisons of the observed partitioning coefficients with three different partitioning equilibrium models strongly suggested that PAHs in water appeared to undergo partitioning among the dissolved phase in water, dissolved organic matter, and organic and soot carbons in SS, which might account for the level and profile of PAHs in SS that were not correlated with those in soil or sediment. The observed results suggested that PAHs of pyrogenic origins entered into soil, sediment, and water by the atmospheric deposition and subsequent other cross-media transfers of PAHs. The results also evidenced that sediments were principally contaminated with PAHs delivered via surface run-off from soil although in the urban areas the run-off influence appeared less immediate than in the rural areas. Environmental quality objectives for PAHs in soil and sediment should be set in a coherent manner and the protection efforts for the sediment quality should be made with the consideration of the soil quality particularly where the river bottom sediment is renewed periodically with eroded soil due to heavy rain and/or large river regime coefficient. In spite of the difference in PAH profiles among the three solid media, BaP commonly appeared to present the greatest TEQ, suggesting that strict regulation of BaP is necessary to efficiently and substantially minimize the total risk of the environmental PAHs.

Fine sediment sources in conservation effects assessment project watersheds

USDA-ARS?s Scientific Manuscript database

Two naturally occurring radionuclides, 7Be and 210Pbxs , were used as tracers to discriminate eroded surface soils from channel-derived sediments in the fine suspended sediment loads of eight Conservation Effects Assessment Project (CEAP) benchmark watersheds. Precipitation, source soils, and suspe...

Surface roughness and runoff

NASA Astrophysics Data System (ADS)

Szabó, Judit Alexandra; Szabó, Boglárka; Centeri, Csaba; Józsa, Sándor; Szalai, Zoltán; Jakab, Gergely

2017-04-01

Soil surface conditions changes dynamically during a precipitation event. The changes involve compaction, aggregate detachment and of course transportation by runoff or drop erosion. Those processes together have an effect on the transport process of the soil particles and aggregates, and influences the roughness of the soil surface as well. How does surface roughness have an effect on the aggregate and particle size distribution of the sediment? How does the sediment connectivity change from precipitation event to precipitation event? Beside the previous questions on of the main aim of the present research is to apply rainfall simulators for the built-up of a complex approach, rather than to concentrate only on one of two factors. Hence four types of sample were collected during the simulation experiment sequences: 1) photos were taken about the surface before and after the rain, in order to build digital surface models; 2) all the runoff and eroded sediment was collected; 3) soil loss due to drop erosion was also sampled separately; and 4) undisturbed crust samples were collected for thin section analyses. Though the runoff ratio was smaller than what, the preliminary results suggest that the sediment connectivity covered bigger area on crusty surface, than on a rough one. These ambiguous data may be connected to the soil crust development. J. A. Szabó wish to acknowledge the support of NTP-NFTÖ-16-0203. G. Jakab wish to acknowledge the support of János Bolyai Fellowship.

Scale and processes dominating soil erosion and sediment transport: case studies from Indonesia and Australia

NASA Astrophysics Data System (ADS)

van Dijk, A. I. J. M.; Bruijnzeel, L. A.

2009-04-01

Soil erosion and sediment transport at different scales of space and time are dominated by a variable set of landscape properties and processes. Research results from West Java (Indonesia) and southeast Australia are presented, taking a natural resources management perspective. The dominant role of vegetation and soil health, rainfall infiltration, and connectivity between hillslope and stream are elaborated on. In humid volcanic upland West Java, vegetative cover and associated infiltration capacity are the dominant control on surface runoff and sediment generation, with additional variation attributed to slope and soil surface structure. Use of process models to replicate and upscale field measurements highlighted that a predictive theory to link vegetative cover and infiltration capacity is lacking, and that full knowledge of the covariance between terrain attributes that promote sediment generation is needed for process based modelling. At the hillslope to catchment scale, slope gradient and a less erodible substrate became additional constraints on sediment yield. A conceptual framework relating processes, scale and sediment delivery ratio was developed. In water-limited southeast Australia, measures to reduce erosion and sediment production generally aim to intercept surface runoff, allowing runoff to infiltrate and sediment to settle on vegetated buffer strips or roadsides or in leaky dams. It is illustrated how remote sensing can help to assess the sources of sediment and hydrological connectivity at different scales and to identify opportunities for mitigation.

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.

Sea level and turbidity controls on mangrove soil surface elevation change

USGS Publications Warehouse

Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

2015-01-01

Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

Spatial glyphosate and AMPA redistribution on the soil surface driven by sediment transport processes - A flume experiment.

PubMed

Bento, Célia P M; Commelin, Meindert C; Baartman, Jantiene E M; Yang, Xiaomei; Peters, Piet; Mol, Hans G J; Ritsema, Coen J; Geissen, Violette

2018-03-01

This study investigates the influence of small-scale sediment transport on glyphosate and AMPA redistribution on the soil surface and on their off-site transport during water erosion events. Both a smooth surface (T1) and a surface with "seeding lines on the contour" (T2) were tested in a rainfall simulation experiment using soil flumes (1 × 0.5 m) with a 5% slope. A dose of 178 mg m -2 of a glyphosate-based formulation (CLINIC ® ) was applied on the upper 0.2 m of the flumes. Four 15-min rainfall events (RE) with 30-min interval in between and a total rainfall intensity of 30 mm h -1 were applied. Runoff samples were collected after each RE in a collector at the flume outlet. At the end of the four REs, soil and sediment samples were collected in the application area and in four 20 cm-segments downslope of the application area. Samples were collected according to the following visually distinguished soil surface groups: light sedimentation (LS), dark sedimentation (DS), background and aggregates. Results showed that runoff, suspended sediment and associated glyphosate and AMPA off-site transport were significantly lower in T2 than in T1. Glyphosate and AMPA off-site deposition was higher for T2 than for T1, and their contents on the soil surface decreased with increasing distance from the application area for all soil surface groups and in both treatments. The LS and DS groups presented the highest glyphosate and AMPA contents, but the background group contributed the most to the downslope off-site deposition. Glyphosate and AMPA off-target particle-bound transport was 9.4% (T1) and 17.8% (T2) of the applied amount, while water-dissolved transport was 2.8% (T1) and 0.5% (T2). Particle size and organic matter influenced the mobility of glyphosate and AMPA to off-target areas. These results indicate that the pollution risk of terrestrial and aquatic environments through runoff and deposition can be considerable. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sediment traps for measuring onslope surface sediment movement

Treesearch

Wade G. Wells; Peter M. Wohlgemuth

1987-01-01

Two types of small (30-cm aperture) sheet metal sediment traps were developed to monitor onslope surface sediment transport. Traditionally, sediment traps and erosion pins have been used to measure the onslope movement of surficial soil material. While pins may be appropriate for documenting landscape denudation, traps are more suitable for monitoring downslope...

Rainfall kinetic energy controlling erosion processes and sediment sorting on steep hillslopes: A case study of clay loam soil from the Loess Plateau, China

NASA Astrophysics Data System (ADS)

Wang, L.; Shi, Z. H.; Wang, J.; Fang, N. F.; Wu, G. L.; Zhang, H. Y.

2014-05-01

Rainfall kinetic energy (KE) can break down aggregates in the soil surface. A better understanding of sediment sorting associated with various KEs is essential for the development and verification of soil erosion models. A clay loam soil was used in the experiments. Six KEs were obtained (76, 90, 105, 160, 270, and 518 J m-2 h-1) by covering wire screens located above the soil surface with different apertures to change the size of raindrops falling on the soil surface, while maintaining the same rainfall intensity (90 ± 3.5 mm h-1). For each rainfall simulation, runoff and sediment were collected at 3-min intervals to investigate the temporal variation of the sediment particle size distribution (PSD). Comparison of the sediment effective PSD (undispersed) and ultimate PSD (dispersed) was used to investigate the detachment and transport mechanisms involved in sediment mobilization. The effective-ultimate ratios of clay-sized particles were less than 1, whereas that of sand-sized particles were greater than 1, suggesting that these particles were transported as aggregates. Under higher KE, the effective-ultimate ratios were much closer to 1, indicating that sediments were more likely transported as primary particles at higher KE owing to an increased severity of aggregate disaggregation for the clay loam soil. The percentage of clay-sized particles and the relative importance of suspension-saltation increased with increasing KE when KE was greater than 105 J m-2 h-1, while decreased with increasing KE when KE was less than 105 J m-2 h-1. A KE of 105 J m-2 h-1 appeared to be a threshold level beyond which the disintegration of aggregates was severe and the influence of KE on erosion processes and sediment sorting may change. Results of this study demonstrate the need for considering KE-influenced sediment transport when predicting erosion.

Experimental and ecosystem model approach to assessing the sensitivity of High arctic deep permafrost to changes in surface temperature and precipitation

NASA Astrophysics Data System (ADS)

Rasmussen, L. H.; Zhang, W.; Elberling, B.; Cable, S.

2016-12-01

Permafrost affected areas in Greenland are expected to experience large temperature increases within the 21st century. Most previous studies on permafrost consider near-surface soil, where changes will happen first. However, how sensitive the deep permafrost temperature is to near-surface conditions through changes in soil thermal properties, snow depth and soil moisture, is not known. In this study, we measured the sensitivity of thermal conductivity (TC) to gravimetric water content (GWC) in frozen and thawed deep permafrost sediments from deltaic, alluvial and fluvial depositional environments in the Zackenberg valley, NE Greenland. We also calibrated a coupled heat and water transfer model, the "CoupModel", for the two closely situated deltaic sites, one with average snow depth and the other with topographic snow accumulation. With the calibrated model, we simulated deep permafrost thermal dynamics in four scenarios with changes in surface forcing: a. 3 °C warming and 20 % increase in precipitation; b. 3 °C warming and 100 % increase in precipitation; c. 6 °C warming and 20 % increase in precipitation; d. 6 °C warming and 100 % increase in precipitation.Our results indicated that frozen sediments had higher TC than thawed sediments. All sediments showed a positive linear relation between TC and soil moisture when frozen, and a logarithmic one when thawed. Fluvial sediments had high sensitivity, but never reached above 12 % GWC, indicating a field effect of water retention capacity. Alluvial sediments were less sensitive to soil moisture than deltaic and fluvial sediments, indicating the importance of unfrozen water in frozen sediment. The deltaic site with snow accumulation had 1 °C higher annual mean ground temperature than the average snow site. The soil temperature at the depth of 18 m increased with 1.5 °C and 3.5 °C in the scenarios with 3 °C and 6 °C warming, respectively. Precipitation had no significant additional effect to warming. We conclude that below-ground sediment properties affect the sensitivity of TC to GWC, that surface temperature changes can significantly affect the deep permafrost within a short period, and that differences in snow depth affect surface temperatures. Geology, pedology and precipitation should thus be considered if estimating future High arctic deep permafrost sensitivity.

Soil erosion transport through multiple rainfall events in the presence of stone cover: Laboratory flume experiments and analysis with the Hairsine-Rose model

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Brovelli, A.; Heng, B. P.; Sander, G. C.; Parlange, J.

2011-12-01

Soil erosion is a major environmental problem that can lead to loss of fertility and degradation of agricultural fields. In order to develop efficient strategies to mitigate the impact of precipitation and reduce the erosion rate, a process-based understanding of the mechanisms that govern sediment transport and delivery is necessary. Soil state and physical properties prior to a precipitation event can affect significantly the erosion rate. Among the most important soil variables are moisture content, compaction and infiltration capacity. Additionally, the presence of stones on the topsoil surface retards the overland flow discharge, reduces runoff generation as well as the sediment delivery and prevents the development of a surface seal, which in turn maintains the infiltration rate. The aim of this study was to examine in detail the effect of surface stones, soil compaction and sealing for a sequence of rainfall events on soil erosion. Experiments were conducted using the EPFL erosion flume, which was divided into two identical flumes (one with stone and one without). The experiment involved four rainfall events with the precipitation rates: 28, 74, 74 and 28 mm h-1. After each 2-h event, the soil was allowed to air dry for 22 h. The total sediment concentration, the concentration of seven sediment size classes and the flow discharge were measured during each event at the outlet of each flume. Experimental results were analyzed using the Hairsine and Rose (H-R) soil erosion model. Results showed that (i) within each precipitation event, the proportion of each size class for the bare/stone-covered flume pairs at steady state were similar, whereas the initial response differed significantly; (ii) in all cases the effluent was enriched in finer particles relative to the original soil; and (iii) the effluent sediment composition was different from that of the original soil, and there was no clear trend towards the parent soil sediment size composition with time. The H-R model was able to reproduce well the events with high precipitation rate (events 2 and 3) with the same parameter set, while the match was less satisfactory for the low precipitation events. A possible explanation for this is that the initial soil compaction/sealing/development of the deposited layer combined to yield a surface that eroded similarly for identical rainfall conditions. Changes in the precipitation rate modifies the soil surface (the deposited layer in particular) and thus the erosion rates. Model application further suggested that over the course of the rainfall events, the contribution of the original soil to the eroded sediment decreased gradually, while that of the deposited layer increased.

Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale

USGS Publications Warehouse

MacDonald, L.H.; Sampson, R.; Brady, D.; Juarros, L.; Martin, Deborah

2000-01-01

Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale in central and western Colorado.Our model for predicting post-fire surface erosion risk is conceptually similar to the Revised Universal Soil Loss Equation (RUSLE). One key addition is the incorporation of a hydrophobicity risk index (HY-RISK) based on vegetation type, predicted fire severity, and soil texture. Post-fire surface erosion risk was assessed for each 90-m pixel by combining HYRISK, slope, soil erodibility, and a factor representing the likely increase in soil wetness due to removal of the vegetation. Sedimentation risk was a simple function of stream gradient. Composite surface erosion and sedimentation risk indices were calculated and compared across the 72 catchments in the study area.When evaluated on a catchment scale, two-thirds of the catchments had relatively little post-fire erosion risk. Steeper catchments with higher fuel loadings typically had the highest post-fire surface erosion risk. These were generally located along the major north-south mountain chains and, to a lesser extent, in west-central Colorado. Sedimentation risks were usually highest in the eastern part of the study area where a higher proportion of streams had lower gradients. While data to validate the predicted erosion and sedimentation risks are lacking, the results appear reasonable and are consistent with our limited field observations. The models and analytic procedures can be readily adapted to other locations and should provide useful tools for planning and management at both the catchment and landscape scale.

Hydroxyatrazine in soils and sediments

USGS Publications Warehouse

Lerch, R.N.; Thurman, E.M.; Blanchard, P.E.

1999-01-01

Hydroxyatrazine (HA) is the major metabolite of atrazine in most surface soils. Knowledge of HA sorption to soils, and its pattern of stream water contamination suggest that it is persistent in the environment. Soils with different atrazine use histories were collected from four sites, and sediments were collected from an agricultural watershed. Samples were exhaustively extracted with a mixed-mode extractant, and HA was quantitated using high performance liquid chromatography with UV detection. Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were also measured in all samples. Concentrations of HA were considerably greater than concentrations of atrazine, DEA, and DIA in all soils and sediments studied. Soil concentrations of HA ranged from 14 to 640 ??g/kg with a median concentration of 84 ??g/kg. Sediment concentrations of HA ranged from 11 to 96 ??g/kg, with a median concentration of 14 ??g/kg. Correlations of HA and atrazine concentrations to soil properties indicated that HA levels in soils were controlled by sorption of atrazine. Because atrazine hydrolysis is known to be enhanced by sorption and pH extremes, soils with high organic matter (OM) and clay content and low pH will result in greater atrazine sorption and subsequent hydrolysis. Significant correlation of HA concentrations to OM, pH, and cation exchange capacity of sediments indicated that mixed-mode sorption (i.e., binding by cation exchange and hydrophobic interactions) was the mechanism controlling HA levels in sediment. The presence of HA in soils and stream sediments at the levels observed support existing hypotheses regarding its transport in surface runoff. These results also indicated that persistence of HA in terrestrial and aquatic ecosystems is an additional risk factor associated with atrazine usage.

Sources of arsenic and fluoride in highly contaminated soils causing groundwater contamination in Punjab, Pakistan

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

Farooqi, A.; Masuda, H.; Siddiqui, R.

2009-05-15

Highly contaminated groundwater, with arsenic (As) and fluoride (F{sup -}) concentrations of up to 2.4 and 22.8 mg/L, respectively, has been traced to anthropogenic inputs to the soil. In the present study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to determine the F{sup -} and As distribution in the soil. The surface soils mainly comprise permeable aeolian sediment on a Pleistocene terrace and layers of sand and silt on an alluvial flood plain. Although the alluvial sediments contain low levels of F, the terrace soils contain high concentrations ofmore » soluble F{sup -} (maximum, 16 mg/kg; mean, 4 mg/kg; pH > 8.0). Three anthropogenic sources were identified as fertilizers, combusted coal, and industrial waste, with phosphate fertilizer being the most significance source of F{sup -} accumulated in the soil. The mean concentration of As in the surface soil samples was 10.2 mg/kg, with the highest concentration being 35 mg/kg. The presence of high levels of As in the surface soil implies the contribution of air pollutants derived from coal combustion and the use of fertilizers. Intensive mineral weathering under oxidizing conditions produces highly alkaline water that dissolves the F{sup -} and As adsorbed on the soil, thus releasing it into the local groundwater.« less

Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands

USGS Publications Warehouse

Wolf, Kristin L.; Noe, Gregory B.; Ahn, Changwoo

2013-01-01

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

Visualization of soil structure and pore structure modifications by pioneering ground beetles (Cicindelidae) in surface sediments of an artificial catchment

NASA Astrophysics Data System (ADS)

Badorreck, Annika; Gerke, Horst H.; Weller, Ulrich; Vontobel, Peter

2010-05-01

An artificial catchment was constructed to study initial soil and ecosystem development. As a key process, the pore structure dynamics in the soil at the surface strongly influences erosion, infiltration, matter dynamics, and vegetation establishment. Little is known, however, about the first macropore formation in the very early stage. This presentation focuses on observations of soil pore geometry and its effect on water flow at the surface comparing samples from three sites in the catchment and in an adjacent "younger" site composed of comparable sediments. The surface soil was sampled in cylindrical plastic rings (10 cm³) down to 2 cm depth in three replicates each site and six where caves from pioneering ground-dwelling beetles Cicindelidae were found. The samples were scanned with micro-X-ray computed tomography (at UFZ-Halle, Germany) with a resolution of 0.084 mm. The infiltration dynamics were visualized with neutronradiography (at Paul-Scherer-Institute, Switzerland) on slab-type soil samples in 2D. The micro-tomographies exhibit formation of surface sealing whose thickness and intensity vary with silt and clay content. The CT images show several coarser- and finer-textured micro-layers at the sample surfaces that were formed as a consequence of repeated washing in of finer particles in underlying coarser sediment. In micro-depressions, the uppermost layers consist of sorted fine sand and silt due to wind erosion. Similar as for desert pavements, a vesicular pore structure developed in these sediments on top, but also scattered in fine sand- and silt-enriched micro-layers. The ground-dwelling activity of Cicindelidae beetles greatly modifies the soil structure through forming caves in the first centimetres of the soil. Older collapsed caves, which form isolated pores within mixed zones, were also found. The infiltration rates were severely affected both, by surface crusts and activity of ground-dwelling beetles. The observations demonstrate relatively high abiotic and biotic dynamics of soil pore structure in the soil surface even during the very early development stages. The structure formation has potentially great effects on changing runoff and infiltration by forming sealing layers or preferential flow paths.

Organochlorine pesticides and polychlorinated biphenyls in surface soils of Novi Sad and bank sediment of the Danube River.

PubMed

Skrbic, Biljana; Cvejanov, Jelena; Durisic-Mladenovic, Natasa

2007-01-01

The contents of 16 organochlorine pesticides (OCPs) and six so-called indicator polychlorinated biphenyls (PCBs) were determined in the surface zone (0-5 cm) of soil and sediment samples, taken from different locations in the city of Novi Sad, capitol of Vojvodina Province (North of the Serbia) covering residential and commercial area, recreational and arable zone. The total organochlorine pesticides concentration in soil varied from 2.63 to 31.78 ng g(-1) dry weight, while the level in sediment was 10.35 ng g(-1) dry weight. Maximum content of identified individual organochlorine pesticide in soil samples was 10.40 ng g(-1) dry weight for p, p-DDE in the market garden and 6.31 ng g(-1) dry weight for p, p'-DDT in sediment of the Danube River, although their application is restricted in Serbia. Some of investigated PCBs were identified only in the soil samples from a park-school backyard in the city downtown (0.32 ng g(-1) dry weight) and market garden (0.22 ng g(-1) dry weight), and also in sediment sample from left bank of the Danube River (0.41 ng g(-1) dry weight). Data of the OCPs and PCBs present in this study were compared with the ones found for soils and river sediments throughout the world, and with limit values set by soil and sediment quality guidelines. Also, correlation between the levels of certain pesticides and soil characteristics (organic matter, pH and clay content) was investigated.

Erosion: Irrigation-induced

USDA-ARS?s Scientific Manuscript database

Soil can be eroded by sprinkler or surface irrigation. Once sprinkler droplet kinetic energy detaches soil, overland flow transports the sediment downslope and off-site. Protecting the soil surface, increasing sprinkler wetted diameters, and tilling to increase infiltration and thereby lessen overla...

Challenges in soil erosion research and prediction model development

USDA-ARS?s Scientific Manuscript database

Quantification of soil erosion has been traditionally considered as a surface hydrologic process with equations for soil detachment and sediment transport derived from the mechanics and hydraulics of the rainfall and surface flow. Under the current erosion modeling framework, the soil has a constant...

Soil fertility in deserts: a review on the influence of biological soil crusts and the effect of soil surface disturbance on nutrient inputs and losses

USGS Publications Warehouse

Reynolds, R.; Phillips, S.; Duniway, M.; Belnap, J.

2003-01-01

Sources of desert soil fertility include parent material weathering, aeolian deposition, and on-site C and N biotic fixation. While parent materials provide many soil nutrients, aeolian deposition can provide up to 75% of plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. Soil surface biota are often sticky, and help retain wind-deposited nutrients, as well as providing much of the N inputs. Carbon inputs are from both plants and soil surface biota. Most desert soils are protected by cyanobacterial-lichen-moss soil crusts, chemical crusts and/or desert pavement. Experimental disturbances applied in US deserts show disruption of soil surfaces result in decreased N and C inputs from soil biota by up to 100%. The ability to glue aeolian deposits in place is compromised, and underlying soils are exposed to erosion. The ability to withstand wind increases with biological and physical soil crust development. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produce up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Soil fines and flora are often concentrated in the top 3 mm of the soil surface. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, disturbances of desert soil surfaces can both reduce fertility inputs and accelerate fertility losses.

Sedimentation Time Measurements of Soil Particles by Light Scattering and Determination of Chromium, Lead, and Iron in Soil Samples via ICP

ERIC Educational Resources Information Center

Todebush, Patricia Metthe; Geiger, Franz M.

2005-01-01

The study of soil samples, using light scattering and Inductively Coupled Plasma spectrometry (ICP) to determine colloid sedimentation rates and the quantity of chromium, lead, and iron in the sample is described. It shows the physical and chemical behavior of solid components in soil, and how such pollutant binding colloid surfaces directly…

Deposition and regional distribution of HCHs and p,p'-DDX in the western and southern Tibetan Plateau: records from a lake sediment core and the surface soils.

PubMed

Tao, Yu-Qiang; Lei, Guo-Liang; Xue, Bin; Yao, Shu-Chun; Pu, Yang; Zhang, Hu-Cai

2014-02-01

Tibetan Plateau is the world's highest plateau, which provides a unique location for the investigation of global fractionation of organochlorine pesticides (OCPs). In this study, deposition and regional distribution of HCHs and p,p'-DDX in the western and southern Tibetan Plateau were investigated by the records from a sediment core of Lake Zige Tangco and 24 surface soils. Concentration of ΣHCHs in the surface soils of the western Tibetan Plateau was much higher than that of the southern part. Maximum fluxes of α-, β-, and δ-HCH in the sediment core were 9.0, 222, and 21 pg cm(-2) year(-1), respectively, which appeared in the mid-1960s. Significant correlations were observed between concentrations of α- and β-HCH in both the surface soils and the sediment core. Concentrations of both α- and β-HCH increased with the inverse of the average annual temperature of these sites. γ-HCH became the dominant isomer of HCHs after the late 1970s, and reached the maximum flux of 160 pg cm(-2) year(-1) in the early 1990s. There were no significant correlations between concentrations of γ-HCH and the other isomers in both the surface soils and the sediment core. The results suggested that there was input of Lindane at scattered sites in this area. In contrast to ΣHCHs, concentration of Σp,p'-DDX in the surface soils of the southern part was much higher than that of the western part. Maximum flux of Σp,p'-DDX was 44 pg cm(-2) year(-1), which appeared in the mid-1960s. Local emission of p,p'-DDT was found at scattered sites. This study provides novel data and knowledge for the OCPs in the western and southern Tibetan Plateau, which will help understand the global fractionation of OCPs in remote alpine regions.

Sediment and solute transport in a mountainous watershed in Valle del Cauca, Colombia

NASA Astrophysics Data System (ADS)

Guzman, C. D.; Castro, A.; Morales, A.; Hoyos, F.; Moreno, P.; Steenhuis, T. S.

2014-12-01

A main goal of this study was to improve prediction of sediment and solute transport using soil surface and soil nutrient changes, based on field measurements, within small watersheds receiving conservation measures. Sediment samples and solute concentrations were measured from two streams in the southwestern region of the Colombian Andes. Two modeling approaches for stream discharge and sediment transport predicted were used with one of these being used for nutrient transport prediction. These streams are a part of a recent initiative from a water fund established by Asobolo, Asocaña, and Cenicaña in collaboration with the Natural Capital Project to improve conservation efforts and monitor their effects. On-site soil depth changes, groundwater depth measurements, and soil nutrient concentrations were also monitored to provide more information about changes within this mountainous watershed during one part of the yearly rainy season. This information is being coupled closely with the outlet sediment concentration and solute concentration patterns to discern correlations. Lateral transects in the upper, middle, and lower part of the hillsides in the Aguaclara watershed of the Rio Bolo watershed network showed differences in soil nutrient status and soil surface depth changes. The model based on semi-distributed hydrology was able to reproduce discharge and sediment transport rates as well as the initially used model indicating available options for comparison of conservation changes in the future.

Interrill sediment enrichment of P and C from organically and conventionally farmed silty loams

NASA Astrophysics Data System (ADS)

Kuhn, N. J.

2012-04-01

Globally, between 0.57 and 1.33 Pg of soil organic carbon (SOC) may be affected by interrill processes. Also, a significant amount of phosphorus (P) is contained in the surface soil layer transformed by raindrop impact, runoff and crust formation. In the EU, the P content of a crusted (2 mm) surface layer corresponds to 4 to 40 kg ha-1 of P on arable land (1.094 mil km2). Therefore, the role of interrill processes for nutrient cycling and the global carbon cycle requires close attention. Interrill erosion is a complex phenomen on involving the detachment, transport and deposition of soil particles by raindrop impacted flow. Resistance to interrill erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to interrill erosion occur during storms as a result of changes in surface roughness, cohesion and particle size. As a consequence, erosion on interrill areas is selective, moving the most easily detached small and/or light soil particles. This leads to the enrichment of clay, phosphorous (P)and carbon (C). Such enrichment in interrill sediment is well documented, however, the role of interrill erosion processes on the enrichment remains unclear. Enrichment of P and C in interrill sediment is attributed to the preferential erosion of the smaller, lighter soil particles. In this study, the P and organic C content of sediment generated from two Devon silts under conventional (CS) and organic (OS) soil management were examined. Artificial rainfall was applied to the soils using two rainfall scenarios of differing intensity and kinetic energy to determine the effects on the P and C enrichment in interrill sediment. Interrill soil erodibility was lower on the OS, irrespective of rainfall intensity. Sediment from both soils showed a significant enrichment in P and C compared to the bulk soil. However, sediment from the OS displayed a much greater degree of P enrichment. This shows that the net P export from organically farmed soils is not reduced by a similar degree than soil erosion compared to conventional soil management. The enrichment of P and C in the interrill sediment was not directly related to SOC, P content of the soil and soil interrill erodibility. A comparison of soil and sediment properties indicates that crusting, P and C content as well as density and size of eroded aggregate fragments control P and C enrichment. Due to complex and dynamic interactions between P, SOC and interrill erosional processes, the nutrient and C status of sediments cannot be predicted based on soil P content, SOC or interrill erodibility alone. Clearly, further research on crust formation and the composition of fragments generated by aggregate breakdown and their transport in raindrop impacted flow under different rainfall conditions is required. Attaining this critical missing knowledge would enable a comprehensive assessment of the benefits of organic farming on nutrient budgets, off-site effects of interrill erosion and its role in the global C cycle.

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.

Results of soil, ground-water, surface-water, and streambed-sediment sampling at Air Force Plane 85, Columbus, Ohio, 1996

USGS Publications Warehouse

Parnell, J.M.

1997-01-01

The U.S. Geological Survey (USGS), in cooperation with Aeronautical Systems Center, Environmental Management Directorate, Restoration Division, prepared the Surface- and Ground- Water Monitoring Work Plan for Air Force Plant 85 (AFP 85 or Plant), Columbus, Ohio, under the Air Force Installation Restoration Program to characterize any ground-water, surface-water, and soil contamination that may exist at AFP 85. The USGS began the study in November 1996. The Plant was divided into nine sampling areas, which included some previously investi gated study sites. The investigation activities included the collection and presentation of data taken during drilling and water-quality sampling. Data collection focused on the saturated and unsatur ated zones and surface water. Twenty-three soil borings were completed. Ten monitoring wells (six existing wells and four newly constructed monitoring wells) were selected for water-quality sam pling. Surface-water and streambed-sediment sampling locations were chosen to monitor flow onto and off of the Plant. Seven sites were sampled for both surface-water and streambed-sediment quality. This report presents data on the selected inorganic and organic constituents in soil, ground water, surface water, and streambed sediments at AFP 85. The methods of data collection and anal ysis also are included. Knowledge of the geologic and hydrologic setting could aid Aeronautical Systems Center, Environmental Management Directorate, Restoration Division, and its governing regulatory agencies in future remediation studies.

Estimating persistence of brominated and chlorinated organic pollutants in air, water, soil, and sediments with the QSPR-based classification scheme.

PubMed

Puzyn, T; Haranczyk, M; Suzuki, N; Sakurai, T

2011-02-01

We have estimated degradation half-lives of both brominated and chlorinated dibenzo-p-dioxins (PBDDs and PCDDs), furans (PBDFs and PCDFs), biphenyls (PBBs and PCBs), naphthalenes (PBNs and PCNs), diphenyl ethers (PBDEs and PCDEs) as well as selected unsubstituted polycyclic aromatic hydrocarbons (PAHs) in air, surface water, surface soil, and sediments (in total of 1,431 compounds in four compartments). Next, we compared the persistence between chloro- (relatively well-studied) and bromo- (less studied) analogs. The predictions have been performed based on the quantitative structure-property relationship (QSPR) scheme with use of k-nearest neighbors (kNN) classifier and the semi-quantitative system of persistence classes. The classification models utilized principal components derived from the principal component analysis of a set of 24 constitutional and quantum mechanical descriptors as input variables. Accuracies of classification (based on an external validation) were 86, 85, 87, and 75% for air, surface water, surface soil, and sediments, respectively. The persistence of all chlorinated species increased with increasing halogenation degree. In the case of brominated organic pollutants (Br-OPs), the trend was the same for air and sediments. However, we noticed that the opposite trend for persistence in surface water and soil. The results suggest that, due to high photoreactivity of C-Br chemical bonds, photolytic processes occurring in surface water and soil are able to play significant role in transforming and removing Br-OPs from these compartments. This contribution is the first attempt of classifying together Br-OPs and Cl-OPs according to their persistence, in particular, environmental compartments.

Biological soil crusts in deserts: A short review of their role in soil fertility, stabilization, and water relations

USGS Publications Warehouse

Belnap, Jayne

2003-01-01

Cyanobacteria and cyanolichens dominate most desert soil surfaces as the major component of biological soil crusts (BSC). BSCs contribute to soil fertility in many ways. BSC can increase weathering of parent materials by up to 100 times. Soil surface biota are often sticky, and help retain dust falling on the soil surface; this dust provides many plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. BSCs also provide roughened soil surfaces that slow water runoff and aid in retaining seeds and organic matter. They provide inputs of newly-fixed carbon and nitrogen to soils. They are essential in stabilizing soil surfaces by linking soil particles together with filamentous sheaths, enabling soils to resist both water and wind erosion. These same sheaths are important in keeping soil nutrients from becoming bound into plant-unavailable forms. Experimental disturbances applied in US deserts show soil surface impacts decrease N and C inputs from soil biota by up to 100%. The ability to hold aeolian deposits in place is compromised, and underlying soils are exposed to erosion. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produces up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, reduction in the cover of cyanophytes in desert soils can both reduce fertility inputs and accelerate fertility losses.

Wind erodibility of soils at Fort Irwin, California (Mojave Desert), USA, before and after trampling disturbance: Implications for land management

USGS Publications Warehouse

Belnap, J.; Phillips, S.L.; Herrick, J.E.; Johansen, J.R.

2007-01-01

Recently disturbed and 'control' (i.e. less recently disturbed) soils in the Mojave Desert were compared for their vulnerability to wind erosion, using a wind tunnel, before and after being experimentally trampled. Before trampling, control sites had greater cyanobacterial biomass, soil surface stability, threshold friction velocities (TFV, i.e. the wind speed required to move soil particles), and sediment yield than sites that had been more recently disturbed by military manoeuvres. After trampling, all sites showed a large drop in TFVs and a concomitant increase in sediment yield. Simple correlation analyses showed that the decline in TFVs and the rise in sediment yield were significantly related to cyanobacterial biomass (as indicated by soil chlorophyll a). However, chlorophyll a amounts were very low compared to chlorophyll a amounts found at cooler desert sites, where chlorophyll a is often the most important factor in determining TFV and sediment yield. Multiple regression analyses showed that other factors at Fort Irwin were more important than cyanobacterial biomass in determining the overall site susceptibility to wind erosion. These factors included soil texture (especially the fine, medium and coarse sand fractions), rock cover, and the inherent stability of the soil (as indicated by subsurface soil stability tests). Thus, our results indicate that there is a threshold of biomass below which cyanobacterial crusts are not the dominant factor in soil vulnerability to wind erosion. Most undisturbed soil surfaces in the Mojave Desert region produce very little sediment, but even moderate disturbance increases soil loss from these sites. Because current weathering rates and dust inputs are very low, soil formation rates are low as well. Therefore, soil loss in this region is likely to have long-term effects.

Soil Organic Matter Erosion by Interrill Processes from Organically and Conventionally farmed Devon Soil

NASA Astrophysics Data System (ADS)

Armstrong, E.; Ling, A.; Kuhn, N. J.

2012-04-01

Globally, between 0.57 and 1.33 Pg of soil organic carbon (SOC) may be affected by interrill processes. Also, a significant amount of phosphorus (P) is contained in the surface soil layer transformed by raindrop impact, runoff and crust formation. In the EU, the P content of a crusted (2 mm) surface layer corresponds to 4 to 40 kg ha-1 of P on arable land (1.094 mil km2). Therefore, the role of interrill processes for nutrient cycling and the global carbon cycle requires close attention. Interrill erosion is a complex phenomenon involving the detachment, transport and deposition of soil particles by raindrop impacted flow. Resistance to interrill erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to interrill erosion occur during storms as a result of changes in surface roughness, cohesion and particle size. As a consequence, erosion on interrill areas is selective, moving the most easily detached small and/or light soil particles. This leads to the enrichment of clay, phosphorous (P) and carbon (C). Such enrichment in interrill sediment is well documented, however, the role of interrill erosion processes on the enrichment remains unclear. Enrichment of P and C in interrill sediment is attributed to the preferential erosion of the smaller, lighter soil particles. In this study, the P and organic C content of sediment generated from two Devon silts under conventional (CS) and organic (OS) soil management were examined. Artificial rainfall was applied to the soils using two rainfall scenarios of differing intensity and kinetic energy to determine the effects on the P and C enrichment in interrill sediment. Interrill soil erodibility was lower on the OS, irrespective of rainfall intensity. Sediment from both soils showed a significant enrichment in P and C compared to the bulk soil. However, sediment from the OS displayed a much greater degree of P enrichment. This shows that the net P export from organically farmed soils is not reduced by a similar degree than soil erosion compared to conventional soil management. The enrichment of P and C in the interrill sediment was not directly related to SOC, P content of the soil and soil interrill erodibility. A comparison of soil and sediment properties indicates that crusting, P and C content as well as density and size of eroded aggregate fragments control P and C enrichment. Due to complex and dynamic interactions between P, SOC and interrill erosional processes, the nutrient and C status of sediments cannot be predicted based on soil P content, SOC or interrill erodibility alone. Clearly, further research on crust formation and the composition of fragments generated by aggregate breakdown and their transport in raindrop impacted flow under different rainfall conditions is required. Attaining this critical missing knowledge would enable a comprehensive assessment of the benefits of organic farming on nutrient budgets, off-site effects of interrill erosion and its role in the global C cycle.

75 FR 55479 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-13

... surface media (soil, surface water, sediment) and structures (both former structures that have been... . SUPPLEMENTARY INFORMATION: The portion of the site to be deleted from the NPL is the surface media (soil...

Effect of stone coverage on soil erosion

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Heng, B. P.; Brovelli, A.; Sander, G. C.; Parlange, J.

2010-12-01

Soil surface coverage has a significant impact on water infiltration, runoff and soil erosion yields. In particular, surface stones protect the soils from raindrop detachment, they retard the overland flow therefore decreasing its sediment transport capacity, and they prevent surface sealing. Several physical and environmental factors control to what extent stones on the soil surface modify the erosion rates and the related hydrological response. Among the most important factors are the moisture content of the topsoil, stone size, emplacement, coverage density and soil texture. Owing to the different inter-related processes, there is ambiguity concerning the quantitative effect of stones, and process-based understanding is limited. Experiments were performed (i) to quantify how stone features affect sediment yields, (ii) to understand the local effect of isolated surface stones, that is, the changes of the soil particle size distribution in the vicinity of a stone and (iii) to determine how stones attenuate the development of surface sealing and in turn how this affects the local infiltration rate. A series of experiments using the EPFL 6-m × 2-m erosion flume were conducted at different rainfall intensities (28 and 74 mm h-1) and stone coverage (20 and 40%). The total sediment concentration, the concentration of the individual size classes and the flow discharge were measured. In order to analyze the measurements, the Hairsine and Rose (HR) erosion model was adapted to account for the shielding effect of the stone cover. This was done by suitably adjusting the parameters based on the area not covered by stones. It was found that the modified HR model predictions agreed well with the measured sediment concentrations especially for the long time behavior. Changes in the bulk density of the topsoil due to raindrop-induced compaction with and without stone protection revealed that the stones protect the upper soil surface against the structural seals resulting in negligible changes in the bulk density during the erosion event. Since the main process contributing to surface sealing development is the compaction due to the raindrop kinetic energy and associated physico-chemical changes, the protection provided by the stone cover is consistent with the area-averaging approach used in applying the HR model.

Estimation of small-scale soil erosion in laboratory experiments with Structure from Motion photogrammetry

NASA Astrophysics Data System (ADS)

Balaguer-Puig, Matilde; Marqués-Mateu, Ángel; Lerma, José Luis; Ibáñez-Asensio, Sara

2017-10-01

The quantitative estimation of changes in terrain surfaces caused by water erosion can be carried out from precise descriptions of surfaces given by means of digital elevation models (DEMs). Some stages of water erosion research efforts are conducted in the laboratory using rainfall simulators and soil boxes with areas less than 1 m2. Under these conditions, erosive processes can lead to very small surface variations and high precision DEMs are needed to account for differences measured in millimetres. In this paper, we used a photogrammetric Structure from Motion (SfM) technique to build DEMs of a 0.5 m2 soil box to monitor several simulated rainfall episodes in the laboratory. The technique of DEM of difference (DoD) was then applied using GIS tools to compute estimates of volumetric changes between each pair of rainfall episodes. The aim was to classify the soil surface into three classes: erosion areas, deposition areas, and unchanged or neutral areas, and quantify the volume of soil that was eroded and deposited. We used a thresholding criterion of changes based on the estimated error of the difference of DEMs, which in turn was obtained from the root mean square error of the individual DEMs. Experimental tests showed that the choice of different threshold values in the DoD can lead to volume differences as large as 60% when compared to the direct volumetric difference. It turns out that the choice of that threshold was a key point in this method. In parallel to photogrammetric work, we collected sediments from each rain episode and obtained a series of corresponding measured sediment yields. The comparison between computed and measured sediment yields was significantly correlated, especially when considering the accumulated value of the five simulations. The computed sediment yield was 13% greater than the measured sediment yield. The procedure presented in this paper proved to be suitable for the determination of sediment yields in rainfall-driven soil erosion experiments conducted in the laboratory.

Simulation of soil loss processes based on rainfall runoff and the time factor of governance in the Jialing River Watershed, China.

PubMed

Wu, Lei; Long, Tian-Yu; Liu, Xia; Mmereki, Daniel

2012-06-01

Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly changed the surface appearance of the Jialing River Watershed (JRW), and it had made the environments of the watershed sediment yield and sediment transport change significantly. In this research, the Revised Universal Soil Loss Equation was selected and used to predict the annual average amount of soil erosion for the special water and sediment environments in the JRW after the implementation of the "Long Control" Project, and then the rainfall-runoff modulus and the time factor of governance were both considered as dynamic factors, the dynamic sediment transport model was built for soil erosion monitoring and forecasting based on the average sediment yield model. According to the dynamic model, the spatial and temporal distribution of soil erosion amount and sediment transport amount of the JRW from 1990 to 2007 was simulated using geographic information system (GIS) technology and space-grid algorithm. Simulation results showed that the average relative error of sediment transport was less than 10% except for the extreme hydrological year. The relationship between water and sediment from 1990 to 2007 showed that sediment interception effects of the soil and water conservation projects were obvious: the annual average sediment discharge reduced from 145.3 to 35 million tons, the decrement of sediment amount was about 111 million tons, and decreasing amplitude was 76%; the sediment concentration was also decreased from 2.01 to 0.578 kg/m(3). These data are of great significance for the prediction and estimation of the future changing trends of sediment storage in the Three Gorges Reservoir and the particulate non-point source pollution load carried by sediment transport from watershed surface.

Pyrosequencing reveals bacteria carried in different wind-eroded sediments.

PubMed

Gardner, Terrence; Acosta-Martinez, Veronica; Calderón, Francisco J; Zobeck, Ted M; Baddock, Matthew; Van Pelt, R Scott; Senwo, Zachary; Dowd, Scot; Cox, Stephen

2012-01-01

Little is known about the microbial communities carried in wind-eroded sediments from various soil types and land management systems. The novel technique of pyrosequencing promises to expand our understanding of the microbial diversity of soils and eroded sediments because it can sequence 10 to 100 times more DNA fragments than previous techniques, providing enhanced exploration into what microbes are being lost from soil due to wind erosion. Our study evaluated the bacterial diversity of two types of wind-eroded sediments collected from three different organic-rich soils in Michigan using a portable field wind tunnel. The wind-eroded sediments evaluated were a coarse sized fraction with 66% of particles >106 μm (coarse eroded sediment) and a finer eroded sediment with 72% of particles <106 μm. Our findings suggested that (i) bacteria carried in the coarser sediment and fine dust were effective fingerprints of the source soil, although their distribution may vary depending on the soil characteristics because certain bacteria may be more protected in soil surfaces than others; (ii) coarser wind-eroded sediment showed higher bacterial diversity than fine dust in two of the three soils evaluated; and (iii) certain bacteria were more predominant in fine dust (, , and ) than coarse sediment ( and ), revealing different locations and niches of bacteria in soil, which, depending on wind erosion processes, can have important implications on the soil sustainability and functioning. Infrared spectroscopy showed that wind erosion preferentially removes particular kinds of C from the soil that are lost via fine dust. Our study shows that eroded sediments remove the active labile organic soil particulates containing key microorganisms involved in soil biogeochemical processes, which can have a negative impact on the quality and functioning of the source soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Vertical migration of fine-grained sediments from interior to surface of seabed driven by seepage flows-`sub-bottom sediment pump action'

NASA Astrophysics Data System (ADS)

Zhang, Shaotong; Jia, Yonggang; Wen, Mingzheng; Wang, Zhenhao; Zhang, Yaqi; Zhu, Chaoqi; Li, Bowen; Liu, Xiaolei

2017-02-01

A scientific hypothesis is proposed and preliminarily verified in this paper: under the driving of seepage flows, there might be a vertical migration of fine-grained soil particles from interior to surface of seabed, which is defined as `sub-bottom sediment pump action' in this paper. Field experiments were performed twice on the intertidal flat of the Yellow River delta to study this process via both trapping the pumped materials and recording the pore pressures in the substrate. Experimental results are quite interesting as we did observe yellow slurry which is mainly composed of fine-grained soil particles appearing on the seabed surface; seepage gradients were also detected in the intertidal flat, under the action of tides and small wind waves. Preliminary conclusions are that `sediment pump' occurs when seepage force exceeds a certain threshold: firstly, it is big enough to disconnect the soil particles from the soil skeleton; secondly, the degree of seabed fluidization or bioturbation is big enough to provide preferred paths for the detached materials to migrate upwards. Then they would be firstly pumped from interior to the surface of seabed and then easily re-suspended into overlying water column. Influential factors of `sediment pump' are determined as hydrodynamics (wave energy), degree of consolidation, index of bioturbation (permeability) and content of fine-grained materials (sedimentary age). This new perspective of `sediment pump' may provide some implications for the mechanism interpretation of several unclear geological phenomena in the Yellow River delta area.

Response of two semiarid grasslands to a second fire application

Treesearch

Carleton S. White; Rosemary L. Pendleton; Burton K. Pendleton

2006-01-01

Prescribed fire was used in two semiarid grasslands to reduce shrub cover, promote grass production, and reduce erosional loss that represents a potential non­point-source of sediment to degrade water quality. This study measured transported soil sediment, dynamics in soil surface microtopography, cover of the woody shrub, grass, and bare ground cover classes, and soil...

Natural attenuation of Fukushima-derived radiocesium in soils due to its vertical and lateral migration.

PubMed

Konoplev, A; Golosov, V; Wakiyama, Y; Takase, T; Yoschenko, V; Yoshihara, T; Parenyuk, O; Cresswell, A; Ivanov, M; Carradine, M; Nanba, K; Onda, Y

2018-06-01

Processes of vertical and lateral migration lead to gradual reduction in contamination of catchment soil, particularly its top layer. The reduction can be considered as natural attenuation. This, in turn, results in a gradual decrease of radiocesium activity concentrations in the surface runoff and river water, in both dissolved and particulate forms. The purpose of this research is to study the dynamics of Fukushima-derived radiocesium in undisturbed soils and floodplain deposits exposed to erosion and sedimentation during floods. Combined observations of radiocesium vertical distribution in soil and sediment deposition on artificial lawn-grass mats on the Niida River floodplain allowed us to estimate both annual mean sediment accumulation rates and maximum sedimentation rates corresponding to an extreme flood event during Tropical Storm Etau, 6-11 September 2015. Dose rates were reduced considerably for floodplain sections with high sedimentation because the top soil layer with high radionuclide contamination was eroded and/or buried under cleaner fresh sediments produced mostly due to bank erosion and sediments movements. Rate constants of natural attenuation on the sites of the Takase River and floodplain of Niida River was found to be in range 0.2-0.4 year -1 . For the site in the lower reach of the Niida River, collimated shield dose readings from soil surfaces slightly increased during the period of observation from February to July 2016. Generally, due to more precipitation, steeper slopes, higher temperatures and increased biological activities in soils, self-purification of radioactive contamination in Fukushima associated with vertical and lateral radionuclide migration is faster than in Chernobyl. In many cases, monitored natural attenuation along with appropriate restrictions seems to be optimal option for water remediation in Fukushima contaminated areas. Copyright © 2017. Published by Elsevier Ltd.

Geomechanical Modeling of Gas Hydrate Bearing Sediments

NASA Astrophysics Data System (ADS)

Sanchez, M. J.; Gai, X., Sr.

2015-12-01

This contribution focuses on an advance geomechanical model for methane hydrate-bearing soils based on concepts of elasto-plasticity for strain hardening/softening soils and incorporates bonding and damage effects. The core of the proposed model includes: a hierarchical single surface critical state framework, sub-loading concepts for modeling the plastic strains generally observed inside the yield surface and a hydrate enhancement factor to account for the cementing effects provided by the presence of hydrates in sediments. The proposed framework has been validated against recently published experiments involving both, synthetic and natural hydrate soils, as well as different sediments types (i.e., different hydrate saturations, and different hydrates morphologies) and confinement conditions. The performance of the model in these different case studies was very satisfactory.

Sources of suspended sediment in the Lower Roanoke River, NC

NASA Astrophysics Data System (ADS)

Jalowska, A. M.; McKee, B. A.; Rodriguez, A. B.; Laceby, J. P.

2015-12-01

The Lower Roanoke River, NC, extends 220 km from the fall line to the bayhead delta front in the Albemarle Sound. The Lower Roanoke is almost completely disconnected from the upper reaches by a series of dams, with the furthest downstream dam located at the fall line. The dams effectively restrict the suspended sediment delivery from headwaters, making soils and sediments from the Lower Roanoke River basin, the sole source of suspended sediment. In flow-regulated rivers, bank erosion, especially mass wasting, is the major contributor to the suspended matter. Additional sources of the suspended sediment considered in this study are river channel, surface soils, floodplain surface sediments, and erosion of the delta front and prodelta. Here, we examine spatial and temporal variations in those sources. This study combined the use of flow and grain size data with a sediment fingerprinting method, to examine the contribution of surface and subsurface sediments to the observed suspended sediment load along the Lower Roanoke River. The fingerprinting method utilized radionuclide tracers 210Pb (natural atmospheric fallout), and 137Cs (produced by thermonuclear bomb testing). The contributions of surface and subsurface sources to the suspended sediment were calculated with 95% confidence intervals using a Monte-Carlo numerical mixing model. Our results show that with decreasing river slope and changing hydrography along the river, the contribution of surface sediments increases and becomes a main source of sediments in the Roanoke bayhead delta. At the river mouth, the surface sediment contribution decreases and is replaced by sediments eroded from the delta front and prodelta. The area of high surface sediment contribution is within the middle and upper parts of the delta, which are considered net depositional. Our study demonstrates that floodplains, often regarded to be a sediment sink, are also a sediment source, and they should be factored into sediment, carbon and nutrient budgets.

Development of a Distributed Source Containment Transport, Transformation, and Fate (CTT&F) Sub-Model for Military Installations

DTIC Science & Technology

2007-08-01

includes soil erodibility terms from the Universal Soil Lass Equation ( USLE ) for estimating the overland sediment transport capacity (for both the x and y...q = unit flow rate of water = va h [L2/T] vc = critical velocity for erosion overland [L/T] K = USLE soil erodibility factor C = USLE soil ...cover factor P = USLE soil management practice factor Be = width of eroding surface in flow direction [L]. In channels, sediment particles can be

Prediction of Mass Wasting, Erosion, and Sediment Transport With the Distributed Hydrology-Soil-Vegetation Model

NASA Astrophysics Data System (ADS)

Doten, C. O.; Lanini, J. S.; Bowling, L. C.; Lettenmaier, D. P.

2004-12-01

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment module linked to the Distributed Hydrology-Soil-Vegetation Model (DHSVM). The DHSVM sediment module represents the main sources of sediment generation in forested environments: mass wasting, hillslope erosion and road surface erosion. It produces failures based on a factor-of-safety analysis with the infinite slope model through use of stochastically generated soil and vegetation parameters. Failed material is routed downslope with a rule-based scheme that determines sediment delivery to streams. Sediment from hillslopes and road surfaces is also transported to the channel network. Basin sediment yield is predicted with a simple channel sediment routing scheme. The model was applied to the Rainy Creek catchment, a tributary of the Wenatchee River which drains the east slopes of the Cascade Mountains, and Hard and Ware Creeks on the west slopes of the Cascades. In these initial applications, the model produced plausible sediment yield and ratios of landsliding and surface erosion , when compared to published rates for similar catchments in the Pacific Northwest. We have also used the model to examine the implications of fires and logging road removal on sediment generation in the Rainy Creek catchment. Generally, in absolute value, the predicted changes (increased sediment generation) following fires, which are primarily associated with increased slope failures, are much larger than the modest changes (reductions in sediment yield) associated with road obliteration, although the small sensitivity to forest road obliteration may be due in part to the relatively low road density in the Rainy Creek catchment, and to mechanisms, such as culvert failure, that are not represented in the model.

Soil aggregate stability and size-selective sediment transport with surface runoff as affected by organic residue amendment.

PubMed

Shi, Pu; Arter, Christian; Liu, Xingyu; Keller, Martin; Schulin, Rainer

2017-12-31

Aggregate breakdown influences the availability of soil particles for size-selective sediment transport with surface runoff during erosive rainfall events. Organic matter management is known to affect aggregate stability against breakdown, but little is known about how this translates into rainfall-induced aggregate fragmentation and sediment transport under field conditions. In this study, we performed field experiments in which artificial rainfall was applied after pre-wetting on three pairs of arable soil plots (1.5×0.75m) six weeks after incorporating a mixture of grass and wheat straw into the topsoil of one plot in each pair (OI treatment) but not on the other plot (NI treatment). Artificial rainfall was applied for approximately 2h on each pair at an intensity of 49.1mmh -1 . In both treatments, discharge and sediment concentration in the discharge were correlated and followed a similar temporal pattern after the onset of surface runoff: After a sharp increase at the beginning both approached a steady state. But the onset of runoff was more delayed on the OI plots, and the discharge and sediment concentration were in average only roughly half as high on the OI as on the NI plots. With increasing discharge the fraction of coarse sediment increased. This relationship did not differ between the two treatments. Thus, due to the lower discharge, the fraction of fine particles in the exported sediment was larger in the runoff from the OI plots than from the NI plots. The later runoff onset and lower discharge rate was related to a higher initial aggregate stability on the OI plots. Terrestrial laser scanning proved to be a very valuable method to map changes in the micro-topography of the soil surfaces. It revealed a much less profound decrease in surface roughness on the OI than on the NI plots. Copyright © 2017 Elsevier B.V. All rights reserved.

Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

USGS Publications Warehouse

Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

2017-01-01

Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

Potential fate of SOC eroded from natural crusted soil surface under simulated wind driven storm

NASA Astrophysics Data System (ADS)

Xiao, Liangang; Fister, Wolfgang; Greenwood, Philip; Hu, Yaxian; Kuhn, Nikolaus J.

2016-04-01

Improving the assessment of the impact of soil erosion on carbon (C) cycling requires a better understanding of the redistribution of eroded sediment and associated soil organic carbon (SOC) across agricultural landscapes. Recent studies conducted on dry-sieved aggregates in the laboratory demonstrated that aggregation can profoundly skew SOC redistribution and its subsequent fate by accelerating settling velocities of aggregated sediment compared to mineral grains, which in turn can increase SOC mineralization into greenhouse gases. However, the erodibility of the soil in the field is more variable than in the laboratory due to tillage, crus formation, drying-wetting and freeze-thaw cycles, and biological effects. This study aimed to investigate the potential fate of the SOC eroded from naturally developed soil surface and to compare the observations with those made in the laboratory. Simulated, short, high intensity wind driven storms were conducted on a crusted loam in the field. The sediments were fractionated with a settling tube according to their potential transport distances. The soil mass, SOC concentration and cumulative 80-day CO2 emission of each fraction were identified. The results show: 1) 53% of eroded sediment and 62% of eroded SOC from the natural surface in the field would be deposited across landscapes, which is six times and three times higher compared to that implied by mineral grains, respectively; 2) the preferential deposition of SOC-rich fast-settling sediment potentially releases approximately 50% more CO2 than the same layer of the non-eroded soil; 3) the respiration of the slow-settling fraction that is potentially transported to the aquatic systems was much more active compared to the other fractions and the bulk soil. Our results confirm in general the conclusions drawn from laboratory and thus demonstrate that aggregation can affect the redistribution of sediment associated SOC under field conditions, including an increase in emissions compared to bulk soil. Overall, this confirms that terrestrial SOC redistribution and the mineralization play an important role in erosion induced C cycling, with major uncertainties to be addressed.

Suspended sediment source areas and future climate impact on soil erosion and sediment yield in a New York City water supply watershed, USA

NASA Astrophysics Data System (ADS)

Mukundan, Rajith; Pradhanang, Soni M.; Schneiderman, Elliot M.; Pierson, Donald C.; Anandhi, Aavudai; Zion, Mark S.; Matonse, Adão H.; Lounsbury, David G.; Steenhuis, Tammo S.

2013-02-01

High suspended sediment loads and the resulting turbidity can impact the use of surface waters for water supply and other designated uses. Changes in fluvial sediment loads influence material fluxes, aquatic geochemistry, water quality, channel morphology, and aquatic habitats. Therefore, quantifying spatial and temporal patterns in sediment loads is important both for understanding and predicting soil erosion and sediment transport processes as well as watershed-scale management of sediment and associated pollutants. A case study from the 891 km2 Cannonsville watershed, one of the major watersheds in the New York City water supply system is presented. The objective of this study was to apply Soil and Water Assessment Tool-Water Balance (SWAT-WB), a physically based semi-distributed model to identify suspended sediment generating source areas under current conditions and to simulate potential climate change impacts on soil erosion and suspended sediment yield in the study watershed for a set of future climate scenarios representative of the period 2081-2100. Future scenarios developed using nine global climate model (GCM) simulations indicate a sharp increase in the annual rates of soil erosion although a similar result in sediment yield at the watershed outlet was not evident. Future climate related changes in soil erosion and sediment yield appeared more significant in the winter due to a shift in the timing of snowmelt and also due to a decrease in the proportion of precipitation received as snow. Although an increase in future summer precipitation was predicted, soil erosion and sediment yield appeared to decrease owing to an increase in soil moisture deficit and a decrease in water yield due to increased evapotranspiration.

Radionuclides deposition and fine sediment transport in a forested watershed, central Japan

NASA Astrophysics Data System (ADS)

Nam, S.; Gomi, T.; Kato, H.; Tesfaye, T.; Onda, Y.

2011-12-01

We investigated radionuclides deposition and fine sediment transport in a 13 ha headwater watershed, Tochigi prefecture, located in 98.94 km north of Tokyo. The study site was within Karasawa experimental forest, Tokyo University of Agriculture and Technology. We conducted fingerprinting approach, based on the activities of fallout radionuclides, including caesium-134 (Cs-134) caesium-137 (Cs-137) and excess lead-210 (Pb-210ex). For indentifying specific sources of fine sediment, we sampled tree, soil on forested floor, soil on logging road surface, stream bed and stream banks. We investigated the radionuclides (i.e., as Cs-134, Cs-137 and Pb-210ex) deposition on tree after accident of nuclear power plants on March 11, 2011. We sampled fruits, leaves, branches, stems, barks on Japanese cedar (Sugi) and Japanese cypress (Hinoki). To analyze the samples, gammaray spectrometry was performed at a laboratory at the University of Tsukuba (Tsukuba City, Japan) using n-type coaxial low-energy HPGe gamma detectors (EGC-200-R and EGC25-195-R of EURYSIS Co., Lingolsheim, France) coupled with a multichannel analyzer. We also collected soil samples under the forest canopy in various soil depths from 2, 5, 10, 20, 30 cm along transect of hillslopes. Samples at forest road were collected road segments crossing on the middle section of monitoring watersheds. Fine sediment transport in the streams were collected at the outlet of 13 ha watersheds using integrated suspended sediment samplers. This study indicates the some portion of radio nuclide potentially remained on the tree surface. Part of the deposited radionuclides attached to soil particles and transported to the streams. Most of the fine sediment can be transported on road surface and/or near stream side (riparian zones).

Modelling high Arctic deep permafrost temperature sensitivity in Northeast Greenland based on experimental and field observations

NASA Astrophysics Data System (ADS)

Rasmussen, Laura Helene; Zhang, Wenxin; Hollesen, Jørgen; Cable, Stefanie; Hvidtfeldt Christiansen, Hanne; Jansson, Per-Erik; Elberling, Bo

2017-04-01

Permafrost affected areas in Greenland are expected to experience a marked temperature increase within decades. Most studies have considered near-surface permafrost sensitivity, whereas permafrost temperatures below the depths of zero annual amplitude is less studied despite being closely related to changes in near-surface conditions, such as changes in active layer thermal properties, soil moisture and snow depth. In this study, we measured the sensitivity of thermal conductivity (TC) to gravimetric water content (GWC) in frozen and thawed permafrost sediments from fine-sandy and gravelly deltaic and fine-sandy alluvial deposits in the Zackenberg valley, NE Greenland. We further calibrated a coupled heat and water transfer model, the "CoupModel", for one central delta sediment site with average snow depth and further forced it with meteorology from a nearby delta sediment site with a topographic snow accumulation. With the calibrated model, we simulated deep permafrost thermal dynamics in four 20-year scenarios with changes in surface temperature and active layer (AL) soil moisture: a) 3 °C warming and AL water table at 0.5 m depth; b) 3 °C warming and AL water table at 0.1 m depth; c) 6 °C warming and AL water table at 0.5 m depth and d) 6 °C warming and AL water table at 0.1 m depth. Our results indicate that frozen sediments have higher TC than thawed sediments. All sediments show a positive linear relation between TC and soil moisture when frozen, and a logarithmic one when thawed. Gravelly delta sediments were highly sensitive, but never reached above 12 % GWC, indicating a field effect of water retention capacity. Alluvial sediments are less sensitive to soil moisture than deltaic (fine and coarse) sediments, indicating the importance of unfrozen water in frozen sediment. The deltaic site with snow accumulation had 1 °C higher mean annual ground temperature than the average snow depth site. Permafrost temperature at the depth of 18 m increased with 1.5 °C and 3.5 °C in the scenarios with 3 °C and 6 °C warming, respectively. Increasing the soil moisture had no important additional effect to warming, although an increase in thermal offset was indicated. We conclude that below-ground sediment properties affect the sensitivity of TC to GWC, that surface temperature changes can influence the deep permafrost within a short time scale, and that differences in snow depth affect surface temperatures. Sediment type and the type of precipitation should thus be considered when estimating future High Arctic deep permafrost sensitivity.

[Runoff loss of soil mineral nitrogen and its relationship with grass coverage on Loess slope land].

PubMed

Zhang, Yali; Li, Huai'en; Zhang, Xingchang; Xiao, Bo

2006-12-01

In a simulated rainfall experiment on Loess slope land, this paper determined the rainfall, surface runoff and the effective depth of interaction (EDI) between rainfall and soil mineral nitrogen, and studied the effects of grass coverage on the EDI and the runoff loss of soil mineral nitrogen. The results showed that with the increase of EDI, soil nitrogen in deeper layers could be released into surface runoff through dissolution and desorption. The higher the grass coverage, the deeper the EDI was. Grass coverage promoted the interaction between surface runoff and surface soil. On the slope land with 60%, 80% and 100% of grass coverage, the mean content of runoff mineral nitrogen increased by 34.52%, 32.67% and 6.00%, while surface runoff decreased by 4.72%, 9.84% and 12.89%, and eroded sediment decreased by 83.55%, 87.11% and 89.01%, respectively, compared with bare slope land. The total runoff loss of soil mineral nitrogen on the lands with 60%, 80%, and 100% of grass coverage was 95.73%, 109.04%, and 84.05% of that on bare land, respectively. Grass cover had dual effects on the surface runoff of soil mineral nitrogen. On one hand, it enhanced the influx of soil mineral nitrogen to surface runoff, and on the other hand, it markedly decreased the runoff, resulting in the decrease of soil mineral nitrogen loss through runoff and sediment. These two distinct factors codetermined the total runoff loss of soil mineral nitrogen.

Surface runoff and soil erosion by difference of surface cover characteristics using by an oscillating rainfall simulator

NASA Astrophysics Data System (ADS)

Kim, J. K.; Kim, M. S.; Yang, D. Y.

2017-12-01

Sediment transfer within hill slope can be changed by the hydrologic characteristics of surface material on hill slope. To better understand sediment transfer of the past and future related to climate changes, studies for the changes of soil erosion due to hydrological characteristics changes by surface materials on hill slope are needed. To do so, on-situ rainfall simulating test was conducted on three different surface conditions, i.e. well covered with litter layer condition (a), undisturbed bare condition (b), and disturbed bare condition (c) and these results from rainfall simulating test were compared with that estimated using the Limburg Soil Erosion Model (LISEM). The result from the rainfall simulating tests showed differences in the infiltration rate (a > b > c) and the highest soil erosion rate was occurred on c condition. The result from model also was similar to those from rainfall simulating tests, however, the difference from the value of soil erosion rate between two results was quite large on b and c conditions. These results implied that the difference of surface conditions could change the surface runoff and soil erosion and the result from the erosion model might significantly underestimate on bare surface conditions rather than that from rainfall simulating test.

Wind erodibility response of physical and biological crusts to rain and flooding

NASA Astrophysics Data System (ADS)

Aubault, H.; Bullard, J. E.; Strong, C. L.; Ghadiri, H.; McTainsh, G. H.

2015-12-01

Soil surface crusts are important controllers of the small-scale wind entrainment processes that occur across all dust source regions globally. The crust type influences water and wind erosion by impacting infiltration, runoff, threshold wind velocity and surface storage capacity of both water and loose erodible material. The spatial and temporal patterning of both physical and biological crusts is known to change with rainfall and flooding. However, little is known about the impact of differing water quantity (from light rainfall through to flooding) on soil crusting characteristics (strength, roughness, sediment loss). This study compares the response of two soil types (loamy sand - LS, sandy loam - SL) with and without BSCs to three different rainfall events (2mm, 8mm, 15mm). Two BSC treatments were used one that simulated a young cyanobacteria dominated crust and an older flood induced multi species biological crust. For both soil types, soil surface strength increased with increasing rainfall amount with LS having consistently higher resistance to rupture than SL. Regardless of texture, soils with BSCs were more resistant and strength did not change in response to rainfall impact. Soil loss due to wind erosion was substantially higher on bare LS (4 times higher) and SL (3 times higher) soils compared with those with BSCs. Our results also show that young biological crust (formed by the rainfall event) have reduced soil erodibility with notably greater strength, roughness and reduced sediment losses when compared to soils with physical crust. Interestingly though, the erodibility of the old BSC did not differ greatly from that of the young BSC with respect to strength, roughness and sediment loss. This raises questions regarding the rapid soil surface protection offered by young colonising cyanobacteria crusts. Further analyses exploring the role of biological soil crusts on surface response to rainfall and wind saltation impact are ongoing.

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.

Effects of Desert Dust on Nutrient Cycling in the San Juan Mountains, Colorado

NASA Astrophysics Data System (ADS)

Neff, J. C.; Farmer, L.; Painter, T. H.; Landry, C.; Reynolds, R.

2005-12-01

The San Juan Mountains of southwestern Colorado lie downwind from several major deserts and experience several dust-deposition events each year. These events appear related to storms that erode soils in the deserts of the western US and then deposit atmospheric dust from these soils during or after snowfall during large late winter and spring deposition events. To evaluate the biogeochemical implications of eolian deposition, we collected dust from distinct layers deposited into the seasonal snowpack. We also sampled soils and lake sediments in a high-elevation catchment in the San Juan Mountains. Atmospheric dust was characterized by measurements of chemical composition, Sr isotopic content and analysis of the organic and inorganic constituents of deposited eolian material. The origins of snowpack dust in the San Juans were analyzed using atmospheric tracer transport modeling. These analyses suggest that many dust events originate in southern Utah and northern Arizona, areas that have undergone substantial land use change through the 20th century and that experience severe wind erosion of soils during periodic severe droughts. Analyses of 87Sr/86Sr isotope ratios dust, soils, bedrock, and sediments suggest that eolian dust may compose as much as 90% of the near-surface soil (top 5 cm). In alpine lake sediments, Sr isotopes suggest a relatively recent (20th century) increase in the fraction of sediments derived from dust (relative to bedrock) and a similarly large contribution of dust to surface sediments. Sediment chemistry in two small alpine tarns show changes in Ca, Mg, Al, and Fe concentrations that imply increasing dust (vs. bedrock) contributions to lake sediments over the past 100-200 years. Increasing loading of Ca, Mg and P to alpine basins may have implications for alpine and sub-alpine biogeochemical cycling including water quality and plant nutrient use.

Quantifying and modeling soil erosion and sediment export from construction sites in southern California

NASA Astrophysics Data System (ADS)

Wernet, A. K.; Beighley, R. E.

2006-12-01

Soil erosion is a power process that continuously alters the Earth's landscape. Human activities, such as construction and agricultural practices, and natural events, such as forest fires and landslides, disturb the landscape and intensify erosion processes leading to sudden increases in runoff sediment concentrations and degraded stream water quality. Understanding soil erosion and sediment transport processes is of great importance to researchers and practicing engineers, who routinely use models to predict soil erosion and sediment movement for varied land use and climate change scenarios. However, existing erosion models are limited in their applicability to constructions sites which have highly variable soil conditions (density, moisture, surface roughness, and best management practices) that change often in both space and time. The goal of this research is to improve the understanding, predictive capabilities and integration of treatment methodologies for controlling soil erosion and sediment export from construction sites. This research combines modeling with field monitoring and laboratory experiments to quantify: (a) spatial and temporal distribution of soil conditions on construction sites, (b) soil erosion due to event rainfall, and (c) potential offsite discharge of sediment with and without treatment practices. Field sites in southern California were selected to monitor the effects of common construction activities (ex., cut/fill, grading, foundations, roads) on soil conditions and sediment discharge. Laboratory experiments were performed in the Soil Erosion Research Laboratory (SERL), part of the Civil and Environmental Engineering department at San Diego State University, to quantify the impact of individual factors leading to sediment export. SERL experiments utilize a 3-m by 10-m tilting soil bed with soil depths up to 1 m, slopes ranging from 0 to 50 percent, and rainfall rates up to 150 mm/hr (6 in/hr). Preliminary modeling, field and laboratory results are presented.

Soil property effects on wind erosion of organic soils

NASA Astrophysics Data System (ADS)

Zobeck, Ted M.; Baddock, Matthew; Scott Van Pelt, R.; Tatarko, John; Acosta-Martinez, Veronica

2013-09-01

Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (OM > 20%) in half or more of the upper 80 cm. Forty two states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss of crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service (NRCS) as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to understand how soil properties vary among organic soils and to calibrate and validate estimates of wind erosion of organic soils using WEPS. Soil properties and sediment flux were measured in six soils with high organic contents located in Michigan and Florida, USA. Soil properties observed included organic matter content, particle density, dry mechanical stability, dry clod stability, wind erodible material, and geometric mean diameter of the surface aggregate distribution. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils ranging from 17% to 67% organic matter. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was sampled using a Grimm optical particle size analyzer. Particle density of the saltation-sized material (>106 μm) was inversely related to OM content and varied from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. Wind erodible material and the geometric mean diameter of the surface soil were inversely related to dry clod stability. The effect of soil properties on sediment flux varied among flux types. Saltation flux was adequately predicted with simple linear regression models. Dry mechanical stability was the best single soil property linearly related to saltation flux. Simple linear models with soil properties as independent variables were not well correlated with PM10E values (mass flux). A second order polynomial equation with OM as the independent variable was found to be most highly correlated with PM10E values. These results demonstrate that variations in sediment and dust emissions can be linked to soil properties using simple models based on one or more soil properties to estimate saltation mass flux and PM10E values from organic and organic-rich soils.

Effects of post-fire salvage logging and a skid trail treatment on ground cover, soils, and sediment production in the interior western United States

Treesearch

Joseph W. Wagenbrenner; Lee H. MacDonald; Robert N. Coats; Peter R. Robichaud; Robert E. Brown

2015-01-01

Post-fire salvage logging adds another set of environmental effects to recently burned areas, and previous studies have reported varying impacts on vegetation, soil disturbance, and sediment production with limited data on the underlying processes. Our objectives were to determine how: (1) ground-based post-fire logging affects surface cover, soil water repellency,...

Development of a Coupled Hydrological/Sediment Yield Model for a Watershed at Regional Level

NASA Technical Reports Server (NTRS)

Rajbhandaril, Narayan; Crosson, William; Tsegaye, Teferi; Coleman, Tommy; Liu, Yaping; Soman, Vishwas

1998-01-01

Development of a hydrologic model for the study of environmental conservation requires a comprehensive understanding of individual-storm affecting hydrologic and sedimentologic processes. The hydrologic models that we are currently coupling are the Simulator for Hydrology and Energy Exchange at the Land Surface (SHEELS) and the Distributed Runoff Model (DRUM). SHEELS runs continuously to estimate surface energy fluxes and sub-surface soil water fluxes, while DRUM operates during and following precipitation events to predict surface runoff and peak flow through channel routing. The lateral re-distribution of surface water determined by DRUM is passed to SHEELS, which then adjusts soil water contents throughout the profile. The model SHEELS is well documented in Smith et al. (1993) and Laymen and Crosson (1995). The model DRUM is well documented in Vieux et al. (1990) and Vieux and Gauer (1994). The coupled hydrologic model, SHEELS/DRUM, does not simulate sedimentologic processes. The simulation of the sedimentologic process is important for environmental conservation planning and management. Therefore, we attempted to develop a conceptual frame work for coupling a sediment yield model with SHEELS/DRUM to estimate individual-storm sediment yield from a watershed at a regional level. The sediment yield model that will be used for this study is the Universal Soil Loss Equation (USLE) with some modifications to enable the model to predict individual-storm sediment yield. The predicted sediment yield does not include wind erosion and erosion caused by irrigation and snow melt. Units used for this study are those given by Foster et al. (1981) for SI units.

Constraints on the sources of branched GDGTs in open ocean sediments: dust transport or in situ production?

NASA Astrophysics Data System (ADS)

Weijers, J.; Schefuss, E.; Kim, J.; Sinninghe Damsté, J. S.; Schouten, S.

2012-12-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are membrane lipids synthesized by soil bacteria that, upon soil erosion, are transported by rivers to the ocean where they accumulate in the near shore sedimentary archive. The degrees of cyclisation (CBT) and methylation (MBT) of these compounds have been shown to relate to soil pH and annual mean air temperature [1]. Therefore, brGDGTs in near shore sedimentary archives can be used to estimate past continental air temperatures and enable a direct comparison of these to marine sea surface temperature estimates obtained from the same samples. In addition, brGDGT abundance relative to crenarchaeol, an isoprenoid GDGT synthesized by marine pelagic Thaumarchaeota, quantified in the branched vs. isoprenoid tetraether (BIT) index, is an indicator of the relative input of soil organic matter in near shore sediments [2]. High BIT values near river outflows testify of relative strong soil organic matter input and generally the BIT index will decrease off shore to values near 0, the marine end-member value. Even in remote open ocean sediments, however, the BIT index will rarely reach 0 as small amounts of brGDGTs are often present. The occurrence of these brGDGTs in open marine settings might be a result of i) dust input, ii) sediment dispersion from near coastal areas, or iii) in situ production in marine sediments. In order to constrain the origin of branched GDGTs in open marine sediments we analyzed i) atmospheric dust samples taken along an equatorial African coastal transect, ii) marine surface waters near and away of the Congo river outflow, iii) a series of surface sediments at and around the Congo deep sea fan, and iv) a series of open marine surface sediments from different oceans with BIT values < 0.08. Our results show that brGDGTs are present, though in relative low amounts, in dust. Their distribution resembles that of soil input as also found in the Congo deep sea fan, with MBT and CBT values that could be representative of tropical African soils. Strikingly, BIT indices are much lower than expected for soils (0.15-0.42), likely as a result of sea spray on the dust filters. Open ocean sediments, on the contrary, are typically characterized by relative high amounts of cyclopentane containing brGDGTs resulting in low CBT values ranging from -0.4 - 0.8. These values are similarly low as reported earlier in marine sediments near Svalbard [3] and in the East China Sea [4], for which in situ production was invoked. Thus, brGDGT transport by dust does seem possible, though quantities are low. Since open ocean brGDGT distributions are markedly different from those in soils and dust, the latter is most likely not a significant source. Our results indicate that production of brGDGTs in ocean sediments, though in relative low amounts, is much more widespread than previously thought. This emphasizes that the MBT-CBT proxy for continental air temperature should only be used at locations where soil organic matter input is significant as evidenced by high BIT indices. References: [1] Weijers J.W.H. et al. (2007) Geochmim. Cosmochim. Acta 71, 703-713. [2] Hopmans E.C. et al. (2004) Earth Planet. Sci. Lett. 224, 107-116. [3] Peterse F. et al. (2009) Org. Geochem. 40, 692-699. [4] Zhu C. Et al. (2011) Org. Geochem. 42, 376-386.

A spatially distributed model for the dynamic prediction of sediment erosion and transport in mountainous forested watersheds

NASA Astrophysics Data System (ADS)

Doten, Colleen O.; Bowling, Laura C.; Lanini, Jordan S.; Maurer, Edwin P.; Lettenmaier, Dennis P.

2006-04-01

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment model that represents the main sources of sediment generation in forested environments (mass wasting, hillslope erosion, and road surface erosion) within the distributed hydrology-soil-vegetation model (DHSVM) environment. The model produces slope failures on the basis of a factor-of-safety analysis with the infinite slope model through use of stochastically generated soil and vegetation parameters. Failed material is routed downslope with a rule-based scheme that determines sediment delivery to streams. Sediment from hillslopes and road surfaces is also transported to the channel network. A simple channel routing scheme is implemented to predict basin sediment yield. We demonstrate through an initial application of this model to the Rainy Creek catchment, a tributary of the Wenatchee River, which drains the east slopes of the Cascade Mountains, that the model produces plausible sediment yield and ratios of landsliding and surface erosion when compared to published rates for similar catchments in the Pacific Northwest. A road removal scenario and a basin-wide fire scenario are both evaluated with the model.

Effect of alternative surface inlet designs on sediment and phosphorus drainage losses

USDA-ARS?s Scientific Manuscript database

Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine whether modifying open inlets by burying them in gravel capped with 30 cm of sandy clay loam soil or in ve...

Tracing the source of sedimentary organic carbon in the Loess Plateau of China: An integrated elemental ratio, stable carbon signatures, and radioactive isotopes approach.

PubMed

Liu, Chun; Dong, Yuting; Li, Zhongwu; Chang, Xiaofeng; Nie, Xiaodong; Liu, Lin; Xiao, Haibing; Bashir, Hassan

2017-02-01

Soil erosion, which will induce the redistribution of soil and associated soil organic carbon (SOC) on the Earth's surface, is of critically importance for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). This study used natural abundance levels of the stable isotope signature ( 13 C) and radioactive isotopes ( 137 Cs and 210 Pb ex ), along with elements ratio (C/N) based on a two end member mixing model to qualitatively and quantitatively identify the sources of sedimentary OC retained by check dam in the Qiaozigou small watershed in the Loess Plateau, China. Sediment profiles (0-200 cm) captured at natural depositional area of the basin was compared to possible source materials, which included: superficial Loess mineral soils (0-20 cm) from three land use types [i.e., grassland (Medicago sativa), forestland (Robinia pseudoacacia.), shrubland (Prunus sibirica), and gully land (Loess parent material.)]. The results demonstrated that SOC in sediments showed significantly negative correlation with pH (P < 0.01), and positive correlation with soil water content (SWC) (P < 0.05). The sedimentary OC was not derived from grasslands or gullies. Forestland and shrubland were two main sources of eroded organic carbon within the surface sediment (0-60 cm deep), except for that in the 20-40 cm soil layer. Radionuclides analyses also implied that the surface sediments retained by check-dams mainly originated from soils of forestland and shrubland. Results of the two end-member mixing model demonstrated that more than 50% SOC (mean probability estimate (MPE) 50.13% via 13 C and 60.53% via C/N) in surface sediment (0-20 cm deep) derived from forestland, whereas subsurface sedimentary SOC (20-200 cm) mainly resulted from shrubland (MPE > 50%). Although uncertainties on the sources of SOC in deep soils exist, the soil organic δ 13 C and C/N is still an effective indicator for sources of sedimentary organic carbon in the deposition zone in the short term (<10 years). Copyright © 2016 Elsevier Ltd. All rights reserved.

Fine Increment Soil Collector (FISC): A new device to support high resolution soil and sediment sampling for agri-environmental assessments

NASA Astrophysics Data System (ADS)

Mabit, Lionel; Meusburger, Katrin; Iurian, Andra-Rada; Owens, Philip N.; Toloza, Arsenio; Alewell, Christine

2014-05-01

Soil and sediment related research for terrestrial agri-environmental assessments requires accurate depth incremental sampling of soil and exposed sediment profiles. Existing coring equipment does not allow collecting soil/sediment increments at millimetre resolution. Therefore, the authors have designed an economic, portable, hand-operated surface soil/sediment sampler - the Fine Increment Soil Collector (FISC) - which allows extensive control of soil/sediment sampling process and easy recovery of the material collected by using a simple screw-thread extraction system. In comparison with existing sampling tools, the FISC has the following advantages and benefits: (i) it permits sampling of soil/sediment samples at the top of the profile; (ii) it is easy to adjust so as to collect soil/sediment at mm resolution; (iii) it is simple to operate by one single person; (iv) incremental samples can be performed in the field or at the laboratory; (v) it permits precise evaluation of bulk density at millimetre vertical resolution; and (vi) sample size can be tailored to analytical requirements. To illustrate the usefulness of the FISC in sampling soil and sediments for 7Be - a well-known cosmogenic soil tracer and fingerprinting tool - measurements, the sampler was tested in a forested soil located 45 km southeast of Vienna in Austria. The fine resolution increments of 7Be (i.e. 2.5 mm) affects directly the measurement of the 7Be total inventory but above all impacts the shape of the 7Be exponential profile which is needed to assess soil movement rates. The FISC can improve the determination of the depth distributions of other Fallout Radionuclides (FRN) - such as 137Cs, 210Pbexand239+240Pu - which are frequently used for soil erosion and sediment transport studies and/or sediment fingerprinting. Such a device also offers great potential to investigate FRN depth distributions associated with fallout events such as that associated with nuclear emergencies. Furthermore, prior to remediation activities - such as topsoil removal - in contaminated soils and sediments (e.g. by heavy metals, pesticides or nuclear power plant accident releases), basic environmental assessment often requires the determination of the extent and the depth penetration of the different contaminants, precision that can be provided by using the FISC.

Soil surface lowering due to soil erosion in villages near Lake Victoria, Uganda

NASA Astrophysics Data System (ADS)

de Meyer, A.; Deckers, J.; Poesen, J.; Isabirye, M.

2009-04-01

In the effort to pinpoint the sources of sediment pollution in Lake Victoria, the contribution of sedi-ment from compounds, landing sites, main roads and footpaths is determined in the catchment of Na-bera Bay and Kafunda Bay at the northern shore of Lake Victoria in southern Uganda. The amount of soil loss in compounds and landing sites is determined by the reconstruction of the original and current soil surface according to botanical and man-made datable objects. The soil erosion rate is then deter-mined by dividing the eroded soil volume (corrected for compaction) by the age of the oldest datable object. In the study area, the average soil erosion rate in compounds amounts to 107 Mg ha-1 year-1 (per unit compound) and in landing sites to 207 Mg ha-1 year-1 (per unit landing site). Although com-pounds and landing sites occupy a small area of the study area (1.1 %), they are a major source of sediment to Lake Victoria (63 %). The soil loss on footpaths and main roads is calculated by multip-lying the total length of footpaths and main roads with the average width and depth (measured towards a reference surface). After the correction for compaction is carried out, the soil erosion rate on foot-paths amounts to 34 Mg ha-1 year-1 and on main roads to 35 Mg ha-1 year-1. Also footpaths and main roads occupy a small area of the study area (1.1 %), but contribute disproportionately to the total soil loss in the catchment (22 %). In this research, the information about the village/compound given by the villager/owner is indispensable. In accordance to an adaptation of the model of McHugh et al. (2002), 32 % of the sediment that is generated in the catchment, is deposited in Lake Victoria (i.e. 2 209 Mg year-1 or 0.7 Mg ha-1 year-1). The main buffer in the study area is papyrus at the shore of Lake Victoria. Also sugarcane can be a major buffer. However, the sugarcane-area is intersected by com-pounds, landing sites, footpaths and main roads that generate large amounts of sediment and function as main bypass mechanisms (high CR) facilitating and enhancing sediment delivery to Lake Victoria.

Sediment and solute transport in a mountainous watershed in Valle del Cauca, Colombia

NASA Astrophysics Data System (ADS)

Guzman, Christian; Hoyos Villada, Fanny; Morales Vargas, Amalia; Rivera, Baudelino; Da Silva, Mayesse; Moreno Padilla, Pedro; Steenhuis, Tammo

2015-04-01

Sediment samples and solute concentrations were measured from the La Vega micro watershed in the southwestern region of the Colombian Andes. A main goal of this study was to improve prediction of soil surface and soil nutrient changes, based on field measurements, within small basin of the Aguaclara watershed network receiving different types of conservation measures. Two modeling approaches for stream discharge and sediment transport predictions were used with one of these based on infiltration-excess and the other on saturation-excess runoff. These streams are a part of a recent initiative from a water fund established by Asobolo, Asocaña, and Cenicaña in collaboration with the Natural Capital Project to improve conservation efforts and monitor their effects. On-site soil depth changes, groundwater depth measurements, and soil nutrient concentrations were also monitored to provide more information about changes within this mountainous watershed during one part of the yearly rainy season. This information is being coupled closely with the outlet sediment concentration and solute concentration patterns to discern correlations between scales. Lateral transects in the upper, middle, and lower part of the hillsides in the La Vega micro watershed showed differences in soil nutrient status and soil surface depth changes. The model based on saturation-excess, semi-distributed hydrology was able to reproduce discharge and sediment transport rates as well as the initially used infiltration excess model indicating available options for comparison of conservation changes in the future.

Mineral formation and organo-mineral controls on the bioavailability of carbon at the terrestrial-aquatic interface

NASA Astrophysics Data System (ADS)

Rod, K. A.; Smith, A. P.; Renslow, R.

2016-12-01

Recent evidence highlights the importance of organo-mineral interactions in regulating the source or sink capacity of soil. High surface area soils, such as allophane-rich or clay-rich soils, retain organic matter (OM) via sorption to mineral surfaces which can also contribute physical isolation in interlayer spaces. Despite the direct correlation between mineral surfaces and OM accumulation, the pedogenic processes controlling the abundance of reactive surface areas and their distribution in the mineral matrix remains unclear. As global soil temperatures rise, the dissolution of primary minerals and formation of new secondary minerals may be thermodynamically favored as part of soil weathering process. Newly formed minerals can supply surfaces for organo-metallic bonding and may, therefore, stabilize OM by surface bonding and physical exclusion. This is especially relevant in environments that intersect terrestrial and aquatic systems, such as the capillary fringe zone in riparian ecosystems. To test the mechanisms of mineral surface area protection of OM, we facilitated secondary precipitation of alumino-silicates in the presence of OM held at two different temperatures in natural Nisqually River sediments (Mt Rainier, WA). This was a three month reaction intended to simulate early pedogenesis. To tease out the influence of mineral surface area increase during pedogenesis, we incubated the sediments at two different soil moisture contents to induce biodegradation. We measured OM desorption, biodegradation, and the molecular composition of mineral-associated OM both prior to and following the temperature manipulation. To simulate the saturation of capillary fringe sediment and associated transport and reaction of OM, column experiments were conducted using the reacted sediments. More co-precipitation was observed in the 20°C solution compared to the 4°C reacted solution suggesting that warming trends alter mineral development and may remove more OM from solution. The results from the static experiments will be used to model and predict the impacts of mineral sorption and biological activity on OM persistence in the context of dynamic saturation conditions and heterogeneous material properties.

Vegetation death and rapid loss of surface elevation in two contrasting Mississippi delta salt marshes: The role of sedimentation, autocompaction and sea-level rise

USGS Publications Warehouse

Day, J.W.; Kemp, G.P.; Reed, D.J.; Cahoon, D.R.; Boumans, R.M.; Suhayda, J.M.; Gambrell, R.

2011-01-01

From 1990 to 2004, we carried out a study on accretionary dynamics and wetland loss in salt marshes surrounding two small ponds in the Mississippi delta; Old Oyster Bayou (OB), a sediment-rich area near the mouth of the Atchafalaya River and Bayou Chitigue (BC), a sediment-poor area about 70. km to the east. The OB site was stable, while most of the marsh at BC disappeared within a few years. Measurements were made of short-term sedimentation, vertical accretion, change in marsh surface elevation, pond wave activity, and marsh soil characteristics. The OB marsh was about 10. cm higher than BC; the extremes of the elevation range for Spartina alterniflora in Louisiana. Vertical accretion and short-term sedimentation were about twice as high at BC than at OB, but the OB marsh captured nearly all sediments deposited, while the BC marsh captured <30%. The OB and BC sites flooded about 15% and 85% of the time, respectively. Marsh loss at BC was not due to wave erosion. The mineral content of deposited sediments was higher at OB. Exposure and desiccation of the marsh surface at OB increased the efficiency that deposited sediments were incorporated into the marsh soil, and displaced the marsh surface upward by biological processes like root growth, while also reducing shallow compaction. Once vegetation dies, there is a loss of soil volume due to loss of root turgor and oxidation of root organic matter, which leads to elevation collapse. Revegetation cannot occur because of the low elevation and weak soil strength. The changes in elevation at both marsh sites are punctuated, occurring in steps that can either increase or decrease elevation. When a marsh is low as at BC, a step down can result in an irreversible change. At this point, the option is not restoration but creating a new marsh with massive sediment input either from the river or via dredging. ?? 2010 Elsevier B.V.

Soils as Sediment database: closing a gap between soil science and geomorphology

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus J.

2016-04-01

Soils are an interface between the Earth's spheres and shaped by the nature of the interaction between them. The relevance of soil properties for the nature of the interaction between atmosphere, hydrosphere and biosphere is well-studied and accepted, on point- or ecotone-scale. However, this understanding of the largely vertical connections between spheres is not matched by a similar recognition of soil properties affecting processes acting largely in a lateral way across the land surface, such as erosion, transport and deposition of soil. Key areas where such an understanding is essential are all issues related to the lateral movement of soil-bound substances that affect the nature of soils itself, as well as water or vegetation downslope from the source area. The redistribution of eroded soil falls several disciplines, most notably soil science, agronomy, hydrology and geomorphology. Accordingly, the way sediment is described differs: in soil science, aggregation and structure are essential properties, while most process-based soil erosion models treat soil as a mixture of individual mineral grains, based on concepts derived in fluvial geomorphology or civil engineering. The actual behavior of aggregated sediment is not reflected by either approach and difficult to capture due to the dynamic nature of aggregation, especially in an environment such as running water. Still, a proxy to assess the uncertainties introduced by aggregation on the behavior of soil as sediment would represent a step forward. To develop such a proxy, a database collating relevant soil and sediment properties could serve as an initial step to identify which soil types and erosion scenarios are prone to generate a high uncertainty compared to the use of soil texture in erosion models. Furthermore, it could serve to develop standardized analytical procedures for appropriate description of soil as sediment.

Predicting the particle size distribution of eroded sediment using artificial neural networks.

PubMed

Lagos-Avid, María Paz; Bonilla, Carlos A

2017-03-01

Water erosion causes soil degradation and nonpoint pollution. Pollutants are primarily transported on the surfaces of fine soil and sediment particles. Several soil loss models and empirical equations have been developed for the size distribution estimation of the sediment leaving the field, including the physically-based models and empirical equations. Usually, physically-based models require a large amount of data, sometimes exceeding the amount of available data in the modeled area. Conversely, empirical equations do not always predict the sediment composition associated with individual events and may require data that are not always available. Therefore, the objective of this study was to develop a model to predict the particle size distribution (PSD) of eroded soil. A total of 41 erosion events from 21 soils were used. These data were compiled from previous studies. Correlation and multiple regression analyses were used to identify the main variables controlling sediment PSD. These variables were the particle size distribution in the soil matrix, the antecedent soil moisture condition, soil erodibility, and hillslope geometry. With these variables, an artificial neural network was calibrated using data from 29 events (r 2 =0.98, 0.97, and 0.86; for sand, silt, and clay in the sediment, respectively) and then validated and tested on 12 events (r 2 =0.74, 0.85, and 0.75; for sand, silt, and clay in the sediment, respectively). The artificial neural network was compared with three empirical models. The network presented better performance in predicting sediment PSD and differentiating rain-runoff events in the same soil. In addition to the quality of the particle distribution estimates, this model requires a small number of easily obtained variables, providing a convenient routine for predicting PSD in eroded sediment in other pollutant transport models. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental Assessment: Zebra Mussel Eradication from the Base Lake at Offutt Air Force Base

DTIC Science & Technology

2008-09-11

water flow even in large diameter piping, increase sedimentation rates , and promote surface corrosion. Natural populations of 5,000 to 30,000...Body Weight (kg) Foraging Territory (ha) Food Ingestion Rate (kg dw/day) Food Ingestion Rate (kg ww/day) Water (L/day) Sediment / Soil Ingestion...Composition - based on diets for Missouri; Korschgen (1958) in USEPA (1993) Soil/ Sediment Ingestion Rate – Assumed 1% of dw ingestion rate ; USEPA (2000

Effect of replacing surface inlets with blind or gravel inlets on sediment and phosphorus subsurface drainage losses

USDA-ARS?s Scientific Manuscript database

Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine whether modifying open inlets by burying them in gravel capped with 30 cm of sandy clay loam soil or in ve...

Effect of aggregation on SOC transport: linking soil properties to sediment organic matter

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus J.

2016-04-01

Soils are an interface between the Earth's spheres and shaped by the nature of the interaction between them. The relevance of soil properties for the nature of the interaction between atmosphere, hydrosphere and biosphere is well-studied and accepted, on point- or ecotone-scale. However, this understanding of the largely vertical connections between spheres is not matched by a similar recognition of soil properties affecting processes acting largely in a lateral way across the land surface, such as erosion, transport and deposition of soil and the associated organic matter. Understanding the redistribution of eroded soil organic matter falls into several disciplines, most notably soil science, agronomy, hydrology and geomorphology, and recently into biogeochemistry. Accordingly, the way soil and sediment are described differs: in soil science, aggregation and structure are essential properties, while most process-based soil erosion models treat soil as a mixture of individual mineral grains, based on concepts derived in fluvial geomorphology or civil engineering. The actual behavior of aggregated sediment and the associated organic matter is not reflected by either approach and difficult to capture due to the dynamic nature of aggregation, especially in an environment such as running water. Still, a proxy to assess the uncertainties introduced by aggregation on the behavior of soil/sediment organic while moving in water across landscapes and into the aquatic system would represent a major step forward. To develop such a proxy, a database collating relevant soil, organic matter and sediment properties could serve as an initial step to identify which soil types and erosion scenarios are prone to generate a high uncertainty compared to the use of soil texture in erosion models. Furthermore, it could serve to develop standardized analytical procedures for appropriate description of soil and organic matter as sediment.

The vulnerability of Indo-Pacific mangrove forests to sea-level rise

USGS Publications Warehouse

Lovelock, Catherine E.; Cahoon, Donald R.; Friess, Daniel A.; Guntenspergen, Glenn R.; Krauss, Ken W.; Reef, Ruth; Rogers, Kerrylee; Saunders, Megan L.; Sidik, Frida; Swales, Andrew; Saintilan, Neil; Thuyen, Le Xuan; Triet, Tran

2015-01-01

Sea-level rise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-level rise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world’s mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-level rise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-level rise, but for 69 per cent of our study sites the current rate of sea-level rise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

The vulnerability of Indo-Pacific mangrove forests to sea-level rise.

PubMed

Lovelock, Catherine E; Cahoon, Donald R; Friess, Daniel A; Guntenspergen, Glenn R; Krauss, Ken W; Reef, Ruth; Rogers, Kerrylee; Saunders, Megan L; Sidik, Frida; Swales, Andrew; Saintilan, Neil; Thuyen, Le Xuan; Triet, Tran

2015-10-22

Sea-level rise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-level rise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world's mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-level rise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-level rise, but for 69 per cent of our study sites the current rate of sea-level rise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

Adsorption of tetracycline on soil and sediment: effects of pH and the presence of Cu(II).

PubMed

Zhang, Zheyun; Sun, Ke; Gao, Bo; Zhang, Guixiang; Liu, Xitao; Zhao, Ye

2011-06-15

Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K(OC)) and PMM saturated adsorption capacity (Q(OC)(0)) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH<5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH. Copyright © 2011 Elsevier B.V. All rights reserved.

Soil erosion in humid regions: a review

Treesearch

Daniel J. Holz; Karl W.J. Williard; Pamela J. Edwards; Jon E. Schoonover

2015-01-01

Soil erosion has significant implications for land productivity and surface water quality, as sediment is the leading water pollutant worldwide. Here, erosion processes are defined. The dominant factors influencing soil erosion in humid areas are reviewed, with an emphasis on the roles of precipitation, soil moisture, soil porosity, slope steepness and length,...

Permafrost Mobilization from the Watershed to the Colville River Delta: Evidence from Biomarkers and 14C Ramped Pyrolysis

NASA Astrophysics Data System (ADS)

Zhang, X.; Bianchi, T. S.; Cui, X.; Rosenheim, B. E.; Ping, C. L.; Kanevskiy, M. Z.; Hanna, A. M.; Allison, M. A.

2016-12-01

As temperatures in the Arctic rise abnormally fast, permafrost in the region is vulnerable to extensive thawing. This could release previously frozen organic carbon (OC) into the contemporary carbon cycle, giving a positive feedback on global warming. Recent research has found the presence of particulate permafrost in rivers, deltas, and continental shelves in the Arctic, but little direct evidence exists on the mechanism of transportation of previously frozen soils from watershed to the coast. The Colville River in northern Alaska is the largest North American Arctic River with a continuous permafrost within its watershed. Previous work has found evidence for the deposition of previously frozen soils in the Colville River delta (Schreiner et al., 2014). Here, we compared the bulk organic carbon thermal properties, ages of soils and river and delta sediments from the Colville River drainage system using 14C Ramped Pyrolysis and chemical biomarkers. Our data show that deep permafrost soils as well as river and delta sediments had similar pyrograms and biomarker signatures, reflecting transport of soils from watershed to the delta. Surface soil had pyrograms indicative of less stable (more biodegradable) OC than deeper soil horizons. Similarity in pyrograms of deep soils and river sediment indicated the limited contribution of surface soils to riverine particulate OC inputs. Sediments in the delta showed inputs of yedoma (ice-rich syngenetic permafrost with large ice wedges) from the watershed sources (e.g., river bank erosion) in addition to peat inputs, that were largely from coastal erosion.

From shifting cultivation to teak plantation: effect on overland flow and sediment yield in a montane tropical catchment.

PubMed

Ribolzi, Olivier; Evrard, Olivier; Huon, Sylvain; de Rouw, Anneke; Silvera, Norbert; Latsachack, Keo Oudone; Soulileuth, Bounsamai; Lefèvre, Irène; Pierret, Alain; Lacombe, Guillaume; Sengtaheuanghoung, Oloth; Valentin, Christian

2017-06-21

Soil erosion supplies large quantities of sediments to rivers of Southeastern Asia. It reduces soil fertility of agro-ecosystems located on hillslopes, and it degrades, downstream, water resource quality and leads to the siltation of reservoirs. An increase in the surface area covered with commercial perennial monocultures such as teak plantations is currently observed at the expanse of traditional slash-and-burn cultivation systems in steep montane environments of these regions. The impacts of land-use change on the hydrological response and sediment yields have been investigated in a representative catchment of Laos monitored for 13 years. After the gradual conversion of rice-based shifting cultivation to teak plantation-based systems, overland flow contribution to stream flow increased from 16 to 31% and sediment yield raised from 98 to 609 Mg km -2 . This result is explained by the higher kinetic energy of raindrops falling from the canopy, the virtual absence of understorey vegetation cover to dissipate drop energy and the formation of an impermeable surface crust accelerating the formation and concentration of overland flow. The 25-to-50% lower 137 Cs activities measured in soils collected under mature teak plantations compared to soils under other land uses illustrate the severity of soil erosion processes occurring in teak plantations.

Quadrant III RFI draft report: Volume 1

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

Not Available

1992-12-01

The purpose of the RCRA Facility Investigation (RFI) at The Portsmouth Gaseous Diffusion Plant (PORTS) is to acquire, analyze and interpret data that will: characterize the environmental setting, including ground water, surface water and sediment, soil and air; define and characterize sources of contamination; characterize the vertical and horizontal extent and degree of contamination of the environment; assess the risk to human health and the environment resulting from possible exposure to contaminants; and support the Corrective Measures Study (CMS), which will follow the RFI, if required. A total of 18 Solid Waste Management Units (SWMU's) were investigated. All surficial soilmore » samples (0--2 ft), sediment samples and surface-water samples proposed in the approved Quadrant III RFI Work Plan were collected as specified in the approved work plan and RFI Sampling Plan. All soil, sediment and surface-water samples were analyzed for parameters specified from the Target Compound List and Target Analyte List (TCL/TAL) as listed in the US EPA Statement of Work for Inorganic (7/88a) and Organic (2/88b) analyses for Soil and Sediment, and analyses for fluoride, Freon-113 and radiological parameters (total uranium, gross alpha, gross beta and technetium).« less

Quadrant III RFI draft report: Volume 1

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

Not Available

1992-12-01

The purpose of the RCRA Facility Investigation (RFI) at The Portsmouth Gaseous Diffusion Plant (PORTS) is to acquire, analyze and interpret data that will: characterize the environmental setting, including ground water, surface water and sediment, soil and air; define and characterize sources of contamination; characterize the vertical and horizontal extent and degree of contamination of the environment; assess the risk to human health and the environment resulting from possible exposure to contaminants; and support the Corrective Measures Study (CMS), which will follow the RFI, if required. A total of 18 Solid Waste Management Units (SWMU`s) were investigated. All surficial soilmore » samples (0--2 ft), sediment samples and surface-water samples proposed in the approved Quadrant III RFI Work Plan were collected as specified in the approved work plan and RFI Sampling Plan. All soil, sediment and surface-water samples were analyzed for parameters specified from the Target Compound List and Target Analyte List (TCL/TAL) as listed in the US EPA Statement of Work for Inorganic (7/88a) and Organic (2/88b) analyses for Soil and Sediment, and analyses for fluoride, Freon-113 and radiological parameters (total uranium, gross alpha, gross beta and technetium).« less

Investigation of the Impact of Stone Bunds on Erosion and Deposition Processes combining Conventional and Tracer Methodology in the Gumara Maksegnit Watershed, Northern Highlands of Ethiopia

NASA Astrophysics Data System (ADS)

Obereder, Eva Maria; Wakolbinger, Stefanie; Guzmán, Gema; Strohmeier, Stefan; Demelash, Nigus; Gomez, José Alfonso; Klik, Andreas

2016-04-01

Ethiopia is one of the poorest countries of the word, with over 85 % of total population dependent from agriculture. Massive deforestation in the past and missing soil and water conservation (SWC) measures cause severe soil erosion problems in the northern highlands of Ethiopia. Different SWC methods are supposed to prevent ongoing land degradation, which is triggered by rainfall driven soil erosion in the Ethiopian agricultural lands. Common technologies for soil and water conservation are stone bunds, which reduce surface runoff and sediment loss. In June 2015 two field experiments were set up in the Gumara-Maksegnit watershed in Northern Ethiopia. The objective of this study was to evaluate the impact of graded stone bunds on surface runoff and sediment yield by using conventional and tracing approaches. Three consecutive runoff plots of 20 x 4 m length and width, respectively were established along the maximum slope direction. Each one was separated to the downstream one by a stone bund. The experimental setup allowed the measurement of surface runoff along each stone bund and the measurement of overflow over the lowest stone bund. To assess the pathway and the spatial distribution of the sediments a different tracer (Magnetite, Hematite and Goethite) was applied in a 40 cm wide strip at the top of each one of the plots. The second tracer experiment was conducted on the same hillslope. It consisted of a 20 m long hillslope without borders in which a 4 m long and 40 cm wide Magnetite strip was placed at the top. At the end of August 2015 soil samples of 0-2 cm depth were taken in a 1.5 x 1.5 m grid within the area of the hillslope. Soil samples parallel to the stone bund (above and underneath) were taken along 16 m to assess the soil movement/deposition. Tracer concentrations of soil and sediment samples in both trials were analysed. Runoff and sediment were collected in weekly intervals from July to September. Runoff and erosion data, as well as the evaluation of the tracer experiments are presented. Preliminary results give an insight of the spatial pattern of sediment flow paths and accumulation areas to understand sediment dynamics within these systems. Gained knowledge on erosion processes provides information about the efficiency of the stone bunds as a SWC measure, very useful to optimize their design which affect indirectly to soil fertility and therefore to crop yield.

Water and soil loss from landslide deposits as a function of gravel content in the Wenchuan earthquake area, China, revealed by artificial rainfall simulations.

PubMed

Gan, Fengling; He, Binghui; Wang, Tao

2018-01-01

A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China.

Water and soil loss from landslide deposits as a function of gravel content in the Wenchuan earthquake area, China, revealed by artificial rainfall simulations

PubMed Central

Gan, Fengling; Wang, Tao

2018-01-01

A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China. PMID:29723279

Effect of the slope and initial moisture content on soil loss, aggregate and particle size distribution

NASA Astrophysics Data System (ADS)

Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka

2015-04-01

Soil structure degradation has effect through the soil water balance and nutrient supply on the agricultural potential of an area. The soil erosion process comprises two phases: detachment and transport by water. To study the transport phase nozzle type laboratory-scale rainfall simulator was used with constant 80 mmhr-1 intensity on an arable haplic Cambisol. Measuring the aggregate and particle size distribution of the soil loss gives a good approach the erosion process. The primary objective of this study was to examine the sediment concentration, and detect the quality and quantity change of the soil loss during a single precipitation under six treatment combinations (recently tilled and crusty soil surface on two different slope steepness, inland inundation and drought soil conditions). Soil loss were collected continually, and separated per aggregate size fractions with sieves in three rounds during a rain to measure the weights. The particle size distribution was measured with Horiba LA-950 particle size analyzer. In general the ratio of the macro aggregates decreases and the ratio of the micro aggregates and clay fraction increases in the sediment with time during the precipitation due to the raindrop impact. Sediment concentration depends on the slope steepness, as from steeper slopes the runoff can transport bigger amount of sediment, but from the tilled surface bigger aggregates were washing down. Micro aggregate fraction is one of the indicators of good soil structure. The degradation of micro aggregates occurs in steeper slopes and the most erosive time period depends on the micromorphology of the surface. And while the aggregate size distribution of the soil loss of the treatments shows high variety of distribution and differs from the original soil, the particle size distribution of each aggregate size fraction shows similar trends except the 50-250 µm fraction where the fine sand fraction is dominating instead of the loam. This anomaly may be connected with the TC content of this fraction, but more research is needed. In agricultural areas micro aggregate fraction plays important role in nutrient supply thus understanding the erosion process is necessary because of the better protection in the future.

Ability of One-Dimensional Hairsine-Rose Erosion Model to Predict Sediment Transport over a Soil with Significant Surface Stones

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Sander, G. C.; Parlange, J.-Y.; Heng, B. C. P.; Tromp-van Meerveld, H. J.

2010-05-01

Surface stones affect erosion rates by reducing raindrop-driven detachment and protecting the original soil against overland flow induced-hydraulic stress. Numerous studies have shown that the effect of surface stones on erosion depends on both the stone characteristics (e.g., size, distribution) and the soil properties. The aim of this study was (i) to quantify how the stone characteristics can affect the total sediment concentration and the concentrations of the individual size classes, (ii) to test if stones affect preferentially a particular size class within the eroded sediment and (iii) to determine whether the 1D Hairsine-Rose (H-R) erosion model can represent the experimental data. A series of laboratory experiments were conducted using the 2 m × 6 m EPFL erosion flume for a high rainfall intensity (60 mm/h) event on a gentle slope (2.2%). The flume was divided into two identical 1-m wide flumes. This separation was done to allow simultaneous replicate experiments. Experiments were conducted with different configurations and scenarios (stone coverage, size and emplacement). Three coverage proportions (20%, 40%, and 70%), two stone diameters (3-4 and 6-7 cm) and two emplacement types (topsoil and partially embedded) were tested. For each experiment, the total sediment concentration, the concentration for the individual size classes, and the flume discharge were measured. Infiltration rates were measured at different depths and locations. A high resolution laser scanner provided details of the surface change due to erosion during the experiments. This technique allowed us to quantify the spatial distribution of eroded soil and to understand better if sediment transport is 1D or rather 2D over the flumes. The one-dimensional Hairsine-Rose (H-R) erosion model was used to fit the integrated data and to provide estimates of the parameters. The ability of the 1D H-R model to predict the measured sediment concentrations in the presence of stones in the soil matrix with different configurations was tested, with reasonable results.

Assessment of hydrology, suspended sediment and particulate organic carbon transport in a large agricultural catchment using SWAT model

NASA Astrophysics Data System (ADS)

Chantha, Oeurng; Sabine, Sauvage; José-Miguel, Sánchez-Pérez

2010-05-01

Suspended sediment transport from agricultural catchments to stream networks is responsible for aquatic habitat degradation, reservoir sedimentation and the transport of sediment-bound pollutants (pesticides, particulate nutrients, heavy metals and other toxic substances). Quantifying and understanding the dynamics of suspended sediment transfer from agricultural land to watercourses is essential in controlling soil erosion and in implementing appropriate mitigation practices to reduce stream suspended sediment and associated pollutant loads, and hence improve surface water quality downstream. Gascogne area, southwest France, has been dominated by anthropogenic activities particularly intensive agriculture causing severe erosion in recent decades. This leads to a major threat to surface water quality due to soil erosion. Therefore, the catchment water quality has been continuously monitored since January 2007 and the historical data of hydrology and suspended sediment has existed since 1998. In this study, the Soil and Water Assessment Tool (SWAT 2005) was applied to assess hydrology, suspended sediment and particulate organic carbon in this catchment Agricultural management practices (crop rotation, planting date, fertilizer quantity and irrigations) were taken into the model for simulation period of 11 years (July, 1998 to March, 2009). The investigation was conducted using a 11-year streamflow and two years of suspended sediment record from January 2007 to March 2009. Modelling strategy with dominant landuse and soil type was chosen in this study. The SWAT generally performs satisfactorily and could simulate both daily and monthly runoff and sediment yield. The simulated daily and monthly runoff matched the observed values satisfactorily (ENash>0.5). For suspended sediment simulation, the simulated values were compared with the observed continuous suspended sediment derived from turbidity data. Based on the relationship between SSC and POC (R2 = 0.93), POC was modelled by simulated SSC from SWAT. The model predicted that the average annual catchment rainfall of the 11-year evaluation period (726 mm) with evapotranspiration (78.3%), percolation/groundwater recharge (14.1%), transmission loss (0.5%), and yielding surface runoff (7.1%). The simulated average total water yield of 11 years accounted for 138 mm (observed=133mm) and annual sediment yield varying from 4766 t to 123000 t (Mean= 48 t km-2). The annual yield of particulate organic carbon ranged from 120 t to 3100 t (Mean=1.2 t km-2).

Improved Flotation Technique for Microscopy of In Situ Soil and Sediment Microorganisms

PubMed Central

Bone, T. L.; Balkwill, D. L.

1986-01-01

An improved flotation method for microscopy of in situ soil and sediment microorganisms was developed. Microbial cells were released into gellike flotation films that were stripped from soil and sediment aggregates as these aggregates were submerged in 0.5% solutions of polyvinylpyrrolidone. The use of polyvinylpyrrolidone solutions instead of water facilitated the release of films from saturated samples such as aquifer sediments as well as from typical surface soils. In situ microbial morphological characteristics could then be surveyed rapidly by light microscopy of films stained with acridine orange. This method effectively determined the ranges of morphological diversity in a variety of sample types. It also detected microcolonies and other spatial relationships among microbial cells. Only a small fraction (3.4 to 10.1%) of the microflora was released into the flotation films, but plating and direct evaluations by microscopy showed that this fraction was representative of the total population. Images PMID:16347005

Contamination and risk of heavy metals in soils and sediments from a typical plastic waste recycling area in North China.

PubMed

Tang, Zhenwu; Zhang, Lianzhen; Huang, Qifei; Yang, Yufei; Nie, Zhiqiang; Cheng, Jiali; Yang, Jun; Wang, Yuwen; Chai, Miao

2015-12-01

Plastic wastes are increasingly being recycled in many countries. However, available information on the metals released into the environment during recycling processes is rare. In this study, the contamination features and risks of eight heavy metals in soils and sediments were investigated in Wen'an, a typical plastic recycling area in North China. The surface soils and sediments have suffered from moderate to high metal pollution and in particular, high Cd and Hg pollution. The mean concentrations of Cd and Hg were 0.355 and 0.408 mg kg(-1), respectively, in the soils and 1.53 and 2.10 mg kg(-1), respectively, in the sediments. The findings suggested that there is considerable to high potential ecological risks in more than half of the soils and high potential ecological risk in almost all sediments. Although the health risk levels from exposure to soil metals were acceptable for adults, the non-carcinogenic risks to local children exceeded the acceptable level. Source assessment indicated that heavy metals in soils and sediments were mainly derived from inputs from poorly controlled plastic waste recycling operations in this area. The results suggested that the risks associated with heavy metal pollution from plastic waste recycling should be of great concern. Copyright © 2015 Elsevier Inc. All rights reserved.

Formation and mechanics of granular waves in gravity and shallow overland flow

USDA-ARS?s Scientific Manuscript database

Sediment transport in overland flow is a highly complex process involving many properties relative to the flow regime characteristics, soil surface conditions, and type of sediment. From a practical standpoint, most sediment transport studies are concerned with developing relationships of rates of s...

The importance of both geological and pedological processes in control of grain size and sedimentation rates in Peoria Loess

USGS Publications Warehouse

Wang, Hongfang; Mason, J.A.; Balsam, W.L.

2006-01-01

The loess-paleosol succession in the Peoria Loess in southern Illinois is characterized as alternating loess layers and weathering bands, known as paleosol A horizons. The fast loess accumulation during the late Wisconsin glaciation interacted with the incipient pedogenesis and caused unclear boundaries of loess-paleosol alternations in soil horizonation and mineralogy. Parameters of grain size distribution, sedimentation rate, matrix carbonate content and diffuse reflectance (i.e. soil colors and iron oxides) are used in this paper to discuss the geological and pedological influences for the Peoria Loess in Keller Farm section in southern Illinois. The multi-proxy analysis revealed that many paleosol A horizons, defined by the diffuse reflectance variability, contain finer-grained materials with a relatively higher sedimentation rate. It suggests that glaciofluvial sediments were available in the source areas for uploading eolian dust during the temporary ice sheet retreats. The denser vegetation and wetter surface soils on the loess deposit area could increase the dust trapping efficiency and caused a greater accumulation rate of loess deposits. The coarser-grained materials and slower sedimentation rate are often found in loess layers. It suggests that strong surface winds transported the coarser-grained materials from local dust sources and sparse vegetation and dry surface soils reduced the dust trapping efficiency during the ice sheet readvance. The strong interactions between the geological and pedological processes played an important role on the loess-paleosol alternations in southern Illinois during the late Wisconsin glaciation. ?? 2006 Elsevier B.V. All rights reserved.

Keeping agricultural soil out of rivers: evidence of sediment and nutrient accumulation within field wetlands in the UK.

PubMed

Ockenden, Mary C; Deasy, Clare; Quinton, John N; Surridge, Ben; Stoate, Chris

2014-03-15

Intensification of agriculture has resulted in increased soil degradation and erosion, with associated pollution of surface waters. Small field wetlands, constructed along runoff pathways, offer one option for slowing down and storing runoff in order to allow more time for sedimentation and for nutrients to be taken up by plants or micro-organisms. This paper describes research to provide quantitative evidence for the effectiveness of small field wetlands in the UK landscape. Ten wetlands were built on four farms in Cumbria and Leicestershire, UK. Annual surveys of sediment and nutrient accumulation in 2010, 2011 and 2012 indicated that most sediment was trapped at a sandy site (70 tonnes over 3 years), compared to a silty site (40 tonnes over 3 years) and a clay site (2 tonnes over 3 years). The timing of rainfall was more important than total annual rainfall for sediment accumulation, with most sediment transported in a few intense rainfall events, especially when these coincided with bare soil or poor crop cover. Nutrient concentration within sediments was inversely related to median particle size, but the total mass of nutrients trapped was dependent on the total mass of sediment trapped. Ratios of nutrient elements in the wetland sediments were consistent between sites, despite different catchment characteristics across the individual wetlands. The nutrient value of sediment collected from the wetlands was similar to that of soil in the surrounding fields; dredged sediment was considered to have value as soil replacement but not as fertiliser. Overall, small field wetlands can make a valuable contribution to keeping soil out of rivers. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Arsenic Fate, Transport And Stability Study: Groundwater, Surface Water, Soil And Sediment Investigation At Fort Devens Superfund Site

EPA Science Inventory

A field investigation was conducted to examine the distribution of arsenic in groundwater, surface water, and sediments at the Fort Devens Superfund Site. The study area encompassed a portion of plow Shop Pond (Red Cove), which receives groundwater discharge from the aquifer und...

Best management practices for nutrient and sediment retention in urban stormwater runoff.

PubMed

Hogan, Dianna M; Walbridge, Mark R

2007-01-01

Stormwater management infrastructure is utilized in urban areas to alleviate flooding caused by decreased landscape permeability from increased impervious surface cover (ISC) construction. In this study, we examined two types of stormwater detention basins, SDB-BMPs (stormwater detention basin-best management practice), and SDB-FCs (stormwater detention basin-flood control). Both are constructed to retain peak stormwater flows for flood mitigation. However, the SDB-BMPs are also designed using basin topography and wetland vegetation to provide water quality improvement (nutrient and sediment removal and retention). The objective of this study was to compare SDB (both SDB-BMP and SDB-FC) surface soil P concentrations, P saturation, and Fe chemistry with natural riparian wetlands (RWs), using sites in Fairfax County, Virginia as a model system. The SDB-BMPs had significantly greater surface soil total P (P(t)) concentrations than the RWs and SDB-FCs (831.9 +/- 32.5 kg ha(-1), 643.3 +/- 19.1 kg ha(-1), and 652.1 +/- 18.8 kg ha(-1), respectively). The soil P sorption capacities of SDB-BMPs were similar to the RWs, and were greater than those of SDB-FCs, appearing to result in greater soil P removal and retention in SDB-BMPs compared with SDB-FCs. Increased Fe concentrations and relatively greater amounts of more crystalline forms of Fe in SDB-BMP soils suggested increased sediment deposition compared with RW and SDB-FC soils. Data suggest that SDB nutrient and sediment retention is facilitated in SDB-BMPs. When stormwater management is necessary, use of SDB-BMPs instead of SDB-FCs could foster more responsible urban development and be an appropriate mitigation action for receiving aquatic ecosystems.

Best management practices for nutrient and sediment retention in urban stormwater runoff

USGS Publications Warehouse

Hogan, D.M.; Walbridge, M.R.

2007-01-01

Stormwater management infrastructure is utilized in urban areas to alleviate flooding caused by decreased landscape permeability from increased impervious surface cover (ISC) construction. In this study, we examined two types of stormwater detention basins, SDB-BMPs (stormwater detention basin-best management practice), and SDB-FCs (stormwater detention basin-flood control). Both are constructed to retain peak stormwater flows for flood mitigation. However, the SDB-BMPs are also designed using basin topography and wetland vegetation to provide water quality improvement (nutrient and sediment removal and retention). The objective of this study was to compare SDB (both SDB-BMP and SDB-FC) surface soil P concentrations, P saturation, and Fe chemistry with natural riparian wetlands (RWs), using sites in Fairfax County, Virginia as a model system. The SDB-BMPs had significantly greater surface soil total P (Pt) concentrations than the RWs and SDB-FCs (831.9 ?? 32.5 kg ha-1, 643.3 ?? 19.1 kg ha-1, and 652.1 ?? 18.8 kg ha-1, respectively). The soil P sorption capacities of SDB-BMPs were similar to the RWs, and were greater than those of SDB-FCs, appearing to result in greater soil P removal and retention in SDB-BMPs compared with SDB-FCs. Increased Fe concentrations and relatively greater amounts of more crystalline forms of Fe in SDB-BMP soils suggested increased sediment deposition compared with RW and SDB-FC soils. Data suggest that SDB nutrient and sediment retention is facilitated in SDB-BMPs. When stormwater management is necessary, use of SDB-BMPs instead of SDB-FCs could foster more responsible urban development and be an appropriate mitigation action for receiving aquatic ecosystems. ?? ASA, CSSA, SSSA.

NEARBY LAKE SEDIMENT QUALITY AND SEEDLING TREE SURVIVAL ON ERODED OILY WASTE/BRINE CONTAMINATED SOIL

EPA Science Inventory

An ecosystem restoration study is being conducted at an old oil production area in Northeast Oklahoma. Surface soil samples from areas impacted by discarded crude oil and brine wastes have been chemically characterized. Surface erosion has occurred in areas impacted by waste disc...

77 FR 31215 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-25

... and Hazardous Substances Pollution Contingency Plan; National Priorities List: Partial Deletion of the... National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This partial deletion pertains to the surface soil, unsaturated subsurface soil, surface water and sediments of Operable Unit (OU) 1...

Fertilizer placement and tillage effects on phosphorus leaching in fine-textured soils

USDA-ARS?s Scientific Manuscript database

Adoption of no-tillage in agricultural watersheds has resulted in substantial reductions in sediment and particulate phosphorus (P) delivery to surface waters. No-tillage, however, may result in increased losses of dissolved P in tile-drained landscapes due to the accumulation of P in surface soil l...

USING CONONICAL CORRELATION TO DETECT ASSOCIATION OF LANDSCAPE METRICS WITH WATER BIOLOGICAL AND CHEMICAL PROPERTIES IN SAVANNAH RIVER BASIN

EPA Science Inventory

Surface water quality is related to conditions in the surrounding geophysical environment, including soils, landcover, and anthropogenic activities. For example, clearing vegetation exposes soil to increased water/wind erosion, resulting in increased sediment loads to surface wat...

[Physicochemical properties of Guanting Reservoir sediment and its land application].

PubMed

Su, De-Chun; Hu, Yu-Feng; Song, Chong-Wei; Wu, Fei-Long; Liu, Pei-Bin

2007-06-01

Surface sediment of Guanting Reservoir was dredged up and dewatered in field, and pollutant and physicochemical characterizations were mensurated. The stabilization and agricultural land use of the sediment was also studied in the field. Results showed that the sediments have a higher clay content, bulk density (1.89 g x cm(-3)) and lower porosity (23.8%), higher deoxidize material and available nitrogen, phosphorus concentration. Heavy metal and organochlorinated pesticides concentration was lower than the class II of national standard for soil. Stabilized the sediment with sand soil and straw could improve the physical property and decrease the concentration of deoxidize material and available nitrogen, phosphorus. Stabilized sediment could be a suitable medium for alfalfa, tree and corn growth and used for agricultural land.

Issues of upscaling in space and time with soil erosion models

NASA Astrophysics Data System (ADS)

Brazier, R. E.; Parsons, A. J.; Wainwright, J.; Hutton, C.

2009-04-01

Soil erosion - the entrainment, transport and deposition of soil particles - is an important phenomenon to understand; the quantity of soil loss determines the long term on-site sustainability of agricultural production (Pimental et al., 1995), and has potentially important off-site impacts on water quality (Bilotta and Brazier, 2008). The fundamental mechanisms of the soil erosion process have been studied at the laboratory scale, plot scale (Wainwright et al., 2000), the small catchment scale (refs here) and river basin scale through sediment yield and budgeting work. Subsequently, soil erosion models have developed alongside and directly from this empirical work, from data-based models such as the USLE (Wischmeier and Smith, 1978), to ‘physics or process-based' models such as EUROSEM (Morgan et al., 1998) and WEPP (Nearing et al., 1989). Model development has helped to structure our understanding of the fundamental factors that control soil erosion process at the plot and field scale. Despite these advances, however, our understanding of and ability to predict erosion and sediment yield at the same plot, field and also larger catchment scales remains poor. Sediment yield has been shown to both increase and decrease as a function of drainage area (de Vente et al., 2006); the lack of a simple relationship demonstrates complex and scale-dependant process domination throughout a catchment, and emphasises our uncertainty and poor conceptual basis for predicting plot to catchment scale erosion rates and sediment yields (Parsons et al., 2006b). Therefore, this paper presents a review of the problems associated with modelling soil erosion across spatial and temporal scales and suggests some potential solutions to address these problems. The transport-distance approach to scaling erosion rates (Wainwright, et al., 2008) is assessed and discussed in light of alternative techniques to predict erosion across spatial and temporal scales. References Bilotta, G.S. and Brazier, R.E., 2008. Understanding the influence of suspended solids on water quality and aquatic biota. Water Research, 42(12): 2849-2861. de Vente, J., Poesen, J., Bazzoffi, P., Van Ropaey, A.V. and Verstraeten, G., 2006. Predicting catchment sediment yield in Mediterranean environments: the importance of sediment sources and connectivity in Italian drainage basins. Earth Surface Processes And Landforms, 31: 1017-1034. Morgan, R.P.C. et al., 1998. The European soil erosion model (EUROSEM): a dynamic approach for predicting sediment transport from fields to small catchments. Earth Surface Processes And Landforms, 23: 527-544. Nearing, M. A., G. R. Foster, L. J. Lane, and S. C. Finkner. 1989. A process-based soil erosion model for USDA Water Erosion Prediction Project technology. Trans. ASAE 32(5): 1587-1593. Parsons, A.J., Brazier, R.E., Wainwright, J. and Powell, D.M., 2006a. Scale relationships in hillslope runoff and erosion. Earth Surface Processes and Landforms, 31(11): 1384-1393. Parsons, A.J., Wainwright, J., Brazier, R.E. and Powell, D.M., 2006b. Is sediment delivery a fallacy? Earth Surface Processes and Landforms, 31(10): 1325-1328. Pimental, D. et al., 1995. Environmental and economic costs of soil erosion and conservation benefits. Science, 267:1117-1122. Wainwright, J., Parsons, A.J. and Abrahams, A.D., 2000. Plot-scale studies of vegetation, overland flow and erosion interactions: case studies from Arizona and New Mexico. Hydrological Processes, 14(16-17): 2921-2943. Wischmeier, W.H. and Smith, D.D., 1978. Predicting rainfall erosion losses - a guide for conservation planning., 537.

Mobilization of selenium from the Mancos Shale and associated soils in the lower Uncompahgre River Basin, Colorado

USGS Publications Warehouse

Mast, M. Alisa; Mills, Taylor J.; Paschke, Suzanne S.; Keith, Gabrielle; Linard, Joshua I.

2014-01-01

This study investigates processes controlling mobilization of selenium in the lower part of the Uncompahgre River Basin in western Colorado. Selenium occurs naturally in the underlying Mancos Shale and is leached to groundwater and surface water by limited natural runoff, agricultural and domestic irrigation, and leakage from irrigation canals. Soil and sediment samples from the study area were tested using sequential extractions to identify the forms of selenium present in solid phases. Selenium speciation was characterized for nonirrigated and irrigated soils from an agricultural site and sediments from a wetland formed by a leaking canal. In nonirrigated areas, selenium was present in highly soluble sodium salts and gypsum. In irrigated soils, soluble forms of selenium were depleted and most selenium was associated with organic matter that was stable under near-surface weathering conditions. Laboratory leaching experiments and geochemical modeling confirm that selenium primarily is released to groundwater and surface water by dissolution of highly soluble selenium-bearing salts and gypsum present in soils and bedrock. Rates of selenium dissolution determined from column leachate experiments indicate that selenium is released most rapidly when water is applied to previously nonirrigated soils and sediment. High concentrations of extractable nitrate also were found in nonirrigated soils and bedrock that appear to be partially derived from weathered organic matter from the shale rather than from agricultural sources. Once selenium is mobilized, dissolved nitrate derived from natural sources appears to inhibit the reduction of dissolved selenium leading to elevated concentrations of selenium in groundwater. A conceptual model of selenium weathering is presented and used to explain seasonal variations in the surface-water chemistry of Loutzenhizer Arroyo, a major tributary contributor of selenium to the lower Uncompahgre River.

Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

DOEpatents

Golden, Jeffry

2007-02-13

A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacts a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

DOEpatents

Mincher, Bruce J.; Curry, Randy Dale; Clevenger, Thomas E.; Golden, Jeffry

2003-05-27

A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacts a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

Process for the solvent extraction for the radiolysis and dehalogenation of halogenated organic compounds in soils, sludges, sediments and slurries

DOEpatents

Mincher, Bruce J.; Curry, Randy Dale; Clevenger, Thomas E.; Golden, Jeffry

2000-01-01

A process of extracting halogenated organic compounds, and particularly PCBs, from soil, sediment, slurry, sludge and dehalogenating the compounds contacting a contaminated soil sample with an extraction medium of a mixture of an alkane and a water miscible alcohol. The organic compounds dissolve in the extraction medium which is separated from the soil by passing water upwardly through the soil. The extraction medium floats to the surface of the water and is separated. Thereafter, the extraction medium containing the halogenated organic contaminants is subjected to ionizing radiation to radiolytically dehalogenate the compounds.

Recent land cover history and nutrient retention in riparian wetlands

USGS Publications Warehouse

Hogan, D.M.; Walbridge, M.R.

2009-01-01

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus]. ?? 2009 Springer Science+Business Media, LLC.

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.

Soil particle tracing using RFID tags for elucidating the behavior of radiocesium on bare soil surfaces in Fukushima

NASA Astrophysics Data System (ADS)

Manome, Ryo; Onda, Yuichi; Patin, Jeremy; Stefani, Chiara; Yoshimura, Kazuya; Parsons, Tony; Cooper, James

2014-05-01

Radioactive materials are generally associated with soil particles in terrestrial environment and therefore the better understanding soil erosion processes is expected to improve the mitigation of radioactive risks. Spatial variability in soil erosion has been one of critical issues for soil erosion management. This study attempts to track soil particle movement on soil surfaces by employing Radio Frequency Identification (RFID) tags for the better understanding radiocesium behavior. A RFID tag contains a specific electronically identifier and it permits tracing its movement by reading the identifier. In this study, we made artificial soil particles by coating the RFID tags with cement material. The particle diameters of the artificial soil particles approximately ranged from 3 to 5 mm. The artificial soil particles were distributed in a reticular pattern on a soil erosion plot (bare soil surface, 22.13 m length × 5 m width, 4.4° slope) in Kawamata town where radiocesium deposited because of the Fukushima Dai-ichi power plant accident. After their distribution on October 2012, we had read the identifiers of RFID tags and recorded their locations on the plot for 14 times by September 2013. Moving distance (MD) was calculated based on the difference of the location for each sampling date. The topographical changes on the plot were also monitored with a laser scanner to describe interrill erosion and rill erosion area on 11occasions. Median MD is 10.8cm for all the observations. Median MD on interrill and rill erosion areas were 9.8 cm and 20.7 cm, respectively. Seasonal variation in MD was observed; an extremely large MD was found in May 2013, at the first reading after the winter season. This large MD after winter suggests that snowmelt runoff was the dominant process which transported the soil particles. Comparing the MD with the observed amounts of rainfall, sediment and runoff on the plot, significant positive correlation were found if the data of May, 2013. The coefficient of correlation with the amounts of surface runoff, sediment discharge and R-factor were 0.79 (p < 0.05, n = 13), 0.92 (p < 0.05, n = 13) and 0.79 (p < 0.05, n = 13), respectively. These positive correlations supported a possible use of RFID tag for tracking soil particles. There was a negative relationship between Cs-137 in sediment eroded from the plot and median MD (r = -0.40, p > 0.05, n = 13). One possible explanation for this negative relationship is that sediments on the rill area, which contain relatively low concentration of Cs-137, were discharged during intensive rainfall events and they resulted in low concentrations of Cs-137 in sediment eroded from the plot. These results suggest that the spatial distribution on Cs-137 and erosion processes should be considered for predicting radiocesium behavior even at the scale of our erosion plot.

Coordinating Chemical and Mineralogical Analyses of Antarctic Dry Valley Sediments as Potential Analogs for Mars

NASA Technical Reports Server (NTRS)

Patel, S. N.; Bishop, J. L.; Englert, P.; Gibson, E. K.

2015-01-01

The Antarctic Dry Valleys (ADV) provide a unique terrestrial analog for Martian surface processes as they are extremely cold and dry sedimentary environments. The surface geology and the chemical composition of the Dry Valleys that are similar to Mars suggest the possible presence of these soil-formation processes on Mars. The soils and sediments from Wright Valley, Antarctica were investigated in this study to examine mineralogical and chemical changes along the surface layer in this region and as a function of depth. Surface samples collected near Prospect Mesa and Don Juan Pond of the ADV were analyzed using visible/near-infrared (VNIR) and mid-IR reflectance spectroscopy and major and trace element abundances.

Pre-aged plant waxes in tropical lake sediments and their influence on the chronology of molecular paleoclimate proxy records

NASA Astrophysics Data System (ADS)

Douglas, Peter M. J.; Pagani, Mark; Eglinton, Timothy I.; Brenner, Mark; Hodell, David A.; Curtis, Jason H.; Ma, Keith F.; Breckenridge, Andy

2014-09-01

Sedimentary records of plant-wax hydrogen (δDwax) and carbon (δ13Cwax) stable isotopes are increasingly applied to infer past climate change. Compound-specific radiocarbon analyses, however, indicate that long time lags can occur between the synthesis of plant waxes and their subsequent deposition in marginal marine sediments. The influence of these time lags on interpretations of plant-wax stable isotope records is presently unconstrained, and it is unclear whether such time lags also affect lacustrine sediments. We present compound-specific radiocarbon (14Cwax) data for n-alkanoic acid plant waxes (n-C26 to n-C32) from: (1) a sediment core from Lake Chichancanab, Yucatan Peninsula, Mexico, (2) soils in the Lake Chichancanab catchment, and (3) surface sediments from three other lakes in southeastern Mexico and northern Guatemala. 14Cwax ages in the surface sediments are consistently older than modern, and may be negatively correlated with mean annual precipitation and positively correlated with lake catchment area. 14Cwax ages in soils surrounding Lake Chichancanab increase with soil depth, consistent with deep, subsoil horizons being the primary source of lacustrine aged plant waxes, which are likely delivered to lake sediments through subsurface transport. Plant waxes in the Lake Chichancanab core are 350-1200 years older than corresponding ages of bulk sediment deposition, determined by 14C dates on terrestrial plant macrofossils in the core. A δDwax time series is in closer agreement with other regional proxy hydroclimate records when a plant-wax 14C age model is applied, as opposed to the macrofossil-based core chronology. Inverse modeling of plant-wax age distribution parameters suggests that plant waxes in the Lake Chichancanab sediment core derive predominantly from millennial-age soil carbon pools that exhibit relatively little age variance (<200 years). Our findings demonstrate that high-temporal-resolution climate records inferred from stable isotope measures on plant waxes in lacustrine sediments may suffer from possible chronologic distortions as a consequence of long residence times of plant waxes in soils. They also underscore the importance of direct radiocarbon dating of these organic molecules.

Forest soil erosion prediction as influenced by wildfire and roads

NASA Astrophysics Data System (ADS)

Cao, L.; Brooks, E. S.; Elliot, W.

2017-12-01

Following a wildfire, the risk of erosion is greatly increased. Forest road networks may change the underlying topography and alter natural flow paths. Flow accumulation and energy can be redistributed by roads and alter soil erosion processes. A LiDAR (Light Detection and Ranging) DEM makes it possible to quantify road topography, and estimate how roads influence surface runoff and sediment transport in a fire-disturbed watershed. With GIS technology and a soil erosion model, this study was carried out to evaluate the effect of roads on erosion and sediment yield following the Emerald Fire southwest of Lake Tahoe. The GeoWEPP model was used to estimate onsite erosion and offsite sediment delivery from each hillslope polygon and channel segment before and after fire disturbance in part of the burned area. The GeoWEPP flow path method was used to estimate the post-fire erosion rate of each GIS pixel. A 2-m resolution LiDAR DEM was used as the terrain layer. The Emerald Fire greatly increased onsite soil loss and sediment yields within the fire boundary. Following the fire, 78.71% of the burned area had predicted sediment yields greater than 4 Mg/ha/yr, compared to the preburn condition when 65.3% of the study area was estimated to generate a sediment yield less than 0.25 Mg/ha/yr. Roads had a remarkable influence on the flow path simulation and sub-catchments delineation, affecting sediment transport process spatially. Road segments acted as barriers that intercepted overland runoff and reduced downslope flow energy accumulation, therefore reducing onsite soil loss downslope of the road. Roads also changed the boundary of sub-catchment and defined new hydrological units. Road segments can transport sediment from one sub-catchment to another. This in turn leads to the redistribution of sediment and alters sediment yield for some sub-catchments. Culverts and road drain systems are of vital importance in rerouting runoff and sediment. Conservation structures can be installed to avoid sediment deposition or debris accumulation on the road surface. On the other hand, the outlets of culverts might be at a high risk of increasing downstream channel erosion due to the large amount of runoff. This implies that conservation measurements should be considered to control the runoff and sediment output from culverts.

Regional Geochemical Results from Analyses of Stream-Water, Stream-Sediment, Soil, Soil-Water, Bedrock, and Vegetation Samples, Tangle Lakes District, Alaska

USGS Publications Warehouse

Wang, Bronwen; Gough, L.P.; Wanty, R.B.; Lee, G.K.; Vohden, James; O'Neill, J. M.; Kerin, L.J.

2008-01-01

We report chemical analyses of stream-water, stream-sediment, soil, soil-water, bedrock, and vegetation samples collected from the headwaters of the Delta River (Tangle Lakes District, Mount Hayes 1:250,000-scale quadrangle) in east-central Alaska for the period June 20-25, 2006. Additionally, we present mineralogic analyses of stream sediment, concentrated by panning. The study area includes the southwestward extent of the Bureau of Land Management (BLM) Delta River Mining District (Bittenbender and others, 2007), including parts of the Delta River Archeological District, and encompasses an area of about 500 km2(approximately bordered by the Denali Highway to the south, near Round Tangle Lake, northward to the foothills of the Alaska Range (fig. 1). The primary focus of this study was the chemical characterization of native materials, especially surface-water and sediment samples, of first-order streams from the headwaters of the Delta River. The impetus for this work was the need, expressed by the Alaska Department of Natural Resources (ADNR), for an inventory of geochemical and hydrogeochemical baseline information about the Delta River Mining District. This information is needed because of a major upturn in exploration, drilling, and general mineral-resources assessments in the region since the late 1990s. Currently, the study area, called the 'MAN Project' area is being explored by Pure Nickel, Inc. (http://www.purenickel.com/s/MAN_Alaska.asp), and includes both Cu-Au-Ag and Ni-Cu-PGE (Pt-Pd-Au-Ag) mining claims. Geochemical data on surface-water, stream-sediment, soil, soil-water, grayleaf willow (Salix glauca L.), and limited bedrock samples are provided along with the analytical methodologies used and panned-concentrate mineralogy. We are releasing the data at this time with only minimal interpretation.

Assessment of DDT and Metabolites in Soil and Sediment of Potentially Contaminated Areas of Belém, Amazon Region, Brazil.

PubMed

Rodrigues, Andreia Oliveira; de Souza, Larissa Costa; da Silva Rocha, Cássia Christina; da Costa, Amilton Cesar Gomes; de Alcântara Mendes, Rosivaldo

2017-07-01

The aim of this study was to evaluate the distribution of DDT and metabolites in surface soils and soil profiles from two areas containing deposits of obsolete pesticides in Belém, Amazon Region, Brazil. DDT and metabolites were extracted by microwave assisted extraction and analyzed by gas chromatography with electron capture detection. Concentrations of total DDT in surface soil samples ranged from 64.22 mg kg -1 in area 1 (A1) to 447.84 mg kg -1 in area 2 (A2). Lower levels were found in soil profiles than at the surface (6.21-21.17 mg kg -1 in A1 and 36.13-113.66 mg kg -1 in A2). pp'-DDT, pp'-DDE and pp'-DDD were detected in sediments at levels of 2.01, 0.96 and 0.35 mg kg -1 , respectively. The ratio (DDE + DDD)/ΣDDT was low indicating the recent introduction of DDT to the environment in the two study areas, through the volatilization and atmospheric deposition of the obsolete pesticides.

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.

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.

Effects of rainfall intensity and slope gradient on runoff and sediment yield characteristics of bare loess soil.

PubMed

Wu, Lei; Peng, Mengling; Qiao, Shanshan; Ma, Xiao-Yi

2018-02-01

Soil erosion is a universal phenomenon on the Loess Plateau but it exhibits complex and typical mechanism which makes it difficult to understand soil loss laws on slopes. We design artificial simulated rainfall experiments including six rainfall intensities (45, 60, 75, 90, 105, 120 mm/h) and five slopes (5°, 10°, 15°, 20°, 25°) to reveal the fundamental changing trends of runoff and sediment yield on bare loess soil. Here, we show that the runoff yield within the initial 15 min increased rapidly and its trend gradually became stable. Trends of sediment yield under different rainfall intensities are various. The linear correlation between runoff and rainfall intensity is obvious for different slopes, but the correlations between sediment yield and rainfall intensity are weak. Runoff and sediment yield on the slope surface both presents an increasing trend when the rainfall intensity increases from 45 mm/h to 120 mm/h, but the increasing trend of runoff yield is higher than that of sediment yield. The sediment yield also has an overall increasing trend when the slope changes from 5° to 25°, but the trend of runoff yield is not obvious. Our results may provide data support and underlying insights needed to guide the management of soil conservation planning on the Loess Plateau.

Streambeds Merit Recognition as a Scientific Discipline

NASA Astrophysics Data System (ADS)

Constantz, J. E.

2016-12-01

Streambeds are generally viewed as simply sediments beneath streams, sediments topping alluvial aquifers, or sediments housing aquatic life, rather than as distinct geographic features comparable to soils and surficial geologic formations within watersheds. Streambeds should be viewed as distinct elements within watersheds, e.g., as akin to soils. In this presentation, streambeds are described as central features in watersheds, cycling water between the surface and underlying portions of the watershed. Regarding their kinship to soils, soils are often described as surficial sediments largely created by atmospheric weathering of underlying geologic parent material, and similarly, streambeds should be described as submerged sediments largely created by streamflow modification of underlying geologic parent material. Thus, streambeds are clearly overdue for recognition as their own scientific discipline along side other well-recognized disciplines within watersheds; however, slowing progress in this direction, the point is often made that hyporheic zones should be considered comparable to streambeds, but this is as misguided as equating unsaturated zones to soils. Streambeds and soils are physical geographic features of relatively constant volume, while hyporheic and unsaturated zones are hydrologic features of varying volume. Expanded upon in this presentation, 'Streambed Science' is proposed for this discipline, which will require both a well-designed protocol to physically characterize streambeds as well as development of streambed taxonomy, for suitable recognition as an independent discipline within watersheds.

Selective nature and inherent variability of interrill erosion across prolonged rainfall simulation

NASA Astrophysics Data System (ADS)

Hu, Y.; Kuhn, N. J.; Fister, W.

2012-04-01

Sediment of interrill erosion has been generally recognized to be selectively enriched with soil organic carbon (SOC) and fine fractions (clay/silt-sized particles or aggregates) in comparison to source area soil. Limited kinetic energy and lack of concentrated runoff are the dominant factors causing selective detachment and transportation. Although enrichment ratios of SOC (ERsoc) in eroded sediment were generally reported > 1, the values varied widely. Causal factors to variation, such as initial soil properties, rainfall properties and experimental conditions, have been extensively discussed. But less attention was directed to the potential influence of prolonged rainfall time onto the temporal pattern of ERsoc. Conservation of mass dictates that ERsoc must be balanced by a decline in the source material which should also lead to a reduced or even negative ERsoc in sediment over time. Besides, the stabilizing effects of structural crust on reducing erosional variation, and the unavoidable variations of erosional response induced by the inherent complexity of interrill erosion, have scarcely been integrated. Moreover, during a prolonged rainfall event surface roughness evolves and affects the movement of eroded aggregates and mineral particles. In this study, two silt loams from Möhlin, Switzerland, organically (OS) and conventionally farmed (CS), were exposed to simulated rainfall of 30 mm h-1 for up to 6 hours. Round donut-flumes with a confined eroding area (1845 cm2) and limited transporting distance (20 cm) were used. Sediments, runoff and subsurface flow were collected in intervals of 30 min. Loose aggregates left on the eroded soil surface, crusts and the soil underneath the crusts were collected after the experiment. All the samples were analyzed for total organic carbon (TOC) content, and texture. Laser scanning of soil surface was applied before and after the rainfall event. The whole experiment was repeated for 10 times. Results from this study showed that: 1) ERsoc in eroded sediment increased at first, then reached steady state and declined afterwards, corresponding well with the formation and completion of structural crust and conservation of mass; 2) the effect of structural crust on stabilizing the surface condition and reducing variation of erosional response was more apparent once steady state discharge was achieved ; and 3) both texture and TOC content in crusts and soil underneath the crusts were comparable to parent soil, explaining the decline in ERsoc. In conclusion, the experiment showed that crusting and conservation of mass lead to a decline and even negative enrichment of organic matter in interrill sediment over time. Enrichment of organic matter should therefore be reported only in conjunction with information about the stage of crust development observed during an erosion event.

Seasonal variation in apparent conductivity and soil salinity at two Narragansett Bay salt marshes

EPA Science Inventory

Measurement of the apparent conductivity of salt marsh sediments using electromagnetic induction (EMI) is a rapid alternative to traditional methods of salinity determination that can be used to map soil salinity across a marsh surface. Soil salinity measures can provide informat...

Biophysical response of dryland soils to rainfall: implications for wind erosion

NASA Astrophysics Data System (ADS)

Bullard, J. E.; Strong, C. L.; Aubault, H.

2016-12-01

Dryland soils can be highly susceptible to wind erosion due to low vegetation cover. The formation of physical and biological soil crusts between vascular plants can exert some control on the soil surface erodibility. The development of these crusts is highly dependent on rainfall which causes sediment compaction and aggregate breakdown, and triggers photosynthetic activity and an increase soil organic matter within biological soil crusts. Using controlled field experiments, this study tests how biological soil crusts in different dryland geomorphic settings respond to various rainfall amounts (0, 5 or 10 mm) and how this in turn affects the resistance of soils to wind erosion. Results show that 10 mm of rainfall triggers more intense photosynthetic activity (high fluorescence) and a greater increase in extracellular polysaccharide content in biological crusts than 5 mm of rainfall but that the duration of photosynthetic activity is comparable for both quantities of rain. These biological responses have little impact on surface resistance, but results show that soils are more susceptible to wind erosion after rainfall events than in their initial dry state. This unexpected result could be explained by the detachment of surface sediments by raindrop impact and overland flow. The study highlights the complexity of soil erodibility at small scale which is driven by rain, wind and crust, and a necessity to understand how the spatial heterogeneity of crust and their ecophysiology alters small scale processes.

Agrogeology today

NASA Astrophysics Data System (ADS)

Kerek, Barbara; Kuti, Laszlo; Vatai, Jozsef

2010-05-01

Agrogeology is one of the research sectors of applied geology. It addresses all geological characteristics of the superficial deposits and the related geological processes taking place therein which are of crucial importance regarding agricultural production and sylviculture, influence the plantation of crops and woods and provide information on a number of factors including the sequences constituting the soil, soil forming sediments and parent rocks, the position and quality of groundwater, the salt regime governed by groundwater movement as well as the natural and manmade changes in the regions below the soil horizon affecting the surface as well. Accordingly, it investigates not only the sediment appearing on the surface and affected by soil development (=soil) but all near-surface sequences taken together as well as the relationship between soil-parent material-groundwater in lowlands and soil-soil forming sediment and parent rock in mountain and hilly areas. Furthermore, it examines also the changes of these systems as a result of human intervention and makes predictions concerning the advantageous or disadvantageous effects of these changes. Consequently, the most important tasks of agrogeology can be defined as follows: 1. Detailed agrogeological description and specification of farmlands and land units aimed at optimal land use as well as supporting the rational selection of crops and the production system. 2. Investigation of the geological factors of different soil degradation processes (erosion, deflation, salinisation, acidification, desiccation, etc.), prediction of the occurrence of these processes together with the geological chances of their prevention and minimisation. 3. Examination of the agrogeological and water regime properties of the soil-(soil forming sediment)-parent rock-groundwater system characteristic for the given land unit. 4. Research, survey, simulation and prediction of the impacts of soil use as well as agri- and sylviculture on the soil-(soil forming sediment)-parent rock-groundwater or "soil-parent rock-bedrock" system aimed at the prevention and elimination of harmful effects. 5. Investigation of the geological aspects of water regulation and irrigation as well as their impact on the environment. 6. Definition, examination and characterisation of the real soil forming geological sequence. In Hungary the actual agrogeological investigations were launched by the agricultural reambulation of geological mapping data. During the early 1980s the so-called BFK-method was elaborated to the agrogeological investigation of these areas still used today. The main aspect of this method is that apart from the common geological sampling of the boreholes samples are also taken from the top- and subsoil (horizon 1), the soil forming sediment or parent material (horizon 2), the fluctuation zone of the groundwater (horizon 3) as well as from the zone permanently below the groundwater level (horizon 4) and the groundwater itself (Figure 2). These samples undergo detailed laboratory analyses. The comparative evaluation of the derived results allows making different agrogeological conclusions. During the period elapsed from the early 1980s the survey of the pilot areas allowed us investigating among others the agrogeological relationships of salinisation, acidification, excess water risk, erosion, and trace element regime as well as vine chlorosis.

Iron oxides in eroded sediments from two representative catchments form South Spain: an example of its environmental implications

NASA Astrophysics Data System (ADS)

Diaz, I.; del Campillo, M. C.; Barrón, V.; Delgado, A.

2012-04-01

Iron (Fe) oxides accounts for one of the most important sorbent compounds in soil and sediments. Nutrients such as P and organic and inorganic pollutants can be retained in soils through its adsorption on these compounds. Particles of Fe oxides can act as a source of sorbed pollutants when these particles are eroded and transported into the bottom of lakes or water as a result of desorption of sorbed compounds or after reduction of Fe oxides under anaerobic conditions. The main target of this work was to study Fe oxides in sediments eroded from two representative catchments from South Spain and how the content and type of oxides in sediments can be affected by the soil properties. One catchment had an extension of 60 ha and soils were mainly classified as Vertisols, with 44-50 % clay in the upper horizon and pH ranging from 7.4 to 7.9. Soils in the other catchment, with an extension of 25 ha, were mainly Alfisols, with 6-33 % clay in the upper horizon and pH between 7.4 and 8.0. Phosphorus and Fe fractions in soil (18 and 10 sampling points in the Vertisol and Alfisols catchment, respectively) and sediments in runoff samples (taken during two consecutive agricultural years, 2000-2002) were studied by means of a sequential fractionation method involving extraction with: NaOH, citrate-bicarbonate (CB), citrate (C), citrate-ascorbate (CA), citrate-bicarbonate-dithionite (CBD), acetate, and HCl. Iron extraction involved sequential extraction with of CB, C, CA and CBD. The two formers step in the Fe fractionation dissolve the poorly crystalline and crystalline Fe oxides, respectively. The concentrations of all the Fe and P fractions were similar in sediments (sum of fractions were 11.5 g Fe/kg and 509 mg P/kg) and soil (sum of fractions were 10.5 g Fe/kg and 586 mg P/kg) from the Vertisol catchment. In this highly calcareous soil, the relevance of Fe oxides in the dynamics of applied P fertilizer was secondary when compared with the precipitation of poorly soluble Ca phosphates, as revealed by the significance of citrate extractable P. In the Alfisols catchment, however, the total free Fe (sum of fractions) was much higher in the sediments (19 g/kg) than in the soil (7.9 g/kg) which explains the increased amounts of P fractions related to oxides (NaOH, CB, CA, and CBD) in sediments (425 mg/kg) when compared with soils (183 mg/kg). Also, the ratio of CA to CBD extractable Fe was higher in sediments (0.22) than in soils (0.15). It can be concluded that in the Alfisol catchment, the content of sorbent surfaces sensitive to reductant conditions are increased in the sediments eroded when compared with soils, and thus, the potential release of pollutants (in this case P) adsorbed or occluded in them. In contrast, in the Vertisol catchment, where P dynamics is dominated by precipitation of Ca phosphates, these forms accounts for the dominant one in soils and sediments, without an increase in the proportion of sorbent surfaces or P forms sensitive to redox conditions.

Significant or negligible sediment and nutrient losses after fire? Pre- and post-fire comparisons

NASA Astrophysics Data System (ADS)

Shakesby, R. A.; Ferreira, A. J. D.; Ferreira, C. S. S.; Stoof, C. R.; Urbanek, E.; Walsh, R. P. D.

2009-04-01

Prescribed fire (or a controlled burn) is a management tool used in wildfire-prone areas to reduce the fuel load of living and dead biomass, while attempting to keep disturbance of the ground surface and soil to a minimum. We know that wildfire, particularly of moderate or extreme severity, can cause important changes to the chemical and physical properties of soil, typically leading to a reduction in aggregate stability, surface roughness and water storage capacity, and an increase in overland flow. It has also been shown that wildfire disturbance can cause major loss of soil, particularly at plot and hillslope scales. There is less information on soil losses at catchment scales, but it is known that losses particularly of organic-rich fine sediment and nutrients can undergo hillslope to channel transfer, where they can affect water quality. Far less research has been carried out into the effects of prescribed fire on soil and nutrient losses at all scales, but particularly at catchment scales. This paper considers the impact of an experimental fire (equivalent to a severe prescribed fire) on soil and nutrient losses. These losses have been monitored at a range of scales (small rainfall simulation plots, long-term erosion plot, erosion plot, hillslope sediment traps (sediment fences) and catchment) before and after the fire in a 10-ha catchment near Góis, central Portugal, which forms part of the 5-year DESIRE research programme concerning desertification and its mitigation at a range of study sites worldwide. The catchment has steep slopes covered mainly with scrub vegetation ranging from c. 0.15 to 2m in height. The soil is thin, stony and highly water repellent. Long-term pre-burn erosion rates are known from a c. 10-year record of soil losses from a small erosion plot (8 x 2m in size) and sediment accumulation in the weir pool of a subcatchment gauging station. Rainfall simulations carried out under dry and wet antecedent conditions before and after the fire, eroded soil collected in sediment fences installed in strategic locations on the catchment slopes and suspended sediment and bedload determinations at the catchment gauging station provide the evidence for pre- and post-fire erosional losses. Comparison with wildfire effects is provided by instrumented scrub-covered hillslopes burnt in early summer 2008 in the same area. In addition to monitoring soil losses in the small catchment, losses of selected nutrients in eroded soil and runoff together with determinations of pre- and post-fire vegetation cover, fuel loads and soil water repellency have been determined. The soil degradational implications are discussed and placed in the context of the literature on prescribed fire and wildfire impacts from elsewhere in the Mediterranean and from further afield.

Variation and significance of surface heat after the mechanical sand control of Qinghai-Tibet Railway was covered with sandy sediments

NASA Astrophysics Data System (ADS)

Xie, Shengbo; Qu, Jianjun; Mu, Yanhu; Xu, Xiangtian

Mechanical control of drifting sand used to protect the Qinghai-Tibet Railway from sand damage inevitably results in sand deposition, and the change in radiation and heat flux after the ground surface is covered with sandy sediments remains unclear. These variations were studied in this work through field observations along with laboratory analyses and tests. After the ground surface was covered with sandy sediments produced by the mechanical control of sand in the Qinghai-Tibet Railway, the reflectivity increased, and the annual average reflectivity on the surface covered with sandy sediments was higher than that without sandy sediments, with the value increasing by 0.043. Moreover, the surface shortwave radiation increased, whereas the surface net radiation decreased. The annual average value of the surface shortwave radiant flux density on the sandy sediments was higher than that without sandy sediments, with the value increasing by 7.291 W·m-2. The annual average value of the surface net radiant flux density on the sandy sediments decreased by 9.639 W·m-2 compared with that without sandy sediments. The soil heat flux also decreased, and the annual average value of the heat flux in the sandy sediments decreased by 0.375 W·m-2 compared with that without sandy sediments. These variations caused the heat source on the surface of sandy sediments underground to decrease, which is beneficial for preventing permafrost from degradation in the section of sand control of the railway.

Impacts of tracked vehicles on sediment from a desert soil

Treesearch

Erek H. Fuchs; Karl M. Wood; Tim L. Jones; Brent Racher

2003-01-01

Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had...

Riparian soil development linked to forest succession above and below dams along the Elwha River, Washington, USA

USGS Publications Warehouse

Perry, Laura G; Shafroth, Patrick B.; Perakis, Steven

2017-01-01

Riparian forest soils can be highly dynamic, due to frequent fluvial disturbance, erosion, and sediment deposition, but effects of dams on riparian soils are poorly understood. We examined soils along toposequences within three river segments located upstream, between, and downstream of two dams on the Elwha River to evaluate relationships between riparian soil development and forest age, succession, and channel proximity, explore dam effects on riparian soils, and provide a baseline for the largest dam removal in history. We found that older, later-successional forests and geomorphic surfaces contained soils with finer texture and greater depth to cobble, supporting greater forest floor mass, mineral soil nutrient levels, and cation exchange. Forest stand age was a better predictor than channel proximity for many soil characteristics, though elevation and distance from the channel were often also important, highlighting how complex interactions between fluvial disturbance, sediment deposition, and biotic retention regulate soil development in this ecosystem. Soils between the dams, and to a lesser extent below the lower dam, had finer textures and higher mineral soil carbon, nitrogen, and cation exchange than above the dams. These results suggested that decreased fluvial disturbance below the dams, due to reduced sediment supply and channel stabilization, accelerated soil development. In addition, reduced sediment supply below the dams may have decreased soil phosphorus. Soil δ15N suggested that salmon exclusion by the dams had no discernable effect on nitrogen inputs to upstream soils. Recent dam removal may alter riparian soils further, with ongoing implications for riparian ecosystems.

40 CFR 434.80 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... grubbing area means the area where woody plant materials that would interfere with soil salvage operations have been removed or incorporated into the soil that is being salvaged. (b) The term regraded area... sediment yield means the sum of the soil losses from a surface minus deposition in macro-topographic...

40 CFR 434.80 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... grubbing area means the area where woody plant materials that would interfere with soil salvage operations have been removed or incorporated into the soil that is being salvaged. (b) The term regraded area... sediment yield means the sum of the soil losses from a surface minus deposition in macro-topographic...

A Simple Close Range Photogrammetry Technique to Assess Soil Erosion in the Field

USDA-ARS?s Scientific Manuscript database

Evaluating the performance of a soil erosion prediction model depends on the ability to accurately measure the gain or loss of sediment in an area. Recent development in acquiring detailed surface elevation data (DEM) makes it feasible to assess soil erosion and deposition spatially. Digital photogr...

40 CFR 264.552 - Corrective Action Management Units (CAMU).

Code of Federal Regulations, 2014 CFR

2014-07-01

... (FML), and the lower component must consist of at least a two-foot layer of compacted soil with a... hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris... with the compacted soil component; (ii) Alternate requirements. The Regional Administrator may approve...

40 CFR 264.552 - Corrective Action Management Units (CAMU).

Code of Federal Regulations, 2012 CFR

2012-07-01

... (FML), and the lower component must consist of at least a two-foot layer of compacted soil with a... hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris... with the compacted soil component; (ii) Alternate requirements. The Regional Administrator may approve...

40 CFR 264.552 - Corrective Action Management Units (CAMU).

Code of Federal Regulations, 2010 CFR

2010-07-01

... (FML), and the lower component must consist of at least a two-foot layer of compacted soil with a... hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris... with the compacted soil component; (ii) Alternate requirements. The Regional Administrator may approve...

40 CFR 264.552 - Corrective Action Management Units (CAMU).

Code of Federal Regulations, 2011 CFR

2011-07-01

... (FML), and the lower component must consist of at least a two-foot layer of compacted soil with a... hazardous wastes, and all media (including ground water, surface water, soils, and sediments) and debris... with the compacted soil component; (ii) Alternate requirements. The Regional Administrator may approve...

MORPHOLOGICAL AND CULTURAL COMPARISON OF MICROORGANISMS IN SURFACE SOIL AND SUBSURFACE SEDIMENTS AT A PRISTINE STUDY SITE IN OKLAHOMA (JOURNAL VERSION)

EPA Science Inventory

Surface-soil and subsurface microfloras at the site of a shallow aquifer in Oklahoma were examined and compared with respect to (1) total and viable cell numbers, (2) colony and cell types that grew on various plating media, (3) cell morphologies seen in flotation films stripped ...

Impact of sedimentation on wetland carbon sequestration in an agricultural watershed.

PubMed

McCarty, Gregory; Pachepsky, Yakov; Ritchie, Jerry

2009-01-01

Landscape redistribution of soil C is common within agricultural ecosystems. Little is known about the effects of upland sediment deposition on C dynamics within riparian wetlands. To assess sedimentation impact, we obtained profile samples of wetland soil and used the combination of (137)Cs, (210)Pb, and (14)C chronological markers to determine rates of C sequestration and mineral deposition over the history of a wetland within a first-order catchment under agricultural management in the coastal plains of the United States. Substantial post settlement deposition in the wetland soil was evidenced in places by a 20- to 40-cm layer of mineral soil that buried the original histosol. Soil profiles contained a minimum in C content within the top 35 cm of the profile which originated from a rapid deposition from low C upland soils. Radiocarbon and radioisotope dating showed that increases in C above this minimum were the result of C sequestered in the past approximately 50 yr. Modeling the kinetics of modern C dynamics using the (137)Cs and (210)Pb markers within these surface profiles provides strong evidence for accelerated C sequestration associated with mineral sediment deposition in the ecosystem. These findings indicate that at the landscape scale, dilution of ecosystem C by import of low C upland sediment into wetlands stimulates C sequestration by pulling soil C content below some pedogenic equilibrium value for the ecosystem. They also indicate that over the history of the wetland, rates of C accretion may be linked to mineral soil deposition.

Rainfall simulation experiments to study sediment redistribution using rare earth element oxides as tracers under conventional and conservation agricultural practices

NASA Astrophysics Data System (ADS)

Tóth, Adrienn; Jakab, Gergely; Sipos, Péter; Karlik, Máté; Madarász, Balázs; Zacháry, Dóra; Szabó, Judit; Szalai, Zoltán

2017-04-01

Rare earth elements (REE) have very favourable characteristics for being ideal sediment tracers as they are characterised by strong binding to soil particles, low mobility, low background concentration in soils, environmental benignity, high analytical sensitivity and they can be detected relatively easily and inexpensively in soils. The group of REEs consist of 16 elements with similar chemical properties, but at the same time, they are clearly distinguishable enabling multiple tracking of sediment deriving from different parts of the studied area, as well as mapping redistribution processes by appropriate designing of subareas marked by different REEs. In this study, rainfall simulation experiments were carried out to compare the loss and redistribution of soil sediments in two plots under conventional and conservation agricultural practices. Five different rainfall intensities (up to 80 mm/h) were applied to both plots. Sources and pathways of sediments within the two plots were studied using REE-oxides as tracers. Approximately 1,000 mg/kg of Er2O3, Ho2O3 and Sm2O3 (calculated to the upper 1 cm of the soil) were dispersed to the soil surface with banded distribution; each transversal band covered the third of the surface are of the plots. Concentration of the REE-oxides in the sediment leaving the plots, and that of the surface soil before and after the experiment were analysed by X-Ray fluorescence spectrometry. Significant sediment losses were found for both plots after the experiments, with slightly different characteristics between the conventional and conservation ones. Highest difference in loss of added REEs was found in the upper third of the plots with 81 ± 19% in the conventional and 71 ± 21% in the conservation ones. These values have been equalized downwards with almost complete losses in the lower third of the plots (99 ± 2% and 97 ± 4%, respectively). Only very small part of the removed sediment has been accumulated in the lower parts of the plots, they rather mostly leaved the study area. These accumulation zones showed patchy distribution and could be characterized by slightly higher REE concentrations in the conservation plot. Also, large variances in the REE amounts removed from the study plots were found during the experiment with slight differences between the two plots. Thanks to the use of the REE tracers, information was received not only on the sediment amounts leaving the area due to the individual rainfall events but also on the source of them within the plot. Our data also suggest that differences between the conventional and conservation plots can be observed even in the short term. The authors are grateful to the support of the National Research, Development and Innovation Office (OTKA PD 112729). A. Tóth also thanks for the support of the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.

Crevasse Splays Versus Avulsions: A Recipe for Land Building With Levee Breaches

NASA Astrophysics Data System (ADS)

Nienhuis, Jaap H.; Törnqvist, Torbjörn E.; Esposito, Christopher R.

2018-05-01

Natural-levee breaches can not only initiate an avulsion but also, under the right circumstances, lead to crevasse splay formation and overbank sedimentation. The formative conditions for crevasse splays are not well understood, yet such river sediment diversions form an integral part of billion-dollar coastal restoration projects. Here we use Delft3D to investigate the influence of vegetation and soil consolidation on the evolution of a natural-levee breach. Model simulations show that crevasse splays heal because floodplain aggradation reduces the water surface slope, decreasing water discharge into the flood basin. Easily erodible and unvegetated floodplains increase the likelihood for channel avulsions. Denser vegetation and less potential for soil consolidation result in small crevasse splays that are not only efficient sediment traps but also short-lived. Successful crevasse splays that generate the largest land area gain for the imported sediment require a delicate balance between water and sediment discharge, vegetation root strength, and soil consolidation.

Using semi-variogram analysis for providing spatially distributed information on soil surface condition for land surface modeling

NASA Astrophysics Data System (ADS)

Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

2010-05-01

The ability to quantitatively and spatially assess soil surface roughness is important in geomorphology and land degradation studies. Soils can experience rapid structural degradation in response to land cover changes, resulting in increased susceptibility to erosion and a loss of Soil Organic Matter (SOM). Changes in soil surface condition can also alter sediment detachment, transport and deposition processes, infiltration rates and surface runoff characteristics. Deriving spatially distributed quantitative information on soil surface condition for inclusion in hydrological and soil erosion models is therefore paramount. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially distributed information on soil surface condition. Laser techniques can provide data for a rapid three dimensional representation of the soil surface at a fine spatial resolution. This provides the ability to capture changes at the soil surface associated with aggregate breakdown, flow routing, erosion and sediment re-distribution. Semi-variogram analysis of the laser data can be used to represent spatial dependence within the dataset; providing information about the spatial character of soil surface structure. This experiment details the ability of semi-variogram analysis to spatially describe changes in soil surface condition. Soil for three soil types (silt, silt loam and silty clay) was sieved to produce aggregates between 1 mm and 16 mm in size and placed evenly in sample trays (25 x 20 x 2 cm). Soil samples for each soil type were exposed to five different durations of artificial rainfall, to produce progressively structurally degraded soil states. A calibrated laser profiling instrument was used to measure surface roughness over a central 10 x 10 cm plot of each soil state, at 2 mm sample spacing. The laser data were analysed within a geostatistical framework, where semi-variogram analysis quantitatively represented the change in soil surface structure during crusting. The laser data were also used to create digital surface models (DSM) of the soil states for visual comparison. This research has shown that aggregate breakdown and soil crusting can be shown quantitatively by a decrease in sill variance (silt soil: 11.67 (control) to 1.08 (after 90 mins rainfall)). Features present within semi-variograms were spatially linked to features at the soil surface, such as soil cracks, tillage lines and areas of deposition. Directional semi-variograms were used to provide a spatially orientated component, where the directional sill variance associated with a soil crack was shown to increase from 7.95 to 19.33. Periodicity within semi-variogram was also shown to quantify the spatial scale of soil cracking networks and potentially surface flowpaths; an average distance between soil cracks of 37 mm closely corresponded to the distance of 38 mm shown in the semi-variogram. The results provide a strong basis for the future retrieval of spatio-temporal variations in soil surface condition. Furthermore, the presence of process-based information on hydrological pathways within semi-variograms may work towards an inclusion of geostatisically-derived information in land surface models and the understanding of complex surface processes at different spatial scales.

Development and validation of a runoff and erosion model for lowland drained catchments

NASA Astrophysics Data System (ADS)

Grangeon, Thomas; Cerdan, Olivier; Vandromme, Rosalie; Landemaine, Valentin; Manière, Louis; Salvador-Blanes, Sébastien; Foucher, Anthony; Evrard, Olivier

2017-04-01

Modelling water and sediment transfer in lowland catchments is complex as both hortonian and saturation excess-flow occur in these environments. Moreover, their dynamics was complexified by the installation of tile drainage networks or stream redesign. To the best of our knowledge, few models are able to simulate saturation runoff as well as hortonian runoff in tile-drained catchments. Most of the time, they are used for small scale applications due to their high degree of complexity. In this context, a model of intermediate complexity was developed to simulate the hydrological and erosion processes at the catchment scale in lowland environments. This GIS-based, spatially distributed and lumped model at the event scale uses a theoretical hydrograph to approximate within-event temporal variations. It comprises two layers used to represent surface and subsurface transfers. Observations of soil surface characteristics (i.e. vegetation density, soil crusting and roughness) were used to document spatial variations of physical soil characteristics (e.g. infiltration capacity). Flow was routed depending on the local slope, using LIDAR elevation data. Both the diffuse and the gully erosion are explicitly described. The model ability to simulate water and sediment dynamics at the catchment scale was evaluated using the monitoring of a selection of flood events in a small, extensively cultivated catchment (the Louroux catchment, Loire River basin, central France; 25 km2). In this catchment, five monitoring stations were equipped with water level sensors, turbidity probes, and automatic samplers. Discharge and suspended sediment concentration were deduced from field measurements. One station was installed at the outlet of a tile drain and was used to parameterize fluxes supplied by the drainage network. The selected floods were representative of various rainfall and soil surface conditions (e.g. low-intensity rainfall occurring on saturated soils as well as intense rainfall occurring on dry soils in spring). The model was able to reproduce the runoff volumes for these different situations, and performed well, especially in winter (the relationship between observed and modeled values has R2=0.72) when most of the sediment are transferred. Therefore, future work will evaluate the model ability to reproduce the erosion and sediment dynamics in this catchment in order to provide a tool for sediment management in these lowland environments draining agricultural land where river siltation is problematic.

Elements patterns of soil and river sediments as a tracer of sediment migration

NASA Astrophysics Data System (ADS)

Dordevic, Dragana; Pétursdóttir, Þórunn; Halldórsson, Guðmundur; Sakan, Sanja; Škrivalj, Sandra; Finger, David Christian

2017-04-01

Iceland is the small island on the mid Atlantic ridge, with strong natural catastrophes, such as floods, droughts, landslides, storms and volcanic eruptions that can have devastating impacts on natural and build environment. Rangárvellir area next to Mt Hekla and the glacier Tindfjallajökul has impacted by severe erosion processes but also rich of surface water that play a crucial role in sediment transport processes in the watersheds of the two rivers Eystri-Rangá and Ytri-Rangá. Their sediments consist of various materials originating from volcanoes ash and lava. Difference of contents of various chemical components in sediments and surrounding soil could be bases for identification of erosion processes and watersheds connectivity. River sediment is accumulator of chemical constituents from water in water-sediment interaction, making it as an important material for investigation their migration routes. In order to develop of methods for investigating of sediment migration using their chemical patterns the STSM of Connecteur COST Action ES1306-34336 have been approved. Samples of river sediments and surrounding soils of the Eystri-Rangá and Ytri-Rangá rivers in watersheds of Rangárvellir area as well as primarily volcanic ash from Eyafjallajökull were taken. Sequential extraction of heavy metals and trace elements from collected samples has been applied using the optimized procedure proposed by European Community Bureau of reference (BCR) in the next fractions: 1) soluble in acid - metals that are exchangeable or associated with carbonates; 2) reducible fraction - metals associated with oxides of Fe and Mn; 3) oxidizable fraction - metals associated with organic matter and sulfides and 4) residual fraction - metals strongly associated with the crystalline structure of minerals. Extracted solutions have analyzed by ICP/OES on next elements: Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Sb, Si, Sr, V, Zn. Distributions of Si is the same in all investigated samples of soils, river sediments and volcanic ash pointing to the same their geochemical basis. Some elements like Li and partly B exist in the first phase of volcanic ash and river sediments but no in the first phases of soils as if they were already washed from them and adsorbed on the river sediments surfaces. In the first phase of volcanic ash P was found but no exists in the first phase of soil and river sediments. Total content of Bi is found only in silicate matrix while total contents of As is found only in organic/sulphide form in all investigated samples.

(210)Pb as a tracer of soil erosion, sediment source area identification and particle transport in the terrestrial environment.

PubMed

Matisoff, Gerald

2014-12-01

Although (137)Cs has been used extensively to study soil erosion and particle transport in the terrestrial environment, there has been much less work using excess or unsupported (210)Pb ((210)Pbxs) to study the same processes. Furthermore, since (137)Cs activities in soils are decreasing because of radioactive decay, some locations have an added complication due to the addition of Chernobyl-derived (137)Cs, and the activities of (137)Cs in the southern hemisphere are low, there is a need to develop techniques that use (210)Pbxs to provide estimates of rates of soil erosion and particle transport. This paper reviews the current status of (210)Pbxs methods to quantify soil erosion rates, to identify and partition suspended sediment source areas, and to determine the transport rates of particles in the terrestrial landscape. Soil erosion rates determined using (210)Pbxs are based on the unsupported (210)Pb ((210)Pbxs) inventory in the soil, the depth distribution of (210)Pbxs, and a mass balance calibration ('conversion model') that relates the soil inventory to the erosion rate using a 'reference site' at which neither soil erosion nor soil deposition has occurred. In this paper several different models are presented to illustrate the effects of different model assumptions such as the timing, depth and rates of the surface soil mixing on the calculated erosion rates. The suitability of model assumptions, including estimates of the depositional flux of (210)Pbxs to the soil surface and the post-depositional mobility of (210)Pb are also discussed. (210)Pb can be used as one tracer to permit sediment source area identification. This sediment 'fingerprinting' has been extended far beyond using (210)Pb as a single radioisotope to include numerous radioactive and stable tracers and has been applied to identifying the source areas of suspended sediment based on underlying rock type, land use (roads, stream banks, channel beds, cultivated or uncultivated lands, pasture lands, forested lands, construction sites, undisturbed lands) or style of erosion (sheet wash, rills, bank). The transport time of particles in the terrestrial system can be estimated using (7)Be/(210)Pbxs radionuclide ratios and from mass balance models of (210)Pbxs and/or (7)Be in streams. Watershed residence times can be calculated from the radionuclide inventory and the erosional loss rate. Copyright © 2014 Elsevier Ltd. All rights reserved.

Grain size associations of branched tetraether lipids in soils and riverbank sediments: influence of hydrodynamic sorting processes

NASA Astrophysics Data System (ADS)

Peterse, Francien; Eglinton, Timothy I.

2017-06-01

We analyzed the abundance and distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in grain size fractions of 7 globally distributed river flank sediments and catchment soils in order to determine if and how the initial soil-brGDGT signature is influenced by hydrodynamic sorting upon entering a river and during subsequent transport from land to sea. BrGDGTs are hypothesized to form associations with high-surface-area fine-grained minerals in soils. Such associations, if maintained during transport, may impart resistance to degradation and promote downstream transport, reducing potential interferences by aquatic brGDGTs. We find that brGDGTs are indeed primarily associated with organic carbon (OC) bound to the clay-silt fraction (<63μm) in both soils and river sediments, and that these associations appear to be maintained during river transport. However, the relative distribution of individual brGDGTs among size fractions is relatively uniform, suggesting that brGDGTs are well mixed in river sediments and that OC-mineral associations are continuously renewed. Consequently, the brGDGT signature finally stored in continental margin sediments appears insensitive to differential particle transport processes. Nevertheless, the lower (upstream) temperature signal generally reflected by brGDGTs in river sediments may also be explained by a contribution of in situ produced brGDGTs leading to an underestimation of reconstructed air temperatures.

Occurrence of glyphosate and AMPA in an agricultural watershed from the southeastern region of Argentina.

PubMed

Lupi, Leonardo; Miglioranza, Karina S B; Aparicio, Virginia C; Marino, Damian; Bedmar, Francisco; Wunderlin, Daniel A

2015-12-01

Glyphosate (GLY) and AMPA concentrations were determined in sandy soil profiles, during pre- and post-application events in two agricultural soybean fields (S1 and S2). Streamwater and sediment samples were also analyzed. Post-application sampling was carried out one month later from the event. Concentrations of GLY+AMPA in surface soils (0-5 cm depth) during pre-application period showed values 20-fold higher (0.093-0.163 μg/g d.w.) than control area (0.005 μg/g d.w.). After application event soils showed markedly higher pesticide concentrations. A predominance of AMPA (80%) was observed in S1 (early application), while 34% in S2 for surface soils. GLY+AMPA concentrations decreased with depth and correlated strongly with organic carbon (r between 0.74 and 0.88, p<0.05) and pH (r between -0.81 and -0.76, p<0.001). The slight enrichment of pesticides observed from 25 cm depth to deeper layer, in addition to the alkaline pH along the profile, is of high concern about groundwater contamination. Sediments from pre-application period showed relatively lower pesticide levels (0.0053-0.0263 μg/g d.w.) than surface soil with a predominance of glyphosate, indicating a limited degradation. Levels of contaminants (mainly AMPA) in streamwater (ND-0.5 ng/mL) denote the low persistence of these compounds. However, a direct relationship in AMPA concentration was observed between sediment and streamwater. Despite the known relatively short half-life of glyphosate in soils, GLY+AMPA occurrence is registered in almost all matrices at different sampling times (pre- and post-application events). The physicochemical characteristics (organic carbon, texture, pH) and structure of soils and sediment in addition to the time elapsed from application determined the behavior of these contaminants in the environment. As a whole, the results warn us about vertical transport trough soil profile with the possibility of reaching groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.

Seasonal herbicide monitoring in soil, runoff and sediments of an olive orchard under conventional tillage

NASA Astrophysics Data System (ADS)

Calderón, Maria Jesus; de Luna, Elena; Gómez, José Alfonso; Cornejo, Juan; Hermosín, M. Carmen

2015-04-01

Several pollution episodes in surface and groundwaters with pesticides have occurred in areas where olive crops are established. For that reason, it is necessary to know the evolution of some pesticides in olive trees plantation depending on their seasonal application. This is especially important when conventional tillage is used. A monitoring of two herbicides (terbuthylazine and oxyfluorfen)in the first cm of soil and, in runoff and sediment yield was carried out after several rainfall events. The rainfall occurred during the study was higher in winter than in spring giving rise more runoff in winter. However, no differences in sediment yields were observed between spring and winter. Terbuthylazine depletion from soil is associated to the first important rainfall events in both seasons (41 mm in spring and 30 mm in winter). At the end of the experiment, no terbuthylazine soil residues were recovered in winter whereas 15% of terbuthylazine applied remained in spring. Oxyfluorfen showed a character more persistent than terbuthylazine remaining 48% of the applied at the end of the experiment due to its low water solubility. Higher percentage from the applied of terbuthylazine was recovered in runoff in winter (0.55%) than in spring (0.17%). Nevertheless, no differences in terbuthylazine sediments yields between both seasons were observed. That is in agreement with the values of runoff and sediment yields accumulated in tanks in both seasons. Due to the low water solubility of oxyfluorfen very low amount of this herbicide was recovered in runoff. Whereas, in sediment yields the 39.5% of the total applied was recovered. These data show that the dissipation of terbuthylazine from soil is closely related with leaching processes and in less extent with runoff. However, oxyfluorfen dissipation is more affected by runoff processes since this herbicide is co-transported in sediment yields. Keywords: olive crop, pesticide, runoff, sediments, surface water, groundwater Acknowledgments: P08-AGR-03643, P11-AGR-7400, JA (AGR-264) partially finnanced with FEDER-FSE (OP 2007-13).and FACCE-JPI (Designchar4food).

Erosion and Sediment Transport Modelling in Shallow Waters: A Review on Approaches, Models and Applications.

PubMed

Hajigholizadeh, Mohammad; Melesse, Assefa M; Fuentes, Hector R

2018-03-14

The erosion and sediment transport processes in shallow waters, which are discussed in this paper, begin when water droplets hit the soil surface. The transport mechanism caused by the consequent rainfall-runoff process determines the amount of generated sediment that can be transferred downslope. Many significant studies and models are performed to investigate these processes, which differ in terms of their effecting factors, approaches, inputs and outputs, model structure and the manner that these processes represent. This paper attempts to review the related literature concerning sediment transport modelling in shallow waters. A classification based on the representational processes of the soil erosion and sediment transport models (empirical, conceptual, physical and hybrid) is adopted, and the commonly-used models and their characteristics are listed. This review is expected to be of interest to researchers and soil and water conservation managers who are working on erosion and sediment transport phenomena in shallow waters. The paper format should be helpful for practitioners to identify and generally characterize the types of available models, their strengths and their basic scope of applicability.

Erosion and Sediment Transport Modelling in Shallow Waters: A Review on Approaches, Models and Applications

PubMed Central

Fuentes, Hector R.

2018-01-01

The erosion and sediment transport processes in shallow waters, which are discussed in this paper, begin when water droplets hit the soil surface. The transport mechanism caused by the consequent rainfall-runoff process determines the amount of generated sediment that can be transferred downslope. Many significant studies and models are performed to investigate these processes, which differ in terms of their effecting factors, approaches, inputs and outputs, model structure and the manner that these processes represent. This paper attempts to review the related literature concerning sediment transport modelling in shallow waters. A classification based on the representational processes of the soil erosion and sediment transport models (empirical, conceptual, physical and hybrid) is adopted, and the commonly-used models and their characteristics are listed. This review is expected to be of interest to researchers and soil and water conservation managers who are working on erosion and sediment transport phenomena in shallow waters. The paper format should be helpful for practitioners to identify and generally characterize the types of available models, their strengths and their basic scope of applicability. PMID:29538335

METHODS FOR THE DETERMINATION OF TOTAL ORGANIC ...

EPA Pesticide Factsheets

Organic matter in soils and sediments is widely distributed over the earth's surface occurring in almost all terrestrial and aquatic environments (Schnitzer, 1978). Soils and sediments contain a large variety of organic materials ranging from simple sugars and carbohydrates to the more complex proteins, fats, waxes, and organic acids. Important characteristics of the organic matter include their ability to: form water-soluble and water- insoluble complexes with metal ions and hydrous oxides; interact with clay minerals and bind particles together; sorb and desorb both naturally-occurring and anthropogenically-introduced organic compounds; absorb and release plant nutrients; and hold water in the soil environment. As a result of these characteristics, the determination of total organic carbon (a measure of one of the chemical components of organic matter that is often used as an indicator of its presence in a soil or sediment) is an essential part of any site characterization since its presence or absence can markedly influence how chemicals will react in the soil or sediment. Soil and sediment total organic carbon (TOC) determinations are typically requested with contaminant analyses as part of an ecological risk assessment data package. TOC contents may be used qualitatively to assess the nature of the sampling location (e.g., was it a depositional area) or may be used to normalize portions of the analytical chemistry data set (e.g., equilibrium partitioning).

Role of freeze-thaw cycles and chlorpyrifos insecticide use on diffuse Cd loss and sediment accumulation

NASA Astrophysics Data System (ADS)

Wang, Fangli; Ouyang, Wei; Hao, Fanghua; Jiao, Wei; Shan, Yushu; Lin, Chunye

2016-06-01

Freeze-thaw cycles are predicted to increase in cold temperate regions. The potential influence of the interactions of freeze-thaw cycles and agrochemicals on the release of Cd into river water is unknown. In this study, the interactions of freeze-thaw cycles and chlorpyrifos (FC) on Cd mobility in soils were analysed. The spatial variability of soil Cd under long-term intensive tillage in a freeze-thaw agro-system was also identified. The temporal variation of sediment Cd was detected based on analysis of the sediment geochemistry. The results showed that FC increased soil Cd mobility, with an increase of approximately 10% in CaCl2-extractable Cd. The increased mobile fractions of water-soluble and exchangeable Cd originated from the decreased fraction of Fe-Mn-oxide-associated Cd and organic matter-bound Cd. The total Cd content in the surface soil followed the zonally decreasing trend of dry land > paddy land > natural land. The Cd concentrations and sedimentation rates of the sediment core generally increased from 1943 to 2013 due to agricultural exploration and farmland irrigation system construction, indicating an increase of the Cd input flux into water. The results provide valuable information about the soil Cd transport response to the influence of climatic and anthropogenic factors in cold intensive agro-systems.

Spectroscopic analyses of soil samples outside Nile Delta of Egypt

NASA Astrophysics Data System (ADS)

Fakhry, Ahmed; Osman, Osama; Ezzat, Hend; Ibrahim, Medhat

2016-11-01

Soil in Egypt, especially around Delta is exposed to various pollutants which are affecting adversely soil fertility and stability. Humic Acids (HA) as a main part of soil organic matter (SOM) represent the heart of the interaction process of inorganic pollutants with soil. Consequently, Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonances (NMR) were used to characterize soil, sediment and extracted HA. Resulting data confirmed that the HA was responsible for transporting inorganic pollutants from surface to subsurface reaching the ground water, which may represent a high risk on public health. The transport process is coming as carboxyl in surface soil changed into metal carboxylate then transferred into the carboxyl in bottom soil.

Preliminary study on detection sediment contamination in soil affected by the Indian Ocean giant tsunami 2004 in Aceh, Indonesia using laser-induced breakdown spectroscopy (LIBS)

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

Idris, Nasrullah, E-mail: nasrullah.idris@unsyiah.ac.id; Ramli, Muliadi; Hedwig, Rinda

This work is intended to asses the capability of LIBS for the detection of the tsunami sediment contamination in soil. LIBS apparatus used in this work consist of a laser system and an optical multichannel analyzer (OMA) system. The soil sample was collected from in Banda Aceh City, Aceh, Indonesia, the most affected region by the giant Indian Ocean tsunami 2004. The laser beam was focused onto surface of the soil pellet using a focusing lens to produce luminous plasma. The experiment was conducted under air as surrounding gas at 1 atmosphere. The emission spectral lines from the plasma weremore » detected by the OMA system. It was found that metal including heavy metals can surely be detected, thus implying the potent of LIBS technique as a fast screening tools of tsunami sediment contamination.« less

Development of a Sediment Transport Component for DHSVM

NASA Astrophysics Data System (ADS)

Doten, C. O.; Bowling, L. C.; Maurer, E. P.; Voisin, N.; Lettenmaier, D. P.

2003-12-01

The effect of forest management and disturbance on aquatic resources is a problem of considerable, contemporary, scientific and public concern in the West. Sediment generation is one of the factors linking land surface conditions with aquatic systems, with implications for fisheries protection and enhancement. Better predictive techniques that allow assessment of the effects of fire and logging, in particular, on sediment transport could help to provide a more scientific basis for the management of forests in the West. We describe the development of a sediment transport component for the Distributed Hydrology Soil Vegetation Model (DHSVM), a spatially distributed hydrologic model that was developed specifically for assessment of the hydrologic consequences of forest management. The sediment transport module extends the hydrologic dynamics of DHSVM to predict sediment generation in response to dynamic meteorological inputs and hydrologic conditions via mass wasting and surface erosion from forest roads and hillslopes. The mass wasting component builds on existing stochastic slope stability models, by incorporating distributed basin hydrology (from DHSVM), and post-failure, rule-based redistribution of sediment downslope. The stochastic nature of the mass wasting component allows specification of probability distributions that describe the spatial variability of soil and vegetation characteristics used in the infinite slope model. The forest roads and hillslope surface erosion algorithms account for erosion from rain drop impact and overland erosion. A simple routing scheme is used to transport eroded sediment from mass wasting and forest roads surface erosion that reaches the channel system to the basin outlet. A sensitivity analysis of the model input parameters and forest cover conditions is described for the Little Wenatchee River basin in the northeastern Washington Cascades.

How mangrove forests adjust to rising sea level

USGS Publications Warehouse

Krauss, Ken W.; McKee, Karen L.; Lovelock, Catherine E.; Cahoon, Donald R.; Saintilan, Neil; Reef, Ruth; Chen, Luzhen

2014-01-01

Mangroves are among the most well described and widely studied wetland communities in the world. The greatest threats to mangrove persistence are deforestation and other anthropogenic disturbances that can compromise habitat stability and resilience to sea-level rise. To persist, mangrove ecosystems must adjust to rising sea level by building vertically or become submerged. Mangroves may directly or indirectly influence soil accretion processes through the production and accumulation of organic matter, as well as the trapping and retention of mineral sediment. In this review, we provide a general overview of research on mangrove elevation dynamics, emphasizing the role of the vegetation in maintaining soil surface elevations (i.e. position of the soil surface in the vertical plane). We summarize the primary ways in which mangroves may influence sediment accretion and vertical land development, for example, through root contributions to soil volume and upward expansion of the soil surface. We also examine how hydrological, geomorphological and climatic processes may interact with plant processes to influence mangrove capacity to keep pace with rising sea level. We draw on a variety of studies to describe the important, and often under-appreciated, role that plants play in shaping the trajectory of an ecosystem undergoing change.

ASSESSING THE MOBILITY OF ARSENIC IN CONTAMINATED SEDIMENTS

EPA Science Inventory

The mobility of arsenic is controlled, in part, by partitioning to mineral surfaces in soils and sediments. Determination of the risk posed to human or ecosystem health by arsenic and identification of remediation technologies that could be employed to eliminate or reduce risk i...

Roughness configuration matters for aeolian sediment flux

USDA-ARS?s Scientific Manuscript database

The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of s...

Mercury emission and distribution: Potential environmental risks at a small-scale gold mining operation, Phichit Province, Thailand.

PubMed

Pataranawat, Poranee; Parkpian, Preeda; Polprasert, Chongrak; Delaune, R D; Jugsujinda, A

2007-07-01

Mercury (Hg) contamination was assessed in environment near an amalgamation gold recovery operation located at a small scale mining operation (Phanom Pha) in Phichit Province, Thailand. Total mercury (THg) concentrations was determined in water, sediment, bivalves in the aquatic environment and as dry deposition or atmospheric fallout on surface soil and leaves of Neem tree (Azadirachta indica Juss. var. siamensis Valeton) near the mining operation. THg in surface soil, Neem flowers (edible part) and rice grain in surrounding terrestrial habitat and with distance from the mining area were also evaluated for possible contamination. Potential environmental risks were evaluated using the hazard quotient equation. Hg analyses conducted in the aquatic habitat showed that THg in water, sediment and bivalves (Scabies cripata Gould) ranged from 0.4 to 4 microg L(-1), 96 to 402 microg kg(-1)dry weight (dw) and 15 to 584 microg kg(-1) wet weight (ww), respectively. High concentrations of THg in water, sediment and bivalves were observed in the receiving stream near the mining operation which was located near the Khao Chet Luk Reservoir. Whereas the THg concentration in water, sediment and bivalves from monitoring stations outside the gold mining operation (upstream and downstream), were considerably lower with the values of 0.4-0.8 microg L(-1), 96-140 microg kg(-1) dw and 88-658 microg kg(-1) dw, respectively. The elevated concentration of Hg found in the sediment near the mining operation was consistent with Hg accumulation measured in bivalves. The elevated Hg levels found in living bivalves collected from highly contaminated sites suggested that the sediment bound Hg was bioavailable. THg in surface soils, brown rice grain (Jasmine rice #105) and Neem flowers of terrestrial habitats were in the range of 16 to 180 microg kg(-1) dw, 190 to 300 microg kg(-1) dw, and 622 to 2150 microg kg(-1) dw, respectively. Elevated concentrations of mercury were found in Neem flowers with the concentration greater than 600 microg kg(-1) ww, which exceeds the maximum permissible concentration reported for biota tissue (500 microg kg(-1) ww). An evaluation of air and soil pollution near the mining operations showed high concentrations of THg in dry deposit from atmospheric fallout (139 microg m(-2) d(-1)), and in surface soil (10,564 microg kg(-1) dw) at station near where open burning of gold ore extracts using the amalgamation process occurred. High or elevated concentration of THg (1172-1301 microg kg(-1) dw) in leaves of Neem tree was also measured near the mining operations. A survey of Hg in surface soil showed elevated Hg concentrations near the site which corresponded to the elevated THg concentration in dry deposition. These results suggested that atmospheric fallout is a major source of Hg to the area surrounding the mining or gold ore extraction. Results also suggest that Hg emitted into the air (estimated to be 60-150 g d(-1)) from the gold mining activities (over the past 10 years) contaminated air, the aquatic environment, surface soil and biota in the area surrounding the gold mining operation.

Effects of traffic and ditch maintenance on forest road sediment production

Treesearch

Charles H. Luce; Thomas A. Black

2001-01-01

Observations of sediment yield from road segments in the Oregon Coast Range show that either heavy traffic during rainfall or blading the road ditch will increase erosion from forest roads. For the fine soils and high quality aggregate surfacing on the study plots, ditch blading increased sediment yield more than traffic equivalent to 12 log trucks per day. The...

Soil erosion and sediment fluxes analysis: a watershed study of the Ni Reservoir, Spotsylvania County, VA, USA.

PubMed

Pope, Ian C; Odhiambo, Ben K

2014-03-01

Anthropogenic forces that alter the physical landscape are known to cause significant soil erosion, which has negative impact on surface water bodies, such as rivers, lakes/reservoirs, and coastal zones, and thus sediment control has become one of the central aspects of catchment management planning. The revised universal soil loss equation empirical model, erosion pins, and isotopic sediment core analyses were used to evaluate watershed erosion, stream bank erosion, and reservoir sediment accumulation rates for Ni Reservoir, in central Virginia. Land-use and land cover seems to be dominant control in watershed soil erosion, with barren land and human-disturbed areas contributing the most sediment, and forest and herbaceous areas contributing the least. Results show a 7 % increase in human development from 2001 (14 %) to 2009 (21.6 %), corresponding to an increase in soil loss of 0.82 Mg ha(-1) year(-1) in the same time period. (210)Pb-based sediment accumulation rates at three locations in Ni Reservoir were 1.020, 0.364, and 0.543 g cm(-2) year(-1) respectively, indicating that sediment accumulation and distribution in the reservoir is influenced by reservoir configuration and significant contributions from bedload. All three locations indicate an increase in modern sediment accumulation rates. Erosion pin results show variability in stream bank erosion with values ranging from 4.7 to 11.3 cm year(-1). These results indicate that urban growth and the decline in vegetative cover has increased sediment fluxes from the watershed and poses a significant threat to the long-term sustainability of the Ni Reservoir as urbanization continues to increase.

Herbicide monitoring in soil, runoff waters and sediments in an olive orchard.

PubMed

Calderon, Maria Jesus; De Luna, Elena; Gomez, Jose Alfonso; Hermosin, M Carmen

2016-11-01

Occurrences of surface water contamination by herbicides in areas where olive orchards are established reveal a need to understand soil processes affecting herbicide fate at field scale for this popular Mediterranean crop. A monitoring study with two herbicides (terbuthylazine and oxyfluorfen) in the first 2cm of soil, runoff waters, and sediments, was carried out after under natural rainfall conditions following winter herbicide application. At the end of the 107day field experiment, no residues of the soil applied terbuthylazine were recovered, whereas 42% of the oxyfluorfen applied remained in the top soil. Very low levels of both herbicides were measured in runoff waters; however, concentrations were slightly higher for terbuthylazine (0.53% of applied) than for oxyfluorfen (0.03% of applied), relating to their respective water solubilities. Congruent with soil residue data, 38.15% of the applied oxyfluorfen was found in runoff-sediment, compared to only 0.46% for terbuthylazine. Accordingly, the herbicide soil distribution coefficients measured within runoff field tanks was much greater for oxyfluorfen (Kd=3098) than for terbuthylazine (Kd=1.57). The herbicide oxyfluorfen is co-transported with sediment in runoff, remaining trapped and/or adsorbed to soil particle aggregates, due in part to its low water solubility. In contrast, terbuthylazine soil dissipation may be associated more so with leaching processes, favored by its high water solubility, low sorption, and slow degradation. By comparing these two herbicides, our results reaffirm the importance of herbicide physico-chemical properties in dictating their behavior in soil and also suggest that herbicides with low solubility, as seen in the case oxyfluorfen, remain susceptible to offsite transport associated with sediments. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of water harvesting techniques on runoff, sedimentation, and soil properties.

PubMed

Al-Seekh, Saleh H; Mohammad, Ayed G

2009-07-01

This study addressed the hydrological processes of runoff and sedimentation, soil moisture content, and properties under the effect of different water harvesting techniques (treatments). The study was conducted at three sites, representing environmental condition gradients, located in the southern part of the West Bank. For each treatment, the study evaluated soil chemical and physical properties, soil moisture at 30 cm depth, surface runoff and sedimentation at each site. Results showed that runoff is reduced by 65-85% and sedimentation by 58-69% in stone terraces and semi-circle bunds compared to the control at the semi-humid site. In addition, stone terraces and contour ridges significantly reduced the amount of total runoff by 80% and 73%, respectively, at the arid site. Soil moisture content was significantly increased by water harvesting techniques compared to the control in all treatments at the three study sites. In addition, the difference between the control and the water harvesting structures were higher in the arid and semi-arid areas than in the semi-humid area. Soil and water conservation, via utilization of water harvesting structures, is an effective principle for reducing the negative impact of high runoff intensity and subsequently increasing soil moisture storage from rainfall. Jessour systems in the valley and stone terraces were effective in increasing soil moisture storage, prolonging the growing season for natural vegetation, and decreasing the amount of supplemental irrigation required for growing fruit trees.

The Effect of Water Harvesting Techniques on Runoff, Sedimentation, and Soil Properties

NASA Astrophysics Data System (ADS)

Al-Seekh, Saleh H.; Mohammad, Ayed G.

2009-07-01

This study addressed the hydrological processes of runoff and sedimentation, soil moisture content, and properties under the effect of different water harvesting techniques (treatments). The study was conducted at three sites, representing environmental condition gradients, located in the southern part of the West Bank. For each treatment, the study evaluated soil chemical and physical properties, soil moisture at 30 cm depth, surface runoff and sedimentation at each site. Results showed that runoff is reduced by 65-85% and sedimentation by 58-69% in stone terraces and semi-circle bunds compared to the control at the semi-humid site. In addition, stone terraces and contour ridges significantly reduced the amount of total runoff by 80% and 73%, respectively, at the arid site. Soil moisture content was significantly increased by water harvesting techniques compared to the control in all treatments at the three study sites. In addition, the difference between the control and the water harvesting structures were higher in the arid and semi-arid areas than in the semi-humid area. Soil and water conservation, via utilization of water harvesting structures, is an effective principle for reducing the negative impact of high runoff intensity and subsequently increasing soil moisture storage from rainfall. Jessour systems in the valley and stone terraces were effective in increasing soil moisture storage, prolonging the growing season for natural vegetation, and decreasing the amount of supplemental irrigation required for growing fruit trees.

Effect of salinity on heavy metal mobility and availability in intertidal sediments of the Scheldt estuary

NASA Astrophysics Data System (ADS)

Du Laing, G.; De Vos, R.; Vandecasteele, B.; Lesage, E.; Tack, F. M. G.; Verloo, M. G.

2008-05-01

The effect of the flood water salinity on the mobility of heavy metals was studied for intertidal sediments of the Scheldt estuary (Belgium). Soils and sediments of 4 sampling sites were flooded with water of different salinities (0.5, 2.5, and 5 g NaCl L -1). Metal concentrations were monitored in pore water and surface water. To study the potential effects of flood water salinity on metal bioavailability, duckweed ( Lemna minor) was grown in the surface water. The salinity was found to primarily enhance the mobility of Cd and its uptake by duckweed. Cadmium concentrations in pore water of soils and sediments and surrounding surface waters significantly exceeded sanitation thresholds and quality standards during flooding of initially oxidized sediments. Moreover, the effect was observed already at lower salinities of 0.5 g NaCl L -1. This implies that risks related to Cd uptake by organisms and Cd leaching to ground water are relevant when constructing flooding areas in the brackish zones of estuaries. These risks can be reduced by inducing sulphide precipitation because Cd is then immobilised as sulphide and its mobility becomes independent of flood water salinity. This could be achieved by permanently flooding the polluted sediments, because sulphates are sufficiently available in the river water of the brackish part of the estuary.

Distribution and biogeochemical controls on net methylmercury production in Penobscot River marshes and sediment.

PubMed

Gilmour, Cynthia; Bell, James Tyler; Soren, Ally Bullock; Riedel, Georgia; Riedel, Gerhardt; Kopec, A Dianne; Bodaly, R A

2018-06-01

The distribution of mercury and methylmercury (MeHg) in sediment, mudflats, and marsh soils of the Hg-contaminated tidal Penobscot River was investigated, along with biogeochemical controls on production. Average total Hg in surface samples (0-3 cm) ranged from 100 to 1200 ng/g; average MeHg ranged from 5 to 50 ng/g. MeHg was usually highest at or near the surface except in highly mobile mudflats. Although total Hg concentrations in the Penobscot are elevated, it is the accumulation of MeHg that stands out in comparison to other ecosystems. Surface soils in the large Mendall Marsh, about 17 km downstream from the contamination source, contained particularly high %MeHg (averaging 8%). In Mendall marsh soil porewaters, MeHg often accounted for more than half of total Hg. Salt marshes are areas of particular concern in the Penobscot River, for they are depositional environments for a Hg-contaminated mobile pool of river sediment, hot spots for net MeHg production, and sources of risk to marsh animals. We hypothesized that exceptionally low mercury partitioning between the solid and aqueous phases (with log K d averaging ~4.5) drives high MeHg in Penobscot marshes. The co-occurrence of iron and sulfide in filtered soil porewaters, sometimes both above 100 μM, suggests the presence of nanoparticulate and/or colloidal metal sulfides. These colloids may be stabilized by high concentrations of aromatic and potentially sulfurized dissolved organic matter (DOM) in marsh soils. Thus, Hg in Penobscot marsh soils appears to be in a highly available for microbial methylation through the formation of DOM-associated HgS complexes. Additionally, low partitioning of MeHg to marsh soils suggests high MeHg bioavailability to animals. Overall, drivers of high MeHg in Penobscot marshes include elevated Hg in soils, low partitioning of Hg to solids, high Hg bioavailability for methylation, rapidly shifting redox conditions in surface marsh soils, and high rates of microbial activity. Copyright © 2018 Elsevier B.V. All rights reserved.

Sedimentation and associated trace metal enrichment in the riparian zone of the Three Gorges Reservoir, China.

PubMed

Tang, Qiang; Bao, Yuhai; He, Xiubin; Zhou, Huaidong; Cao, Zhijing; Gao, Peng; Zhong, Ronghua; Hu, Yunhua; Zhang, Xinbao

2014-05-01

Impoundment of the Three Gorges Reservoir has created an artificial riparian zone with a vertical height of 30 m and a total area of 349 km(2), which has been subjected to seasonal inundation and exposure due to regular reservoir impoundment and the occurrence of natural floods. The significant alteration of hydrologic regime has caused numerous environmental changes. The present study investigated the magnitude and spatial pattern of sedimentation and metal enrichment in a typical section of the riparian zone, composed of bench terraces with previous agricultural land uses, and explored their links to the changed hydrologic regime. In particular, we measured the total sediment depths and collected surface riparian sediments and down-profile sectioned riparian soils (at 5 cm intervals) for trace metal determination. Our analysis showed that the annual average sedimentation rates varied from 0.5 to 10 cm·yr(-1) and they decreased significantly with increasing elevation. This lateral distribution was principally attributed to seasonal variations in water levels and suspended sediment concentrations. Enriched concentrations of trace metals were found both in the riparian sediments and soils, but they were generally higher in the riparian sediments than in riparian soils and followed a similar lateral decreasing trend. Metal contamination assessment showed that the riparian sediments were slightly contaminated by Ni, Zn, and Pb, moderately contaminated by Cu, and moderately to strongly contaminated by Cd; while riparian soils were slightly contaminated by As, and moderately contaminated by Cd. Trace metal enrichment in the riparian sediments may be attributed to external input of contaminated sediments produced from upstream anthropogenic sources and chemical adsorption from dissolved fractions during pure sediment mobilization and after sink for a prolonged flooding period due to reservoir impoundment. Copyright © 2014 Elsevier B.V. All rights reserved.

Volume change associated with formation and dissociation of hydrate in sediment

USGS Publications Warehouse

Ruppel, Carolyn D.; Lee, J.Y.; Santamarina, J. Carlos

2017-01-01

Gas hydrate formation and dissociation in sediments are accompanied by changes in the bulk volume of the sediment and can lead to changes in sediment properties, loss of integrity for boreholes, and possibly regional subsidence of the ground surface over areas where methane might be produced from gas hydrate in the future. Experiments on sand, silts, and clay subject to different effective stress and containing different saturations of hydrate formed from dissolved phase tetrahydrofuran are used to systematically investigate the impact of gas hydrate formation and dissociation on bulk sediment volume. Volume changes in low specific surface sediments (i.e., having a rigid sediment skeleton like sand) are much lower than those measured in high specific surface sediments (e.g., clay). Early hydrate formation is accompanied by contraction for all soils and most stress states in part because growing gas hydrate crystals buckle skeletal force chains. Dilation can occur at high hydrate saturations. Hydrate dissociation under drained, zero lateral strain conditions is always associated with some contraction, regardless of soil type, effective stress level, or hydrate saturation. Changes in void ratio during formation-dissociation decrease at high effective stress levels. The volumetric strain during dissociation under zero lateral strain scales with hydrate saturation and sediment compressibility. The volumetric strain during dissociation under high shear is a function of the initial volume average void ratio and the stress-dependent critical state void ratio of the sediment. Other contributions to volume reduction upon hydrate dissociation are related to segregated hydrate in lenses and nodules. For natural gas hydrates, some conditions (e.g., gas production driven by depressurization) might contribute to additional volume reduction by increasing the effective stress.

Mineralogy and arsenic mobility in arsenic-rich Brazilian soils and sediments

USGS Publications Warehouse

de Mello, J.W.V.; Roy, W.R.; Talbott, J.L.; Stucki, J.W.

2006-01-01

Background. Soils and sediments in certain mining regions of Brazil contain an unusually large amount of arsenic (As), which raises concerns that mining could promote increased As mobility, and thereby increase the risks of contaminating water supplies. Objectives. The purpose of t his study was to identify the most important factors governing As mobility in sediments and soils near three gold-mining sites in the State of Minas Gerais, Brazil. Methods. Surface and sub-surface soil samples were collected at those sites and characterized by chemical and mineralogical analyses. Oxalate (Feo) and citrate-bicarbonate-dithionite (Fed) iron contents were determined by atomic absorption spectroscopy (AAS). Arsenic mobilization was measured after incubating the samples in a 2.5 mM CaCl2 solution under anaerobic conditions for 1, 28, 56, 84, or 112 days. The solution concentrations of As, Fe, and Mn were then measured by inductively coupled plasma-mass spectrometry (ICP-MS) and AAS, respectively. Results and Discussion. Results indicated that As mobilization is largely independent of both the total As and the Feo/Fed ratio of the solid phase. Soluble As is roughly controlled by the Fe (hydr)oxide content of the soil, but a closer examination of the data revealed the importance of other highly weathered clay minerals and organic matter. Large amounts of organic matter and a low iron oxide content should favor As leaching from soils and sediments. Under reducing conditions, As is mobilized by the reductive dissolution of Fe and/or Mn oxides. However, released As may be readsorbed depending on the sorptive properties of the soil. Gibbsite is particularly effective in adsorbing or readsorbing As, as is the remaining unreduced fraction of the iron (hydr)oxides. Conclusion and Outlook. In general, low soluble As is rel ated to the presence of gibbsite, a large amount of iron oxides, and a lack of organic matter in the solid phase. This has environmental significance because gibbsite is thermodynamically more stable than Fe oxides under anaerobic conditions, such as those found in waterlogged soils and lake sediments. ?? 2006 ecomed publishers (Verlagsgruppe Hu??thig Jehle Rehm GmbH), D-86899 Landsberg and Tokyo.

Nontronite Stability in Near-Surface Sediments

NASA Astrophysics Data System (ADS)

Home, C.; Baker, L.

2015-12-01

The purpose of this study is to examine how long nontronite clays persist in soil, by studying samples collected from a sediment cone weathering out of crack in a basalt outcrop near Moscow Idaho. Nontronite, a dioctahedral ferric smectite clay, is a frequent weathering product of basaltic rocks. However, it is rarely described in surface soils, even in basaltic terrains. At our field site, nontronite formed by basalt weathering is eroding from cracks in the basalt and forming small talus cones. We are examining samples collected from a trench and several soil cores to determine the clay mineralogy at different depths in the talus cone. Bulk and clay mineralogy is being determined using X-ray Diffractometry (XRD) analysis and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. Bulk chemical analyses, and selective extractions with acid oxalate and citrate-bicarbonate-dithionite reagents, are being used to analyze Fe mineralogy and amorphous constituents. Preliminary observations suggest that iron mineralogy may vary with depth in the sediments, and that older, deeper sediments may contain more Fe in oxide phases. We hypothesize that nontronite in the sediments is decomposing over time to form low-Fe smectites + Fe oxides. The results of this study will help determine whether nontronite is stable to erosion and redeposition in a surficial environment, as well as the timescale of its possible decomposition. These results may be useful in assessing proposed models of nontronite transport and redeposition on Mars.

Hydrology of area 4, Eastern Coal Province, Pennsylvania, Ohio, and West Virginia

USGS Publications Warehouse

Roth, Donald K.; Engelke, Morris J.; ,

1981-01-01

Area 4 (one of the 24 hydrologic areas defining the Eastern Coal Province) is located at the northern end of the Eastern Coal Province in eastern Ohio, northern West Virginia, and western Pennsylvania. It is part of the upper Ohio River basin, which includes the Beaver, Mahoning, and Shenango Rivers. The area is underlain by rocks of the Pottsville, Allegheny, Conemaugh, Monongahela Groups (or Formations) and Dunkard Group. Area 4 has a temperate climate with an annual average rainfall of 38 to 42 inches, most of its area is covered by forest. The soils have a high erosion potential where the vegetation cover is removed. In response to Public Law 95-87, 132 sites were added to the existing surface-water data-collection network in area 4. At these added sites, collected data includes discharge, water quality, sediment, and biology. The data are available from computer storage through the National Water Data Exchange (NAWDEX) or the published annual Water Resources Data reports for Ohio, Pennsylvania, and West Virginia. Hydrologic problems related to mining are: (1) Erosion and increased sedimentation, and (2) degradation of water quality. Erosion and sedimentation are associated chiefly with surface mining. Sediment yields increase drastically when vegetation is removed from the highly erosive soils. Degradation of water quality can be caused by acid-mine drainage from underground and surface mining. More than half the acid-mine drainage effluent in area 4 comes from underground mines. The rest seeps from abandoned surface mines. Usually in reclaimed surface mines the overburden is replaced in such a short time after the coal is taken out that oxidation of acid-forming minerals, commonly pyrite or marcasite, is not complete or is neutralized by the buffering action of calcareous minerals in the soils. (USGS)

Use of carbon isotope analysis to understand semi-arid erosion dynamics and long-term semi-arid land degradation.

PubMed

Turnbull, Laura; Brazier, Richard E; Wainwright, John; Dixon, Liz; Bol, Roland

2008-06-01

Many semi-arid areas worldwide are becoming degraded, in the form of C(4) grasslands being replaced by C(3) shrublands, which causes an increase in surface runoff and erosion, and altered nutrient cycling, which may affect global biogeochemical cycling. The prevention or control of vegetation transitions is hindered by a lack of understanding of their temporal and spatial dynamics, particularly in terms of interactions between biotic and abiotic processes. This research investigates (1) the effects of soil erosion on the delta(13)C values of soil organic matter (SOM) throughout the soil profile and its implications for reconstructing vegetation change using carbon-isotope analysis and (2) the spatial properties of erosion over a grass-shrub transition to increase understanding of biotic-abiotic interactions by using delta(13)C signals of eroded material as a sediment tracer. Results demonstrate that the soils over grass-shrub transitions are not in steady state. A complex interplay of factors determines the input of SOM to the surface horizon of the soil and its subsequent retention and turnover through the soil profile. A positive correlation between event runoff and delta(13)C signatures of eroded sediment was found in all plots. This indicates that the delta(13)C signatures of eroded sediment may provide a means of distinguishing between changes in erosion dynamics over runoff events of different magnitudes and over different vegetation types. The development of this technique using delta(13)C signatures of eroded sediment provides a new means of furthering existing understanding of erosion dynamics over vegetation transitions. This is critical in terms of understanding biotic-abiotic feedbacks and the evolution of areas subject to vegetation change in semi-arid environments. John Wiley & Sons, Ltd

Ecoenzymatic Stoichiometry of Stream Sediments with Comparison to Terrestrial Soils

EPA Science Inventory

In this study, we extend the development of ecoenzymatic stoichiometry to the surface sediments of stream ecosystems using data collected in a nationwide survey. The data set is larger and more comprehensive than those used in our previous studies. The data include the first broa...

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.

Stereochemistry of amino acids in surface samples of a marine sediment

NASA Technical Reports Server (NTRS)

Pollock, G. E.; Kvenvolden, K. A.

1978-01-01

In two surface samples of marine sediment, the percentages of D-alanine and D-aspartic acid are significantly higher than the other D-amino acids and are similar to the range found in soils. The percentage of D-glutamic acid is also higher than the other amino acids but less than D-alanine and D-aspartic acid. These D-amino acids may come mainly from bacteria.

Stereochemistry of amino acids in surface samples of a marine sediment

USGS Publications Warehouse

Pollock, G.E.; Kvenvolden, K.A.

1978-01-01

In two surface samples of marine sediment, the percentages of d-alanine and d-aspartic acid are significantly higher than the other d-amino acids and are similar to the range found in soils. The percentage of d-glutamic acid is also higher than the other amino acids but less than d-alanine and d-aspartic acid. These d-amino acids may come mainly from bacteria. ?? 1978.

On the non-uniqueness of sediment yield

NASA Astrophysics Data System (ADS)

Kim, J.; Ivanov, V. Y.; Katopodes, N.

2012-12-01

Estimation of sediment yield at the catchment scale plays an important role for optimal design of hydraulic structures, such as bridges, culverts, reservoirs, and detention basins, as well as making informed decisions in environmental management. Many experimental studies focused on obtaining flow and sediment data in search of unique relationships between runoff (specifically, volume and peak) and sediment characteristics. These relationships were employed to predict sediment yield from flow information. However, despite the same flow volume, the actual sediment yield produced by river basins can vary significantly depending on several conditions: (i) the catchment size, (ii) land use, topography, and soil type, (iii) climatic variations or characteristics , and (iv) initial conditions of soil moisture and soil surface . Additionally, shield formation by relatively larger particles can be one of the possible controllers of erosion and net sediment transport. Smaller particles have low settling velocities and tend to move far from their original position of detachment. Conversely, larger particles can settle quickly near their original locations. Eventually, such particles can form a shield on soil bed and protect underlying soil from rainfall detachment and runoff entrainment. The shield formation and temporal development can be influenced by rainfall intensity, frequency, and volume. Rainfall influences the generation of runoff leading to different conditions of flow depth and velocity that can perturb intact soil into a loose condition. In this study, we numerically investigate the effects of precipitation patterns on the generation of sediment yield. In particular, we address reasons of non-uniqueness of basin sediment yield for the same runoff volume as well as causes of unsteady phenomena in erosion processes under steady state flow conditions. For numerical simulations, the two-dimensional Hairsine-Rose model coupled with a fully distributed hydrology and hydraulics model (tRIBS-OFM: Triangulated irregular network - based Real time Integrated Basin Simulator-Overland Flow Model) is used.

Event-based soil loss models for construction sites

NASA Astrophysics Data System (ADS)

Trenouth, William R.; Gharabaghi, Bahram

2015-05-01

The elevated rates of soil erosion stemming from land clearing and grading activities during urban development, can result in excessive amounts of eroded sediments entering waterways and causing harm to the biota living therein. However, construction site event-based soil loss simulations - required for reliable design of erosion and sediment controls - are one of the most uncertain types of hydrologic models. This study presents models with improved degree of accuracy to advance the design of erosion and sediment controls for construction sites. The new models are developed using multiple linear regression (MLR) on event-based permutations of the Universal Soil Loss Equation (USLE) and artificial neural networks (ANN). These models were developed using surface runoff monitoring datasets obtained from three sites - Greensborough, Cookstown, and Alcona - in Ontario and datasets mined from the literature for three additional sites - Treynor, Iowa, Coshocton, Ohio and Cordoba, Spain. The predictive MLR and ANN models can serve as both diagnostic and design tools for the effective sizing of erosion and sediment controls on active construction sites, and can be used for dynamic scenario forecasting when considering rapidly changing land use conditions during various phases of construction.

Anaerobic methane oxidation may be more prevalent in surface soils than was originally thought

NASA Astrophysics Data System (ADS)

Gauthier, Mathieu; Bradley, Robert L.; Šimek, Miloslav

2013-04-01

Anaerobic oxidation of methane (CH4) (AOM) is a process that was first reported to occur in deep anoxic marine sediments. In this environment, CH4 is oxidized with sulphate (SO42-) as the terminal electron acceptor. It is mediated by a syntrophic consortium formed by SO42- reducing bacteria and anaerobic CH4 oxidizing Archaea, or by the latter alone. Since this landmark discovery, AOM was found to occur in other environments including freshwater lake sediments and water columns, mud volcanoes, landfill leachate, deep buried Holocene sediments and hydrocarbon contaminated aquifers. All of these situations are very specific and point to AOM as being primarily occurring in highly reducing conditions. Thus, observations of AOM in surface soils with fluctuating REDOX conditions are relatively scarce, although a few independent studies have reported AOM in surface peatlands as well as in a forest soil. Furthermore, AOM may follow different pathways, such as via the coupled oxidation of CH4 and reduction of manganese (Mn(IV)) or iron (Fe(III)), or by a lone denitrifying species that converts nitrite to nitric oxide in order to generate O2 that is then used internally to oxidize CH4. Thus, the goal of our study was to determine whether AOM is more prevalent than was thought in hydromorphic surface soils across different environments, and whether the addition of NO3- or SO4= as alternative electron acceptors may stimulate the process. We collected samples from 3 peatland soils in Scotland, 2 acid-sulphate soils in Finland, and shore sediments of 15 drained fish ponds in the Czech Republic. Subsamples were incubated in the absence of O2 and amended with either NO3-, SO42-, or left unamended (control). The net flux of CH4 and CO2 were assessed by gas chromatography after 2, 20, 40 and 60 days. We also used a 13C-CH4 isotope dilution technique to determine gross production and consumption rates of CH4. We detected AOM in all of our soils, with oxidation rates ranging between 0.001 and 37.28 nmol g-1 day-1, suggesting that AOM may be more ubiquitous than was originally thought. On the other hand, no clear patterns emerged as to the effects of NO3- or SO42- amendments on this process.

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.

Process based modelling of soil organic carbon redistribution on landscape scale

NASA Astrophysics Data System (ADS)

Schindewolf, Marcus; Seher, Wiebke; Amorim, Amorim S. S.; Maeso, Daniel L.; Jürgen, Schmidt

2014-05-01

Recent studies have pointed out the great importance of erosion processes in global carbon cycling. Continuous erosion leads to a massive loss of top soils including the loss of organic carbon accumulated over long time in the soil humus fraction. Lal (2003) estimates that 20% of the organic carbon eroded with top soils is emitted into atmosphere, due to aggregate breakdown and carbon mineralization during transport by surface runoff. Furthermore soil erosion causes a progressive decrease of natural soil fertility, since cation exchange capacity is associated with organic colloids. As a consequence the ability of soils to accumulate organic carbon is reduced proportionately to the drop in soil productivity. The colluvial organic carbon might be protected from further degradation depending on the depth of the colluvial cover and local decomposing conditions. Some colluvial sites can act as long-term sinks for organic carbon. The erosional transport of organic carbon may have an effect on the global carbon budget, however, it is uncertain, whether erosion is a sink or a source for carbon in the atmosphere. Another part of eroded soils and organic carbon will enter surface water bodies and might be transported over long distances. These sediments might be deposited in the riparian zones of river networks. Erosional losses of organic carbon will not pass over into atmosphere for the most part. But soil erosion limits substantially the potential of soils to sequester atmospheric CO2 by generating humus. The present study refers to lateral carbon flux modelling on landscape scale using the process based EROSION 3D soil loss simulation model, using existing parameter values. The selective nature of soil erosion results in a preferentially transport of fine particles while less carbonic larger particles remain on site. Consequently organic carbon is enriched in the eroded sediment compared to the origin soil. For this reason it is essential that EROSION 3D provides the grain size distribution (clay, silt and sand) of the transported sediment. A test slope is modeled covering certain land use and soil management scenarios referring to different rainfall events. Results allow first insights on carbon loss and depletion on sediment delivery areas as well as carbon gains and enrichments on deposition areas on landscape scale. Lal, R. (2003). Soil erosion and the global carbon budget. Environment International vol. 29: 437-450.

[Impact of wind-water alternate erosion on the characteristics of sediment particles].

PubMed

Tuo, Deng-Feng; Xu, Ming-Xiang; Ma, Xin-Xin; Zheng, Shi-Qing

2014-02-01

Wind and water are the two dominant erosion agents that caused soil and water losses in the wind-water alternate erosion region on the Loess Plateau. It is meaningful to study the impact of wind-water alternate erosion on the characteristics of soil particles for understanding the response of soil quality and environment to erosion. Through wind tunnel combined rainfall simulation, this paper studied the characteristics of the erosive sediment particles under the effect of wind-water alternate erosion. The results showed that the particles of 0-1 cm soil were coarsened by wind erosion at the wind speeds of 11 and 14 m x s(-1) compared with no wind erosion. Soil fine particles (< 0.01 mm) decreased by 9.8%-10.8%, and coarse particles (> 0.05 mm) increased by 16.8%-20.8%. The physical property of surface soil was changed by the wind erosion, which, in turn, caused an increase in finer particles content in the sediment. Compared with no wind erosion, fine particles (< 0.01 mm) in sediment under the water-wind alternate erosion increased by 2.7%-18.9% , and coarse particles (> 0.05 mm) decreased by 3.7%-9.3%. However, the changing trend of erosive sediment particles after the wind erosion at wind speeds of 11 and 14 m x s(-1) was different along with the rainfall intensity and duration. The erosive sediment particles at the rainfall intensities of 60, 80, 100 mm x h(-1) changed to greater extents than at the 150 mm x h(-1) rainfall intensity with longer than 15 min runoff flowing.

Health assessment for Stamina Mills Site, North Smithfield, Providence County, Rhode Island, Region 1. CERCLIS No. RID980731442. Preliminary report

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

Not Available

1988-11-15

The Stamina Mills site is on the National Priorities List (NPL). The environmental contamination of concern consists of methylene chloride, chromium, lead, nickel, trichloroethylene, perchloroethylene, and 1,2-dichloro- ethylene in groundwater; trichloroethylene, 1,2-dichloroethylene, methylene chloride, and nickel in surface water; trichloroethylene, 1,2-dichloroethylene, chloroform, methylene chloride, cyanide, 2-butanone, cadmium, lead, chromium, nickel, and dieldrin in soil; and chloroform, lead, nickel, and chromium in sediment. The site is considered to be of potential public health concern because of the risk to human health caused by the possibility of exposure to hazardous substances via soil, sediment, and surface water.

Mars Pathfinder Wheel Abrasion Experiment Ground Test

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Siebert, Mark W.

1998-01-01

The National Aeronautics and Space Administration (NASA) sent a mission to the martian surface, called Mars Pathfinder. The mission payload consisted of a lander and a rover. The primary purpose of the mission was demonstrating a novel entry, descent, and landing method that included a heat shield, a parachute, rockets, and a cocoon of giant air bags. Once on the surface, the spacecraft returned temperature measurements near the Martian surface, atmosphere pressure, wind speed measurements, and images from the lander and rover. The rover obtained 16 elemental measurements of rocks and soils, performed soil-mechanics, atmospheric sedimentation measurements, and soil abrasiveness measurements.

Sediment pathways in a tropical forest: effects of logging roads and skid trails

NASA Astrophysics Data System (ADS)

Sidle, Roy C.; Sasaki, Shozo; Otsuki, Mieko; Noguchi, Shoji; Rahim Nik, Abdul

2004-03-01

Significant erosion occurred from recently constructed forest logging roads and skid trails in a small headwater catchment in Peninsular Malaysia. Soil loss was estimated by measuring dimensions of all significant rills and gullies along the road, as well as by measuring height of preserved soil pedestals in sidecast and fill material and on skid trails. Estimates of surface erosion from logging roads and skid trails were 272 +/- 20 t ha-1 year-1 and 275 +/- 20 t ha-1 year-1 respectively. However, owing to lack of connectivity of skid trails to the stream, much of the sediment mobilized on skid trails was stored either on adjacent hillslopes or the trails themselves, rather than being transported to the stream system, as was the case for the road. Steeper skid trails (>20% gradient) had slightly higher erosion rates (320 +/- 24 t ha-1 year-1) than trails with gentler gradients (245-264 t ha-1 year-1). Some 60% of the soil loss on logging roads comes from erosion of the running surface. Disturbed cut and fill material along the road supplied the remaining 40% of the soil loss from roads. Roads and skid trails had no designed drainage systems; runoff discharged onto the hillslope at 25 major discharge nodes from the logging road (690 m total length) and at 34 nodes from skid trails (2300 m). Sediment pathways were either fully or moderately connected to headwater channels at 64% of the logging road nodes, but at only 26% of the nodes emanating from skid trails. A detailed sediment budget revealed that 78% of the soil loss from the road system (including log landings) was delivered to the stream in the first 16 months after logging began. Most (90%) of the deposition from skid trails occurred below just three discharge nodes. Runoff from and onto skid trails often exacerbated the sediment connectivity to channels. Clearly, sediment discharge from logging roads was more highly connected to the stream than discharge from skid trails. Once in the channel, much of this sediment was temporarily stored in the floodplain and behind woody debris.

Scratching technique for the study and analysis of soil surface abrasion mechanism

NASA Astrophysics Data System (ADS)

Ta, Wanquan

2007-11-01

Aeolian abrasion is the most fundamental and active surface process that takes place in arid and semi-arid environments. Its nature is a wear process for wind blown grains impinging on a soil or sediment surface, which causes particles and aggregates to fracture from the soil surface through a series of plastic and brittle cracking deformation such as cutting, ploughing and brittle fracturing. Using a Universal Micro-Tribometer (UMT), a scratching test was carried out on six soil surfaces (sandy soil, sand loam, silt loam, loam, silt clay loam, and silt clay). The results indicate that traces of normal and tangential force vs. time show a jagged curve, which can reflect the plastic deformation and brittle fracturing of aggregates and particles of various sizes fractured from the soil surfaces. The jagged curve peaks, and the area enclosed underneath, may represent the bonding forces and bonding energies of some aggregates and grains on the soil surface, respectively. Connecting the scratching test with an impact abrasion experiment furthermore demonstrates that soil surface abrasion rates are proportional to the square of speeds of impacting particles and to the 2.6 power of mean soil grain size, and inversely proportional to the 1.5 power of specific surface abrasive energy or to the 1.7 power of specific surface hardness.

Superfund Record of Decision (EPA Region 3): Metal Banks, Philadelphia, PA, December 31, 1997

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

NONE

1998-09-01

This Record of Decision (ROD) presents the final remedial action selected for the Metal Bank Superfund Site (Site), located in northeastern Philadelphia, Pennsylvania. The remedy addresses contaminated soil, sediment, surface water, and groundwater at the Site and includes: installation of an oil collection system consisting of a sheet pile wall around the southern and western perimeter of the property; installation of temporary cofferdams prior to soil/sediment excavation to minimize transport of contamination into the Delaware River; excavation of contaminated soil within the Courtyard Area within two feet of the surface where polychlorinated biphenyl (PCB) concentrations exceed 10 ppm; disposal ofmore » contaminated soils and sediments that are hazardous; removal and disposal of the underground storage tank and its contents from the Southern Portion of the property; backfilling of excavated areas; posting signs prohibiting consumption of fish caught in the Delaware River in the vicinity of the Site; restrictions on the deed to the property to prevent future residential or agricultural use of the Site, use of the groundwater, and intrusive activities into the subsurface soils below the water table in the Southern Portion of the property; additional investigation to determine whether dense non-aqueous phase liquids (DNAPLs) are present at the Site and whether the storm sewer system in the vicinity of the Site is contaminated; and monitoring of groundwater, the Delaware River, and the Baxter Water intake.« less

Integrative investigations on sediments in the Belauer See catchment (northern Germany)

NASA Astrophysics Data System (ADS)

Dreibrodt, Stefan

2015-04-01

The Holocene history of lake development, catchment vegetation, soil formation and human impact since the onset of the Neolithic period was reconstructed via the analysis of sediment sequences at Lake Belau (northern Germany). The chronology of the annually laminated lake sediment sequence was established via varve counts, radiocarbon dating and tephra analysis. Sequences of colluvial sediments and buried soils studied in 19 large exposures and supplementing auger cores within the lake catchment area were dated via radiocarbon dating and archaeological dating of embedded artifacts. The long term development of the lake status was found to be strongly influenced by local human activity. This is indicated by coincidence of phases of landscape openness deduced from pollen data with input of detritus and solutes into the lake. A comparison with palaeo-climate reconstructions reveals that calcite precipitation in the lake reflects climate variability at least to a certain degree. Calibrating the sediment record of the sub-recent lake sediments (micro-facies) on limnological and meteorological records discovered the influence of the NAO as well as solar activity on the limnological processes during the last century reflected by distinguished sedimentation patterns. A comparative study of additional laminated surface sediment sequences from northern Germany corroborates the results. A high resolution reconstruction of Neolithic weather conditions in northern Germany based on the varves of Lake Belau and Lake Poggensee was facilitated by the calibration. The quantitative records of sediments originating from soil erosion (colluvial sediments, allochthonous input into the lake) illustrate the dominance of short distance surface processes (slopes) acting in Holocene mid-latitude landscapes. Coincidence of gully incision in the lake catchment area and increased allochthonous input into the lake indicates the former occurrence of hydrological high energy runoff events (e. g. in the 14th century or at ca. 200 cal BC) whose regional significance is testable via comparative investigations in additional lake catchments.

Dust in the western U.S.: how biological, physical and human activities at the local scale interact to affect hydrologic function at the landscape scale (Invited)

NASA Astrophysics Data System (ADS)

Belnap, J.; Reheis, M. C.; Munson, S. M.

2009-12-01

Dryland regions constitute over 35% of terrestrial lands around the globe. Limited rainfall in these regions restricts plant growth and the spaces between vascular plants are often large. Most interspace soils are protected from wind erosion by the cover of rocks, physical crusts, and biological crusts (cyanobacteria, lichens, and mosses). However, disturbance of the soil surface in dryland regions (e.g., recreation, livestock, mining and energy exploration, military exercises, fire) reduces or eliminates the protective cover of the soils. Rising temperatures will reduce soil moisture and thus plant cover. Wind tunnel data show that most desert surfaces produce little sediment under typical wind speeds. However, disturbing the soil surface with vehicles, humans, or animals resulted in much higher sediment production from all surfaces tested, regardless of parent material, texture, or age of the soil surface. Synergist effects, such as surface disturbance occurring during drought periods in annualized plant communities, can create very large dust events. As surface disturbance, invasion, and drought are expected to increase in the future, an increase in dust production can be expected as well. Increased particulates in the air threaten human well-being through disease, highway accidents, and economic losses. Where dust losses are greater than the inputs, the source areas lose carbon and nutrients. These compounds are transferred to high elevation regions, where such fertilization likely impacts ecosystem function. Deposition of dust on the snowpack darkens the surface, increasing snowmelt by 30 days or more and exposing soils to evaporation, all of which decrease the quantity and quality of water in major streams and rivers. As increases occur in temperature, pumping of shallow aquifers, human activities, and invasion of exotic annual plants in dryland regions, the frequency, severity, and negative impact of dust storms is expected to increase as well. The implications of these future changes will be discussed.

Tracing tetraether lipids from source to sink in the Rhône River system (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Kim, Jung-Hyun; Ludwig, Wolfgang; Buscail, Roselyne; Dorhout, Denise; Sinninghe Damste, Jaap

2015-06-01

In this study, we investigated soils and river suspended particulate matter (SPM) collected in the Rhône and its tributary basins as well as marine surface sediments taken in the Rhône prodelta (Gulf of Lions, NW Mediterranean). Thereby, we traced the signal of branched glycerol dialkyl glycerol tetraethers (brGDGTs) from the source to sink via the Rhône River and its tributaries and identified sources of brGDGTs in rivers and marine sediments. Soil pH rather than the mean annual air temperature (MAAT) explains most of the observed variances of the brGDGT distribution in our soil dataset. The observed changes in the distribution of brGDGTs in the river SPM indicate that brGDGTs brought by the river to the sea are primarily derived from the lower Rhône and its tributary soils, even though in situ production in the river itself cannot be excluded. In marine surface sediments, it appears that the input of riverine brGDGTs is the primary source of brGDGTs in the Rhône prodelta, although the brGDGT composition may be further modified by the in situ production in the marine environment. More work is required to assess fully whether brGDGTs can be used to reconstruct the terrestrial paleoenvironmental changes using marine sediment cores taken in the Rhône prodelta close to the river mouth.

How sedge meadow soils, microtopography, and vegetation respond to sedimentation

USGS Publications Warehouse

Werner, K.J.; Zedler, Joy B.

2002-01-01

The expansion of urban and agricultural activities in watersheds of the Midwestern USA facilitates the conversion of species-rich sedge meadows to stands of Phalaris arundinacea and Typha spp. We document the role of sediment accumulation in this process based on field surveys of three sedge meadows dominated by Carex stricta, their adjacent Phalaris or Typha stands, and transitions from Carex to these invasive species. The complex microtopography of Carex tussocks facilitates the occurrence of other native species. Tussock surface area and species richness were positively correlated in two marshes (r2 = 0.57 and 0.41); on average, a 33-cm-tall tussock supported 7.6 species. Phalaris also grew in tussock form in wetter areas but did not support native species. We found an average of 10.5 Carex tussocks per 10-m transect, but only 3.5 Phalaris tussocks. Microtopographic relief, determined with a high-precision GPS, measured 11% greater in Carex meadows than Phalaris stands. Inflowing sediments reduced microtopographic variation and surface area for native species. We calculated a loss of one species per 1000 cm2 of lost tussock surface area, and loss of 1.2 species for every 10-cm addition of sediment over the sedge meadow surface. Alluvium overlying the sedge meadow soil had a smaller proportion of organic matter content and higher dry bulk density than the buried histic materials. We conclude that sedimentation contributes to the loss of native species in remnant wetlands. ?? 2002, The Society of Wetland Scientists.

Mineralogical analyses of surface sediments in the Antarctic Dry Valleys: coordinated analyses of Raman spectra, reflectance spectra and elemental abundances.

PubMed

Bishop, Janice L; Englert, Peter A J; Patel, Shital; Tirsch, Daniela; Roy, Alex J; Koeberl, Christian; Böttger, Ute; Hanke, Franziska; Jaumann, Ralf

2014-12-13

Surface sediments at Lakes Fryxell, Vanda and Brownworth in the Antarctic Dry Valleys (ADV) were investigated as analogues for the cold, dry environment on Mars. Sediments were sampled from regions surrounding the lakes and from the ice cover on top of the lakes. The ADV sediments were studied using Raman spectra of individual grains and reflectance spectra of bulk particulate samples and compared with previous analyses of subsurface and lakebottom sediments. Elemental abundances were coordinated with the spectral data in order to assess trends in sediment alteration. The surface sediments in this study were compared with lakebottom sediments (Bishop JL et al. 2003 Int. J. Astrobiol. 2, 273-287 (doi:10.1017/S1473550403001654)) and samples from soil pits (Englert P et al. 2013 In European Planetary Science Congress, abstract no. 96; Englert P et al. 2014 In 45th Lunar and Planetary Science Conf., abstract no. 1707). Feldspar, quartz and pyroxene are common minerals found in all the sediments. Minor abundances of carbonate, chlorite, actinolite and allophane are also found in the surface sediments, and are similar to minerals found in greater abundance in the lakebottom sediments. Surface sediment formation is dominated by physical processes; a few centimetres below the surface chemical alteration sets in, whereas lakebottom sediments experience biomineralization. Characterizing the mineralogical variations in these samples provides insights into the alteration processes occurring in the ADV and supports understanding alteration in the cold and dry environment on Mars. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

A 15,400-year record of environmental magnetic variations in sub-alpine lake sediments from the western Nanling Mountains in South China: Implications for palaeoenvironmental changes

NASA Astrophysics Data System (ADS)

Zhong, Wei; Wei, Zhiqiang; Shang, Shentan; Ye, Susu; Tang, Xiaowen; Zhu, Chan; Xue, Jibin; Ouyang, Jun; Smol, John P.

2018-04-01

A detailed environmental magnetic investigation has been performed on a sub-alpine sedimentary succession deposited over the past 15,400 years in Daping Swamp in the western Nanling Mountains of South China. Magnetic parameters reveal that fine grains of pseudo-single domain (PSD) magnetite or titanomagnetite are the dominant magnetic minerals in the lake sediments and surface soils collected from the catchment, which suggests that magnetic minerals in lake sediments mainly originated from surface soil erosion of the catchment. Variation of surface runoff caused by rainfall is interpreted as the main process for transportation of weathered soils into the lake. In the Last Deglacial period (LGP, 15,400-11,500 cal a BP), the influx of magnetic minerals of detrital material may have been significantly affected by the severe dry and cold conditions of the Last Glacial Maximum. Stabilised conditions of the catchment associated with increased vegetation coverage (e.g., 8000-4500 and 2500-1000 cal a BP) limited the input of magnetic minerals. Intensive soil erosion caused by increased human activity may have given rise to abnormal increases in multiple magnetic parameters after 1000 cal a BP. Because changes in runoff and vegetation coverage are closely related to Asian summer monsoon (ASM) intensity, the sedimentary magnetism of Daping Swamp provides another source of information to investigate the evolution of the ASM.

Surface runoff and retention of transported pollutants in strips of riparian vegetation with and without trees

NASA Astrophysics Data System (ADS)

Giaccio, Gustavo; Laterra, Pedro; Aparicio, Virginia; Costa, Jose Luis

2017-04-01

In this study, some aspects related to the effect of the crack willow (Salix fragilis L.) invasion on the reduction of runoff and sediment retention, glyphosate, nitrogen and phosphorus in riparian environments with herbaceous vegetation of the Austral Pampa of Argentina were analysed. In order to evaluate the influence of the willows on the filtering mechanisms, surface runoff simulation experiments were carried out in plots of 1.5 m x 2.5 m in environments characterized by the presence vs. the absence of willows. In spite of the small length of the experimental plots, glyphosate retention in the tree-less plots reached 73.6%, a higher value than that recorded in tree stands (43.8%). However, sediment, nitrogen and phosphorus retention did not vary significantly between treatments. On the other hand, the reduction of the volume of runoff in the sites with trees reached 63%, a superior value to the one registered in strips without trees (31%). The presence of trees only significantly modified the biophysical properties of hydraulic conductivity, surface roughness, aerial biomass and soil moisture, compared to areas with no trees. Partial correlation analysis for both tree and no-tree environments showed that the reduction in runoff volume increased significantly with hydraulic conductivity, soil sand content and depth at the water table, and decreased with apparent density, soil moisture and the slope of the riverbank. However, sediment retention increased significantly with aerial, mulch and root biomass and decreased with the slope of the riparian strip. Glyphosate retention increased significantly with sediment retention and decreased with the slope of the riparian strip and the mulch biomass. Nitrogen retention increased with the reduction of runoff flow, soil hydraulic conductivity and depth to the water table and decreased with slope and sediment retention. While, phosphorus retention increased with sediment retention and decreased with slope and soil content of soils. However, the mechanisms involved in the differential effect of the vegetation with or without trees could not be explained. This work emphasizes the importance of the ecosystem function of glyphosate filtration of riparian environments covered by herbaceous vegetation in front of the increasing intensification of agriculture. On the other hand, in the context of agro ecosystems and agricultural landscapes the presence of trees contributes to the reduction of the flow of runoff, although these sub compensate in relation to the sites without trees, considering the balance between flow and concentration.

Polychlorinated biphenyls (PCBs) in sediments/soils of different wetlands along 100-year coastal reclamation chronosequence in the Pearl River Estuary, China.

PubMed

Zhao, Qingqing; Bai, Junhong; Lu, Qiongqiong; Gao, Zhaoqin; Jia, Jia; Cui, Baoshan; Liu, Xinhui

2016-06-01

PCBs (polychlorinated biphenyls) were determined in sediment/soil profiles to a depth of 30 cm from three different wetlands (i.e., ditch wetlands, riparian wetlands and reclaimed wetlands) of the Pearl River Estuary to elucidate their levels, distribution and toxic risks along a 100-year chronosequence of reclamation. All detected PCB congeners and the total 15 PCBs (∑15 PCBs) decreased with depth along sediment/soil profiles in these three wetlands. The ∑15 PCBs concentrations ranged from 17.68 to 169.26 ng/g in surface sediments/soils. Generally, old wetlands tended to have higher PCB concentrations than younger ones. The dominant PCB congeners at all sampling sites were light PCB homologues (i.e., tetra-CBs and tri-CBs). According to the sediment quality guideline, the average PCB concentrations exceeded the threshold effects level (TEL, 21.6 ng/g) at most of the sampling sites, exhibiting possible adverse biological effects, which were dominantly caused by light PCB congeners. The total toxic equivalent (TEQ) concentrations of 10 dioxin-like PCBs (DL-PCBs) detected at all sampling sites ranged from 0.04 to 852.7 (10(-3) ng/g), mainly affected by PCB126. Only DL-PCB concentrations in ditch and riparian wetland sediments with 40-year reclamation histories (i.e., D40 and Ri40) exhibited moderate adverse biological effects according to SQGQ values. Principal component analysis indicated that PCBs in three wetland sediments/soils mainly originated from Aroclor 1016, 1242, and 1248. Correlation analysis showed that sediment/soil organic carbon content had a significant correlation with the concentrations of several PCB congeners (P < 0.05), whereas no significant correlations were observed between any PCBs congeners and grain size or aggregate content (P > 0.05). Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of forest road amelioration techniques on soil bulk density, surface runoff, sediment transport, soil moisture and seedling growth

Treesearch

Randy K. Kolka; Mathew F. Smidt

2004-01-01

Although numerous methods have been used to retire roads, new technologies have evolved that can potentially ameliorate soil damage, lessen ,the generation of nonpoint source pollution and increase tree productivity on forest roads. In this study we investigated the effects of three forest road amelioration techniques, subsoiling, recontouring and traditional...

Sources of core and intact branched tetraether membrane lipids in the lacustrine environment: Anatomy of Lake Challa and its catchment, equatorial East Africa

NASA Astrophysics Data System (ADS)

Buckles, Laura K.; Weijers, Johan W. H.; Verschuren, Dirk; Sinninghe Damsté, Jaap S.

2014-09-01

The MBT/CBT palaeotemperature proxy uses the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), membrane lipids that are supposed to derive from soil bacteria, to reconstruct mean annual air temperature (MAAT). Applied successfully in coastal marine sediments, its extension to lake-sediment records with potentially high time resolution would greatly expand its utility. Over the last years, however, studies have indicated the presence of additional sources of brGDGTs within lake systems. To constrain the factors influencing the MBT/CBT palaeotemperature proxy in lakes, detailed investigation of brGDGT fluxes in a modern lake system is necessary to identify their potential sources. This study concentrates on Lake Challa, a permanently stratified crater lake in equatorial East Africa with limited catchment area. An almost 3-year time series of approximately monthly samples of settling particles, supplemented with a depth profile of suspended particulate matter (SPM) and sets of profundal surface-sediment and catchment soil samples, were analysed for both the 'living' intact polar lipids (IPLs) and 'fossil' core lipids (CLs) of GDGTs. We found that brGDGTs are produced in oxic, suboxic and anoxic zones of the water column, and in substantial amounts compared to influxes from catchment soils. Additional in situ production within the lake sediments is most probable, but cannot be definitely confirmed at this time. These lacustrine brGDGTs display a different response to temperature variation than soil-derived brGDGTs, signifying either a different physiological adaptation to changing conditions within the water column and/or a different composition of the respective bacterial communities. Using this specific relationship with temperature, a local calibration based on brGDGT distributions in SPM generates relatively accurate water temperature estimates from settling particles but fails for surface sediments.

Freshwater sediments and sludges: two important terrestrial sinks for emissions from damaged NPPs

NASA Astrophysics Data System (ADS)

Fischer, Helmut W.; Evangelia Souti, Maria; Ulbrich, Susanne; Hormann, Volker

2013-04-01

Surface deposition of radionuclides released from the damaged Fukushima NPPs is well documented and emissions to the Pacific Ocean and their distribution with time and space are also subject to monitoring and research. In both cases, solid matter (soil and sea sediment, respectively) acts as a sink for radioisotopes after their transport through air and water. The possible hazards from direct irradiation of workers and public and from entry of radionuclides into food chains are well recognized. Apart from direct deposition onto soil, plants, building roofs etc., aerosols and contaminated rainwater will reach surface waters, leading to long-term deposition in freshwater sediments (and possibly to interim contamination of drinking water). In populated and industrial areas, drained rainwater will enter the wastewater collection and treatment chain if a combined rain and wastewater sewer is used. Depending on the processes in the wastewater treatment plant and chemical element and speciation, the isotopes will either concentrate in treatment sludge or be released with the effluent to rivers and lakes and their sediments. The mentioned media may act as long-term storage for radioisotopes when disposed of properly, but can also contribute to direct irradiation of workers or public, lead to continuous releases to the environment and possibly enter the food chain in the same way as soil and sea sediments. It appears therefore essential to monitor these environmental compartments as well. However, very few data on Fukushima-related radioisotope concentration in sludges and freshwater sediments have been published to date. We will therefore compare data for regional surface deposition and related concentrations in surface water, river sediments and sewage sludge obtained in Europe during 1986 to published data from Japan in 2011 for the most important common short-lived (I-131, half-life = 8.02 d) and long-lived (Cs-137, half-life = 30.17 yr) isotopes. As in central Europe the Chernobyl fallout was not accompanied by other catastrophic events, well documented time series of data exist. It might become possible to estimate sludge and sediment isotope concentrations in Japan by proportionality considerations and by application of transport models when no or insufficient current data exist. Additional insight into transport processes can be obtained from ongoing investigations of medically used I-131 in wastewater and rivers. The results might help in identification and remediation of possibly emerging hazards.

Depletion and Redistribution of Soil Nutrients in Response to Wind Erosion in Desert Grasslands of the Southwestern United States

NASA Astrophysics Data System (ADS)

Li, J.; Okin, G.; Hartman, L.; Epstein, H.

2005-12-01

Wind is a key abiotic factor that determines the spatial distribution of soil nutrients in arid grasslands with large unvegetated gaps, such as those found in the southwestern US. On the landscape scale, basic relationships such as wind erosion rate vs. vegetative cover, and soil nutrient removal rate vs. vegetative cover have not yet been extensively studied. In a series of experiments conducted in the Jornada Experimental Range near Las Cruces, New Mexico, we have examined these relationships to determine the impact of wind erosion and dust emission on pools of soil nutrients. In the experiments, varying levels of cover were achieved by vegetation removal on 25 m x 50 m plots. Intense surface soil sampling was conducted to monitor spatial distribution of soil nutrients. Large numbers of aeolian sediment samplers were installed to obtain estimates of vertical and horizontal dust flux. Available data from one wind erosion season show that: 1) total organic C (TOC) and total N (TN) content in the windblown sediment collected at the height of 1 m were 2.2 to 7.2 times larger than those of nutrients in the surface soil (enrichment ratio); 2) enrichment ratio generally increases with the increase of vegetative cover, indicating biotic processes continually add nutrients to surface soil in high-cover treatments, while nutrients are depleted in low-cover treatments; 3) average horizontal mass flux is 12 times larger in the bare plot than in the control plot, indicating the extreme importance of vegetative cover in protecting soil nutrient loss caused by wind erosion; 4) detectable soil nutrient depletion happened within one windy season in plots with vegetation removal, especially for TOC and TN, reflecting the importance of biotic processes in maintaining nutrient pools in the surface soil; and, 5) after only a single windy season, wind erosion can significantly alter the spatial pattern of soil nutrients.

A field method for measurement of infiltration

USGS Publications Warehouse

Johnson, A.I.

1963-01-01

The determination of infiltration--the downward entry of water into a soil (or sediment)--is receiving increasing attention in hydrologic studies because of the need for more quantitative data on all phases of the hydrologic cycle. A measure of infiltration, the infiltration rate, is usually determined in the field by flooding basins or furrows, sprinkling, or measuring water entry from cylinders (infiltrometer rings). Rates determined by ponding in large areas are considered most reliable, but the high cost usually dictates that infiltrometer rings, preferably 2 feet in diameter or larger, be used. The hydrology of subsurface materials is critical in the study of infiltration. The zone controlling the rate of infiltration is usually the least permeable zone. Many other factors affect infiltration rate--the sediment (soil) structure, the condition of the sediment surface, the distribution of soil moisture or soil- moisture tension, the chemical and physical nature of the sediments, the head of applied water, the depth to ground water, the chemical quality and the turbidity of the applied water, the temperature of the water and the sediments, the percentage of entrapped air in the sediments, the atmospheric pressure, the length of time of application of water, the biological activity in the sediments, and the type of equipment or method used. It is concluded that specific values of the infiltration rate for a particular type of sediment are probably nonexistent and that measured rates are primarily for comparative use. A standard field-test method for determining infiltration rates by means of single- or double-ring infiltrometers is described and the construction, installation, and operation of the infiltrometers are discussed in detail.

The role of subsurface flow in hillslope and streambank erosion: A review of status and research needs

USDA-ARS?s Scientific Manuscript database

Sediment is the most common cause of stream impairment. Great progress has been made in understanding processes of soil erosion due to surface runoff and incorporating these in prediction technologies. However, in many landscapes the dominant source of sediment is derived from mass wasting of hillsl...

Improved or unimproved urban areas effect on soil and water quality

USDA-ARS?s Scientific Manuscript database

Construction in urban areas usually results in compacted soil, which restricts plant growth and infiltration. Nutrients may be lost in storm runoff water and sediment. The purpose of this study was to determine if existing lawns benefit from aeration and surface compost additions without negative im...

43 CFR 23.8 - Approval of mining plan.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Two copies of a suitable map, or aerial photograph showing the topography, the area covered by the... all runoff water and drainage from workings so as to reduce soil erosion and sedimentation and to... fire, soil erosion, pollution of surface and ground water, damage to fish and wildlife, and hazards to...

43 CFR 23.8 - Approval of mining plan.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Two copies of a suitable map, or aerial photograph showing the topography, the area covered by the... all runoff water and drainage from workings so as to reduce soil erosion and sedimentation and to... fire, soil erosion, pollution of surface and ground water, damage to fish and wildlife, and hazards to...

43 CFR 23.8 - Approval of mining plan.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Two copies of a suitable map, or aerial photograph showing the topography, the area covered by the... all runoff water and drainage from workings so as to reduce soil erosion and sedimentation and to... fire, soil erosion, pollution of surface and ground water, damage to fish and wildlife, and hazards to...

Effect of high sedimentation rates on surface sediment dynamics and mangrove growth in the Porong River, Indonesia.

PubMed

Sidik, Frida; Neil, David; Lovelock, Catherine E

2016-06-15

Large quantities of mud from the LUSI (Lumpur Sidoarjo) volcano in northeastern Java have been channeled to the sea causing high rates of sediment delivery to the mouth of the Porong River, which has a cover of natural and planted mangroves. This study investigated how the high rates of sediment delivery affected vertical accretion, surface elevation change and the growth of Avicennia sp., the dominant mangrove species in the region. During our observations in 2010-2011 (4-5years after the initial volcanic eruption), very high rates of sedimentation in the forests at the mouth of the river gave rise to high vertical accretion of over 10cmy(-1). The high sedimentation rates not only resulted in reduced growth of Avicennia sp. mangrove trees at the two study sites at the Porong River mouth, but also gave rise to high soil surface elevation gains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling of Soil Erosion by IntErO model: The Case Study of the Novsicki Potok Watershed, of the Prokletije high mountains of Montenegro

NASA Astrophysics Data System (ADS)

Spalevic, Velibor; Al-Turki, Ali M.; Barovic, Goran; Leandro Naves Silva, Marx; Djurovic, Nevenka; Soares Souza, Walisson; Veloso Gomes Batista, Pedro; Curovic, Milic

2016-04-01

The application of soil conservation programs to combat erosion and sedimentation are significantly contributing to the protection of the natural resources. Watershed management practices include the assessment of Physical-Geographical, Climate, Geological, Pedological characteristics, including the analysis of Land Use of the regions concerned. The policy makers are increasingly looking for the different land uses and climatic scenarios that can be used for valuable projections for watershed management. To increase knowledge about those processes, use of hydrological and soil erosion models is needed and that is allowing quantification of soil redistribution and sediment productions. We focused on soil erosion processes in one of Northern Montenegrin mountain watersheds, the Novsicki Potok Watershed of the Polimlje River Basin, using modeling techniques: the IntErO model for calculation of runoff and soil loss. The model outcomes were validated through measurements of lake sediment deposition at the Potpec hydropower plant dam. Our findings indicate a medium potential of soil erosion risk. With 464 m³ yr-1 of annual sediment yield, corresponding to an area-specific sediment yield of 270 m³km-2 yr-1, the Novsicki Potok drainage basin belongs to the Montenegrin basins with the medium sediment discharge; according to the erosion type, it is surface erosion. The value of the Z coefficient was calculated on 0.403, what indicates that the river basin belongs to 3rd destruction category (of five). Our results suggest that the calculated peak discharge from the river basin was 82 m3s-1 for the incidence of 100 years. According to our analysis there is a possibility for large flood waves to appear in the studied river basin. With this research we, to some extent, improved the knowledge on the status of sediment yield and runoff of the river basins of Montenegro, where the map of Soil erosion is still not prepared. The IntErO model we used in this study is relatively novel concept and is highly recommended for soil erosion modelling in other river basins similar to the studied watershed, because of its simple identification of critical areas affected by the soil loss caused by soil erosion.

Data Summary Report for teh Remedial Investigation of Hanford Site Releases to the Columbia River, Hanford Site, Washington

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

Hulstrom, L.

2011-02-07

This data summary report summarizes the investigation results to evaluate the nature and distribution of Hanford Site-related contaminants present in the Columbia River. As detailed in DOE/RL-2008-11, more than 2,000 environmental samples were collected from the Columbia River between 2008 and 2010. These samples consisted of island soil, sediment, surface water, groundwater upwelling (pore water, surface water, and sediment), and fish tissue.

Diversity and Distribution Characteristics of Viruses in Soils of a Marine-Terrestrial Ecotone in East China.

PubMed

Yu, Dan-Ting; Han, Li-Li; Zhang, Li-Mei; He, Ji-Zheng

2018-02-01

A substantial gap remains in our understanding of the abundance, diversity, and ecology of viruses in soil although some advances have been achieved in recent years. In this study, four soil samples according to the salinity gradient from shore to inland in East China have been characterized. Results showed that spherical virus particles represented the largest viral component in all of the four samples. The viromes had remarkably different taxonomic compositions, and most of the sequences were derived from single-stranded DNA viruses, especially from families Microviridae and Circoviridae. Compared with viromes from other aquatic and sediment samples, the community compositions of our four soil viromes resembled each other, meanwhile coastal sample virome closely congregated with sediment and hypersaline viromes, and high salinity paddy soil sample virome was similar with surface sediment virome. Phylogenetic analysis of functional genes showed that four viromes have high diversity of the subfamily Gokushovirinae in family Microviridae and most of Circoviridae replicase protein sequences grouped within the CRESS-DNA viruses. This work provided an initial outline of the viral communities in marine-terrestrial ecotone and will improve our understanding of the ecological functions of soil viruses.

Novel sorbents for environmental remediation

NASA Astrophysics Data System (ADS)

Manariotis, Ioannis D.; Karapanagioti, Hrissi K.; Werner, David

2014-05-01

Nowadays, one of the major environmental problems is the pollution of aquatic systems and soil by persistent pollutants. Persistent pollutants have been found widespread in sediments, surface waters, and drinking water supplies. The removal of pollutants can be accomplished prior to their discharge to receiving bodies or by immobilizing them onto soil. Sorption is the most commonly applied process, and activated carbons have been widely used. Rapid progress in nanotechnology and a new focus on biomass-based instead of non-renewable starting materials have produced a wide range of novel engineered sorbents including biosorbents, biochars, carbon-based nanoparticles, bio-nano hybrid materials, and iron-impregnated activated carbons. Sorbent materials have been used in environmental remediation processes and especially in agricultural soil, sediments and contaminated soil, water treatment, and industrial wastewater treatment. Furthermore, sorbents may enhance the synergistic action of other processes, such as volatilization and biodegradation. Novel sorbents have been employed for the removal or immobilization of persistent pollutants such as and include heavy metals (As, Cr, Cu, Pb, Cd, and Hg), halogenated organic compounds, endocrine disrupting chemicals, metalloids and non-metallic elements, and other organic pollutants. The development and evaluation of novel sorbents requires a multidisciplinary approach encompassing environmental, nanotechnology, physical, analytical, and surface chemistry. The necessary evaluations encompass not only the efficiency of these materials to remove pollutants from surface waters and groundwater, industrial wastewater, polluted soils and sediments, etc., but also the potential side-effects of their environmental applications. The aim of this work is to present the results of the use of biochar and impregnated carbon sorbents for the removal of organic pollutants and metals. Furthermore, the new findings from the forthcoming session on Novel sorbents for environmental remediation, will also be evaluated and presented.

Non-point source pollution of glyphosate and AMPA in a rural basin from the southeast Pampas, Argentina.

PubMed

Okada, Elena; Pérez, Débora; De Gerónimo, Eduardo; Aparicio, Virginia; Massone, Héctor; Costa, José Luis

2018-05-01

We measured the occurrence and seasonal variations of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in different environmental compartments within the limits of an agricultural basin. This topic is of high relevance since glyphosate is the most applied pesticide in agricultural systems worldwide. We were able to quantify the seasonal variations of glyphosate that result mainly from endo-drift inputs, that is, from direct spraying either onto genetically modified (GM) crops (i.e., soybean and maize) or onto weeds in no-till practices. We found that both glyphosate and AMPA accumulate in soil, but the metabolite accumulates to a greater extent due to its higher persistence. Knowing that glyphosate and AMPA were present in soils (> 93% of detection for both compounds), we aimed to study the dispersion to other environmental compartments (surface water, stream sediments, and groundwater), in order to establish the degree of non-point source pollution. Also, we assessed the relationship between the water-table depth and glyphosate and AMPA levels in groundwater. All of the studied compartments had variable levels of glyphosate and AMPA. The highest frequency of detections was found in the stream sediments samples (glyphosate 95%, AMPA 100%), followed by surface water (glyphosate 28%, AMPA 50%) and then groundwater (glyphosate 24%, AMPA 33%). Despite glyphosate being considered a molecule with low vertical mobility in soils, we found that its detection in groundwater was strongly associated with the month where glyphosate concentration in soil was the highest. However, we did not find a direct relation between groundwater table depth and glyphosate or AMPA detections. This is the first simultaneous study of glyphosate and AMPA seasonal variations in soil, groundwater, surface water, and sediments within a rural basin.

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.

Carbon redistribution by erosion processes in an intensively disturbed catchment

NASA Astrophysics Data System (ADS)

Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

2016-04-01

Understanding how organic carbon moves with sediments along the fluvial system is crucial to close catchment scale carbon budgets. Especially challenging is the analysis of organic carbon dynamics during fluvial transport in heterogeneous, fragile and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale organic carbon redistribution by lateral flows in extreme Mediterranean environmental conditions from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, shallow soils, and highly disturbed by agricultural terraces, land levelling, reforestations and construction of check-dams. To increase understanding of erosion induced catchment scale organic carbon redistribution, we studied the subcatchments of 8 check-dams distributed along the catchment main channel in detail. We determined 137Cs, physicochemical characteristics and organic carbon pools of soils and sediments deposited behind each check-dam, performed spatial analysis of properties of the catchment and buffer areas around check-dams, and carried out geomorphological analysis of the slope-channel connections. Soils showed very low Total Organic Carbon (TOC) values oscillating between 15.2 and 4.4 g Kg-1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC compared to the eroded (forest) soils (6.6±0.7 g Kg-1), and the redistribution of organic carbon through the catchment, especially of the Mineral Associated Organic Carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates (0.031±0.03 Mg ha-1 y-1) were comparable to others reported for subhumid Mediterranean catchments and to those modelled worldwide for pasture land. Those lateral fluxes were equivalent to 10.4 % of the TOC stock from the topsoil at the moment of the check-dam construction and reforestation works. However the organic carbon in deposited sediments comes not only from surface erosion processes, but also from deeper soil or sediment layers mobilized by concentrated erosion processes. Sediment richer in organic carbon comes from the soil surface of vegetated (reforested) areas close and well connected to the channels. Subcatchments dominated by laminar erosion processes showed two times higher TOC/total erosion ratio than subcatchments dominated by concentrated flow erosion processes. Lithology, soils and geomorphology exert a more important control on organic carbon redistribution than land use and vegetation cover in this geomorphologically very active catchment.

Soil sealing and vesicular layer formation as initial structure development and its effect on infiltration

NASA Astrophysics Data System (ADS)

Badorreck, A.; Gerke, H. H.; Weller, U.; Vontobel, P.

2009-04-01

In the Lusatia mining district (NE-Germany) an artificial catchment was constructed to study initial ecosystem development and runoff generation. As a key process in this early stage, we investigate the surface structure dynamics as it strongly influences erosion, infiltration, matter dynamics, and vegetation establishment. The presented work focuses on observations of soil pore structure formation at the surface at five sites in the catchment and in an adjacent "younger" area composed of comparable sediments. Moreover we've conducted infiltration experiments in the lab and field to relate the soil pore structure to the hydraulic properties. The surface soil was sampled in cylindrical rings (10 cm³) down to 2 cm depth from which bulk density profiles were obtained using X-ray computed tomography (CT) (at UFZ- Halle, Germany) with a resolution of 0.084 mm. The influence of structure on infiltration was investigated using neutron radiography (at the NEUTRA facility of the Paul-Scherrer-Institut, Villigen, Switzerland) to visualise two-dimensional (2D) infiltration patterns. The slab-type samples were equilibrated to different initial water contents and then exposed to drip irrigation (to simulate rainfall) while a series of neutron radiographs were taken. In addition, field measurements with a miniature tension infiltrometer were conduced. The micro-tomographies exhibit formation of surface sealing whose thickness and intensity vary with silt and clay content. The CT images show several coarser- and finer-textured micro-layers at the sample surfaces that were formed as a consequence of repeated washing in of finer particles in underlying coarser sediment. In micro-depressions, the uppermost layers consist of sorted fine sand and silt due to wind erosion. Similar as for desert pavements, a vesicular pore structure developed in these sediments on top, but also scattered in fine sand- and silt-enriched micro-layers. The infiltration rates were severely affected by the surface crusts; however, the rates were independent of the vesicular pore layer.

Profiling bacterial diversity in a limestone cave of the western Loess Plateau of China

PubMed Central

Wu, Yucheng; Tan, Liangcheng; Liu, Wuxing; Wang, Baozhan; Wang, Jianjun; Cai, Yanjun; Lin, Xiangui

2015-01-01

Bacteria and archaea sustain subsurface cave ecosystems by dominating primary production and fueling biogeochemical cyclings, despite the permanent darkness and shortage of nutrients. However, the heterogeneity and underlying mechanism of microbial diversity in caves, in particular those well connect to surface environment are largely unexplored. In this study, we examined the bacterial abundance and composition in Jinjia Cave, a small and shallow limestone cave located on the western Loess Plateau of China, by enumerating and pyrosequencing small subunit rRNA genes. The results clearly reveal the contrasting bacterial community compositions in relation to cave habitat types, i.e., rock wall deposit, aquatic sediment, and sinkhole soil, which are differentially connected to the surface environment. The deposits on the cave walls were dominated by putative cave-specific bacterial lineages within the γ-Proteobacteria or Actinobacteria that are routinely found on cave rocks around the world. In addition, sequence identity with known functional groups suggests enrichments of chemolithotrophic bacteria potentially involved in autotrophic C fixation and inorganic N transformation on rock surfaces. By contrast, bacterial communities in aquatic sediments were more closely related to those in the overlying soils. This is consistent with the similarity in elemental composition between the cave sediment and the overlying soil, implicating the influence of mineral chemistry on cave microhabitat and bacterial composition. These findings provide compelling molecular evidence of the bacterial community heterogeneity in an East Asian cave, which might be controlled by both subsurface and surface environments. PMID:25870592

Profiling bacterial diversity in a limestone cave of the western Loess Plateau of China.

PubMed

Wu, Yucheng; Tan, Liangcheng; Liu, Wuxing; Wang, Baozhan; Wang, Jianjun; Cai, Yanjun; Lin, Xiangui

2015-01-01

Bacteria and archaea sustain subsurface cave ecosystems by dominating primary production and fueling biogeochemical cyclings, despite the permanent darkness and shortage of nutrients. However, the heterogeneity and underlying mechanism of microbial diversity in caves, in particular those well connect to surface environment are largely unexplored. In this study, we examined the bacterial abundance and composition in Jinjia Cave, a small and shallow limestone cave located on the western Loess Plateau of China, by enumerating and pyrosequencing small subunit rRNA genes. The results clearly reveal the contrasting bacterial community compositions in relation to cave habitat types, i.e., rock wall deposit, aquatic sediment, and sinkhole soil, which are differentially connected to the surface environment. The deposits on the cave walls were dominated by putative cave-specific bacterial lineages within the γ-Proteobacteria or Actinobacteria that are routinely found on cave rocks around the world. In addition, sequence identity with known functional groups suggests enrichments of chemolithotrophic bacteria potentially involved in autotrophic C fixation and inorganic N transformation on rock surfaces. By contrast, bacterial communities in aquatic sediments were more closely related to those in the overlying soils. This is consistent with the similarity in elemental composition between the cave sediment and the overlying soil, implicating the influence of mineral chemistry on cave microhabitat and bacterial composition. These findings provide compelling molecular evidence of the bacterial community heterogeneity in an East Asian cave, which might be controlled by both subsurface and surface environments.

Verification and completion of a soil data base for process based erosion model applications in Mato Grosso/Brazil

NASA Astrophysics Data System (ADS)

Schindewolf, Marcus; Schultze, Nico; Schönke, Daniela; Amorim, Ricardo S. S.; Schmidt, Jürgen

2014-05-01

The study area of central Mato Grosso is subjected to severe soil erosion. Continuous erosion leads to massive losses of top soil and related organic carbon. Consequently agricultural soil soils suffer a drop in soil fertility which only can be balanced by mineral fertilization. In order to control soil degradation and organic carbon losses of Mato Grosso cropland soils a process based soil loss and deposition model is used. Applying the model it will be possible to: - identify the main areas affected by soil erosion or deposition in different scales under present and future climate and socio-economic conditions - estimate the related nutrient and organic carbon losses/yields - figure out site-related causes of soil mobilization/deposition - locate sediment and sediment related nutrient and organic matter pass over points into surface water bodies - estimate the impacts of climate and land use changes on the losses of top soil, sediment bound nutrients and organic carbon. Model input parameters include digital elevation data, precipitation characteristics and standard soil properties as particle size distribution, total organic carbon (TOC) and bulk density. The effects of different types of land use and agricultural management practices are accounted for by varying site-specific parameters predominantly related to soil surface properties such as erosional resistance, hydraulic roughness and percentage ground cover. In this context the existing EROSION 3D soil parameter data base deducted from large scale rainfall simulations in Germany is verified for application in the study area, using small scale disc type rainfall simulator with an additional runoff reflux approach. Thus it's possible to enlarge virtual plot length up to at least 10 m. Experimental plots are located in Cuiabá region of central Mato Grosso in order to cover the most relevant land use variants and tillage practices in the region. Results show that derived model parameters are highly influenced by soil management. This indicates a high importance of tillage impact on resistance to erosion, mulch cover and TOC. The measured parameter ranges can generally be confirmed by the existing data base, which only need to be completed due to changed phenological stages in Mato Grosso compared to German conditions.

Runoff initiation, soil detachment and connectivity are enhanced as a consequence of vineyards plantations.

PubMed

Cerdà, A; Keesstra, S D; Rodrigo-Comino, J; Novara, A; Pereira, P; Brevik, E; Giménez-Morera, A; Fernández-Raga, M; Pulido, M; di Prima, S; Jordán, A

2017-11-01

Rainfall-induced soil erosion is a major threat, especially in agricultural soils. In the Mediterranean belt, vineyards are affected by high soil loss rates, leading to land degradation. Plantation of new vines is carried out after deep ploughing, use of heavy machinery, wheel traffic, and trampling. Those works result in soil physical properties changes and contribute to enhanced runoff rates and increased soil erosion rates. The objective of this paper is to assess the impact of the plantation of vineyards on soil hydrological and erosional response under low frequency - high magnitude rainfall events, the ones that under the Mediterranean climatic conditions trigger extreme soil erosion rates. We determined time to ponding, Tp; time to runoff, Tr; time to runoff outlet, Tro; runoff rate, and soil loss under simulated rainfall (55 mm h -1 , 1 h) at plot scale (0.25 m 2 ) to characterize the runoff initiation and sediment detachment. In recent vine plantations (<1 year since plantation; R) compared to old ones (>50 years; O). Slope gradient, rock fragment cover, soil surface roughness, bulk density, soil organic matter content, soil water content and plant cover were determined. Plantation of new vineyards largely impacted runoff rates and soil erosion risk at plot scale in the short term. Tp, Tr and Tro were much shorter in R plots. Tr-Tp and Tro-Tr periods were used as connectivity indexes of water flow, and decreased to 77.5 and 33.2% in R plots compared to O plots. Runoff coefficients increased significantly from O (42.94%) to R plots (71.92%) and soil losses were approximately one order of magnitude lower (1.8 and 12.6 Mg ha -1 h -1 for O and R plots respectively). Soil surface roughness and bulk density are two key factors that determine the increase in connectivity of flows and sediments in recently planted vineyards. Our results confirm that plantation of new vineyards strongly contributes to runoff initiation and sediment detachment, and those findings confirms that soil erosion control strategies should be applied immediately after or during the plantation of vines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sediment budget for five millennia of tillage in the Rockenberg catchment (Wetterau loess basin, Germany)

NASA Astrophysics Data System (ADS)

Houben, Peter

2012-10-01

The long-cultivated loess landscapes of central Europe provide the opportunity to explore the long-term perspective on the evolution human-natural sediment systems that are driven by human-caused soil erosion processes. A balance of spatially non-uniform sediment production, sedimentation and delivery was developed to highlight the quantitative dimensions and functioning of anthropogenic sediment redistribution in an undulating loess catchment of temperate Europe. The presented long-term perspective relies on analysing pedostratigraphic and lithostratigraphic field data from 728 corings across ˜10-km2, GIS-based data processing, and the analysis of data uncertainty. For a period of 5000 years of tillage, anthropogenic sediment production equals ˜9425 t ha-1, of which 62% still reside as colluvial sediment on the catchment's hillsides. The valley floors fulfil a sediment-conveyor function through transporting 77% of the sediment received from the hillsides. Whole-catchment yield to the contiguous higher-order valley is 29% of the amount of anthropogenic sediment production. The average catchment-scale depth of soil truncation is 0.64 m while the remaining anthropogenic sediment cover has an average thickness of 0.46 m (effective surface denudation: ˜0.18 m). The long-term integral net erosion rate is ˜0.5 t ha-1 a-1 because of extensive sediment retention on hillsides. The inherited human imprint on the soilscape, eventually, can be judged as beneficial rather than detrimental: the ubiquitous cover of humic colluvia generally is more suitable for intense cultivation than pristine pedostratigraphies. The sediment budget, although build from a historic perspective, also provides a plausible reference for realistic objectives of managing the soil erosion problem in human-natural sediment systems.

Sorption of selected pesticides on soils, sediment and straw from a constructed agricultural drainage ditch or pond.

PubMed

Vallée, Romain; Dousset, Sylvie; Billet, David; Benoit, Marc

2014-04-01

Buffer zones such as ponds and ditches are used to reduce field-scale losses of pesticides from subsurface drainage waters to surface waters. The objective of this study was to assess the efficiency of these buffer zones, in particular constructed wetlands, focusing specifically on sorption processes. We modelled the sorption processes of three herbicides [2-methyl-4-chlorophenoxyacetic acid (2,4-MCPA), isoproturon and napropamide] and three fungicides (boscalid, prochloraz and tebuconazole) on four substrates (two soils, sediment and straw) commonly found in a pond and ditch in Lorraine (France). A wide range of Freundlich coefficient (K fads) values was obtained, from 0.74 to 442.63 mg(1 - n) L (n) kg(-1), and the corresponding K foc values ranged from 56 to 3,725 mg(1 - n) L (n) kg(-1). Based on potential retention, the substrates may be classified as straw > sediments > soils. These results show the importance of organic carbon content and nature in the process of sorption. Similarly, the studied pesticides could be classified according to their adsorption capacity as follows: prochloraz > tebuconazole-boscalid > napropamide > MCPA-isoproturon. This classification is strongly influenced by the physico-chemical properties of pesticides, especially solubility and K oc. Straw exhibited the largest quantity of non-desorbable pesticide residues, from 12.1 to 224.2 mg/L for all pesticides. The presence of plants could increase soil-sediment sorption capacity. Thus, establishment and maintenance of plants and straw filters should be promoted to optimise sorption processes and the efficiency of ponds and ditches in reducing surface water pollution.

Fire Events and Soil Thermometry: The Applications of Clay Chemistry for Tracing Temperature Changes in Soils and Sediments Below Surface Fires

NASA Astrophysics Data System (ADS)

Watson, E.; Werts, S. P.; Gelabert, M.

2016-12-01

Fires in the natural environment affect the physical, chemical, and biological properties of soils. However, fires may also alter the mineralogy of the geologic material in which it comes in contact. Previous experiments on high temperature alteration of clays indicate that dehydration, oxidation, and hydroxylation in clay minerals can occur progressively in that order at increasing temperatures up to 500°C. It is also well known that wildfire events can heat soils to these temperature ranges several centimeters deep. In this experiment, alterations in clay chemistry were used as a tool to investigate fire intensity along with the changing morphology of clay minerals. For data collection, small camp fires were set in York County, SC and temperatures were recorded using a datalogger system to 5 cm deep during the fire event. Control samples were taken adjacent to the fires to compare the changing morphology of the minerals when heated. Powder x-ray diffraction and scanning electron microscopy were used to identify the clay mineralogy. The clay from soil samples was identified as hydrous kaolinite, anhydrous kaolinite, and varying types of goethite. To observe the dehydration, oxidation, and hydroxylation of clay minerals, scanning electron microscopy with emission dispersive spectroscopy was used to identify the O/cation ratios present, which would indicate changes in the oxidation state of the clay minerals. By mapping the changes in O/cation ratios with temperature in silicates, we are able to trace the temperature of the sediments during fire events. This research suggests it may be possible to utilize these geochemical trends to aid in soil and sediment temperature investigations in both archeological and modern soil and surface process investigations.

Soils on raised marine terraces in the Metaponto area, S Italy: not a simple chronosequence

NASA Astrophysics Data System (ADS)

Sauer, Daniela; Al-Sharif, Riyad; Wagner, Stephen; Scarciglia, Fabio; Deffontaines, Benoît; Benvenuti, Marco; Carnicelli, Stefano; Brückner, Helmut

2015-04-01

A sequence of Middle and Late Pleistocene raised marine terraces stretches along the Gulf of Taranto, S Italy, for more than 65 km from Rocca Imperiale, Calabria, in the SW to Taranto, Apulia, in the NE, in an approximately 25 km wide belt. The terraces formed as a result of the interplay between sea-level fluctuations and regional tectonic uplift over a time-span of ca. 780 ka. They were selected for establishing a soil chronosequence, in order to analyse rates of soil-forming processes in the central Mediterranean region. Indeed, several general trends of soil formation with terrace age were identified. For example, soil thickness and Fed/Fet ratios increase, while the weathering ratio (Ca+Mg+K+Na)/Al decreases with assumed terrace age. These changes could be best described by power functions (R2 = 0.88 for soil thickness, R2 = 0.87 for Fed/Fet, and R2 = 0.96 for (Ca+Mg+K+Na)/Al). However, closer examination revealed that the soils did not simply form in the marine gravel bodies but in various kinds of sediments. The development of the landscape along the Gulf of Taranto turned out to be much more complex than previously expected. Sediment-soil successions exposed in several gravel quarries reveal that each terrace, after its original formation, was exposed to changing conditions in terms of climate, vegetation, level of erosion base (related to sea-level oscillations and/or tectonics), and other environmental factors during the Pleistocene and Holocene periods. As a result, it was subject to (i) further geomorphological and sedimentological evolution, including incision, denudation, deposition of alluvial sediments, and accumulation of colluvial deposits, in parts due to natural processes and in parts due to human activity; (ii) various directions and rates of soil development, corresponding to changing environmental conditions during glacial and interglacial periods. In some cases, there is evidence for a period of soil formation in the marine deposits prior to the deposition of the alluvial sediments. For example, a several metres thick marine gravel body, overlain by a layer of alluvial sandy-loamy sediments, is exposed in a gravel quarry on terrace T2 (assumed to have accumulated during MIS 5c). The boundary between the two sediment packages is very sharp and wavy, indicating a period of incision into the gravel body prior to the deposition of the alluvial sediments. Based on these observations, the following chronological sequence of events is assumed for this site: 1) accumulation of the gravel body in a delta environment during MIS 5c; 2) period of soil formation during late MIS 5c, after the surface of the gravel body had fallen dry; 3) incision of creeks, cutting channels into the gravel body as sea level dropped during MIS 5b; 4) sea-level rise during MIS 5a, not reaching the same level as during MIS 5c due to progressing regional uplift in the meantime; wave action of the MIS 5a sea removed part of the MIS 5c gravel body and cut a cliff into it, thus shaping the seaward edge of terrace T2; 5) accumulation of alluvial deposits in the previously incised channels and on top of the erosional gravel-body surface during MIS 5a because of the raised erosion base level; 6) incorporation of sandy sediments from the near-by MIS 5a beach, possibly with some contribution from temporarily dry beds of the nearby torrential rivers, into the alluvial deposits. Similarly complex sediment successions can be observed in several exposures. In addition, in some locations up to several metres of loess-like sediments are exposed. They probably accumulated during glacial periods, being blown out from the wide, temporarily dry river beds and from the exposed shelf. These observations led to a more differentiated reconstruction of the evolution of the landscape and soils in the Metaponto area.

Physicochemical studies on Uburu Salt Lake Ebonyi State-Nigeria.

PubMed

Akubugwo, I E; Ofoegbu, C J; Ukwuoma, C U

2007-09-15

Physicochemical properties of soil (sediment) and water from Uburu salt lake were evaluated and compared with control soil and surface water from the same community. Results showed significant (p < 0.05) higher values for the heavy metals cadmium, chromium, copper, lead and zinc in the lake water relative to the control. The values of these metals in the lake soil (sediments) however, were significantly (p < 0.05) lower than the control soil. Similar significant (p < 0.05) elevations were observed in the lake water temperature, salinity, pH, calcium, magnesium, sodium, potassium, nitrate, carbonate, sulphate and phosphate levels compared to the control. Significant (p < 0.05) changes were also noted in the lake soil's pH, exchangeable acidity, nitrogen, organic carbon, calcium and magnesium levels. Also the soil texture was affected relative to the control. In a number of cases, the values of the studied parameters were higher than the permissible WHO standards. In view of these findings, cautious use of the salt lake soil and water is advocated.

Weathering of Olivine during Interaction of Sulfate Aerosols with Mars Soil under Current Climate Conditions

NASA Astrophysics Data System (ADS)

Niles, P. B.; Golden, D. C.; Michalski, J. R.; Ming, D. W.

2017-12-01

Sulfur concentrations in the Mars soils are elevated above 1 wt% in nearly every location visited by landed spacecraft. This observation was first made by the Viking landers, and has been confirmed by subsequent missions. The wide distribution of sulfur in martian soils has been attributed to volcanic degassing, formation of sulfate aerosols, and later incorporation into martian soils during gravitational sedimentation. However, later discoveries of more concentrated sulfur bearing sediments by the Opportunity rover has led some to believe that sulfates may instead be a product of evaporation and aeolian redistribution. One question that has not been addressed is whether the modern surface conditions are too cold for weathering of volcanic materials by sulfate aerosols. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars. Laboratory experiments were conducted to simulate weathering of olivine under Mars-like conditions. The weathering rates measured in this study suggest that fine grained olivine on Mars would weather into sulfate minerals in short time periods if they are exposed to H2SO4 aerosols at temperatures at or above -40°C. In this system, the strength of the acidic solution is maximized through eutectic freezing in an environment where the silicate minerals are extremely fine grained and have high surface areas. This provides an ideal environment for olivine weathering despite the very low temperatures. The likelihood of substantial sulfur-rich volcanism on Mars and creation of abundant sulfate aerosols suggests that this process would have been important during formation of martian soils and sediments. Future work modeling sulfur release rates during volcanic eruptions and aerosol distribution over the surface will help understand how well this process could concentrate sulfate minerals in nearby surface materials or whether this process would simply result in widespread globally distributed sulfur materials.

Polycyclic aromatic hydrocarbons in soil and surface marine sediment near Jubany Station (Antarctica). Role of permafrost as a low-permeability barrier.

PubMed

Curtosi, Antonio; Pelletier, Emilien; Vodopivez, Cristian L; Mac Cormack, Walter P

2007-09-20

Although Antarctica is still considered as one of the most pristine areas of the world, the growing tourist and fisheries activities as well as scientific operations and their related logistic support are responsible for an increasing level of pollutants in this fragile environment. Soils and coastal sediments are significantly affected near scientific stations particularly by polycyclic aromatic hydrocarbons (PAHs). In this work sediment and soil were sampled in two consecutive summer Antarctic expeditions at Potter Cove and peninsula, in the vicinity of Jubany Station (South Shetland Islands). Two- and 3-ring PAHs (methylnaphthalene, fluorene, phenanthrene and anthracene) were the main compounds found in most sites, although total PAH concentrations showed relatively low levels compared with other human-impacted areas in Antarctica. Pattern distribution of PAHs observed in samples suggested that low-temperature combustion processes such as diesel motor combustion and open-field garbage burning are the main sources of these compounds. An increase in PAH concentrations was observed from surface to depth into the active soil layer except for a unique sampling site where a fuel spill had been recently reported and where an inverted PAH concentration gradient was observed. The highest level was detected in the upper layer of permafrost followed by a sharp decrease in depth, showing this layer is acting as a barrier for downward PAH migration. When PAH levels in soil from both sampling programs were compared a significant decrease (p<0.01) was observed in summer 2005 (range at 75-cm depth: 12+/-1-153+/-22 ng/g) compared to summer 2004 (range at 75-cm depth: 162+/-15-1182+/-113 ng/g) whereas concentrations in surface sediment collected nearby the station PAHs increased drastically in 2005 (range: 36+/-3-1908+/-114 ng/g) compared to 2004 (range: 28+/-3-312+/-24 ng/g). Precipitation regime and water run off suggest that an important wash out of soil-PAHs occurred during the interval time between samplings. Results showed that the present PAH contamination level of Jubany Station is relatively low compared to other reported cases in Antarctica but also suggests that an increase in rain and in thawing processes caused by the global warming could result in an important soil-associated PAH mobilization with unpredictable consequences for the biota of Potter Cove.

RUNOFF, SEDIMENT TRANSPORT, AND SURFACE COLLAPSE AT A LOW-LEVEL RADIOACTIVE-WASTE BURIAL SITE NEAR SHEFFIELD, ILLINOIS.

USGS Publications Warehouse

Gray, John R.; Peters, Charles A.; ,

1985-01-01

Runoff, sediment transport, and precipitation were measured in three gaged basins composing two-thirds of the 20-acre site, and in a 3. 5-acre basin located 0. 3 mile south of the site. Locations and dimensions of surface collapses at the site were recorded by the site contractor. Volumes of collapsed material were calculated and converted to an equivalent weight of earth material by applying a mean value for the bulk density of soils at the site.

Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

NASA Astrophysics Data System (ADS)

Seitz, Steffen; Nebel, Martin; Goebes, Philipp; Käppeler, Kathrin; Schmidt, Karsten; Shi, Xuezheng; Song, Zhengshan; Webber, Carla L.; Weber, Bettina; Scholten, Thomas

2017-12-01

This study investigated the development of biological soil crusts (biocrusts) in an early successional subtropical forest plantation and their impact on soil erosion. Within a biodiversity and ecosystem functioning experiment in southeast China (biodiversity and ecosystem functioning (BEF) China), the effect of these biocrusts on sediment delivery and runoff was assessed within micro-scale runoff plots under natural rainfall, and biocrust cover was surveyed over a 5-year period. Results showed that biocrusts occurred widely in the experimental forest ecosystem and developed from initial light cyanobacteria- and algae-dominated crusts to later-stage bryophyte-dominated crusts within only 3 years. Biocrust cover was still increasing after 6 years of tree growth. Within later-stage crusts, 25 bryophyte species were determined. Surrounding vegetation cover and terrain attributes significantly influenced the development of biocrusts. Besides high crown cover and leaf area index, the development of biocrusts was favoured by low slope gradients, slope orientations towards the incident sunlight and the altitude of the research plots. Measurements showed that bryophyte-dominated biocrusts strongly decreased soil erosion, being more effective than abiotic soil surface cover. Hence, their significant role in mitigating sediment delivery and runoff generation in mesic forest environments and their ability to quickly colonise soil surfaces after disturbance are of particular interest for soil erosion control in early-stage forest plantations.

Chemical, Mineralogical, and Physical Properties of Martian Dust and Soil

NASA Technical Reports Server (NTRS)

Ming, D. W.; Morris, R. V.

2017-01-01

Global and regional dust storms on Mars have been observed from Earth-based telescopes, Mars orbiters, and surface rovers and landers. Dust storms can be global and regional. Dust is material that is suspended into the atmosphere by winds and has a particle size of 1-3 micrometer. Planetary scientist refer to loose unconsolidated materials at the surface as "soil." The term ''soil'' is used here to denote any loose, unconsolidated material that can be distinguished from rocks, bedrock, or strongly cohesive sediments. No implication for the presence or absence of organic materials or living matter is intended. Soil contains local and regional materials mixed with the globally distributed dust by aeolian processes. Loose, unconsolidated surface materials (dust and soil) may pose challenges for human exploration on Mars. Dust will no doubt adhere to spacesuits, vehicles, habitats, and other surface systems. What will be the impacts on human activity? The objective of this paper is to review the chemical, mineralogical, and physical properties of the martian dust and soil.

25 CFR 216.7 - Approval of mining plan.

Code of Federal Regulations, 2014 CFR

2014-04-01

... suitable map, or aerial photograph showing the topography, the area covered by the permit or lease, the... as to reduce soil erosion and sedimentation and to prevent the pollution of receiving waters; (6) A description of measures to be taken to prevent or control fire, soil erosion, pollution of surface and ground...

25 CFR 216.7 - Approval of mining plan.

Code of Federal Regulations, 2012 CFR

2012-04-01

... suitable map, or aerial photograph showing the topography, the area covered by the permit or lease, the... as to reduce soil erosion and sedimentation and to prevent the pollution of receiving waters; (6) A description of measures to be taken to prevent or control fire, soil erosion, pollution of surface and ground...

25 CFR 216.7 - Approval of mining plan.

Code of Federal Regulations, 2013 CFR

2013-04-01

... suitable map, or aerial photograph showing the topography, the area covered by the permit or lease, the... as to reduce soil erosion and sedimentation and to prevent the pollution of receiving waters; (6) A description of measures to be taken to prevent or control fire, soil erosion, pollution of surface and ground...

[Pollution and Potential Ecology Risk Evaluation of Heavy Metals in River Water, Top Sediments on Bed and Soils Along Banks of Bortala River, Northwest China].

PubMed

Zhang, Zhao-yong; Abuduwaili, Jilili; Jiang, Feng-qing

2015-07-01

This paper focuses on the sources, pollution status and potential ecology risks of heavy metals (Cr, Cu, Hg, As, Cd, Pb, and Zn) in the surface water, top sediment of river bed and soil along banks of Bortala River, which locates in the oasis region of Xinjiang, northwest China. Results showed that: (1) As a whole, contents of 7 tested heavy metals of Bortala River were low, while the maximum values of Hg, Cd, Pb, and Cr in the river water were significantly higher than those of Secondary Category of the Surface Water Quality Standards of People's Republic of China (GB 3838-2002) and Drinking Water Guideline from WHO. Analysis showed that the heavy metals contents of top sediment on river bed and soils along river banks were significantly higher than those of the river water. (Correlation analysis and enrichment factor (EF) calculation showed that in the river water, top sediment on river bed and soils along river banks, Hg, Cd, Pb, and Cr mainly originated from industrial emissions, urban and rural anthropogenic activities, transportation and agricultural production activities; While Cu, Zn, and As mainly originated from natural geological background and soil parent materials. (3) Pollution assessment showed that in three matrices, the single factor pollution index(Pi) and the integrated pollution index (Pz) of 7 heavy metals were all lower than 1, and they all belonged to safe and clean levels. (4) Potential ecology risk evaluation showed that as a whole the single factor potential ecological risk (Eir) and the integrated potential ecology risks (RI) of 7 heavy metals were relatively low, and would not cause threats to the health of water and soil environment of river basin, while the potential ecology risks of Cd, Hg, Pb, and Cr were significantly higher than those of other heavy metals.

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

DOE PAGES

McCorkle, Emma P.; Berhe, Asmeret Asefaw; Hunsaker, Carolyn T.; ...

2016-04-29

Here, soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance levels of the stable and radioactive isotopes of C ( 13C and 14C) and stable isotope of nitrogen ( 15N) to elucidate the origins of SOM eroded from low-order catchments along the western slopes of the Sierra Nevada of California, USA. Our work was conducted in two relatively undisturbed catchmentsmore » (low elevation = 1800 m, and high elevation = 2300 m) of the Kings River Experimental Watersheds (KREW) in the Sierra National Forest. Sediment captured in basins at the outlet of each gauged watershed were compared to possible source materials, which included: upland surficial organic horizons (i.e., forest floor) and mineral soils (0–0.6 m) from three landform positions (i.e., crest, backslope, and toeslope), stream bank soils (0–0.6 m), and stream-bed materials (0–0.05 m). We found that most of the organic matter (OM) in the captured sediments was composed of O-horizon material that had high C concentrations. Radiocarbon analyses also showed that the captured OM is composed of modern (post-1950) C, with fraction modern values at or above 1.0. Our results suggest that surface (sheet) erosion, as opposed to channeling through established streams and episodic mass wasting events, is likely the largest source of sediment exported out of these minimally disturbed, headwater catchments. The erosional export of sediment with a high concentration of C, especially in the form of relatively undecomposed litter from the O horizon, suggests that a large fraction of the exported C is likely to be decomposed during or after erosion; hence, it is unlikely that soil erosion acts as a significant net sink for atmospheric CO 2 in these low-order, temperate forest catchments.« less

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

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

McCorkle, Emma P.; Berhe, Asmeret Asefaw; Hunsaker, Carolyn T.

Here, soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance levels of the stable and radioactive isotopes of C ( 13C and 14C) and stable isotope of nitrogen ( 15N) to elucidate the origins of SOM eroded from low-order catchments along the western slopes of the Sierra Nevada of California, USA. Our work was conducted in two relatively undisturbed catchmentsmore » (low elevation = 1800 m, and high elevation = 2300 m) of the Kings River Experimental Watersheds (KREW) in the Sierra National Forest. Sediment captured in basins at the outlet of each gauged watershed were compared to possible source materials, which included: upland surficial organic horizons (i.e., forest floor) and mineral soils (0–0.6 m) from three landform positions (i.e., crest, backslope, and toeslope), stream bank soils (0–0.6 m), and stream-bed materials (0–0.05 m). We found that most of the organic matter (OM) in the captured sediments was composed of O-horizon material that had high C concentrations. Radiocarbon analyses also showed that the captured OM is composed of modern (post-1950) C, with fraction modern values at or above 1.0. Our results suggest that surface (sheet) erosion, as opposed to channeling through established streams and episodic mass wasting events, is likely the largest source of sediment exported out of these minimally disturbed, headwater catchments. The erosional export of sediment with a high concentration of C, especially in the form of relatively undecomposed litter from the O horizon, suggests that a large fraction of the exported C is likely to be decomposed during or after erosion; hence, it is unlikely that soil erosion acts as a significant net sink for atmospheric CO 2 in these low-order, temperate forest catchments.« less

Modelling landscape evolution at the flume scale

NASA Astrophysics Data System (ADS)

Cheraghi, Mohsen; Rinaldo, Andrea; Sander, Graham C.; Barry, D. Andrew

2017-04-01

The ability of a large-scale Landscape Evolution Model (LEM) to simulate the soil surface morphological evolution as observed in a laboratory flume (1-m × 2-m surface area) was investigated. The soil surface was initially smooth, and was subjected to heterogeneous rainfall in an experiment designed to avoid rill formation. Low-cohesive fine sand was placed in the flume while the slope and relief height were 5 % and 20 cm, respectively. Non-uniform rainfall with an average intensity of 85 mm h-1 and a standard deviation of 26 % was applied to the sediment surface for 16 h. We hypothesized that the complex overland water flow can be represented by a drainage discharge network, which was calculated via the micro-morphology and the rainfall distribution. Measurements included high resolution Digital Elevation Models that were captured at intervals during the experiment. The calibrated LEM captured the migration of the main flow path from the low precipitation area into the high precipitation area. Furthermore, both model and experiment showed a steep transition zone in soil elevation that moved upstream during the experiment. We conclude that the LEM is applicable under non-uniform rainfall and in the absence of surface incisions, thereby extending its applicability beyond that shown in previous applications. Keywords: Numerical simulation, Flume experiment, Particle Swarm Optimization, Sediment transport, River network evolution model.

Phytoremediation management of selenium-laden drainage sediments in the San Luis Drain: a greenhouse feasibility study.

PubMed

Bañuelos, G S; Lin, Z-Q

2005-11-01

An estimated 100,000m(3) selenium (Se)-laden drainage sediment resides in the San Luis Drain (SLD) of Central California. This greenhouse study was undertaken to evaluate the feasibility of growing salt- and boron-tolerant plant species in sediment for reduction of Se content by plant extraction. Drainage sediment was collected from the SLD and mixed with control soil (i.e., uncontaminated soil) to the following ratios (sediment:control soil) by volume: 0:3 (i.e., control soil only), 1:2 (i.e., 1/3 sediment and 2/3 control soil), 2:1 (i.e., 2/3 sediment and 1/3 control soil), and 3:0 (i.e., sediment only). Salt-tolerant plant species consisted of canola (Brassica napus var. Hyola 420), tall fescue (Festuca arundinacea var. Au Triumph), salado grass (Sporobulus airoides), and cordgrass (Spartina patens var. Flageo). Increased ratios of sediment:soil resulted in decreased dry matter production for all tested plant species; especially at ratios of sediment:soil greater than 1:2. Plant Se concentrations (mgkg(-1) DM) ranged as follows for plant species at all ratios of sediment:soil: canola (51-72), tall fescue (16-36), and cordgrass and salado grass (9-14). Total Se concentrations in the soil were at least 20% lower at postharvest compared to preplant concentrations for all plant species at each ratio of sediment:soil. In contrast, water-extractable Se concentrations in the soil were at least three times higher at postharvest than at preplant for all plant species, irrespective of the ratio of sediment:soil. Leaching of Se occurred in irrigated bare pots from each respective ratio of sediment:soil over a duration of 60 days. Based upon the downward movement of Se in bare pots of sediment:soil, it may be more prudent to leave the drainage sediment in the SLD, incorporate clean soil, and then grow low maintenance salt-tolerant plants (e.g., cordgrass, salado grass) in the concrete-lined canal. By this means, possible contamination of groundwater with soluble Se will be eliminated, while phytoremediation slowly reduces Se content in the drainage sediment.

Major and trace element distribution in soil and sediments from the Egyptian central Nile Valley

NASA Astrophysics Data System (ADS)

Badawy, W. M.; Ghanim, E. H.; Duliu, O. G.; El Samman, H.; Frontasyeva, M. V.

2017-07-01

The distributions of 32 major and trace elements in 72 surface soil and sediment samples collected from the Asyut to Cairo Nile river section were determined by epithermal neutron activation analysis and compared with corresponding data for the Upper Continental Crust, North American Shale Composite, Average Soil and Average Sediment as well as suspended sediments from Congo and Upper Niger Rivers, in order to establish to which extent the Nile sedimentary material can be related to similar material all over the world as well as to local geology. Their relative distributions indicate the presence of detrital material of igneous origin, most probably resulting from weathering of the Ethiopian Highlands and transported by the Blue Nile, the Nile main tributary. The distributions of nickel, zinc, and arsenic contents suggest that the lower part of the Nile and its surroundings including the Nile Delta is not seriously polluted with heavy metals, so that, in spite of a human activity, which lasted four millennia, the Nile River continues to be less affected by any anthropogenic contamination.

Heavy metal pollution of soils and sediments at the historical smelting site of the Rudawy Janowickie Mountains (Lower Silesia, Poland).

NASA Astrophysics Data System (ADS)

Kierczak, Jakub; Néel, Catherine; Pietranik, Anna

2010-05-01

Multidisciplinary studies of historical slags are mostly focused on exploring how metallurgy evolved through human history. Another purpose for studying historical slags are potentially harmful interactions between slags, surrounding soils, sediments and waters. Metallurgical slags generally concentrate potentially toxic elements (PTE) such as arsenic, copper and lead. These elements may be mobilized and transferred into immediate surroundings. The main aim of our work is to identify factors controlling migration of metals at the historical smelting site of the Rudawy Janowickie Mountains. This study involves detailed analyzes of historical slags (older than 300 years) containing PTE, as well as surrounding soils and sediments. The Rudawy Janowickie Mountains represented an important centre of copper mining and smelting in Poland until 1925 with metallurgical activities being documented as early as in the XIV century. The exploitation of Cu ores has left large amounts of mine tailings and slags extending over ca. 35ha. The slags were deposited on ground and no barriers between the slags and environment were set. Therefore, they were continuously affected by variable factors, for example, changing weather conditions. Soils located in the study area are derived from granitic rocks. They are shallow (< 1 meter depth) and skeletic (containing > 50 wt. % of coarse fragments). Their pHw is acidic and varies from 3.4 to 4.5 from the topsoil to the deeper horizons in which slags are widespread. Mineral composition of soils and sediments is dominated by quartz, alkali feldspar, plagioclase and biotite. However, some samples may contain additionally numerous slag fragments. At present, the slags occur within three types of environments: (1) at the surface, (2) in soils and (3) in sediments from two streams: Janówka and Smelter Stream. Studied slags were sampled in the vicinity of both streams from (1) surface, (2) soil profiles and (3) streambeds. Furthermore, samples of soils and stream sediments were collected at the same time in order to observe weathering features of slags in different environments and to verify the influence of those wastes on properties of soils and sediments. Studied slags are isometric and well rounded (pebble-like), with size ranging from few to dozens of centimetres. The average chemical composition of slags is 47 wt. % Fe2O3, 40 wt. % SiO2, 8 wt. % Al2O3. Slags show elevated concentrations of Cu (up to 13400 ppm), Zn (up to 3640 ppm), Pb (up to 270 ppm) and As (up to 130 ppm). Dominant type of slag occurring in all environments is black and has massive texture. It consists of silicate glass, fayalite, hercynite, bornite, pyrhotite, intermetallic compounds of Fe and As, metallic Pb and Cu. Sulfides and metallic phases are the most important PTE carriers. Second type of slag was found only on surface. It is highly porous and often encloses small fragments of granitic rocks. Despite weathered appearance, it has similar phase composition to the dominant type of slag. The weathering products occur as aureoles and interstitial replacements within the sulfides. Secondary phases in the aureoles are: brochantite, malachite and Fe oxy-hydroxides. PTE initially concentrated in primary phases such as sulfides can be mobilized by weathering and be subsequently bounded in secondary phases (brochantite, malachite). The stability of these phases depends on the surrounding conditions (e.g. here, secondary phases are stable only in slags from surface). Presence of slags at the studied site is clearly documented by geochemical analysis of stream sediments. The Cu concentration in sediments from the area where no slags have been found is 8 ppm, while it exceeds 130 ppm in the site where slags are widespread. Our observations thus show that the studied slags release some potentially toxic elements (especially Cu) during weathering and the slag texture appears to be an important factor controlling metal migration. The work was financed by Polish Ministry of Science and Higher Education grant no. 4269/PB/ING/09.

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).

Utilising Structure-From-Motion Approaches to Develop a Spatial Understanding of Soil Erosion Processes, in an Experimental Setting.

NASA Astrophysics Data System (ADS)

Benaud, P.; Anderson, K.; Quine, T. A.; James, M. R.; Quinton, J.; Brazier, R. E.

2016-12-01

While total sediment capture can accurately quantify soil loss via water erosion, it isn't practical at the field scale and provides little information on the spatial nature of soil erosion processes. Consequently, high-resolution, remote sensing, point cloud data provide an alternative method for quantifying soil loss. The accessibility of Structure-from-Motion Multi-Stereo View (SfM) and the potential for multi-temporal applications, offers an exciting opportunity to spatially quantify soil erosion. Accordingly, published research provides examples of the successful quantification of large erosion features and events, to centimetre accuracy. Through rigorous control of the camera and image network geometry, the centimetre accuracy achievable at the field scale, can translate to sub-millimetre accuracies within a laboratory environment. Accordingly, this study looks to understand how the ultra-high-resolution spatial information on soil surface topography, derived from SfM, can be integrated with a multi-element sediment tracer to develop a mechanistic understanding of rill and inter-rill erosion, under experimental conditions. A rainfall simulator was used to create three soil surface conditions; compaction and rainsplash, inter-rill erosion, and rill erosion, at two experimental scales (0.15 m2 and 3 m2). Total sediment capture was the primary validation for the experiments, allowing the comparison between structurally and volumetrically derived change, and true soil loss. A Terrestrial Laser Scanner (resolution of ca. 0.8mm) has been employed to assess spatial discrepancies within the SfM data sets and to provide an alternative measure of volumetric change. Preliminary results show the SfM approach used can achieve a ground resolution of less than 0.2 mm per pixel, and a RMSE of less than 0.3 mm. Consequently, it is expected that the ultra-high-resolution SfM point clouds can be utilised to provide a detailed assessment of soil loss via water erosion processes.

Lipid-based palaeotemperature reconstruction in lakes: New insights on the applicability of branched GDGTs in lacustrine sedimentary archives

NASA Astrophysics Data System (ADS)

Weber, Yuki; De Jonge, Cindy; Hopmans, Ellen C.; Sinninghe Damsté, Jaap S.; Gilli, Adrian; Lehmann, Moritz F.; Niemann, Helge

2014-05-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that occur ubiquitously in soils worldwide. The relative abundances of nine structurally related brGDGTs (used in the MBT and CBT indices) have been shown to correlate with mean annual air temperature (MAAT) and soil pH, making them potential proxies in sediments that receive soil organic matter from terrestrial environments. The brGDGT distributions in lake deposits, however, mostly follow a different correlation with air temperature and (to a minor extent) lake water pH. This points to a substantial contribution of brGDGTs from in situ production within the lake water column and/or -sediments. It is also quite likely that the fractions of soil- and lake-derived brGDGTs vary considerably between sampling sites and with time, due to spatial and temporal changes in sediment input rates. Paleoclimate reconstructions using lacustrine brGDGT records thus remain challenging, especially because little is known about the environmental variables that control bacterial brGDGT production within aquatic environments. In order to decipher the impact of in situ production, we compared the brGDGT composition of surface sediments and corresponding catchment soils of 35 lakes from the Swiss alpine region, spanning an altitudinal gradient from 200 - 2000 m above mean sea level. We used an improved HPLC method to additionally quantify six recently discovered isomers, which vary in the position of their methyl branches. These 6-methyl compounds previously co-eluted with those brGDGTs used to calculate the MBT and CBT indices, obscuring any paleoenvironmental information they potentially yield. A principal component analysis suggests that the fractional abundances of the 6-methyl brGDGTs are primarily controlled by the surface water pH of the lakes. Notably, and in contrast to soils, the fractional abundance of the 5-methyl pentamethylated brGDGT in lake sediments does not show a correlation with MAAT (derived from the lapse rate model), possibly pointing to different source organisms in soils and lakes. Our results imply that in situ production of brGDGTs plays a mayor role. By further constraining the environmental controls on lake-derived brGDGTs, we aim to improve the future applicability of brGDGT-based proxies in lacustrine climate archives.

Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients

USGS Publications Warehouse

Reynolds, R.; Neff, J.; Reheis, M.; Lamothe, P.

2006-01-01

Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5-40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of far-traveled aeolian dust can be estimated from magnetic properties that primarily reflect magnetite content, such as isothermal remanent magnetization (IRM). Isothermal remanent magnetization was measured on bulk sediment samples taken along two transects in surficial sediment down gentle slopes away from sandstone headwalls. One transect was in undisturbed surficial sediment, the other in a setting that was grazed by domestic livestock until 1974. Calculation of far-traveled dust contents of the surficial deposits is based on measurements of the magnetic properties of rock, surficial deposits, and modern dust using a binary mixing model. At the undisturbed site, IRM-based calculations show a systematic down-slope increase in aeolian dust (ranging from 2% to 18% of the surface soil mass), similar to the down-slope increase in total fines (18-39% of surface soil mass). A combination of winnowing by wind during the past and down-slope movement of sediment likely accounts for the modern distribution of aeolian dust and associated nutrients. At the previously grazed site, dust also increases down slope (5-11%) in sediment with corresponding abundances of 13-25% fines. Estimates of the contributions of aeolian dust to the total soil nutrients range widely, depending on assumptions about grain-size partitioning of potential nutrients in weathered bedrock. Nevertheless, aeolian dust is important for this setting, contributing roughly 40-80% of the rock-derived nutrient stocks (P, K, Na, Mn, Zn, and Fe) in uppermost soil over most of the sampled slope at the undisturbed site, which shows no evidence of recent wind erosion. ?? 2005 Elsevier B.V. All rights reserved.

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

Enrichment of Arsenic in Surface Water, Stream Sediments and Soils in Tibet.

PubMed

Li, Shehong; Wang, Mingguo; Yang, Qiang; Wang, Hui; Zhu, Jianming; Zheng, Baoshan; Zheng, Yan

2013-12-01

Groundwater in sedimentary deposits in China, Southern, and Southeast Asia down gradient from the Tibetan plateau contain elevated As concentrations on a regional scale. To ascertain the possibility of source region As enrichment, samples of water (n=86), stream sediment (n=77) and soil (n=73) were collected from the Singe Tsangpo (upstream of the Indus River), Yarlung Tsangpo (upstream of the Brahmaputra River) and other drainage basins in Tibet in June of 2008. The average arsenic concentration in stream waters, sediments and soils was 58±70 μg/L (n=39, range 2-252 μg/L), 42±40 mg/kg (n=37, range 12-227 mg/kg), and 44±27mg/kg (n=28, range 12-84 mg/kg) respectively for the Singe Tsangpo and was 11±17 μg/L (n=30, range 2-83 μg/L), 28±11 mg/kg (n=28, range 2-61 mg/kg), and 30±34 mg/kg (n=21, range 6-173 mg/kg) respectively for the Yarlung Tsangpo. A dug well contained 195 μg/L of As. In addition to elevated As levels in surface and shallow groundwater of Tibet, hot spring and alkaline salt lake waters displayed very high As levels, reaching a maximum value of 5,985 μg/L and 10,626 μg/L As, respectively. The positive correlation between [As] and [Na]+[K] in stream waters indicates that these surface water arsenic enrichments are linked to the hot springs and/or salt lakes. Further, 24% of As in stream sediment is reductively leachable, with bulk As displaying a positive correlation with stream water As, suggesting sorption from stream water. In contrast, the fraction of reductively leachable As is negligible for soils and several rock samples, suggesting that As in them are associated with unweathered minerals. Whether the pronounced As anomaly found in Tibet affects the sedimentary As content in deltas downstream or not requires further study.

Enrichment of Arsenic in Surface Water, Stream Sediments and Soils in Tibet

PubMed Central

Li, Shehong; Wang, Mingguo; Yang, Qiang; Wang, Hui; Zhu, Jianming; Zheng, Baoshan; Zheng, Yan

2013-01-01

Groundwater in sedimentary deposits in China, Southern, and Southeast Asia down gradient from the Tibetan plateau contain elevated As concentrations on a regional scale. To ascertain the possibility of source region As enrichment, samples of water (n=86), stream sediment (n=77) and soil (n=73) were collected from the Singe Tsangpo (upstream of the Indus River), Yarlung Tsangpo (upstream of the Brahmaputra River) and other drainage basins in Tibet in June of 2008. The average arsenic concentration in stream waters, sediments and soils was 58±70 μg/L (n=39, range 2-252 μg/L), 42±40 mg/kg (n=37, range 12-227 mg/kg), and 44±27mg/kg (n=28, range 12-84 mg/kg) respectively for the Singe Tsangpo and was 11±17 μg/L (n=30, range 2-83 μg/L), 28±11 mg/kg (n=28, range 2-61 mg/kg), and 30±34 mg/kg (n=21, range 6-173 mg/kg) respectively for the Yarlung Tsangpo. A dug well contained 195 μg/L of As. In addition to elevated As levels in surface and shallow groundwater of Tibet, hot spring and alkaline salt lake waters displayed very high As levels, reaching a maximum value of 5,985 μg/L and 10,626 μg/L As, respectively. The positive correlation between [As] and [Na]+[K] in stream waters indicates that these surface water arsenic enrichments are linked to the hot springs and/or salt lakes. Further, 24% of As in stream sediment is reductively leachable, with bulk As displaying a positive correlation with stream water As, suggesting sorption from stream water. In contrast, the fraction of reductively leachable As is negligible for soils and several rock samples, suggesting that As in them are associated with unweathered minerals. Whether the pronounced As anomaly found in Tibet affects the sedimentary As content in deltas downstream or not requires further study. PMID:24367140

Using Short-Lived Fallout Radionuclides to Study Soil Mixing on Hillslopes in Different Climatic and Tectonic Settings

NASA Astrophysics Data System (ADS)

Kaste, J. M.; Heimsath, A. M.

2002-12-01

Hillslope soil processes can be difficult to quantify, but an understanding of soil and sediment dynamics is required for an accurate prediction of topographic evolution. Our data indicate that soil mixing processes and rates on hillslopes vary widely across different climatic and geologic settings. We use the depth-profiles of short-lived fallout radionuclides 210Pb, 137Cs, and 241Am measured in soils sampled from the Hubbard Brook Experimental Forest in NH (HBEF), USA, from Point Rays National Seashore (PRNS), CA, USA, and from the Nunnock River Valley (NR) in Southeastern Australia to study short-term (<100 y) soil mixing resulting from bioturbation. Results from the radionuclide analysis suggest that some fraction of the soil at NR is mixed from the surface to a depth of up to 0.5m on timescales of a few decades. These results support previous studies at NR quantifying soil mixing at millennial timescales using optically stimulated luminescence (OSL). Field evidence at NR corroborates these data, showing a clear lack of soil profile development and differentiation. However, in well-developed spodosols at the HBEF, radionuclide data suggests that mixing is confined to the forest floor (upper 12 cm of organic matter) and surface grains do not penetrate to significant depth in the profile on short timescales. Tree-throw seems to be the primary process mixing soil at the HBEF, which mixes soil on timescales of several centuries. At NR and PRNS however, bioturbation by insects and burrowing mammals mixes surface soil particles deep into the profile on timescales of decades. These differences in bioturbation rates result from different climatic and geologic settings, and we will discuss the implications for sediment transport mechanisms on hillslopes, as well as for soil carbon storage and the fate of atmospherically-delivered conaminants.

Hurricane Katrina sediment slowed elevation loss in subsiding brackish marshes of the Mississippi River delta

USGS Publications Warehouse

McKee, K.L.; Cherry, J.A.

2009-01-01

Although hurricanes can damage or destroy coastal wetlands, they may play a beneficial role in reinvigorating marshes by delivering sediments that raise soil elevations and stimulate organic matter production. Hurricane Katrina altered elevation dynamics of two subsiding brackish marshes in the Mississippi River deltaic plain by adding 3 to 8 cm of sediment to the soil surface in August 2005. Soil elevations at both sites subsequently declined due to continued subsidence, but net elevation gain was still positive at both Pearl River (+1.7 cm) and Big Branch (+0.7 cm) marshes two years after the hurricane. At Big Branch where storm sediments had higher organic matter and water contents, post-storm elevation loss was more rapid due to initial compaction of the storm layer in combination with root-zone collapse. In contrast, elevation loss was slower at Pearl River where the storm deposit (high sand content) did not compact and the root zone did not collapse. Vegetation at both sites fully recovered within one year, and accumulation of root matter at Big Branch increased 10-fold from 2005 to 2006, suggesting that the hurricane stimulated belowground productivity. Results of this study imply that hurricane sediment may benefit subsiding marshes by slowing elevation loss. However, long-term effects of hurricane sediment on elevation dynamics will depend not only on the amount of sediment deposited, but on sediment texture and resistance to compaction as well as on changes in organic matter accumulation in the years following the hurricane.

[Environmental behavior and ecological effect of polydimethylsiloxane: a review].

PubMed

Yang, Shang-Yuan; Li, Xin; Yang, Jia; Shen, Chao-Feng; Yu, Hua-Dong; Lu, Kang

2012-08-01

Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used.

Effect of microrelief on water erosion and their changes during rainfall

USDA-ARS?s Scientific Manuscript database

Soil surface roughness contains two elementary forms, i.e., depressions and mounds, which affect water flow on the surface differently. While depressions serve as temporary water storage, mounds diverge water away from their local summits. Although roughness effects on runoff and sediment production...

Development and application of multi-proxy indices of land use change for riparian soils in southern New England, USA.

PubMed

Ricker, M C; Donohue, S W; Stolt, M H; Zavada, M S

2012-03-01

Understanding the effects of land use on riparian systems is dependent upon the development of methodologies to recognize changes in sedimentation related to shifts in land use. Land use trends in southern New England consist of shifts from forested precolonial conditions, to colonial and agrarian land uses, and toward modern industrial-urban landscapes. The goals of this study were to develop a set of stratigraphic indices that reflect these land use periods and to illustrate their applications. Twenty-four riparian sites from first- and second-order watersheds were chosen for study. Soil morphological features, such as buried surface horizons (layers), were useful to identify periods of watershed instability. The presence of human artifacts and increases in heavy metal concentration above background levels, were also effective indicators of industrial-urban land use periods. Increases and peak abundance of non-arboreal weed pollen (Ambrosia) were identified as stratigraphic markers indicative of agricultural land uses. Twelve 14C dates from riparian soils indicated that the rise in non-arboreal pollen corresponds to the start of regional deforestation (AD 1749 +/- 56 cal yr; mean +/- 2 SD) and peak non-arboreal pollen concentration corresponds to maximum agricultural land use (AD 1820 +/- 51 cal yr). These indices were applied to elucidate the impact of land use on riparian sedimentation and soil carbon (C) dynamics. This analysis indicated that the majority of sediment and soil organic carbon (SOC) stored in regional riparian soils is of postcolonial origins. Mean net sedimentation rates increased -100-fold during postcolonial time periods, and net SOC sequestration rates showed an approximate 200-fold increase since precolonial times. These results suggest that headwater riparian zones have acted as an effective sink for alluvial sediment and SOC associated with postcolonial land use.

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.

Hydrogeochemical zonation in intertidal salt marsh sediments: evidence of positive plant-soil feedback?

NASA Astrophysics Data System (ADS)

Moffett, K. B.; Dittmar, J.; Seyfferth, A.; Fendorf, S.; Gorelick, S.

2012-12-01

Surface and subsurface environments are linked by the biogeochemical activity in near-surface sediment and by the hydrological fluxes that mobilize its reagents and products. A particularly dynamic and interesting setting to study near-surface hydrogeochemistry is the intertidal zone. Here, the very strong tidal hydraulic forcing is often thought to dominate water and solute transport. However, we demonstrated the importance of two additional subsurface drivers: groundwater flow and plant root water uptake. A high-resolution, coupled surface water-groundwater model of an intertidal salt marsh in San Francisco Bay, CA showed that these three drivers vary over different spatial scales: tidal flooding varies over 10's of meters; groundwater flow varies over meters, particularly within channel banks; and plant root water uptake varies in 3D at the sub-meter scale. Expanding on this third driver, we investigated whether the spatial variations in soil-water-plant hydraulic interactions that occur due to vegetation zonation also cause distinct geochemical zonation in salt marsh sediment pore waters. The existence of such geochemical zonation was verified and mapped by detailed field observations of the chemical composition of sediments, pore waters, surface waters, and vegetation. The field data and the coupled hydrologic model were then further analyzed to evaluate potential causal mechanisms for the geochemical zonation, including testing the hypothesis that the vegetation affects pore water geochemistry via a positive feedback beneficial to itself. If further supported by future studies, this geochemical feedback may complement known physical ecosystem engineering mechanisms to help stabilize and organize intertidal wetlands.

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.

Environmental and Anthropogenic Factors Influencing Mercury Dynamics During the Past Century in Floodplain Lakes of the Tapajós River, Brazilian Amazon.

PubMed

Oestreicher, Jordan Sky; Lucotte, Marc; Moingt, Matthieu; Bélanger, Émilie; Rozon, Christine; Davidson, Robert; Mertens, Frédéric; Romaña, Christina A

2017-01-01

In the Tapajós River region of the Brazilian Amazon, mercury (Hg) is a prevalent contaminant in the aquatic ecosystem. Few studies have used comprehensive chronological analyses to examine the combined effects of environmental and anthropogenic factors on Hg accumulation in sediments. Total mercury (THg) content was measured in sediments from eight floodplain lakes and Pb 210 isotope analysis was used to develop a timeline of THg accumulation. Secondary data representing environmental and anthropogenic factors were analyzed using geo-spatial analyses. These include land-cover change, hydrometeorological time-series data, lake morphology, and watershed biophysical characteristics. The results indicate that THg accumulation and sedimentation rates have increased significantly at the surface of most sediment cores, sometimes doubling since the 1970s. Human-driven land-cover changes in the watershed correspond closely to these shifts. Tropical deforestation enhances erosion, thereby mobilizing the heavy metal that naturally occurs in soils. Environmental factors also contribute to increased THg content in lacustrine sediments. Climate shifts since the 1980s are further compounding erosion and THg accumulation in surface sediments. Furthermore, variations in topography, soil types, and the level of hydrological connectivity between lakes and the river explain observed variations in THg fluxes and sedimentation. Although connectivity naturally varies among sampled lakes, deforestation of sensitive floodplain vegetation has changed lake-river hydrology in several sites. In conclusion, the results point to a combination of anthropogenic and environmental factors as determinants of increased THg accumulation in tropical floodplain sediments in the Tapajós region.

Modeling suspended sediment transport and assessing the impacts of climate change in a karstic Mediterranean watershed.

PubMed

Nerantzaki, S D; Giannakis, G V; Efstathiou, D; Nikolaidis, N P; Sibetheros, I Α; Karatzas, G P; Zacharias, I

2015-12-15

Mediterranean semi-arid watersheds are characterized by a climate type with long periods of drought and infrequent but high-intensity rainfalls. These factors lead to the formation of temporary flow tributaries which present flashy hydrographs with response times ranging from minutes to hours and high erosion rates with significant sediment transport. Modeling of suspended sediment concentration in such watersheds is of utmost importance due to flash flood phenomena, during which, large quantities of sediments and pollutants are carried downstream. The aim of this study is to develop a modeling framework for suspended sediment transport in a karstic watershed and assess the impact of climate change on flow, soil erosion and sediment transport in a hydrologically complex and intensively managed Mediterranean watershed. The Soil and Water Assessment Tool (SWAT) model was coupled with a karstic flow and suspended sediment model in order to simulate the hydrology and sediment yield of the karstic springs and the whole watershed. Both daily flow data (2005-2014) and monthly sediment concentration data (2011-2014) were used for model calibration. The results showed good agreement between observed and modeled values for both flow and sediment concentration. Flash flood events account for 63-70% of the annual sediment export depending on a wet or dry year. Simulation results for a set of IPCC "A1B" climate change scenarios suggested that major decreases in surface flow (69.6%) and in the flow of the springs (76.5%) take place between the 2010-2049 and 2050-2090 time periods. An assessment of the future ecological flows revealed that the frequency of minimum flow events increases over the years. The trend of surface sediment export during these periods is also decreasing (54.5%) but the difference is not statistically significant due to the variability of the sediment. On the other hand, sediment originating from the springs is not affected significantly by climate change. Copyright © 2015 Elsevier B.V. All rights reserved.

An Innovative Method for Estimating Soil Retention at a ...

EPA Pesticide Factsheets

Planning for a sustainable future should include an accounting of services currently provided by ecosystems such as erosion control. Retention of soil improves fertility, increases water retention, and decreases sedimentation in streams and rivers. Landscapes patterns that facilitate these services could help reduce costs for flood control, dredging of reservoirs and waterways, while maintaining habitat for fish and other species important to recreational and tourism industries. Landscape scale geospatial data available for the continental United States was leveraged to estimate sediment erosion (RUSLE-based, Renard, et al. 1997) employing recent geospatial techniques of sediment delivery ratio (SDR) estimation (Cavalli, et al. 2013). The approach was designed to derive a quantitative approximation of the ecological services provided by vegetative cover, management practices, and other surface features with respect to protecting soils from the erosion processes of detachment, transport, and deposition. Quantities of soil retained on the landscape and potential erosion for multiple land cover scenarios relative to current (NLCD 2011) conditions were calculated for each calendar month, and summed to yield annual estimations at a 30-meter grid cell. Continental-scale data used included MODIS NDVI data (2000-2014) to estimate monthly USLE C-factors, gridded soil survey geographic (gSSURGO) soils data (annual USLE K factor), PRISM rainfall data (monthly USLE

Holocene loess deposition and soil formation as competing processes, Matanuska Valley, southern Alaska

USGS Publications Warehouse

Muhs, D.R.; McGeehin, J.P.; Beann, J.; Fisher, E.

2004-01-01

Although loess-paleosol sequences are among the most important records of Quaternary climate change and past dust deposition cycles, few modern examples of such sedimentation systems have been studied. Stratigraphic studies and 22 new accelerator mass spectrometry radiocarbon ages from the Matanuska Valley in southern Alaska show that loess deposition there began sometime after ???6500 14C yr B.P. and has continued to the present. The silts are produced through grinding by the Matanuska and Knik glaciers, deposited as outwash, entrained by strong winds, and redeposited as loess. Over a downwind distance of ???40 km, loess thickness, sand content, and sand-plus-coarse-silt content decrease, whereas fine-silt content increases. Loess deposition was episodic, as shown by the presence of paleosols, at distances >10 km from the outwash plain loess source. Stratigraphic complexity is at a maximum (i.e., the greatest number of loesses and paleosols) at intermediate (10-25 km) distances from the loess source. Surface soils increase in degree of development with distance downwind from the source, where sedimentation rates are lower. Proximal soils are Entisols or Inceptisols, whereas distal soils are Spodosols. Ratios of mobile CaO, K2O, and Fe2O3 to immobile TiO2 show decreases in surface horizons with distance from the source. Thus, as in China, where loess deposition also takes place today, eolian sedimentation and soil formation are competing processes. Study of loess and paleosols in southern Alaska shows that particle size can vary over short distances, loess deposition can be episodic over limited time intervals, and soils developed in stabilized loess can show considerable variability under the same vegetation. ?? 2004 University of Washington. All rights reserved.

Area G perimeter surface-soil and single-stage water sampling: Environmental surveillance for fiscal year 95. Progress report

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

Childs, M.; Conrad, R.

1997-09-01

ESH-19 personnel collected soil and single-stage water samples around the perimeter of Area G at Los Alamos National Laboratory (LANL) during FY 95 to characterize possible radionuclide movement out of Area G through surface water and entrained sediment runoff. Soil samples were analyzed for tritium, total uranium, isotopic plutonium, americium-241, and cesium-137. The single-stage water samples were analyzed for tritium and plutonium isotopes. All radiochemical data was compared with analogous samples collected during FY 93 and 94 and reported in LA-12986 and LA-13165-PR. Six surface soils were also submitted for metal analyses. These data were included with similar data generatedmore » for soil samples collected during FY 94 and compared with metals in background samples collected at the Area G expansion area.« less

Soil carbon storages and erosional exports along a forested denudation gradient in the Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Yoo, K.; Wang, X.; Mudd, S. M.; Weinman, B.; Gutknecht, J.; Gabet, E. J.

2017-12-01

Eroding uplands not only provide physically mixed soil zones where OC and minerals actively interact but also are the significant sources of suspended sediments and organic carbon (OC) to rivers. Here our goal is to quantify the extents that erosion affects soils' capacities to store OC in different degrees of mineral-association and to facilitate the exports of minerals that might capture OC on their reactive surfaces. We examined a tributary basin to the Middle Folk Feather River in California, where knickpoint migration has created a series of hillslopes with erosion rates varying from 35 to 250 mm kyr-1. Other than erosion rates, the studied hillslopes within the tributary basin shared similar environmental factors. Soil samples were collected from select hillslopes that differ in their relative positions to knikpoints and were subject to size and density fractionation. Despite the substantial difference in erosion rates, concentrations of particulate OC (POC) and mineral-associated OC (MOC) and soil thickness varied little. Instead, considerable increase in coarse rock contents positively associated with erosion rate was responsible for the reduction of soil OC inventories by 37% with increasing erosion rate. In contrast to consistent MOC concentrations across the erosion gradient, clay contents in soils are negatively correlated with erosion rates. This seemingly contradictory result, however, is consistent with BET mineral specific surface area that remains insensitive to erosion rates. OC coverage on mineral surface was found to be less than < 50%, indicating that eroded minerals would have a significant, and currently unknown, capacity to adsorb additional OC during their transport to sediment sinks. This study thus reveals that mineral weathering acts as an important filter through which erosion affects the soil carbon cycle.

Phosphorus runoff from waste water treatment biosolids and poultry litter applied to agricultural soils.

PubMed

White, John W; Coale, Frank J; Sims, J Thomas; Shober, Amy L

2010-01-01

Differences in the properties of organic phosphorus (P) sources, particularly those that undergo treatment to reduce soluble P, can affect soil P solubility and P transport in surface runoff. This 2-yr field study investigated soil P solubility and runoff P losses from two agricultural soils in the Mid-Atlantic region after land application of biosolids derived from different waste water treatment processes and poultry litter. Phosphorus speciation in the biosolids and poultry litter differed due to treatment processes and significantly altered soil P solubility and dissolved reactive P (DRP) and bioavailable P (FeO-P) concentrations in surface runoff. Runoff total P (TP) concentrations were closely related to sediment transport. Initial runoff DRP and FeO-P concentrations varied among the different biosolids and poultry litter applied. Over time, as sediment transport declined and DRP concentrations became an increasingly important component of runoff FeO-P and TP, total runoff P was more strongly influenced by the type of biosolids applied. Throughout the study, application of lime-stabilized biosolids and poultry litter increased concentrations of soil-soluble P, readily desorbable P, and soil P saturation, resulting in increased DRP and FeO-P concentrations in runoff. Land application of biosolids generated from waste water treatment processes that used amendments to reduce P solubility (e.g., FeCl(3)) did not increase soil P saturation and reduced the potential for DRP and FeO-P transport in surface runoff. These results illustrate the importance of waste water treatment plant process and determination of specific P source coefficients to account for differential P availability among organic P sources.

Competitive adsorption of heavy metals in soil underlying an infiltration facility installed in an urban area.

PubMed

Hossain, M A; Furumai, H; Nakajima, F

2009-01-01

Accumulation of heavy metals at elevated concentration and potential of considerable amount of the accumulated heavy metals to reach the soil system was observed from earlier studies in soakaways sediments within an infiltration facility in Tokyo, Japan. In order to understand the competitive adsorption behaviour of heavy metals Zn, Ni and Cu in soil, competitive batch adsorption experiments were carried out using single metal and binary metal combinations on soil samples representative of underlying soil and surface soil at the site. Speciation analysis of the adsorbed metals was carried out through BCR sequential extraction method. Among the metals, Cu was not affected by competition while Zn and Ni were affected by competition of coexisting metals. The parameters of fitted 'Freundlich' and 'Langmuir' isotherms indicated more intense competition in underlying soil compared to surface soil for adsorption of Zn and Ni. The speciation of adsorbed metals revealed less selectivity of Zn and Ni to soil organic matter, while dominance of organic bound fraction was observed for Cu, especially in organic rich surface soil. Compared to underlying soil, the surface soil is expected to provide greater adsorption to heavy metals as well as provide greater stability to adsorbed metals, especially for Cu.

Erodibility of calcareous soils as influenced by land use and intrinsic soil properties in a semiarid region of central Iran.

PubMed

Ayoubi, Shamsollah; Mokhtari, Javad; Mosaddeghi, Mohammad Reza; Zeraatpisheh, Mojtaba

2018-03-06

The most important properties affecting the soil loss and runoff were investigated, and the effects of land use on the soil properties, together with the erodibility indices in a semiarid zone, central Iran, were evaluated. The locations of 100 positions were acquired by cLHS and 0-5-cm surface soil layer samples were used for laboratory analyses from the Borujen Region, Chaharmahal-Va-Bakhtiari Province, central Iran. To measure in situ runoff and soil erodibility of three different land uses comprising dryland, irrigated farming, and rangeland, a portable rainfall simulator was used. The results showed that the high variations (coefficient of variation, CV) were obtained for electrical conductivity (EC), mean weight diameter (MWD), soil organic carbon (SOC), and soil erodibility indices including runoff volume, soil loss, and sediment concentration (CV ~ 43.6-77.4%). Soil erodibility indices showed positive and significant correlations with bulk density and negative correlations with SOC, MWD, clay content, and soil shear strength in the area under investigation. The values of runoff in the dryland, irrigated farming, and rangeland were found 1.5, 28.9, and 58.7 cm 3 ; soil loss in the dryland, irrigated farming, and rangeland were observed 0.25, 2.96, and 76.8 g; and the amount of sediment concentration in the dryland, irrigated farming, and rangeland were found 0.01, 0.11, and 0.15 g cm -3 . It is suggested that further investigations should be carried out on soil erodibility and the potential of sediment yield in various land uses with varying topography and soil properties in semiarid regions of Iran facing the high risk of soil loss.

Installation Restoration Program. Stage 1. King Salmon Airport , King Salmon, Alaska

DTIC Science & Technology

1989-08-29

DESCRIPTION SOILS, SEDIMENTS , SLU_ SOLIDS TREATMENT ] CONSTITUENTS OR CON., SOLIDO /F/CATION, FIXATION" - STABILIZATION AND FIX/ STABILIZATION FORM...are consistently present in site media _il, sediment , surface, and ground-I waters), and are potentially toxic to humans and the eni--ent. Suggested...Seep IV-76 4.1.5.2.3 North Barrel Bluff IV-76 4.1.5.2.4 South Barrel Bluff IV-94 4.1.6 Sediment Investigation IV-94 4.1.6.1 Eskimo Creek Seep IV-94

In-filled reservoirs serving as sediment archives to analyse soil organic carbon erosion - Taking a closer look at the Karoo rangelands

NASA Astrophysics Data System (ADS)

Krenz, Juliane; Greenwood, Philip; Kuhn, Brigitte; Heckrath, Goswin; Foster, Ian; Boardman, John; Meadows, Michael; Kuhn, Nikolaus

2016-04-01

The semi-arid rangelands of the Great Karoo region in South Africa, which are nowadays characterized by badlands on the foot slopes of upland areas and complex gully systems in valley bottoms, have experienced a number of environmental changes. With the settlement of European farmers in the late 18th century agricultural activities increased, leading to overgrazing which probably acted as a trigger to land degradation. As a consequence of higher water demands and shifting rainfall patterns, many dams and small reservoirs have been constructed to provide drinking water for cattle or to facilitate irrigation during dry periods. Most of these dams are now filled with sediment and many have become breached, revealing sediment archives that can be used to analyse land use changes as well as carbon erosion and deposition during the last ca. 100 years. In this ongoing project, a combination of analytical methods that include drone imagery, landscape mapping, erosion modelling and sediment analysis have been employed to trace back the sediment origin and redistribution within the catchment, setting a special focus on the carbon history. Sediment deposits from a silted-up reservoir were analysed for varying physicochemical parameters, in order to analyse erosional and depositional patterns. A sharp decrease in total carbon content with decreasing depth suggests that land degradation during and after the post-European settlement most likely triggered erosion of the relatively fertile surface soils which presumably in-filled the reservoirs. It is assumed that the carbon-rich bottom layers of the dam deposits originate from these eroded surface soils. A combination of erosion modelling and sediment analysis will be used to determine the source areas of the depositional material and might clarify the question if land degradation in the Karoo has resulted in its return from being a net sink of carbon into a net source of carbon.

Effects of cattle manure on erosion rates and runoff water pollution by faecal coliforms.

PubMed

Ramos, M C; Quinton, J N; Tyrrel, S F

2006-01-01

The large quantities of slurry and manure that are produced annually in many areas in which cattle are raised could be an important source of organic matter and nutrients for agriculture. However, the benefits of waste recycling may be partially offset by the risk of water pollution associated with runoff from the fields to which slurry or manure has been applied. In this paper, the effects of cattle manure application on soil erosion rates and runoff and on surface water pollution by faecal coliforms are analysed. Rainfall simulations at a rate of 70 mm h(-1) were conducted in a sandy loam soil packed into soil flumes (2.5m long x 1m wide) at a bulk density of 1400 kg m(-3), with and without cattle slurry manure applied on the surface. For each simulation, sediment and runoff rates were analysed and in those simulations with applied slurry, presumptive faecal coliform (PFC) concentrations in the runoff were evaluated. The application of slurry on the soil surface appeared to have a protective effect on the soils, reducing soil detachment by up to 70% but increasing runoff volume by up to 30%. This practice implies an important source of pollution for surface waters especially if rainfall takes place within a short period after application. The concentrations of micro-organisms (presumptive faecal coliforms (PFCs)) found in water runoff ranged from 1.9 x 10(4) to 1.1 x 10(6) PFC 100mL(-1), depending on the initial concentration in the slurry, and they were particularly high during the first phases of the rainfall event. The result indicates a strong relationship between the faecal coliforms transported by runoff and the organic matter in the sediment.

Post-fire soil nutrient redistribution in northern Chihuahuan Desert

NASA Astrophysics Data System (ADS)

Wang, G.; Li, J. J.; Ravi, S.; Sankey, J. B.; Duke, D.; Gonzales, H. B.; Van Pelt, S.

2016-12-01

The desert grassland in the southwestern US has undergone dramatic land degradation with woody shrub encroachment over the last 150 years. Wind erosion and periodic fires are major drivers of vegetation dynamics in these ecosystems. Due to climate change and anthropogenic disturbances, many drylands are undergoing changes in fire regimes, which can largely alter the nutrient loss rate as well as the soil resource heterogeneity. In this study, we used manipulative field experiments, laboratory and geostatistical analyses to investigate the distribution of fertile islands, nutrient loss rate and spatial variation. Replicated burned and control experimental plots were set up in a desert grassland in northern Chihuahuan Desert in March 2016. Windblown sediments were monitored by multiple MWAC sediment collectors on each plot. Surface soil samples, with their locations accurately recorded (i.e., under shrub, under grass, and bare interspace) were collected twice per year in spring and again in summer after the experimental setup. Our preliminary results show that the spatial heterogeneity of soil C and N in the burned plots has changed notably compared to the control plots. Our results further demonstrated that areas with burned shrubs is most vulnerable to wind erosion, therefore the soil nutrient loss is most significant, almost five times of the nutrient loss rate of bare areas. Interspace bare areas is in the lowest micro-land and some of the surface has caliche, which makes the surface resistant to wind erosion. And areas with burned grass receive the lightest wind erosion and nutrient loss, around one third of the erosion on bare areas, because burned grasses still cover the surface and the dead bodies can eliminate wind erosion to a large extent. Hence, periodic fire in desert grassland favors the evenness distribution of soil nutrients and can retard the shrub encroachment process.

Groundwater control of mangrove surface elevation: shrink and swell varies with soil depth

USGS Publications Warehouse

Whelan, K.R.T.; Smith, T. J.; Cahoon, D.R.; Lynch, J.C.; Anderson, G.H.

2005-01-01

We measured monthly soil surface elevation change and determined its relationship to groundwater changes at a mangrove forest site along Shark River, Everglades National Park, Florida. We combined the use of an original design, surface elevation table with new rod-surface elevation tables to separately track changes in the mid zone (0?4 m), the shallow root zone (0?0.35 m), and the full sediment profile (0?6 m) in response to site hydrology (daily river stage and groundwater piezometric pressure). We calculated expansion and contraction for each of the four constituent soil zones (surface [accretion and erosion; above 0 m], shallow zone [0?0.35 m], middle zone [0.35?4 m], and bottom zone [4?6 m]) that comprise the entire soil column. Changes in groundwater pressure correlated strongly with changes in soil elevation for the entire profile (Adjusted R2 5 0.90); this relationship was not proportional to the depth of the soil profile sampled. The change in thickness of the bottom soil zone accounted for the majority (R2 5 0.63) of the entire soil profile expansion and contraction. The influence of hydrology on specific soil zones and absolute elevation change must be considered when evaluating the effect of disturbances, sea level rise, and water management decisions on coastal wetland systems.

Possible Exposure Pathways During Emergencies

EPA Pesticide Factsheets

There are three basic ways a person may be exposed to a hazardous substance: inhalation, ingestion, or direct contact. Points of contact include groundwater or surface water; soil, sediment, or dust; air; or food.

A simple distributed sediment delivery approach for rural catchments

NASA Astrophysics Data System (ADS)

Reid, Lucas; Scherer, Ulrike

2014-05-01

The transfer of sediments from source areas to surface waters is a complex process. In process based erosion models sediment input is thus quantified by representing all relevant sub processes such as detachment, transport and deposition of sediment particles along the flow path to the river. A successful application of these models requires, however, a large amount of spatially highly resolved data on physical catchment characteristics, which is only available for a few, well examined small catchments. For the lack of appropriate models, the empirical Universal Soil Loss Equation (USLE) is widely applied to quantify the sediment production in meso to large scale basins. As the USLE provides long-term mean soil loss rates, it is often combined with spatially lumped models to estimate the sediment delivery ratio (SDR). In these models, the SDR is related to data on morphological characteristics of the catchment such as average local relief, drainage density, proportion of depressions or soil texture. Some approaches include the relative distance between sediment source areas and the river channels. However, several studies showed that spatially lumped parameters describing the morphological characteristics are only of limited value to represent the factors of influence on sediment transport at the catchment scale. Sediment delivery is controlled by the location of the sediment source areas in the catchment and the morphology along the flow path to the surface water bodies. This complex interaction of spatially varied physiographic characteristics cannot be adequately represented by lumped morphological parameters. The objective of this study is to develop a simple but spatially distributed approach to quantify the sediment delivery ratio by considering the characteristics of the flow paths in a catchment. We selected a small catchment located in in an intensively cultivated loess region in Southwest Germany as study area for the development of the SDR approach. The flow pathways were extracted in a geographic information system. Then the sediment delivery ratio for each source area was determined using an empirical approach considering the slope, morphology and land use properties along the flow path. As a benchmark for the calibration of the model parameters we used results of a detailed process based erosion model available for the study area. Afterwards the approach was tested in larger catchments located in the same loess region.

Quality of water and chemistry of bottom sediment in the Rillito Creek basin, Tucson, Arizona, 1986-92

USGS Publications Warehouse

Tadayon, Saeid; Smith, C.F.

1994-01-01

Data were collected on physical properties and chemistry of 4 surface water, l4 ground water, and 4 bottom sediment sites in the Rillito Creek basin where artificial recharge of surface runoff is being considered. Concentrations of suspended sediment in streams generally increased with increases in streamflow and were higher during the summer. The surface water is a calcium and bicarbonate type, and the ground water is calcium sodium and bicarbonate type. Total trace ek=nents in surface water that exceeded the U.S. Environmental Protection Agency primary maximum contaminant levels for drinking-water standards were barium, beryllium, cadmium, chromium, lead, mercury and nickel. Most unfiltered samples for suspended gross alpha as uranium, and unadjusted gross alpha plus gross beta in surface water exceeded the U.S. Environmental Protection Agency and the State of Arizona drinking-water standards. Comparisons of trace- element concentrations in bottom sediment with those in soils of the western conterminous United States generally indicate similar concentrations for most of the trace elements, with the exceptions of scandium and tin. The maximum concentration of total nitrite plus nitrate as nitrogen in three ground- samples and total lead in one ground-water sample exceeded U.S. Environmental Protection Agency primary maximum contaminant levels for drinking- water standards, respectively. Seven organochlorine pesticides were detected in surface-water samples and nine in bottom-sediment samples. Three priority pollutants were detected in surface water, two were detected in ground water, and eleven were detected in bottom sediment. Low concentrations of oil and grease were detected in surface-water and bottom- sediment samples.

75 FR 27192 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-14

..., paper mill, saw mill, and oil refinery repairs; casting services for ``grey iron and brass,'' including... surface soil hot spots, sampling of surface water and sediment in the canals, stratigraphic profiling with..., monitor well installation, ground water sampling, and aquifer testing. Foundry operations resulted in...

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: Consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, Claudia; Kim, Jung-Hyun; Balinsha, Maria; Dorhout, Denise; Santos Fernandez, Cten; Baas, Marianne; Sinninghe Damsté, Jaap S.

2014-05-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature(MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers(MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study we are tracing the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed,indicating that marine in-situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in-situ production.

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, C.; Kim, J.-H.; Balsinha, M.; Dorhout, D.; Fernandes, C.; Baas, M.; Sinninghe Damsté, J. S.

2014-03-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature (MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers (MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study we are tracing the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed, indicating that marine in-situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in-situ production.

Transport of branched tetraether lipids from the Tagus River basin to the coastal ocean of the Portuguese margin: consequences for the interpretation of the MBT'/CBT paleothermometer

NASA Astrophysics Data System (ADS)

Zell, C.; Kim, J.-H.; Balsinha, M.; Dorhout, D.; Fernandes, C.; Baas, M.; Sinninghe Damsté, J. S.

2014-10-01

Branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are thought to be transported from soil to marine sediment by rivers, have been used to reconstruct the mean annual air temperature (MAAT) and soil pH of the drainage basin using the methylation index of branched tetraethers (MBT, recently refined as MBT') and cyclization index of branched tetraethers (CBT) from coastal marine sediment records. In this study, we trace the brGDGTs from source to sink in the Tagus River basin, the longest river system on the Iberian Peninsula, by determining their concentration and distribution in soils, river suspended particulate matter (SPM), riverbank sediments, marine SPM, and marine surface sediments. The concentrations of brGDGTs in river SPM were substantially higher and their distributions were different compared to those of the drainage basin soils. This indicates that brGDGTs are mainly produced in the river itself. In the marine environment, the brGDGT concentrations rapidly decreased with increasing distance from the Tagus estuary. At the same time, the brGDGT distributions in marine sediments also changed, indicating that marine in situ production also takes place. These results show that there are various problems that complicate the use of the MBT'/CBT for paleoreconstructions using coastal marine sediments in the vicinity of a river. However, if the majority of brGDGTs are produced in the river, it might be possible to reconstruct the environmental (temperature and pH) conditions of the river water using appropriate aquatic calibrations, provided that marine core locations are chosen in such a way that the brGDGTs in their sediments are predominantly derived from riverine in situ production.

Sediment budget for Murder Creek, Georgia, USA, from Pu239+240 - determined soil erosion rates

NASA Astrophysics Data System (ADS)

Stubblefield, A. P.; Matissoff, G.; Ketterer, M. E.; Whiting, P. J.

2005-12-01

Soil inventories of the radionuclides Cs137 and Pb210 have been used in a variety of environments as indicators for erosion and depositional processes. Development of sediment budgets for entire watersheds from radionuclide data has been somewhat constrained because limited sample numbers may not adequately characterize the wide range of geomorphic conditions and land uses found in heterogeneous environments. The measurement of Pu239+240 shows great potential for developing quantitative watershed sediment budgets. With inductively-coupled plasma mass spectrometry, hundreds of samples may be processed in dramatically shorter times than the gamma spectrometry method used for Cs137 or alpha spectrometry method used for Pb210. We collected surface soil samples from Murder Creek in the Piedmont region of Georgia, USA, to compare Pu239+240 inventories with Cs137 and Pb210 inventories for a range of land uses in a predominantly forested watershed. Excellent correlations were found for radionuclide inventories (r2 =0.88, n = 38) and high resolution (4 mm) depth profiles. The second objective was to generate a sediment budget using the full Pu239+240 dataset (n = 309). Average Pu239+240 inventories were 70.0 Bq/m2 for hardwood forest, 60.0 Bq/m2 for pine plantation, 65.1 Bq/m2 for pine forest, 66.7 Bq/m2 for row crop agriculture and 67.9 Bq/m2 for pasture. The sediment budget will be constructed by converting inventories into site-specific erosion rates. Erosion rates will be scaled up to the watershed scale using GIS coverages of land use, soil, slope, and slope position. Results will be compared with Murder Creek sediment budgets in the scientific literature generated from RUSLE erosion modeling, USGS monitoring networks and reservoir sedimentation.

Biodegradation of organic compounds in vadose zone and aquifer sediments.

PubMed Central

Konopka, A; Turco, R

1991-01-01

The microbial processes that occur in the subsurface under a typical Midwest agricultural soil were studied. A 26-m bore was installed in November of 1988 at a site of the Purdue University Agronomy Research Center. Aseptic collections of soil materials were made at 17 different depths. Physical analysis indicated that the site contained up to 14 different strata. The site materials were primarily glacial tills with a high carbonate content. The N, P, and organic C contents of sediments tended to decrease with depth. Ambient water content was generally less than the water content, which corresponds to a -0.3-bar equivalent. No pesticides were detected in the samples, and degradation of added 14C-labeled pesticides (atrazine and metolachlor) was not detected in slurry incubations of up to 128 days. The sorption of atrazine and metolachlor was correlated with the clay content of the sediments. Microbial biomass (determined by direct microscopic count, viable count, and phospholipid assay) in the tills was lower than in either the surface materials or the aquifer located at 25 m. The biodegradation of glucose and phenol occurred rapidly and without a lag in samples from the aquifer capillary fringe, saturated zone, and surface soils. In contrast, lag periods and smaller biodegradation rates were found in the till samples. Subsurface sediments are rich in microbial numbers and activity. The most active strata appear to be transmissive layers in the saturated zone. This implies that the availability of water may limit activity in the profile. PMID:1768098

A Stochastic Multi-Media Model of Microbial Transport in Watersheds

NASA Astrophysics Data System (ADS)

Yeghiazarian, L.; Safwat, A.; Whiteaker, T.; Teklitz, A.; Nietch, C.; Maidment, D. R.; Best, E. P.

2012-12-01

Fecal contamination is the leading cause of surface-water impairment in the US, and fecal pathogens are capable of triggering massive outbreaks of gastrointestinal disease. The difficulty in prediction of water contamination has its roots in the stochastic variability of fecal pathogens in the environment, and in the complexity of microbial dynamics and interactions on the soil surface and in water. To address these challenges, we have developed a stochastic model whereby the transport of microorganisms in watersheds is considered in two broad categories: microorganisms that are attached to mineral or organic substrates in suspended sediment; and unattached microorganisms suspended in overland flow. The interactions of microorganisms with soil particles on the soil surface and in the overland flow lead to transitions of microorganisms between solid and aqueous media. The strength of attachment of microorganisms to soil particles is determined by the chemical characteristics of soils which are highly correlated with the particle size. The particle size class distribution in the suspended sediment is predicted by the Water Erosion Prediction Project (WEPP). The model is integrated with ArcGIS, resulting in a general transport-modeling framework applicable to a variety of biological and chemical surface water contaminants. Simulations are carried out for a case study of contaminant transport in the East Fork Little Miami River Watershed in Ohio. Model results include the spatial probability distribution of microbes in the watershed and can be used for assessment of (1) mechanisms dominating microbial transport, and (2) time and location of highest likelihood of microbial occurrence, thus yielding information on best water sampling strategies.

[Sediment transport characteristics at different erosion stages for non-hardened roads of the Shenfu Coalfield, west China].

PubMed

Guo, Ming-ming; Wang, Wen-long; Li, Jian-ming; Huang, Peng-fei; Zhu, Bao-cai; Wang, Zhen; Luo, Ting

2015-02-01

Non-hardened roads formed in the production of the Shenfu Coalfield have a unique condition of underlying surface. The road surface is composed of a regolith layer with a certain thickness resulted from long-term rolling and thus, is characterized by weakened anti-scourabilty and anti-erodibility. In contrast, soil layer below the regolith has a higher bulk density and anti-erodibility. The processes of soil erosion on the non-hardened roads exhibit some differences under rainfall condition. The process of sediment transport and the relationship between sediment transport rate and erosion factors at different erosion stages were studied on non-hardened roads with slope degrees ranging from 3° to 12° (3°, 6°, 9°, 12°) by a field experiment under artificial rainfall. Results showed that the first peak of sediment transport on the regolith surface was observed at the sheet erosion stage. Sheet erosion occurred only at 3° slope degree, with an average variation coefficient of 0.07 for sediment transport rate. Rills in every testing began to develop at slope degrees of 6° to 12° about 15 min after runoff initiation. At the sheet erosion stage, the process of sediment transport fluctuated considerably at rainfall intensities of > 1.5 mm · min(-1), but the differences in its variation were little at the three slope degrees, with average variation coefficients of 0.20, 0.19 and 0.16, respectively. Rainfall intensity had a more significant impact on sediment transport rate than slope degree. The process of sediment transport at the rill erosion stage fluctuated, but the fluctuation was obviously smaller than that at the sheet erosion stage, with average variation coefficients of 0.05, 0.09 and 0.10 at the three slope degrees. Many wide and shallow rills evolved at the rill erosion stage. The sediment transport rate could be well predicted by a power function of rainfall intensity and slope degree at the sheet and rill erosion stages. The stable sediment transport rate for all the tests was linearly related to runoff rate and sediment concentration.

Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities

USGS Publications Warehouse

Ayuso, Robert A.; Foley, Nora K.

2016-01-01

Isotopic discrimination can be an effective tool in establishing a direct link between sources of Pb contamination and the presence of anomalously high concentrations of Pb in waters, soils, and organisms. Residential wells supplying water containing up to 1600 ppb Pb to houses built on the former Mohr orchards commercial site, near Allentown, PA, were evaluated to discern anthropogenic from geogenic sources. Pb (n = 144) and Sr (n = 40) isotopic data and REE (n = 29) data were determined for waters from residential wells, test wells (drilled for this study), and surface waters from pond and creeks. Local soils, sediments, bedrock, Zn-Pb mineralization and coal were also analyzed (n = 94), together with locally used Pb-As pesticide (n = 5). Waters from residential and test wells show overlapping values of 206Pb/207Pb, 208Pb/207Pb and 87Sr/86Sr. Larger negative Ce anomalies (Ce/Ce*) distinguish residential wells from test wells. Results show that residential and test well waters, sediments from residential water filters in water tanks, and surface waters display broad linear trends in Pb isotope plots. Pb isotope data for soils, bedrock, and pesticides have contrasting ranges and overlapping trends. Contributions of Pb from soils to residential well waters are limited and implicated primarily in wells having shallow water-bearing zones and carrying high sediment contents. Pb isotope data for residential wells, test wells, and surface waters show substantial overlap with Pb data reflecting anthropogenic actions (e.g., burning fossil fuels, industrial and urban processing activities). Limited contributions of Pb from bedrock, soils, and pesticides are evident. High Pb concentrations in the residential waters are likely related to sediment build up in residential water tanks. Redox reactions, triggered by influx of groundwater via wells into the residential water systems and leading to subtle changes in pH, are implicated in precipitation of Fe oxyhydroxides, oxidative scavenging of Ce(IV), and desorption and release of Pb into the residential water systems. The Pb isotope features in the residences and the region are best interpreted as reflecting a legacy of industrial Pb present in underlying aquifers that currently supply the drinking water wells.

Soil nitrogen dynamics in a river floodplain mosaic.

PubMed

Shrestha, J; Niklaus, P A; Frossard, E; Samaritani, E; Huber, B; Barnard, R L; Schleppi, P; Tockner, K; Luster, J

2012-01-01

In their natural state, river floodplains are heterogeneous and dynamic ecosystems that may retain and remove large quantities of nitrogen from surface waters. We compared the soil nitrogen dynamics in different types of habitat patches in a restored and a channelized section of a Thur River floodplain (northeast Switzerland). Our objective was to relate the spatiotemporal variability of selected nitrogen pools (ammonium, nitrate, microbial nitrogen), nitrogen transformations (mineralization, nitrification, denitrification), and gaseous nitrogen emission (NO) to soil properties and hydrological processes. Our study showed that soil water content and carbon availability, which depend on sedimentation and inundation dynamics, were the key factors controlling nitrogen pools and processes. High nitrogen turnover rates were measured on gravel bars, characterized by both frequent inundation and high sediment deposition rates, as well as in low-lying alluvial forest patches with a fine-textured, nutrient-rich soil where anaerobic microsites probably facilitated coupled nitrification-denitrification. In contrast, soils of the embankment in the channelized section had comparatively small inorganic nitrogen pools and low transformation rates, particularly those related to nitrate production. Environmental heterogeneity, characteristic of the restored section, favors nitrogen removal by creating sites of high sedimentation and denitrification. Of concern, however, are the locally high NO efflux and the possibility that nitrate could leach from nitrification hotspots. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Distribution of branched GDGTs in surface sediments from the Colville River, Alaska: Implications for the MBT'/CBT paleothermometer in Arctic marine sediments

NASA Astrophysics Data System (ADS)

Hanna, Andrea J. M.; Shanahan, Timothy M.; Allison, Mead A.

2016-07-01

Significant climate fluctuations in the Arctic over the recent past, and additional predicted future temperature changes, highlight the need for high-resolution Arctic paleoclimate records. Arctic coastal environments supplied with terrigenous sediment from Arctic rivers have the potential to provide annual to subdecadal resolution records of climate variability over the last few millennia. A potential tool for paleotemperature reconstructions in these marine sediments is the revised methylation index of branched tetraethers (MBT')/cyclization ratio of branched tetraethers (CBT) proxy based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). In this study, we examine the source of brGDGTs in the Colville River, Alaska, and the adjacent Simpson Lagoon and reconstruct temperatures from Simpson Lagoon sediments to evaluate the applicability of this proxy in Arctic estuarine environments. The Colville catchment soils, fluvial sediments, and estuarine sediments contain statistically similar brGDGT distributions, indicating that the brGDGTs throughout the system are soil derived with little alteration from in situ brGDGT production in the river or coastal waters. Temperatures reconstructed from the MBT'/CBT indices for surface samples show good agreement with regional summer (June through September) temperatures, suggesting a seasonal bias in Arctic temperature reconstructions from the Colville system. In addition, we reconstruct paleotemperatures from an estuarine sediment core that spans the last 75 years, revealing an overall warming trend in the twentieth century that is consistent with trends observed in regional instrumental records. These results support the application of this brGDGT-based paleotemperature proxy for subdecadal-scale summer temperature reconstructions in Arctic estuaries containing organic material derived from sediment-laden, episodic rivers.

Rainfall simulation and Structure-from-Motion photogrammetry for the analysis of soil water erosion in Mediterranean vineyards.

PubMed

Prosdocimi, Massimo; Burguet, Maria; Di Prima, Simone; Sofia, Giulia; Terol, Enric; Rodrigo Comino, Jesús; Cerdà, Artemi; Tarolli, Paolo

2017-01-01

Soil water erosion is a serious problem, especially in agricultural lands. Among these, vineyards deserve attention, because they constitute for the Mediterranean areas a type of land use affected by high soil losses. A significant problem related to the study of soil water erosion in these areas consists in the lack of a standardized procedure of collecting data and reporting results, mainly due to a variability among the measurement methods applied. Given this issue and the seriousness of soil water erosion in Mediterranean vineyards, this works aims to quantify the soil losses caused by simulated rainstorms, and compare them with each other depending on two different methodologies: (i) rainfall simulation and (ii) surface elevation change-based, relying on high-resolution Digital Elevation Models (DEMs) derived from a photogrammetric technique (Structure-from-Motion or SfM). The experiments were carried out in a typical Mediterranean vineyard, located in eastern Spain, at very fine scales. SfM data were obtained from one reflex camera and a smartphone built-in camera. An index of sediment connectivity was also applied to evaluate the potential effect of connectivity within the plots. DEMs derived from the smartphone and the reflex camera were comparable with each other in terms of accuracy and capability of estimating soil loss. Furthermore, soil loss estimated with the surface elevation change-based method resulted to be of the same order of magnitude of that one obtained with rainfall simulation, as long as the sediment connectivity within the plot was considered. High-resolution topography derived from SfM revealed to be essential in the sediment connectivity analysis and, therefore, in the estimation of eroded materials, when comparing them to those derived from the rainfall simulation methodology. The fact that smartphones built-in cameras could produce as much satisfying results as those derived from reflex cameras is a high value added for using SfM. Copyright © 2016 Elsevier B.V. All rights reserved.

Rainfall simulations as a tool for quantification of soil erosion processes caused by the trampling of sheep and goats in semi-arid and arid landscapes

NASA Astrophysics Data System (ADS)

Ruthenberg, Jonas; Tumbrink, Jonas; Wilms, Tobias; Peter, Klaus Daniel; Wirtz, Stefan; Ries, Johannes B.

2015-04-01

As there is a massive increase of livestock husbandry in semi-arid and arid landscapes, the investigation of trampling-induced soil erosion has become indispensable for a better understanding of erosive processes such as loosening and translocation of sediment, as well as the genesis of rill erosion and gully systems. Our work will support other studies focusing on desertification and land-use changes in the investigated landscapes. Up to this date, research on livestock-induced soil erosion, even in relation to other erosion processes such as aeolian and fluvial/pluvial sediment translocation, is very scarcely found in literature. The presented study on trampling-induced soil erosion by sheep and goats in arid and semi-arid landscapes aims to create a general understanding, an estimation and quantification of the influencing factors of these erosive processes. Within this study, we present the first results of several field rainfall experiments on rock fragment translocation as well as loosening and transportation of coarse and fine sediment depending on the motion sequence and the individual weight, size, and hoof beat of the animals. Furthermore, we conducted additional experiments to investigate the trampling-induced erosion processes for various other sediments, especially those in the range of clay, silt, and sand. To do so, we used a specially designed test plot, equipped with sediment traps on each side. For a clear and reliable analysis of the measured parameters, univariate as well as multivariate statistical methods have been used. For all field methods, we developed relevant statements concerning flock size. The rock fragment translocation experiments done so fare have shown that a flock of 45 sheep or goats moved 87 % of 320 spread out rock fragments with a mean translocation distance of 0.123 m when trampling across a test plot of 3.2 m^2. Besides that we found out that the soil surface was worked up in a way that the loosened fine sediment proved to be easily detachable by secondary erosive processes such as rainfall. The conducted rainfall simulations confirmed this assumption. They have shown that sediment yields were significantly higher on trail areas than on intershrub or shrub areas. The preliminary work done up until now suggests that the grazing and trampling of sheep and goats can be regarded as an important factor for soil degradation in semi-arid and arid landscapes. However, the understanding of the erosive processes in detail remains to be defined, i.e. the exact movement of the sheep and goats, the energy they can impart with their hooves, and how that energy affects different sediments or surfaces they tread upon, as well as the general quantification of trampling-induced erosion rates and transport processes of clastic sediments.

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 1: nonuniform infiltration and soil water redistribution

NASA Astrophysics Data System (ADS)

Muñoz-Carpena, Rafael; Lauvernet, Claire; Carluer, Nadia

2018-01-01

Vegetation buffers like vegetative filter strips (VFSs) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in floodplains often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall-runoff event. Simple and robust components of hydrological models are needed to analyze the impacts of WT in the landscape. To simulate VFS infiltration under realistic rainfall conditions with WT, we propose a generic infiltration solution (Shallow Water table INfiltration algorithm: SWINGO) based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new integral formulae to calculate singular times (time of ponding, shift time, and time to soil profile saturation). The algorithm was tested successfully on five distinct soils, both against Richards's numerical solution and experimental data in terms of infiltration and soil moisture redistribution predictions, and applied to study the combined effects of varying WT depth, soil type, and rainfall intensity and duration. The results show the robustness of the algorithm and its ability to handle various soil hydraulic functions and initial nonponding conditions under unsteady rainfall. The effect of a WT on infiltration under ponded conditions was found to be effectively decoupled from surface infiltration and excess runoff processes for depths larger than 1.2 to 2 m, being shallower for fine soils and shorter events. For nonponded initial conditions, the influence of WT depth also varies with rainfall intensity. Also, we observed that soils with a marked air entry (bubbling pressure) exhibit a distinct behavior with WT near the surface. The good performance, robustness, and flexibility of SWINGO supports its broader use to study WT effects on surface runoff, infiltration, flooding, transport, ecological, and land use processes. SWINGO is coupled with an existing VFS model in the companion paper (Lauvernet and Muñoz-Carpena, 2018), where the potential effects of seasonal or permanent WTs on VFS sediment and pesticide trapping are studied.

The Quaternary Environmental Change in the Northeast of Quintana Roo, Mexico:The Paleopedological Proxies

NASA Astrophysics Data System (ADS)

Cabadas Báez, H. V.; Sedov, S.; Solleiro Rebolledo, E.

2010-03-01

The Yucatán Peninsula, located in the southeast part of Mexico, is characterized to be an extended and low altitude platform constituted by calcareous rocks. These rocks are mainly limestones formed since Cretaceous under a marine shelf environment. In the northeast coast, the youngest sediments are found, as products of Quaternary sea level changes. We studied various profiles in quarries, following north-south transect in the Yucatan coast, near Cancún. In such profiles a sequence consisting of different kind of calcareous sediments and a soil in the surface were analyzed. The base of the sequence is constituted by a petrocalcic horizon (calcrete) that was formed during the last interglacial, 125,000 yrs. ago. Under the calcrete, a transgressive sequence appears with calcareous sediments of lagoon and reef facies. The uppermost part consists of dune-like sediments with crossed stratification overlied by another petrocalcic horizon, maybe formed during the Pleistocene-Holocene transition. Soils of the Yucatan Peninsula are very thin, rich in organic matter, neutral and well structured, and their image do not correspond to that found in tropical soils (deep, strongly weathered, leached). They are directly associated with the dune sediment dissolution because are infilling the "space" generated by rock dissolution. Calcrete is always in the uppermost part, but is broken and crossed by soil. This sequence reveals some aspects of the environmental dynamic during Late Pleistocene-Holocene. First, a dryer environment is assumed due to the presence of the calcrete in the base. During the glacial period, a transgressive environment prevailed and marine calcareous sedimentation started. During Last Glacial Maximum a regression occurred, the climate was drier and the formation of dune sediments and another calcrete occurred. In the Holocene climate changed shifting toward more humid conditions that produced the modern soil cover, under tropical conditions.

Fallout Radionuclides as Tracers in Southern Alps Sediment Studies

NASA Astrophysics Data System (ADS)

Carey, A. E.; Karanovic, Z.; Dibb, J. E.

2005-12-01

The primary geologic processes shaping the landscape are physical and chemical weathering and the transport of solids by erosion. As part of our studies on the coupling between physical erosion and chemical weathering, we have determined depositional and erosional processes in New Zealand's tectonically active, rapidly uplifting Southern Alps, specifically focusing on the Hokitika River watershed. The South Island watersheds we are studying are subject to extreme orographic precipitation (as high as 7-12 m annually) and high landslide frequency, but have modest topography due to the rapid erosion. In concert with our studies of chemical weathering and physical erosion, we have used the atmospherically-delivered radionuclides of 7Be, 137Cs and 210Pbexcess to determine the relative magnitude of particle residence time in the high elevation Cropp and Whitcombe subwatersheds and the rates of sedimentation. One- and two-box modeling with 7Be and 210Pbexcess was used to determine soil and sediment residence times. Residence time of fine suspended particles is short and particles can travel the length of the river during a single storm, probably due to the short duration, high-intensity rainfalls which produce rapidly moving, steep flood waves. The readily detected peak of 137Cs activity in Cropp terrace and Hokitika gorge soils yielded sedimentation rates of 0.06-0.12 cm yr-1. At the Cropp terrace, inventory models of 210Pbexcess yield soil accumulation rates significantly less than those determined using the 137Cs activity peak. We attribute the differences to overestimation of 210Pbexcess in surface soils and to contrasting fallout fluxes, geochemical behavior and radionuclide contents of sedimenting materials. Total inventories of 210Pbexcess in soils greatly exceed the expected direct atmospheric deposition, suggesting that lateral transport of this nuclide occurs within the watershed. At the Hokitika gorge, all nuclides studied yielded similar sedimentation rates, confirming the potential of 210Pbexcess for determining sedimentation rates in New Zealand watersheds with very low 137Cs inventories.

Pollution and ecological risk assessment of heavy metals in the soil-plant system and the sediment-water column around a former Pb/Zn-mining area in NE Morocco.

PubMed

El Azhari, Abdellah; Rhoujjati, Ali; El Hachimi, Moulay Laârabi; Ambrosi, Jean-Paul

2017-10-01

This study discussed the environmental fate and ecological hazards of heavy metals in the soil-plant system and sediment-water column around the former Pb-Zn mining Zeïda district, in Northeastern Morocco. Spatial distribution, pollution indices, and cluster analysis were applied for assessing Pb, Zn, As, Cu and Cd pollution levels and risks. The geo-accumulation index (I geo ) was determined using two different geochemical backgrounds: i) the commonly used upper crust values, ii) local geochemical background calculated with exploratory data analysis. The soils in the vicinity of the tailings, as well as the sediments downstream of the latter, displayed much higher metal concentrations, I geo, and potential ecology risk coefficient values than other sites, classifying these sites as highly contaminated and severely hazardous. The concentrations of Pb in contaminated sediment samples also exceeded the PEC limits and are expected to cause harmful effects on sediment-dwelling organisms. Based on the comparison with the toxicity limits, the most contaminated plant samples were found around the tailings piles. The metal concentrations in both raw and filtrated water samples were overall below the drinking water standards in samples upstream and downstream of the mining center, indicating that heavy metals levels in the Moulouya River surface waters were not affected by the tailings spill. Cluster analysis suggest that: i) Pb and Zn in sediments were derived from the abandoned tailings and are mainly stored and transported as particle-bound to the bedload, ii) Pb, Zn, and Cu in the soil-plant system were related to the dispersion of tailings materials while As and Cd originated primarily from natural geological background in both the soil-plant and the water-sediment systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Environmental impact assessment of the 2011 Tohoku-oki tsunami on the Sendai Plain

NASA Astrophysics Data System (ADS)

Chagué-Goff, Catherine; Niedzielski, Przemyslaw; Wong, Henri K. Y.; Szczuciński, Witold; Sugawara, Daisuke; Goff, James

2012-12-01

Large areas of farmland in the Sendai Plain, Japan, were inundated by the 11 March 2011 Tohoku-oki tsunami and covered by a discontinuous 30-0.2 cm thick sediment layer consisting of sand and/or mud and generally thinning and fining inland. Two months after the tsunami, numerous rice paddy fields and depressions remained ponded with brackish or saline water. A series of field surveys in May, August and October 2011 were carried out north of Sendai airport, in order to assess the environmental impact of the tsunami. While evaporation had resulted in elevated conductivity in ponded water in May (up to 68.2 mS cm- 1), rainfall over the next five months led to dilution, although brackish water was still recorded in depressions and on paddy fields. Tsunami sediments, underlying soil and soil beyond the tsunami inundation limit were collected at 43 sites along and near a transect extending over 5 km inland, and analysed for grain size, organic content, water leachable ions, acid leachable metals and exchangeable metalloids. Water leachable anion and cation concentrations were elevated in sandy and muddy tsunami deposits and soils particularly in areas, where seawater had stagnated for a longer period of time after the tsunami, with up to 10.5% Cl, 6.6% Na, 2.8% SO4, 440 mg kg- 1 Br measured in surface sediments (< 0.5 cm depth). Vertical variations were also recorded, with higher concentrations often measured in the surface samples. A similar trend could be observed for some of the metalloids (As) and metals (Zn, Cu and Ni), although in general, maximum concentrations of metals and metalloids were not much higher than in soils not inundated by the tsunami and were within background levels for uncontaminated Japanese soils. The impact of saltwater inundation was documented in the chemistry of soils underlying tsunami sediments, which were affected by salt contamination down to ~ 15 cm depth, and soils not covered by tsunami deposits. The latter implies that the extent of tsunami inundation may successfully be determined using geochemical markers in absence of any sedimentological evidence. Water leachable ions mostly decreased over time, however, they remained high enough to impact on rice farming, which was completely halted in 2011. Although further work is required to assess the longer term impact of tsunami inundation, flushing of salt with freshwater, as well as the possible removal of sandy/muddy sediments and underlying soil are recommended to allow crop production to resume.

Field Sampling Plan/Quality Assurance Project Plan Volume I of III

EPA Pesticide Factsheets

This document contains procedures related to the collection and analysis of soil, sediment, groundwater, surface water, air and biota samples at GE’s Pittsfield, Massachusetts facility and at other areas.

Effects of land disposal of municipal sewage sludge on fate of nitrates in soil, streambed sediment, and water quality

USGS Publications Warehouse

Tindall, James A.; Lull, Kenneth J.; Gaggiani, Neville G.

1994-01-01

This study was undertaken to determine the effects of sewage-sludge disposal at the Lowry sewage-sludge-disposal area, near Denver, Colorado, on ground- and surface-water quality, to determine the fate of nitrates from sludge leachate, and to determine the source areas of leachate and the potential for additional leaching from the disposal area.Sewage-sludge disposal began in 1969. Two methods were used to apply the sludge: burial and plowing. Also, the sludge was applied both in liquid and cake forms. Data in this report represent the chemical composition of soil and streambed sediment from seven soil- and four streambed-sampling sites in 1986, chemical and bacterial composition of ground water from 28 wells from 1981 to 1987, and surface-water runoff from seven water-sampling sites from 1984 to 1987. Ground water samples were obtained from alluvial and bedrock aquifers. Samples of soil, streambed sediment, ground water and surface water were obtained for onsite measurement and chemical analysis. Measurements included determination of nitrogen compounds and major cations and anions, fecal-coliform and -streptococcus bacteria, specific conductance, and pH.Thirteen wells in the alluvial aquifer in Region 3 of the study area contain water that was probably affected by sewage-sludge leachate. The plots of concentration of nitrate with time show seasonal trends and trends caused by precipitation. In addition to yearly fluctuation, there were noticeable increases in ground-water concentrations of nitrate that coincided with increased precipitation. After 3 years of annual ground-water-quality monitoring and 4 years of a quarterly sampling program, it has been determined that leachate from the sewage-sludge-disposal area caused increased nitrite plus nitrate (as nitrogen) concentration in the alluvial ground water at the site. Soil analyses from the disposal area indicate that organic nitrogen was the dominant form of nitrogen in the soil.As a result of investigations at the research site, it has been determined that a potentially large source of contamination exists in the soils of the study area owing to increased concentrations of nitrogen, sodium, calcium, magnesium, sulfate, bicarbonate, and chloride because of sewage disposal. Continued monitoring of surface and ground water for nitrogen and the other ions previously mentioned is required to assess long-term effects of municipal sludge disposal on water quality.

Effects of land disposal of municipal sewage sludge on fate of nitrates in soil, streambed sediment, and water quality

NASA Astrophysics Data System (ADS)

Tindall, James A.; Lull, Kenneth J.; Gaggiani, Neville G.

1994-12-01

This study was undertaken to determine the effects of sewage-sludge disposal at the Lowry sewage-sludge-disposal area, near Denver, Colorado, on ground- and surface-water quality, to determine the fate of nitrates from sludge leachate, and to determine the source areas of leachate and the potential for additional leaching from the disposal area. Sewage-sludge disposal began in 1969. Two methods were used to apply the sludge: burial and plowing. Also, the sludge was applied both in liquid and cake forms. Data in this report represent the chemical composition of soil and streambed sediment from seven soil- and four streambed-sampling sites in 1986, chemical and bacterial composition of ground water from 28 wells from 1981 to 1987, and surface-water runoff from seven water-sampling sites from 1984 to 1987. Ground water samples were obtained from alluvial and bedrock aquifers. Samples of soil, streambed sediment, ground water and surface water were obtained for onsite measurement and chemical analysis. Measurements included determination of nitrogen compounds and major cations and anions, fecal-coliform and -streptococcus bacteria, specific conductance, and pH. Thirteen wells in the alluvial aquifer in Region 3 of the study area contain water that was probably affected by sewage-sludge leachate. The plots of concentration of nitrate with time show seasonal trends and trends caused by precipitation. In addition to yearly fluctuation, there were noticeable increases in ground-water concentrations of nitrate that coincided with increased precipitation. After 3 years of annual ground-water-quality monitoring and 4 years of a quarterly sampling program, it has been determined that leachate from the sewage-sludge-disposal area caused increased nitrite plus nitrate (as nitrogen) concentration in the alluvial ground water at the site. Soil analyses from the disposal area indicate that organic nitrogen was the dominant form of nitrogen in the soil. As a result of investigations at the research site, it has been determined that a potentially large source of contamination exists in the soils of the study area owing to increased concentrations of nitrogen, sodium, calcium, magnesium, sulfate, bicarbonate, and chloride because of sewage disposal. Continued monitoring of surface and ground water for nitrogen and the other ions previously mentioned is required to assess long-term effects of municipal sludge disposal on water quality.

Mobilization and attenuation of metals downstream from a base-metal mining site in the Matra Mountains, northeastern Hungary

USGS Publications Warehouse

Odor, L.; Wanty, R.B.; Horvath, I.; Fugedi, U.; ,

1999-01-01

Regional geochemical baseline values have been established for Hungary by the use of low-density stream-sediment surveys of flood-plain deposits of large drainage basins and of the fine fraction of stream sediments. The baseline values and anomaly thresholds thus produced helped to evaluate the importance of high toxic element concentrations found in soils in a valley downstream of a polymetallic vein-type base-metal mine. Erosion of the mine dumps and flotation dump, losses of metals during filtering, storage and transportation, human neglects, and operational breakdowns, have all contributed to the contamination of a small catchment basin in a procession of releases of solid waste. The sulfide-rich waste material weathers to a yellow color; this layer of 'yellow sand' blankets a narrow strip of the floodplain of Toka Creek in the valley near the town of Gyongyosoroszi. Contamination was spread out in the valley by floods. Metals present in the yellow sand include Pb, As, Cd, Cu, Zn, and Sb. Exposure of the local population to these metals may occur through inhalation of airborne particulates or by ingestion of these metals that are taken up by crops grown in the valley. To evaluate the areal extent and depth of the contamination, active stream sediment, flood-plain deposits, lake or reservoir sediments, soils, and surface water were sampled along the erosion pathways downstream of the mine and dumps. The flood-plain profile was sampled in detail to see the vertical distribution of elements and to relate the metal concentrations to the sedimentation and contamination histories of the flood plain. Downward migration of mobile Zn and Cd from the contaminated upper layers under supergene conditions is observed, while vertical migration of Pb, As, Hg and Sb appears to be insignificant. Soil profiles of 137Cs which originated from above-ground atomic bomb tests and the Chernobyl accident, provide good evidence that the upper 30-40 cm of the flood-plain sections, which includes the yellow sand contamination, were deposited in the last 30-40 years.The regional geochemical baseline values are established for Hungary using low-density stream-sediment surveys of flood-plain deposits of large drainage basins and of the fine fraction of stream sediments. The baseline values and anomaly thresholds allowed the evaluation of the importance of high toxic element concentrations in soils in a valley, downstream of a polymetallic vein-type base-metal mine. The metals present in the yellow sand include Pb, As, Cd, Cu, Zn and Sb. To evaluate the areal extent and depth of the contamination, active stream sediment, flood-plain deposits, lake or reservoir sediments, the soils and surface water were sampled along the erosion pathways downstream of the mine and dumps.

Physicochemical Characterization of Potential Mobile Organic Matter In Five Typical German Agricultural Soils

NASA Astrophysics Data System (ADS)

Séquaris, J.-M.; Lewandowski, H.; Vereecken, H.

Organic matter (OM) in soils plays an important role, i.e., in maintaining soil structure or as source of nutrients. OM is mainly adsorbed at the surface of clay minerals and oxides and remains mostly immobile. However, mobile OM in dissolved form (DOM) or associated with water dispersible colloids (WDC) in soil water may influence trans- port of pollutants. The goal of this study is to compare 5 typical German agricultural soils in terms of distribution and quality of OM in the top soil (0-15 cm). The present report focuses on the physicochemical characterization of potential mobile OM so- lutions obtained after physical fractionation of soil materials based on sedimentation after a prolonged shaking in water or electrolyte solutions. Three soil fractions dif- fering in particle size were separated in function of sedimentation time: a colloidal fraction: < 2 ţm; a microaggregate fraction: 2-20 ţm and a sediment fraction: > 20 ţm. The soil electrolyte phase containing the DOM fraction was obtained by a high-speed centrifugation of the colloidal phase. After a water or low electrolyte concentration (« 1 mM Ca2+) extraction, it can be shown that the mobile fraction of OM or OC (organic carbon) is distributed between the colloidal and the electrolyte phases in a concentration ratio range of 10-40 to 1. A less mobile OC fraction is associated with the microaggregate fraction while immobile OC remains adsorbed in the sediment fraction. An increasing OC and total-N content with diminishing particle-size of soil (colloidal and microaggregate fractions) has been confirmed. A higher OC input due to special soil management is sensitively detected in fractions with a greater particle size (sediment fraction). Increasing the Ca2+ concentration up to 10 mM during the water extraction diminishes the DOC concentration by an average factor of 3 while the OC associated with the dispersed colloids (OCWDC) vanished almost completely. Thus, a critical coagulation concentration of about 1-2 mM Ca2+ can be estimated which increases the stability of soil aggregates in water. Different titration, electrokinetic and spectroscopic methods were applied to characterize the colloidal and electrolyte phases. These techniques provide information on the physicochemical heterogeneity of mobile OM from various agricultural soils.

Soil fauna and leaf species, but not species diversity, affect initial soil erosion in a subtropical forest plantation

NASA Astrophysics Data System (ADS)

Seitz, Steffen; Goebes, Philipp; Assmann, Thorsten; Schuldt, Andreas; Scholten, Thomas

2017-04-01

In subtropical parts of China, high rainfall intensities cause continuous soil losses and thereby provoke severe harms to ecosystems. In woodlands, it is not the tree canopy, but mostly an intact forest floor that provides protection from soil erosion. Although the protective role of leaf litter covers against soil losses is known for a long time, little research has been conducted on the processes involved. For instance, the role of different leaf species and leaf species diversity has been widely disregarded. Furthermore, the impact of soil meso- and macrofauna within the litter layer on soil losses remains unclear. To investigate how leaf litter species and diversity as well as soil meso- and macrofauna affect sediment discharge in a subtropical forest ecosystem, a field experiment was carried out in Xingangshan, Jiangxi Province, PR China (BEF China). A full-factorial random design with 96 micro-scale runoff plots and seven domestic leaf species in three diversity levels and a bare ground feature were established. Erosion was initiated with a rainfall simulator. This study confirms that leaf litter cover generally protects forest soils from water erosion (-82 % sediment discharge on leaf covered plots compared to bare plots) and this protection is gradually removed as the litter layer decomposes. Different leaf species showed variable impacts on sediment discharge and thus erosion control. This effect can be related to different leaf habitus, leaf decomposition rates and food preferences of litter decomposing meso- and macrofauna. In our experiment, runoff plots with leaf litter from Machilus thunbergii in monoculture showed the highest sediment discharge (68.0 g m-2), whereas plots with Cyclobalanopsis glauca in monoculture showed the smallest rates (7.9 g m-2). At the same time, neither leaf species diversity, nor functional diversity showed any significant influence, only a negative trend could be observed. Nevertheless, the protective effect of the leaf litter layer was influenced by the presence (or absence) of soil meso- and macrofauna. Fauna presence increased soil erosion rates significantly by 58 %. It was assumed that this faunal effect arose from arthropods loosening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Thus, effects of this fauna group on sediment discharge have to be considered in soil erosion experiments.

Soil-like bodies on Mars

NASA Astrophysics Data System (ADS)

Targulian, V. O.; Mergelov, N. S.; Goryachkin, S. V.

2017-02-01

Soils sensu stricto are absent on Mars; most probably, they have never been formed there, because, up to now, we have no evidence of the presence of life, either relict or recent, on this planet. Numerous references to "Martian soils" in scientific literature concern loose substrates rather than Dokuchaev's soils. In this context, surface bodies on Mars can be described using the concept of planetary shells, or exons. Exons can be subdivided into sitons formed via in situ transformation of parent material, transons formed in the course of lateral transportation and deposition of substances, and transsitons formed by the combination of both in situ and lateral processes. Among Martian exons, transons predominate. They represent loose sediments of mainly eolian genesis related to extremely strong winds. Soil-like bodies (soloids) on Mars are represented by sitons and transsitons. These are abiotic formations having the profiles differentiated by the contents of iron oxides, soluble salts, and clay minerals and mainly formed in the presence of liquid water during the paleohumid eras of Mars evolution more than 2.5/3 billion years ago. True deep sitons (Martian weathering mantles) could only be formed under the impact of long-term weathering on stable surfaces during humid eras. Then, they were either buried by later deposited sediments, or eroded. Up to now, such objects have not been discovered on Mars.

Mineral-leaching chemical transport with runoff and sediment from severely eroded rare-earth tailings in southern China

NASA Astrophysics Data System (ADS)

Lu, Huizhong; Cao, Longxi; Liang, Yin; Yuan, Jiuqin; Zhu, Yayun; Wang, Yi; Gu, Yalan; Zhao, Qiguo

2017-08-01

Rare-earth mining has led to severe soil erosion in southern China. Furthermore, the presence of the mineral-leaching chemical ammonium sulfate in runoff and sediment poses a serious environmental threat to downstream water bodies. In this paper, the characteristics of mineral-leaching chemicals in surface soil samples collected in the field were studied. In addition, NH4+ and SO42- transport via soil erosion was monitored using runoff and sediment samples collected during natural rainfall processes. The results demonstrated that the NH4+ contents in the surface sediment deposits increased from the top of the heap (6.56 mg kg-1) to the gully (8.23 mg kg-1) and outside the tailing heap (13.03 mg kg-1). The contents of SO42- in the different locations of the tailing heaps ranged from 27.71 to 40.33 mg kg-1. During typical rainfall events, the absorbed NH4+ concentrations (2.05, 1.26 mg L-1) in runoff were significantly higher than the dissolved concentrations (0.93, 1.04 mg L-1), while the absorbed SO42- concentrations (2.87, 1.92 mg L-1) were significantly lower than the dissolved concentrations (6.55, 7.51 mg L-1). The dissolved NH4+ and SO42- concentrations in runoff displayed an exponentially decreasing tendency with increasing transport distance (Y = 1. 02 ṡ exp( - 0. 00312X); Y = 3. 34 ṡ exp( - 0. 0185X)). No clear trend with increasing distance was observed for the absorbed NH4+ and SO42- contents in transported sediment. The NH4+ and SO42- contents had positive correlations with the silt and clay ratio in transported sediment but negative correlations with the sand ratio. These results provide a better understanding of the transport processes and can be used to develop equations to predict the transport of mineral-leaching chemicals in rare-earth tailings, which can provide a scientific foundation for erosion control and soil management in rare-earth tailing regions in southern China.

Summary of Surface-Water Quality Data from the Illinois River Basin in Northeast Oklahoma, 1970-2007

USGS Publications Warehouse

Andrews, William J.; Becker, Mark F.; Smith, S. Jerrod; Tortorelli, Robert L.

2009-01-01

The quality of streams in the Illinois River Basin of northeastern Oklahoma is potentially threatened by increased quantities of wastes discharged from increasing human populations, grazing of about 160,000 cattle, and confined animal feeding operations raising about 20 million chickens. Increasing numbers of humans and livestock in the basin contribute nutrients and bacteria to surface water and groundwater, causing greater than the typical concentrations of those constituents for this region. Consequences of increasing contributions of these substances can include increased algal growth (eutrophication) in streams and lakes; impairment of habitat for native aquatic animals, including desirable game fish species; impairment of drinking-water quality by sediments, turbidity, taste-and-odor causing chemicals, toxic algal compounds, and bacteria; and reduction in the aesthetic quality of the streams. The U.S. Geological Survey, in cooperation with the Oklahoma Scenic Rivers Commission, prepared this report to summarize the surface-water-quality data collected by the U.S. Geological Survey at five long-term surface-water-quality monitoring sites. The data summarized include major ions, nutrients, sediment, and fecal-indicator bacteria from the Illinois River Basin in Oklahoma for 1970 through 2007. General water chemistry, concentrations of nitrogen and phosphorus compounds, chlorophyll-a (an indicator of algal biomass), fecal-indicator bacteria counts, and sediment concentrations were similar among the five long-term monitoring sites in the Illinois River Basin in northeast Oklahoma. Most water samples were phosphorus-limited, meaning that they contained a smaller proportion of phosphorus, relative to nitrogen, than typically occurs in algal tissues. Greater degrees of nitrogen limitation occurred at three of the five sites which were sampled back to the 1970s, probably due to use of detergents containing greater concentrations of phosphorus than in subsequent periods. Concentrations of nitrogen, phosphorus, and sediment, and counts of bacteria generally increased with streamflow at the five sites, probably due to runoff from the land surface and re-suspension of streambed sediments. Phosphorus concentrations typically exceeded the Oklahoma standard of 0.037 milligrams per liter for Scenic Rivers. Concentrations of chlorophyll-a in phytoplankton in water samples collected at the five sites were not well correlated with streamflow, nor to concentrations of the nutrients nitrogen and phosphorus, probably because much of the algae growing in these streams are periphyton attached to streambed cobbles and other debris, rather than phytoplankton in the water column. Sediment concentrations correlated with phosphorus concentrations in water samples collected at the sites, probably due to sorption of phosphorus to soil particles and streambed sediments and runoff of soils and animal wastes at the land surface and resuspension of streambed sediments and phosphorus during wet, high-flow periods. Fecal coliform bacteria counts at the five sites sometimes exceeded the Oklahoma Primary Body Contact Standard of 400 colonies per 100 milliliters when streamflows were greater than 1000 cubic feet per second. Ultimately, Lake Tenkiller, an important ecological and economic resource for the region, receives the compounds that runoff the land surface or seep to local streams from groundwater in the basin. Because of eutrophication from increased nutrient loading, Lake Tenkiller is listed for impairment by diminished dissolved oxygen concentrations, phosphorus, and chlorophyll-a by the State of Oklahoma in evaluation of surface-water quality required by section 303d of the Clean Water Act. Stored phosphorus in soils and streambed and lakebed sediments may continue to provide phosphorus to local streams and lakes for decades to come. Steps are being made to reduce local sources of phosphorus, including upgrades in capacity and effective

The early warning system of landslides and sediment runoffs using meteorological condition including rainfall-soil moisture index (Invited)

NASA Astrophysics Data System (ADS)

Kubota, T.; Silva, I. C.; Hasnawir, H.

2009-12-01

The research including observation of rain, soil moisture content and sediment discharge is conducted on a torrent in northern Kyushu whose geology consists of Paleozoic metamorphic rocks (mainly schist) and whose vegetation consists of mainly Japanese cypress and cedar. Soil depth is approximately 50cm in average and permeability k is 0.1~0.01 order. With data obtained by the observation for more than 4 years, standard rainfalls of warning and evacuation against the sudden sediment runoffs are analyzed. Then, the result was compared with the ones in Nuevo Leon Mexico (geology of schist, slate, k=0.01~0.001 order) and in southern Sulawesi Island Indonesia (volcanic geology, k=0.001~0.0001 order). Hitherto, various methods were proposed to analyze the warning critical standard for landslide disaster or large sediment discharge. In this study, we employed Hirano's element slope runoff theory, the Self Organized Criticality Assumption (SOC), and the Elementary Catastrophe Theory (ETC) to analyze the data, although the soil moisture fluctuation, meteorological condition such as upper air wind and dew point depression, the rainfall-soil moisture index provided by Japan Meteorological Agency was considered. The last one is a cutting edge technology based on the tank model calculation of soil moisture content combined with short term rainfall prediction which is a product of numerical simulation using radar image advection analysis compensated with surface rain data and with orographic rain effect. In Hirano's theory, we can describe the critical rain Rc and rain intensity Ric as following equation. Q/A/M/ cosθ = Ri ∫(r*cosθ)dt = Ri*R (1) ∴ Ric*Rc = C (2) Here, Q: sediment runoff or debris flow discharge, A: watershed area, M: function concerning with sediment deposit features on the upstream torrents or slopes (porosity, torrent bed slope gradient, sediment accumulation length and depth, cohesion), t: time, θ: torrent bed or hillside slope gradient, r: instant precipitation. C: constant, given as 8000 in Fukuoka (Kyushu, Japan), as 3750 in Sierra Madere Oriental (Nuevo Leon, Mexico), as 9000 in southern Sulawesi(Indonesia). Consequently, the forecast-warning system which has enough accuracy of 80% against sediment runoffs or debris flows for both wide range region with meteorological conditions and narrow region with the critical rain standard are established. However, in the region with lower soil permeability we may revise the standard rain by the compensation with the soil moisture content response such as increasing rate.

Hydrogeomorphology influences soil nitrogen and phosphorus mineralization in floodplain wetlands

USGS Publications Warehouse

Noe, Gregory B.; Hupp, Cliff R.; Rybicki, Nancy B.

2013-01-01

Conceptual models of river–floodplain systems and biogeochemical theory predict that floodplain soil nitrogen (N) and phosphorus (P) mineralization should increase with hydrologic connectivity to the river and thus increase with distance downstream (longitudinal dimension) and in lower geomorphic units within the floodplain (lateral dimension). We measured rates of in situ soil net ammonification, nitrification, N, and P mineralization using monthly incubations of modified resin cores for a year in the forested floodplain wetlands of Difficult Run, a fifth order urban Piedmont river in Virginia, USA. Mineralization rates were then related to potentially controlling ecosystem attributes associated with hydrologic connectivity, soil characteristics, and vegetative inputs. Ammonification and P mineralization were greatest in the wet backswamps, nitrification was greatest in the dry levees, and net N mineralization was greatest in the intermediately wet toe-slopes. Nitrification also was greater in the headwater sites than downstream sites, whereas ammonification was greater in downstream sites. Annual net N mineralization increased with spatial gradients of greater ammonium loading to the soil surface associated with flooding, soil organic and nutrient content, and herbaceous nutrient inputs. Annual net P mineralization was associated negatively with soil pH and coarser soil texture, and positively with ammonium and phosphate loading to the soil surface associated with flooding. Within an intensively sampled low elevation flowpath at one site, sediment deposition during individual incubations stimulated mineralization of N and P. However, the amount of N and P mineralized in soil was substantially less than the amount deposited with sedimentation. In summary, greater inputs of nutrients and water and storage of soil nutrients along gradients of river–floodplain hydrologic connectivity increased floodplain soil nutrient mineralization rates.

Nutrient transport through a Vegetative Filter Strip with subsurface drainage.

PubMed

Bhattarai, Rabin; Kalita, Prasanta Kumar; Patel, Mita Kanu

2009-04-01

The transport of nutrients and soil sediments in runoff has been recognized as a noteworthy environmental issue. Vegetative Filter Strips (VFS) have been used as one of the best management practices (BMPs) for retaining nutrients and sediments from surface runoff, thus preventing the pollutants from reaching receiving waters. However, the effectiveness of a VFS when combined with a subsurface drainage system has not been investigated previously. This study was undertaken to monitor the retention and transport of nutrients within a VFS that had a subsurface drainage system installed at a depth of 1.2 m below the soil surface. Nutrient concentrations of NO(3)-N (Nitrate Nitrogen), PO(-)(4) (Orthophosphorus), and TP (Total Phosphorus) were measured in surface water samples (entering and leaving the VFS), and subsurface outflow. Soil samples were collected and analyzed for plant available Phosphorus (Bray P1) and NO(3)-N concentrations. Results showed that PO(-)(4), NO(3)-N, and TP concentrations decreased in surface flow through the VFS. Many surface outflow water samples from the VFS showed concentration reductions of as much as 75% for PO(-)(4) and 70% for TP. For subsurface outflow water samples through the drainage system, concentrations of PO(-)(4) and TP decreased but NO(3)-N concentrations increased in comparison to concentrations in surface inflow samples. Soil samples that were collected from various depths in the VFS showed a minimal buildup of nutrients in the top soil profile but indicated a gradual buildup of nutrients at the depth of the subsurface drain. Results demonstrate that although a VFS can be very effective in reducing runoff and nutrients from surface flow, the presence of a subsurface drain underneath the VFS may not be environmentally beneficial. Such a combination may increase NO(3)-N transport from the VFS, thus invalidating the purpose of the BMP.

Missing evidence for the LGM-asynchronity in the Central Spanish Pyrenees in geomorphological, sedimentological and pedological archives

NASA Astrophysics Data System (ADS)

Hirsch, Florian; Raab, Thomas

2016-04-01

According to the state of knowledge, the glacial advances in the Eastern Pyrenees were synchronous with the global LGM during the Late Pleistocene (MIS 2), but the glacial advances in the Central Spanish Pyrenees at MIS 3 were asynchron with the global LGM. Whereas in the Eastern Pyrenees the glacial advances are dated in several well agreeing studies by surface exposure dating of boulders from lateral or terminal moraines, the asynchronity of the Central Spanish Pyrenees was postulated mainly by OSL dating on glacial and fluvial sediments and on radiocarbon dating of pollen from lacustrine deposits. The time difference of about 15 ka raises the question if this is a result of (local) climate factors or owed to failures caused by using several dating techniques on different archives. Anyway, if this time lag is correct, post-LGM formation of soils and sediments from the Late Pleistocene should be different between the Eastern Pyrenees and the Central Spanish Pyrenees. We therefore applied a combined approach of geomorphological, sedimentological and pedological investigations to reconstruct the Late Quaternary landscape development in the Aragon- and Gallego Valley of the Central Spanish Pyrenees. Our study reveals that in both valleys the Pre-Holocene geomorphodynamics on the lateglacial deposits show clear analogies with findings from Pleistocene periglacial landscapes in Central Europe. For MIS 4 and early MIS 3 periglacial processes are proven by loess deposition and formation of solifluction sediments. The glacial sediments, which were dated in earlier studies into mid MIS 3 and counted so far as prove for the asynchronous LGM of the Central Spanish Pyrenees, are covered by periglacial deposits of lateglacial age (14 ka to 11 ka). Surprisingly neither the glacial sediments have pedogenic features that indicate lateglacial soil development, nor do the periglacial deposits show indications for lateglacial soil erosion. Therefore we conclude that soil formation began after the sedimentation of the periglacial deposits, either implying a striking timeframe of more than 15 ka with a stable landscape without any pedogenesis, or the untenability of the MIS 3 age of the glacial sediments. Because we can clearly differentiate further phases of geomorphodynamics during the Holocene with truncated soil profiles and the correlate sediments of soil erosion next to undisturbed soils in periglacial sediments with a lateglacial age, we challenge the thesis of an asynchronous LGM in the Central Spanish Pyrenees and advocate a synchronous LGM in the Gallego- and Aragon valley analog to the Eastern Pyrenees.

Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) data

NASA Technical Reports Server (NTRS)

Price, Kevin P.

1993-01-01

Multispectral measurements collected by Landsat Thematic Mapper (TM) were correlated with field measurements, direct soil loss estimates, and Universal Soil Loss Equation (USLE) estimates to determine the sensitivity of TM data to varying degrees of soil erosion in pinyon-juniper woodland in central Utah. TM data were also evaluated as a predictor of the USLE Crop Management C factor for pinyon-juniper woodlands. TM spectral data were consistently better predictors of soil erosion factors than any combination of field factors. TM data were more sensitive to vegetation variations than the USLE C factor. USLE estimates showed low annual rates of erosion which varied little among the study sites. Direct measurements of rate of soil loss using the SEDIMENT (Soil Erosion DIrect measureMENT) technique, indicated high and varying rates of soil loss among the sites since tree establishment. Erosion estimates from the USLE and SEDIMENT methods suggest that erosion rates have been severe in the past, but because significant amounts of soil have already been eroded, and the surface is now armored by rock debris, present erosion rates are lower. Indicators of accelerated erosion were still present on all sites, however, suggesting that the USLE underestimated erosion within the study area.

Soft Soil Improvement for Sub-grade Layer Using Hexagonal Micropiles Layout

NASA Astrophysics Data System (ADS)

Ambak, K.; Abdullah, N. A. H.; Yusoff, M. F.; Abidin, M. H. Z.

2018-04-01

Soft soil problems are often associated with sediment and stability where it represents a major challenge in Geotechnical Engineering. Research on a soft soil was carried out to determine the level of sediment resulting from the applied load and thus compare the most ideal form of arrangement by the results obtained from bearing capacity. The study was conducted at Research Centre for Soft Soil (RECESS), UTHM by using kaolin. There are several tests conducted on kaolin before the arrangement of pile which is liquid limit test. Through these tests, the level of water content can be maintained which is 1.2 liquid limit where it is in the homogeneous condition. Density test also carried to know weight of kaolin and water that needed in the model. Meanwhile, large strain consolidation test carried on the soil by placing a load of 8 kPa. Then, the pile was arranged in the soil in the shape of a hexagon and square. Load was increased to 12 kPa and imposed on the surface of the pile with a different forms. After 24 hours, the reading of sediment was measured everyday and the process collecting data conducted for 3 week. Based on data obtained, time against sediment can be plotted. To determine the bearing capacity, direct shear test was conducted to get the value coefficient of cohesion, c as a parameter in the calculation of the soil bearing capacity. The results showed that the rate of settlement occurs is different where hexagonal form less the rate of settlement compared to square form which is 64.2% while the results of bearing capacity have the same value.

The Rusty Sink: Iron Promotes the Preservation of Organic Matter in Sediments

NASA Astrophysics Data System (ADS)

Lalonde, K. M.; Mucci, A.; Moritz, A.; Ouellet, A.; Gelinas, Y.

2011-12-01

The biogeochemical cycles of iron (Fe) and organic carbon (OC) are strongly interlinked. In oceanic waters, organic ligands have been shown to control the concentration of dissolved Fe [1], whereas in soils, solid Fe phases provide a sheltering and preservative effect for organic matter [2]. Until now however, the role of iron in the preservation of OC in sediments has not been clearly established. Here we show that 21.5 ± 8.6% of the OC in sediments is directly bound to reactive iron phases, which promote the preservation of OC in sediments. Iron-bound OC represents a global mass of 19 to 45 × 10^15 g of OC in surface marine sediments. This pool of OC is different from the rest of sedimentary OC, with 13C and nitrogen-enriched organic matter preferentially bound to Fe which suggests that biochemical fractionation occurs with OC-Fe binding. Preferential binding also affects the recovery of high molecular weight lipid biomarkers and acidic lignin oxidation products, changing the environmental message of proxies derived from these biomarkers. [1] Johnson, K. S., Gordon, R. M. & Coale, K. H. What controls dissolved iron in the world ocean? Marine Chemistry 57, 137-161 (1997). [2] Kaiser, K. & Guggenberger, G. The role of DOM sorption to mineral surfaces in the preservation of organic matter in soils. Organic Geochemistry 31, 711-725 (2000).

Assessment of soil erosion risk in Komering watershed, South Sumatera, using SWAT model

NASA Astrophysics Data System (ADS)

Salsabilla, A.; Kusratmoko, E.

2017-07-01

Changes in land use watershed led to environmental degradation. Estimated loss of soil erosion is often difficult due to some factors such as topography, land use, climate and human activities. This study aims to predict soil erosion hazard and sediment yield using the Soil and Water Assessment Tools (SWAT) hydrological model. The SWAT was chosen because it can simulate the model with limited data. The study area is Komering watershed (806,001 Ha) in South Sumatera Province. There are two factors land management intervention: 1) land with agriculture, and 2) land with cultivation. These factors selected in accordance with the regulations of spatial plan area. Application of the SWAT demonstrated that the model can predict surface runoff, soil erosion loss and sediment yield. The erosion risk for each watershed can be classified and predicted its changes based on the scenarios which arranged. In this paper, we also discussed the relationship between the distribution of erosion risk and watershed's characteristics in a spatial perspective.

The influence of the annual invasive plant, Impatiens glandulifera, on the sediment dynamics of inland watercourses in temperate regions

NASA Astrophysics Data System (ADS)

Dalvi, Shrutika; Greenwood, Philip

2016-04-01

Impatiens glandulifera (Common English Name - Himalayan Balsam) is a non native annual and highly invasive plant that was introduced into parts of Europe from the Himalaya during the nineteenth century as a colourful adornment to parks and gardens. This Plant colonises areas along the river banks, preferably wet, depositional sites, and displaces natural vegetation. The plant is killed by cold weather. The leaves area of riverbank previously occupied by the plant extremely vulnerable to soil erosion until new plant germinates in the following spring. Research work undertaken in the northwest Switzerland and the soutwestern United Kingdom established s link between accelerated soil erosion caused by Impatiens glandulifera and its detrimental impact on native biodiversity of riparian zone of river catchment area. This study focueses on the potential impact of such erosion on sediment quality. A priory reasoning suggests that the preference of Impatiens glandulifera on young depsotional sites near watercourses affects sediment quality. In this study, the results of a soil quality analysis along Impatiens glandulifera-contaminated river banks is presented. Soil physical and chemical properties are compared to non-affected sites to assess the potential impact of preferential erosion on water quality. In addtiion, soil surface profile (SSP) measuring based on by erosion pins, a micro profile bridge and a digital calliper at different selected locations along the riparian zone of river catchment area is used to determine erosion rates and determine sediment transfer from the riparian zone into the rivers.

Geophysical techniques for reconnaissance investigations of soils and surficial deposits in mountainous terrain

USGS Publications Warehouse

Olson, C.G.; Doolittle, J.A.

1985-01-01

Two techniques were assessed for their capabilities in reconnaissance studies of soil characteristics: depth to the water table and depth to bedrock beneath surficial deposits in mountainous terrain. Ground-penetrating radar had the best near-surface resolution in the upper 2 m of the profile and provided continuous interpretable imagery of soil profiles and bedrock surfaces. Where thick colluvium blankets side slopes, the GPR could not consistently define the bedrock interface. In areas with clayey or shaley sediments, the GPR is also more limited in defining depth and is less reliable. Seismic refraction proved useful in determining the elevation of the water table and depth to bedrock, regardless of thickness of overlying material, but could not distinguish soil-profile characteristics.-from Authors

Comparing Background and Recent Erosion Rates in Degraded Areas of Southeastern Brazil

NASA Astrophysics Data System (ADS)

Fernandes, N.; Bierman, P. R.; Sosa-Gonzalez, V.; Rood, D. H.; Fontes, R. L.; Santos, A. C.; Godoy, J. M.; Bhering, S.

2014-12-01

Soil erosion is a major problem in northwestern Rio de Janeiro State where, during the last three centuries, major land-use changes took place, associated with the replacement of the original rainforest by agriculture and grazing. The combination of steep hillslopes, erodible soils, sparse vegetation, natural and human-induced fires, as well as downslope ploughing, led to an increase in surface runoff and surface erosion on soil-mantled hillslopes; together, these actions and responses caused a decline in soil productivity. In order to estimate changes in erosion rates over time, we compared erosion rates measured at different spatial and temporal scales, both background (natural) and short-term (human-induced during last few decades). Background long-term erosion rates were measured using in-situ produced cosmogenic 10Be in the sand fraction quartz of active river channel sediment in four basins in the northwestern portion of Rio de Janeiro State. In these basins, average annual precipitation varies from 1,200 to 1,300 mm, while drainage areas vary from 15 to 7,200 km2. Short-term erosion rates were measured in one of these basins from fallout 210Pb in soil samples collected along a hillslope transect located in an abandoned agriculture field. In this transect, 190 undisturbed soil samples (three replicates) were collected from the surface to 0.50 m depth (5 cm vertical intervals) in six soil pits. 10Be average background, basin-wide, erosion rates in the area are ~ 13 m/My; over the last decades, time-integrated (210Pb) average hillslope erosion rates are around 1450 m/Myr, with maximum values at the steepest portion of convex hillslopes of about 2000 m/Myr. These results suggest that recent hillslope erosion rates are about 2 orders of magnitude above background rates of sediment generation integrated over many millennia. This unsustainable rate of soil loss has severely decreased soil productivity eventually leading to the abandonment of farming activities in areas where soil loss is severe.

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

Gustavson, T.C.; Holliday, V.T.

Eolian sediments have accumulated as non-glacigenic loess and thin sand sheets on the Central and Southern High Plains grasslands of Texas and new mexico since the late Miocene. Locally as much as 110 m of eolian sediments with numerous paleosols are preserved in the Quaternary Blackwater Draw formation and the upper part of the Miocene-Pleiocene Ogallala formation. These sediments and paleosols, which cover more than 130,000 km{sup 2}, are similar to recent surface sediments and soils and record a long period of episodic eolian transport and sedimentation, and pedogenesis on a stable low-relief grass-covered landscape. Eolian sections, which comprise themore » fine sand to coarse silt lithofacies of the Ogallala formation, and the very fine to fine sand and sandy mud lithofacies of the Blackwater Draw formation, generally lack primary sedimentary structures. Grain size of Ogallala sediments decreases from west to east and grain size of Blackwater Draw sediments decreases from southwest to northeast. Soil horizonation is well developed in most sections, and buried calcic and argillic horizons are common. Calcic horizons are characterized by sharply increased CaCO{sub 3} content in the form of filaments, nodules, and petrocalcic horizons (calcretes). Argillic horizons are characterized by increased illuvial clay, pedogenic structure, and darker reddish hues. Rhizocretions are common locally. Open root tubules, which are typically less than 1 mm in diameter and characteristic of small plants like grasses, are present in all Ogallala and Blackwater Draw eolian sediments. Paleosols preserved in eolian sediments of the High Plains reflect periods of sedimentation followed by episodes of landscape stability and pedogenesis, and negligible sedimentation. Episodes of sedimentation and soil development likely resulted from cyclic decreases and increases in available moisture and vegetative cover. Eolian sediments were eroded and transported eastward during dry periods when vegetation was sparse in source areas, such as the western High Plains and the Pecos Valley. During humid periods more abundant vegetation probably protected source areas from deflation, and resulted in landscape stability across the High Plains.« less

Deposition, Accumulation, and Alteration of Cl(-), NO3(-), ClO4(-) and ClO3(-) Salts in a Hyper-Arid Polar Environment: Mass Balance and Isotopic Constraints

NASA Technical Reports Server (NTRS)

Jackson, Andrew; Davila, Alfonso F.; Boehlke, J. K.; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrette, Megan; Lacell, Denis; McKay, Christopher P.; Poghosyan, Armen;

Deposition, accumulation, and alteration of Cl-, NO3-, ClO4- and ClO3- salts in a hyper-arid polar environment: Mass balance and isotopic constraints

NASA Astrophysics Data System (ADS)

Jackson, Andrew; Davila, Alfonso F.; Böhlke, John Karl; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrett, Maeghan; Lacelle, Denis; McKay, Christopher P.; Poghosyan, Armen; Pollard, Wayne; Zacny, Kris

2016-06-01

The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources. We expand upon this work by evaluating permafrost soil/sediments in University Valley, located in the ultraxerous zone where both liquid water transport and marine influences are minimal. We determined the abundances of Cl-, NO3-, ClO4- and ClO3- in dry and ice-cemented soil/sediments, snow and glacier ice, and also characterized Cl- and NO3- isotopically. The data are not consistent with salt deposition in a sublimation till, nor with nuclear weapon testing fall-out, and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate, from minimal alteration in bare soils to significant alteration (photodegradation and/or volatilization) in snow and glacier ice. Ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions, likely due to percolation of snowmelt. Subtle changes in ClO4-/NO3- ratios and NO3- isotopic composition with depth and location may reflect both transport related fractionation and depositional history. Low molar ratios of ClO3-/ClO4- in surface soils compared to deposition and other arid systems suggest significant post depositional loss of ClO3-, possibly due to reduction by iron minerals, which may have important implications for oxy-chlorine species on Mars. Salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from ∼10 to 30 kyr near the glacier to 70-200 kyr near the valley mouth. The relatively young age of the salts and relatively low and homogeneous anion concentrations in the ice-cemented sediments point to either a mechanism of recent salt removal, or to relatively modern permafrost soils (<1 million years). Together, our results show that near surface salts in University Valley serve as an end-member of stratospheric sources not subject to biological processes or extensive remobilization.

Interactions Between Wind Erosion, Vegetation Structure, and Soil Stability in Groundwater Dependent Plant Communities

NASA Astrophysics Data System (ADS)

Vest, K. R.; Elmore, A. J.; Okin, G. S.

2009-12-01

Desertification is a human induced global phenomenon causing a loss of biodiversity and ecosystem productivity. Semi-arid grasslands are vulnerable to anthropogenic impacts (i.e., groundwater pumping and surface water diversion) that decrease vegetation cover and increase bare soil area leading to a greater probability of soil erosion, potentially enhancing feedback processes associated with desertification. To enhance our understanding of interactions between anthropogenic, physical, and biological factors causing desertification, this study used a combination of modeling and field observations to examine the relationship between chronic groundwater pumping and vegetation cover change and its effects on soil erosion and stability. The work was conducted in Owens Valley California, where a long history of groundwater pumping and surface water diversion has lead to documented vegetation changes. The work examined hydrological, ecological and biogeochemical factors across thirteen sites in Owens Valley. We analyzed soil stability, vegetation and gap size, soil organic carbon, and we also installed Big Spring Number Eight (BSNE) catchers to calculate mass transport of aeolian sediment across sites. Mass transport calculations were used to validate a new wind erosion model that represents the effect of porous vegetation on surface windshear velocity. Results across two field seasons show that the model can be used to predict mass transport, and areas with increased groundwater pumping show a greater susceptibility to erosion. Sediment collected in BSNE catchers was positively correlated with site gap size. Additionally, areas with larger gap sizes have a greater threshold shear velocity and soil stability, yet mass transport was greater at these sites than at sites with smaller gap sizes. Although modeling is complicated by spatial variation in multiple model parameters (e.g., gap size, threshold shear velocity in gaps), our results support the hypothesis that soils with high organic matter are being eroded following the loss of vegetation cover due to groundwater decline leaving behind bare soil surfaces with less fertility hampering vegetation reestablishment. Desertification in this system is apparently easily initiated through groundwater decline due to the high friability of these meadow soils.

The effect of leaf litter cover on surface runoff and soil erosion in Northern China.

PubMed

Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

2014-01-01

The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h-1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes.

The Effect of Leaf Litter Cover on Surface Runoff and Soil Erosion in Northern China

PubMed Central

Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

2014-01-01

The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h−1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes. PMID:25232858

Effects of gully erosion on sediment connectivity in a small agrarian catchment: basis of an experimental proposal

NASA Astrophysics Data System (ADS)

Zubieta, Elena; Casalí, Javier; Masselink, Rens J. H.; Giménez, Rafael; Keesstra, Saskia D.

2017-04-01

Connectivity aims to explain the transit of substances in a certain (natural) area. Thereby, the connectivity of sediments from soil erosion involves complex factors determining the subsequent movement of detached matter across the land (for instance, a hydrographic catchment). Agricultural soil erosion in Navarre has been studied mainly by recording sediments at the outlets of experimental catchments. These studies have revealed a complex dynamics in the sediments. For example, a clear seasonality was noticed, with the highest records in winter and the beginning of spring, coinciding, however, with rainfall events of a relatively low erosion capacity. In fact, this dynamics was not only conditioned by the intensity and duration of precipitations, but also, for instance, by the soil's previous humidity, use and management, and by plant cover. Further, it was suspected that a key factor in sediment connectivity would be erosion due to concentrated flows (i.e. ephemeral gullies), which would act as a source and transport of sediments. The aim of this research is to monitor, long-term, the movement of sediments generated by erosion from ephemeral gullies within a typical agrarian catchment in Navarra, in order to clarify the role played by those gullies in sediment connectivity. The experiments will be performed in the experimental catchment of "La Tejería" (169 ha) located in the Central Area of Navarre, and which is frequently affected by concentrated flow erosion and with long-term records of sediments at its outlet. The climate is humid submediterranean, with an average annual precipitation of approximately 725 mm. The prevailing soil class is Vertic Haploxerept and cereal crops usually cover over 90% of the total area. Our previous experience in the study area would permit the prediction, with a high degree of certainty, of the appearance of ephemeral gullies at least in 4-5 watercourses selected. A specific tracer (a rare-earth oxide) will be sprinkled over each watercourse following the methodology proposed by Masselink et al.(under review). This will also be done throughout the principal channel of the catchment in an area next to its outlet. These tracers do not affect either the soil properties - or therefore their erodibility - or the natural process of sediment transport by runoff either. With the formation of each gully, after the occurrence of rain events, significant for their intensity or duration, the surface layer of the soil will be sampled. This will be carried out throughout the natural drainage network of the catchment (determined from a high resolution DEM), starting from the gully upper limit to the main channel of the catchment. The soil samples will be analysed in our laboratory. A very much higher rare-earth oxide concentration than those found naturally in the soil would indicate that this element comes from the experimentation and, therefore, from a certain gully. The spatial-temporal monitoring of the sediments from different gullies associated with rainfall records, soil conditions, degree of plant cover, and sediment records at the catchment outlet, would contribute to a better understanding of sediment movement and the factors conditioning its dynamics. References Masselink, R. J.H., A. Temme, R. Giménez, J. Casalí, S. Keesstra. Determining hillslope-channel connectivity in an agricultural catchment using rare-earth oxide tracers and random forests. Cuadernos de Investigación Geográfica. (Under review).

Surface disturbances: their role in accelerating desertification

USGS Publications Warehouse

Belnap, Jayne

1995-01-01

Maintaining soil stability and normal water and nutrient cycles in desert systems is critical to avoiding desertification. These particular ecosystem processes are threatened by trampling of livestock and people, and by off-road vehicle use. Soil compaction and disruption of cryptobiotic soil surfaces (composed of cyanobacteria, lichens, and mosses) can result in decreased water availability to vascular plants through decreased water infiltration and increased albedo with possible decreased precipitation. Surface disturbance may also cause accelerated soil loss through wind and water erosion and decreased diversity and abundance of soil biota. In addition, nutrient cycles can be altered through lowered nitrogen and carbon inputs and slowed decomposition of soil organic matter, resulting in lower nutrient levels in associated vascular plants. Some cold desert systems may be especially susceptible to these disruptions due to the paucity of surface-rooting vascular plants for soil stabilization, fewer nitrogen-fixing higher plants, and lower soil temperatures, which slow nutrient cycles. Desert soils may recover slowly from surface disturbances, resulting in increased vulnerability to desertification. Recovery from compaction and decreased soil stability is estimated to take several hundred years. Re-establishment rates for soil bacterial and fungal populations are not known. The nitrogen fixation capability of soil requires at least 50 years to recover. Recovery of crusts can be hampered by large amounts of moving sediment, and re-establishment can be extremely difficult in some areas. Given the sensitivity of these resources and slow recovery times, desertification threatens million of hectares of semiarid lands in the United States.

Anthropogenic Increase Of Soil Erosion In The Gangetic Plain Revealed By Geochemical Budget Of Erosion

NASA Astrophysics Data System (ADS)

Galy, V.; France-Lanord, C.; Galy, A.; Gaillardet, J.

2007-12-01

Tectonic and climatic factors are the key natural variables controlling the erosion through complex interactions. Nonetheless, over the last few hundred years, human activity also exerts a dominant control in response to extensive land use. The geochemical budget of erosion allows the balance between the different erosion processes to be quantified. The chemical composition of river sediment results from the chemical composition of the source rock modified by (1) weathering reactions occurring during erosion and (2) physical segregation during transport. If erosion is at steady state, the difference between the chemical composition of source rocks and that of river sediments must therefore be counterbalanced by the dissolved flux. However, climatic variations or anthropic impact can induce changes in the erosion distribution in a given basin resulting in non steady state erosion. Using a mass balance approach, the comparison of detailed geochemical data on river sediments with the current flux of dissolved elements allows the steady state hypothesis to be tested. In this study, we present a geochemical budget of weathering for the Ganga basin, one of the most densely populated basin in the world, based on detailed sampling of Himalayan rivers and of the Ganga in the delta. Sampling includes depth profile in the river, to assess the variability generated by transport processes. Himalayan river sediments are described by the dilution of an aluminous component (micas + clays + feldspars) by quartz. Ganga sediments on the other hand correspond to the mixing of bedload, similar to coarse Himalayan sediments, with an aluminous component highly depleted in alkaline elements. Compared with the dissolved flux, the depletion of alkaline elements in Ganga sediments shows that the alkaline weathering budget is imbalanced. This imbalance results from an overabundance of fine soil material in the Ganga sediment relative to other less weathered material directly derived from Himalaya. Based on the average composition of the suspended load and of floodplain soils, we estimate that 250x106 t/yr i.e. 5 t/ha/yr is eroded from soil surfaces of the Ganga floodplain. This enhanced soil erosion is likely triggered by intense deforestation and change in land use due to increasing human activity in the basin.

Anthropogenic sediments and soils of tells of the Balkans and Anatolia: Composition, genesis, and relationships with the history of landscape and human occupation

NASA Astrophysics Data System (ADS)

Sedov, S. N.; Aleksandrovskii, A. L.; Benz, M.; Balabina, V. I.; Mishina, T. N.; Shishkov, V. A.; Şahin, F.; Özkaya, V.

2017-04-01

Soils and sediments composing Tell Körtik Tepe (Epipaleolithic, Turkey) and Tell Yunatsite (Chalcolithic (Eneolithic), Bulgaria) have been studied with the aim to gain a better insight into their microfabrics, determine the composition of anthropogenic artifacts, and, on this basis, to analyze similarities and distinctions between these objects and the modern soils of urban areas. The methods of micromorphology, scanning electron microscopy with an energy dispersive X-ray microanalyzer, X-ray fluorometry, and other techniques to determine the chemical and physical properties of the soils and sediments have been applied. Two paleosols have been identified in Tell Yunatsite with a total thickness of 9 m: the paleosol buried under the tell and the paleosol in its middle part. Sediments of Tell Körtik Tepe have a total thickness of up to 5 m; their accumulation began at the end of Pleistocene over the surface of buried paleosol. The cultural layer of the tells consists of construction debris mainly represented by a mixture of clay and sand and of domestic wastes with the high content of phosphorus. The major source of phosphorus is calcium phosphate (apatite) of bone tissues. The abundance of various anthropogenic materials in the sediments is clearly seen in thin sections. Even in the paleosols developed within the cultural layer (the mid-profile paleosol in Tell Yunatsite), the amount of microinclusions of bone fragments, charcoal, and burnt clay (ceramics) is very high. Micromorphological data indicate that up to 50% of the layered material filling an Epipaleolithic construction in Tell Körtik Tepe consists of the anthropogenic inclusions: bone fragments, charcoal, etc. The features of pedogenic transformation are present in the sediments. Such sediments can be classified as synlithogenic soils similar to the modern Urbic Technosols. It is shown that the formation of paleosols and sediments of Tell Körtik Tepe took place under extreme environmental conditions—arid climate of the latest Pleistocene climate cooling phase (the Younger Dryas, Tell Körtik Tepe)—and intensive anthropogenic loads (tells Körtik Tepe and Yunatsite).

[Spatiotemporal variation characteristics of heavy metals pollution in the water, soil and sediments environment of the Lean River-Poyang Lake Wetland].

PubMed

Jian, Min-Fei; Li, Ling-Yu; Xu, Peng-Fei; Chen, Pu-Qing; Xiong, Jian-Qiu; Zhou, Xue-Ling

2014-05-01

Overlying water, sediments, surface soils in the typical wetland areas of Lean River and Poyang Lake which were rich in non-ferrous metal mineral resources on both sides of the river, were chosen for monitoring heavy metals including copper, lead and cadmium of base flow in average season, flood season, and dry season in 2012. Statistical analysis methods were coupled to characterize the spatiotemporal variation of heavy metals pollution and identify the main sources. The results indicated that the concentrations of copper were the highest in all samples of each sampling sites in the Lean River-Poyang Lake wetland. And the content values of copper, lead and cadmium in different samples of different sampling sites also showed that the content values of copper were higher than those of lead, and the content values of lead were also higher than those of cadmium. The results also showed that the heavy metals pollution of copper, lead and cadmium in flood season was the heaviest whereas the heavy metals pollution in dry season was comparatively light. The results of the contents of the three kinds of heavy metals elements in different sampling sites of the watersheds of lean River showed that the contents of copper in the samples from the upstream sampling sites of Lean River were higher than those of other samples from other sites. And the contents of lead in the samples from the downstream sampling sites of Lean River were higher than those of other samples from other sampling sites. The contents of cadmium in the samples from the midstream sampling sites of Lean River were higher than those of other samples from other sites. The first principal component representing copper pollution explained 36. 99% of the total variance of water quality. The second principal component concerning representing lead pollution explained 30. 12% of the total variance. The correlation analysis results showed that there were significant positive correlations among the contents of copper in sediments and the contents of copper in overlying water. And there was also significant positive correlation between the contents of copper in sediments and the contents of copper in the surface soils. And the correlation analysis showed that there were significant positive correlations among the contents of cadmium in sediments and the contents of cadmium in surface soils. The above results reflected that the copper pollution or cadmium sources of water, soil and sediments were consistent, which were mainly from heavy metal acidic waste of mining emissions. The correlations between other components were not very obvious, which reflected the sources of pollutants were different.

On the origin of saline soils at Blackspring Ridge, Alberta, Canada

NASA Astrophysics Data System (ADS)

Stein, Richard; Schwartz, Franklin W.

1990-09-01

Problems of soil salinity occur at Blackspring Ridge, Alberta, in four different settings. The most seriously affected area is at the base of the ridge where salinity appears as severe salt crusting on the surface, salt-tolerant vegetation, and areas of poor or no crop production. Blackspring Ridge is a structural bedrock high that is underlain by Upper Cretaceous sediment of the Horseshoe Canyon Formation. Bedrock is overlain by fluvial, glacial, lacustrine, and aeolian sediment. Piezometric data indicate that groundwater is recharged on and along the upper flanks of Blackspring Ridge and discharges in southern parts of a lacustrine plain that surrounds the ridge. Hydraulic conductivity data, water-level fluctuations, stable isotopes, and hydrochemical data indicate that the fractured near-surface bedrock and overlying thin-drift sediment constitute a zone of active groundwater flow within which salts are generated and transported. Water discharging from this shallow system evaporates and forms saline areas at the base of the ridge. The most seriously affected areas on the lacustrine plain coincide with places where the water table is less than 1.5m from the ground surface. A high water table occurs locally because of the changing topology of geologic units, and lows in the topographic surface that focus groundwater and surface water flows. Some proportion of the shallow groundwater salinized by evaporation is also transported down the flow system where it mixes with unevaporated water. Surface water, from snowmelt and precipitation events, dissolves salt that was deposited at the surface by evaporating groundwater and redistributes the salt to areas of lower elevation.

Conversion of traditional cropland into teak plantations strongly increased soil erosion in montane catchments of Southeastern Asia (Northern Laos; 2002-2014)

NASA Astrophysics Data System (ADS)

Evrard, O.; Ribolzi, O.; Huon, S.; de Rouw, A.; Silvera, N.; Latsachack, K. O.; Soulileuth, B.; Lefèvre, I.; Pierret, A.; Lacombe, G.; Sengtaheuanghoung, O.; Valentin, C.

2017-12-01

Soil erosion delivers an excessive quantity of sediment to rivers of Southeastern Asia. Land use is rapidly changing in this region of the world, and these modifications may further accelerate soil erosion in this area. Although the conversion of forests into cropland has often been investigated, much fewer studies have addressed the replacement of traditional slash-and-burn cultivation systems with commercial perennial monocultures such as teak plantations. The current research investigated the impact of this land use change on the hydrological response and the sediment yields from a representative catchment of Northern Laos (Houay Pano, 0.6 km²) where long-term monitoring (2002-2014) was conducted (http://msec.obs-mip.fr/). The results showed a significant growth in the overland flow contribution to stream flow (from 16 to 31%). Furthermore, sediment yields strongly increased from 98 to 609 Mg km-2. These changes illustrate the severity of soil erosion processes occurring under teak plantations characterized by the virtual absence of understorey vegetation to dissipate raindrop energy, which facilitates the formation of an impermeable surface crust. This counter-intuitive increase of soil erosion generated by afforestation reflects the difficulty to find sustainable production solutions for the local populations of Southeastern Asia. To reduce soil loss under teak plantations, the development of extensive agro-forestry practices could be promoted.

Monitoring sediment transfer processes on the desert margin

NASA Technical Reports Server (NTRS)

Millington, Andrew C.; Arwyn, R. Jones; Quarmby, Neil; Townshend, John R. G.

1987-01-01

LANDSAT Thematic Mapper and Multispectral Scanner data have been used to construct change detection images for three playas in south-central Tunisia. Change detection images have been used to analyze changes in surface reflectance and absorption between wet and dry season (intra-annual change) and between different years (inter-annual change). Change detection imagery has been used to examine geomorphological changes on the playas. Changes in geomorphological phenomena are interpreted from changes in soil and foliar moisture levels, differences in reflectances between different salt and sediments and the spatial expression of geomorphological features. Intra-annual change phenomena that can be detected from multidate imagery are changes in surface moisture, texture and chemical composition, vegetation cover and the extent of aeolian activity. Inter-annual change phenomena are divisible into those restricted to marginal playa facies (sedimentation from sheetwash and alluvial fans, erosion from surface runoff and cliff retreat) and these are found in central playa facies which are related to the internal redistribution of water, salt and sediment.

Formation of natural gas hydrates in marine sediments. Gas hydrate growth and stability conditioned by host sediment properties

USGS Publications Warehouse

Clennell, M.B.; Henry, P.; Hovland, M.; Booth, J.S.; Winters, W.J.; Thomas, M.

2000-01-01

The stability conditions of submarine gas hydrates (methane clathrates) are largely dictated by pressure, temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of the host sediments also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our model presumes that gas hydrate behaves in a way analogous to ice in the pores of a freezing soil, where capillary forces influence the energy balance. Hydrate growth is inhibited within fine-grained sediments because of the excess internal phase pressure of small crystals with high surface curvature that coexist with liquid water in small pores. Therefore, the base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature, and so nearer to the seabed than would be calculated from bulk thermodynamic equilibrium. The growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, sheets, and lenses in muds; cements in sand and ash layers) can be explained by a requirement to minimize the excess of mechanical and surface energy in the system.

Transfer of fallout radionuclides derived from Fukushima NPP accident: 1 year study on transfer of radionuclides through hydrological processes

NASA Astrophysics Data System (ADS)

Onda, Yuichi; Kato, Hiroaki; Patin, Jeremy; Yoshimura, Kazuya; Tsujimura, Maki; Wakahara, Taeko; Fukushima, Takehiko

2013-04-01

Previous experiences such as Chernobyl Nuclear Power Plant accident have confirmed that fallout radionuclides on the ground surface migrate through natural environment including soils and rivers. Therefore, in order to estimate future changes in radionuclide deposition, migration process of radionuclides in forests, soils, ground water, rivers should be monitored. However, such comprehensive studies on migration through forests, soils, ground water and rivers have not been conducted so far. Here, we present the following comprehensive investigation was conducted to confirm migration of radionuclides through natural environment including soils and rivers. 1)Study on depth distribution of radiocaesium in soils within forests, fields, and grassland 2)Confirmation of radionuclide distribution and investigation on migration in forests 3)Study on radionuclide migration due to soil erosion under different land use 4)Measurement of radionuclides entrained from natural environment including forests and soils 5)Investigation on radionuclide migration through soil water, ground water, stream water, spring water under different land use 6)Study on paddy-to-river transfer of radionuclides through suspended sediments 7)Study on river-to-ocean transfer of radionuclides via suspended sediments 8)Confirmation of radionuclide deposition in ponds and reservoirs

The role of a coarse surface layer in impeding evaporation from gravel bars

NASA Astrophysics Data System (ADS)

Edmaier, Katharina; Peter, Molnar; Clémentine, Cyprien; Paolo, Burlando

2010-05-01

The presence of a coarse surface layer (CSL) on bars in gravel bed rivers is expected to have an influence on evaporation rates from these surfaces and thereby on the water content in the underlying gravel-sand matrix. A statistically significant increase in soil water content in the presence of a CSL has recently been demonstrated in outdoor experiments by Meier and Hauer (2010). The authors argued that the CSL leads to a reduction in available energy for evaporation, decreases the advection of water vapour from the evaporating surface and reduces the supply of water from the underlying matrix to the evaporating surface. These findings are important because the germination of seeds and vegetative reproduction of riparian species on gravel bars are presumed to be driven by local soil moisture availability. Therefore local conditions of erosion-deposition which lead to the presence or absence of a CSL could be a crucial parameter for successful vegetation establishment on gravel bars. We conducted a simple laboratory experiment to verify the findings of Meier and Hauer (2010) under more controlled conditions. In the experiment 6 cylindrical buckets with a surface area of 720 cm2 and total volume of 19500 cm3 were filled with a sand-gravel mixture to replicate the sediment composition in the Thur River, Switzerland (d50 = 8 mm). This site is part of the research project RECORD (www.record.ethz.ch), which focuses on river restoration issues. Three treatments were investigated, each with a CSL of different thickness (H = 0, 40 and 80 mm) with one replicate each, roughly corresponding to 2 and 4 layers of typical CSL gravel diameters in the Thur River. We also measured the temperature in the sediment matrix underneath the CSL. The samples were saturated over several days and subsequently gravitationally drained in order to retain water held only by capillary forces as the initial condition. The samples were then weighed daily for 47 days and the evaporation rates and the soil water content were computed and analyzed. Our results support the findings of Meier and Hauer (2010). The average evaporation rate without a CSL was 1 mm/day, while for the treatments H = 40 and 80 mm it was 0.3 and 0.17 mm/day respectively. These changes were highly statistically significant (Kruskal-Wallis and T tests). At the end of the experiment after 47 days, the volumetric soil moisture retained in the sediment related to the fine matrix was only 5% without CSL while it was 18-22% with a CSL depending on the treatment. For comparison the porosity of the fine sediment matrix was 33%. We conclude that a CSL decreases evaporation rates and maintains higher soil moisture in the underlying sediment matrix due to its shielding effect but that the effectiveness of the CSL at a site far from the water table will depend on the interarrival time of rainfall (and flood inundation) which replenishes the soil moisture at that location. In ongoing laboratory experiments we are currently studying whether the shielding effect is significant for root growth of typical riparian species such as Salix by planting cuttings into different treatments and monitoring the evapotranspiration rates as well as the length and architecture of the root system which develops.

Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria

NASA Technical Reports Server (NTRS)

Happell, James D.; Chanton, Jeffrey P.; Whiting, Gary J.; Showers, William J.

1993-01-01

The stable carbon isotopic composition of CH4 is used to study the processes that affect it during transport through plants from sediment to the atmosphere. The enhancement of CH4 flux from Cladium and Eleocharis over the flux from open water or clipped sites indicated that these plants served as gas conduits between the sediments and the atmosphere. Lowering of the water table below the sediment surface caused an Everglades sawgrass marsh to shift from emission of CH4 to consumption of atmospheric CH4. Cladium transported gases passively mainly via molecular diffusion and/or effusion instead of actively via bulk flow. Stable isotropic data gave no evidence that CH4 oxidation was occurring in the rhizosphere of Cladium. Both CH4 stable carbon isotope and flux data indicated a lack of CH4 oxidation at the sediment-water interface in Everglades marl soils and its presence in peat soils where 40 to 92 percent of the flux across the sediment-water interface was oxidized.

Health assessment for Harvey and Knott Drum National Priorities List (NPL) Site, New Castle County, Delaware, Region 3. CERCLIS No. DED980713093. Final report

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

Not Available

The Harvey Knott Drum National Priorities List site, located near Kirkwood in New Castle County, Delaware, is an inactive landfill that had received sanitary, municipal and industrial wastes. Contaminants released from the site include heavy metals and organic compounds and have entered groundwater, soils, sediments, and surface waters. The principal concern is that contaminated groundwater may migrate to off-site domestic, public, and agricultural water supply wells. Also, contaminants in off-site surface water and sediments pose some concern for recreational use and consumption of fish. Off-site contaminated soils near the west property line may be a threat to persons that trespassmore » into that area. The site is of potential health concern because of the risk to human health resulting from possible exposure to hazardous substances at concentrations that may result in adverse health effects.« less

Mass tree mortality leads to mangrove peat collapse at Bay Islands, Honduras after Hurricane Mitch

USGS Publications Warehouse

Cahoon, D.R.; Hensel, P.; Rybczyk, J.; McKee, K.L.; Proffitt, C.E.; Perez, B.C.

2003-01-01

We measured sediment elevation and accretion dynamics in mangrove forests on the islands of Guanaja and Roatan, Honduras, impacted by Hurricane Mitch in 1998 to determine if collapse of underlying peat was occurring as a result of mass tree mortality. Little is known about the balance between production and decomposition of soil organic matter in the maintenance of sediment elevation of mangrove forests with biogenic soils. Sediment elevation change measured with the rod surface elevation table from 18 months to 33 months after the storm differed significantly among low, medium and high wind impact sites. Mangrove forests suffering minimal to partial mortality gained elevation at a rate (5 mm yeara??1) greater than vertical accretion (2 mm yeara??1) measured from artificial soil marker horizons, suggesting that root production contributed to sediment elevation. Basin forests that suffered mass tree mortality experienced peat collapse of about 11 mm yeara??1 as a result of decomposition of dead root material and sediment compaction. Low soil shear strength and lack of root growth accompanied elevation decreases. Model simulations using the Relative Elevation Model indicate that peat collapse in the high impact basin mangrove forest would be 37 mm yeara??1 for the 2 years immediately after the storm, as root material decomposed. In the absence of renewed root growth, the model predicts that peat collapse will continue for at least 8 more years at a rate (7 mm yeara??1) similar to that measured (11 mm yeara??1). Mass tree mortality caused rapid elevation loss. Few trees survived and recovery of the high impact forest will thus depend primarily on seedling recruitment. Because seedling establishment is controlled in large part by sediment elevation in relation to tide height, continued peat collapse could further impair recovery rates.

Steady as a rock: Biogeomorphic influence of nurse rocks and slope processes on kūpaoa (Dubautia menziesii) shrubs in Haleakalā Crater (Maui, Hawai'i)

NASA Astrophysics Data System (ADS)

Pérez, Francisco L.

2017-10-01

This study examines biogeomorphic interactions between nurse rocks, slope processes, and 300 kūpaoa (Dubautia menziesii) shrubs in Haleakalā Crater (Maui, Hawai'i). Research objectives were to: assess the association of kūpaoa with substrates upslope and downslope of plants, and proximity to the closest rock uphill; contrast shrub/substrate relationships with site frequency of sediment types; measure surface soil shear-strength and compressibility on 50 paired locations near boulders; and investigate the aggregation characteristics and spatial patterns of kūpaoa in relation to rock and substrate variation. Data analyzed came from three 100-plant surveys at 3 sites: a plant census at 2720-2975 m altitude, and wandering-quarter transects (WQTs) across two areas (2610-2710 m); ground sediment cover was estimated along four phototransects on these sites. Data for the three 100-plant surveys included substrate type-outcrops, blocks, cobbles, pebbles, exposed soil, organic litter-upslope from each plant, and distance to the largest rock upslope. The two surveys examined along WQTs included substrate type found downslope from kūpaoa, plant height, plant diameters across and along the slope, and distance between successively censused plants. Most plants grew downslope of nurse rocks; > 74% were adjacent to blocks or outcrops, and > 17% near cobbles. Plants showed avoidance for finer substrates; only 5.3% and 2.7% grew on/near bare soils and pebbles, respectively. About 92% of kūpaoa were ≤ 10 cm downslope of rocks; > 89% grew ≤ 2 cm away, and 83% in direct contact with a rock. Some seedlings also grew on pukiawe (Leptecophylla tameiameiae) nurse plants. Several stable rock microsites protected plants from disturbance by slope processes causing debris shift. Site sediments were significantly finer than substrates near plants; shrubs grew preferentially adjacent to boulders > 20 cm wide, which were more common near plants than across sites. Soils downslope of 50 boulders-mean 41.3 cm-showed higher shear strength and compressibility than soils along rock sides. These boulder dams stop descending debris, steadily deflecting them toward rock sides, whereas protected soils downslope of blocks are infrequently disturbed and develop into downslope elongated, clast-free fine-earth flags. Kūpaoa were uniformly dispersed across slopes, showing a single-phase mosaic arrangement, without apparent aggregation. Slopes where kūpaoa grows had a relatively uniform distribution of surface sediments; observed kūpaoa patterns may have resulted from the array of microsites generated by surface rocks and sediments, as shrubs simply responded to such spatial structure.

Retention of 14C-labeled multiwall carbon nanotubes by humic acid and polymers: Roles of macromolecule properties

PubMed Central

Zhao, Qing; Petersen, Elijah J.; Cornelis, Geert; Wang, Xilong; Guo, Xiaoying; Tao, Shu; Xing, Baoshan

2016-01-01

Developing methods to measure interactions of carbon nanotubes (CNTs) with soils and sediments and understanding the impact of soil and sediment properties on CNT deposition are essential for assessing CNT environmental risks. In this study, we utilized functionalized carbon-14 labeled nanotubes to systematically investigate retention of multiwall CNTs (MWCNTs) by 3 humic acids, 3 natural biopolymers, and 10 model solid-phase polymers, collectively termed macromolecules. Surface properties, rather than bulk properties of macromolecules, greatly influenced MWCNT retention. As shown via multiple linear regression analysis and path analysis, aromaticity and surface polarity were the two most positive factors for retention, suggesting retention was regulated by π-π stacking and hydrogen bonding interactions. Moreover, MWCNT deposition was irreversible. These observations may explain the high retention of MWCNT in natural soils. Moreover, our findings on the relative contribution of each macromolecule property on CNT retention provide information on macromolecule selection for removal of MWCNTs from wastewater and provide a method for measuring CNT interactions with organic macromolecules. PMID:27458320

Denitrification potential in relation to lithology in five headwater riparian zones.

PubMed

Hill, Alan R; Vidon, Philippe G F; Langat, Jackson

2004-01-01

The influence of riparian zone lithology on nitrate dynamics is poorly understood. We investigated vertical variations in potential denitrification activity in relation to the lithology and stratigraphy of five headwater riparian zones on glacial till and outwash landscapes in southern Ontario, Canada. Conductive coarse sand and gravel layers occurred in four of the five riparian areas. These layers were thin and did not extend to the field-riparian perimeter in some riparian zones, which limited their role as conduits for ground water flow. We found widespread organic-rich layers at depths ranging from 40 to 300 cm that resulted from natural floodplain processes and the burial of surface soils by rapid valley-bottom sedimentation after European settlement. The organic matter content of these layers varied considerably from 2 to 5% (relic channel deposit) to 5 to 21% (buried soils) and 30 to 62% (buried peat). Denitrification potential (DNP) was measured by the acetylene block method in sediment slurries amended with nitrate. The highest DNP rates were usually found in the top 0- to 15-cm surface soil layer in all riparian zones. However, a steep decline in DNP with depth was often absent and high DNP activity occurred in the deep organic-rich layers. Water table variations in 2000-2002 indicated that ground water only interacted frequently with riparian surface soils between late March and May, whereas subsurface organic layers that sustain considerable DNP were below the water table for most of the year. These results suggest that riparian zones with organic deposits at depth may effectively remove nitrate from ground water even when the water table does not interact with organic-rich surface soil horizons.

[GIS Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Shallow Lakes in Jiangsu Province].

PubMed

Li, Ying-jie; Zhang, Lie-yu; Wu, Yi-wen; Li, Cao-le; Yang, Tian-xue; Tang, Jun

2016-04-15

To understand pollution of heavy metals in surface sediments of shallow lakes, surface sediments samples of 11 lakes in Jiangsu province were collected to determine the content of six heavy metals including As, Cr, Cu, Pb, Zn and Ni. GIS was used to analyze the spatial distribution of heavy metals, and geological accumulation index (Igeo), modified contamination index (mCd) pollution load index (PLI) and potential ecological risk index (RI) were used to evaluate heavy metal contamination in the sediments. The results showed that: in the lakes' surface sediments, the average content of As, Cu, Zn, Cr, Pb, Ni in multiples of soil background of Jiangsu province were 1.74-3.85, 0.65-2.66, 0.48-3.56, 0.43-1.52, 0.02-1.49 and 0.12-1.42. According to the evaluation results of Igeo and RI, As, which had high degree of enrichment and great potential ecological risk, was the main pollutant, followed by Cu, and pollution of the rest of heavy metals was relatively light. Combining the results of several evaluation methods, in surface sediments of Sanjiu Lake, Gaoyou Lake and Shaobo Lake, these heavy metals had the most serious pollution, the maximum pollution loading and moderate potential ecological risk; in surface sediments of Gehu Lake, Baima Lake and Hongze Lake, some regions were polluted by certain metals, the overall trend of pollution was aggravating, the pollution loading was large, and the potential ecological risk reached moderate; in the other 5 lakes, the risk of sediments polluted by heavy metals, as well as the pollution loading, was small, and the overall was not polluted.

Rapid-response tools and datasets for post-fire remediation: Linking remote sensing and process-based hydrological models

Treesearch

M. E. Miller; William Elliot; M. Billmire; Pete Robichaud; K. A. Endsley

2016-01-01

Post-wildfire flooding and erosion can threaten lives, property and natural resources. Increased peak flows and sediment delivery due to the loss of surface vegetation cover and fire-induced changes in soil properties are of great concern to public safety. Burn severity maps derived from remote sensing data reflect fire-induced changes in vegetative cover and soil...

The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards.

PubMed

Prosdocimi, Massimo; Jordán, Antonio; Tarolli, Paolo; Keesstra, Saskia; Novara, Agata; Cerdà, Artemi

2016-03-15

Soil and water loss in agriculture is a major problem throughout the world, and especially in Mediterranean areas. Non-conservation agricultural practices have further aggravated the situation, especially in vineyards, which are affected by one of the highest rates of soil loss among cultivated lands. Therefore, it is necessary to find the right soil practices for more sustainable viticulture. In this regard, straw mulching has proven to be effective in other crop and fire affected soils, but, nonetheless, little research has been carried out in vineyards. This research tests the effect of barley straw mulching on soil erosion and surface runoff on vineyards in Eastern Spain where the soil and water losses are non-sustainable. An experiment was setup using rainfall simulation tests at 55 mm h(-1) over 1h on forty paired plots of 0.24 m(2): twenty bare and twenty straw covered. Straw cover varied from 48 to 90% with a median value of 59% as a result of the application of 75 g of straw per m(2). The use of straw mulch resulted in delayed ponding and runoff generation and, as a consequence, the median water loss decreased from 52.59 to 39.27% of the total rainfall. The straw cover reduced the median sediment concentration in runoff from 9.8 to 3.0 g L(-1) and the median total sediment detached from 70.34 to 15.62 g per experiment. The median soil erosion rate decreased from 2.81 to 0.63 Mg ha(-1)h(-1) due to the straw mulch protection. Straw mulch is very effective in reducing soil erodibility and surface runoff, and this benefit was achieved immediately after the application of the straw. Copyright © 2015 Elsevier B.V. All rights reserved.

Dust emissions from unpaved roads on the Colorado Plateau

NASA Astrophysics Data System (ADS)

Duniway, M.; Flagg, C.; Belnap, J.

2013-12-01

On the Colorado Plateau, elevated levels of aeolian dust have become a major land management and policy concern due to its influence on climate, weather, terrestrial ecosystem dynamics, landscape development and fertility, melting of snow and ice, air quality, and human health. Most desert soil surfaces are stabilized by plants, rocks, and/or physical or biological soil crusts, but once disturbed, sediment production from these surfaces can increase dramatically. Road development and use is a common surface disturbing activity in the region. The extent and density of roads and road networks is rapidly increasing due to continued energy exploration, infrastructure development, and off-highway recreation activities. Though it is well known that unpaved roads produce dust, the relative contribution of dust from existing roads or the implications of future road development to regional dust loading is unknown. To address this need, we have initiated a multifaceted research effort to evaluating dust emissions from unpaved roads regionally. At 34 sites arranged across various road surfaces and soil textures in southeastern Utah, we are: 1) monitoring dust emissions, local wind conditions, and vehicle traffic and 2) evaluating fugitive dust potential using a portable wind tunnel and measuring road characteristics that affect dust production. We will then 3) develop a GIS-based model that integrates results from 1 & 2 to estimate potential dust contributions from current and future scenarios of regional road development. Passive, horizontal sediment traps were installed at three distances downwind from the road edge. One control trap was placed upwind of the samplers to account for local, non-road dust emissions. An electronic vehicle counter and anemometer were also installed at monitoring sites. Dust samples were collected every three months at fixed heights, 15 cm up to 100 cm above the soil surface, from March 2010 to the present. Threshold friction velocities (TFV), the minimum wind velocity required to initiate erosion, and sediment production were also quantified using a portable wind tunnel at monitoring sites. Additionally, numerous characteristics including gravel cover, particle-size distribution, soil compaction, and loose-erodible material were measured on road surfaces at monitoring sites. Preliminary results suggest that roads are an important regional dust source, as emissions from roads are comparable to non-road, rural sources that are being monitored concurrently. While gravel roads produce more dust per day on average, per vehicle emissions are larger on dirt roads. Dust flux decreases with distance from the road edge on all road types, however this decline is less pronounced on dirt roads. Portable wind tunnel results indicate that TFV is consistently lower on dirt versus gravel roads across all soil types. Fugitive dust flux is generally larger and more variable on dirt roads compared to gravel roads. Initial analyses suggest that several easily measurable road surface characteristics can potentially be used to predict both TFV and sediment production, including: total gravel cover, gravel particle-size classes, clay content, and road compaction. The relation between TFV and total gravel cover in particular appears to be non-linear, with TFV increasing rapidly above ~40% gravel cover.

Community and functional shifts in ammonia oxidizers across terrestrial and marine (soil/sediment) boundaries in two coastal Bay ecosystems.

PubMed

Zhang, Li-Mei; Duff, Aoife M; Smith, Cindy J

2018-04-24

Terrestrial-marine boundaries are significant sites of biogeochemical activity with delineated gradients from land to sea. While niche differentiation of ammonia-oxidizing archaea (AOA) and bacteria (AOB) driven by pH and nitrogen is well known, the patterns and environmental drivers of AOA and AOB community structure and activity across soil-sediment boundaries have not yet been determined. In this study, nitrification potential rate, community composition and transcriptional activity of AOA and AOB in soil, soil/sediment interface and sediments of two coastal Bays were characterized using a combination of field investigations and microcosm incubations. At DNA level, amoA gene abundances of AOA were significantly greater than AOB in soil, while in sediments AOB were significantly more abundant than AOA, but at the soil/sediment interface there were equal numbers of AOA and AOB amoA genes. Microcosm incubations provided further evidence, through qPCR and DGGE-sequencing analysis of amoA transcripts, that AOA were active in soil, AOB in sediment and both AOA and AOB were active at the soil/sediment interface. The AOA and AOB community composition shifted across the coastal soil-interface-sediment gradient with salinity and pH identified as major environmental drivers. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Using molecular-scale tracers to investigate transport of agricultural pollutants in soil and water

NASA Astrophysics Data System (ADS)

Lloyd, C.; Michaelides, K.; Chadwick, D.; Dungait, J.; Evershed, R. P.

2012-12-01

We explore the use of molecular-scale tracers to investigate the transport of potential pollutants due to the application of slurry to soil. The molecular-scale approach allows us to separate the pollutants which are moved to water bodies through sediment-bound and dissolved transport pathways. Slurry is applied to agricultural land to as a soil-improver across a wide-range of topographic and climatic regimes, hence a set of experiments were designed to assess the effect of changing slope gradient and rainfall intensity on the transport of pollutants. The experiments were carried out using University of Bristol's TRACE (Test Rig for Advancing Connectivity Experiments) facility. The facility includes a dual axis soil slope (6 x 2.5 x 0.3 m3) and 6-nozzle rainfall simulator, which enables the manipulation of the slope to simulate different slope gradient and rainfall scenarios. Cattle slurry was applied to the top 1 metre strip of the experimental soil slope followed by four rainfall simulations, where the gradient (5° & 10°) and the rainfall intensity (60 & 120 mm hr-1) were co-varied. Leachate was sampled from different flow pathways (surface, subsurface and percolated) via multiple outlets on the slope throughout the experiments and soil cores were taken from the slope after each experiment. Novel tracers were used to trace the pollutants in both dissolved and sediment-bound forms. Fluorescence spectroscopy was used to trace dissolved slurry-derived material via water flow pathways, as the slurry was found to have a distinct signature compared with the soil. The fluorescence signatures of the leachates were compared with those of many organic compounds in order to characterise the origin of the signal. This allowed the assessment of the longevity of the signal in the environment to establish if it could be used as a robust long-term tracer of slurry material in water or if would be subject to transform processes through time. 5-βstanols, organic compounds unique to ruminant faeces, were used to trace the transport of sediment-bound pollutants from the slurry which could be transported into water bodies via erosion processes. The results showed that contributions of potential pollutants from the surface and subsurface flow pathways and from the eroded sediment differ according to slope gradient and rainfall intensity. Therefore, as the contribution of each of these pathways changes in response to rainfall and slope gradient, the pollution risk also changes accordingly, as different organic compounds are mobilised at varying rates. Rapid hydrological response to rainfall results in erosion and surface transport of sediment-bound and dissolved pollutants, creating an immediate contamination threat. However, conditions resulting in a slower hydrological response and the predominance of flow percolation over surface runoff results in higher rates of dissolved pollutant transport through the soil layers which risks contamination of subsurface and deeper ground-water systems. These experiments provide insight into the pathways and timing of contaminant transport with potential implications for understanding contamination risk from the transfer of slurry from land to water bodies. Understanding this threat is critical at a time when pressure is on to develop land-management strategies to reduce pollution alongside maintaining food security.

Risk of the residents, infrastructure and water bodies by flash floods and sediment transport - assessment for scale of the Czech Republic

NASA Astrophysics Data System (ADS)

Dostál, Tomáš; Krása, Josef; Bauer, Miroslav; Strouhal, Luděk; Jáchymová, Barbora; Devátý, Jan; David, Václav; Koudelka, Petr; Dočkal, Martin

2015-04-01

Pluvial and flash floods, related to massive sediment transport become phenomenon nowadays, under conditions of climate changes. Storm events, related to material damages appear at unexpected places and their effective control is only possible in form of prevention. To apply preventive measures, there have to be defined localities with reasonable reliability, which are endangered by surface runoff and sediment transport produced in the subcatchments, often at agriculturally used landscape. Classification of such localities, concerning of potential damages and magnitude of sediment transport shall be also included within the analyses, to design control measures effectively. Large scale project for whole territory of the Czech Republic (ca 80.000 km2) has therefore been granted b the Ministry of Interior of the Czech Republic, with the aim to define critical points, where interaction between surface runoff connected to massive sediment transport and infrastructure or vulnerable water bodies can occur and to classify them according to potential risk. Advanced GIS routines, based on analyses of land use, soil conditions and morphology had been used to determine the critical points - points, where significant surface runoff occurs and interacts with infrastructure and vulnerable water bodies, based exclusively on the contributing area - flow accumulation. In total, ca 150.000 critical points were determined within the Czech Republic. For each of critical points, its subcatchment had then been analyzed in detail, concerning of soil loss and sediment transport, using simulation model WATEM/SEDEM. The results were used for classification of potential risk of individual critical points, based on mean soil loss within subcatchment, total sediment transport trough the outlet point and subcatchment area. The classification has been done into 5 classes. The boundaries were determined by calibration survey and statistical analysis, performed at three experimental catchments area of 100 km2 each. Concentrated flow trajectory had then been analyzed trough urban areas and potential vulnerability of incident structures has been determined. Total hazard of infrastructure has been classified again into 5 categories for each individual critical point using risk matrix, combining threat and vulnerability features. Generalized control measures (changes in land-use, changes in agrotechnology, diverting linear measures or retention structures) were then introduced into mathematical model WATEM/SEDEM in number of scenarios, to allow effective design of control measures against surface runoff and sediment transport for each individual critical point. Result of the project will be public available by WEB application and shall be useful for government, local decision makers, for planning of development of communities and also optimization of effective design of flash floods control measures. The research has been supported by the research project VG20122015092.

Runoff losses of sediment and phosphorus from no-till and cultivated soils receiving dairy manure.

PubMed

Verbree, David A; Duiker, Sjoerd W; Kleinman, Peter J A

2010-01-01

Managing manure in no-till systems is a water quality concern because surface application of manure can enrich runoff with dissolved phosphorus (P), and incorporation by tillage increases particulate P loss. This study compared runoff from well-drained and somewhat poorly drained soils under corn (Zea mays, L.) production that had been in no-till for more than 10 yr. Dairy cattle (Bos taurus L.) manure was broadcast into a fall planted cover crop before no-till corn planting or incorporated by chisel/disk tillage in the absence of a cover crop. Rainfall simulations (60 mm h(-1)) were performed after planting, mid-season, and post-harvest in 2007 and 2008. In both years and on both soils, no-till yielded significantly less sediment than did chisel/disking. Relative effects of tillage on runoff and P loss differed with soil. On the well-drained soil, runoff depths from no-till were much lower than with chisel/disking, producing significantly lower total P loads (22-50% less). On the somewhat poorly drained soil, there was little to no reduction in runoff depth with no-till, and total P loads were significantly greater than with chisel/disking (40-47% greater). Particulate P losses outweighed dissolved P losses as the major concern on the well-drained soil, whereas dissolved P from surface applied manure was more important on the somewhat poorly drained soil. This study confirms the benefit of no-till to erosion and total P runoff control on well-drained soils but highlights trade-offs in no-till management on somewhat poorly drained soils where the absence of manure incorporation can exacerbate total P losses.

Amending soils with sediment material from constructed wetlands increases phosphorus sorption

NASA Astrophysics Data System (ADS)

Laakso, Johanna; Uusitalo, Risto; Leppänen, Janette; Yli-Halla, Markku

2017-04-01

Sediment of agricultural constructed wetlands (CWs) is comprised of matter eroded from surrounding fields. This material is rich in aluminium (Al) and iron (Fe) (hydr)oxides that have a high affinity for phosphorus (P). Sediment material returned to fields could therefore affect soil P retention characteristics. We incubated a clay soil with a high soil test P (STP, 24 mg PAc l-1; extracted with pH 4.65 ammonium acetate buffer) and a sandy loam with excessive STP (210 mg PAc l-1) for three weeks with increasing amounts of CW sediment: 0, 2, 5, 10 and 50% of the sample volume. After incubation, the soil-sediment mixtures were studied with the quantity/intensity (Q/I) technique, using chemical extractions and by exposing the mixtures to simulated rainfall. Sorption affinity for P regularly increased with increasing the sediment share of the mixtures, the 0% sediment content having the lowest and 50% sediment content the highest P sorption. With 0% sediment application, the value of equilibrium P concentration (EPC0) determined by Q/I technique, was 0.69 and 44.3 mg l-1 for clay soil and sandy loam, respectively. With 2-5% sediment amendment, the EPC0 decreased 13-36% for clay soil and 13-54% for sandy loam. The 50% sediment mixtures had EPC0 of 0.05 mg l-1 for both soils. At a practically feasible sediment addition rate of 5%, dissolved reactive P (DRP) in percolating water from simulated rainfall decreased by 55% in the clay soil and 54% in sandy loam (p<0.001 in both cases). Particulate-P (PP) also showed a decreasing trend with increasing sediment addition rate. Upon prolonged simulated rainfall, the decreasing effect of sediment on DRP and PP declined somewhat. The effects of sediment addition can be attributed partly to increased salt concentrations in the sediment, which have a short-term effect on P mobilisation, but mostly to increased concentrations of Al and Fe (hydr)oxides, increasing long-term P sorption capacity. Amending the soils with sediment material would decrease P solubility and might at large application rates hamper P uptake by plants or, on the other hand, the sediment amendment in the soil might reduce P losses by runoff.

Evaluation of current techniques for isolation of chars as natural adsorbents

USGS Publications Warehouse

Chun, Y.; Sheng, G.; Chiou, C.T.

2004-01-01

Chars in soils or sediments may potentially influence the soil/sediment sorption behavior. Current techniques for the isolation of black carbon including chars rely often on acid demineralization, base extraction, and chemical oxidation to remove salts and minerals, humic acid, and refractory kerogen, respectively. Little is known about the potential effects of these chemical processes on the char surface and adsorptive properties. This study examined the effects of acid demineralization, base extraction, and acidic Cr2O72- oxidation on the surface areas, surface acidity, and benzene adsorption characteristics of laboratory-produced pinewood and wheat-residue chars, pure or mixed with soils, and a commercial activated carbon. Demineralization resulted in a small reduction in the char surface area, whereas base extraction showed no obvious effect. Neither demineralization nor base extraction caused an appreciable variation in benzene adsorption and presumably the char surface properties. By contrast, the Cr2O 72- oxidation caused a >31% reduction in char surface area. The Boehm titration, supplemented by FTIR spectra, indicated that the surface acidity of oxidized chars increased by a factor between 2.3 and 12 compared to nonoxidized chars. Benzene adsorption with the oxidized chars was lower than that with the non-oxidized chars by a factor of >8.9; both the decrease in char surface area and the increase in char surface acidity contributed to the reduction in char adsorptive power. Although the Cr 2O72- oxidation effectively removes resistant kerogen, it is not well suited for the isolation of chars as contaminant adsorbents because of its destructive nature. Alternative nondestructive techniques that preserve the char surface properties and effectively remove kerogen must be sought.

Erosion measurements at various scales in a semi arid mountainous catchment - case of the Rheraya watershed, High Atlas, Morocco

NASA Astrophysics Data System (ADS)

Cheggour, A.; Simonneaux, V.; Roose, E.

2009-04-01

Erosion is a critical phenomenon in North Africa, under the combined effects of aggressive rainfall and soil fragility, increased by the grazing pressure on rangelands. However measurements of actual erosion rates are rare, especially in mountainous areas. Siltation of dams is estimated at more than 60 million m3 annually in Morocco, which corresponds to a decrease of 0.5% of the storage capacity. The Rheraya watershed (225 km2) is located in a semi-arid climat, in the High Atlas of Morocco. In order to assess erosion processes at various scales, three types of measurements were achieved on this area, namely rainfall simulation tests one square meter, erosion plots on 150 m2, and catchment's discharge and associated sediments measurements. Rainfall simulation experiments were achieved on 27 sites, measuring runoff and sediment charge. The turbidity was correctly measured thanks to the development of a new runoff collector which doesn't disturb the soil. In the scope of spatial extrapolation, we searched for indicators obtained from ground description variables and/or by laboratory tests on soil samples, which were well correlated with infiltration and turbidity of the simulations. For the various soils present in the study area, the results show a large variability of infiltration (from 1 to 70 mm h-1) and turbidity (from 3 to 325 g.l-1). Analysis showed that infiltration is correlated mainly with texture and soil surface opening, and that turbidity is related to the surface of bare soil exposed to runoff. Six erosion plots of about 150 m2, located on various soil and land cover conditions, were measured during four years. The observations showed very rare runoff events in the main part of the watershed, producing a low sediment load (between 0.015 and 2.5 t.ha1.year1). Conversely, runoff was much more frequent on silty badlands, producing about 95% of the watershed sediment (350 t.ha-1.year-1) despite their area was only 1% of the watershed. There was a significant linear relation between simulation turbidity and erosion plot turbidity. However, there was a great difference between infiltration estimates from the two types of measurements. Plot infiltrations estimates were only between 3 and 5 mm/h, but they were significantly correlated to the one from test, through an exponential relation. Finally, an estimate of the overall erosion at catchment's scale was achieved from plots values extrapolated using a soil map, and gave about 3 to 4 t.ha-1.year-1. A good correlation was found between this watershed scale estimate and the catchment's exportation, indirectly validating the significance of both measurements. Moreover, both estimates were about the same, showing a sediment delivery ratio around one. Keywords: erosion, rainfall simulation, erosion plot, sediment exportation

In situ burning of oil in coastal marshes. 1. Vegetation recovery and soil temperature as a function of water depth, oil type, and marsh type.

PubMed

Lin, Qianxin; Mendelssohn, Irving A; Bryner, Nelson P; Walton, William D

2005-03-15

In-situ burning of oiled wetlands potentially provides a cleanup technique that is generally consistent with present wetland management procedures. The effects of water depth (+10, +2, and -2 cm), oil type (crude and diesel), and oil penetration of sediment before the burn on the relationship between vegetation recovery and soil temperature for three coastal marsh types were investigated. The water depth over the soil surface during in-situ burning was a key factor controlling marsh plant recovery. Both the 10- and 2-cm water depths were sufficient to protect marsh vegetation from burning impacts, with surface soil temperatures of <35 and 48 degrees C, respectively. Plant survival rate and growth responses at these water depth burns were not significantly different from the unburned control. In contrast, a water table 2 cm below the soil surface during the burn resulted in high soil temperatures, with 90-200 degrees C at 0-0.5 cm soil depth and 55-75 degrees C at 1-2 cm soil depth. The 2-cm soil exposure to fire significantly impeded the post-burn recovery of Spartina alterniflora and Sagittaria lancifolia but did not detrimentally affect the recovery of Spartina patens and Distichlis spicata. Oil type (crude vs diesel) and oil applied to the marsh soil surface (0.5 L x m(-2)) before the burn did not significantly affect plant recovery. Thus, recovery is species-specific when no surface water exists. Even water at the soil surface will most likely protect wetland plants from burning impact.

The influence of copper-based fungicide use in soils and aquatic sediments. Case study: Aetoliko lagoon, Western Greece

NASA Astrophysics Data System (ADS)

Avramidis, Pavlos; Barouchas, Pantelis; Dünwald, Thomas; Unkel, Ingmar

2017-04-01

In the study area, in order farmers to keep their olive trees healthy, the first measure is to keep their olive trees well-fed that is the best initial defense against diseases. Copper-based fungicides are the most common fungicides to protect olive plantations against diseases such as the olive leaf spot. Pathogens are controlled by farmers with strategically timed disease control programs rely on copper sprays to protect the foliage and fruit from infection Successful disease control depends on even distribution and good retention of the copper over all of the plant surfaces before the disease develops. Artificially added copper has the ability to accumulate in soils and aquatic sediments and can cause adverse effects on flora and fauna in its environment. For the present study soil and aquatic sediments field campaign was carried out in the Aetoliko Lagoon ecosystem which is exclusively dominated by olive orchards. It is for the first time in Greece that soil as well as aquatic sediments samples of one coherent protected aquatic ecosystem were taken and compared. To determine the influence that the usage of copper-based fungicides have on the lagoon and surrounding areas, ten (10) sediment samples from the bottom of the lagoon and twenty five (25) soil samples at the different olive orchards that are bordering the water body were taken. The samples were analyzed for total copper content (total digestion) and extractable copper (DTPA and NH4NO3). Furthermore, soil / sedimentological and geochemical analyses such as pH, grain size, total organic carbon, total nitrogen and calcium carbonate content were carried out. The results show in over 80 % of the orchard soils a critical accumulation of the total amount of copper. In some of the examined soils the value of 140 mg/kg(as set by the European Union as a limit for total copper in farmland) is exceeded by the factors of 2 to 4.5. Copper content in the aquatic sediments is generally lower and varies between 43.85 mg/kg and 71.87 mg/kg. The values for DTPA-extractable copper are relatively very low, while the highest fractions of bioavailable copper are found on the eastern shore of the lagoon. Our study can be used as a valuable reference for future studies on this subject at the Aetoliko lagoon and similar ecosystems.

Modelling soil erosion and associated sediment yield for small headwater catchments of the Daugava spillway valley, Latvia

NASA Astrophysics Data System (ADS)

Soms, Juris

2015-04-01

The accelerated soil erosion by water and associated fine sediment transfer in river catchments has various negative environmental as well as economic implications in many EU countries. Hence, the scientific community had recognized and ranked soil erosion among other environmental problems. Moreover, these matters might worsen in the near future in the countries of the Baltic Region, e.g. Latvia considering the predicted climate changes - more precisely, the increase in precipitation and shortening of return periods of extreme rainfall events, which in their turn will enable formation of surface runoff, erosion and increase of sediment delivery to receiving streams. Thereby it is essential to carry out studies focused on these issues in order to obtain reliable data in terms of both scientific and applied aims, e.g. environmental protection and sustainable management of soils as well as water resources. During the past decades, many of such studies of soil erosion had focused on the application of modelling techniques implemented in a GIS environment, allowing indirectly to estimate the potential soil losses and to quantify related sediment yield. According to research results published in the scientific literature, this approach currently is widely used all over the world, and most of these studies are based on the USLE model and its revised and modified versions. Considering that, the aim of this research was to estimate soil erosion rates and sediment transport under different hydro-climatic conditions in south-eastern Latvia by application of GIS-based modelling. For research purposes, empirical RUSLE model and ArcGIS software were applied, and five headwater catchments were chosen as model territories. The selected catchments with different land use are located in the Daugava spillway valley, which belongs to the upper Daugava River drainage basin. Considering lithological diversity of Quaternary deposits, a variety of soils can be identified, i.e., Stagnic Albeluvisols, Albic Rubic Arenosols and Albic Stagnic Podzols with stony loamy - clayey diamicton to coarse sand textures prevail in the selected catchments. The results of modelling were validated through obtaining data on suspended sediment load directly during episodic runoff events caused by different scenarios of runoff formation. In order to get comparable values of suspended sediment load from gully catchments that differ in size, an area-specific daily suspended sediment yield was derived. The obtained results indicate that modelled area-specific sediment yield from the catchments to river greatly varies from 0.001 to 97.2 t ha-1 yr-1; the average soil loss predicted by RUSLE for the each of five catchments calculated for a 1 × 1 m cell grid totals 0.81; 1.36; 0.96; 1.05 and 1.55 t ha-1 yr-1 respectively. Notably, despite the presence of forest vegetation that cover more than 40% of area of three of these catchments, sizable plots of soils are potentially prone to erosion rates above the tolerable threshold, i.e. 0.3 t ha-1 yr-1. Comparison of modelled vs. measured values indicates that the applied RUSLE model underestimates real sediment delivery, which shortly can reach values 213.75 kg ha-1 day-1 during intense snow melting in spring. Nevertheless, results of GIS modelling can be reasonably used to estimate the spatial distribution of soil erosion risk and to identify potential erosion hotspots.

Quality of water and chemistry of bottom sediment in the Rillito Creek basin, Tucson, Arizona, 1992-93

USGS Publications Warehouse

Tadayon, Saeid

1995-01-01

Physical and chemical data were collected from four surface-water sites, six ground-water sites, and two bottom-sediment sites during 1992-93. Specific conductance, hardness, alkalinity, and dissolved- solids concentrations generally were higher in ground water than in surface water. The median concentrations of dissolved major ions, with the exception of potassium, were higher in ground water than in surface water. In surface water and ground water, calcium was the dominant cation, and bicarbonate was the dominant anion. Concentrations of dissolved nitrite and nitrite plus nitrate in surface water and ground water did not exceed the U.S. Environmental Protection Agency maximum contaminant levels of 1 and 10 milligrams per liter for drinking water, respectively. Ammonium plus organic nitrogen in bottom sediment was detected at the highest concentration of any nitrogen species. Median values for most of the dissolved trace elements in surface water and ground water were below the detection levels. Dissolved trace elements in surface water and ground water did not exceed the U.S. Environmental Protection Agency maximum contaminant levels for drinking water. Trace-element concentrations in bottom sediment were similar to trace-element concentrations reported for soils of the western conterminous United States. Several organochlorine pesticides and priority pollutants were detected in surface-water and bottom-sediment samples; however, they did not exceed water-quality standards. Pesticides or priority pollutants were not detected in ground-water samples.

Beryllium-7 in vegetation, soil, sediment and runoff on the northern Loess Plateau.

PubMed

Zhang, Fengbao; Yang, Mingyi; Zhang, Jiaqiong

2018-06-01

Beryllium-7 ( 7 Be), as a potentially powerful tracer, was widely used to document soil redistribution and identify sediment sources in recent decades, but the quantity and distribution of 7 Be in vegetation, soil, sediment and runoff on the Loess Plateau have not been fully described. In this study, we measured 7 Be in vegetation, soil, sediment and runoff on the northern Loess Plateau of China and analyzed its variations during the rainy season to assess the potential of the 7 Be method for documenting soil redistribution and identifying sediment sources in a wide range of environments. The results indicated that vegetation, soil, and sediment samples showed higher levels and larger variations of 7 Be activities during the rainy season. The drying plants showed 7 Be mass activity that was more than three times higher than that of living and semi-decomposed plants. 7 Be mass activity in plants and sediment was much higher than in the soil. 7 Be activity in runoff water with a few submicron suspended particles varied slightly and was far lower than in plant, soil and sediment samples. The cumulative precipitation generally determined 7 Be inventory held by plants and soil. An inverse relationship was found between the 7 Be mass activity in sediment and the sediment amount. Globally, approximate 30% of the total 7 Be was held by plants in both the herbaceous and subshrub plots. Approximate 10% of the total 7 Be was lost with sediment from the bare plot. A very small proportion of 7 Be (1.18%-3.20%) was lost with runoff, and the vast majority of 7 Be was retained in the slope soil at the end of rainy season. Vegetation cover and soil erosion significantly affected the spatial distribution and variations of the 7 Be inventory in soil, providing a necessary condition for the development of a 7 Be method to document soil erosion on slopes with vegetation. Copyright © 2018 Elsevier B.V. All rights reserved.

Soil characteristics of sediment-amended baldcypress (Taxodium distichum) swamps of coastal Louisiana

USGS Publications Warehouse

Jiang, Ming; Middleton, Beth A.

2011-01-01

Amendments of sediment from dredging activities have played an important role in raising the elevation of sinking coastal wetlands. This study compared the soil characteristics of sediment- amended coastal swamps in the Barataria Preserve unit of Jean Lafitte National Historical Park and Preserve with natural swamps along Bayou des Familles. The sandy sediment amendments used in the coastal forests had different soil texture and characteristics than the more organic soils of the natural swamps. Three years after the application of these sediments on the sediment-amended swamps, dewatering and compaction of the sediment had occurred but the sediment still had high salinity and bulk density, and low organic matter content. The two sediment-amended swamps differed from each other in that Site 1 had a higher elevation (mean = 25 cm higher) and drier soil than Site 2. The effects of sediment in coastal forested wetlands require separate consideration from studies of salt marshes, e.g., the weight of the sediment might damage tree roots, or the amendments might influence soil stability during storms in a different way. Generally, this study suggests that shallower depths of sediment are more likely to yield environments beneficial to these sinking baldcypress swamps in coastal Louisiana.

The influence of particles recycling on the geochemistry of sediments in a large tropical dam lake in the Amazonian region, Brazil

NASA Astrophysics Data System (ADS)

Fonseca, Rita; Pinho, Catarina; Oliveira, Manuela

2016-12-01

As a result of over-erosion of soils, the fine particles, which contain the majority of nutrients, are easily washed away from soils, which become deficient in a host of components, accumulating in lakes. On one hand, the accumulation of nutrients-rich sediments are a problem, as they affect the quality of the overlying water and decrease the water storage capacity of the system; on the other hand, sediments may constitute an important resource, as they are often extremely rich in organic and inorganic nutrients in readily available forms. In the framework of an extensive work on the use of rock related materials to enhance the fertility of impoverish soils, this study aimed to evaluate the role on the nutrients cycle, of particles recycling processes from the watershed to the bottom of a large dam reservoir, at a wet tropical region under high weathering conditions. The study focus on the mineralogical transformations that clay particles undergo from the soils of the drainage basin to their final deposition within the reservoir and their influence in terms of the geochemical characteristics of sediments. We studied the bottom sediments that accumulate in two distinct seasonal periods in Tucuruí reservoir, located in the Amazonian Basin, Brazil, and soils from its drainage basin. The surface layers of sediments in twenty sampling points with variable depths, are representative of the different morphological sections of the reservoir. Nineteen soil samples, representing the main soil classes, were collected near the margins of the reservoir. Sediments and soils were subjected to the same array of physical, mineralogical and geochemical analyses: (1) texture, (2) characterization and semi-quantification of the clay fraction mineralogy and (3) geochemical analysis of the total concentration of major elements, organic compounds (organic C and nitrogen), soluble fractions of nutrients (P and K), exchangeable fractions (cation exchange capacity, exchangeable bases and acidity) and pH(H2O). There is a remarkable homogeneity in the sedimentary distribution along the reservoir in terms of the texture and mineralogy of the clay fraction and of the chemistry of the total, soluble and exchangeable phases. These observations contrast with the physical, morphological and chemical heterogeneity of the soils and the setting lithology. Most of the sediments has a higher contribution of fine-grained material and the mineralogy of the clay fraction is dominated by kaolinite in soils and kaolinite and illite in sediments, followed by lesser amounts of gibbsite, goethite, and metahaloisite and by small/vestigial contents of chlorite and smectite. The sediments are mainly inherited from the watershed but there exist marked differences between the accumulated sediments and their parent materials. These differences mainly come from the selective erosion of fine-grained particles and the extreme climatic conditions which enhance complex transformations of mineralogical and chemical nature. Compared with the parental soils, the reservoir sediments show the following differences: (1) enrichment in fine-grained and less dense inorganic particles, (2) aggradative mineralogical transformations, including enrichment in clay minerals with higher cationic adsorption and exchange capacity, (3) degradation of the crystalline structure of Fe- and Al-oxides (goethite, gibbsite), (4) increase in easily leached elements (Mg, Ca, P, K, Na) and decrease in chemically less mobile elements (Si, Fe) and (5) higher contents of organic carbon, nitrogen, and soluble forms of P and K, mainly concentrated in the clay fraction. These transformations are extremely important in the nutrients cycle, denoting that sediments represent an efficient sink for nutrients from the over-erosion of soils. Mineral and organic compounds can permanently or temporarily sequester these nutrients, recycling them and enhancing their availability through the slow release of components from relatively loose crystal structures. These processes can easily explain the enrichment in soluble and exchangeable forms of elements such as P, K, Ca or Mg. This study conclude that the particles recycling in a large tropical dam reservoir which receives high fluxes of allochthonous nutrients, has an important role in the good quality of sediments for agricultural use and in the profitable use of this technology to recover depleted soils in remediation projects in regions near large hydroelectric plants.

Urbanization Effects on Floodplain Sediments in the Fourche Creek Wetlands in Little Rock, Arkansas, United States

NASA Astrophysics Data System (ADS)

Simmons, J.; Ruhl, L. S.

2017-12-01

Jason Simmons and Laura S. Ruhl As Earth's population continues to grow, is it expected that by the year 2030, sixty percent of all people will be housed in urban cities. Although these urban areas are of the utmost importance socially, culturally and economically, they also have an adverse impact on the geochemical makeup of the natural landscape. Rapid urbanization has profound hydrological, chemical, physical, and ecological impacts on watersheds near urban areas. Trace metals, and other organic and inorganic contaminants from industrialization, car exhaust, overflow of sewage lines, and excess storm drain runoff are found in this surface water. In Little Rock, Arkansas, runoff from seventy-three percent of the city's surface area empties into Fourche Creek, then its urban wetlands, before it is further transported to the Arkansas River. Previous studies have revealed that the Fourche Creek wetlands mitigate flooding and remove contaminants from the water column. In this study, we examined the effects of urbanization by examining the geochemical makeup of the wetland sediment that drains most of Little Rock. Sediment samples were collected along transects of Fourche Creek at three locations, beginning at the water's edge and moving out distances between seventy to one hundred feet into the wetland. Sediments were dried, homogenized, and then sieved for grain size distribution. Leaching experiments were performed to determine the trace element concentration adsorbed to the surface, which could be easily mobilized. In these experiments, ultrapure deionized water and homogenized soil were combined in centrifuge tubes at a 10:1 liquid to solid ratio, and rotated for twenty-four hours allowing the mixture to properly combine and react. The leachate was filtered, then analyzed using Ion Chromatography (IC) to determine cations and anions, and ICPMS to determine trace metals present in the soil. Results were compiled, and a map was created showing grain sizes present, and metal distribution in the wetland soil. Results of this research were used to compare metal concentrations present in the Fourche Creek wetlands with those of a background non-urban soil, as well as determine the enrichment factors of those constituents related to anthropogenic activity (heavy metals).

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips - Part 2: model coupling, application, factor importance, and uncertainty

NASA Astrophysics Data System (ADS)

Lauvernet, Claire; Muñoz-Carpena, Rafael

2018-01-01

Vegetative filter strips are often used for protecting surface waters from pollution transferred by surface runoff in agricultural watersheds. In Europe, they are often prescribed along the stream banks, where a seasonal shallow water table (WT) could decrease the buffer zone efficiency. In spite of this potentially important effect, there are no systematic experimental or theoretical studies on the effect of this soil boundary condition on the VFS efficiency. In the companion paper (Muñoz-Carpena et al., 2018), we developed a physically based numerical algorithm (SWINGO) that allows the representation of soil infiltration with a shallow water table. Here we present the dynamic coupling of SWINGO with VFSMOD, an overland flow and transport mathematical model to study the WT influence on VFS efficiency in terms of reductions of overland flow, sediment, and pesticide transport. This new version of VFSMOD was applied to two contrasted benchmark field studies in France (sandy-loam soil in a Mediterranean semicontinental climate, and silty clay in a temperate oceanic climate), where limited testing of the model with field data on one of the sites showed promising results. The application showed that for the conditions of the studies, VFS efficiency decreases markedly when the water table is 0 to 1.5 m from the surface. In order to evaluate the relative importance of WT among other input factors controlling VFS efficiency, global sensitivity and uncertainty analysis (GSA) was applied on the benchmark studies. The most important factors found for VFS overland flow reduction were saturated hydraulic conductivity and WT depth, added to sediment characteristics and VFS dimensions for sediment and pesticide reductions. The relative importance of WT varied as a function of soil type (most important at the silty-clay soil) and hydraulic loading (rainfall + incoming runoff) at each site. The presence of WT introduced more complex responses dominated by strong interactions in the modeled system response, reducing the typical predominance of saturated hydraulic conductivity on infiltration under deep water table conditions. This study demonstrates that when present, the WT should be considered as a key hydrologic factor in buffer design and evaluation as a water quality mitigation practice.

75 FR 4106 - Notice of Lodging of Consent Decree Under the Comprehensive Environmental Response, Compensation...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-26

..., the remedy chosen for the soils and sediments was failing to clean the soils and sediments up to the required performance standards. EPA issued an Amended Record of Decision for the soils and sediments... then became necessary to amend the 1998 Decree to include the revised soils and sediment cleanup under...

Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils.

PubMed

Guimarães, J R; Meili, M; Hylander, L D; de Castro e Silva, E; Roulet, M; Mauro, J B; de Lemos, R

2000-10-16

In aquatic systems, bottom sediments have often been considered as the main methylmercury (MeHg) production site. In tropical floodplain areas, however, floating meadows and flooded forests extend over large areas and can be important Hg methylating sites. We present here a cross-system comparison of the Hg net methylation capacity in surface sediments, flooded soils and roots of floating aquatic macrophytes, assayed by in situ incubation with 203Hg and extraction of formed Me203 Hg by acid leaching and toluene. The presence of mono-MeHg was confirmed by thin layer chromatography and other techniques. Study areas included floodplain lakes in the Amazon basin (Tapajós, Negro and Amazon rivers), the Pantanal floodplain (Paraguay river basin), freshwater coastal lagoons in Rio de Janeiro and oxbow lakes in the Mogi-Guaçú river, São Paulo state. Different Hg levels were added in assays performed in 1994-1998, but great care was taken to standardise all other test parameters, to allow data comparisons. Net MeHg production was one order of magnitude higher (mean 13.8%, range 0.28-35) in the living or decomposing roots of floating or rooted macrophyte mats (Eichhornia azurea, E. crassipes, Paspalum sp., Eleocharis sellowiana, Salvinia sp., S. rotundifolia and Scirpus cubensis) than in the surface layer of underlying lake sediments (mean 0.6%, range 0.022-2.5). Methylation in flooded soils presented a wide range and was in some cases similar to the one found in macrophyte roots but usually much lower. In a Tapajós floodplain lake, natural concentrations of MeHg in soil and sediment cores taken along a lake-forest transect agreed well with data on net methylation potentials in the same samples. E. azurea, E. crassipes and Salvinia presented the highest methylation potentials, up to 113 times higher than in sediments. Methylation in E. azurea from six lakes of the Paraguay and Cuiabá rivers, high Pantanal, was determined in the 1998 dry and wet seasons and ranged from 1.8 to 35%. Methylation was lower in washed roots than in untreated roots of E. azurea and methylation in solids isolated from the roots, was higher than in sediments but lower than in untreated roots. This indicates that the methylation in roots zones occurs mainly in the root-associated solids. Floating meadows are sites of intense production of biomass and of highly bioavailable MeHg and appear to be an essential link of the MeHg cycle in tropical aquatic systems.

Sources and characteristics of organochlorine pesticides in the soil and sediment along the Kaidu-Peacock River, Northwest of China

NASA Astrophysics Data System (ADS)

Chen, Wei; Qi, Shihua; Peng, Fei; Qu, Chengkai; Zhang, Yuan; Xing, Xinli; Zhang, Jiaquan

2016-04-01

Organochlorine pesticides (OCPs) are a sub-group of persistent organic pollutants (POPs), which have raised the concerns from researchers all around the world for several decades. But very little research has been conducted on POPs in the arid zone of Northwest China. More than 100 soil and sediment samples were collected from Kaidu-Peacock River of Xinjiang, Northwest of China, to investigate the organochlorine pesticides (OCPs) in this region analysed by the gas chromatograph equipped with a mass selective detector (GC-MSD). Our pre-study in 2006 (Chen et al. 2011) in the same region, showed that OCPs except o,p'-DDT were detected in sediments from the Peacock River. Similar results were found in the whole river catchment in this investigation. DDTs, HCHs, chlordanes and endosulfans were the dominant OCPs residual in the soil and sediments. This study confirmed that POPs, such as OCPs in this region were contributed to by both local emissions and long-term atmospheric transport and may pose risks to human health and the ecosystem. Chen, W., Jing, M., Bu, J., Ellis Burnet, J., Qi, S., Song, Q., Ke, Y., Miao, J., Liu, M. & Yang, C. (2011) Organochlorine pesticides in the surface water and sediments from the Peacock River Drainage Basin in Xinjiang, China: a study of an arid zone in Central Asia. Environmental Monitoring and Assessment, 177, 1-21.

PHYTOTECHNOLOGIES IN THE UNITED STATES: GROWING SOLUTIONS TO ENVIRONMENTAL CHALLENGES

EPA Science Inventory

Phytotechnology may be defined as the use of plants to contain, sequester, remove, or degrade organic and inorganic contaminants in soils, sediments, surface water, and groundwater. Mechanisms employed by the plant community may include transpiration (phytovolatilization), plant...

The Effect on Soil Erosion of Different Tillage Applications

NASA Astrophysics Data System (ADS)

Gür, Kazım

2016-04-01

The Effects on Soil Erosion of Different Tillage Applications Kazım Gür1, Kazim Çarman2 and Wim M.Cornelis3 1Bahri Daǧdaş International Agricultural Research Instıtute, 42020 Konya, Turkey 2Faculty of Agriculture, Department of Agricultural Machinery, University of Selçuk, 42031 Konya, Turkey 3Department of Soil Management, Faculty of Bioscience Engineering, Ghent University, 653 Coupure Links, 9000 Gent, Belgium Traditional soil cultivation systems, with excessive and inappropriate soil tillage, will generally lead to soil degradation and loss of soil by wind erosion. Continuous reduced tillage and no-till maintaining soil cover with plant residues called Conservation Agriculture that is considered as effective in reducing erosion. There exist a wide variety of practices using different tools that comply with reduced tillage principles. However, few studies have compared the effect of several of such tools in reducing wind erosion and related soil and surface properties. We therefore measured sediment transport rates over bare soil surfaces (but with under stubbles of wheat, Triticum aestivum L.) subjected to three tillage practices using two pulling type machines and one type of power takeoff movable machines and generated with a portable field wind tunnel. At 10 ms-1, sediment transport rates varied from 107 to 573 gm-1h-1, and from 176 to 768 gm-1h-1 at 13 ms-1. The lowest transport rates were observed for N(no-tillage) and the highest for Rr(L-type rototiller). After tillage, surface roughness, mean weighted diameter, wind erodible fraction, mechanical stability and soil water content were measured as well and varied from 5.0 to 15.9%, 6.9 to 13.8 mm, 14.3 to 29.7%, 79.5 to 93.4% and 8.6 to 15.1%, respectively, with again N is being the most successful practice. In terms of conservation soil tillage technique, it can be said that the applications compared with each other; direct sowing machine is more appropriate and cause to the less erosion.

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.

Postfire soil erosion processes are conditioned by aridity

NASA Astrophysics Data System (ADS)

Jordán, Antonio; Zavala, Lorena M.; Gordillo-Rivero, Ángel J.; Muñoz-Rojas, Miriam; Keesstra, Saskia; Cerdà, Artemi

2017-04-01

In this work we have studied the runoff and rate of erosion in severely burnt Mediterranean shrublands of southern Spain by simulating high intensity rainfall over a period of 5 years. We have also observed temporal changes in soil surface properties (0-10 mm) of two scrub areas in different years. In both cases, surface runoff increased appreciably during the first year after the fire, compared to burning bushes in more rainy areas. Although differences in the rate of infiltration (determined by a mini-disk infiltrometer with ethanol, to avoid the effect of hydrophobicity) were observed, the increase in the rate of runoff was related to the increase of water repellency in the first millimeters of the soil surface, regardless of other physical properties (texture or percentage of rock fragments), chemical (acidity, organic matter content) or fire severity. Sediment loss was also exceptionally high during the first year. Then, runoff and soil loss rates were progressively approaching the values observed in the control zones. However, most of the physical and chemical properties of the soil after the fire did not change during the post-fire period, suggesting erosion of sediment depletion. No large differences were observed between the study points along the precipitation gradient, suggesting that, independently of this and other factors, the impact of high severity fires can be long over time. Although other authors have shown that relatively small changes in aridity have great impacts on erosion processes, this does not seem to be valid in the case of high severity fires in Mediterranean areas.

The relationship between land use and organochlorine compounds in streambed sediment and fish in the Central Columbia Plateau, Washington and Idaho, USA

USGS Publications Warehouse

Munn, M.D.; Gruber, S.J.

1997-01-01

We analyzeds streambed sediment and fish in the Central Columbia Plateau in eastern Washington and Idaho for or ganochlorine pesticides and polychlorinated biphenyls (ΣPCB). Our objective was to assess the effects of land use on the occurrence and distribution of these compounds; land uses in the study area included forest, dryland and irrigated farming, and urban. We detected 16 organochlorine compounds in streambed sediment and fish tissue; fish usually had more compounds and a greater frequency of detection. The most frequently detected compound was ΣDDT (sum of six isomers), which was found in 52% of bed sediment samples and 94% of whole fish composite samples. The other commonly detected compounds were dimethyl tetrachloroterephthalate (DCPA), dieldrin, hexachlorobenzene, and Σchlordane (sum of cis- and trans-chlordane, cis- and trans-nonachlor oxychlordane, heptachlor, and heptachlor epoxide). Forest was the only land use with no detections of organochlorine compounds in either fish or bed sediment. Hexachlorobenzene was the only organochlorine pesticide detected at concentrations that differed significantly among land uses: concentrations were higher in the dryland farming areas than in the irrigated farming or urban areas. In agricultural areas irrigated by surface water, ΣDDT concentrations in both streambed sediment and fish tissue were related to the percentage of land irrigated by water delivered via furrows (gravity irrigation), although ΣDDT was not detectable in bed sediments until gravity irrigation exceeded 30%. Because of the relation between gravity irrigation and soil erosion, our study supports the importance of controlling soil erosion in order to reduce the overall loading of organochlorine compounds to surface waters.

Comparative metagenomics of bathypelagic plankton and bottom sediment from the Sea of Marmara

PubMed Central

Quaiser, Achim; Zivanovic, Yvan; Moreira, David; López-García, Purificación

2011-01-01

To extend comparative metagenomic analyses of the deep-sea, we produced metagenomic data by direct 454 pyrosequencing from bathypelagic plankton (1000 m depth) and bottom sediment of the Sea of Marmara, the gateway between the Eastern Mediterranean and the Black Seas. Data from small subunit ribosomal RNA (SSU rRNA) gene libraries and direct pyrosequencing of the same samples indicated that Gamma- and Alpha-proteobacteria, followed by Bacteroidetes, dominated the bacterial fraction in Marmara deep-sea plankton, whereas Planctomycetes, Delta- and Gamma-proteobacteria were the most abundant groups in high bacterial-diversity sediment. Group I Crenarchaeota/Thaumarchaeota dominated the archaeal plankton fraction, although group II and III Euryarchaeota were also present. Eukaryotes were highly diverse in SSU rRNA gene libraries, with group I (Duboscquellida) and II (Syndiniales) alveolates and Radiozoa dominating plankton, and Opisthokonta and Alveolates, sediment. However, eukaryotic sequences were scarce in pyrosequence data. Archaeal amo genes were abundant in plankton, suggesting that Marmara planktonic Thaumarchaeota are ammonia oxidizers. Genes involved in sulfate reduction, carbon monoxide oxidation, anammox and sulfatases were over-represented in sediment. Genome recruitment analyses showed that Alteromonas macleodii ‘surface ecotype', Pelagibacter ubique and Nitrosopumilus maritimus were highly represented in 1000 m-deep plankton. A comparative analysis of Marmara metagenomes with ALOHA deep-sea and surface plankton, whale carcasses, Peru subsurface sediment and soil metagenomes clustered deep-sea Marmara plankton with deep-ALOHA plankton and whale carcasses, likely because of the suboxic conditions in the deep Marmara water column. The Marmara sediment clustered with the soil metagenome, highlighting the common ecological role of both types of microbial communities in the degradation of organic matter and the completion of biogeochemical cycles. PMID:20668488

Process recognition in multi-element soil and stream-sediment geochemical data

USGS Publications Warehouse

Grunsky, E.C.; Drew, L.J.; Sutphin, D.M.

2009-01-01

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on the spatial separation of the stream-sediment and soil samples, some elements are more highly correlated than others. Crown Copyright ?? 2009.

Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

PubMed Central

Reynolds, Richard; Belnap, Jayne; Reheis, Marith; Lamothe, Paul; Luiszer, Fred

2001-01-01

Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20–30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt. PMID:11390965

Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

USGS Publications Warehouse

Reynolds, R.; Belnap, Jayne; Lamothe, Paul; Luiszer, Fred

2001-01-01

Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20a??30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt.

Superfund Record of Decision (EPA Region 5): Summit National Liquid Disposal Service, Deerfield, OH. (First remedial action), (Amendment), November 1990. Final report

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

Not Available

The 11.5-acre Summit National Liquid Disposal Service site is a former liquid waste disposal facility in rural Deerfield Township, Ohio. The site contains two ponds, an inactive incinerator, and several vacant buildings. Surrounding the site are several residences, two landfills, light industries, and farmland. From 1973 to 1978, Summit National operated a solvent recycling and waste disposal facility onsite. The Record of Decision (ROD) amends a 1988 ROD that provided for remediation of contaminated soil, sediment, debris, ground water, and surface water. In both the 1990 proposed remedy for the ROD amendment and the 1988 ROD, the remedy for themore » most highly contaminated soil and sediment is excavation and treatment. The amended remedial action for the site includes expanding site boundaries to include contaminated areas along the site perimeters; excavating and incinerating onsite 24,000 cubic yards of soil excavated to a depth of 2 feet, 4,000 cubic yards of sediment from the site perimeter, drainage ditches and offsite ponds, and 900 to 1,600 buried drums.« less

Concentrations of polybrominated diphenyl ethers and alternative flame retardants in surface soils and river sediments from an electronic waste-processing area in northern Vietnam, 2012-2014.

PubMed

Matsukami, Hidenori; Suzuki, Go; Someya, Masayuki; Uchida, Natsuyo; Tue, Nguyen Minh; Tuyen, Le Huu; Viet, Pham Hung; Takahashi, Shin; Tanabe, Shinsuke; Takigami, Hidetaka

2017-01-01

We investigated the concentrations of polybrominated diphenyl ethers (PBDEs) and alternative flame retardants (FRs) in environmental samples collected in January 2012, 2013, and 2014 from an electronic waste-processing area in northern Vietnam. During the study period, PBDE and alternative FR concentrations in soils around the electronic waste-processing workshops ranged from 37 to 9200 ng g -1 dry weight (dw) and from 35 to 24,000 ng g -1 dw; the concentrations in soils around the open-burning sites ranged from 1.6 to 62 ng g -1 dw and from <4 to 1900 ng g -1 dw; and the concentrations in river sediments around the workshops ranged from 100 to 3800 ng g -1 dw and from 23 to 6800 ng g -1 dw, respectively. Over the course of study period, we observed significant decreases in concentrations of PBDEs and significant increases in concentrations of alternative FRs, particularly Dechlorane Plus isomers and oligomeric organophosphorus FRs (o-PFRs) in both soils and sediments around the workshops. We also report information on concentrations and environmental emissions of o-PFRs and their low-molecular-weight impurities in the same soils and sediments. The detection of o-PFR impurities around the workshops and the open-burning sites highlights an enhanced breakdown of o-PFRs probably due to weathering during open storage and high temperature attained during the burning of electronic wastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.).

Reconciling drainage and receiving basin signatures of the Godavari River system

NASA Astrophysics Data System (ADS)

Ojoshogu Usman, Muhammed; Kirkels, Frédérique Marie Sophie Anne; Zwart, Huub Michel; Basu, Sayak; Ponton, Camilo; Blattmann, Thomas Michael; Ploetze, Michael; Haghipour, Negar; McIntyre, Cameron; Peterse, Francien; Lupker, Maarten; Giosan, Liviu; Eglinton, Timothy Ian

2018-06-01

The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic matter (OM) exported by the fluvial system and establish links to sedimentary records accumulating on its adjacent continental margin, the stable and radiogenic isotopic composition of bulk OC, abundance and distribution of long-chain fatty acids (LCFAs), sedimentological properties (e.g. grain size, mineral surface area, etc.) of fluvial (riverbed and riverbank) sediments and soils from the Godavari basin were analysed and these characteristics were compared to those of a sediment core retrieved from the continental slope depocenter. Results show that river sediments from the upper catchment exhibit higher total organic carbon (TOC) contents than those from the lower part of the basin. The general relationship between TOC and sedimentological parameters (i.e. mineral surface area and grain size) of the sediments suggests that sediment mineralogy, largely driven by provenance, plays an important role in the stabilization of OM during transport along the river axis, and in the preservation of OM exported by the Godavari to the Bay of Bengal. The stable carbon isotopic (δ13C) characteristics of river sediments and soils indicate that the upper mainstream and its tributaries drain catchments exhibiting more 13C enriched carbon than the lower stream, resulting from the regional vegetation gradient and/or net balance between the upper (C4-dominated plants) and lower (C3-dominated plants) catchments. The radiocarbon contents of organic carbon (Δ14COC) in deep soils and eroding riverbanks suggests these are likely sources of old or pre-aged carbon to the Godavari River that increasingly dominates the late Holocene portion of the offshore sedimentary record. While changes in water flow and sediment transport resulting from recent dam construction have drastically impacted the flux, loci, and composition of OC exported from the modern Godavari basin, complicating reconciliation of modern-day river basin geochemistry with that recorded in continental margin sediments, such investigations provide important insights into climatic and anthropogenic controls on OC cycling and burial.

Autecological Study of the Chemoautotroph Nitrobacter by Immunofluorescence

PubMed Central

Fliermans, C. B.; Bohlool, B. B.; Schmidt, E. L.

1974-01-01

Fluorescent antibodies (FA) prepared for Nitrobacter agilis and N. winogradskyi were highly reactive in homologous staining. Low-level cross-reactions between the two species were removed by adsorption. All 15 pure-culture isolates of Nitrobacter tested reacted strongly with either N. agilis FA or N. winogradskyi FA. All pure-culture isolates from soils were determined to be N. winogradskyi; those from Mammoth Cave sediments and a cattle waste oxidation ditch were N. agilis. No cross-reaction was found in extensive tests that included five isolates of Nitrosomonas europaea and 668 heterotrophic aerobic and anaerobic bacteria isolated from soil, sewage, and cave sites. The FA preparations were used to detect Nitrobacter species in Mammoth Cave sediments, in a cattle waste oxidation ditch, and in surface waters and sediments of a river and to observe that N. winogradskyi can outgrow N. agilis in enrichment culture. Images PMID:4589121

Remediation of PCB contaminated soils in the Canadian Arctic: excavation and surface PRB technology.

PubMed

Kalinovich, Indra; Rutter, Allison; Poland, John S; Cairns, Graham; Rowe, R Kerry

2008-12-15

The site BAF-5 is located on the summit of Resolution Island, Nunavut, just southeast of Baffin Island at 61 degrees 35'N and 60 degrees 40'W. The site was part of a North American military defense system established in the 1950s that became heavily contaminated with PCBs during and subsequent, its operational years. Remediation through excavation of the PCB contaminated soil at Resolution Island began in 1999 and at its completion in 2006 approximately 5 tonnes of pure PCBs in approximately 20,000 m3 of soil were remediated. Remediation strategies were based on both quantity of soil and level of contamination in the soil. Excavation removed 96% of the PCB contaminated soil on site. In 2003, a surface funnel-and-gate permeable reactive barrier was design and constructed to treat the remaining contamination left in rock crevices and inaccessible areas of the site. Excavation had destabilized contaminated soil in the area, enabling contaminant migration through erosion and runoff pathways. The barrier was designed to maximize sedimentation through settling ponds. This bulk removal enabled the treatment of highly contaminated fines and water through a permeable gate. The increased sediment loading during excavation required both modifications to the funnel and a shift to a more permeable, granular system. Granulated activated charcoal was chosen for its ability to both act as a particle retention filter and adsorptive filter. The reduction in mass of PCB and volume of soils trapped by the funnel of the barrier indicate that soils are re-stabilizing. In 2007, nonwoven geotextiles were re-introduced back into the filtration system as fine filtering could be achieved without clogging. Monitoring sites downstream indicate that the barrier system is effective. This paper describes the field progress of PCB remediation at Resolution Island.

Physical and chemical properties of the Martian soil: Review of resources

NASA Technical Reports Server (NTRS)

Stoker, C. R.; Gooding, James L.; Banin, A.; Clark, Benton C.; Roush, Ted

1991-01-01

The chemical and physical properties of Martian surface materials are reviewed from the perspective of using these resources to support human settlement. The resource potential of Martian sediments and soils can only be inferred from limited analyses performed by the Viking Landers (VL), from information derived from remote sensing, and from analysis of the SNC meteorites thought to be from Mars. Bulk elemental compositions by the VL inorganic chemical (x ray fluorescence) analysis experiments have been interpreted as evidence for clay minerals (possibly smectites) or mineraloids (palagonite) admixed with sulfate and chloride salts. The materials contained minerals bearing Fe, Ti, Al, Mg and Si. Martian surface materials may be used in many ways. Martian soil, with appropriate preconditioning, can probably be used as a plant growth medium, supplying mechanical support, nutrient elements, and water at optimal conditions to the plants. Loose Martian soils could be used to cover structures and provide radiation shielding for surface habitats. Martian soil could be wetted and formed into abode bricks used for construction. Duricrete bricks, with strength comparable to concrete, can probably be formed using compressed muds made from martian soil.

Groundwater control on the suspended sediment load in the Na Borges River, Mallorca, Spain

NASA Astrophysics Data System (ADS)

Estrany, Joan; Garcia, Celso; Batalla, Ramon J.

2009-05-01

Groundwater dominance has important effects on the hydrological and geomorphological characteristics of river systems. Low suspended sediment concentrations and high water clarity are expected because significant inputs of sediment-free spring water dilute the suspended sediment generated by storms. However, in many Mediterranean rivers, groundwater dominance is characterised by seasonal alternations of influent and effluent discharge involving significant variability on the sediment transport regimes. Such areas are often subject to soil and water conservation practices over the centuries that have reduced the sediment contribution from agricultural fields and favour subsurface flow to rivers. Moreover, urbanisation during the twentieth century has changed the catchment hydrology and altered basic river processes due to its 'flashy' regime. In this context, we monitored suspended sediment fluxes during a two-year period in the Na Borges River, a lowland agricultural catchment (319 km 2) on the island of Mallorca (Balearic Islands). The suspended sediment concentration (SSC) was lower when the base flow index (i.e., relative proportion of baseflow compared to stormflow, BFI) was higher. Therefore, strong seasonal contrasts explain the high SSC coefficient of variation, which is clearly related to dilution effects associated with different groundwater and surface water seasonal interactions. A lack of correlation in the Q-SSC rating curves shows that factors other than discharge control sediment transport. As a result, at the event scale, multiple regressions illustrate that groundwater and surface water interactions are involved in the sedimentary response of flood events. In the winter, the stability of baseflow driven by groundwater contributions and agricultural and urban spills causes hydraulic variables (i.e., maximum discharge) to exert the most important control on events, whereas in the summer, it is necessary to accumulate important volumes of rainfall, creating a minimum of wet conditions in the catchment to activate hydrological pathways and deliver sediment to the drainage network. The BFI is also related to sediment delivery processes, as the loads are higher with lower BFI, corroborating the fact that most sediment movement is caused by stormflow and its related factors. Overall, suspended sediment yields were very low (i.e., < 1 t km - 2 yr - 1 ) at all measuring sites. Such values are the consequence of the limited sediment delivery attributable to soil conservation practices, low surface runoff coefficients and specific geomorphic features of groundwater-dominated rivers, such as low drainage density, low gradient, steep valley walls and flat valley floors.

Groundwater Flow Through a Constructed Treatment Wetland

DTIC Science & Technology

2002-03-01

sediments or has the water found preferential flow paths? (2) Does the behavior of groundwater flow change with varying loading rates or environmental...surface of the wetland. Water flows through a subsurface flow wetland in a similar fashion as groundwater flows through an aquifer. The concept is...circuiting of the wetland media. Groundwater Flow Various physical properties influence the flow of water through soil. In wetlands, the type of soil

Development of Surface Complexation Models of Cr(VI) Adsorption on Soils, Sediments and Model Mixtures of Kaolinite, Montmorillonite, γ-Alumina, Hydrous Manganese and Ferric Oxides and Goethite

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

Koretsky, Carla

Hexavalent chromium is a highly toxic contaminant that has been introduced into aquifers and shallow sediments and soils via many anthropogenic activities. Hexavalent chromium contamination is a problem or potential problem in the shallow subsurface at several DOE sites, including Hanford, Idaho National Laboratory, Los Alamos National Laboratory and the Oak Ridge Reservation (DOE, 2008). To accurately quantify the fate and transport of hexavalent chromium at DOE and other contaminated sites, robust geochemical models, capable of correctly predicting changes in chromium chemical form resulting from chemical reactions occurring in subsurface environments are needed. One important chemical reaction that may greatlymore » impact the bioavailability and mobility of hexavalent chromium in the subsurface is chemical binding to the surfaces of particulates, termed adsorption or surface complexation. Quantitative thermodynamic surface complexation models have been derived that can correctly calculate hexavalent chromium adsorption on well-characterized materials over ranges in subsurface conditions, such pH and salinity. However, models have not yet been developed for hexavalent chromium adsorption on many important constituents of natural soils and sediments, such as clay minerals. Furthermore, most of the existing thermodynamic models have been developed for relatively simple, single solid systems and have rarely been tested for the complex mixtures of solids present in real sediments and soils. In this study, the adsorption of hexavalent chromium was measured as a function of pH (3-10), salinity (0.001 to 0.1 M NaNO3), and partial pressure of carbon dioxide(0-5%) on a suite of naturally-occurring solids including goethite (FeOOH), hydrous manganese oxide (MnOOH), hydrous ferric oxide (Fe(OH)3), γ-alumina (Al2O3), kaolinite (Al2Si2O5(OH)4), and montmorillonite (Na3(Al, Mg)2Si4O10(OH)2-nH2O). The results show that all of these materials can bind substantial quantities of hexavalent chromium, especially at low pH. Unexpectedly, experiments with the clay minerals kaolinite and montmorillonite suggest that hexavalent chromium may interact with these solids over much longer periods of time than expected. Furthermore, hexavalent chromium may irreversibly bind to these solids, perhaps because of oxidation-reduction reactions occurring on the surfaces of the clay minerals. More work should be done to investigate and quantify these chemical reactions. Experiments conducted with mixtures of goethite, hydrous manganese oxide, hydrous ferric oxide, γ-alumina, montmorillonite and kaolinite demonstrate that it is possible to correctly predict hexavalent chromium binding in the presence of multiple minerals using thermodynamic models derived for the simpler systems. Further, these models suggest that of the six solid considered in this study, goethite is typically the solid to which most of the hexavalent chromium will bind. Experiments completed with organic-rich and organic-poor natural sediments demonstrate that in organic-rich substrates, organic matter is likely to control uptake of the hexavalent chromium. The models derived and tested in this study for hexavalent chromium binding to γ-alumina, hydrous manganese oxide, goethite, hydrous ferric oxide and clay minerals can be used to better predict changes in hexavalent chromium bioavailability and mobility in contaminated sediments and soils.« less

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.

Localized enrichment of polycyclic aromatic hydrocarbons in soil, spruce needles, and lake sediments linked to in-situ bitumen extraction near Cold Lake, Alberta.

PubMed

Korosi, J B; Irvine, G; Skierszkan, E K; Doyle, J R; Kimpe, L E; Janvier, J; Blais, J M

2013-11-01

The extraction of bitumen from the Alberta oil sands using in-situ technologies is expanding at a rapid rate; however, investigations into the environmental impacts of oil sands development have focused on surface mining in the Athabasca region. We measured polycyclic aromatic hydrocarbons (PAH) in soils, spruce needles, and lake sediment cores in the Cold Lake oil sands region to provide a historical and spatial perspective on PAH contamination related to in-situ extraction activities. A pronounced increase in PAH concentrations was recorded in one of two study lakes (Hilda Lake) corresponding to the onset of commercial bitumen production in ~1985. Distance from extraction rigs was not an important predictor of PAH concentrations in soils, although two samples located near installations were elevated in alkyl PAHs. Evidence of localized PAH contamination in Hilda Lake and two soil samples suggests that continued environmental monitoring is justified to assess PAH contamination as development intensifies. Copyright © 2013 Elsevier Ltd. All rights reserved.

PFAS methods and guidance for sampling and analyzing water and other environmental media (Technical Brief)

EPA Pesticide Factsheets

EPA's methods for analyzing PFAS in environmental media are in various stages of development. This fact sheet summarizes EPA's analytical methods development for groundwater, surface water, wastewater, and solids, including soils, sediments, and biosolids

Engineering geologic conditions at the sinkhole entrance to Logan Cave, Benton County, Arkansas

USGS Publications Warehouse

Schulz, William H.; McKenna, Jonathan P.

2004-01-01

Logan Cave, located in Benton County, Arkansas, is inhabited by several endangered and threatened species. The cave and surrounding area was designated a National Wildlife Refuge under the control of the U.S. Fish and Wildlife Service (USFWS) in 1989. Cave researchers access the cave through a steep-sided sinkhole entrance, which also is one of the two access points used by endangered bats. There is evidence of instability of one of the entrance slopes that has raised concerns that the entrance could close if slope failure was to occur. At the request of USFWS, we performed an engineering geologic investigation of the sinkhole to evaluate stability of this slope, which is comprised of soil, and other mechanisms of sediment transport into the cave entrance. The investigation included engineering geologic mapping, sampling and laboratory testing of subsurface geologic materials, and slope-stability analysis. We found that the sinkhole slope that extends into the entrance of the cave is comprised of sandy and gravelly soil to the depths explored (6.4 meters). This soil likely was deposited as alluvium within a previous, larger sinkhole. Based on properties of the alluvium, geometry of the slope, and results of finite-element slope-stability analyses, we conclude that the slope is marginally stable. Future failures of the slope probably would be relatively thin and small, thus several would be required to completely close the cave entrance. However, sediment is accumulating within the cave entrance due to foot traffic of those accessing the cave, surface-water erosion and transport, and shallow slope failures from the other sinkhole slopes. We conclude that the entrance will be closed by sediment in the future, similar to another entrance that we identified that completely closed in the past. Several measures could be taken to reduce the potential for closure of the cave entrance, including periodic sediment removal, installation of materials that reduce erosion by foot traffic and surface water, construction of a sediment-retention wall, and excavation of the soil slope. Any measures taken must be carefully planned and executed so that they have no impact on organisms within the cave.

Surface-water-quality assessment of the Yakima River basin, Washington; distribution of pesticides and other organic compounds in water, sediment, and aquatic biota, 1987-91; with a section on dissolved organic carbon in the Yakima River basin

USGS Publications Warehouse

Rinella, Joseph F.; McKenzie, Stuart W.; Crawford, J. Kent; Foreman, William T.; Fuhrer, Gregory J.; Morace, Jennifer L.; Aiken, George R.

1999-01-01

During 1987-91, chemical data were collected for pesticides and other organic compounds in surface water, streambed sediment, suspended sediment, agricultural soil, and aquatic biota to determine the occurrence, distribution, transport, and fate of organic compounds in the Yakima River basin in Washington. The report describes the chemical and physical properties of the compounds most frequently detected in the water column; organochlorine compounds including DDT, organophosphorus compounds, thiocarbamate and sulfite compounds, acetamide and triazine compounds, and chlorophenoxy-acetic acid and benzoic compounds. Concentrations are evaluated relative to chronic-toxicity water quality criteria and guidelines for the protection of human health and freshwater aquatic life.

The influence of terracettes on surface hydrology and erosion on vegetated Alpine, mountain and steep-sloping environments

NASA Astrophysics Data System (ADS)

Kuhn, Nikolaus; (Phil) Greenwood, Philip

2014-05-01

Alpine and mountain slopes represent important pathways that link high altitude grazing areas to meadows and rangelands at lower elevations. Given the often acute gradient of mountain slopes, they represent a convenient and potentially highly efficient runoff conveyance route that facilitates the downslope transfer of fine-sediment and sediment-bound nutrients and contaminants during erosion events. Above a certain gradient, many slopes host small steps, or `terracettes`. As these are generally orientated across slope, their genesis is usually attributed to a combination of soil creep, coupled with (and often accentuated by) grazing animals. Motivated by the prevalence of these distinct landform features and lack of information on their role as runoff conveyance routes, this communication reports preliminary results from an investigation to explore the possibility that terracettes may act as preferential flow-paths, with an as yet undocumented ability to greatly influence surface hydrology in mountainous and steeply-sloping environments. A ca. 40 m2 area of vegetated terracettes and section of adjacent thalweg, with gradients ranging from approximately 25-35o, were scanned using an automated Topcon IS03 Total Station at a resolution of 0.1 * 0.1 m. Data were converted to a Digital Elevation Model (DEM) in ArcGIS 10 Geographical Information System (GIS), and queried using Spatial Analyst (Surface Hydrology; Flow Accumulation function) to identify slope-sections that could act as preferential flow-pathways during runoff events. These data were supplemented by information on soil physical properties that included grain size composition, bulk density and porosity, in order to establish spatial variations in soil characteristics associated with the vertical and horizontal terracette features. Combining the digital and in-situ data indicate that the technique is able to identify preferential surface flow-paths. Such information could greatly benefit the future management of grazing and rangelands in Alpine, mountain and steeply sloping environments. With higher resolution data covering larger areas, as well as the possibility of using fallout radionuclide data to establish sediment residence times on depositional areas, it is envisioned that runoff and transportation of fine-sediment and sediment-associated nutrients and contaminants down these flow pathways could be modeled, predicted and their effects mitigated and perhaps eventually reduced.

Infiltration and soil erosion modelling on Lausatian post mine sites

NASA Astrophysics Data System (ADS)

Kunth, Franziska; Schmidt, Jürgen

2013-04-01

Land management of reclaimed lignite mine sites requires long-term and safe structuring of recultivation areas. Erosion by water leads to explicit soil losses, especially on heavily endangered water repellent and non-vegetated soil surfaces. Beyond that, weathering of pyrite-containing lignite burden dumps causes sulfuric acid-formation, and hence the acidification of groundwater, seepage water and surface waters. Pyrite containing sediment is detached by precipitation and transported into worked-out open cuts by draining runoff. In addition to ground water influence, erosion processes are therefore involved in acidification of surface waters. A model-based approach for the conservation of man-made slopes of post mining sites is the objective of this ongoing study. The study shall be completed by modeling of the effectiveness of different mine site recultivation scenarios. Erosion risks on man-made slopes in recultivation areas should be determined by applying the physical, raster- and event based computer model EROSION 2D/3D (Schmidt, 1991, 1992; v. Werner, 1995). The widely used erosion model is able to predict runoff as well as detachment, transport and deposition of sediments. Lignite burden dumps contain hydrophobic substances that cover soil particles. Consequently, these soils show strong water repellency, which influences the processes of infiltration and soil erosion on non-vegetated, coal containing dump soils. The influence of water repellency had to be implemented into EROSION 2D/3D. Required input data for soil erosion modelling (e.g. physical soil parameters, infiltration rates, calibration factors, etc.) were gained by soil sampling and rainfall experiments on non-vegetated as well as recultivated reclaimed mine sites in the Lusatia lignite mining region (southeast of Berlin, Germany). The measured infiltration rates on the non-vegetated water repellent sites were extremely low. Therefore, a newly developed water repellency-factor was applied to depict infiltration and erosion processes on water repellent dump soils. For infiltration modelling with EROSION 2D calibration factors (e.g. water repellency factor, skin-factor, etc.) were determined in different steps by calibrating computer modelled infiltration, respectively volume rate of flow to the measured data.

Using Unmanned Aerial Vehicle (UAV) for spatio-temporal monitoring of soil erosion and roughness in Chania, Crete, Greece

NASA Astrophysics Data System (ADS)

Alexakis, Dimitrios; Seiradakis, Kostas; Tsanis, Ioannis

2016-04-01

This article presents a remote sensing approach for spatio-temporal monitoring of both soil erosion and roughness using an Unmanned Aerial Vehicle (UAV). Soil erosion by water is commonly known as one of the main reasons for land degradation. Gully erosion causes considerable soil loss and soil degradation. Furthermore, quantification of soil roughness (irregularities of the soil surface due to soil texture) is important and affects surface storage and infiltration. Soil roughness is one of the most susceptible to variation in time and space characteristics and depends on different parameters such as cultivation practices and soil aggregation. A UAV equipped with a digital camera was employed to monitor soil in terms of erosion and roughness in two different study areas in Chania, Crete, Greece. The UAV followed predicted flight paths computed by the relevant flight planning software. The photogrammetric image processing enabled the development of sophisticated Digital Terrain Models (DTMs) and ortho-image mosaics with very high resolution on a sub-decimeter level. The DTMs were developed using photogrammetric processing of more than 500 images acquired with the UAV from different heights above the ground level. As the geomorphic formations can be observed from above using UAVs, shadowing effects do not generally occur and the generated point clouds have very homogeneous and high point densities. The DTMs generated from UAV were compared in terms of vertical absolute accuracies with a Global Navigation Satellite System (GNSS) survey. The developed data products were used for quantifying gully erosion and soil roughness in 3D as well as for the analysis of the surrounding areas. The significant elevation changes from multi-temporal UAV elevation data were used for estimating diachronically soil loss and sediment delivery without installing sediment traps. Concerning roughness, statistical indicators of surface elevation point measurements were estimated and various parameters such as standard deviation of DTM, deviation of residual and standard deviation of prominence were calculated directly from the extracted DTM. Sophisticated statistical filters and elevation indices were developed to quantify both soil erosion and roughness. The applied methodology for monitoring both soil erosion and roughness provides an optimum way of reducing the existing gap between field scale and satellite scale. Keywords : UAV, soil, erosion, roughness, DTM

Groundwater and Human Controls on the Suspended Sediment Load of Na Borges River, Mallorca (Spain)

NASA Astrophysics Data System (ADS)

Estrany, J.; Garcia, C.

2009-04-01

Groundwater dominance has important effects on the hydrological and geomorphological characteristics of river systems. Low suspended sediment concentrations and high water clarity are expected because significant inputs of sediment-free spring water dilute the suspended sediment generated by storms. However, in many Mediterranean temporary rivers, groundwater dominance is characterised by seasonal alternations of influent and effluent discharge involving significant variability on the sediment transport regimes. Such areas are often subject to soil and water conservation practices over the centuries that have reduced the sediment contribution from agricultural fields and favour subsurface flow to rivers. Moreover, urbanisation during the twentieth century has changed the catchment hydrology and altered basic river processes due to its ‘flashy' regime. In this context, we monitored suspended sediment fluxes by means of three nested sub-catchments during a two-year period in the Na Borges River, a lowland agricultural catchment (319 km2) on the island of Mallorca (Balearic Islands) managed and therefore modified since Roman Age by agricultural soil and water conservation practices and recently by urbanisation. The suspended sediment concentration (SSC) was lower when the base flow index (i.e., relative proportion of baseflow compared to stormflow, BFI) was higher. Considering the high variability of the Mediterranean climate, a significant scatter of daily average SSC between sites and seasonally was observed, ranging between 22 to 54 mg l-1 for the total study period. The maximum instantaneous peak surpassed 6,000 mg l-1, recorded at downstream site based on the sediment supplied when there was no baseflow and the rainfall intensity was remarkable. At the other sites, peak concentrations did not exceed 2,000 mg l-1 because groundwater plays a more significant role. Furthermore, strong seasonal contrasts explain the high SSC coefficient of variation, which is clearly related to dilution effects associated with different groundwater and surface water seasonal interactions. A lack of correlation in the Q-SSC rating curves shows that factors other than discharge control sediment transport. As a result, at the event scale, multiple regressions illustrate that groundwater and surface water interactions are involved in the sedimentary response of flood events. In the winter, the stability of baseflow driven by groundwater contributions and agricultural and urban spills causes hydraulic variables (i.e., maximum discharge) to exert the most important control on events, whereas in the summer, it is necessary to accumulate important volumes of rainfall, creating a minimum of wet conditions in the catchment to activate hydrological pathways and deliver sediment to the drainage network. The BFI is also related to sediment delivery processes, as the loads are higher with lower BFI, corroborating the fact that most sediment movement is caused by stormflow and its related factors. Overall, suspended sediment yields were very low (i.e., <1 t km-2 yr-1) at all measuring sites. Such values are the consequence of the limited sediment delivery attributable to soil conservation practices, low surface runoff coefficients and specific geomorphic features of groundwater-dominated rivers, such as low drainage density, low gradient, steep valley walls and flat valley floors. Moreover, most sediment was transported in the wetter winter period when influent dynamics dominate along the drainage network. Strong contrasts are also evident between the three sites, revealing that significant sediment transport is accomplished in a shorter period for more ephemeral fluvial regimes.

Meteoric 10Be as a tracer of subglacial processes and interglacial surface exposure in Greenland

NASA Astrophysics Data System (ADS)

Graly, Joseph A.; Corbett, Lee B.; Bierman, Paul R.; Lini, Andrea; Neumann, Thomas A.

2018-07-01

In order to test whether sediment emerging from presently glaciated areas of Greenland was exposed near or at Earth's surface during previous interglacial periods, we measured the rare isotope 10Be contained in grain coatings of sediment collected at five ice marginal sites. Such grain coatings contain meteoric 10Be (10Bemet), which forms in the atmosphere and is deposited onto Earth's surface. Samples include sediment entrained in ice, glaciofluvial sediment collected at the ice margin, and subglacial sediment extracted during hot water drilling in the ablation zone. Due to burial by ice, contemporary subglacial sediment could only have acquired substantial 10Bemet concentrations during periods in the past when the Greenland Ice Sheet was less extensive than present. The highest measured 10Bemet concentrations are comparable to those found in well-developed, long-exposed soils, suggesting subglacial preservation and glacial transport of sediment exposed during preglacial or interglacial periods. Ice-bound sediment has significantly higher 10Bemet concentrations than glaciofluvial sediment, suggesting that glaciofluvial processes are sufficiently erosive to remove tracers of previous interglacial exposures. Northern Greenland sites where ice and sediment are supplied from the ice sheet's central main dome have significantly higher 10Bemet concentrations than sites in southern Greenland, indicating greater preglacial or interglacial landscape preservation in central Greenland than in the south. Because southern Greenland has more frequent and spatially extensive periods of glacial retreat but nevertheless has less evidence of past subaerial exposure, we suggest that 10Bemet measurements in glacial sediment are primarily controlled by erosional efficiency rather than interglacial exposure length.

Organic carbon burial in fjords: Terrestrial versus marine inputs

NASA Astrophysics Data System (ADS)

Cui, Xingqian; Bianchi, Thomas S.; Savage, Candida; Smith, Richard W.

2016-10-01

Fjords have been identified as sites of enhanced organic carbon (OC) burial and may play an important role in regulating climate change on glacial-interglacial timescales. Understanding sediment processes and sources of sedimentary OC are necessary to better constrain OC burial in fjords. In this study, we use Fiordland, New Zealand, as a case study and present data on surface sediments, sediment down-cores and terrestrial end-members to examine dynamics of sediments and the sources of OC in fjord sediments. Sediment cores showed evidence of multiple particle sources, frequent bioturbation and mass-wasting events. A multi-proxy approach (stable isotopes, lignin-phenols and fatty acids) allowed for separation of marine, soil and vascular plant OC in surface sediments. The relationship between mass accumulation rate (MAR) and OC contents in fjord surface sediments suggested that mineral dilution is important in controlling OC content on a global scale, but is less important for specific regions (e.g., New Zealand). The inconsistency of OC budgets calculated by using MAR weighted %OC and OC accumulation rates (AR; 6 vs 21-31 Tg OC yr-1) suggested that sediment flux in fjords was likely underestimated. By using end-member models, we propose that 55% to 62% of total OC buried in fjords is terrestrially derived, and accounts for 17 ± 12% of the OCterr buried in all marine sediments. The strong correlation between MAR and OC AR indicated that OC flux will likely decrease in fjords in the future with global warming due to decrease in sediment flux caused by glacier denudation.

Shifts in microbial community composition following surface application of dredged river sediments.

PubMed

Baniulyte, Dovile; Favila, Emmanuel; Kelly, John J

2009-01-01

Sediment input to the Illinois River has drastically decreased river depth and reduced habitats for aquatic organisms. Dredging is being used to remove sediment from the Illinois River, and the dredged sediment is being applied to the surface of a brownfield site in Chicago with the goal of revegetating the site. In order to determine the effects of this drastic habitat change on sediment microbial communities, we examined sediment physical, chemical, and microbial characteristics at the time of sediment application to the soil surface as well as 1 and 2 years after application. Microbial community biomass was determined by measurement of lipid phosphate. Microbial community composition was assessed using phospholipid fatty acid (PLFA) analysis, terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes, and clone library sequencing of 16S rRNA genes. Results indicated that the moisture content, organic carbon, and total nitrogen content of the sediment all decreased over time. Total microbial biomass did not change over the course of the study, but there were significant changes in the composition of the microbial communities. PLFA analysis revealed relative increases in fungi, actinomycetes, and Gram positive bacteria. T-RFLP analysis indicated a significant shift in bacterial community composition within 1 year of application, and clone library analysis revealed relative increases in Proteobacteria, Gemmatimonadetes, and Bacteriodetes and relative decreases in Acidobacteria, Spirochaetes, and Planctomycetes. These results provide insight into microbial community shifts following land application of dredged sediment.

Using synthetic polymers to reduce soil erosion after forest fires in Mediterranean soils

NASA Astrophysics Data System (ADS)

Lado, Marcos; Ben-Hur, Meni; Inbar, Assaf

2010-05-01

Forest fires are a major environmental problem in the Mediterranean region because they result in a loss of vegetation cover, changes in biodiversity, increases in greenhouse gasses emission and a potential increase of runoff and soil erosion. The large increases in runoff and sediment yields after high severity fires have been attributed to several factors, among them: increase in soil water repellency; soil sealing by detached particles and by ash particles, and the loss of a surface cover. The presence of a surface cover increases infiltration, and decreases runoff and erosion by several mechanisms which include: rainfall interception, plant evapotranspiration, preservation of soil structure by increasing soil organic matter, and increasing surface roughness. The loss of vegetation cover as a result of fire leaves the surface of the soil exposed to the direct impact of the raindrops, and therefore the sensitivity of the soil to runoff generation and soil loss increases. In this work, we propose a new method to protect soils against post-fire erosion based on the application of synthetic polymers to the soil. Laboratory rainfall simulations and field runoff plots were used to analyze the suitability of the application of synthetic polymers to reduce soil erosion and stabilize soil structure in Mediterranean soils. The combination of these two processes will potentially favor a faster recovery of the vegetation structure. This method has been successfully applied in arable land, however it has not been tested in burnt forests. The outcome of this study may provide important managerial tools for forest management following fires.

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.

Health assessment for Lake Sandy Jo Landfill, Gary, Indiana, Region 5. CERCLIS No. IND980500524. Final report

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

Not Available

1985-11-21

The 50-acre Lake Sandy Jo Landfill is located in the Black Oak community (predominantly residential) of southwestern Gary in Lake County, Indiana. From about 1971 until about 1980, the lake was filled in with construction and demolition debris, municipal garbage, industrial wastes, hazardous materials, and possibly drummed wastes. These wastes are partly to completely exposed on the landfill surface. Surface soil, subsurface soil, surface water, sediment, and ground water show a variety of metal and organic chemical carcinogens. Toxic noncarcinogen priority pollutants found were chloromethane, copper, cyanide, lead, mercury, and silver. Inorganic soil levels found on the site for leadmore » and cadmium exceed levels of concern that would permit unrestricted use of the site. Remedial measures would be necessary before the site could be granted unrestricted use.« less

Developing a Dynamic SPARROW Water Quality Decision Support System Using NASA Remotely-Sensed Products

NASA Astrophysics Data System (ADS)

Al-Hamdan, M. Z.; Smith, R. A.; Hoos, A.; Schwarz, G. E.; Alexander, R. B.; Crosson, W. L.; Srikishen, J.; Estes, M., Jr.; Cruise, J.; Al-Hamdan, A.; Ellenburg, W. L., II; Flores, A.; Sanford, W. E.; Zell, W.; Reitz, M.; Miller, M. P.; Journey, C. A.; Befus, K. M.; Swann, R.; Herder, T.; Sherwood, E.; Leverone, J.; Shelton, M.; Smith, E. T.; Anastasiou, C. J.; Seachrist, J.; Hughes, A.; Graves, D.

2017-12-01

The USGS Spatially Referenced Regression on Watershed Attributes (SPARROW) surface water quality modeling system has been widely used for long term, steady state water quality analysis. However, users have increasingly requested a dynamic version of SPARROW that can provide seasonal estimates of nutrients and suspended sediment to receiving waters. The goal of this NASA-funded project is to develop a dynamic decision support system to enhance the southeast SPARROW water quality model and finer-scale dynamic models for selected coastal watersheds through the use of remotely-sensed data and other NASA Land Information System (LIS) products. The spatial and temporal scale of satellite remote sensing products and LIS modeling data make these sources ideal for the purposes of development and operation of the dynamic SPARROW model. Remote sensing products including MODIS vegetation indices, SMAP surface soil moisture, and OMI atmospheric chemistry along with LIS-derived evapotranspiration (ET) and soil temperature and moisture products will be included in model development and operation. MODIS data will also be used to map annual land cover/land use in the study areas and in conjunction with Landsat and Sentinel to identify disturbed areas that might be sources of sediment and increased phosphorus loading through exposure of the bare soil. These data and others constitute the independent variables in a regression analysis whose dependent variables are the water quality constituents total nitrogen, total phosphorus, and suspended sediment. Remotely-sensed variables such as vegetation indices and ET can be proxies for nutrient uptake by vegetation; MODIS Leaf Area Index can indicate sources of phosphorus from vegetation; soil moisture and temperature are known to control rates of denitrification; and bare soil areas serve as sources of enhanced nutrient and sediment production. The enhanced SPARROW dynamic models will provide improved tools for end users to manage water quality in near real time and for the formulation of future scenarios to inform strategic planning. Time-varying SPARROW outputs will aid water managers in decision making regarding allocation of resources in protecting aquatic habitats, planning for harmful algal blooms, and restoration of degraded habitats, stream segments, or lakes.

Soil erosion and effluent particle size distribution under different initial conditions and rock fragment coverage

NASA Astrophysics Data System (ADS)

Jomaa, S.; Barry, D. A.; Brovelli, A.; Heng, B. C. P.; Sander, G. C.; Parlange, J.-Y.

2012-04-01

It is well known that the presence of rock fragments on the soil surface and the soil's initial characteristics (moisture content, surface roughness, bulk density, etc.) are key factors influencing soil erosion dynamics and sediment delivery. In addition, the interaction of these factors increases the complexity of soil erosion patterns and makes predictions more difficult. The aim of this study was (i) to investigate the effect of soil initial conditions and rock fragment coverage on soil erosion yields and effluent particle size distribution and (ii) to evaluate to what extent the rock fragment coverage controls this relationship. Three laboratory flume experiments with constant precipitation rate of 74 mm/h on a loamy soil parcel with a 2% slope were performed. Experiments with duration of 2 h were conducted using the 6-m × 2-m EPFL erosion flume. During each experiment two conditions were considered, a bare soil and a rock fragment-protected (with 40% coverage) soil. The initial soil surface state was varied between the three experiments, from a freshly re-ploughed and almost dry condition to a compacted soil with a well-developed shield layer and high moisture content. Experiments were designed so that rain splash was the primary driver of soil erosion. Results showed that the amount of eroded mass was highly controlled by the initial soil conditions and whether the steady-state equilibrium was un-, partially- or fully- developed during the previous event. Additionally, results revealed that sediment yields and particle size composition in the initial part of an erosion event are more sensitive to the erosion history than the long-time behaviour. This latter appears to be mainly controlled by rainfall intensity. If steady-state was achieved for a previous event, then the next event consistently produced concentrations for each size class that peaked rapidly, and then declined gradually to steady-state equilibrium. If steady state was not obtained, then different and more complex behaviour was observed in the next event, with large differences found between fine, medium and coarse size classes. The presence of rock fragments on the topsoil reduced the time needed to reach steady state compared with the bare soil. This was attributed to the reduction of rain splash erosion caused by the rapid development of the overland flow, as a result of rock fragments reducing the flow cross-sectional area.

Health assessment for Louisiana Army Ammunition Plant, Shreveport, Webster County, Louisiana, Region 6. CERCLIS No. LA0213820533. Preliminary report

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

Not Available

1989-04-10

The Louisiana Army Ammunition Plant (LAAP) is listed on the National Priorities List. The site is a 15,000-acre Federal facility located in Shreveport (Webster Parish), Louisiana. On-site ground water beneath 16 unlined surface impoundments near the southern boundary is contaminated. Access to LAAP is restricted and under 24-hour security. Contaminants include 2,4,6-trinitrotoluene (TNT), cyclonite (RDX), trinitrobenzene (TNB), and homocyclonite (HMX). Preliminary on-site sampling results have identified TNT (493,133 ppm in sediment/subsoil, 483,556 ppm in sludge, 1,033 ppm in surface soil, 7 ppm in surface water, and 18 ppm in ground water), RDX (60,224 ppm in sediment/subsoil, 602 ppm in surfacemore » soil, 60,224 ppm in sludge, and 14 ppm in ground water), TNB (2 ppm in surface water and 8 ppm in ground water), and HMX (4 ppm in ground water). Based on available information, the site is considered to be of potential public health concern because of the risk to human health caused by the possibility of human exposure to hazardous substances.« less

Mercury and cadmium contamination of irrigation water, sediment, soil and shallow groundwater in a wastewater-irrigated field in Tianjin, China.

PubMed

Wu, G-H; Cao, S-S

2010-03-01

We investigated the concentrations of Hg, Cd, Pb and As in samples of irrigation water, sediment, soil and groundwater from a field in Tianjin that was irrigated with wastewater. The results showed that the concentrations (Hg, 0.82 microg/L; Cd, 0.18 microg/L; Pb, 1.5 microg/L; As, 8.02 microg/L) in the irrigation water did not exceed the China Surface Water Quality Standard or the maximum concentrations in irrigation water recommended by the FAO. The concentrations of metals in the groundwater of wells (Hg, 0.016 microg/L; Cd, 0.128 microg/L; Pb, 0.25 microg/L; As, 4.65 microg/L) were lower than China Groundwater Quality Standard and the WHO guideline values for drinking water. The groundwater had not yet been contaminated through vertical infiltration-induced leaching. However, a substantial buildup of Hg and Cd in river sediments (I(geo) for Hg and Cd; 5.24 and 3.04, respectively) and wastewater-irrigated soils (I(geo) for Hg and Cd; 2.50 and 3.09, respectively) was observed. Taken together, these results indicated that irrigation with wastewater damaged the soil quality over the long term and that metals more easily accumulated in vegetable fields than rice fields.

Evaluating grass strips trapping efficiency of sediments and herbicides

NASA Astrophysics Data System (ADS)

Burguet, Maria; Guzmán, Gema; de Luna, Elena; Taguas, Encarnación V.; Gómez, José Alfonso

2016-04-01

Water erosion and associated offsite contamination are major environmental risks in many Mediterranean crops such as olives or vineyards (Beaufoy, 2001; Gómez et al., 2011). The use of cover crops has been prescribed as a mitigation measure for both problems because permanent cover crops have demonstrated to reduce sediment and agrochemical loads (e.g. Gómez, 2009a, b). However, large uncertainty remains about its effectiveness degree to reduce sediment and agrochemical contribution to streams due to the limited number of available studies, and the large variability observed under field conditions (Taguas et al., 2012). Furthermore, the determination of sediment and herbicide sources using suitable sediment tracing/fingerprinting properties has been noted as one tool to evaluate the effectiveness and functioning of vegetated filters at the catchment scale (Koiter et al., 2013). The objectives of the present study were twofold: [1] to explore the combined use of natural and simulated rainfall and magnetic iron oxide in understanding the performance of vegetation strips on runoff and soil and herbicide losses at plot scale and, [2] to evaluate the effectiveness degree of vegetation strips in buffering sediment and herbicide from bare soil areas under different conditions compared to a control situation with no strips. This study encompasses six rainfall simulations under four different soil managements combining the use of a magnetic iron oxide as a sediment tracer to obtain a better understanding of the vegetation strips trapping efficiency. Three runoff plots of 6 m × 14 m were established in a 20% hillslope under a Fluvisol alluvial terrace. Each of the plots contained three bare strips tagged with magnetic iron oxide and three strips with Lolium multiflorum L. The soil management simulated scenarios were: immediately after sowing the vegetation cover (June 2011cover crop), with settled vegetation cover (June 2012cover crop), after 5 cm of deep ploughing (October 2013freshly tilled) and after ploughing and mechanically compacting the soil with a sheet metal (November 2013 consolidated surface). Our results indicate that by using cover crop strips, runoff and sediment losses were approximately 50 % and 12 % respectively lower than the measured values in bare consolidated and freshly tilled soil. The formation of microrelief steps after the first simulation also helped to reduce soil losses and runoff. Ploughed and compacted soil management showed the highest cumulative runoff and soil losses values (28 mm and 15 kg). Evident tracer selectivity from small particle size soil textures (clays) was observed as there was an enrichment of these particles in the collected sediment. These features contribute to explain the effects of the management and the vegetation on the sediment distribution in the hillslopes and must be taken into account when performing tracing studies as well as when using cover crop strips to mitigate offsite contamination by agrochemicals. Acknowledgements: The authors would like to thank Clemente Trujillo, Manuel Redondo and Azahara Ramos for their full help and support during the fieldwork. This study was supported by the Project P08-AGR-03925 (Andalusian Government), AGL2009-12936-C03-01 (Ministry of Science and Innovation), RESEL (Ministry of Agriculture, Food and Environment) and FEDER fund. The program JAE of the National Spanish Research Centre which provided grant support for the PhD project of the corresponding author is also thanked. References: Beaufoy, G. 2001. EU policies for olive farming. Unsustainable on all counts. BirdLife Internacional-WWF, Brussels. Gómez, J.A., Sobrinho, T.A, Giráldez, J.V., Fereres, E. 2009a. Soil management effects on runoff, erosion and soil properties in an olive grove of Southern Spain. Soil & Tillage Research 102: 5-13. Gómez, J.A., Guzmán, M.G., Giráldez, J.V., Fereres, E. 2009b. The influence of cover crops and tillage on water and sediment yield, and on nutrient, and organic matter losses in an olive orchard on a sandy loam soil. Soil Till Res 106: 137-144. Gómez, J.A., Llewellyn, C., Basch, G., Sutton, P. B., Dyson, J. S., Jones, C. A. 2011. The effects of cover crops and conventional tillage on soil and runoff loss in vineyards and olive groves in several Mediterranean countries. Soil Use and Management 27: 502 - 514. Koiter, A.J., Owens, P.N., Petticrew, E.L., Lobb, D.A. 2013. The behavioural characteristics of sediment properties and their implications for sediment fingerprinting as an approach for identifying sediment sources in river basins. Earth-Science Reviews 125: 24-42. Taguas, E.V., Burguet, M., Pérez, R., Ayuso, J.L., Gómez, J.A., 2012. Interpretation of the impact of different managements and the rainfall variability on the soil erosion in a Mediterranean olive orchard microcatchment. Geophysical Research Abstracts 14, EGU2012-10966.

Deposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints

USGS Publications Warehouse

Jackson, Andrew; Davila, Alfonso F.; Böhlke, John Karl; Sturchio, Neil C.; Sevanthi, Ritesh; Estrada, Nubia; Brundrett, Maeghan; Lacelle, Denis; McKay, Christopher P.; Poghosyan, Armen; Pollard, Wayne; Zacny, Kris

2016-01-01

The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources. We expand upon this work by evaluating permafrost soil/sediments in University Valley, located in the ultraxerous zone where both liquid water transport and marine influences are minimal. We determined the abundances of Cl−, NO3−, ClO4− and ClO3− in dry and ice-cemented soil/sediments, snow and glacier ice, and also characterized Cl− and NO3−isotopically. The data are not consistent with salt deposition in a sublimation till, nor with nuclear weapon testing fall-out, and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate, from minimal alteration in bare soils to significant alteration (photodegradation and/or volatilization) in snow and glacier ice. Ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions, likely due to percolation of snowmelt. Subtle changes in ClO4−/NO3− ratios and NO3− isotopic composition with depth and location may reflect both transport related fractionation and depositional history. Low molar ratios of ClO3−/ClO4− in surface soils compared to deposition and other arid systems suggest significant post depositional loss of ClO3−, possibly due to reduction by iron minerals, which may have important implications for oxy-chlorine species on Mars. Salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from ∼10 to 30 kyr near the glacier to 70–200 kyr near the valley mouth. The relatively young age of the salts and relatively low and homogeneous anion concentrations in the ice-cemented sediments point to either a mechanism of recent salt removal, or to relatively modern permafrost soils (<1 million years). Together, our results show that near surface salts in University Valley serve as an end-member of stratospheric sources not subject to biological processes or extensive remobilization.

Reservoir-flooded river mouth areas as sediment traps revealing erosion from peat mining areas - Jukajoki case study in eastern Finland

NASA Astrophysics Data System (ADS)

Tahvanainen, Teemu; Meriläinen, Henna-Kaisa; Haraguchi, Akira; Simola, Heikki

2016-04-01

Many types of soil-disturbing land use have caused excess sedimentation in Finnish lakes. Identification and quantification of catchment sources of sediment material is crucial in cases where demands for remediation measures are considered. We studied recent (50 yr) sediments of four small rivers, all draining to a reservoir impounded in 1971. Catchments of two of the rivers had had peat mining activities from early 1980s until recently, exposing large areas of peat surfaces to erosion. The water level of the reservoir had risen to the river mouth areas of all rivers, while in each case, the river mouth areas still form riverine narrows separable from the main reservoir, hence collecting sedimentation from their own catchments. The original soils under the reservoir water level could readily be observed in core samples, providing a dated horizon under recent sediments. In addition, we used 137Cs-stratigraphies for dating of samples from original river bed locations. As expected, recent sediments of rivers with peat mining influence differed from others e.g. by high organic content and C:N ratios. Stable isotopes 13C and 15N both correlated with C:N (r = 0.799 and r = -0.717, respectively) and they also differentiated the peat-mining influenced samples from other river sediments. Principal components of the physical-chemical variables revealed clearer distinction than any variables separately. Light-microscopy revealed abundance of leafs of Sphagnum mosses in peat-mining influenced river sediments that were nearly absent from other rivers. Spores of Sphagnum were, however, abundant in all river sediments indicating their predominantly airborne origin. We find that combination of several physical-chemical characters rather than any single variable and microscopy of plant remains can result in reliable recognition of peatland-origin of sediment material when non-impacted sites are available for comparison. Dating of disturbed recent sediments is challenging. River-mouth areas with reservoir history can be particularly useful as the terrestrial soil strata provides a dated horizon under recent sediments.

Soil erosion rates (particulate and dissolved fluxes) variations in a temperate river basin

NASA Astrophysics Data System (ADS)

Cerdan, Olivier; Gay, Aurore; Négrel, Philippe; Pételet-Giraud, Emmanuelle; Salvador Blanes, Sébastien; Degan, Francesca

2015-04-01

Soil erosion is one of the major drivers of landscape evolution in Western Europe. However, depending on the land use characteristics and on the geological and topographical settings, miscellaneous forms of erosion may lead to a very diverse morphological evolution. To understand these landscape evolutions different scientific questions remain to be answered or quantified. The main difficulty arises from the nonlinear interactions between different erosional processes that act at different temporal and spatial scales. This study proposes to investigate different datasets describing particulate and dissolved sediment fluxes within a French River basin (The Loire River) at different spatial scales and at temporal scales ranging from the flood event to several decades. The particulate sediment load values at the outlet of the catchments range from 2.5 102 to 8.6 105 t yr-1, and the sediment yield values range from 2.9 to 32.4 t km 2 yr-1. Sediment exports from the Loire and Brittany river basins are low compared with mountainous regions and European exports. However, a strong spatial variability within this territory exists. The expected results on the sediment yield spatial pattern distribution and the correlation between SY values and basin sizes are not observed. An analysis of the sediment yield values at different time steps shows a strong effect of the seasonal availability of detached particles to be transported. High concentrations of suspended sediments during the winter and lower values during the summer and autumn are observed. Inter-annual variations are also observed, with export values varying by a factor 2 to 10 between years for one catchment. The influence of rainfall on the sediment exports is predominant, but investigations on physical characteristics of each catchment (e.g., lithology, slope, land use) are required to better understand the production and transfer processes within a drainage basin. These inter-annual variations imply that long-term data are required to provide mean SY values representative of the catchment functioning. From our calculations, 18 complete years of data are required to obtain a mean sediment yield value with less than 10% of variation on average around the mean. The specific dissolved fluxes vary from 13.7 to 199.9 t.km-2. t yr-1. Contrary to particulate matters, the impact of the lithology is illustrated by higher total dissolved solid fluxes on limestone catchments compared with graniteous or schisteous catchments. Nitrates and ammonium are indicators of anthropogenic perturbation and their fluxes vary respectively from 0.4 to 31.4 t.km-2. yr-1 and from 7.8*10-3 to 7.7 t.km-2. yr-1 and evolve differently according to land uses: nitrates fluxes are lower in the upstream Loire and higher downstream in the region where agricultural pressure is higher. The analysis of these datasets at different spatial and temporal scales permits to identify some of the dominant processes, and also to distinguish natural from anthropogenic influences. Concerning upland physical soil surface erosion rates, we find that the average travel distance of eroded particles may be limited, implying a strong decrease in physical erosion rates when moving from the local scale (m²) to the river basin scale (> 103 km²). Chemical erosion rates are less sensitive to scale and can either decrease or increase with increasing area in function of lithology, land management and topography. The results also highlight the predominant role of surface connectivity to characterize the fraction of sediment exported out of river drainage areas by physical soil surface erosion. For the export of dissolved sediment originating from weathering processes, the catchment physiography and connectivity does no longer play the dominant role. A direct link between soil production rates and exported dissolved fluxes tends to show that, contrary to the suspended particles, which are transport-limited, the dissolved matter seems to be supply-limited.

Modelling evolution of air dose rates in river basins in Fukushima Prefecture affected by sediment-sorbed radiocesium redistribution

NASA Astrophysics Data System (ADS)

Malins, A.; Sakuma, K.; Nakanishi, T.; Kurikami, H.; Machida, M.; Kitamura, A.; Yamada, S.

2015-12-01

The radioactive 134Cs and 137Cs isotopes deposited over Fukushima Prefecture by the Fukushima Daiichi nuclear disaster are the predominant radiological concern for the years following the accident. This is because the energetic gamma radiation they emit on decay constitutes the majority of the elevated air dose rates that now afflict the region. Therefore, we developed a tool for calculating air dose rates from arbitrary radiocesium spatial distributions across the land surface and depth profiles within the ground. As cesium is strongly absorbed by clay soils, its primary redistribution mechanism within Fukushima Prefecture is by soil erosion and water-borne sediment transport. Each year between 0.1~1% of the total radiocesium inventory in the river basins neighboring Fukushima Daiichi is eroded from the land surface and enters into water courses, predominantly during typhoon storms. Although this is a small amount in relative terms, in absolute terms it corresponds to terabecquerels of 134Cs and 137Cs redistribution each year and this can affect the air dose rate at locations of high erosion and sediment deposition. This study inputs the results of sediment redistribution simulations into the dose rate evaluation tool to calculate the locations and magnitude of air dose rate changes due to radiocesium redistribution. The dose rate calculations are supported by handheld survey instrument results taken within the Prefecture.

SORPTION OF VINCLOZOLIN AND ATRAZINE ON FOUR GEOSORBENTS

EPA Science Inventory

The objectives of this study were to evaluate the magnitude and kinetics of vinclozolin and atrazine sorption on one surface soil and three freshwater sediments using batch and column techniques. Data from miscible displacement column studies were analyzed using a two-domain, fir...

PC-BASED SUPERCOMPUTING FOR UNCERTAINTY AND SENSITIVITY ANALYSIS OF MODELS

EPA Science Inventory

Evaluating uncertainty and sensitivity of multimedia environmental models that integrate assessments of air, soil, sediments, groundwater, and surface water is a difficult task. It can be an enormous undertaking even for simple, single-medium models (i.e. groundwater only) descr...

BIOMETHYLATION AND ENVIRONMENTAL TRANSPORT OF METALS

EPA Science Inventory

Toxic heavy metals are ubiquitous in the environment. They are found as metal or oxide dust in air, metal ions attached to humic substances in surface and ground water, and as metal ions bound to soils and sediments. The transformations, mobilization, transport, and bioaccumulati...

Stronger association of polycyclic aromatic hydrocarbons with soot than with char in soils and sediments

PubMed Central

Han, Y.M.; Bandowe, B.A.M.; Wei, C.; Cao, J.J.; Wilcke, W.; Wang, G.H.; Ni, H.Y.; Jin, Z.D.; An, Z.S.; Yan, B.Z.

2016-01-01

The knowledge of the association of polycyclic aromatic hydrocarbons (PAHs) with organic matter and carbonaceous materials is critical for a better understanding of their environmental transport, fate, and toxicological effects. Extensive studies have been done with regard to the relationship of PAHs with total organic carbon (TOC) and elemental carbon (EC) in different environmental matrices. The relationship between PAHs and the two subtypes of EC, char (combustion residues) and soot (produced via gas-to-particle conversion) also has been tested in field and laboratory experiments using reference materials. However, a direct comparison of associations of PAHs between with char and with soot in real environmental matrices has to our knowledge not yet been reported because of a lack of methodology to differentiate them. In this study, char and soot were measured using the IMPROVE method to test their associations with 12 EPA priority PAHs measured in topsoil samples (N = 22, top 10 cm) collected from the Guanzhong Plain and in surface sediment samples (N = 32, top 5 cm) from the Wei River (central China). In both soils and sediments, Σ12PAHs were more strongly associated with soot than with char, mainly due to the fact that soot and PAHs were produced in the same gas phase during combustion, had a strong affinity for each other, and were transported and deposited together, while char, the combustion residue, was transported differently to PAHs due to its large particle size. Stronger correlations between PAHs and the different carbon fractions (TOC, soot, and char) in sediments than in soils were observed, which is associated with the redistribution of PAHs among the organic matter pools in water because of the processes during soil erosion and sedimentation in the river. PMID:24656973

The impact of soil erosion on soil fertility and vine vigor. A multidisciplinary approach based on field, laboratory and remote sensing approaches.

PubMed

Novara, Agata; Pisciotta, Antonino; Minacapilli, Mario; Maltese, Antonino; Capodici, Fulvio; Cerdà, Artemi; Gristina, Luciano

2018-05-01

Soil erosion processes in vineyards, beyond surface runoff and sediment transport, have a strong effect on soil organic carbon (SOC) loss and redistribution along the slope. Variation in SOC across the landscape can determine differences in soil fertility and vine vigor. The goal of this research was to analyze the interactions among vines vigor, sediment delivery and SOC in a sloping vineyard located in Sicily. Six pedons were studied along the slope by digging 6 pits up to 60cm depth. Soil was sampled every 10cm and SOC, water extractable organic carbon (WEOC) and specific ultraviolet absorbance (SUVA) were analyzed. Erosion rates, detachment and deposition areas were measured by the pole height method which allowed mapping of the soil redistribution. The vigor of vegetation, expressed as Normalized Difference Vegetation Index (NDVI), derived from high-resolution satellite multispectral data, was compared with measured pruning weight. Results confirmed that soil erosion, sediment redistribution and SOC across the slope was strongly affected by topographic features, slope and curvature. The erosion rate was 16Mgha -1 y -1 since the time of planting (6years). SOC redistribution was strongly correlated with the detachment or deposition areas as highlighted by pole height measurements. The off-farm SOC loss over six years amounted to 1.2MgCha -1 . SUVA 254 values, which indicate hydrophobic material rich in aromatic constituents of WEOC, decreased significantly along the slope, demonstrating that WEOC in the detachment site is more stable in comparison to deposition sites. The plant vigor was strongly correlated with WEOC constituents. Results demonstrated that high resolution passive remote sensing data combined with soil and plant analyses can survey areas with contrasting SOC, soil fertility, soil erosion and plant vigor. This will allow monitoring of soil erosion and degradation risk areas and support decision-makers in developing measures for friendly environmental management. Copyright © 2017 Elsevier B.V. All rights reserved.

Biotransformation of tetrabromobisphenol A (TBBPA) in anaerobic digester sludge, soils, and freshwater sediments.

PubMed

McAvoy, Drew C; Pittinger, Charles A; Willis, Alison M

2016-09-01

The biotransformation of tetrabromobisphenol A (TBBPA) was evaluated in anaerobic digester sludge, soils, and freshwater sediments. In anaerobic digester sludge, TBBPA biotransformed rapidly with a 50% disappearance time (DT50) of 19 days, though little mineralization (1.1%) was observed. In aerobic soils, mineralization of TBBPA ranged from 17.5% to 21.6% with 55.3-83.6% of the TBBPA incorporated into the soils as a non-extractable bound residue. The DT50 for TBBPA in aerobic soils ranged from 5.3 to 7.7 days. In anaerobic soils, 48.3-100% of the TBBPA was incorporated into the soils as non-extractable bound residue with <4% mineralized. The soil fate studies demonstrated extensive incorporation of TBBPA into the solid matrix and this association was related to the amount of organic carbon in the soils (i.e., greater association of TBBPA with soil at higher organic carbon content). In anaerobic sediments the DT50 for TBBPA ranged from 28 to 42 days, whereas in aerobic sediments the DT50 for TBBPA ranged from 48 to 84 days and depended on the initial dose concentration. Most of the TBBPA in the sediment studies was incorporated as a non-extractable bound residue with little mineralization observed. Sediment extracts revealed three unknown biotransformation products and bisphenol A (BPA). These results were consistent with previously published studies where TBBPA biotransformed in anaerobic environments (digester sludge and sediments) by debromination and slowly mineralized in the test environments (anaerobic digester sludge, soils, and freshwater sediments). Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

On the non-uniqueness of the hydro-geomorphic responses in a zero-order catchment with respect to soil moisture

NASA Astrophysics Data System (ADS)

Kim, Jongho; Dwelle, M. Chase; Kampf, Stephanie K.; Fatichi, Simone; Ivanov, Valeriy Y.

2016-06-01

This study advances mechanistic interpretation of predictability challenges in hydro-geomorphology related to the role of soil moisture spatial variability. Using model formulations describing the physics of overland flow, variably saturated subsurface flow, and erosion and sediment transport, this study explores (1) why a basin with the same mean soil moisture can exhibit distinctly different spatial moisture distributions, (2) whether these varying distributions lead to non-unique hydro-geomorphic responses, and (3) what controls non-uniqueness in relation to the response type. Two sets of numerical experiments are carried out with two physically-based models, HYDRUS and tRIBS+VEGGIE+FEaST, and their outputs are analyzed with respect to pre-storm moisture state. The results demonstrate that distinct spatial moisture distributions for the same mean wetness arise because near-surface soil moisture dynamics exhibit different degrees of coupling with deeper-soil moisture and the process of subsurface drainage. The consequences of such variations are different depending on the type of hydrological response. Specifically, if the predominant runoff response is of infiltration excess type, the degree of non-uniqueness is related to the spatial distribution of near-surface moisture. If runoff is governed by subsurface stormflow, the extent of deep moisture contributing area and its "readiness to drain" determine the response characteristics. Because the processes of erosion and sediment transport superimpose additional controls over factors governing runoff generation and overland flow, non-uniqueness of the geomorphic response can be highly dampened or enhanced. The explanation is sediment composed by multi-size particles can alternate states of mobilization or surface shielding and the transient behavior is inherently intertwined with the availability of mobile particles. We conclude that complex nonlinear dynamics of hydro-geomorphic processes are inherent expressions of physical interactions. As complete knowledge of watershed properties, states, or forcings will always present the ultimate, if ever resolvable, challenge, deterministic predictability will remain handicapped. Coupling of uncertainty quantification methods and space-time physics-based approaches will need to evolve to facilitate mechanistic interpretations and informed practical applications.

[Contamination and Ecological Risk Assessment of Mercury in Hengshuihu Wetland, Hebei Province].

PubMed

Wang, Nai-shan; Zhang, Man-yin; Cui, Li-juan; Ma, Mu-yuan; Yan, Liang; Mu, Yong-lin; Qin, Peng

2016-05-15

Investigation on the concentrations and the distribution characteristics of total mercury in atmosphere, water surface and soil/ sediments of Hengshuihu wetland was carried out based on a uniform set point sampling method. The geoaccumulation index and potential ecological risk index methods were simultaneously used to assess the mercury pollution in Hengshuihu wetland ecosystem. The results showed that: the total mercury content in Hengshuihu wetland atmosphere ranged from 1.0 to 5.0 ng · m⁻³, with an average of (2.9 ± 0.85) ng · m⁻³; the total mercury content in water surface ranged from 0.010 to 0.57 µg · L⁻¹, with the average value of (0.081 ± 0.053) µg · L⁻¹; the total mercury content in soil/sediment ranged from 0.001 0 to 0.058 mg · kg⁻¹, with an average of (0.027 ± 0.013) mg · kg⁻¹. The distribution features of total mercury in Hengshuihu wetland were as follows: the total mercury concentration in surface water of the shore was significantly higher than that in the center (P < 0.05), but the total mercury concentration of sediments in the center of the lake was significantly higher than that at the shore (P < 0.05); the total mercury in the soil of shore had a consistent trend with that in the atmosphere; high concentrations of total mercury pollution were accompanied by severe human activities. The geoaccumulation index showed that mercury pollution in Hengshuihu wetland was at clean level; potential ecological risk index showed mercury contamination had a low ecological risk in Hengshuihu wetland.

Water quality impact assessment of agricultural Beneficial Management Practices (BMPs) simulated for a regional catchment in Quebec, Eastern Canada

NASA Astrophysics Data System (ADS)

Rousseau, Alain N.; Hallema, Dennis W.; Gumiere, Silvio J.; Savary, Stéphane; Hould Gosselin, Gabriel

2014-05-01

Water quality has become a matter of increasing concern over the past four decades as a result of the intensification of agriculture, and more particularly so in Canada where agriculture has evolved into the largest non-point source of surface water pollution. The Canadian WEBs project (Watershed Evaluation of Beneficial Management Practices, BMPs) was initiated in order to determine the efficiency of BMPs in improving the surface water quality of rural catchments, and the economic aspects related to their implementation on the same scale. In this contribution we use the integrated watershed modelling platform GIBSI (Gestion Intégrée des Bassins versants à l'aide d'un Système Informatisé) to evaluate the effects of various BMPs on sediment and nutrient yields and, in close relation to this, the surface water quality for the Beaurivage River catchment (718 km2) in Quebec, eastern Canada. A base scenario of the catchment is developed by calibrating the different models of the GIBSI platform, namely HYDROTEL for hydrology, the Revised Universal Soil Loss Equation (RUSLE) for soil erosion, the Erosion-Productivity Impact Calculator (EPIC) of the Soil and Water Assessment Tool (SWAT) for contaminant transport and fate, and QUAL2E for stream water quality. Four BMPs were analysed: (1) vegetated riparian buffer strips, (2) precision slurry application, (3) transition of all cereal and corn fields to grassland (grassland conversion), and (4) no-tillage on corn fields. Simulations suggest that riparian buffer strips and grassland conversion are more effective in terms of phosphorus, nitrogen and sediment load reduction than precision slurry application and no-tillage on corn fields. The results furthermore indicate the need for a more profound understanding of sediment dynamics in streams and on riparian buffer strips.

Determination of biocides in different environmental matrices by use of ultra-high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Chen, Zhi-Feng; Ying, Guang-Guo; Lai, Hua-Jie; Chen, Feng; Su, Hao-Chang; Liu, You-Sheng; Peng, Fu-Qiang; Zhao, Jian-Liang

2012-12-01

A sensitive and robust method using solid-phase extraction and ultrasonic extraction for preconcentration followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS) has been developed for determination of 19 biocides: eight azole fungicides (climbazole, clotrimazole, ketoconazole, miconazole, fluconazole, itraconazole, thiabendazole, and carbendazim), two insect repellents (N,N-diethyl-3-methylbenzamide (DEET), and icaridin (also known as picaridin)), three isothiazolinone antifouling agents (1,2-benzisothiazolinone (BIT), 2-n-octyl-4-isothiazolinone (OIT), and 4,5-dichloro-2-n-octyl-isothiazolinone (DCOIT)), four paraben preservatives (methylparaben, ethylparaben, propylparaben, and butylparaben), and two disinfectants (triclosan and triclocarban) in surface water, wastewater, sediment, sludge, and soil. Recovery of the target compounds from surface water, influent, effluent, sediment, sludge, and soil was mostly in the range 70-120%, with corresponding method quantification limits ranging from 0.01 to 0.31 ng L(-1), 0.07 to 7.48 ng L(-1), 0.01 to 3.90 ng L(-1), 0.01 to 0.45 ng g(-1), 0.01 to 6.37 ng g(-1), and 0.01 to 0.73 ng g(-1), respectively. Carbendazim, climbazole, clotrimazole, methylparaben, miconazole, triclocarban, and triclosan were detected at low ng L(-1) (or ng g(-1)) levels in surface water, sediment, and sludge-amended soil. Fifteen target compounds were found in influent samples, at concentrations ranging between 0.4 (thiabendazole) and 372 ng L(-1) (methylparaben). Fifteen target compounds were found in effluent samples, at concentrations ranging between 0.4 (thiabendazole) and 114 ng L(-1) (carbendazim). Ten target compounds were found in dewatered sludge samples, at concentrations ranging between 1.1 (DEET) and 887 ng g(-1) (triclocarban).

Deforestation, Madagascar

NASA Image and Video Library

1990-04-29

This high oblique view shows the majority of the island of Madagascar (19.0S, 47.5E). This Texas sized island is now largely deforested and is suffering from severe soil erosion as well as a declining biological species diversity and productivity. At the turn of the century, the island was almost totally forested but now, forests cover only about 10 percent of the surface. Evidence of soil erosion can be seen in the offshore sediment plumes.

Deforestation, Madagascar

NASA Technical Reports Server (NTRS)

1990-01-01

This high oblique view shows the majority of the island of Madagascar (19.0S, 47.5E). This Texas sized island is now largely deforested and is suffering from severe soil erosion as well as a declining biological species diversity and productivity. At the turn of the century, the island was almost totally forested but now, forests cover only about 10 percent of the surface. Evidence of soil erosion can be seen in the offshore sediment plumes.

Deforestation, Madagascar

NASA Technical Reports Server (NTRS)

1989-01-01

This high oblique view shows the majority of the island of Madagascar (22.0S, 45.5E). This Texas sized island is now largely deforested and is suffering from severe soil erosion as well as a declining biological species diversity and productivity. At the turn of the century, the island was almost totally forested but now, forests cover only about 10 percent of the surface. Evidence of soil erosion can be seen in the offshore sediment plumes.

The Use of LiDAR Elevation Data and Satellite Imagery to Locate Critical Source Areas to Diffuse Pollution in Agricultural Watersheds

NASA Astrophysics Data System (ADS)

Drouin, Ariane; Michaud, Aubert; Thériault, Georges; Beaudin, Isabelle; Rodrigue, Jean-François; Denault, Jean-Thomas; Desjardins, Jacques; Côté, Noémi

2013-04-01

In Quebec / Canada, water quality improvement in rural areas greatly depends on the reduction of diffuse pollution. Indeed, point source pollution has been reduced significantly in Canada in recent years by creating circumscribed pits for manure and removing animals from stream. Diffuse pollution differs from point source pollution because it is spread over large areas. In agricultural areas, sediment loss by soil and riverbank erosion along with loss of nutrients (phosphorus, nitrogen, etc.) and pesticides from fields represent the main source of non-point source pollution. The factor mainly responsible for diffuse pollution in agricultural areas is surface runoff occurring in poorly drained areas in fields. The presence of these poorly drained areas is also one of the most limiting factors in crop productivity. Thus, a reconciliation of objectives at the farm (financial concern for farmers) and off-farm concerns (environmental concern) is possible. In short, drainage, runoff, erosion, water quality and crop production are all interconnected issues that need to be tackled together. Two complementary data sources are mainly used in the diagnosis of drainage, surface runoff and erosion : elevation data and multispectral satellite images. In this study of two watersheds located in Québec (Canada), LiDAR elevation data and satellite imagery (QuickBird, Spot and Landsat) were acquired. The studied territories have been partitioned in hydrologic response units (HRUs) according to sub-basins, soils, elevation (topographic index) and land use. These HRUs are afterwards used in a P index software (P-Edit) that calculates the quantities of sediments and phosphorus exported from each HRUs. These exports of sediments and phosphorus are validated with hydrometric and water quality data obtain in two sub-basins and are also compared to soil brightness index derived from multispectral images. This index is sensitive to soil moisture and thus highlights areas where the soil is more humid. A variety of other indices are used to explain the sediments yields. These indices, such as the average percentage of slope, the distance to the stream, the relative position in landscape, the position to the water table, etc. are mainly derived from high precision elevation data. All these data are used to locate critical source areas that generally correspond to a restraint part of the territory but account for the principal amount of sediments exports. Once the critical source areas are identified, best management practices (BMPs) (per example : contaminant source control practices, conservation cropping practices and surface runoff control structures) can be planned. This way, money and energy are used where it really counts. In this presentation, the complete methodology including LiDAR data processing will be explained. The results and the possibility to reproduce the developed method will be discussed.

Spatial patterns of plant litter in a tidal freshwater marsh and implications for marsh persistence.

PubMed

Elmore, Andrew J; Engelhardt, Katharina A M; Cadol, Daniel; Palinkas, Cindy M

2016-04-01

The maintenance of marsh platform elevation under conditions of sea level rise is dependent on mineral sediment supply to marsh surfaces and conversion of above- and belowground plant biomass to soil organic material. These physical and biological processes interact within the tidal zone, resulting in elevation-dependent processes contributing to marsh accretion. Here, we explore spatial pattern in a variable related to aboveground biomass, plant litter, to reveal its role in the maintenance of marsh surfaces. Plant litter persisting through the dormant season represents the more recalcitrant portion of plant biomass, and as such has an extended period of influence on ecosystem processes. We conducted a field and remote sensing analysis of plant litter height, aboveground biomass, vertical cover, and stem density (collectively termed plant litter structure) at a tidal freshwater marsh located within the Potomac River estuary, USA. LiDAR and field observations show that plant litter structure becomes more prominent with increasing elevation. Spatial patterns in litter structure exhibit stability from year to year and correlate with patterns in soil organic matter content, revealed by measuring the loss on ignition of surface sediments. The amount of mineral material embedded within plant litter decreases with increasing elevation, representing an important tradeoff with litter structure. Therefore, at low elevations where litter structure is short and sparse, the role of plant litter is to capture sediment; at high elevations where litter structure is tall and dense, aboveground litter contributes organic matter to soil development. This organic matter contribution has the potential to eclipse that of belowground biomass as the root:shoot ratio of dominant species at high elevations is low compared to that of dominant species at low elevations. Because of these tradeoffs in mineral and organic matter incorporation into soil across elevation gradients, the rate of marsh surface elevation change is remarkably consistent across elevation. Because of the role of plant litter in marsh ecosystem processes, monitoring and assessment of these dynamic geomorphic marsh landscapes might be streamlined through the measurement of plant litter structure, either via LiDAR technologies or field observation.

Kd Values for Agricultural and Surface Soils for Use in Hanford Site Farm, Residential, and River Shoreline Scenarios

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

Serne, R. Jeffrey

This report provides best estimate Kd values and a minimum and maximum range of Kd values to be used for agricultural soils and Columbia River bank sediments that exist today or would exist in the future when portions of the Hanford Site are released for farming, residential, and recreational use after the U. S. Department of Energy (DOE) completes clean up of defense waste on the site. The Kd values should be used to determine the fate and transport rates of contaminants and their availability for plant and animal uptake in selected non-groundwater scenarios included in Hanford Site environmental impactmore » statements, risk assessments and specific facility performance assessments. This report describes scenarios such as a small farm where drilling of a well inadvertently goes through buried waste and brings waste to the surface, allowing the tailings to become available for direct human exposure or incorporation into garden crops and farm animals used for food by the farm family. The Kd values recommended in this report can also be used to calculate sediment-water partitioning factors used to predict plant and animal uptake from interaction with the contaminated soil.« less

Predicting improved optical water quality in rivers resulting from soil conservation actions on land.

PubMed

Dymond, J R; Davies-Colley, R J; Hughes, A O; Matthaei, C D

2017-12-15

Deforestation in New Zealand has led to increased soil erosion and sediment loads in rivers. Increased suspended fine sediment in water reduces visual clarity for humans and aquatic animals and reduces penetration of photosynthetically available radiation to aquatic plants. To mitigate fine-sediment impacts in rivers, catchment-wide approaches to reducing soil erosion are required. Targeting soil conservation for reducing sediment loads in rivers is possible through existing models; however, relationships between sediment loads and sediment-related attributes of water that affect both ecology and human uses of water are poorly understood. We present methods for relating sediment loads to sediment concentration, visual clarity, and euphotic depth. The methods require upwards of twenty concurrent samples of sediment concentration, visual clarity, and euphotic depth at a river site where discharge is measured continuously. The sediment-related attributes are related to sediment concentration through regressions. When sediment loads are reduced by soil conservation action, percentiles of sediment concentration are necessarily reduced, and the corresponding percentiles of visual clarity and euphotic depth are increased. The approach is demonstrated on the Wairua River in the Northland region of New Zealand. For this river we show that visual clarity would increase relatively by approximately 1.4 times the relative reduction of sediment load. Median visual clarity would increase from 0.75m to 1.25m (making the river more often suitable for swimming) after a sediment load reduction of 50% associated with widespread soil conservation on pastoral land. Likewise euphotic depth would increase relatively by approximately 0.7 times the relative reduction of sediment load, and the median euphotic depth would increase from 1.5m to 2.0m with a 50% sediment load reduction. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-time monitoring of subsurface microbial metabolism with graphite electrodes

DOE PAGES

Wardman, Colin; Nevin, Kelly P.; Lovley, Derek R.

2014-11-21

Monitoring in situ microbial activity in anoxic submerged soils and aquatic sediments can be labor intensive and technically difficult, especially in dynamic environments in which a record of changes in microbial activity over time is desired. Microbial fuel cell concepts have previously been adapted to detect changes in the availability of relatively high concentrations of organic compounds in waste water but, in most soils and sediments, rates of microbial activity are not linked to the concentrations of labile substrates, but rather to the turnover rates of the substrate pools with steady state concentrations in the nM-μ M range. In ordermore » to determine whether levels of current produced at a graphite anode would correspond to the rates of microbial metabolism in anoxic sediments, small graphite anodes were inserted in sediment cores and connected to graphite brush cathodes in the overlying water. Currents produced were compared with the rates of [2- 14C]-acetate metabolism. There was a direct correlation between current production and the rate that [2- 14C]-acetate was metabolized to 14CO 2 and 14CH 4 in sediments in which Fe(III) reduction, sulfate reduction, or methane production was the predominant terminal electron-accepting process. At comparable acetate turnover rates, currents were higher in the sediments in which sulfate-reduction or Fe(III) reduction predominated than in methanogenic sediments. This was attributed to reduced products (Fe(II), sulfide) produced at distance from the anode contributing to current production in addition to the current that was produced from microbial oxidation of organic substrates with electron transfer to the anode surface in all three sediment types. In conclusion, the results demonstrate that inexpensive graphite electrodes may provide a simple strategy for real-time monitoring of microbial activity in a diversity of anoxic soils and sediments.« less

Enhancement of the surface methane hydrate-bearing layer based on the specific microorganisms form deep seabed sediment in Japan Sea.

NASA Astrophysics Data System (ADS)

Hata, T.; Yoneda, J.; Yamamoto, K.

2017-12-01

A methane hydrate-bearing layer located near the Japan Sea has been investigated as a new potential energy resource. In this study examined the feasibility of the seabed surface sediment strength located in the Japan Sea improvement technologies for enhancing microbial induced carbonate precipitation (MICP) process. First, the authors cultivated the specific urease production bacterium culture medium from this surface methane hydrate-bearing layer in the seabed (-600m depth) of Japan Sea. After that, two types of the laboratory test (consolidated-drained triaxial tests) were conducted using this specific culture medium from the seabed in the Japan Sea near the Toyama Prefecture and high urease activities bacterium named Bacillus pasteurii. The main outcomes of this research are as follows. 1) Specific culture medium focused on the urease production bacterium can enhancement of the urease activities from the methane hydrate-bearing layer near the Japan Sea side, 2) This specific culture medium can be enhancement of the surface layer strength, 3) The microbial induced carbonate precipitation process can increase the particle size compared to that of the original particles coating the calcite layer surface, 4) The mechanism for increasing the soil strength is based on the addition of cohesion like a cement stabilized soil.

Rainfall and sheet power model for interrill erosion in steep slope

NASA Astrophysics Data System (ADS)

Shin, Seung Sook; Deog Park, Sand; Nam, Myeong Jun

2015-04-01

The two-phase process of interrill erosion consist of the splash and detachment of individual particles from soil mass by impact of raindrops and the transport by erosive running water. Most experimental results showed that the effect of interaction between rainfall impact and surface runoff increases soil erosion in low or gentle slope. Especially, the combination of rain splash and sheet flow is the dominant runoff and erosion mechanism occurring on most steep hillslopes. In this study, a rainfall simulation was conducted to evaluate interrill erosion in steep slope with cover or non-cover. The kinetic energy of raindrops of rainfall simulator was measured by disdrometer used to measure the drop size distribution and velocity of falling raindrops and showed about 0.563 rate of that calculated from empirical equation between rainfall kinetic energy and rainfall intensity. Surface and subsurface runoff and sediment yield depended on rainfall intensity, gradient of slope, and existence of cover. Sediment from steep plots under rainfall simulator is greatly reduced by existence of the strip cover that the kinetic energy of raindrop approximates to zero. Soil erosion in steep slope with non-cover was nearly 4.93 times of that measured in plots with strip cover although runoff was only 1.82 times. The equation of a rainfall and sheet power was used to evaluate sediment yields in steep slope with cover or non-cover. The power model successfully explained physical processes for interrill erosion that combination of raindrop impact and sheet flow increases greatly soil erosion in steep slope. This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology(No. 2013R1A1A3011962).

Leachates draining from controlled municipal solid waste landfill: Detailed geochemical characterization and toxicity tests.

PubMed

Mavakala, Bienvenu K; Le Faucheur, Séverine; Mulaji, Crispin K; Laffite, Amandine; Devarajan, Naresh; Biey, Emmanuel M; Giuliani, Gregory; Otamonga, Jean-Paul; Kabatusuila, Prosper; Mpiana, Pius T; Poté, John

2016-09-01

Management of municipal solid wastes in many countries consists of waste disposal into landfill without treatment or selective collection of solid waste fractions including plastics, paper, glass, metals, electronic waste, and organic fraction leading to the unsolved problem of contamination of numerous ecosystems such as air, soil, surface, and ground water. Knowledge of leachate composition is critical in risk assessment of long-term impact of landfills on human health and the environment as well as for prevention of negative outcomes. The research presented in this paper investigates the seasonal variation of draining leachate composition and resulting toxicity as well as the contamination status of soil/sediment from lagoon basins receiving leachates from landfill in Mpasa, a suburb of Kinshasa in the Democratic Republic of the Congo. Samples were collected during the dry and rainy seasons and analyzed for pH, electrical conductivity, dissolved oxygen, soluble ions, toxic metals, and were then subjected to toxicity tests. Results highlight the significant seasonal difference in leachate physicochemical composition. Affected soil/sediment showed higher values for toxic metals than leachates, indicating the possibility of using lagoon system for the purification of landfill leachates, especially for organic matter and heavy metal sedimentation. However, the ecotoxicity tests demonstrated that leachates are still a significant source of toxicity for terrestrial and benthic organisms. Therefore, landfill leachates should not be discarded into the environment (soil or surface water) without prior treatment. Interest in the use of macrophytes in lagoon system is growing and toxic metal retention in lagoon basin receiving systems needs to be fully investigated in the future. This study presents useful tools for evaluating landfill leachate quality and risk in lagoon systems which can be applied to similar environmental compartments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Membrane-micelle model for humus in soils and sediments and its relation to humification

USGS Publications Warehouse

Wershaw, Robert L.

1994-01-01

Humification, the process whereby biomass consisting of dead plant and animal remains is converted into soil organic matter (humus), is one of the basic processes of the carbon cycle. The organic compounds that make up plant and animal tissue are thermodynamically unstable in the oxidizing atmosphere at the surface of the Earth. After the organisms in which they are incorporated die, the compounds are converted back to carbon dioxide and water by degradation reactions catalyzed by enzymes secreted by micro-organisms. However, not all the organic compounds in the dead biomass are immediately converted; some of the material is only partially oxidized. The residue left after partial oxidative degradation of the dead biomass is the source of the organic compounds that accumulate in soils and sediments as humus. Previously, humification was thought to involve a conversion of degradation products by a series of polymerization reactions into new types of polymeric species that are different from the precursor molecular species in the original biomass. However, it is proposed here that the depolymerization and oxidation reactions that take place during the enzymatic degradation of biopolymers produce amphiphiles--molecules that have a polar (hydrophilic) part and a nonpolar (hydrophobic) part. These amphiphiles that result from the partial oxidative degradation of dead biomass assemble spontaneously into ordered aggregates in which the hydrophobic parts of the molecules form the interiors and the hydrophilic parts of the molecules make up the exterior surfaces of the aggregates. These ordered aggregates constitute the humus in soils and sediments. Humus ordered aggregates most likely exist as bilayer membranes coating mineral grains and as micelles in solution.

Nitrogen enrichment in runoff sediments as affected by soil texture in Beijing mountain area.

PubMed

Yang, Yang; Ye, Zhihan; Liu, Baoyuan; Zeng, Xianqin; Fu, Suhua; Lu, Bingjun

2014-02-01

Enrichment ratio (ER) is widely used in nonpoint source pollution models to estimate the nutrient loss associated with soil erosion. The objective of this study was to determine the ER of total nitrogen (ERN) in the sediments eroded from the typical soils with varying soil textures in Beijing mountain area. Each of the four soils was packed into a 40 by 30 by 15 cm soil pan and received 40-min simulated rainfalls at the intensity of 90 mm h(-1) on five slopes. ERN for most sediments were above unity, indicating the common occurrence of nitrogen enrichment accompanied with soil erosion in Beijing mountain area. Soil texture was not the only factor that influenced N enrichment in this experiment since the ERN for the two fine-textured soils were not always lower. Soil properties such as soil structure might exert a more important influence in some circumstances. The selective erosion of clay particles was the main reason for N enrichment, as implied by the significant positive correlation between the ER of total nitrogen and clay fraction in eroded sediments. Significant regression equations between ERN and sediment yield were obtained for two pairs of soils, which were artificially categorized by soil texture. The one for fine-textured soils had greater intercept and more negative slope. Thus, the initially higher ERN would be lower than that for the other two soils with coarser texture once the sediment yield exceeded 629 kg ha(-1).

River Sediment Monitoring Using Remote Sensing and GIS (case Study Karaj Watershed)

NASA Astrophysics Data System (ADS)

Shafaie, M.; Ghodosi, H.; Mostofi, K. H.

2015-12-01

Whereas the tank volume and dehydrating digits from kinds of tanks are depended on repository sludge, so calculating the sediments is so important in tank planning and hydraulic structures. We are worry a lot about soil erosion in the basin area leading to deposit in rivers and lakes. It holds two reasons: firstly, because the surface soil of drainage would lose its fertility and secondly, the capacity of the tank decreases also it causes the decrease of water quality in downstream. Several studies have shown that we can estimate the rate of suspension sediments through remote sensing techniques. Whereas using remote sensing methods in contrast to the traditional and current techniques is faster and more accurate then they can be used as the effective techniques. The intent of this study has already been to estimate the rate of sediments in Karaj watershed through remote sensing and satellite images then comparing the gained results to the sediments data to use them in gauge-hydraulic station. We mean to recognize the remote sensing methods in calculating sediment and use them to determine the rate of river sediments so that identifying their accuracies. According to the results gained of the shown relations at this article, the amount of annual suspended sedimentary in KARAJ watershed have been 320490 Tones and in hydrologic method is about 350764 Tones .

EarthShape: A Strategy for Investigating the Role of Biota on Surface Processes

NASA Astrophysics Data System (ADS)

Ehlers, T. A.; von Blanckenburg, F.; Übernickel, K.; Paulino, L.

2016-12-01

EarthShape - "Earth surface shaping by biota" is a 6-year priority research program funded by the German science foundation (DFG-SPP 1803) that performs soil- and landscape-scale critical zone research at 4 locations along a climate gradient in the Chilean Coastal Cordillera. This region was selected because of its north-south orientation such that it captures a large ecological and climate gradient ranging from hyper-arid to temperate to humid conditions. The sites comprise granitic, previously unglaciated mountain ranges. EarthShape involves an interdisciplinary collaboration between geologists, geomorphologists, ecologists, soil scientists, microbiologists, geophysicists, geochemists, and hydrogeologists including 18 German and 8 Chilean institutions. EarthShape is composed of 4 research clusters representing the process chain from weathering of substrate to deposition of eroded material. Cluster 1 explores micro-biota as the "weathering engine". Investigations in this cluster quantify different mechanisms of biogenic weathering whereby plants, fungi, and bacteria interact with rock in the production of soil. Cluster 2 explores bio-mediated redistribution of material within the weathering zone. Studies in this cluster focus on soil catenas along hill slope profiles to investigate the modification of matter along its transport path. Cluster 3 explores biotic modulation of erosion and sediment routing at the catchment scale. Investigations in this cluster explore the effects of vegetation cover on solute and sediment transport from hill slopes to the channel network. Cluster 4 explores the depositional legacy of coupled biogenic and Earth surface systems. This cluster investigates records of vegetation-land surface interactions in different depositional settings. A final component of EarthShape lies in the integration of results from these 4 clusters using numerical models to bridging between the diverse times scales used by different disciplines.

Post-fire mulching and soil hydrological response

NASA Astrophysics Data System (ADS)

Jordán, Antonio; Zavala, Lorena M.; Gordillo-Rivero, Ángel J.; Muñoz-Rojas, Miriam; Keesstra, Saskia; Cerdà, Artemi

2017-04-01

In general, one of the major threats after a forest fire is the increased erosion. This can occur due to the erosive impact of rainfall after a drastic reduction of vegetation cover or to changes in soil surface properties that contribute to enhanced runoff flow. There is a consensus among researchers that one of the best ways to reduce this risk is to apply a mulch cover (straw, shredded wood or other materials) immediately after fire. In this study, we studied the effectiveness of various types of mulch materials for the reduction of runoff and soil loss during the first 3 years after a forest fire, in plots of different sizes, with special attention to water repellency and physical properties of the soil surface. In general, straw mulch reduced both runoff and erosion rate more than other treatments. However, the effect was much more important on larger plots. This may be due to specific processes and impacts on sediment connectivity and surface water flow. Therefore, the effect of the scale seems to be an important factor in the management of burnt soils.

Per- and Polyfluoroalkyl Substances (PFAS): Sampling ...

EPA Pesticide Factsheets

Per- and polyfluoroalkyl substances (PFAS) are a large group of manufactured compounds used in a variety of industries, such as aerospace, automotive, textiles, and electronics, and are used in some food packaging and firefighting materials. For example, they may be used to make products more resistant to stains, grease and water. In the environment, some PFAS break down very slowly, if at all, allowing bioaccumulation (concentration) to occur in humans and wildlife. Some have been found to be toxic to laboratory animals, producing reproductive, developmental, and systemic effects in laboratory tests. EPA's methods for analyzing PFAS in environmental media are in various stages of development. This technical brief summarizes the work being done to develop robust analytical methods for groundwater, surface water, wastewater, and solids, including soils, sediments, and biosolids. The U.S. Environmental Protection Agency’s (EPA) methods for analyzing PFAS in environmental media are in various stages of development. EPA is working to develop robust analytical methods for groundwater, surface water, wastewater, and solids, including soils, sediments, and biosolids.

Geomorphic considerations for erosion prediction

USGS Publications Warehouse

Osterkamp, W.R.; Toy, T.J.

1997-01-01

Current soil-erosion prediction technology addresses processes of rainsplash, overland-flow sediment transport, and rill erosion in small watersheds. The effects of factors determining sediment yield from larger-scale drainage basins, in which sediment movement is controlled by the combined small-scale processes and a complex set of channel and other basin-scale sediment-delivery processes, such as soil creep, bioturbation, and accelerated erosion due to denudation of vegetation, have been poorly evaluated. General suggestions are provided for the development of erosion-prediction technology at the geomorphic or drainage-basin scale based on the separation of sediment-yield data for channel and geomorphic processes from those of field-scale soil loss. An emerging technology must consider: (1) the effects on sediment yield of climate, geology and soils, topography, biotic interactions with other soil processes, and land-use practices; (2) all processes of sediment delivery to a channel system; and (3) the general tendency in most drainage basins for progressively greater sediment storage in the downstream direction.

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.

Overland flow generation mechanisms affected by topsoil treatment: Application to soil conservation

NASA Astrophysics Data System (ADS)

González Paloma, Hueso; Juan Francisco, Martinez-Murillo; Damian, Ruiz-Sinoga Jose; Hanoch, Lavee

2015-04-01

Hortonian overland-flow is responsible for significant amounts of soil loss in Mediterranean geomorphological systems. Restoring the native vegetation is the most effective way to control runoff and sediment yield. During the seeding and plant establishment, vegetation cover may be better sustained if soil is amended with an external source. Four amendments were applied in an experimental set of plots: straw mulching (SM); mulch with chipped branches of Aleppo Pine (Pinus halepensis L.) (PM); TerraCotten hydroabsobent polymers (HP); sewage sludge (RU); and control (C). Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha-1. This research demonstrates the role played by the treatments in overland flow generation mechanism (runoff, overland flow and soil moisture along the soil profile). The general overland flow characteristics showed that in the C plots the average overland flow was 8.0 ± 22.0 l per event, and the HP plots produced a similar mean value (8.1 ± 20.1 l). The average overland flow per event was significantly less for soil amended with SM, PM or RU (2.7 ± 8.3 l; 1.3 ± 3.5 l and 2.2 ± 5.9 l, respectively). There was a similar trend with respect to the maximum overland flow. The mean sediment yield per event was relatively high in the C and HP plots (8.6 ± 27.8 kg and 14.8 ± 43.4 kg, respectively), while significantly lower values were registered in the SM, PM and RU plots (0.4 ± 1.0 kg; 0.2 ± 0.3 kg and 0.2 ± 0.3 kg, respectively). Very similar trends were found for the maximum sediment yield. Regarding to the soil moisture values, there was a difference in the trends between the C and HP plots and the SM, PM and RU plots. In the C and HP plots the general trend was for a decrease in soil moisture downward through the soil profile, while in the SM, PM and RU plots the soil moisture remained relatively constant or increased, except for the RU treatment in which the soil moisture decreased from 5 to 10 cm depth. According to the results, the hydrological and erosive response in the five treatments showed dissimilarities, despite having similar rainfall exposure and the same original soil properties. This means that the differences between the treatments play a key role in the soil moisture, overland flow and sediment yield values. The study has demonstrated the effects of various treatments on the generation of overland flow, and hence the sediment yield. In the C and HP plots, relatively large amounts of overland flow rapidly developed. This cannot be explained by saturation conditions, as the soil moisture content was highest near the surface and decreased with depth in the profile. This, together with the relatively low macro-porosity, proved that the mechanism of overland flow generation was of the Hortonian type. On the other hand, in the SM and PM plots, the high level of macro-porosity, together with the increase in soil moisture content with depth, explained the small quantities of overland flow and sediment yield. In the rare case that overland flow developed in these plots, it was minor in amount, and yielded little sediment because of saturation conditions. The processes in the RU plots were more complicated; from 10 cm depth the soil moisture content always increased with further depth, usually rapidly. Thus, water infiltrated continuously and there was no rainfall excess. Therefore, in terms of overland flow and sediment yield, the RU plots behaved in a similar way to the SM and PM plots. The fact that the soil moisture content was low at depths of 10 cm is because of the uptake of water at these depths by the roots of Carlina hispanica Lam. From a land management standpoint, the SM, PM and RU treatments were the most effective in reducing overland flow and sediment yield following afforestation. In addition, the soil profile became more wettable, which provided more water to support plant survival. However, when afforestation was combined with RU treatment, the vegetation cover resulting from the amendment treatment was the main factor controlling the hydrological processes. Application of the HP treatment caused a decrease in soil moisture content with depth in the soil profile, and overland flow and sediment yield were maximum in this treatment.

Global Soil and Sediment transfer during the Anthropocene

NASA Astrophysics Data System (ADS)

Hoffmann, Thomas; Vanacker, Veerle; Stinchcombe, Gary; Penny, Dan; Xixi, Lu

2016-04-01

The vulnerability of soils to human-induced erosion and its downstream effects on fluvial and deltaic ecosystems is highly variable in space and time; dependent on climate, geology, the nature and duration of land use, and topography. Despite our knowledge of the mechanistic relationships between erosion, sediment storage, land-use and climate change, the global patterns of soil erosion, fluvial sediment flux and storage throughout the Holocene remain poorly understood. The newly launched PAGES working group GloSS aims to determine the sensitivity of soil resources and sediment routing systems to varying land use types during the period of agriculture, under contrasting climate regimes and socio-ecological settings. Successfully addressing these questions in relation to the sustainable use of soils, sediments and river systems requires an understanding of past human-landscape interactions. GloSS, therefore, aims to: Develop proxies for, or indices of, human impact on rates of soil erosion and fluvial sediment transfer that are applicable on a global scale and throughout the Holocene; Create a global database of long-term (102-104 years) human-accelerated soil erosion and sediment flux records; Identify hot spots of soil erosion and sediment deposition during the Anthropocene, and Locate data-poor regions where particular socio-ecological systems are not well understood, as strategic foci for future work. This paper will present the latest progress of the PAGES GloSS working group.

Transfer of fallout radionuclides derived from Fukushima NPP accident: 1 year study on transfer of radionuclides through geomorphic processes

NASA Astrophysics Data System (ADS)

Onda, Y.; Kato, H.; Fukushima, T.; Wakahara, T.; Kita, K.; Takahashi, Y.; Sakaguchi, A.; Tanaka, K.; Yamashiki, Y.; Yoshida, N.

2012-12-01

After the Fukushima Daiichi Nuclear Power Plant acciden, fallout radionuclides on the ground surface will transfer through geomorphic processes. Therefore, in order to estimate future changes in radionuclide deposition, migration process of radionuclides in forests, soils, ground water, rivers, and entrainment from trees and soils should be confirmed. We (FMWSE group) was funded by MEXT, Japanese government, and 1 year following monitoring has been conducted about 1 year. 1 Migration study of radionuclides in natural environment including forests and rivers 1) Study on depth distribution of radiocaesium in soils within forests, fields, and grassland. 2) Confirmation of radionuclide distribution and investigation on migration in forests. 3) Study on radionuclide migration due to soil erosion under different land use. 4) Measurement of radionuclides entrained from natural environment including forests and soils. 2 Migration study of radionuclides through hydrological cycle such as soil water, rivers, lakes and ponds, ground water. 1) Investigation on radionuclide migration through soil water, ground water, stream water, spring water under different land use. 2) Study on paddy-to-river transfer of radionuclides through suspended sediment. 3) Study on river-to-ocean transfer of radionuclides via suspended sediment. 4) Confirmation of radionuclide deposition in ponds and reservoirs. We will present how and where the fallout radionulides transfter through geomorphic processes.

DEMONSTRATION BULLETIN: SOIL/SEDIMENT WASHING SYSTEM BERGMANN USA

EPA Science Inventory

The Bergmann USA Soil/Sediment Washing System is a waste minimization technique designed to separate or "partition" soils and sediments by grain size and density. In this water-based volume reduction process, hazardous contaminants are concentrated into a small residual portion...

Source tracing of fluvial suspended sediments by magnetic and geochemical particle characterization: example of the Canche watershed (Nord-Pas-de-Calais, France)

NASA Astrophysics Data System (ADS)

Patault, Edouard; Alary, Claire; Franke, Christine; Gauthier, Arnaud; Abriak, Nor-Edine

2016-04-01

In France, erosion by water run-off is estimated to 1.5 t ha-1yr-1 and can exceed 10 t ha-1yr-1 in large growing areas, such as the North of France (Nord-Pas-de-Calais). In this region, the Canche watershed (1294 km2) sustains heavy loss of fertile soils. The land use is mainly dominated by arable lands (80%) and in 2013, 104 kt of suspended sediment transited to the estuary. As demonstrated in literature, agricultural soil erosion leads to the gradual disappearance and depletion of fertile soil, which constitute a non-renewable resource at human time scale. Additionally, water erosion can significantly damage the aquatic habitat and can be responsible for the input of nutrients, bacteria, pesticides, heavy metals and radionuclides into surface waters. Conscious of these effects, many programs have emerged in the Nord-Pas-de-Calais to reduce erosion. This study presents a combination of environmental magnetic proxy parameters and geochemical analyses on sediments and suspended particulate matter. The aim is to develop effective tools to trace erosion by water run-off and quantify this process. In order to identify the respective sediment sources in the Canche watershed, sediment trap samples of suspended particulate matter were recovered at key positions along the Canche watershed. The preliminary results show that magnetic concentration (Mrs) shows typical values for the agricultural soils in the region, but these variations in magnetic concentrations and total irons concentrations are not always correlated, which may be explained by the iron speciation. In calculating the so-called S-ratio for each sample we can distinguish changes in magneto-mineralogy (and thus iron speciation) from magnetite-dominated assemblages in the mainstream Canche (naturel background signal) to high-coercivity-dominated assemblages in the tributaries, typical for soil erosion material rich in hematite/goethite. In combination with the element concentrations from ICP analyses, this proxy parameter may give valuable insight into the tracing of the suspended sediment sources. In perspective, the seasonal variability and the discharge in the Canche watershed have to be taken into account.

Sediment and Phosphorus losses by Surface Runoff from a Catchment in the Humid Pampa Landscape, Argentina Republic

NASA Astrophysics Data System (ADS)

Méndez M., A.; Díaz E., L.; Lenzi M., L.; Lado, M.; Vidal-Vázquez, E.

2015-04-01

The estimation of sediment and phosphorus transfers from soil into watersheds as a result of agricultural activity is a key aspect for characterizing the sustainability of current land use systems. The objective of the present study was to quantify the temporal evolution of suspended sediment and dissolved phosphorus losses from the upper basin of the Gualeguaychú River. The studied catchment has an area of 483 Km2 and is located in the Entre Ríos province, Argentina Republic. The climate is subtropical humid with average annual rainfall of 1200 mm. Soils are characterized by very low infiltration rates. Land use was assessed by remote sensing and GIS tools, and consists of: 31% abandoned rice fields, 20% naturalized fields, 20% soybean (second cycle), 10% soybean (first cycle), 7% rice, 4% Pasture, and the remaining 7% is devoted to civil and road works, native forests and other crops. Low soil infiltration capacity, together with landscape geomorphological traits of the studied landscape and zonal rainfall regime, typically originates periods with high surface runoff volumes, mainly in autumn, spring and summer months. The study was conducted during a period of eight years. Instantaneous water flow measurements (discharge) were estimated in a control section of Gualeguaychú River from hydrometer reading and the rating curve of height-flow. In addition, 134 water samples of 2000 cm3 were collected during the study period to analyze the concentration of suspended sediments and dissolved phosphorus. The instantaneous flow was estimated with the hydrometer reading and the application of curve of height - flow. The discharge range was from 0.14 to 128 m3/sec, indicating a high variability in the response of the catchment to seasonal rainfall. On average suspended sediment and dissolved phosphorus losses of the experimental catchment were 1.42 Mg and 0.335 Kg per hectare/year, respectively. It was also shown that few events of high rainfall that generate excess runoff were responsible for the most of recorded losses of sediment and phosphorus. Moreover, the highest exportation of sediments and phosphorus from soil to streamflow occurred in the spring and summer period. The daily losses of phosphorus or sediments were mainly explained by the amount of precipitation accumulated during the five days prior to sampling, as shown by regression analysis, and a higher coefficient of determination was obtained for samples extracted during the summer season. This response mainly has been demonstrated to be produced in periods with higher amounts of precipitation equal or greater than 35 mm arising in this season, which are characteristic for summer storms with high rain intensities, and therefore greater erosive power.

The distribution of mercury around the small-scale gold mining area along the Cikaniki river, Bogor, Indonesia.

PubMed

Tomiyasu, Takashi; Kono, Yuriko; Kodamatani, Hitoshi; Hidayati, Nuril; Rahajoe, Joeni Setijo

2013-08-01

The distribution of mercury in the soil, sediment and river water around the artisanal small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia, was investigated. The total mercury concentration (T-Hg) in the forest soil ranged from 0.11 to 7.0mgkg(-1), and the highest value was observed at the ASGM village. In the vertical T-Hg profile around the villages, the highest value was observed at the soil surface, and the concentration decreased with depth. This result suggested that the mercury released by mining activity was dispersed through the atmosphere and deposited on the surface. The total organic carbon content (TOC) showed a similar vertical profile as the T-Hg, and a linear relationship was found between T-Hg and TOC. Mercury deposited on the surface can be absorbed by organic matter. The slope of the line was larger near the ASGM village, implying a higher rate of deposition of mercury. The T-Hg in the sediment ranged from 10 to 70mgkg(-1), decreasing gradually toward the lower reaches of the river. Mining waste can be transported with the river flow and deposited along the river. The distribution of the mining waste can be determined using the mineralogical composition measured by X-ray fluorescence spectrometry. Copyright © 2013 Elsevier Inc. All rights reserved.

Assessment of contemporary erosion/sedimentation rates trend within a small well-cultivated catchments using caesium-137 as a chronomarker (on the example of the Republic of Tatarstan, Russia)

NASA Astrophysics Data System (ADS)

Sharifullin, Aidar; Gusarov, Artem; Gafurov, Artur; Golosov, Valentin

2017-04-01

An analysis of sedimentation at a first order valley bottoms allows us to receive a sufficiently reliable quantitative evaluation of soil losses from the catchment area for two time intervals: 1963-1986 and 1987-2015 and its temporal variability. The studied catchment "Temeva River" with total area 1.13 km2 is located in the northwestern part of the Republic of Tatarstan (the Myósha river basin). Combination methods and approaches were used for evaluation of sediment redistribution for the both time intervals, including detail geodetic survey of the main morphological units of the valley, large scale geomorphological mapping, cesium-137 technique for the sediment dating in the typical locations of the valley bottom, calculation of soil losses using modified version of USLE and State Hydrological Institute models. In addition available information was collected from the local meteorological stations about some climate characteristics dynamics for the period 1950-2015. Landsat images were applied for evaluation of possible changes of land use. Crop management coefficients were calculated separately for the rainfall season and snow-melt using available data about crop-rotation dynamics for the last 55 years. In the results it was found the significant decrease of average annual soil losses from the cultivated part of the "Temeva River" catchment for the period 1987-2015 if it is compare with period 1963-1986. Such conclusion is mainly based on the different sedimentation rates in the valley bottom: for the period of 1963-1986 the average sedimentation rates were 0.92-1.81 cm per year, while the period of 1987-2015 the rates were 0.17-0.50 cm per year. The main reason for this significant decrease sediment redistribution within the catchment is the reduction of surface runoff caused by climate warming in the region. It is led to the reduction of soils freezing depth and water reserves in a snow cover before the snow-melt, and to the sharp decline in the frequency of extreme (storm) precipitation (>50 mm per a day). The influence of agricultural activity on the erosion and sedimentation changeability was insignificant, although some regional variation of crop rotation including an increase in the proportion of perennial grasses obviously caused the decline in soil losses during warm period of year. The similar trend of erosion/sedimentation rates due to mostly climate changes was identified for south-western sector of the East European Plain, but the more serious reduction of erosion rates is established for the Middle Volga region. Keywords: erosion, sedimentation, sediment, caesium-137, dry valley, small catchment, cultivated lands, Republic of Tatarstan, East European Plain.

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.

Scale, thresholds and connectivity: sediment pathways and delivery from the patch to the catchment scale

NASA Astrophysics Data System (ADS)

Cammeraat, L. H.

2009-04-01

Geomorphological processes including soil erosion are active in specific spatio-temporal domains and lead eventually to various emerging soil properties and landscape structures which are evidently also scale dependent. In this study the scale and threshold dependency of landscapes will be compared involving three different landscapes from the temperate, Mediterranean and semi-arid Sahelian geo-ecosystems, especially with regard to the connectivity of water and sediment redistribution. The dominant processes and feed-backs interwoven with soil erosion processes will be discussed from a hierarchical theory type of approach. However, current processes are almost always affected by the presence of inherited soil and landscape properties that might be formed under very different climatological conditions than those that are dominant today. Another important factor in these processes is the role of animals and plants. It will be shown that in all discussed geo-ecosystems plants and animals can be seen as geo-ecosystem engineers and are also important at broader scales with respect to runoff generation and sediment transport. For the temperate zone a case study from the cuesta landscape of the Paris Basin will be discussed, showing that fine scale, soil physico-chemical processes, soil animal and vegetation related processes lead to the emergence of partial areas and also play an important role in the formation of the cuestas itself. For the Mediterranean a case study is discussed where vegetation pattern heterogeneity determines water and sediment distribution from the patch to the sub-catchment scale leading to the emergence of either sheetwash generated slopes (pediments) or concentrated flow generated slopes (gullies), but where inherited landscape elements such as pediments with calcretes strongly affect runoff generation and the availability of sediments and hence have a strong impact on the sediment redistribution and measured erosion rates that strongly vary with the scale at which they are measured. Finally a case study from a semi-arid Sahelian ecosystem is discussed where runoff generation and sediment sources are strongly related to the semi-natural upper landscape zones with a strong interplay between vegetation and surface conditions, and where land use in the lower landscape units is an important sink area for both sediment and water. Landscape heterogeneity and the distribution of source and sinks of water and sediment is often strongly disconnected and shows clear physical thresholds that can be either of natural origin (e.g. vegetation clumps and patterns) or man-made (e.g. terraces). These physical thresholds are also important as temporary sediment sinks, that may convert to sediment sources during high magnitude events. The connectivity of sediment flow and hence sediment delivery to lower landscape units or larger channels is therefore highly variable and strongly dependent on both finer scale landscape elements and their specific position in the landscape, and the frequency-magnitude relationships of rainfall. It can be concluded that aspects of hydrological connectivity, temporary sinks of water and sediment in combination with biophysical and anthropogenic thresholds as well as storm characteristics should be included when scaling landscape processes to understand erosion and sediment yields. Furthermore the role and importance of biotic components in erosion studies is still underrated, despite the fact that vegetation is more and more applied to reduce erosion.

Identifying drought response of semi-arid aeolian systems using near-surface luminescence profiles and changepoint analysis, Nebraska Sandhills.

NASA Astrophysics Data System (ADS)

Buckland, Catherine; Bailey, Richard; Thomas, David

2017-04-01

Two billion people living in drylands are affected by land degradation. Sediment erosion by wind and water removes fertile soil and destabilises landscapes. Vegetation disturbance is a key driver of dryland erosion caused by both natural and human forcings: drought, fire, land use, grazing pressure. A quantified understanding of vegetation cover sensitivities and resultant surface change to forcing factors is needed if the vegetation and landscape response to future climate change and human pressure are to be better predicted. Using quartz luminescence dating and statistical changepoint analysis (Killick & Eckley, 2014) this study demonstrates the ability to identify step-changes in depositional age of near-surface sediments. Lx/Tx luminescence profiles coupled with statistical analysis show the use of near-surface sediments in providing a high-resolution record of recent system response and aeolian system thresholds. This research determines how the environment has recorded and retained sedimentary evidence of drought response and land use disturbances over the last two hundred years across both individual landforms and the wider Nebraska Sandhills. Identifying surface deposition and comparing with records of climate, fire and land use changes allows us to assess the sensitivity and stability of the surface sediment to a range of forcing factors. Killick, R and Eckley, IA. (2014) "changepoint: An R Package for Changepoint Analysis." Journal of Statistical Software, (58) 1-19.

Legacy Compliance Final Report: Results of the Navy/Encapo Soil Stabilization Study at the Nevada Test Site, Nye County, Nevada

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

Desotell, Lloyd; Anderson, David; Rawlinson, Stuart

Historic atmospheric testing of nuclear devices at the Nevada Test Site (NTS) has resulted in large areas of plutonium-contaminated surface soils. The potential transport of these contaminated soils to onsite and offsite receptors is a concern to the land steward and local stakeholders. The primary transport pathways of interest at the NTS are sediment entrained in surface water runoff and windblown dust. This project was initially funded by the U.S. Navy and subsequently funded by the USDOE Stockpile Stewardship Program. Field tests were conducted over a 20.5 month period to evaluate the efficacy of an organic-based, surface applied emulsion tomore » reduce sediment transport from plutonium-contaminated soils. The patented emulsion was provided by Encapco Technologies LLC. Field tests were conducted within the SMOKY radioactive contamination area (CA). The SMOKY above ground nuclear test was conducted on 08/31/1957, with a reported yield of 44 kilotons and was located at N 37 degrees 10.5 minutes latitude and W 116 degrees 04.5 minutes longitude. Three 'safety tests' were also conducted within approximately 1,500 meters (5,000 feet) of the SMOKY ground zero in 1958. Safety tests are designed to test the response of a nuclear device to an unplanned external force (e.g., nearby detonation of conventional explosives). These three safety tests (CERES, OBERON, and TITANIA) resulted in dispersal of plutonium over a wide area (Bechtel Nevada, 2002). Ten 3 x 4.6 meter test plots were constructed within the SMOKY CA to conduct rainfall-runoff simulations. Six of the ten test plots were treated with the emulsion at the manufacturer recommended loading of 1.08 gallons per square meter, and four plots were held untreated as experimental controls. Separate areas were also treated to assess impacts to native vegetation and surface infiltration rate. Field tests were conducted at approximately 6, 13, and 20.5 months post emulsion treatment. Field tests consisted of rainfall-runoff simulations and double ring infiltrometer measurements. Plant vigor assessments were conducted during peak production time, approximately seven months post treatment. Rainfall was simulated at the approximate 5 minute intensity of a 50-year storm (5.1 inches per hour) for durations of four to five minutes. All runoff generated from each test plot was collected noting the time for each liter of volume. Five gallon carboys containing the runoff water and sediment were shipped to Clemson Environmental Technologies Laboratory for analysis. The samples were separated into liquid and solid fractions. Liquid and solid fractions were weighed and analyzed for Americium-241 (Am-241) by gamma spectrometry. Quality control measures used at the laboratory indicate the analytical data are accurate and reproducible. A weather station was deployed to the field site to take basic meteorological measurements including air temperature, incoming solar radiation, wind speed, wind direction, barometric pressure, relative humidity, precipitation, and volumetric soil moisture content. Meteorological monitoring data indicate the climate over the test period was hot and dry with 41 days having measurable precipitation. The total precipitation for the study period was 12.5 centimeters, 37% of the long-term average. For the 20.5 month test period, 64 freeze-thaw cycles occurred. Vegetation assessments indicate the emulsion treatment did not negatively impact existing vegetation. The three rounds of double ring infiltration tests on treated surfaces indicate the infiltration rate was relatively constant over time and not significantly different from measurements taken on untreated surfaces. Significant differences were observed in the amount of runoff and sediment collected from treated and untreated plots for the first two but not the third round of rainfall-runoff simulations, indicating significant emulsion degradation after 20.5 months of exposure. Treated plots had higher total runoff volumes and sediment loads as compared to untreated plots for the first two rounds of simulations. These data indicate the treatment caused the treated surfaces to repel more of the simulated rainfall than the untreated plots but did not increase the cohesion between soil particles to resist soil particle detachment and transport with the runoff water. Am-241 concentration in collected sediments varied as a function of proximity to the safety test locations, not as a function of surface treatment. The results from field testing the Encapco emulsion indicate it is not a viable long-term option for the stabilization of radionuclide impacted surface soils at the Nevada Test Site in its current formulation. Dust suppression studies conducted by Etyemezian et al. (2006) at an uncontaminated location near the SMOKY site indicate the emulsion significantly reduced dust emissions for at least four months post application, indicating the emulsion may be useful for short-term applications.« less

The influence of badland surfaces and erosion processes on vegetation cover

NASA Astrophysics Data System (ADS)

Hardenbicker, Ulrike; Matheis, Sarah

2014-05-01

To assess the links between badland geomorphology and vegetation cover, we used detailed mapping in the Avonlea badlands, 60 km southwest of Regina, Saskatchewan Canada. Three badlands surfaces are typical in the study area: a basal pediment surface, a mid-slope of bentonitic mudstone with typical popcorn surface, and an upper slope with mud-cemented sandstone. Badland development was triggered by rapid post Pleistocene incision of a meltwater channel in Upper Cretaceous marine and lagoonal sediments. After surveying and mapping of a test area, sediment samples were taken to analyze geophysical parameters. A detailed geomorphic map and vegetation map (1:1000) were compared and analyzed in order to determine the geomorphic environment for plant colonization. The shrink-swell capacity of the bentonitic bedrock, slaking potential and dispersivity are controlled by soil texture, clay mineralogy and chemistry, strongly influencing the timing and location of runoff and the relative significance of surface and subsurface erosional processes. The absence of shrink-swell cracking of the alluvial surfaces of the pediments indicates a low infiltration capacity and sheetflow. The compact lithology of the sandstone is responsible for its low permeability and high runoff coefficient. Slope drainage of steep sandstone slopes is routed through a deep corrasional pipe network. Silver sagebrush (Artemisia cana) is the only species growing on the popcorn surface of the mudrock, which is in large parts vegetation free. The basal pediment shows a distinct 2 m band surrounding the mudrock outcrop without vegetation as a result of high sedimentation rate due to slope wash. Otherwise the typical pioneer vegetation of this basal pediment are grasses. In the transition zone below the steep sandstone cliffs and above the gentle bentonitic mudrock surfaces patches of short-grass vegetation are found, marking slumped blocks with intact vegetation and soil cover. These patches are surrounded by less dense pioneer vegetation consisting of grasses and sage bushes indicating minimal surface erosion or sedimentation. Geomorphic mapping documented a high density of active pipes in this area, transporting silt and fine sand from the sandstone cliffs to lower and basal pediments. Vegetation cover alone is a poor indicator of badland surfaces and erosion processes because of the three-dimensional nature of badland erosion processes, and the shrink-swell capacity of the bentonitic bedrock. A combination of geomorphic and vegetation mapping is needed to identify badland surfaces and processes in the study area.

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.

The aqueous geochemistry of uranium in a drainage containing uraniferous organic-rich sediments, Lake Tahoe area, Nevada, USA

USGS Publications Warehouse

Zielinski, R.A.; Otton, J.K.; Wanty, R.B.; Pierson, C.T.

1988-01-01

Anomalously uraniferous waters occur in a small (4.2 km2) drainage in the west-central Carson Range, Nevada, on the eastern side of Lake Tahoe. The waters transport uranium from local U-rich soils and bedrock to organic-rich valley-fill sediments where it is concentrated, but weakly bound. The dissolved U and the U that is potentially available from coexisting sediments pose a threat to the quality of drinking water that is taken from the drainage. The U concentration in samples of 6 stream, 11 spring and 7 near-surface waters ranged from 0.1 V). Possible precipitation of U(IV) minerals is predicted under the more reducing conditions that are particularly likely in near-surface waters, but the inhibitory effects of sluggish kinetics or organic complexing are not considered. These combined results suggest that a process such as adsorption or ion exchange, rather than mineral saturation, is the most probable mechanism for uranium fixation in the sediments. -Authors

Near Surface Geophysical Methods Applied to the Rising Star Cave System

NASA Astrophysics Data System (ADS)

Webb, S. J.; Naidoo, M.; Elliott, M. C.; Kruger, A.; Roberts, E.; Dirks, P.

2017-12-01

The Rising Star Cave system is located approximately 40 km northwest of Johannesburg in the Malmani dolomites (Chuniespoort group,Transvaal Supergroup). The cave system is extensive with 4 km of mapped passages and chambers. The Dinaledi chamber, host to the Homo Naledi fossils, is reached by following a tortuous route with squeezes as small as 20 cm. The chamber is located 30 m below surface and 80 m from the entrance. The enigmatic find of fossils from at least 15 individual hominins, without the presence of other species, led to the idea of deliberate burial. The present access route is difficult and it is unclear how early hominins were able to navigate it, prompting the suggestion of an undiscovered entrance. We are using near surface geophysical methods to investigate possible connections between the surface and the caves. Using a Geometrics Cs-vapor Walkmag, we collected preliminary ground magnetic intensity measurements over a region 300 m x 200 m, using 1 m station spacing and 10 m line spacing. The average magnetic variation along line is 200 nT. We also collected over 100 susceptibility measurements on outcropping lithologies, surface soil and cave sediments using a SM-30 susceptibility meter. The surface soil was one to two orders of magnitude higher than surrounding lithologies (average = 1.5 x 10-3 SI) and the cave sediment samples were slightly higher (average = 3.07 x 10-3 SI). We were able to collect GPR data (GSSI SIR-3000, 400 MHz) in selected spots on the cave floor with the goal of locating the cave floor beneath the sediments. Dolomites usually have low magnetic susceptibilities, but erosion products of the nearby magnetic Hospital Hill or Rooihoogte shales may have been transported into or onto the cave system. This is a likely cause of the magnetic anomalies and larger amplitude anomalies may indicate an accumulation of sediments, extending to depth. These anomalies will be further investigated using gravity to determine if there are previously unknown connections between the surface and the cave system.

A Methodology for Soil Moisture Retrieval from Land Surface Temperature, Vegetation Index, Topography and Soil Type

NASA Astrophysics Data System (ADS)

Pradhan, N. R.

2015-12-01

Soil moisture conditions have an impact upon hydrological processes, biological and biogeochemical processes, eco-hydrology, floods and droughts due to changing climate, near-surface atmospheric conditions and the partition of incoming solar and long-wave radiation between sensible and latent heat fluxes. Hence, soil moisture conditions virtually effect on all aspects of engineering / military engineering activities such as operational mobility, detection of landmines and unexploded ordinance, natural material penetration/excavation, peaking factor analysis in dam design etc. Like other natural systems, soil moisture pattern can vary from completely disorganized (disordered, random) to highly organized. To understand this varying soil moisture pattern, this research utilized topographic wetness index from digital elevation models (DEM) along with vegetation index from remotely sensed measurements in red and near-infrared bands, as well as land surface temperature (LST) in the thermal infrared bands. This research developed a methodology to relate a combined index from DEM, LST and vegetation index with the physical soil moisture properties of soil types and the degree of saturation. The advantage in using this relationship is twofold: first it retrieves soil moisture content at the scale of soil data resolution even though the derived indexes are in a coarse resolution, and secondly the derived soil moisture distribution represents both organized and disorganized patterns of actual soil moisture. The derived soil moisture is used in driving the hydrological model simulations of runoff, sediment and nutrients.

Mechanisms for surface contamination of soils and bottom sediments in the Shagan River zone within former Semipalatinsk Nuclear Test Site.

PubMed

Aidarkhanov, A O; Lukashenko, S N; Lyakhova, O N; Subbotin, S B; Yakovenko, Yu Yu; Genova, S V; Aidarkhanova, A K

2013-10-01

The Shagan River is the only surface watercourse within the former Semipalatinsk Test Site (STS). Research in the valley of the Shagan River was carried out to study the possible migration of artificial radionuclides with surface waters over considerable distances, with the possibility these radionuclides may have entered the Irtysh River. The investigations revealed that radioactive contamination of soil was primarily caused by the first underground nuclear test with soil outburst conducted at the "Balapan" site in Borehole 1004. The surface nuclear tests carried out at the "Experimental Field" site and global fallout made insignificant contributions to contamination. The most polluted is the area in the immediate vicinity of the "Atomic" Lake crater. Contamination at the site is spatial. The total area of contamination is limited to 10-12 km from the crater piles. The ratio of plutonium isotopes was useful to determine the source of soil contamination. There was virtual absence of artificial radionuclide migration with surface waters, and possible cross-border transfer of radionuclides with the waters of Shagan and Irtysh rivers was not confirmed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Soil archives of mardel deposits: the impact of Late Holocene vegetation development, climatic oscillations and historical land use on soil erosion in Luxembourg

NASA Astrophysics Data System (ADS)

van Mourik, Jan; Slotboom, Ruud

2014-05-01

Mardel genesis. Mardels are small scale circular to elongated closed depressions (Ø > 50 m). They occur in Luxembourg on the Lias plateau in the Gutland, but also in other regions with landscapes, developed on Keuper and Lias deposits (as Lorraine). We can distinguish geogenetic and anthropogenic mardels. There are two types of genetic mardels, sink holes (controlled by diaclases in the Luxembourger sandstone and 'true mardels' or subsidence basins (controlled by dissolved gypsic lenses in marls of the Keuper deposits). These mardels developed during the Holocene. The age of the mardel sediments is Subatlantic; the sediments have been deposited on a palaeosol. Anthropogenic mardels are the result of historic clay excavation (Roman Time or younger). The age of these mardels is Subatlantic. The age of the sediments is also Subatlantic; the sediments have been deposited on a truncated soil in excavations. In all the genetic types of mardels, the sediments can consist of peat, peaty loam, or colluvic clayloam and the mardel sediments contain always valuable soil archives for the reconstruction of the impact of vegetation development, climatic oscillations and land use on soil erosion and deposition. Comparison of mardel deposits and valley deposits. - Pre-Holocene mardels have been eroded during the Weichselian. Geogenic mardels have been developed during the Holocene, anthropogenic mardels have been excavated since Roman Time. The age of the clastic (colluvic) deposits in mardels is Subatlantic - In the Late Glacial, valley bottoms were rather broad and covered with a gravelly bed load. Till the Subboreal river incision was active in primary valleys and peat accumulation took place on broad valley bottoms of secondary valleys. Since Celtic/Roman Time deforestation and extension of agriculture. During the Subatlantic colluvic/alluvic sedimentation took place on all the valley bottoms. The Subatlantic is a period of accelerated sedimentation of clastic sediments in closed depressions and (open) valleys This was the impact of two factors. 1. Impact of natural forest evolution on soil erosivity. Fagus arrived in the area, jostled Tilia in the Subboreal and extended in the Subatlantic. The understory and humus forms changed, the erosivity of the surface increased and the consequence was accelerating soil erosion. Stable mardels changed in sediment traps, river valleys got constipated with colluvic/alluvic sediments. 2. Anthropogenic deforestation and extension of agriculture since Roman Time. Conclusions. 1. In a lot of studies, deforestation was considered as the responsible factor for soil erosion. 2. Impact of natural forest evolution (the appearance of Fagus) was not recognized 3. The impact of the Little Ice Age on Subatlantic soil erosion was not recognized 4. Three factors controlled Subatlantic soil erosion and mardel and valley deposition - The (natural) jostle of mixed oak forest by beach forest promoted soil erosivity and erosion - The (anthropogenic) deforestation and expansion of agriculture promoted soil erosion - The temporally move from pasture to arable land during the Little Ice Age promoted soil erosivity References. - Barth B (1996) Mardellen im Lotharingischen Gipskeuper. Delattinia 22: 7-60. - Buisman J (1995-2006) Duizend jaar weer, wind en water in de lage landen, Vols. 1-5. KNMI, Netherlands. - Etienne D, Ruffaldi P, Goepp S, Ritz F, Georges-Leroy M, Pollier B and Dambrine E (2011) The origin of closed depressions in Northeastern France: A new assessment. Geomorphology 126: 121-131. - Loehle C (2007) A 2000-year global temperature reconstruction based on non-treeing proxies. Energy and Environment, 18 No. 7+8 - Poeteray FA, Riezebos PA, Slotboom RT (1984) Rates of Subatlantic lowering calculated from mardel-trapped material (Gutland, Luxembourg). Zeitschrift für Geomorphologie 1984: 467-4821. - Schönwiese C (1995) Klimaänderungen: Daten, Analysen, Prognosen. Springer, Heidelberg - Slotboom RT (1963) Comparative geomorphological and palynological investigation of the pingos (Viviers) in the Haute Fagnes (Belgium) and the Mardellen in the Gutland (Luxembourg). Zeitschift für Geomorphologie 7: 193-231. - Riezebos PA and Slotboom RT (1978) Pollen analysis of the Husterbaach peat (Luxembourg). Boreas 7: 75-82 - Thoen, D. and Hérault, B., 2006. Flore, groups socio-écologique et typologie de mardelles forestières de Lorrainne belge et luxembourgeoise. Bull.Soc. luxemb. 107 (2006), 3-25.

Partition characteristics of polycyclic aromatic hydrocarbons on soils and sediments

USGS Publications Warehouse

Chiou, C.T.; Mcgroddy, S.E.; Kile, D.E.

1998-01-01

The partition behavior was determined for three polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, and pyrene, from water to a range of soil and sediment samples. The measured partition coefficients of the individual PAHs between soil/sediment organic matter (SOM) and water (i.e., K(oc) values) are relatively invariant either for the 'clean' (uncontaminated) soils or for the clean sediments; however, the mean K(oc) values on the sediments are about twice the values on the soils. This disparity is similar to the earlier observation for other nonpolar solutes and reflects the compositional differences between soil and sediment organic matters. No significant differences in K(oc) are observed between a clean coastal marine sediment and freshwater sediments. The coastal sediments that are significantly impacted by organic contaminants exhibit higher K(oc) values. At given K(ow) values (octanol-water), the PAHs exhibit much higher K(oc) values than other relatively nonpolar solutes (e.g., chlorinated hydrocarbons). This effect is shown to result from the enhanced partition of PAHs to SOM rather than from lower K(ow) values of PAHs at given supercooled liquid solute solubilities in water. The enhanced partition of PAHs over other nonpolar solutes in SOM provides an account of the markedly different correlations between log K(oc) and log K(ow) for PAHs and for other nonpolar solutes. The improved partition of PAHs in SOM stems apparently from the enhanced compatibility of their cohesive energy densities with those of the aromatic components in SOM. The approximate aromatic fraction in soil/sediment organic matter has been assessed by solid-state 13C-NMR spectroscopy.The partition behavior was determined for three polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, and pyrene, from water to a range of soil and sediment samples. The measured partition coefficients of the individual PAHs between soil/sediment organic matter (SOM) and water (i.e., Koc values) are relatively invariant either for the `clean' (uncontaminated) soils or for the clean sediments; however, the mean Koc values on the sediments are about twice the values on the soils. This disparity is similar to the earlier observation for other nonpolar solutes and reflects the compositional differences between soil and sediment organic matters. No significant differences in Koc are observed between a clean coastal marine sediment and freshwater sediments. The coastal sediments that are significantly impacted by organic contaminants exhibit higher Koc values. At given Kow values (octanol-water), the PAHs exhibit much higher Koc values than other relatively nonpolar solutes (e.g., chlorinated hydrocarbons). This effect is shown to result from the enhanced partition of PAHs to SOM rather than from lower Kow values of PAHs at given supercooled liquid solute solubilities in water. The enhanced partition of PAHs over other nonpolar solutes in SOM provides an account of the markedly different correlations between log Koc and log Kow for PAHs and for other nonpolar solutes. The improved partition of PAHs in SOM stems apparently from the enhanced compatibility of their cohesive energy densities with those of the aromatic components in SOM. The approximate aromatic fraction in soil/sediment organic matter has been assessed by solid-state 13C-NMR spectroscopy.

The potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from Utah and Colorado, U.S.A.: Preliminary results

NASA Astrophysics Data System (ADS)

Forman, S. L.; Jackson, M. E.; McCalpin, J.; Maat, P.

The natural TL intensity for surface and buried Holocene and Pleistocene A horizons developed on flood-plain silts, near Denver, Colorado exponentially decreases with time. This signal is approaching saturation by ca. 130 ka. The A horizon of the modern flood-plain soil is not fully light bleached. The TL properties and age estimates are presented for radiocarbon dated, eolian-enriched buried-A horizons developed on fault-derived colluvium from the American Fork segment of the Wasatch fault zone, Utah. Dating of these buried soils provide a close age estimate on paleoearthquake events. Mean TL age estimates by regeneration and total bleach techniques for buried A horizons are 0.5 ± 0.1 ka and 2.7 ± 0.4 ka which are in agreement with corresponding radiocarbon dates of 980 ± 70 years BP and 2620 ± 70 years BP. A surface sag pond mud formed within an antithetic grabben is well light bleached and yielded a TL age estimate by the total bleach method of 240 ± 60 years BP, in agreement with its known age of <300 years BP. This study indicates that relatively brief periods of pedogenesis are not sufficient to light-bleach sediment and that eolian additions enhance the reduction of TL in soils.

Soil erosion and sediment yield and their relationships with vegetation cover in upper stream of the Yellow River.

PubMed

Ouyang, Wei; Hao, Fanghua; Skidmore, Andrew K; Toxopeus, A G

2010-12-15

Soil erosion is a significant concern when considering regional environmental protection, especially in the Yellow River Basin in China. This study evaluated the temporal-spatial interaction of land cover status with soil erosion characteristics in the Longliu Catchment of China, using the Soil and Water Assessment Tool (SWAT) model. SWAT is a physical hydrological model which uses the RUSLE equation as a sediment algorithm. Considering the spatial and temporal scale of the relationship between soil erosion and sediment yield, simulations were undertaken at monthly and annual temporal scales and basin and sub-basin spatial scales. The corresponding temporal and spatial Normalized Difference Vegetation Index (NDVI) information was summarized from MODIS data, which can integrate regional land cover and climatic features. The SWAT simulation revealed that the annual soil erosion and sediment yield showed similar spatial distribution patterns, but the monthly variation fluctuated significantly. The monthly basin soil erosion varied from almost no erosion load to 3.92 t/ha and the maximum monthly sediment yield was 47,540 tones. The inter-annual simulation focused on the spatial difference and relationship with the corresponding vegetation NDVI value for every sub-basin. It is concluded that, for this continental monsoon climate basin, the higher NDVI vegetation zones prevented sediment transport, but at the same time they also contributed considerable soil erosion. The monthly basin soil erosion and sediment yield both correlated with NDVI, and the determination coefficients of their exponential correlation model were 0.446 and 0.426, respectively. The relationships between soil erosion and sediment yield with vegetation NDVI indicated that the vegetation status has a significant impact on sediment formation and transport. The findings can be used to develop soil erosion conservation programs for the study area. Copyright © 2010 Elsevier B.V. All rights reserved.

Determination of erosion thresholds and aeolian dune stabilization mechanisms via robotic shear strength measurements

NASA Astrophysics Data System (ADS)

Qian, F.; Lee, D. B.; Bodek, S.; Roberts, S.; Topping, T. T.; Robele, Y.; Koditschek, D. E.; Jerolmack, D. J.

2017-12-01

Understanding the parameters that control the spatial variation in aeolian soil erodibility is crucial to the development of sediment transport models. Currently, in-situ measurements of erodibility are time consuming and lack robustness. In an attempt to remedy this issue, we perform field and laboratory tests to determine the suitability of a novel mechanical shear strength method to assess soil erodibility. These tests can be performed quickly ( 1 minute) by a semi-autonomous robot using its direct-drive leg, while environmental controls such as soil moisture and grain size are simultaneously characterized. The robot was deployed at White Sands National Monument to delineate and understand erodibility gradients at two different scales: (1) from dry dune crest to moist interdune (distance 10s m), where we determined that shear strength increases by a factor of three with increasing soil moisture; and (2) from barren barchan dunes to vegetated and crusted parabolics downwind (distance 5 km), where we found that shear strength was enhanced by a factor of two relative to loose sand. Interestingly, shear strength varied little from carbonate-crusted dune surfaces to bio-crust covered interdunes in the downwind parabolic region, indicating that varied surface crusts contribute similarly to erosion resistance. To isolate the control of soil moisture on erodibility, we performed laboratory experiments in a sandbox. These results verify that the observed increase in soil erodibility from barchan crest to interdune at White Sands is dominated by soil moisture, and the variation in parabolic dune and barchan interdune areas results from a combination of soil moisture, bio-activity, and crust development. This study highlights that spatial variation of soil erodibility in arid environments is large enough to significantly affect sediment transport, and that probing soil erodibility with a robot has the potential to improve our understanding of this multifaceted problem.

Tracking Soil Organic Carbon Transport to Continental Margin Sediments Using Soil-Specific Hopanoid Biomarkers: a Case Study From the Congo Fan (ODP Site 1075)

NASA Astrophysics Data System (ADS)

Cooke, M. P.; Talbot, H. M.; Eniola, O.; Zabel, M.; Wagner, T.

2007-12-01

The transport and subsequent deposition of terrestrially derived organic matter into the ocean is an important but poorly constrained aspect of the modern global carbon cycle. In regions associated with large river systems it is likely that the terrestrial input of organic carbon is much more complex than commonly considered and very difficult to trace based on established geochemical proxies. It is therefore important to develop proxies that target the movement and fate of this terrestrial organic material. The identification of bacteriohopanepolyol (BHP) biomarkers unique to soil derived organic carbon (SOC) has enabled the transport of SOC into aquatic sediments to be traced. The extreme recalcitrance of BHPs enables these source specific compounds to be used on recent and ancient sediments to identify periods of high and low SOC input into sediments. BHPs are bacterial membrane compounds with a high degree of structural variability. They are analogous to steroids in eukaryotes and have been identified in over half of all bacteria studied for their presence. BHPs have a wide range of over 40 functional groups on the side chain, with up to 6 functional groups in each structure, and with methylation and unsaturation over 100 total structures have been identified1. During the BHP analysis of a wide range of soils from around the world we consistently measure high levels adenosylhopane, known to originate from purple non-sulphur, nitrogen fixing and ammonia oxidising bacteria and 2-methyl adenosyl hopane (m/z 802)2, from nitrogen fixing bacteria. Only 3 lacustrine sediments with large SOC supply from their catchments areas have been found to contain these markers in a survey of over 40 different non-marine settings. Recent studies on Late Quaternary sediments from the Congo deep sea fan (OPD site 1075, approximately 2 km water depth) provide a strong case to expect markers for SOC3. An initial analysis of the core samples confirms the presence of soil specific BHP markers in each sample analyzed down to 89 m depth in addition to the presence of common sediment associated BHPs. Concentrations of soil markers are high in the upper sediment section down to about 49 m supporting the case for these molecular markers as novel proxies for SOC supply and burial. Distinct peaks of adenosyl and 2 methyl adenosyl hopane at about 200, 300 and 550 kyrs tentatively imply that the rate of terrestrial organic matter discharge from tropical Africa significantly increased at these times, possibly associated with periods of reduced soil stability in the Congo catchment. Analysis of the surface sediments from 4 other cores in close proximity to ODP site 1075 clearly shows that the percentage contribution of soil marker BHPs decreases with increasing distance from the river mouth, indicating that the river is the source of these BHPs. References 1. Rohmer, M. 1993. Pure and Applied Chemistry 65, 1293-1298. 2. Talbot, H.M., Rohmer, M., Farrimond, P., 2007. Rapid Communications in Mass Spectrometry (In press). 3. Holtvoeth, J., Wagner, T., Kolonic, S., 2005. Geochimica et Cosmochimica Acta, 69, 2031-2041.

LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

EPA Science Inventory

Metal oxide phases play an important role in governing the sorption and desorption mechanisms of metals in water, soils, and sediments. Many researchers have examined the efficiency of Pb sorption on Mn, Fe, Al, Ti, and Si oxide surfaces. Most studies concluded that adsorption ...

Optimization Review: French Gulch/Wellington-Oro Mine Site Water Treatment Plant, Breckenridge, Summit County, Colorado

EPA Pesticide Factsheets

The French Gulch/Wellington-Oro Mine Site is located near the town of Breckenridge in Summit County, Colorado. Environmental contamination of surface water, groundwater, soil and sediment at the site resulted from mining activities dating to the 1880s.

Geology, geohydrology, and soils of NASA, Kennedy Space Center: A review

NASA Technical Reports Server (NTRS)

Schmalzer, Paul A.; Hinkle, C. Ross

1990-01-01

Sediments underlying Kennedy Space Center (KSC) have accumulated in alternating periods of deposition and erosion since the Eocene. Surface sediments are of Pleistocene and Recent ages. Fluctuating sea levels with the alternating glacial-interglacial cycles have shaped the formation of the barrier island. Merritt Island is an older landscape whose formation may have begun as much as 240,000 years ago, although most of the surface sediments are not that old. Cape Canaveral probably dates from less than 7,000 years B.P. (before present) as does the barrier strip separating Mosquito Lagoon from the Atlantic Ocean. Merritt Island and Cape Canaveral have been shaped by progradational processes but not continuously so, while the Mosquito Lagoon barrier has been migrating landward. Deep acquifers beneath KSC are recharged inland but are highly mineralized in the coastal region and interact little with surface vegetation. The Surficial acquifer has formed in the Pleistocene and Recent deposits and is recharged by local rainfall. Sand ridges in the center of Merritt Island are important to its recharge.

Occurrence and fractionation of Cr along the Loushan River affected by a chromium slag heap in East China.

PubMed

Chen, Youyuan; Dong, Bingbing; Xin, Jia

2017-06-01

This study investigated the chromium (Cr) occurrence and distribution along the Loushan River adjacent to a chromium slag heap. The speciation and chemical fractionation of Cr in different environmental media were determined. The potential ecological risks for the surrounding environment were assessed on the basis of both potential ecological risk index (RI) and risk assessment code (RAC). The results show that the surface soil experienced severe Cr contamination with Cr(T) and Cr(VI) values of 3220 ± 6266 and 64 ± 94 mg/kg, respectively, even though the chromium slag heap had already been removed. The chromium slag enhanced the Cr concentration level in the surface soil, water, and sediment samples more than the background level to different extents, which indicates that Cr released from the chromium slag actually affects the surrounding environment. The spatial distribution variety of Cr implies that their transport might have been affected by soil leaking, atmospheric transport, and fluvial hydraulics. The chemical fractionation results demonstrate that the residual fraction was the dominant form, accounting for 54.6 and 66.1% Cr(T) in surface soil and sediment samples, respectively. The content of bioavailable exchangeable Cr fraction correlated with the organic matter (OM), cation exchange capacity (CEC), and pH value. The ecological risk assessment suggests no considerable ecological risk toward the biota despite a relatively high Cr(T) level. Nevertheless, attention should be paid to the potential long-term risks owing to the slow release of oxidizable and residual fractions.

Area G Perimeter Surface-Soil Sampling Environmental Surveillance for Fiscal Year 1998 Hazardous and Solid Waste Group (ESH-19)

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

Marquis Childs

1999-09-01

Material Disposal Area G (Area G) is at Technical Area 54 at Los Alamos National Laboratory (LANL). Area G has been the principal facility for the disposal of low-level, solid-mixed, and transuranic waste since 1957. It is currently LANL's primary facility for radioactive solid waste burial and storage. As part of the annual environmental surveillance effort at Area G, surface soil samples are collected around the facility's perimeter to characterize possible radionuclide movement off the site through surface water runoff During 1998, 39 soil samples were collected and analyzed for percent moisture, tritium, plutonium-238 and 239, cesium-137 and americium-241. Tomore » assess radionuclide concentrations, the results from these samples are compared with baseline or background soil samples collected in an undisturbed area west of the active portion Area G. The 1998 results are also compared to the results from analogous samples collected during 1996 and 1997 to assess changes over this time in radionuclide activity concentrations in surface soils around the perimeter of Area G. The results indicate elevated levels of all the radionuclides assessed (except cesium-137) exist in Area G perimeter surface soils vs the baseline soils. The comparison of 1998 soil data to previous years (1996 and 1997) indicates no significant increase or decrease in radionuclide concentrations; an upward or downward trend in concentrations is not detectable at this time. These results are consistent with data comparisons done in previous years. Continued annual soil sampling will be necessary to realize a trend if one exists. The radionuclide levels found in the perimeter surface soils are above background but still considered relatively low. This perimeter surface soil data will be used for planning purposes at Area G, techniques to prevent sediment tm.nsport off-site are implemented in the areas where the highest radionuclide concentrations are indicated.« less

Quantifying Construction Site Sediment Discharge Risk and Treatment Potential

NASA Astrophysics Data System (ADS)

Ferrell, L.; Beighley, R. E.

2006-12-01

Dealing with soil erosion and sediment transport can be a significant challenge during the construction process due to the potentially large spatial and temporal extent and conditions of bare soils. Best Management Practices (BMP) are commonly used to eliminate or reduce offsite discharge of sediment. However, few efforts have investigated the time varying risk of sediment discharge from construction sites, which often have dynamic soil conditions and the potential for less than optimal BMP installations. The goal of this research is to improve the design, implementation and effectiveness of sediment and erosion control at construction sites using site specific, temporal distributions of sediment discharge risk. Sediment risk is determined from individual factors leading to sediment expert, such as rainfall frequency, the adequacy of BMP installations, and the extent and duration of bare soil conditions. This research specifically focuses on quantifying: (a) the effectiveness of temporary sediment and control erosion control BMPs in preventing, containing, and/or treating construction site sediment discharge at varying levels of "proper" installation, and (b) sediment discharge potential from construction sites during different phases of construction, (ex., disturbed earth operations). BMPs are evaluated at selected construction sites in southern California and at the Soil Erosion Research Laboratory (SERL) in the Civil and Environmental Engineering department at San Diego State University. SERL experiments are performed on a 3-m by 10-m tilting soil bed with soil depths up to 1 meter, slopes ranging from 0 to 50 percent, and rainfall rates up to 150 mm/hr (6 in/hr). BMP performance is assessed based on experiments where BMPs are installed per manufacture specifications, potential less than optimal installations, and no treatment conditions. Soil conditions are also varied to represent site conditions during different phases of construction (i.e., loose lifts, stock piles, temporary roads, finished grade, others). Preliminary site monitoring, experimental results, and a conceptual model for estimating the time depend risk of sediment discharge over the duration of a construction project are presented.

Determining the Chemical and Biological Availability of Zinc in Urban Stormwater Retention Ponds

NASA Astrophysics Data System (ADS)

Camponelli, K.; Casey, R.; Lev, S. M.; Landa, E. R.; Snodgrass, J.

2005-12-01

Highway runoff has the potential to negatively impact receiving systems due to transport of contaminants that accumulate on road surfaces. Metals such as copper and zinc are major components of automobile brake pads and tires, respectively. As these automobile parts are degraded, these metal containing particulates are deposited on the roadway and are washed into storm water retention ponds and surface water bodies during precipitation events. It has been estimated that 15 to 60% of the Zn in urban stormwater runoff comes from tire wear and that tire wear is a significant source of Zn to the environment with release inventories comparable to waste incineration sources. In urban and sub-urban systems, this large source of Zn can accumulate in stormwater retention ponds which serve as habitat for a variety of species. Understanding the chemical and biological availability of Zn to biota is integral to assessing the habitat quality of retention ponds. This study is a first effort to relate the amount and speciation of Zn in a retention pond to Zn inputs through highway-derived runoff events. In addition, results suggest that the chemical speciation and availability of particulate Zn can be related to the bioavailability and toxicity of Zn to pond organisms (i.e. larval amphibians). The study site in Owings Mills, MD is located next to a four-lane highway from which it receives runoff through a single culvert. Five species of anurans are known to utilize the pond as a breeding site and Zn in amphibian tissues and retention pond sediments were highly elevated at this site in 2001 and 2002. A recent analysis of pond sediments, soils, roadway dust and storm water collected at this site suggests that roadway particulate matter transported during runoff events is the dominant source of Zn in this system. Overall, Zn and other trace metals were found to be most abundant in the clay sized faction of pond sediments and soils. The pond cores were found to have higher Zn and Cu concentrations at both the surface and a deeper interval possibly related to a change in land use during the pond's history. Pond sediments are above natural soil background for both Zn and Cu and represent mixing between the roadway particulates and local soils. It is therefore likely that these particulates are the primary source of metals to the pond.

Coupling fractionation and batch desorption to understand arsenic and fluoride co-contamination in the aquifer system.

PubMed

Kumar, Manish; Das, Nilotpal; Goswami, Ritusmita; Sarma, Kali Prasad; Bhattacharya, Prosun; Ramanathan, A L

2016-12-01

The present work is an attempt to study As and F+ coevality using laboratory based assays which couples fractionation and batch dissolution experiments. Sequential extraction procedure (SEP) resulting into five "operationally defined phases", was performed on sediment and soil samples collected from the Brahmaputra flood plains, Assam, India. High correlation between the Fe (hydr)oxide fraction and total As content of the soil/sediment sample indicates the involvement of Fe (hydr)oxides as the principal source of As. F - being an anion has high potential to be sorbed onto positively charged surfaces. Findings of the SEP were used to design the batch desorption experiments by controlling the Fe (hydr)oxide content of the soil/sediment. Desorption of As and F - was observed under acidic, neutral and alkaline pH from untreated and Fe (hydr)oxide removed samples. Highest amount of As and F - were found to be released from untreated samples under alkaline pH, while the amount leached from samples with no Fe (hydr)oxide was low. The study showed that the Fe (hydr)oxide fraction commonly found in the soils and sediments, had high affinity for negatively charged species like F - oxyanions of As, AsO 4 3- (arsenate) and AsO 3 3- (arsenite). Fe (hydr)oxide fraction was found to play the major role in co-evolution of As and F - . Two sorption coefficients were proposed based on easily leachable fraction and As present in the groundwater of sampling location for understanding of contamination vulnerability from the leaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mathematical model of sediment and solute transport along slope land in different rainfall pattern conditions

PubMed Central

Tao, Wanghai; Wu, Junhu; Wang, Quanjiu

2017-01-01

Rainfall erosion is a major cause of inducing soil degradation, and rainfall patterns have a significant influence on the process of sediment yield and nutrient loss. The mathematical models developed in this study were used to simulate the sediment and nutrient loss in surface runoff. Four rainfall patterns, each with a different rainfall intensity variation, were applied during the simulated rainfall experiments. These patterns were designated as: uniform-type, increasing-type, increasing- decreasing -type and decreasing-type. The results revealed that changes in the rainfall intensity can have an appreciable impact on the process of runoff generation, but only a slight effect on the total amount of runoff generated. Variations in the rainfall intensity in a rainfall event not only had a significant effect on the process of sediment yield and nutrient loss, but also the total amount of sediment and nutrient produced, and early high rainfall intensity may lead to the most severe erosion and nutrient loss. In this study, the calculated data concur with the measured values. The model can be used to predict the process of surface runoff, sediment transport and nutrient loss associated with different rainfall patterns. PMID:28272431

BERGMANN USA SOIL SEDIMENT WASHING TECHNOLOGY - APPLICATIONS ANALYSIS REPORT

EPA Science Inventory

This document provides an evaluation of the performance of the Bergmann USA Soil/Sediment Washing System and its applicability for the treatment of soils or sediments contaminated with organic and/or inorganic compounds. Both the technical and economic aspects of the technology w...

Using Rare Earth Element (REE) tracers to identify preferential micro-sites of post-fire aeolian erosion

NASA Astrophysics Data System (ADS)

Van Pelt, R.; Zobeck, T. M.; Barnes, M. A.; Baddock, M.; D'Odorico, P.

2011-12-01

Plant communities in desert environments are spatially anisotropic. Nutrient islands develop below shrub canopies and in the bases of bunch grasses that enhance plant growth and reinforce the spatial anisotropy. Catastrophic disturbance that removes the vegetation such as fire or drought can result in the release of the trapped sediment which becomes redistributed over the landscape by wind and water. We applied Rare Earth Element (REE) tracers to different landscape positions of an anisotropic Northern Chihuahua Desert ecosystem at the Sevilleta National Wildlife Refuge in central New Mexico in an effort to study this process. We delineated three 0.5 m by 6 m plots of desert grassland and three plots of desert grassland-shrubland ecotone. Nitric acid was used to dissolve the REE oxides (Eu2O3, Dy2O3, and Pr6O11) which were then diluted in distilled water to a target concentration of 1 g REE l-1 and applied to the surface at a rate of 4 l m-2. From laboratory column studies using soil collected at the site, we estimated that this would penetrate the surface to a depth of 2.5 cm resulting in a sediment REE concentration of approximately 100 mg kg-1. Eu was applied to bare surfaces between vegetation characterized as sand with a surface covering of gravel, Pr was applied under grass clumps, and Dy was applied under Creosote Bush (Larrea tridentata (DC.). Two replicate 0.25 m2 areas of each surface type were also tagged to obtain a sample of tagged surface sediment for analysis. The area containing the plots was burned by U.S. Fish and Wildlife personnel on April 14, 2010. During the next two days, two grassland plots and two grassland-shrubland ecotone plots were tested by placing a portable boundary layer field wind tunnel over the plots and blowing them with 12 m s-1 wind for 10 minutes during which time a paired set of entrained sediment samples were captured at the outlet of the wind tunnel. This period was followed by a 30 minute test in which clean quartz sand abrader was added to the wind tunnel flow and a second test of 10 minutes with abrader added to the flow. At the end of the first four tests, the wind tunnel cooling system broke and due to the extent of necessary repairs, the last two plots were tested two weeks later. Three paired aeolian sediment samples were collected for each plot tested. The results indicated that in desert grassland, a disproportionate amount of the post-fire sediment is entrained from areas under grass clumps and in grassland-shrubland ecotones, the soil under shrubs is the primary source of entrained sediment followed by areas under grass clumps. The bare surfaces between vegetation produced the least sediment. REEs appear to be a powerful tool for investigating spatial patterns of aeolian processes.

Occurrence and source apportionment of polycyclic aromatic hydrocarbons in soils and sediment from Hanfeng Lake, Three Gorges, China.

PubMed

Cai, Jing; Gao, Shutao; Zhu, Like; Jia, Xuwei; Zeng, Xiangying; Yu, Zhiqiang

2017-11-10

This study was conducted to investigate the pollutant status and the retention mechanism of polycyclic aromatic hydrocarbons (PAHs) in soils and sediment from bank-water-level-fluctuating zone (WLFZ)-water systems in Hanfeng Lake, Three Gorges, China. The concentrations of the 16 PAHs ranged from 21.8 to 1324 ng g -1 dry wt for all 20 soil and sediment samples. These concentration levels were remarkably lower than those in soils and sediment collected domestically and worldwide. PAHs with two and three rings were found to be dominant in all the samples, with phenanthrene being most abundant. The spatial distribution of PAHs in bank soil, WLFZ soil, and sediment implied that the transfer and fate of PAHs in the bank soil-WLFZ soil-sediment systems were influenced by both water dynamic factors and physicochemical properties of PAHs. Diagnostic ratio analysis and principal component analysis suggested that the PAHs in the areas of Hanfeng Lake were primarily (>75%) derived from coal combustion and vehicle emissions . Use of natural gas, improving gasoline/diesel quality and phasing out old and nonstandard vehicles and ships are proposed to control PAH contamination and protect drinking water safety in the region.

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.

Land use and sediment yield

USGS Publications Warehouse

Leopold, Luna Bergere; Thomas, William L.

1956-01-01

When the vegetal cover is removed from a land surface, the rate of removal of the soil material, at least initially, increases rapidly. So well known is this principle that it hardly needs restatement.If attention is focused on any individual drainage basin in its natural state, large or small, and inquiry is made as to the rate of denudation, a quantitative answer is not easily obtained. The possible error in any computation of rate of sediment production from any given drainage basin is considerable. Significant variations are found in sediment yields from closely adjacent watersheds which appear to be generally similar. To make a quantitative evaluation of the change in the rate of denudation when the natural vegetation is disturbed is, therefore, even more difficult. Considering the fact that "soil conservation" has been promoted to the status of a science, our lack of ability to answer what is apparently so simple a question may seem surprising. Let us look at some of the reasons.

Correlation of soil and sediment organic matter polarity to aqueous sorption of nonionic compounds

USGS Publications Warehouse

Kile, D.E.; Wershaw, R. L.; Chiou, C.T.

1999-01-01

Polarities of the soiL/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment sam pies were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (K(oc)) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct assessment of the polarity of SOM that is not possible by elemental analysis. The percent of organic carbon associated with polar functional groups was estimated from the combined fraction of carbohydrate and carboxylamide-ester carbons. A plot of the measured partition coefficients (K(oc)) of carbon tetrachloride (CT) vs. percent polar organic carbon (POC) shows distinctly different populations of soils and sediments as well as a roughly inverse trend among the soil/sediment populations. Plots of K(oc) values for CT against other structural group carbon fractions did not yield distinct populations. The results indicate that the polarity of SOM is a significant factor in accounting for differences in K(oc) between the organic matter in soils and sediments. The alternate direct correlation of the sum of aliphatic and aromatic structural carbons with K(oc) illustrates the influence of nonpolar hydrocarbon on solute partition interaction. Additional elemental analysis data of selected samples further substantiate the effect of the organic matter polarity on the partition efficiency of nonpolar solutes. The separation between soil and sediment samples based on percent POC reflects definite differences of the properties of soil and sediment organic matters that are attributable to diagenesis.Polarities of the soil/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment samples were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (Koc) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct assessment of the polarity of SOM that is not possible by elemental analysis. The percent of organic carbon associated with polar functional groups was estimated from the combined fraction of carbohydrate and carboxyl-amide-ester carbons. A plot of the measured partition coefficients (Koc) of carbon tetrachloride (CT) vs. percent polar organic carbon (POC) shows distinctly different populations of soils and sediments as well as a roughly inverse trend among the soil/sediment populations. Plots of Koc values for CT against other structural group carbon fractions did not yield distinct populations. The results indicate that the polarity of SOM is a significant factor in accounting for differences in Koc between the organic matter in soils and sediments. The alternate direct correlation of the sum of aliphatic and aromatic structural carbons with Koc illustrates the influence of nonpolar hydrocarbon on solute partition interaction. Additional elemental analysis data of selected samples further substantiate the effect of the organic matter polarity on the partition efficiency of nonpolar solutes. The separation between soil and sediment samples based on percent POC reflects definite differences of the properties of soil and sediment organic matters that are attributable to diagenesis.

Channel, floodplain, and wetland responses to floods and overbank sedimentation, 1846-2006, Halfway Creek Marsh, Upper Mississippi Valley, Wisconsin

USGS Publications Warehouse

Fitzpatrick, F.A.; Knox, J.C.; Schubauer-Berigan, J. P.

2009-01-01

Conversion of upland forest and prairie vegetation to agricultural land uses, following Euro-American settlement in the Upper Mississippi River System, led to accelerated runoff and soil erosion that subsequently transformed channels, floodplains, and wetlands on bottomlands. Halfway Creek Marsh, at the junction of Halfway Creek and the Mississippi River on Wisconsin's western border, is representative of such historical transformation. This marsh became the focus of a 2005-2006 investigation by scientists from the U.S. Geological Survey, the University of Wisconsin- Madison, and the U.S. Environmental Protection Agency, who used an understanding of the historical transformation to help managers identify possible restoration alternatives for Halfway Creek Marsh. Field-scale topographic surveys and sediment cores provided data for reconstructing patterns and rates of historical overbank sedimentation in the marsh. Information culled from historical maps, aerial photographs, General Land Offi ce Survey notes, and other historical documents helped establish the timing of anthropogenic disturbances and document changes in channel patterns. Major human disturbances, in addition to agricultural land uses, included railroad and road building, construction of artifi cial levees, drainage alterations, and repeated dam failures associated with large floods. A volume of approximately 1,400,000 m3, involving up to 2 m of sandy historical overbank deposition, is stored through the upper and lower marshes and along the adjacent margins of Halfway Creek and its principal tributary, Sand Lake Coulee. The estimated overbank sedimentation rate for the entire marsh is ??3,000 m3 yr-1 for the recent period 1994-2006. In spite of reduced surface runoff and soil erosion in recent years, this recent sedimentation rate still exceeds by ??4 times the early settlement (1846-1885) rate of 700 m3 yr-1, when anthropogenic acceleration of upland surface runoff and soil erosion was beginning. The highest rate of historical bottomland sedimentation occurred from 1919 to 1936, when the estimated overbank sedimentation rate was 20,400 m3 yr- 1. This rate exceeded by nearly 30 times the 1846-1886 rate. Artifi cial levees were constructed along the upper reach of Halfway Creek in the marsh during the early twentieth century to restrict fl ooding on the adjacent bottomlands. Anomalously high overbank sedimentation rates subsequently occurred on the fl oodplain between the levees, which also facilitated more effi cient transport of sediment into the lower marsh bottomland. Although overbank sedimentation rates dropped after 1936, corresponding to the widespread adoption of soil-conservation and agricultural best-management practices, the continuation of anomalously high overbank sedimentation between the levees led to increased bank heights and development of a relatively deep channel. The deep cross-section morphology is commonly mistaken as evidence of channel incision; however, this morphology actually resulted from excessive overbank sedimentation. The historical metamorphosis of the Halfway Creek channel and riparian wetlands underscores the importance of understanding the long-term history of channel and fl oodplain evolution when restoration of channels and riparian wetlands are under consideration. Sedimentation patterns and channel morphology for Halfway Creek Marsh probably are representative of other anthropogenically altered riparian wetlands in the Upper Mississippi River System and similar landscapes elsewhere.

Linear alkylbenzene sulfonates (LAS) in sewage sludges, soils and sediments: analytical determination and environmental safety considerations.

PubMed

De Henau, H; Mathijs, E; Hopping, W D

1986-01-01

Linear Alkylbenzenesulphonates (LAS), a major anionic surfactant used in laundry products, can be measured specifically in the environment by instrumental analysis. In addition to a desulphonation-gas chromatography approach, a method based on high performance liquid chromatography has been developed. The main features of the methods are outlined, and LAS concentrations measured in sewage sludge, sediments and sludge amended soils are reported. Knowledge of usage volumes, sewage treatment practices and environmental transport and transformation mechanisms has been used to predict concentrations of LAS. These calculated concentrations were found to agree well with those actually measured in the environment. Both measured and calculated ambient concentrations of LAS are below those which could produce potentially adverse effects in representative surface water, benthic and terrestrial organisms.

Radiocesium wash-off associated with soil erosion from various land uses after the Fukushima Dai-ichi NPP accident

NASA Astrophysics Data System (ADS)

Wakiyama, Yoshifumi; Onda, Yuichi; Yoshimura, Kazuya; Kato, Hiroaki; Konoplev, Alexei; Zheleznyak, Mark

2014-05-01

Soil erosion is the initial process which drives radiocesium into the aquatic systems and therefore the quantification of radiocesium wash-off associated with soil erosion is indispensable for mitigating the risks. This study presents two year's observation of soil erosion and radiocesium wash-off to quantify differences in radiocesium behavior in various land uses. Seven runoff plots were established in four landscapes; uncultivated farmland (Farmland A1, Farmland B1), cultivated farmland (Farmland A2, Farmland B2), grassland (Grassland A, Grassland B) and Japanese cedar forest (Forest) in Kawamata town, an area affected by the Fukushima Dai-ichi Nuclear Power Plant accident. The discharged sediments were collected approximately every two weeks. In laboratories, collected sediments were dried and weighed for calculating soil erosion rates (kg m-2) and served for measurements of radiocesium concentration (Bq kg-1) with HPGe detectors. The erosivity factor of the Universal Soil Loss Equation (R-factor: MJ mm ha-1 hr-1 yr-1) was calculated based on the data of precipitation. Standardized soil erosion rates (kg m-2 MJ-1 mm-1 ha hr yr), observed soil erosion rates divided by R-factor, was 1.8 × 10-4 in Farmland A1, 6.0 × 10-4 in Farmland A2, 1.5 × 10-3 in Farmland B1, 8.3 × 10-4 in Farmland B2, 9.6 × 10-6 in Grassland A, 5.9 × 10-6 in Grassland B and 2.3 × 10-6 in Forest. These erosion rates were basically proportional to their vegetation cover of soil surfaces except for cultivated farmlands. Concentrations of Cs-137 in eroded sediments basically depended on the local deposition of Cs-137 and varied enormously with ranging several orders of magnitude in all the landscapes. For the observation period of time decreasing trends in concentrations of Cs-137 in eroded sediments were not obvious. To compare these results with those of Chernobyl, we calculated normalized 'solid' wash-off coefficient (m2 g-1) with dividing the mean total concentration of Cs-137 in sediments by local deposition of Cs-137 (Konoplev et al., 1992). The coefficient was 4.4 × 10-5 in Farmland A1, 1.3 × 10-5 in Farmland A2, 6.4 × 10-5 in Farmland B1, 1.0 × 10-5 in Farmland B2, 2.2 × 10-5 in Grassland A, 1.0 × 10-5 in Grassland B and 8.2 × 10-5 in Forest. High erodibilities and relatively low values of normalized wash-off coefficients in cultivated farmlands can be attributed to the mixing of surface soil by ploughing. These values almost corresponded to those of Chernobyl. It was found that the total 'solid' wash-off coefficient of radiocesium from farmlands is high and for 2 years period of time after the accident reaches 10%. Generally high precipitation in the region and steep slopes promote higher wash-off of radiocesium as compared to the Chernobyl case. Also, normalized wash-off coefficients exhibited relatively less volatility than erodibilities in the landscapes. These results suggest that soil erosion management is crucial for mitigating risks of radiocesium.

A step towards a holistic assessment of soil degradation in Europe: Coupling on-site erosion with sediment transfer and carbon fluxes.

PubMed

Borrelli, P; Van Oost, K; Meusburger, K; Alewell, C; Lugato, E; Panagos, P

2018-02-01

Soil degradation due to erosion is connected to two serious environmental impacts: (i) on-site soil loss and (ii) off-site effects of sediment transfer through the landscape. The potential impact of soil erosion processes on biogeochemical cycles has received increasing attention in the last two decades. Properly designed modelling assumptions on effective soil loss are a key pre-requisite to improve our understanding of the magnitude of nutrients that are mobilized through soil erosion and the resultant effects. The aim of this study is to quantify the potential spatial displacement and transport of soil sediments due to water erosion at European scale. We computed long-term averages of annual soil loss and deposition rates by means of the extensively tested spatially distributed WaTEM/SEDEM model. Our findings indicate that soil loss from Europe in the riverine systems is about 15% of the estimated gross on-site erosion. The estimated sediment yield totals 0.164 ± 0.013Pgyr -1 (which corresponds to 4.62 ± 0.37Mgha -1 yr -1 in the erosion area). The greatest amount of gross on-site erosion as well as soil loss to rivers occurs in the agricultural land (93.5%). By contrast, forestland and other semi-natural vegetation areas experience an overall surplus of sediments which is driven by a re-deposition of sediments eroded from agricultural land. Combining the predicted soil loss rates with the European soil organic carbon (SOC) stock, we estimate a SOC displacement by water erosion of 14.5Tg yr -1 . The SOC potentially transferred to the riverine system equals to 2.2Tgyr -1 (~15%). Integrated sediment delivery-biogeochemical models need to answer the question on how carbon mineralization during detachment and transport might be balanced or even off-set by carbon sequestration due to dynamic replacement and sediment burial. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The presence of radioactive materials in soil, sand and sediment samples of Potenga sea beach area, Chittagong, Bangladesh: Geological characteristics and environmental implication

NASA Astrophysics Data System (ADS)

Yasmin, Sabina; Barua, Bijoy Sonker; Uddin Khandaker, Mayeen; Kamal, Masud; Abdur Rashid, Md.; Abdul Sani, S. F.; Ahmed, H.; Nikouravan, Bijan; Bradley, D. A.

2018-03-01

Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226Ra (238U), 232Th and 40K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238U, 232Th and 40K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232Th/238U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232Th/238U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection.

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.

Chemical and biological assessment of Cd-polluted sediment for land use: The effect of stabilization using chitosan-coated zeolite.

PubMed

Wen, Jia; Zeng, Guangming

2018-04-15

Disposal of dredged sediment contaminated with heavy metals on site or in landfills inevitably causes leaching of metals that generate new environmental problems. In this study, we investigated the effectiveness of stabilizing heavy metal Cd in sediment taken from Dongting Lake, China, using a chitosan-coated zeolite, and assessed the feasibility of reusing the stabilized sediment in river bank soil based on chemical and biological analyses. Results showed that the addition of chitosan-coated zeolite significantly reduced acid-exchangeable Cd by 8% in the dredged sediment and 7% in a sediment-soil mixture. Cadmium leachability was greatly reduced in the amended sediment or sediment-soil mixture. Toxicity bioassay using Eisenia fetida showed the mortality rate of worms reduced by 16% in sediment-soil mixture with a Cd concentration of 550 mg/kg and by 17% under a Cd concentration of 250 mg/kg, both with the addition of modified zeolite. Moreover, assimilation of Cd in the earthworms was decreased by a maximum of 36 mg/kg in the sediment-soil mixture with zeolite amendment. These results indicate that the reuse of Cd-contaminated sediment following chitosan-coated zeolite modification is a feasible option for treating the dredged sediment, and could thus benefit both aquatic and terrestrial systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extensive rill erosion and gullying on abandoned pit mining sites in Lusatia, Germany

NASA Astrophysics Data System (ADS)

Kunth, Franziska; Kaiser, Andreas; Vláčilová, Markéta; Schindewolf, Marcus; Schmidt, Jürgen

2015-04-01

As the major economic driver in the province of Lusatia, Eastern Germany, the large open-cast lignite mining sites characterize the landscape and leave vast areas of irreversible changed post-mining landscapes behind. Cost-intensive renaturation projects have been implemented in order to restructure former mine sites into stabile self-sustaining ecosystems and local recreation areas. With considerable expenditure the pits are stabilized, flooded and surrounding areas are restructured. Nevertheless, heavy soil erosion, extensive gullying and slope instability are challenges for the restructuring and renaturation of the abandoned open-cast mining sites. The majority of the sites remain inaccessible to the public due to instable conditions resulting in uncontrolled slides and large gullies. In this study a combined approach of UAV-based aerial imagery, 3D multi-vision surface reconstruction and physically-based soil erosion modelling is carried out in order to document, quantify and better understand the causes of erosion processes on mining sites. Rainfall simulations have been carried out in lausatian post mining areas to reproduce soil detachment processes and observe the responsible mechanisms for the considerable erosion rates. Water repellency and soil sealing by biological crusts were hindering infiltration and consequently increasing runoff rates despite the mainly sandy soil texture. On non-vegetated experimental plots runoff coefficients up to 87 % were measured. In a modelling routine for a major gully catchment regarding a 50 years rainfall event, simulation results reveal runoff coefficients of up to 84% and erosion rates of 118 Mg*ha^-1. At the sediment pass over point 450Mg of sediments enter the surface water bodies. A system response of this order of magnitude were unexpected by the authorities. By applying 3D multi-vision surface reconstruction a model validation is now possible and further may illustrate the great importance of soil conservation measures under the described conditions.

Impacts of biological soil crust disturbance and composition on C and N loss from water erosion

USGS Publications Warehouse

Barger, N.N.; Herrick, J.E.; Van Zee, J.; Belnap, J.

2006-01-01

In this study, we conducted rainfall simulation experiments in a cool desert ecosystem to examine the role of biological soil crust disturbance and composition on dissolved and sediment C and N losses. We compared runoff and sediment C and N losses from intact late-successional dark cyanolichen crusts (intact) to both trampled dark crusts (trampled) and dark crusts where the top 1 cm of the soil surface was removed (scraped). In a second experiment, we compared C and N losses in runoff and sediments in early-successional light cyanobacterial crusts (light) to that of intact late-successional dark cyanolichen crusts (dark). A relatively high rainfall intensity of approximately 38 mm per 10-min period was used to ensure that at least some runoff was generated from all plots. Losses of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonium (NH 4+ ) were significantly higher from trampled plots as compared to scraped and intact plots. Sediment C and N losses, which made up more than 98% of total nutrient losses in all treatments, were more than 4-fold higher from trampled plots relative to intact plots (sediment C g/m2, intact = 0.74, trampled = 3.47; sediment N g/m2, intact = 0.06, trampled = 0.28). In light crusts, DOC loss was higher relative to dark crusts, but no differences were observed in dissolved N. Higher sediment loss in light crusts relative to dark crusts resulted in 5-fold higher loss of sediment-bound C and N. Total C flux (sediment + dissolved) was on the order of 0.9 and 7.9 g/m2 for dark and light crusts, respectively. Sediment N concentration in the first minutes after runoff from light crusts was 3-fold higher than the percent N of the top 1 cm of soil, suggesting that even short-term runoff events may have a high potential for N loss due to the movement of sediments highly enriched in N. Total N loss from dark crusts was an order of magnitude lower than light crusts (dark = 0.06 g N/m2, light = 0.63 g/m2). Overall, our results from the small plot scale (0.5 m2) suggest that C and N losses are much lower from intact late-successional cyanolichen crusts as compared to recently disturbed or early-successional light cyanobacterial crusts. ?? Springer 2006.

Sorption of Cu(2+) on humic acids sequentially extracted from a sediment.

PubMed

Yang, Kun; Miao, Gangfen; Wu, Wenhao; Lin, Daohui; Pan, Bo; Wu, Fengchang; Xing, Baoshan

2015-11-01

In addition to the diverse properties of humic acids (HAs) extracted from different soils or sediments, chemical compositions, functional groups and structures of HAs extracted from a single soil or sediment could also be diverse and thus significantly affect sorption of heavy metals, which is a key process controlling the transfer, transformation and fate of heavy metals in the environment. In this study, we sequentially extracted four HA fractions from a single sediment and conducted the sorption experiments of Cu(2+) on these HA fractions. Our results showed that aromaticity and acidic group content of HA fraction decreased with increasing extraction. Earlier extracted HA fraction had higher sorption capacity and affinity for Cu(2+). There were two fractions of adsorbed Cu(2+) on HAs, i.e., ion exchanged fraction and surface bonded fraction, which can be captured mechanically by the bi-Langmuir model with good isotherm fitting. The ion exchanged fraction had larger sorption capacity but lower sorption affinity, compared with the surface bonded fraction. The dissociated carboxyl groups of HAs were responsible for both fractions of Cu(2+) sorption, due to the more Cu(2+) sorption on the earlier extracted HA fraction with more carboxyl groups and at higher pH. The intensive competition between H(+) and the exchangeable Cu(2+) could result in the decrease of ion exchanged capacity and affinity for Cu(2+) on HAs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of climate and land use changes on recent trend of soil erosion within the Russian Plain

NASA Astrophysics Data System (ADS)

Golosov, Valentin; Yermolaev, Oleg; Rysin, Ivan; Litvin, Leonid; Kiryukhina, Zoya; Safina, Guzel

2016-04-01

The Russian Plain is one of the largest plains with an area of 460 × 106 ha. Soil erosion during snow-melting and rainstorms occurs mostly on arable lands at the Russian Plain. The relative contribution of different types of soil erosion changes from the central part of the Russian Plain to the south. Sheet and rill soil erosion during snow-melting and rainfall are practically equal in the forest zone, while rainfall erosion prevails in the forest-steppe zone and the northern part of the steppe zone. Mostly rainfall erosion is observed in the southern part of the steppe zone. Mean annual soil losses from cultivated lands change in the range from 1 to 3 t ha-1 within lowlands to 6 to 8 t ha-1 at uplands with the maximum (10 t ha-1) observed near the Caucasus Mountains in the Stavropolskiy Krai. The intensity of gully erosion is relatively low during the last two decades. The collapse of the Soviet Union in 1991 caused a serious crisis in the agriculture because of financial problems and structural reorganization. As a result, the area of arable lands decreased in the southern half of the Russian Plain in 1991 - 2003. To a greater extent it was observed in the south of the forest zone because of the low productivity of its soils compared with chernozem. More than one third of the arable lands were abandoned in the dry steppe - semi-desert zones because these lands were irrigated during the Soviet period. The reduction of the arable land occurred in the forest-steppe and steppe zones mostly because of funding limitations during the 1990s. Recently the area of arable lands in the steppe zone was practically restored to its pre-1991 size. Simultaneously the last 25 years are characterized by unusual warm winters - in particular, in the southern half of the Russian Plain because of the global warming. As a result, the coefficient of surface snow-melting runoff considerably decreased for both cultivated fields and compacted fields after harvesting. Accordingly, spring flood levels decreased considerably - in particular, in small rivers. This is confirmed by a serious decrease of floodplain sedimentation rates since 1986 compared with the period from 1964 to 1986. As a result of both positive trend of extreme rainfall and negative trend of surface snow melting runoff, the proportion of sediments eroded from cultivated slopes and delivered by surface runoff to river channels decreased considerably during the last few decades in the southern part of the Russian Plain. Complex assessment of different erosion factors changes is undertaken for the different landscape zones of the Russian Plain. Given analysis allows evaluating of recent trend in erosion rates from cultivated lands. The other indicators of sediment redistribution dynamic (gully head retreat rate, floodplain sedimentation) are also used for assessment of soil erosion rate dynamic under land use and climate changes during last 25-30 years.

76 FR 32081 - National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-03

... County. Groundwater near the Site is used for domestic purposes, including drinking water. Landfill No. 1... synthetic liner. The permit also required leachate collection, installation of groundwater monitoring wells... investigation during the RI/FS included waste, leachate, groundwater, surface water and sediment, soil, and air...

Plant Growth and Phosphorus Uptake of Three Riparian Grass Species

USDA-ARS?s Scientific Manuscript database

Riparian buffers can significantly reduce sediment-bound phosphorus (P) entering surface water, but control of dissolved P inputs is more challenging. Because plant roots remove P from soil solution, it follows that plant uptake will reduce dissolved P losses. We evaluated P uptake of smooth bromegr...

Pesticide management and their residues in sediments and surface and drinking water in the Mekong Delta, Vietnam.

PubMed

Toan, Pham Van; Sebesvari, Zita; Bläsing, Melanie; Rosendahl, Ingrid; Renaud, Fabrice G

2013-05-01

Public concern in Vietnam is increasing with respect to pesticide pollution of the environment and of drinking water resources. While established monitoring programs in the Mekong Delta (MD) focus on the analysis of organochlorines and some organophosphates, the environmental concentrations of more recently used pesticides such as carbamates, pyrethroides, and triazoles are not monitored. In the present study, household level pesticide use and management was therefore surveyed and combined with a one year environmental monitoring program of thirteen relevant pesticides (buprofezin, butachlor, cypermethrin, α-endosulfan, β-endosulfan, endosulfan-sulfate, fenobucarb, fipronil, isoprothiolane, pretilachlor, profenofos, propanil, and propiconazole) in surface water, soil, and sediment samples. The surveys showed that household level pesticide management remains suboptimal in the Mekong Delta. As a consequence, a wide range of pesticide residues were present in water, soil, and sediments throughout the monitoring period. Maximum concentrations recorded were up to 11.24 μg l(-1) in water for isoprothiolane and up to 521 μg kg(-1) dm in sediment for buprofezin. Annual average concentrations ranged up to 3.34 μg l(-1) in water and up to 135 μg kg(-1) dm in sediment, both for isoprothiolane. Occurrence of pesticides in the environment throughout the year and co-occurrence of several pesticides in the samples indicate a considerable chronic exposure of biota and humans to pesticides. This has a high relevance in the delta as water for drinking is often extracted from canals and rivers by rural households (GSO, 2005, and own surveys). The treatment used by the households for preparing surface water prior to consumption (flocculation followed by boiling) is insufficient for the removal of the studied pesticides and boiling can actually increase the concentration of non-volatile pollutants. Copyright © 2012 Elsevier B.V. All rights reserved.