Elemental concentration and potential ecological risk assessment of reef associated surface sediments of Appa Island, Gulf of Mannar Biosphere Reserve, Southeast coast of India.

PubMed

Saravanan, P; Krishnakumar, S; Silva, Judith D; Pradhap, D; Vidyasakar, A; Radhakrishnan, K; Godson, Prince S; Arumugam, K; Magesh, N S

2018-03-01

Thirty three surface sediments were collected for the present study to assess the elemental concentration and its associated ecological risk in the reef associated surface sediments, Appa Island, Gulf of Mannar Biosphere Reserve, South east coast of India. The distribution of calcium carbonate in the reef sediments is controlled by coral debris and shell fragments whereas the Organic matter (OM) content are chiefly derived from mangroves and sea grasses. The circulation of trace elements and Fe, Mn are controlled by the fluvial process and re-suspended sediments. The concentration of Pb was primarily controlled by migration of pollutants through long shore sediment transport process. The main source of Pb in the study area is from coal incinerating power plants and coal handling operations from harbors. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

PubMed

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

2016-03-07

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

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Role of organic phosphorus in sediment in a shallow eutrophic lake

NASA Astrophysics Data System (ADS)

Shinohara, Ryuichiro; Hiroki, Mikiya; Kohzu, Ayato; Imai, Akio; Inoue, Tetsunori; Furusato, Eiichi; Komatsu, Kazuhiro; Satou, Takayuki; Tomioka, Noriko; Shimotori, Koichi; Miura, Shingo

2017-08-01

We tested the hypothesis that mineralization of molybdenum unreactive phosphorus (MUP) in pore water is the major pathway for the changes in the concentration of molybdenum-reactive P (MRP) in pore water and inorganic P in sediment particles. The concentration of inorganic P in the sediment particles increased from December to April in Lake Kasumigaura, whereas concentrations of organic P in the sediment particles and MUP in pore water decreased. These results suggest that MUP mineralization plays a key role as the source of MRP, whereas desorption of inorganic P from the sediment particles into the pore water is a minor process. One-dimensional numerical simulation of sediment particles and the pore water supported the hypothesis. Diffusive flux of MUP was small in pore water, even in near-surface layers, so mineralization was the dominant process for changing the MUP concentration in the pore water. For MRP, diffusion was the dominant process in the surface layer, whereas adsorption onto the sediment was the dominant process in deeper layers. Researchers usually ignore organic P in the sediment, but organic P in sediment particles and the pore water is a key source of inorganic P in the sediment particles and pore water; our results suggest that in Lake Kasumigaura, organic P in the sediment is an important source, even at depths more than 1 cm below the sediment surface. In contrast, the large molecular size of MUP in pore water hampers diffusion of MUP from the sediment into the overlying water.

Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

NASA Technical Reports Server (NTRS)

Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

2000-01-01

This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

Three decades of TBT contamination in sediments around a large scale shipyard.

PubMed

Kim, Nam Sook; Shim, Won Joon; Yim, Un Hyuk; Ha, Sung Yong; An, Joon Geon; Shin, Kyung Hoon

2011-08-30

Tributyltin (TBT) contamination in sediments was investigated in the vicinity of a large-scale shipyard in the years after the implementation of a total ban on the use of TBT based antifouling paints in Korea. Extremely high level of TBT (36,292ng Sn/g) in surface sediment was found at a station in front of a drydock and near surface runoff outfall of the shipyard. TBT concentration in surface sediments of Gohyeon Bay, where the shipyard is located, showed an apparent decreased TBT concentration gradient from the shipyard towards the outer bay. The vertical distribution of TBT contamination derived from a sediment core analysis demonstrated a significant positive correlation (r(2)=0.88; p<0.001) with the annual tonnage of ship-construction in the shipyard within the past three decades. TBT concentrations at six stations surveyed before (2003) and seven years after (2010) the total ban showed no significant differences (p>0.05). Despite the ban on the use of TBT, including ocean going vessels, surface sediments are still being heavily contaminated with TBT, and its levels well exceeded the sediment quality guideline or screening values. Copyright © 2011 Elsevier B.V. All rights reserved.

Spatial and Vertical Distribution of Dechlorane Plus in Mangrove Sediments of the Pearl River Estuary, South China.

PubMed

Sun, Yu-Xin; Zhang, Zai-Wang; Xu, Xiang-Rong; Hao, Qin-Wei; Hu, Yong-Xia; Zheng, Xiao-Bo; Luo, Xiao-Jun; Diao, Zeng-Hui; Mai, Bi-Xian

2016-10-01

Thirty surface sediments and three sediment cores were collected from mangrove wetlands in the Pearl River Estuary of South China to investigate the spatial and vertical distribution of Dechlorane Plus (DP). DP concentrations in the mangrove surface sediments ranged from 0.0130 to 1.504 ng/g dry weight (dw). DP concentrations in sediments from Shenzhen were significantly greater than those from Guangzhou and Zhuhai. Anti-Cl11-DP, the dechlorinated product of anti-DP, was also detected in the mangrove sediments with concentrations ranged from not detected to 0.0198 ng/g dw. Significant positive relationship between anti-Cl11-DP and anti-DP levels was observed in the mangrove sediments, suggesting that photo and/or microbial degradation of anti-DP might occur in the sediments. The f anti values in the mangrove sediments were close to those in the technical DP products, suggesting that stereoselective enrichment of anti-DP may not exist in the mangrove sediments. DP concentrations in the mangrove sediment cores generally showed an increasing trend from the bottom to top layers. This is the first study to report the occurrence of DP and its degradation product in the mangrove wetlands.

Mercury accumulation in periphyton of eight river ecosystems

USGS Publications Warehouse

Bell, A.H.; Scudder, B.C.

2007-01-01

In 2003, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected using trace element clean techniques and NAWQA sampling protocols in spring and fall from targeted habitats (streambed surface-sediment, cobble, or woody snags) at each river site. A positive correlation was observed between concentrations of THg and MeHg in periphyton (r2 = 0.88, in log-log space). Mean MeHg and THg concentrations in surface-sediment periphyton were significantly higher (1,333 ng/m2 for MeHg and 53,980 ng/m2 for THg) than cobble (64 ng/m2 for MeHg and 1,192 ng/m2 for THg) or woody snag (71 ng/m2 for MeHg and 1,089 ng/m2 for THg) periphyton. Concentrations of THg in surface-sediment periphyton had a strong positive correlation with concentrations of THg in sediment (dry weight). The ratio of MeHg:THg in surface-sediment periphyton increased with the ratio of MeHg:THg in sediment. These data suggest periphyton may play a key role in mercury bioaccumulation in river ecosystems. ?? 2007 American Water Resources Association.

Spatial distribution and risk assessment of heavy metals and As pollution in the sediments of a shallow lake.

PubMed

Deng, Jiancai; Wang, Yuansheng; Liu, Xin; Hu, Weiping; Zhu, Jinge; Zhu, Lin

2016-05-01

The concentrations and spatial distributions of eight heavy metals in surface sediments and sediment core samples from a shallow lake in China were investigated to evaluate the extent of the contamination and potential ecological risks. The results showed that the heavy metal concentrations were higher in the northern and southwestern lake zones than those in the other lake zones, with lower levels of As, Hg, Zn, Cu, Pb, Cr, and Ni primarily observed in the central and eastern lake regions and Cd primarily confined to areas surrounding the lake. The concentrations of the eight heavy metals in the sediment profiles tended to decrease with increasing sediment depth. The contents of Ni, Cu, Zn, Pb, and Cd in the surface sediment were approximately 1.23-18.41-fold higher than their background values (BVs), whereas the contents of Cr, As, and Hg were nearly identical to their BVs. The calculated pollution load index (PLI) suggested that the surface sediments of this lake were heavily polluted by these heavy metals and indicated that Cd was a predominant contamination factor. The comprehensive potential ecological risk index (PERI) in the surface sediments ranged from 99.2 to 2882.1, with an average of 606.1. Cd contributed 78.7 % to the PERI, and Hg contributed 8.4 %. Multivariate statistical analyses revealed that the surface sediment pollution with heavy metals mainly originated from industrial wastewater discharged by rivers located in the western and northwestern portion of the lake.

Polycyclic aromatic hydrocarbon pollution in the surface water and sediments of Chabahar Bay, Oman Sea.

PubMed

Agah, Homira; Mehdinia, Ali; Bastami, Kazem Darvish; Rahmanpour, Shirin

2017-02-15

In the present study, the concentrations and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in the water and surface sediments from the Chabahar Bay, Oman Sea, were investigated in May (premonsoon) and December (postmonsoon) 2012. The concentrations of PAHs in the surface water samples ranged from 1.7 to 2.8ngl -1 and from 0.04 to 59.6ngl -1 in pre- and postmonsoon, respectively. In general, the PAH levels of the water samples from Chabahar Bay were higher in postmonsoon than in premonsoon (p<0.05). The concentrations of PAHs in the sediment samples varied from undetectable levels to 92.8ngg -1 d.w. in both seasons. The seasonal comparison of the results in sediment samples showed that the overall concentration of PAH compounds was higher in the postmonsoon season (p<0.05). Copyright © 2016. Published by Elsevier Ltd.

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

PubMed Central

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

2016-01-01

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

Trace metal pollution assessment in the surface sediments of nearshore area, off Calicut, southwest coast of India.

PubMed

Srinivas, Reji; Shynu, R; Sreeraj, M K; Ramachandran, K K

2017-07-15

Metal concentrations (Al, Cr, Ni, Cu, Zn, and Pb), grain size, and total organic carbon content in 29 surface sediment samples from the nearshore area off Calicut were analyzed to determine their distribution and pollution status. Surface sediments were dominantly silts with low percentage of clay and sand at nearshore and offshore areas. The mean metal concentrations were in the following order: Cr>Ni>Zn>Pb>Cu. The enrichment factor and geo-accumulation index of metals suggest that the surface sediments were not polluted by Zn and moderately polluted by Cu and Ni. By contrast, Cr and Pb showed significant enrichment levels. Results from a multivariate statistical analysis suggested that the spatial enrichment of these heavy metals was related to sediment type. Thus, the sediment distribution and their metal enrichment were mainly controlled by local hydrodynamic conditions that caused the winnowing of fine-grained sediments. Copyright © 2017. Published by Elsevier Ltd.

Vertical distribution of trace-element concentrations and occurrence of metallurgical slag particles in accumulated bed sediments of Lake Roosevelt, Washington, September 2002

USGS Publications Warehouse

Cox, S.E.; Bell, P.R.; Lowther, J.S.; Van Metre, P.C.

2005-01-01

Sediment cores were collected from six locations in Lake Roosevelt to determine the vertical distributions of trace-element concentrations in the accumulated sediments of Lake Roosevelt. Elevated concentrations of arsenic, cadmium, copper, lead, mercury, and zinc occurred throughout much of the accumulated sediments. Concentrations varied greatly within the sediment core profiles, often covering a range of 5 to 10 fold. Trace-element concentrations typically were largest below the surficial sediments in the lower one-half of each profile, with generally decreasing concentrations from the 1964 horizon to the surface of the core. The trace-element profiles reflect changes in historical discharges of trace elements to the Columbia River by an upstream smelter. All samples analyzed exceeded clean-up guidelines adopted by the Confederated Tribes of the Colville Reservation for cadmium, lead, and zinc and more than 70 percent of the samples exceeded cleanup guidelines for mercury, arsenic, and copper. Although 100 percent of the samples exceeded sediment guidelines for cadmium, lead, and zinc, surficial concentrations of arsenic, copper, and mercury in some cores were less than the sediment-quality guidelines. With the exception of copper, the trace-element profiles of the five cores collected along the pre-reservoir Columbia River channel typically showed trends of decreasing concentrations in sediments deposited after the 1964 time horizon. The decreasing concentrations of trace elements in the upper half of cores from along the pre-reservoir Columbia River showed a pattern of decreasing concentrations similar to reductions in trace-element loading in liquid effluent from an upstream smelter. Except for arsenic, trace-element concentrations typically were smaller at downstream reservoir locations along the pre-reservoir Columbia River. Trace-element concentration in sediments from the Spokane Arm of the reservoir showed distinct differences compared to the similarities observed in cores from along the pre-reservoir Columbia River. Particles of slag, which have physical and chemical characteristics of slag discharged to the Columbia River by a lead-zinc smelter upstream of the reservoir at Trail, British Columbia, were found in sediments of Lake Roosevelt. Slag particles are more common in the upstream reaches of the reservoir. The chemical composition of the interior matrix of slag collected from Lake Roosevelt closely approximated the reported elemental concentrations of fresh smelter slag, although evidence of slag weathering was observed. Exfoliation flakes were observed on the surface of weathered slag particles isolated from the core sediments. The concentrations of zinc on the exposed surface of slag grains were smaller than concentrations on interior surfaces. Weathering rinds also were observed in the cross section of weathered slag grains, indicating that the glassy slag material was undergoing hydration and chemical weathering. Trace elements observed in accumulated sediments in the middle and lower reaches of the reservoir are more likely due to the input from liquid effluent discharges compared to slag discharges from the upstream smelter.

The metal oxide fraction of pelagic sediment in the equatorial North Pacific Ocean: A source of metals in ferromanganese nodules

USGS Publications Warehouse

Piper, D.Z.

1988-01-01

Pelagic sediment recovered at DOMES Site A in the equatorial North Pacific (151??W, 9?? 15???N) consists of a surface homogeneous layer, approximately 10 cm thick, overlying a strongly mottled layer that is lighter in color. The radiolarian composition of both units is Quaternary. In areas where this sediment was only a few centimeters thick, the underlying sediment was early Tertiary. Clay mineralogy and major oxide composition of the two Quaternary sediments are uniform. Their similarity to continental shale suggests that the sediment has a terrigenous source. Clay mineralogy and major oxide composition of the Tertiary sediment also are uniform, although they differ markedly from the Quarternary sediment. In contrast to the major oxides, concentrations of Mn, Co, Cu, and Ni soluble in hydroxylamine hydrochlorideacetic acid are strongly different in the surface and subsurface Quaternary sediment. Mn and Ni exhibit pronounced depletions in the subsurface sediment, Ni slightly more than Mn. Cu is also depleted in the subsurface sediment, but less than Mn. It is also depleted in the subsurface Tertiary sediment, whereas the Mn concentration remains high. Concentration of Co relative to Mn increases into the subsurface Quaternary sediment to a constant Co:Mn ratio of 3 ?? 10-2. The trivalent REE (the REE exclusive of Ce) and Fe exhibit little down-core variation. Distribution of elements in these sediments is closely related to their concentration in associated surface ferromanganese nodules. The nodules are of two distinct types: those from the area where the Quaternary sediment is relatively thick have ??-MnO2 as the dominant manganese mineral. The ratios of Ni:Mn, Cu:Mn, and Fe:Mn in these nodules approximate the corresponding ratios of the soluble fraction of surface sediment. Todorokite is the dominant mineral of nodules recovered from areas where the Quaternary sediment is thin. Relatively high Cu/Mn, Ni/Mn, and low Fe/Mn ratios of these nodules mirror differences between the soluble fraction of surface and subsurface Quaternary sediment. These compositional trends of sediment and nodules at DOMES Site A reflect a diagenetic origin for the todorokite nodules and a predominantly hydrogenous origin for the ??-MnO2 nodules. ?? 1988.

Mercury, methylmercury, and other constituents in sediment and water from seasonal and permanent wetlands in the Cache Creek settling basin and Yolo Bypass, Yolo County, California, 2005-06

USGS Publications Warehouse

Marvin-DiPasquale, Mark; Alpers, Charles N.; Fleck, Jacob A.

2009-01-01

This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three locations within the Cache Creek drainage basin; two within the Cache Creek Nature Preserve (CCNP) and one in the Cache Creek Settling Basin (CCSB) within the creek's main channel near the southeast outlet to the Yolo Bypass. Two additional downstream sites within the Yolo Bypass Wildlife Area (YBWA) were also sampled during Phase I, including one permanently flooded wetland and one seasonally flooded wetland, which had began being flooded only 1–2 days before Phase I sampling.Results from Phase I include: (a) a negative correlation between total mercury (THg) and the percentage of methylmercury (MeHg) in unfiltered surface water; (b) a positive correlation between sediment THg concentration and sediment organic content; (c) surface water and sediment THg concentrations were highest at the CCSB site; (d) sediment inorganic reactive mercury (Hg(II)R) concentration was positively related to sediment oxidation-reduction potential and negatively related to sediment acid volatile sulfur (AVS) concentration; (e) sediment Hg(II)R concentrations were highest at the two YBWA sites; (f) unfiltered surface water MeHg concentration was highest at the seasonal wetland YBWA site, and sediment MeHg was highest at the permanently flooded YBWA site; (g) a 1,000-fold increase in sediment pore water sulfate concentration was observed in the downstream transect from the CCNP to the YBWA; (h) low sediment pore water sulfide concentrations (<1 µmol/L) across all sites; and (i) iron (Fe) speciation data suggest a higher potential for microbial Fe(III)-reduction in the YBWA compared to the CCSB.Phase II sampling did not include the original three Cache Creek sites, but instead focused on the original two sites within the YBWA and a similarly paired set of seasonally and permanently flooded wetland sites within the CCSB. Sediment sampling at the YBWA and CCSB occurred approximately 28 days and 52 days, respectively, after the initial flooding of the respective seasonal wetlands, and again towards the end of the seasonal flooding period (end of May 2006). Results from Phase II sampling include: (a) sediment MeHg concentration and the percentage of THg as MeHg (%MeHg) in unfiltered surface waters were generally higher in the YBWA compared to the CCSB; (b) suspended sediment concentration (SCC) in surface water was positively correlated with both THg and MeHg in unfiltered water across all sites, although the relationship between SCC and MeHg differed for the two regions, suggesting local MeHg sources; (c) MeHg concentration in unfiltered surface water was positively correlated to sediment MeHg concentrations across all sites, supporting the suggestion of unique local (sediment) sources of MeHg to the water column; (d) THg concentration in filtered water was positively correlated with both total Fe and dissolved organic carbon (DOC), offering additional support for the role of these constituents in the partitioning of THg between particulate and dissolved phases; (e) flooding of the YBWA seasonal wetland resulted in a rapid and significant (5-fold) rise in sediment MeHg concentration within 3–4 weeks following inundation; and (f) temporal changes in sediment S and Fe speciation suggest that rates of both microbial sulfate reduction and Fe(III)-reduction were significantly higher at YBWA, compared to CCSB, during the period between flooding and drying.The geochemical data presented in this report indicate that (a) strong spatial and temporal differences in Hg speciation and transformations can occur within the range of wetland habitats found in the lower Sacramento River basin; (b) flooding of seasonal wetlands can be accompanied by a rapid increase in benthic MeHg production and the release of previously formed MeHg (generated during or since the previous flooding season) to the overlying water column; (c) S and Fe chemistry, and associated microbial reduction pathways, play an important role in mediating the speciation and transformation of Hg in these wetland habitats; (d) hydroperiod is a primary forcing function in mediating MeHg production among various wetland types; and (e) MeHg production appears to be more active in the YBWA compared to the CCSB.

Concentration of Antifouling Biocides and Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay

PubMed Central

Tsunemasa, Noritaka; Yamazaki, Hideo

2014-01-01

Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter’s degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT) and triphenyltin (TPT)) were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn) levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation. PMID:24901529

Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower East Tampa Bay

EPA Science Inventory

Contaminant concentrations are reported for surface water, sediment, seagrass, mangroves, Florida Crown conch, blue crabs and fish collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay. Concentrations of trace metals, chlorinated pesticides, atrazine, total ...

Sediment production from forest road surfaces.

Treesearch

Leslie Reid; T. Dunne

2011-01-01

Erosion on roads is an important source of fine-grained sediment in streams draining logged basins of the Pacific Northwest. Runoff rates and sediment concentrations from 10 road segments subject to a variety of traffic levels were monitored to produce sediment rating curves and unit hydrographs for different use levels and types of surfaces. These relationships are...

Assessment of heavy metal contamination in the sediments of Nansihu Lake Catchment, China.

PubMed

Liu, Enfeng; Shen, Ji; Yang, Liyuan; Zhang, Enlou; Meng, Xianghua; Wang, Jianjun

2010-02-01

At present, anthropogenic contribution of heavy metals far exceeds natural input in some aquatic sediment, but the proportions are difficult to differentiate due to the changes in sediment characters. In this paper, the metal (Al, Fe, K, Mg, Ca, Cr, Cu, Ni, and Zn) concentrations, grain size, and total organic carbon (TOC) content in the surface and core sediments of Nansihu Lake Catchment (the open lake and six inflow rivers) were determined. The chemical speciations of the metals (Al, Fe, Cr, Cu, Ni, and Zn) in the surface sediments were also analyzed. Approaches of factor analysis, normalized enrichment factor (EF) and the new non-residual fractions enrichment factor (K(NRF)) were used to differentiate the sources of the metals in the sediments, from detrital clastic debris or anthropogenic input, and to quantify the anthropogenic contamination. The results indicate that natural processes were more dominant in concentrating the metals in the surface and core sediments of the open lake. High concentration of Ca and deficiency of other metals in the upper layers of the sediment core were attributed to the input of carbonate minerals in the catchment with increasing human activities since 1980s. High TOC content magnified the deficiency of the metals. Nevertheless, the EF and K(NRF) both reveal moderate to significant anthropogenic contamination of Cr, Cu, Ni, and Zn in the surface sediments of Laoyun River and the estuary and Cr in the surface sediments of Baima River. The proportion of non-residual fractions (acid soluble, reducible, and oxidizable fractions) of Cr, Cu, Ni, and Zn in the contaminated sediments increased to 37-99% from the background levels less than 30%.

Spatial and temporal distribution and sources of polycyclic aromatic hydrocarbons in sediments of Taihu Lake, eastern China.

PubMed

Tang, Zhi; Guo, Jianyang; Liao, Haiqing; Zhao, Xiaoli; Wu, Fengchang; Zhu, Yuanrong; Zhang, Liang; Giesy, John P

2015-04-01

Spatial and temporal distributions of concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and dated sediment core from Taihu Lake in eastern China were determined. The sum of concentrations of PAHs (sum of total 16 USEPA priority PAH (∑PAHs)) of the entire Taihu Lake ranged from 2.9 × 10(2) to 8.4 × 10(2) ng/g dry mass (dm). Concentrations of ∑PAHs in surface sediments near more urbanized regions of the lake shore were greater than those in areas more remote from the urban centers. Temporal trends in concentrations of ∑PAHs ranged from 5.1 × 10(2) to 1.5 × 10(3) ng/g dm, increasing from deeper layers to surface sediments with some fluctuations, especially in the past three decades after the inception of China's Reform and Opening Up Policy, in which China's economy and urbanization underwent rapid development. Forensic analysis of surface sediments indicates that PAHs originated primarily from combustion of grass/wood/coal except for the special function water area, which was most likely influenced by petroleum products of traveling vessels. Vertical profiles of relative concentrations of PAHs suggested that the contribution of lesser-molecular-weight PAHs was gradually decreasing, while due to the heavier consumption of petroleum products, the proportion of greater-molecular-weight PAHs was increasing. When assessed by use of the rather conservative, apparent effect threshold method, concentrations of ∑PAHs in sediments from most locations in Taihu Lake are predicted to pose little risk of harm to benthic invertebrates.

Effects of Offshore Oil Exploration and Development in the Alaskan Beaufort Sea: A Three-Decade Record for Sediment Metals.

PubMed

Trefry, John H; Neff, Jerry M

2018-06-19

Impacts from oil exploration, development and production in the Beaufort Sea, Alaska, are assessed using concentrations of metals in sediments collected during 2014-15, combined with a large dataset for 1985-2006. Concentrations of 7 (1980 s) or 17 (1999-2015) metals in 423 surface sediments from 134 stations, plus 563 samples from 30 cores were highly variable, primarily as a function of sediment granulometry with naturally greater metal concentrations in fine-grained, Al-rich sediment. Metals versus Al correlation plots were used to normalize metal concentrations and identify values significantly above background. Barium, Cr, Cu, Hg and Pb concentrations were above background, but variable, within 250 m of some offshore sites where drilling occurred between 1981-2001; these areas totaled <6 km 2 of 11,000 km 2 in the total lease area. Random and fixed sampling along the coastal Beaufort Sea from 1985-2015 yielded 40 positive anomalies for metals in surface sediments (∼0.8% of 5,082 data points). About 85% of the anomalies were from developed areas. Half the anomalies were for the five metals found enhanced near drilling sites. No metals concentrations, except As, exceeded accepted sediment quality criteria. Interannual shifts in metals values for surface sediments at inner shelf sites were common and linked to storm-induced transitions in granulometry; however, metal/Al ratios were uniform during these shifts. Sediment cores generally recorded centuries of background values, except for As, Fe and Mn. These three metals were naturally enriched in sediments from deeper water (>100 m) via diagenetic remobilization at sediment depths of 5-15 cm, upward diffusion, and precipitation in surface oxic layers. Minimal evidence for anthropogenic inputs of metals, except near some exploratory drilling sites, is consistent with extraction of most oil from land or barrier islands in the Alaskan Arctic and restricted offshore activity to date. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Rare earth elements in intertidal sediments of Bohai Bay, China: concentration, fractionation and the influence of sediment texture.

PubMed

Zhang, Yong; Gao, Xuelu; Arthur Chen, Chen-Tung

2014-07-01

Surface sediments from intertidal Bohai Bay were assessed using a four-step sequential extraction procedure to determine their concentrations of rare earth elements (REEs) and the chemical forms in which those elements were present. The normalized ratios La/Gd and La/Yb showed that LREE contents were not significantly higher than the middle REEs or HREE contents. A negative Ce anomaly and positive Eu were observed in sand and silty sand sediments, whereas no significant Ce or Eu anomaly was found in clayey silt sediments. Residual fraction of REEs accounted for the majority of their total concentrations. Middle REEs were more easily leached than other REEs, especially in clayey silt sediment. REEs contents in the surface sediment from the intertidal Bohai Sea were consistent with data from the upper continental crust and China shallow sea sediments, indicating that they were generally unaffected by heavily anthropogenic effects from adjacent areas. Copyright © 2014 Elsevier Inc. All rights reserved.

Contaminants in surface water and sediments near the Tynagh silver mine site, County Galway, Ireland.

PubMed

O'Neill, A; Phillips, D H; Bowen, J; Sen Gupta, B

2015-04-15

A former silver mine in Tynagh, Co. Galway, Ireland is one of the most contaminated mine sites in Europe with maximum concentrations of Zn, As, Pb, Mn, Ni, Cu, and Cd far exceeding guideline values for water and sediment. The aims of this research were to 1) further assess the contamination, particularly metals, in surface water and sediment around the site, and 2) determine if the contamination has increased 10 years after the Environmental Protection Agency Ireland (EPAI) identified off-site contamination. Site pH is alkaline to neutral because CaCO3-rich sediment and rock material buffer the exposed acid generating sulphide-rich ore. When this study was compared to the previous EPAI study conducted 10 years earlier, it appeared that further weathering of exposed surface sediment had increased concentrations of As and other potentially toxic elements. Water samples from the tailings ponds and adjacent Barnacullia Stream had concentrations of Al, Cd, Mn, Zn and Pb above guideline values. Lead and Zn concentrations from the tailings pond sediment were 16 and 5 times higher, respectively, than concentrations reported 10 years earlier. Pb and Zn levels in most sediment samples exceeded the Expert Group (EGS) guidelines of 1000 and 5000 mg/kg, respectively. Arsenic concentrations were as high as 6238 mg/kg in the tailings ponds sediment, which is 62 and 862 times greater than the EGS and Canadian Soil Quality Guidelines (CSQG), respectively. Cadmium, Cu, Fe, Mn, Pb and Zn concentrations in water and sediment were above guideline values downstream of the site. Additionally, Fe, Mn and organic matter (OM) were strongly correlated and correlated to Zn, Pb, As, Cd, Cu and Ni in stream sediment. Therefore, the nearby Barnacullia Stream is also a significant pathway for contaminant transport to downstream areas. Further rehabilitation of the site may decrease the contamination around the area. Copyright © 2015 Elsevier B.V. All rights reserved.

Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors.

PubMed

Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

2014-04-15

This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community. Copyright © 2014 Elsevier B.V. All rights reserved.

Arsenic and lead distribution and mobility in lake sediments in the south-central Puget Sound watershed: the long-term impact of a metal smelter in Ruston, Washington, USA.

PubMed

Gawel, James E; Asplund, Jessica A; Burdick, Sarah; Miller, Michelle; Peterson, Shawna M; Tollefson, Amanda; Ziegler, Kara

2014-02-15

The American Smelting and Refining Company (ASARCO) smelter in Ruston, Washington, contaminated the south-central Puget Sound region with heavy metals, including arsenic and lead. Arsenic and lead distribution in surface sediments of 26 lakes is significantly correlated with atmospheric model predictions of contaminant deposition spatially, with concentrations reaching 208 mg/kg As and 1,375 mg/kg Pb. The temporal distribution of these metals in sediment cores is consistent with the years of operation of the ASARCO smelter. In several lakes arsenic and lead levels are highest at the surface, suggesting ongoing inputs or redistribution of contaminants. Moreover, this study finds that arsenic is highly mobile in these urban lakes, with maximum dissolved arsenic concentrations proportional to surface sediment levels and reaching almost 90 μg/L As. With 83% of the lakes in the deposition zone having surface sediments exceeding published "probable effects concentrations" for arsenic and lead, this study provides evidence for possible ongoing environmental health concerns. Copyright © 2013 Elsevier B.V. All rights reserved.

Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge

USGS Publications Warehouse

Colby, B.R.

1963-01-01

This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

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.

Concentration of selected trace elements and PCBs in sediments from the Adriatic Sea

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

Fowler, S W; Hamilton, T F; Coquery, M

2000-07-26

A broad baseline study of the levels and distributions of trace metals and PCB compounds in sediments has been undertaken. PCB concentrations in surface sediments reflect the source of these contaminates in the region. The highest PCB concentrations as Aroclor 1260 (approximately 10 ng g{sup -1}) were found in sediments near the outflow of the Po river. The lowest concentrations (1.5 ng g{sup -1} dry) were associated with the sediments from the Jabuka Pit in the Middle Adriatic. These values are quite similar to total PCBs (<1.0-17) measured in surface sediments sampled off the coast of Croatia in 1977-78. Thus,more » based on the limited amount of new data available, it appears that there has been little, if any, decrease in PCB loading in Adriatic sediments over the past 15 years. Downcore profiles of PCBs in sediment cores are also discussed from a pollution history standpoint. Likewise, total mercury in surface sediments was also highest at stations off the Po (403-499 ng g{sup -1} dry) and lowest (67-224 ng g{sup -1}) in the Jabuka Pit. In one core located just south of the Po outflow, total Hg concentrations at all depths were relatively high decreasing gradually from approximately 400 ng g{sup -1} in the top 4 cm to roughly 200 ng g{sup -1} at a depth of 32 cm. Using a {sup 210}Pb-derived sedimentation rate of 0.26 em Y{sup -1} for this station, it appears that anthropogenic inputs of mercury may have been responsible for the gradual increase in total mercury noted over the last 125 years.« less

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sediments from the Gulf of Batabanó, Cuba.

PubMed

Alonso-Hernandez, C M; Mesa-Albernas, M; Tolosa, I

2014-01-01

The spatial distribution of various organochlorinated compounds, e.g. PCBs, DDTs, HCB and HCHs, were investigated in sediments of the Gulf of Batabanó, Cuba. Among the target organochlorine compounds measured, ΣDDT isomers were the predominant contaminant with concentrations ranging from 0.019 to 1.27 ng g(-1)dry wt. Lindane was present at very low concentrations in the range n.d. to 0.05 ng g(-1), while PCBs and other organochlorine pesticide residues, such as HCB, Heptaclor, Aldrin and Mirex were lower than detection limits (∼0.010 ng g(-1)). According to established sediment quality guidelines, the OCPs concentrations encountered in the surface sediments are probably not having an adverse effect on sediment dwelling organisms. Compared to concentrations reported in coastal environments from other parts of the world, PCBs and OCs concentrations in surface sediments of Batabanó Gulf were low and similar to the reported for remote and pristine environments. These results contribute to the sparse regional database for organochlorinated compounds in the Caribbean marine environment. Copyright © 2013. Published by Elsevier Ltd.

Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in sediment collected from offshore waters of Central Vietnam.

PubMed

Tri, Tran Manh; Anh, Hoang Quoc; Tham, Trinh Thi; Van Quy, Tran; Long, Nguyen Quang; Nhung, Dao Thi; Nakamura, Masafumi; Nishida, Masayo; Maeda, Yasuaki; Van Boi, Luu; Minh, Tu Binh

2016-05-15

Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5pgg(-1), respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 0.39 to 2.9, and 1.6 to 22pgg(-1), respectively. OCDD was detected at the highest concentration, ranged from 100 to 300pgg(-1). Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Pollution characteristics and ecological risk assessment of heavy metals in surface sediments of Qingshan Reservoir in Lin' an City, Zhejiang Province of East China].

PubMed

Zhang, Fen; Yang, Chang-Ming; Pan, Rui-Jie

2013-09-01

A total of 8 representative surface sediment sampling sites were collected from the Qingshan Reservoir in Lin'an City of Zhejiang Province to investigate the differences in the total concentrations of As, Cr, Cu, Ni, Mn, Pb, and Zn among the sampling sites. The different forms of the heavy metals, i. e., acid soluble, easily reducible, easily oxidizable, and residual, were determined by BCR sequential extraction method, and the pollution degrees and potential ecological risk, of the heavy metals in the surface sediments at different sampling sites of the Reservoir were assessed by using geo-accumulation index (I(geo)) and Hakanson potential ecological risk index. There existed obvious spatial differences in the total concentrations of the heavy metals in the surface sediments of the Reservoir. The sampling sites nearby the estuaries of the tributaries flowing through downtowns and heavy industrial parks to the Reservoir had obviously higher heavy metals concentrations in surface sediments, as compared to the other sampling sites. In the sediments, Mn was mainly in acid extractable form, Cu and Pb were mainly in reducible form, and As was mainly in residual form. The surface sediments at the sampling sites nearby the estuaries of the tributaries flowing through downtowns to the Reservoir had higher proportions of acid extractable and reducibles forms of the heavy metals, which would have definite potential toxic risk to aquatic organisms. Among the 7 heavy metals in the surface sediments, As showed the highest pollution degree, followed by Cu, Ni, Mn, Pb, and Zn, which were at moderate pollution degree, while Cr was at non-pollution degree, with relatively low potential ecological risk. Through the comparison of the sampling sites, it was observed that the surface sediments at the sites nearby the estuaries of Jinxi River and Hengxi River flowing through downtowns and heavy industrial parks to the Reservoir showed obviously higher heavy metals pollution degree and potential ecological risk.

Occurrence, compositional distribution, and toxicity assessment of pyrethroid insecticides in sediments from the fluvial systems of Chaohu Lake, Eastern China.

PubMed

Wang, Ji-Zhong; Bai, Ya-Shu; Wu, Yakton; Zhang, Shuo; Chen, Tian-Hu; Peng, Shu-Chuan; Xie, Yu-Wei; Zhang, Xiao-Wei

2016-06-01

Surface sediment-associated synthetic pyrethroid insecticides (SPs) are known to pose high risks to the benthic organisms in Chaohu Lake, a shallow lake of Eastern China. However, the pollution status of the lake's tributaries and estuaries is still unknown. The present study was conducted to investigate the occurrence, compositional distribution, and toxicity of 12 currently used SPs in the surface sediments from four important tributaries, as well as in the sediment cores at their estuaries, using GC-MS for quantification. All SPs selected were detectable, with cypermethrin, es/fenvalerate, and permethrin dominant in both surface and core sediments, suggesting that these compounds were extensively applied. Urban samples contained the highest summed concentrations of the 12 SPs analyzed (Σ12SP) in both surface and core sediments compared with rural samples, suggesting that urban areas near aquatic environments posed high risks for SPs. The mean concentration of Σ12SP in surface sediments of each river was generally higher than that found in core sediments from its corresponding estuary, perhaps implying recent increases in SP usage. Surface sediments were significantly dominated by cypermethrin and permethrin, whereas core sediments were dominated by permethrin and es/fenvalerate. The compositional distributions demonstrated a spatial variation for surface sediments because urban sediments generally contained greater percentages of permethrin and cypermethrin, but rural sediments had significant levels of es/fenvalerate and cypermethrin. In all sediment cores, the percentage of permethrin gradually increased, whereas es/fenvalerate tended to decrease, from the bottom sediments to the top, indicating that the former represented fresh input, whereas the latter represented historical residue. Most urban samples would be expected to be highly toxic to benthic organisms due to the residue of SPs based on a calculation of toxic units (TUs) using toxicity data of the amphipod Hyalella azteca. However, low TU values were found for the samples from rural areas. These results indicate that the bottom sediments were exposed to high risk largely by the residual SPs from urban areas. The summed TUs were mostly attributable to cypermethrin, followed by λ-cyhalothrin and es/fenvalerate. Despite permethrin contributing ∼28.7 % of the Σ12SP concentration, it only represented 6.34 % of the summed TUs. Therefore, our results suggest that high levels of urbanization can increase the accumulation of SPs in aquatic environments.

Variability of Plant Wax Concentrations and Carbon Isotope Values in Surface Lake Sediments Provide Clues into Their Transport and Deposition

NASA Astrophysics Data System (ADS)

Bates, B.; Lowell, T. V.; Diefendorf, A. F.; Freimuth, E. J.; Stewart, A. K.

2017-12-01

Plant wax compounds preserved in lake sediments are used as proxies for paleohydrologic reconstructions. Despite their presence in lake sediments, little is known about their transport from plants to their deposition in lake sediments. By drawing on the leaf and pollen taphonomy literature combined with sediment focusing models, it is possible to develop several working hypotheses for the transport and deposition of plant waxes in lake sediments. An improved understanding of plant wax transport and deposition into lake sediments is necessary to increase the accuracy of paleohydrologic reconstructions. To better understand the controls on plant wax transport and deposition in lake sediment, we analyzed the sedimentary plant waxes from 3 lakes in the Adirondack Mountains of New York. These lakes were chosen to capture a range of basin-specific properties to evaluate their influences on the transport and deposition of plant wax compounds in surface sediments. We spatially characterized sediment properties with surface sediment samples and high-resolution underwater imaging, acoustically profiled the sub-bottom, and measured temperature profiles. From each site, we measured n-alkanes, bulk organic content (loss-on-ignition), bulk carbon and nitrogen concentrations, C:N ratios, and bulk carbon isotopes. Preliminary n-alkane concentrations and chain length distributions, as well as bulk carbon isotopes, are variable within each lake basin suggesting a mix of aquatic and terrestrial sources. The bulk carbon isotope values for two of the three lakes show a similar range of -2‰ compared to a range of -6.3‰ at the third lake. Likewise, the range of total n-alkane concentrations is much higher in the third lake suggesting that the controls on the distribution of n-alkanes and organic carbon are different between lakes. For terrestrial plant waxes, we find low n-alkane concentrations in sandy nearshore sediments relative to higher n-alkane concentrations in deeper fine-grained sediments. Combined, this information suggests that littoral processes focus organic compounds and fine sediments towards the main depo-center of the lake. These and other observations highlight important relationships between basin-specific properties and processes controlling the transport and deposition of plant wax compounds.

Effectiveness of a sediment time critical removal action-PCB reduction in fish tissue, surface water, and sediment via wet excavation.

PubMed

Santini, Andrew D; King, Todd; Krawczyk, Keith; Kern, John W

2015-01-01

Documenting successful remediation of polychlorinated biphenyl (PCB)-contaminated sediments is limited; potentially due to inadequate monitoring methods, complexities associated with the environment, and selected remedial techniques. At some sites, absence of appropriate baseline and postremoval monitoring limits proper evaluation of remedial efficacy. Accurate interpretation of interactions between media, space, time, species, lipid content, and remedial technique requires robust study design and data. This article presents baseline and postremoval data documenting reduced PCB concentrations in fish tissue, surface water, and sediment in response to the US Environmental Protection Agency (USEPA) time-critical removal action (TCRA) that was conducted at the former Bryant Mill Pond (BMP) on Portage Creek in Kalamazoo, Michigan. The BMP is part of an operable unit (OU) within the Allied Paper, Inc./Portage Creek/Kalamazoo River Superfund Site. PCBs discharged to the creek as a byproduct of carbonless copy paper recycling are the primary contaminant of concern. Paper waste residuals commonly appear as gray to light gray clays in river sediments and floodplain soils. The cleanup criterion was 10 mg/kg, with a residual PCB concentration goal of 1 mg/kg. Because the PCB-containing waste is (generally) associated with readily visible light gray clay, excavation of all visibly contaminated current or formerly impounded sediment served as a surrogate for the cleanup criteria and goal. Sediment was wet excavated and backfilled after diversion of the creek. After confirmation that PCB concentrations met cleanup criteria, the stream was diverted to the excavated side, and excavation and backfilling were completed. Overall, 146000 cubic yards of material including PCB-contaminated sediments were removed from the BMP. The long-term monitoring (LTM) program implemented by the Michigan Department of Environmental Quality (MDEQ), and historic data from a variety of sources (federal, state, and local agencies and responsible parties) provided data demonstrating TCRA effectiveness. Before TCRA, surface sediment PCB concentration in instream and formerly inundated sediment combined was 83 mg/kg (with a maximum of 700 mg/kg). Instream sediments that are more representative of fish exposures had a pre-TCRA surface weighted average concentration (SWAC) of 27 mg/kg. The post-TCRA SWAC for instream and floodplain sediments combined was 0.26 mg/kg. Average surface water concentrations at the downstream end of the BMP were reduced from 0.11 µg/L pre-TCRA to 0.0025 µg/L post-TCRA. Tissue samples for adult carp fillets decreased from 4 mg/kg pre-TCRA to 0.26 mg/kg post-TCRA; whole body white suckers from 3 mg/kg pre-TCRA to 0.1 mg/kg post-TCRA; whole body channel catfish from 39 mg/kg-L pre-TCRA to 2.6 mg/kg-L post-TCRA. Concentrations of PCBs in 2 species of resident fish (carp and white suckers), caged channel catfish, surface water, and sediment were reduced by over 1 order of magnitude within 1 year of completion, substantively accelerating natural recovery processes. A slight increase in PCB concentration was observed in both whole body suckers and adult carp fillets in the second monitoring period post-TCRA; however, these concentrations are still near an order of magnitude less than pre-TCRA concentrations and appear to be currently stable or on a slight downward trend. © 2014 SETAC.

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments of two lakes of the Dongting Lake district in Hunan, China

NASA Astrophysics Data System (ADS)

He, Jiang; Yang, Yajing; Zhang, Lugang; Luo, Yushuang; Liu, Fei; Yang, Pinhong

2018-04-01

In this paper, 18 and 12 surface sediment samples were collected from Datong Lake and Shanpo Lake, respectively, and the 16 USEPA priority Polycyclic aromatic hydrocarbons (PAHs) in these samples were detected. The result indicated that the Σ16PAHs ranged from 206.56 to 1058.98 ng.g-1 with an average concentration of 667.22 ng.g-1 in sediments from Datong Lake, whereas it ranged from 90.62 to 900.70 ng.g-1 with an average concentration of 364.97 ng.g-1 in sediments from Shanpo Lake. The concentrations of individual PAHs in sediments ranged from 5.50 to 85.23 and from 4.39 to 52.74 ng.g-1 in Datong Lake and Shanpo Lake, respectively. According to the indexes such as HMW/LMW, Ant/(Ant+Phe), Flua/(Flua+Pyr), IcdP/(IcdP+BghiP), and BaA/(BaA+Chr), the PAHs in sediments from both lakes are mainly of pyrogenic origin. The total BaP equivalent in the surface sediment samples from Datong Lake and Shanpo Lake is 42.77 and 33.35 ng.g-1, respectively.

Impact of bottom trawling on deep-sea sediment properties along the flanks of a submarine canyon.

PubMed

Martín, Jacobo; Puig, Pere; Masqué, Pere; Palanques, Albert; Sánchez-Gómez, Anabel

2014-01-01

The offshore displacement of commercial bottom trawling has raised concerns about the impact of this destructive fishing practice on the deep seafloor, which is in general characterized by lower resilience than shallow water regions. This study focuses on the flanks of La Fonera (or Palamós) submarine canyon in the Northwestern Mediterranean, where an intensive bottom trawl fishery has been active during several decades in the 400-800 m depth range. To explore the degree of alteration of surface sediments (0-50 cm depth) caused by this industrial activity, fishing grounds and control (untrawled) sites were sampled along the canyon flanks with an interface multicorer. Sediment cores were analyzed to obtain vertical profiles of sediment grain-size, dry bulk density, organic carbon content and concentration of the radionuclide 210Pb. At control sites, surface sediments presented sedimentological characteristics typical of slope depositional systems, including a topmost unit of unconsolidated and bioturbated material overlying sediments progressively compacted with depth, with consistently high 210Pb inventories and exponential decaying profiles of 210Pb concentrations. Sediment accumulation rates at these untrawled sites ranged from 0.3 to 1.0 cm y-1. Sediment properties at most trawled sites departed from control sites and the sampled cores were characterized by denser sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sediments caused by trawling gears. Other alterations of the physical sediment properties, including thorough mixing or grain-size sorting, as well as organic carbon impoverishment, were also visible at trawled sites. This work contributes to the growing realization of the capacity of bottom trawling to alter the physical properties of surface sediments and affect the seafloor integrity over large spatial scales of the deep-sea.

Impact of Bottom Trawling on Deep-Sea Sediment Properties along the Flanks of a Submarine Canyon

PubMed Central

Martín, Jacobo; Puig, Pere; Masqué, Pere; Palanques, Albert; Sánchez-Gómez, Anabel

2014-01-01

The offshore displacement of commercial bottom trawling has raised concerns about the impact of this destructive fishing practice on the deep seafloor, which is in general characterized by lower resilience than shallow water regions. This study focuses on the flanks of La Fonera (or Palamós) submarine canyon in the Northwestern Mediterranean, where an intensive bottom trawl fishery has been active during several decades in the 400–800 m depth range. To explore the degree of alteration of surface sediments (0–50 cm depth) caused by this industrial activity, fishing grounds and control (untrawled) sites were sampled along the canyon flanks with an interface multicorer. Sediment cores were analyzed to obtain vertical profiles of sediment grain-size, dry bulk density, organic carbon content and concentration of the radionuclide 210Pb. At control sites, surface sediments presented sedimentological characteristics typical of slope depositional systems, including a topmost unit of unconsolidated and bioturbated material overlying sediments progressively compacted with depth, with consistently high 210Pb inventories and exponential decaying profiles of 210Pb concentrations. Sediment accumulation rates at these untrawled sites ranged from 0.3 to 1.0 cm y−1. Sediment properties at most trawled sites departed from control sites and the sampled cores were characterized by denser sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sediments caused by trawling gears. Other alterations of the physical sediment properties, including thorough mixing or grain-size sorting, as well as organic carbon impoverishment, were also visible at trawled sites. This work contributes to the growing realization of the capacity of bottom trawling to alter the physical properties of surface sediments and affect the seafloor integrity over large spatial scales of the deep-sea. PMID:25111298

Metal Oxides in Surface Sediment Control Nickel Bioavailability to Benthic Macroinvertebrates.

PubMed

Mendonca, Raissa M; Daley, Jennifer M; Hudson, Michelle L; Schlekat, Christian E; Burton, G Allen; Costello, David M

2017-11-21

In aquatic ecosystems, the cycling and toxicity of nickel (Ni) are coupled to other elemental cycles that can limit its bioavailability. Current sediment risk assessment approaches consider acid-volatile sulfide (AVS) as the major binding phase for Ni, but have not yet incorporated ligands that are present in oxic sediments. Our study aimed to assess how metal oxides play a role in Ni bioavailability in surficial sediments exposed to effluent from two mine sites. We coupled spatially explicit sediment geochemistry (i.e., separate oxic and suboxic) to the indigenous macroinvertebrate community structure. Effluent-exposed sites contained high concentrations of sediment Ni and AVS, though roughly 80% less AVS was observed in surface sediments. Iron (Fe) oxide mineral concentrations were elevated in surface sediments and bound a substantial proportion of Ni. Redundancy analysis of the invertebrate community showed surface sediment geochemistry significantly explained shifts in community abundances. Relative abundance of the dominant mayfly (Ephemeridae) was reduced in sites with greater bioavailable Ni, but accounting for Fe oxide-bound Ni greatly decreased variation in effect thresholds between the two mine sites. Our results provide field-based evidence that solid-phase ligands in oxic sediment, most notably Fe oxides, may have a critical role in controlling nickel bioavailability.

Selenium in irrigated agricultural areas of the western United States

USGS Publications Warehouse

Nolan, B.T.; Clark, M.L.

1997-01-01

A logistic regression model was developed to predict the likelihood that Se exceeds the USEPA chronic criterion for aquatic life (5 ??g/L) in irrigated agricultural areas of the western USA. Preliminary analysis of explanatory variables used in the model indicated that surface-water Se concentration increased with increasing dissolved solids (DS) concentration and with the presence of Upper Cretaceous, mainly marine sediment. The presence or absence of Cretaceous sediment was the major variable affecting Se concentration in surface-water samples from the National Irrigation Water Quality Program. Median Se concentration was 14 ??g/L in samples from areas underlain by Cretaceous sediments and < 1 ??g/L in samples from areas underlain by non-Cretaceous sediments. Wilcoxon rank sum tests indicated that elevated Se concentrations in samples from areas with Cretaceous sediments, irrigated areas, and from closed lakes and ponds were statistically significant. Spearman correlations indicated that Se was positively correlated with a binary geology variable (0.64) and DS (0.45). Logistic regression models indicated that the concentration of Se in surface water was almost certain to exceed the Environmental Protection Agency aquatic-life chronic criterion of 5 ??g/L when DS was greater than 3000 mg/L in areas with Cretaceous sediments. The 'best' logistic regression model correctly predicted Se exceedances and nonexceedances 84.4% of the time, and model sensitivity was 80.7%. A regional map of Cretaceous sediment showed the location of potential problem areas. The map and logistic regression model are tools that can be used to determine the potential for Se contamination of irrigated agricultural areas in the western USA.

Historical trends of perfluoroalkyl substances (PFASs) in dated sediments from semi-enclosed bays of Korea.

PubMed

Shen, Aihua; Lee, Sunggyu; Ra, Kongtae; Suk, Dongwoo; Moon, Hyo-Bang

2018-03-01

Information is scarce on historical trends of perfluoroalkyl substances (PFASs) in the coastal environment. In this study, four sediment cores were collected from semi-enclosed bays of Korea to investigate the pollution history, contamination profiles, and environmental burden of PFASs. The total PFAS concentrations in sediment cores ranged from 6.61 to 821 pg/g dry weight. The highest concentrations of PFASs were found in surface or sub-surface sediments, indicating on-going contamination by PFASs. Historical trends in PFASs showed a clear increase since the 1980s, which was consistent with the global PFAS consumption pattern. Concentrations of PFASs were dependent on the organic carbon content in sediment cores. PFOS and longer-chain PFASs were predominant in all of the sediment cores. In particular, a large proportion of longer-chain PFASs was observed in the upper layers of the sediment cores from industrialized coastal regions. Inventories and fluxes estimated for PFASs were similar to those for PCDD/Fs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Distribution and assessment of sediment toxicity in Tamaki Estuary, Auckland, New Zealand

NASA Astrophysics Data System (ADS)

Abrahim, G. M. S.; Parker, R. J.; Nichol, S. L.

2007-07-01

Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants, since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction, sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements. However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal to long established sources of catchment pollution.

Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA.

PubMed

Kayzar, Theresa M; Villa, Adam C; Lobaugh, Megan L; Gaffney, Amy M; Williams, Ross W

2014-10-01

The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. The ((234)U)/((238)U) composition of Red Rock Creek is altered downstream of the Juniper Mine. As a result of mine-derived contamination, water ((234)U)/((238)U) ratios are 67% lower than in water upstream of the mine (1.114-1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activity ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041-1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (∼70-80% of uranium in leachable fraction). Contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment. Published by Elsevier Ltd.

Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA

DOE PAGES

Kayzar, Theresa M.; Villa, Adam C.; Lobaugh, Megan L.; ...

2014-06-07

The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. Furthermore, we alter the (234U)/(238U) composition of Red Rock Creek downstream of the Juniper Mine. As a result of mine-derived contamination, water (234U)/(238U) ratios are 67% lower than in water upstream of the mine (1.114–1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activitymore » ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041–1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (~70–80% of uranium in leachable fraction). Furthermore, contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.« less

Characteristics and Distribution of Phosphorus in Surface Sediments of Limnetic Ecosystem in Eastern China

PubMed Central

Zhang, Wenqiang; Jin, Xin; Zhu, Xiaolei; Shan, Baoqing

2016-01-01

Phosphorus (P) is an essential nutrient for aquatic organisms; however, excessive P inflow to limnetic ecosystems can induce eutrophication. P concentrations in the rivers, wetlands and lakes of Eastern China have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the distribution and speciation of P is lacking at the regional scale. We determined the distribution and speciation of P in limnetic ecosystems in Eastern China using Standards, Measurements and Testing (SMT) and phosphorus nuclear magnetic resonance (31P-NMR). The results indicate that P pollution in surface sediments was serious. Inorganic P (Pi) was the primary drive of variation in total P (TP) among different river systems, and Pi accounted for 71% to 90% of TP in surface sediment in Eastern China. Also, the concentrations of TP and Pi varied among watersheds and Pi primarily drove the variation in TP in different watersheds. Sediments less than 10-cm deep served as the main P reservoir. Environmental factors affect the speciation and origin of P. NaOH-Pi, HCl-Pi and organic P (Po) were related to pH accordingly at the regional scale. The physicochemical properties of sediments from different limnetic ecosystems affect the P speciation. HCl-Pi was higher in wetland sediments than in riverine and lake sediments in Eastern China. Conversely, NaOH-Pi was lowest in wetland sediments. Total Po concentration was lower in riverine sediments than in other sediments, but Mono-P was higher, with an average concentration of 48 mg kg−1. Diesters-P was highest in lake sediments. By revealing the regional distribution of TP, Pi and Po, this study will support eutrophication management in Eastern China. PMID:27281191

Increase in Nutrients, Mercury, and Methylmercury as a Consequence of Elevated Sulfate Reduction to Sulfide in Experimental Wetland Mesocosms

NASA Astrophysics Data System (ADS)

Myrbo, A.; Swain, E. B.; Johnson, N. W.; Engstrom, D. R.; Pastor, J.; Dewey, B.; Monson, P.; Brenner, J.; Dykhuizen Shore, M.; Peters, E. B.

2017-11-01

Microbial sulfate reduction (MSR) in both freshwater and marine ecosystems is a pathway for the decomposition of sedimentary organic matter (OM) after oxygen has been consumed. In experimental freshwater wetland mesocosms, sulfate additions allowed MSR to mineralize OM that would not otherwise have been decomposed. The mineralization of OM by MSR increased surface water concentrations of ecologically important constituents of OM: dissolved inorganic carbon, dissolved organic carbon, phosphorus, nitrogen, total mercury, and methylmercury. Increases in surface water concentrations, except for methylmercury, were in proportion to cumulative sulfate reduction, which was estimated by sulfate loss from the surface water into the sediments. Stoichiometric analysis shows that the increases were less than would be predicted from ratios with carbon in sediment, indicating that there are processes that limit P, N, and Hg mobilization to, or retention in, surface water. The highest sulfate treatment produced high levels of sulfide that retarded the methylation of mercury but simultaneously mobilized sedimentary inorganic mercury into surface water. As a result, the proportion of mercury in the surface water as methylmercury peaked at intermediate pore water sulfide concentrations. The mesocosms have a relatively high ratio of wall and sediment surfaces to the volume of overlying water, perhaps enhancing the removal of nutrients and mercury to periphyton. The presence of wild rice decreased sediment sulfide concentrations by 30%, which was most likely a result of oxygen release from the wild rice roots. An additional consequence of the enhanced MSR was that sulfate additions produced phytotoxic levels of sulfide in sediment pore water.

Clostridium perfringens in Long Island Sound sediments: An urban sedimentary record

USGS Publications Warehouse

Buchholtz ten Brink, Marilyn R.; Mecray, E.L.; Galvin, E.L.

2000-01-01

Clostridium perfringens is a conservative tracer and an indicator of sewage-derived pollution in the marine environment. The distribution of Clostridium perfringens spores was measured in sediments from Long Island Sound, USA, as part of a regional study designed to: (1) map the distribution of contaminated sediments; (2) determine transport and dispersal paths; (3) identify the locations of sediment and contaminant focusing; and (4) constrain predictive models. In 1996, sediment cores were collected at 58 stations, and surface sediments were collected at 219 locations throughout the Sound. Elevated concentrations of Clostridium perfringens in the sediments indicate that sewage pollution is present throughout Long Island Sound and has persisted for more than a century. Concentrations range from undetectable amounts to 15,000 spores/g dry sediment and are above background levels in the upper 30 cm at nearly all core locations. Sediment focusing strongly impacts the accumulation of Clostridium perfringens spores. Inventories in the cores range from 28 to 70,000 spores/cm2, and elevated concentrations can extend to depths of 50 cm. The steep gradients in Clostridium perfringens profiles in muddier cores contrast with concentrations that are generally constant with depth in sandier cores. Clostridium perfringens concentrations rarely decrease in the uppermost sediment, unlike those reported for metal contaminants. Concentrations in surface sediments are highest in the western end of the Sound, very low in the eastern region, and intermediate in the central part. This pattern reflects winnowing and focusing of Clostridium perfringens spores and fine-grained sediment by the hydrodynamic regime; however, the proximity of sewage sources to the westernmost Sound locally enhances the Clostridium perfringens signals.

Suspended sediments limit coral sperm availability

PubMed Central

Ricardo, Gerard F.; Jones, Ross J.; Clode, Peta L.; Humanes, Adriana; Negri, Andrew P.

2015-01-01

Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L−1), with 2–37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water’s surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water’s surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment. PMID:26659008

Suspended sediments limit coral sperm availability.

PubMed

Ricardo, Gerard F; Jones, Ross J; Clode, Peta L; Humanes, Adriana; Negri, Andrew P

2015-12-14

Suspended sediment from dredging activities and natural resuspension events represent a risk to the reproductive processes of coral, and therefore the ongoing maintenance of reefal populations. To investigate the underlying mechanisms that could reduce the fertilisation success in turbid water, we conducted several experiments exposing gametes of the corals Acropora tenuis and A. millepora to two sediment types. Sperm limitation was identified in the presence of siliciclastic sediment (230 and ~700 mg L(-1)), with 2-37 fold more sperm required to achieve maximum fertilisation rates, when compared with sediment-free treatments. This effect was more pronounced at sub-optimum sperm concentrations. Considerable (>45%) decreases in sperm concentration at the water's surface was recorded in the presence of siliciclastic sediment and a >20% decrease for carbonate sediment. Electron microscopy then confirmed sediment entangled sperm and we propose entrapment and sinking is the primary mechanism reducing sperm available to the egg. Longer exposure to suspended sediments and gamete aging further decreased fertilisation success when compared with a shorter exposure. Collectively, these findings demonstrate that high concentrations of suspended sediments effectively remove sperm from the water's surface during coral spawning events, reducing the window for fertilisation with potential subsequent flow-on effects for recruitment.

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.

Sediment Transport from Urban, Urbanizing, and Rural Areas in Johnson County, Kansas, 2006-08

USGS Publications Warehouse

Lee, Casey J.

2013-01-01

1. Studies have commonly illustrated that erosion and sediment transport from construction sites is extensive, typically 10-100X that of background levels. 2. However, to our knowledge, the affects of construction and urbanization have rarely been assessed (1) since erosion and sediment controls have been required at construction sites, and (2) at watershed (5-65 mi2) scales. This is primarily because of difficulty characterizing sediment loads in small basins. Studies (such as that illustrated from Timble, 1999) illustrated how large changes in surface erosion may not result in substantive changes in downstream sediment loads (b/c of sediment deposition on land-surfaces, floodplains, and in stream channels). 3. Improved technology (in-situ turbidity) sensors provide a good application b/c they provide an independent surrogate of sediment concentration that is more accurate at estimating sediment concentrations and loads that instantaneous streamflow.

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

Effects of the Upper Taum Sauk Reservoir Embankment Breach on the Surface-Water Quality and Sediments of the East Fork Black River and the Black River, Southeastern Missouri - 2006-07

USGS Publications Warehouse

Barr, Miya N.

2009-01-01

On December 14, 2005, a 680-foot wide section of the upper reservoir embankment of the Taum Sauk pump-storage hydroelectric powerplant located in Reynolds County, Missouri, suddenly failed. This catastrophic event sent approximately 1.5 billion gallons of water into the Johnson's Shut-Ins State Park and into the East Fork Black River, and deposited enormous quantities of rock, soil, and vegetation in the flooded areas. Water-quality data were collected within and below the impacted area to study and document the changes to the riverene system. Data collection included routine, event-based, and continuous surface-water quality monitoring as well as suspended- and streambed-sediment sampling. Surface water-quality samples were collected and analyzed for a suite of physical and chemical constituents including: turbidity; nutrients; major ions such as calcium, magnesium, and potassium; total suspended solids; total dissolved solids; trace metals such as aluminum, iron, and lead; and suspended-sediment concentrations. Suspended-sediment concentrations were used to calculate daily sediment discharge. A peculiar blue-green coloration on the water surface of the East Fork Black River and Black River was evident downstream from the lower reservoir during the first year of the study. It is possible that this phenomenon was the result of 'rock flour' occurring when the upper reservoir embankment was breached, scouring the mountainside and producing extremely fine sediment particles, or from the alum-based flocculent used to reduce turbidity in the lower reservoir. It also was determined that no long-term effects of the reservoir embankment breach are expected as the turbidity and concentrations of trace metals such as total recoverable aluminum, dissolved aluminum, dissolved iron, and suspended-sediment concentration graphically decreased over time. Larger concentrations of these constituents during the beginning of the study also could be a direct result of the alum-based flocculent used in the lower reservoir. Suspended-sediment concentrations and turbidity measurements were largest at the site downstream from the lower reservoir. This is because of the large amounts of debris deposited in the lower reservoir from the breach, which in turn were redeposited into the East Fork Black River during releases. When these constituents were plotted over time, the concentrations decreased and were similar to the other two sites in the study. Trend analyses were studied at one site with historical data. No major trends were discovered for streamflow, turbidity, suspended-sediment concentrations, or suspended-sediment discharges before or after the event. Although long-term effects of the elevated turbidity, major trace metals, and suspended sediments in the study area as a result of the reservoir embankment breach are not expected, there could possibly be other effects not measured during this study that could potentially affect the surface-water quality, such as loss of riparian habitat, changes in biological ecosystems, and large-scale reworking of sediments.

Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area, Bohai Sea, China

USGS Publications Warehouse

Ding, Xigui; Ye, Siyuan; Yuan, Hongming; Krauss, Ken W.

2018-01-01

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg (Pb), 50 mg/kg (Zn), 48.8 mg/kg (Cr), 0.1 mg/kg (Cd), 8.4 mg/kg (As), and 20.3 μg/kg (Hg). These concentrations generally met the China Marine Sediment Quality criteria. However, both pollution assessments indicated moderate to strong Cd and Hg contamination in the study area. The potential ecological risk index suggested that the combined ecological risk of the seven studied metals may be low, but that 24.5% of the sites, where sediments were more finer and higher in Corg concentration, had high ecological risk in Hg and Cd pollution.

Sediment studies in the Assabet River, central Massachusetts, 2003

USGS Publications Warehouse

Zimmerman, Marc J.; Sorenson, Jason R.

2005-01-01

From its headwaters in Westborough, Massachusetts, to its confluence with the Sudbury River, the 53-kilometer-long Assabet River passes through a series of small towns and mixed land-use areas. Along the way, wastewater-treatment plants release nutrient-rich effluents that contribute to the eutrophic state of this waterway. This condition is most obvious where the river is impounded by a series of dams that have sequestered large amounts of sediment and support rooted and floating macrophytes and epiphytic algae. The water in parts of these impoundments may also have low concentrations of dissolved oxygen, another symptom of eutrophication. All of the impoundments had relatively shallow maximum water depths, which ranged from approximately 2.4 to 3.4 meters, and all had extensive shallow areas. Sediment volumes estimated for the six impoundments ranged from approximately 380 cubic meters in the Aluminum City impoundment to 580,000 cubic meters in the Ben Smith impoundment. The other impoundments had sediment volumes of 120,000 cubic meters (Powdermill), 67,000 cubic meters (Gleasondale), 55,000 cubic meters (Hudson), and 42,000 cubic meters (Allen Street). The principal objective of this study was the determination of sediment volume, extent, and chemistry, in particular, the characterization of toxic inorganic and organic chemicals in the sediments. To determine the bulk-sediment chemical-constituent concentrations, more than one hundred sediment cores were collected in pairs from the six impoundments. One core from each pair was sampled for inorganic constituents and the other for organic constituents. Most of the cores analyzed for inorganics were sectioned to provide information on the vertical distribution of analytes; a subset of the cores analyzed for organics was also sectioned. Approximately 200 samples were analyzed for inorganic constituents and 100 for organics; more than 10 percent were quality-control replicate or blank samples. Maximum bulk-sediment phosphorus concentrations in surface samples from the impoundments increased along a downstream gradient, with the exception of samples from the last impoundment, where the concentrations decreased. In addition, the highest phosphorus concentrations were generally in the surface samples; this finding may prove helpful if surface dredging is selected as a means to control phosphorus release from sediments. There is no known relation, however, between bulk-sediment concentration of phosphorus and the concentrations of phosphorus available to biota. Potentially toxic metals, including arsenic, cadmium, chromium, copper, nickel, lead, and zinc were frequently measured at concentrations that exceeded U.S. Environmental Protection Agency sediment-quality guidelines for the protection of aquatic life and that occasionally exceeded Massachusetts Department of Environmental Protection guidelines governing landfill disposal (reuse). Due to the effects of matrix interference and sample dilution on laboratory analyses, neither pesticides nor volatile organic compounds were detected at any sites. However, samples collected in other studies from nearby streams indicated the possibility that pesticides might have been detected in the impoundments if not for these analytical problems. Although polychlorinated biphenyl concentrations, as individual Aroclors, generally exceeded published U.S. Environmental Protection Agency guideline concentrations for potential effects on aquatic life, the U.S. Environmental Protection Agency guideline concentrations for human contact or the Massachusetts guidelines for landfill reuse were rarely exceeded. Concentrations of polycyclic aromatic hydrocarbons, both individually and total, frequently were greater than guideline concentrations. Concentrations of total extractable petroleum hydrocarbons did not exceed Massachusetts guideline concentrations in any samples. When the sediment analytes from surface samples are considered togethe

Sediment transport and Hg recovery in Lavaca Bay, as evaluated from radionuclide and Hg distributions

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

Santschi, P.H.; Allison, M.A.; Asbill, S.

1999-02-01

Mercury was released in the late 1960s from a chloralkali facility managed by ALCOA and deposited into sediments of Lavaca Bay, TX. Sediments have recorded this event as a well-defined subsurface concentration maximum. Radionuclide, mercury, X-radiography, and grain size data from sediment cores taken in 1997 at 15 stations in Lavaca bay were used to assess sediment and Hg movements in the bay. Sediment accumulation rates were calculated from bomb fallout nuclide ({sup 137}Cs, {sup 239,240}Pu) peaks in 1963 and from the steady-state delivery of {sup 210}Pb from the atmosphere. Sedimentation rates are highest at near-shore sites near the ALCOAmore » facility and generally decrease away from shore. Sedimentation rates in some areas are likely influenced by anthropogenic activities such as dredging. Particle reworking, as assessed from {sup 7}Be measurements, is generally restricted to the upper 2--7 cm of sediments. Numerical simulations of Hg profiles using measured sedimentation and mixing parameters indicate that at most sites high remnant mercury concentrations at 15--60 cm depth cannot supply substantial amounts of Hg to surface sediments. Assuming no future Hg supplies, Hg concentrations in surface sediments are predicted to decrease exponentially with a recovery half-time of 4 {+-} 2 years.« less

Phthalate esters in water and surface sediments of the Pearl River Estuary: distribution, ecological, and human health risks.

PubMed

Li, Xiaohui; Yin, Pinghe; Zhao, Ling

2016-10-01

The Pearl River Estuary (PRE) is vulnerable due to the increasingly serious environmental pollution, such as phthalate esters (PAEs) contaminants, from the Pearl River Delta (PRD). The concentrations of six US Environmental Protection Agency (USEPA) priority PAEs in water and surface sediments collected from the PRD's six main estuaries in spring, summer, and winter 2013 were measured by GC-MS. Total PAEs (∑6PAEs) concentrations were from 0.5 to 28.1 μg/L and from 0.88 to 13.6 μg/g (dry weight (DW)) in water and surface sediments, respectively. The highest concentration was detected in summer. Higher concentrations of PAEs were found in Yamen (YM) and Humen (HM) areas than the other areas. Bis(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP) were the dominant PAEs in the investigated areas, contributing between 61 and 95 % of the PAEs in water and from 85 to 98 % in surface sediments. Based on risk quotients (RQs), DEHP posed greater ecological risks to the studied aquatic environments than other measured compounds. Little human health risk from the target PAEs was identified.

Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

PubMed Central

2014-01-01

Background Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels. PMID:24641695

Tofu wastewater treatment by sediment microbial fuel cells

NASA Astrophysics Data System (ADS)

Rinaldi, W.; Abubakar; Rahmi, R. F.; Silmina

2018-03-01

This research aimed to measure power density generated by sediment microbial fuel cells (SMFCs) by varying anode position and wastewater concentration. Anode position was varied at 2 cm and 4 cm under the surface of sediment, while wastewater concentration varied into 25%, 50%, 75% and 100%. The electrodes employed was stainless steel mesh, while the organic subtrate source was taken from wastewater of soybean washing and boiling process. The sediment was taken from the Lamnyong River around the outlet of tofu industry wastewater. SMFCs was run until the power density was relatively small. The produced electricity represented in power density. The results of this research showed that power density was decreased over time. Generated power density by varying 2 cm and 4 cm position of anode under the sediment surface was not significantly different, while the lowest wastewater concentration, 25%, gave the highest power density.

Polycyclic aromatic hydrocarbons in sediments from the Old Yellow River Estuary, China: occurrence, sources, characterization and correlation with the relocation history of the Yellow River.

PubMed

Yuan, Zijiao; Liu, Guijian; Wang, Ruwei; Da, Chunnian

2014-11-01

The levels of 16 USEPA priority PAHs were determined in surface sediments and one dated sediment core from the abandoned Old Yellow River Estuary, China. Total PAH concentrations in the surface sediments ranged from 100.4 to 197.3 ng g(-1) dry weight and the total toxic equivalent quantity (TEQ(carc)) values of the carcinogenic PAHs were very low. An evaluation of PAH sources based on diagnostic ratios and principal component analysis suggested that PAHs in the surface sediments mainly derived from combustion sources. The total PAH concentrations altered significantly with year of deposition and showed quite different patterns of change compared with other studies: it is hypothesized that the principal cause of these changes is the relocation of the course of the Yellow River to the sea in 1976 and 1996. Copyright © 2014 Elsevier Inc. All rights reserved.

Occurrence, spatiotemporal distribution, and ecological risks of steroids in a large shallow Chinese lake, Lake Taihu.

PubMed

Zhou, Li-Jun; Zhang, Bei-Bei; Zhao, Yong-Gang; Wu, Qinglong L

2016-07-01

Steroids have been frequently detected in surface waters, and might pose adverse effects on aquatic organisms. However, little information is available regarding the occurrence and spatiotemporal distribution of steroids in lake environments. In addition to pollution sources, the occurrence and spatiotemporal distribution of steroids in lake environments might be related to lake types (shallow or deep), lake hydrodynamics, and sorption-desorption processes in the water-sediment systems. In this study, the occurrence, spatiotemporal distribution, and ecological risks of 36 steroids in a large shallow lake were evaluated by investigating surface water and sediment samples at 32 sites in Lake Taihu over two seasons. Twelve and 15 analytes were detected in aqueous and sedimentary phases, respectively, with total concentrations ranging from 0.86 to 116ng/L (water) and from 0.82 to 16.2ng/g (sediment, dry weight). Temporal variations of steroid concentrations in the water and sediments were statistically significant, with higher concentrations in winter. High concentrations of steroids were found in the seriously polluted bays rather than in the pelagic zone of the lake. Strong lake currents might mix pelagic waters, resulting in similar concentrations of steroids in the pelagic zone. Mass balance analysis showed that sediments in shallow lakes are in general an important sink for steroids. Steroids in the surface water and sediments of Lake Taihu might pose potential risks to aquatic organisms. Overall, our study indicated that the concentrations and spatiotemporal distribution of steroids in the large shallow lake are influenced simultaneously by pollution sources and lake hydrodynamics. Steroids in the large shallow Lake Taihu showed clear temporal and spatial variations and lake sediments may be a potential sink of steroids. Copyright © 2016 Elsevier B.V. All rights reserved.

Distribution, behavior, and transport of inorganic and methylmercury in a high gradient stream

USGS Publications Warehouse

Flanders, J.R.; Turner, R.R.; Morrison, T.; Jensen, R.; Pizzuto, J.; Skalak, K.; Stahl, R.

2010-01-01

Concentrations of Hg remain elevated in physical and biological media of the South River (Virginia, USA), despite the cessation of the industrial use of Hg in its watershed nearly six decades ago, and physical characteristics that would not seem to favor Hg(II)-methylation. A 3-a study of inorganic Hg (IHg) and methylmercury (MeHg) was conducted in physical media (soil, sediment, surface water, porewater and soil/sediment extracts) to identify non-point sources, transport mechanisms, and potential controls on Hg(II)-methylation. Data collected from surface water and sediment indicate that the majority of the non-point sources of IHg to the South River are within the first 14. km downstream from the historic point source. Partitioning data indicate that particle bound IHg is introduced in this reach, releasing dissolved and colloidal bound IHg, which is transported downstream. Extraction experiments revealed that floodplain soils released a higher fraction of their IHg content in aqueous extractions than fine-grained sediment (FGS). Based on ultrafiltration [<5000 nominal molecular weight cutoff (NMWC)] the majority of soil IHg released was colloidal in nature, providing evidence for the continued evolution of IHg for Hg(II)-methylation from soil. Strong seasonal patterns in MeHg concentrations were observed in surface water and sediment. The highest concentrations of MeHg in surface water were observed at moderate temperatures, suggesting that other factors limit net Hg(II)-methylation. Seasonal changes in sediment organic content and the fraction of 1. N KOH-extractable THg were also observed and may be important factors in controlling net Hg(II)-methylation rates. Sulfate concentrations in surface water are low and the evidence suggests that Fe reduction may be an important Hg(II)-methylation process. The highest sediment MeHg concentrations were observed in habitats with large amounts of FGS, which are more prevalent in the upper half of the study area due to the lower hydrologic gradient and agricultural impacts. Past and present land use practices and other geomorphologic controls contribute to the erosion of banks and accumulation of fine-grained sediment in this section of the river, acting as sources of IHg. ?? 2010 Elsevier Ltd.

Presence of Nitrate-Accumulating Sulfur Bacteria and Their Influence on Nitrogen Cycling in a Shallow Coastal Marine Sediment

PubMed Central

Sayama, Mikio

2001-01-01

Nitrate flux between sediment and water, nitrate concentration profile at the sediment-water interface, and in situ sediment denitrification activity were measured seasonally at the innermost part of Tokyo Bay, Japan. For the determination of sediment nitrate concentration, undisturbed sediment cores were sectioned into 5-mm depth intervals and each segment was stored frozen at −30°C. The nitrate concentration was determined for the supernatants after centrifuging the frozen and thawed sediments. Nitrate in the uppermost sediment showed a remarkable seasonal change, and its seasonal maximum of up to 400 μM was found in October. The directions of the diffusive nitrate fluxes predicted from the interfacial concentration gradients were out of the sediment throughout the year. In contrast, the directions of the total nitrate fluxes measured by the whole-core incubation were into the sediment at all seasons. This contradiction between directions indicates that a large part of the nitrate pool extracted from the frozen surface sediments is not a pore water constituent, and preliminary examinations demonstrated that the nitrate was contained in the intracellular vacuoles of filamentous sulfur bacteria dwelling on or in the surface sediment. Based on the comparison between in situ sediment denitrification activity and total nitrate flux, it is suggested that intracellular nitrate cannot be directly utilized by sediment denitrification, and the probable fate of the intracellular nitrate is hypothesized to be dissimilatory reduction to ammonium. The presence of nitrate-accumulating sulfur bacteria therefore may lower nature's self-purification capacity (denitrification) and exacerbate eutrophication in shallow coastal marine environments. PMID:11472923

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

NASA Astrophysics Data System (ADS)

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

2001-12-01

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

Distribution and accumulation of mercury and copper in mangrove sediments in Shenzhen, the world's most rapid urbanized city.

PubMed

Li, Ruili; Xu, Hualin; Chai, Minwei; Qiu, Guo Yu

2016-02-01

To investigate the influence of mangrove forest on heavy metal accumulation and storage in intertidal sediments, core sediments from natural mangrove, restored mangrove, and adjacent mud flat spanning the intertidal zone along the south coastline of the most heavily urbanized Deep bay, Guangdong province, China were analyzed. The average concentrations of mercury (Hg) in surface sediments of natural mangrove and restored mangrove were 172 and 151 ng g(-1), whereas those of copper (Cu) were 75 and 50 μg g(-1), respectively. Compared to those from other typical mangrove wetlands of the world, the metal levels in Shenzhen were at median to high levels, which is consistent with the fact that Shenzhen is in high exploitation and its mangrove suffer intensive impact from human activities. Hg and Cu concentration profiles indicated a higher metal accumulation in surface layers of sediments, in agreement with enrichment of organic matter contents. Maximum concentration, enrichment factors, and excess (background-deducted) concentration inventories of metals (Hg and Cu) were substantially different between environments, decreasing from natural mangrove sediments to restored mangrove sediments to mud flat. Furthermore, metal inputs to Futian mangrove decreased in the order natural mangrove > restored mangrove > mud flat, indicating that mangrove facilitated the accumulation and storage of Hg and Cu in sediment layers.

The geochemistry of coprostanol in waters and surface sediments from Narragansett Bay

NASA Astrophysics Data System (ADS)

LeBlanc, Lawrence A.; Latimer, James S.; Ellis, John T.; Quinn, James G.

1992-05-01

A geochemical study of coprostanol (5β-Cholestan-3β-ol) was undertaken, to examine the transport and fate of a compound of moderate polarity and reactivity in the marine environment, and also because of the interest in coprostanol for use as a sewage tracer. During 1985-86, 20 sites in Narragansett Bay, including the major point sources and rivers discharging into the bay estuary, were sampled at four different times. In addition, surface sediments from 26 stations in the bay were collected. The large number and diversity of samples allowed for an assessment of major inputs of sewage into the bay as well as the recent fate of sewage-derived particles in surface sediments. Results from the study revealed that 50% of the total particulate coprostanol entering the bay was discharged into the Providence River, primarily due to inputs from the wastewater treatment facility (WWTF) at Fields Point, as well as input from the Pawtuxet and Blackstone Rivers. In the lower bay, the Newport WWTF was the largest single source of coprostanol (37% of the total particulate coprostanol) to the bay. Effluent concentrations of coprostanol from secondary WWTFs were consistently lower than those of primary treatment facilities, demonstrating the usefulness of corporstanol as an indicator of treatment plant efficiency. The distribution of coprostanol in waters and surface sediments showed a gradient of decreasing concentration downbay. When coprostanol concentrations in surface sediments were normalized to organic carbon (OC) concentrations, elevated levels were seen only in the Providence River, with a more or less even distribution throughout the rest of the bay. Results also suggest that coprostanol degrades more rapidly in the water column compared to the petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), however, it is relatively stable once it is buried in the sediments. Coprostanol concentrations in waters (0·02-0·22 μg 1 -1) and surface sediments (0·22-33 μg g -1) were as high or higher than values reported in the literature, indicating that the estuary is impacted by sewage.

The history of hexachlorobenzene accumulation in Svalbard fjords.

PubMed

Pouch, A; Zaborska, A; Pazdro, K

2018-05-24

In the present study, we investigated the spatial and historical trends of hexachlorobenzene (HCB) contamination in dated sediments of three Svalbard fjords (Kongsfjorden, Hornsund, Adventfjorden) differing in environmental conditions and human impact. HCB concentrations ranging from below limit of quantification (6.86 pg/g d.w.) to 143.99 pg/g d.w. were measured. The highest concentrations were measured in two surface sediment layers of the core collected in Hornsund near the melting glacier. The lowest concentrations of HCB were measured in Adventfjorden, suggesting that local source of HCB is not significant and global transport processes are the major transport pathways. The history of HCB deposition did not fully reflect the history of HCB emission (largest in 1950s and 1960s). In case of several sediment cores, the HCB enrichment in surface (recent) sediments was noticed. This can indicate importance of secondary sources of HCB, e.g., the influx of HCB accumulated over decades on the surface of glaciers. Detected levels of HCB were generally low and did not exceed background concentration levels; thus, a negative effect on benthic organisms is not expected.

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

Kayzar, Theresa M.; Villa, Adam C.; Lobaugh, Megan L.

The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. Furthermore, we alter the (234U)/(238U) composition of Red Rock Creek downstream of the Juniper Mine. As a result of mine-derived contamination, water (234U)/(238U) ratios are 67% lower than in water upstream of the mine (1.114–1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activitymore » ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041–1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (~70–80% of uranium in leachable fraction). Furthermore, contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.« less

Trace element concentrations in surface estuarine and marine sediments along the Mississippi Gulf Coast following Hurricane Katrina.

PubMed

Warren, Crystal; Duzgoren-Aydin, Nurdan S; Weston, James; Willett, Kristine L

2012-01-01

Hurricanes are relatively frequent ecological disturbances that may cause potentially long-term impacts to the coastal environment. Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, and caused a storm surge with the potential to change the trace element content of coastal surface sediments. In this study, surface estuarine and marine sediments were collected monthly following the storm from ten sites along the Mississippi Gulf Coast (Mobile Bay, Grand Bay Bayous Heron and Cumbest, Pascagoula, Ocean Springs, Biloxi Gulf, Back Biloxi Bay, Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina). Concentrations of V, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb were measured by inductively coupled plasma-mass spectrometry to evaluate their temporal and spatial variations in the year following Hurricane Katrina. Sediments were characterized by pH, particle size distribution and total carbon and nitrogen content. Trace element contents of the sediments were determined in both <2 mm and <63 μm grain size fractions. Results revealed no significant temporal and spatial variability in trace element concentrations, in either size fraction. Potential ecological risk of the sediments was assessed by using NOAA SQuiRTs' guideline values; most concentrations remained below probable adverse effects guidelines to marine organisms suggesting that trace elements redistributed by Hurricane Katrina would not cause an adverse impact on resident organisms. Instead, the concentrations of trace elements were site-dependent, with specific contaminants relating to the use of the area prior to Hurricane Katrina.

Surface Sediment Geochemistry in and around the Hudson Shelf Valley Offshore of New York

NASA Astrophysics Data System (ADS)

Mecray, E. L.; ten Brink, M. B.; Butman, B.; Denny, J.; Murray, R. W.

2001-05-01

The Hudson Shelf Valley, an ancient submerged portion of the Hudson River, extends across the continental shelf offshore of New York and New Jersey. Between 1959 and 1987, the area near the head of the valley was used for disposal of approximately 1.20 x 108 m3 of dredged material and sewage sludge. The distribution of metal concentrations and sediment characteristics were used to investigate the transport and fate of the sediments and their associated contaminants. Surface (0-2cm) sediments collected at 440 stations throughout the New York Bight between 1993 and 1998 were used to establish the regional distribution of pollutant metals, grain size, organic carbon, and Clostridium perfringens spores. Sediments in the New York Bight are generally sandy, however fine-grained sediments are found in the axis of the Valley. Statistical methods identified common sources and chemical mobility within groups of anthropogenic and naturally-occurring elements. High metal concentrations, fine-grained sediments, and higher organic carbon concentrations co-occur in depo-centers within the Valley. Normalization of the metal concentrations to these factors shows higher metal concentrations on the fine-grained particles in sandy areas of the Bight, particularly along the southern shore of Long Island. These distributions have implications for evaluating the impact of the mass distribution for contaminated metals in different habitats and areas. Decreasing concentrations of pollutants with time are observed, reflecting reduced contaminant loading in the upper region of the Valley; however, concentrations are still above natural background levels.

Heavy metals pollution and pb isotopic signatures in surface sediments collected from Bohai Bay, North China.

PubMed

Gao, Bo; Lu, Jin; Hao, Hong; Yin, Shuhua; Yu, Xiao; Wang, Qiwen; Sun, Ke

2014-01-01

To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 28.70, 36.56, 25.63, and 72.83 mg/kg, respectively. The mean concentrations of the studied metals were slightly higher than the background values. However, the heavy metals concentrations in surface sediments in Bohai Bay were below the other important bays or estuaries in China. The assessment by Geoaccumulation Index indicated that Cr, Zn, and Cd were classified as "the unpolluted" level, while Ni, Cu, and Pb were ranked as "unpolluted to moderately polluted" level. The order of pollution level of heavy metals was: Pb > Ni > Cu > Cr > Zn > Cd. The Pb isotopic ratios in surface sediments varied from 1.159 to 1.185 for (206)Pb/(207)Pb and from 2.456 to 2.482 for (208)Pb/(207)Pb. Compared with Pb isotopic radios in other sources, Pb contaminations in the surface sediments of Bohai Bay may be controlled by the mix process of coal combustion, aerosol particles deposition, and natural sources.

Spatial variability of metals in the inter-tidal sediments of the Medway Estuary, Kent, UK.

PubMed

Spencer, Kate L

2002-09-01

Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system.

Transport mechanisms of Silver Nanoparticles by runoff - A Flume Experiment

NASA Astrophysics Data System (ADS)

Mahdi Mahdi, Karrar NM; Commelin, Meindert; Peters, Ruud J. B.; Baartman, Jantiene E. M.; Ritsema, Coen; Geissen, Violette

2017-04-01

Silver Nanoparticles (AgNPs) are being used in many products as it has unique antimicrobial-biocidal properties. Through leaching, these particles will reach the soil environment which may affect soil organisms and disrupt plants. This work aims to study the potential transport of AgNPs with water and sediment over the soil surface due to soil erosion by water. This was done in a laboratory setting, using a rainfall simulator and flume. Low AgNPs concentration (50 μg.kg-1) was applied to two soil-flumes with slopes of 20% and 10%. The rainfall was applied in four events of 15 min each with the total amount of rainfall was 15mm in each event. After applying the rainfall, different samples were collected; soil clusters, background (BS) and surface sediments (Sf), from the flume surface, and, Runoff sediments (RS) and water (RW) was collected from the outlet. The results showed that AgNPs were detected in all samples collected, however, AgNPs concentration varied according samples type (soil or water), time of collection (for runoff water and sediment) and the slope of the soil flume. Further, the higher AgNPs concentrations were detected in the background soil (BS); as the BS samples have more finer parts (silt and clay). The AgNPs concentration in the runoff sediments increased with subsequent applied rain events. In addition to that, increasing the slope of the flume from 10% to 20% increased the total AgNPs transported with the runoff sediments by a factor 1.5. The study confirms that AgNPs can be transported over the soil surface by both runoff water and sediments due to erosion.

Accumulation and persistence of chlorobiphenyls, organochlorine pesticides and faecal sterols at the Garroch Head sewage sludge disposal site, Firth of Clyde.

PubMed

Kelly, A G

1995-01-01

The sediment concentrations of organic carbon, faecal sterols, individual chlorobiphenyl congeners and organochlorine pesticides have been measured in seabed cores from the sewage sludge disposal area at Garroch Head in the Firth of Clyde. The measurements confirm the accumulative nature of the site with high levels of sedimentary faecal sterols (152 mg kg(-1) coprostanol). Levels of chlorobiphenyls, DDT compounds and dieldrin in surface sediment were elevated by factors of 12, 40 and 120, respectively, over those observed at a site remote from the effects of dumping. Total chlorobiphenyl levels of 515 microg kg(-1) Arochlor 1254 in surface sediment were comparable to levels found in other areas heavily contaminated with sewage sludge. The 20-cm depth of heavily sludge-contaminated sediment overlays a mixed sludge/basal sediment layer some 10 cm in depth. Levels of organochlorine contaminants were elevated to depths of 90 cm in the sediment, suggesting that the surface layer is a source of contaminants to the deeper sediment. Within the upper 15-20 cm sediment in the disposal area, chlorobiphenyls are conservative, the variation in their concentration with respect to depth being related to historical input. Lindane and possibly dieldrin, and hexachlorobenzene are not conservative. Faecal sterols are removed in sub-surface sediment, in contrast to conservative behaviour previously found at other sewage polluted sites.

Chemical and physical properties affecting strontium distribution coefficients of surficial-sediment samples at the Idaho National Engineering and Environmental Laboratory, Idaho

USGS Publications Warehouse

Liszewski, M.J.; Rosentreter, J.J.; Miller, Karl E.; Bartholomay, R.C.

2000-01-01

The U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy, conducted a study to determine strontium distribution coefficients (K(d)s) of surficial sediments at the Idaho National Engineering and Environmental Laboratory (INEEL). Batch experiments using synthesized aqueous solutions were used to determine K(d)s, which describe the distribution of a solute between the solution and solid phase, of 20 surficial-sediment samples from the INEEL. The K(d)s for the 20 surficial-sediment samples ranged from 36 to 275 ml/g. Many properties of both the synthesized aqueous solutions and sediments used in the experiments also were determined. Solution properties determined were initial and equilibrium concentrations of calcium, magnesium, and strontium, pH and specific conductance, and initial concentrations of potassium and sodium. Sediment properties determined were grain-size distribution, bulk mineralogy, whole-rock major-oxide and strontium and barium concentrations, and Brunauer-Emmett-Teller (BET) surface area. Solution and sediment properties were correlated with strontium K(d)s of the 20 surficial sediments using Pearson correlation coefficients. Solution properties with the strongest correlations with strontium K(d)s were equilibrium pH and equilibrium calcium concentration correlation coefficients, 0.6598 and -0.6518, respectively. Sediment properties with the strongest correlations with strontium K(d)s were manganese oxide (MnO), BET surface area, and the >4.75-mm-grain-size fraction correlation coefficients, 0.7054, 0.7022, and -0.6660, respectively. Effects of solution properties on strontium K(d)s were interpreted as being due to competition among similarly charged and sized cations in solution for strontium-sorption sites; effects of sediment properties on strontium K(d)s were interpreted as being surface-area related. Multivariate analyses of these solution and sediment properties resulted in r2 values of 0.8071 when all five properties were used and 0.8043 when three properties, equilibrium pH, MnO, and BET surface area, were used.

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

Lockhart, L.; Ramial, K.; Wilkinson, P.

Mercury concentrations were measured in sediment cores from lakes in central and northern Canada. Typically cores spanned periods of one hundred to several hundred years, as judged by profiles of unsupported lead-210 and cesium-137. Mercury in the uppermost slices of sediment from lakes in more easterly locations was consistently elevated above that in deeper slices from the same lakes. The authors have interpreted this surface enrichment as evidence of increased recent loadings in agreement with similar studies in Ontario, Quebec, USA and Scandinavia. Western sites showed less surface enrichment with mercury, sometimes almost none, in agreement with experience in Alaska.more » Surface grab samples and two deep cores from Lake Winnipeg indicated that mercury in surface sediments exceeded that at depths corresponding to several thousand years in the history of the lake. The current indication from the cores is a regional difference in loadings of mercury with higher enrichments over basal values in the East than in the West. Recent literature, however, has raised the possibility of vertical mobility of mercury in sediments. This has suggested that processes controlling the well-known concentration of iron and manganese in oxidized surface sediments may also concentrate mercury. A number of the cores were analyzed for iron and manganese but mercury (or lead or cadmium) failed to correlate with iron or manganese. Efforts are underway to develop ways to distinguish rigorously between natural mercury and contamination.« less

Methane in Sediments From Three Tropical, Coastal Lagoons on the Yucatan Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Young, B.; Paytan, A.; Miller, L.; Herrera-Silveira, J.

2002-12-01

Tropical wetlands are significant sources of methane (CH4) to the atmosphere, and the majority of research on methane flux and cycling in the tropics has been conducted in fresh-water wetlands and lakes. However, several previous studies have shown that tropical coastal ecosystems can produce significant methane flux to the atmosphere despite the presence of moderate to marine salinities. Information regarding methane cycling within the sediments is crucial to understanding how natural and anthropogenic changes may influence these systems. We measured methane concentrations in sediments from two tropical coastal lagoons during different seasons, as well as in a third, heavily polluted, lagoon (Terminos) during the rainy season. These three lagoons, Celestun, Chelem, and Terminos, have similar vegetation, seasonal temperature and rainfall patterns, and substrate geology, but very different levels of ground water discharge and pollution. Methane concentrations in Celestun and Terminos lagoon showed high spatial variability(> 0.001 to 5 mmol kg-1 wet sediment), while sediments in Chelem Lagoon, which has near marine salinities and little sewage discharge, showed much lower variability of methane concentrations. Methane concentrations in Celestun sediments displayed two predominant patterns: some profiles contained a peak in methane concentration (1 to 2 mmole methane kg-1 wet sediment) between 5 and 15 cm below the surface while the other sediment profiles instead displayed a steady or monotonic increase in methane concentration with depth to approximately 0.025-0.080 mmol kg-1 at 10-15cm below surface followed by stable methane concentrations to the bottom of the cores (20-45 cm below the surface). A subsurface peak in methane concentrations was also found in some locations in Chelem, however, the concentrations were much lower than those measured in Celestun. Previous studies have shown that sewage pollution may drastically increase methane production in tropical coastal ecosystems. Laboratory experiments using sediment from the upper 20 cm in Celestun lagoon resulted in high rates of biogenic production of methane from the addition of trimethylamine, hydrogen, and, while additions of formate and acetate stimulated methane production to a lesser extent. This indicates that methane production in these sediments may be highly responsive to natural or anthropogenic changes in substrate availability. By synthesizing laboratory data and extensive field measurements from the lagoons, we hope to shed light on the factors controlling methane cycling in these sediments, and to better estimate methane flux to the atmosphere from these ecosystems.

[Pollution characteristics and sources of polycyclic aromatic hydrocarbons in urban rivers of Wenzhou city].

PubMed

Zhou, Jie-Cheng; Chen, Zhen-Lou; Bi, Chun-Juan; Lü, Jin-Gang; Xu, Shi-Yuan; Pan, Qi

2012-12-01

Concentrations of 18 polycyclic aromatic hydrocarbons (PAHs) in water and surface sediments collected from the urban rivers of Wenzhou city in spring and summer were measured by GC-MS. The results showed that the total PAHs concentrations in water and sediments of the studied rivers varied in ranges of 146.74-3 047.89 ng x L(-1) and 21.01-11 990.48 ng x g(-1), respectively. Higher concentrations occurred in spring. The low and middle rings of 2-4-ring were dominant in both water and sediments, but the concentrations of 5-ring and 6-ring PAHs in sediments were relatively higher than those in water. The EBaP values of PAHs in water of the studied rivers in spring and summer were 1.69-51.95 ng x L(-1) and 0-3.03 ng x L(-1), respectively. Eighty percent of water samples in spring surpassed the limits of BaP in surface water of China. The concentrations of sigma PAHs in the sediments both in spring and summer were lower than the ERM value, but part of the components of PAHs had values higher than the ERM, suggesting possible toxic effect on living organisms. Based on the PAHs molecule ratios and principal component analysis, a mixed PAHs source of petroleum and combustion in water and sediments was diagnosed, while sediments showed a greater proportion of combustion sources.

Sediment studies at Bikini Atoll part 3. Inventories of some long-lived gamma-emitting radionuclides associated with lagoon surface sediments

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

Noshkin, V.E.

1997-12-01

Surface sediment samples were collected during 1979 from 87 locations in the lagoon at Bikini Atoll. The collections were made to better define the concentrations and distribution of long-lived radionuclides associated with the bottom material and to show what modifications occurred to the composition of the surface sediment from the nuclear testing program conducted by the United States at the Atoll between 1946 and 1958. This is the last of three reports on Bikini sediment studies. In this report, we discuss the concentrations and inventories of the residual long-lived gamma-emitting radionuclides in sediments from the lagoon. The gamma-emitting radionuclides detectedmore » most frequently in sediments collected in 1979, in addition to Americium-241 ({sup 241}Am) (discussed in the second report of this series), included Cesium-137 ({sup 137}Cs), Bismuth-207 ({sup 207}Bi), Europium-155 ({sup 155}Eu), and Cobalt-60 ({sup 60}Co). Other man-made, gamma-emitting radionuclides such as Europium-152,154 ({sup 152,154}Eu), Antimony-125 ({sup 125}Sb), and Rhodium-101,102m ({sup 101,102m}Rh) were occasionally measured above detection limits in sediments near test site locations. The mean inventories for {sup 137}Cs, {sup 207}Ei, {sup 155}Eu, and {sup 60}Co in the surface 4 cm of the lagoon sediment to be 1.7, 0.56, 7.76, and 0.74 TBq, respectively. By June 1997, radioactive decay would reduce these values to 1.1, 0.38, 0.62, and 0.07 TBq, respectively. Some additional loss results from a combination of different processes that continuously mobilize and return some amount of the radionuclides to the water column. The water and dissolved constituents are removed from the lagoon through channels and exchange with the surface waters of the north equatorial Pacific Ocean. Highest levels of these radionuclides are found in surface deposits lagoonward of the Bravo Crater. Lowest concentrations and inventories are associated with sediment lagoonward of the eastern reef. The quantities in the 0-4 cm surface layer are estimated to be less than 35% of the total inventory to depth in the sediment column.« less

Deposition and accumulation of airborne organic contaminants in Yosemite National Park, Calfornia

USGS Publications Warehouse

Mast, Alisa M.; Alvarez, David A.; Zaugg, Steven D.

2012-01-01

Deposition and accumulation of airborne organic contaminants in Yosemite National Park were examined by sampling atmospheric deposition, lichen, zooplankton, and lake sediment at different elevations. Passive samplers were deployed in high-elevation lakes to estimate surface-water concentrations. Detected compounds included current-use pesticides chlorpyrifos, dacthal, and endosulfans and legacy compounds chlordane, dichlorodiphenyltrichloroethane-related compounds, dieldrin, hexachlorobenzene, and polychlorinated biphenyls. Concentrations in snow were similar among sites and showed little variation with elevation. Endosulfan concentrations in summer rain appeared to coincide with application rates in the San Joaquin Valley. More than 70% of annual pesticide inputs from atmospheric deposition occurred during the winter, largely because most precipitation falls as snow. Endosulfan and chlordane concentrations in lichen increased with elevation, indicating that mountain cold-trapping might be an important control on accumulation of these compounds. By contrast, chlorpyrifos concentrations were inversely correlated with elevation, indicating that distance from source areas was the dominant control. Sediment concentrations were inversely correlated with elevation, possibly because of the organic carbon content of sediments but also perhaps the greater mobility of organic contaminants at lower elevations. Surface-water concentrations inferred from passive samplers were at sub-parts-per-trillion concentrations, indicating minimal exposure to aquatic organisms from the water column. Concentrations in sediment generally were low, except for dichlorodiphenyldichloroethane in Tenaya Lake, which exceeded sediment guidelines for protection of benthic organisms.

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

USGS Publications Warehouse

Kratzer, Charles R.; Shelton, Jennifer L.

1998-01-01

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

Spatial distribution and ecological risk assessment of heavy metals in coastal surface sediments in the Hebei Province offshore area, Bohai Sea, China.

PubMed

Ding, Xigui; Ye, Siyuan; Yuan, Hongming; Krauss, Ken W

2018-06-01

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg (Pb), 50 mg/kg (Zn), 48.8 mg/kg (Cr), 0.1 mg/kg (Cd), 8.4 mg/kg (As), and 20.3 μg/kg (Hg). These concentrations generally met the China Marine Sediment Quality criteria. However, both pollution assessments indicated moderate to strong Cd and Hg contamination in the study area. The potential ecological risk index suggested that the combined ecological risk of the seven studied metals may be low, but that 24.5% of the sites, where sediments were finer and higher in Corg concentration, had high ecological risk in Hg and Cd pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Observation of suspended sediments in Mobile Bay, Alabama from satellite

USGS Publications Warehouse

Stumpf, Richard P.

1991-01-01

As part of a comprehensive geologic study of coastal Alabama and Mississippi, the U.S. Geological Survey is investigating coastal sediment transport in Mobile Bay and the adjacent shelf. Satellite imagery from the NOAA AVHRR is being used to provide data on the variability of spatial patterns in the near-surface suspended sediment concentration. This imagery is processed using atmospheric corrections to remove haze and Rayleigh radiance in order to obtain water reflectances; the reflectances are than converted to approximate sediment concentrations using standard relationships between water reflectance and in situ sediment concentrations. A series of images from early 1990 shows rapid changes in sediment concentrations in response to high river flow of the Alabama-Tombigbee river system. During these times, suspended sediment tends to flow out Mobile Bay without mixing into the eastern lobe of the Bay (Bon Secour Bay). The sediment concentration field also appears to be disturbed by the main ship channel. The sediment plume extends more than 60 km offshore after the peak flow event. One wind event in December 1989 was identified as increasing sediment concentration in the Bay. It is not believed that such an event has been previously observed from satellite.

Origin of the anomalies in light and middle REE in sediments of an estuary affected by phosphogypsum wastes (south-western Spain).

PubMed

Borrego, J; López-González, N; Carro, B; Lozano-Soria, O

2004-12-01

Sc, Y, Th, Cu and rare earth elements (REE) concentrations have been analyzed in 14 samples of surface sediments and in two gravity cores by means of ICP-MS. Mean concentrations of Sc, Y and Th in surface sediments are 6.23, 4.76 and 16.30 ppm, respectively, lower than those present in the Upper Continental Crust (UCC). Cu concentration in these sediments is very high, 1466 ppm, and is caused by inputs from the Odiel and Tinto rivers, affected by acid mine drainage. SigmaREE mean concentration is 106.8 ppm, lower than that observed in other rivers and estuaries. In the cores, Sc, Y and Th concentrations show a significant increase in the intermediate levels, between 10 and 40 cm depth. The same pattern exists with Cu, where concentrations of 4440 ppm can be reached. Vertical evolution patterns for Sc, Y, Cu and heavy REE (HREE) are similar, and contrary to those shown by Th, light REE (LREE) and middle REE (MREE). Plots of North American Shale Composite (NASC)-normalized REE data of surface sediments show a slight depletion in REE concentrations. Most samples present with middle REE enrichment relative to light REE and heavy REE. Conversely, samples of the intermediate levels of the cores show significant enrichment of REE relative to NASC and high values in the (La/Gd)NASC and (La/Yb)NASC ratios. These anomalies in the fractionation patterns caused by enrichments in LREE and MREE concentrations is related to the presence of high concentrations of Th. They were generated by effluents from fertilizer factories between 1968 and 1998 which used phosphorite as source material.

Contaminant profiles for surface water, sediment, flora and fauna associated with the mangrove fringe along middle and lower eastern Tampa Bay.

PubMed

Lewis, M A; Russell, M J

2015-06-15

Contaminant concentrations are reported for surface water, sediment, flora and fauna collected during 2010-2011 from the mangrove fringe along eastern Tampa Bay, Florida. Concentrations of trace metals, chlorinated pesticides, atrazine, total polycyclic aromatic hydrocarbons, and polychlorinated biphenyls were species-, chemical- and location-specific. Contaminants in sediments did not exceed proposed individual sediment quality guidelines. Most sediment quality assessment quotients were less than one indicating the likelihood of no inhibitory effect based on chemical measurements alone. Faunal species typically contained more contaminants than plant species; seagrass usually contained more chemicals than mangroves. Bioconcentration factors for marine angiosperms were usually less than 10 and ranged between 1 and 31. Mercury concentrations (ppm) in blue crabs and fish did not exceed the U.S. Environmental Protection Agency fish tissue criterion of 0.3 and the U.S. Food and Drug Administration action level of 1.0. In contrast, total mercury concentrations in faunal species often exceeded guideline values for wildlife consumers of aquatic biota. Published by Elsevier Ltd.

Upward movement of plutonium to surface sediments during an 11-year field study.

PubMed

Kaplan, D I; Demirkanli, D I; Molz, F J; Beals, D M; Cadieux, J R; Halverson, J E

2010-05-01

An 11-year lysimeter study was established to monitor the movement of Pu through vadose zone sediments. Sediment Pu concentrations as a function of depth indicated that some Pu moved upward from the buried source material. Subsequent numerical modeling suggested that the upward movement was largely the result of invading grasses taking up the Pu and translocating it upward. The objective of this study was to determine if the Pu of surface sediments originated from atmosphere fallout or from the buried lysimeter source material (weapons-grade Pu), providing additional evidence that plants were involved in the upward migration of Pu. The (240)Pu/(239)Pu and (242)Pu/(239)Pu atomic fraction ratios of the lysimeter surface sediments, as determined by Thermal Ionization Mass Spectroscopy (TIMS), were 0.063 and 0.00045, respectively; consistent with the signatures of the weapons-grade Pu. Our numerical simulations indicate that because plants create a large water flux, small concentrations over multiple years may result in a measurable accumulation of Pu on the ground surface. These results may have implications on the conceptual model for calculating risk associated with long-term stewardship and monitored natural attenuation management of Pu contaminated subsurface and surface sediments. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter

PubMed Central

Lin, Yu-Shih; Koch, Boris P.; Feseker, Tomas; Ziervogel, Kai; Goldhammer, Tobias; Schmidt, Frauke; Witt, Matthias; Kellermann, Matthias Y.; Zabel, Matthias; Teske, Andreas; Hinrichs, Kai-Uwe

2017-01-01

Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life. PMID:28327661

Relation between Enterococcus concentrations and turbidity in fresh and saline recreational waters, coastal Horry County, South Carolina, 2003–04

USGS Publications Warehouse

Landmeyer, James E.; Garigen, Thomas J.

2016-06-24

The positive relation observed between turbidity and Enterococcus concentrations in surface water at the water-quality data collection station located in the channel that drains a freshwater swamp may be attributed to bacterial survival in the abundant channel bed sediments that characterized this more naturalized area. Surface-water bed sediments collected near each water-quality data collection station and the surf zone were incubated in static microcosms in the laboratory and analyzed for Enterococcus concentrations over time. Enterococcus concentrations continued to persist in bed sediments collected in the channel that drains the swamp even after almost 4 months of incubation. Conversely, enterococci were not observed to persist in bed sediments characterized by high specific conductance. Although it is currently (2016) unknown whether this persistence of enterococci demonstrates growth or viability, the data indicate that enterococci can exist in channel bed-sediment environments outside of a host for a long time. This observation confirms previous reports that challenge the use of Enterococcus concentrations as an indicator of the recent introduction of fecal-related material and the associated acute risk to other pathogens.

Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event.

PubMed

Laissaoui, A; Mas, J L; Hurtado, S; Ziad, N; Villa, M; Benmansour, M

2013-06-01

This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles.

Factors influencing mercury in freshwater surface sediments of northeastern North America

USGS Publications Warehouse

Kamman, N.C.; Chalmers, A.; Clair, T.A.; Major, A.; Moore, R.B.; Norton, S.A.; Shanley, J.B.

2005-01-01

We report on an inventory and analysis of sediment mercury (Hg) concentrations from 579 sites across northeastern North America. Sediment Hg concentrations ranged from the limit of detection ca. 0.01-3.7 ??g g -1 (dry weight, d.w.), and the average concentration was 0.19 ??g g-1 (d.w.) Sediment methylmercury concentrations ranged from 0.15 to 21 ng g-1 (d.w.) and the mean concentration was 3.83 ng g -1 (d.w.). Total Hg concentrations (HgT) were greatest in lakes > reservoirs > rivers, although the proportion of Hg as methylmercury showed an inverse pattern. Total Hg was weakly and positively correlated with the sediment organic matter and percent of watershed as forested land, and weakly and negatively correlated with sediment solids content, drainage area, and agricultural land. Sediment methylmercury concentrations were weakly and positively correlated to wetland area, and weakly and negatively correlated to drainage area. Methylmercury, expressed as a percentage of HgT was positively correlated to agricultural land area. For sites with co-located sediment and fish-tissue sampling results, there was no relationship between sediment Hg and fish-tissue Hg. Finally, our data indicate that at least 44% of waters across the region have sediment HgT concentrations in excess of Canadian and United States minimum sediment contaminant guidelines for the protection of aquatic biota. ?? 2005 Springer Science+Business Media, Inc.

Hydrocarbons in the Surface Layer of Bottom Sediments in the Northwestern Caspian Sea

NASA Astrophysics Data System (ADS)

Nemirovskaya, I. A.; Ostrovskaya, E. V.

2018-03-01

The paper presents research results on the concentrations and compositions of aliphatic and polycyclic aromatic hydrocarbons in the surface layer of bottom sediments in the Northwestern Caspian Sea (2014) and compares them to data for sediments of the Middle and Southern Caspian (2012-2013). The seepage of hydrocarbons out of the sediment mass, resulting in abnormally high concentrations of aliphatic hydrocarbons per dry weight (up to 468 μg/g), as well as within the Corg composition (up to 35.2%), is considered the main source of hydrocarbons in sediments in the surveyed area of the Northern Caspian. This is also confirmed by the absence of any correlation between the hydrocarbon and Corg distributions, as well as by the transformed oil composition of high-molecular alkanes. The distribution of markers within polycyclic aromatic hydrocarbons points to a mixed genesis—petrogenic and pyrogenic—with prevalence of the latter. Unlike the shallow-water northern part of the Caspian Sea, the content and composition of hydrocarbons in deep-seated sediments are affected by facial conditions of sedimentation and by matter exchange at the water-bottom interface. Therefore, despite high Corg concentrations (up to 9.9%), sediments in deep-water depressions are characterized by a quite low concentration of aliphatic hydrocarbons (52 μg/g on average; 0.2% of Corg) with prevailing natural allochthonous alkanes.

The effect of sedimentation and diffusion on cellular uptake of gold nanoparticles

PubMed Central

Cho, Eun Chul; Zhang, Qiang; Xia, Younan

2011-01-01

In vitro experiments typically measure the uptake of nanoparticles by exposing cells at the bottom of a culture plate to a suspension of nanoparticles, which is assumed to be well-dispersed. However, nanoparticles can sediment and this means the concentration of particles on the cell surface and those actually taken up by the cells may be higher than the initial bulk concentration. Here we use upright and inverted cell culture configurations to show that cellular uptake of gold nanoparticles depends on the sedimentation and diffusion velocities of the nanoparticles and is independent of size, shape, density, surface coating and initial concentration of the nanoparticles. Generally more nanoparticles are taken up in the upright configuration than the inverted one and nanoparticles that sediment faster showed greater differences in uptake between the two configurations. Our results suggest that cellular uptake of nanoparticles is sensitive to the way cells are positioned and sedimentation need to be considered when performing in vitro studies for large and heavy nanoparticles. PMID:21516092

A baseline study on the concentration of trace elements in the surface sediments off Southwest coast of Tamil Nadu, India.

PubMed

Godson, Prince S; Magesh, N S; Peter, T Simon; Chandrasekar, N; Krishnakumar, S; Vincent, Salom Gnana Thanga

2018-01-01

Forty two surface sediment samples were collected in order to document baseline elemental concentration along the Southwest coast of Tamil Nadu, India. The elements detected were Manganese (Mn), Zinc (Zn), Iron (Fe), Copper (Cu), Nickel (Ni) and Lead (Pb). The concentration of Fe and Mn was primarily controlled by the riverine input. The source of Pb and Zn is attributed to leaded petrol and anti-biofouling paints. The calculated index (EF, Igeo and CF) suggests that the sediments of the study area are significantly enriched with all elements except Pb. The contamination factor showed the order of Mn>Zn>Fe>Cu>Ni>Pb. The sediment pollution index (SPI) revealed that the sediments belonged to low polluted to dangerous category. The correlation matrix and dendrogram showed that the elemental distribution was chiefly controlled by riverine input as well as anthropogenic activity in the coast. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sedimentology and geochemistry of surface sediments, outer continental shelf, southern Bering Sea

USGS Publications Warehouse

Gardner, J.V.; Dean, W.E.; Vallier, T.L.

1980-01-01

Present-day sediment dynamics, combined with lowerings of sea level during the Pleistocene, have created a mixture of sediments on the outer continental shelf of the southern Bering Sea that was derived from the Alaskan Mainland, the Aleutian Islands, and the Pribilof ridge. Concentrations of finer-grained, higher-organic sediments in the region of the St. George basin have further modified regional distribution patterns of sediment composition. Q-mode factor analysis of 58 variables related to sediment size and composition - including content of major, minor, and trace elements, heavy and light minerals, and clay minerals - reveals three dominant associations of sediment: 1. (1) The most significant contribution, forming a coarse-grained sediment scattered over most of the shelf consists of felsic sediment derived from the generally quartz-rich rocks of the Alaskan mainland. This sediment contains relatively high concentrations of Si, Ba, Rb, quartz, garnet, epidote, metamorphic rock fragments, potassium feldspar, and illite. 2. (2) The next most important group, superimposed on the felsic group consists of andesitic sediment derived from the Aleutian Islands. This more mafic sediment contains relatively high concentrations of Na, Ca, Ti, Sr, V, Mn, Cu, Fe, Al, Co, Zn, Y, Yb, Ga, volcanic rock fragments, glass, clinopyroxene, smectite, and vermiculite. 3. (3) A local group of basaltic sediment, derived from rocks of the Pribilof Islands, is a subgroup of the Aleutian andesite group. Accumulation of fine-grained sediment in St. George basin has created a sediment group containing relatively high concentrations of C, S, U, Li, B, Zr, Ga, Hg, silt, and clay. Sediment of the Aleutian andesite group exhibits a strong gradient, or "plume", with concentrations decreasing away from Unimak Pass and toward St. George basin. The absence of present-day currents sufficient to move even clay-size material as well as the presence of Bering submarine canyon between the Aleutian Islands and the outer continental shelf and slope, indicates that Holocene sediment dynamics cannot be used to explain the observed distribution of surface sediment derived from the Aleutian Islands. We suggest that this pattern is relict and resulted from sediment dynamics during lower sea levels of the Pleistocene. ?? 1980.

Trace-metal concentrations in sediment and water and health of aquatic macroinvertebrate communities of streams near Park City, Summit County, Utah

USGS Publications Warehouse

Giddings, Elis M.P.; Hornberger, Michelle I.; Hadley, Heidi K.

2001-01-01

The spatial distribution of metals in streambed sediment and surface water of Silver Creek, McLeod Creek, Kimball Creek, Spring Creek, and part of the Weber River, near Park City, Utah, was examined. From the mid-1800s through the 1970s, this region was extensively mined for silver and lead ores. Although some remediation has occurred, residual deposits of tailing wastes remain in place along large sections of Silver Creek. These tailings are the most likely source of metals to this system. Bed sediment samples were collected in 1998, 1999, and 2000 and analyzed using two extraction techniques: a total extraction that completely dissolves all forms of metals in minerals and trace elements associated with the sediment; and a weak-acid extraction that extracts the metals and trace elements that are only weakly adsorbed onto the sediment surface. This latter method is used to determine the more biologically relevant fraction of metal complexed onto the sediment. Water samples were collected in March and August 2000 and were analyzed for total and dissolved trace metals.Concentrations of silver, cadmium, copper, lead, mercury, and zinc in the streambed sediment of Silver Creek greatly exceeded background concentrations. These metals also exceeded established aquatic life criteria at most sites. In the Weber River, downstream of the confluence with Silver Creek, concentrations of cadmium, lead, zinc, and total mercury in streambed sediment also exceeded aquatic life guidelines, however, concentrations of metals in streambed sediment of McLeod and Kimball Creeks were lower than Silver Creek. Water-column concentrations of zinc, total mercury, and methylmercury in Silver Creek were high relative to unimpacted sites, and exceeded water quality criteria for the protection of aquatic organisms. Qualitative measurements of the macroinvertebrate community in Silver Creek were compared to the spatial distribution of metals in streambed sediment. The data indicate that impairment related to metal concentration exists in Silver Creek.

Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

NASA Astrophysics Data System (ADS)

Méndez-García, C.; Renteria-Villalobos, M.; García-Tenorio, R.; Montero-Cabrera, M. E.

2014-07-01

Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. 232Th-series, 238U-series, 40K and 137Cs activity concentrations (AC, Bq kg-1) were determined by gamma spectrometry with a high purity Ge detector. 238U and 234U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating of core sediments was performed applying CRS method to 210Pb activities. Results were verified by 137Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High 238U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento - Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) 234U/overflow="scroll">238U and 238U/overflow="scroll">226Ra in sediments have values between 0.9-1.2, showing a behavior close to radioactive equilibrium in the entire basin. 232Th/overflow="scroll">238U, 228Ra/overflow="scroll">226Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.

Geochemical evidence for enhanced preservation of organic matter in the oxygen minimum zone of the continental margin of northern California during the Late Pleistocene

USGS Publications Warehouse

Dean, Walter E.; Gardner, James V.; Anderson, Roger Y.

1994-01-01

The present upper water mass of the northeastern Pacific Ocean off California has a well-developed oxygen minimum zone between 600 and 1200 m wherein concentrations of dissolved oxygen are less than 0.5 mL/L. Even at such low concentrations of dissolved oxygen, benthic burrowing organisms are abundant enough to thoroughly bioturbate the surface and near-surface sediments. These macro organisms, together with micro organisms, also consume large quantities of organic carbon produced by large seasonal stocks of plankton in the overlying surface waters, which are supported by high concentrations of nutrients within the California Current upwelling system. In contrast to modern conditions of bioturbation, laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen minimum zone from at least as far north as the California-Oregon border and as far south as Point Conception. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine “snow” demonstrates that the dark-light lamination couplets are indeed annual (varves). These upper Pleistocene varved sediments contain more abundant lipid-rich “sapropelic” (type II) organic matter than the overlying bioturbated, oxidized Holocene sediments. The baseline of stable carbon isotopic composition of the organic matter in these slope cores does not change with time, indicating that the higher concentrations of type II organic matter in the varved sediments represent better preservation of organic matter rather than any change in the source of organic matter.

Modeling the transport of PCDD/F compounds in a contaminated river and the possible influence of restoration dredging on calculated fluxes.

PubMed

Malve, Olli; Salo, Simo; Verta, Matti; Forsius, John

2003-08-01

River Kymijoki, the fourth largest river in Finland, has been heavily polluted by pulp mill effluents as well as by chemical industry. Loading has been reduced considerably, although remains of past emissions still exist in river sediments. The sediments are highly contaminated with polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated diphenyl ethers (PCDEs), and mercury originating from production of the chlorophenolic wood preservative (Ky-5) and other sources. The objective of this study was to simulate the transport of these PCDD/F compounds with a one-dimensional flow and transport model and to assess the impact of restoration dredging. Using the estimated trend in PCDD/F loading, downstream concentrations were calculated until 2020. If contaminated sediments are removed by dredging, the temporary increase of PCDD/F concentrations in downstream water and surface sediments will be within acceptable limits. Long-term predictions indicated only a minor decrease in surface sediment concentrations but a major decrease if the most contaminated sediments close to the emission source were removed. A more detailed assessment of the effects is suggested.

Characteristics of the near-bottom suspended sediment field over the continental shelf off northern California based on optical attenuation measurements during STRESS and SMILE

NASA Astrophysics Data System (ADS)

Trowbridge, J. H.; Butman, B.; Limeburner, R.

1994-08-01

Time-series measurements of current velocity, optical attenuation and surface wave intensity obtained during the Sediment Transport Events on Shelves and Slopes (STRESS) experiments, combined with shipboard measurements of conductivity, temperature and optical attenuation obtained during the Shelf Mixed Layer Experiment (SMILE), provide a description of the sediment concentration field over the central and outer shelf off northern California. The questions addressed are: (1) existence and characteristics of bottom nepheloid layers and their relationship to bottom mixed layers; (2) characteristics of temporal fluctuations in sediment concentration and their relationship to waves and currents; (3) spatial scales over which suspended sediment concentrations vary horizontally; and (4) vertical distribution of suspended sediment.

[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.

Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia).

PubMed

Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

2015-07-15

Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trace-metal and organic constituent concentrations in bed sediment at Big Base and Little Base Lakes, Little Rock Air Force Base, Arkansas—Comparisons to sediment-quality guidelines and indications for timing of exposure

USGS Publications Warehouse

Justus, B.G.; Hays, Phillip D.; Hart, Rheannon M.

2015-09-16

Regarding highest concentrations and associated timing of exposure, trace metals analyzed in the sediment core seem to indicate three fairly distinct exposure patterns. For 11 trace metals that had the highest concentration measured in the shallowest and most recently deposited sediment, the most likely explanation is recent exposure by anthropogenic activities. Most of the 11 trace metals with highest concentrations in shallow sediment are relatively innocuous; however, arsenic, copper, selenium, and zinc are among the U.S. Environmental Protection Agency’s 126 priority pollutants. For three trace metals (cadmium, lead, and mercury), for which concentrations were highest in sediments that were 16–20 centimeters down the core, it is likely that a source associated with those contaminants during the period when those sediments were deposited, was reduced or eliminated. The eight remaining trace metals, for which concentrations were highest in sediments that were just below the prereservoir surface, likely had sources that were eliminated soon after lake construction or occurred at relatively high background concentrations in soils in the area around Little Rock Air Force Base.

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.

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.

Spatial variability of surface-sediment porewater pH and related water-column characteristics in deep waters of the northern South China Sea

NASA Astrophysics Data System (ADS)

Shao, Changgao; Sui, Yi; Tang, Danling; Legendre, Louis

2016-12-01

This study analyzes the pH of surface-sediment porewater (i.e. 2-3 cm below the water-sediment interface), and concentrations of CaCO3 and organic carbon (OC) in 1192 sediment cores from the northern South China Sea, in water depths ranging from 137 to 3702 m. This is the first study in the literature to analyze the large-scale spatial variability of deep-water surface-sediment pH over a large ocean basin. The data showed strong spatial variations in pH. The lowest pH values (<7.3) were observed south of Hainan Island, an area that is affected by summer upwelling and freshwater runoff from the Pearl and Red Rivers. Moderately low pH values (generally 7.3-7.5) occurred in two other areas: a submarine canyon, where sediments originated partly from the Pearl River and correspond to a paleo-delta front during the last glacial period; and southwest of Taiwan Island, where waters are affected by the northern branch of the Kuroshio intrusion current (KIC) and runoff from Taiwan rivers. The surface sediments with the highest pH (⩾7.5, and up to 8.3) were located in a fourth area, which corresponded to the western branch of the KIC where sediments have been intensively eroded by bottom currents. The pH of surface-sediment porewater was significantly linearly related to water depth, bottom-water temperature, and CaCO3 concentration (p < 0.05 for the whole sampling area). This study shows that the pH of surface-sediment porewater can be sensitive to characteristics of the overlying water column, and suggests that it will respond to global warming as changes in surface-ocean temperature and pH progressively reach deeper waters.

Open inlet conversion: Water quality benefits of two designs

USDA-ARS?s Scientific Manuscript database

Open surface inlets that connect to subsurface tile drainage systems provide a direct pathway for movement of sediment, nutrients, and agrochemicals to surface waters. This study was conducted to determine the reduction in drainage effluent total suspended sediment (TSS) and phosphorus (P) concentr...

Impact Of Groundwater Discharge On Contaminant Behavior In Sediments

EPA Science Inventory

The discharge of groundwater into surface water may influence the concentrations and availability of contaminants in sediments. There are three predominant pathways by which groundwater may affect the characteristics of contaminated sediments: 1) direct contribution of contamin...

Multivariate geostatistical analysis and source identification of heavy metals in the sediment of Poyang Lake in China.

PubMed

Dai, Lijun; Wang, Lingqing; Li, Lianfang; Liang, Tao; Zhang, Yongyong; Ma, Chuanxin; Xing, Baoshan

2018-04-15

Heavy metals in lake sediment have become a great concern because their remobilization has frequently occurred under hydrodynamic disturbance in shallow lakes. In this study, heavy metals (Cr, Cu, Cd, Pb, and Zn) concentrations in the surface and core sediments of the largest freshwater lake in China, Poyang Lake, were investigated. Geostatistical prediction maps of heavy metals distribution in the surface sediment were completed as well as further data mining. Based on the prediction maps, the ranges of Cr, Cu, Cd, Pb, and Zn concentrations in the surface sediments of the entire lake were 96.2-175.2, 38.3-127.6, 0.2-2.3, 22.5-77.4, and 72.3-254.4mg/kg, respectively. A self-organizing map (SOM) was applied to find the inner element relation of heavy metals in the sediment cores. K-means clustering of the self-organizing map was also completed to define the Euclidian distance of heavy metals in the sediment cores. The geoaccumulation index (I geo ) for Poyang Lake indicated a varying degree of heavy metal contamination in the surface sediment, especially for Cu. The heavy metal contamination in the sediment profiles had similar pollution levels as those of surface sediment, except for Cd. Correlation matrix mapping and principal component analysis (PCA) were used to support the idea that Cr, Pb, and Zn may be mainly derived from both lithogenic and human activities, such as atmospheric and river inflow transportation, whereas Cu and Cd may be mainly contributed from anthropogenic sources, such as mining activities and fertilizer application. Copyright © 2017 Elsevier B.V. All rights reserved.

Temperature signal in suspended sediment export from an Alpine catchment

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Data on Streamflow and Quality of Water and Bottom Sediment in and near Humboldt Wildlife Management Area, Churchill and Pershing Counties, Nevada, 1998-2000

USGS Publications Warehouse

Paul, Angela P.; Thodal, Carl E.

2003-01-01

This study was initiated to expand upon previous findings that indicated concentrations of dissolved solids, arsenic, boron, mercury, molybdenum, selenium, and uranium were either above geochemical background concentrations or were approaching or exceeding ecological criteria in the lower Humboldt River system. Data were collected from May 1998 to September 2000 to further characterize streamflow and surface-water and bottom-sediment quality in the lower Humboldt River, selected agricultural drains, Upper Humboldt Lake, and Lower Humboldt Drain (ephemeral outflow from Humboldt Sink). During this study, flow in the lower Humboldt River was either at or above average. Flows in Army and Toulon Drains generally were higher than reported in previous investigations. An unnamed agricultural drain contributed a small amount to the flow measured in Army Drain. In general, measured concentrations of sodium, chloride, dissolved solids, arsenic, boron, molybdenum, and uranium were higher in water from agricultural drains than in Humboldt River water during this study. Mercury concentrations in water samples collected during the study period typically were below the laboratory reporting level. However, low-level mercury analyses showed that samples collected in August 1999 from Army Drain had higher mercury concentrations than those collected from the river or Toulon Drain or the Lower Humboldt Drain. Ecological criteria and effect concentrations for sodium, chloride, dissolved solids, arsenic, boron, mercury, and molybdenum were exceeded in some water samples collected as part of this study. Although water samples from the agricultural drains typically contained higher concentrations of sodium, chloride, dissolved solids, arsenic, boron, and uranium, greater instantaneous loads of these constituents were carried in the river near Lovelock than in agricultural drains during periods of high flow or non-irrigation. During this study, the high flows in the lower Humboldt River produced the maximum instantaneous loads of sodium, chloride, dissolved solids, arsenic, boron, molybdenum, and uranium at all river-sampling sites, except molybdenum near Imlay. Nevada Division of Environmental Protection monitoring reports on mine-dewatering discharge for permitted releases of treated effluent to the surface waters of the Humboldt River and its tributaries were reviewed for reported discharges and trace-element concentrations from June 1998 to September 1999. These data were compared with similar information for the river near Imlay. In all bottom sediments collected for this study, arsenic concentrations exceeded the Canadian Freshwater Interim Sediment-Quality Guideline for the protection of aquatic life and probable-effect level (concentration). Sediments collected near Imlay, Rye Patch Reservoir, Lovelock, and from Toulon Drain and Army Drain were found to contain cadmium and chromium concentrations that exceeded Canadian criteria. Chromium concentrations in sediments collected from these sites also exceeded the consensus-based threshold-effect concentration. The Canadian criterion for sediment copper concentration was exceeded in sediments collected from the Humboldt River near Lovelock and from Toulon, Army, and the unnamed agricultural drains. Mercury in sediments collected near Imlay and from Toulon Drain in August 1999 exceeded the U.S. Department of the Interior sediment probable-effect level. Nickel concentrations in sediments collected during this study were above the consensus-based threshold-effect concentration. All other river and drain sediments had constituent concentrations below protective criteria and toxicity thresholds. In Upper Humboldt Lake, chloride, dissolved solids, arsenic, boron, molybdenum, and uranium concentrations in surface-water samples collected near the mouth of the Humboldt River generally were higher than in samples collected near the mouth of Army Drain. Ecological criteria or effect con

Suspended sediment concentration and optical property observations of mixed-turbidity, coastal waters through multispectral ocean color inversion

EPA Science Inventory

Multispectral satellite ocean color data from high-turbidity areas of the coastal ocean contain information about the surface concentrations and optical properties of suspended sediments and colored dissolved organic matter (CDOM). Empirical and semi-analytical inversion algorit...

Mercury methylation in high and low-sulphate impacted wetland ponds within the prairie pothole region of North America.

PubMed

Hoggarth, Cameron G J; Hall, Britt D; Mitchell, Carl P J

2015-10-01

Using enriched stable (201)Hg injections into intact sediment cores, we provide the first reported Hg methylation potential rate constants (km) in prairie wetland ponds (0.016-0.17 d(-1)). Our km values were similar to other freshwater wetlands and did not differ in ponds categorized with high compared to low surface water concentrations of sulphate. Sites with high sulphate had higher proportions of methylmercury (MeHg) in sediment (2.9 ± 1.6% vs. 1.0 ± 0.3%) and higher surface water MeHg concentrations (1.96 ± 1.90 ng L(-1)vs. 0.56 ± 0.55 ng L(-1)). Sediment-porewater partitioning coefficients were small, and likely due to high ionic activity. Our work suggests while km measurements are useful for understanding mercury cycling processes, they are less important than surface water MeHg concentrations for assessing MeHg risks to biota. Significant differences in MeHg concentrations between sites with high and low sulphate concentrations may also inform management decisions concerning wetland remediation and creation. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of sediment ingestion in exposing wood ducks to lead

USGS Publications Warehouse

Beyer, W.N.; Blus, L.J.; Henny, C.J.; Audet, D.

1997-01-01

Waterfowl on lateral lakes of the Coeur d'Alene River and on Lake Coeur d'Alene have been poisoned for many years by lead (Pb) from mining and smelting. In 1992 we undertook a study in the area to determine the importance of sediment ingestion in exposing wood ducks (Aix sponsa) to Pb. Digesta were removed from the intestines of wood ducks collected from contaminated and reference areas. The average Pb concentration in digesta of wood ducks from the contaminated area was 32 ppm dry weight. The sediment content was estimated to average less than 2% of the dry weight of the wood duck diet. Lead concentrations in digesta were closely correlated with concentrations of acid-insoluble ash, Al, Ti and Fe in digesta, and these four variables are associated with sediment. Samples containing low concentrations of these variables also had low concentrations of Pb. These results suggest that most of the Pb in the digesta came from ingested sediment, rather than from plant material in the diet. The importance of ingested sediment as a source of lead was unexpected, because wood ducks are surface feeders on aquatic plants and they rarely dabble beneath the surface or feed on the bottom. However, it appears that sediment ingestion is sometimes the principal route of exposure to environmental contaminants that are not readily taken up by plants and invertebrates, and this route should be considered in risk assessments of waterfowl.

Hydrogeology and chemical quality of water and bottom sediment at three stormwater detention ponds, Pinellas County, Florida

USGS Publications Warehouse

Fernandez, Mario; Hutchinson, C.B.

1993-01-01

An investigation of three detention ponds in Pinellas County, Florida indicated little potential for chemical contamination of surficial-aquifer ground water; however, concentrations of contami- nants in some sediments are sufficient to indicate possible hazardous levels of bioconcentration in benthic organisms. The general direction of ground- water movement at three pond sites indicates that the ponds are ground-water discharge points. Shallow ground water tends to move laterally toward these ponds, which have surface outflow, instead of from the ponds into the aquifer. Surface-water and pond-sediment samples from a 1-year-old pond were collected and analyzed for inorganic constituents and organic compounds. The concentrations were either near or below analytical detection limits. Surface-water and pond-sediment samples from the other two ponds, 20- and 30-years old, respectively, also were analyzed for inorganic constituents and organic compounds. The water quality of these older ponds was not significantly different from that of the 1-year-old pond. However, bottom sediments in the 20- and 30-year-old ponds contained 16 and 23 organic compounds, respectively. None of the organic compounds were in sufficient concentrations to cause concern about their chronic effects on aquatic life. Concentrations of dichlordiphenyl-trichlorethane, dieldrin, and heptachlor were above the hazardous level with respect to bioconcentration in the food chain.

Sediment quality in Burlington Harbor, Lake Champlain, U.S.A.

USGS Publications Warehouse

Lacey, E.M.; King, J.W.; Quinn, J.G.; Mecray, E.L.; Appleby, P.G.; Hunt, A.S.

2001-01-01

Surface samples and cores were collected in 1993 from the Burlington Harbor region of Lake Champlain. Sediment samples were analyzed for trace metals (cadmium, copper, lead, nickel, silver and zinc), simultaneously extracted metal/acid volatile sulfide (SEM-AVS), grain size, nutrients (carbon and nitrogen) and organic contaminants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)). The concentrations of cadmium, copper, silver and zinc from the partial sediment digestion of the surface samples correlated well with each other (r2 > 0.60) indicating that either a common process, or group of processes determined the sediment concentrations of these metals. In an analysis of the spatial distribution of the trace metals and PAHs, high surficial concentrations were present in the southern portion of the Harbor. The trace metal trend was strengthened when the concentrations were normalized by grain size. A sewage treatment plant outfall discharge was present in the southeastern portion of the Harbor at the time of this study and is the major source of trace metal and PAH contamination. Evaluation of sediment cores provides a proxy record of historical trace metal and organic inputs. The peak accumulation rate for copper, cadmium, lead, and zinc was in the late 1960s and the peak silver accumulation rate was later. The greatest accumulation of trace metals occurred in the late 1960s after discharges from the STP began. Subsequent declines in trace metal concentrations may be attributed to increased water and air regulations. The potential toxicity of trace metals and organic contaminants was predicted by comparing contaminant concentrations to benchmark concentrations and potential trace metal bioavailability was predicted with SEM-AVS results. Surface sample results indicate lead, silver, ???PAHs and ???PCBs are potentially toxic and/or bioavailable. These predictions were supported by studies of biota in the Burlington Harbor watershed. There is a clear trend of decreasing PAH and trace metal contaminant concentrations with distance from the STP outfall.Surface samples and cores were collected in 1993 from the Burlington Harbor region of Lake Champlain. Sediment samples were analyzed for trace metals (cadmium, copper, lead, nickel, silver and zinc), simultaneously extracted metal/acid volatile sulfide (SEM-AVS), grain size, nutrients (carbon and nitrogen) and organic contaminants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)). The concentrations of cadmium, copper, silver and zinc from the partial sediment digestion of the surface samples correlated well with each other (r2>0.60) indicating that either a common process, or group of processes determined the sediment concentrations of these metals. In an analysis of the spatial distribution of the trace metals and PAHs, high surficial concentrations were present in the southern portion of the Harbor. The trace metal trend was strengthened when the concentrations were normalized by grain size. A sewage treatment plant outfall discharge was present in the southeastern portion of the Harbor at the time of this study and is the major source of trace metal and PAH contamination. Evaluation of sediment cores provides a proxy record of historical trace metal and organic inputs. The peak accumulation rate for copper, cadmium, lead, and zinc was in the late 1960s and the peak silver accumulation rate was later. The greatest accumulation of trace metals occurred in the late 1960s after discharges from the STP began. Subsequent declines in trace metal concentrations may be attributed to increased water and air regulations. The potential toxicity of trace metals and organic contaminants was predicted by comparing contaminant concentrations to benchmark concentrations and potential trace metal bioavailability was predicted with SEM-AVS results. Surface sample results indicate lead, silver, ??PAHs and ??PCBs are potentially toxic and/or bi

Trace metal in sediment from a deep-sea floor of Makassar Strait

NASA Astrophysics Data System (ADS)

Budianto, F.; Lestari

2018-02-01

Makassar Strait is located in the entrance of Indonesian Through Flow (ITF). However, the geochemistry of metals in sediment within Makassar Strait remains unexplored. The aim of this study was to measure the concentration of metals in sediment and to assess the sediment quality based on those metals concentrations. The sediment was collected from 632-4730 m in depth using giant piston corer on R/V Baruna Jaya VIII in December 2014. In each observation point, three layers of sediment were sub-sampled from the core i.e. surface layer (0-5 cm), middle layer (45-55 cm) and bottom layer. The metals were analyzed using acid digestion procedure followed by Atomic Absorption Spectrophotometer. The result indicated that the metal has spatially insignificant differences in sediment and the increase of metal concentration by depth was noticed. The Enrichment factor presented as no enrichment to minor enrichment of metal in sediment.

Analysis of pesticides in surface water and sediment from Yolo Bypass, California, 2004-2005

USGS Publications Warehouse

Smalling, Kelly L.; Orlando, James L.; Kuivila, Kathryn

2005-01-01

Inputs to the Yolo Bypass are potential sources of pesticides that could impact critical life stages of native fish. To assess the direct inputs during inundation, pesticide concentrations were analyzed in water, in suspended and bed-sediment samples collected from six source watersheds to the Yolo Bypass, and from three sites within the Bypass in 2004 and 2005. Water samples were collected in February 2004 from the six input sites to the Bypass during the first flood event of the year representing pesticide inputs during high-flow events. Samples were also collected along a transect across the Bypass in early March 2004 and from three sites within the Bypass in the spring of 2004 under low-flow conditions. Low-flow data were used to understand potential pesticide contamination and its effects on native fish if water from these areas were used to flood the Bypass in dry years. To assess loads of pesticides to the Bypass associated with suspended sediments, large-volume water samples were collected during high flows in 2004 and 2005 from three sites, whereas bed sediments were collected from six sites in the fall of 2004 during the dry season. Thirteen current-use pesticides were detected in surface water samples collected during the study. The highest pesticide concentrations detected at the input sites to the Bypass corresponded to the first high-flow event of the year. The highest pesticide concentrations at the two sites sampled within the Bypass during the early spring were detected in mid-April following a major flood event as the water began to subside. The pesticides detected and their concentrations in the surface waters varied by site; however, hexazinone and simazine were detected at all sites and at some of the highest concentrations. Thirteen current-use pesticides and three organochlorine insecticides were detected in bed and suspended sediments collected in 2004 and 2005. The pesticides detected and their concentrations varied by site and sediment sample type. Trifluralin, p,p'-DDE, and p,p'-DDT were highest in the bed sediments, whereas oxyfluorfen and thiobencarb were highest in the suspended sediments. With the exception of the three organochlorine insecticides, suspended sediments had higher pesticide concentrations compared with bed sediments, indicating the potential for pesticide transport throughout the Bypass, especially during high-flow events. Understanding the distribution of pesticides between the water and sediment is needed to assess fate and transport within the Bypass and to evaluate the potential effects on native fish.

Assessment of elemental concentrations in streams of the New Lead Belt in southeastern Missouri, 2002-05

USGS Publications Warehouse

Brumbaugh, William G.; May, Thomas W.; Besser, John M.; Allert, Ann L.; Schmitt, Christopher J.

2007-01-01

Concerns about possible effects of lead-mining activities on the water quality of federally protected streams located in southeastern Missouri prompted a suite of multidisciplinary studies to be conducted by the U.S. Geological Survey. As part of this investigation, a series of biological studies were initiated in 2001 for streams in the current mining region and the prospecting area. In this report, results are examined for trace elements and other selected chemical measurements in sediment, surface water, and sediment interstitial (pore) water sampled between 2002 and 2005 in association with these biological studies. Compared to reference sites, fine sediments collected downstream from mining areas were enriched in metals by factors as large as 75 for cadmium, 62 for cobalt, 171 for nickel, 95 for lead, and 150 for zinc. Greatest metal concentrations in sediments collected in 2002 were from sites downstream from mines on Strother Creek, Courtois Creek, and the West Fork Black River. Sediments from sites on Bee Fork, Logan Creek, and Sweetwater Creek also were noticeably enriched in lead. Sediments in Clearwater Lake, at least 75 kilometers downstream from mining activity, had metal concentrations that were 1.5 to 2.1 times greater than sediments in an area of the lake with no upstream mining activity. Longitudinal sampling along three streams in 2004 indicated that sediment metal concentrations decreased considerably a few kilometers downstream from mining activities; however, in Strother Creek some metals were still enriched by a factor of five or more as far as 13 kilometers downstream from the Buick tailings impoundment. Compared with 2002 samples, metals concentrations were dramatically lower in sediments collected in 2004 at an upper West Fork Black River site, presumably because beneficiation operations at the West Fork mill ceased in 2000. Concentrations of metals and sulfate in sediment interstitial (pore) waters generally tracked closely with metal concentrations in sediments. Metals, including cobalt, nickel, lead, and zinc, were elevated substantially in laboratory-produced pore waters of fine sediments collected near mining operations in 2002 and 2004. Passive diffusion samplers (peepers) buried 4 to 6 centimeters deep in riffle-run stream sediments during 2003 and 2005 had much lower pore-water metal concentrations than the laboratory-produced pore waters of fine sediments collected in 2002 and 2004, but each sampling method produced similar patterns among sites. The combined mean concentration of lead in peeper samples from selected sites located downstream from mining activities for six streams was about 10-fold greater than the mean of the reference sites. In most instances, metals concentrations in surface water and peeper water were not greatly different, indicating considerable exchange between the surface water and pore water at the depths and locations where peepers were situated. Passive sampling probes used to assess metal lability in pore waters of selected samples during 2004 sediment toxicity tests indicated that most of the filterable lead in the laboratory-prepared pore water was relatively non-labile, presumably because lead was complexed by organic matter, or was present as colloidal species. In contrast, large percentages of cobalt and nickel in pore water appeared to be labile. Passive integrative samplers deployed in surface water for up to 3 weeks at three sites in July 2005 confirmed the presence of elevated concentrations of labile metals downstream from mining operations on Strother Creek and, to a lesser extent, Bee Fork. These samplers also indicated a considerable increase in metal loadings occurred for a few days at the Strother Creek site, which coincided with moderate increases in stream discharges in the area.

Environmental assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Santander Bay, Northern Spain.

PubMed

Viguri, J; Verde, J; Irabien, A

2002-07-01

Samples of intertidal surface sediments (0-2 cm) were collected in 17 stations of the Santander Bay, Cantabric Sea, Northern Spain. The concentrations of polycyclic aromatic hydrocarbons (PAHs), 16, were analysed by HPLC and MS detection. Surface sediments show a good linear correlation among the parameters of the experimental organic matter evaluation, where total carbon (TC) and loss on ignition (LOI) are approximately 2.5 and 5 times total organic carbon (TOC). A wide range of TOC from 0.08% to 4.1%, and a broad distribution of the sum of sigma16PAHs, from 0.02 to 344.6 microg/g d.w., which can be correlated by an exponential equation to the TOC, has been identified. A qualitative relationship may be established between the industrial input along the rivers and the concentration of sigma6PAHs in the sediments of the estuaries: Boo estuary (8404-4631 microg/g OC), Solia-San Salvador estuaries (305-113 microg/g OC) and Cubas estuary (31-32 microg/g OC). This work shows a dramatic change in the spatial distribution in the concentration of PAHs of intertidal surface sediments. The left edge of the Bay has the main traffic around the city and the major source of PAHs is from combustion processes and estuarine inputs, leading to medium values of PAHs in the sediments; the right edge of the Bay has much lesser anthropogenic activities leading to lower values of PAHs in sediments. The distribution of individual PAHs in sediments varies widely depending on their structure and molecular weight; the 4-6 ring aromatics predominate in polluted sediments due to their higher persistence. The isomer ratio does not allow any clear identification of the PAHs origin. Environmental evaluation according to Dutch guidelines and consensus sediment quality guidelines based on ecotoxicological data leads to the same conclusion, sediments in the Santander Bay show a very different environmental quality depending on the spatial position from heavily polluted/medium effects to non-polluted/below threshold effects. These results indicate that local sources of PAHs, especially estuary discharges, lead to very different qualities of sediments in coastal zones, where traffic and industrial activities take place.

Current status and historical trends of organochlorine pesticides in the ecosystem of Deep Bay, South China

NASA Astrophysics Data System (ADS)

Qiu, Yao-Wen; Zhang, Gan; Guo, Ling-Li; Cheng, Hai-Rong; Wang, Wen-Xiong; Li, Xiang-Dong; Wai, Onyx W. H.

2009-11-01

To characterize the current status and historical trends in organochlorine pesticides (OCPs) contamination in Deep Bay, an important water body between Hong Kong and mainland China with a Ramsar mangrove wetland (Maipo), samples from seawater, suspended particulate matter (SPM), surface sediment, sediment core and fish were collected to determine the OCPs concentrations. Sediment core dating was accomplished using the 210Pb method. The average concentrations of DDTs, HCHs and chlordanes in water were 1.96, 0.71, 0.81 ng l -1, while in SPM were 36.5, 2.5, 35.7 ng g -1 dry weight, in surface sediment were 20.2, 0.50, 2.4 ng g -1 dry weight, and in fish were 125.4, 0.43, 13.1 ng g -1 wet weight, respectively. DDTs concentrations in various matrices of Deep Bay were intermediate compared with those in other areas. Temporal trends of the targeted OCPs levels in sediment core generally increased from 1948 to 2004, with the highest levels in top or sub-surface sediment. Both DDT composition and historical trends indicated an ongoing fresh DDT input. A positive relationship between the bioconcentration factor (BCF) of target chemicals and the corresponding octanol-water partition coefficient ( Kow), and between the biota-sediment accumulation factors (BSAF) and the Kow were observed in the Bay. The risk assessment indicated that there were potential ecological and human health risks for the target OCPs in Deep Bay.

Occurrence of pharmaceuticals and personal care products, and their associated environmental risks in a large shallow lake in north China.

PubMed

Zhang, Panwei; Zhou, Huaidong; Li, Kun; Zhao, Xiaohui; Liu, Qiaona; Li, Dongjiao; Zhao, Gaofeng

2018-01-13

Eighteen selected pharmaceuticals and personal care products (PPCPs), consisting of five non-antibiotic pharmaceuticals (N-APs), four sulfonamides (SAs), four tetracyclines (TCs), four macrolides (MCs), and one quinolone (QN) were detected in water, pore water, and sediment samples from Baiyangdian Lake, China. A total of 31 water samples and 29 sediment samples were collected in March 2017. Caffeine was detected with 100% frequency in surface water, pore water, and sediment samples. Carbamazepine was detected with 100% frequency in surface water and sediment samples. Five N-APs were prominent, with mean concentrations of 4.90-266.24 ng/l in surface water and 5.07-14.73 μg/kg in sediment samples. Four MCs were prominent, with mean concentrations of 0.97-29.92 ng/l in pore water samples. The total concentrations of the different classes of PPCPs followed the order: N-APs (53.26%) > MCs (25.39) > SAs (10.06%) > TCs (7.64%) > QNs (3.64%) in surface water; N-APs (42.70%) > MCs (25.43%) > TCs (14.69%) > SAs (13.90%) > QNs (3.24%) in sediment samples, and MCs (42.12%) > N-APs (34.80%) > SAs (11.71%) > TCs (7.48%) > QNs (3.88%) in pore water samples. The geographical differences of PPCP concentrations were largely due to anthropogenic activities. Sewage discharged from Baoding City and human activities around Baiyangdian Lake were the main sources of PPCPs in the lake. An environmental risk assessment for the upper quartile concentration was undertaken using calculated risk quotients and indicated a low or medium-high risk from 18 PPCPs in Baiyangdian Lake and its five upstream rivers.

Temporal variations of 90Sr and 137Cs concentrations in Japanese coastal surface seawater and sediments from 1974 to 1998

NASA Astrophysics Data System (ADS)

Ikeuchi, Yoshihiro

2003-09-01

90Sr and 137Cs concentrations were determined in surface water and bottom sediments collected at 11 sites offshore from Japan during the period 1974-1998, to investigate their temporal variations and behaviour in the coastal marine environment. The concentrations of 90Sr and 137Cs in surface water have decreased with time since 1974. After the period of atmospheric nuclear weapons tests, the mean residence times of 90Sr and 137Cs were about 41 and 51 years, respectively. The 137Cs/ 90Sr activity ratios in coastal seawater during the atmospheric nuclear weapons tests (up until 1980) were lower than those after the tests due to the inflow of 90Sr in river water. A sharp increase in 137Cs levels was observed in airborne dust, in precipitation on the Japanese islands, and in coastal surface seawater in 1986 following the Chernobyl accident. However, the 137Cs levels in surface water returned to pre-1986 levels quickly, indicating rapid removal of Cs from the surface to deeper water. Concentrations of 90Sr in sediments were generally much lower than those for 137Cs, reflecting the more effective scavenging of Cs from the water column. In Ca-rich sediments, consisting of corals and shells, higher 90Sr levels and 90Sr/ 137Cs activity ratios were found, reflecting higher accumulation of Sr than Cs in marine organisms. Higher accumulation of 90Sr than 137Cs was also found in seaweed (gulfweed and wakame).

Occurrence, distribution and risk assessment of organophosphate esters in surface water and sediment from a shallow freshwater Lake, China.

PubMed

Xing, Liqun; Zhang, Qin; Sun, Xu; Zhu, Hongxia; Zhang, Shenghu; Xu, Huaizhou

2018-04-30

Organophosphate esters (OPEs) are ubiquitous in the environment and pose a potential threat to ecosystem and human health. This study investigated the concentrations, distributions and risk of 12 OPEs in surface water and sediment from Luoma Lake, Fangting River and Yi River. Solid-phase extraction (SPE) method were used to extract OPEs from water samples, ultrasonic process and SPE method were used to extract OPEs from sediment samples, and the extracts were finally analyzed using the HPLC-MS/MS. The results revealed that the median and maximum concentrations of ΣOPEs were 73.9 and 1066 ng/L in surface water, and were 28.7 and 35.9 ng/g in sediment, respectively. Tris(2-chloroethyl) phosphate (TCEP) and trimethyl phosphate (TMP) were the most abundant OPEs in the surface water with median concentrations of 24.3 and 16.4 ng/L in Luoma Lake, respectively. Triethyl phosphate (TEP) was the most abundant OPE in the sediment with a median concentrations of 28.9 ng/g. However, tricresyl phosphate (TCrP) and ethylhexyl diphenyl phosphate (EHDPP) predominantly contributed to the ecological risk with respective median risk quotients 0.07 and 0.01 for surface water in Luoma Lake. TEP and TCrP were the most significant contributors to the ecological risk with respective median risk quotients of 6.4 × 10 -4 and 5.6 × 10 -4 for sediment. It was also found that inflowing Fangting River could be the major pollution source to Luoma Lake. The no-cancer and carcinogenic risks of OPEs were lower than the theoretical threshold of risk. The study found that the ecological and human health risks due to the exposure to OPEs were currently acceptable. In other words, the Luoma Lake was relatively safer to use as a drinking water source in urban areas in the context of OPEs pollution. Copyright © 2018 Elsevier B.V. All rights reserved.

Uranium mobility and accumulation along the Rio Paguate, Jackpile Mine in Laguna Pueblo, NM.

PubMed

Blake, Johanna M; De Vore, Cherie L; Avasarala, Sumant; Ali, Abdul-Mehdi; Roldan, Claudia; Bowers, Fenton; Spilde, Michael N; Artyushkova, Kateryna; Kirk, Matthew F; Peterson, Eric; Rodriguez-Freire, Lucia; Cerrato, José M

2017-04-19

The mobility and accumulation of uranium (U) along the Rio Paguate, adjacent to the Jackpile Mine, in Laguna Pueblo, New Mexico was investigated using aqueous chemistry, electron microprobe, X-ray diffraction and spectroscopy analyses. Given that it is not common to identify elevated concentrations of U in surface water sources, the Rio Paguate is a unique site that concerns the Laguna Pueblo community. This study aims to better understand the solid chemistry of abandoned mine waste sediments from the Jackpile Mine and identify key hydrogeological and geochemical processes that affect the fate of U along the Rio Paguate. Solid analyses using X-ray fluorescence determined that sediments located in the Jackpile Mine contain ranges of 320 to 9200 mg kg -1 U. The presence of coffinite, a U(iv)-bearing mineral, was identified by X-ray diffraction analyses in abandoned mine waste solids exposed to several decades of weathering and oxidation. The dissolution of these U-bearing minerals from abandoned mine wastes could contribute to U mobility during rain events. The U concentration in surface waters sampled closest to mine wastes are highest during the southwestern monsoon season. Samples collected from September 2014 to August 2016 showed higher U concentrations in surface water adjacent to the Jackpile Mine (35.3 to 772 μg L -1 ) compared with those at a wetland 4.5 kilometers downstream of the mine (5.77 to 110 μg L -1 ). Sediments co-located in the stream bed and bank along the reach between the mine and wetland had low U concentrations (range 1-5 mg kg -1 ) compared to concentrations in wetland sediments with higher organic matter (14-15%) and U concentrations (2-21 mg kg -1 ). Approximately 10% of the total U in wetland sediments was amenable to complexation with 1 mM sodium bicarbonate in batch experiments; a decrease of U concentration in solution was observed over time in these experiments likely due to re-association with sediments in the reactor. The findings from this study provide new insights about how hydrologic events may affect the reactivity of U present in mine waste solids exposed to surface oxidizing conditions, and the influence of organic-rich sediments on U accumulation in the Rio Paguate.

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

USGS Publications Warehouse

Paulson, Anthony J.

2004-01-01

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

Comparison of streamflow and water-quality data collection techniques for the Saginaw River, Michigan

USGS Publications Warehouse

Hoard, C.J.; Holtschlag, D.J.; Duris, J.W.; James, D.A.; Obenauer, D.J.

2012-01-01

In 2009, the Michigan Department of Environmental Quality and the U.S. Geological Survey developed a plan to compare the effect of various streamgaging and water-quality collection techniques on streamflow and stream water-quality data for the Saginaw River, Michigan. The Saginaw River is the primary contributor of surface runoff to Saginaw Bay, Lake Huron, draining approximately 70 percent of the Saginaw Bay watershed. The U.S. Environmental Protection Agency has listed the Saginaw Bay system as an "Area of Concern" due to many factors, including excessive sediment and nutrient concentrations in the water. Current efforts to estimate loading of sediment and nutrients to Saginaw Bay utilize water-quality samples collected using a surface-grab technique and flow data that are uncertain during specific conditions. Comparisons of current flow and water-quality sampling techniques to alternative techniques were assessed between April 2009 and September 2009 at two locations in the Saginaw River. Streamflow estimated using acoustic Doppler current profiling technology was compared to a traditional stage-discharge technique. Complex conditions resulting from the influence of Saginaw Bay on the Saginaw River were able to be captured using the acoustic technology, while the traditional stage-discharge technique failed to quantify these effects. Water-quality samples were collected at two locations and on eight different dates, utilizing both surface-grab and depth-integrating multiple-vertical techniques. Sixteen paired samples were collected and analyzed for suspended sediment, turbidity, total phosphorus, total nitrogen, orthophosphate, nitrite, nitrate, and ammonia. Results indicate that concentrations of constituents associated with suspended material, such as suspended sediment, turbidity, and total phosphorus, are underestimated when samples are collected using the surface-grab technique. The median magnitude of the relative percent difference in concentration based on sampling technique was 37 percent for suspended sediment, 26 percent for turbidity, and 9.7 percent for total phosphorus samples collected at both. Acoustic techniques were also used to assist in the determination of the effectiveness of using acoustic-backscatter information for estimating the suspended-sediment concentration of the river water. Backscatter data was collected by use of an acoustic Doppler current profiler, and a Van Dorn manual sampler was simultaneously used to collect discrete water samples at 10 depths (3.5, 7.5, 11, 14, 15.5, 17.5, 19.5, 20.5, 22, and 24.5 ft below the water surface) along two vertical profiles near the center of the Saginaw River near Bay City. The Van Dorn samples were analyzed for suspended-sediment concentrations, and these data were then used to develop a relationship between acoustic-backscatter data. Acoustic-backscatter data was strongly correlated to sediment concentrations and, by using a linear regression, was able to explain 89 percent of the variability. Although this regression technique showed promise for using acoustic backscatter to estimate suspended-sediment concentration, attempts to compare suspended-sediment concentrations to the acoustic signal-to-noise ratio estimates, recorded at the fixed acoustic streamflow-gaging station near Bay City (04157061), resulted in a poor correlation.

Distribution of radionuclide and trace-elements in ground water, grasses, and surficial sediments associated with the alluvial aquifer along the Puerco River, northeastern Arizona; a reconnaissance sampling program

USGS Publications Warehouse

Webb, R.H.; Rink, G.R.; Favor, B.O.

1987-01-01

The concentrations of gross alpha radioactivity minus uranium equaled or exceeded 15 picoCuries/L (pCi/L) in five of 14 wells sampled. The concentration of radium-226 plus radium-228 exceeded the primary water quality standard of 5 pCi/L in one well. The concentration of uranium exceeded a recommended limit of 0.035 mg/L in two wells. Perennial grass and sediment samples had low concentrations of radionuclides. The concentration of trace elements in the sediment samples was not unusual. Water quality of surface water in the Puerco River at Chambers varied as a function of the suspended sediment concentration. Concentrations of total gross alpha radiation fluctuated from 12 to 11,200 pCi/L. Concentrations of total gross beta radiation fluctuated from 45 to 4,500 pCi/L. (Author 's abstract)

Perfluorinated Chemicals in Surface Waters and Sediments from Northwest Georgia, USA, and Their Bioaccumulation in Lumbriculus variegatus

EPA Science Inventory

Concentrations of perfluorinated chemicals (PFCs) were measured in surface waters and sediments from the Coosa River watershed in northwest Georgia, USA, to examine their distribution downstream of a suspected source. Samples from eight sites were analyzed using liquid chromatogr...

Chemical fractionation of Cu and Zn in stormwater, roadway dust and stormwater pond sediments

USGS Publications Warehouse

Camponelli, Kimberly M.; Lev, Steven M.; Snodgrass, Joel W.; Landa, Edward R.; Casey, Ryan E.

2010-01-01

This study evaluated the chemical fractionation of Cu and Zn from source to deposition in a stormwater system. Cu and Zn concentrations and chemical fractionation were determined for roadway dust, roadway runoff and pond sediments. Stormwater Cu and Zn concentrations were used to generate cumulative frequency distributions to characterize potential exposure to pond-dwelling organisms. Dissolved stormwater Zn exceeded USEPA acute and chronic water quality criteria in approximately 20% of storm samples and 20% of the storm duration sampled. Dissolved Cu exceeded the previously published chronic criterion in 75% of storm samples and duration and exceeded the acute criterion in 45% of samples and duration. The majority of sediment Cu (92–98%) occurred in the most recalcitrant phase, suggesting low bioavailability; Zn was substantially more available (39–62% recalcitrant). Most sediment concentrations for Cu and Zn exceeded published threshold effect concentrations and Zn often exceeded probable effect concentrations in surface sediments.

Uranium series isotopes concentration in sediments at San Marcos and Luis L. Leon reservoirs, Chihuahua, Mexico

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

Méndez-García, C.; Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx; Renteria-Villalobos, M.

2008-01-01

Spatial and temporal distribution of the radioisotopes concentrations were determined in sediments near the surface and core samples extracted from two reservoirs located in an arid region close to Chihuahua City, Mexico. At San Marcos reservoir one core was studied, while from Luis L. Leon reservoir one core from the entrance and another one close to the wall were investigated. ²³²Th-series, ²³⁸U-series, ⁴⁰K and ¹³⁷Cs activity concentrations (AC, Bq kg⁻¹) were determined by gamma spectrometry with a high purity Ge detector. ²³⁸U and ²³⁴U ACs were obtained by liquid scintillation and alpha spectrometry with a surface barrier detector. Dating ofmore » core sediments was performed applying CRS method to ²¹⁰Pb activities. Results were verified by ¹³⁷Cs AC. Resulting activity concentrations were compared among corresponding surface and core sediments. High ²³⁸U-series AC values were found in sediments from San Marcos reservoir, because this site is located close to the Victorino uranium deposit. Low AC values found in Luis L. Leon reservoir suggest that the uranium present in the source of the Sacramento – Chuviscar Rivers is not transported up to the Conchos River. Activity ratios (AR) ²³⁴U/²³⁸U and ²³⁸U/²²⁶Ra in sediments have values between 0.9–1.2, showing a behavior close to radioactive equilibrium in the entire basin. ²³²Th/²³⁸U, ²²⁸Ra/²²⁶Ra ARs are witnesses of the different geological origin of sediments from San Marcos and Luis L. Leon reservoirs.« less

The role of C:N:P stoichiometry in affecting denitrification in sediments from agricultural surface and tile-water wetlands.

PubMed

Grebliunas, Brian D; Perry, William L

2016-01-01

Nutrient stoichiometry within a wetland is affected by the surrounding land use, and may play a significant role in the removal of nitrate (NO3-N). Tile-drained, agricultural watersheds experience high seasonal inputs of NO3-N, but low phosphorus (PO4-P) and dissolved organic carbon (DOC) loads relative to surface water dominated systems. This difference may present stoichiometric conditions that limit denitrification within receiving waterways. We investigated how C:N:P ratios affected denitrification rates of sediments from tile-drained mitigation wetlands incubated for: 0, 5, 10, and 20 days. We then tested whether denitrification rates of sediments from surface-water and tile-drained wetlands responded differently to C:N ratios of 2:1 versus 4:1. Ratios of C:N:P (P < 0.05) and incubation length (P < 0.05) had a significant effect on denitrification in tile-drained wetland sediments. Carbon limitation of denitrification became evident at elevated NO3-N concentrations (20 mg L(-1)). Denitrification measured from tile water and surface water wetland sediments increased significantly (P < 0.05) at the 2:1 and 4:1 C:N treatments. The results from both experiments suggest wetland sediments provide a limiting pool of labile DOC to maintain prolonged NO3-N removal. Also, DOC limitation became more evident at elevated NO3-N concentrations (20 mg L(-1)). Irrespective of NO3-N concentrations, P did not limit denitrification rates. In addition to wetting period, residence time, and maintenance of anaerobic conditions, the availability of labile DOC is playing an important limiting role in sediment denitrification within mitigation wetlands.

n-Alkanes in sediments from the Yellow River Estuary, China: Occurrence, sources and historical sedimentary record.

PubMed

Wang, Shanshan; Liu, Guijian; Yuan, Zijiao; Da, Chunnian

2018-04-15

A total of 21 surface sediments from the Yellow River Estuary (YRE) and a sediment core from the abandoned Old Yellow River Estuary (OYRE) were analyzed for n-alkanes using gas chromatography-mass spectrometry (GC-MS). n-Alkanes in the range C 12 -C 33 and C 13 -C 34 were identified in the surface sediments and the core, respectively. The homologous series were mainly bimodal distribution pattern without odd/even predominance in the YRE and OYRE. The total n-alkanes concentrations in the surface sediments ranged from 0.356 to 0.572mg/kg, with a mean of 0.434mg/kg on dry wt. Evaluation of n-alkanes proxies indicated that the aliphatic hydrocarbons in the surface sediments were derived mainly from a petrogenic source with a relatively low contribution of submerged/floating macrophytes, terrestrial and emergent plants. The dated core covered the time period 1925-2012 and the mean sedimentation rate was ca. 0.5cm/yr. The total n-alkanes concentrations in the core ranged from 0.0394 to 0.941mg/kg, with a mean of 0.180mg/kg. The temporal evolution of n-alkanes reflected the historical input of aliphatic hydrocarbons and was consistent with local and regional anthropogenic activity. In general, the investigation on the sediment core revealed a trend of regional environmental change and the role of anthropogenic activity in environmental change. Copyright © 2017 Elsevier Inc. All rights reserved.

Distribution of the concentration of heavy metals associated with the sediment particles accumulated on road surfaces.

PubMed

Zafra, C A; Temprano, J; Tejero, I

2011-07-01

The heavy metal pollution caused by road run-off water constitutes a problem in urban areas. The metallic load associated with road sediment must be determined in order to study its impact in drainage systems and receiving waters, and to perfect the design of prevention systems. This paper presents data regarding the sediment collected on road surfaces in the city of Torrelavega (northern Spain) during a period of 65 days (132 samples). Two sample types were collected: vacuum-dried samples and those swept up following vacuuming. The sediment loading (g m(-2)), particle size distribution (63-2800 microm) and heavy metal concentrations were determined. The data showed that the concentration of heavy metals tends to increase with the reduction in the particle diameter (exponential tendency). The concentrations ofPb, Zn, Cu, Cr, Ni, Cd, Fe, Mn and Co in the size fraction <63 microm were 350, 630, 124, 57, 56, 38, 3231, 374 and 51 mg kg(-1), respectively (average traffic density: 3800 vehicles day(-1)). By increasing the residence time of the sediment, the concentration increases, whereas the ratio of the concentration between the different size fractions decreases. The concentration across the road diminishes when the distance between the roadway and the sampling siteincreases; when the distance increases, the ratio between size fractions for heavy metal concentrations increases. Finally, the main sources of heavy metals are the particles detached by braking (brake pads) and tyre wear (rubber), and are associated with particle sizes <125 microm.

Organic matter control on the distribution of arsenic in lake sediments impacted by ~65years of gold ore processing in subarctic Canada.

PubMed

Galloway, Jennifer M; Swindles, Graeme T; Jamieson, Heather E; Palmer, Michael; Parsons, Michael B; Sanei, Hamed; Macumber, Andrew L; Timothy Patterson, R; Falck, Hendrik

2018-05-01

Climate change is profoundly affecting seasonality, biological productivity, and hydrology in high northern latitudes. In sensitive subarctic environments exploitation of mineral resources led to contamination and it is not known how cumulative effects of resource extraction and climate warming will impact ecosystems. Gold mines near Yellowknife, Northwest Territories, subarctic Canada, operated from 1938 to 2004 and released >20,000t of arsenic trioxide (As 2 O 3 ) to the environment through stack emissions. This release resulted in elevated arsenic concentrations in lake surface waters and sediments relative to Canadian drinking water standards and guidelines for the protection of aquatic life. A meta-analytical approach is used to better understand controls on As distribution in lake sediments within a 30-km radius of historic mineral processing activities. Arsenic concentrations in the near-surface sediments range from 5mg·kg -1 to over 10,000mg·kg -1 (median 81mg·kg -1 ; n=105). Distance and direction from the historic roaster stack are significantly (p<0.05) related to sedimentary As concentration, with highest As concentrations in sediments within 11km and lakes located downwind. Synchrotron-based μXRF and μXRD confirm the persistence of As 2 O 3 in near surface sediments of two lakes. Labile organic matter (S1) is significantly (p<0.05) related to As and S concentrations in sediments and this relationship is greatest in lakes within 11km from the mine. These relations are interpreted to reflect labile organic matter acting as a substrate for microbial growth and mediation of authigenic precipitation of As-sulphides in lakes close to the historic mine where As concentrations are highest. Continued climate warming is expected to lead to increased biological productivity and changes in organic geochemistry of lake sediments that are likely to play an important role in the mobility and fate of As in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Numerical model of frazil ice and suspended sediment concentrations and formation of sediment laden ice in the Kara Sea

USGS Publications Warehouse

Sherwood, C.R.

2000-01-01

A one-dimensional (vertical) numerical model of currents, mixing, frazil ice concentration, and suspended sediment concentration has been developed and applied in the shallow southeastern Kara Sea. The objective of the calculations is to determine whether conditions suitable for turbid ice formation can occur during times of rapid cooling and wind- and wave-induced sediment resuspension. Although the model uses a simplistic approach to ice particles and neglects ice-sediment interactions, the results for low-stratification, shallow (∼20-m) freeze-up conditions indicate that the coconcentrations of frazil ice and suspended sediment in the water column are similar to observed concentrations of sediment in turbid ice. This suggests that wave-induced sediment resuspension is a viable mechanism for turbid ice formation, and enrichment mechanisms proposed to explain the high concentrations of sediment in turbid ice relative to sediment concentrations in underlying water may not be necessary in energetic conditions. However, salinity stratification found near the Ob' and Yenisey Rivers damps mixing between ice-laden surface water and sediment-laden bottom water and probably limits incorporation of resuspended sediment into turbid ice until prolonged or repeated wind events mix away the stratification. Sensitivity analyses indicate that shallow (≤20 m), unstratified waters with fine bottom sediment (settling speeds of ∼1 mm s−1 or less) and long open water fetches (>25 km) are ideal conditions for resuspension.

The Relationship between the Distribution of Common Carp and Their Environmental DNA in a Small Lake

PubMed Central

Eichmiller, Jessica J.; Bajer, Przemyslaw G.; Sorensen, Peter W.

2014-01-01

Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or ‘carp’), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart. PMID:25383965

The relationship between the distribution of common carp and their environmental DNA in a small lake.

PubMed

Eichmiller, Jessica J; Bajer, Przemyslaw G; Sorensen, Peter W

2014-01-01

Although environmental DNA (eDNA) has been used to infer the presence of rare aquatic species, many facets of this technique remain unresolved. In particular, the relationship between eDNA and fish distribution is not known. We examined the relationship between the distribution of fish and their eDNA (detection rate and concentration) in a lake. A quantitative PCR (qPCR) assay for a region within the cytochrome b gene of the common carp (Cyprinus carpio or 'carp'), an ubiquitous invasive fish, was developed and used to measure eDNA in Lake Staring (MN, USA), in which both the density of carp and their distribution have been closely monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by carp. In water, areas of high carp use had a higher rate of detection and concentration of eDNA, but there was no effect of fish use on sediment eDNA. The detection rate and concentration of eDNA in surface and sub-surface water were not significantly different (p≥0.5), indicating that eDNA did not accumulate in surface water. The detection rate followed the trend: high-use water > low-use water > sediment. The concentration of eDNA in sediment samples that were above the limit of detection were several orders of magnitude greater than water on a per mass basis, but a poor limit of detection led to low detection rates. The patchy distribution of eDNA in the water of our study lake suggests that the mechanisms that remove eDNA from the water column, such as decay and sedimentation, are rapid. Taken together, these results indicate that effective eDNA sampling methods should be informed by fish distribution, as eDNA concentration was shown to vary dramatically between samples taken less than 100 m apart.

Modeling radiocesium transport from a river catchment based on a physically-based distributed hydrological and sediment erosion model.

PubMed

Kinouchi, Tsuyoshi; Yoshimura, Kazuya; Omata, Teppei

2015-01-01

The accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in March 2011 resulted in the deposition of large quantities of radionuclides, such as (134)Cs and (137)Cs, over parts of eastern Japan. Since then high levels of radioactive contamination have been detected in large areas, including forests, agricultural land, and residential areas. Due to the strong adsorption capability of radiocesium to soil particles, radiocesium migrates with eroded sediments, follows the surface flow paths, and is delivered to more populated downstream regions and eventually to the Pacific Ocean. It is therefore important to understand the transport of contaminated sediments in the hydrological system and to predict changes in the spatial distribution of radiocesium concentrations by taking the land-surface processes related to sediment migration into consideration. In this study, we developed a distributed model to simulate the transport of water and contaminated sediment in a watershed hydrological system, and applied this model to a partially forested mountain catchment located in an area highly contaminated by the radioactive fallout. Observed discharge, sediment concentration, and cesium concentration measured from June 2011 until December 2012 were used for calibration of model parameters. The simulated discharge and sediment concentration both agreed well with observed values, while the cesium concentration was underestimated in the initial period following the accident. This result suggests that the leaching of radiocesium from the forest canopy, which was not considered in the model, played a significant role in its transport from the catchment. Based on the simulation results, we quantified the long-term fate of radiocesium over the study area and estimated that the effective half-life of (137)Cs deposited in the study area will be approximately 22 y due to the export of contaminated sediment by land-surface processes, and the amount of (137)Cs remaining in the catchment will be reduced to 39% of the initial total within 30 y after contamination. This study provides a perspective on the transport of suspended sediments and radiocesium in catchments with similar land use and radiocesium contamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

Alkylphenols in surface sediments of the Yellow Sea and East China Sea inner shelf: occurrence, distribution and fate.

PubMed

Duan, Xiao-yong; Li, Yan-xia; Li, Xian-guo; Zhang, Da-hai; Gao, Yi

2014-07-01

Alkylphenols (APs) have been found as ubiquitous environmental pollutants with reproductive and developmental toxicity. In this study, APs in surface sediments of the Yellow Sea (YS) and East China Sea (ECS) inner shelf were analyzed to assess influences of riverine and atmospheric inputs of pollutants on the marine environment. NP concentrations ranged from 349.5 to 1642.8 ng/g (average 890.1 ng/g) in the YS sediments and from 31.3 to 1423.7 ng/g (average 750.1 ng/g) in the ECS inner shelf sediments. NP distribution pattern was mainly controlled by the sedimentary environment. OP concentration was 0.8-9.3 ng/g (average 4.7 ng/g) in the YS sediments and 0.7-11.1 ng/g (average 5.1 ng/g) in the ECS sediments. Assessment of the influence of distances from land on OP concentrations provided evidence for the predominance of coastal riverine and/or atmospheric inputs rather than long-range transport. And the biological pump may play an important role for sequestration of OP in the nearshore area. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of sediment characteristics on the heavy metal concentration and their ecological risk level of surface sediments of Vaigai river, Tamilnadu, India.

PubMed

Paramasivam, K; Ramasamy, V; Suresh, G

2015-02-25

The distributions of the metals (Al, Fe, Mg, Cd, Cr, Cu, Ni, Pb and Zn) were measured for the surface sediments of the Vaigai river, Tamilnadu, India. These values are compared with different standard values to assess the level of toxicity of the heavy metals in the sediments. Risk indices (CF, PLI and PER) are also calculated to understand the level of toxicity of the metals. Multivariate statistical analyses (Pearson's correlation analysis, cluster analysis and factor analysis) are carried out to know the inter-relationship between sediment characteristics and the heavy metals. From this analysis, it is confirmed that the contents of clay and organic matter play an important role to raise the level of heavy metal contents as well as PLI and PER (level of toxicity). Heavy metal concentrations of the samples (after removing silt and clay fractions from bulk samples) show decrease in their concentrations and risk indices compared to the level of bulk samples. Copyright © 2014 Elsevier B.V. All rights reserved.

That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles

PubMed Central

Ricardo, Gerard F.; Jones, Ross J.; Negri, Andrew P.; Stocker, Roman

2016-01-01

Spawning synchrony represents a common reproductive strategy in sessile marine organisms and for broadcast spawning corals, buoyancy of egg-sperm bundles is critical to maximise fertilisation at the ocean surface. Here we demonstrate a novel threat to coral reproduction whereby buoyant egg-sperm bundles intercept and are “ballasted” by sediment grains on their journey to the ocean surface, preventing them from reaching the ocean surface and greatly reducing egg-sperm encounter rates. Empirical observations of this mechanism are successfully captured by a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load. When applied to 15 m deep reefs, the model predicts that 10% and 50% reductions in egg-sperm encounters occur at 35 mg L−1 and 87 mg L−1 suspended sediment concentrations, respectively, and for a 5 m deep reef a 10% reduction occurs at 106 mg L−1. These concentrations are commonly associated with sediment plumes from dredging or natural resuspension events. The potential for sediments to sink coral gametes highlights the need to carefully manage the timing of turbidity-generating human activities near reefs during spawning periods. PMID:26898352

That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles.

PubMed

Ricardo, Gerard F; Jones, Ross J; Negri, Andrew P; Stocker, Roman

2016-02-22

Spawning synchrony represents a common reproductive strategy in sessile marine organisms and for broadcast spawning corals, buoyancy of egg-sperm bundles is critical to maximise fertilisation at the ocean surface. Here we demonstrate a novel threat to coral reproduction whereby buoyant egg-sperm bundles intercept and are "ballasted" by sediment grains on their journey to the ocean surface, preventing them from reaching the ocean surface and greatly reducing egg-sperm encounter rates. Empirical observations of this mechanism are successfully captured by a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load. When applied to 15 m deep reefs, the model predicts that 10% and 50% reductions in egg-sperm encounters occur at 35 mg L(-1) and 87 mg L(-1) suspended sediment concentrations, respectively, and for a 5 m deep reef a 10% reduction occurs at 106 mg L(-1). These concentrations are commonly associated with sediment plumes from dredging or natural resuspension events. The potential for sediments to sink coral gametes highlights the need to carefully manage the timing of turbidity-generating human activities near reefs during spawning periods.

PARTICLE SEPARATION METHOD

DOEpatents

Anderson, N.G.

1963-01-29

An improved method of sedimentation is described. A series of spaced surfaces of powdered material positioned normal to the centrifugal field concentrates the larger, slower moving molecules of a liquid and hastens sedimentation. (AEC)

Antibiotics in surface water and sediments from Hanjiang River, Central China: Occurrence, behavior and risk assessment.

PubMed

Hu, Ying; Yan, Xue; Shen, Yun; Di, Mingxiao; Wang, Jun

2018-08-15

Thirteen antibiotics including sulfonamides (SAs), tetracyclines (TETs) and fluoroquinolones (FQs) were measured in Hanjiang River (HR) during two periods. The total concentrations of 13 antibiotics in surface water and sediments ranged from 3.1 to 109 ng/l and from 10 to 45 ng/g dry weight, respectively. SAs were dominant in water while the concentrations of TETs were the highest in sediments in two seasons. For their spatial distribution, total concentrations of 13 antibiotics in both matrices were significantly higher in the lower section of HR (p < 0.02, F > 5.15) due to wastewater release, agricultural activities and water transfer project. Obvious seasonal variations of sulfadiazine, sulfameter, trimethoprim and oxytetracycline in water were observed (p < 0.05, F > 4.62). Phase partition of antibiotics between water and sediments suggested a greater affinity of TETs and FQs to sediments. In addition, significantly positive relationships were found between SAs (sulfameter, sulfamethoxazole and trimethoprim) and sediment TOC (p < 0.05). Risk assessment indicated that the hazard quotients of antibiotics were higher in the sediment than those in the water. Moreover, antibiotic mixtures posed higher ecological risks to aquatic organisms. Copyright © 2018 Elsevier Inc. All rights reserved.

Interaction of Strontium-90 in Sediment and Porewater in a Stream Near Chernobyl

NASA Astrophysics Data System (ADS)

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

2002-12-01

We investigated the interaction of 90Sr in sediments and pore waters of wetlands and stream hyporheic zones at a stream near Chernobyl. A non-dimensional activity ratio was formulated, the ratio of 90Sr in the pore waters compared with exchangeable 90Sr in the sediment on a volume basis. The average activity ratio for the wetland and channel sediments was 0.028 +/- 0.005. The activity ratio decreased when the sediment and porewaters were not in equilibrium. The change in the activity ratio was documented during two observational periods in a wetland: initially during a time when groundwater was discharging to the wetland (snowmelt, 2000) and subsequently at a time of near-stagnant groundwater flow (late fall in 2001 after a dry three month period). In both the discharge and stagnant periods, the exchangeable 90Sr concentration in sediment increased with depth by a factor of five to a peak concentration at 10 cm. In contrast, the 90Sr concentration in porewater differed significantly in the two observational periods. During the groundwater discharge period, the porewater concentration was relatively constant over the 30 cm depth of observation (120 +/-12 Bq/L) and surface water concentrations were similar. During the near-stagnant period, the porewater concentration increased with depth from 20+/-2 Bq/L in surface waters to 400 +/-40 Bq/L at a depth of 10 cm. We hypothesize that during discharge periods, the porewaters in the wetland represent the 90Sr concentration of advecting groundwater while during stagnant periods, the porewaters represent the concentration of 90Sr in equilibrium with the sediment. This proposed explanation is supported using PHREEQC in a dual porosity mode. Using independent estimates of the model parameters, the concentration profiles could be successfully matched with the assumption of advective transport during the discharge period and diffusive transport of 90Sr during near-stagnant conditions.

Sediment characteristics of the Yellowstone River in the vicinity of a proposed bypass chute near Glendive, Montana, 2011

USGS Publications Warehouse

Hanson, Brent R.

2012-01-01

In 2011, sediment data were collected by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers on the Yellowstone River at the location of a proposed bypass chute. The sediment data were collected to provide an understanding of the sediment dynamics of the given reach of the Yellowstone River. Suspended-sediment concentrations collected at the three sites generally decreased with decreasing streamflow. In general, the highest suspendedsediment concentrations were found near the channel bed and towards the center of the channel with lower suspendedsediment concentrations near the channel banks and water surface. Suspended sediment was the primary component of the total sediment load for all three sampling locations on the Yellowstone River and contributed at least 98 percent of the total sediment load at each of the three sites. The amount of bedload measured at the three sites was a smaller load in comparison with the suspended-sediment load.

Methylmercury bioaccumulation in an urban estuary: Delaware River USA.

PubMed

Buckman, Kate; Taylor, Vivien; Broadley, Hannah; Hocking, Daniel; Balcom, Prentiss; Mason, Rob; Nislow, Keith; Chen, Celia

2017-09-01

Spatial variation in mercury (Hg) and methylmercury (MeHg) bioaccumulation in urban coastal watersheds reflects complex interactions between Hg sources, land use, and environmental gradients. We examined MeHg concentrations in fauna from the Delaware River estuary, and related these measurements to environmental parameters and human impacts on the waterway. The sampling sites followed a north to south gradient of increasing salinity, decreasing urban influence, and increasing marsh cover. Although mean total Hg in surface sediments (top 4cm) peaked in the urban estuarine turbidity maximum and generally decreased downstream, surface sediment MeHg concentrations showed no spatial patterns consistent with the examined environmental gradients, indicating urban influence on Hg loading to the sediment but not subsequent methylation. Surface water particulate MeHg concentration showed a positive correlation with marsh cover whereas dissolved MeHg concentrations were slightly elevated in the estuarine turbidity maximum region. Spatial patterns of MeHg bioaccumulation in resident fauna varied across taxa. Small fish showed increased MeHg concentrations in the more urban/industrial sites upstream, with concentrations generally decreasing farther downstream. Invertebrates either showed no clear spatial patterns in MeHg concentrations (blue crabs, fiddler crabs) or increasing concentrations further downstream (grass shrimp). Best-supported linear mixed models relating tissue concentration to environmental variables reflected these complex patterns, with species specific model results dominated by random site effects with a combination of particulate MeHg and landscape variables influencing bioaccumulation in some species. The data strengthen accumulating evidence that bioaccumulation in estuaries can be decoupled from sediment MeHg concentration, and that drivers of MeHg production and fate may vary within a small region.

Impacts of mangrove density on surface sediment accretion, belowground biomass and biogeochemistry in Puttalam Lagoon, Sri Lanka

USGS Publications Warehouse

Phillips, D.H.; Kumara, M.P.; Jayatissa, L.P.; Krauss, Ken W.; Huxham, M.

2017-01-01

Understanding the effects of seedling density on sediment accretion, biogeochemistry and belowground biomass in mangrove systems can help explain ecological functioning and inform appropriate planting densities during restoration or climate change mitigation programs. The objectives of this study were to examine: 1) impacts of mangrove seedling density on surface sediment accretion, texture, belowground biomass and biogeochemistry, and 2) origins of the carbon (C) supplied to the mangroves in Palakuda, Puttalam Lagoon, Sri Lanka. Rhizophora mucronata propagules were planted at densities of 6.96, 3.26, 1.93 and 0.95 seedlings m−2along with an unplanted control (0 seedlings m−2). The highest seedling density generally had higher sediment accretion rates, finer sediments, higher belowground biomass, greatest number of fine roots and highest concentrations of C and nitrogen (N) (and the lowest C/N ratio). Sediment accretion rates, belowground biomass (over 1370 days), and C and N concentrations differed significantly between seedling densities. Fine roots were significantly greater compared to medium and coarse roots across all plantation densities. Sulphur and carbon stable isotopes did not vary significantly between different density treatments. Isotope signatures suggest surface sediment C (to a depth of 1 cm) is not derived predominantly from the trees, but from seagrass adjacent to the site.

Biogeochemical Processes Related to Metal Removal and Toxicity Reduction in the H-02 Constructed Wetland, Savannah River Site

NASA Astrophysics Data System (ADS)

Burgess, E. A.; Mills, G. L.; Harmon, M.; Samarkin, V.

2011-12-01

The H-02 wetland system was designed to treat building process water and storm water runoff from multiple sources associated with the Tritium Facility at the DOE-Savannah River Site, Aiken, SC. The wetland construction included the addition of gypsum (calcium sulfate) to foster a sulfate-reducing bacterial population. Conceptually, the wetland functions as follows: ? Cu and Zn initially bind to both dissolved and particulate organic detritus within the wetland. ? A portion of this organic matter is subsequently deposited into the surface sediments within the wetland. ? The fraction of Cu and Zn that is discharged in the wetland effluent is organically complexed, less bioavailable, and consequently, less toxic. ? The Cu and Zn deposited in the surface sediments are eventually sequestered into insoluble sulfide minerals in the wetland. Development of the H-02 system has been closely monitored; sampling began in August 2007, shortly after its construction. This monitoring has included the measurement of water quality parameters, Cu and Zn concentrations in surface water and sediments, as well as, characterization of the prokaryotic (e.g., bacterial) component of wetland biogeochemical processes. Since the beginning of the study, the mean influent Cu concentration was 31.5±12.1 ppb and the mean effluent concentration was 11.9±7.3 ppb, corresponding to an average Cu removal of 64%. Zn concentrations were more variable, averaging 39.2±13.8 ppb in the influent and 25.7±21.3 ppb in the effluent. Average Zn removal was 52%. The wetland also ameliorated high pH values associated with influent water to values similar to those measured at reference sites. Seasonal variations in DOC concentration corresponded to seasonal variations in Cu and Zn removal efficiency. The concentration of Cu and Zn in the surface layer of the sediments has increased over the lifetime of the wetland and, like removal efficiency, demonstrated seasonal variation. Within its first year, the H-02 wetland showed biomarkers for sulfate-reducing bacteria. Sulfate-reduction and methane-oxidation rates in the sediments were determined using radiotracer techniques. Sulfate-reduction was detected in all depths of sediment cores, even in surface detritus layers. Gas measurements from H-02 sediments demonstrated that methane is available to support a methane oxidizing community, and active methane-oxidation was detected in the sediments and overlying water. Our results demonstrate that the H-02 wetlands are functioning successfully to remove Cu and Zn from influent waters. The continued success and long-term sustainability of the functioning H-02 system is predicated on maintaining in situ biogeochemistry. However, the relative importance of various biogeochemical cycles remains unclear. For example, the Cu and Zn deposited in the sediments are associated with organic detritus at the sediment surface; the extent and rate at which the metals will redistribute to more recalcitrant sulfide mineral phases remain to be determined. Thus, the H-02 wetland system is a valuable resource not only for metal removal at SRS, but also can further enhance the understanding of wetland function within the scientific and regulatory communities.

Spatial and temporal assessment of mercury and organic matter in thermokarst affected lakes of the Mackenzie Delta uplands, NT, Canada.

PubMed

Deison, Ramin; Smol, John P; Kokelj, Steve V; Pisaric, Michael F J; Kimpe, Linda E; Poulain, Alexandre J; Sanei, Hamed; Thienpont, Joshua R; Blais, Jules M

2012-08-21

We examined dated sediment cores from 14 thermokarst affected lakes in the Mackenzie Delta uplands, NT, Arctic Canada, using a case-control analysis to determine how retrogressive thaw slump development from degrading permafrost affected the delivery of mercury (Hg) and organic carbon (OC) to lakes. We show that sediments from the lakes with retrogressive thaw slump development on their shorelines (slump-affected lakes) had higher sedimentation rates and lower total Hg (THg), methyl mercury (MeHg), and lower organic carbon concentrations compared to lakes where thaw slumps were absent (reference lakes). There was no difference in focus-corrected Hg flux to sediments between reference lakes and slump-affected lakes, indicating that the lower sediment Hg concentration in slump-affected lakes was due to dilution by rapid inorganic sedimentation in the slump-affected lakes. Sedimentation rates were inversely correlated with THg concentrations in sediments among the 14 lakes considered, and explained 68% of the variance in THg concentration in surface sediment, further supporting the dilution hypothesis. We observed higher S2 (algal-derived carbon) and particulate organic carbon (POC) concentrations in sediment profiles from reference lakes than in slump lakes, likely because of dilution by inorganic siliciclastic matter in cores from slump-affected lakes. We conclude that retrogressive thaw slump development increases inorganic sedimentation in lakes, and decreases concentrations of organic carbon and associated Hg and MeHg in sediments.

Petroleum hydrocarbons in a water-sediment system from Yellow River estuary and adjacent coastal area, China: Distribution pattern, risk assessment and sources.

PubMed

Wang, Min; Wang, Chuanyuan; Li, Yuanwei

2017-09-15

Aliphatic hydrocarbons (AHs), biomarker and polycyclic aromatic hydrocarbons (PAHs) concentrations of surface water and sediment samples collected from Yellow River Estuary and adjacent coastal area in China were measured to determine their spatial distributions, analyze their sources and evaluate the ecological risk of PAHs in the water-sediment system. The spatial distributions of n-alkane in sediments are mainly controlled by the mixing inputs of terrigenous and marine components. In comparison with AHs, the total concentrations of Σ16PAHs in surface sediments from a transect of the offshore area were noticeably higher than that of the riverine and estuary areas. Additionally, the AHs and total PAHs concentrations all indicated an overall pattern of a seaward decrease. The PAHs concentrations during the dry season (mainly in the form of dissolved phase) were higher than that of PAHs (mainly dissolved phase and particulate phase form) in the flooding season. In comparison with global concentration levels of PAHs, the level of PAHs in suspended particulate matter and sediments from the Yellow River Estuary was lower than those from other countries, while the concentration of PAHs in the dissolved phase were in the middle range. Petroleum contamination, mainly from oil exploration and discharge of pollutants from rivers, was the main source of n-alkanes. The PAHs in the river were mostly of petrogenic origin, while those in the estuarial and marine areas originated mainly from pyrogenic sources. The results of the toxicology assessment suggested that the PAHs in sediments from Yellow River Estuary and adjacent coastal area exhibited a low potential eco-toxicological contamination level. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recent paleorecords document rising mercury contamination in Lake Tanganyika

USGS Publications Warehouse

Conaway, C.H.; Swarzenski, P.W.; Cohen, A.S.

2012-01-01

Recent Lake Tanganyika Hg deposition records were derived using 14C and excess 210Pb geochronometers in sediment cores collected from two contrasting depositional environments: the Kalya Platform, located mid-lake and more removed from watershed impacts, and the Nyasanga/Kahama River delta region, located close to the lake's shoreline north of Kigoma. At the Kalya Platform area, pre-industrial Hg concentrations are 23??0.2ng/g, increasing to 74ng/g in modern surface sediment, and the Hg accumulation rate has increased from 1.0 to 7.2??g/m 2/a from pre-industrial to present, which overall represents a 6-fold increase in Hg concentration and accumulation. At the Nyasanga/Kahama delta region, pre-industrial Hg concentrations are 20??3ng/g, increasing to 46ng/g in surface sediment. Mercury accumulation rate has increased from 30 to 70??g/m 2/a at this site, representing a 2-3-fold increase in Hg concentration and accumulation. There is a lack of correlation between charcoal abundance and Hg accumulation rate in the sediment cores, demonstrating that local biomass burning has little relationship with the observed Hg concentration or Hg accumulation rates. Examined using a sediment focusing-corrected mass accumulation rate approach, the cores have similar anthropogenic atmospheric Hg deposition profiles, suggesting that after accounting for background sediment concentrations the source of accumulating Hg is predominantly atmospheric in origin. In summary, the data document an increase of Hg flux to the Lake Tanganyika ecosystem that is consistent with increasing watershed sediment delivery with background-level Hg contamination, and regional as well as global increases in atmospheric Hg deposition. ?? 2011.

Temporal variation of aerobic methane oxidation over a tidal cycle in a wetland of northern Taiwan.

NASA Astrophysics Data System (ADS)

Lee, T. Y.; Wang, P. L.; Lin, L. H.

2017-12-01

Aerobic methanotrophy plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Two field campaigns were carried out in December of 2016 and March of 2017. Fluxes of methane emission, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive the kinetic parameters for aerobic methanotrophy. Our results demonstrated temporal changes of the surface methane concentration and the methane emission flux during a tidal cycle, while the oxygen flux into the sediment was kept at a similar magnitude. The methane flux was low when the surface was exposed for both shortest and longest periods of time. The potential aerobic methane oxidation rate was high for sample collected from the surface sediments exposed the longest. No correlation could be found between the potential aerobic methane oxidation rate and either the oxygen downward flux or methane emission flux. The decoupled relationships between these observed rates and fluxes suggest that, rather than aerobic methanotrophy, heterotrophic respirations exert a profound control on oxygen flux, and the methane emission is not only been affected by methane consumption but also methane production at depths. The maximum potential rate and the half saturation concentration determined from the batch incubations were high for the surface sediments collected in low tide, suggesting that aerobic methanotrophy could be modulated to reach peak activity once the influence of saline water is reduced to a low level.

Surface Water Geochemistry, Sediment, and Field Parameters During Snowmelt and Monsoons in the New Mexico Reach of the Animas and San Juan Rivers, 2016

NASA Astrophysics Data System (ADS)

Blake, J.; Brown, J. E.; Mast, A.

2017-12-01

Following the release of three million gallons of metals laden surface water from the Gold King Mine in August 2015, surface-water samples were collected in the New Mexico reach of the Animas and San Juan Rivers during 2016 snowmelt and in the Animas River during three 2016 monsoonal storms. These samples were evaluated for dissolved (<0.45 µm) and total (unfiltered) concentrations of trace elements including aluminum, arsenic, iron, lead, and manganese. Dissolved concentrations of aluminum, iron, and lead account for between 0.70 % and 14% of their total metal concentrations; the manganese and arsenic range of dissolved concentrations compared to total concentrations ranges from 1.2%-75%. Concentrations of total aluminum, arsenic, iron, lead, manganese increase during the rising limb of all hydrographs, suggesting a relationship with sediment concentrations, which also increase with increasing streamflow. Aluminum and iron have the highest total concentrations, 63,400 µg/L and 82,500 µg/L, respectively. Lead and arsenic total concentrations range from 0.67 to 65.5 µg/L and 0.6 to 17 µg/L, respectively. Metals such as lead and arsenic are known to adsorb to iron and aluminum particulates. During snowmelt, the relations of total aluminum and iron to total lead and arsenic are positive and linear, while during monsoonal events, the relations are polynomial. These relations may be due to the source of metals during the specific hydrologic event. Relations between discrete water quality data and continuously monitored field parameters such as turbidity and specific conductance can provide insight to changes in concentrations of the river on a finer time scale. Regression models developed for selected sites on the Animas and San Juan Rivers show that flow, turbidity and specific conductance may be useful in understanding the relationship between total metal concentrations and real-time parameters. Surrogates for suspended sediment such as hydroacoustic may also be useful, and potentially the best option in this system, for monitoring the concentration of metals in surface water. Further evaluation of the chemistry of the watershed soils and bedrock, the streambed sediments, and suspended sediments will improve understanding of the geochemical processes in the Animas and San Juan Rivers.

Identification of Marbon in the Indiana Harbor and Ship Canal.

PubMed

Guo, Jiehong; Venier, Marta; Romanak, Kevin; Westenbroek, Stephen; Hites, Ronald A

2016-12-20

Marbon is isomeric with Dechlorane Plus (DP). Both are produced by the Diels-Alder condensation of hexachlorocyclopentadiene with cyclic dienes, and both have elemental compositions of C 18 H 12 Cl 12 . Dechlorane Plus is commonly found in the environment throughout the world, but Marbon has, so far, only been detected at low levels in one sediment core collected near the mouth of the Niagara River in Lake Ontario. Here we report on the concentrations of Marbon and anti-DP in 59 water samples from five Lake Michigan tributaries [the Grand, Kalamazoo, St. Joseph, and Lower Fox Rivers, and the Indiana Harbor and Ship Canal (IHSC)], 10 surface sediment samples from the IHSC, and 2 surface sediment samples from the Chicago Sanitary and Ship Canal. Three Marbon diastereomers were detected in the water and sediment samples from the IHSC, which is far from the location of its previous detection in Lake Ontario. The sum of the concentrations of the three Marbons was greater in the water from the IHSC (N = 11, median =150 pg/L) compared to those in water from the other four tributaries (N = 11-13, medians =0.9-2.0 pg/L). Marbon concentrations in sediment samples from the IHSC were up to 450 ng/g dry weight. Anti-DP was also measured for comparison. Its concentrations were not significantly different among the water samples, but its sediment concentrations in the IHSC were significantly correlated with those of Marbon. The source of Marbon contamination in the IHSC is not clear.

PBDD/Fs in surface sediments from the East River, China.

PubMed

Ren, M; Peng, P A; Chen, D Y; Chen, P; Zhou, L

2009-09-01

The contamination status of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) was preliminarily investigated in surface sediments from the East River. The concentrations of eight 2,3,7,8-substituted tetra- to hexa- PBDD/Fs were found to be in the range of 0.32-110 (mean 13) pg g(-1) and the corresponding TEQ concentrations were 0.087-18 (mean 2) pg I-TEQ g(-1). All sediments were characterized by the dominant PBDFs. 2,3,4,7,8-PeBDF was the most important TEQ contributor, accounting for 47%-77% of the total I-TEQ of PBDD/Fs. PCDD/Fs contributed dominantly to the total TEQs of PCDD/Fs, PBDD/Fs and dioxin-like PCBs in most samples except of the sediment from the Shima River. The higher PBDD/F concentrations in the Shima River may be attributed to the use of BFRs in the electrical and electronics industries, which posed a potential risk of dioxins on ecological system.

Organic carbon accumulation and preservation in surface sediments on the Peru margin

USGS Publications Warehouse

Arthur, M.A.; Dean, W.E.; Laarkamp, K.

1998-01-01

Concentrations and characteristics of organic matter in surface sediments deposited under an intense oxygen-minimum zone on the Peru margin were studied in samples from deck-deployed box cores and push cores acquired by submersible on two transects spanning depths of 75 to 1000 m at 12??and 13.5??S. The source of organic matter to the seafloor in these areas is almost entirely marine material as confirmed by the narrow range of ??13C of organic carbon obtained in the present study (-20.3 to -21.6???; PDB) and the lack of any relationship between pyrolysis hydrogen index and carbon isotope composition. Organic carbon contents are highest (up to 16%) on the slope at depths between 75 and 350 m in sediments deposited under intermediate water masses with low dissolved oxygen concentrations (< 5 ??mol/kg). Even at these low concentrations of dissolved oxygen, however, the surface sediments that were recovered from these depths are dominantly unlaminated. Strong currents (up to 30 cm/s) associated with the poleward-flowing Peru Undercurrent were measured at depths between 160 and 300 m on both transects. The seafloor in this range of water depths is characterized by bedforms stabilized by bacterial mats, extensive authigenic mineral crusts, and (or) thick organic flocs. Constant advection of dissolved oxygen, although in low concentrations, active resuspension of surficial organic matter, activity of organisms, and transport of fine-grained sediment to and from more oxygenated zones all contribute to greater degradation and poorer initial preservation of organic matter than might be expected under oxygen-deficient conditions. Dissolved-oxygen concentrations ultimately may be the dominant affect on organic matter characteristics, but reworking of fine-grained sediment and organic matter by strong bottom currents and redeposition on the seafloor in areas of lower energy also exert important controls on organic carbon concentration and degree of oxidation in this region.

Incorporating both physical and kinetic limitations in quantifying dissolved oxygen flux to aquatic sediments

USGS Publications Warehouse

O'Connor, B.L.; Hondzo, Miki; Harvey, J.W.

2009-01-01

Traditionally, dissolved oxygen (DO) fluxes have been calculated using the thin-film theory with DO microstructure data in systems characterized by fine sediments and low velocities. However, recent experimental evidence of fluctuating DO concentrations near the sediment-water interface suggests that turbulence and coherent motions control the mass transfer, and the surface renewal theory gives a more mechanistic model for quantifying fluxes. Both models involve quantifying the mass transfer coefficient (k) and the relevant concentration difference (??C). This study compared several empirical models for quantifying k based on both thin-film and surface renewal theories, as well as presents a new method for quantifying ??C (dynamic approach) that is consistent with the observed DO concentration fluctuations near the interface. Data were used from a series of flume experiments that includes both physical and kinetic uptake limitations of the flux. Results indicated that methods for quantifying k and ??C using the surface renewal theory better estimated the DO flux across a range of fluid-flow conditions. ?? 2009 ASCE.

Mercury speciation and microbial transformations in mine wastes, stream sediments, and surface waters at the Almaden Mining District, Spain

USGS Publications Warehouse

Gray, John E.; Hines, Mark E.; Higueras, Pablo L.; Adatto, Isaac; Lasorsa, Brenda K.

2004-01-01

Speciation of Hg and conversion to methyl-Hg were evaluated in mine wastes, sediments, and water collected from the Almade??n District, Spain, the world's largest Hg producing region. Our data for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from the Almade??n area. Concentrations of Hg and methyl-Hg in mine waste, sediment, and water from Almade??n are among the highest found at Hg mines worldwide. Mine wastes from Almade??n contain highly elevated Hg concentrations, ranging from 160 to 34 000 ??g/g, and methyl-Hg varies from <0.20 to 3100 ng/g. Isotopic tracer methods indicate that mine wastes at one site (Almadenejos) exhibit unusually high rates of Hg-methylation, which correspond with mine wastes containing the highest methyl-Hg concentrations. Streamwater collected near the Almade??n mine is also contaminated, containing Hg as high as 13 000 ng/L and methyl-Hg as high as 30 ng/L; corresponding stream sediments contain Hg concentrations as high as 2300 ??g/g and methyl-Hg concentrations as high as 82 ng/g. Several streamwaters contain Hg concentrations in excess of the 1000 ng/L World Health Organization (WHO) drinking water standard. Methyl-Hg formation and degradation was rapid in mines wastes and stream sediments demonstrating the dynamic nature of Hg cycling. These data indicate substantial downstream transport of Hg from the Almade??n mine and significant conversion to methyl-Hg in the surface environment.

An assessment of butyltins and metals in sediment cores from the St. Thomas East End Reserves, USVI.

PubMed

Hartwell, S Ian; Apeti, Dennis A; Mason, Andrew L; Pait, Anthony S

2016-11-01

Tributyltin (TBT) concentrations near a marina complex in Benner Bay on St. Thomas, US Virgin Islands, were elevated relative to other areas in a larger study of the southeastern shore of the island. At the request of the USVI Coastal Zone Management Program, sediment cores and surface sediment samples were collected to better define the extent and history of TBT deposition in the vicinity of Benner Bay. The sediment cores were sectioned into 2-cm intervals and dated with 210 Pb and 137 Cs. The core sections and the surface samples were analyzed for butyltins and 16 elements. Deposition rates varied from 0.07-5.0 mm/year, and were highest in the marina complex. Core ages ranged from 54 to 200 years. The bottoms of the cores contained shell hash, but the top layers all consisted of much finer material. Surface concentrations of TBT exceeded 2000 ng Sn/g (dry weight) at two locations. At a depth of 8 cm TBT exceeded 8800 ng Sn/g in the marina complex sediment. Based on the ratio of tributyltin to total butyltins, it appears that the marina sediments are the source of contamination of the surrounding area. There is evidence that vessels from neighboring islands may also be a source of fresh TBT. Copper concentrations increase over time up to the present. Gradients of virtually all metals and metalloids extended away from the marina complex. NOAA sediment quality guidelines were exceeded for As, Pb, Cu, Zn, and Hg.

Chromium distribution in an Amazonian river exposed to tannery effluent.

PubMed

de Sousa, Eduardo Araujo; Luz, Cleber Calado; de Carvalho, Dario Pires; Dorea, Caetano Chang; de Holanda, Igor Bruno Barbosa; Manzatto, Ângelo Gilberto; Bastos, Wanderley Rodrigues

2016-11-01

This study aims to evaluate the Cr concentrations in surface water, suspended particles, and bottom sediments exposed to tannery effluent releases in the Candeias River. Cr concentrations were compared in relation to environmental thresholds imposed by United States Environmental Protection Agency (USEPA) and the Brazilian Environmental Council (CONAMA), and the geoaccumulation index (Igeo) was calculated in bottom sediment. Samples were collected in flood and dry seasons. Cr extraction was done by an acid extraction and quantified by flame atomic absorption spectrometry. Most samples were found to be below the environmental thresholds imposed by CONAMA and USEPA, except in the one from the discharge zone sampled during the dry season, showing values 1.5 and 6.1 higher than CONAMA in water and bottom sediment, respectively. Cr concentrations were significantly higher (P < 0.001) in suspended particles during dry season than flood season. Surface water and bottom sediment did not show significant differences between the seasons. The Igeo revealed an enrichment of Cr in bottom sediments after discharge zone, indicating that the effluent may be contributing to metal accumulation in the sediment. Apparently, the Candeias River shows a wash behavior on the river bottom, leaching the accumulated metal deposited on the riverbed to other areas during the flood pulses, which decreases Cr concentration in the discharge zone during dry seasons. Thus, this behavior can promote Cr dispersion to unpolluted areas.

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.

Fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp in Hong Kong following an oil spill.

PubMed

Ke, L; Wong, Teresa W Y; Wong, Y S; Tam, Nora F Y

2002-01-01

The fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp (Yi O) in Hong Kong after an oil spill accident was investigated. The concentrations and profiles of PAHs in surface sediments collected from five quadrats (each of 10 m x 10 m) covering different degrees of oil contamination and the most contaminated mangrove leaves were examined in December 2000 (30 days after the accident) and March 2001 (126 days later). The concentrations of total PAHs in surface sediments ranged from 138 to 2,135 ng g(-1), and PAHs concentrations decreased with time. In the most contaminated sediments, total PAHs dropped from 2,135 (30 days) to 1,196 ng g(-1) (120 days), and the decrease was smaller in less contaminated sediments. The percentage reduction in sediment PAHs over three months (44%) was less significant than that in contaminated leaves (85%), indicating PAH in or on leaves disappeared more rapidly. The PAH profiles were very similar in sediments collected from quadrats Q1 and Q2 with benzo[a]anthracene and pyrene being the most abundant PAH compounds, but were different in the other three quadrats. The proportion of the light molecular weight PAHs to total PAHs increased after three months, especially phenanthrene. Results suggest that physical and photo-chemical weathering (tidal washing and photo-oxidation) of crude oil in surface sediments and on plant leaves were important processes in the first few months after the oil spill. The PAH contamination in Yi O swamp came from both petrogenic and pyrolytic sources. The petrogenic characteristic in the most contaminated sediment was confirmed with high values of phenanthrene to anthracene ratio (>10) and low values of fluoranthene to pyrene ratio (0.3-0.4).

Annual variability and regulation of methane and sulfate fluxes in Baltic Sea estuarine sediments

NASA Astrophysics Data System (ADS)

Sawicka, Joanna E.; Brüchert, Volker

2017-01-01

Marine methane emissions originate largely from near-shore coastal systems, but emission estimates are often not based on temporally well-resolved data or sufficient understanding of the variability of methane consumption and production processes in the underlying sediment. The objectives of our investigation were to explore the effects of seasonal temperature, changes in benthic oxygen concentration, and historical eutrophication on sediment methane concentrations and benthic fluxes at two type localities for open-water coastal versus eutrophic, estuarine sediment in the Baltic Sea. Benthic fluxes of methane and oxygen and sediment pore-water concentrations of dissolved sulfate, methane, and 35S-sulfate reduction rates were obtained over a 12-month period from April 2012 to April 2013. Benthic methane fluxes varied by factors of 5 and 12 at the offshore coastal site and the eutrophic estuarine station, respectively, ranging from 0.1 mmol m-2 d-1 in winter at an open coastal site to 2.6 mmol m-2 d-1 in late summer in the inner eutrophic estuary. Total oxygen uptake (TOU) and 35S-sulfate reduction rates (SRRs) correlated with methane fluxes showing low rates in the winter and high rates in the summer. The highest pore-water methane concentrations also varied by factors of 6 and 10 over the sampling period with the lowest values in the winter and highest values in late summer-early autumn. The highest pore-water methane concentrations were 5.7 mM a few centimeters below the sediment surface, but they never exceeded the in situ saturation concentration. Of the total sulfate reduction, 21-24 % was coupled to anaerobic methane oxidation, lowering methane concentrations below the sediment surface far below the saturation concentration. The data imply that bubble emission likely plays no or only a minor role in methane emissions in these sediments. The changes in pore-water methane concentrations over the observation period were too large to be explained by temporal changes in methane formation and methane oxidation rates due to temperature alone. Additional factors such as regional and local hydrostatic pressure changes and coastal submarine groundwater flow may also affect the vertical and lateral transport of methane.

Investigation of Sediment Pathways and Concealed Sedimentological Features in Hidden River Cave, Kentucky

NASA Astrophysics Data System (ADS)

Feist, S.; Maclachlan, J. C.; Reinhardt, E. G.; McNeill-Jewer, C.; Eyles, C.

2016-12-01

Hidden River Cave is part of a cave system hydrogeologically related to Mammoth Cave in Kentucky and is a multi-level active cave system with 25km of mapped passages. Upper levels experience flow during flood events and lower levels have continuously flowing water. Improper industrial and domestic waste disposal and poor understanding of local hydrogeology lead to contamination of Hidden River Cave in the early 1940s. Previously used for hydroelectric power generation and as a source of potable water the cave was closed to the public for almost 50 years. A new sewage treatment plant and remediation efforts since 1989 have improved the cave system's health. This project focuses on sedimentological studies in the Hidden River Cave system. Water and sediment transport in the cave are being investigated using sediment cores, surface sediment samples and water level data. An Itrax core scanner is used to analyze sediment cores for elemental concentrations, magnetic susceptibility, radiography, and high resolution photography. Horizons of metal concentrations in the core allow correlation of sedimentation events in the cave system. Thecamoebian (testate amoebae) microfossils identified in surface samples allow for further constraint of sediment sources, sedimentation rates, and paleoclimatic analysis. Dive recorders monitor water levels, providing data to further understand the movement of sediment through the cave system. A general time constraint on the sediment's age is based on the presence of microplastic in the surface samples and sediment cores, and data from radiocarbon and lead-210 dating. The integration of various sedimentological data allows for better understanding of sedimentation processes and their record of paleoenvironmental change in the cave system. Sediment studies and methodologies from this project can be applied to other karst systems, and have important applications for communities living on karst landscapes and their water management policies.

Trace metals in sediments of two estuarine lagoons from Puerto Rico.

PubMed

Acevedo-Figueroa, D; Jiménez, B D; Rodríguez-Sierra, C J

2006-05-01

Concentrations of As, Cd, Cu, Fe, Hg, Pb and Zn were evaluated in surface sediments of two estuaries from Puerto Rico, known as San José Lagoon (SJL) and Joyuda Lagoon. Significantly higher concentrations in microg/g dw of Cd (1.8 vs. 0.1), Cu (105 vs. 22), Hg (1.9 vs. 0.17), Pb (219 vs. 8), and Zn (531 vs. 52) were found in sediment samples from SJL when compared to Joyuda Lagoon. Average concentrations of Hg, Pb, and Zn in some sediment samples from SJL were above the effect range median (ERM) that predict toxic effects to aquatic organisms. Enrichments factors using Fe as a normalizer, and correlation matrices showed that metal pollution in SJL was the product of anthropogenic sources, while the metal content in Joyuda Lagoon was of natural origins. Sediment metal concentrations found in SJL were comparable to aquatic systems classified as contaminated from other regions of the world.

On the use of the partitioning approach to derive Environmental Quality Standards (EQS) for persistent organic pollutants (POPs) in sediments: a review of existing data.

PubMed

Dueri, Sibylle; Castro-Jiménez, Javier; Comenges, José-Manuel Zaldívar

2008-09-15

A review of experimental data has been performed to study the relationships between the concentration in water, pore water and sediments for different families of organic contaminants. The objective was to determine whether it is possible to set EQS for sediments from EQS defined for surface waters in the Daughter Directive of the European Parliament (COM (2006) 397). The analysis of experimental data showed that even though in some specific cases there is a coupling between water column and sediments, this coupling is rather the exception. Therefore it is not recommendable to use water column data to assess the chemical quality status of sediments and it is necessary to measure in both media. At the moment EQS have been defined for the water column and will assess only the compliance with good chemical status of surface waters. Since the sediment toxicity depends on the dissolved pore water concentration, the EQS developed for water could be applied to pore water (interstitial water); hence, there would be no need of developing another set of EQS. The partitioning approach has been proposed as a solution to calculate sediment EQS from water EQS, but the partitioning coefficient strongly depends on sediment characteristics and its use introduces an important uncertainty in the definition of sediment EQS. Therefore, the direct measurement of pore water concentration is regarded as a better option.

[Effects of Perfluoroalkyl Substances on the Microbial Community Structure in Surface Sediments of Typical River, China].

PubMed

Sun, Ya-jun; Wang, Tie-yu; Peng, Xia-wei; Wang, Pei

2015-07-01

In order to reveal the relationship between Perfluoroalkyl substances (PFASs) contamination and the bacterial community composition, surface sediment samples were collected along the Xiaoqing River in Shandong Province in April and July 2014 (XQ1-XQ10), where many PFASs manufacturers were located. PFASs were quantified by HPLC/MS-MS, related environmental factors affecting the microbial community structure were measured, and the microbial community structure in surface sediments was measured by the second-generation sequencing technology Illumina MiSeq. The results not only revealed the degree of PFASs pollution in the sediments of Xiaoqing River, but also illustrated the relationship between PFASs pollution and the microbial community structure. Among the twelve kinds of PFASs detected in this study, PFOA was the predominant compound, and the highest PFOA concentrations were detected in the sample of XQ5 (April: 456. 2 ng. g-1; July: 748.7 ng . g-1) located at the downstream of Xiaoqing River with many fluoropolymer producing facilities. PFOA contamination was the main factor affecting the microbial community structure in April, accordingly community richness and evenness were significantly negatively correlated with PFOA levels. The abundance of Thiobacillus increased with the increasing PFOA concentration in the sediment PFOA. This suggested that Thiobacillus was sensitive to PFOA pollution and might be the potential indicator to reveal the degree of PFOA pollution in sediment. When the concentrations of PFOA were below 100 ng . g-1, no significant effects on the microbial community structure were observed.

Trace element, semivolatile organic, and chlorinated organic compound concentrations in bed sediments of selected streams at Fort Gordon, Georgia, February-April 2010

USGS Publications Warehouse

Thomas, Lashun K.; Journey, Celeste A.; Stringfield, Whitney J.; Clark, Jimmy M.; Bradley, Paul M.; Wellborn, John B.; Ratliff, Hagan; Abrahamsen, Thomas A.

2011-01-01

A spatial survey of streams was conducted from February to April 2010 to assess the concentrations of major ions, selected trace elements, semivolatile organic compounds, organochlorine pesticides, and polychlorinated biphenyls associated with the bed sediments of surface waters at Fort Gordon military installation near Augusta, Georgia. This investigation expanded a previous study conducted in May 1998 by the U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, that evaluated the streambed sediment quality of selected surface waters at Fort Gordon. The data presented in this report are intended to help evaluate bed sediment quality in relation to guidelines for the protection of aquatic life, and identify temporal trends in trace elements and semivolatile organic compound concentrations at streambed sites previously sampled. Concentrations of 34 major ions and trace elements and 102 semivolatile organic, organochlorine pesticide, and polychlorinated biphenyl compounds were determined in the fine-grained fraction of bed sediment samples collected from 13 of the original 29 sites in the previous study, and 22 additional sites at Fort Gordon. Three of the sites were considered reference sites as they were presumed to be located away from potential sources of contaminants and were selected to represent surface waters flowing onto the fort, and the remaining 32 nonreference sites were presumed to be located within the contamination area at the fort. Temporal trends in trace elements and semivolatile organic compound concentrations also were evaluated at 13 of the 32 nonreference sites to provide an assessment of the variability in the number of detections and concentrations of constituents in bed sediment associated with potential sources, accumulation, and attenuation processes. Major ion and trace element concentrations in fine-grained bed sediment samples from most nonreference sites exceeded concentrations in samples from reference sites at Fort Gordon. Bed sediments from one of the nonreference sites sampled contained the highest concentrations of copper and lead with elevated levels of zinc and chromium relative to reference sites. The percentage change of major ions, trace elements, and total organic carbon that had been detected at sites previously sampled in May 1998 and current bed sediment sites ranged from -4 to 8 percent with an average percentage change of less than 1 percent. Concentrations of major ions and trace elements in bed sediments exceeded probable effect levels for aquatic life (based on the amphipod Hyalella azteca) established by the U.S. Environmental Protection Agency at 46 and 69 percent of the current and previously sampled locations, respectively. The greatest frequency of exceedances for major ions and trace elements in bed sediments was observed for lead. Concentrations of semivolatile organic compounds, organochlorine pesticides, and polychlorinated biphenyls were detected in bed sediment samples at 94 percent of the sites currently sampled. Detections of these organic compounds were reported with greater frequency in bed sediments at upstream sampling locations, when compared to downstream locations. The greatest number of detections of these compounds was reported for bed sediment samples collected from two creeks above a lake. The percentage change of semivolatile organic compounds detected at previously sampled and current bed sediment sites ranged from -68 to 100 percent with the greatest percentage increase reported for one of the creeks above the lake. Concentrations of semivolatile organic compounds and polychlorinated biphenyls in bed sediments exceeded aquatic life criteria established by the U.S. Environmental Protection Agency at three sites. Contaminant compounds exceeding aquatic life criteria included fluoranthene, phenanthrene, anthracene, benzo(a)anthracene

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

USGS Publications Warehouse

Juracek, Kyle E.; Rasmussen, Patrick P.

2008-01-01

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

The origin, historical variations, and distribution of heavy metals in the Qiongzhou Strait and nearby marine areas

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Chen, Liang; Wang, Weiping; Li, Tuanjie; Zu, Tingting

2017-04-01

We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine areas. The areas of high concentrations are primarily outside the eastern mouth of the Qiongzhou Strait and on the west side of the Leizhou Peninsula, whereas the areas of low concentrations are located primarily in the eastern Qiongzhou Strait. The maximum Cd, Pb and Zn concentrations in the samples collected in our study do not exceed the official standards for marine sediments, whereas the concentrations of Cr and Cu slightly exceed the standards. Correlations exist between the concentrations of Cu, Pb, Zn, Cr and Cd, and the concentrations of these metals are positively correlated with the mean particle size (φ value), indicating that the finer sediments have adsorbed greater amounts of heavy metal elements than the coarser sediments. An evaluation of the potential environmental risks demonstrates that certain indices of heavy metal pollution and environmental risks are relatively low and may be assigned low risk levels, thereby indicating that, in terms of heavy metals, the marine sedimentary environment in this region is only mildly impacted. Our analysis of the contaminant origins shows that the heavy metals in this region primarily originate in the Pearl River Estuary and that a small amount of them is derived from local runoff. The elevated heavy metal concentrations from the upper sections of the cores started 130 years ago, which indicats that heavy metals in the surface sediments are primarily due to human activities associated with industrialization.

Geochemistry of surface and pore water at USGS coring sites in wetlands of South Florida, 1994 and 1995

USGS Publications Warehouse

Orem, William H.; Lerch, Harry E.; Rawlik, Peter

2002-01-01

In this report, we present preliminary data on surface and pore water geochemistry from 22 sites in south Florida sampled during 1994 and 1995. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. The data are briefly discussed in regard to regional trends in the concentrations of chemical species, and general diagenetic processes in sediments. These results are part of a larger study designed to evaluate the role of biogeochemical processes in sediments in the cycling of carbon, nitrogen, phosphorus, and sulfur in the south Florida ecosystem. These elements play a crucial role in regulating organic sedimentation, nutrient dynamics, redox conditions, and the biogeochemistry of mercury in the threatened wetlands of south Florida. Pore water samples for chemical analyis were obtained using a piston corer/squeezer designed to avoid compression of the sediment and avoid oxidation and contamination of the pore water samples. Results show distinct regional trends in both surface water and pore water geochemistry. Most chemical species in surface and pore water show peak concentrations in Water Conservation Area 2A, with diminishing concentrations to the south and west into Water Conservation Area 3A, and Everglades National Park. The largest differences observed were for phosphate and sulfide, with concentrations in pore waters in Water Conservation Area 2A up to 500x higher than concentrations observed in freshwater marsh areas of Water Conservation Area 3A and Everglades National Park. Sites near the Hillsboro Canal in Water Conservation Area 2A are heavily contaminated with both phosphorus and sulfur. Pore water profiles for dissolved reactive phosphate suggest that recycling of phosphorus at these contaminated sites occurs primarily in the upper 20 cm of sediment. High levels of sulfide in pore water in Water Conservation Area 2A may inhibit mercury methylation here. At sites in Water Conservation Area 3A south of Alligator Alley, sulfide levels are much lower and sulfate reduction in the sediments here may be conducive to methyl mercury formation. Concentration versus depth profiles of biogeochemically important chemical species in pore water at most sites are smoth curves amenable to modelling using standard diagenetic equations. This should allow prediction of rates of biogeochemical processes in these sediments for incorporation in ecosystem models.

Toxicity of sediments and pore water from Brunswick Estuary, Georgia

USGS Publications Warehouse

Winger, Parley V.; Lasier, Peter J.; Geitner, Harvey

1993-01-01

A chlor-alkali plant in Brunswick, Georgia, USA, discharged >2 kg mercury/d into a tributary of the Turtle River-Brunswick Estuary from 1966 to 1971. Mercury concentrations in sediments collected in 1989 along the tributary near the chlor-alkali plant ranged from 1 to 27 μg/g (dry weight), with the highest concentrations found in surface (0–8 cm) sediments of subtidal zones in the vicinity of the discharge site. Toxicity screening in 1990 using Microtox® bioassays on pore water extracted on site from sediments collected at six stations distributed along the tributary indicated that pore water was highly toxic near the plant discharge. Ten-day toxicity tests on pore water from subsequent sediment samples collected near the plant discharge confirmed high toxicity to Hyalella azteca, and feeding activity was significantly reduced in whole-sediment tests. In addition to mercury in the sediments, other metals (chromium, lead, and zinc) exceeded 50 μg/g, and polychlorobiphenyl (PCB) concentrations ranged from 67 to 95 μg/g. On a molar basis, acid-volatile sulfide concentrations (20–45 μmol/g) in the sediments exceeded the metal concentrations. Because acid-volatile sulfides bind with cationic metals and form metal sulfides, which are generally not bioavailable, toxicities shown by these sediments were attributed to the high concentrations of PCBs and possibly methylmercury.

Characterizing the Fate and Mobility of Phosphorus in Utah Lake Sediments

NASA Astrophysics Data System (ADS)

Randall, M.; Carling, G. T.; Nelson, S.; Bickmore, B.; Miller, T.

2016-12-01

An increasing number of lakes worldwide are impacted by eutrophication and harmful algal blooms due to nutrient inputs. Utah Lake, located in northern Utah, is a eutrophic freshwater lake that is unique because it is naturally shallow, turbid, and alkaline with high dissolved oxygen levels. Recently, the Utah Division of Water Quality has proposed a new rule to limit phosphorus (P) loading to Utah Lake from wastewater treatment plants in an effort to mitigate eutrophication. However, reducing external P loads may not lead to immediate improvements in water quality due to the legacy pool of nutrients in lake sediments. The purpose of this study is to characterize the fate and mobility of P in Utah Lake to better understand P cycling in this unique system. We analyzed P speciation, mineralogy, and binding capacity in lake sediment samples collected from 9 locations across Utah Lake. P concentrations in sediment ranged from 1120 to 1610 ppm, with highest concentrations in Provo Bay near the major metropolitan area. Likewise, P concentrations in sediment pore water were highest in Provo Bay with concentrations up to 4 mg/L. Sequential leach tests indicate that 30-45% of P is bound to apatite and another 40-55% is adsorbed onto the surface of redox sensitive Fe/Mn hydroxides. This was confirmed by SEM images, which showed the highest P concentrations correlating with both Ca (apatite) and Fe (Fe hydroxides). The apatite-bound P fraction is likely immobile, but the P fraction sorbed to Fe/Mn hydroxides is potentially bioavailable under changing redox conditions. Batch sorption results indicate that lake sediments have a high capacity to absorb and remove P from the water column, with an average uptake of 70-96% of P from spiked surface water with concentrations ranging from 1-10 mg/L. Mineral precipitation and sorption to bottom sediments is an efficient removal mechanism of P in Utah Lake, but a significant portion of P may be available for resuspension and cycling in surface waters. Mitigating lake eutrophication is a complex problem that goes beyond reducing nutrient loads to the water body and requires a better understanding of internal P cycling.

Water-quality assessment of the Kentucky River basin, Kentucky; results of investigations of surface-water quality, 1987-90

USGS Publications Warehouse

Haag, K.H.; Garcia, Rene; Jarrett, G.L.; Porter, S.D.

1995-01-01

The U.S. Geological Survey investigated the water quality of the Kentucky River Basin in Kentucky as part of the National Water-Quality Assessment program. Data collected during 1987-90 were used to describe the spatial and temporal variability of water-quality constituents including metals and trace elements, nutrients, sediments, pesticides, dissolved oxygen, and fecal-coliform bacteria. Oil-production activities were the source of barium, bromide, chloride, magnesium, and sodium in several watersheds. High concentrations of aluminum, iron, and zinc were related to surface mining in the Eastern Coal Field Region. High concentrations of lead and zinc occurred in streambed sediments in urban areas, whereas concentrations of arsenic, strontium, and uranium were associated with natural geologic sources. Concentrations of phosphorus were significantly correlated with urban and agricultural land use. The high phosphorus content of Bluegrass Region soils was an important source of phosphorus in streams. At many sites in urban areas, most of the stream nitrogen load was attributable to wastewater-treatment-plant effluent. Average suspended-sediment concentrations were positively correlated with discharge. There was a downward trend in suspended-sediment concentrations downstream in the Kentucky River main stem during the study. The most frequently detected herbicides in water samples were atrazine, 2,4-D, alachlor, metolachlor, and dicamba. Diazinon, malathion, and parathion were the most frequently detected organophosphate insecticides in water samples. Detectable concentrations of aldrin, chlordane, DDT, DDE, dieldrin, endrin, endosulfan, heptachlor, and lindane were found in streambed-sediment samples. Dissolved-oxygen concentrations were sometimes below the minimum concentration needed to sustain aquatic life. At some sites, high concentrations of fecal-indicator bacteria were found and water samples did not meet sanitary water-quality criteria.

Historical record of mercury contamination in sediments from the Babeni Reservoir in the Olt River, Romania.

PubMed

Bravo, Andrea Garcia; Loizeau, Jean-Luc; Ancey, Lydie; Ungureanu, Viorel Gheorghe; Dominik, Janusz

2009-08-01

Mercury (Hg) is a ubiquitous and hazardous contaminant in the aquatic environment showing a strong biomagnification effect along the food chain. The most common transfer path of Hg to humans is contaminated fish consumption. In severely exposed humans, Hg poisoning may lead to damage in the central nervous system. Thus, it is important to examine current and past contamination levels of Hg in aquatic milieu. The Olt River is the largest Romanian tributary of the Danube River. The use of Hg as an electrode in a chlor-alkali plant contributed to the contamination of the aquatic environment in the Rm Valcea region. The purpose of this study was to compare the current state of Hg contamination with the past contamination using a historical record obtained from a dated sediment core from one of the Olt River reservoirs (Babeni) located downstream from the chlor-alkali plant. To our knowledge, no published data on Hg contamination in this region are available. The Babeni Reservoir was selected for this study because it is situated downstream from the chlor-alkali plant, whilst the other reservoirs only retain the pollutants coming from the upstream part of the watershed. Preliminary analyses (unpublished) showed high Hg concentrations in the surface sediment of the Babeni Reservoir. One core was taken in the upstream Valcea Reservoir to provide a local background level of Hg concentrations in sediments. Sediment texture was uniform in the cores from both reservoirs. Laminated sediment structure, without any obvious discontinuities, was observed. Hg concentrations in the sediment core from the Valcea Reservoir were low and constant (0.01-0.08 mg/kg). In Babeni Reservoir sediments, Hg concentrations were very high in the deeper core section (up to 45 mg/kg in the longest core) and decreased to lower concentrations toward the top of the cores (1.3-2.4 mg/kg). This decrease probably reflects technological progress in control of emissions from the Hg-cell-based chlor-alkali industry. Two strong peaks could be distinguished in older sediments. The mean rate of sedimentation (5.9 cm/year) was calculated from the depth of the (137)Cs Chernobyl peak. This was in good agreement with the sedimentation rate estimated at this site from a bathymetric study. Assuming a constant sedimentation rate, the two Hg peaks would reflect two contamination events in 1987 and 1991, respectively. However, it is also possible that the two peaks belong to the same contamination event in 1987 but were separated by a sediment layer richer in sand and silt. This layer had a low Hg concentration, which can be interpreted as a mass deposition event related to a major flood bringing Hg-free sediments. Whilst the chlor-alkali plant partly switched to a cleaner technology in 1999, no obvious decrease of Hg concentrations was observed in recent decade. Results from the sediment core reflected the historical trend of Hg release from the chlor-alkali plant, revealed important contamination episodes and confirmed a legacy of contamination of Hg in recent sediments even if the concentrations of Hg decreased toward the surface due to a more efficient emission control. Although the Hg concentrations in Babeni Reservoir sediments were extremely high in the late eighties and they remain one order of magnitude higher in the surface sediments than in sediments from the upstream reservoir, little is known about the transfer of Hg to the biota and human population. Our initial measurements indicate the presence of monomethyl-Hg (MMHg) in pore water, but further studies are necessary to evaluate fluxes of MMHg at the sediment-water interface. Samples of fish and hair from various groups of the local population were recently collected to evaluate the potential hazard of Hg contamination to human health in the Rm Valcea region.

Accurate mass replacement method for the sediment concentration measurement with a constant volume container

NASA Astrophysics Data System (ADS)

Ban, Yunyun; Chen, Tianqin; Yan, Jun; Lei, Tingwu

2017-04-01

The measurement of sediment concentration in water is of great importance in soil erosion research and soil and water loss monitoring systems. The traditional weighing method has long been the foundation of all the other measuring methods and instrument calibration. The development of a new method to replace the traditional oven-drying method is of interest in research and practice for the quick and efficient measurement of sediment concentration, especially field measurements. A new method is advanced in this study for accurately measuring the sediment concentration based on the accurate measurement of the mass of the sediment-water mixture in the confined constant volume container (CVC). A sediment-laden water sample is put into the CVC to determine its mass before the CVC is filled with water and weighed again for the total mass of the water and sediments in the container. The known volume of the CVC, the mass of sediment-laden water, and sediment particle density are used to calculate the mass of water, which is replaced by sediments, therefore sediment concentration of the sample is calculated. The influence of water temperature was corrected by measuring water density to determine the temperature of water before measurements were conducted. The CVC was used to eliminate the surface tension effect so as to obtain the accurate volume of water and sediment mixture. Experimental results showed that the method was capable of measuring the sediment concentration from 0.5 up to 1200 kg m-3. A good liner relationship existed between the designed and measured sediment concentrations with all the coefficients of determination greater than 0.999 and the averaged relative error less than 0.2%. All of these seem to indicate that the new method is capable of measuring a full range of sediment concentration above 0.5 kg m-3 to replace the traditional oven-drying method as a standard method for evaluating and calibrating other methods.

Distribution of tributyltin in surface sediments from transitional marine-lagoon system of the south-eastern Baltic Sea, Lithuania.

PubMed

Suzdalev, Sergej; Gulbinskas, Saulius; Blažauskas, Nerijus

2015-02-01

The current research paper presents the results of contamination by tributyltin (TBT) compounds in Klaipėda Port, which is situated in a unique marine-lagoon water interaction zone. One hundred fifty-four surface sediment samples have been taken along the whole transition path from lagoon to the sea and analysed in order to quantify the contamination rate in specific environment of high anthropogenic pressure. The detected TBT concentrations ranged from 1 to 5,200 ng Sn g(-1) of dry weight of sediment. The back-trace of horizontal distribution of TBT-contaminated sediments show obvious increase of tributyltin concentrations closer to port areas dealing with ship repair and places of dry-docking facilities. This is a clear indication that those activities are the main source of contamination in the study area. The estimated correlation of TBT concentration in sediments with total organic carbon and the amount of fine fraction (<0.063 mm) was significant for most of the stations. The TBT concentration in those sites varies from 1 to 100 ng Sn g(-1). This fact indicates that the most intensive accumulation of tributyltin is related to potential contamination source areas (ship repairing, dockyards) due to direct input of hazardous substances into the water.

Calculating the Diffusive Flux of Persistent Organic Pollutants between Sediments and the Water Column on the Palos Verdes Shelf Superfund Site using Polymeric Passive Samplers

EPA Science Inventory

Passive samplers were used to determine water concentrations of persistent organic pollutants (POPs) in the surface sediments and near-bottom water of a marine Superfund site on the Palos Verdes Shelf, California, USA. Measured concentrations in the porewater and water column at...

Enhancement of sediment phosphorus release during a tunnel construction across an urban lake (Lake Donghu, China).

PubMed

Wang, Siyang; Li, Hui; Xiao, Jian; Zhou, Yiyong; Song, Chunlei; Bi, Yonghong; Cao, Xiuyun

2016-09-01

Tunnel construction in watershed area of urban lakes would accelerate eutrophication by inputting nutrients into them, while mechanisms underlying the internal phosphorus cycling as affected by construction events are scarcely studied. Focusing on two main pathways of phosphorus releasing from sediment (enzymatic mineralization and anaerobic desorption), spatial and temporal variations in phosphorus fractionation, and activities of extracellular enzymes (alkaline phosphatase, β-1,4-glucosidase, leucine aminopeptidase, dehydrogenase, lipase) in sediment were examined, together with relevant parameters in interstitial and surface waters in a Chinese urban lake (Lake Donghu) where a subaqueous tunnel was constructed across it from October 2013 to July 2014. Higher alkaline phosphatase activity (APA) indicated phosphorus deficiency for phytoplankton, as illustrated by a significantly negative relationship between APA and concentration of dissolved total phosphorus (DTP). Noticeably, in the construction area, APAs in both sediment and surface water were significantly lower than those in other relevant basins, suggesting a phosphorus supply from some sources in this area. In parallel, its sediment gave the significantly lower iron-bound phosphorus (Fe(OOH)∼P) content, coupled with significantly higher ratio of iron (II) to total iron content (Fe(2+)/TFe) and dehydrogenase activities (DHA). Contrastingly, difference in the activities of sediment hydrolases was not significant between the construction area and other basins studied. Thus, in the construction area, subsidy of bioavailable phosphorus from sediment to surface water was attributable to the anaerobic desorption of Fe(OOH)∼P rather than enzymatic mineralization. Finally, there existed a significantly positive relationship between chlorophyll a concentration in surface water and Fe(OOH)∼P content in sediment. In short, construction activities within lakes may interrupt cycling patterns of phosphorus across sediment-water interface by enhancing release of redox-sensitive phosphate, and thereby facilitating phytoplankton growth in water column.

Mercury contamination of riverine sediments in the vicinity of a mercury cell chlor-alkali plant in Sagua River, Cuba.

PubMed

Bolaños-Álvarez, Yoelvis; Alonso-Hernández, Carlos Manuel; Morabito, Roberto; Díaz-Asencio, Misael; Pinto, Valentina; Gómez-Batista, Miguel

2016-06-01

Sediment is a great indicator for assessing coastal mercury contamination. The objective of this study was to assess the magnitude of mercury pollution in the sediments of the Sagua River, Cuba, where a mercury-cell chlor-alkali plant has operated since the beginning of the 1980s. Surface sediments and a sediment core were collected in the Sagua River and analyzed for mercury using an Advanced Mercury Analyser (LECO AMA-254). Total mercury concentrations ranged from 0.165 to 97 μg g(-1) dry weight surface sediments. Enrichment Factor (EF), Index of Geoaccumulation (Igeo) and Sediment Quality Guidelines were applied to calculate the degrees of sediment contamination. The EF showed the significant role of anthropogenic mercury inputs in sediments of the Sagua River. The result also determined that in all stations downstream from the chlor-alkali plant effluents, the mercury concentrations in the sediments were higher than the Probable Effect Levels value, indicating a high potential for adverse biological effects. The Igeo index indicated that the sediments in the Sagua River are evaluated as heavily polluted to extremely contaminated and should be remediated as a hazardous material. This study could provide the latest benchmark of mercury pollution and prove beneficial to future pollution studies in relation to monitoring works in sediments from tropical rivers and estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing Coral Reef: Evidence from Molokai, Hawaii

USGS Publications Warehouse

Ogston, A.S.; Field, M.E.

2010-01-01

Accelerating sea-level rise associated with global climate change will affect sedimentary processes on coral reefs and other shoreline environments by increasing energy and sediment resuspension. On reefs, sedimentation is known to increase coral stress and bleaching as particles that settle on coral surfaces interfere with photosynthesis and feeding, and turbidity induced by suspended sediment reduces incident light levels. Using relationships developed from observations of wave orbital velocity, water-surface elevation, and suspended-sediment concentration on a fringing reef flat of Molokai, Hawaii, predictions of the average daily maximum in suspended-sediment concentration increase from ~11 mg/l to ~20 mg/l with 20 cm sea-level rise. The duration of time concentrations exceeds 10 mg/l increases from 9 to 37. An evaluation of the reduction of wave energy flux through breaking and frictional dissipation across the reef flat shows an increase of ~80 relative to the present will potentially reach the shoreline as sea level increases by 20 cm. Where the shoreline exists on low, flat terrain, the increased energy could cause significant erosion of the shoreline. Considering the sediment budget, the sediment flux is predicted to increase and removal of fine-grained sediment may be expedited on some fringing reefs, and sediment in storage on the inner reef could ultimately be reduced. However, increased shoreline erosion may add sediment and offset removal from the reef flat. The shifts in sediment availability and transport that will occur as result of a modest increase in sea level have wide application to fringing coral reefs elsewhere, as well as other shoreline environments. ?? 2010 the Coastal Education & Research Foundation (CERF).

Mercury in Long Island Sound sediments

USGS Publications Warehouse

Varekamp, J.C.; Buchholtz ten Brink, Marilyn R.; Mecray, E.I.; Kreulen, B.

2000-01-01

Mercury (Hg) concentrations were measured in 394 surface and core samples from Long Island Sound (LIS). The surface sediment Hg concentration data show a wide spread, ranging from 600 ppb Hg in westernmost LIS. Part of the observed range is related to variations in the bottom sedimentary environments, with higher Hg concentrations in the muddy depositional areas of central and western LIS. A strong residual trend of higher Hg values to the west remains when the data are normalized to grain size. Relationships between a tracer for sewage effluents (C. perfringens) and Hg concentrations indicate that between 0-50 % of the Hg is derived from sewage sources for most samples from the western and central basins. A higher percentage of sewage-derived Hg is found in samples from the westernmost section of LIS and in some local spots near urban centers. The remainder of the Hg is carried into the Sound with contaminated sediments from the watersheds and a small fraction enters the Sound as in situ atmospheric deposition. The Hg-depth profiles of several cores have well-defined contamination profiles that extend to pre-industrial background values. These data indicate that the Hg levels in the Sound have increased by a factor of 5-6 over the last few centuries, but Hg levels in LIS sediments have declined in modern times by up to 30 %. The concentrations of C. perfringens increased exponentially in the top core sections which had declining Hg concentrations, suggesting a recent decline in Hg fluxes that are unrelated to sewage effluents. The observed spatial and historical trends show Hg fluxes to LIS from sewage effluents, contaminated sediment input from the Connecticut River, point source inputs of strongly contaminated sediment from the Housatonic River, variations in the abundance of Hg carrier phases such as TOC and Fe, and focusing of sediment-bound Hg in association with westward sediment transport within the Sound.

Quaternary stratigraphy, sediment characteristics and geochemistry of arsenic-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in central Bangladesh.

PubMed

Shamsudduha, M; Uddin, A; Saunders, J A; Lee, M-K

2008-07-29

This study focuses on the Quaternary stratigraphy, sediment composition, mineralogy, and geochemistry of arsenic (As)-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in the central Bangladesh. Arsenic concentrations in 85 tubewells in Manikganj area, 70 km northwest of Dhaka City, range from 0.25 microg/L to 191 microg/L with a mean concentration of 33 microg/L. Groundwater is mainly Ca-HCO(3) type with high concentrations of dissolved As, Fe, and Mn, but low level of SO(4). The uppermost aquifer occurs between 10 m and 80 m below the surface that has a mean arsenic concentration of 35 microg/L. Deeper aquifer (>100 m depth) has a mean arsenic concentration of 18 microg/L. Sediments in the upper aquifer are mostly gray to dark-gray, whereas sediments in the deep aquifer are mostly yellowing-gray to brown. Quartz, feldspar, mica, hornblende, garnet, kyanite, tourmaline, magnetite, ilmenite are the major minerals in sediments from both aquifers. Biotite and potassium feldspar are dominant in shallow aquifer, although plagioclase feldspar and garnet are abundant in deep aquifer sediments. Sediment composition suggests a mixed provenance with sediment supplies from both orogenic belts and cratons. High arsenic concentrations in sediments are found within the upper 50 m in drilled core samples. Statistical analysis shows that As, Fe, Mn, Ca, and P are strongly correlated in sediments. Concentrations of Cd, Cu, Ni, Zn, and Bi also show strong correlations with arsenic in the Manikganj sediment cores. Authigenic goethite concretions, possibly formed by bacteria, are found in the shallow sediments, which contain arsenic of a concentration as high as 8.8 mg/kg. High arsenic concentrations in aquifers are associated with fine-grained sediments that were derived mostly from the recycled orogens and relatively rapidly deposited mainly by meandering channels during the Early to Middle Holocene rising sea-level conditions.

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii

USGS Publications Warehouse

Bothner, Michael H.; Reynolds, R.L.; Casso, M.A.; Storlazzi, C.D.; Field, M.E.

2006-01-01

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates > 1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves.The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii.

PubMed

Bothner, Michael H; Reynolds, Richard L; Casso, Michael A; Storlazzi, Curt D; Field, Michael E

2006-09-01

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000-May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates>1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

Environmental impact of ongoing sources of metal contamination on remediated sediments

DOE PAGES

Knox, Anna Sophia; Paller, Michael H.; Milliken, Charles E.; ...

2016-04-29

One challenge to all remedial approaches for contaminated sediments is the continued influx of contaminants from uncontrolled sources following remediation. We investigated the effects of ongoing contamination in mesocosms employing sediments remediated by different types of active and passive caps and in-situ treatment. Our hypothesis was that the sequestering agents used in active caps and in situ treatment will bind elements (arsenic, chromium, cadmium, cobalt, copper, nickel, lead, selenium, and zinc) from ongoing sources thereby reducing their bioavailability and protecting underlying remediated sediments from recontamination. Most element concentrations in surface water remained significantly lower in mesocosms with apatite and mixedmore » amendment caps than in mesocosms with passive caps (sand), uncapped sediment, and spike solution throughout the 2520 hour experiment. Element concentrations were significantly higher in Lumbriculus variegatus from untreated sediment than in Lumbriculus from most active caps. Moreover, Pearson correlations between element concentrations in Lumbriculus and metal concentrations in the top 2.5 cm of sediment or cap measured by diffusive gradient in thin films (DGT) sediment probes were generally strong (as high as 0.98) and significant (p<0.05) for almost all tested elements. Metal concentrations in both Lumbriculus and sediment/cap were lowest in apatite, mixed amendment, and activated carbon treatments. Finally, these findings show that some active caps can protect remediated sediments by reducing the bioavailable pool of metals/metalloids in ongoing sources of contamination.« less

Biotransformation of tributyltin to tin in freshwater river-bed sediments contaminated by an organotin release

USGS Publications Warehouse

Landmeyer, J.E.; Tanner, T.L.; Watt, B.E.

2004-01-01

The largest documented release of organotin compounds to a freshwater river system in the United States occurred in early 2000 in central South Carolina. The release consisted of an unknown volume of various organotin compounds such tetrabutyltin (TTBT), tributyltin (TBT), tetraoctyltin (TTOT), and trioctyl tin (TOT) and resulted in a massive fish kill and the permanent closures of a municipal wastewater treatment plant and a local city's only drinking-water intake. Initial sampling events in 2000 and 2001 indicated that concentrations of the ecologically toxic TTBT and TBT were each greater than 10 000 ??g/kg in surface-water bed sediments in depositional areas, such as lakes and beaver ponds downstream of the release. Bed-sediment samples collected between 2001 and 2003, however, revealed a substantial decrease in bed-sediment organotin concentrations and an increase in concentrations of degradation intermediate compounds. For example, in bed sediments of a representative beaver pond located about 1.6 km downstream of the release, total organotin concentrations [the sum of TTBT, TBT, and the TBT degradation intermediates dibutyltin (DBT) and monobutyltin (MBT)] decreased from 38 670 to 298 ??g/kg. In Crystal Lake, a large lake about 0.4 km downstream from the beaver pond, total organotin concentrations decreased from 28 300 to less than 5 ??g/kg during the same time period. Moreover, bed-sediment inorganic tin concentrations increased from pre-release levels of less than 800 to 32 700 ??g/kg during this time. These field data suggest that the released organotin compounds, such as TBT, are being transformed into inorganic tin by bed-sediment microbial processes. Microcosms were created in the laboratory that contained bed sediment from the two sites and were amended with tributyltin (as tributyltin chloride) under an ambient air headspace and sacrificially analyzed periodically for TBT, the biodegradation intermediates DBT and MBT, and tin. TBT concentrations decreased faster [half-life (t1/2) = 28 d] in the organic-rich sediments (21.5%) that characterized the beaver pond as compared to the slower (t1/2 = 78 d) degradation rate in the sandy, organic-poor, sediments (0.43%) of Crystal Lake. Moreover, the concentration of inorganic tin increased in microcosms containing bed sediments from both locations. These field and laboratory results suggest that biotransformation of the released organotins, in particular the ecologically detrimental TBT, does occur in this fresh surface-water system impacted with high concentrations of neat organotin compounds.

Importance of Dissolved Neutral Hg-Sulfides, Energy Rich Organic Matter and total Hg Concentrations for Methyl Mercury Production in Sediments

NASA Astrophysics Data System (ADS)

Drott, A.; Skyllberg, U.

2007-12-01

Methyl mercury (MeHg) is the mercury form that biomagnifies to the greatest extent in aquatic food webs. Therefore information about factors determining MeHg concentrations is critical for accurate risk assessment of contaminated environments. The concentration of MeHg in wetlands and sediments is the net result of: 1) methylation rates, 2) demethylation rates, and 3) input/output processes. In this study, the main controls on Hg methylation rates and total concentrations of MeHg, were investigated at eight sites in Sweden with sediments that had been subjected to local Hg contamination either as Hg(0), or as phenyl-Hg. Sediments were selected to represent a gradient in total Hg concentration, temperature climate, salinity, primary productivity, and organic C content and quality. Most sediments were high in organic matter content due to wood fibre efflux from pulp and paper industry. The pore water was analysed for total Hg, MeHg, DOC, H2S(aq), pH, DOC, Cl and Br. The chemical speciation of Hg(II) and MeHg in pore water was calculated using equilibrium models. Potential methylation and demethylation rates in sediments were determined in incubation experiments at 23° C under N2(g) for 48 h, after addition of isotopically enriched 201Hg(II) and Me204Hg. In all surface (0-20 cm) sediments there was a significant (p<0.001) positive relationship between the experimentally determined specific potential methylation rate constant (Km, day-1) and % MeHg (concentrations of MeHg normalized to total Hg) in the sediment. This indicates that MeHg production overruled degradation and input/output processes of MeHg in surface sediments, and that % MeHg in surface sediments may be used as a proxy for net production of MeHg. To our knowledge, these are the first data showing significant positive relationships between short term (48 h) MeHg production and longer term accumulation of MeHg, across a range of sites with different properties (1). If MeHg was not normalized to total Hg, the relationship was not significant. For sub-sets of brackish waters (p<0.001, n=23), southern, high-productivity freshwaters (p<0.001, n=20) as well as northern, low-productivity freshwater (p=0.048, n=6), the sum of neutral Hg-sulfides [Hg(SH)20 (aq)] and [HgS0 (aq)] in the sediment pore water was significantly, positively correlated with both the potential methylation rate constant (Km) and total MeHg concentrations (2). This indicates that methylating sulphate reducing bacteria passively take up neutral Hg-sulfides, which are transformed to MeHg. Differences in slopes of the relationships were explained by differences in primary productivity and availability of energy-rich organic matter to methylating bacteria. High primary productivity at southern freshwater sites, reflected by a low C/N ratio (large contribution from free living algae and bacteria) in the sediment and a high annual temperature sum, resulted in high methylation rates. In conclusion, concentrations of neutral Hg-sulfides and availability of energy rich organic matter, but also total Hg concentrations in sediments are important factors behind net production and accumulation of MeHg . References: (1) Drott et. al. submitted, (2) Drott, A.; Lambertsson, L.; Björn, E.; Skyllberg, U. Importance of dissolved neutral mercury sulfides for methyl mercury production in contaminated sediments. Environmental Science & Technology 2007, 41, 2270-2276.

Abundance and δ13C values of fatty acids in lacustrine surface sediments: Relationships with in-lake methane concentrations

NASA Astrophysics Data System (ADS)

Stötter, Tabea; Bastviken, David; Bodelier, Paul L. E.; van Hardenbroek, Maarten; Rinta, Päivi; Schilder, Jos; Schubert, Carsten J.; Heiri, Oliver

2018-07-01

Proxy-indicators in lake sediments provide the only approach by which the dynamics of in-lake methane cycling can be examined on multi-decadal to centennial time scales. This information is necessary to constrain how lacustrine methane production, oxidation and emissions are expected to respond to global change drivers. Several of the available proxies for reconstructing methane cycle changes of lakes rely on interpreting past changes in the abundance or relevance of methane oxidizing bacteria (MOB), either directly (e.g. via analysis of bacterial lipids) or indirectly (e.g. via reconstructions of the past relevance of MOB in invertebrate diet). However, only limited information is available about the extent to which, at the ecosystem scale, variations in abundance and availability of MOB reflect past changes in in-lake methane concentrations. We present a study examining the abundances of fatty acids (FAs), particularly of 13C-depleted FAs known to be produced by MOB, relative to methane concentrations in 29 small European lakes. 39 surface sediment samples were obtained from these lakes and FA abundances were compared with methane concentrations measured at the lake surface, 10 cm above the sediments and 10 cm within the sediments. Three of the FAs in the surface sediment samples, C16:1ω7c, C16:1ω5c/t, and C18:1ω7c were characterized by lower δ13C values than the remaining FAs. We show that abundances of these FAs, relative to other short-chain FAs produced in lake ecosystems, are related with sedimentary MOB concentrations assessed by quantitative polymerase chain reaction (qPCR). We observed positive relationships between methane concentrations and relative abundances of C16:1ω7c, C16:1ω5c/t, and C18:1ω7c and the sum of these FAs. For the full dataset these relationships were relatively weak (Spearman's rank correlation (rs) of 0.34-0.43) and not significant if corrected for multiple testing. However, noticeably stronger and statistically significant relationships were observed when sediments from near-shore and deep-water oxic environments (rs = 0.57 to 0.62) and those from anoxic deep-water environment (rs = 0.55 to 0.65) were examined separately. Our results confirm that robust relationships exist between in-lake CH4 concentrations and 13C-depleted groups of FAs in the examined sediments, agreeing with earlier suggestions that the availability of MOB-derived, 13C-depleted organic matter for aquatic invertebrates increases with increasing methane concentrations. However, we also show that these relationships are complex, with different relationships observed for oxic and anoxic sediments and highest values measured in sediments deposited in oxic environments overlain with relatively methane-rich water. Furthermore, although all three 13C-depleted FA groups identified in our survey are known to be produced by MOB, they also receive contributions by other organism groups, and this will have influenced their distribution in our dataset.

Probabilistic modeling of the flows and environmental risks of nano-silica.

PubMed

Wang, Yan; Kalinina, Anna; Sun, Tianyin; Nowack, Bernd

2016-03-01

Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053-3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg · y in the EU (0.19-12 mg/kg · y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data. Copyright © 2015 Elsevier B.V. All rights reserved.

Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste

PubMed Central

Johnson, Bryce E.; Esser, Bradley K.; Whyte, Dyan C.; Ganguli, Priya M.; Austin, Carrie M.; Hunt, James R.

2009-01-01

The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta’s sediment surface had MMHg concentrations ranging from 7.5 to 31.5 ng/g, and the top 1 cm of sediment directly under the mats had two times greater MMHg concentrations compared to adjacent locations without algal covering. Spatial trends in resident biota reflect enhanced MMHg uptake at the delta compared to other bay locations. Eighteen sediment cores, 1 to 2 meters deep, collected from the 1.2 km2 delta provide an estimate of a total mercury (Hg) inventory of 2500 ± 500 kg. Sediment Hg concentrations ranged from pre-mining background conditions of approximately 0.1 μg/g to a post-mining maximum of 5 μg/g. Sediment accumulation rates were determined from three sediment cores using measured differences of 137Cs activity. We estimate a pre-mining Hg accumulation of less than 20 kg/yr, and a period of maximum Hg accumulation in the 1970s and 1980s with loading rates greater than 50 kg/yr, corresponding to the failure of a tailings dam at the mine site. At the time of sampling (2003) over 40 kg/yr of Hg was still accumulating at the delta, indicating limited recovery. We attribute observed spatial evolution of elevated Hg levels to ongoing inputs and sediment re-working, and estimate the inventory of the anthropogenic fraction of total Hg to be at least 1500 ± 300 kg. We suggest ongoing sediment inputs and methylation at the deltaic surface support enhanced mercury levels for resident biota and transfer to higher trophic levels throughout the Bay. PMID:19539980

Tidal wetland fluxes of dissolved organic carbon and sediment at Browns Island, California: initial evaluation

USGS Publications Warehouse

Ganju, N.K.; Bergamaschi, B.; Schoellhamer, D.H.

2003-01-01

Carbon and sediment fluxes from tidal wetlands are of increasing concern in the Sacramento-San Joaquin River Delta (Delta), because of drinking water issues and habitat restoration efforts. Certain forms of dissolved organic carbon (DOC) react with disinfecting chemicals used to treat drinking water, to form disinfection byproducts (DBPs), some of which are potential carcinogens. The contribution of DBP precursors by tidal wetlands is unknown. Sediment transport to and from tidal wetlands determines the potential for marsh accretion, thereby affecting habitat formation.Water, carbon, and sediment flux were measured in the main channel of Browns Island, a tidal wetland located at the confluence of Suisun Bay and the Delta. In-situ instrumentation were deployed between May 3 and May 21, 2002. Water flux was measured using acoustic Doppler current profilers and the index-velocity method. DOC concentrations were measured using calibrated ultraviolet absorbance and fluorescence instruments. Suspended-sediment concentrations were measured using a calibrated nephelometric turbidity sensor. Tidally averaged water flux through the channel was dependent on water surface elevations in Suisun Bay. Strong westerly winds resulted in higher water surface elevations in the area east of Browns Island, causing seaward flow, while subsiding winds reversed this effect. Peak ebb flow transported 36% more water than peak flood flow, indicating an ebb-dominant system. DOC concentrations were affected strongly by porewater drainage from the banks of the channel. Peak DOC concentrations were observed during slack after ebb, when the most porewater drained into the channel. Suspended-sediment concentrations were controlled by tidal currents that mobilized sediment from the channel bed, and stronger tides mobilized more sediment than the weaker tides. Sediment was transported mainly to the island during the 2-week monitoring period, though short periods of export occurred during the spring tide. Future deployments will characterize the seasonal variability of these fluxes.

Spatial variation and sources of polycyclic aromatic hydrocarbons influenced by intensive land use in an urbanized river network of East China.

PubMed

Bi, Chunjuan; Wang, Xueping; Jia, Jinpu; Chen, Zhenlou

2018-06-15

The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) in urbanized river networks are strongly influenced by intensive land use, industrial activities and population density. The spatial variations and their influencing factors of 16 priority PAHs were investigated in surface water, suspended particulate matter (SPM) and sediments among areas under different intensive land uses (industrial areas, agricultural areas, inner city, suburban towns and island areas) in the Shanghai river network, East China. Source apportionment was carried out using isomer ratios of PAHs and Positive Matrix Factorization (PMF). Total concentrations of 16 PAHs ranged from 105.2 to 400.5 ng/L, 108.1 to 1058.8 ng/L and 104.4 to 19,480.0 ng/g in water, SPM and sediments, respectively. The concentrations of PAHs in SPM and sediments varied significantly among areas (p < 0.05), with the highest concentrations in inner city characterized by highly intensive land use and high population density. The PAH concentrations in sediments were positively correlated with those in SPM and were more strongly correlated with black carbon than with total organic carbon, indicating a stronger influence of prolonged anthropogenic contamination than the recent surface input in sediments. Biomass and coal combustion contributed strongly to total PAHs, followed by natural gas combustion in water and SPM, and vehicular emissions in sediments. Vehicular emissions were the strongest contributors in SPM and sediments of the inner city, indicating the strong influence of vehicular transportation to PAHs pollution in the urbanized river network. Copyright © 2018 Elsevier B.V. All rights reserved.

Hydrocarbon composition and concentrations in the Gulf of Mexico sediments in the 3 years following the Macondo well blowout.

PubMed

Babcock-Adams, Lydia; Chanton, Jeffrey P; Joye, Samantha B; Medeiros, Patricia M

2017-10-01

In April of 2010, the Macondo well blowout in the northern Gulf of Mexico resulted in an unprecedented release of oil into the water column at a depth of approximately 1500 m. A time series of surface and subsurface sediment samples were collected to the northwest of the well from 2010 to 2013 for molecular biomarker and bulk carbon isotopic analyses. While no clear trend was observed in subsurface sediments, surface sediments (0-3 cm) showed a clear pattern with total concentrations of n-alkanes, unresolved complex mixture (UCM), and petroleum biomarkers (terpanes, hopanes, steranes) increasing from May to September 2010, peaking in late November 2010, and strongly decreasing in the subsequent years. The peak in hydrocarbon concentrations were corroborated by higher organic carbon contents, more depleted Δ 14 C values and biomarker ratios similar to those of the initial MC252 crude oil reported in the literature. These results indicate that at least part of oil discharged from the accident sedimented to the seafloor in subsequent months, resulting in an apparent accumulation of hydrocarbons on the seabed by the end of 2010. Sediment resuspension and transport or biodegradation may account for the decrease in sedimented oil quantities in the years following the Macondo well spill. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of selected radionuclides in sediment and surface water in Standley Lake, Great Western Reservoir, and Mower Reservoir, Jefferson County, Colorado, 1992

USGS Publications Warehouse

Clow, D.W.; Johncox, D.A.

1995-01-01

Lake sediment and surface water from Standley Lake, Great Western Reservoir, and Mower Reservoir, near Denver, Colorado, were sampled and analyzed for selected radionuclides during August through October, 1992. Sample concentrations were summarized and compared to results from a study conducted in 1983-84. Median plutonium-239,240 (239,240Pu) concentrations in lake-sediment grab samples from Standley Lake, Great Western Reservoir, and Mower Reservoir were 0.037, 0.105, and 0.351 picocuries per gram (pCi/g). The maximum concen- tration of 239,240Pu dissolved in lake water was 0.009 picocuries per liter, substantially below limits suggested by the Colorado Department of Health and the Environment. Dissolved concentrations of gross alpha and uranium isotopes were below National Drinking Water Standards in all water samples. There was no statistically significant difference between 239,240Pu concentration in lake-sediment grab samples collected from Standley Lake in 1983-84 and in 1992; however, there was a small, but statistically significant, difference at Great Western Reservoir (p<0.05). In 1992 at Great Western Reservoir, median 239,240Pu concentrations were 0.040 pCi/g lower than in 1983-84. There was a small, but statistically significant (p<0.05) difference in 239,240Pu concentrations in lake- bottom-sediment cores collected in 1983-84 and in 1992. Measured concentrations tended to be higher in 1983-84 than in 1992. The differences were greatest at concentrations above 1.5 pCi/g; in those samples concentrations were 10 to 30% higher in 1983-84 than in 1992.

Effects of the Razor Clam Tagelus plebeius on the Fate of Petroleum Hydrocarbons: A Mesocosm Experiment.

PubMed

Klerks, P L; Kascak, A; Cazan, A M; Deb Adhikary, N; Chistoserdov, A; Shaik, A; Osman, S; Louka, F R

2018-02-22

The relationship between organisms and contaminants may be a two-way interaction: contaminants affecting the biota and the biota affecting the environmental fate and distribution of the contaminants. This may be especially so for sediment-dwelling organisms, because their burrowing and feeding can drastically influence sediment characteristics. The present study looked at the influence of the suspension-feeding stout razor clam Tagelus plebeius on the distribution of crude oil and pyrene in greenhouse mesocosm experiments. Water column turbidity and sediment redox also were monitored during the 15- to 30-day exposures to provide information on the influence of hydrocarbons and the razor clams on environmental conditions. For the experiment with crude oil, sediment was taken from the mesocosms at the end of the experiment, and the hydrocarbon-degradation potential was assessed in incubations with 14 C-naphthalene. The experiments used four treatments: hydrocarbons present/absent and razor clams present/absent. Hydrocarbon dosing levels were relatively low (1 mL of oil or 30 mg of pyrene per mesocosm with 22 L of natural sediment and 11 L of seawater). The presence of the razor clams resulted in hydrocarbon concentrations at the sediment surface being 25% lower than in mesocosms without clams. No consistent effects were noted for polycyclic aromatic hydrocarbon (PAH) concentrations in the water column or in subsurface sediment. The naphthalene-degradation potential was elevated for sediment from mesocosms dosed with oil, but the presence of the clams did not affect this potential. The presence of the razor clams resulted in a lowering of water column turbidity, but no effect on sediment redox. The hydrocarbon addition had no effect on turbidity, but sediment redox was lowered. While results show that the presence of the razor clams resulted in a loss of hydrocarbons from the surface sediment, the other results do not provide a clear picture of the underlying mechanisms and the fate of the PAHs lost from the sediment surface. We hypothesize that the loss of surface sediment PAHs was due to burial of surface sediment and possibly bioaccumulation by the clams. While additional research is needed for further insights into underlying mechanisms, the present work demonstrates that the presence of sediment-burrowing suspension feeders decreases hydrocarbon levels in surface sediment. This means that assessments of the impact of an oil spill should pay attention to effects on these organisms and to their influence on the fate and distribution of the spilled oil.

Current and historical concentrations of poly and perfluorinated compounds in sediments of the northern Great Lakes - Superior, Huron, and Michigan.

PubMed

Codling, Garry; Hosseini, Soheil; Corcoran, Margaret B; Bonina, Solidea; Lin, Tian; Li, An; Sturchio, Neil C; Rockne, Karl J; Ji, Kyunghee; Peng, Hui; Giesy, John P

2018-05-01

Current and historical concentrations of 22 poly- and perfluorinated compounds (PFASs) in sediment collected from Lake Superior and northern Lake Michigan in 2011 and Lake Huron in 2012 are reported. The sampling was performed in two ways, Ponar grabs of surface sediments for current spatial distribution across the lake and dated cores for multi-decadal temporal trends. Mean concentrations of the sum of PFASs (∑PFASs) were 1.5, 4.6 and 3.1 ng g -1 dry mas (dm) in surface sediments for Lakes Superior, Michigan and Huron, respectively. Of the five Laurentian Lakes, the watersheds of Superior and Huron are the less densely populated by humans, and concentrations observed were typically less and from more diffuse sources, due to lesser urbanization and industrialization. However, some regions of greater concentrations were observed and might indicate more local, point sources. In core samples concentrations ranged from 7 that include perfluoro-n-octane sulfonate (PFOS) bind more strongly to sediment, which resulted in more accurate analyses of temporal trends. Shorter-chain PFASs, such as perfluoro-n-butanoic acid which is the primary replacement for C8 PFASs that have been phased out, are more soluble and were identified in some core layers at depths corresponding to pre-production periods. Thus, analyses of temporal trends of these more soluble compounds in cores of sediments were less accurate. Total elemental fluorine (TF) and extractable organic fluorine (EOF) indicated that identified PFASs were not a significant fraction of fluorine containing compounds in sediment (<0.01% in EOF). Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of environmental and anthropogenic factors on the composition, concentration and spatial distribution of microplastics: A case study of the Bay of Brest (Brittany, France).

PubMed

Frère, L; Paul-Pont, I; Rinnert, E; Petton, S; Jaffré, J; Bihannic, I; Soudant, P; Lambert, C; Huvet, A

2017-06-01

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53-67%) followed by polypropylene (PP, 16-30%) and polystyrene (PS, 16-17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg -1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m -3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem. Copyright © 2017 Elsevier Ltd. All rights reserved.

Organochlorine compounds and polycyclic aromatic hydrocarbons in surface sediment from Baiyangdian Lake, North China: concentrations, sources profiles and potential risk.

PubMed

Hu, Guocheng; Luo, Xiaojun; Li, Fengchao; Dai, Jiayin; Guo, Jianyang; Chen, Shejun; Hong, Cao; Mai, Bixian; Xu, Muqi

2010-01-01

Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) were determined in nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river (Fuhe River) in North China. Total concentrations of OCPs, PCBs and PAHs in sediments ranged from 5.4 to 707.6 ng/g, 2.3 to 197.8 ng/g, and 101.3 to 6360.5 ng/g, respectively. The levels of contaminants in Fuhe River were significantly higher than those in Baiyandian Lake. For hexachlorocyclohexane (HCHs) and dichlorodiphenytrichloroethanes (DDTs), alpha-HCH and p,p'-DDT were predominant isomers; while for PCBs, PCB 28/31, PCB 40/103, PCB 60, PCB 101, and PCB 118 were predominant congeners. Possible sources derived from historical usage for OCPs and incomplete combustion fuel, wood, and coal and exhaustion of boats or cars for PAHs. Risk assessment of sediment indicated that sediments in Fuhe River were likely to pose potential biological adverse impact.

Physical and chemical characteristics including total and geochemical forms of phosphorus in sediment from the top 30 centimeters of cores collected in October 2006 at 26 sites in Upper Klamath Lake, Oregon

USGS Publications Warehouse

Simon, Nancy S.; Ingle, Sarah N.

2011-01-01

μThis study of phosphorus (P) cycling in eutrophic Upper Klamath Lake (UKL), Oregon, was conducted by the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation. Lakebed sediments from the upper 30 centimeters (cm) of cores collected from 26 sites were characterized. Cores were sampled at 0.5, 1.5, 2.5, 3.5, 4.5, 10, 15, 20, 25, and 30 cm. Prior to freezing, water content and sediment pH were determined. After being freeze-dried, all samples were separated into greater than 63-micron (μm) particle-size (coarse) and less than 63-μm particle-size (fine) fractions. In the surface samples (0.5 to 4.5 cm below the sediment water interface), approximately three-fourths of the particles were larger than 63-μm. The ratios of the coarse particle-size fraction (>63 μm) and the fine particle-size fraction (<63 μm) were approximately equal in samples at depths greater than 10 cm below the sediment water interface. Chemical analyses included both size fractions of freeze-dried samples. Chemical analyses included determination of total concentrations of aluminum (Al), calcium (Ca), carbon (C), iron (Fe), poorly crystalline Fe, nitrogen (N), P, and titanium (Ti). Total Fe concentrations were the largest in sediment from the northern portion of UKL, Howard Bay, and the southern portion of the lake. Concentrations of total Al, Ca, and Ti were largest in sediment from the northern, central, and southernmost portions of the lake and in sediment from Howard Bay. Concentrations of total C and N were largest in sediment from the embayments and in sediment from the northern arm and southern portion of the lake in the general region of Buck Island. Concentrations of total C were larger in the greater than 63-μm particle-size fraction than in the less than 63-μm particle-size fraction. Sediments were sequentially extracted to determine concentrations of inorganic forms of P, including loosely sorbed P, P associated with poorly crystalline Fe oxides, and P associated with mineral phases. The difference between the concentration of total P and sum of the concentrations of inorganic forms of P is referred to as residual P. Residual P was the largest fraction of P in all of the sediment samples. In UKL, the correlation between concentrations of total P and total Fe in sediment is poor (R2<0.1). The correlation between the concentrations of total P and P associated with poorly crystalline Fe oxides is good (R2=0.43) in surface sediment (0.5-4.5 cm below the sediment water interface) but poor (R2<0.1) in sediments at depths between 10 cm and 30 cm. Phosphorus associated with poorly crystalline Fe oxides is considered bioavailable because it is released when sediment conditions change from oxidizing to reducing, which causes dissolution of Fe oxides.

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.

Hydrogeologic framework, arsenic distribution, and groundwater geochemistry of the glacial-sediment aquifer at the Auburn Road landfill superfund site, Londonderry, New Hampshire

USGS Publications Warehouse

Degnan, James R.; Harte, Philip T.

2013-01-01

Leachate continues to be generated from landfills at the Auburn Road Landfill Superfund Site in Londonderry, New Hampshire. Impermeable caps on the three landfills at the site inhibit direct infiltration of precipitation; however, high water-table conditions allow groundwater to interact with landfill materials from below, creating leachate and ultimately reducing conditions in downgradient groundwater. Reducing conditions can facilitate arsenic transport by allowing it to stay in solution or by liberating arsenic adsorbed to surfaces and from geologic sources, such as glacial sediments and bedrock. The site occupies a 180-acre parcel of land containing streams, ponds, wetlands, and former gravel pits located in glacial sediment. Four areas, totaling 14 acres, including three landfills and one septage lagoon, were used for waste disposal. The site was closed in 1980 after volatile organic compounds associated with industrial waste dumping were detected. The site was added to the U.S. Environmental Protection Agency National Priority List in 1982, and the landfills were capped in 1996. Although volatile organic compound concentrations in groundwater have declined substantially, some measurable concentrations remain. Temporally variable and persistent elevated arsenic concentrations have been measured in groundwater affected by the landfill leachate. Microbial consumption of carbon found in leachate is a driver of reducing conditions that liberate arsenic at the site. In addition to sources of carbon in landfill leachate, wetland areas throughout the site also could contribute carbon to groundwater, but it is currently unknown if any of the wetland areas have downward or reversing gradients that could allow the infiltration of surface water to groundwater. Red-stained sediments and water indicate iron-rich groundwater discharge to surface water and are also associated with elevated concentrations of arsenic in sediment and groundwater. Ironrich groundwater seeps have been observed in the wetland, streams, and pond downgradient of the landfills. Piezometers were installed in some of these locations to confirm groundwater discharge, measure vertical-flow gradients, and to provide a way to sample the discharging groundwater. Understanding the movement of leachate in groundwater is complicated by the presence of preferential flow paths through aquifer materials with differing hydraulic properties; these preferential flow paths can affect rates of recharge, geochemical conditions, and contaminant fluxes. In areas adjacent to the three capped landfills, infiltration of precipitation containing oxygenated water through permeable deltaic sediments in the former gravel pit area causes increases in dissolved oxygen concentrations and decreases in arsenic concentrations. Layered deltaic sediments produce anisotropic hydraulic characteristics and zones of high hydraulic conductivity. The glacial-sediment aquifer also includes glaciolacustrine sediments that have low permeability and limit infiltration at the surface Discharge of leachate-affected groundwater may be limited in areas of organic muck on the bottom of Whispering Pines Pond because the muck may act as a semiconfining layer. Geophysical survey results were used to identify several areas with continuous beds of muck and an underlying highresistivity layer on top of a layer of low resistivity that may represent leachate-affected groundwater. The high-resistivity layer is likely groundwater associated with oxygenated recharge, which would cause arsenic to adsorb onto aquifer sediments and reduce concentrations of dissolved arsenic in groundwater. Surface and borehole geophysical data collected in 2011 were used to identify potentially high-permeability or contaminated zones in the aquifer (preferential flowpaths) as well as low-permeability zones that may promote contamination through back diffusion. Some groundwater in parts of the glacial-sediment aquifer where the leachate plumes were present had low electrical resistivity, low dissolved oxygen, and high concentrations of arsenic. Low-resistivity zones in the underlying bedrock were associated with fractures that also may contain leachate. Although surveying the fractured bedrock was not a specific objective of this study, the results suggest that such a survey would help to determine if leachate and associated concentrations of arsenic are migrating downward into the fractured-bedrock-aquifer system. An uncalibrated, one-dimensional, reactive-transport model was used to assess several conditions that affect arsenic mobility. The results indicate that reductive dissolution and desorption from glacial sediments control dissolved arsenic concentrations. Parameter sensitivity analysis was used to identify key data that are needed in order to accurately assess the time required for arsenic concentrations to fall to levels below the maximum contaminant level at the site. Quantifying this time will require accurate characterization of carbon, sediment-surface sorption sites, and groundwater fluxes at the site.

The lacustrine carbon cycle as illuminated by the waters and sediments of two hydrologically distinct headwater lakes in North-Central Minnesota, U.S.A

USGS Publications Warehouse

Dean, W.E.; Schwalb, A.

2002-01-01

The accumulation rates of CaCO3 and organic carbon (OC) in lake sediments are delicately balanced between production in the epilimnion and destruction in the hypolimnion. The cycling of these two forms of carbon makes a "carbon pump" that greatly affects the biogeochemical cycles of other elements. To further understand these biogeochemical dynamics, the lakes, streams, and wetlands of the Shingobee River headwater area of north-central Minnesota have been subjected to intensive hydrologic and biogeochemical studies. Williams Lake, situated close to the highest point in the regional flow system, is hydrologically closed, with no surface inlet or outlet, and ground water and precipitation as the only sources of water. Shingobee Lake, situated at the lowest point in the regional flow system, has the Shingobee River as an inlet and outlet. The surface waters of both lakes are oversaturated, and the bottom waters undersaturated, with respect to CaCO3 during the summer. The small amount of CaCO3 that is precipitated in the epilimnion of Williams Lake during the summer is dissolved in the undersaturated hypolimnion and sediments with the result that no CaCO3 is incorporated into the profundal surface sediments. Because of the high phytoplankton productivity of Shingobee Lake, sufficient CaCO3 is produced in the epilimnion that large amounts survive the corrosive hypolimnion and sediments, and an average of 46 wt. % accumulates in surface sediments. Another consequence of higher phytoplankton productivity in Shingobee Lake is that the hypolimnion becomes oxygen deficient within a month after overturn in both the spring and fall. Because of reducing conditions that develop in the hypolimnion of Shingobee Lake, high concentrations of dissolved Fe and Mn accumulate there during summer stratification. Precipitation of Fe and Mn oxyhydroxides during periods of fall and spring overturn results in high concentrations of Fe and Mn in surface sediments. In Williams Lake, high concentrations of Fe and Mn do not build up in the hypolimnion. The concentration of CaCO3 is about 80 wt. % in lower Holocene sediments of both lakes. The lower Holocene sediments in both lakes also contain high concentrations of Fe and Mn, and the lower Holocene sediments of Shingobee are laminated. The waters of both lakes had identical values of ??13C and ??18O during the early Holocene, but the waters of Williams Lake "evolved" during the early Holocene, increasing about 10??? in both ??13C and ??18O. Deposits of lacustrine marl occur as much as seven meters above the present elevation of Williams Lake, the highest of the two lakes. Taken together, these observations suggest that the lakes were once connected to form a larger lake called Lake Willobee with a hypolimnion that was anoxic, at least seasonally.

Occurrence and distribution of selected heavy metals in the surface sediments of South Brittany coastal waters: An assessment using pollution indicators

NASA Astrophysics Data System (ADS)

Ong, M. C.; Menier, D.; Noor Azhar, M. S.; Dupont, V.; Révillon, S.

2012-04-01

In order to avoid the pollution of heavy metals in South Brittany water, it is necessary to establish the data and understand the mechanisms influencing the distribution of heavy metals of the area. One of the aims of this work was to assess heavy metals contamination in Gulf of Morbihan and Quiberon Bay. Another aim was to use interpolation surfaces per metals to assess the contamination separately per metal. A total of 196 bottom sediment samples were collected from the coastal waters in order to determine the spatial concentration of Cr, Mn, Co, Cu, Zn, Cd and Pb by Inductively Coupled Plasma Mass Spectrometry (ICPMS) after acid digestion. The average heavy metal concentrations are ranked as follows: Mn>Zn>Cr>Pb>Cu>Cu>Cd. In the gulf, metal enrichments observed compared to the bay environment may due river run-off from three major river (Auray, Le Marle and Novalo rivers) which carried municipal waste and maritime activities along the coastal area within the gulf. Beside those factors, the natural factors such as the sheltered basin morphology itself, fine sediment and low hydrodynamic regime which favour the in situ accumulation of pollutants. The level of pollution levels attributed to heavy metals was evaluated using several pollution indicators in order to determine anthropogenically derived sediment contamination. Comparison to sediment quality guidelines (SQGs), enrichment factors (EFs), index of geoaccumulation (Igeo) and contamination factors (CF) based on reference element and background value to compensate for the influence of the natural variability in sediment mineralogy and to assess whether the concentration observed in surface sediment represent background and contaminated levels and visualize using ArcGIS software. These analyses validated that the bottom sediment only enriched in Pb and the other metals in most sample are not due to artificial contamination. Overall, geochemistry of the samples show the effect of both natural and anthropogenic inputs to the catchment, however, natural processes are more dominant than anthropogenic inputs in concentrating metals in the sediment.

Do acid volatile sulfides (AVS) influence the accumulation of sediment-bound metals to benthic invertebrates under natural field conditions?

PubMed

De Jonge, Maarten; Dreesen, Freja; De Paepe, Josefina; Blust, Ronny; Bervoets, Lieven

2009-06-15

The present study evaluates the influence of acid volatile sulfides (AVS) on accumulation of sediment-bound metals in benthic invertebrates under natural field conditions. Natural sediments, pore water, surface water, and two species of widespread benthic invertebrates (Chironomus gr. thummi and Tubifex tubifex) were collected from 17 historical polluted Flemish lowland rivers and measured for metal concentrations. Different sediment characteristics were determined (AVS, organic matter, clay content) and multiple regression was used to study their relationship with accumulated metals in the invertebrates. Physical and chemical analysis of the field samples indicated low metal concentrations in the water and pore water, but very high metal concentrations in the sediment and the invertebrates, especially for Pb (5.99 micromol/ g). In general, metal accumulation in chironomids and tubificid worms was most strongly correlated with total metal concentrations in the sediment and sediment metal concentrations normalized for organic matter and clay content. Following the results of the linear regression model, AVS did not turn out to be a significant variable in describing variation in metal accumulation. Our study clearly demonstrates that, in addition to the results gained from experiments under lab conditions, benthic invertebrates can accumulate metals from unspiked field sediments even when there's an excess of AVS.

Contaminant distribution and accumulation in the surface sediments of Long Island Sound

USGS Publications Warehouse

Mecray, E.L.; Buchholtz ten Brink, Marilyn R.

2000-01-01

The distribution of contaminants in surface sediments has been measured and mapped as part of a U.S. Geological Survey study of the sediment quality and dynamics of Long Island Sound. Surface samples from 219 stations were analyzed for trace (Ag, Ba, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn and Zr) and major (Al, Fe, Mn, Ca, and Ti) elements, grain size, and Clostridium perfringens spores. Principal Components Analysis was used to identify metals that may covary as a function of common sources or geochemistry. The metallic elements generally have higher concentrations in fine-grained deposits, and their transport and depositional patterns mimic those of small particles. Fine-grained particles are remobilized and transported from areas of high bottom energy and deposited in less dynamic regions of the Sound. Metal concentrations in bottom sediments are high in the western part of the Sound and low in the bottom-scoured regions of the eastern Sound. The sediment chemistry was compared to model results (Signell et al., 1998) and maps of sedimentary environments (Knebel et al., 1999) to better understand the processes responsible for contaminant distribution across the Sound. Metal concentrations were normalized to grain-size and the resulting ratios are uniform in the depositional basins of the Sound and show residual signals in the eastern end as well as in some local areas. The preferential transport of fine-grained material from regions of high bottom stress is probably the dominant factor controlling the metal concentrations in different regions of Long Island Sound. This physical redistribution has implications for environmental management in the region.

Surface-water-quality assessment of the upper Illinois River Basin in Illinois, Indiana, and Wisconsin; data on agricultural organic compounds, nutrients, and sediment in water, 1988-90

USGS Publications Warehouse

Sullivan, D.J.; Terrio, P.J.

1994-01-01

This report describes the sampling design and methods and presents data collected to determine the distribution of agricultural organic compounds, nutrients, and sediment in selected areas of the upper Illinois River Basin as part of the National Water-Quality Assessment program. Four stations in small watersheds (two urban, two agricultural) were sampled in 1988 and 1989. Seventeen stations in an agricultural subbasin were sampled in 1990. Samples were collected before, during, and after runoff events from late spring to midsummer to determine concentrations of agricultural organic compounds in surface waters resulting from storm runoff, as well as background concentrations. Over 200 water samples were analyzed for agricultural organic compound, nutrient, and suspended-sediment concentrations. The agricultural organic compounds included triazine and chlorophenoxy-acid herbicides, and organo-phosphorus insecticides.

Heavy metal concentration in mangrove surface sediments from the north-west coast of South America.

PubMed

Fernández-Cadena, J C; Andrade, S; Silva-Coello, C L; De la Iglesia, R

2014-05-15

Mangrove ecosystems are coastal estuarine systems confined to the tropical and subtropical regions. The Estero Salado mangrove located in Guayaquil, Ecuador, has suffered constant disturbances during the past 20 years, due to industrial wastewater release. However, there are no published data for heavy metals present in its sediments and the relationship with anthropogenic disturbance. In the present study, metal concentrations were evaluated in surface sediment samples of the mangrove, showing that B, Cd, Cu, Pb, Se, V, and Zn levels exceeded those declared in international environmental quality standards. Moreover, several metals (Pb, Sn, Cd, Ag, Mo, Zn and Ni) could be linked to the industrial wastewater present in the studied area. In addition, heavy metal levels detected in this mangrove are higher than previous reports on mangrove sediments worldwide, indicating that this mangrove ecosystem is one of the most disrupted on earth. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

PubMed Central

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

2014-01-01

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

The Environment Quality, Speciation and their Origins of Heavy Metals in Surficial Sediments in Central Bohai Sea, China

NASA Astrophysics Data System (ADS)

Liu, M.; Fan, D.; Han, Z.; Liao, Y.; Chen, B.; Yang, Z.

2016-02-01

The concentrations and speciations of heavy metals (Cu, Co, Ni, Zn, Pb, Cr and Cd) in surface and core sediments collected from the central Bohai Sea were analyzed by ICP-MS, to evaluate their distribution / fractionation, pollution status and sources. The results showed that Cd exhibited gradual increasing vertically, while others were stable or declined slightly in core sediments. Metals showed higher values in `central mud area of the Bohai Sea' and the coastal area of the Bohai Bay in surface sediments. Residual fractions were the dominant forms of Cu, Co, Ni, Zn and Cr in the surface sediments, while Cd and Pb had large proportions of the total concentration in the non-residual fractions. Both the contamination factors and the geo-accumulation index indicated that Cu, Co, Ni, Cr were not polluted, while Pb, Zn, Cd were in moderate contamination. The ecological risk assessment (by sepeciations) indicated that the sediments were unpolluted with respect to the heavy metals Co, Ni and Cr and unpolluted to moderately polluted with respect to Cu, Zn, Cd and Pb. Compared with sediment quality guidelines (SQGs), Cu, Zn, Cr, Pb, Cd were likely to produce occasional adverse biological effects, while Ni showed possible ecotoxicological risks. The combined levels of the metals have a 21% probability of being toxic. Elements Cr, Co and Ni were mainly natural origined and significantly affected by the composition of sediments. Cu, Zn, Pb and especially Cd may be influenced by human activities.

Distribution and ecological risk assessment of HCHs and DDTs in surface seawater and sediment of the mariculture area of Jincheng Bay, China

NASA Astrophysics Data System (ADS)

Hu, Yanbing; Sun, Shan; Song, Xiukai; Ma, Jianxin; Ru, Shaoguo

2015-04-01

The distribution of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L-1 and were < 0.032 ng L-1, respectively, in surface seawater, and ranged from 5.52 to 9.43 and from 4.11 to 6.72 ng g-1, respectively, in surface sediment. It was deduced from the composition profile of HCH isomers and DDT congeners that HCH residues derived from a mixture of technical-grade HCH and lindane whereas the DDT residues derived from technical-grade DDT and dicofol. Moreover, both HCH and DDT residues may mainly originate from historical inputs. The hazard quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p, p'-DDD, p, p'-DDE and p, p'-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.

Mass fluxes of organic pollutants between groundwater, streambed sediments and surface water

NASA Astrophysics Data System (ADS)

Schirmer, Mario; Kalbus, Edda; Schmidt, Christian

2010-05-01

Rivers and groundwater are commonly hydraulically connected and thus also pollutants migrate between one and the other. Particularly in small lowland streams, pollutant transport by discharging groundwater can deteriorate the surface water quality. Moreover, in urban and industrial areas streambed sediments are often polluted with a variety of organic and inorganic substances. For planning measures to improve surface water quality or to mitigate pollutant migration, it is an essential prerequisite to understand pollutant pathways and mass fluxes between the stream, the streambed sediment and the connected aquifer. We present methodological approaches and results of a study conducted at a small man-made stream located in the industrial area of Bitterfeld-Wolfen, Germany. This site is characterized by a diffuse groundwater contamination with a variety of aliphatic and aromatic organic substances. The underlying approach of this study was to quantify the mass fluxes between the aquifer, the streambed and the stream by combining high-resolution with integral monitoring approaches. Magnitudes and pattern of water fluxes were obtained by mapping streambed temperatures. The method was applied to a reach of 280 m in length. The mass fluxes from the aquifer towards the stream were estimated by combining the water fluxes with representative, average pollutant concentrations. The concentrations were obtained from an integral pumping test with four simultaneously pumped wells operated for the period of five days. For monochlorobenzene (MCB), the main groundwater pollutant at the site, the resulting average mass flux from the aquifer towards the stream was estimated to 724 µg/m²/d. Mass flux calculations with average aqueous concentrations of MCB in the streambed were found to be higher than those originating from the aquifer. Consequently, the streambed sediments represent a secondary pollutant source for the surface water. Pollutant concentrations in the streambed were lower at locations with high groundwater discharge and vice versa. Hence, the spatial heterogeneity of water fluxes must be considered when mass fluxes between surface water and streambed sediments are assessed. River restoration could improve the structural state of rivers and may thus result in an enhanced biodegradation of organic pollutants in the streambed. However, before any physical measure is applied a profound knowledge of pollutant concentration and pathways is required in order to avoid mobilization of sediment-bound pollutants.

Water-Quality Characterization of Surface Water in the Onondaga Lake Basin, Onondaga County, New York, 2005-08

USGS Publications Warehouse

Coon, William F.; Hayhurst, Brett A.; Kappel, William M.; Eckhardt, David A.V.; Szabo, Carolyn O.

2009-01-01

Water-resources managers in Onondaga County, N.Y., have been faced with the challenge of improving the water-quality of Onondaga Lake. To assist in this endeavor, the U.S. Geological Survey undertook a 3-year basinwide study to assess the water quality of surface water in the Onondaga Lake Basin. The study quantified the relative contributions of nonpoint sources associated with the major land uses in the basin and also focused on known sources (streams with large sediment loads) and presumed sinks (Onondaga Reservoir and Otisco Lake) of sediment and nutrient loads, which previously had not been evaluated. Water samples were collected and analyzed for nutrients and suspended sediment at 26 surface-water sites and 4 springs in the 285-square-mile Onondaga Lake Basin from October 2005 through December 2008. More than 1,060 base-flow, stormflow, snowmelt, spring-water, and quality-assurance samples collected during the study were analyzed for ammonia, nitrite, nitrate-plus-nitrite, ammonia-plus-organic nitrogen, orthophosphate, phosphorus, and suspended sediment. The concentration of total suspended solids was measured in selected samples. Ninety-one additional samples were collected, including 80 samples from 4 county-operated sites, which were analyzed for suspended sediment or total suspended solids, and 8 precipitation and 3 snowpack samples, which were analyzed for nutrients. Specific conductance, salinity, dissolved oxygen, and water temperature were periodically measured in the field. The mean concentrations of selected constituents in base-flow, stormflow, and snowmelt samples were related to the land use or land cover that either dominated the basin or had a substantial effect on the water quality of the basin. Almost 40 percent of the Onondaga Lake Basin is forested, 30 percent is in agricultural uses, and almost 21 percent, including the city of Syracuse, is in developed uses. The data indicated expected relative differences among the land types for concentrations of nitrate, ammonia-plus-organic nitrogen, and orthophosphate. The data departed from the expected relations for concentrations of phosphorus and suspended sediment, and plausible explanations for these departures were posited. Snowmelt concentrations of dissolved constituents generally were greater and those of particulate constituents were less than concentrations of these constituents in storm runoff. Presumably, the snowpack acted as a short-term sink for dissolved constituents that had accumulated from atmospheric deposition, and streambed erosion and resuspension of previously deposited material, rather than land-surface erosion, were the primary sources of particulate constituents in snowmelt flows. Longitudinal assessments documented the changes in the median concentrations of constituents in base flows and event flows (combined stormflow and snowmelt) from upstream to downstream monitoring sites along the two major tributaries to Onondaga Lake - Onondaga Creek and Ninemile Creek. Median base-flow concentrations of ammonia and phosphorus and event concentrations of ammonia increased in the downstream direction in both streams. Whereas median event concentrations of other constituents in Onondaga Creek displayed no consistent trends, concentrations of ammonia-plus-organic nitrogen, orthophosphate, phosphorus, and suspended sediment in Ninemile Creek decreased from upstream to downstream sites. Springs discharging from the Onondaga and Bertie Limestone had measureable effects on water temperatures in the receiving streams and increased salinity and values of specific conductance in base flows. Loads of selected nutrients and suspended sediment transported in three tributaries of Otisco Lake were compared with loads from 1981-83. Loads of ammonia-plus-organic nitrogen and orthophosphate decreased from 1981-83 to 2005-08, but those of nitrate-plus-nitrite, phosphorus, and suspended sediment increased. The largest load increase was for suspende

Vertical Segregation and Phylogenetic Characterization of Ammonia-Oxidizing Bacteria and Archaea in the Sediment of a Freshwater Aquaculture Pond

PubMed Central

Lu, Shimin; Liu, Xingguo; Ma, Zhuojun; Liu, Qigen; Wu, Zongfan; Zeng, Xianlei; Shi, Xu; Gu, Zhaojun

2016-01-01

Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in sediment samples (0–50 cm depth) collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5- to 39.9-fold in surface sediments (0–10 cm depth), which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0–2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10–15 and 20–25 cm depths) were grouped into the Nitrosopumilus cluster. PMID:26834709

Pollution by organochlorine pesticides in Navachiste-Macapule, Sinaloa, Mexico.

PubMed

Montes, Adriana M; González-Farias, Fernando A; Botello, Alfonso V

2012-03-01

The lagoon system of Navachiste-Macapule is located in northern Mexico, in the state of Sinaloa, with an area of 24,000 ha. The main economic activity in the area is agriculture, and the lagoon lies next to the irrigation district ID-063 which covers 116,615 ha. The purpose of this study is to evaluate the levels of pollution generated by organochlorine pesticides (OC) in the surface sediments of the lagoon and in the agricultural drains of the ID-063 that are supposedly transported into the system as a result of agricultural activities and runoff from adjacent land. For this, between 2006 and 2007, 45 surface sediment samples were collected (warm dry, rainy and cold dry) from 15 sampling sites, during the three climatic seasons. Of these, eight were located inside the lagoon in marine conditions (salinity >31 PSU) and seven in the agricultural drains of the ID-063 in freshwater conditions (salinity <5 PSU). The average concentration of the OC in the sediments was 44.75 ng g(-1), among which the group of the alicyclic compounds presented the greatest concentrations. The average value of the total organic carbon (TOC) in the sediments of the system was 0.90%. The sediments collected inside the lagoon had an average OC concentration of 18.97 ng g(-1), and the predominant type of sediment was fine to very fine sand. The average OC concentration in the sediments collected in the agricultural drains was 75.69 ng g(-1), where fine sediments (silt) were predominant. The presence of methoxychlor, endrin and heptachlor suggested that these compounds were continuously used in the system, even though their use is forbidden in Mexico.

Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.

PubMed

Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender

2016-05-01

Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

The Influence of Coastal Wetland Zonation on Surface Sediment and Porewater Mercury Speciation

NASA Astrophysics Data System (ADS)

Marvin-DiPasquale, M. C.; Windham-Myers, L.; Wilson, A. M.; Buck, T.; Smith, E.

2014-12-01

An investigation of mercury (Hg) speciation in saltmarsh surface sediment (top 0-2 cm) and porewater (integrated 0-50 cm) was conducted along two monitoring well transects established within North Inlet Estuary (S. Carolina, USA) as part of the NOAA sponsored National Estuarine Research Reserve (NERR) network. Transects were perpendicular to the shoreline, from the forested uplands to the edge of the tidal channel, and traversed a range of vegetated zones from the high marsh (pickleweed, rush, and salt panne-dominated) to the low marsh (cordgrass dominated), as mediated by elevation and tidal inundation. Sediment grain size and organic content explained 95% of the variability in the distribution of total Hg (THg) in surface sediment. Tin-reducible 'reactive' mercury (HgR) concentration was 10X greater in the high marsh, compared to the low marsh, and increased sharply with decreasing sediment pH values below pH=6. The percentage of THg as HgR decreased as sediment redox conditions became more reducing. There were no significant differences in surface sediment methylmercury (MeHg) concentrations between high and low marsh zones. In contrast, porewater MeHg concentrations were 5X greater in the high marsh compared to the low marsh. As a percentage of THg, mean porewater %MeHg was 23% in the low marsh and 51% in the high marsh, reaching levels of 73-89% in a number of high marsh sites. Calculations of partitioning between porewater and the solid phase suggest stronger binding to particles in the low marsh and a shift towards the dissolved phase in the high marsh for both THg and MeHg. These results are consistent with a conceptual model for coastal wetlands where the less frequently inundated high marsh zone may be important in terms of MeHg production and enhanced subsurface mobilization, partially due to the subsurface mixing of saline estuarine water and freshwater draining in from the uplands area.

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.

Nutrients, organic compounds, and mercury in the Meduxnekeag River watershed, Maine, 2003

USGS Publications Warehouse

Schalk, Charles W.; Tornes, Lan

2005-01-01

In 2003, the U.S. Geological Survey, in cooperation with the Houlton Band of Maliseet Indians, sampled streambed sediments and surface water of the Meduxnekeag River watershed in northeastern Maine under various hydrologic conditions for nutrients, hydrophobic organic compounds, and mercury. Nutrients were sampled to address concerns related to summer algal blooms, and organic compounds and mercury were sampled to address concerns about regional depositional patterns and overall watershed quality. In most surface-water samples, phosphorus was not detected or was detected at concentrations below the minimum reporting limit. Nitrate and organic nitrogen were detected in every surface-water sample for which they were analyzed; the highest concentration of total nitrogen was 0.75 milligrams per liter during low flow. Instantaneous nitrogen loads and yields were calculated at four stations for two sampling events. These data indicate that the part of the watershed that includes Houlton, its wastewater-treatment plant, and four small urban brooks may have contributed high concentrations of nitrate to Meduxnekeag River during the high flows on April 23-24 and high concentrations of both organic and nitrate nitrogen on June 2-3. Mercury was detected in all three bed-sediment samples for which it was analyzed; concentrations were similar to those reported from regional studies. Notable organic compounds detected in bed sediments included p,p'-DDE and p,p'-DDT (pesticides of the DDT family) and several polycyclic aromatic hydrocarbons. Polychlorinated biphenyls (PCBs) and phthalates were not detected in any sample, whereas p-cresol was the only phenolic compound detected. Phosphorus was detected at concentrations below 700 milligrams per kilogram in each bed-sediment sample for which it was analyzed. Data were insufficient to establish whether the lack of large algal blooms in 2003 was related to low concentrations of phosphorus.

Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the lower San Joaquin River drainage, California

USGS Publications Warehouse

Brown, Larry R.

1998-01-01

Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 16 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of total DDT (sum of o,p'- and p,p'-forms of DDD, DDE, and DDT) were statistically different among groups of sites for tissue and sediment (Kruskal-Wallis, P < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of total DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (P < 0.05), which are indicators of the proportion of irrigation-return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total-organic- carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (P < 0.05). Regressions of the concentration of total DDT in tissue as a function of total DDT in bed sediment were significant and explained as much as 76 percent of the variance in the data. The concentration of total DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment.

Mercury Distribution in the Deûle River (Northern France) Measured by the Diffusive Gradients in Thin Films Technique and Conventional Methods.

PubMed

Diviš, Pavel; Kadlecová, Milada; Ouddane, Baghdad

2016-05-01

The distribution of mercury in surface water and in sediment from Deûle River in Northern France was studied by application of conventional sampling methods and by diffusive gradients in thin films technique (DGT). Concentration of total dissolved mercury in surface water was 20.8 ± 0.8 ng l(-1). The particulate mercury concentration was 6.2 ± 0.6 µg g(-1). The particulate mercury was accumulated in sediment (9.9 ± 2.3 mg kg(-1)), and it was transformed by methylating bacteria to methylmercury, mainly in the first 2-cm layer of the sediment. Total dissolved concentration of mercury in sediment pore water obtained by application of centrifugation extraction was 17.6 ± 4.1 ng l(-1), and it was comparable with total dissolved pore water mercury concentration measured by DGT probe containing Duolite GT-73 resin gel (18.2 ± 4.3 ng l(-1)), taking the sediment heterogeneity and different principles of the applied methods into account. By application of two DGT probes with different resin gels specific for mercury, it was found that approximately 30% of total dissolved mercury in sediment pore water was present in labile forms easy available for biota. The resolution of mercury DGT depth profiles was 0.5 cm, which allows, unlike conventional techniques, to study the connection of the geochemical cycle of mercury with geochemical cycles of iron and manganese.

Accumulation of sedimentary photosynthetic pigments characterized by pyropheophorbide a and steryl chlorin esters (SCEs) in a shallow eutrophic coastal lake (Lake Hamana, Japan)

NASA Astrophysics Data System (ADS)

Itoh, Nobuyasu; Tani, Yukinori; Soma, Yuko; Soma, Mitsuyuki

2007-01-01

We investigated the factors controlling the composition of sedimentary photosynthetic pigments in Lake Hamana (Japan), a shallow (12 m), brackish, holomictic lake, by analyzing photosynthetic pigments and the sterol composition of steryl esters of pyropheophorbide a (steryl chlorin esters, SCEs) in the water column and surface sediments. The mean annual composition of carotenoids in the water was quite different from that in the surface sediments. We evaluated the relative accumulation efficiency of individual pigments in the sediments by comparing ratios of individual pigment concentrations relative to total chlorophyll a (TChl- a) in sediment to those in the water column. The relative accumulation efficiencies decreased in the following order: lutein > diatoxanthin > β,β-carotene > zeaxanthin > β,ɛ-carotene > alloxanthin ≫ fucoxanthin. The ratio of total pyro-derivatives of chlorophyll a, formed through the grazing of algae by zooplankton, to TChl- a in the surface sediments was much higher (0.24-0.33) than that in the water column, which was less than 0.03 even in the deepest water (10 m). The summed concentration of pyropheophytin a and SCEs (TPyphe- a) showed positive and significant relationships ( r2 > 0.56, n = 7) with residual carotenoids in sediments. These results suggest that incorporation of algal pigments in fecal pellets through grazing by zooplankton enhances pigment preservation during early diagenesis at the sediment surface. Moreover, sedimentary carotenoid compositions were consistent with the sterol compositions of sedimentary SCE fractions. Selective grazing by zooplankton was thus a primary factor determining the composition of sedimentary carotenoids in this lake.

Environmental monitoring and assessment of heavy metals in surface sediments at Coleroon River Estuary in Tamil Nadu, India.

PubMed

Venkatramanan, S; Chung, S Y; Ramkumar, T; Selvam, S

2015-08-01

The combined studies on grain size distribution, organic matter contents of sediments, sequential extraction and bulk concentration of heavy metals, statistical analysis, and ecological risk assessments were carried out to investigate the contamination sources and ecological risks of surface sediments at Coleroon River Estuary in Tamil Nadu, India. The sequential extraction of metals showed that a larger portion of the metals was associated with the residual phase and also in other fractions. The low concentrations of heavy metals were found in exchangeable and carbonate bounds (bioavailable phases). It revealed that sediments of Coleroon River Estuary were relatively unpolluted and were influenced mainly by natural sources. The observed order of bulk concentrations of heavy metals in the sediments was as follows: Fe > Mn > Zn > Cu > Pb > Cr > Ni > Co. Factor analyses represented that the enrichment of heavy metals was mostly resulted from lithogenic origins associated with anthropogenic sources. These sources were reconfirmed by cluster analysis. Risk assessment code (RAC) suggested that all metals were not harmful in monsoon season. However, Fe was in medium risk, and Mn and Cu were in low risk in summer. According to pollution load index (PLI) of sediments, all heavy metals were toxic. Cu might be related with adverse biological effects on the basis of sediment quality guidelines (SQG) in both seasons. These integrated approaches were very useful to identify the contamination sources and ecological risks of sediments in estuarine environment. It is expected that this research can give a useful information for the remediation of heavy metals in sediments.

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

Knox, Anna Sophia; Paller, Michael H.; Milliken, Charles E.

One challenge to all remedial approaches for contaminated sediments is the continued influx of contaminants from uncontrolled sources following remediation. We investigated the effects of ongoing contamination in mesocosms employing sediments remediated by different types of active and passive caps and in-situ treatment. Our hypothesis was that the sequestering agents used in active caps and in situ treatment will bind elements (arsenic, chromium, cadmium, cobalt, copper, nickel, lead, selenium, and zinc) from ongoing sources thereby reducing their bioavailability and protecting underlying remediated sediments from recontamination. Most element concentrations in surface water remained significantly lower in mesocosms with apatite and mixedmore » amendment caps than in mesocosms with passive caps (sand), uncapped sediment, and spike solution throughout the 2520 hour experiment. Element concentrations were significantly higher in Lumbriculus variegatus from untreated sediment than in Lumbriculus from most active caps. Moreover, Pearson correlations between element concentrations in Lumbriculus and metal concentrations in the top 2.5 cm of sediment or cap measured by diffusive gradient in thin films (DGT) sediment probes were generally strong (as high as 0.98) and significant (p<0.05) for almost all tested elements. Metal concentrations in both Lumbriculus and sediment/cap were lowest in apatite, mixed amendment, and activated carbon treatments. Finally, these findings show that some active caps can protect remediated sediments by reducing the bioavailable pool of metals/metalloids in ongoing sources of contamination.« less

Algae metabolism and organic carbon in sediments determining arsenic mobilisation in ground- and surface water. A field study in Doñana National Park, Spain.

PubMed

Kohfahl, Claus; Navarro, Daniel Sánchez-Rodas; Mendoza, Jorge Armando; Vadillo, Iñaki; Giménez-Forcada, Elena

2016-02-15

A study has been performed to explore the origin, spatiotemporal behaviour and mobilisation mechanism of the elevated arsenic (As) concentrations found in ground water and drinking ponds of the Doñana National Park, Southern Spain. At a larger scale, 13 piezometers and surface water samples of about 50 artificial drinking ponds and freshwater lagoons throughout the National Park were collected and analysed for major ions, metals and trace elements. At a smaller scale, 5 locations were equipped with piezometers and groundwater was sampled up to 4 times for ambient parameters, major ions, metals, trace elements and iron (Fe) speciation. As was analysed for inorganic and organic speciation. Undisturbed sediment samples were analysed for physical parameters, mineralogy, geochemistry as well as As species. Sediment analyses yielded total As between 0.1 and 18 mg/kg and are not correlated with As concentration in water. Results of the surface- and groundwater sampling revealed elevated concentration of As up to 302 μg/L within a restricted area of the National Park. Results of groundwater sampling reveals strong correlation of As with Fe(2+) pointing to As mobilisation due to reductive dissolution of hydroferric oxides (HFO) in areas of locally elevated amounts of organic matter within the sediments. High As concentrations in surface water ponds are correlated with elevated alkalinity and pH attributed to algae metabolism, leading to As desorption from HFO. The algae metabolism is responsible for the presence of methylated arsenic species in surface water, in contrast to ground water in which only inorganic As species was found. Temporal variations in surface water and groundwater are also related to changes in pH and alkalinity as a result of enhanced algae metabolism in surface water or related to changes in the redox level in the case of groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.

Concentrations of chlorinated organic compounds in biota and bed sediment in streams of the San Joaquin Valley, California

USGS Publications Warehouse

Brown, L.R.

1997-01-01

Samples of resident biota and bed sediments were collected in 1992 from 18 sites on or near the floor of the San Joaquin Valley, California, for analysis of 33 organochlorine compounds. The sites were divided into five groups on the basis of physiographic region and land use. Ten compounds were detected in tissue, and 15 compounds were detected in bed sediment. The most frequently detected compound in both media was p,p'-DDE. Concentrations of ??DDT (sum of o,p'- and p, p' forms of DDD, DDE, and DDT) were statistically different among groups of sites for both tissue and sediment (Kruskal- Wallis, p < 0.05). Concentrations in both media were highest in streams draining the west side of the valley. Concentrations of ??DDT in tissue were significantly correlated with specific conductance, pH, and total alkalinity (p < 0.05), which are indicators of the proportion of irrigation return flows in stream discharge. Concentrations in sediment on a dry-weight basis were not correlated with these water-quality parameters, but total organic carbon (TOC) normalized concentrations were significantly correlated with specific conductance and pH (p < 0.05). Regressions of the concentration of ??DDT in tissue, as a function of ??DDT in bed sediment, were significant and explained up to 76% of the variance in the data. The concentration of ??DDT in sediment may be related to mechanisms of soil transport to surface water with bioavailability of compounds related to the concentration of TOC in sediment. The results of this study did not indicate any clear advantage to using either bed sediment or tissues in studies of organochlorine chemicals in the environment. Some guidelines for protection of fish and wildlife were exceeded. Concentrations of organochlorine chemicals in biota, and perhaps sediment, have declined from concentrations measured in the 1970s and 1980s, but remain high compared to other regions of the United States.

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.

Perfluoroalkyl substances and extractable organic fluorine in surface sediments and cores from Lake Ontario.

PubMed

Yeung, Leo W Y; De Silva, Amila O; Loi, Eva I H; Marvin, Chris H; Taniyasu, Sachi; Yamashita, Nobuyoshi; Mabury, Scott A; Muir, Derek C G; Lam, Paul K S

2013-09-01

Fourteen perfluoroalkyl substances (PFASs) including short-chain perfluorocarboxylates (PFCAs, C4-C6) and perfluoroalkane sulfonates (PFSAs, C4 and C6) were measured in surface sediment samples from 26 stations collected in 2008 and sediment core samples from three stations (Niagara, Mississauga, and Rochester basins) collected in 2006 in Lake Ontario. Perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUnDA) were detected in all 26 surface sediment samples, whereas perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonamide (FOSA), perfluorododecanoate (PFDoDA) and perfluorobutanoate (PFBA) were detected in over 70% of the surface sediment samples. PFOS was detected in all of the sediment core samples (range: 0.492-30.1ngg(-1) d.w.) over the period 1952-2005. The C8 to C11 PFCAs, FOSA, and PFBA increased in early 1970s. An overall increasing trend in sediment PFAS concentrations/fluxes from older to more recently deposited sediments was evident in the three sediment cores. The known PFCAs and PFSAs accounted for 2-44% of the anionic fraction of the extractable organic fluorine in surface sediment, suggesting that a large proportion of fluorine in this fraction remained unknown. Sediment core samples collected from Niagara basin showed an increase in unidentified organic fluorine in recent years (1995-2006). These results suggest that the use and manufacture of fluorinated organic compounds other than known PFCAs and PFSAs has diversified and increased. © 2013.

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.

Dissolved methane concentrations in the water column and surface sediments of Hanna Shoal and Barrow Canyon, Northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Lapham, Laura; Marshall, Kathleen; Magen, Cédric; Lyubchich, Viacheslav; Cooper, Lee W.; Grebmeier, Jacqueline M.

2017-10-01

Current estimates of methane (CH4) flux suggest that Arctic shelves may be a significant source of atmospheric CH4, a potent greenhouse gas. However, little information is known about the CH4 flux from most Arctic shelves, other than the East Siberian Arctic Shelf. We report here dissolved CH4 concentrations in the water column and within surface sediments of the Northern Chukchi Sea. We hypothesized that this area contains high concentrations of CH4 because it receives nutrient rich waters through the Bering Strait, promoting primary production that enhances an organic-rich material flux to the seafloor and eventual microbial methanogenesis in the sediments. In August 2012, as part of the Chukchi Sea Offshore Monitoring in Drilling Area (COMIDA) project, fourteen stations were sampled on Hanna Shoal, a shallow feature on the shelf, and ten stations across the undersea Barrow Canyon. On Hanna Shoal, water column CH4 concentrations ranged from 14 to 74 nM, and surface concentrations were up to 15 times supersaturated in CH4 compared to equilibrium with the average atmospheric concentrations (3 nM). CH4 concentrations at the sediment-water interface were around 1,500 nM, and typically increased with depth in the sediment. At the head of Barrow Canyon, water column CH4 concentrations ranged from 5 to 46 nM, with the highest concentrations in the deepest waters that were sampled (118 m). Overall, the calculated fluxes to the atmosphere ranged from 1 to 80 μmol CH4 m-2 d-1 for Hanna Shoal and 4 to 17 μmol CH4 m-2 d-1 across the Barrow Canyon stations. Although there was a large range in these fluxes, the average atmospheric flux (20 μmol CH4 m-2 d-1) across Hanna Shoal was 12 times lower than the flux reported from the East Siberian Arctic Shelf in summer. We conclude that while there is a positive flux of CH4 to the atmosphere, this part of the Chukchi Sea is not a significant source of atmospheric CH4 compared to the East Siberian Sea shelf.

Selected Metals in Sediments and Streams in the Oklahoma Part of the Tri-State Mining District, 2000-2006

USGS Publications Warehouse

Andrews, William J.; Becker, Mark F.; Mashburn, Shana L.; Smith, S. Jerrod

2009-01-01

The abandoned Tri-State mining district includes 1,188 square miles in northeastern Oklahoma, southeastern Kansas, and southwestern Missouri. The most productive part of the Tri-State mining district was the 40-square mile part in Oklahoma, commonly referred to as 'the Picher mining district' in north-central Ottawa County, Oklahoma. The Oklahoma part of the Tri-State mining district was a primary producing area of lead and zinc in the United States during the first half of the 20th century. Sulfide minerals of cadmium, iron, lead, and zinc that remained in flooded underground mine workings and in mine tailings on the land surface oxidized and dissolved with time, forming a variety of oxide, hydroxide, and hydroxycarbonate metallic minerals on the land surface and in streams that drain the district. Metals in water and sediments in streams draining the mining district can potentially impair the habitat and health of many forms of aquatic and terrestrial life. Lakebed, streambed and floodplain sediments and/or stream water were sampled at 30 sites in the Oklahoma part of the Tri-State mining district by the U.S. Geological Survey and the Oklahoma Department of Environmental Quality from 2000 to 2006 in cooperation with the U.S. Environmental Protection Agency, and the Quapaw and Seneca-Cayuga Tribes of Oklahoma. Aluminum and iron concentrations of several thousand milligrams per kilogram were measured in sediments collected from the upstream end of Grand Lake O' the Cherokees. Manganese and zinc concentrations in those sediments were several hundred milligrams per kilogram. Lead and cadmium concentrations in those sediments were about 10 percent and 0.1 percent of zinc concentrations, respectively. Sediment cores collected in a transect across the floodplain of Tar Creek near Miami, Oklahoma, in 2004 had similar or greater concentrations of those metals than sediment cores collected at the upstream end of Grand Lake O' the Cherokees. The greatest concentrations of cadmium, iron, lead, and zinc were detected in sediments beneath an intermittent tributary to Tar Creek, a slough which drains mined areas near Commerce, Oklahoma. In surface water, aluminum and iron concentrations were greatest in the Neosho River, perhaps a result of runoff from areas underlain by shales. The greatest aqueous concentrations of cadmium, lead, manganese, and zinc were measured in water from Tar Creek, the primary small stream draining the Picher mining district with the largest proportion of mined area. Water from the Spring River had greater zinc concentrations than water from the Neosho River, perhaps as a result of a greater proportion of mined area in the Spring River Basin. Dissolved metals concentrations were generally much less than total metals concentrations, except for manganese and zinc at sites on Tar Creek, where seepage of ground water from the mine workings, saturated mine tailings, and/or metalliferous streambed sediments may be sources of these dissolved metals. Iron and lead concentrations generally decreased with increasing streamflow in upstream reaches of Tar Creek, indicating dilution of metals-rich ground water by runoff. Farther downstream in Tar Creek, and in the Neosho and Spring Rivers, metals concentrations tended to increase with increasing streamflow, indicating that most metals in these parts of these streams were associated with runoff and re-suspension of metals precipitated as oxide, hydroxide, and hydroxycarbonate minerals on land surface and streambeds. Estimated total aluminum, cadmium, iron, manganese, and zinc loads generally were greatest in water from the Neosho and Spring Rivers, primarily because of comparatively large streamflows in those rivers. Slight increases in metal loads in the downstream directions on those rivers indicated contributions of metals from inflows of small tributaries such as Tar Creek and from runoff.

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.

Occurrence, distribution, and risk assessment of alkylphenols, bisphenol A, and tetrabromobisphenol A in surface water, suspended particulate matter, and sediment in Taihu Lake and its tributaries.

PubMed

Liu, Dan; Liu, Jining; Guo, Min; Xu, Huaizhou; Zhang, Shenghu; Shi, Lili; Yao, Cheng

2016-11-15

The occurrence and distribution of nine selected compounds were investigated in surface water, suspended particulate matter (SPM), and sediment in Taihu Lake and its tributaries. With the exception of 4-Butylphenol, all compounds were detected in at least two phases, and nonylphenol (NP) and 4-tert-Octylphenol (4-OP) were the predominant alkylphenols (APs) in the lake. A significant correlation was observed between NP and 4-OP, indicating that they may share the same source. Moreover, surface water phase was the dominant sink of Bisphenol A (BPA) in the aquatic environment. The concentrations of BPA between the surface water and SPM phases were closely related to each other. In addition, Tetrabromobisphenol A (TBBPA) exhibited relatively higher concentrations and detection frequencies in the SPM. Risk assessment revealed greater risk associated with the surface water than the sediment, indicating that the discharge of industrial wastewater and domestic sewage poses a serious threat to aquatic ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Unravelling metal mobility under complex contaminant signatures.

PubMed

de Souza Machado, Anderson Abel; Spencer, Kate L; Zarfl, Christiane; O'Shea, Francis T

2018-05-01

Metals are concerning pollutants in estuaries, where contamination can undergo significant remobilisation driven by physico-chemical forcing. Environmental concentrations of metals in estuarine sediments are often higher than natural backgrounds, but show no contiguity to potential sources. Thus, better understanding the metal mobility in estuaries is essential to improve identification of pollution sources and their accountability for environmental effects. This study aims to identify the key biogeochemical drivers of metal mobilisation on contaminated estuarine sediments through (1) evaluation of the potential mobilisation under controlled conditions, and (2) investigation of the relevance of metal mobilisation for in situ pollution levels in an area with multiple contaminant sources. Sediments from a saltmarsh adjacent to a coastal landfill, a marina, and a shipyard on the Thames Estuary (Essex, UK) were exposed in the laboratory (24h, N=96, 20°C) to water under various salinity, pH, and redox potential. Major cations, Fe(II), and trace metal concentrations were analysed in the leachate and sediment. Salinity, pH and redox had a significant effect on metal mobilisation (p<0.001), e.g. under certain conditions Fe(II) leaching was increased ~1000-fold. Measurements in situ of surface and subsurface sediment cores revealed that landfill proximity poorly explained metal spatial distribution. However, physicochemical parameters explained up to 97% of geochemically normalized metal concentrations in sediments. Organic matter and pH were dominant factors for most of the metal concentrations at the sediment surface. At subsurface, major cations (Ca, Na, Mg and K) were determinant predictors of metal concentrations. Applying the empirical model obtained in the laboratory to geochemical conditions of the studied saltmarsh it was possible to demonstrate that Fe mobilisation regulates the fate of this (and other) metal in that area. Thus, present results highlight the importance of metal mobility to control sediment pollution and estuarine fate of metals. Copyright © 2017 Elsevier B.V. All rights reserved.

Alkane and polycyclic aromatic hydrocarbons in sediments and benthic invertebrates of the northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger; Taylor, Karen A.

2017-10-01

The Hanna Shoal region represents an important northern gateway for transport and deposition in the Chukchi Sea. This study determined the concentration and distribution of organic contaminants (aliphatic hydrocarbon and polycyclic aromatic hydrocarbons, PAHs) in surface sediments from 34 sites across Hanna Shoal. Up to 31 total PAHs, including parent and alkyl homologues were detected with total concentrations ranging from a low of 168 ng g-1 the western flank of Hanna Shoal (station H34) to 1147 ng g-1 at station in Barrow Canyon (station BarC5). Alkyl PAHs were more abundant than parent structures and accounted for 53-64% of the summed concentrations suggesting overall at background levels (< 1600 ng g-1) in sediments. Alkane (C15-C33) hydrocarbons ranged from 4.3 μg g-1 on the southern flank of Hanna shoal to 31 μg g-1 at a northern station. Sediments were often dominated by short chain (C15-C22) alkanes with overall terrestrial aquatic ratios (TAR) for the region averaging 0.20. Based on the ratio of Fl/(Fl+ Py) and BaF/(Baf+BeP) verses (BA/BA+Ch) in sediments, PAHs are largely derived from petrogenic sources with minor amounts of mixed combustion sources. A diversity of PAHs were detected in the northern whelk Neptunea heros foot muscle with total concentrations ranging from 0.14 to 1.5 μg g-1 dry tissue wt. Larger (and presumably older) animals showed higher levels of PAH per unit muscle tissue, suggesting that animals may bioaccumulate PAHs over time, with low but increasing concentrations also present in internal and external eggs. Alkane hydrocarbons were also higher in whelks with distributions similar to that seen in sediments. The mussel Muscularus discors collected in Barrow Canyon showed constrained distributions and substantially lower concentrations of both PAHs and alkanes than the surrounding surface sediments.

Enhanced Sorption of PAHs in Natural-Fire-Impacted Sediments from Oriole Lake, California

EPA Science Inventory

Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon (BC), and their δ13C isotope ratios. Sediments displayed high OC(20-25%) and increasing BC concentrations from ∼0.40% (in 1800 C.E.) to ∼0.60% dry weight (in 2000 C.E.). Petrographic...

Effects of spatial and temporal variation of acid-volatile sulfide on the bioavailability of copper and zinc in freshwater sediments

USGS Publications Warehouse

Besser, John M.; Ingersoll, Christopher G.; Giesty, John P.

1996-01-01

Variation in concentrations of acid-volatile sulfide (AVS) in sediments from the upper Clark Fork River of Montana, USA, was associated with differences in bioaccumulation of Cu and Zn and growth of larvae of the midge, Chironomus tentans. Growth of midge larvae was significantly greater and bioaccumulation of Cu was significantly less in surface sections (0–3 cm depth) of sediment cores, which had greater concentrations of AVS and lesser ratios of simultaneously extracted metals to AVS (SEM:AVS ratios) than in subsurface sediments (6–9 cm). Concentrations of AVS were significantly less in sediments incubated with oxic overlying water for 9 weeks than in the same sediments incubated under anoxic conditions. Bioaccumulation of Cu differed significantly between incubation treatments, corresponding to differences in concentrations of AVS and SEM:AVS ratios, although midge growth did not. Bioaccumulation of Zn did not differ significantly between depth strata of sediment cores or between incubation treatments. When results from the two sets of bioassays were combined, bioaccumulation of Cu and Zn, but not growth, was significantly correlated with SEM:AVS ratios and other estimates of bioavailable metal fractions in sediments. Growth of midge larvae was significantly correlated with bioaccumulation of Zn, but not Cu, suggesting that Zn was the greater contributor to the toxicity of these sediments. Assessments of the toxicity of metal-contaminated freshwater sediments should consider the effects of spatial and temporal variation in AVS concentrations on metal bioavailability.

Seasonal variation of nonylphenol concentrations and fluxes with influence of flooding in the Daliao River Estuary, China.

PubMed

Li, Zhengyan; Gibson, Mark; Liu, Chang; Hu, Hong

2013-06-01

Nonylphenol is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This study aims to investigate the distribution and ecological risks of nonylphenol in the Daliao River Estuary, China. Nonylphenol, together with other phenolic endocrine disruptors (bisphenol A, 4-t-butylphenol, 4-t-octylphenol, and 2,4-dichlorophenol), was detected in surface water and sediment on three cruises in May 2009, June 2010, and August 2010, respectively. A large flooding occurred during our sampling campaign in August and its effect on nonylphenol concentrations and fluxes in the estuary was therefore evaluated. The results showed that nonylphenol with a concentration range between 83.6-777 ng l(-1) and 1.5-456 ng g(-1) dw in surface water and sediment was the most abundant among the phenolic compounds, accounting for 59.1-81.0 and 79.9-92.1 % of the total phenolic concentration in surface water and sediment, respectively. The concentrations recorded in May and June were comparable, whereas those in August were considerably higher, mainly due to the flush of flooding. The flooding also caused a 50 times increase in nonylphenol flux from the estuary into the adjacent Bohai Sea. Nonylphenol concentrations in the estuary have exceeded the threshold level of undesirable effects with a potential risk of harm to local species, especially benthic organisms.

Distribution, Source, and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediment of Liaodong Bay, Northeast China

NASA Astrophysics Data System (ADS)

Xu, Shuang; Tao, Ping; Li, Yuxia; Guo, Qi; Zhang, Yan; Wang, Man; Jia, Hongliang; Shao, Mihua

2018-01-01

Sixteen polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from Liaodong Bay, northeast China. The concentration levels of total PAHs (Σ16PAHs) in sediment were 11.0˜249.6 ng·g-1 dry weight (dw), with a mean value of 89.9 ng·g-1 dry weight (dw). From the point of the spatial distribution, high PAHs levels were found in the western areas of Liaodong Bay. In the paper, sources of PAHs were investigated by diagnostic ratios, which indicated that pyrogenic sources were the main sources of PAHs in the sediment of Liaodong Bay. Therefore, selected PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL indexes) for evaluation probable toxic effects on marine organism.

Toxicity and bioavailability of metals in the Missouri River adjacent to a lead refinery

USGS Publications Warehouse

Chapman, Duane C.; Allert, Ann L.; Fairchild, James F.; May, Thomas W.; Schmitt, Christopher J.; Callahan, Edward V.

2001-01-01

This study is an evaluation of the potential environmental impacts of contaminated groundwater from the ASARCO metals refining facility adjacent to the Missouri River in Omaha, Nebraska. Surface waters, sediments, and sediment pore waters were collected from the Burt-Izard drain, which transects the facility, and from the Missouri River adjacent to the facility. Groundwater was also collected from the facility. Waters and sediments were analyzed for inorganic contaminants, and the toxicity of the waters was evaluated with the Ceriodaphnia dubia 7-day test. Concentrations of several elemental contaminants were highly elevated in the groundwater, but not in river sediment pore waters. Lead concentrations were moderately elevated in whole sediment at one site, but lead concentrations in pore waters were low due to apparent sequestration by acid-volatile sulfides. The groundwater sample was highly toxic to C. dubia, causing 100% mortality. Even at the lowest groundwater concentration tested (6.25%) C. dubia survival was reduced; however, at that concentration, reproduction was not significantly different from upstream porewater reference samples. Sediment pore waters were not toxic, except reproduction in pore water collected from one downstream site was somewhat reduced. The decrease in reproduction could not be attributed to measured elemental contaminants.

Distribution of total and methyl mercury in sediments along Steamboat Creek (Nevada, USA)

USGS Publications Warehouse

Stamenkovic, J.; Gustin, M.S.; Marvin-DiPasquale, M. C.; Thomas, B.A.; Agee, J.L.

2004-01-01

In the late 1800s, mills in the Washoe Lake area, Nevada, used elemental mercury to remove gold and silver from the ores of the Comstock deposit. Since that time, mercury contaminated waste has been distributed from Washoe Lake, down Steamboat Creek, and to the Truckee River. The creek has high mercury concentrations in both water and sediments, and continues to be a constant source of mercury to the Truckee River. The objective of this study was to determine concentrations of total and methyl mercury (MeHg) in surface sediments and characterize their spatial distribution in the Steamboat Creek watershed. Total mercury concentrations measured in channel and bank sediments did not decrease downstream, indicating that mercury contamination has been distributed along the creek's length. Total mercury concentrations in sediments (0.01-21.43 ??g/g) were one to two orders of magnitude higher than those in pristine systems. At 14 out of 17 sites, MeHg concentrations in streambank sediments were higher than the concentrations in the channel, suggesting that low banks with wet sediments might be important sites of mercury methylation in this system. Both pond/wetland and channel sites exhibited high potential for mercury methylation (6.4-30.0 ng g-1 day-1). Potential methylation rates were positively correlated with sulfate reduction rates, and decreased as a function of reduced sulfur and MeHg concentration in the sediments. Potential demethylation rate appeared not to be influenced by MeHg concentration, sulfur chemistry, DOC, sediment grain size or other parameters, and showed little variation across the sites (3.7-7.4 ng g-1 day-1). ?? 2003 Elsevier B.V. All rights reserved.

DDTs and other chlorinated organic pesticides and polychlorinated biphenyls pollution in the surface sediments of Keratsini harbour, Saronikos gulf, Greece.

PubMed

Galanopoulou, Stavroula; Vgenopoulos, Andreas; Conispoliatis, Nikolaos

2005-05-01

Sediment samples were collected from Keratsini harbour, Saronikos gulf, Greece and were analysed for chlorinated organic pesticides (DDTs, HCB, Lindane) and polychlorinated biphenyls (PCBs). High total DDTs values were detected in all the sediments samples ranging from 9.1 to 75.6 mug/g, dry weight. PCBs concentrations range from 47.8 to 351.8 ng/g. The results and especially the high concentrations of DDTs reflect the influence of the industrial and urban wastes in the pollution for the Keratsini harbour environment.

Behavior of medically-derived 131I in the tidal Potomac River.

PubMed

Rose, Paula S; Smith, Joseph P; Cochran, J Kirk; Aller, Robert C; Swanson, R Lawrence

2013-05-01

Iodine-131 (t1/2=8.04 d) is administered to patients for treatment of thyroid disorders, excreted by patients and discharged to surface waters via sewage effluent. Radionuclides generally behave like their stable analogs; therefore, medically-derived (131)I is useful as a transport-reaction tracer of anthropogenic inputs and the aquatic biogeochemistry of iodine. Iodine-131 was measured in Potomac River water and sediments in the vicinity of the Blue Plains Water Pollution Control Plant (WPCP), Washington, DC, USA. Concentrations measured in sewage effluent from Blue Plains WPCP and in the Potomac River suggest a relatively continuous source of this radionuclide. The range of (131)I concentrations detected in surface water was 0.076±0.006 to 6.07±0.07 Bq L(-1). Iodine-131 concentrations in sediments ranged from 1.3±0.8 to 117±2 Bq kg(-1) dry weight. Partitioning in the sewage effluent from Blue Plains and in surface waters indicated that (131)I is associated with colloidal and particulate organic material. The behavior of medically-derived (131)I in the Potomac River is consistent with the nutrient-like behavior of natural iodine in aquatic environments. After discharge to the river via sewage effluent, it is incorporated into biogenic particulate material and deposited in sediments. Solid phase sediment profiles of (131)I indicated rapid mixing or sedimentation of particulate debris and diagenetic remineralization and recycling on short time scales. Copyright © 2013. Published by Elsevier B.V.

Sorption processes affecting arsenic solubility in oxidized surface sediments from Tulare Lake Bed, California

USGS Publications Warehouse

Gao, S.; Goldberg, S.; Herbel, M.J.; Chalmers, A.T.; Fujii, R.; Tanji, K.K.

2006-01-01

Elevated concentrations of arsenic (As) in shallow groundwater in Tulare Basin pose an environmental risk because of the carcinogenic properties of As and the potential for its migration to deep aquifers that could serve as a future drinking water source. Adsorption and desorption are hypothesized to be the major processes controlling As solubility in oxidized surface sediments where arsenate [As(V)] is dominant. This study examined the relationship between sorption processes and arsenic solubility in shallow sediments from the dry Tulare Lake bed by determining sorption isotherms, pH effect on solubility, and desorption-readsorption behavior (hysteresis), and by using a surface complexation model to describe sorption. The sediments showed a high capacity to adsorb As(V). Estimates of the maximum adsorption capacity were 92 mg As kg- 1 at pH 7.5 and 70 mg As kg- 1 at pH 8.5 obtained using the Langmuir adsorption isotherm. Soluble arsenic [> 97% As(V)] did not increase dramatically until above pH 10. In the native pH range (7.5-8.5), soluble As concentrations were close to the lowest, indicating that As was strongly retained on the sediment. A surface complexation model, the constant capacitance model, was able to provide a simultaneous fit to both adsorption isotherms (pH 7.5 and 8.5) and the adsorption envelope (pH effect on soluble As), although the data ranges are one order of magnitude different. A hysteresis phenomenon between As adsorbed on the sediment and As in solution phase was observed in the desorption-readsorption processes and differs from conventional hysteresis observed in adsorption-desorption processes. The cause is most likely due to modification of adsorbent surfaces in sediment samples upon extensive extractions (or desorption). The significance of the hysteresis phenomenon in affecting As solubility and mobility may be better understood by further microscopic studies of As interaction mechanisms with sediments subjected to extensive leaching in natural environments. ?? 2006 Elsevier B.V. All rights reserved.

The behavior of natural and anthropogenic osmium in Long Island Sound, an urban estuary in the eastern U.S.

NASA Astrophysics Data System (ADS)

Williams, Gwyneth; Marcantonio, Franco; Turekian, Karl K.

1997-04-01

The Os concentration and 187Os/ 186Os distributions in surface sediments of Long Island Sound (eastern U.S.) provide a way of determining the sources and estuarine transport of Os. The contribution of anthropogenic Os from sewer outfalls from the New York City region supplies a tracer with a characteristic 187Os/ 186Os of about 1. The Os concentration of the bulk surface sediment increases steeply moving toward New York City in the westernmost Sound and generally follows the concentration of organic carbon. The 187Os/ 186Os ratio of bulk surface sediment increases from west to east in the westernmost part of the Sound and is effectively constant in the central Sound. We interpret these results as indicating that the surface bulk sediments of the Sound contain a low 187Os/ 186Os component, perhaps as a reduced coating associated with organic remains from sewer outfalls. The acid hydrogen peroxide leach fraction has an average 187Os/ 186Os of 9.5 in the central Sound, significantly higher than both the bulk sediment value and the probable sea water value of about 8. The leach fraction in the westernmost part of the traverse is less radiogenic than the central Sound and follows the Os wsotope trend of the bulk sediment. Liquid effluent from a New York City sewer outfall contains 30 pg l -1 of dissolved Os with a 187Os/ 186Os of about 2.5, consistent with its being an end-member of the west-east sediment pattern recorded in the leach fractions of the westernmost cores. The leachable Os from the central Sound predominantly reflects Os in ferromanganese oxyhydroxide coatings from continentally derived sediments with 187Os/ 186Os ratios more radiogenic than seawater. The distribution patterns of anthropogenic and natural Os, with their characteristic isotopic signatures in the Sound, and the insights gained from the behavior of other particle-reactive species, indicates that very little Os in solution may pass through the estuarine gauntlet.

Studies on kinetics of water quality factors to establish water transparency model in Neijiang River, China.

PubMed

Li, Ronghui; Pan, Wei; Guo, Jinchuan; Pang, Yong; Wu, Jianqiang; Li, Yiping; Pan, Baozhu; Ji, Yong; Ding, Ling

2014-05-01

The basis for submerged plant restoration in surface water is to research the complicated dynamic mechanism of water transparency. In this paper, through the impact factor analysis of water transparency, the suspended sediment, dissolved organic matter, algae were determined as three main impactfactors for water transparency of Neijiang River in Eastern China. And the multiple regression equation of water transparency and sediment concentration, permanganate index, chlorophyll-a concentration was developed. Considering the complicated transport and transformation of suspended sediment, dissolved organic matter and algae, numerical model of them were developed respectively for simulating the dynamic process. Water transparency numerical model was finally developed by coupling the sediment, water quality, and algae model. These results showed that suspended sediment was a key factor influencing water transparency of Neijiang River, the influence of water quality indicated by chemical oxygen demand and algal concentration indicated by chlorophyll a were indeterminate when their concentrations were lower, the influence was more obvious when high concentrations are available, such three factors showed direct influence on water transparency.

Metabolic Potential of Microbial Genomes Reconstructed from a Deep-Sea Oligotrophic Sediment Metagenome

NASA Astrophysics Data System (ADS)

Tully, B. J.; Huber, J. A.; Heidelberg, J. F.

2016-02-01

The South Pacific Gyre (SPG) possesses the lowest rates of sedimentation, surface chlorophyll concentration and primary productivity in the global oceans, making it one of the most oligotrophic environments on earth. As a direct result of the low-standing biomass in surface waters, deep-sea sediments are thin and contain small amount of labile organic carbon. It was recently shown that the sediment column within the SPG is fully oxic through to the underlying basalt basement and may be representative of 9-37% of the global marine environment. In addition, it appears that approximately 50% of the total organic carbon is removed from the oligotrophic sediments within the first 20 centimeters beneath the sea floor (cmbsf). To understand the microbial processes that contribute to the removal of the labile organic matter, metagenomic sequencing and analysis was carried out on a sample of sediment collected from 0-5 cmbsf from SPG site 10 (U1369). Analysis of 9 partially reconstructed environmental genomes revealed that the members of the SPG surface sediment microbial community are phylogenetically distinct from surface/upper ocean organisms, with deep branches within the Alpha- and Gammaproteobacteria, Nitrospirae, Nitrospina, the phylum NC10, and several unique phylogenetic groups. Within these partially complete genomes there is evidence for microbially mediated metal (iron/manganese) oxidation and carbon fixation linked to the nitrification. Additionally, despite low sedimentation and hypothesized energy-limitation, members of the SPG microbial community had motility and chemotactic genes and possessed mechanisms for the utilization of high molecular weight organic matter, including exoproteases and peptide specific membrane transporters. Simultaneously, the SPG genomes showed a limited potential for the degradation of recalcitrant carbon compounds. Finally, the presence of putative genes with functions involved with denitrification and the consumption of C1 compounds suggest that there may be microenvironments in the surface sediments were microbes can deplete oxygen concentrations to hypoxic/anoxic levels. This study represents an important first analysis in understanding how microorganisms in oligotrophic sediments impact deep-sea carbon transformations.

Assessment of heavy metal impact on sediment quality of the Xiaoqinghe estuary in the coastal Laizhou Bay, Bohai Sea: inconsistency between two commonly used criteria.

PubMed

Zhuang, Wen; Gao, Xuelu

2014-06-15

Surface sediments in the Xiaoqinghe estuary, southwestern coastal Laizhou Bay, were examined to assess the bio-toxic risk of heavy metals (Cd, Cu, Ni, Pb and Zn) with the effects range-low and effects range-median guidelines (ERL-ERMs) and the concentration ratio of simultaneously extractable metals to acid volatile sulfides ([SEM]/[AVS]). Based on the ERL-ERM guidelines, bio-toxic effect caused by Cu, Ni, Pb and Zn could be expected in the riverine surface sediments of the Xiaoqinghe estuary; and the surface sediments in the marine area were in good quality and only Ni might cause bio-toxic effect occasionally. The AVS-SEM guidelines revealed that no bio-toxic effect could be caused by any of the studied metals in both the riverine and marine sediments, since there were excess sulfides in surface sediments which could form water-insoluble substances with free metal ions and reduce the bioavailability of heavy metals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fractionation and risk assessment of Fe and Mn in surface sediments from coastal sites of Sonora, Mexico (Gulf of California).

PubMed

Jara-Marini, Martín E; García-Camarena, Raúl; Gómez-Álvarez, Agustín; García-Rico, Leticia

2015-07-01

The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual > Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.

Concentration, composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar, Arabian Gulf.

PubMed

Soliman, Y S; Al Ansari, E M S; Wade, T L

2014-08-30

Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6 ng g(-1) to 1025 ng g(-1). The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe+Ant), (Flt/Flt+Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrocarbon pollution in the sediment from the Jarzouna-Bizerte coastal area of Tunisia (Mediterranean Sea).

PubMed

Zrafi-Nouira, I; Khedir-Ghenim, Z; Zrafi, F; Bahri, R; Cheraeif, I; Rouabhia, M; Saidane-Mosbahi, D

2008-06-01

This study investigated the presence and origin of hydrocarbon pollution in industrial waste water sediments found near the Jarzouna (Bizerte, Tunisia) oil refinery. Analyses of surface sediments (layer 1) and deep sediments (layer 2) showed that Total Hydrocarbon (TH) concentrations ranged from 602 +/- 7.638 microg/g in layer-1 to 1270 +/- 2.176 microg/g in layer-2. The results suggest that the deeper the sediment, the higher the level of total hydrocarbon found. The sedimentary Non Aromatic Hydrocarbon (NAH) and Aromatic Hydrocarbon (AH) concentrations ranged from 66.22 +/- 1.516 to 211.82 +/- 10.670 microg/g for NAH, and from 13.84 +/- 0.180 to 115.60 +/- 2.479 microg/g for AH. The high variability of these concentrations was associated with the location of the sediment collection sites. Aliphatic biomarker analysis revealed petroleum contamination close to the refinery rejection site, and biogenic sources further away. Petroleum contamination may be associated with increased industrial activity in the area of Jarzouna-Bizerte in the Mediterranean Sea.

Flocculation, heavy metals (Cu, Pb, Zn) and the sand-mud transition on the Adriatic continental shelf, Italy

USGS Publications Warehouse

George, D.A.; Hill, P.S.; Milligan, T.G.

2007-01-01

Across a limited depth range (5-10 m) on many continental shelves, the dominant sediment size changes from sand to mud. This important boundary, called the sand-mud transition (SMT), separates distinct benthic habitats, causes a significant change in acoustic backscatter, represents a key facies change, and delimits more surface-reactive mud from less surface-reactive sand. With the goal of improving dynamical understanding of the SMT, surficial sediments were characterized across two SMTs on the Adriatic continental shelf of Italy. Geometric mean diameter, specific surface area (SSA), mud fraction (<63 ??m) and heavy metal concentrations were all measured. The SMT related to the Tronto River is identified between 15 and 20 m water depth while the SMT associated with the Pescara River varies between 15 and 25 m water depth. The sediment properties correlate with a new, process-based sedimentological parameter that quantifies the fraction of the sediment in the seabed that was delivered as flocs. These correlations suggest that floc dynamics exert strong influence over sediment textural properties and metal concentrations. Relative constancy in the depth of the SMT along this portion of the margin and its lack of evolution over a period during which sediment input to the margin has dramatically decreased suggest that on the Adriatic continental shelf energy is the dominant control on the depth of the SMT. ?? 2006 Elsevier Ltd. All rights reserved.

Quantification of Surface Suspended Sediments along a River Dominated Coast with NOAA AVHRR and SeaWiFS Measurements: Louisiana, USA

NASA Technical Reports Server (NTRS)

Myint, S. W.; Walker, N. D.

2002-01-01

The ability to quantify suspended sediment concentrations accurately over both time and space using satellite data has been a goal of many environmental researchers over the past few decades This study utilizes data acquired by the NOAA Advanced Very High Resolution Radiometer (AVHRR) and the Orbview-2 Sea-viewing wide field-of-view (SeaWiFS) ocean colour sensor, coupled with field measurements to develop statistical models for the estimation of near-surface suspended sediment and suspended solids "Ground truth" water samples were obtained via helicopter, small boat and automatic water sampler within a few hours of satellite overpasses The NOAA AVHRR atmospheric correction was modified for the high levels of turbidity along the Louisiana coast. Models were developed based on the field measurements and reflectance/radiance measurements in the visible and near infrared Channels of NOAA-14 and Orbview-2 SeaWiFS. The best models for predicting surface suspended sediment concentrations were obtained with a NOAA AVHRR Channel 1 (580-680nm) cubic model, Channel 2 (725-1100 nm) linear mod$ and SeaWiFs Channel 6 (660-68Onm) power modeL The suspended sediment models developed using SeaWiFS Channel 5 (545-565 nm) were inferior, a result that we attribute mainly to the atmospheric correction technique, the shallow depth of the water samples and absorption effects from non-sediment water constituents.

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.

Current-use pesticides and organochlorine compounds in precipitation and lake sediment from two high-elevation national parks in the Western United States

USGS Publications Warehouse

Mast, M.A.; Foreman, W.T.; Skaates, S.V.

2007-01-01

Current-use pesticides (CUPs) and banned organochlorine compounds (OCCs) were measured in precipitation (snowpack and rain) and lake sediments from two national parks in the Western United States to determine their occurrence and distribution in high-elevation environments. CUPs frequently detected in snow were endosulfan, dacthal, and chlorothalonil in concentrations ranging from 0.07 to 2.4 ng/L. Of the OCCs, chlordane, hexachlorobenzene, and two polychlorinated biphenyl congeners were detected in only one snow sample each. Pesticides most frequently detected in rain were atrazine, carbaryl, and dacthal in concentrations from 3.0 to 95 ng/L. Estimated annual deposition rates in one of the parks were 8.4 ??g/m2 for atrazine, 9.9 ??g/m2 for carbaryl, and 2.6 ??g/m2 for dacthal, of which >85% occurred during summer. p,p'-DDE and p,p'-DDD were the most frequently detected OCCs in surface sediments from lakes. However, concentrations were low (0.12 to 4.7 ??g/kg) and below levels at which harmful effects for benthic organisms are likely to be observed. DDD and DDE concentrations in an age-dated sediment core suggest that atmospheric deposition of DDT and its degradates, and possibly other banned OCCs, to high-elevation areas have been decreasing since the 1970s. Dacthal and endosulfan sulfate were present in low concentrations (0.11 to 1.2 ??g/kg) and were the only CUPs detected in surface sediments. Both pesticides were frequently detected in snow, confirming that some CUPs entering high-elevation aquatic environments through atmospheric deposition are accumulating in lake sediments and potentially in aquatic biota as well. ?? 2007 Springer Science+Business Media, Inc.

Evaluating porewater polycyclic aromatic hydrocarbon-related toxicity at a contaminated sediment site using a spiked field-sediment approach.

PubMed

Hartzell, Sharon E; Unger, Michael A; Vadas, George G; Yonkos, Lance T

2018-03-01

Although the complexity of contaminant mixtures in sediments can confound the identification of causative agents of adverse biological response, understanding the contaminant(s) of primary concern at impacted sites is critical to sound environmental management and remediation. In the present study, a stock mixture of 18 polycyclic aromatic hydrocarbon (PAH) compounds was prepared to reflect the variety and relative proportions of PAHs measured in surface sediment samples collected from discrete areas of a historically contaminated industrial estuary. This site-specific PAH stock mixture was spiked into nontoxic in-system and out-of-system field-collected reference sediments in dilution series spanning the range of previously measured total PAH concentrations from the region. Spiked sediments were evaluated in 10-d Leptocheirus plumulosus tests to determine whether toxicity in laboratory-created PAH concentrations was similar to the toxicity found in field-collected samples with equivalent PAH concentrations. The results show that toxicity of contaminated sediments was not explained by PAH exposure, while indicating that toxicity in spiked in-system (fine grain, high total organic carbon [TOC]) and out-of-system (course grain, low TOC) sediments was better explained by porewater PAH concentrations, measured using an antibody-based biosensor that quantified 3- to 5-ring PAHs, than total sediment PAH concentrations. The study demonstrates the application of site-specific spiking experiments to evaluate sediment toxicity at sites with complex mixtures of multiple contaminant classes and the utility of the PAH biosensor for rapid sediment-independent porewater PAH analysis. Environ Toxicol Chem 2018;37:893-902. © 2017 SETAC. © 2017 SETAC.

Spatial-temporal distribution and potential ecological risk assessment of nonylphenol and octylphenol in riverine outlets of Pearl River Delta, China.

PubMed

Chen, Ru; Yin, Pinghe; Zhao, Ling; Yu, Qiming; Hong, Aihua; Duan, Shunshan

2014-11-01

The aquatic environments of the Pearl River Delta in Southern China are subjected to contamination with various industrial chemicals from local industries. In this paper, the occurrence, seasonal variation and spatial distribution of alkylphenol octylphenol (OP) and nonylphenol (NP) in river surface water and sediments in the runoff outlets of the Pearl River Delta were investigated. NP and OP were detected in all water and sediment samples and their mean concentrations in surface water during the dry season ranged from 810 to 3366 ng/L and 85.5 to 581 ng/L, respectively, and those in sediments ranged from 14.2 to 95.2 ng/g dw and 0.4 to 3.0 ng/g dw, respectively. In surface water, much higher concentrations were detected in the dry season than those in the wet season. In sediments, the concentrations in the dry season were also mostly higher. High concentrations of NP and OP were found in Humen outlet, likely due to high levels of domestic and industrial wastewater discharges. An ecological risk assessment with the use of hazard quotient (HQ) was also carried out and the HQ values ranged from 3.6×10(-5) to 35 and 64% of samples gave a HQ>1, indicating that the current levels of NP and OP pose a significant risk to the relevant aquatic organisms in the region. Copyright © 2014. Published by Elsevier B.V.

Temperature dependency of long-chain alkenone distributions in recent to fossil limnic sediments and in lake waters 1

NASA Astrophysics Data System (ADS)

Zink, Klaus-G.; Leythaeuser, Detlev; Melkonian, Michael; Schwark, Lorenz

2001-01-01

Distribution patterns of C 37 and C 38 polyunsaturated long-chain alkenones (LCAs) serve as proxies for the determination of paleotemperatures for marine surface waters. We studied Recent/Subrecent and Late Glacial/Holocene sediments from Germany, Austria, Russia, and the U.S. to test for a correspondence between LCA distribution and surface water temperature in limnic systems. Previously, reports of LCA occurrence were restricted to sediments of 6 wide distributed freshwater and alkaline lakes. In this study 13 of 27 investigated lakes contained LCAs in surface sediments with concentrations varying between 12 to 205 μg/g TOC. Late Glacial to Holocene sediment sequences from Lake Steisslingen and Lake Wummsee, (Germany), Lake Pichozero (Russia), and Brush Lake (U.S.A.) contained abundant LCAs with averaged concentrations of 33 to 7536 μg/g TOC. For the first time we observed the occurrence of LCAs within in the water column of oligotrophic Lake Stechlin (NE-Germany). Alkenones were restricted to the zone of maximum chlorophyll concentration within the water column indicating that LCAs have a biosynthetic origin and can be attributed to phototrophic (micro)algae. Attempts to identify the producing organism, however, were not successful. Culture experiments allow various phytoplankton to be excluded as producers. Alkenone-producing algae are evidently of small size, hindering microscopical identification. LCAs commonly occur in high concentrations in Late Glacial sediments, mainly during the cold period of the Younger Dryas, whereas the Holocene usually is devoid of polyunsaturated alkenones. The episodic occurrence of LCAs restricts their utility as proxies for continuous geological records. Furthermore, lack of microscopical verification and the episodic distribution allow for different producers of unsaturated alkenones in Recent and Late Glacial sediments. An empirical relationship between LCA distribution and temperature was observed. In fossil sediments from Lake Steisslingen, there is a good correspondence between Uk37 and the temperature-controlled δ 18O isotope ratio of lake chalk. Comparison of LCA patterns obtained from the uppermost centimetres of lake sediments with averaged summer surface water temperatures of the lakes studied, demonstrates a trend of covariance ( r2: Uk'37 = 0.90, Uk37 = 0.67; n = 9). Hence, the same mechanism that causes temperature-dependence of LCA patterns in marine systems might be effective in limnic settings. Identification of alkenone producers and their culture under controlled temperature are still mandatory before LCAs can be routinely applied as paleotemperature proxy in limnic systems.

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

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.

An operation manual for a time-series, storm-activated suspended sediment sampler deployed in the coastal ocean: function, maintenance, and testing procedures

USGS Publications Warehouse

Rendigs, Richard R.; Bothner, Michael H.

2004-01-01

This manual describes the operation and testing procedures for two models of a multi-port suspended sediment sampler that are moored in the coastal ocean and that collect samples on a programmable time schedule that can be interrupted to collect during a storm. The ability to sense and collect samples before, during, and after the height of a storm is a unique feature of these instruments because it provides samples during conditions when it is difficult or impossible to sample from a surface ship. The sensors used to trigger storm sampling are a transmissometer or a pressure sensor. The purpose of such samples is to assess composition and concentration of sediment resuspended from the seafloor during storms and subsequently transported within the coastal system. Both light transmission and the standard deviation of pressure from surface waves correlate with the passage of major storms. The instruments successfully identified the onset of storms and collected samples before, during, and after the storm maximum as programmed. The accuracy of determining suspended matter concentrations collected by the sediment sampler has not been fully evaluated. Preliminary laboratory tests using a suspension of muddy sediment collected in a near-bottom sediment trap yielded excellent results. However in laboratory tests with different sediment types, the suspended matter concentrations determined with these samplers became less accurate with increasing average grain size. Future calibration work is necessary and should be conducted in a facility that ideally has a water depth of at least 30 feet to prevent cavitation of the pump that draws sea water through the filters. The test facility should also have the capability for adding suspended matter of known composition and concentration to a fixed volume of seawater that is well mixed.

Spatial distribution of polycyclic aromatic hydrocarbon and polychlorinated biphenyl sources in the Nakdong River Estuary, South Korea.

PubMed

Lee, Jun H; Woo, Han J; Jeong, Kap S; Kang, Jeong W; Choi, Jae U; Jeong, Eun J; Park, Kap S; Lee, Dong H

2017-10-15

Our research team investigated the elemental composition and the presence of various toxic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), in estuary surface sediments to trace the spatial distribution of the sources of pollution deposited in Nakdong River, Busan, South Korea. The spatial patterns of elemental composition and toxic organic compounds were determined from the measurements of total organic carbon (TOC), total nitrogen, total sulfur, PAHs, and PCBs. The sediments had TOC contents of between 0.02 and 1.80 wt% (avg. 0.34 wt%), depending on the amount of clay-sized particles. The concentrations of PAHs and PCBs (10.8-167.7 ng g -1 dry wt and 197.0-754.0 pg g -1 dry wt, respectively) in surface sediments revealed different spatial patterns for these compounds, suggesting that they partially originated from the combustion of fossil fuels and from the use of commercial PCB products at adjacent industrial complexes. Although these concentrations were far below the Sediment Quality Guideline (SQG) of the National Oceanic and Atmospheric Administration (NOAA), the sediments at one site contained PCBs at concentrations close to the response level (754.0 pg g -1 dry wt), and were dominated by low-molecular-weight PAHs. The PAHs and PCBs in Nakdong River Estuary sediments were likely to have originated from the combustion of fossil fuels and biomass at the adjacent industrial complexes. The primarily analyzed results determined that PAHs originated from the combustion of fossil fuels and biomass, and overall concentrations were related to the contributions of individual PAHs in most sediment samples. Based on the SQG of the NOAA, our results indicate that the anthropogenic activity should be considered on the future-sustainable management of this estuary system.

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.

Pollution, toxicity, and ecological risk of heavy metals in surface river sediments of a large basin undergoing rapid economic development.

PubMed

Tang, Wenzhong; Zhang, Chao; Zhao, Yu; Shan, Baoqing; Song, Zhixin

2017-05-01

A comprehensive and detailed investigation of heavy metal pollution, toxicity, and ecological risk assessment was conducted for the surface river sediments of the Haihe Basin in China based on 220 sampling sites selected in 2013. The average concentrations of Cr, Cu, Ni, Pb, and Zn in the sediments were 129 mg/kg, 63.4 mg/kg, 36.6 mg/kg, 50.0 mg/kg, and 202 mg/kg, respectively. As indicated by the geoaccumulation and pollution load indices, most surface river sediments of the Haihe Basin were contaminated with the investigated metals, especially in the junction region of the Zi Ya He and Hei Long Gang watersheds. The 5 heavy metals in the sediments all had anthropogenic sources, and the enrichment degrees followed the order Cu > Pb > Zn > Cr > Ni, with mean enrichment factors of 3.27, 2.77, 2.58, 1.81, and 1.44, respectively. According to the mean index of comprehensive potential ecological risk (38.9), the studied sediments of the Haihe Basin showed low potential ecological risk, but the sediments were potentially biologically toxic based on the mean probable effect concentration quotient (0.547), which may be the result of speciation of the 5 metals in the sediments. The results indicate that heavy metal pollution should be considered during the development of ecological restoration strategies in the Haihe Basin. Environ Toxicol Chem 2017;36:1149-1155. © 2016 SETAC. © 2016 SETAC.

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

Inorganic geochemistry of surface sediments of the Ebro shelf and slope, northwestern Mediterranean

USGS Publications Warehouse

Gardner, J.V.; Dean, W.E.; Alonso, B.

1990-01-01

Distributions of major, minor, and trace elements in surface sediment of the continental shelf and upper slope of the northeastern Spanish continental margin reflect the influences of discharge from the Ebro River and changes in eustatic sea levels. Multivariate factor analysis of sediment geochemistry was used to identify five groupings of samples (factors) on the shelf and slope. The first factor is an aluminosilicate factor that represents detrital clastic material. The second factor is a highly variable amount of excess SiO2 and probably represents a quartz residuum originating from winnowing of relict detrital sediments. A carbonate factor (Factor 3) has no positive correlation with other geochemical parameters but is associated with the sand-size fraction. The carbonate in these sediments consists of a mixture of biogenic calcite and angular to subangular detrital grains. Organic carbon is associated with the aluminosilicate factor (Factor 1) but also factors out by itself (Factor 4); this suggests that there may be two sources of organic matter, terrestrial and marine. The fifth factor comprises upper slope sediments that contain high concentrations of manganese. The most likely explanation for these high manganese concentrations is precipitation of Mn oxyhydroxides at the interface between Mn-rich, oxygen-deficient, intermediate waters and oxygenated surface waters. During eustatic low sea levels of the glacial Pleistocene, the Ebro Delta built across the outer continental shelf and deposited sediment with fairly high contents of organic carbon and continental components. The period of marine transgression from eustatic low (glacial) to eustatic high (interglacial) sea levels was characterized by erosion of the outer shelf delta and surficial shelf sediments and the transport of sediment across the slope within numerous canyons. Once eustatic high sea level was reached, delta progradation resumed on the inner shelf. Today, coarse-grained sediment (silt and sand) is transported to the continental shelf by Ebro River and is distributed along the inner shelf by currents generated by dominant northeasterly winds. Clay-size material is deposited on the mid- and outer-shelf. However, erosion and delta progradation during the last glacial period, and fine-grained Holocene sedimentation, have probably produced a distribution of sediment on a diachronous surface. ?? 1990.

Levels of metals and semimetals in sedimentary cores in Bertioga Channel, Brazil

NASA Astrophysics Data System (ADS)

Sartoretto, J. R.; Salaroli, A.; Figueira, R. C.

2013-05-01

The Baixada Santista is one of the most exploited and populated regions of São Paulo state. During the last decades, due to intense industrialization the Baixada Santista has passed through a strong process of environmental degradation. Metals in sediments are persistent, present toxicity in varied concentrations and may be deposited reaching biota habitats. In this context, high concentrations of metals represent environmental concern to costal management. Bertioga Channel is part of this complex system and is known mainly by a wide adjacent mangrove area. The channel is 25 km long, connecting the upstream region of Santos estuary to the adjacent ocean through an inlet located at the city of Bertioga. Urban development generates the concern of potential waste influx from surrounding streams, generating deposits and contaminating surface sediments along the channel, which may lead to adjacent coastal issues. The objective of this study was to characterize the concentration of the following metals at Bertioga Channel sediments: Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sc, V and Zn. Five sediment cores were sampled along the channel and analyzed. Determination of metals concentration was based on methods SW 846 US EPA 3050B and EPA 7471. High As concentrations were observed at all cores, with considerable concentration similarity between the first and second sampling points. Analytical results showed that cores Bertioga 4 and Bertioga 5 have accumulated high quantity of metals and semimetals, mainly As, Cd and Cr. Normalization of concentration values showed low contamination at the cores. Nevertheless, As and Hg values indicated moderate to significant contamination at a few sampling points. Despite of the low probability of contamination demonstrated by the normalized values, increasing at the sediment surface of Enrichment Factor (ER), Pollution Load Index (PLI) and Sediment Pollution Index (SPI) parameters were observed. Results indicate that industrialization process and environmental degradation at the region are acting for the last decades.

Estimating selenium removal by sedimentation from the Great Salt Lake, Utah

USGS Publications Warehouse

Oliver, W.; Fuller, C.; Naftz, D.L.; Johnson, W.P.; Diaz, X.

2009-01-01

The mass of Se deposited annually to sediment in the Great Salt Lake (GSL) was estimated to determine the significance of sedimentation as a permanent Se removal mechanism. Lake sediment cores were used to qualitatively delineate sedimentation regions (very high to very low), estimate mass accumulation rates (MARs) and determine sediment Se concentrations. Sedimentation regions were defined by comparison of isopach contours of Holocene sediment thicknesses to linear sedimentation rates determined via analysis of 210Pb, 226Ra, 7Be and 137Cs activity in 20 short cores (<5 cm), yielding quantifiable results in 13 cores. MARs were developed via analysis of the same radioisotopes in eight long cores (>10 cm). These MARs in the upper 1-2 cm of each long core ranged from 0.019 to 0.105 gsed/cm2/a. Surface sediment Se concentrations in the upper 1 or 2 cm of each long core ranged from 0.79 to 2.47 mg/kg. Representative MARs and Se concentrations were used to develop mean annual Se removal by sedimentation in the corresponding sedimentation region. The spatially integrated Se sedimentation rate was estimated to be 624 kg/a within a range of uncertainty between 285 and 960 kg/a. Comparison to annual Se loading and other potential removal processes suggests burial by sedimentation is not the primary removal process for Se from the GSL. ?? 2009 Elsevier Ltd.

Status, distribution and ecological risk of organochlorines (OCs) in the surface sediments from the Ravi River, Pakistan.

PubMed

Syed, Jabir Hussain; Malik, Riffat Naseem; Li, Jun; Chaemfa, Chakra; Zhang, Gan; Jones, Kevin C

2014-02-15

Organochlorines (OCs) including organochlorine pesticides (OCPs) and polychlorinated biphenyl (PCBs) were analyzed in surface sediments from the Ravi River, Punjab, Pakistan. Among the OCPs, hexachlorocyclohexane (HCHs), dichlorodiphenyltrichloroethane (DDTs) and chlordane (cis- and trans-) were most abundant and their concentrations were ranged from n.d to 16.0 ng g(-1), 1.5 to 58.5 ng g(-1) and n.d to 29.0 ng g(-1), respectively. Concentrations of Σ31PCBs ranged from 4.6 to 424.3 ng g(-1) with a mean value of 48.9 ng g(-1). In general, the concentrations of all studied organochlorines (OCs) in sediments collected from the sampling sites in the vicinity of industrial areas were higher than those from the agricultural areas. Compositional analyses of PCBs indicated that penta- and tetra-PCBs homologues were dominant which was consistent with the previous studies. Compared with other areas around the world, levels of OCs in sediments from the Ravi River were within the range, but were found to be much higher than previously reported from Pakistan. According to established sediment quality guidelines (SQGs), screening-level risk assessment of OCPs and PCBs suggested that they have a potential for adverse effects on benthic organisms. Copyright © 2013 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Evaluating a 5-year metal contamination remediation and the biomonitoring potential of a freshwater gastropod along the Xiangjiang River, China.

PubMed

Li, Deliang; Pi, Jie; Zhang, Ting; Tan, Xiang; Fraser, Dylan J

2018-05-16

Effective remediation of heavy metal pollution in aquatic systems is desired in many regions, but it requires integrative assessments of sediments, water, and biota that can serve as robust biomonitors. We assessed the effects of a 5-year metal contamination remediation along the Xiangjiang River, China, by comparing concentrations of trace metals in water and surface sediments between 2010-2011 and 2016. We also explored the trace metal biomonitoring potential of a freshwater gastropod (Bellamya aeruginosa). Metal concentrations in water (means and ranges) dropped over time to within permissible limits of drinking water guidelines set by China, USEPA, and WHO in 2016. Although sediment means and ranges of Cd, Pb, Zn, and Mn also diminished with remediation, those for Cr and Cu slightly increased, and all six metals retained concentrations higher than standards set by China. All metals in sediments could also be associated with anthropogenic inputs using a hierarchical clustering analysis, and they generate high potential ecological risks based on several indices, especially for Cd and As. The bio-sediment accumulation factors of all measured trace metals in gastropod soft tissues and shells were lower than 1.0, except for Ca. Trace metal contents in gastropods were positively correlated with those in water and surface sediments for As (soft tissues) and Cr (shells). Collectively, our results do not yet highlight strong beneficial effects of 5-year remediation and clearly illustrate the heavy metal pollution remaining in Xiangjiang River sediment. Additional physical, chemical, and biological measurements should be implemented to improve sediment quality. We further conclude that gastropod soft tissues and shells can be suitable biomonitors of spatial differences in some heavy metals found within river sediments (e.g., As, Cr).

Spatial variation of acid-volatile sulfide and simultaneously extracted metals in Egyptian Mediterranean Sea lagoon sediments.

PubMed

Younis, Alaa M; El-Zokm, Gehan M; Okbah, Mohamed A

2014-06-01

In risk assessment of aquatic sediments, the immobilizing effect of acid-volatile sulfide (AVS) on trace metals is a principal control on availability and associated toxicity of metals to aquatic biota, which reduces metal bioavailability and toxicity by binding and immobilizing metals as insoluble sulfides. Spatial variation pattern of AVS, simultaneously extracted metals (SEM), and sediment characteristics were studied for the first time in surface sediment samples (0-20 cm) from 43 locations in Egyptian northern delta lagoons (Manzalah, Burullus, and Maryut) as predictors of the bioavailability of some divalent metals (Cu, Zn, Cd, Pb, and Ni) in sediments as well as indicators of metal toxicity in anaerobic sediments. The results indicated that the ∑SEM (Cu + Zn + Cd + Pb + Ni) values in sediments of lagoon Burullus had higher concentrations than those of Maryut and Manzalah. In contrast, AVS concentrations were considerably higher in lagoons Manzalah and Maryut and seemed to be consistent with the increase in organic matter than lagoon Burullus. Generally, the average concentrations of the SEM in all lagoons were in the order of Zn > Cu > Ni > Pb > Cd. The ratios of ∑SEM/AVS were less than 1 at all the sampling stations except at one station in lagoon Maryut as well as four stations located in lagoon Burullus (∑SEM/AVS > 1), which suggests that the metals have toxicity potential in these sediments. Therefore, SEM concentrations probably are better indicators of the metal bioavailability in sediments than the conventional total metal concentrations.

Occurrence, distribution, and volume of metals-contaminated sediment of selected streams draining the Tri-State Mining District, Missouri, Oklahoma, and Kansas, 2011–12

USGS Publications Warehouse

Smith, D. Charlie

2016-12-14

Lead and zinc were mined in the Tri-State Mining District (TSMD) of southwest Missouri, northeast Oklahoma, and southeast Kansas for more than 100 years. The effects of mining on the landscape are still evident, nearly 50 years after the last mine ceased operation. The legacies of mining are the mine waste and discharge of groundwater from underground mines. The mine-waste piles and underground mines are continuous sources of trace metals (primarily lead, zinc, and cadmium) to the streams that drain the TSMD. Many previous studies characterized the horizontal extent of mine-waste contamination in streams but little information exists on the depth of mine-waste contamination in these streams. Characterizing the vertical extent of contamination is difficult because of the large amount of coarse-grained material, ranging from coarse gravel to boulders, within channel sediment. The U.S. Geological Survey, in cooperation with U.S. Fish and Wildlife service, collected channel-sediment samples at depth for subsequent analyses that would allow attainment of the following goals: (1) determination of the relation between concentration and depth for lead, zinc and cadmium in channel sediments and flood-plain sediments, and (2) determination of the volume of gravel-bar sediment from the surface to the maximum depth with concentrations of these metals that exceeded sediment-quality guidelines. For the purpose of this report, volume of gravel-bar sediment is considered to be distributed in two forms, gravel bars and the wetted channel, and this study focused on gravel bars. Concentrations of lead, zinc, and cadmium in samples were compared to the consensus probable effects concentration (CPEC) and Tri-State Mining District specific probable effects concentration (TPEC) sediment-quality guidelines.During the study, more than 700 sediment samples were collected from borings at multiple sites, including gravel bars and flood plains, along Center Creek, Turkey Creek, Shoal Creek, Tar Creek, and Spring River in order to characterize the vertical extent of mine waste in select streams in the TSMD. The largest concentrations of lead, zinc, and cadmium in gravel bar-sediment samples generally were detected in Turkey Creek and Tar Creek and the smallest concentrations were detected in Shoal Creek followed by the Spring River. Gravel bar-sediment samples from Turkey Creek exceeded the CPEC for cadmium (minimum of 70 percent of samples), lead (94 percent), and zinc (99 percent) at a slightly higher frequency than similar samples from Tar Creek (69 percent, 88 percent, and 96 percent, respectively). Gravel bar-sediment samples from Turkey Creek also contained the largest concentrations of cadmium (174 milligrams per kilogram [mg/kg]) and lead (7,520 mg/kg) detected; however, the largest zinc concentration (46,600 mg/kg) was detected in a gravel bar-sediment sample from Tar Creek. In contrast, none of the 65 gravel bar-sediment samples from Shoal Creek contained cadmium above the x-ray fluorescence reporting level of 12 mg/kg, and lead and zinc exceeded the CPEC in only 12 percent and 74 percent of samples, respectively. In most cases, concentrations of lead and zinc above the CPEC or TPEC were present at the maximum depth of boring, which indicated that nearly the entire thickness of sediment in the stream has been contaminated by mine wastes. Approximately 284,000 cubic yards of channel sediment from land surface to the maximum depth that exceeded the CPEC and approximately 236,000 cubic yards of channel sediment from land surface to the maximum depth that exceeded the TPEC were estimated along 37.6 of the 55.1 miles of Center Creek, Turkey Creek, Shoal Creek, and Tar Creek examined in this study. Mine-waste contamination reported along additional reaches of these streams is beyond the scope of this study. Flood-plain cores collected in the TSMD generally only had exceedances of the CPEC and TPEC for lead and zinc in the top 1 or 2 feet of soil with a few exceptions, such as cores in low areas near the stream or cores in areas disturbed by past mining.

Sewage contamination in the upper Mississippi River as measured by the fecal sterol, coprostanol

USGS Publications Warehouse

Writer, J.H.; Leenheer, J.A.; Barber, L.B.; Amy, G.L.; Chapra, S.C.

1995-01-01

The molecular sewage indicator, coprostanol, was measured in bed sediments of the Mississippi River for the purpose of determining sewage contamination. Coprostanol is a non-ionic, non-polar, organic molecule that associates with sediments in surface waters, and concentrations of coprostanol in bed sediments provide an indication of long-term sewage loads. Because coprostanol concentrations are dependent on particle size and percent organic carbon, a ratio between coprostanol (sewage sources) and cholestanol + cholesterol (sewage and non-sewage sources) was used to remove the biases related to particle size and percent organic carbon. The dynamics of contaminant transport in the Upper Mississippi River are influenced by both hydrologic and geochemical parameters. A mass balance model incorporating environmental parameters such as river and tributary discharge, suspended sediment concentration, fraction of organic carbon, sedimentation rates, municipal discharges and coprostanol decay rates was developed that describes coprostanol concentrations and therefore, expected patterns of municipal sewage effects on the Upper Mississippi River. Comparison of the computed and the measured coprostanol concentrations provides insight into the complex hydrologic and geochemical processes of contaminant transport and the ability to link measured chemical concentrations with hydrologic characteristics of the Mississippi River.

Influence of anthropogenic activities on PAHs in sediments in a significant gulf of low-latitude developing regions, the Beibu Gulf, South China Sea: distribution, sources, inventory and probability risk.

PubMed

Li, Pingyang; Xue, Rui; Wang, Yinghui; Zhang, Ruijie; Zhang, Gan

2015-01-15

Fifteen polycyclic aromatic hydrocarbons (PAHs) in 41 surface sediment samples and a sediment core (50 cm) from the Beibu Gulf, a significant low-latitude developing gulf, were analyzed. PAHs concentrations were 3.01-388 ng g(-)(1) (mean 95.5 ng g(-)(1)) in the surface sediments and 10.5-87.1 ng g(-)(1) (average 41.1 ng g(-)(1)) in the sediment core. Source apportionment indicated that PAHs were generated from coke production and vehicular emissions (39.4%), coal and biomass combustion (35.8%), and petrogenic sources (24.8%). PAHs were mainly concentrated in the industrialized and urbanized regions and the harbor, and were transported by atmospheric deposition to the marine matrix. The mass inventory (1.57-2.62t) and probability risk showed sediments here served as an important reservoir but low PAH risk. Different from oil and natural gas in developed regions, coal combustion has always been a significant energy consumption pattern in this developing region for the past 30 years (56 ± 5%). Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of heavy metals in sediment of Aguamilpa Dam, Mexico.

PubMed

Rangel-Peraza, Jesús Gabriel; de Anda, José; González-Farías, Fernando A; Rode, Michael; Sanhouse-García, Antonio; Bustos-Terrones, Yaneth A

2015-03-01

The Aguamilpa Dam is part of the reservoir cascade system formed by four reservoirs in the middle and lower part of the Santiago River. For decades, this system has received urban and industrial wastewater from the metropolitan area of Guadalajara and the runoff of agricultural fields located in the river basin. The present study was carried out to obtain a preliminary assessment on the concentration distribution of heavy metals (Al, Ba, Cd, Cr, Cu, Fe, Hg, Mg, Ni, Pb, and Zn) in surface sediments of the Aguamilpa reservoir collected from 10 sampling stations. The metal concentrations (mg kg(-1)) in the sampling stations ranged as follows: Al, 27,600-7760; Ba, 190.0-15.9; Cd, 0.27-0.02; Cr, 18.30-0.22; Cu, 60.80-0.79; Fe, 15,900-4740; Hg, 0.04-0.01; Mg, 7590-8.05; Ni, 189.00-0.24; Pb, 13.6-1.64; and Zn, 51.8-14.8. Significant spatial variation in concentrations was observed for Al, Fe, and Pb. Sediment pollution was evaluated using the enrichment factor, the geo-accumulation index, the pollution load index, and sediment quality guidelines. Based on geo-accumulation and pollution load indexes, Aguamilpa sediments were found, in some sampling stations, as unpolluted to moderately polluted with Ni, Cd, Cu, and Mg. Enrichment factors showed that Cd is highly related to agricultural activities that take place in the surrounding areas of the Aguamilpa reservoir. Despite these results, none of the heavy metals evaluated exceeded international concentrations limits, indicating that the Aguamilpa reservoir surface sediments are not contaminated.

Effect of various electrokinetic treatment regimes on solids surface properties and thermal behavior of oil sediments.

PubMed

Kariminezhad, Esmaeel; Elektorowicz, Maria

2018-04-10

The electrokinetic process has shown its ability to separate the different material phases. However, not much is known about the effect of the electric fields on the surface properties of solids in the oil sediments and their behavior under different electrical regimes. In this study, the effect of four different types of electrical current on the surface properties of oil sediments was investigated, namely constant direct current (CDC), pulsed direct current (PDC), incremental direct current (IDC) and decremental direct current (DDC). X-ray photoelectron spectroscopy (XPS) analyses showed a decrease in the concentration of carbon from 99% in centrifuged samples to 63% on the surface of the solids in the PDC-treated oil sediment. Wettability alteration and contact angle studies showed an enhance in hydrophilicity of the solids following electrokinetic treatment. A significant change in carbon and oxygen-containing functionalities at the surface solids of the DDC-treated sediment was also observed. Thermogravimetric analyses (TGA) confirmed the ability of electrokinetic treatment in separating the phases by shifting the thermogram profiles towards lower temperatures. The findings showed that the electrokinetic process exerts its effect by altering the surface properties of the sediment solids and destabilizing water-in-oil emulsions to facilitate phase separation of this complex waste. Copyright © 2018 Elsevier B.V. All rights reserved.

Toward an understanding of "Legacy P" - phosphorus sorption mechanisms in stream sediments as influenced by organic matter

NASA Astrophysics Data System (ADS)

Audette, Yuki; O'Halloran, Ivan P.; Nowell, Peter M.; Congreves, Katelyn; Voroney, R. Paul

2017-04-01

Water chemistry and phosphorus (P) forms were analyzed to determine the nature of legacy P in sediments of the West Holland River and the adjacent drainage canals of the Holland Marsh drainage system, located in southern Ontario, Canada. The river and canals route water from the intensively cropped muck polders of the Holland Marsh and drain Lake Simcoe. Sediment samples were characterized for mineralogy using X-ray diffraction techniques (XRD); total P (TP); and Ca, Fe, Mn, and Mg contents, as well as cation exchange capacity and organic matter (OM) content. Forms of sediment P in five depth sections (ranging from 0-15 cm depth) were characterized and quantified by sequential P fractionation chemistry. At all study sites, mobile P forms including organic P forms were found to be higher in surface sediments than in deeper sediments. The major P form within the sediments of the two canal sites, where the concentration of TP in the surface water was within the Ontario Provincial Water Quality Objectives (PWQO) of 0.03 mg P L-1, was Ca-bound P, indicating a low risk of soluble reactive P (SRP) release. A trace of apatite (a stable Ca-P mineral) was also detected in these sediments. Conversely, sediments collected from the West Holland River at sites located within the Holland Marsh exhibited a high risk of SRP release, and redox-sensitive P was the dominant P form in the sediment despite the surface water exhibiting higher concentration of Ca and alkaline pH. In addition, the concentrations of TP as measured in surface water samples taken from the site were 8 times greater than PWQO. In the sediments where the risk of SRP release was high, OM contents were also relatively high and traces of brushite (a labile Ca-P mineral) were detected. The formation of OM and cation complexes, such as OM-Fe complexes, may play an important role in regulating the fate of sediment-P forms through the adsorption of SRP. These OM-Fe complexes may inhibit the formation of more stable Ca-P minerals, even under neutral to alkaline conditions. Thus, where OM-Fe-P forms predominate, we predict a high risk of SRP release from sediments when water chemistry changes. In addition, OM may inhibit the transformation of labile Ca-P forms to more stable Ca-P minerals. Loading of OM affects the development of hypoxia in aquatic systems, and the accumulation of OM can promote the release of both SRP and dissolved organic C to downstream environments. This study provides evidence that the presence of OM in stream sediments influences P sorption mechanisms and is critical in understanding P biogeochemistry in freshwater environments.

Distribution and relationships of selected trace metals in molluscs and associated sediments from the Gulf of Aden, Yemen.

PubMed

Szefer, P; Ali, A A; Ba-Haroon, A A; Rajeh, A A; Gełdon, J; Nabrzyski, M

1999-09-01

Concentrations of Cd, Pb, Zn, Cu, Ni, Co, Cr, Mn and Fe in the soft tissue of Turbo coronatus, Acanthopleura haddoni, Ostrea cucullata and Pitar sp., as well as in associated surface sediments (bulk and bioavailable metal concentrations) from the Gulf of Aden, Yemen, were determined by atomic absorption spectrophotometry method. Large differences between size-classes of molluscs in metal concentrations were recorded. Significant spatial differences in metal concentrations in both the soft tissue of the molluscs and associated sediments studied were mostly identified. Statistically significant correlations (p<0.01) between concentrations of selected metals were observed. A slope of the linear regression is significantly higher than unity for Fe (9.91) and Cd (3.45) in A. haddoni and for Ni (4.15) in T. coronatus, suggesting that the bioavailability of these metals is disproportionally increased with a degree of enrichment of the sediments in Fe, Cd and Ni, respectively. A slope constant approximating to unity (1.14) for Cu in A. haddoni relative to its concentration in sediment extract implies that bioavailability of this metal proportionally increased with growing concentrations of its labile forms in the associated sediment. The degree of contamination of Gulf of Aden waters by the metals studied is discussed and the potential ability of molluscs, especially A. haddoni and T. coronatus, as biomonitors of metallic pollutants is postulated.

Hydrogen concentrations as an indicator of the predominant terminal electron-accepting reactions in aquatic sediments

USGS Publications Warehouse

Lovley, D.R.; Goodwin, S.

1988-01-01

Factors controlling the concentration of dissolved hydrogen gas in anaerobic sedimentary environments were investigated. Results, presented here or previously, demonstrated that, in sediments, only microorganisms catalyze the oxidation of H2 coupled to the reduction of nitrate, Mn(IV), Fe(III), sulfate, or carbon dioxide. Theoretical considerations suggested that, at steady-state conditions, H2 concentrations are primarily dependent upon the physiological characteristics of the microorganism(s) consuming the H2 and that organisms catalyzing H2 oxidation, with the reduction of a more electrochemically positive electron acceptor, can maintain lower H2 concentrations than organisms using electron acceptors which yield less energy from H2 oxidation. The H2 concentrations associated with the specified predominant terminal electron-accepting reactions in bottom sediments of a variety of surface water environments were: methanogenesis, 7-10 nM; sulfate reduction, 1-1.5 nM; Fe(III) reduction, 0.2 nM; Mn(IV) or nitrate reduction, less than 0.05 nM. Sediments with the same terminal electron acceptor for organic matter oxidation had comparable H2 concentrations, despite variations in the rate of organic matter decomposition, pH, and salinity. Thus, each terminal electron-accepting reaction had a unique range of steady-state H2 concentrations associated with it. Preliminary studies in a coastal plain aquifer indicated that H2 concentrations also vary in response to changes in the predominant terminal electron-accepting process in deep subsurface environments. These studies suggest that H2 measurements may aid in determining which terminal electron-accepting reactions are taking place in surface and subsurface sedimentary environments. ?? 1988.

Assessing trace metal pollution through high spatial resolution of surface sediments along the Tunis Gulf coast (southwestern Mediterranean).

PubMed

Ennouri, Rym; Zaaboub, Noureddine; Fertouna-Bellakhal, Mouna; Chouba, Lassad; Aleya, Lotfi

2016-03-01

Tunis Gulf (northern Tunisia, Mediterranean Sea) is of great economic importance due to its abundant fish resources. Rising urbanization and industrial development in the surrounding area have resulted in an increase in untreated effluents and domestic waste discharged into the gulf via its tributary streams. Metal (Cd, Pb, Hg, Cu, Zn, Fe, and Mn) and major element (Mg, Ca, Na, and K) concentrations were measured in the grain fine fraction <63 μm by atomic absorption spectrophotometry. Results showed varying spatial distribution patterns for metals, indicating complex origins and controlling factors such as anthropogenic activities. Sediment metal concentrations are ranked as follows: Fe > Mg > Zn > Mn > Pb > Cu > Cd > Hg. Metals tend to be concentrated in proximity to source points, suggesting that the mineral enrichment elements come from sewage of coastal towns and pollution from industrial dumps and located along local rivers, lagoons, and on the gulf shore itself. This study showed that trace metal and major element concentrations in surface sediments along the Tunis Gulf shores were lower than those found in other coastal areas of the Mediterranean Sea.

The correlation and quantification of airborne spectroradiometer data to turbidity measurements at Lake Powell, Utah

NASA Technical Reports Server (NTRS)

Merry, C. J.

1979-01-01

A water sampling program was accomplished at Lake Powell, Utah, during June 1975 for correlation to multispectral data obtained with a 500-channel airborne spectroradiometer. Field measurements were taken of percentage of light transmittance, surface temperature, pH and Secchi disk depth. Percentage of light transmittance was also measured in the laboratory for the water samples. Analyses of electron micrographs and suspended sediment concentration data for four water samples located at Hite Bridge, Mile 168, Mile 150 and Bullfrog Bay indicated differences in the composition and concentration of the particulate matter. Airborne spectroradiometer multispectral data were analyzed for the four sampling locations. The results showed that: (1) as the percentage of light transmittance of the water samples decreased, the reflected radiance increased; and (2) as the suspended sediment concentration (mg/l) increased, the reflected radiance increased in the 1-80 mg/l range. In conclusion, valuable qualitative information was obtained on surface turbidity for the Lake Powell water spectra. Also, the reflected radiance measured at a wavelength of 0.58 micron was directly correlated to the suspended sediment concentration.

Acidification of lake water due to drought

NASA Astrophysics Data System (ADS)

Mosley, L. M.; Zammit, B.; Jolley, A. M.; Barnett, L.

2014-04-01

Droughts are predicted to increase in many river systems due to increased demand on water resources and climate variability. A severe drought in the Murray-Darling Basin of Australia from 2007 to 2009 resulted in unprecedented declines in water levels in the Lower Lakes (Ramsar-listed ecosystem of international importance) at the end of the river system. The receding water exposed large areas (>200 km2) of sediments on the lake margins. The pyrite (FeS2) in these sediments oxidised and generated high concentrations of acidity. Upon rewetting of the exposed sediments, by rainfall or lake refill, surface water acidification (pH 2-3) occurred in several locations (total area of 21.7 km2). High concentrations of dissolved metals (Al, As, Co, Cr, Cu, Fe, Mn, Ni, Zn), which greatly exceeded aquatic ecosystem protection guidelines, were mobilised in the acidic conditions. In many areas neutralisation of the surface water acidity occurred naturally during lake refill, but aerial limestone dosing was required in two areas to assist in restoring alkalinity. However acidity persists in the submerged lake sediment and groundwater several years after surface water neutralisation. The surface water acidification proved costly to manage and improved water management in the Murray-Darling Basin is required to prevent similar events occurring in the future.

A simple pore water hydrogen diffusion syringe sampler

USGS Publications Warehouse

Vroblesky, D.A.; Chapelle, F.H.; Bradley, P.M.

2007-01-01

Molecular hydrogen (H2) is an important intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H 2 are often diagnostic of the predominant terminal electron-accepting processes in ground water systems or aquatic sediments. H2 concentrations are routinely measured in ground water monitoring wells but are rarely measured in saturated aquatic sediments due to a lack of simple and practical sampling methods. This report describes the design and development (including laboratory and field testing) of a simple, syringe-based H 2 sampler in (1) saturated, riparian sediments, (2) surface water bed sediments, and (3) packed intervals of a fractured bedrock borehole that are inaccessible by standard pumped methods. ?? 2007 National Ground Water Association.

Trace metal concentrations in tropical mangrove sediments, NE Brazil.

PubMed

Miola, Brígida; Morais, Jáder Onofre de; Pinheiro, Lidriana de Souza

2016-01-15

Sediment cores were taken from the mangroves of the Coreaú River estuary off the northeast coast of Brazil. They were analyzed for grain size, CaCO3, organic matter, and trace metal (Cd, Pb, Zn, Cu, Al, and Fe) contents. Mud texture was the predominant texture. Levels of trace metals in surface sediments indicated strong influence of anthropogenic processes, and diagenetic processes controlled the trace metal enrichment of core sediments of this estuary. The positive relationships between trace metals and Al and Fe indicate that Cu, Zn, Pb, and Cd concentrations are associated mainly with Al and Fe oxy-hydroxides and have natural sources. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

USGS Publications Warehouse

Bergamaschi, B.A.; Tsamakis, E.; Keil, R.G.; Eglinton, T.I.; Montlucon, D.B.; Hedges, J.I.

1997-01-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays. Copyright ?? 1997 Elsevier Science Ltd.

The effect of grain size and surface area on organic matter, lignin and carbohydrate concentration, and molecular compositions in Peru Margin sediments

NASA Astrophysics Data System (ADS)

Bergamaschi, Brian A.; Tsamakis, Elizabeth; Keil, Richard G.; Eglinton, Timothy I.; Montluçon, Daniel B.; Hedges, John I.

1997-03-01

A C-rich sediment sample from the Peru Margin was sorted into nine hydrodynamically-determined grain size fractions to explore the effect of grain size distribution and sediment surface area on organic matter content and composition. The neutral monomeric carbohydrate composition, lignin oxidation product yields, total organic carbon, and total nitrogen contents were determined independently for each size fraction, in addition to sediment surface area and abundance of biogenic opal. The percent organic carbon and percent total nitrogen were strongly related to surface area in these sediments. In turn, the distribution of surface area closely followed mass distribution among the textural size classes, suggesting hydrodynamic controls on grain size also control organic carbon content. Nevertheless, organic compositional distinctions were observed between textural size classes. Total neutral carbohydrate yields in the Peru Margin sediments were found to closely parallel trends in total organic carbon, increasing in abundance among grain size fractions in proportion to sediment surface area. Coincident with the increases in absolute abundance, rhamnose and mannose increased as a fraction of the total carbohydrate yield in concert with surface area, indicating these monomers were preferentially represented in carbohydrates associated with surfaces. Lignin oxidation product yields varied with surface area when normalized to organic carbon, suggesting that the terrestrially-derived component may be diluted by sorption of marine derived material. Lignin-based parameters suggest a separate source for terrestrially derived material associated with sand-size material as opposed to that associated with silts and clays.

Composition, distribution, and hydrologic effects of contaminated sediments resulting from the discharge of gold milling wastes to Whitewood Creek at Lead and Deadwood, South Dakota

USGS Publications Warehouse

Goddard, K.E.

1989-01-01

The Whitewood Creek-Belle Fourche-Cheyenne River stream system in western South Dakota has been extensively contaminated by the discharge to Whitewood Creek of about 100 million tons of mill tailings from gold-mining operations. The resulting contaminated sediments contain unusually large concentrations of arsenic, as much as 11,000 micrograms/g, derived from the mineral arsenopyrite, as well as potentially toxic constituents derived from the ore-body minerals or from the milling processes. Because of the anomalous arsenic concentrations associated with the contamination, arsenic was used as an indicator for a geochemically based, random, sediment-sampling program. Arsenic concentrations in shallow, contaminated sediments along the flood plains of the streams were from 1 to 3 orders of magnitude larger than arsenic concentrations in uncontaminated sediments in about 75% of the flood plains of Whitewood Creek and the Belle Fourche River. Appreciable surface-water contamination resulting from the contaminated sediments is confined to Whitewood Creek and a reach of the Belle Fourche River downstream from the mouth of Whitewood Creek. In Whitewood Creek , dissolved-arsenic concentrations vary from about 20 to 80 microgram/L during the year in response to variations in groundwater inflow and dilution, whereas total-recoverable-arsenic concentrations vary from about 20 to 8 ,000 micrograms/L during short periods in response to rapid changes in suspended-sediment concentration. Contamination of the alluvial aquifer along the stream system is limited to areas in direct contact with large deposits of contaminated sediments. Within the aquifer, arsenic concentrations are thought to be controlled by sorption-desorption on metallic hydroxides. (USGS)

Accumulation and trace-metal variability of estuarine sediments, St. Bernard delta geomorphic region, Louisiana

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

Landrum, K.E.

1995-10-01

Prior to government regulation, little monitoring of metal discharges into the canals, bayous, and rivers that drain estuarine systems occured. Discharges of trace-metals by industries and municipalities into surface water bodies are presently regulated through the use of Federal and State mandated permit programs. Resource management of economically important estuarine systems has fostered increasing concern over the accumulation of trace-metal pollutants in water, sediments, and biota from these dynamic areas. The acid-leachable concentrations of fourteen trace-metals were determined for 125 bottom sediment samples and 50 core interval samples by plasma emission analysis. Bottom sediments of the St. Bernard estuarom complexmore » consist predominantly of silty clays and clayey silts derived from the erosion of the St. Bernard lobe of the Mississippi River delta and sediments associated with historic crevasses along the Mississippi River. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Trace-metal concentrations from sediments for the study area tend to have greater mean concentrations than Florida estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology. Rates varied from 0.12 to 0.21 cm/yr. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Natural trace-metal variability was examined through the use of an aluminum normalization model based on Florida and Louisiana estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology, and grain-size corrected data. Elevated concentrations of As, Ba, Cd, Pb, V and Zn were noted from sediments associated with oil and gas drilling and production, sandblasting and shipbuilding, dredging, and stormwater, municipal, and industrial discharges.« less

Recent Trends in Suspended Sediment Load & Water Quality in the Upper Chesapeake Bay

NASA Astrophysics Data System (ADS)

Freeman, L. A.; Ackleson, S. G.

2016-02-01

The Chesapeake Bay spans several major cities on the US east coast and drains a large watershed (164,200 km2) to the Atlantic Ocean. Upstream deforestation and agriculture have led to a major decline in water quality (increased sediment and nutrient load) of the Bay over the past century. Sediment flux into the Chesapeake Bay is a natural process, but has become an environmental concern as land use changes have exacerbated natural suspended sediment loads and saturated the capacity of the estuary to filter and remove sediments. In situ measurements of suspended sediments and surface reflectance from the Potomac, Patapsco, and Severn River were used to develop algorithms that convert surface reflectance from Landsat (1-3, 4-5, 7, 8) imagery to suspended sediment concentration for the entire Chesapeake Bay. A unique time series of suspended sediment load in the Chesapeake Bay was compiled from Landsat imagery dating from 1977-2015. Particular focus is given to the upper Chesapeake Bay near Washington, DC and Baltimore, MD to understand urban effects. In particular, the Potomac, Patapsco, and Severn River are examined from both remote sensing and in situ measurements. Landsat imagery combined with in situ monitoring provides environmental scientists and resource managers with detailed trends in sediment distribution and concentration, a key measure of water quality. Trends of suspended sediment load in several rivers and the upper Chesapeake Bay will be presented, along with a discussion of suspended sediment algorithms for Landsat imagery. Advantages of Landsat 8 (improved signal-to-noise performance and more bands) versus previous sensors will be examined for suspended sediment applications.

Effect of sediment composition on methane concentration and production in the transition zone of a mangrove (Sepetiba Bay, Rio de Janeiro, Brazil).

PubMed

Marinho, C C; Campos, E A; Guimarães, J R D; Esteves, F A

2012-08-01

The aim of this research was to evaluate the effect of sediment composition on methane (CH4) dynamics in sediments of different areas in the transition zone between a mangrove and the sea. This research was conducted in a mangrove at Coroa Grande, on the southern coast of Rio de Janeiro. Samples were collected at three stations: (1) region colonised by Rhizophora mangle L. on the edge of the mangrove, (2) region colonised by seagrasses and (3) infra-littoral region without vegetation. Samples were collected from the surface layer of the sediment to determine the concentrations of nutrients (C, N and P) and CH4 concentration and production. We observed that concentrations of CH4 and carbon (C) were significantly higher (p < 0.05) in station 1 than station 3. The molar ratios (C:N, C:P and N:P) suggest that the origin of the substrate is mainly autochthonous. Methanogenesis was initially low, possibly due to competition between methanogens and sulfate reducers, and increased significantly (p < 0.05) on the twenty-sixth day in the sediment of station 1, probably due to higher organic matter (OM) availability in this region. Results indicate that methanogenic activity observed herein is not regulated by the amount or quality of OM, but by other factors. The concentration of CH4 in the sea-land ecotone at Mangrove Coroa Grande is a function of available OM suggesting a possible inhibition of methanotrophy by intense oxygen consumption in the soil surface covered by detritus of Rhizophora mangle vegetation.

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

PubMed

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

2017-06-15

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

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

Polycyclic aromatic hydrocarbons in surface sediment of typical estuaries and the spatial distribution in Haihe river basin.

PubMed

Liu, Jing L; Zhang, Jing; Liu, Feng; Zhang, Lu L

2014-05-01

Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic and mutagenic characteristics have been detected in many estuaries and bays around the world. To detect the contaminated level in typical estuaries in Haihe river basin, China, a comprehensive survey of 16 PAHs in surface sediment has been conducted and an ecological risk assessment has been taken. It showed that Haihe river estuary had the highest concentration, ranging from 92.91 to 15886.00 ng g(-1). And Luan river estuary has the lowest polluted level, ranging from 39.55 to 328.10 ng g(-1). PAHs in sediment were dominated by low and mid molecular weight PAHs in all the sampling sites. Most of the sampling sites in all sampling seasons indicated a rarely happened ecological risk of ΣPAHs, while the S6 in Haihe river estuary was in an occasionally anticipated risk. To illustrate the spatial distribution pattern of PAHs in surface sediment in Haihe river basin, the results were compared with previous research of the research team. Based on data of the comparison, it had been revealed that Haihe river had the most serious PAHs pollution, with an average concentration of 5884.86 ng g(-1), and showed the highest contamination level in all four ecological units. The ΣPAHs concentration showed in a rank of reservoir > estuary > rural area > city.

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).

Florida seagrass habitat evaluation: A comparative survey for chemical quality

EPA Science Inventory

Contaminant concentrations were determined for media associated with 13 Florida seagrass beds. Concentrations of 10 trace metals were more commonly detected in surface water, sediment and two seagrass species than PAHs, pesticides and PCBs. Concentrations of copper and arsenic ...

Mercury Concentrations in Coastal Sediment from Younger Lagoon, Central California

NASA Astrophysics Data System (ADS)

Hohn, R. A.; Ganguli, P. M.; Swarzenski, P. W.; Richardson, C. M.; Merckling, J.; Johnson, C.; Flegal, A. R.

2013-12-01

Younger Lagoon Reserve, located in northern Monterey Bay, is one of the few relatively undisturbed wetlands that remain along the Central Coast of California. This lagoon system provides protected habitat for more than 100 bird species and for populations of fish, mammals, and invertebrates. Total mercury (HgT) concentrations in water within Younger Lagoon appear to vary with rainfall conditions and range from about 5-15 pM. These concentrations are similar to HgT in water from six nearby lagoon systems. However, Younger Lagoon contains elevated concentrations of dissolved organic carbon (~1 mM) and monomethylmercury (MMHg, ~1 pM) relative to our comparison lagoon sites (DOC < 0.5 mM and MMHg < 0.5 pM). We attribute Younger Lagoon's high DOC and MMHg to its restricted connection to the ocean and minor riverine contribution. Coastal lagoons in this region typically form at the mouth of streams. They behave as small estuaries during the wet season when surface water discharge keeps the mouth of the stream open to the ocean, and then transition into lagoons in the dry season when a sand berm develops and effectively cuts off surface water exchange. At Younger Lagoon, the sand berm remains intact throughout the year, breaching only during particularly high tides or intense rain events. Therefore, the lagoon's connection to nearshore seawater is primarily via surface water - groundwater interaction through the sand berm. Because Younger Lagoon is largely isolated from a surface water connection with the ocean, runoff from upgradient urban and agricultural land has an enhanced impact on water (and presumably sediment) quality. As a result, the lagoon is eutrophic and experiences annual algal blooms. Groundwater surveys suggest surface water, groundwater, and coastal seawater are hydraulically connected at Younger Lagoon, and mixing among these water masses appears to influence water geochemistry. To date, no chemical analyses have been conducted on sediment from Younger Lagoon. To address this data gap we collected sediment samples during a February 2013 field campaign. One set of sediment samples is from the bottom of the lagoon along a transect perpendicular to the shoreline and another set is from an approximately 1 m depth profile on the lagoon side of the sand berm (depth of the groundwater table at the time of collection). These samples are being analyzed for HgT, MMHg, and total organic carbon (TOC) and will provide a first glimpse into the distribution of mercury species and organic carbon in sediments from the Younger Lagoon Reserve. We will also collect and analyze sediment samples from another lagoon site with comparable watershed characteristics.

Assessing the occurrence and distribution of pyrethroids in water and suspended sediments

USGS Publications Warehouse

Hladik, M.L.; Kuivila, K.M.

2009-01-01

The distribution of pyrethroid insecticides in the environment was assessed by separately measuring concentrations in the dissolved and suspended sediment phases of surface water samples. Filtered water was extracted by HLB solid-phase extraction cartridges, while the sediment on the filter was sonicated and cleaned up using carbon and aluminum cartridges. Detection limits for the 13 pyrethroids analyzed by gas chromatography-tandem mass spectrometry were 0.5 to 1 ng L-1 for water and 2 to 6 ng g for the suspended sediments. Seven pyrethroids were detected in six water samples collected from either urban or agricultural creeks, with bifenthrin detected the most frequently and at the highest concentrations. In spiked water samples and field samples, the majority of the pyrethroids were associated with the suspended sediments.

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.

Metal accumulation in the greentail prawn, Metapenaeus bennettae, in Sydney and Port Hacking estuaries, Australia.

PubMed

Lewtas, K L M; Birch, G F; Foster-Thorpe, C

2014-01-01

Metal concentrations of the inshore greentail prawn, Metapenaeus bennettae, and surface sediments from locations within Sydney estuary and Port Hacking (Australia) were assessed for bioaccumulation and contamination. The current study aimed to assess metal concentrations in prawn tissue (tail muscle, exoskeleton, hepatopancreas and gills), relate whole body prawn tissue metal concentrations to sediment metal concentrations and animal size, as well as assess prawn consumption as a risk to human health. Metal concentrations were highest in sediment and prawns from contaminated locations (Iron Cove, Hen and Chicken Bay and Lane Cove) in Sydney estuary compared with the reference estuary (Port Hacking). Concentrations in sediments varied considerably between sites and between metals (As, Cd, Cr, Cu, Ni, Pb and Zn), and although concentrations exceeded Interim Sediment Quality Guideline-Low values, metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were below Australian National Health and Medical Research Council human consumption guidelines in prawn tail muscle tissue. Metal concentrations in prawn tail muscle tissue were significantly different (p ≤ 0.05) amongst locations for Pb, Zn and Cd, and metal concentrations were generally highest in gills tissue, followed by the hepatopancreas, exoskeleton and tail muscle. The exoskeleton contained the highest Sr concentration; the hepatopancreas contained the highest As, Cu and Mo concentrations; and the gills contained the highest Al, Cr, Fe and Pb concentrations. Concentrations of Pb, As and Sr were significantly different (p ≤ 0.05) between size groups amongst locations.

Decadal Comparisons of Particulate Matter in Repeat Transects in the Atlantic, Pacific, and Indian Ocean Basins

NASA Astrophysics Data System (ADS)

Gardner, W. D.; Mishonov, A. V.; Richardson, M. J.

2018-01-01

Basin-wide sections of beam cp (proxy for particle concentration) in ocean basins collected during numerous oceanographic programs over the last four decades record variable concentrations in euphotic surface waters, very low concentrations through most of the water column, and very low to very high concentrations near the seafloor. Sections resampled at decadal intervals show that intense benthic nepheloid layers (BNLs) recur in the same general locations in these repeat sections, most often where eddy kinetic energy (EKE: cm2 s-2) is high in overlying waters. Areas beneath regions of low surface EKE consistently have weak to no BNLs. The decadal persistence of the close connection between surface and benthic EKE and presence or absence of BNLs is clear. Understanding the location and causes of intense versus weak BNLs helps in assessing scavenging of adsorption-prone elements in the deep sea and quantifying the impact of deep ocean sediment dynamics on sediment redistribution.

The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifer

USGS Publications Warehouse

Kent, D.B.; Fox, P.M.

2004-01-01

We examined the chemical reactions influencing dissolved concentrations, speciation, and transport of naturally occurring arsenic (As) in a shallow, sand and gravel aquifer with distinct geochemical zones resulting from land disposal of dilute sewage effluent. The principal geochemical zones were: (1) the uncontaminated zone above the sewage plume [350 ??M dissolved oxygen (DO), pH 5.9]; (2) the suboxic zone (5 ??M DO, pH 6.2, elevated concentrations of sewage-derived phosphate and nitrate); and (3) the anoxic zone [dissolved iron(II) 100-300 ??M, pH 6.5-6.9, elevated concentrations of sewage-derived phosphate]. Sediments are comprised of greater than 90% quartz but the surfaces of quartz and other mineral grains are coated with nanometer-size iron (Fe) and aluminum (Al) oxides and/or silicates, which control the adsorption properties of the sediments. Uncontaminated groundwater with added phosphate (620 ??M) was pumped into the uncontaminated zone while samples were collected 0.3 m above the injection point. Concentrations of As(V) increased from below detection (0.005 ??M) to a maximum of 0.07 ??M during breakthrough of phosphate at the sampling port; As(III) concentrations remained below detection. These results are consistent with the hypothesis that naturally occurring As(V) adsorbed to constituents of the coatings on grain surfaces was desorbed by phosphate in the injected groundwater. Also consistent with this hypothesis, vertical profiles of groundwater chemistry measured prior to the tracer test showed that dissolved As(V) concentrations increased along with dissolved phosphate from below detection in the uncontaminated zone to approximately 0.07 and 70 ??M, respectively, in the suboxic zone. Concentrations of As(III) were below detection in both zones. The anoxic zone had approximately 0.07 ??M As(V) but also had As(III) concentrations of 0.07-0.14 ??M, suggesting that release of As bound to sediment grains occurred by desorption by phosphate, reductive dissolution of Fe oxides, and reduction of As(V) to As(III), which adsorbs only weakly to the Fe-oxide-depleted material in the coatings. Results of reductive extractions of the sediments suggest that As associated with the coatings was relatively uniformly distributed at approximately 1 nmol/g of sediment (equivalent to 0.075 ppm As) and comprised 20%-50% of the total As in the sediments, determined from oxidative extractions. Quartz sand aquifers provide high-quality drinking water but can become contaminated when naturally occurring arsenic bound to Fe and Al oxides or silicates on sediment surfaces is released by desorption and dissolution of Fe oxides in response to changing chemical conditions. ?? 2004 American Institute of Physics.

Alkylphenols in Surface Sediments of the Gulf of Gdansk (Baltic Sea).

PubMed

Koniecko, Iga; Staniszewska, Marta; Falkowska, Lucyna; Burska, Dorota; Kielczewska, Joanna; Jasinska, Anita

2014-01-01

The widespread use of alkylphenols in European industry has led to their presence in the environment and the living organisms of the Baltic Sea. The present study (2011-2012) was designed to determine the concentrations of alkylphenols, 4-nonylphenol (NP) and 4- tert -octylphenol (OP), in surface sediments of the Gulf of Gdansk, a section of the Baltic that lies in close proximity to industrial and agricultural areas and borders with an agglomeration of nearly one million inhabitants. It is also where the Vistula, the largest Polish river, ends its course. In spring, large concentrations of 4-nonylphenol and 4- tert -octylphenol were washed off into the coastal zone with meltwater. In summertime, sediments near the beach had the highest alkylphenol concentrations (NP-2.31 ng g -1 dw, OP-13.09 ng g -1 dw), which was related to tourism and recreational activity. In silt sediments located off the coast, the highest NP (1.46 ng g -1 dw) and OP (6.56 ng g -1 dw) amounts were observed in autumn. The origin of OP and NP at those test stations was linked to atmospheric transport of black carbon along with adsorbed alkylphenols.

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.

Ecological risk assessment of heavy metals in surface seawater and sediment near the outlet of a zinc factory in Huludao City, Liaoning Province, China

NASA Astrophysics Data System (ADS)

Feng, Yongliang; Chen, Yanzhen; Wang, Jing; Gong, Yufeng; Liu, Xigang; Mu, Gang; Tian, Hua

2016-11-01

At present, the methods widely applied to assess ecological risk of heavy metals are essentially single-point estimates in which exposure and toxicity data cannot be fully used and probabilities of adverse biological eff ects cannot be achieved. In this study, based on investigation of concentrations of six heavy metals (As, Hg, Pb, Cd, Cu, and Zn) in the surface seawater and sediment near the outlet of a zinc factory, located in Huludao City, Liaoning Province, China, a tiered approach consisting of several probabilistic options was used to refine ecological risk assessment for the individuals. A mixture of various heavy metals was detected in the surface seawater, and potential ecological risk index (PERI) was adopted to assess the potential ecological risk of heavy metals in the surface sediment. The results from all levels of aquatic ecological risk assessment in the tiered framework, ranging from comparison of single eff ects and exposure values to the use of distribution-based Hazard Quotient obtained through Monte Carlo simulation, are consistent with each other. Briefly, aquatic Zn and Cu posed a clear ecological risk, while Cd, Pb, Hg, and As in the water column posed potential risk. As expected, combined ecological risk of heavy metal mixture in the surface seawater was proved significantly higher than the risk caused by any individual heavy metal, calculated using the concept of total equivalent concentration. According to PERI, the severity of pollution by the six heavy metals in the surface sediment decreased in the following sequence: Cd>Hg>As>Pb>Cu>Zn, and the total heavy metals in the sediment posed a very high risk to the marine environment. This study provides a useful mathematical framework for ecological risk assessment of heavy metals.

Arsenic associations in sediments from shallow aquifers of northwestern Hetao Basin, Inner Mongolia

USGS Publications Warehouse

Deng, Y.; Wang, Y.; Ma, T.; Yang, H.; He, J.

2011-01-01

Understanding the mechanism of arsenic mobilization from sediments to groundwater is important for water quality management in areas of endemic arsenic poisoning, such as the Hetao Basin in Inner Mongolia, northern China. Aquifer geochemistry was characterized at three field sites (SH, HF, TYS) in Hangjinhouqi County of northwestern Hetao Basin. The results of bulk geochemistry analysis of sediment samples indicated that total As concentrations have a range of 6. 8-58. 5 mg/kg, with a median of 14. 4 mg/kg. The highest As concentrations were found at 15-25 m depth. In the meanwhile, the range of As concentration in the sediments from background borehole is 3-21. 8 mg/kg, with a median value of 9 mg/kg. The As sediments concentrations with depth from the SH borehole were correlated with the contents of Fe, Sb, B, V, total C and total S. Generally, the abundance of elements varied with grain size, with higher concentrations in finer fractions of the sediments. Distinct lithology profile and different geochemical characteristics of aquifer sediments indicate the sediments are associated with different sources and diverse sedimentary environments. Up to one third of arsenic in the sediments could be extracted by ammonium oxalate, suggesting that Fe oxyhydroxides may be the major sink of As in the aquifer. Sequential extraction results indicate that arsenic occurs as strongly adsorbed on and/or co-precipitated with amorphous Fe oxyhydroxides in sediments accounting for 35 and 20%, respectively, of the total contents of arsenic. The release of As into groundwater may occur by desorption from the mineral surface driven by reductive dissolution of the Fe oxide minerals. Furthermore, small proportions of As associated with iron sulfides occur in the reductive sediments. ?? 2011 Springer-Verlag.

Estimation and influence of physicochemical properties and chemical fractions of surface sediment on the bioaccessibility of Cd and Hg contaminant in Langat River, Malaysia.

PubMed

Kadhum, Safaa A; Ishak, Mohd Yusoff; Zulkifli, Syaizwan Zahmir

2017-10-01

This study applied the use of sequential extraction technique and simple bioaccessibility extraction test to quantify the bioavailable fractions and the human bioaccessible concentration of metals collected from nine stations in surface sediment of the Langat River. The concentrations of total and bioaccessible metals from different stations were in the range of 0.49-1.04, 0.10-0.32 μg g -1 for T-Cd, Bio-Cd, respectively, and 12.9-128.03, 2.06-8.53 μg kg -1 for T-Hg, Bio-Hg, respectively. The results revealed highest R-Bio-Cd in Banting station (55.3 %), while the highest R-Bio-Hg was in Kajang station (49.61 %). The chemical speciation of Cd in most sampling stations was in the order of oxidisable-organic > residual > exchangeable > acid-reducible, while speciation of Hg was in the order of exchangeable > residual > oxidisable-organic > acid-reducible. The correlation matric of mean content showed that the TOM, particle size and Mg ++ in polluted surface sediments was highly correlated with total mercury. The PCA showed that the main factors influencing the bioaccessibility of Hg in surface sediments were the sediment TOM, F1 (EFLE) and F3 (oxidation-organic), while the factor influencing the bioaccessibility of Cd was the F3 (oxidation-organic) and T-Cd.

Mercury speciation in sediments at a municipal sewage sludge marine disposal site.

PubMed

Shoham-Frider, E; Shelef, G; Kress, N

2007-12-01

Mercury speciation was performed in excess activated sewage sludge (ASS) and in marine sediments collected at the AAS disposal site off the Mediterranean coast of Israel in order to characterize the spatial and vertical distribution of different mercury species and assess their environmental impact. Total Hg (HgT) concentrations ranged between 0.19 and 1003ng/g at the polluted stations and 5.7 and 72.8ng/g at the background station, while the average concentration in ASS was 1181+/-273ng/g. Only at the polluted stations did HgT concentrations decrease exponentially with sediment depth, reaching background values at 16-20cm, the vertical distribution resulting from mixing of natural sediment with ASS solids and bioturbation by large populations of polycheates. Average Methyl Hg (MeHg) concentration in ASS was 39.7+/-7.1ng/g, ca. 3% of the HgT concentration, while the background concentrations ranged between 0.1 and 0.61ng/g. MeHg concentrations in surficial polluted sediments were 0.7-5.9ng/g (ca. 0.5% of the HgT) and decreased vertically, similar to HgT. A positive correlation between MeHg and Hg only at the polluted stations, higher MeHg concentrations at the surface of the sediment and not below the redoxline, and no seasonality in the concentrations suggest that the MeHg originated from the ASS and not from in situ methylation. By doing selective extractions, we found that ca. 80% of the total Hg in ASS and polluted sediments was strongly bound to amorphous organo-sulfur and to inorganic sulfide species that are not bioavailable. The fractions with potential bioaccessible Hg had maximal concentrations in the range in which biotic effects should be expected. Therefore, although no bioaccumulation was found in the biota in the area, the concentration in the polluted sediments are not negligible and should be carefully monitored.

The Contribution of Opal-Associated Phosphorus to Bioavailable Phosphorus in Surface and Core Sediments in the East China Sea

NASA Astrophysics Data System (ADS)

Li, Huanxin; He, Huijun; Yang, Shifeng; Liu, Yanli; Che, Hong; Li, Mujian; Zhang, Jing

2018-06-01

To improve the burial flux calculations of bioavailable phosphorus (P) and study opal-associated P (Opal-P) in the East China Sea (ECS), surface and core sediments were collected in the Changjiang Estuary (CE) and the south of the Cheju Island. In this study, sedimentary P was operationally divided into seven different forms using modified sedimentary extraction (SEDEX) technique: LSor-P (exchangeable or loosely sorbed P), Fe-P (easily reducible or reactive ferric Fe-bound P), CFA-P (authigenic carbonate fluorapatite and biogenic apatite and CaCO3-bound P), Detr-P (detrital apatite), Org-P (organic P), Opal-P and Ref-P (refractory P). The data revealed that the concentrations of the seven different P forms rank as Detr-P > CFA-P > Org-P > Ref-P > Opal-P > Fe-P > LSor-P in surface sediments and CFA-P > Detr-P > Org-P > Ref-P > Fe-P > Opal-P > LSor-P in core sediments. The distributions of the total phosphorus (TP), TIP, CFA-P, Detr-P are similar and decrease from the CE to the south of the Cheju Island. Meanwhile, Org-P and Opal-P exhibit different distribution trends; this may be affected by the grain size and TOM. The concentrations of potentially bioavailable P are 9.6-13.0 μmol g-1 and 10.0-13.6 μmol g-1, representing 61%-70% and 41%-64% of the TP in surface and core sediments, respectively. The concentrations of Opal-P are 0.6-2.3 μmol g-1 and 0.6-1.4 μmol g-1 in surface and core sediments, accounting for 5.3%-19.8% and 4.2%-10.6% of bioavailable P, respectively. The total burial fluxes of Opal-P and bioavailable P are 1.4×109 mol yr-1 and 1.1×1010 mol yr-1 in the ECS, respectively. Opal-P represents about 12.7% of potentially bioavailable P, which should be recognized when studying P cycling in marine ecosystems.

Impact of concentration and species of sulfamethoxazole and ofloxacin on their adsorption kinetics on sediments.

PubMed

Wang, Peng; Zhang, Di; Zhang, Huang; Li, Hao; Ghosh, Saikat; Pan, Bo

2017-05-01

Antibiotics are used widely in human and veterinary medicine and are ubiquitous in environmental matrices worldwide. The influence of the concentration of antibiotics on adsorption kinetics is still unclear. This study used sulfamethoxazole (SMX) and ofloxacin (OFL) as adsorbates to investigate the adsorption kinetics on sediment affected by varying concentrations of antibiotics adsorbable species. At the experimental pH values, the major adsorbed species of SMX and OFL on sediment were SMX 0 and OFL + by hydrophobic interaction and electrostatic attraction, respectively. The apparent adsorption rate of SMX was not affected by the initial concentration and the pH values because the hydrophobic interactions were concentration-independent and charge-independent. However, the apparent adsorption rate of OFL significantly slowed down as the initial concentration increased. The adsorbed OFL + effectively neutralized the negative charges of the sediment, leading to a reduced adsorption rate of subsequent OFL + . The neutralization effect was greatly enhanced due to the increased OFL + with the increasing OFL concentration. Additionally, the apparent adsorption rate of OFL significantly increased at higher pH due to the reduced neutralization effect that resulted from the decreased OFL + and increased negative charges of the sediment surface. This study implied that the adsorption kinetics of antibiotics was greatly dominated by the concentration of adsorbable species rather than apparent overall concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmental controls on the speciation and distribution of mercury in surface sediments of a tropical estuary, India.

PubMed

Chakraborty, Parthasarathi; Babu, P V Raghunadh

2015-06-15

Distribution and speciation of mercury (Hg) in the sediments from a tropical estuary (Godavari estuary) was influenced by the changing physico-chemical parameters of the overlying water column. The sediments from the upstream and downstream of the estuary were uncontaminated but the sediments from the middle of the estuary were contaminated by Hg. The concentrations of Hg became considerably less during the monsoon and post monsoon period. Total Hg concentrations and its speciation (at the middle of the estuary) were dependent on the salinity of the overlying water column. However, salinity had little or no effect on Hg association with organic phases in the sediments at downstream. Increasing pH of the overlying water column corresponded with an increase in the total Hg content in the sediments. Total organic carbon in the sediments played an important role in controlling Hg partitioning in the system. Uncomplexed Hg binding ligands were available in the sediments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatial and temporal trends in poly- and per-fluorinated compounds in the Laurentian Great Lakes Erie, Ontario and St. Clair.

PubMed

Codling, Garry; Sturchio, Neil C; Rockne, Karl J; Li, An; Peng, H; Tse, Timothy J; Jones, Paul D; Giesy, John P

2018-06-01

The temporal and spatial trends in sediment of 22 poly- and perfluorinated (PFAS) compounds were investigated in the southern Great Lakes Erie and Ontario as well as Lake St. Clair. Surface concentrations measured by Ponar grab samples indicated a trend for greater concentrations near to urban sites. Mean concentrations ∑ 22 PFAS were 15.6, 18.2 and 19 ng g -1 dm for Lakes St. Clair, Erie and Ontario, respectively. Perfluoro-n-butanoic acid (PFBA) and Perfluoro-n-hexanoic acid (PFHxA) were frequently determined in surface sediment and upper core samples indicating a shift in use patterns. Where PFBA was identified it was at relatively great concentrations typically >10 ng g -1 dm. However as PFBA and PFHxA are less likely to bind to sediment they may be indicative of pore water concentrations Sedimentation rates between Lake Erie and Lake Ontario differ greatly with greater rates observed in Lake Erie. In Lake Ontario, in general concentrations of PFAS observed in core samples closely follow the increase in use along with an observable change due to regulation implementation in the 1970s for water protection. However some of the more water soluble PFAS were observed in deeper core layers than the time of production could account for, indicating potential diffusion within the sediment. Given the greater sedimentation rates in Lake Erie, it was hoped to observe in greater resolution changes since the mid-1990s. However, though some decrease was observed at some locations the results are not clear. Many cores in Lake Erie had clearly observable gas voids, indicative of gas ebullition activity due to biogenic production, there were also observable mussel beds that could indicate mixing by bioturbation of core layers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of geology on arsenic concentrations in ground and surface water in central Lesvos, Greece.

PubMed

Aloupi, Maria; Angelidis, Michael O; Gavriil, Apostolos M; Koulousaris, Michael; Varnavas, Soterios P

2009-04-01

The occurrence of As was studied in groundwater used for human consumption and irrigation, in stream water and sediments and in water from thermal springs in the drainage basin of Kalloni Gulf, island of Lesvos, Greece, in order to investigate the potential influence of the geothermal field of Polichnitos-Lisvori on the ground and surface water systems of the area. Total dissolved As varied in the range <0.7-88.3 microg L(-1) in groundwater, 41.1-90.7 microg L(-1) in thermal spring water and 0.4-13.2 microg L(-1) in stream water, whereas As concentrations in stream sediments varied between 2.0-21.9 mg kg(-1). Four out of 31 groundwater samples exceeded the EC standard of 10 microg L(-1). The survey revealed an enrichment in both surface and groundwater hydrological systems in the northern part of the area (average concentrations of As in groundwater, stream water and stream sediment: 8.0 microg L(-1), 8.8 microg L(-1) and 15.0 mg kg(-1) respectively), in association with the volcanic bedrocks, while lower As concentrations were found in the eastern part (average concentrations in groundwater, stream water and stream sediment: 2.9 microg L(-1), 1.7 microg L(-1) and 5.9 mg kg(-1) respectively), which is dominated by ophiolitic ultramafic formations. The variation of As levels between the different parts of the study area suggests that local geology exerts a determinant influence on As geochemical behaviour. On the other hand, the geothermal activity manifested in the area of Polichnitos-Lisvori does not affect the presence of As in groundwater and streams.

[Accumulation, distribution and pollution assessment of heavy metals in surface sediment of Caohai plateau wetland, Guizhou province].

PubMed

Zhang, Qing-Hai; Lin, Chang-Hu; Tan, Hong; Lin, Shao-Xia; Yang, Hong-Bo

2013-03-01

The objective of this paper is to investigate the concentrations and distribution characteristics of heavy metals in surface sediments of different areas in the Caohai plateau wetland. 16 samples of surface sediments were collected and 7 heavy metals were analyzed. Heavy metal pollution in surface sediments of different areas in the Caohai plateau wetland was estimated by the Tomlinson Pollution Load Index (PLI) method. The analyzed results indicated that the average contents of Cd, Hg, As, Pb, Cr, Cu, Zn were 0.985, 0.345, 15.8, 38.9, 38.6, 22.8 and 384 mg x kg(-1), respectively. The heavy metal distributions varied with regional environment changes, the order of average contents of Cd and Hg in different regions was E (the eastern region) > S (the southern region) > N (the northern region), the order of the average content of Pb was N > E > S, and that of Zn was S > E > N. The results also suggested a medium heavy metal pollution level in the surface sediment of the Caohai plateau wetland with the PLI(zone) reaching 1.17. The order of pollution level in surface sediments of different regions was E > S > N. The results showed medium pollution levels in E and Hg which reached the extreme intensity pollution level were also the major polluted elements in surface sediments of the Caohai plateau wetland. And also, results showed medium pollution levels of Cd and Pb in surface sediments of Caohai plateau wetland. Cluster analysis results showed similar pollution sources of Cd, Zn, Pb and Hg, which should be attached great importance in terms of the prevention of the Caohai plateau wetland.

An application of excess lead-210 analysis for the study of fine sediment connectivity in a Mediterranean mountain basin with badlands, the Vallcebre research catchments

NASA Astrophysics Data System (ADS)

Moreno de las Heras, Mariano; Gallart, Francesc; Latron, Jérôme; Martínez-Carreras, Núria; Ferrer, Laura; Estrany, Joan

2017-04-01

Analysis of sediment dynamics in Mediterranean environments is fundamental to basin management, particularly for mountain catchments with badlands, which affect water bodies and freshwater ecosystems. Connectivity has emerged in Environmental and Earth Sciences as an evolution of the sediment delivery concept, providing a useful framework for understanding how sediments are transferred between geomorphic zones of the catchment. This study explores the feasibility of excess lead-210 (210Pbex) to analyse sediment connectivity in a 4-km2 Mediterranean mountain basin with badlands (the Vallcebre research catchments, Eastern Pyrenees) by applying simple 210Pbex mass-balance models for hypothesis generation and experimental testing in the field. Badland surfaces in the basin are weathered by freezing during the winter and are further eroded in summer by the effect of high-intensity storms. The eroded sediments may remain deposited within the catchment streams from months to years. Application of 210Pbex balance models in our basin proposes: (i) a saw-tooth seasonal pattern of badland surface 210Pbex activities (increasing from October to May, and depleted in summer) and (ii) a downstream increase in sediment activity due to fallout lead-210 accumulation in streambed sediment deposits. Both deposited and suspended sediments collected at the Vallcebre catchments showed, in general, low sediment 210Pbex concentrations, illustrating their fresh-rock origin at the badland sites, but also hampering the understanding of sediment 210Pbex patterns due to high measurement uncertainty (particularly for sediments with d50>20µm) and to strong dependence on sediment sampling methodology. Suspended sediment 210Pbex activity reproduced the simulated seasonal activity patterns for the badland surfaces. Contrary to the in-stream transit increases of sediment 210Pbex activity that were predicted by our model simulations, fallout lead-210 concentrations in the suspended sediments decreased towards the basin outlet, suggesting that fine sediment flushing by flooding prevented 210Pbex accumulation in the coarser streambed sediment deposits. These results indicate a high fine-sediment connectivity between the badlands, streams and basin outlet of the Vallcebre catchments, as well as the sequestration and fast transmission of fallout lead-210 by the finest and most dynamic fraction of sediments.

Butyltin compounds in sediments from the commercial harbor of Alexandria City, Egypt.

PubMed

Barakat, A O; Kim, M; Qian, Y; Wade, T L

2001-12-01

Tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined in surface-sediment samples collected from 23 sites in the commercial harbor of Alexandria City, Egypt. Butyltin concentrations in sediments varied widely depending on the sample location, ranging from less than 0.1 to 186 ng g(-1) of Sn for MBT, less than 0.1 to 379 ng g(-1) of Sn for DBT, and 1 to 2,067 ng g(-1) of Sn for TBT Elevated TBT concentrations, ranging from 727 to 2,067 ng g(-1) of Sn were observed in harbors, marinas, and near ship-repair facilities, indicating that the butyltin-containing, antifouling paints of boats and vessels are the major source of butyltin contamination. The TBT concentration decreased rapidly away from potential source areas of boat docking and repair facilities. The high relative concentrations of TBT in the sediments indicated that degradation processes in the sediments are minor, probably due to the anoxic sedimentary conditions at the sampling sites and/or relatively fresh input of TBT to these sites.

Field screening of water quality, bottom sediment, and biota associated with irrigation drainage in the Yuma Valley, Arizona, 1995

USGS Publications Warehouse

Tadayon, Saeid; King, K.A.; Andrews, Brenda; Roberts, William

1997-01-01

Because of concerns expressed by the U.S. Congress and the environmental community, the Department of the Interior began a program in late 1985 to identify the nature and extent of water-quality problems induced by irrigation that might exist in the western States. Surface water, bottom sediment, and biota were collected from March through September 1995 along the lower Colorado River and in agricultural drains at nine sites in the Yuma Valley, Arizona, and analyzed for selected inorganic and organic constituents. Analyses of water, bottom sediment, and biota were completed to determine if irrigation return flow has caused, or has the potential to cause, harmful effects on human health, fish, and wildlife in the study area. Concentrations of dissolved solids in surface-water samples collected in March generally did not vary substantially from surface-water samples collected in June. Concentrations of dissolved solids ranged from 712 to 3,000 milligrams per liter and exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 500 milligrams per liter for drinking water. Concentrations of chloride in 9 of 18 water samples and concentrations of sulfate in 16 of 18 water samples exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 250 milligrams per liter for drinking water. Calcium and sodium were the dominant cations, and chloride and sulfate were the dominant anions. The maximum selenium concentration of 8 micrograms per liter exceeded the U.S. Environmental Protection Agency aquatic-life chronic criterion of 5 micrograms per liter. Concentrations of lead in 7 of 18 water samples and concentrations of mercury in 4 of 18 water samples exceeded the aquatic-life cronic criteria of 3.2 and 0.012 micrograms per liter, respectively. Concentrations of antimony, beryllium, cadmium, and silver in the water samples were below analytical reporting limits. Arsenic was detected in 3 of 9 bottom-sediment samples, and concentrations ranged from 11 to 16 micrograms per gram. Concentrations ofaluminum, beryllium, boron, copper, lead, and zinc were highest in samples from Main Drain at southerly international boundary near San Luis, Arizona. Selenium was detected in all bottom-sediment samples, and concentrations ranged from 0.1 to 0.7 micrograms per gram. Concentrations of cadmium, europium, homium, mercury, molybdenum, silver, tantalum, tin, and uranium were below analytical reporting limits in the bottom-sediment samples. Concentrations of trace elements in bottom-sediment samples were within the ranges found in a study of soils of the western United States and did not indicate a significant accumulation of these constituents. p,p'Dichlorodiphenyldichloroethylene (commonly referred to as p,-p'-DDE) was detected in one bottom-sediment sample at a concentration of 1.4 micrograms per gram. No other organochlorine compounds were detected in the bottom-sediment samples. DDE was present in all fish and bird samples. Almost one-half of the fish samples contained DDE residues that were two times higher than the mean calculated for a national study in 1984-85. Twenty-tree percent of the fish contained more than three times the national mean. Fish from downstream parts of the Main Drain had the highest concentrations of DDE. Although concentrations of DDE in fish and in bird carcasses and eggs were above background levels, residues generally were below thresholds associated with chronic poisoning and reproductive problems in figh and wildlife. Concentrations of 18 trace elements were detected in cattail (Typha sp.) roots, freshwater clam (Corbicula fluminea), fish, and bird samples. Selenium in most fish and in livers of red-winged (Agelaius phoeniceus) and yellow-headed (Xanthocephalus xanthocephalus) blackbirds was above background concentrations but below toxic concentrations. In contrast, selenium was present in a killdeer (Charadrium vociferus) liver sample at potentially toxic con

Distribution, diffusive fluxes, and toxicity of heavy metals and PAHs in pore water profiles from the northern bays of Taihu Lake.

PubMed

Lei, Pei; Zhang, Hong; Shan, Baoqing; Zhang, Bozheng

2016-11-01

Pore water plays a more significant role than do sediments in pollutant cycling dynamics. Also, concentrations of pollutants in pore water provide important information about their bioavailability or eco-toxicity; however, very few studies have focused on this topic. In this study, four duplicate sediment cores from three typical northern bays as well as the central part of Taihu Lake were collected to investigate the distribution, diffusive fluxes, and toxicity of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in pore water profiles, which will be good in understanding the mobility and toxicity of these toxic pollutants and achieving better environmental management. The diffusive fluxes of heavy metals across the sediment-water interface was estimated through Fick's First Law, and the toxicity of heavy metals and PAHs in pore water was assessed by applying a water quality index (interstitial water toxicity criteria unit, IWCTU) and a hazard index (HI), respectively. The average concentrations of Cr, Cu, Ni, Pb, and Zn in surface pore water were 18.8, 23.4, 12.0, 13.5, and 42.5 μg L -1 , respectively. Also, concentrations of the selected heavy metals in both overlying water and pore water from Taihu Lake were all lower than the standard values of the environmental quality standards for surface water. The concentrations as the pore water depth increased, and the highest detected concentrations of heavy metals were recorded between 3 and 5 cm below the sediment surface. The average diffusive fluxes of these metals were 27.3, 24.8, 7.03, 7.81, and -3.32 μg (m 2 day) -1 , respectively, indicating export from sediment into overlying water, with the exception of Zn. There was a potential risk of toxicity, mainly from Pb and Cu, indicating that heavy metals in pore water had slight to moderate impact on sediment-dwelling organisms by values of the IWCTU and the Nemeraw index. The total PAH concentrations in pore water were higher than those in overlying water, and such gradient implies a potential flux of PAHs from pore water to overlying water. The average HI value of PAHs in surface pore water showed no or low ecological risk. While there may be occasional risk due to the HI values in some sites being greater than 1, the dominant contributors were carcinogenic PAHs. Because of their potential biological impact, heavy metals and PAHs and their comprehensive toxic effects in pore water should be given priority attention to keep the safety of Taihu Lake.

Demonstration of In Situ Treatment with Reactive Amendments for Contaminated Sediments in Active DoD Harbors

DTIC Science & Technology

2017-06-30

United States (NRC 2007). At elevated concentrations, these contaminants pose long-term risks to ecosystems and human health . 4 Reactive amendments...ability to reduce bioavailable concentrations thereby reducing ecological and human health risks. 6 2.1.2 AquaGate Composite Aggregate...could be of great interest as a remedy to HOC-impacted (e.g., PCBs, polycyclic aromatic hydrocarbon [PAHs], and pesticides ) surface sediments in

Occurrence, Ecological and Human Health Risks, and Seasonal Variations of Phenolic Compounds in Surface Water and Sediment of a Potential Polluted River Basin in China.

PubMed

Zhou, Mo; Zhang, Jiquan; Sun, Caiyun

2017-09-27

Five phenolic compounds in water and sediment of Yinma River Basin were investigated. The average concentration of phenol was the highest in water samples as well as in sediment samples during the wet season, 101.68 ng/L and 127.76 ng/g, respectively. 2,4,6-Trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) was not detected in some sampling sites. Shitou Koumen Reservoir and the neighboring area were the severest areas of phenolic pollution. The lower reach was more polluted in three water seasons than the middle reach and upper reach. Phenol had ecological risks in sediment during three water seasons. 2-Nitrophenol (2-NP) and 2,4-dichlorophenol (2,4-DCP) had ecological risks in sediment in both the normal and wet season. The concentrations of five phenolic compounds from high to low were in the wet season, normal season, and dry season in water and sediment, respectively. There were middle risks in water of total concentrations for five phenolic compounds in several sampling sites. Total concentrations for five phenolic compounds in sediment had high ecological risks in all sampling sites. However, there was no human health risk in the Yinma River Basin.

Occurrence, Ecological and Human Health Risks, and Seasonal Variations of Phenolic Compounds in Surface Water and Sediment of a Potential Polluted River Basin in China

PubMed Central

Zhou, Mo; Sun, Caiyun

2017-01-01

Five phenolic compounds in water and sediment of Yinma River Basin were investigated. The average concentration of phenol was the highest in water samples as well as in sediment samples during the wet season, 101.68 ng/L and 127.76 ng/g, respectively. 2,4,6-Trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) was not detected in some sampling sites. Shitou Koumen Reservoir and the neighboring area were the severest areas of phenolic pollution. The lower reach was more polluted in three water seasons than the middle reach and upper reach. Phenol had ecological risks in sediment during three water seasons. 2-Nitrophenol (2-NP) and 2,4-dichlorophenol (2,4-DCP) had ecological risks in sediment in both the normal and wet season. The concentrations of five phenolic compounds from high to low were in the wet season, normal season, and dry season in water and sediment, respectively. There were middle risks in water of total concentrations for five phenolic compounds in several sampling sites. Total concentrations for five phenolic compounds in sediment had high ecological risks in all sampling sites. However, there was no human health risk in the Yinma River Basin. PMID:28953252

Modeling of the Contaminated Sediment in the Erft River

NASA Astrophysics Data System (ADS)

Hu, Wei; Westrich, Bernhard; Rode, Michael

2010-05-01

Sediment transport processes play an important role in the surface water systems coupled with rainfall-runoff and contaminant transport. Pollutants like heavy metals adsorbed mainly by fine sediment particles can be deposited, eroded or transported further downstream. When the toxic pollutants deposited before and covered by cleaner sediment are remobilized by large flow events such as floods, they pose a hidden threat to the human health and environment. In the Erft River, due to mining activities in the past, the heavy metals release from the tributary Veybach on the downstream water and sediment quality is significant. Recent measurements prove the decreasing concentration trend of heavy metals in the river bed sediment from the Veybach. One-dimensional hydrodynamic model COSMOS is used to model the complicated water flow, sediment erosion, deposition and contaminant mixing and transport in the mainstream of the Erft River. It is based on a finite-difference formulation and consists of one-dimensional, unsteady sub-model of flow and transport, coupled with a sub-model of the layered sediment bed. The model accounts for the following governing physical-chemical processes: convective and dispersive transport, turbulent mixing deposited sediment surface, deposition, consolidation, aging and erosion of sediment, adsorption-desorption of pollutants to suspended particles and losses of pollutants due to decay or volatilization. The results reproduce the decreasing profile of the pollutant concentration in the river bed sediment nicely. Further modeling is to analysis the influence of the mixing process at the water-riverbed interface on the contaminant transport, hydrological scenarios impact on the remobilization of the sink of pollutant and its negative consequences on the river basin.

Geochemical background and ecological risk of heavy metals in surface sediments from the west Zhoushan Fishing Ground of East China Sea.

PubMed

Xu, Gang; Liu, Jian; Pei, Shaofeng; Hu, Gang; Kong, Xianghuai

2015-12-01

Surface sediment grain size as well as the spatial distribution, pollution status, and source identification of heavy metals in the west Zhoushan Fishing Ground (ZFG) of the East China Sea were analyzed to study the geochemical background concentrations of heavy metals and to assess their potential ecological risk. Our results show that surface sediments in the eastern part of study area were mainly composed of sand-sized components. Spatial distributions of heavy metals were mainly controlled by grain size and terrigenous materials, and their concentrations in the coarsest grain sediments formed primarily during the Holocene transgressive period could represent the element background values of our study area. Contamination factor suggests that there was no pollution of Pb, Zn, and Cr generally in our study area and slight pollution of Cu, Cd, and As (especially Cu) at some stations. In addition, ecological harm coefficient indicates that the ecological risk of each heavy metal, except for Cd, at two stations was low as well. These results are consistent with the pollution load index and ecological risk index, which suggest both the overall level of pollution and the overall ecological risk of six studied metals in sediment were relatively low in our study area. Enrichment factor indicates that the heavy metals came mostly from the natural source. Summarily, the quality level of sediment in our study area was relatively good, and heavy metals in sediments could not exert threat to aquatic lives in the ZFG until now.

Tracking paraglacial sediment with cosmogenic 10Be using an example from the northwest Scottish Highlands

NASA Astrophysics Data System (ADS)

Fame, Michelle L.; Owen, Lewis A.; Spotila, James A.; Dortch, Jason M.; Caffee, Marc W.

2018-02-01

Beryllium-10 concentrations in samples of sediment and bedrock from five study sites across the Scottish Highlands trace paraglacial sediment sources and define the nature of glacial erosion for the late Quaternary. Exposure ages derived from 10Be concentrations in ridge and lower elevation bedrock range from 10 to 33 ka, which suggest that polythermal ice and warm based ice were primarily responsible for producing glacial sediment. Comparisons of 10Be concentrations between catchment-wide sediment (2.06 ± 0.34 × 104 to 11.24 ± 1.54 × 104 atoms g-1 SiO2; n = 33), near surface deposits (2.71 ± 0.33 × 104 to 3.48 ± 0.49 × 104 atoms g-1 SiO2; n = 6), 4-m-thick deep till (0.68 × 10410Be atoms g-1 SiO2; n = 1), ridge bedrock (8.93 ± 0.47 × 104 to 34.05 ± 1.66 × 104 atoms g-1 SiO2; n = 20), and lower elevation polished bedrock (6.74 ± 0.67 × 104 to 12.65 ± 0.7 × 104 atoms g-1 SiO2, n = 5) indicate that most sand fluxing through catchments in the Scottish Highlands is sourced from the remobilization and vertical mixing of near surface deposits. These findings indicate that glaciogenic material continues to dominate paraglacial sediment budgets more than 11 ka after deglaciation.

Redox Trapping of Arsenic During Groundwater Discharge in Sediments from the Meghna Riverbank in Bangladesh

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

Datta, S.; Mailloux, B; Jung, H

2009-01-01

Groundwater arsenic (As) is elevated in the shallow Holocene aquifers of Bangladesh. In the dry season, the shallow groundwater discharges to major rivers. This process may influence the chemistry of the river and the hyporheic zone sediment. To assess the fate of As during discharge, surface (0-5 cm) and subsurface (1-3 m) sediment samples were collected at 9 sites from the bank of the Meghna River along a transect from its northern source (25 degrees N) to the Bay of Bengal (22.5 degrees N). Bulk As concentrations of surface sediment averaged 16 {+-} 7 mg/kg (n = 9). Subsurface sedimentmore » contained higher mean concentrations of As of 4,000 mg/kg (n = 14), ranging from 1 to 23,000 mg/kg As, with >100 mg/kg As measured at 8 sites. X-ray absorption near-edge structure spectroscopy indicated that As was mainly arsenate and arsenite, not As-bearing sulfides. We hypothesize that the elevated sediment As concentrations form as As-rich groundwater discharges to the river, and enters a more oxidizing environment. A significant portion of dissolved As sorbs to iron-bearing minerals, which form a natural reactive barrier. Recycling of this sediment-bound As to the Ganges-Brahmaputra-Meghna Delta aquifer provides a potential source of As to further contaminate groundwater. Furthermore, chemical fluxes from groundwater discharge from the Ganges-Brahmaputra-Meghna Delta may be less than previous estimates because this barrier can immobilize many elements.« less

Method validation and reconnaissance of pharmaceuticals, personal care products, and alkylphenols in surface waters, sediments, and mussels in an urban estuary.

PubMed

Klosterhaus, Susan L; Grace, Richard; Hamilton, M Coreen; Yee, Donald

2013-04-01

Novel methods utilizing liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry were validated for low-level detection of 104 pharmaceuticals and personal care products ingredients (PPCPs) and four alkylphenols (APs) in environmental samples. The methods were applied to surface water, sediment, and mussel tissue samples collected from San Francisco Bay, CA, USA, an urban estuary that receives direct discharge from over forty municipal and industrial wastewater outfalls. Among the target PPCPs, 35% were detected in at least one sample, with 31, 10, and 17 compounds detected in water, sediment, and mussels, respectively. Maximum concentrations were 92 ng/L in water (valsartan), 33 ng/g dry weight (dw) in sediments (triclocarban), and 14 ng/g wet weight (ww) in mussels (N,N-diethyl-m-toluamide). Nonylphenol was detected in water (<2-73 ng/L), sediments (22-86 ng/g dw), and mussels (<0.04-95 ng/g ww), and nonylphenol mono- and diethoxylates were detected in sediments (<1-40 ng/g dw) and mussels (<5-192 ng/g ww). The concentrations of PPCPs and APs detected in the San Francisco Bay samples were generally at least an order of magnitude below concentrations expected to elicit toxic effects in aquatic organisms. This study represents the first reconnaissance of PPCPs in mussels living in an urban estuary and provides the first field-derived bioaccumulation factors (BAFs) for select compounds in aquatic organisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

Suspended-sediment sources in an urban watershed, Northeast Branch Anacostia River, Maryland

USGS Publications Warehouse

Devereux, Olivia H.; Prestegaard, Karen L.; Needelman, Brian A.; Gellis, Allen C.

2010-01-01

Fine sediment sources were characterized by chemical composition in an urban watershed, the Northeast Branch Anacostia River, which drains to the Chesapeake Bay. Concentrations of 63 elements and two radionuclides were measured in possible land-based sediment sources and suspended sediment collected from the water column at the watershed outlet during storm events. These tracer concentrations were used to determine the relative quantity of suspended sediment contributed by each source. Although this is an urbanized watershed, there was not a distinct urban signature that can be evaluated except for the contributions from road surfaces. We identified the sources of fine sediment by both physiographic province (Piedmont and Coastal Plain) and source locale (streambanks, upland and street residue) by using different sets of elemental tracers. The Piedmont contributed the majority of the fine sediment for seven of the eight measured storms. The streambanks contributed the greatest quantity of fine sediment when evaluated by source locale. Street residue contributed 13% of the total suspended sediment on average and was the source most concentrated in anthropogenically enriched elements. Combining results from the source locale and physiographic province analyses, most fine sediment in the Northeast Branch watershed is derived from streambanks that contain sediment eroded from the Piedmont physiographic province of the watershed. Sediment fingerprinting analyses are most useful when longer term evaluations of sediment erosion and storage are also available from streambank-erosion measurements, sediment budget and other methods.

Chemical quality of the Saw Mill River, Westchester County, New York, 1981-83

USGS Publications Warehouse

Rogers, R.J.

1984-01-01

Surface waters, bottom sediments and coatings formed on artificial substrates (ceramic tiles) were analyzed to evaluate the chemical quality of the Saw Mill River, New York. Heavy metals, nutrients, and organic contaminants were studied. Dissolved orthophosphate concentrations were highest in the lower third of the river. Dissolved manganese was the only metal to exceed U.S. Environmental Protection Agency water-quality criteria. Arsenic, cadmium, copper, lead, and zinc concentrations were highest in waters from the lowest 4 river miles. Concentrations of copper, lead, and zinc in bottom sediments from the lowest 3 river miles were greater than in upstream sediments. Concentrations of nine heavy metals were higher on tiles emplaced below river mile 3 than on tiles upstream. Few organic compounds were detected in the water column; none persisted at all sites. Chlordane, DDD, DDE, DDT, dieldrin, and polychlorinated biphenyls (PCB's) were found in bottom sediments throughout the basin. PCB concentrations were highest in the lowest 6 river miles; the other organic compounds exhibited no spatial patterns. Polynuclear aromatic hydrocarbons were most abundant in bottom sediments from the lowest 2 river miles. Collectively the distribution of contaminants indicates that river quality deteriorates in the lower, more heavily urbanized reach. (USGS)

Overview of selected surrogate technologies for continuous suspended-sediment monitoring

USGS Publications Warehouse

Gray, J.R.; Gartner, J.W.

2006-01-01

Surrogate technologies for inferring selected characteristics of suspended sediments in surface waters are being tested by the U.S. Geological Survey and several partners with the ultimate goal of augmenting or replacing traditional monitoring methods. Optical properties of water such as turbidity and optical backscatter are the most commonly used surrogates for suspended-sediment concentration, but use of other techniques such as those based on acoustic backscatter, laser diffraction, digital photo-optic, and pressure-difference principles is increasing for concentration and, in some cases, particle-size distribution and flux determinations. The potential benefits of these technologies include acquisition of automated, continuous, quantifiably accurate data obtained with increased safety and at less expense. When suspended-sediment surrogate data meet consensus accuracy criteria and appropriate sediment-record computation techniques are applied, these technologies have the potential to revolutionize the way fluvial-sediment data are collected, analyzed, and disseminated.

A pilot study on remediation of sediments enriched by oyster farming wastes using granulated coal ash.

PubMed

Yamamoto, T; Kim, K H; Shirono, K

2015-01-15

In order to evaluate the ability of granulated coal ash (GCA), a byproduct of coal thermal electric power stations, to remove hydrogen sulfide from organically enriched sediments, a pilot study was carried out at oyster farming sites, where sediments were enriched with oyster feces and dead oysters. Concentration of hydrogen sulfide in the interstitial water of the sediment decreased to nearly zero in both experimental sites, whereas it remained over 0.2mg/l in the control site. Concentration of acid volatile sulfide (AVS) in the sediment also decreased significantly in both experimental sites, while remained over 0.4 mg/g in the control site. Increases were observed in both the number of benthic microalgae species and the individual number of benthic animals in the surface sediments. This may have been due to the decrease in hydrogen sulfide. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

PubMed

Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

2017-08-15

Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

Variation laws and release characteristics of phosphorus on surface sediment of Dongting Lake.

PubMed

Zhu, Guangrui; Yang, Ying

2018-05-01

The variation trend and growth rate of P were analyzed by the concentration of the phosphorus fraction on surface sediment of Dongting Lake from 2012 to 2016, to reveal the cumulative effect of P in the actual environment. Meanwhile, the adsorption kinetics and adsorption isotherm were employed to examine the P-release possibility of sediment, which predicts the yearly released sediment phosphorus in Dongting Lake. The actual growth rate of TP (Total Phosphorus) is 53 mg·(kg·year) -1 in East Dongting Lake, 39 mg·(kg·year) -1 in South Dongting Lake, and 29 mg·(kg·year) -1 in West Dongting Lake, while the sum of the phosphorus fraction growth rates has little difference from the rate of TP in sediments of the three areas of Dongting Lake. Furthermore, the Elovich model and the Langmuir crossover-type equations are established to present the adsorption characteristic of sediment in Dongting Lake; the result shows that the sediments play a source role for phosphorus in East and South Dongting Lake from zero equilibrium phosphorus concentration (EPC 0 ) in the present situation, but an adsorption effect on TP is shown in West Dongting Lake. When the conditions of environment change are ignored, the maximum P-sorption level in sediments of East Dongting Lake will reach in 2040 according to the actual growth rate of sediments, while that in West Dongting Lake and South Dongting Lake will be in 2046 and 2061, respectively.

Distribution of short chain chlorinated paraffins in marine sediments of the East China Sea: influencing factors, transport and implications.

PubMed

Zeng, Lixi; Zhao, Zongshan; Li, Huijuan; Wang, Thanh; Liu, Qian; Xiao, Ke; Du, Yuguo; Wang, Yawei; Jiang, Guibin

2012-09-18

Short chain chlorinated paraffins (SCCPs) are high production volume chemicals in China and found to be widely present in the environment. In this study, fifty-one surface sediments and two sediment cores were collected from the East China Sea to study their occurrence, distribution patterns and potential transport in the marginal sea. SCCPs were found in all surface sediments and ranged from 5.8 to 64.8 ng/g (dry weight, d.w.) with an average value of 25.9 ng/g d.w. A general decreasing trend with distance from the coast was observed, but the highest value was found in a distal mud area far away from the land. The C10 homologue was the most predominant carbon chain group, followed by C11, C12, and C13 homologue groups. Significant linear relationship was found between total organic carbon (TOC) and total SCCP concentrations (R(2) = 0.51, p < 0.05). Spatial distributions and correlation analysis indicated that TOC, riverine input, ocean current, and atmospheric deposition played an important role in controlling SCCP accumulation in marine sediments. Vertical profiles of sediment cores showed that SCCP concentrations decreased from surface to the depth of 36 cm, and then slightly increased again with depth, which showed a significant positive correlation with TOC and chlorine contents (Cl%). The results suggest that SCCPs are being regionally or globally distributed by long-range atmospheric or ocean current transport.

Stable lead isotopic analyses of historic and contemporary lead contamination of San Francisco Bay estuary

USGS Publications Warehouse

Ritson, P.I.; Bouse, R.M.; Flegal, A.R.; Luoma, S.N.

1999-01-01

Variations in stable lead isotopic composition (240Pb, 206Pb, 207Pb, 208Pb) in three sediment cores from the San Francisco Bay estuary document temporal changes in sources of lead during the past two centuries. Sediment, with lead from natural geologic sources, and relatively homogeneous lead isotopic compositions are overlain by sediments whose isotopic compositions indicate change in the sources of lead associated with anthropogenic modification of the estuary. The first perturbations of lead isotopic composition in the cores occur in the late 1800s concordant with the beginning of industrialization around the estuary. Large isotopic shifts, toward lower 206Pb/207Pb, occur after the turn of the century in both Richardson and San Pablo Bays. A similar relationship among lead isotopic compositions and lead concentrations in both Bays suggest contamination from the same source (a lead smelter). The uppermost sediments (post 1980) of all cores also have a relatively homogenous lead isotopic composition distinct from pre-anthropogenic and recent aerosol signatures. Lead isotopic compositions of leachates from fourteen surface sediments and five marsh samples from the estuary were also analyzed. These analyses suggest that the lead isotopic signature identified in the upper horizons of the cores is spatially homogeneous among recently deposited sediments throughout the estuary. Current aerosol lead isotopic compositions [Smith, D.R., Niemeyer, S., Flegal, A.R., 1992. Lead sources to California sea otters: industrial inputs circumvent natural lead biodepletion mechanisms. Environmental Research 57, 163-175] are distinct from the isotopic compositions of the surface sediments, suggesting that the major source of lead is cycling of historically contaminated sediments back through the water column. Both the upper core sediments and surface sediments apparently derive their lead predominantly from sources internal to the estuary. These results support the idea that geochemical cycling of lead between sediments and water accounts for persistently elevated lead concentrations in the water column despite 10-fold reduction of external source inputs to San Francisco Bay [Flegal, A.R., Rivera-Duarte, I., Ritson, P.I., Scelfo, G., Smith, G.J., Gordon, M., Sanudo-Wilhelmy, S.A., 1996. Metal contamination in San Francisco Waters: historic perturbations, contemporary concentrations, and future considerations in San Francisco Bay. In: Hollobaugh, J.T. (Ed.), The Ecosystem. AAAS, pp. 173-188].

Aerobic biodegradation potential of endocrine disrupting chemicals in surface-water sediment at Rocky Mountains National Park, USA

USGS Publications Warehouse

Bradley, Paul M.; Battaglin, William A.; Iwanowicz, Luke R.; Clark, Jimmy M.; Journey, Celeste A.

2016-01-01

Endocrine disrupting chemicals (EDC) in surface water and bed sediment threaten the structure and function of aquatic ecosystems. In natural, remote, and protected surface-water environments where contaminant releases are sporadic, contaminant biodegradation is a fundamental driver of exposure concentration, timing, duration, and, thus, EDC ecological risk. Anthropogenic contaminants, including known and suspected EDC, were detected in surface water and sediment collected from 2 streams and 2 lakes in Rocky Mountains National Park (ROMO). The potential for aerobic EDC biodegradation was assessed in collected sediments using 6 14C-radiolabeled model compounds. Aerobic microbial mineralization of natural (estrone and 17β-estradiol) and synthetic (17α-ethinylestradiol) estrogen was significant at all sites. ROMO bed sediment microbial communities also effectively degraded the xenoestrogens, bisphenol-A and 4-nonylphenol. The same sediment samples exhibited little potential for aerobic biodegradation of triclocarban, however, illustrating the need to assess a wider range of contaminant compounds. The current results support recent concerns over the widespread environmental occurrence of carbanalide antibacterials, like triclocarban and triclosan, and suggest that backcountry use of products containing these compounds should be discouraged.

From agricultural intensification to conservation: Sediment transport in the Raccoon River, Iowa, 1916-2009

USGS Publications Warehouse

Jones, C.S.; Schilling, K.E.

2011-01-01

Fluvial sediment is a ubiquitous pollutant that negatively aff ects surface water quality and municipal water supply treatment. As part of its routine water supply monitoring, the Des Moines Water Works (DMWW) has been measuring turbidity daily in the Raccoon River since 1916. For this study, we calibrated daily turbidity readings to modern total suspended solid (TSS) concentrations to develop an estimation of daily sediment concentrations in the river from 1916 to 2009. Our objectives were to evaluate longterm TSS patterns and trends, and relate these to changes in climate, land use, and agricultural practices that occurred during the 93-yr monitoring period. Results showed that while TSS concentrations and estimated sediment loads varied greatly from year to year, TSS concentrations were much greater in the early 20th century despite drier conditions and less discharge, and declined throughout the century. Against a backdrop of increasing discharge in the Raccoon River and widespread agricultural adaptations by farmers, sediment loads increased and peaked in the early 1970s, and then have slowly declined or remained steady throughout the 1980s to present. With annual sediment load concentrated during extreme events in the spring and early summer, continued sediment reductions in the Raccoon River watershed should be focused on conservation practices to reduce rainfall impacts and sediment mobilization. Overall, results from this study suggest that eff orts to reduce sediment load from the watershed appear to be working. ?? 2011 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Soil aggregate stability and rainfall-induced sediment transport on field plots as affected by amendment with organic matter inputs

NASA Astrophysics Data System (ADS)

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

2017-04-01

Aggregate stability is an important factor in soil resistance against erosion, and, by influencing the extent of sediment transport associated with surface runoff, it is thus also one of the key factors which determine on- and off-site effects of water erosion. As it strongly depends on soil organic matter, many studies have explored how aggregate stability can be improved by organic matter inputs into the soil. However, the focus of these studies has been on the relationship between aggregate stability and soil organic matter dynamics. How the effects of organic matter inputs on aggregate stability translate into soil erodibility under rainfall impacts has received much less attention. In this study, we performed field plot experiments to examine how organic matter inputs affect aggregate breakdown and surface sediment transport under field conditions in artificial rainfall events. Three pairs of plots were prepared by adding a mixture of grass and wheat straw to one of plots in each pair but not to the other, while all plots were treated in the same way otherwise. The rainfall events were applied some weeks later so that the applied organic residues had sufficient time for decomposition and incorporation into the soil. Surface runoff rate and sediment concentration showed substantial differences between the treatments with and without organic matter inputs. The plots with organic inputs had coarser and more stable aggregates and a rougher surface than the control plots without organic inputs, resulting in a higher infiltration rate and lower transport capacity of the surface runoff. Consequently, sediments exported from the amended plots were less concentrated but more enriched in suspended particles (<20 µm) than from the un-amended plots, indicating a more size-selective sediment transport. In contrast to the amended plots, there was an increase in the coarse particle fraction (> 250 µm) in the runoff from the plots with no organic matter inputs towards the end of the rainfall events due to emerging bed-load transport. The results show that a single application of organic matter can already cause a large difference in aggregate breakdown, surface sealing, and lateral sediment-associated matter transfer under rainfall impact. Furthermore, we will present terrestrial laser scanning data showing the treatment effects on soil surface structure, as well as data on carbon, phosphorus and heavy metal export associated with the translocation of the sediments.

Trace Elements in the Marine Sediments of the La Paz Lagoon, Baja California Peninsula, Mexico: Pollution Status in 2013.

PubMed

Pérez-Tribouillier, Habacuc; Shumilin, Evgueni; Rodríguez-Figueroa, Griselda Margarita

2015-07-01

To determine the actual concentrations of trace elements in surface sediments from the La Paz Lagoon, as well as their associations and possible origins, 91 sediment samples were analyzed for more than 50 elements using a combination of ICP-MS and ICP-AES. The results of a principal component analysis are used to distinguish four associative groups within the elements. Natural enrichment of As, Cd and U occurs due to the supply of weathered phosphorites from the El Cien formation located to the north-west of the lagoon. Sediment quality indices for potentially toxic trace elements do not show any probable impact on the biota of the lagoon. Only the concentrations of As in 30 % of the stations and Cu in 20 % of them exceed related effect range low levels. The highest concentration of Pb (36.8 mg kg(-1)) was measured in the sediments near the City of La Paz.

Petroleum pollution in mangrove forests sediments from Qeshm Island and Khamir Port-Persian Gulf, Iran.

PubMed

Ebrahimi-Sirizi, Zohreh; Riyahi-Bakhtiyari, Alireza

2013-05-01

The concentrations of total polycyclic aromatic hydrocarbons (PAHs) and 22 individual PAH compounds in 42 surface sediments collected from the mangrove forest of Qeshm Island and Khamir Port (Persian Gulf) were analyzed. PAHs concentrations ranged from 259 to 5,376 ng g(-1) dry weight with mean and median values of 1,585 and 1,146 ng g(-1), respectively. The mangrove sediments had higher percentages of lower molecular weight PAHs and the PAH profiles were dominated by naphthalene. Ratio values of specific PAH compounds were calculated to evaluate the possible source of PAH contamination. This ratios suggesting that the mangrove sediments have a petrogenic input of PAHs. Sediment quality guidelines were conducted to assess the toxicity of PAH compounds. The levels of total PAHs at all of stations except one station, namely Q6, were below the effects range low. Also, concentrations of naphthalene in some stations exceeded the effects range median.

Impact evaluation of the industrial activities in the Bay of Bakar (Adriatic Sea, Croatia): recent benthic foraminifera and heavy metals.

PubMed

Popadić, Adriana; Vidović, Jelena; Cosović, Vlasta; Medaković, Davorin; Dolenec, Matej; Felja, Igor

2013-11-15

The Bay of Bakar is one of the most heavily polluted bays at the Eastern Adriatic. Three major industrial companies potentially endanger the bay. The concentration of major, minor and trace elements in surface sediments from thirteen stations was discussed in relation to the sediment type and foraminiferal assemblages. The distribution of major elements in the bay is influenced by geological nature of surroundings. Heavy metal distribution depends on pollution sources and on amount of mud fraction: fine-grained sediments are enriched by them in comparison with coarse-grained ones. Different sediment quality criteria complicate the pollution assessment in the bay. Heavy metal concentrations generally fall into allowed depositional values for marine environments; only area in front of the coke plant and the City of Bakar harbor is heavily polluted. Stress-tolerant foraminiferal species dominate at stations with higher concentrations of heavy metals and coarse-grained sediments consist of larger number of epifaunal taxa. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Georges Bank monitoring program 1985; analysis of trace metals in bottom sediments during the third year of monitoring

USGS Publications Warehouse

Bothner, Michael H.; Rendigs, R. R.; Campbell, Esma; Doughten, M.W.; Parmenter, C.M.; O'Dell, C. H.; DiLisio, G.P.; Johnson, R.G.; Gillison, J.R.; Rait, Norma

1986-01-01

Of the 12 elements analyzed in bulk (undifferentiated) sediments collected adjacent to drilling rigs on Georges Bank, only barium was found to increase in concentration during the period when eight exploratory wells were drilled (July 1981 until September 1982). The maximum postdrilling concentration of barium (a major element in drilling mud) reached 172 ppm in bulk sediments near the drill site in block 410. This concentration is higher than the predrilling concentration at this location by a factor of 5.9. This maximum barium concentration is within the range of predrilling concentrations (28-300 ppm) measured in various sediment types from the regional stations of this program. No drilling-related changes in the concentrations of the 11 other metals have been observed in bulk sediments at any of the locations sampled in this program. We estimate that about 25 percent of the barite discharged at block 312 was present in the sediments within 6 km of the rig, 4 weeks after drilling was completed at this location (drilling period was December 8, 1981-June 27, 1982). For almost a year following completion of this well, the inventory of barite decreased rapidly, with a half-life of 0.34 year. During the next year, the inventory decreased at a slower rate (half-life of 3.4 years). The faster rate probably reflects resuspension and sediment transport of bariterich material residing at the sediment surface. Elevated barium concentrations in post-drilling sediment-trap samples from block 312 indicate that such resuspension can occur up to at least 25 m above the sea floor. As the remaining barite particles are reworked deeper into the sediments by currents and bioturbation, removal by sediment-transport processes is slower. The barite discharged during the exploratory phase of drilling is associated with the fine fraction of sediment and is widely distributed around the bank. We found evidence for barium transport to Great South Channel, 115 km west of the drilling, and to stations 2 and 3, 35 km east of the easternmost drilling site. Small increases in barium concentrations, present in the fine fraction of sediment only, were measured also at the heads of both Lydonia and Oceanographer Canyons, located 8 and 39 km, respectively, seaward of the nearest exploratory well.

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

PubMed

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

2004-09-01

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

Accumulation, Release, and Solubility of Arsenic, Molybdenum, and Vanadium in Wetland Sediments

USGS Publications Warehouse

Fox, P.M.; Doner, H.E.

2003-01-01

This study was undertaken to determine the fate of As, Mo, and V (trace elements, TEs) in the sediments of a constructed wetland in use for the remediation of potentially toxic trace element-contaminated agricultural drainwater. After three years of wetland operation, sediment cores were collected to determine changes in TE concentrations as a function of depth and the effects of varying water column depth. All TE concentrations were highest in the top 2 to 4 cm and decreased with depth. Molybdenum accumulated in the wetland sediments, up to levels of 32.5 ?? 4.6, 30.2 ?? 8.9, and 59.3 ?? 26.1 mg kg-1 in the top 1 cm of sediment at water depths of 15, 30, and 60 cm, respectively. In the top 2 cm of sediment, As accumulated (28.2 ?? 3.0 mg kg-1) only at the 60-cm water depth. Below 2 cm, as much as 10 mg kg-1 of As was lost from the sediment at all water depths. In most cases, V concentrations decreased in the sediment. In this wetland system, the lowest redox potentials were found near the sediment surface and increased with depth. Thus, in general As, Mo, and V concentrations in the sediment were highest under more reducing conditions and lowest under more oxidizing conditions. Most of the accumulated Mo (73%) became water soluble on drying of samples. This has important implications for systems undergoing changes in redox status; for instance, if these wetland sediments are dried, potentially large amounts of Mo may be solubilized.

Ecological risks of home and personal care products in the riverine environment of a rural region in South China without domestic wastewater treatment facilities.

PubMed

Zhang, Nai-Sheng; Liu, You-sheng; Van den Brink, Paul J; Price, Oliver R; Ying, Guang-Guo

2015-12-01

Home and personal care products (HPCPs) including biocides, benzotriazoles (BTs) and ultraviolet (UV) filters are widely used in our daily life. After use, they are discharged with domestic wastewater into the receiving environment. This study investigated the occurrence of 29 representative HPCPs, including biocides, BTs and UV filters, in the riverine environment of a rural region of South China where no wastewater treatment plants were present, and assessed their potential ecological risks to aquatic organisms. The results showed the detection of 11 biocides and 4 BTs in surface water, and 9 biocides, 3 BTs and 4 UV filters in sediment. In surface water, methylparaben (MeP), triclocarban (TCC), and triclosan (TCS) were detected at all sites with median concentrations of 9.23 ng/L, 2.64 ng/L and 5.39 ng/L, respectively. However, the highest median concentrations were found for clotrimazole (CLOT), 5-methyl-1H-benzotriazole (MBT) and carbendazim (CARB) at 55.6 ng/L, 33.7 ng/L and 13.8 ng/L, respectively. In sediment, TCC, TCS, and UV-326 were detected with their maximum concentrations up to 353 ng/g, 155 ng/g, and 133 ng/g, respectively. The concentrations for those detected HPCPs in surface water and sediment were generally lower in the upper reach (rural area) of Sha River than in the lower reach of Sha River with close proximity to Dongjiang River (Pt-test<0.05), indicating other input sources of HPCPs in the lower reach. Biocides showed significantly higher levels in surface water in the wet season than in the dry and intermediate seasons. Preliminary risk assessment demonstrated that the majority of HPCPs monitored represented low risk in surface waters. There are potentially greater risks to aquatic organisms from the use of TCS and TCC in the wet season than in dry and intermediate seasons in surface waters. This preliminary assessment also indicates potential concerns associated with TCC, TCS, DEET, CARB, and CLOT in sediments, although additional data should be generated to assess this fully. Thus future research is needed to investigate ecological effects of these HPCPs on benthic organisms in sediment of rural rivers receiving untreated wastewater discharge. Copyright © 2015 Elsevier Inc. All rights reserved.

Distribution and contamination status of chromium in surface sediments of northern Kaohsiung Harbor, Taiwan.

PubMed

Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng

2013-07-01

The distribution, enrichment, accumulation, and potential ecological risk of chromium (Cr) in the surface sediments of northern Kaohsiung Harbor, Taiwan, China were investigated. Sediment samples from ten locations located between the river mouths and harbor entrance of northern Kaohsiung Harbor were collected quarterly in 2011 and characterized for Cr, aluminum, water content, organic matter, total nitrogen, total phosphorous, total grease, and grain size. Results showed that the Cr concentrations varied from 27.0 to 361.9 mg/kg with an average of (113.5 +/- 87.0) mg/kg. High Cr concentration was observed near the Jen-Gen River mouth. The mean Cr concentration was high at 255.5 mg/kg, which was at least 2 to 7 times than that of other sites. This might imply significant Cr contribution from upstream receiving tanneries wastewater into the Jen-Gen River. The spatial distribution of Cr reveals relatively high in the river mouth region, especially in Jen-Gen River, and gradually diminishes toward the harbor entrance region. This indicates that the major sources of Cr pollution from upstream industrial and municipal wastewaters discharged along the river bank; and Cr may drift with sea current and be dispersed into open sea. Moreover, Cr concentrations correlated closely to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the neighboring industrial parks and river basins. Results from the enrichment factor and geo-accumulation index analyses imply that the Jen-Gen River sediments can be characterized as moderate enrichment and none to medium accumulation of Cr, respectively. However, results of potential ecological risk index indicate that the sediment has low ecological potential risk. The results can provide valuable information to developing future strategies for the management of river mouth and harbor.

Monitoring of nutrients, pesticides, and metals in waters, sediments, and fish of a wetland.

PubMed

Salvadó, V; Quintana, X D; Hidalgo, M

2006-10-01

Wetland areas are of extraordinary importance for the conservation of wildlife. The Aiguamolls de l'Empordà Natural Park, located in Girona (northeast Spain), is one of the few areas in Europe acting as a way station for migratory birds. The natural park is made up of a brackish water reserve and a fresh water reserve. Agriculture and tourism, which are concentrated especially around coastal population centers, are the main activities in this area and result in the release into the environment of nutrients, pesticides, and heavy metals. This article aims to investigate the presence of nutrients, selected pesticides (organochlorine compounds, permethrin and triazines) and metals (Cr, Cu, Cd, Ni and Pb) in water, sediments, and fish samples. In the case of water, seasonal variations in levels of contamination were also monitored. Comparison was made of the fresh and brackish water reserves and concentration factors for metals and pesticides in sediment were determined. We conclude that the most significant sources of contamination in the natural park are from the entry of pesticides and nutrients into surface waters and sediments as a result of the intensive farming activity of the surrounding areas. The pesticides with the greatest presence were found to be lindane, heptachlor epoxide, permethrin, and atrazine. Among the metals analyzed, Cu and Cr presented the highest concentrations in surface waters and sediments.

Diphytanyl glycerol ether distributions in sediments of the Orca Basin

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

Pease, T.K.; VanVleet, E.S.; Barre, J.S.

1992-09-01

Archaebacterially produced diphytanyl glycerol ether (DPGE) was examined in core sediments from the Orca Basin, an anoxic hypersaline basin in the northwestern Gulf of Mexico, to observe its spatial variability and potential origin. A differential extraction protocol was employed to quantify the isopranyl glycerol ethers associated with unbound, intermediate-bound, and kerogen-bound lipid fractions. Archaebacterial lipids were evident at all depths for the unbound and intermediate-bound fractions. Concentrations of DPGE ranged from 0.51 to 2.91 [mu]g/g dry sediment at the surface and showed secondary maxima deeper in basin sediments. Intermediate-bound DPGE concentrations exhibited an inverse relationship to unbound DPGE concentrations. Kerogen-boundmore » DPGE concentrations were normally below detection limits. Earlier studies describing the general homogeneity of lipid components within the overlying brine and at the brine/seawater interface suggest that the large-scale sedimentary DPGE variations observed in this study result from spatial and temporal variations in in-situ production by methanogenic or extremely halophilic archaebacteria.« less

The Preliminary Study of Organochlorine Pesticide Residues on Sediments of Bivalvia Fishing Ground at Eastern Part of Coastal Semarang

NASA Astrophysics Data System (ADS)

Adhi Suryono, Chrisna; Subagyo; Setyati, Wilis Ari; Sri Susilo, Endang; Rochaddi, Baskoro; Triaji Mahendrajaya, Robertus

2018-02-01

This paper presents the occurrence level of organochlorine contamination in marine sediments of Semarang coastal areas as a fishing ground of Bivalvia. Five compounds (Heptachlor, Aldrin, Endosulfan, Endrin and pp-DDT) of contaminant have been determined in the sediments surface of Semarang coastal waters. The samples were then analyzed by using gas chromatography and followed by using the method of Standard Method Examination. The result showed that the average concentration of organochlorine pesticides Heptachlor, Aldrin, Endosulfan, Endrin and pp-DDT were 25.5, bellow detected, 7.1, 37.2, 28.6 μ g/L, respectively. The high concentration of pesticide showed on Endrin (65,84 ppb), pp-DDT (29,53 μ g/L), and heptachlor (25,45 μ g/L). The low concentrations were detected on aldrin (bellow detected) and endosulfan (0,92 μ g/L). The concentration of organochlorine pesticides in these areas might contribute on four rivers which deposited the sediment in these coastal waters

Use of sediment-trace element geochemical models for the identification of local fluvial baseline concentrations

USGS Publications Warehouse

Horowitz, A.J.; Elrick, K.A.; Demas, C.R.; Demcheck, D.K.

1991-01-01

Studies have demonstrated the utility of fluvial bed sediment chemical data in assesing local water-quality conditions. However, establishing local background trace element levels can be difficult. Reference to published average concentrations or the use of dated cores are often of little use in small areas of diverse local petrology, geology, land use, or hydrology. An alternative approach entails the construction of a series of sediment-trace element predictive models based on data from environmentally diverse but unaffected areas. Predicted values could provide a measure of local background concentrations and comparison with actual measured concentrations could identify elevated trace elements and affected sites. Such a model set was developed from surface bed sediments collected nationwide in the United States. Tests of the models in a small Louisiana basin indicated that they could be used to establish local trace element background levels, but required recalibration to account for local geochemical conditions outside the range of samples used to generate the nationwide models.

Spatial distribution of heavy metals in surficial sediments from Guanabara Bay: Rio de Janeiro, Brazil

NASA Astrophysics Data System (ADS)

Neto, José Antônio Baptista; Gingele, Franz Xaver; Leipe, Thomas; Brehme, Isa

2006-04-01

Ninety-two surface sediment samples were collected in Guanabara Bay, one of the most prominent urban bays in SE Brazil, to investigate the spatial distribution of anthropogenic pollutants. The concentrations of heavy metals, organic carbon and particle size were examined in all samples. Large spatial variations of heavy metals and particle size were observed. The highest concentrations of heavy metals were found in the muddy sediments from the north western region of the bay near the main outlets of the most polluted rivers, municipal waste drainage systems and one of the major oil refineries. Another anomalous concentration of metals was found adjacent to Rio de Janeiro Harbour. The heavy metal concentrations decrease to the northeast, due to intact rivers and the mangrove systems in this area, and to the south where the sand fraction and open-marine processes dominate. The geochemical normalization of metal data to Li or Al has also demonstrated that the anthropogenic input of heavy metals have altered the natural sediment heavy metal distribution.

Characteristics of sediment data and annual suspended-sediment loads and yields for selected lower Missouri River mainstem and tributary stations, 1976-2008

USGS Publications Warehouse

Heimann, David C.; Rasmussen, Patrick P.; Cline, Teri L.; Pigue, Lori M.; Wagner, Holly R.

2010-01-01

Suspended-sediment data from 18 selected surface-water monitoring stations in the lower Missouri River Basin downstream from Gavins Point Dam were used in the computation of annual suspended-sediment and suspended-sand loads for 1976 through 2008. Three methods of suspended-sediment load determination were utilized and these included the subdivision method, regression of instantaneous turbidity with suspended-sediment concentrations at selected stations, and regression techniques using the Load Estimator (LOADEST) software. Characteristics of the suspended-sediment and streamflow data collected at the 18 monitoring stations and the tabulated annual suspended-sediment and suspended-sand loads and yields are presented.

Impacts of pollution derived from ship wrecks on the marine environment on the basis of s/s "Stuttgart" (Polish coast, Europe).

PubMed

Rogowska, Justyna; Wolska, Lidia; Namieśnik, Jacek

2010-11-01

In 1943 the German hospital ship s/s Stuttgart (Lazaretschiff "C") was sunk close to the port of Gdynia (Gulf of Gdańsk - Polish coast). This and other actions (undertaken after the war to remove the wreck) led to pollution of the sea bottom with oil derivatives. During our studies (2009) 11 surface sediment and water samples were collected as well as sediment core samples at 4 locations in order to determine the concentration levels of priority pollutants belonging to polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB). The concentrations of 16 PAH and 7 PCB were analysed with GC-MS. ΣPAH varied between 11.54 ± 0.39 and 206.7 ± 6.5mg/kg dry weight in the surface sediments, and from 0.686 ± 0.026 to 1291 ± 53 mg/kg dry weight in the core samples. Contamination in the core samples collected may reach a depth of at least 230-240 cm (deepest sample studied). The PAH-group profiles in all surface sediment samples suggest a pyrolytic source of PAH, while the results obtained for core samples indicate a mixed pattern of pyrolytic and petrogenic inputs of PAH. Results obtained may suggest also that fuel residues being present at sea bottom is not crude oil derived but results from coal processing (synthetic fuel). The sum of PCB in surface sediments ranged from 0.761 ± 0.068 to 6.82 ± 0.28 μg/kg dry weight (except for sampling point W2, where ΣPCB was 108.8 ± 4.4 μg/kg dry weight). The strong correlation between PAH and PCB levels, and the fact that PCB are present only in the surface sediments, suggest that the compounds in these sediments got there as a result of emission from urban areas, entering the aquatic environment via atmospheric deposition. PCB levels in the sediment core samples were generally very low and in most cases did not exceed the method quantification limit. Copyright © 2010 Elsevier B.V. All rights reserved.

Wildfire vs. Agricultural Operations: A Tale of Overprinted Disturbance Regimes

NASA Astrophysics Data System (ADS)

Gray, A. B.; Pasternack, G. B.; Watson, E. B.; Warrick, J. A.; Hatten, J. A.; Goni, M. A.

2016-12-01

Punctuated disturbances, such as wildfire, compete with interdecadal scale changes to land surfaces, such as shifting agricultural practices, resulting in complex trends in the suspended sediment transport dynamics of watersheds. A powerful, though data intensive approach to identifying dominant disturbance regimes is the application of retrospective forensic analysis, whereby time series of major factors potentially affecting watershed expression are investigated. In the test case, a decreasing trend in discharge corrected suspended sediment concentrations was found in the lower Salinas River, California between 1967 and 2011. Event to decadal scale patterns in sediment production in the Salinas River have been found to be largely controlled by antecedent hydrologic conditions, but decreasing suspended sediment concentrations over the last 15 years of the record departed from those expected from hydro-climatic forcing. Sediment production from the mountainous headwaters of the central California Coast Ranges, which are drained in part by the Salinas River, is known to be dominated by the interaction of wildfire and large rainfall/runoff events. However, the decreasing trend in Salinas River suspended sediment concentrations run contrary to increases in the watershed's effective burn area over time. The departure from hydrologic and wildfire forcing on suspended sediment concentration patterns was found to coincide with a rapid conversion of irrigation practices from sprinkler and furrow to subsurface drip irrigation. Changes in agricultural operations appear to have decreased sediment supply to the Salinas River over late 20th to early 21st century; obscuring the influence of wildfire on suspended sediment production.

Distribution of Cr, Pb, Cd, Zn, Fe and Mn in Lake Victoria sediments, East Africa

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

Onyari, J.M.; Wandiga, S.O.

1989-06-01

The presence of many metals at trace or ultra-trace levels in the human environment has received increased global attention. Sediments as a sink for pollutants are widely recognized pollution sources and diagenesis and biochemical transformations within the sediment may mobilize pollutants posing a threat to a wider biological community. The natural (background) concentrations of heavy metals in lake sediments can be estimated either by analysis of surface sediments in non-polluted regions or by analysis of core samples antedating modern pollution. The distribution pattern of heavy metals in tropical freshwater systems has been little studied. The authors found increased concentrations ofmore » lead and other trace metals in Lake Victoria. Thus this study was initiated in order to further investigate the distribution patterns of lead and other metals in Lake Victoria.« less

Effect of Cosolutes on the Sorption of Phenanthrene onto Mineral Surface of River Sediments and Kaolinite

PubMed Central

2014-01-01

Sorption of phenanthrene onto the natural sediment with low organic carbon content (OC%), organic-free sediment, and kaolinite was investigated through isotherm experiments. Effects of cosolutes (pyrene, 4-n-nonyphenol (NP), and humic acid (HA)) on phenanthrene sorption were also studied by comparing apparent solid-water distribution coefficients (K d app) of phenanthrene. Two addition sequences, including “cosolute added prior to phenanthrene” and “cosolute and phenanthrene added simultaneously,” were adopted. The Freundlich model fits phenanthrene sorption on all 3 sorbents well. The sorption coefficients on these sorbents were similar, suggesting that mineral surface plays an important role in the sorption of hydrophobic organic contaminants on low OC% sediments. Cosolutes could affect phenanthrene sorption on the sorbents, which depended on their properties, concentrations, and addition sequences. Pyrene inhibited phenanthrene sorption. Sorbed NP inhibited phenanthrene sorption at low levels and promoted sorption at high levels. Similar to NP, effect of HA on phenanthrene sorption onto the natural sediment depended on its concentrations, whereas, for the organic-free sediment and kaolinite, preloading of HA at high levels led to an enhancement in phenanthrene K d app while no obvious effect was observed at low HA levels; dissolved HA could inhibit phenanthrene sorption on the two sorbents. PMID:25147865

Transport and deposition of the fire biomarker levoglucosan across the tropical North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Schreuder, Laura T.; Hopmans, Ellen C.; Stuut, Jan-Berend W.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

2018-04-01

Biomass burning impacts biogeochemical cycling, vegetation dynamics and climate. However, interactions between fire, climate and vegetation are not well understood and therefore studies have attempted to reconstruct fire and vegetation history under different climatic conditions using sedimentary archives. Here we focus on levoglucosan, a thermal by-product of cellulose generated during biomass burning, and, therefore, a potential fire biomarker in the marine sedimentary archive. However, before levoglucosan can be applied as a biomass burning proxy in marine sediments, there is a need for studies on how levoglucosan is transported to the marine environment, how it is reflecting biomass burning on continents, as well as the fate of levoglucosan in the marine water column and during deposition in marine sediments. Here we present analyses of levoglucosan, using an improved Ultra High Pressure Liquid Chromatography-Electro Spray Ionization/High Resolution Mass Spectrometry (UHPLC-ESI/HRMS) method, in atmospheric particles, in particulate matter settling through the water column and in marine surface sediments on a longitudinal transect crossing the tropical North Atlantic Ocean at 12°N. Levoglucosan was detected in the atmosphere, although in low concentration, possibly due to the sampled particle size, the source area of the aerosols, or the short time interval of sampling by which large burning events may have been missed. In sinking particles in the tropical North Atlantic Ocean we find that levoglucosan deposition is influenced by a mineral ballast effect associated with marine biogenic particles, and that levoglucosan is not transported in association with mineral dust particles. Highest levoglucosan concentrations and seasonal differences in sinking particles were found close to continents and low concentrations and seasonal differences were found in the open ocean. Close to Africa, levoglucosan concentration is higher during winter, reflecting seasonal burning in northwestern Africa. However, close to South America levoglucosan concentrations appear to be affected by riverine transport from the Amazon River. In surface sediments close to South America, levoglucosan concentration is higher than in the middle of the Atlantic Ocean, implying that here the influence from the South American continent is important and perennial. Our study provides evidence that degradation of levoglucosan during settling in the marine water column is not substantial, but is substantial at the sediment-water interface. Nevertheless, levoglucosan was detected in all surface sediments throughout the tropical North Atlantic, indicating its presence in the marine sedimentary record, which reveals the potential for levoglucosan as a biomass burning proxy in marine sediments.

Occurrence of fungicides and other pesticides in surface water, groundwater, and sediment from three targeted-use areas in the United States, 2009

USGS Publications Warehouse

Orlando, James L.; Smalling, Kelly L.; Reilly, Timothy J.; Boehlke, Adam; Meyer, Michael T.; Kuivila, Kathryn

2013-01-01

Surface-water, groundwater, and suspended- and bedsediment samples were collected in three targeted-use areas in the United States where potatoes were grown during 2009 and analyzed for an extensive suite of fungicides and other pesticides by gas chromatograph/mass spectrometry and liquid chromatography with tandem mass spectrometry. Fungicides were detected in all environmental matrices sampled during the study. The most frequently detected fungicides were azoxystrobin, boscalid, chlorothalonil, and pyraclostrobin. Other pesticides that were detected frequently included amino phosphonic acid (AMPA), atrazine, metolaclor, and the organochlorine insecticide p,p’-DDT and its degradates p,p’-DDD and p,p’-DDE. A greater number of pesticides were detected in surface water relative to the other environmental matrices sampled, and at least one pesticide was detected in 62 of the 63 surfacewater samples. The greatest numbers of pesticides and the maximum observed concentrations for most pesticides were measured in surface-water samples from Idaho. In eight surface- water samples (six from Idaho and two from Wisconsin), concentrations of bifenthrin, metolachlor, or malathion exceeded U.S. Environmental Protection Agency freshwater aquatic-life benchmarks for chronic toxicity to invertebrates. Thirteen pesticides, including seven fungicides, were detected in groundwater samples. Shallow groundwater samples collected beneath recently harvested potato fields contained more pesticides and had higher concentrations of pesticides than samples collected from other groundwater sources sampled during the study. Generally, pesticide concentrations were lower in groundwater samples than in surfacewater or sediment samples, with the exception of the fungicide boscalid, which was found to have its highest concentration in a shallow groundwater sample collected in Wisconsin. Thirteen pesticides, including four fungicides, were detected in suspended-sediment samples. The most frequently detected compounds were the fungicides boscalid, pyraclostrobin, and zoxamide, and the degradates p,p’-DDD and p,p’-DDE. Twenty pesticides, including six fungicides, were detected in bed-sediment samples. The most frequently detected compounds were pyraclostrobin, p,p’-DDT, p,p’-DDD, and p,p’-DDE.

Geochemical and geo-statistical assessment of selected heavy metals in the surface sediments of the Gorgan Bay, Iran.

PubMed

Bastami, Kazem Darvish; Bagheri, Hossein; Haghparast, Sarah; Soltani, Farzaneh; Hamzehpoor, Ali; Bastami, Mousa Darvish

2012-12-01

We investigated heavy metal concentrations of zinc (Zn), copper (Cu), chromium (Cr), and lead (Pb), their spatial distribution and enrichment factor index in surface sediments of the Gorgan Bay. Sediment Quality Guidelines were also applied to assess adverse biological effects of these metals. Heavy metals were determined by inductively coupled plasma-mass spectroscopy (ICP-MS). The results indicated mean concentrations (ppm) of heavy metals were (mean±S.D.) Pb: 11.5±4.88, Cu: 18±8.83, Zn: 42±22.15 and Cr: 32±15.19. Based on Enrichment index, the Gorgan Bay is a low-enriched to non-enriched bay. Heavy metal contents were lower than the standard limits of PEL, ERL, and ERM that reveal no threatening influence of the metals in the Bay. Copyright © 2012 Elsevier Ltd. All rights reserved.

Distribution and pollution assessment of heavy metals in surface sediments in Xiaoqing river estuary and its adjacent sea of Laizhou bay

NASA Astrophysics Data System (ADS)

Wang, Li; Luo, Xianxiang; Fan, Yuqing

2018-03-01

In this paper, the monitoring results of four heavy metals Cu, Pb, Zn and Hg at 10 sampling stations in Xiaoqing river estuary and its adjacent sea of Laizhou Bay in November 2008 were analyzed and evaluated. The results showed that the concentrations of heavy metals in the steam channel and estuary are higher than those in the adjacent sea, and the metal concentrations were below the standard for I class of marine sediment quality, excepting the station 2 in the steam channel and station 5 in the estuary. The assessment of the single-factor pollution index showed that the overall pollution level of the study area was relatively low, but there was serious pollution phenomenon in individual station. The potential ecological risk of heavy metals in the surface sediments was generally at a low level, and Hg had the highest potential risk.

Response surface analysis and modeling of n-alkanes removal through bioremediation of weathered crude oil.

PubMed

Mohajeri, Leila; Abdul Aziz, Hamidi; Ali Zahed, Mohammad; Mohajeri, Soraya; Mohamed Kutty, Shamsul Rahman; Hasnain Isa, Mohamed

2011-01-01

Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.

Geochemical evidence for modern sediment accumulation on the continental shelf off southern New England

USGS Publications Warehouse

Bothner, Michael H.; Spiker, E. C.; Johnson, P. P.; Rendigs, R. R.; Aruscavage, P. J.

1981-01-01

An area of fine-grained sediment approximately 170 km x 74 km in size, located in water depths between 60 m and 150 m, south of Martha's Vineyard, Mass., is a site of modern sediment deposition. The 14C ages systematically increase with sediment depth from about 1,300 years B.P. at the surface to 8,000-10,000 years B.P. at the depth of maximum core penetration. The old age for the surface sediments probably results from a combination of deposition of old carbon and faunal mixing. In the finest sediments, the sedimentation rates were approximately 130 cm/1,000 yrs when deposition began and have decreased to about 25 cm/1,000 yrs. The decreasing sedimentation rate reflects a diminishing source of fine sediments, which presumably came from the Georges Bank and Nantucket Shoals area. Inventories of excess 210Pb in undisturbed cores average 70 dpm/cm2 (disintegrations per minute per square centimeter), more than two times higher than the flux of 210Pb from the atmosphere and from 226Ra decay in the overlying water. This additional influx of 210Pb either must be with new fine-grained sediment material or from solutions that are stripped of their 210Pb by particulates in the bottom nepheloid layer. Stable Pb concentrations in surface sediments are about 28 ppm, as much as two times higher than concentrations at depth. The high accumulation rates, 210Pb inventories, and trace-metal profiles imply that this area is a modern sink for fine-grained sediments and for pollutants associated with particulate matter in the water column. To our knowledge, this is the only site of present-day natural deposition on the Continental Shelf off the eastern United States, exclusive of the Gulf of Maine. Because the net currents on the outer half of this Continental Shelf flow from northeast to southwest, this fine-grained deposit may receive its sediments and possible contaminants from the Nantucket Shoals and Georges Bank regions.

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.

Cs-137 geochronology, epithermal neutron activation analysis, and principal component analysis of heavy metals pollution of the Black Sea anoxic continental shelf sediments

NASA Astrophysics Data System (ADS)

Duliu, O. G.; Cristache, C.; Oaie, G.; Culicov, O. A.; Frontasyeva, M. V.

2009-04-01

Anthropogenic Cs-137 Gamma-ray Spectroscopy assay (GrSA) performed at the National Institute of Research and Development for Physics and Nuclear Engineering - Bucharest (Romania) in correlation with Epithermal Neutrons Activation Analysis (ENAA) performed at the Joint Institute of Nuclear Researches - Dubna (Russia) were used to investigate a 50 cm core containing unconsolidated sediments collected at a depth of 600 m off Romanian town of Constantza, located in the anoxic zone of the Black Sea Continental Shelf. A digital radiography showed the presence of about 265 distinct laminae, 1 to 3 mm thick, a fact attesting a stationary sedimentary process, completely free of bioturbation. After being radiographed, the core was sliced into 45 segments whose thickness gradually increased from 0.5 to 5 cm, such that the minimum thickness corresponded to the upper part of the core. From each segment two aliquots of about 0.5 g and 50 g were extracted for subsequent ENAA and Cs-137 GrSA. The Cs-137 vertical profile evidenced two maxima, one of them was very sharp and localized at a depth of 1 cm and the other very broad, almost undistinguished at about 8 cm depth, the first one being attributed to 1986 Chernobyl accident. Based on these date, we have estimated a sedimentation ratio of about 0.5 mm/year, value taken as reference for further assessment of recent pollution history. By means of ENAA we have determined the vertical content of five presumed pollutants, e.i. Zn, As, Br, Sn and Sb and of Sc, as natural, nonpolluting element. In the first case, all five elements presented a more or less similar vertical profile consisting of an almost exponential decrease for the first 10 cm below sediment surface followed by a plateau until the core base, i.e. 50 cm below surface, dependency better described by the equation: c(z) = c0 [1+k exp (-z/Z)] (1) where: where c(z) represents the concentration vertical profile; z represents depth (in absolute value); c0 represents the plateau concentrations; k represents the surface to plateau relative increment of concentration; Z represents concentration decrement: the depth at which the concentration becomes 1+k times greater than plateau one. Final results have shown with clarity that in the case of Zn, As, Br, Sn and Sb, the concentrations near sediment surface were 1.6 to 4.1 times greater then the plateau ones while Sc vertical profile, excepting some small fluctuations observed between 18 to 25 cm below surface, shown to be almost constant. Moreover, the concentration decrements Z of Zn, Br, Sn and Sb were almost coincident within one standard deviation while in the case of As, this coincidence appears within two standard deviation, these facts pleading for a comparable time evolution in the past 100 years. On the other hand, in the case of Sn and As, the maximum concentrations were reached 1 cm below the sediment surface, roughly corresponding to 1990 year, while the concentrations of all other three elements monotonously increases up to sediment surface. Further Principal Components Analysis of the data concerning the vertical distribution of all six elements illustrates the presence of two distinct clusters, one consisting of Zn, As, Br, Sn and Sb and the other on only of Sn, attesting both differences and similarities in the vertical distribution of considered elements. By comparing the experimental concentrations of all five elements with Romania Regulations concerning heavy metal pollution, we remarked that, by respect to these Regulations the only Zn, As, Br and Sb slightly exceeded normal accepted limits while the minimum alert concentrations were exceeded only in few cases by of As and Br, but no elements concentrations reached the intervention threshold. In our opinion, these results reflect the dynamics of the industrial activity in the riparian to Danube River European countries: a steady increase beginning with the last half of the XIX-th century followed by a slightly decline after the fall of Communism.

Water-quality characteristics in runoff for three discovery farms in North Dakota, 2008-12

USGS Publications Warehouse

Nustad, Rochelle A.; Rowland, Kathleen M.; Wiederholt, Ronald

2015-01-01

Consistent patterns in water quality emerged at each individual farm, but similarities among farms also were observed. Suspended sediment, total phosphorus, and ammonia concentrations generally decreased downstream from feeding areas, and were primarily affected by surface runoff processes such as dilution, settling out of sediment, or vegetative uptake. Because surface runoff affects these constituents, increased annual surface runoff volume tended to result in increased loads and yields. No significant change in nitrate plus nitrite concentration were observed downstream from feeding areas because additional processes such as high solubility, nitrification, denitrification, and surface-groundwater interaction affect nitrate plus nitrite. For nitrate plus nitrite, increases in annual runoff volume did not consistently relate to increases in annual loads and yields. It seems that temporal distribution of precipitation and surface-groundwater interaction affected nitrate plus nitrite loads and yields. For surface drainage sites, the primary form of nitrogen was organic nitrogen whereas for subsurface drainage sites, the primary form of nitrogen was nitrate plus nitrite nitrogen.

Study on the sorption behaviour of estrone on marine sediments.

PubMed

Zhang, Jing; Yang, Gui-Peng; Li, Quan; Cao, Xiaoyan; Liu, Guangxing

2013-11-15

The sorption behaviour of estrone (E1) on marine sediments treated by different methods was systematically investigated. About 22 h was required for sorption equilibrium of E1. Sorption isotherms of E1 were well fitted with Freundlich model. The sorption behaviour of E1 on HCl-treatment and H2O-treatment sediments related significantly with the sediment organic carbon contents. Additionally, clay minerals and surface areas of sediments played dominant roles in the sorption of E1 on H2O2-treatment sediments. Some external factors which could affect sorption behaviour of E1 were also investigated. Our results showed that the sorption capacity of E1 on the sediments increased with the increasing concentrations of cationic surfactant cetyltrimethylammonium bromide (CTAB), nonionic surfactant polyoxyethylene (80) sorbitan esters (Tween 80) and salinity of seawater. In contrast, the sorption capacity of E1 decreased with the increasing concentration of anionic surfactant sodium dodecylbenzene sulfonate (SDBS), pH value and temperature of seawater. Copyright © 2013 Elsevier Ltd. All rights reserved.

Distribution, sources and ecological risk assessment of PAHs in surface sediments from the Luan River Estuary, China.

PubMed

Zhang, Daolai; Liu, Jinqing; Jiang, Xuejun; Cao, Ke; Yin, Ping; Zhang, Xunhua

2016-01-15

The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1 ng g(-1)dw with a mean value of 120.8 ng g(-1)dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of acid volatile sulfides and metal concentrations on metal partitioning in contaminated sediments

USGS Publications Warehouse

Lee, J.-S.; Lee, B.-G.; Luoma, S.N.; Choi, H.J.; Koh, C.-H.; Brown, C.L.

2000-01-01

The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 ??mol/g). The results were compared to sediments spiked with four levels of Cd-Ni-Zn mixtures at one AVS concentration (7.5 ??mol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65-95% due to oxidation during incubation; initial [AVS] was maintained at 0.5-7.5 cm depth. PW metal concentrations were correlated with [SEM - AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kd(pw) (the ratio of [SEM] to PW metal concentrations) to vary by 2-3 orders of magnitude at a given [SEM - AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM - AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM - AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd-Ni-Zn mixture (0.06, 3, 7.5 ??mol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 ??mol/g). The results were compared to sediments spiked with four levels of Cd-Ni-Zn mixtures at one AVS concentration (7.5 ??mol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65-95% due to oxidation during incubation; initial [AVS] was maintained at 0.5-7.5 cm depth. PW metal concentrations were correlated with [SEM - AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kdpw (the ratio of [SEM] to PW metal concentrations) to vary by 2-3 orders of magnitude at a given [SEM - AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM - AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM - AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.

Can acid volatile sulfides (AVS) influence metal concentrations in the macrophyte Myriophyllum aquaticum?

PubMed

Teuchies, Johannes; De Jonge, Maarten; Meire, Patrick; Blust, Ronny; Bervoets, Lieven

2012-08-21

The difference between the molar concentrations of simultaneously extracted metals (SEM) and acid volatile sulfides (AVS) is widely used to predict metal availability toward invertebrates in hypoxic sediments. However, this model is poorly investigated for macrophytes. The present study evaluates metal accumulation in roots and stems of the macrophyte Myriophyllum aquaticum during a 54 day lab experiment. The macrophytes, rooting in metal contaminated, hypoxic, and sulfide rich field sediments were exposed to surface water with 40% or 90% oxygen. High oxygen concentrations in the 90% treatment resulted in dissolution of the metal-sulfide complexes and a gradual increase in labile metal concentrations during the experiment. However, the general trend of increasing availability in the sediment with time was not translated in rising M. aquaticum metal concentrations. Processes at the root-sediment interface, e.g., radial oxygen loss (ROL) or the release of organic compounds by plant roots and their effect on metal availability in the rhizosphere may be of larger importance for metal accumulation than the bulk metal mobility predicted by the SEM-AVS model.

Numerical simulation of two-phase flow for sediment transport in the inner-surf and swash zones

NASA Astrophysics Data System (ADS)

Bakhtyar, R.; Barry, D. A.; Yeganeh-Bakhtiary, A.; Li, L.; Parlange, J.-Y.; Sander, G. C.

2010-03-01

A two-dimensional two-phase flow framework for fluid-sediment flow simulation in the surf and swash zones was described. Propagation, breaking, uprush and backwash of waves on sloping beaches were studied numerically with an emphasis on fluid hydrodynamics and sediment transport characteristics. The model includes interactive fluid-solid forces and intergranular stresses in the moving sediment layer. In the Euler-Euler approach adopted, two phases were defined using the Navier-Stokes equations with interphase coupling for momentum conservation. The k-ɛ closure model and volume of fluid approach were used to describe the turbulence and tracking of the free surface, respectively. Numerical simulations explored incident wave conditions, specifically spilling and plunging breakers, on both dissipative and intermediate beaches. It was found that the spatial variation of sediment concentration in the swash zone is asymmetric, while the temporal behavior is characterized by maximum sediment concentrations at the start and end of the swash cycle. The numerical results also indicated that the maximum turbulent kinetic energy and sediment flux occurs near the wave-breaking point. These predictions are in general agreement with previous observations, while the model describes the fluid and sediment phase characteristics in much more detail than existing measurements. With direct quantifications of velocity, turbulent kinetic energy, sediment concentration and flux, the model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in the nearshore zone.

The influence of fish feed pellets on the stability of seabed sediment: A laboratory flume investigation

NASA Astrophysics Data System (ADS)

Neumeier, Urs; Friend, Patrick L.; Gangelhof, Uffe; Lunding, Jens; Lundkvist, Morten; Bergamasco, Alessandro; Amos, Carl L.; Flindt, Mogens

2007-11-01

Superfluous fish food settling below fish farms can have a negative impact on the seabed. To aid in the assessment of this impact a series of flume experiments, designed to mimic seabed conditions below a fish farm, was conducted with the aim of examining the effects of fish pellets on the stability of fine sediments. Artificial beds, with varying quantities of fish pellets incorporated both within the sediment matrix and lying on the sediment surface, were allowed to consolidate for different periods of time ranging from 1 to 10 days, and then subjected to erosion experiments. In flume experiments containing fish pellets, a bacterial biofilm developed at the sediment-water interface after a few days. In the control experiments (no fish pellets), a diatom biofilm caused extensive stabilisation of the surface sediment. The erosion experiments showed that the addition of fish pellets reduced the surface erosion threshold by more than 50%. The stability decrease was more pronounced in the experiments with greater amounts of pellets. Evidence of drag reduction due to high suspended sediment concentration was also observed. This phenomenon is discussed and a correction formula is proposed for the effective shear stress experienced by the bed.

Mercury in Sediments From the Long Island Sound Region

NASA Astrophysics Data System (ADS)

Varekamp, J. C.; Lauriat, K.; Zierzow, T.; Buchholtz ten Brink, M.; Mecray, E.

2001-05-01

About 400 surface and core sediment samples from a sampling grid in Long Island Sound (LIS) were analyzed for mercury, Clostridium perfringens with many other chemical and physical parameters. About 16 cores from coastal salt marshes in Connecticut were analyzed as well. The Hg concentrations in LIS surface sediments vary between 30 and 650 ppb, with the highest values in the western end of LIS. The trend of increasing Hg to the west correlates with increasing abundances of fine-grained sediment and C-org. Normalization of the Hg data on mean grainsize or C-org contents still show an east-west trend. Data from the "12 mile sewage dump site" in the New York Bight area provide a linear relationship between C. perfringens and Hg. Using that relationship, we obtain that many LIS samples have 10-50 percent sewage-derived Hg, with values up to 70 percent in the extreme west. The remaining Hg is largely imported with fine-grained sediment from the surrounding watersheds, which is a focussed flux of the integrated regional atmospheric Hg deposition and point source mercury. The Housatonic River is an important source of mercury, with up to 5 ppm Hg in the river bed sediment. The Still River, a tributary of the Housatonic River, has sediments that carry up to 15 ppm Hg, and we surmise that the hatting industry of Danbury (CT) was an important Hg source. The in situ atmospheric deposition of Hg on LIS is only a small part of the overall LIS Hg sediment budget. Core data from LIS and surrounding marshes show contamination profiles with background values at 50-100 ppb Hg and peak values in the 200-500 range, with values up to 1200 ppb Hg at the mouth of the Housatonic River. Many cores show a decline in Hg concentrations in the upper 10-15 cm (last 40 years), whereas the C. perfringens concentrations increase exponentially towards the surface. The onset of Hg contamination coincides with the first elevated C. perfringens levels, indicating an anthropogenic origin for the Hg contamination.

Heavy metals and polycyclic aromatic hydrocarbons in surface sediments of Karoon River, Khuzestan Province, Iran.

PubMed

Keshavarzi, Behnam; Mokhtarzadeh, Zeinab; Moore, Farid; Rastegari Mehr, Meisam; Lahijanzadeh, Ahmadreza; Rostami, Soqra; Kaabi, Helena

2015-12-01

Karoon is the longest river in Iran and provides water for industries located along its banks, such as metal, petrochemical, and oil industries. It is also the source of drinking water for cities such as Ahwas, Abadan, and Khorramshahr. In this study, 34 and 18 surface sediment samples were collected and analyzed for heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and polycyclic aromatic hydrocarbons (PAHs). The measured concentrations of heavy metals were compared with US EPA sediment quality guidelines, and the results showed that Cu concentration was above the threshold effect level (TEL) in 65.67% of the samples and Hg concentration was above the effect range median (ERM) in some samples. The results revealed that Hg was severely enriched (5 < enrichment factor < 20) and classified in very high ecological risk index category. It is the major metallic contaminant in the study area. The total PAH concentrations ranged from 11.54-117,730 μg/kg, with the mean value of 7034.55 μg/kg dominated by lower molecular weight (LMW) PAHs. The total potentially carcinogenic PAHs (∑cPAHs) in sediment samples ranged from 2.09 to 31,930 μg/kg, indicating high carcinogenic potential of sediments in the study area. The total toxic equivalent (TEQ) values ranged from 1.06 to 7228.7 μg/kg. Maximum TEQ occurred in Abadan oil refinery station followed by Khorramshahr soap factory and Abadan petrochemical complex. Principal component analysis and cluster analysis also revealed the relationships between the studied parameters and identified their probable sources.

Platinum group elements in stream sediments of mining zones: The Hex River (Bushveld Igneous Complex, South Africa)

NASA Astrophysics Data System (ADS)

Almécija, Clara; Cobelo-García, Antonio; Wepener, Victor; Prego, Ricardo

2017-05-01

Assessment of the environmental impact of platinum group elements (PGE) and other trace elements from mining activities is essential to prevent potential environmental risks. This study evaluates the concentrations of PGE in stream sediments of the Hex River, which drains the mining area of the Bushveld Igneous Complex (South Africa), at four sampling points. Major, minor and trace elements (Fe, Ca, Al, Mg, Mn, V, Cr, Zn, Cu, As, Co, Ni, Cd, and Pb) were analyzed by FAAS and ETAAS in suspended particulate matter and different sediment fractions (<63, 63-500 and 500-2000 μm), and Pt, Pd, Rh, and Ir were measured by ICP-MS after removal of interfering elements (cation exchange resin 50W-DOWEX-X8). Procedures were blank-corrected and accuracy checked using reference materials. Nickel, Cr, Pt, Pd, Rh and Ir show concentrations 3-, 13- 18-, 28-, 48- and 44- fold the typical upper continental crust levels, respectively, although lower than concentrations reported for the parent rocks. The highest concentrations were observed closer to the mining area, decreasing with distance and in the <63 μm fraction, probably derived from atmospheric deposition and surface runoff of PGE-rich particles released from mining activities. Thus, mining activities are causing some disturbance of the surface PGE geochemical cycle, increasing the presence of PGE in the fine fraction of river sediments. We propose that indicators such as airborne particulate matter, and soil and river sediment quality, should be added to the protocols for evaluating the sustainability of mining activities.

The microbial nitrogen cycling potential is impacted by polyaromatic hydrocarbon pollution of marine sediments

DOE PAGES

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.; ...

2014-03-25

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. Furthermore, these data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems.« less

The microbial nitrogen cycling potential is impacted by polyaromatic hydrocarbon pollution of marine sediments

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

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.

2014-03-25

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. These data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems« less

The carbon cycle and biogeochemical dynamics in lake sediments

USGS Publications Warehouse

Dean, W.E.

1999-01-01

The concentrations of organic carbon (OC) and CaCO3 in lake sediments are often inversely related. This relation occurs in surface sediments from different locations in the same lake, surface sediments from different lakes, and with depth in Holocene sediments. Where data on accumulation rates are available, the relation holds for organic carbon and CaCO3 accumulation rates as well. An increase of several percent OC is accompanied by a decrease of several tens of percent CaCO3 indicating that the inverse relation is not due to simple dilution of one component by another. It appears from core data that once the OC concentration in the sediments becomes greater than about 12%, the CO2 produced by decomposition of that OC and production of organic acids lowers the pH of anoxic pore waters enough to dissolve any CaCO3 that reaches the sediment-water interface. In a lake with a seasonally anoxic hypolimnion, processes in the water column also can produce an inverse relation between OC and CaCO3 over time. If productivity of the lake increases, the rain rate of OC from the epilimnion increases. Biogenic removal of CO2 and accompanying increase in pH also may increase the production of CaCO3. However, the decomposition of organic matter in the hypolimnion will decrease the pH of the hypolimnion causing greater dissolution of CaCO3 and therefore a decrease in the rain rate of CaCO3 to the sediment-water interface.

[Spatial distribution and potential ecological risk assessment of heavy metals in sediments of Yalu River estuary wetland mudflat.

PubMed

Zhang, Chun Peng; Li, Fu Xiang

2016-09-01

Kriging interpolation analysis was conducted with ArcGIS to find out the distribution characteristics of heavy metals concentrations in the surface sediments of the coastal wetland mudflat on the Yalu River estuary, environmental risk index and Hakanson potential ecological risk index were used to assess their extents of pollution in this area.The concentrations of heavy metals in the surface sediments of the study area were at a relatively high level compared with the typical estuarine wetland. The concentration of heavy metals in the east was higher than that in the west, and in the human activity area, the concentration was higher. Cu was found to contribute the most to the pollution status based on environmental risk index method, while Hg and Cd produced the greatest potential ecological harm according to Hankanson Potential ecological risk index method. The average potential ecological risk index (RI) of the Yalu River estuary wetland was 189.30 (ranged from 93.65-507.20), suggesting a moderate ecological risk. However, the potential ecological risk was highest in the east and should be treated as the major heavy metal pollution prevention area in the future.

Effects-based spatial assessment of contaminated estuarine sediments from Bear Creek, Baltimore Harbor, MD, USA.

PubMed

Hartzell, Sharon E; Unger, Michael A; McGee, Beth L; Wilson, Sacoby M; Yonkos, Lance T

2017-10-01

Estuarine sediments in regions with prolonged histories of industrial activity are often laden to significant depths with complex contaminant mixtures, including trace metals and persistent organic pollutants. Given the complexity of assessing risks from multi-contaminant exposures, the direct measurement of impacts to biological receptors is central to characterizing contaminated sediment sites. Though biological consequences are less commonly assessed at depth, laboratory-based toxicity testing of subsurface sediments can be used to delineate the scope of contamination at impacted sites. The extent and depth of sediment toxicity in Bear Creek, near Baltimore, Maryland, USA, was delineated using 10-day acute toxicity tests with the estuarine amphipod Leptocheirus plumulosus, and chemical analysis of trace metals and persistent organic pollutants. A gradient of toxicity was demonstrated in surface sediments with 21 of 22 tested sites differing significantly from controls. Effects were most pronounced (100% lethality) at sites proximate to a historic industrial complex. Sediments from eight of nine core samples to depths of 80 cm were particularly impacted (i.e., caused significant lethality to L. plumulosus) even in locations overlain with relatively non-toxic surface sediments, supporting a conclusion that toxicity observed at the surface (top 2 cm) does not adequately predict toxicity at depth. In seven of nine sites, toxicity of surface sediments differed from toxicity at levels beneath by 28 to 69%, in five instances underestimating toxicity (28 to 69%), and in two instances overestimating toxicity (44 to 56%). Multiple contaminants exceeded sediment quality guidelines and correlated positively with toxic responses within surface sediments (e.g., chromium, nickel, polycyclic aromatic hydrocarbon (PAH), total petroleum hydrocarbon). Use of an antibody-based PAH biosensor revealed that porewater PAH concentrations also increased with depth at most sites. This study informs future management decisions concerning the extent of impact to Bear Creek sediments, and demonstrates the benefits of a spatial approach, relying primarily on toxicity testing to assess sediment quality in a system with complex contaminant mixtures.

Drivers of Microbial Metabolic Activity, Biogeochemical Cycling and Associated Greenhouse Gas Production in Streambed Sediments

NASA Astrophysics Data System (ADS)

Comer-Warner, S.; Krause, S.; Gooddy, D.; Blaen, P.; Brekenfeld, N.; Wexler, S.; Kaiser, J.

2017-12-01

Hotspots of enhanced biogeochemical reactivity are produced where groundwater and surface water mixes in streambed sediments. This enhanced reactivity is due to elevated residence times and nutrient concentrations found in these areas, leading to increased rates of microbial metabolic activity. Streambed sediments, therefore, may be important in reducing catchment-wide nutrient concentrations through increased cycling. However, they also have the potential to produce high concentrations of greenhouse gases (CO2, CH4 and N2O), as end-products of respiration and intermediate products of denitrification. The hydrological and biogeochemical drivers of streambed C and N cycling, are still insufficiently understood. Here we present results from biogeochemical sampling and tracer experiments in an agricultural sandstone stream in the UK. Nutrient, DOC and greenhouse gas concentrations, as well as d13CCO2, were measured in the streambed sediment in multilevel piezometers, and nutrient concentrations, as well as d15NNO3 and d18ONO3, were measured in Diffusive Equilibrium in Thin-film Gels. Tracer experiments using both conservative (Fluorescein and NaCl) and smart (Resazurin-Resorufin) tracers were performed to determine in-stream metabolism, transient storage and solute transport times in sub-reaches of the stream. Our results show large differences in nutrient and greenhouse gas concentrations between sub-reaches dominated by gravel sediments and those dominated by sandy sediments, as well as seasonally. This suggests temperature, sediment type and residence time are key controls on streambed nutrient cycling and greenhouse gas production. The results of this study have important implications for future greenhouse gas estimates from streams and rivers, particularly as the contribution of sediment greenhouse gas production is recognised as increasingly significant.

Distribution and sources of polycyclic aromatic hydrocarbons and phthalic acid esters in water and surface sediment from the Three Gorges Reservoir.

PubMed

Lin, Li; Dong, Lei; Meng, Xiaoyang; Li, Qingyun; Huang, Zhuo; Li, Chao; Li, Rui; Yang, Wenjun; Crittenden, John

2018-07-01

After the impoundment of the Three Gorges Reservoir (TGR), the hydrological situation of the reservoir has changed greatly. The concentration and distribution of typical persistent organic pollutants in water and sediment have also changed accordingly. In this study, the concentration, distribution and potential sources of 16 polycyclic aromatic hydrocarbons (PAHs) and 6 phthalic acid esters (PAEs) during the water drawdown and impoundment periods were investigated in water and sediment from the TGR. According to our results, PAHs and PAEs showed temporal and spatial variations. The mean ΣPAH and ΣPAE concentrations in water and sediment were both higher during the water impoundment period than during the water drawdown period. The water samples from the main stream showed larger ΣPAH concentration fluctuations than those from tributaries. Both the PAH and PAE concentrations meet the Chinese national water environmental quality standard (GB 3838-2002). PAH monomers with 2-3 rings and 4 rings were dominant in water, and 4-ring and 5-6-ring PAHs were dominant in sediment. Di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) were the dominant PAE pollutants in the TGR. DBP and DEHP had the highest concentrations in water and sediment, respectively. The main source of PAHs in water from the TGR was petroleum and emissions from coal and biomass combustion, whereas the main sources of PAHs in sediments included coal and biomass combustion, petroleum, and petroleum combustion. The main source of PAEs in water was domestic waste, and the plastics and heavy chemical industries were the main sources of PAEs in sediment. Copyright © 2017. Published by Elsevier B.V.

Persistence and distribution of 4-nonylphenol in water, sediment, macrophytes, and wall material of littoral enclosures

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

Heinis, L.J.; Tunell, R.; Liber, K.

1994-12-31

Eighteen enclosures (5 m x 10 m) were constructed in the littoral zone of a 2-ha pond near Duluth, MN. Each enclosure consisted of 5 m of natural shoreline and three walls of an inert plastic. The enclosures had an average surface area of 31.9 m{sup 2} , an average depth of 0.6 m and an average water volume of 33.1 m{sup 3}. The enclosure waters were treated with the alkyl phenol ethoxylate precursor and degradation product 4-nonylphenol. Application was accomplished by sub-surface injection over a 20-day period with a 2 day frequency. Nominal aqueous concentrations were 0, 3, 30,more » 100 and 300 {mu}g/L. Concentrations of 4-nonylphenol were monitored during and after application in the water, sediment, macrophytes, and enclosure wall material. Average maximum water concentrations ranged from 96.5% of nominal to 62.0% of nominal and average minimum water concentrations ranged from 33.3% of nominal to 29.5% of nominal during the application period. Water concentrations decreased exponentially after application ended. Sediment concentrations during the application period were constant from 8 to 20 d and peak concentrations occurred 48 d after application began. Macrophyte concentrations peaked 21 d after initial application with a steady decline through 76 d. Enclosure wall material concentrations reached a peak 3 h before the final application. A gradual decline occurred until 34 d after initial application followed by a more rapid dissipation.« less

Assessing the Influence of Copper-Nickel-Bearing Bedrock on Baseline Water Quality in Filson Creek Watershed, Northeast Minnesota

NASA Astrophysics Data System (ADS)

Runkel, R. L.; Jones, P. M.; Elliott, S. M.; Woodruff, L. G.

2017-12-01

Mining sulfide-bearing copper (Cu), nickel (Ni), and platinum-group-elements (PGE) deposits in the Duluth Complex of northeast Minnesota could have detrimental effects on surrounding water resources and associated ecosystems. A study was conducted to 1) assess copper, nickel, and other metal concentrations in surface water, bedrock, streambed sediments, and soils in watersheds where the basal part of the Duluth Complex is exposed or near the land surface; and 2) determine if these concentrations, and metal-bearing deposits, are currently influencing regional water quality in areas of potential base-metal mining. One of the watersheds that was assessed was the Filson Creek watershed, where shallow Cu-Ni-PGE deposits are present. Field water-quality, streambed sediments, soils, bedrock, and streamflow data set were collected in Filson Creek and it's watershed in 2014 and 2015. Surface-water samples were analyzed for 12 trace metals (dissolved and total concentrations), 14 inorganic constituents (dissolved concentrations), alkalinity, 18 O /16O and 2H/1H isotopes, and total and dissolved organic carbon. Background total Cu and Ni concentrations in the creek in 2014 and 2015 ranged from 1.2 to 10.8 micrograms per liter (µg/L), and 1.7 to 8.4 µg/L, respectively. The concentrations of copper, nickel, and other trace metals in surface waters and streambed sediments reflects the geochemistry of underlying rock types and glacially transported unconsolidated material, establishing baseline conditions prior to any mining. Dissolved and total organic carbon (DOC and TOC) concentrations in surface waters are very high compared to most surface waters in Minnesota, ranging from 21.3 to 43.2 milligrams per liter (mg/L), and 22.4 and 53.5 mg/L. Synoptic water-quality and flow data from a tracer test conducted over a stream segment of Filson Creek above a shallow Cu-Ni-PGE deposit (Spruce Road Deposit) was used with the 2014-15 water-quality and synthetic flow data to calibrate the reactive transport model. Results from transport modeling suggest that the high DOC content exert control on copper and other trace metal transport.

Distribution and flux estimates of soluble, colloidal, and leachable particulate trace metals in dynamic and oxygen depleted Mauritanian shelf waters

NASA Astrophysics Data System (ADS)

Rapp, I.; Schlosser, C.; Gledhill, M.; Achterberg, E. P.

2016-02-01

Fe availability in surface waters determines primary production, N2 fixation and microbial community structure and thus plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling areas with oxygen minimum zones, such as the Mauritanian shelf region, are typically associated with elevated Fe concentrations with shelf sediments as key source of Fe to bottom and surface waters. The magnitude of vertical and horizontal Fe fluxes from shelf sediments to onshore and offshore surface waters are not well constrained and there are still large uncertainties concerning the stabilisation of Fe once released from sediments into suboxic and oxic waters. Supportive data of other trace metals can be used as an indicator of sediment release, scavenging processes and biological utilisation. Here we present soluble (<0.02 µm), dissolved (<0.2 µm) and total dissolvable (unfiltered) trace metal data collected at 10 stations on a 90 nautical mile transect across the Mauritanian shelf region in June 2014 (cruise Meteor 107). The samples were pre-concentrated using an automated off-line pre-concentration device and analysed simultaneously for Cd, Pb, Fe, Ni, Cu, Zn, Mn and Co using a high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). First results indicate the importance of benthic sources to the overall Fe budget in this region. Both dissolved Fe and Mn showed enhanced concentrations close to the shelf at depths between 40 and 180 m corresponding with low oxygen concentrations (<50 µmol L-1). Elevated soluble, dissolved, and total dissolvable Fe and Mn concentrations at an offshore station coincided with the location of a cyclonic Eddie that was characterised by an oxygen depleted water body. To further assess the accuracy of vertical and horizontal fluxes of Fe and other trace metals, we compare diffusivity estimates determined by a microstructure profiler and the scale length method (de Jong et al. 2012) with observed isotopic Ra data.

Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

PubMed Central

Mayer, Philipp; Parkerton, Thomas F; Adams, Rachel G; Cargill, John G; Gan, Jay; Gouin, Todd; Gschwend, Philip M; Hawthorne, Steven B; Helm, Paul; Witt, Gesine; You, Jing; Escher, Beate I

2014-01-01

Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminant's chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree. Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments. Integr Environ Assess Manag 2014;10:197–209. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:24288295

Water-quality assessment of the Kentucky River Basin, Kentucky; distribution of metals and other trace elements in sediment and water, 1987-90

USGS Publications Warehouse

Porter, Stephen D.; White, Kevin D.; Clark, J.R.

1995-01-01

The U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program is designed to provide a nationally consistent description of the current status of water quality, to define water-quality trends, and to relate past and present water-quality conditions to natural features, uses of land and water, and other water-quality effects from human activities. The Kentucky River Basin is one of four NAWQA pilot projects that focused primarily on the quality of surface water. Water, sediment, and bedrock samples were collected in the Kentucky River Basin during 1987-90 for the purpose of (1) describing the spatial distribution, transport, and temporal variability of metals and other trace elements in streams of the basin; (2) estimating mean annual loads, yields, and trends of constituent concentrations and identifying potential causes (or sources) of spatial patterns; (3) providing baseline information for concentrations of metals in streambed and suspended sediments; (4) identifying stream reaches in the Kentucky River Basin with chronic water-quality problems; and (5) evaluating the merits of the NAWQA pilot study-approach for the assessment of metals and other trace elements in a river system. The spatial distribution of metals and other trace elements in streambed sediments of the Kentucky River Basin is associated with regional differences of geology, land use and cover, and the results of human activities. Median concentrations of constituents differed significantly among physiographic regions of the basin because of relations to bedrock geochemistry and land disturbance. Concentrations of potentially toxic metals were large in urban and industrial areas of the basin. Elevated concentrations of certain metals were also found in streambed sediments of the Knobs Region because of the presence of Devonian shale bedrock. Elevated concentrations of lead and zinc found in streambed sediments of the Bluegrass Region are likely associated with urban stormwater runoff, point-source discharges, and waste-management practices. Concentrations of cadmium, chromium, copper, mercury, and silver were elevated in streambed sediments downstream from wastewater-treatment plant discharges. Streambed-sediment concentrations of barium, chromium, and lithium were elevated in streams that receive brine discharges from oil production. Elevated concentrations of antimony, arsenic, molybdenum, selenium, strontium, uranium, and vanadium in streambed sediments of the Kentucky River Basin were generally associated with natural sources. Concentrations of metals and other trace elements in water samples from fixed stations (stations where water-quality samples were collected for 3.5 years) in the Kentucky River Basin were generally related to stream discharge and the concentration of suspended sediment, whereas constituent concentrations in the suspended-sediment matrix were indicative of natural and human sources. Estimated mean annual loads and yields for most metals and other trace elements were associated with the transport of suspended sediment. Land disturbance, such as surface mining and agriculture, contribute to increased transport of sediment in streams, thereby increasing concentrations of metals in water samples during periods of intense or prolonged rainfall and increased stream discharge. Concentrations of many metals and trace elements were reduced during low streamflow. Although total-recoverable and dissolved concentrations of certain metals and trace elements were large in streams affected by land disturbance, concentrations of constituents in the suspendedsediment matrix were commonly large in streams in the Knobs and Eastern Coal Field Regions (because of relations with bedrock geochemistry) and in streams that receive wastewater or oil-well-brine discharges. Concentrations and mean annual load estimates for aluminum, chromium, copper, iron, lead, manganese, and mercury were larger than those obtained from data collected by a State agency, probably because of differences in sample-collection methodology, the range of discharge associated with water-quality samples, and laboratory analytical procedures. However, concentrations, loads, and yields of arsenic, barium, and zinc were similar to those determined from the State data. Significant upward trends in the concentrations of aluminum, iron, magnesium, manganese, and zinc were indicated at one or more fixed stations in the Kentucky River Basin during the past 10 to 15 years. Upward trends for concentrations of aluminum, iron, and manganese were found at sites that receive drainage from coal mines in the upper Kentucky River Basin, whereas upward trends for zinc may be associated with urban sources. Water-quality criteria established by the U.S. Environmental Protection Agency (USEPA) or the State of Kentucky for concentrations of aluminum, beryllium, cadmium, chromium, copper, iron, manganese, nickel, silver, and zinc were exceeded at one or more fixed stations in the Kentucky River Basin. On a qualitative basis, dissolved concentrations of certain metals and trace elements were large during low streamflow at sites where (1) concentrations of these constituents in underlying streambed sediments were large, or (2) dissolvedoxygen concentrations were small. Concentrations of barium, lithium, and strontium were large during low streamflow, which indicates the influence of ground-water baseflows on the quality of surface water during low flow. The effects of point-source discharges, landfills, and other wastemanagement practices are somewhat localized in the Kentucky River Basin and are best indicated by the spatial distribution of metals and other trace elements in streambed sediments and in the suspended-sediment fraction of water samples at stream locations near the source. It was not possible to quantify the contribution of point sources to the total transport of metals and other trace elements at fixed stations because data were not available for wastewater effluents. Quantification of baseline concentrations of metals and other trace elements in streambed sediments provides a basis for the detection of water-quality changes that may result from improvements in wastewater treatment or the implementation of best-management practices for controlling contamination from nonpoint sources in the Kentucky River Basin.

Subsurface sediment contamination during borehole drilling with an air-actuated down-hole hammer.

PubMed

Malard, Florian; Datry, Thibault; Gibert, Janine

2005-10-01

Drilling methods can severely alter physical, chemical, and biological properties of aquifers, thereby influencing the reliability of water samples collected from groundwater monitoring wells. Because of their fast drilling rate, air-actuated hammers are increasingly used for the installation of groundwater monitoring wells in unconsolidated sediments. However, oil entrained in the air stream to lubricate the hammer-actuating device can contaminate subsurface sediments. Concentrations of total hydrocarbons, heavy metals (Cu, Ni, Cr, Zn, Pb, and Cd), and nutrients (particulate organic carbon, nitrogen, and phosphorus) were measured in continuous sediment cores recovered during the completion of a 26-m deep borehole drilled with a down-hole hammer in glaciofluvial deposits. Total hydrocarbons, Cu, Ni, Cr and particulate organic carbon (POC) were all measured at concentrations far exceeding background levels in most sediment cores. Hydrocarbon concentration averaged 124 +/- 118 mg kg(-1) dry sediment (n = 78 samples) with peaks at depths of 8, 14, and 20 m below the soil surface (maximum concentration: 606 mg kg(-1)). The concentrations of hydrocarbons, Cu, Ni, Cr, and POC were positively correlated and exhibited a highly irregular vertical pattern, that probably reflected variations in air loss within glaciofluvial deposits during drilling. Because the penetration of contaminated air into the formation is unpreventable, the representativeness of groundwater samples collected may be questioned. It is concluded that air percussion drilling has strong limitations for well installation in groundwater quality monitoring surveys.

Spatio-temporal variations in the composition of organic matter in surface sediments of a mangrove receiving shrimp farm effluents (New Caledonia).

PubMed

Aschenbroich, Adélaïde; Marchand, Cyril; Molnar, Nathalie; Deborde, Jonathan; Hubas, Cédric; Rybarczyk, Hervé; Meziane, Tarik

2015-04-15

In order to investigate spatio-temporal variations in the composition and origin of the benthic organic matter (OM) at the sediment surface in mangrove receiving shrimp farm effluents, fatty acid (FA) biomarkers, natural stable isotopes (δ(13)C and δ(15)N), C:N ratios and chlorophyll-a (chl-a) concentrations were determined during the active and the non-active period of the farm. Fatty acid compositions in surface sediments within the mangrove forest indicated that organic matter inputs varied along the year as a result of farm activity. Effluents were the source of fresh particulate organic matter for the mangrove, as evidenced by the unsaturated fatty acid (UFA) distribution. The anthropogenic MUFA 18:1ω9 was not only accumulated at the sediment surface in some parts of the mangrove, but was also exported to the seafront. Direct release of bacteria and enhanced in situ production of fungi, as revealed by specific FAs, stimulated mangrove litter decomposition under effluent runoff condition. Also, microalgae released from ponds contributed to maintain high benthic chl-a concentrations in mangrove sediments in winter and to a shift in microphytobenthic community assemblage. Primary production was high whether the farm released effluent or not which questioned the temporary effect of shrimp farm effluent on benthic microalgae dynamic. This study outlined that mangrove benthic organic matter was qualitatively and quantitatively affected by shrimp farm effluent release and that responses to environmental condition changes likely depended on mangrove stand characteristics. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Prediction of the fate of p,p'-DDE in sediment on the Palos Verdes shelf, California, USA

USGS Publications Warehouse

Sherwood, C.R.; Drake, D.E.; Wiberg, P.L.; Wheatcroft, R.A.

2002-01-01

Long-term (60-yr) predictions of vertical profiles of p,p???-DDE concentrations in contaminated bottom sediments on the Palos Verdes shelf were calculated for three locations along the 60-m isobath using a numerical solution of the one-dimensional advection-diffusion equation. The calculations incorporated the following processes: sediment deposition (or erosion), depth-dependent solid-phase biodiffusive mixing, in situ diagenetic transformation, and loss of p,p???-DDE across the sediment-water interface by two mechanisms (resuspension of sediments by wave action and subsequent loss of p,p???-DDE to the water column by desorption, and desorption from sediments to porewater and subsequent molecular diffusion to the water column). A combination of field measurements, laboratory analyses, and calculations with supporting models was used to set parameters for the model. The model explains significant features observed in measurements made every 2 years from 1981 to 1997 by the County Sanitation Districts of Los Angeles (LACSD). Analyses of available data suggest that two sites northwest of the Whites Point sewage outfalls will remain depositional, even as particulate supply from the sewage-treatment plant and nearby Portuguese Bend Landslide decreases. At these sites, model predictions for 1991-2050 indicate that most of the existing inventory of p,p???-DDE will remain buried and that surface concentrations will gradually decrease. Analyses of data southeast of the outfalls suggest that erosion is likely to occur somewhere on the southeast edge of the existing effluent-affected deposit, and model predictions for such a site showed that erosion and biodiffusion will reintroduce the p,p???-DDE to the upper layer of sediments, with subsequent increases in surface concentrations and loss to the overlying water column.

Sources of mercury to San Francisco Bay surface sediment as revealed by mercury stable isotopes

USGS Publications Warehouse

Gehrke, Gretchen E.; Blum, Joel D.; Marvin-DePasquale, Mark

2011-01-01

Mercury (Hg) concentrations and isotopic compositions were examined in shallow-water surface sediment (0–2 cm) from San Francisco (SF) Bay to determine the extent to which historic Hg mining contributes to current Hg contamination in SF Bay, and to assess the use of Hg isotopes to trace sources of contamination in estuaries. Inter-tidal and wetland sediment had total Hg (HgT) concentrations ranging from 161 to 1529 ng/g with no simple gradients of spatial variation. In contrast, inter-tidal and wetland sediment displayed a geographic gradient of δ202Hg values, ranging from -0.30% in the southern-most part of SF Bay (draining the New Almaden Hg District) to -0.99% in the northern-most part of SF Bay near the Sacramento–San Joaquin River Delta. Similar to SF Bay inter-tidal sediment, surface sediment from the Alviso Slough channel draining into South SF Bay had a δ202Hg value of -0.29%, while surface sediment from the Cosumnes River and Sacramento–San Joaquin River Delta draining into north SF Bay had lower average δ202Hg values of -0.90% and -0.75%, respectively. This isotopic trend suggests that Hg-contaminated sediment from the New Almaden Hg District mixes with Hg-contaminated sediment from a low δ202Hg source north of SF Bay. Tailings and thermally decomposed ore (calcine) from the New Idria Hg mine in the California Coast Range had average δ202Hg values of -0.37 and +0.03%, respectively, showing that Hg calcination fractionates Hg isotopes resulting in Hg contamination from Hg(II) mine waste products with higher δ202Hg values than metallic Hg(0) produced from Hg mines. Thus, there is evidence for at least two distinct isotopic signals for Hg contamination in SF Bay: Hg associated with calcine waste materials at Hg mines in the Coast Range, such as New Almaden and New Idria; and Hg(0) produced from these mines and used in placer gold mines and/or in other industrial processes in the Sierra Nevada region and SF Bay area.

Evaluation of triclosan in Minnesota lakes and rivers: Part I - ecological risk assessment.

PubMed

Lyndall, Jennifer; Barber, Timothy; Mahaney, Wendy; Bock, Michael; Capdevielle, Marie

2017-08-01

Triclosan, an antimicrobial compound found in consumer products, may be introduced into the aquatic environment via residual concentrations in municipal wastewater treatment effluent. We conducted an aquatic risk assessment that incorporated the available measured triclosan data from Minnesota lakes and rivers. Although only data reported from Minnesota were considered in the risk assessment, the developed toxicity benchmarks can be applied to other environments. The data were evaluated using a series of environmental fate models to ensure the data were internally consistent and to fill any data gaps. Triclosan was not detected in over 75% of the 567 surface water and sediment samples. Measured environmental data were used to model the predicted environmental exposures to triclosan in surface water, surface sediment, and biota tissues. Toxicity benchmarks based on fatty acid synthesis inhibition and narcosis were determined for aquatic organisms based, in part, on a species sensitivity distribution of chronic toxicity thresholds from the available literature. Predicted and measured environmental concentrations for surface water, sediment, and tissue were below the effects benchmarks, indicating that exposure to triclosan in Minnesota lakes and rivers would not pose an unacceptable risk to aquatic organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto regional water quality control plant in south San Francisco Bay, California: 2005

USGS Publications Warehouse

Cain, Daniel J.; Parcheso, Francis; Thompson, Janet K.; Luoma, Samuel N.; Lorenzi, Allison H.; Moon, Edward; Shouse, Michelle K.; Hornberger, Michelle I.; Dyke, Jessica

2006-01-01

Trace elements in sediment and the clam Macoma petalum (formerly reported as Macoma balthica (Cohen and Carlton 1995), clam reproductive activity and benthic, macroinvertebrate community structure are reported for a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay. This report includes data collected for the period January to December 2005, and extends a critical long-term biogeochemical record dating back to 1974. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. Metal concentrations in both sediments and clam tissue during 2005 were consistent with results observed since 1990. Copper and zinc concentrations in sediment and bivalve tissue displayed a continued decrease over the last decade. In 2005, Cu concentrations were at or below the effects range-low (ERL) concentration (34 ?g/g) for the entire year, the first time this has been observed. Also, zinc concentrations never exceeded the ERL (150 ?g/g). Yearly average concentrations of copper, zinc and silver in Macoma petalum for 2005 were some of the lowest recorded since monitoring for metals began in 1975. The concentrations of mercury and selenium in sediments, during April and January 2004, respectively, were the highest values observed for these elements during this study. Later in 2005, concentrations decreased to historic levels. The increase in mercury and selenium in 2004 was not a permanent trend and concentrations of these elements in sediments and clams at Palo Alto remain similar to concentrations observed elsewhere in the San Francisco Bay. Analyses of the benthic-community structure of a mudflat in South San Francisco Bay over a 31-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinal clam Macoma petalum from the same area. Analysis of the reproductive activity of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable with almost all animals initiating reproduction in the fall and spawning the following spring of most years. The community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that suggests a more stable community that is subjected to less stress. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals. Heteromastus filiformis, a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying their eggs on or in the sediment has shown a concurrent increase in dominance. These changes in species dominance reflect a change in the community from one dominated by surface dwelling, brooding species to one with species with varying life history characteristics. For the first time since its invasion in 1986, the non-indigenous filter-feeding bivalve Corbula (Potamocorbula) amurensis has shown up in small but persistent numbers in the benthic community.

Oceanographic controls on sedimentary and geochemical facies on the Peru outer shelf and upper slope

USGS Publications Warehouse

Arthur, Michael A.; Dean, Walter E.

2013-01-01

Concentrations and characteristics of organic matter in surface sediments deposited under an intense oxygen-minimum zone (OMZ) on the Peru margin were mapped and studied in samples from deck-deployed box cores and push cores acquired by submersible on two east-west transects spanning depths of 75 to 1,000 meters (m) at 12°S and 13.5°S. On the basis of sampling and analyses of the top 1–2 centimeters (cm) of available cores, three main belts of sediments were identified on each transect with increasing depth: (1) muds rich in organic carbon (OC); (2) authigenic phosphatic mineral crusts and pavements; and (3) glaucony facies.Sediments rich in OC on the 12°S transect were mainly located on the outer shelf and upper slope (150–350 m), but they occurred in much shallower water (approximately 100 m) on the 13.5°S transect. The organic matter is almost entirely marine as confirmed by Rock-Eval pyrolysis and isotopic composition of OC. Concentrations of OC are highest (up to 18 percent) in sediments within the OMZ where dissolved oxygen (DO) concentrations are <5 micromoles per kilogram (μM). Even at these low concentrations of DO, however, the surface sediments from within the OMZ are dominantly unlaminated. Concentrations of DO may have the dominant effect on organic matter characteristics, but reworking of fine-grained sediment and organic matter by strong bottom currents with velocities as high as 30 centimeters per second (cm/s) on the slope between 150 and 300 m and redeposition on the seafloor in areas of lower energy and higher DO concentration also exert important controls on OC concentration and degree of oxidation in this region.Phosphate-rich sediments and crusts occurred at depths of about 300 to 550 m on both transects. Nodular crusts of sediment cemented by carbonate-fluorapatite (CFA; phosphorite) or dolomite form within the OMZ. These phosphorite crusts evolve through cementation from light olive-green, stiff but friable, phosphatized claystone “protocrusts” through dense, dark phosphorite crusts, cemented breccias, and pavements. The degree of phosphatization and thickness of the crusts depend on the rates of sediment supply and on the strength and frequency of currents that re-expose crusts on the seafloor. Phosphorite crusts and pavements on the Peru margin can only become buried and incorporated into the geologic record once bottom currents slacken sufficiently to allow fine-grained sediment to accumulate.Glaucony-rich surface sediments, relatively undiluted by other components, were found mainly in deeper water on the 13.5°S transect (750 m to at least 1,067 m). These sediments consist almost entirely of sand-size glaucony pellets. These widespread glaucony sands formed in place and were then concentrated and reworked by strong currents that winnowed away the fine-grained matrix. Although the glaucony occurs in sand-size pellets, the pellets are made up of aggregates of authigenic, platy, micaceous clay minerals. Glaucony is predominantly a potassium (K), sodium (Na), iron (Fe), magnesium (Mg) aluminosilicate with an approximate formula of (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2. The glaucony on the 13.5°S transect forms by alteration of one or more original “framework” minerals (carbonate and [or] aluminosilicates) to form pellital aggregates of Fe-, K-, and Mg-rich clay minerals. Because Fe, K, and Mg are derived from seawater, sedimentation rates must be extremely slow in order for the original framework minerals to remain in contact with seawater. The close association of glaucony and phosphorite indicates a delicate balance between the slightly oxidizing conditions at the base of the OMZ that form glaucony and the slightly reducing conditions that mobilize iron and phosphate to form phosphorite.

Estuarine water-quality and sediment data, and surface-water and ground-water-quality data, Naval Submarine Base Kings Bay, Camden County, Georgia, January 1999

USGS Publications Warehouse

Leeth, David C.; Holloway, Owen G.

2000-01-01

In January 1999, the U.S. Geological Survey collected estuarine-water, estuarine-sediment, surface-water, and ground-water quality samples in the vicinity of Naval Submarine Base Kings Bay, Camden County, Georgia. Data from these samples are used by the U.S. Navy to monitor the impact of submarine base activities on local water resources. Estuarine water and sediment data were collected from five sites on the Crooked River, Kings Bay, and Cumberland Sound. Surface-water data were collected from seven streams that discharge from Naval Submarine Base, Kings Bay. Ground-water data were collected from six ground-water monitoring wells completed in the water-table zone of the surficial aquifer at Naval Submarine Base Kings Bay. Samples were analyzed for nutrients, total and dissolved trace metals, total and dissolved organic carbon, oil and grease, total organic halogens, biological and chemical oxygen demand, and total and fecal coliform. Trace metals in ground and surface waters did not exceed U.S. Environmental Protection Agency Drinking Water Standards; and trace metals in surface water also did not exceed U.S. Environmental Protection Agency Surface Water Standards. These trace metals included arsenic, barium, cadmium, chromium, copper, lead, mercury, selenium, silver, tin, and zinc. Barium was detected in relatively high concentrations in ground water (concentrations ranged from 18 to 264 micrograms per liter). Two estuarine water samples exceeded the Georgia Department of Natural Resources, Environmental Protection Division standards for copper (concentrations of 6.2 and 3.0 micrograms per liter).

The effects of phosphorus additions on the sedimentation of contaminants in a uranium mine pit-lake.

PubMed

Dessouki, Tarik C E; Hudson, Jeff J; Neal, Brian R; Bogard, Matthew J

2005-08-01

We investigated the usefulness of phytoplankton for the removal of surface water contaminants. Nine large mesocosms (92.2m(3)) were suspended in the flooded DJX uranium pit at Cluff Lake (Saskatchewan, Canada), and filled with highly contaminated mine water. Each mesocosm was fertilized with a different amount of phosphorus throughout the 35 day experiment to stimulate phytoplankton growth, and to create a range in phosphorus load (g) to examine how contaminants may be affected by different nutrient regimes. Algal growth was rapid in fertilized mesocosms (as demonstrated by chlorophyll a profiles). As phosphorus loads increased there were significant declines (p<0.05) in the surface water concentrations of As, Co, Cu, Mn, Ni, and Zn. This decline was near significant for uranium (p=0.065). The surface water concentrations of Ra-226, Mo, and Se showed no relationship to phosphorus load. Contaminant concentrations in sediment traps suspended at the bottom of each mesocosm generally showed the opposite trend to that observed in the surface water, with most contaminants (As, Co, Cu, Mn, Ni, Ra-226, U, and Zn) exhibiting a significant positive relationship (p<0.05) with phosphorus load. Selenium and Mo did not respond to nutrient treatments. Our results suggest that phytoremediation has the potential to lower many surface water contaminants through the sedimentation of phytoplankton. Based on our results, we estimate that the Saskatchewan Surface Water Quality Objectives (SSWQO) for DJX pit would be met in approximately 45 weeks for Co, 65 weeks for Ni, 15 weeks for U, and 5 weeks for Zn.

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.

Antibiotics in water and sediments of rivers and coastal area of Zhuhai City, Pearl River estuary, south China.

PubMed

Li, Si; Shi, Wanzi; Li, Huimin; Xu, Nan; Zhang, Ruijie; Chen, Xuejiao; Sun, Weiling; Wen, Donghui; He, Shanliang; Pan, Jianguo; He, Zhidong; Fan, Yingying

2018-09-15

The occurrence, spatiotemporal distribution and ecological risks of 27 antibiotics in water and sediments from rivers and coastal area of Zhuhai, Pearl River estuary, south China were investigated. Higher concentrations of antibiotics were found in river water in dry season than those in wet season (p < 0.01), especially for quinolones (QNs) (6.36-463 ng/L) and aminoglycosides (AGs) (94.9-458 ng/L). In coastal water samples, the concentrations of antibiotics were up to 419 ng/L and 357 ng/L in dry season and wet season, respectively. Higher concentrations of antibiotics in coastal sediment samples were observed in wet season compared with those in dry season (p < 0.01). This may be ascribed to the greater discharge of antibiotics from mariculture and surface sediment flushing in wet season, leading to the accumulation of polluted sediments in the estuary. Redundancy analysis showed that the concentrations of antibiotics in water were correlated with biological/chemical oxygen demand, ammonia nitrogen, and/or total nitrogen (TN). In addition, sediment organic matter (SOC) and TN strongly affected the distribution of antibiotics in sediments. Ecological risk assessment based on risk quotients (RQs) indicated that most antibiotics in water samples posed insignificant risk to fish and green algae, and insignificant to medium risk to daphnid. Copyright © 2018 Elsevier B.V. All rights reserved.

A Buoy for Continuous Monitoring of Suspended Sediment Dynamics

PubMed Central

Mueller, Philip; Thoss, Heiko; Kaempf, Lucas; Güntner, Andreas

2013-01-01

Knowledge of Suspended Sediments Dynamics (SSD) across spatial scales is relevant for several fields of hydrology, such as eco-hydrological processes, the operation of hydrotechnical facilities and research on varved lake sediments as geoarchives. Understanding the connectivity of sediment flux between source areas in a catchment and sink areas in lakes or reservoirs is of primary importance to these fields. Lacustrine sediments may serve as a valuable expansion of instrumental hydrological records for flood frequencies and magnitudes, but depositional processes and detrital layer formation in lakes are not yet fully understood. This study presents a novel buoy system designed to continuously measure suspended sediment concentration and relevant boundary conditions at a high spatial and temporal resolution in surface water bodies. The buoy sensors continuously record turbidity as an indirect measure of suspended sediment concentrations, water temperature and electrical conductivity at up to nine different water depths. Acoustic Doppler current meters and profilers measure current velocities along a vertical profile from the water surface to the lake bottom. Meteorological sensors capture the atmospheric boundary conditions as main drivers of lake dynamics. It is the high spatial resolution of multi-point turbidity measurements, the dual-sensor velocity measurements and the temporally synchronous recording of all sensors along the water column that sets the system apart from existing buoy systems. Buoy data collected during a 4-month field campaign in Lake Mondsee demonstrate the potential and effectiveness of the system in monitoring suspended sediment dynamics. Observations were related to stratification and mixing processes in the lake and increased turbidity close to a catchment outlet during flood events. The rugged buoy design assures continuous operation in terms of stability, energy management and sensor logging throughout the study period. We conclude that the buoy is a suitable tool for continuous monitoring of suspended sediment concentrations and general dynamics in fresh water bodies. PMID:24129017

Recent increases in atmospheric deposition of mercury to North-Central Wisconsin lakes inferred from sediment analyses

USGS Publications Warehouse

Rada, R.G.; Wiener, J.G.; Winfrey, M.R.; Powell, D.E.

1989-01-01

Profiles of total mercury (Hg) concentrations in sediments were examined in 11 lakes in north-central Wisconsin having a broad range of pH (5.1 to 7.8) and alkalinity (-12 to 769 μeq/L). Mercury concentrations were greatest in the top 15 cm of the cores and were much lower in the deeper strata. The Hg content in the most enriched stratum of individual cores ranged from 0.09 to 0.24 μg/g dry weight, whereas concentrations in deep, precolonial strata ranged from 0.04 to 0.07 μg/g. Sediment enrichment factors varied from 0.8 to 2.8 and were not correlated with lake pH. The increase in the Hg content of recent sediments was attributed to increased atmospheric deposition of the metal. Eight of the 11 systems studied were low-alkalinity lakes that presumably received most (≥90%) of their hydrologic input from precipitation falling directly onto the lake surface. Thus, the sedimentary Hg in these lakes seems more likely linked to direct atmospheric deposition onto the lake surfaces than to influxes from the watershed. The data imply that a potentially significant fraction of the high Hg burdens measured in game fish in certain lakes in north-central Wisconsin originated from atmospheric sources.

The changes in trace metal contamination over the last decade in surface sediments of the Pearl River Estuary, South China.

PubMed

Chen, Baowei; Liang, Ximei; Xu, Weihai; Huang, Xiaoping; Li, Xiangdong

2012-11-15

Surface sediments can provide useful information on the recent pollution status of an estuary. One recent field survey was carried out in the Pearl River Estuary (PRE), South China in 2011. The comparisons with previous surveys demonstrated that the concentrations of Ni and Pb in the PRE declined over the last decade, but the concentration of Cu increased in the same time frame. The significant decreases in the concentrations of Ni and Pb were probably due to a reduction of anthropogenic inputs, such as industrial wastewater, into the PRE environment, and the ban imposed on leaded gasoline. Statistical analyses have consistently demonstrated that the process of the sedimentation of fine particles was the dominant factor in controlling the transport and distribution of trace metals in the PRE. The riverine trace metals generally displayed a pattern of diffusion from the northwest to the southeast in the estuary. However, the riparian industrial activities at the east bank of the inner PRE caused significant metal contamination in sediments. In general, effective pollution control measures in the PRD region have decreased the levels of some trace metals in the entire PRE over the last decade with the exception of Cu. Copyright © 2012 Elsevier B.V. All rights reserved.

PCBs in Rain Water, Streams and a Reservoir in a Small Catchment of NW Spain

NASA Astrophysics Data System (ADS)

Delgado-Martín, Jordi; Cereijo-Arango, José Luis; García-Morrondo, David; Juncosa-Rivera, Ricardo; Cillero-Castro, Carmen; Muñoz-Ibáñez, Andrea

2016-04-01

Polychlorinated biphenyls (PCBs) constitute a significant environmental concern due to its persistence, tendency to bio-accumulate, acknowledged toxicity and ubiquity. In the present study, a small water catchment (~100 km2) inclusive of a two-tailed water supply reservoir (Abegondo-Cecebre) has been monitored between 2009 and 2014. Sampling stations include: a) one precipitation gauge used to collect monthly-integrated bulk precipitation (25 samples); b) seven streams (95 samples); c) five surface and one bottom points within the reservoir (104 samples); d) five points for sediment sampling in two surveys (spring and summer; 10 samples). All the water samples as well as the leachates of sediment washing have been analyzed for their concentration in 6 marker PCB (congeners 28, 52, 101, 138, 153 and 180) and 12 dioxin-like PCB (congeners 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169 and 189) compounds. The average concentration of PCBtot in the bulk precipitation during the sampling period is ~406 pg/L although a very significant decrease has occurred since the end of 2011 (~800 pg/L) to the end of 2014 (~60 pg/L). Likewise, the mean concentration of PCBtot in the stream water samples is 174 pg/L and a similar reduction in the concentration of PCBtot is also acknowledged for the same period of time (~250 pg/L before the end of 2011 and ~30 pg/L after then). Reservoir surface water has a PCBtot concentration of ~234 pg/L which, according to its sampling time (2010-2011) is consistent with the measured stream waters. However, deep reservoir water reveals an average concentration which is higher than the corresponding top water (~330 pg/L) but significantly smaller than the water-leached sediments (~860 pg/L). The available data suggest that up to a 30% of PCBs associated with precipitation becomes sequestered by the soil/sediment system while no significant change takes place during the transfer of water from the stream to the reservoir system, at least in surface. However, deep reservoir water is enriched in PCBs what is likely due to exchange reactions with the already enriched reservoir sediments. Significant differences are also observed between the PCBtot concentrations of the sediment samples taken in spring (lower) and summer (higher) as well as in connection with the different organic carbon and metal content present in the two tails of the reservoir.

Comparison of vapor concentrations of volatile organic compounds with ground-water concentrations of selected contaminants in sediments beneath the Sudbury River, Ashland, Massachusetts, 2000

USGS Publications Warehouse

Campbell, J.P.; Lyford, F.P.; Willey, Richard E.

2002-01-01

A mixed plume of contaminants in ground water, including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and metals, near the former Nyanza property in Ashland, Massachusetts, discharges to the Sudbury River upstream and downstream of Mill Pond and a former mill raceway. Polyethylene-membrane vapor-diffusion (PVD) samplers were installed in river-bottom sediments to determine if PVD samplers provide an alternative to ground-water sampling from well points for identifying areas of detectable concentrations of contaminants in sediment pore water near the ground-water and surface-water interface. In August and September 2000, the PVD samplers were installed near well points at depths of 8 to 12 inches in both fine and coarse sediments, whereas the well points were installed at depths of 1 to 5 feet in coarse sediments only. Comparison between vapor and water samples at 29 locations upstream from Mill Pond show that VOC vapor concentrations from PVD samplers in coarse river-bottom sediments are more likely to correspond to ground-water concentrations from well points than PVD samplers installed in fine sediments. Significant correlations based on Kendall's Tau were shown between vapor and ground-water concentrations for trichloroethylene and chlorobenzene for PVD samplers installed in coarse sediments where the fine organic layer that separated the two sampling depths was 1 foot or less in thickness. VOC concentrations from vapor samples also were compared to VOC, SVOC, and metals concentrations from ground-water samples at 10 well points installed upstream and downstream from Mill Pond, and in the former mill raceway. Chlorobenzene vapor concentrations correlated significantly with ground-water concentrations for 5 VOCs, 2 SVOCs, and 10 metals. Trichloroethylene vapor concentrations did not correlate with any of the other ground-water constituents analyzed at the 10 well points. Chlorobenzene detected by use of PVD samplers appears to be a strong indicator of the presence of VOCs, SVOCs, and metals in ground water sampled from well points at this site. Results from PVD samplers indicate that contaminant concentrations in water from well points installed 1 to 5 ft below fine sediments may not reflect concentrations in pore water less than 1 foot below the river bottom. There is insufficient information available to determine if VOC concentrations detected in PVD samplers are useful for identifying detectable aqueous concentrations of SVOCs and metals in sediment pore water at this site. Samples of pore water from a similar depth as PVD samplers are needed for confirmation of this objective.

Influence of sea level rise on iron diagenesis in an east Florida subterranean estuary

USGS Publications Warehouse

Roy, M.; Martin, J.B.; Cherrier, J.; Cable, J.E.; Smith, C.G.

2010-01-01

Subterranean estuary occupies the transition zone between hypoxic fresh groundwater and oxic seawater, and between terrestrial and marine sediment deposits. Consequently, we hypothesize, in a subterranean estuary, biogeochemical reactions of Fe respond to submarine groundwater discharge (SGD) and sea level rise. Porewater and sediment samples were collected across a 30-m wide freshwater discharge zone of the Indian River Lagoon (Florida, USA) subterranean estuary, and at a site 250. m offshore. Porewater Fe concentrations range from 0.5 ??M at the shoreline and 250. m offshore to about 286 ??M at the freshwater-saltwater boundary. Sediment sulfur and porewater sulfide maxima occur in near-surface OC-rich black sediments of marine origin, and dissolved Fe maxima occur in underlying OC-poor orange sediments of terrestrial origin. Freshwater SGD flow rates decrease offshore from around 1 to 0.1. cm/day, while bioirrigation exchange deepens with distance from about 10. cm at the shoreline to about 40. cm at the freshwater-saltwater boundary. DOC concentrations increase from around 75 ??M at the shoreline to as much as 700 ??M at the freshwater-saltwater boundary as a result of labile marine carbon inputs from marine SGD. This labile DOC reduces Fe-oxides, which in conjunction with slow discharge of SGD at the boundary, allows dissolved Fe to accumulate. Upward advection of fresh SGD carries dissolved Fe from the Fe-oxide reduction zone to the sulfate reduction zone, where dissolved Fe precipitates as Fe-sulfides. Saturation models of Fe-sulfides indicate some fractions of these Fe-sulfides get dissolved near the sediment-water interface, where bioirrigation exchanges oxic surface water. The estimated dissolved Fe flux is approximately 0.84 ??M Fe/day per meter of shoreline to lagoon surface waters. Accelerated sea level rise predictions are thus likely to increase the Fe flux to surface waters and local primary productivity, particularly along coastlines where groundwater discharges through sediments. ?? 2010 Elsevier Ltd.

Nitrate removal in deep sediments of a nitrogen-rich river network: A test of a conceptual model

USGS Publications Warehouse

Stelzer, Robert S.; Bartsch, Lynn

2012-01-01

Many estimates of nitrogen removal in streams and watersheds do not include or account for nitrate removal in deep sediments, particularly in gaining streams. We developed and tested a conceptual model for nitrate removal in deep sediments in a nitrogen-rich river network. The model predicts that oxic, nitrate-rich groundwater will become depleted in nitrate as groundwater upwelling through sediments encounters a zone that contains buried particulate organic carbon, which promotes redox conditions favorable for nitrate removal. We tested the model at eight sites in upwelling reaches of lotic ecosystems in the Waupaca River Watershed that varied by three orders of magnitude in groundwater nitrate concentration. We measured denitrification potential in sediment core sections to 30 cm and developed vertical nitrate profiles to a depth of about 1 m with peepers and piezometer nests. Denitrification potential was higher, on average, in shallower core sections. However, core sections deeper than 5 cm accounted for 70%, on average, of the depth-integrated denitrification potential. Denitrification potential increased linearly with groundwater nitrate concentration up to 2 mg NO3-N/L but the relationship broke down at higher concentrations (> 5 mg NO3-N/L), a pattern that suggests nitrate saturation. At most sites groundwater nitrate declined from high concentrations at depth to much lower concentrations prior to discharge into the surface water. The profiles suggested that nitrate removal occurred at sediment depths between 20 and 40 cm. Dissolved oxygen concentrations were much higher in deep sediments than in pore water at 5 cm sediment depth at most locations. The substantial denitrification potential in deep sediments coupled with the declines in nitrate and dissolved oxygen concentrations in upwelling groundwater suggest that our conceptual model for nitrate removal in deep sediments is applicable to this river network. Our results suggest that nitrate removal rates can be high in deep sediments of upwelling stream reaches, which may have implications for efforts to understand and quantify nitrogen transport and removal at larger scales.

The distribution of triclosan and methyl-triclosan in marine sediments of Barker Inlet, South Australia.

PubMed

Fernandes, Milena; Shareef, Ali; Kookana, Rai; Gaylard, Sam; Hoare, Sonja; Kildea, Tim

2011-04-01

In this work, we investigated the transport and burial of triclosan and its methylated derivative, in surface sediments near the mouth of Barker Inlet in South Australia. The most likely source of this commonly used bactericide to the area is a wastewater outfall discharging at the confluence of the inlet with marine waters. Triclosan was detected in all samples, at concentrations (5-27 μg kg(-1)) comparable to values found in other surface sediments under the influence of marine wastewater outfalls. Its dispersal was closely associated with fine and organic-rich fractions of the sediments. Methyl-triclosan was detected in approximately half of the samples at concentrations <11 μg kg(-1). The occurrence of this compound was linked to both wastewater discharges and biological methylation of the parent compound. Wastewater-borne methyl-triclosan had a smaller spatial footprint than triclosan and was mostly deposited in close proximity to the outfall. In situ methylation of triclosan likely occurs at deeper depositional sites, whereas the absence of methyl-triclosan from shallower sediments was potentially explained by photodegradation of the parent compound. Based on partition equilibrium, a concentration of triclosan in the order of 1 μg L(-1) was estimated in sediment porewaters, a value lower than the threshold reported for harmful effects to occur in the couple of species of marine phytoplankton investigated to date. Methyl-triclosan presents a greater potential for bioaccumulation than triclosan, but the implications of its occurrence to aquatic ecosystem health are difficult to predict given the lack of ecotoxicological data in the current literature.

Distribution of Heavy Metals in Surface Sediments of the Bay of Bengal Coast

PubMed Central

Hasan, M. R.; Khan, M.; Aktar, S.; Fatema, K.

2017-01-01

The concentrations of major (Si, Al, Ca, Fe, and K) and minor (Cd, Mn, Ni, Pb, U, Zn, Co, Cr, As, Cu, Rb, Sr, and Zr,) elements in the surficial sediments were studied in an attempt to establish their concentration in the Bengal coast. It was revealed that the majority of the trace elements have been introduced into the Bengal marine from the riverine inflows that are also affected by the impact of industrial, ship breaking yard, gas production plant, and urban wastes. The concentration of heavy metals was measured using Atomic Absorption Spectroscopy and Energy Dispersive X-ray fluorescence instruments. The highest concentrations for several trace elements were thus recorded which generally decrease with distance from the coast. It was observed that the heavy metal concentrations in the sediments generally met the criteria of international marine sediment quality. However, both the contamination factor and pollution load index values suggested the elevation of some metals' concentrations in the region. Constant monitoring of the Bengal coast water quality needs to be recorded with a view to minimizing the risk of health of the population and the detrimental impacts on the aquatic ecosystem. PMID:28255298

Coastal surface sediment quality assessment in Leizhou Peninsula (South China Sea) based on SEM-AVS analysis.

PubMed

Li, Feng; Lin, Jin-qin; Liang, Yan-yan; Gan, Hua-yang; Zeng, Xiang-yun; Duan, Zhi-peng; Liang, Kai; Liu, Xing; Huo, Zhen-hai; Wu, Chang-hua

2014-07-15

Surface sediments from the coastal area of the Leizhou Peninsula in the South China Sea were collected and analyzed and the potential ecological risks in the area were assessed based on acid-volatile sulfide (AVS) model. The AVS levels are between 0.109 and 55.6 μmol g(-1), with the average at 4.45 μmol g(-1). The high AVS-concentration zones include the aquaculture areas of Liusha Bay and the densely populated areas of Zhanjiang Bay. The simultaneously extracted metals (SEM) range from 0.026 μmol g(-1) to 8.61 μmol g(-1), with the average at 0.843 μmol g(-1). Most of high SEM-concentration stations were located in ports or aquaculture zones. Most of the coastal surface sediments of the Leizhou Peninsula (90%) had no adverse biological effects according to the criterion proposed by USEPA (2005); while adverse effects were uncertain in some stations (8%); even in 2 stations (2%) adverse biological effects may be expected. Copyright © 2014 Elsevier Ltd. All rights reserved.

Watershed-Scale Impacts from Surface Water Disposal of Oil and Gas Wastewater in Western Pennsylvania.

PubMed

Burgos, William D; Castillo-Meza, Luis; Tasker, Travis L; Geeza, Thomas J; Drohan, Patrick J; Liu, Xiaofeng; Landis, Joshua D; Blotevogel, Jens; McLaughlin, Molly; Borch, Thomas; Warner, Nathaniel R

2017-08-01

Combining horizontal drilling with high volume hydraulic fracturing has increased extraction of hydrocarbons from low-permeability oil and gas (O&G) formations across the United States; accompanied by increased wastewater production. Surface water discharges of O&G wastewater by centralized waste treatment (CWT) plants pose risks to aquatic and human health. We evaluated the impact of surface water disposal of O&G wastewater from CWT plants upstream of the Conemaugh River Lake (dam controlled reservoir) in western Pennsylvania. Regulatory compliance data were collected to calculate annual contaminant loads (Ba, Cl, total dissolved solids (TDS)) to document historical industrial activity. In this study, two CWT plants 10 and 19 km upstream of a reservoir left geochemical signatures in sediments and porewaters corresponding to peak industrial activity that occurred 5 to 10 years earlier. Sediment cores were sectioned for the collection of paired samples of sediment and porewater, and analyzed for analytes to identify unconventional O&G wastewater disposal. Sediment layers corresponding to the years of maximum O&G wastewater disposal contained higher concentrations of salts, alkaline earth metals, and organic chemicals. Isotopic ratios of 226 Ra /228 Ra and 87 Sr /86 Sr identified that peak concentrations of Ra and Sr were likely sourced from wastewaters that originated from the Marcellus Shale formation.

Influence of contaminant burial depth on the bioaccumulation of PCBs and PBDEs by two benthic invertebrates (Monoporeia affinis and Marenzelleria spp.).

PubMed

Josefsson, Sarah; Leonardsson, Kjell; Gunnarsson, Jonas S; Wiberg, Karin

2011-11-01

The bioaccumulation of buried polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) added to specific depths in sediment (2.0-2.5, 5.0-5.5 and 10.0-10.5cm) was studied in two infaunal species with similar feeding habits (surface deposit-feeders) but different bioturbation modes. The deep-burrowing polychaetes Marenzelleria spp. (Mz) displayed up to 36 times higher tissue concentrations of buried (spiked) contaminants than the surface-dwelling biodiffusing amphipod Monoporeia affinis. The differences in bioaccumulation were most pronounced for less hydrophobic contaminants due to the bioirrigating activity of Mz. Contaminants buried at shallow depths displayed higher accumulation than more deeply buried contaminants. In contrast, the bioaccumulation of unspiked (native) contaminants with a uniform vertical distribution in the sediment was similar between the species. For Mz, the BSAFs increased with increased K(OW) for the uniformly distributed contaminants, but decreased for the buried contaminants, which indicates that the dominant uptake routes of the buried contaminants can differ from the uniformly distributed contaminants. The surface sediment concentration of buried contaminants increased in Mz treatments, showing that Mz bioturbation can remobilize historically buried contaminants to the biologically active surface layer and increase the exposure for surface-dwelling species. Copyright © 2011 Elsevier Ltd. All rights reserved.

Mobilisation of traffic-derived trace metals from road corridors into coastal stream and estuarine sediments, Cairns, northern Australia

NASA Astrophysics Data System (ADS)

Pratt, C.; Lottermoser, B. G.

2007-04-01

This investigation revealed the presence of traffic-derived metals within road, stream and estuarine sediments collected from a coastal catchment, northern Australia. Studied road sediments displayed variable total metal concentrations (median Cd, Cu, Pb, Pd, Pt, Ni and Zn values: 0.19, 42.6, 67.5, 0.064, 0.104, 36.7 and 698 mg/kg, respectively). The distinctly elevated Zn values are due to abundant tyre rubber shreds (as verified by SEM-EDS and correlation analysis). By comparison to the road sediments, background stream sediments taken upstream from roads have relatively low median Pb, Pd, Pt and Zn concentrations (7.3 mg/kg Pb, 0.01 mg/kg Pd, 0.012 mg/kg Pt, 62 mg/kg Zn). Stream and estuarine sediment samples collected below roads have median values of 21.8 mg/kg Pb, 0.014 mg/kg Pd, 0.021 mg/kg Pt and 71 mg/kg Zn, and exhibit 207Pb/206Pb and 208Pb/206Pb ratios that appear on a mixing line between the isotopically distinct background stream sediments and the road sediments. Thus, mobilisation of dusts and sediments from road surfaces has resulted in relatively elevated Pb, Pd, Pt and Zn concentrations and non-radiogenic Pb isotope ratios in local coastal stream and estuarine sediments. The investigation demonstrates that traffic-derived metals enter coastal stream and estuary sediments at the fringe of the Great Barrier Reef lagoon.

Geospatial risk assessment and trace element concentration in reef associated sediments, northern part of Gulf of Mannar biosphere reserve, Southeast Coast of India.

PubMed

Krishnakumar, S; Ramasamy, S; Simon Peter, T; Godson, Prince S; Chandrasekar, N; Magesh, N S

2017-12-15

Fifty two surface sediments were collected from the northern part of the Gulf of Mannar biosphere reserve to assess the geospatial risk of sediments. We found that distribution of organic matter and CaCO 3 distributions were locally controlled by the mangrove litters and fragmented coral debris. In addition, Fe and Mn concentrations in the marine sediments were probably supplied through the riverine input and natural processes. The Geo-accumulation of elements fall under the uncontaminated category except Pb. Lead show a wide range of contamination from uncontaminated-moderately contaminated to extremely contaminated category. The sediment toxicity level of the elements revealed that the majority of the sediments fall under moderately to highly polluted sediments (23.07-28.84%). The grades of potential ecological risk suggest that predominant sediments fall under low to moderate risk category (55.7-32.7%). The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low to moderate risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrence and levels of glyphosate and AMPA in shallow lakes from the Pampean and Patagonian regions of Argentina.

PubMed

Castro Berman, M; Marino, D J G; Quiroga, María Victoria; Zagarese, Horacio

2018-06-01

Glyphosate (N-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide used to kill weeds that compete with commercial crops. In Argentina, the use of glyphosate-based herbicides increased dramatically (up to ∼200,000 tons on 2012) since the introduction of glyphosate-resistant crops, such as transgenic soy and resistant corn, and the adoption of non-till practices in the 1990's. Sallow lakes within the Pampa region may be potentially impacted by continuous herbicide usage. We surveyed 52 shallow lakes from the Pampa region (Buenos Aires Province, Argentina) to assess the occurrence and concentrations of glyphosate and its main degradation product (AMPA). For comparison, we also sampled 24 shallow lakes from an area with no agricultural use of glyphosate (Northern Patagonia). Glyphosate and AMPA were analyzed by UPLC-MS/MS ESI (±) in lake water, suspended particulate matter (SPM), and sediment samples. Within the Pampa region, glyphosate residues were detected in >40% of samples. Glyphosate residues were detected more frequently in sediment and surface water than in SPM samples. The mean (maximum) concentrations of glyphosate were 2.11 (4.52) μg l -1 for surface water; 0.10 (0.13) μg l -1 for SPM and 10.47 (20.34) μg kg -1 for sediment samples, respectively. Whereas, mean (maximum) concentrations of AMPA were 0.84 and (0.90) μg l -1 for surface water; 0.07 (0.07) μg l -1 for SPM; and 22.53 (32.89) μg kg -1 for sediment samples. The herbicide was not detected in samples from the Patagonian region. To our knowledge, this is the first study reporting the occurrence and concentrations of the herbicide in freshwater lakes of Argentina. Copyright © 2018 Elsevier Ltd. All rights reserved.

In Situ Mo Isotope Fractionation in the Water Columns of Euxinic Basins

NASA Astrophysics Data System (ADS)

Neubert, N.; Nägler, T. F.; Böttcher, M. E.

2007-12-01

The present study investigates for the first time the overall process of molybdenum (Mo) scavenging in modern euxinic systems using Mo concentration and stable isotope measurements. We analyzed samples from three different sites: The Black Sea, the largest permanently euxinic basin, and two anoxic basins of the Baltic Sea, the Gotland Deep and the Landsort Deep which have maximum water depths of 247 m and 459 m, respectively. Water column profiles, as well as surface sediment samples, were recovered from different water depths. Mo is a redox-sensitive trace metal which is soluble as the molybdate oxyanion in oxic seawater with a residence time of about 800 ka. The isotope signature of Mo is a relatively new proxy used to reconstruct the paleo-redox conditions of the Earth's atmosphere and the oceanic system. The Mo isotope composition in seawater is homogeneous (Siebert et al. 2003). Scavenging of Mo under euxinic conditions is related to the amount of free sulfide in the water column. Near total removal of Mo from the water column is reached at aquatic sulfide concentration of c. 11 μM (Erickson and Helz 2000). In the Black Sea this corresponds to a water depth of about 400 m. Sediment samples of the Black Sea from more then 400 m water depth show seawater isotopic composition, in line with the assumption of bulk Mo removal. However, shallower sediments deposited under lower aquatic sulfide concentrations show significant Mo isotope fractionation. The Baltic Sea oceanographic conditions, including temporary bottom water oxygenation due to sporadic North Sea water inflows, are more complex than in the Black Sea. The aquatic sulfide concentration in the water column is less than 5 μM in the two anoxic troughs. As expected from this lower sulfidity, the surface sediments show Mo fractionation similar to the oxic to slightly euxinic sediments of the Black Sea. Our new results on the Mo isotopic composition in euxinic water columns clearly indicate in situ fractionation of Mo isotopes. All euxinic water samples from the three settings are shifted towards heavier Mo isotope signatures, thus complementing the lighter values in the surface sediments (Nagler et al. 2005).

Cross-Validation of Suspended Sediment Concentrations Derived from Satellite Imagery and Numerical Modeling of the 1997 New Year's Flood on the Feather River, CA

NASA Astrophysics Data System (ADS)

Kilham, N. E.

2009-12-01

Image analysis was applied to assess suspended sediment concentrations (SSC) predicted by a numerical model of 2D hydraulics and sediment transport (Telemac-2D), coupled to a solver for the advection-diffusion equation (SISYPHE) and representing 18 days of flooding over 70 kilometers of the lower Feather-Yuba Rivers. Sisyphe treats the suspended load as a tracer, removed from the flow if the bed shear velocity, u* is lower than an empirically derived threshold (ud* = 7.8E-3 m s-1). Agreement between model (D50 = 0.03 mm) and image-derived SSC (mg L-1) suggests that image interpretation could prove to be a viable approach for verifying spatially-distributed models of floodplain sediment transport if imagery is acquired for a particular flood and at a sufficient spatial and radiometric resolution. However, remotely derived SSC represents the integrated concentration of suspended sediment at the water surface. Hence, comparing SSC magnitudes derived from imagery and numerical modeling requires that a relationship is first established between the total suspended load and the portion of this load suspended within the optical range of the sensor (e.g., Aalto, 1995). Using the optical depth (0.5 m) determined from radiative transfer modeling, surface SSC measured from a 1/14/97 Landsat TM5 image (30 m) were converted to depth-integrated SSC with the Rouse (1937) equation. Surface concentrations were derived using a look-up table for the sensor to convert endmember fractions obtained from a spectral mixture analysis of the image. A two-endmember model (2.0 and 203 mg L-1) was used, with synthetic endmembers derived from optical and radiative transfer modeling and inversion of field spectra collected from the Sacramento and Feather Rivers and matched to measured SSC values. Remotely sensed SSC patterns were then compared to the Telemac results for the same day and time. Modeled concentrations are a function of both the rating curve boundary conditions, and the transport and deposition calculations. At each of three upstream channel boundaries, hourly SSC was derived from instantaneous discharge and SSC records at USGS gages for winter months (December-April) following dam closure on the Feather, Yuba, and Bear Rivers (r2 = 0.61; r2 = 0.81; r2 = 0.55). Model channel concentrations declined downstream from about 90 mg L-1 to 40 mg L-1 as sediment input was depleted through decanting of river water overbank, advection through floodplain channels, and deposition onto the floodplain. Similar downstream declines in the image values suggest that bed and bank erosion downstream of the major gages did not contribute much new sediment two weeks following the flood peak. Model predicted concentrations agree with image derived concentrations to within 10 mg L-1, although the model predicts a more rapid drawdown of floodplain flow than is apparent from the image. Aalto, R., 1995. Discordance between suspended sediment diffusion theory and observed sediment concentration profiles in rivers. M.S., University of Washington, Seattle, WA. Rouse, H.R., 1937. Modern conceptions of the mechanics of turbulence. Transactions, American Society of Civil Engineers, 102: 463-543.

The influence of sediment transport rate on the development of structure in gravel bed rivers

NASA Astrophysics Data System (ADS)

Ockelford, Annie; Rice, Steve; Powell, Mark; Reid, Ian; Nguyen, Thao; Tate, Nick; Wood, Jo

2013-04-01

Although adjustments of surface grain size are known to be strongly influenced by sediment transport rate little work has systematically explored how different transport rates can affect the development of surface structure in gravel bed rivers. Specifically, it has been well established that the transport of mixed sized sediments leads to the development of a coarser surface or armour layer which occurs over larger areas of the gravel bed. Armour layer development is known to moderate overall sediment transport rate as well as being extremely sensitive to changes in applied shear stress. However, during this armouring process a bed is created where, smaller gain scale changes, to the bed surface are also apparent such as the development of pebble clusters and imbricate structures. Although these smaller scale changes affect the overall surface grain size distribution very little their presence has the ability to significantly increase the surface stability and hence alter overall sediment transport rates. Consequently, the interplay between the moderation of transport rate as a function of surface coarsening at a larger scale and moderation of transport rate as a function of the development of structure on the bed surface at the smaller scale is complicated and warrants further investigation. During experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to 3 different levels of constant discharge that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Sediment was re-circulated during the experiments surface grain size distribution bed load and fractional transport rates were measured at a high temporal resolution such that the time evolution of the beds could be fully described. Discussion concentrates on analysing the effects of the evolving bed condition sediment transport rate (capacity) and transported grain size (competence). The outcome of this research is pertinent to developing new methods of linking the development of bed surface organisation with near bed flow characteristics and bed load transport in gravel bed rivers. Keywords: Graded, Sediment, Structure

Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

USGS Publications Warehouse

Winger, P.V.; Lasier, P.J.; Jackson, B.P.

1995-01-01

Designation of Okefenokee National Wildlife Refuge (Georgia) as a Class I Air Quality Area affords mandatory protection of the airshed through permit-review processes for planned developments. Rainfall is the major source of water to the swamp, and potential impacts from developments in the airshed are high. To meet management needs for baseline information, chemical contributions from atmospheric deposition and partitioning of anions and cations in various matrices of the swamp, with emphasis on mercury and lead, were determined during this study. Chemistry of rainfall was measured on an event basis from one site and quarterly on surface water, pore water, floc, and sediment from four locations. A sediment core collected from the Refuge interior was sectioned, aged, and analyzed for mercury. Rainfall was acidic (pH 4.7-4.9), with average total and methyl mercury concentrations of 9 ng/L and 0.1 ng/L, respectively. Surface waters were acidic (pH 3.8-4.1), dilute (specific conductance 35-60 pS), and highly organic (dissolved organic carbon 35-50 mg/L). Total mercury was 1-3.5 ng/L in surface and pore water, and methyl mercury was 0.02-0.20 ng/L. Total mercury in sediments and floc was 100-200 ng/g dry weight, and methyl mercury was 4-16 ng/g. Lead was 0-1.7 pg/L in rainfall, not detectable in surface water, 3.4-5.4 pg/L in pore water, and 3.9-4.9 mg/kg in floc and sediment. Historical patterns of mercury deposition showed an increase in total mercury from pre-1800 concentrations of 250 ng/g to 500 ng/g in 1950, with concentrations declining thereafter to present.

Comparison of modern pollen distribution between the northern and southern parts of the South China Sea.

PubMed

Luo, Chuanxiu; Chen, Muhong; Xiang, Rong; Liu, Jianguo; Zhang, Lanlan; Lu, Jun

2015-04-01

The authors conducted a palynological analysis based on different number of air pollen samples for the northern and southern parts of the South China Sea, respectively, in order to give a reference to reconstruct the paleoclimate of the area. (1) Fifteen air pollen samples were collected from the northern part of the South China Sea from August to September 2011, and 13 air pollen samples were collected from the southern part of the South China Sea in December 2011. The pollen types were more abundant in the north than in the south. The total pollen number and concentration in the north was 10 times more than that in the south, which may be because of the sampling season. Airborne pollen types and concentrations have a close relationship with wind direction and distance from the sampling point to the continent. (2) Seventy-four samples were collected from surface sediments in the northern part of the South China Sea in the autumn. Thirty-three samples were collected from surface sediments in the southern part of the South China Sea in the winter. Pollen concentrations in the north were nearly 10 times higher than that in the south. This is because trilete spores are transported by rivers from Hainan Island to the sea and also by the summer monsoon-forced marine current. (3) Ten air pollen samples and 10 surface sediments samples were selected for comparison. The pollen and spores in the air were mainly herbaceous and woody pollen, excluding fern spores, having seasonal pollen characteristics. Pollen in the surface sediments were mainly trilete, Pinus, and herbaceous, and may also show a combination of annual pollen characteristics.

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

PubMed

Poerschmann, Juergen; Koschorreck, Matthias; Górecki, Tadeusz

2012-01-01

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

Response of Benthic Foraminiferal Size to Oxygen Concentration in Antarctic Sediment Cores

NASA Astrophysics Data System (ADS)

Guo, D.; Keating-Bitonti, C.; Payne, J.

2014-12-01

Oxygen availability is important for biological reactions and the demand of oxygen is determined by the size of the organism. Few marine organisms can tolerate low oxygen conditions, but benthic foraminifera, a group of amoeboid protists that are highly sensitive to environmental factors, are known to live in these conditions. Benthic foraminifera may be able to live in oxygen stressed environments by changing the size and shape of their test. Low oxygen concentrations should favor smaller, thinner-shelled, flattened test morphologies. We hypothesize that the volume-to-surface area ratio of benthic foraminifera will decrease with decreasing dissolved oxygen concentrations. To test this hypothesis, we picked two calcareous species (Epistominella exigua and Cassulinoides porrectus) and one agglutinated species (Portatrochammina antarctica) from three sediment cores collected from Explorer's Cove, Antarctica. Starting at the sediment-water interface, each core spans approximately 5-8 cm of depth. Profiles of dissolved oxygen concentrations were measured at the time of collection. At specific depths within the cores, we measured the three dimensions of picked foraminiferal tests using NIS-Elements. We calculated the volume and surface area of the tests assuming the shape of the foraminifers was an ellipsoid. The size trends of E. exigua confirm our hypothesis that the test volume-to-surface area ratios correlate positively with dissolved oxygen concentrations (p-value < 0.001). However, the size trends of the other species refute our hypothesis: P. antarctica shows no correlation and C. porrectus shows a negative correlation (p-value < 0.001) to dissolved oxygen concentrations. Thus, our results show that the change in size in response to variations in dissolved oxygen concentrations is species dependent. Moreover, we find that calcareous species are more sensitive to oxygen fluctuations than agglutinated species.

Polycyclic Aromatic Hydrocarbons in Sediments and Bivalves on the Pacific Coast of Japan: Influence of Tsunami and Fire

PubMed Central

Onozato, Mayu; Nishigaki, Atsuko; Okoshi, Kenji

2016-01-01

Surface sediments and at least one edible bivalve species (Ruditapes philippinarum, Mytilus galloprovincialis, and Crassostrea gigas) were collected from each of seven intertidal sites in Japan in 2013. The sites had experienced varying levels of tsunami and fire disturbance following the major earthquake of 2011. Eight polycyclic aromatic hydrocarbons (PAHs) were identified and analyzed by gas chromatography–mass spectrometry. Total sediment PAH concentration (CT), the sum of the average concentrations of the eight PAHs, was 21–1447 μg kg-1-dry. Relative to the average level of one type of PAH in sediments collected around Japan in 2002 (benzo[a]pyrene = 21 μg kg-1-dry), five of the seven sites showed concentrations significantly lower than this average in 2013. The CTs for the three bivalves (134–450 μg kg-1-dry) were within the range of the previous reports (2.2–5335 μg kg-1-dry). The data suggest that the natural disaster did not increase PAH concentrations or affect the distribution within sediment or bivalves in Tohoku district. Although PAH concentrations at the sites pose no risk to human health, the findings highlight that the observed PAH levels derive from pre- rather than post-quake processes. PMID:27232189

Biogeochemical and microbiological characteristic of the pockmark sediments, the Gdansk Deep, The Baltic Sea

NASA Astrophysics Data System (ADS)

Pimenov, Nikolay; Kanapatskiy, Timur; Sivkov, Vadim; Toshchakov, Stepan; Korzhenkov, Aleksei; Ulyanova, Marina

2016-04-01

Comparison of the biogeochemical and microbial features was done for the gas-bearing and background sediments as well as near-bottom water of the Gdansk Deep, The Baltic Sea. Data were received in October, 2015 during 64th cruise of the R/V Akademik Mstislav Keldysh. Gas-bearing sediments were sampled within the known pockmark (Gas-Point, depth 94 m). Background sediments area (BG-Point, depth 86 m) was located several km off the pockmark area. The sulphate concentration in the pore water of the surface sediment layer (0-5 cm) of Gas-Point was 9,7 mmol/l, and sharply decreased with depth (did not exceed 1 mmol/l deeper than 50 cm). The sulphate concentration decrease at BG-Point also took place but was not so considerable. Sulphate concentration decrease is typical for the organic rich sediments of the high productive areas, both as for the methane seep areas. Fast sulphate depletion occurs due to active processes of its microbial reduction by consortium of the sulphate-reduction bacteria, which may use low-molecular organic compounds or hydrogen, formed at the different stages of the organic matter destruction; as well as within the process of the anaerobic methane oxidation by consortium of the methane-trophic archaea and sulphate-reduction bacteria. Together with sulphate concentration decrease the methane content increase, typical for the marine sediments, occurred. At the Gas-Point the methane concentration varied within 10 μmol/dm3 in the surface layer till its maximum at sediment horizon of 65 cm (5 mmol/dm3), and decreased to 1.5 mmol/dm3 at depth of 300 cm. The BG-Point maximum values were defined at sediment horizon 6 cm (2,6 μmol/dm3). Methane sulfate transition zone at the Gas-Point sediments was at 25-35 cm depth; whereas it was not defined at the BG-Point mud. High methane concentration in the gas-bearing sediments results in the formation of the methane seep from the sediments to the near-bottom water. So the Gas-Point near-bottom waters were characterized by high methane concentration (0.36-0.50 μmol/l) even in the water 2-5 m above the bottom (0.08-0.28 μmol/l), whereas at the BG-Point sediments methane concentration in the near-bottom water was 0.06-0.08 μmol/l. In order to get insights into the structure of microbial community responsible for realization of these redox processes we performed microbial community profiling using high-throughput 16S amplicon sequencing. DNA was extracted from sediments and water column in pockmark and background zones. NGS libraries were prepared with fusion primers for V4 variable region (Caporaso et al., 2012) and sequenced on the MiSeq system. Results well correlated with new data obtained from the analysis of the intensity of microbial processes. The study was financed by the Russian Scientific Fund (grant 14-37-00047). Caporaso JG, Lauber CL, Walters WA, Berg-Lyons D, Huntley J, Fierer N, Owens SM, Betley J, Fraser L, Bauer M, Gormley N, Gilbert JA, Smith G, Knight R. Ultra-high-throughput microbial community analysis on the Illumina HiSeq and MiSeq platforms. ISME J. 2012 Aug;6(8):1621-4

Acid-volatile sulfide and simultaneously extracted metals in surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea: concentrations, spatial distributions and the indication of heavy metal pollution status.

PubMed

Zhuang, Wen; Gao, Xuelu

2013-11-15

Surface sediments were collected from the coastal waters of southwestern Laizhou Bay and the rivers it connects with during summer and autumn 2012. The acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) were measured to assess the sediment quality. The results showed that not all sediments with [SEM]-[AVS]>0 were capable of causing toxicity because the organic carbon is also an important metal-binding phase in sediments. Suppose the sediments had not been disturbed and the criteria of US Environmental Protection Agency had been followed, heavy metals in this area had no adverse biological effects in both seasons except for few riverine samples. The major ingredient of SEM was Zn, whereas the contribution of Cd - the most toxic metal studied - to SEM was <1%. The distributions of AVS and SEM in riverine sediments were more easily affected by anthropogenic activity compared with those in marine sediments. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Tidally Averaged Sediment-Transport Model for San Francisco Bay, California

USGS Publications Warehouse

Lionberger, Megan A.; Schoellhamer, David H.

2009-01-01

A tidally averaged sediment-transport model of San Francisco Bay was incorporated into a tidally averaged salinity box model previously developed and calibrated using salinity, a conservative tracer (Uncles and Peterson, 1995; Knowles, 1996). The Bay is represented in the model by 50 segments composed of two layers: one representing the channel (>5-meter depth) and the other the shallows (0- to 5-meter depth). Calculations are made using a daily time step and simulations can be made on the decadal time scale. The sediment-transport model includes an erosion-deposition algorithm, a bed-sediment algorithm, and sediment boundary conditions. Erosion and deposition of bed sediments are calculated explicitly, and suspended sediment is transported by implicitly solving the advection-dispersion equation. The bed-sediment model simulates the increase in bed strength with depth, owing to consolidation of fine sediments that make up San Francisco Bay mud. The model is calibrated to either net sedimentation calculated from bathymetric-change data or measured suspended-sediment concentration. Specified boundary conditions are the tributary fluxes of suspended sediment and suspended-sediment concentration in the Pacific Ocean. Results of model calibration and validation show that the model simulates the trends in suspended-sediment concentration associated with tidal fluctuations, residual velocity, and wind stress well, although the spring neap tidal suspended-sediment concentration variability was consistently underestimated. Model validation also showed poor simulation of seasonal sediment pulses from the Sacramento-San Joaquin River Delta at Point San Pablo because the pulses enter the Bay over only a few days and the fate of the pulses is determined by intra-tidal deposition and resuspension that are not included in this tidally averaged model. The model was calibrated to net-basin sedimentation to calculate budgets of sediment and sediment-associated contaminants. While simulated net sedimentation in the four basins that comprise San Francisco Bay was correct, the simulations incorrectly eroded shallows while channels deposited because model surface-layer boxes span both shallows and channels, and neglect lateral variability of suspended-sediment concentration. Validation with recent (1983-2005) net sedimentation in South San Francisco Bay was poor, perhaps owing to poorly quantified sediment supply, and to invasive species that altered erosion and deposition processes. This demonstrates that deterministically predicting future sedimentation is difficult in this or any estuary for which boundary conditions are not stationary. The model would best be used as a tool for developing past and present sediment budgets, and for creating scenarios of future sedimentation that are compared to one another rather than considered a deterministic prediction.

Polychlorinated biphenyls (PCBs) in recreational marina sediments of San Diego Bay, southern California.

PubMed

Neira, Carlos; Vales, Melissa; Mendoza, Guillermo; Hoh, Eunha; Levin, Lisa A

2018-01-01

Polychlorinated biphenyl (PCB) concentrations were determined in surface sediments from three recreational marinas in San Diego Bay, California. Total PCB concentrations ranged from 23 to 153, 31-294, and 151-1387ngg -1 for Shelter Island Yacht Basin (SIYB), Harbor Island West (HW) and Harbor Island East (HE), respectively. PCB concentrations were significantly higher in HE and PCB group composition differed relative to HW and SIYB, which were not significantly different from each other in concentration or group composition. In marina sediments there was a predominance (82-85%) of heavier molecular weight PCBs with homologous groups (6CL-7CL) comprising 59% of the total. In HE 75% of the sites exceeded the effect range median (ERM), and toxicity equivalence (TEQ dioxin-like PCBs) values were higher relative to those of HW and SIYB, suggesting a potential ecotoxicological risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

From source to sink: Unravelling the complex in situ cosmogenic 10Be-14C signature in eroding bedrock surfaces and river sediment from the Bolivian Altiplano

NASA Astrophysics Data System (ADS)

Hippe, Kristina; Lupker, Maarten; Gordijn, Tiemen; Ivy-Ochs, Susan; Kober, Florian; Christl, Marcus; Wacker, Lukas; Hajdas, Irka; Wieler, Rainer

2017-04-01

Sediment storage is a critical component of fluvial sedimentary systems. By interrupting transport processes, intermittent sediment storage can effectively decouple source from sink and buffer the transmission of signals of environmental change (e.g., in climate, vegetation, human impact) through the fluvial system. Combined in situ cosmogenic 14C-10Be analysis in fluvial sediment provides a unique method to simultaneously assess sediment transit times (in situ 14C signal) and long-term sediment production rates from bedrock erosion (10Be signal). The key is the much shorter half-life of in situ 14C compared to 10Be which causes a rapid decrease of the in situ 14C concentration when sediment is buried during sediment storage and creates an offset to 10Be. Here, we use the in situ 14C-10Be chronometer to determine changes in surface erosion and estimate absolute rates of sediment transfer in a catchment on the Bolivian Altiplano. Previous research in the study area has found a significant offset in the in situ 14C-10Be inventories from river sediments with much lower in situ 14C concentrations than expected from the 10Be content for steady-state conditions. This offset has been interpreted to reflect sediment storage over the past 11-20 ka [1]. Additional analyses of in situ 14C and 10Be in a dense network of sediment samples from the main channel and tributaries agree with previous data and yield very low in situ 14C concentrations that suggest an increase in storage duration by a few ka with downstream distance. However, analyses of in situ 14C-10Be in hilltop samples from the eroding source area reveal an almost as large offset as in the river sediments. Such complex in situ 14C-10Be inventories in the source area have a severe impact on the quantification of sediment storage times and strongly challenge previous data interpretation. The most straightforward explanation for the in situ 14C-10Be offset at hilltop locations is a change in denudation rate during the Holocene. Using a simple model of a rapid, one-step denudation rate change, a minimum increase by a factor of 30-40 at about 4-6 ka ago is required to approach the measured in situ 14C-10Be concentrations. This corresponds to the Mid-Holocene shift towards wetter climate in the Eastern Andes as proposed from paleolake deposits [2]. Assuming that fluvial sediments inherit a complex 10Be-14C signal from the source area, the estimated duration of total sediment storage reduces to 1-5 ka and is, thus, much shorter than previously assumed. These time spans correlate well with ages of 2-3 ka obtained for fluvial terraces in the study area by radiocarbon and 10Be depth profile dating. Our data allows tracing the spatial pattern of sediment storage and quantify individual storage durations during source-to-sink sediment transfer through the catchment. We further highlight the potential of the in situ 14C-10Be chronometer to determine the magnitude and timing of changes in surface erosion in the past and, thus, to identify transience in eroding landscapes. [1] Hippe et al., 2012 - Geomorphology 179 - pp. 58-70. [2] Rigsby et al., 2005 - J Quaternary Sci 20 - pp. 671-691.

Temporal and spatial trends of total petroleum hydrocarbons and heavy metals in the surface sediment of Caofeidian Sea Area, China from 2011 to 2016

NASA Astrophysics Data System (ADS)

Huang, Wei

2018-05-01

The temporal and spatial distribution of total petroleum hydrocarbons (TPH) and four heavy metals in the surface sediments of Caofeidian Sea Area during 2011–2016 was investigated. The sediment concentration of TPH, Cu, Zn, Pb and Cd were 10.07-186.4 mg/L, 16.5-84.9 mg/L, 11.1-135 mg/L, 6.8-24.6 mg/L, and 0.07-0.199 mg/L, respectively. The pollution level in Caofeidian sea area is lower than those in other area in China. These results reached the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. In addition, TPH at all stations decreased during 2011-2016. The highest values obtained were at stations near the port areas and estuary region.

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

Viklander, M.

Sediments that had accumulated during the winter season, and which were left at the surface when the snow had melted, were studied with regard to physical and chemical characteristics. The investigation was carried out in the city of Luleaa, which is located in northern Sweden. Sediment samples were collected in the city center and in a housing area at streets with different traffic loads. The results showed that the amount of the sediments at a street surface was evidently affected by the presence of a sidewalk. The street with a sidewalk accumulated much more sediment than the street without amore » sidewalk. Both of these streets had approximately the same traffic load. The sidewalk also affected the particle size distribution. The content of heavy metals in the sediments varied with the traffic load and the area type. The highest concentration of cadmium, lead, and zinc was found in the street with the highest traffic load.« less

The effect of Hurricane Lili on the distribution of organic matter along the inner Louisiana shelf (Gulf of Mexico, USA)

NASA Astrophysics Data System (ADS)

Goñi, Miguel A.; Gordon, Elizabeth S.; Monacci, Natalie M.; Clinton, Rebecca; Gisewhite, Rachel; Allison, Mead A.; Kineke, Gail

2006-11-01

On October 3, 2002 Hurricane Lili made landfall on a previously studied region of the inner Louisiana shelf as a Category 2 storm with winds over 160 km/h. A week after the hurricane, major impacts of the storm were not evident in the water column except for the lower than expected inshore salinities (˜12 psu) for this time of year, which was characterized by low river discharge. Turbidity profiles were typical of those measured during previous investigations with suspended sediment concentrations >75 mg/L at inshore stations and <50 mg/L in surface waters and offshore. The implication is that the sediments resuspended during the hurricane settled soon after the storm passage. Water column particulate organic carbon (POC) concentrations ranged from 0.1 to over 2.0 mg/L, with the highest concentrations measured near the seabed and in the inshore portions of the study area. Suspended particles were characterized by low organic matter content (%POC of 0.5-2 wt%), low chlorophyll:POC ratios (Chl:POC<4 mg/g) and moderately elevated POC:particulate nitrogen ratios (POC:PN of 10-14 mol/mol), all suggesting their source was locally resuspended seabed sediment rather than from algal biomass or land-derived vascular plant detritus. Post hurricane sediment deposition throughout the study area resulted in a storm layer that ranged from <0.5 to 20 cm in thickness. In most locations sediment accumulation ranged from 3 to 10 cm. The storm deposits were generally composed of silty clays with a coarser, somewhat sandy 1-2 cm basal layer. Surface sediments from the storm layer were characterized by relatively high mineral surface areas (SA of 30-50 m 2/g) and elevated OC contents (%OC of 1.0-2.0%). The dispersal of fine sediments following the hurricane resulted in marked changes in the SA and %OC values of surface sediments from offshore locations, which prior to the storm contained coarser, organic-poor particles (SA of 5-15 m 2/g and %OC of 0.2-0.6%). The OC:SA and OC:N ratios of storm layer sediments ranged from 0.4 to 0.6 mg OC/m 2 and from 10 to 12 mol/mol, respectively, and were comparable to those measured in surface sediments prior to the hurricane. Such similarities in the composition of the organic matter reinforce the idea that the source of the storm deposits was the finer fraction of resuspended seabed sediments, with little evidence for inputs from local land-derived sources or autochthonous algal production. Overall, the magnitude of sediment and organic matter deposition on the seabed after the storm greatly exceeded the annual inputs from the Atchafalaya River and coastal primary production. The combined effects of hurricane-driven erosion and post-storm deposition represent a major perturbation to the benthic community of the region, which is already subject to these types of disturbances due to the combined effects of peaks in river discharge and the passage of storm fronts.

Modern processes of sediment formation in Lake Towuti, Indonesia, as derived from the composition of lake surface sediments

NASA Astrophysics Data System (ADS)

Hasberg, Ascelina; Melles, Martin; Morlock, Marina; Vogel, Hendrik; Russel, James M.; Bijaksana, Satria

2016-04-01

In summer 2015, a drilling operation funded by the International Continental Scientific Drilling Program (ICDP) was conducted at Lake Towuti (2.75°S, 121.5°E), the largest tectonically formed lake (surface area: 561 km²) of the Republic Indonesia. The Towuti Drilling Project (TDP) recovered more than 1000 meters of sediment core from three sites. At all three sites replicate cores down to 133, 154, and 174 m below lake floor have penetrated the entire lake sediment record, which is expected to comprise the past ca. 650.000 years continuously. Lake Towutís sediment record thus can provide unique information for instance concerning the climatic and environmental history in the Indo-Pacific-Warm-Pool (IPWP) and concerning the evolutionary biology in SE Asia. For a better understanding of the palaeoenvironmental proxies to be analyzed on the drill cores, the modern processes of sediment formation in the lake and in its catchment - under known environmental conditions - were investigated on a set of 84 lake sediment surface samples. Sampling was conducted by grab sampler (UWITEC Corp., Austria) in a grid of 1 to 4 km resolution that covers the entire lake. The samples were analyzed for inorganic geochemical composition (XRF powder scans and ICP-MS), magnetic susceptibility (Kappabridge), grain-size distribution (laser scanner), biogenic components (smear-slide analyses), biogenic silica contents (leaching), and carbonate, total organic carbon (TOC), nitrogen (TN), and sulfur (TS) concentrations (elemental analyzer). The sediments close to the lake shores and in front of the major river inlets are characterized by mean grain sizes coarser than average and high magnetic susceptibilities presented by high ratios of Cr, Ni, Co, and Zr. This reflects higher energies due to wave action and fluvial sediment supply, as well as the occurrence of magnetic minerals particularly in the sand and gravel fractions of the sediments. In regions of deeper waters and more distal to the shore the grain size and magnetic susceptibility decrease, but the organic carbon vs. total sulfur (C/S) ratio and the redox-sensitive elements such as U, Cd, Mo, and V increase. This suggests that sulfur accumulation in lake Towuti is controlled by autochthoneous pyrite formation, in dependence on differences in redox conditions, rather than gypsum accumulation. Highest silicon (Si) concentrations appear in front of the four major inlets of Lake Towuti, however, a distinct maximum also occurs close to the southeastern shore, where larger river inlets are missing. Hence, the silicon distribution is partly controlled by fluvial input and partly by biogenic silica deposition; the latter is confirmed by high concentrations of pelagic and benthic diatoms as well as sponge spiculae in smear slides from the sediments at the southeastern shore. Hence, the data thus far obtained on the surface sediments of lake Towuti show a strong influence of fluvial sediment supply and water-depth dependent redox conditions on the sediment composition. No indication, in contrast, was found for a significant influence of lake currents on the distribution of the sediments supplied by riverine input.

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.

Polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs in the coastal seawater, surface sediment and oyster from Dalian, Northeast China.

PubMed

Hong, Wen-Jun; Jia, Hongliang; Li, Yi-Fan; Sun, Yeqing; Liu, Xianjie; Wang, Luo

2016-06-01

A total of 46 polycyclic aromatic hydrocarbons (PAHs, 21 parent and 25 alkylated) were determined in seawater, surface sediment and oyster from coastal area of Dalian, North China. The concentration of Σ46PAHs in seawater, sediment, and oyster were 136-621 ng/L, 172-4700 ng/g dry weight (dw) and 60.0-129 ng/g wet weight (ww) in winter, and 65.0-1130 ng/L, 71.1-1090 ng/g dw and 72.8-216 ng/g ww in summer, respectively. High PAH levels were found in industrial area both in winter and summer. Selected PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL, TEL-PEL indexes) for evaluation probable toxic effects on marine organism and the results indicate that surface sediment from all sampling sites have a low to medium ecotoxicological risk. Daily intake of PAHs via oyster as seafood by humans were estimated and the results indicated that oyster intake would not pose a health risk to humans even 30 days after a oil spill accident near by. Water-sediment exchange analysis showed that, both in winter and summer, the fluxes for most high molecular weight PAHs were from seawater to sediment, while for low molecular weight PAHs, an equilibrium was reached between seawater and sediment. Copyright © 2016 Elsevier Inc. All rights reserved.

Adjustable shear stress erosion and transport flume

DOEpatents

Roberts, Jesse D.; Jepsen, Richard A.

2002-01-01

A method and apparatus for measuring the total erosion rate and downstream transport of suspended and bedload sediments using an adjustable shear stress erosion and transport (ASSET) flume with a variable-depth sediment core sample. Water is forced past a variable-depth sediment core sample in a closed channel, eroding sediments, and introducing suspended and bedload sediments into the flow stream. The core sample is continuously pushed into the flow stream, while keeping the surface level with the bottom of the channel. Eroded bedload sediments are transported downstream and then gravitationally separated from the flow stream into one or more quiescent traps. The captured bedload sediments (particles and aggregates) are weighed and compared to the total mass of sediment eroded, and also to the concentration of sediments suspended in the flow stream.

Suspended-Sediment Export From Four Small Montane Humid-Tropical Watersheds With Varying Land use and Lithology, Puerto Rico

NASA Astrophysics Data System (ADS)

Larsen, M. C.

2003-12-01

Intensive land-use conversion of forested landscapes to agricultural use accelerated in most of the global tropics during the 20th century and has resulted in large increases in soil erosion and suspended-sediment export. Fluvial sediment is one of the most abundant freshwater contaminants on earth. Stormflows episodically transport sediment to reservoirs, estuaries and in coastal waters where coral reefs are located. The sediment and associated contaminants such as pesticides, herbicides, and fertilizers, degrade water quality and are harmful to aquatic organisms in these areas. Improved understanding of the processes and rates of fluvial sediment transport in natural and anthropogenically disturbed settings enhances management of natural resources and aids in the establishment of standards for acceptable sediment concentrations. Four USGS WEBB (Water, Energy, and Biogeochemical Budgets) study watersheds in Puerto Rico (18° latitude) were paired to compare and contrast the effects of land use and bedrock geology on suspended-sediment yield. Sediment concentration, calculated as sediment yield normalized to runoff, was more than three times greater in two watersheds in secondary forest and pasture compared to sediment concentration in watersheds in primary forest. The influence of lithology was comparable: sediment concentration in intrusive-bedrock (quartz diorite and granodiorite) watersheds was more than three times higher than sediment concentration in volcaniclastic-bedrock (volcanic sandstone, mudstone, and breccia) watersheds. These contrasts highlight the well-known effect of land use on sediment concentration and yield but also demonstrate the strong control of bedrock geology. Most importantly, the high sediment yields in the watersheds that were converted to pasture and secondary forest, even after 60 years of forest reestablishment, provide a glimpse into the future of tropical watersheds elsewhere that are now undergoing deforestation. Erosion rates observed in agriculturally-developed watersheds are substantial in regard to reservoir storage. Public water supply for the city of San Juan (population 1.6 million) is largely derived from surface-water storage. The principal San Juan reservoir lost approximately 60 percent of its storage capacity from siltation in the 40 years following impoundment in 1954. The reduced storage capacity resulted in severe water rationing for San Juan during several droughts during the past decade.

Are the Element Budget and the Occurrence of Polymetallic Nodules influenced by Fluids Circulating through the Oceanic Crust or/and Sediments?

NASA Astrophysics Data System (ADS)

Heller, C.; Kuhn, T.

2016-12-01

Hydrothermal fluids can extract significant amounts of heat from oceanic lithosphere by lateral fluid flow through permeable basaltic crust of an age of up to 65 Ma. Fluid recharge and discharge occur at basement outcrops in between impermeable pelagic sediments. Recharge of oxic seawater causes upward oxygen diffusion into sediments overlying the permeable basalt in areas proximal to recharge sites. It is suggested that this oxygen have a strong impact on sediments and Mn nodules during fluid exposure time. The aim of this study is to investigate if and how fluid flow through oceanic crust influence the distribution and element budget of the Mn nodules. For that purpose, Mn nodules were examined which were collected during the research cruise SO240 in the equatorial NE Pacific at sites with and without faults in the upper basement and overlying sediments. Faults are thought to be preferred fluid pathways. Nodules were found on the sediment surface as well as in the sediment and consist of different nm- to µm-thick, dense and porous layers. The geochemical composition of bulk nodules and single nodule layers were determined by XRF, ICP-MS/OES and by high resolution analyses with EMPA and LA-ICP-MS. Dense layers have low Mn/Fe ratios (<4) and high concentrations of Co, Zr and REY, while porous layers are characterized by high Mn/Fe ratios (> 10) and high Ni+Cu and Li concentrations (Koschinsky et al., 2010; Kuhn et al., 2010). The different compositions depends on different formation processes of the layers. Dense layers are formed by element precipitation from oxygen rich seawater and/or pore water and are called hydrogenetic, while porous layers were formed by precipitation from almost oxygen-free (suboxic) pore water (Burns & Burns, 1978; Glasby, 2006) and are called diagenetic (Halbach et al., 1988). Preliminary results show that there are significant differences between the geochemical composition of nodules grown at sediment surface and those found within sediments. Compared to surface nodules, buried nodules are enriched in Co and W, but has lower concentration of Mo, Ba, Zn, Li. Distribution of Rare Earth Elements (REY) are also different. Especially, the element distribution in the bulk samples and the single layers of the buried nodules could be used to find a possible influence of circulating fluids on nodule formation.

Pyrethroid sorption to Sacramento River suspended solids and bed sediments

PubMed Central

Fojut, Tessa L.; Young, Thomas M.

2011-01-01

Sorption of pyrethroid insecticides to solid materials will typically dominate the fate and transport of these hydrophobic compounds in aquatic environments. Batch reactor isotherm experiments were performed with bifenthrin and λ-cyhalothrin with suspended material and bed sediment collected from the Sacramento River, CA. These batch reactor experiments were performed with low spiking concentrations and a long equilibration time (28 d) to be more relevant to environmental conditions. Sorption to suspended material and bed sediment was compared to examine the role of differential sorption between these phases in the environmental transport of pyrethroids. The equilibrium sorption data were fit to the Freundlich isotherm model and fit with r2 > 0.87 for all experiments. Freundlich exponents ranged from 0.72 ± 0.19 to 1.07 ± 0.050, indicating sorption nonlinearity for some of the experimental conditions and linearity for others over the concentration range tested. The Freundlich capacity factors were larger for the suspended solids than for the bed sediments and the suspended material had a higher specific surface area and higher organic carbon content compared to the bed sediment. Calculated organic carbon-normalized distribution coefficients were larger than those previously reported in the literature by approximately an order of magnitude and ranged from 106.16 to 106.68 at an equilibrium aqueous concentration of 0.1 µg/L. Higher than expected sorption of pyrethroids to the tested materials may be explained by sorption to black carbon and/or mineral surfaces. PMID:21191877

Spatial distributions, fractionation characteristics, and ecological risk assessment of trace elements in sediments of Chaohu Lake, a large eutrophic freshwater lake in eastern China.

PubMed

Wu, Lei; Liu, Guijian; Zhou, Chuncai; Liu, Rongqiong; Xi, Shanshan; Da, Chunnian; Liu, Fei

2018-01-01

The concentrations, spatial distribution, fractionation characteristics, and potential ecological risks of trace elements (Cu, Pb, Zn, Cr, Ni, and Co) in the surface sediment samples collected from 32 sites in Chaohu Lake were investigated. The improved BCR sequential extraction procedure was applied to analyze the chemical forms of trace elements in sediments. The enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (PERI), and risk assessment code (RAC) were employed to evaluate the pollution levels and the potential ecological risks. The results found that the concentrations of Cu, Pb, Zn, Cr, Ni, and Co in the surface sediments were 78.59, 36.91, 161.84, 98.87, 38.92, and 10.09 mg kg -1 , respectively. The lower concentrations of Cu, Pb, Zn, Cr, and Ni were almost found in the middle part of the lake, while Co increased from the western toward the eastern parts of the lake. Cr, Ni, Co, and Zn predominantly existed in the residual fractions, with the average values of 76.35, 59.22, 45.60, and 44.30%, respectively. Cu and Pb were mainly combined with Fe/Mn oxides in reducible fraction, with the average values of 66.4 and 69.1%, respectively. The pollution levels were different among the selected elements. Cu had the highest potential ecological risk, while Cr had the lowest potential ecological risk.

Quantification of MTE in surface sediments of Morbihan Coast (South Brittany, France): A preliminary approach for determination of sources and dynamics

NASA Astrophysics Data System (ADS)

Jimenez, Joselyn; Goubert, Evelyne; Labeyrie, Laurent; Coynel, Alexandra; Menier, David

2014-05-01

The Morbihan Coast (South Brittany, France) has an intense coastal activity: farming, industry, urban habitation run-off, yachting and transportation. In the past centuries, tin mining industry was also developed. These different factors may introduce metal trace elements (MTE) into the marine environment at toxic concentration levels. This pollution can particularly affect the oyster production, widely developed in the area. Monitoring MTE in surface sediments at high spatial resolution has been programmed to assess pollutants and their sources in two of the major Morbihan coastal systems concerned with oyster farming, and where available information on MTE impact and sediment quality is limited: the Bay of Quiberon, partly protected from the open ocean by the Quiberon Peninsula and several islands, mostly sandy (coarse to fine, with a significant shelly fraction), with water depths shallower that 25 m, and the Gulf of Morbihan, a shallow depth (less than 5 m, apart from the two paleoriver beds), semi-enclosed, estuarine system with very coarse sand to fine mud, mostly distributed by a strong tidal current system. Fifty two surface sediment samples were collected in April 2013 to characterize the MTE spatial distribution through the salinity and pollution gradients, from the small local rivers and harbor areas to the open marine environments. Analyses cover sedimentological and biogeochemical properties (particulate organic carbon using a LECO-CS-230; MTE using ICP-MS or DMA for Hg). Statistical analyses help to discriminate within the spatial variability the natural (e.g. grain-size effect) and anthropogenic factors. MTE concentrations were also compared to local geochemical background as measured at the bottom of three sediment cores collected in representative sites, for calculating the enrichment index of each MTE and evaluating the degree of sediment contamination. The initial interpretation of the results would indicate a clear distinction between the geochemical gradients linked to natural processes: sediment sources and size fractionation (for example, the relationship between Sr and carbonate concentration in the sand fraction), and gradients linked to polluting factors, in particular in the harbors and protected arias, probably associated with boat maintenance (with Cu, Zn and Sn concentrations exceeding 100 ppm, up to 300 ppm in isolated places). More detailed statistical analyses and implications will be presented at the conference.

Lipid biomarkers in surface sediments from the Gulf of Genoa (Ligurian Sea) and their potential for palaeo-environmental reconstructions

NASA Astrophysics Data System (ADS)

Ruggieri, Nicoletta; Kaiser, Jérôme; Arz, Helge W.; Hefter, Jens; Siegel, Herbert; Mollenhauer, Gesine; Lamy, Frank

2014-05-01

A series of molecular organic markers were determined in surface sediments from the Gulf of Genoa (Ligurian Sea) in order to evaluate their potential for palaeo-environmental reconstructions. The interest for the Gulf of Genoa lies in its contrasting coastal and central areas in terms of terrestrial input, oligotrophy, primary production and surface temperature gradient. Moreover, the Gulf of Genoa contains a large potential for climate reconstruction as it is one of the four major Mediterranean centres for cyclogenesis and the ultra high sedimentation rates on the shelf make this area suitable for high resolution environmental reconstruction. Initial results from sediment cores in the coastal area indeed reveal the potential for Holocene environmental reconstruction on up to decadal timescales (see Poster "Reconstruction of late Holocene flooding events in the Gulf of Genoa, Ligurian Sea" by Lamy et al.). During R/V Poseidon cruise P413 (May 2011), ca. 60 sediment cores were taken along the Ligurian shelf, continental slope, and in the basin between off Livorno and the French border. Results based on surface sediments suggest that some biomarker-based proxies are well-suited to reconstruct sea surface temperature (SST), the input of terrestrial organic material (TOM), and marine primary productivity (PP). The estimated UK'37 SST reflects very closely the autumnal mean satellite-based SST distribution, while TEXH86 SSTs correspond to summer SST at offshore sites and to winter SST for the nearshore sites. Using both SST proxies together may thus allow reconstructing past seasonality changes. Proxies for TOM input (terrestrial n-alkane and n-alkanol concentrations, BIT index) have higher values close to the major river mouths and decrease offshore suggesting that these may be used as proxy for the variability in TOM input by runoff. Interestingly, high n-alkane average chain length in the most offshore sites may result from aeolian input from northern Africa. Finally, high concentrations of crenarchaeol and isoprenoid GDGTs in the open basin illustrate the preference of Thaumarchaeota for oligotrophic waters. This study represents a major prerequisite for the future application of lipid biomarkers on sediment cores from the Gulf of Genoa.

Diurnal shifts in co-distributions of sulfide and iron(II) and profiles of phosphate and ammonium in the rhizosphere of Zostera capricorni

NASA Astrophysics Data System (ADS)

Pagès, Anaïs; Welsh, David T.; Robertson, David; Panther, Jared G.; Schäfer, Jörg; Tomlinson, Rodger B.; Teasdale, Peter R.

2012-12-01

High resolution, two dimensional distributions of porewater iron(II) and sulfide were measured, using colourimetric DET (diffusive equilibration in a thin film) and DGT (diffusive gradients in a thin film) techniques, respectively, in Zostera capricorni colonised sediments under both light and dark conditions. Low resolution depth profiles of ammonium and phosphate were measured using conventional DET and DGT methods, respectively. Porewater iron(II) and sulfide distributions showed a high degree of spatial heterogeneity under both light and dark conditions, and distributions were characterised by a complex mosaic of sediment zones dominated by either iron(II) or sulfide. However, there was a clear shift in overall redox conditions between light and dark conditions. During light deployments, iron(II) and sulfide concentrations were generally low throughout the rhizosphere, apart from a few distinct "hotspots" of high concentration. Whereas during dark deployments, high concentrations of iron(II) were sometimes measured in the near surface sediments and sulfide depth distributions migrated towards the sediment surface. Profiles of porewater ammonium and phosphate demonstrated an increase in ammonium concentrations under dark compared to light conditions. Surprisingly, despite the large changes in iron(II) distributions between light and dark conditions, phosphate profiles remained similar, indicating that adsorption/release of phosphate by iron(III) hydr(oxide) mineral formation and reduction was not a major factor regulating porewater phosphate concentrations in these sediments or that phosphate uptake by the seagrass roots persisted during the dark period. Overall, the results demonstrate that the photosynthetic activity of the seagrass played a significant role in regulating sulfide, iron(II) and ammonium concentrations in the rhizosphere, due to rates of radial oxygen loss and ammonium uptake by the roots and rhizomes being lower under dark compared to light conditions. This cyclic production and reduction of iron(III) hydr(oxides) in the rhizosphere may act as a buffering system preventing sulfide accumulation.

Near-Field Receiving Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2007

USGS Publications Warehouse

Lorenzi, Allison H.; Cain, Daniel J.; Parcheso, Francis; Thompson, Janet K.; Luoma, Samuel N.; Hornberger, Michelle I.; Dyke, Jessica

2008-01-01

Results reported herein include trace element concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica (Cohen and Carlton 1995)), clam reproductive activity, and benthic macroinvertebrate community structure for a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay. This report includes data collected for the period January 2007 to December 2007, and extends a critical long-term biogeochemical record dating back to 1974. These data serve as the basis for the City of Palo Alto?s Near-Field Receiving Water Monitoring Program, initiated in 1994. Metal concentrations in both sediments and clam tissue during 2007 remained consistent with results observed since 1990. Most notably, copper and silver concentrations in sediment and clam tissue are elevated for the second consecutive year, but the values remain well within the range of past findings. Other metals such as chromium, nickel, vanadium, and zinc remained relatively constant throughout the year except for maximum values that generally occur in winter months (January-March). Mercury levels in sediment and clam tissue were some of the lowest seen on record. Last year?s elevated selenium levels appear to be transient, and selenium concentrations have returned to background levels. Overall, metal concentrations in sediments and tissue remain within past findings. Analyses of the benthic-community structure of a mudflat in South San Francisco Bay over a 31-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of the reproductive activity of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable, with almost all animals initiating reproduction in the fall and spawning the following spring of most years. The community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that suggests a more stable community that is subjected to less stress. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes, have shown a continual decline in dominance coincident with the decline in metals. Heteromastus filiformis, a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying their eggs on or in the sediment, has shown a concurrent increase in dominance and is now showing signs of population stability. These changes in species dominance reflect a change in the community from one dominated by surface dwelling, brooding species to one with species with varying life history characteristics.

Geochemical controls on lead concentrations in stream water and sediments

USGS Publications Warehouse

Hem, J.D.

1976-01-01

The equilibrium distribution of lead in solution and adsorbed on cation exchange sites in sediment theoretically may be calculated from equations representing selectivities of substrate for lead over H+, Ca2+ and Na+, and the stabilities of lead solute species. Such calculations include consideration of total concentrations of major ions, cation exchange capacity (CEC) of substrate, and pH, at values expected in various natural systems. Measurements of CEC and selectivity coefficients were made for synthetic halloysite, a finely divided amorphous 1:1 clay prepared by precipitation from a mixture of solutions of aluminum and silica. Where suspended sediment having the same properties is present in concentrations of 10-1,000 mg/1 at pH 6-8, more than 90% of the lead present can be adsorbed on sediment surfaces. The cation exchange behavior of lead and other minor cationic species in natural systems could be predicted by this type of model if enough other supporting information were available. Information of the type needed describing natural stream sediments, however, is presently inadequate for accurate predictions. ?? 1976.

Environmental setting, water quality, and ecological indicators of surface-water quality in the Mermentau River Basin, southwestern Louisiana, 1998-2001

USGS Publications Warehouse

Skrobialowski, Stanley C.; Mize, Scott V.; Demcheck, Dennis K.

2004-01-01

The U.S. Geological Survey collected data from 29 wells and 24 surface-water sites in the Mermentau River Basin, 1998-2001, to better understand ground-water and surface-water quality; aquatic invertebrate communities; and habitat conditions, in relation to land use. This study was apart of the National Water-Quality Assessment Program, which was designed to assess water quality as it relates to various land uses. Water-quality data were evaluated with criteria established for the protection of drinking water and aquatic life, and bed-sediment data were compared to aquatic life criteria. Water-quality and ecological data were analyzed statistically in relation to drainage area and agricultural land-use integrity. Concentrations of nutrients and major inorganic ions in ground water and surface water generally were highest in the southeastern part of the study area where soils contain thick loess deposits. Peak concentrations of nutrients in surface water occurred March-may at two sites with high agricultural intensity; the lowest concentrations occurred August-January. The greatest potential for eutrophic conditions in surface water, based on nutrient concentrations, existed March-May, at about the same time or shortly after ricefields were drained. Secondary Maximum Contaminant Levels established by the U.S. Environmental Protection Agency (USEPA) were exceeded for sulfate, chloride, iron, or manganese in samples from 20 wells, and for iron or manganese in samples from all surface-water sites. Fewer pesticides were detected in ground water than in surface water. In 11 of of the 29 wells sampled, at least one pesticide or pesticide degradation product was detected. The most frequently detected pesticides or pesticide degradation products in ground water were the herbicides benzaton and atrazine. Concentrations of 47 pesticides and degradation products were detected in surface water. At least 3 pesticides were detected in all surface-water samples. In 72 percent of the samples at least 5 hydrophilic pesticides were detected, and in more than 70 percent of the samples at least 3 hydrophobic pesticides were detected. Although atrazine concentrations in three samples collected in the spring exceeded 3 micrograms per liter, the USEPA Maximum Contaminant Level of 3 micrograms per liter was not exceeded because it is based on an annual average of quarterly samples. Concentrations larger than 3.0 micrograms per liter were not detected in samples collected during other times of the year. Tebuthiuron was detected at all surface-water sites; the largest concentration (6.33 micrograms per liter) was detected at a site on Bayou des Cannes, and was the only detection that exceeded the criterion (1.6 micrograms per liter) for the protection of aquatic life. Malathion was detected at 16 surface-water sites; the largest concentration (0.113 micrograms per liter) was detected at a site on Bayou Lacassine and was the only detection that exceeded the criterion (0.1 micrograms per liter) for the protection of aquatic life. Concentrations of fipronil exceeded numeric targets for acute total maximum daily loads (2.3 micrograms per liter) at 3 sites and chronic total maximum daily loads (4.6 micrograms per liter) at 14 sites. Maximum pesticide concentrations in surface water usually occurred in the spring at about the same time or shortly after ricefields were drained. Concentrations of DDE in bed sediment at two sites exceeded interim freshwater sediment quality guidelines for the protection of aquatic life. Fipronil sulfide and desulfinylpronil were detected at all 17 sites from which bed-sediment samples were collected, but there are no current (2002) guidelines with which to evaluate the environmental effects of fipronil and degradation products. Two methods were used to group the ecological data-collection sites: (1) Sites were grouped before data collection (according to the study design) using drainage area

Arsenic speciation and transport associated with the release of spent geothermal fluids in Mutnovsky field (Kamchatka, Russia)

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

Ilgen, Anastasia G.; Rychagov, Sergey N.; Trainor, Thomas P.

The use of geothermal fluids for the production of electricity poses a risk of contaminating surface waters when spent fluids are discharged into (near) surface environments. Arsenic (As) in particular is a common component in geothermal fluids and leads to a degradation of water quality when present in mobile and bioavailable forms. We have examined changes in arsenic speciation caused by quick transition from high temperature reducing conditions to surface conditions, retention mechanisms, and the extent of transport associated with the release of spent geothermal fluids at the Dachny geothermal fields (Mutnovsky geothermal region), Kamchatka, Russia -- a high temperaturemore » field used for electricity production. In the spent fluids, the arsenic concentration reaches 9 ppm, while in natural hot springs expressed in the vicinity of the field, the As concentration is typically below 10 ppb. The aqueous phase arsenic speciation was determined using Liquid Chromatography (LC) coupled to an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The arsenic speciation in the bottom sediments (< 65 {mu}m fraction) of the local surface waters was analyzed using X-ray Absorption Spectroscopy (XAS). Arsenic in the geothermal source fluids is predominantly found as As(III), while a mixture of As(III)/As(V) is found in the water and sediment of the Falshivaia River downstream from the power plant. The extent of elevated arsenic concentrations in water is limited by adsorption to the bottom sediment and dilution, as determined using Cl{sup -} from the deep well fluids as a tracer. Analysis of the Extended X-ray Absorption Fine Structure (EXAFS) spectra shows that sediment phase arsenic is associated with both Al- and Fe-rich phases with a bi-dentate corner sharing local geometry. The geothermal waste fluids released in the surface water create a localized area of arsenic contamination. The extent of transport of dissolved As is limited to {approx}7 km downstream from the source, while As associated with bottom sediment travels {approx}3 km farther.« less

Role of manganese oxides in the exposure of mute swans (Cygnus olor) to Pb and other elements in the Chesapeake Bay, USA

USGS Publications Warehouse

Beyer, W.N.; Day, D.

2004-01-01

The aims of this study are to estimate exposure of waterfowl to elements in contaminated sediments in the Chesapeake Bay and to consider the potential role of Mn in influencing bioavailability and exposure. Mute swans living on the Aberdeen Proving Ground were collected and samples of swan digesta were analyzed and compared to samples of feces collected from mute swans living at a nearby reference site. Sediments from the proving ground had elevated concentrations of Cu, S, Se, Zn, As, Co, Cr, Hg and Pb, but concentrations of only the first four of these elements were elevated in swan digesta. Sediments from the proving ground had an elevated mean concentration of total As, about seven times the concentration at the reference site, but the swans from that site were not ingesting more As than were reference swans. Swans at both sites were feeding on submerged aquatic vegetation and ingested about 4% sediment at the proving ground and about 5% sediment at the reference site. None of the concentrations detected in the digesta or livers of the swans was considered toxic, although the concentrations of Cu and Se were high compared to those concentrations reported in other waterfowl. A remarkably high mean concentration of Mn (6900 mg/kg, dry weight) detected in the feces of the reference swans was attributed to the deposition of manganese oxides on vegetation. The ingestion of Pb by swans at the reference site was correlated with Mn and Fe concentrations, rather than with markers of sediment ingestion. The Pb was presumably scavenged by Mn and Fe oxides from the water and deposited on the surface of vegetation. Under some environmental chemical conditions, this route of exposure for Pb is more important than sediment ingestion, which was previously thought to be the main route of exposure.

Rare earth element geochemistry characteristics of seawater and porewater from deep sea in western Pacific.

PubMed

Deng, Yinan; Ren, Jiangbo; Guo, Qingjun; Cao, Jun; Wang, Haifeng; Liu, Chenhui

2017-11-28

Deep-sea sediments contain high concentrations of rare earth element (REE) which have been regarded as a huge potential resource. Understanding the marine REE cycle is important to reveal the mechanism of REE enrichment. In order to determine the geochemistry characteristics and migration processes of REE, seawater, porewater and sediment samples were systematically collected from the western Pacific for REE analysis. The results show a relatively flat REE pattern and the HREE (Heavy REE) enrichment in surface and deep seawater respectively. The HREE enrichment distribution patterns, low concentrations of Mn and Fe and negative Ce anomaly occur in the porewater, and high Mn/Al ratios and low U concentrations were observed in sediment, indicating oxic condition. LREE (Light REE) and MREE (Middle REE) enrichment in upper layer and depletion of MREE in deeper layer were shown in porewater profile. This study suggests that porewater flux in the western Pacific basin is a minor source of REEs to seawater, and abundant REEs are enriched in sediments, which is mainly caused by the extensive oxic condition, low sedimentation rate and strong adsorption capacity of sediments. Hence, the removal of REEs of porewater may result in widespread REE-rich sediments in the western Pacific basin.

[Effects of sediment dredging on benthos community structure and water quality in Zhushan Bay].

PubMed

Liu, Guo-Feng; Zhang, Zhi-Yong; Liu, Hai-Qin; Zhong, Ji-Cheng; Yan, Shao-Hua; Fan, Cheng-Xin

2010-11-01

We surveyed the changes of macro-benthos community composition and nutrients concentration in water in Zhushan Bay after it had been dredged 6 months, which aimed to remove the polluted surface sediments. The results showed that the main benthos in the dredged and un-dredged sediments were Limodrilus hoffmeisteri, Pelopia and Bellamya aeruginosa; compared to the un-dredged sediments, the bio-diversity of dredged areas became lower. However, its biomass became higher than that in un-dredged areas. Concentration range changes of TN and TP in overlying water was 1.64-4.45 mg/L and 0.133-0.258 mg/L, respectively. The post-dredged sediments were still in a higher state of nutrients for the higher concentration nutrients in overlying water, macro-benthos were the species that lived in a serious polluted water environment. Using Shannon-Weaver, Simpson, and Goodnight benthic index to evaluate the results show that the dredged area is in the moderately polluted level, but un-dredged area is in the middle-heavily polluted level. According to the benthos fauna surveys and water quality monitoring results, the effective of sediment dredging could play its role only the strict control on the external pollution resources have been made and reduces the effects of polluted water on the sediments.

Numerical Simulation of Plume Transport in Channel Bend with Different Sediment Diameters

NASA Astrophysics Data System (ADS)

Kim, H. S.; Chen, H. C.

2017-12-01

The flow and transport of suspended sediment particles, in the form of plume, were simulated using an in-house Computational Fluid Dynamics (CFD) solver FANS3D (Finite Analytic Navier-Stokes code for 3D flow). The motivation for this investigation is to provide a means to simulate and visualize dispersal systems in a complex flow environment. The physical domain considered is a 90-degrees channel bend with wingwall abutments, which induces complex, three-dimensional flow characteristics. At the inlet of the channel, a sediment plume with the volumetric concentration of 1,000 parts per million (ppm) was constantly supplied. For simplicity, it was assumed that neither deposition nor erosion takes place inside the channel and settling sediment was made to pass through the bed surface. The effect of the sediment particle size was also analyzed using two different median diameters: 0.10 mm and 0.20 mm. It was shown that flow acceleration and vortices cause strong mixing inside the channel. The three-dimensional time series from the simulation captured increasing suspended sediment concentration downstream of the abutments, along the outer bank. When the median diameter was varied, the sediment concentration at certain locations differed by orders of magnitude, indicating that the settling velocity dominates the transport process for larger diameters.

Mercury distribution in ancient and modern sediment of northeastern Bering Sea

USGS Publications Warehouse

Nelson, C.H.; Pierce, D.E.; Leong, K.W.; Wang, F.F.H.

1975-01-01

Reconnaissance sampling of surface and subsurface sediment to a maximum depth of 80 m below the sea floor shows that typical values of 0.03 p.p.m. and anomalies of 0.2-1.3 p.p.m. mercury have been present in northeastern Bering Sea since Early Pliocene time. Values are highest in modern beach (maximum 1.3 and mean 0.22 p.p.m. Hg) and nearshore subsurface gravels (maximum 0.6 and mean 0.06 p.p.m. Hg) along the highly mineralized Seward Peninsula and in clayey silt rich in organic matter (maximum 0.16 and mean 0.10 p.p.m. Hg) throughout the region. Although gold mining may be partly responsible for high mercury levels in the modern beach near Nome, Alaska (maximum 0.45 p.p.m.), equally high or greater concentrations of mercury occur in buried Pleistocene sediments immediately offshore (maximum 0.6 p.p.m.) and in modern unpolluted beach sediments at Bluff (maximum 1.3 p.p.m.); this suggests that the contamination effects of mining may be no greater than natural concentration processes in the Seward Peninsula region. The mercury content of offshore surface sediment, even adjacent to mercury-rich beaches, corresponds to that of unpolluted marine and fresh-water sediment elsewhere. The normal values that prevail offshore may be attributable to entrapment of mercury-bearing heavy minerals on beaches near sources and/or dilution effects of offshore sedimentation. The few minor anomalies offshore occur in glacial drift derived from mercury source regions of Chukotka (Siberia) and Seward Peninsula; Pleistocene shoreline processes have reworked the drift to concentrate the heavy metals. The distribution pattern of mercury indicates that particulate mercury-bearing minerals have not been widely dispersed from onland deposits in quantities sufficient to increase mercury levels above normal in offshore sediments of Bering Sea; however, it shows that natural sedimentary processes can concentrate this mercury in beaches of the coastal zone where there already is concern because of potential pollution from man's activities.

Phosphorus losses from agricultural land to natural waters are reduced by immobilization in iron-rich sediments of drainage ditches.

PubMed

Baken, Stijn; Verbeeck, Mieke; Verheyen, Dries; Diels, Jan; Smolders, Erik

2015-03-15

Redox reactions involving iron (Fe) strongly affect the mobility of phosphorus (P) and its migration from agricultural land to freshwater. We studied the transfer of P from groundwater to open drainage ditches in an area where, due to Fe(II) rich groundwater, the sediments of these ditches contain accumulated Fe oxyhydroxides. The average P concentrations in the groundwater feeding two out of three studied drainage ditches exceeded environmental limits for freshwaters by factors 11 and 16, but after passing through the Fe-rich sediments, the P concentrations in the ditch water were below these limits. In order to identify the processes which govern Fe and P mobility in these systems, we used diffusive equilibration in thin films (DET) to measure the vertical concentration profiles of P and Fe in the sediment pore water and in the ditchwater. The Fe concentrations in the sediment pore water ranged between 10 and 200 mg L(-1) and exceeded those in the inflowing groundwater by approximately one order of magnitude, due to reductive dissolution of Fe oxyhydroxides in the sediment. The dissolved P concentrations only marginally increased between groundwater and sediment pore water. In the poorly mixed ditchwater, the dissolved Fe concentrations decreased towards the water surface due to oxidative precipitation of fresh Fe oxyhydroxides, and the P concentrations decreased more sharply than those of Fe. These observations support the view that the dynamics of Fe and P are governed by reduction reactions in the sediment and by oxidation reactions in the ditchwater. In the sediment, reductive dissolution of P-containing Fe oxyhydroxides causes more efficient solubilization of Fe than of P, likely because P is buffered by adsorption on residual Fe oxyhydroxides. Conversely, in the ditchwater, oxidative precipitation causes more efficient immobilization of P than of Fe, due to ferric phosphate formation. The combination of these processes yields a natural and highly efficient sink for P. It is concluded that, in Fe-rich systems, the fate of P at the sediment-water interface is determined by reduction and oxidation of Fe. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Scott, Nicole M.; Hess, Matthias; Bouskill, Nick J.

During hydrocarbon exposure, the composition and functional dynamics of marine microbial communities are altered, favoring bacteria that can utilize this rich carbon source. Initial exposure of high levels of hydrocarbons in aerobic surface sediments can enrich growth of heterotrophic microorganisms having hydrocarbon degradation capacity. As a result, there can be a localized reduction in oxygen potential within the surface layer of marine sediments causing anaerobic zones. We hypothesized that increasing exposure to elevated hydrocarbon concentrations would positively correlate with an increase in denitrification processes and the net accumulation of dinitrogen. This hypothesis was tested by comparing the relative abundance ofmore » genes associated with nitrogen metabolism and nitrogen cycling identified in 6 metagenomes from sediments contaminated by polyaromatic hydrocarbons from the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico, and 3 metagenomes from sediments associated with natural oil seeps in the Santa Barbara Channel. An additional 8 metagenomes from uncontaminated sediments from the Gulf of Mexico were analyzed for comparison. We predicted relative changes in metabolite turnover as a function of the differential microbial gene abundances, which showed predicted accumulation of metabolites associated with denitrification processes, including anammox, in the contaminated samples compared to uncontaminated sediments, with the magnitude of this change being positively correlated to the hydrocarbon concentration and exposure duration. Furthermore, these data highlight the potential impact of hydrocarbon inputs on N cycling processes in marine sediments and provide information relevant for system scale models of nitrogen metabolism in affected ecosystems.« less

Water-quality monitoring for a pilot piling removal field evaluation, Coal Creek Slough, Washington, 2008-09

USGS Publications Warehouse

Nilsen, Elena B.; Alvarez, David A.

2011-01-01

Significant Findings Water and sediment quality monitoring was conducted before and after the removal of a piling field located in Coal Creek Slough near Longview, Washington. Passive chemical samplers and continuous water-quality monitoring instruments were deployed at the piling removal site, Coal Creek Slough Site 1 (CCS1), and at a comparison site, Coal Creek Slough Site 2 (CCS2), before (2008) and after (2009) piling removal. Surface and subsurface (core) sediment samples were collected before and after piling removal and were analyzed for grain size, organic carbon content, and chemicals of concern. Significant findings from this study include: * Phenanthrene was the only compound detected in wood piling samples analyzed for a large suite of semivolatile organic compounds and polycyclic aromatic hydrocarbons (PAHs). Metals potentially associated with wood treatment were detected in the wood piling samples at low concentrations. * Organic carbon was slightly lower in core samples from CCS1 in pre-removal (2008) and post-removal (2009) samples than in surface samples from both sites in both years. * Grain-size class distributions were relatively uniform between sites and years. * Thirty-four out of 110 chemicals of concern were detected in sediments. Eight of those detected were anthropogenic waste indicator (AWI) compounds, 18 were PAHs, 4 were sterols, and 4 were metals potentially associated with wood treatment. * Nearly all reported concentrations of chemicals of concern in sediments are qualified as estimates, primarily due to interferences in extracts resulting from complex sample matrices. Indole, perylene, and fluoranthene are reported without qualification for some of the samples, and the metals are reported without qualification for all samples. * The highest frequency of detection of chemicals of concern was seen in the pre-removal surface samples at both sites. * AWI compounds were detected less frequently and at lower concentrations during the post-removal sampling compared to the pre-removal sampling. * Several PAHs were detected at relatively high concentrations in core samples, likely indicating historical sources. * Most commonly detected PAHs in sediments were 2,6-dimethylnaphthalene, fluoranthene, perylene, and pyrene. * Most commonly detected AWIs in sediments were 3-methyl-1h-indole (skatol), acetophenone, indole, phenol, and paracresol. * Sedimentary concentrations of perylene exceeded available sediment quality guidelines. Perylene is widespread in the environment and has large potential natural sources in addition to its anthropogenic sources. * Concentrations of metals did not exceed sediment quality guidelines. * Multiple organochlorine pesticides, both banned and currently used, were detected at each site using passive samplers. * Commonly detected pesticides included hexachlorobenzene, pentachloroanisole (a degradation product of pentachlorophenol), diazinon, cis-chlordane, endosulfan, DDD, and endosulfan sulfate. * PBDE concentrations detected in passive sampler extracts were less than the method detection limit at all sites with the exception of PBDE-99, detected at a concentration less than the reporting limit. * The fragrance galaxolide was detected at a concentration greater than the method detection limit. * Common PAHs, such as phenanthrene, fluoranthene, and pyrene, were detected in every passive sampler. * Dissolved oxygen concentration was slightly higher at site CCS1 compared to site CCS2 in both years. * Overall, there was no systematic increase in chemicals of concern at the restoration site during post-removal monitoring compared to conditions during pre-removal monitoring. Any immediate, short-duration effects of piling removal on water quality could not be determined because monitoring was not conducted during the removal.

On the bioavailability of trace metals in surface sediments: a combined geochemical and biological approach.

PubMed

Roosa, Stéphanie; Prygiel, Emilie; Lesven, Ludovic; Wattiez, Ruddy; Gillan, David; Ferrari, Benoît J D; Criquet, Justine; Billon, Gabriel

2016-06-01

The bioavailability of metals was estimated in three river sediments (Sensée, Scarpe, and Deûle Rivers) impacted by different levels of Cu, Cd, Pb, and Zn (Northern France). For that, a combination of geochemistry and biological responses (bacteria and chironomids) was used. The results obtained illustrate the complexity of the notion of "bioavailability." Indeed, geochemical indexes suggested a low toxicity, even in surface sediments with high concentrations of total metals and a predicted severe effect levels for the organisms. This was also suggested by the abundance of total bacteria as determined by DAPI counts, with high bacterial cell numbers even in contaminated areas. However, a fraction of metals may be bioavailable as it was shown for chironomid larvae which were able to accumulate an important quantity of metals in surface sediments within just a few days.We concluded that (1) the best approach to estimate bioavailability in the selected sediments is a combination of geochemical and biological approaches and that (2) the sediments in the Deûle and Scarpe Rivers are highly contaminated and may impact bacterial populations but also benthic invertebrates.

Approaches to surface complexation modeling of Uranium(VI) adsorption on aquifer sediments

NASA Astrophysics Data System (ADS)

Davis, James A.; Meece, David E.; Kohler, Matthias; Curtis, Gary P.

2004-09-01

Uranium(VI) adsorption onto aquifer sediments was studied in batch experiments as a function of pH and U(VI) and dissolved carbonate concentrations in artificial groundwater solutions. The sediments were collected from an alluvial aquifer at a location upgradient of contamination from a former uranium mill operation at Naturita, Colorado (USA). The ranges of aqueous chemical conditions used in the U(VI) adsorption experiments (pH 6.9 to 7.9; U(VI) concentration 2.5 · 10 -8 to 1 · 10 -5 M; partial pressure of carbon dioxide gas 0.05 to 6.8%) were based on the spatial variation in chemical conditions observed in 1999-2000 in the Naturita alluvial aquifer. The major minerals in the sediments were quartz, feldspars, and calcite, with minor amounts of magnetite and clay minerals. Quartz grains commonly exhibited coatings that were greater than 10 nm in thickness and composed of an illite-smectite clay with occluded ferrihydrite and goethite nanoparticles. Chemical extractions of quartz grains removed from the sediments were used to estimate the masses of iron and aluminum present in the coatings. Various surface complexation modeling approaches were compared in terms of the ability to describe the U(VI) experimental data and the data requirements for model application to the sediments. Published models for U(VI) adsorption on reference minerals were applied to predict U(VI) adsorption based on assumptions about the sediment surface composition and physical properties (e.g., surface area and electrical double layer). Predictions from these models were highly variable, with results overpredicting or underpredicting the experimental data, depending on the assumptions used to apply the model. Although the models for reference minerals are supported by detailed experimental studies (and in ideal cases, surface spectroscopy), the results suggest that errors are caused in applying the models directly to the sediments by uncertain knowledge of: 1) the proportion and types of surface functional groups available for adsorption in the surface coatings; 2) the electric field at the mineral-water interface; and 3) surface reactions of major ions in the aqueous phase, such as Ca 2+, Mg 2+, HCO 3-, SO 42-, H 4SiO 4, and organic acids. In contrast, a semi-empirical surface complexation modeling approach can be used to describe the U(VI) experimental data more precisely as a function of aqueous chemical conditions. This approach is useful as a tool to describe the variation in U(VI) retardation as a function of chemical conditions in field-scale reactive transport simulations, and the approach can be used at other field sites. However, the semi-empirical approach is limited by the site-specific nature of the model parameters.

Approaches to surface complexation modeling of Uranium(VI) adsorption on aquifer sediments

USGS Publications Warehouse

Davis, J.A.; Meece, D.E.; Kohler, M.; Curtis, G.P.

2004-01-01

Uranium(VI) adsorption onto aquifer sediments was studied in batch experiments as a function of pH and U(VI) and dissolved carbonate concentrations in artificial groundwater solutions. The sediments were collected from an alluvial aquifer at a location upgradient of contamination from a former uranium mill operation at Naturita, Colorado (USA). The ranges of aqueous chemical conditions used in the U(VI) adsorption experiments (pH 6.9 to 7.9; U(VI) concentration 2.5 ?? 10-8 to 1 ?? 10-5 M; partial pressure of carbon dioxide gas 0.05 to 6.8%) were based on the spatial variation in chemical conditions observed in 1999-2000 in the Naturita alluvial aquifer. The major minerals in the sediments were quartz, feldspars, and calcite, with minor amounts of magnetite and clay minerals. Quartz grains commonly exhibited coatings that were greater than 10 nm in thickness and composed of an illite-smectite clay with occluded ferrihydrite and goethite nanoparticles. Chemical extractions of quartz grains removed from the sediments were used to estimate the masses of iron and aluminum present in the coatings. Various surface complexation modeling approaches were compared in terms of the ability to describe the U(VI) experimental data and the data requirements for model application to the sediments. Published models for U(VI) adsorption on reference minerals were applied to predict U(VI) adsorption based on assumptions about the sediment surface composition and physical properties (e.g., surface area and electrical double layer). Predictions from these models were highly variable, with results overpredicting or underpredicting the experimental data, depending on the assumptions used to apply the model. Although the models for reference minerals are supported by detailed experimental studies (and in ideal cases, surface spectroscopy), the results suggest that errors are caused in applying the models directly to the sediments by uncertain knowledge of: 1) the proportion and types of surface functional groups available for adsorption in the surface coatings; 2) the electric field at the mineral-water interface; and 3) surface reactions of major ions in the aqueous phase, such as Ca2+, Mg2+, HCO3-, SO42-, H4SiO4, and organic acids. In contrast, a semi-empirical surface complexation modeling approach can be used to describe the U(VI) experimental data more precisely as a function of aqueous chemical conditions. This approach is useful as a tool to describe the variation in U(VI) retardation as a function of chemical conditions in field-scale reactive transport simulations, and the approach can be used at other field sites. However, the semi-empirical approach is limited by the site-specific nature of the model parameters. ?? 2004 Elsevier Ltd.

Distribution of biogenic silica and quartz in recent deep-sea sediments

NASA Astrophysics Data System (ADS)

Leinen, Margaret; Cwienk, Douglas; Heath, G. Ross; Biscaye, Pierre E.; Kolla, V.; Thiede, Jørn; Dauphin, J. Paul

1986-03-01

All available quartz and biogenic silica concentrations from deep-sea surface sediments were intercalibrated, plotted, and contoured on a calcium-carbonate-free basis. The maps show highest concentrations of biogenic silica (opal) along the west African coast, along equatorial divergences in all oceans, and at the Polar Front in the southern Indian Ocean. These are all areas where upwelling is strong and there is high biological productivity. Quartz in pelagic sediments deposited far from land is generally eolian in origin. Its distribution reflects dominant wind systems in the Pacific, but in much of the Atlantic and Indian oceans the distribution pattern is strongly modified by turbidite deposition and bottom current processes.

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.

Present and Reference Concentrations and Yields of Suspended Sediment in Streams in the Great Lakes Region and Adjacent Areas

USGS Publications Warehouse

Robertson, Dale M.; Saad, David A.; Heisey, Dennis M.

2006-01-01

In-stream suspended sediment and siltation and downstream sedimentation are common problems in surface waters throughout the United States. The most effective way to improve surface waters impaired by sediments is to reduce the contributions from human activities rather than try to reduce loadings from natural sources. Total suspended sediment/solids (TSS) concentration data were obtained from 964 streams in the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River Basins from 1951 to 2002. These data were used to estimate median concentrations, loads, yields, and volumetrically (flow) weighted (VW) concentrations where streamflow data were available. SPAtial Regression-Tree Analysis (SPARTA) was applied to land-use-adjusted (residualized) TSS data and environmental-characteristic data to determine the natural factors that best described the distribution of median and VW TSS concentrations and yields and to delineate zones with similar natural factors affecting TSS, enabling reference or natural concentrations and yields to be estimated. Soil properties (clay and organic-matter content, erodibility, and permeability), basin slope, and land use (percentage of agriculture) were the factors most strongly related to the distribution of median and VW TSS concentrations. TSS yields were most strongly related to amount of precipitation and the resulting runoff, and secondarily to the factors related to high TSS concentrations. Reference median TSS concentrations ranged from 5 to 26 milligrams per liter (mg/L), reference median annual VW TSS concentrations ranged from 10 to 168 mg/L, and reference TSS yields ranged from about 980 to 90,000 kilograms per square kilometer per year. Independent streams (streams with no overlapping drainage areas) with TSS data were ranked by how much their water quality exceeded reference concentrations and yields. Most streams exceeding reference conditions were in the central part of the study area, where agricultural activities are the most intensive; however, other sites exceeding reference conditions were identified outside of this area. Whether concentrations or yields should be considered in guiding rehabilitation efforts depends on whether in-stream or downstream effects are more important. Although this study attempted to obtain all available water-quality data for the study area, any actual prioritization of sites for remediation would need to rely on more extensive data collection or numerical models that can accurately simulate the effects of various human activities in a range of environmental settings.

Metal concentrations in aquatic environments of Puebla River basin, Mexico: natural and industrial influences.

PubMed

Morales-García, S S; Rodríguez-Espinosa, P F; Shruti, V C; Jonathan, M P; Martínez-Tavera, E

2017-01-01

The rapid urban expansion and presence of volcanoes in the premises of Puebla River basin in central Mexico exert significant influences over its aquatic environments. Twenty surface sediment samples from Puebla River basin consisting of R. Alseseca, R. Atoyac, and Valsequillo dam were collected during September 2009 and analyzed for major (Al, Fe, Mg, Ba, Ca, and K) and trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) in order to identify the metal concentrations and their enrichment. R. Atoyac sediments presented higher concentrations of Ba (1193.8 μg g -1 ) and Pb (27.1 μg g -1 ) in comparison with the local reference sample values. All the metal concentrations except Sr for R. Alseseca sediments were within the range of local reference sample values indicating no significant external influence, whereas Valsequillo dam sediments had elevated concentrations of all the metals suggesting both natural and external influences in the study region. The magnitude of metal contamination was assessed using several indices such as geoaccumulation index (I geo ), enrichment factor (EF), degree of contamination (C d ), and pollution load index (PLI). The results suggest that As, Pb, and Zn were predominantly enriched in the Puebla River basin sediments. Comparing with sediment quality guidelines and ecotoxicological values, it is revealed that Cd, Cr, Cu, and Ni have possible harmful effects on the biological community. The present study provides an outlook of metal enrichment in Puebla River basin sediments, highlighting the necessity to conserve this river ecosystem for the near future.

Effect of mining and related activities on the sediment trace element geochemistry of Lake Coeur D'Alene, Idaho, USA. Part I: Surface sediments

USGS Publications Warehouse

Horowitz, Arthur J.; Elrick, Kent A.; Cook, Robert B.

1993-01-01

During the summer of 1989 surface sediment samples were collected in Lake Coeur d'Alene, the Coeur d'Alene River and the St Joe River, Idaho, at a density of approximately one sample per square kilometre. Additional samples were collected from the banks of the South Fork of the Coeur d'Alene and the Coeur d'Alene Rivers in 1991. All the samples were collected to determine trace element concentrations, partitioning and distribution patterns, and to relate them to mining, mining related and discharge operations that have occurred in the Coeur d'Alene district since the 1880s, some of which are ongoing.Most of the surface sediments in Lake Coeur d'Alene north of Conkling Point and Carey Bay are substantially enriched in Ag, As, Cu, Cd, Hg, Pb, Sb and Zn relative to unaffected sediments in the southern portion of the lake near the St Joe River. All the trace element enriched sediments are extremely fine grained (mean grain sizes « 63 μm). Most of the enriched trace elements, based on both the chemical analyses of separated heavy and light mineral fractions and a two step sequential extraction procedure, are associated with an operationally defined Fe oxide phase; much smaller percentages are associated either with operationally defined organics/sulphides or refractory phases.The presence, concentration and distribution of the Fe oxides and heavy minerals indicates that a substantial portion of the enriched trace elements are probably coming from the Coeur d'Alene River, which is serving as a point source. Within the lake, this relatively simple point source pattern is complicated by a combination of (1) the formation of trace element rich authigenic Fe oxides that appear to have reprecipitated from material solubilized from anoxic bed sediments and (2) physical remobilization by currents and wind driven waves. The processes that have caused the trace element enrichment in the surface sediments of Lake Coeur d'Alene are likely to continue for the foreseeable future.

Exploiting LSPIV to assess debris-flow velocities in the field

NASA Astrophysics Data System (ADS)

Theule, Joshua I.; Crema, Stefano; Marchi, Lorenzo; Cavalli, Marco; Comiti, Francesco

2018-01-01

The assessment of flow velocity has a central role in quantitative analysis of debris flows, both for the characterization of the phenomenology of these processes and for the assessment of related hazards. Large-scale particle image velocimetry (LSPIV) can contribute to the assessment of surface velocity of debris flows, provided that the specific features of these processes (e.g. fast stage variations and particles up to boulder size on the flow surface) are taken into account. Three debris-flow events, each of them consisting of several surges featuring different sediment concentrations, flow stages, and velocities, have been analysed at the inlet of a sediment trap in a stream in the eastern Italian Alps (Gadria Creek). Free software has been employed for preliminary treatment (orthorectification and format conversion) of video-recorded images as well as for LSPIV application. Results show that LSPIV velocities are consistent with manual measurements of the orthorectified imagery and with front velocity measured from the hydrographs in a channel recorded approximately 70 m upstream of the sediment trap. Horizontal turbulence, computed as the standard deviation of the flow directions at a given cross section for a given surge, proved to be correlated with surface velocity and with visually estimated sediment concentration. The study demonstrates the effectiveness of LSPIV in the assessment of surface velocity of debris flows and permit the most crucial aspects to be identified in order to improve the accuracy of debris-flow velocity measurements.

Pushpoint sampling for defining spatial and temporal variations in contaminant concentrations in sediment pore water near the ground-water / surface-water interface

USGS Publications Warehouse

Zimmerman, Marc J.; Massey, Andrew J.; Campo, Kimberly W.

2005-01-01

During four periods from April 2002 to June 2003, pore-water samples were taken from river sediment within a gaining reach (Mill Pond) of the Sudbury River in Ashland, Massachusetts, with a temporary pushpoint sampler to determine whether this device is an effective tool for measuring small-scale spatial variations in concentrations of volatile organic compounds and selected field parameters (specific conductance and dissolved oxygen concentration). The pore waters sampled were within a subsurface plume of volatile organic compounds extending from the nearby Nyanza Chemical Waste Dump Superfund site to the river. Samples were collected from depths of 10, 30, and 60 centimeters below the sediment surface along two 10-meter-long, parallel transects extending into the river. Twenty-five volatile organic compounds were detected at concentrations ranging from less than 1 microgram per liter to hundreds of micrograms per liter (for example, 1,2-dichlorobenzene, 490 micrograms per liter; cis-1,2-dichloroethene, 290 micrograms per liter). The most frequently detected compounds were either chlorobenzenes or chlorinated ethenes. Many of the compounds were detected only infrequently. Quality-control sampling indicated a low incidence of trace concentrations of contaminants. Additional samples collected with passive-water-diffusion-bag samplers yielded results comparable to those collected with the pushpoint sampler and to samples collected in previous studies at the site. The results demonstrate that the pushpoint sampler can yield distinct samples from sites in close proximity; in this case, sampling sites were 1 meter apart horizontally and 20 or 30 centimeters apart vertically. Moreover, the pushpoint sampler was able to draw pore water when inserted to depths as shallow as 10 centimeters below the sediment surface without entraining surface water. The simplicity of collecting numerous samples in a short time period (routinely, 20 to 30 per day) validates the use of a pushpoint sampler as a highly effective tool for mapping the extent of contaminated subsurface plumes, determining their constituents and loadings, and performing technical studies that may be relevant to bioremediation and other activities.

Nitrate consumption in sediments of the German Bight (North Sea)

NASA Astrophysics Data System (ADS)

Neumann, Andreas; van Beusekom, Justus E. E.; Holtappels, Moritz; Emeis, Kay-Christian

2017-09-01

Denitrification on continental margins and in coastal sediments is a major sink of reactive N in the present nitrogen cycle and a major ecosystem service of eutrophied coastal waters. We analyzed the nitrate removal in surface sediments of the Elbe estuary, Wadden Sea, and adjacent German Bight (SE North Sea) during two seasons (spring and summer) along a eutrophication gradient ranging from a high riverine nitrate concentrations at the Elbe Estuary to offshore areas with low nitrate concentrations. The gradient encompassed the full range of sediment types and organic carbon concentrations of the southern North Sea. Based on nitrate penetration depth and concentration gradient in the porewater we estimated benthic nitrate consumption rates assuming either diffusive transport in cohesive sediments or advective transport in permeable sediments. For the latter we derived a mechanistic model of porewater flow. During the peak nitrate discharge of the river Elbe in March, the highest rates of diffusive nitrate uptake were observed in muddy sediments (up to 2.8 mmol m- 2 d- 1). The highest advective uptake rate in that period was observed in permeable sediment and was tenfold higher (up to 32 mmol m- 2 d- 1). The intensity of both diffusive and advective nitrate consumption dropped with the nitrate availability and thus decreased from the Elbe estuary towards offshore stations, and were further decreased during late summer (minimum nitrate discharge) compared to late winter (maximum nitrate discharge). In summary, our rate measurements indicate that the permeable sediment accounts for up to 90% of the total benthic reactive nitrogen consumption in the study area due to the high efficiency of advective nitrate transport into permeable sediment. Extrapolating the averaged nitrate consumption of different sediment classes to the areas of Elbe Estuary, Wadden Sea and eastern German Bight amounts to an N-loss of 3.1 ∗ 106 mol N d- 1 from impermeable, diffusion-controlled sediment, and 5.2 ∗ 107 mol N d- 1 from permeable sediment with porewater advection.

Assessment of concentrated flow through riparian buffers

Treesearch

M.G. Dosskey; M.J. Helmers; D.E. Eisenhauer; T.G. Franti; K.D. Hoagland

2002-01-01

Concentrated flow of surface runoff from agricultural fields may limit the capability of riparian buffers to remove pollutants. This study was conducted on four farms in southeastern Nebraska to develop a method for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that it has on sediment-trapping efficiency. Field methods...

Nutrients and sediment in frozen-ground runoff from no-till fields receiving liquid-dairy and solid-beef manures

USGS Publications Warehouse

Komiskey, Matthew J.; Stuntebeck, Todd D.; Frame, Dennis R.; Madison, Fred W.

2011-01-01

Nutrients and sediment in surface runoff from frozen agricultural fields were monitored within three small (16.0 ha [39.5 ac] or less), adjacent basins at a no-till farm in southwest Wisconsin during four winters from 2003 to 2004 through 2006 to 2007. Runoff depths and flow-weighted constituent concentrations were compared to determine the impacts of surface-applied liquid-dairy or solid-beef manure to frozen and/or snow-covered ground. Despite varying the manure type and the rate and timing of applications, runoff depths were not significantly different among basins within each winter period. Sediment losses were low (generally less than 22 kg ha−1 [20 lb ac−1] in any year) and any statistical differences in sediment concentrations among basins were not related to the presence or absence of manure or the amount of runoff. Concentrations and losses of total nitrogen and total phosphorus were significantly increased in basins that had either manure type applied less than one week preceding runoff. These increases occurred despite relatively low application rates. Lower concentrations and losses were measured in basins that had manure applied in fall and early winter and an extended period of time (months) had elapsed before the first runoff event. The highest mean, flow-weighted concentrations of total nitrogen (31.8 mg L−1) and total phosphorus (10.9 mg L−1) occurred in winter 2003 to 2004, when liquid-dairy manure was applied less than one week before runoff. On average, dissolved phosphorus accounted for over 80% of all phosphorus measured in runoff during frozen-ground periods. The data collected as part of this study add to the limited information on the quantity and quality of frozen-ground runoff at field edges, and the results highlight the importance of manure management decisions during frozen-ground periods to minimize nutrients lost in surface runoff.

Polycyclic aromatic and aliphatic hydrocarbons in Chukchi Sea biota and sediments and their toxicological response in the Arctic cod, Boreogadus saida

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger; Taylor, Karen A.; Pie, Hannah V.; Mitchelmore, Carys L.

2014-04-01

As part of the Chukchi Sea Offshore Monitoring in Drilling Area-Chemical and Benthos (COMIDA CAB) project, we determined the distribution and concentrations of aliphatic n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in surface sediments (0-1 cm) among 52 sites across the Chukchi Sea and in muscle tissues of the benthic Northern whelk, Neptunea heros, collected opportunistically. In addition, downcore profiles of contaminants were determined at three targeted sites to establish historic patterns. Baseline responses of PAH exposure and its potential toxicological effects were examined in the common Arctic cod, Boreogadus saida, through measures of cytochrome P4501A/ ethoxyresorufin O-deethylase (CYP1A/EROD), glutathione-S-transferase (GST), and Cu/Zn superoxide dismutase (SOD) activity in liver tissue. The total concentration of PAHs in surface sediments throughout the study area, including parent and alkyl-homologs, were very low (<1600 ng g-1 dry wt) except for a single station, where values were 2-20-fold greater than at other baseline sites (2956 ng g-1 dry wt). Alkyl-substituted PAHs were the dominant form in all surface (54-93%) and subsurface sediments (50-81% of the total), with a general decrease in total PAH concentrations observed downcore. In biota, larger Neptunea showed lower total concentrations of PAHs in foot muscles (4.5-10.7 ng g-1 wet wt) compared to smaller animals; yet aliphatic n-alkane (C19-C33) concentrations (0.655-5.20 μg g-1 wet wt) increased in larger organisms with distributions dominated by long-chain (C23-C33) hydrocarbons. In B. saida, CYP1A1, GST, and SOD enzyme levels were comparable to baseline levels previously reported in other pristine systems. Of the three assays, only SOD had a significant correlation between gene expression and enzyme activity.

Steroid markers to assess sewage and other sources of organic contaminants in surface sediments of Cienfuegos Bay, Cuba.

PubMed

Tolosa, I; Mesa, M; Alonso-Hernandez, C M

2014-09-15

Analyses of faecal steroids in coastal sediments from Cienfuegos Bay Cuba indicate chronic sewage contamination at the main outfalls from the city, where concentrations of coprostanol up to 5400ngg(-)(1) (dry wt) were measured. In contrast, steroid concentrations and compositions from sites from the south part of the Bay are characteristic of uncontaminated sewage environments. The levels of coprostanol in the Cienfuegos sediments compares to the lower to mid-range of concentrations reported for coastal sediments on a world-wide basis, with sedimentary levels markedly below those previously reported for heavily impacted sites. This study delivers baseline data for further investigation of the effectiveness of the proposed sewerage plan promoted by the GEF project in Cienfuegos. Investigations on the correlations between faecal steroids and other organic contaminants confirmed that the major source of petroleum hydrocarbons within the bay was associated with the sewage effluents from the Cienfuegos city. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater

USGS Publications Warehouse

Kent, D.B.; Davis, J.A.; Joye, J.L.; Curtis, G.P.

2008-01-01

Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation.

Surface-water-quality assessment of the Upper Illinois River basin in Illinois, Indiana, and Wisconsin; cross-sectional and depth variation of water-quality constituents and properties in the Upper Illinois River basin, 1987-88

USGS Publications Warehouse

Marron, Donna C.; Blanchard, Stephen F.

1995-01-01

Data on water velocity, temperature, specific con- ductance, pH, dissolved oxygen concentration, chlorophyll concentration, suspended sediment con- centration, fecal-coliform counts, and the percen- tage of suspended sediment finer than 62 micrometers ranged up to 21 percent; and cross-section coefficients of variation of the concentrations of suspended sediment, fecal coliform, and chlorophyll ranged from 7 to 115 percent. Midchannel measure- ments of temperature, specific conductance, and pH were within 5 percent of mean cross-sectional values of these properties at the eight sampling sites, most of which appear well mixed because of the effect of dams and reservoirs. Measurements of the concentration of dissolved oxygen at various cross- section locations and at variable sampling depths are required to obtain a representative value of this constituent at these sites. The large varia- bility of concentrations of chlorophyll and suspended sediment, and fecal-coliform counts at the eight sampling sites indicates that composite rather than midchannel or mean values of these constituents are likely to be most representative of the channel cross section.

Distribution and bioaccumulation of endocrine disrupting chemicals in water, sediment and fishes in a shallow Chinese freshwater lake: Implications for ecological and human health risks.

PubMed

Dan Liu; Wu, Shengmin; Xu, Huaizhou; Zhang, Qin; Zhang, Shenghu; Shi, Lili; Yao, Cheng; Liu, Yanhua; Cheng, Jie

2017-06-01

The occurrence, distribution and bioaccumulation of six endocrine disrupting compounds (EDCs) were investigated in water, sediment and biota samples from Luoma Lake, a shallow Chinese freshwater lake. Total concentrations of ∑phenolic EDCs were much higher than ∑estrogens EDCs in both waters and sediments. There were not obvious differences on the concentrations of target compounds [except nonylphenol (NP)] in upstream, lake and downstream locations, these may be suggested that they were mainly affected by non-point discharges in this area. However, the high concentration of NP in water may be associated with the discharge of rural domestic wastewater without thorough treatment. Furthermore, concentrations of NP were about 2-3 order magnitude higher than those of OP in both water and sediment compartments. Relatively higher bioaccumulation factors (BAF) were obtained for DES and EE2. Ecological risk assessment revealed greater risk of NP in surface water, which may pose a serious threat to aquatic ecosystems. The estrogen equivalent concentration (EEQ) of male were higher than those in female, and occurred in the order of city >rural-urban>countryside. Copyright © 2017 Elsevier Inc. All rights reserved.

Data on surface-water, streambed-interstitial water, and bed-sediment quality for selected locations in the small arms impact area of central Fort Gordon, Georgia, September 4-6, 2001

USGS Publications Warehouse

Priest, Sheryln; Stamey, Timothy C.; Lawrence, Stephen J.

2002-01-01

In September 2001, the U.S. Geological Survey, in cooperation with the Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon (U.S. Department of the Army), conducted a chemical assessment of surface water, streambed-interstitial water, and bed sediments within the small arms impact area of Fort Gordon Military Installation. The study was conducted in support of the development of an Integrated Natural Resources Management Plan (INRMP) for Fort Gordon, Georgia. An effective INRMP ensures that natural resources conservation measures and U.S. Army activities on the military base are integrated and consistent with Federal requirements to manage military installations on an ecosystem basis. Filtered water samples were collected from five sites along South Prong Creek and three sites along Marcum Branch Creek for chemical analyses of major ions, nutrients, and selected trace elements. On-site measurements of pH, temperature, specific conductance, and dissolved oxygen were made at the eight sites. Filtered water collected showed varying concentrations in both surface- and streambed-interstitial water. Bed-sediment samples collected from South Prong Creek contain elevated levels of arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, selenium, vanadium, and total organic carbon relative to previous concentrations (McConnell and others, 2000). Bed-sediment samples collected from Marcum Branch Creek contain elevated levels of beryllium, copper, lead, manganese, mercury, selenium, and total organic carbon relative to previous concentrations (McConnell and others, 2000).

Can ipids in lake sediments help to reconstruct changes in methane availability and methane fluxes in boreal and temperate lakes?

NASA Astrophysics Data System (ADS)

Stoetter, T.; van Hardenbroek, M.; Rinta, P.; Schilder, J.; Schubert, C. J.; Heiri, O.

2013-12-01

Methane (CH4) is a major greenhouse gas and lakes are an important but poorly studied source of CH4 to the atmosphere. Lipid analysis was used before to identify and quantify CH4 oxidizing bacteria (MOB), giving insight into CH4 oxidation and production in lakes. However, few studies are available that examine how closely the distribution and the carbon isotopic signature (δ13C) of lipids are related to CH4 concentrations and fluxes in different lake ecosystems. In a multi-lake survey we quantified the relationship between lipids, mainly fatty acids (FAs), and CH4 concentrations or fluxes, with the aim of assessing whether FA analysis of lake sediment samples can provide information on past CH4 abundance and production in lakes. The study sites include small lakes in Sweden, Finland, the Netherlands, and Switzerland. Surface sediments collected in the deepest point of the lakes were examined using gas chromatography with flame ionization for determining FA concentrations, gas chromatography mass spectrometry (GC-MS) for identification of individual FAs, and isotope ratio mass spectrometry (IRMS) for determining compound specific δ13C values. Since CH4 is significantly more depleted in 13C than other carbon sources, δ13C is a good tracer for CH4 related processes. The analysis of the acid fraction in the sediments showed that mainly three FAs, identified as C16:1ω7, C16:1ω5 and C18:1ω7, were more depleted in 13C than the others, suggesting that they may originate from MOB. Comparison with literature sources indicated that these FAs are produced by MOB, however, not exclusively. The relative abundance of these depleted FAs showed clear relations to CH4 parameters. For example, increasing abundances were observed with increasing CH4 concentrations in the sediment or with increasing CH4 flux measured at the lake surface. An explanation for these relations would be an increase in MOB biomass with increasing CH4 availability, as they use CH4 as energy and carbon source, which would lead to increasing abundances of MOB produced FAs in the sediment. The presence or absence of oxygen above the sediments seems to have a strong effect on these relationships. In lakes with oxic bottom water, the abundance of depleted FAs shows a stronger rise with increasing CH4 concentrations than in lakes with anoxic bottom waters, suggesting that aerobic CH4 oxidizers are an important source of these depleted FAs. With increasing CH4 concentrations, for example just above the sediment, we find more depleted values in C16:1ω7 and C18:1ω7. This correlation is only strong if we exclude lakes with a strong terrestrial influence. Our preliminary analysis of FAs in surface sediment samples showed clear relations to CH4 parameters measured in the examined lake ecosystems suggesting that it may be possible to use FA analysis of lake sediment records as a proxy for CH4 availability in lakes. However, our results also show that oxygen conditions at the sediment-water interface and organic matter imported from the lake catchment can have a strong effect.

Relative importance of methylotrophic methanogenesis in sediments of the Western Mediterranean Sea

NASA Astrophysics Data System (ADS)

Zhuang, Guang-Chao; Heuer, Verena B.; Lazar, Cassandre S.; Goldhammer, Tobias; Wendt, Jenny; Samarkin, Vladimir A.; Elvert, Marcus; Teske, Andreas P.; Joye, Samantha B.; Hinrichs, Kai-Uwe

2018-03-01

Microbial production of methane is an important terminal metabolic process during organic matter degradation in marine sediments. It is generally acknowledged that hydrogenotrophic and acetoclastic methanogenesis constitute the dominant pathways of methane production; the importance of methanogenesis from methylated compounds remains poorly understood. We conducted various biogeochemical and molecular genetic analyses to characterize substrate availability, rates of methanogenesis, and methanogen community composition, and further evaluated the contribution of different substrates and pathways for methane production in deltaic surface and subsurface sediments of the Western Mediterranean Sea. Major substrates representing three methanogenic pathways, including H2, acetate, and methanol, trimethylamine (TMA), and dimethylsulfide (DMS), were detected in the pore waters and sediments, and exhibited variability over depth and between sites. In accompanying incubation experiments, methanogenesis rates from various 14C labeled substrates varied as well, suggesting that environmental factors, such as sulfate concentration and organic matter quality, could significantly influence the relative importance of individual pathway. In particular, methylotrophic and hydrogenotrophic methanogenesis contributed to the presence of micromolar methane concentrations in the sulfate reduction zone, with methanogenesis from methanol accounting for up to 98% of the total methane production in the topmost surface sediment. In the sulfate-depleted zone, hydrogenotrophic methanogenesis was the dominant methanogenic pathway (67-98%), and enhanced methane production from acetate was observed in organic-rich sediment (up to 31%). Methyl coenzyme M reductase gene (mcrA) analysis revealed that the composition of methanogenic communities was generally consistent with the distribution of methanogenic activity from different substrates. This study provides the first quantitative assessment of methylotrophic methanogenesis in marine sediments and has important implications for marine methane cycling. The occurrence of methylotrophic methanogenesis in surface sediments could fuel the anaerobic oxidation of methane (AOM) in the shallow sulfate reduction zone. Release of methane produced from methylotrophic methanogenesis could be a source of methane efflux to the water column, thus influencing the benthic methane budgets.

Microbial cycling of mercury in contaminated pelagic and wetland sediments of San Pablo Bay, California

USGS Publications Warehouse

Marvin-DiPasquale, M. C.; Agee, J.L.; Bouse, R.M.; Jaffe, B.E.

2003-01-01

San Pablo Bay is an estuary, within northern San Francisco Bay, containing elevated sediment mercury (Hg) levels because of historic loading of hydraulic mining debris during the California gold-rush of the late 1800s. A preliminary investigation of benthic microbial Hg cycling was conducted in surface sediment (0-4 cm) collected from one salt-marsh and three open-water sites. A deeper profile (0-26 cm) was evaluated at one of the open-water locations. Radiolabeled model Hg-compounds were used to measure rates of both methylmercury (MeHg) production and degradation by bacteria. While all sites and depths had similar total-Hg concentrations (0.3-0.6 ppm), and geochemical signatures of mining debris (as eNd, range: -3.08 to -4.37), in-situ MeHg was highest in the marsh (5.4??3.5 ppb) and ??? 0.7 ppb in all open-water sites. Microbial MeHg production (potential rate) in 0-4 surface sediments was also highest in the marsh (3.1 ng g-1 wet sediment day-1) and below detection (<0.06 ng g-1 wet sediment day-1) in open-water locations. The marsh exhibited a methylation/demethylation (M/D) ratio more than 25x that of all open-water locations. Only below the surface 0-4-cm horizon was significant MeHg production potential evident in the open-water sediment profile (0.2-1.1 ng g-1 wet sediment day-1). In-situ Hg methylation rates, calculated from radiotracer rate constants, and in-situ inorganic Hg(II) concentrations compared well with potential rates. However, similarly calculated in-situ rates of MeHg degradation were much lower than potential rates. These preliminary data indicate that wetlands surrounding San Pablo Bay represent important zones of MeHg production, more so than similarly Hg-contaminated adjacent open-water areas. This has significant implications for this and other Hg-impacted systems, where wetland expansion is currently planned.

Changing sources of polychlorinated dibenzo-p-dioxins and furans in sediments and ecological risk for nekton in the lower Passaic River and Newark Bay, New Jersey, USA.

PubMed

Khairy, Mohammed; Barrett, Kirk; Lohmann, Rainer

2016-03-01

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in sediments (surface and deeper sediments) and porewater of the lower Passaic River and Newark Bay (New Jersey, USA) to apportion their sources and conduct an ecological risk assessment. Positive matrix factorization was applied to identify sources of PCDD/Fs. Five source profiles were extracted from the positive matrix factorization model applied to the sediment samples including chloranil, combustion, polychlorinated biphenyl impurities, mixed urban sources, and the historical contamination from the former Diamond Alkali plant. The ecological risk assessment was estimated using several lines of evidence depending on site-specific data (blue crab and fish samples representing different feeding habits and positions in the trophic wood web of the river). Porewater concentrations gave the best estimates of lipid concentrations especially in the blue crab samples (with an average factor difference of 3.8). Calculated hazard quotients (HQs) for the fish samples and blue crab were >1 based on the no-effect concentration and tissue screening concentration approaches. At the same time, calculated porewater toxic units were >1. Sediment concentrations exceeded the published sediment quality guidelines for the protection of fish and benthic species, indicating the existence of significant risk to the aquatic life in the Passaic River. Accordingly, further actions and control measures are needed to reduce the emission of PCDD/Fs from ongoing sources. © 2015 SETAC.

Migration of two antibiotics during resuspension under simulated wind-wave disturbances in a water-sediment system.

PubMed

Li, Shu; Huang, Zheng; Wang, Yi; Liu, Yu-Qing; Luo, Ran; Shang, Jing-Ge; Liao, Qian-Jia-Hua

2018-02-01

In this study, the migration of antibiotics (norfloxacin, NOR; and sulfamethoxazole, SMX) under simulated resuspension conditions across the sediment-water interface were quantified for two locations in China: point A, located in Meiliang Bay of Lake Taihu, and point B, located in Dapukou of Lake Taihu. The concentrations of suspended solids (SS) in the overlying water amounted to 100, 500, and 1000 mg/L during background, moderate, and strong simulated wind-wave disturbances, respectively. At each SS level, the initial concentrations of the two antibiotics were set to 1, 5, and 10 mg/L. The results showed that both resuspended SS and the initial concentration of antibiotics could influence the migration of NOR in the water-sediment system. Specifically, both higher SS and initial antibiotic concentrations were associated with higher rates of migration and accumulation of NOR from water to sediment. In contrast, the migration of SMX in the water-sediment system was not impacted by SS or initial antibiotic concentration. The adsorption capacities of sediments for NOR and SMX were significantly different at both locations, possibly reflecting differences in cation exchange capacity (CEC) and organic material (OM) contents. In general, higher CEC and OM values were found in sediments with a higher adsorption capacity for the antibiotics. When CEC and OM values of sediments were higher, the adsorption capacity reached up to 51.73 mg/kg. Large differences in the migration from water to sediment were observed for the two antibiotics, with NOR migration rates higher than those of SMX. The accumulation of NOR in surface sediment during resuspension was about 14 times higher than that of SMX. The main reason for this is that the chemical adsorption of NOR is seldom reversible. Overall, this study demonstrates that resuspension of NOR and SMX attached to sediments under simulated wind-wave disturbances can promote the migration of the antibiotics from water to sediment; these results could be useful for assessing the migration and fate of commonly used antibiotics in water-sediment systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Heavy metal contamination and ecological risk assessment in the surface sediments of the coastal area surrounding the industrial complex of Gabes city, Gulf of Gabes, SE Tunisia.

PubMed

El Zrelli, Radhouan; Courjault-Radé, Pierre; Rabaoui, Lotfi; Castet, Sylvie; Michel, Sylvain; Bejaoui, Nejla

2015-12-30

In the present study, the concentrations of 6 trace metals (Hg, Cd, Cu, Pb, Cr and Zn) were assessed in the surface sediments of the central coastal area of Gabes Gulf to determine their contamination status, source, spatial distribution and ecological risks. The ranking of metal contents was found to be Zn>Cd>Cr>Pb>Cu>Hg. Correlation analysis indicated that Cd and Zn derived mainly from the Tunisian Chemical Group phosphogypsum. The other pollutants may originate from other industrial wastes. Metallic contamination was detected in the south of chemical complex, especially in the inter-harbor zone, where the ecological risk of surface sediments is the highest, implying potential negative impacts of industrial pollutants. The spatial distribution of pollutants seems to be due to the effect of harbor installations and coastal currents. The metallic pollution status of surface sediments of Gabes Gulf is obvious, very worrying and requires rapid intervention. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treated and untreated wastewater effluents alter river sediment bacterial communities involved in nitrogen and sulphur cycling.

PubMed

Martínez-Santos, Miren; Lanzén, Anders; Unda-Calvo, Jessica; Martín, Iker; Garbisu, Carlos; Ruiz-Romera, Estilita

2018-08-15

Studying the dynamics of nitrogen and sulphur cycling bacteria in river surface sediments is essential to better understand their contribution to global biogeochemical cycles. Evaporitic rocks settled at the headwater of the Deba River catchment (northern Spain) lead to high values of sulphate concentration in its waters. Besides, the discharge of effluents from untreated and treated residual (urban and industrial) wastewaters increases the concentration of metals, nutrients and organic compounds in its mid- and low-water courses. The aim of this study was to assess the impact of anthropogenic contamination from untreated and treated residual and industrial wastewaters on the structure and function of bacterial communities present in surface sediments of the Deba River catchment. The application of a quantitative functional approach (qPCR) based on denitrification genes (nir: nirS+nirK; and nosZ), together with a 16S rRNA gene metabarcoding structural analysis, revealed (i) the high relevance of the sulphur cycle at headwater surface sediments (as reflected by the abundance of members of the Syntrophobacterales order, and the Sulfuricurvum and Thiobacillus genera) and (ii) the predominance of sulphide-driven autotrophic denitrification over heterotrophic denitrification. Incomplete heterotrophic denitrification appeared to be predominant in surface sediments strongly impacted by treated and untreated effluents, as reflected by the lower values of the nosZ/nir ratio, thus favouring N 2 O emissions. Understanding nitrogen and sulphur cycling pathways has profound implications for the management of river ecosystems, since this knowledge can help us determine whether a specific river is acting or not as a source of greenhouse gases (i.e., N 2 O). Copyright © 2018 Elsevier B.V. All rights reserved.

A statistical experiment design approach for optimizing biodegradation of weathered crude oil in coastal sediments.

PubMed

Mohajeri, Leila; Aziz, Hamidi Abdul; Isa, Mohamed Hasnain; Zahed, Mohammad Ali

2010-02-01

This work studied the bioremediation of weathered crude oil (WCO) in coastal sediment samples using central composite face centered design (CCFD) under response surface methodology (RSM). Initial oil concentration, biomass, nitrogen and phosphorus concentrations were used as independent variables (factors) and oil removal as dependent variable (response) in a 60 days trial. A statistically significant model for WCO removal was obtained. The coefficient of determination (R(2)=0.9732) and probability value (P<0.0001) demonstrated significance for the regression model. Numerical optimization based on desirability function were carried out for initial oil concentration of 2, 16 and 30 g per kg sediment and 83.13, 78.06 and 69.92 per cent removal were observed respectively, compare to 77.13, 74.17 and 69.87 per cent removal for un-optimized results.

Trend and dynamic cause of sediment particle size on the adjacent continental shelf of the Yangtze Estuary

NASA Astrophysics Data System (ADS)

Yang, Yun-ping; Zhang, Ming-jin; Li, Yi-tian; Fan, Yong-yang

2016-12-01

Based on the measured data in recent 20 years, the variation trends of the median grain size of the surface sediment, the sand-silt boundary and the mud area on the adjacent continental shelf of the Yangtze Estuary were analyzed in depth, and the effects of natural mechanism and human activities were discussed. The results show that: (1) In recent years (2006-2013), the median grain size of sediment and the distribution pattern of grouped sediments in the adjacent continental shelf area to the Yangtze Estuary have presented no obvious change compared with those before 2006; (2) The median diameter of the surface sediment in the continental shelf area displayed a coarsening trend with the decrease of sediment discharge from the basin and the drop in suspended sediment concentration in the shore area; (3) In 2004-2007, the sand-silt boundary in the north part (31°30'N) of the continental shelf area presented no significant changes, while that in the south part (31°30'S) moved inwards; In 2008-2013, both the sand-silt boundaries in the north and south parts of the continental shelf area moved inwards, mainly due to the fact that in the dry season, a relatively enhanced hydrodynamic force of the tides was generated in the Yangtze River, as well as a decreased suspended sediment concentration and a flow along the banks in North Jiangsu; (4) The mud area where the maximum deposition rate is found in the Yangtze Estuary, tends to shrink due to the drop in sediment discharge from the basin, and the decrease in suspended sediment concentration in the shore area and erosion in the delta. Moreover, it tended to shift to the south at the same time because the implement of the training works on the deep-water channel of the North Passage changed the split ratio between the North and South Passages with an increase in the power of the discharged runoff in the South Passage.

Building Towards a Conceptual Model for Phosphorus Transport in Lowland Catchments

NASA Astrophysics Data System (ADS)

van der Grift, B.; Griffioen, J.; Oste, L.

2016-12-01

The release of P to surface water following P leaching from heavily fertilized agricultural fields to groundwater and the extent of P retention at the redox interphase are of major importance for surface water quality. We studied the role of biogeochemical and hydrological processes during exfiltration of groundwater and their impact on phosphorus transport in lowland catchments in the Netherlands. Our study showed that the mobility and ecological impact of P in surface waters in lowland catchments or polders like in the Netherlands is strongly controlled by the exfiltration of anoxic groundwater containing ferrous iron. Chemical precipitates derived from groundwater-associated Fe(II) seeping into the overlying surface water contribute to immobilization of dissolved phosphate and, therefore, reduces its bioavailability. Aeration experiments with Fe(II) and phosphate-containing synthetic solutions and natural groundwater showed that Fe(II) oxidation in presence of phosphate leads initially to formation of Fe(III) hydroxyphosphates precipitates until phosphate is near-depleted from solution. A field campaign on P specation in surface waters draining agricultural land showed, additionally, that the total-P concentration is strongly dominated by iron-bound. Between 75 and 95% of the total-P concentration in the water samples was iron-bound particulate P. After the turnover of dissolved P to iron-bound particulate P, the P transport in catchments or polders is controlled by sedimentation and erosion of suspended sediments in the water body. Shear flow-induced surface erosion of sediment beds upon natural discharge events or generated by pumping stations is thus an important mechanism for P transport in catchments or polders. The flow velocities in headwaters like drainage ditches are generally low and not high enough to cause a bed shear stress that exceed the critical shear stress. Transport of particulate P that originates from groundwater and (agricultural) drains discharge is strongly retained but particulate P can be remobilized due to biogeochemical processes in the sediment layer at other moments. This makes it difficult to link agricultural practice to P concentrations in the surface water and this should be accounted for when judging measures to reduce P loads from agriculture.