Polychlorinated biphenyl contamination trends in Lake Hartwell, South Carolina (USA): sediment recovery profiles spanning two decades.
ABSTRACT To assess the ca. 20-year polychlorinated biphenyl (PCB) contamination trends in Lake Hartwell, SC, sediment cores from the Twelve Mile Creek arm were collected in July 2004 at two sites (G30 and G33) first sampled in the mid-1980s. Congener-specific PCB data as a function of depth from the sediment-water interface for the 2004 sediment samples were compared to data obtained from 1987 and 1998 samples taken from the same locations. Despite modest decreases in total PCB levels near the G30 sediment-water interface, historical increases in average degrees of chlorination may elevate the overall toxic risk at this site. Unlike G30, the more rapid recovery in the near-surface sediment of G33 suggests that the effectiveness of the U.S. EPA natural attenuation record of decision is site-specific and is unlikely to result in uniform surface sediment recovery throughout the most contaminated regions of Lake Hartwell.
Full-textDOI: · Available from: Cindy Lee, May 08, 2015
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ABSTRACT: Twenty-eight polychlorinated biphenyls (PCB) congeners were measured in surface sediments from Chaohu Lake to assess their characteristics, potential risk, and the correlation with lake trophic status. PCB levels ranged from 11.074 to 42.712 ng g−1 dry weight (d.w.) in the western lake and 2.017 to 20.189 ng g−1 d.w. in the eastern lake. The highest concentrations were found at the sites near the inlets of western lake tributary rivers where big cities and industrial centers are located. Congeners concentrations showed decreasing order of tetra-CB > tri-CB > deca-CB (PCB-209 detected) > penta-CB > hexa-CB > di-CB > hepta-CB > Octa-CB. It indicated that light and heavy Aroclor mixtures were simultaneously used surrounding the lake basin. PCB levels in the western lake are potentially dangerous to humans and the local fauna. There was a significant positive relationship between tetra-CB (one abundant PCB congener) concentration distribution and sediment grain size in the 16–64 μm fraction, whereas a negative correlation was found in the 4–8 μm fraction. Furthermore, PCB distributions were positively correlated with the total organic carbon of sediments and lake trophic status, especially in the more seriously polluted western lake zone. However, the correlation completely disappeared in eastern lake zone. It suggested that PCB contamination might be attributed to industrial wastewaters and domestic sewages from western lake basin, reaching the lake through rivers, rains and floods.Environmental earth sciences 01/2013; 71(2). DOI:10.1007/s12665-013-2487-8 · 1.57 Impact Factor
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ABSTRACT: Concentrations, temporal trends and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs) were determined in soil and (210)Pb-dated sediment cores from remote lacustrine environments (El Tule and Santa Elena lakes) in rural areas of Central Mexico. In both areas, the concentrations of target analytes in soil and sediment samples were comparable and indicative of slightly contaminated environments. The prevalence of low-molecular-weight PAHs in soils suggested their mainly atmospheric origin, in contrast to the aquatic sediments where runoff contribution was also significant. Increasing contamination trends of PCBs and PBDEs were evident, showing maximum fluxes of 4.8±2.1 and 0.3±0.1ngcm(-2)a(-1) for PCBs and PBDEs, respectively. The predominance of lower-brominated PBDEs and lower-chlorinated PCBs in soils and sediments indicated that their presence is mostly due to long-range atmospheric transport.Science of The Total Environment 06/2014; 493C:505-520. DOI:10.1016/j.scitotenv.2014.05.002 · 3.16 Impact Factor
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ABSTRACT: The U.S. Department of Energy Portsmouth Gaseous Diffusion Plant is in the early stages of decommissioning and decontamination. During operations, the site drew a large amount of electric power and had multiple large switchyards on site. These are a source of polychlorinated biphenyls (PCB) contamination to both on-site and off-site streams. Some soil remediation has been completed in the main switchyard. During 2011 and 2012, fifteen sites were sampled at the surface (<10 cm) and subsurface (20–30 cm) to characterize the extent of PCB contamination, to identify weathering and migration of PCB contamination and to explore potential polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) contamination due to transformer fires and explosions in the 1950s and 1960s. Stagnant sites tended to exhibit more migration of contamination to deeper sediments than sites with fast-moving waters, and the highest concentrations were found at the bottom of a settling pond. A signature set of five dioxin-like PCBs were consistently found across the site with higher concentrations in carbon rich surface sediments. PCB concentrations had a significant inverse correlation with clay content, suggesting that PCBs did not bind to clays at this site. Remediation has reduced PCB concentrations throughout the site compared to levels found in previous studies and long-term upkeep of sediment lagoons is necessary to retain PCB and dioxin-rich sediments. The flow regimen, organic carbon and clay content play a very important role in the fate of PCBs in the environment at the surface as well as downward migration.Chemosphere 11/2014; 114:93–100. DOI:10.1016/j.chemosphere.2014.03.092 · 3.50 Impact Factor