Historical Changes in Polychlorinated Biphenyls Contaminated Sediments
Viet D. Dang, David M. Walters and Cindy M. Lee
DOI : 10.3844/ajessp.2012.11.15
American Journal of Environmental Sciences
Volume 8, Issue 1
Problem statement: PCBs contamination continues to pose a health risk to aquatic environments due to their recalcitrance and bioaccumulation. The Sangamo Weston/Twelvemile Creek/Lake Hartwell Superfund Site is an example of such a health risk as a result of PCBs discharged from a former capacitor manufacturing plant. We conducted a study in twelvemile creek (Clemson, SC, USA) to examine the temporal trend of PCB contaminated sediments. Approach: Surface sediments were sampled at four sites in fall 2008 to compare with concentrations measured in past studies. Total PCBs and congener-specific analyses were performed on Gas Chromatography-Electron Capture Detector (GC-ECD). Results: Total PCB concentrations ranged from 0.026-0.18 μg g-1, which were one order of magnitude lower than levels measured in 1987 (<0.20-10.23 μg g-1). Total PCBs in this study (based on more than 130 congeners) were similar to those observed in 2003-2004 (based on only 20 congeners). PCB congener patterns indicated that PCBs near the source were dominated by lower chlorinated congeners while heavy congeners were persistent further downstream. Conclusion: Physical and biochemical processes such as natural attenuation, mixing/dispersion and PCBs degradation are contributing to the decreasing concentrations after the discharge was eliminated in 1975. The congener pattern shift is likely attributed to a loss via volatilization and export of contaminated sediment from the stream. Burial could be a potential means to prevent resuspension into the water column.
© 2012 Viet D. Dang, David M. Walters and Cindy M. Lee. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.