Historical Changes in Polychlorinated Biphenyls Contaminated Sediments

Ir Ir

doi:10.3844/ajessp.2012.11.15

Abstract

Problem statement: PCBs contamination continues to pose a health risk to aquatic environments due to their recalcitrance and bioaccu mulation. 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 t o 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 �g g -1 , which were one order of magnitude lower than levels measured in 1987 (<0.20-10.23 �g g -1 ). Total PCBs in this study (based on more than 130 congener s) 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 attri buted 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.

Highlights

Synthetic Chlorinated Hydrocarbons (e.g., Polychlorinated Biphenyls (PCBs), DDTs and HCHs) are widely distributed throughout the aquatic environment
The Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund site located in Pickens, South Carolina, USA, was contaminated with PCBs-containing wastes released from a former capacitor manufacturing plant
PCB concentrations in yellowfin shiner (Notropis lutipinnis) collected from 2003-2005 in Twelvemile Creek continue to be above the 2.0 mg kg−1 FDA limit (Walters et al, 2008; Dang, 2007)

Summary

Introduction

Synthetic Chlorinated Hydrocarbons (e.g., PCBs, DDTs and HCHs) are widely distributed throughout the aquatic environment. Polychlorinated Biphenyls (PCBs) are some of the most persistent and ubiquitous pollutants in the environment Their physicochemical properties are variable owing to different number of chlorines attached to the biphenyl molecule. The functional properties that make PCBs ideal for “open” applications (e.g., heat insulators, transformers and dielectric fluids) result from the fact those commercialgrade PCBs are mixtures or Aroclors (Baker, 1980). Because of their potential carcinogenicity, since the late. Environmental cycling has led to worldwide distribution of PCBs. Measurable levels of PCBs have been documented universally in ambient air, soils, rivers, sediments and tissues of organisms (EPA, 1976).

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