DISTRIBUTION OF PCB CONGENERS IN SHEBOYGAN RIVER (WISCONSIN) SEDIMENTS

Polychlorinated biphenyl (PCB) contaminated sediment from the Sheboygan River in Wisconsin was examined to determine the PCB congeners present and their respective weight percentages of the total PCB concentration. Total PCB concentrations in the sediments ranged from less than 1 mug/g to over 1,500 mug/g (on a dry weight basis). Sediments containing PCBs at concentrations greater than 50 mug/g had a higher percentage of lower chlorinated congeners compared to the PCB mixtures originally thought to have been deposited in the sediment (Aroclor 1248 and 1254). The most prominent congeners observed in the sediments were IUPAC numbers 17, 26, 49, 52, and coeluting congeners 5/8, 24/27, 16/32, 28/31, 41/64/71, 47/48, 66/95, and 77/110. In the highly contaminated sediments, ortho-chlorinated congeners were observed to be enriched relative to meta- and para-chlorinated congeners. The similarity of these results to results from experiments with anaerobic PCB-dehalogenating microbes suggests that anaerobic microbial degradation has occurred in the highly contaminated sediments of the Sheboygan River.