DISTRIBUTION OF PCB CONGENERS IN SHEBOYGAN RIVER (WISCONSIN) SEDIMENTS

Polychlorinated biphenyl (PCB) contaminated sediment from the Sheboyga n River in Wisconsin was examined to determine the PCB congeners prese nt and their respective weight percentages of the total PCB concentrat ion. 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 containi ng PCBs at concentrations greater than 50 mug/g had a higher percentag e of lower chlorinated congeners compared to the PCB mixtures original ly thought to have been deposited in the sediment (Aroclor 1248 and 12 54). 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 se diments, ortho-chlorinated congeners were observed to be enriched rela tive 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.