PCB congeners and dechlorination in sediments of Sheboygan River, Wisconsin, determined by matrix factorization

Nine sediment cores were collected from the Sheboygan River Inner Harbor, WI, and analyzed for polychlorinated biphenyl (PCB) congeners. Total PCBs ranged from similar to 0 to 161 mg/g. Positive matrix factorization (PMF) was applied to the PCB data set to determine source profiles. Two factors were determined to be significant. One factor resembled the original approximated PCB mixture of 50% Aroclor 1248 and 50% Aroclor 1254 and the other factor was a dechlorinated version of the mixture. An anaerobic dechlorination model was applied to the dechlorinated source profiles to quantify possible dechlorination pathways. It was found that dechlorination process H' provided the best fit for an individual process, and H' + M provides the best fit for combined processes. PMF source contributions, and plots of PCB concentration versus congener for individual samples, provide evidence of enhanced dechlorination at high concentrations (> 40 ppm) and small amounts of dechlorination at low concentrations (< 3 ppm). In addition, downward migration of lower chlorinated PCBs in core SR1a has occurred. Remediation dredging in the Upper Sheboygan River in 1989 and 1990 reintroduced PCBs to the water column and selective transport of PCB 18 is observed in core SR7.