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One of the few pathways for environmental transformation of polychlorinated biphenyls (PCBs) is microbial dechlorination under anaerobic conditions, which is reported to occur in contaminated sediments of rivers, lakes and harbors. The goal of this work was to determine whether PCB dechlorination occurs in built waste treatment environments. We analyzed a large database on PCB congener concentrations in effluents and some influents of facilities in the Delaware River Basin. Positive matrix factorization was used to identify the sources of PCBs and to look for evidence of dechlorination. Seven factors were resolved from the data set of 89 congeners in 645 samples. Two of the resolved factors represented dechlorination signals. One of these was dominated by PCBs 4 and 19 and represents an advanced stage of dechlorination of Aroclors to di- and trichlorinated congeners. This dechlorination signal was most prevalent in effluents from sites with contaminated groundwater and from wastewater treatment plants (WWTPs) that serve combined sewers or treat landfill leachate. The other dechlorination signal appeared to represent an intermediate stage of dechlorination, because it was dominated by two coeluting groups of tetrachlorinated congeners: PCBs 44 + 47 + 65 and 45 + 51. This partial dechlorination signal was most prevalent in the 40 WWTPs with separate (sanitary) sewer systems, where it often comprised more than 20% of the PCBs in the effluents. Both dechlorination signals were present in WWTP influents, but were not observed in stormwater runoff, suggesting that dechlorination occurs in sewers. This work represents the first convincing evidence of PCB dechlorination occurring outside of contaminated aquatic sediments or anaerobic digesters. The results suggest that PCBs are dechlorinated by anaerobic bacteria in sewers, landfills, and contaminated groundwater. These two dechlorination signals comprise about 19% of the total loads of PCBs to the Delaware River from the sampled dischargers. [ABSTRACT FROM AUTHOR]

The non-Aroclor congener 3,3'-dichlorobiphenyl (PCB 11) has been recently detected in air, water, biota, sediment, and suspended sediment. Although it has been known since at least the 1970s that this congener is produced inadvertently during the production of diarylide yellow pigments, this work presents the first evidence that the use of these pigments in consumer goods results in the dispersion of PCB 11 throughout the environment at levels that are problematic in terms of achieving water quality standards for the sum of polychlorinated biphenyls (PCBs). In this work, PCB 11 is measured at ppb levels in consumer goods that are likely to be discarded in ways that allow them to enter wastewater treatment plants and combined sewer overflows, including newspapers, magazines, cardboard boxes used for food packaging, and plastic bags. Also, using data sets acquired for the purpose of calculating total maximum daily loads (TMDLs) for PCBs, PCB 11 loads to the New York/New Jersey Harbor and Delaware River are calculated. Despite the fact that there are no known manufacturers of diarylide yellow pigments in the Delaware River watershed, the loads of PCB 11 to the Delaware River exceed the TMDL for the sum of PCBs by nearly a factor of 2. The ratio of PCB 11 to a characteristic dechlorination end product, PCB 4 (2,2'-dichlorobiphenyl), in these data sets indicates that dechlorination is not a significant source of PCB 11 in these systems. In the upper Hudson River, where extensive dechlorination of heavy PCB congeners occurs, the ratio is just 0.012. In contrast, downstream in the NY/NJ Harbor as well as in the Delaware River the ratio is much higher and more variable. Pigment use therefore appears to be the main source of PCB 11 in these systems, and this congener is likely to present a significant obstacle to achieving PCB water quality standards throughout the United States. [ABSTRACT FROM AUTHOR]