Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs). They can threaten the health of humans and wildlife. Urban stormwater runoff is considered as an important source of many pollutants, including PCBs, to aquatic environments. In this study, concentrations of 209 PCB congeners as well as profiles of the ten homologues were determined in stormwater sediments collected from various (primarily roadway) sites with different land use. The total PCB concentrations ranged from 8.3 – 57.4 ng/g dry weight (dw), with a mean value of 29.2 ng/g dw. PCB concentrations varied with nearby land use. Higher stormwater sediment PCB concentrations were found in dense urban areas (average: 39.8 ± 10.5 ng/g) and residential areas (average: 35.3 ± 6.2 ng/g) compared to highways passing through greenspace (average: 18.0 ± 0.4 ng/g). The number of chlorines per biphenyl ranged from 3.63 to 5.39 and the toxic equivalency (TEQs) of the PCBs were between 1.5 and 18.0 pg/g at all sites. A non-Aroclor congener, PCB 11, was detected in all samples and was dominant at two sites. PCBs were sorbed to smaller stormwater particulate matter (≤ 75 µm) at higher concentrations compared to larger particles (&gt; 75 µm). Total PCB concentrations were positively related with the total organic carbon (TOC) of the particulate matter. However, PCBs sorbed to the larger particles made up the greatest mass. Thus, sediment capture may be a viable treatment for reduction of PCBs in stormwater. Additionally, bacteria capable of PCB transformation were detected at some sites, indicating the potential of PCB removal via biotransformation. Results from this study suggest that targeting sediments from high density urban areas could reduce large portion of PCB stormwater load via particulate matter reduction. Information on sediment PCB concentrations from different land uses, along with stormwater particulate matter data can allow the estimation of PCB loads and load reductions using stormwater control measures.

Polychlorinated biphenyls in stormwater sediments: Relationships with land use and particle characteristics

2019 Fall National Meeting

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