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

Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs). 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 to 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 (>75 μm). PCB sorption tended to increase with the total organic carbon (TOC) of the particulate matter in the sediment samples. However, greater PCB mass (almost 80%) was present in the larger particles. 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.