Spatial-temporal variation, possible source and ecological risk of PCBs in sediments from Songhua River, China: Effects of PCB elimination policy and reverse management framework

The spatial variation, possible sources and ecological risk of polychlorinated biphenyls (PCBs) in the sediment from the Songhua River, China were investigated and evaluated in this paper. The total concentration of PCBs ranged from 0.59 to 12.38 ng/g dw, with a mean value of 3.82 ng/g dw. The seven indicators of PCB concentrations are significantly correlated with the total PCB concentrations (R = 0.950, p = 0.000). The temporal trend of PCBs in sediments showed that the total PCBs in the Songhua River have decreased since 2008. Point source pollution, discharge of historical usage and industrial sewage, and emissions of unintentionally produced PCBs were the predominant sources in sediment. A risk assessment indicated that most of the sampling sites in the sediment were at low potential ecological risk. The apparent decrease of PCBs in the sediment appeared after the China National Coordination Group for Implementation of the Stockholm Convention was established. A conceptual reverse management framework for PCBs and other organic pollutants was established in this study.