Temporal Trends And Sources Of Pcbs In Mollusks From The Bohai Sea Between 2011 And 2018

Commercial technical mixtures of polychlorinated biphenyls (PCBs) have been banned for almost 40 years. However, there are still sources from chemical products, such as 3,3'-dichlorobiphenyl (PCB-11), a byproduct of pigment production, which continuously release PCBs into the environment. In this study, mollusks (n = 316) were collected from nine coastal cities of the Chinese Bohai Sea area between 2011 and 2018 to investigate the temporal trend and sources of PCBs in this area. Sigma(27) PCBs ranged from 0.19 to 16.01 ng/g dry weight, with a median concentration of 2.00 ng/g dry weight. PCB-11 was the most detected congener, accounting for 52.5 +/- 18% of Sigma(27) PCBs. The temporal trend analysis indicated that the concentrations of PCBs in mollusks decreased significantly, with halving times of approximately 10.4 years. Compared to the total concentrations of PCBs, PCB-11 in mollusks did not significantly change over this time period, indicating that PCB-11 is continuously leaking into the environment. The positive matrix factorization (PMF) model indicated that the main source of PCBs in mollusks was pigment and painting (58.2%). These results imply that the unintentional emission of PCBs requires further attention.