Temporal Trends and Sources of PCBs in Mollusks from the Bohai Sea between 2011 and 2018

Abstract

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. Σ27 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 Σ27 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.

Soil’s Hidden Power: The Stable Soil Organic Carbon Pool Controls the Burden of Persistent Organic Pollutants in Background Soils

“…To minimize contamination during analytical procedures, strict quality assurance and control measures were conducted which were reported in previous studies. ,, Method detection limits (MDLs) of contaminants were determined as three times the standard deviation (SD) of the method blank concentrations. For contaminants with no signals in the blanks, MDLs were determined as the lowest standard in the calibration curve.…”