Characterization of polychlorinated biphenyl congeners in surface sediments of the Changjiang Estuary and adjacent shelf by high-resolution sampling and high-resolution mass spectrometry

Due to limited samples and low-resolution analysis, conflicting findings on major polychlorinated biphenyl (PCB) congeners and their origins remain in the East China Sea (ECS). Based on high-resolution sampling and high-resolution mass spectrometry analysis, 72 surface sediment samples from the Changjiang Estuary and adjacent ECS shelf were determined to characterize 39 PCB congeners. PCBs (Sigma(39)PCBs) ranged from 0.003 to 16.18 ng/g dw, presenting a decreasing seaward trend. Tri-, tetra- and penta-CBs were the main components, accounting for > 64% of Sigma(39)PCBs in most samples. Tetra-CBs were the dominant congeners, corresponding to results of sediments from Changjiang middle reach and soils from Changjiang Delta. Comparison between PCBs and sediment properties indicated there may be a deposition boundary of 30 degrees N. In the north, the spatial distribution of PCBs is controlled by Changjiang input and hydrodynamic conditions, while in the south closely related to combination of local source and riverine input