Use of lipid biomarkers for identification of regional sources and dechlorination characteristics of polychlorinated biphenyls in the East China Sea

Terrestrial organic matter (TOM) indicators could serve as proxies in studying the environmental behavior of organic pollutants because they are transported into the shelf seas along with the TOM. In this study, comparisons between polychlorinated biphenyls (PCBs) and TOM indicators of ∑ C27 + C29 + C31n-alkanes, as well as branched and isoprenoid tetraether (BIT) index, were performed to examine the regional sources of PCBs in the East China Sea. The results indicated that sedimentary PCBs in the mud area southwest of the Cheju Island, coastal area north of the 29°N, and coastal area south of the 29°N were mainly from atmospheric deposition, riverine input of the Yangtze River, and local coastal sources via atmospheric deposition, respectively. The broad resemblance of the spatial patterns of non-definitive indicators of PCB dechlorination, hypoxia, and ∑ ladderane lipids suggested that deep dechlorination mainly occurred at the coastal areas and center shelf southwest of Cheju Island.