Polybrominated diphenyl ethers and polychlorinated biphenyls in mangrove sediments of Shantou, China: Occurrence, profiles, depth-distribution, and risk assessment

Surface and columnar sediments were collected from four mangrove Wetlands in Shantou coastal areas of South China to investigate the level, distribution, possible sources and ecotoxicological risks of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). Total concentration of 14 PBDEs (∑₁₄PBDEs) and 41 PCBs (∑₄₁PCBs) varied from 0.61 to 180 ng/g and 42-636 pg/g dry weight (dw) in surface sediments, respectively. The concentration of PBDEs was much higher than that of PCBs. Compared with other mangrove Wetlands around the world, PCBs levels in the studied area were relatively low, while the concentrations of PBDE were at higher level. Decabromodiphenyl ether (BDE-209) was the predominant PBDEs homologue in all sediment samples, indicating the extensive use of deca-BDE in this area. Penta-CBs and hexa-CBs were the main homologues of PCBs. Spatial variations showed that the concentration of PBDEs might be mainly affected by anthropogenic activities in specific sites of this region, whereas dry and wet deposition might be an important input source of PCBs in this area. Although accurate sediment chronology was not available, higher concentrations of PBDEs and PCBs were still found in some deeper sediment layers, suggesting that new input quantity tends to decrease with the increase of control. Risk assessment showed that penta-BDEs and deca-BDE may have potential negative ecological effects on the ecological of Shantou mangrove sediments, while the effects of PCBs can be neglected.