Program

Sediments and biota were collected from mangrove wetlands in the Pearl River Estuary (PRE) to investigate the distributions of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) and dechlorane plus (DP). Concentrations of PCBs, DDTs, PBDEs, DBDPE and DP in surface sediments ranged from 0.18-7.11, 1.11-84.1, 1.3-206.0, 0.36-34.9 and 0.013-1.50 ng/g dry weight, respectively. PBDEs levels in mangrove sediments of the PRE were at the high end of the global range. The highest concentrations of PCBs, PBDEs, DBDPE and DP were found at the mangrove wetlands from Shenzhen, showing the dependence on the proximity to urban areas. PBDEs were the predominant HOPs in mangrove sediments from the PRE. Levels of PBDEs, DBDPE and DP in the mangrove sediment cores from the PRE showed an increasing trend from the bottom to top layers, reflecting an increasing usage of these halogenated flame retardants. Daggertooth pike conger (Muraenesox cinereus) had the highest concentrations of HOPs among the four biota species. Significant positive relationship between anti-Cl11-DP and anti-DP levels was observed in mangrove biota. DDTs were the predominant HOPs in all biota species, followed by PCBs and PBDEs. All the target compounds exhibited biomagnification, with biomagnification factors greater than 1 in the studied feeding relationships. Food web magnification was found for SPCBs, SDDTs, SPBDEs and DP, with trophic magnification factors of 2.76, 2.61, 2.20 and 2.31, respectively.