HCH and DDT Residues in Bivalves <Emphasis Type="Italic">Anodonta woodiana</Emphasis> from the Taihu Lake,China

The present article attempts to use freshwater bivalves Anodonta woodiana for monitoring the pollution of hexachlorocyclohexane isomers (α-, β-, γ-, δ-HCH), dichlorodiphenyltrichloroethanes (o, p′, p, p′-DDT) and metabolites (p, p′-DDE, p, p′-DDD) in the Taihu Lake, China. A total of 36 bivalves were sampled from 4 sites of Huzhou city, Dapu of Yixing city, Xueyan of Changzhou city, and Wulihu of Wuxi city around the lake in August–October 2004. The organochlorines were detected in all bivalves, and the mean concentration of ΣDDTs (7.07 ng/g wet weight) was significantly higher than that of ΣHCHs (2.37 ng/g wet weight). Overall, ΣHCHs are at the highest concentrations in the bivalves from the Dapu and Huzhou site, whereas ΣDDTs are at highest concentrations in the bivalves from the Wulihu site. Compositions of ΣHCHs were predominated by α- and γ-HCH isomers in the bivalves from all four study sites. Among these sampling sites, p, p′-DDT exhibited the highest percentage in the bivalves from Huzhou site. Furthermore, significant regional variations in compositions of both ΣDDTs and ΣHCHs had been identified. The residue levels of ΣDDTs and ΣHCHs in the bivalves of the present study were much lower than the corresponding residue limits for aquatic products of Ministry of Agriculture of China, FDA, and FAO/WHO. These findings suggest that Anodonta woodiana could serve as a unique bioindicator to monitor the HCH and DDT pollutions in the freshwater environment.