Distribution of persistent organic pollutants in bivalves from the northeast coast of China

To assess the levels of organochlorine compounds (OCs) in the Chinese coastal environment, monitoring study using bivalves was conducted in 2005. A total of 21 bivalve samples covering the northeastern coast of China were collected and analyzed. Organochlorine compounds were widely distributed in the Chinese coastal environment, with dichlorodiphenyltrichloroethane (DDT) contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, chlordane compounds (CHLs), dieldrin, and endosulfans in bivalves were in the ranges of 3.27–25.4, 54.8–2680, 1.42–25.5, n.d. (not detected)–2.28, n.d.–4.02, and n.d.–9.55 ng g−1 on a dry weight basis, respectively. The concentrations of DDT and HCH compounds are relatively higher than those from the coastal areas of other Asian countries. DDT metabolites were predominant, suggesting that the degradation of DDT is in progress in the Chinese coastal environment. Still, however, DDTs of high concentration exceeding 1000 ng g−1 were observed at 19% of the stations surveyed. Among HCH compounds, β-HCH, which is an isomer with strong persistency, was observed predominantly. Compositions of DDT and HCH compounds imply that fresh input of the two compounds into the Chinese coasts is possibly low.