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Residues and chiral signatures of organochlorine pesticides in sediments from Xiangshan Bay, East China Sea

Residual levels and enantiomeric signatures of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in surface sediments from Xiangshan Bay, East China Sea were investigated. The concentrations of ∑HCHs (sums of α-, β-, γ-, and δ-HCH) and ∑DDTs (sums of p, p′-DDT, p, p′-DDD,p, p′-DDE, o, p′-DDT, and o, p′-DDD) ranged from 0.14 to 0.67 ng g−1 and 0.61 to 22.38 ng g−1, respectively. A slight potential health risk to the organism was then indicated for the residual levels of DDTs according to the ERL/ERM guidelines. Moreover, the predominant β-HCH implied that the technical HCH contamination was mainly due to the historical usage. But the high ratio of DDT/∑DDTs depicted a cocktail input pattern of fresh and weathered DDTs. The enantiomeric fractions (EFs) of α-HCH, o, p′-DDT, and o, p′-DDD were also determined. The degradation of α-HCH was enantioselective in all sediments samples, resulting in an enrichment of (–)-enantiomers. However, the racemic residues of o, p′-DDT and o, p′-DDD were observed in all sediments samples.