Distribution and characterization of organochlorine pesticides and polycyclic aromatic hydrocarbons in surface sediment from Poyang Lake, China.

The concentrations of organochlorine pesticides (OCPs) and 16 priority polycyclic aromatic hydrocarbons (PAHs) were investigated in the sediments from Poyang Lake, the largest freshwater lake in China. The results showed that the total concentrations of four hexachlorocyclohexane (HCH) isomers (α-HCH, β-HCH, γ-HCH, δ-HCH), three dichlorodiphenyltrichloroethane (DDT) homologs and their metabolites (p,p'-DDD, o,p'-DDD, p,p'-DDE, p,p'-DDT, o,p'-DDT, o,p'-DDE), sodium pentachlorophenate and PAHs varied from 0.536±0.330 to 6.937±2.655, 14.421±5.260 to 82.871±31.258, 15.346±6.935 to 48.254±16.836, and 33.0±11.5 to 369.1±138.5 μg/kg, respectively. The concentrations of HCH isomers followed the order: γ-HCH>β-HCH>δ-HCH>α-HCH. The most dominant γ-HCH ranged from 0.253±0.155 to 3.465±1.010 μg/kg, suggesting a recent input of lindane. p,p'-DDD was the most dominant pollutant of DDTs, with a mean concentration of 31.684±13.530 μg/kg. The ratios of (DDE+DDD)/DDT ranged from 75±24 to 360±115, indicating no recent input of DDTs. The PAHs were mainly originated from liquid fossil fuel combustion and leakage, except at Pojiang River estuary, where the pyrogenic source (coal, grass and wood combustion) was dominant. Several PAH metabolites were identified and the possible degradation pathways were proposed.