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Gaseous exchange fluxes of organochlorine pesticides (OCPs) across the air−water interface of the coastal East China Sea were determined in order to assess whether the contaminated plume of the Yangtze River could be an important regional source of OCPs to the atmosphere. Hexachlorocyclohexanes (HCHs), chlordane compounds (CHLs), and dichlorodiphenyltrichloroethanes (DDTs) were the most frequently detected OCPs in air and water. Air−water exchange was mainly characterized by net volatilization for all measured OCPs. The net gaseous exchange flux ranged 10−240 ng/ (m 2 ·day) for γ-HCH, 60−370 ng/(m 2 ·day) for trans-CHL, 97−410 ng/(m 2 ·day) for cis-CHL, and ∼0 (e.g., equilibrium) to 490 ng/(m 2 · day) for p,p′-DDE. We found that the plume of the large contaminated river can serve as a significant regional secondary atmospheric source of legacy contaminants released in the catchment. In particular, the sediment plume represented the relevant source of DDT compounds (especially p,p′-DDE) sustaining net degassing when clean air masses from the open ocean reached the plume area. In contrast, a mass balance showed that, for HCHs, contaminated river discharge (water and sediment) plumes were capable of sustaining volatilization throughout the year. These results demonstrate the inconsistencies in the fate of HCHs and DDTs in this large estuarine system with declining primary sources.

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a b s t r a c tTotal organic carbon, total nitrogen, d 13 C org , d 15 N, and aliphatic and polyaromatic hydrocarbons of fiftyfive soil samples collected from the coastal wetlands of the Liaohe Delta were measured, in order to determine the sources and possible preservation of organic matter (OM). The d 15 N and d 13 C org values in the samples ranged from 3.0‰ to 9.4‰ and from À30.4‰ to À20.3‰, respectively, implying that the OM in the soils is predominantly derived from C 3 plant. The long-chain n-alkanes had a strong odd-over-even carbon number predominance, suggesting a significant contribution from waxes of higher plants. The ubiquitous presence of unresolved complex mixture, alkylated polycylic aromatic hydrocarbons and typical biomarkers of petroleum hydrocarbons (pristane, phytane, hopanes and steranes) indicates that there is a contribution of petroleum hydrocarbons to the organic carbon pool in the wetland soils. P. australis-vegetated wetlands have strong potentials for the preservation of organic carbon in the wetlands.

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