Organochlorine pesticides in seawater and the surrounding atmosphere of the marginal seas of China: spatial distribution, sources and air-water exchange.

Shipboard air and surface seawater samples collected over the Yellow Sea, East China Sea and South China Sea were analyzed for organochlorine pesticides (OCPs). In air, γ-hexachlorocyclohexane (HCH), trans-chlordane (TC) and cis-chlordane (CC) had significantly (p<0.001) higher concentrations than α-HCH, o,p'-Dichlorodiphenyltrichloroethane (DDT), p,p'-DDE, p,p'-DDT and α-endosulfan. Generally, α-HCH concentrations in the atmosphere were quite uniform over the Chinese marginal seas. However, the highest concentrations of γ-HCH, TC, CC and DDT compounds were found in the southern parts of the marginal seas, and higher concentrations of α-endosulfan were observed in the northern part of the marginal seas. In water, the OCP concentrations varied over a narrow range, with hundreds picogram per liter levels. Air-water exchange gradients suggested net deposition or equilibrium for γ-HCH and o,p'-DDT and net volatilization for α-HCH, CC, TC, p,p'-DDE and p,p'-DDT. Due to the potential source of those compounds from coastal water runoff, the ocean water played an important role of OCP sources for the atmosphere after a long period of OCP prohibition.