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.

► OCPs were analyzed in air and water samples collected over marginal seas of China. ► α-HCH concentrations in the atmosphere were quite uniform. ► Atmospheric γ-HCH, TC, CC and DDT concentrations were highest in South China Sea. ► Dissolved OCP concentrations in water varied over a narrow range. ► Oceans exhibit net volatilization of some OCPs after a long period of prohibition.