Temporal variations of organochlorine pesticides in precipitation in Beijing, China

Temporal variations of organochlorine pesticides (OCPs) were determined in precipitation and monthly depositional fluxes were calculated in Beijing from February 2009 to March 2011. Compounds which were detected most often included α-HCH and β-HCH, and the volume-weighted mean (VWM) concentration of hexachlorocyclohexanes (HCHs) was 33.0 ng L−1, accounting for 72.3% of the ∑OCPs in precipitation. The total concentrations of OCPs ranged from 3.73 to 152 ng L−1 (mean: 29.7 ± 3.5 ng L−1) for dissolved phase and from 1.61 to 114 ng L−1 (mean: 15.9 ± 2.0 ng L−1) for particulate phase, respectively. OCPs in dissolved phase dominated sampled concentrations in precipitation (HCHs: 71.8%, Chlordane: 77.7%, dichlorodiphenyltrichloroethanes-DDTs: 50.1%) with an exception of hexachlorobenzene–HCB (26.3%). Furthermore, the distribution coefficient, Kpd, was generally large in low temperature, especially in spring. The abundance of ∑OCPs in the precipitation fluctuated monthly, with high value in late winter and spring. The past farmland near the sampling site was under construction during sampling, which may be an important local re-emission source in this study. The elevated wet deposition flux of 11 selected OCPs was 14.9 μg m−2 yr−1 in Beijing.