Research of organochlorine pesticides and polychlorinated biphenyls in atmospheric precipitation and surface water in Zoige alpine wetland

To further understand the geochemical behaviors of persistent organic pollutant (POPs) in remote areas, the seasonal distribution characteristics of anthropogenic organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) concentrations in surface water and wet precipitation samples collected from Zoige alpine wetland in the eastern edge of the Qinghai-Tibet Plateau were determined by HRGC-HRMS. The mean concentrations of ∑HCHs, ∑DDTs, HCB, ∑6PCBs in the surface water were 0.90, 1.36, 0.95, 1.35 ng/L, respectively. The mean concentrations of ∑OCPs and ∑6PCBs in wet precipitation were 0.363, 0.118 ng/L, respectively, with the maximum values present in snow of November. The mean concentrations were in the order of HCB > PCB28 > p,p'-DDD > p,p'-DDE > α-HCH > γ-HCH. PCB28 and PCB52 were the predominant PCB congeners. Except for trace amount of PCB101, all highly chlorinated PCB congeners were not detected. The deposition fluxes of ∑HCHs, ∑DDTs, and ∑6PCBs were in the range of 0.058~0.268, 0.087~0.311, and 0.049~0.188 ng/(m2·d), respectively. The results confirmed the difference between long-range atmospheric transport via high altitude air mass and the mountain cold trapping effect. The precipitation mode of POPs in high altitude areas can be distinguished as two types, i.e., the altitudinal gradient wet precipitation mode and the high plateau mode. Similar to the cases in polar areas, the snow deposition flux of POPs in high plateau mode is generally higher than rain deposition flux, lack of less persistent PCB 138, PCB153 and PCB180 components.