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Yang G.,CAS Institute of High Energy Physics | Yang G.,International Joint Research Center for Persistent Toxic Substances | Ma L.,CAS Institute of High Energy Physics | Ma L.,International Joint Research Center for Persistent Toxic Substances | And 9 more authors.
Atmospheric Environment | Year: 2012

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, K pd, 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. © 2012 Elsevier Ltd.

Niu L.,International Joint Research Center for Persistent Toxic Substances | Niu L.,Zhejiang University | Xu C.,Zhejiang University of Technology | Xu Y.,International Joint Research Center for Persistent Toxic Substances | And 3 more authors.
Environmental Science and Technology | Year: 2014

The environmental issue caused by atmospheric hexachlorocyclohexanes (HCHs) has been a worldwide concern due to their long-range transport potential. Tree bark is an excellent passive sampler for monitoring atmospheric pollutants. In this study, bark samples from agricultural regions across China were collected and analyzed to elucidate the contamination status of atmospheric HCHs and the enantiomeric composition of chiral α-HCH. Average contents of α-HCH, β-HCH, γ-HCH, δ-HCH, and ΣHCHs in bark were 1.16, 2.51, 1.67, 0.368, and 5.71 ng/g (dry basis), respectively. Jing-Jin-Tang region was identified as the "hot-spot" of bark HCHs in China. Their residues were likely from the combined sources of historical applications of technical HCHs and lindane through long-distance transport. HCH contents were found inversely correlated with annual precipitation and temperature, but positively correlated with PM10 or PM2.5 due to the bioaccumulation of both vapor- and particle-phase HCHs by tree bark. Most bark samples preferentially accumulated (+)-α-HCH, and the enantiomeric fractions (EFs) of α-HCH were positively correlated with α-HCH concentrations and the elevations of sampling locations. Compared to atmospheric analysis, tree bark analysis and enantiomeric signatures provide valuable time-integrated information on the spatial distribution and transport pathways of atmospheric HCHs on the national scale in China. © 2014 American Chemical Society.

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