| 1960s, Rachel Carson’s book "Silent Spring "was publicated, which rasied public awareness on the environmental problem of persisten and bioaccumulating chemicals. With more and more serious environmental problems brought out by persistent organic pollutants (POPs) large of usages, Some countries and international organizations began to eliminate or restricte the use and production such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). However, newly emerged halogenate flame retardants (HFRs) included hexabromocyclododecanes (HBCDs), tris (2,3-dibromopropyl) isocyanurate (TBC) and short chain chlorinated paraffins (SCCPs) have been widely used in industry, mechanical and electrical products. They have similar POPs properties, and ubiquitous present in the environment.The purpose of this study is to investigate the spatial distribution transportationand fate of PCBs, PBDEs, HBCDs, TBC, SCCPs in different environmental matrixes.Firstly, we investigated the spatial distribution of PCBs and PBDEs in three farmland fields with different irrigation practices (irrigated with the reclaimed wastewater from a river, groundwater and mixed water) at the Tongzhou of Beijing, and discussed potential relationships between their concentrations and distributions. The concentrations of the total of26PCB congeners (∑26PCBs) in surface soil ranged from130to193×103ng kg-1dry weight (dw), including dioxin-like PCBs(15.6-441ng kg-1dw), six indicator congeners(50.7-452ng kg-1dw), and other eight congeners (76.9-1.06×103ng kg-1dw). Moreover, fourteen PBDE congeners were analyzed and the total PBDE concentrations(∑14PBDEs) were within the range1.81-14.4μg kg-1dw. Decabromodiphenyl ether (BDE-209) was the predominant congener which accounted for>94%of∑14PBDEs. PCBs and PBDEs concentrations in the river water and mixed water irrigated farmlands were found to be higher than those in the ground water irrigated farmland. Besides, correlations were found among concentrations of higher chlorinated biphenyls (C1≥4) in all samples, which might be related to the different irrigation practices and stronger adsorption capability of higher chlorinated biphenyls onto soil.Secondly, we studied the TBC and HBCDs the spatial and distributions in in farmland fields at the Tongzhou of Beijing. Relatively high concentrations and increasing temporal trends of TBC and HBCD in soils were found. Higher HBCDs levels were found at farmland irrigated by riverwater. The result also showed that a, y-HBCD had been found in all surface soil samples. The concentration ranges of TBC, α, β,γ-HBCD,∑HBCD were<LOD-1.62ng g-1,0.11-6.94ngg-1,<LOD-5.54ng g-1,0.06-23.8ng g-1,0.17-34.5ng g-1, respectively. Irrigating farms with wastewater might not be able to introduce the high contamination of HBCD and TBC into the soil, and there might be a local point sources, such as local industries or construction projects.Short chain chlorinated paraffins (SCCPs) are semi-volatile industrial chemicals that are persistent in the environment and subject to long-range transport. Despite these concerns, limited information is available on the atmospheric levels and distribution of SCCPs. The results showed that total atmospheric SCCP levels ranged1.85-33.0ng m-3during wintertime with an average of7.65ng m-3. Significantly higher levels were found during the summer (range112-332ng m"3, average200ng m-3). The average fraction of total SCCPs in the particle phase(φ) was0.67during wintertime but decreased significantly during the summer (φ=0.06). The ten and eleven carbon chain homologues with five to eight chlorine atoms were the predominant SCCP formula groups in air. Significant linear correlations were found between the gas-particle partition coefficients and the predicted subcooled vapor pressures and octanol-air partition coefficients. The gas-particle partitioning of SCCPs was further investigated and compared with both the Junge-Pankow adsorption and Koa-based absorption models. |
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