title: Characteristic accumulation and soil penetration of polychlorinated biphenyls and polybrominated diphenyl ethers in wastewater irrigated farmlands.
abstract: The impact of wastewater irrigation on the distribution of two groups of persistent organic pollutants (POPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), in farm soil was investigated in this study. The concentrations of total analyzed PCBs were in the range 256-2140pgg(-1) on dry weight basis in surface soils. There was a higher accumulation of PCBs in farms irrigated by wastewater, with decachlorobiphenyl (CB-209) as the predominant congener. The spatial distributions of PBDEs were similar although not as obvious as that of PCBs, and BDE-209 was the predominant congener at 2040-496000pgg(-1)dw, accounting for >96% of the total analyzed PBDEs. However, no significant correlations could be found between PCB and PBDE concentrations in the topsoil samples, and also with soil organic content between the different sites. On the other hand, soil vertical profiles showed significant relationship with soil organic content in cores taken from farms irrigated with wastewater. The vertical distribution was quite uniform at the topsoil, corresponding to the plowed layer, and decreased thereafter exponentially. Furthermore, the soil vertical distribution was found to be congener specific for PCBs, where less chlorinated congeners were able to penetrate deeper into the soil while heavier congeners were more restricted in their movement. This fractionation process was however not found for PBDEs. Also, the prevalence and high relative concentrations of CB-11 and CB-209 suggests that these PCB congeners should more often be included in routine environmental analysis in order to identifying unusual contamination sources.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
authors.forename: Thanh
authors.initials: T
authors.lastname: Wang
authors.forename: Yawei
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianjie
authors.initials: J
authors.lastname: Fu
authors.forename: Pu
authors.initials: P
authors.lastname: Wang
authors.forename: Yingming
authors.initials: Y
authors.lastname: Li
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhang
authors.forename: Guibin
authors.initials: G
authors.lastname: Jiang
mesh_terms: D057914:Agricultural Irrigation; D004784:Environmental Monitoring; D055768:Halogenated Diphenyl Ethers / Q000032:analysis*; D007700:Kinetics; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D055768:Halogenated Diphenyl Ethers; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls