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.
Chemosphere. 2010 Nov;81(8):1045-51. doi: 10.1016/j.chemosphere.2010.07.045. Epub 2010 Sep 16.
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.
本研究调查了废水灌溉对农田土壤中两类持久性有机污染物（POPs）——多氯联苯（PCBs）和多溴二苯醚（PBDEs）分布的影响。表层土壤中总分析 PCBs 的浓度范围为 256-2140pg/g 干重。废水灌溉农田中 PCBs 的积累量更高，其中十氯联苯（CB-209）为主要同系物。PBDEs 的空间分布与 PCBs 相似，但不如 PCBs 明显，BDE-209 为主要同系物，浓度范围为 2040-496000pg/g 干重，占总分析 PBDEs 的>96%。然而，在表层土壤样本中，PCBs 和 PBDEs 的浓度与不同地点的土壤有机含量之间没有明显的相关性。另一方面，从废水灌溉的农田中采集的土壤垂直剖面与土壤有机含量呈显著相关。在耕作层，土壤垂直分布非常均匀，此后呈指数下降。此外，发现 PCBs 的土壤垂直分布与同系物特异性有关，其中氯代较少的同系物能够更深入地渗透到土壤中，而较重的同系物在其迁移过程中受到更多限制。然而，这种分馏过程在 PBDEs 中并未发现。此外，CB-11 和 CB-209 的高浓度和高相对浓度表明，这些 PCB 同系物应更经常包含在常规环境分析中，以识别异常的污染来源。
