黄河中下游流域表层土壤中多氯联苯的残留特征

采用气质联用仪（GC-MS）对黄河中下游流域18个国家控制断面处表层土壤（0～15cm）样品中的多氯联苯含量进行测定，分析其残留特征、可能的污染源和生态风险.结果表明，黄河中下游表层土壤中∑PCBs变化范围为0.43～39.83ng/g dw，均值为3.72ng/g，和其他地区研究结果相比，黄河中下游流域表层土壤中PCBs 含量水平较低.类二英类PCBs的毒性当量DL-TEQ变化范围为1.85～27.22pg/g dw，均值为15.24pg/g dw，远低于其他国家相应的限值，极少存在生态风险. PCB18、PCB33、PCB49、PCB44、PCB52的检出率和残留量均比较高，是黄河中下游流域表层土壤中的优势污染物.二氯联苯、三氯联苯和四氯联苯是主要的同族体，分别占总量的10.71%.13.48%、63.43%，说明黄河中下游流域表层土壤中主要是低氯联苯污染.主成分分析表明黄河中下游流域表层土壤中PCBs主要是来自Aorclor1242、1248、1254、1260系列PCBs产品和国产变压器油的混合污染源.

Residual characteristics of polychlorinated biphenyls in surface soil of the Middle and Lower Reaches of the Yellow River

The residual characteristics of polychlorinated biphenyls (PCBs) in 18surface soil (0~15cm) samples collected from the Middle and Lower Reaches of the Yellow River were analyzed by GC-MS. The results showed that the concentrations of total PCBs in surface soil ranged from 0.43 to 39.83 ng/g dry weight (ng/g dw), with an average value of 3.72 ng/g dw, and the average PCBs level in this study was in a comparatively low level when compared with those in others regions. The toxic equivalency concentrations of dioxin-like PCBs (DL-TEQ)in surface soil ranged from 1.85 to 27.22 pg/g dw, with an average value of 15.24 pg/g dw. The DL-TEQ values were much lower than the corresponding limit values in other countries and rarely posed potential ecological risk. PCB18, PCB33, PCB49, PCB44 were identified as the prevalent contaminates of the surface soil. PCBs homologues analysis revealed that the PCBs in the study area were dominated by di-, tri-, tetra- and penta-chclorinated biphenys, indicating a relatively high proportion of lower PCBs. PCBs in surface soil might come from the Aroclor mixtures 1242, 1248, 1254 and 1260 and the transformer oil produced in China based on the principal component analysis (PCA).