太湖竺山湾及入湖河流沉积物中多氯联苯单体分布及源解析

Distribution and source apportionment of polychlorinated biphenyl congeners in surface sediments from Zhushan Bay and the inflow rivers of Lake Taihu

采用改进后的GC-μECD方法定量测定了太湖竺山湾及入湖河流(太滆运河、漕桥河、殷村港和社渎港)16个表层沉积物中209种多氯联苯(PCBs)单体浓度,并对其分布特征进行了探讨.结果表明,在16个采样点共检测出115种多氯联苯单体,ΣPCBs浓度在11.02~84.05ng/g(干重)之间,整体呈现出殷村港<漕桥河<社渎港<太滆运河<竺山湾的趋势,平均浓度为26.42ng/g(干重).沉积物中多氯联苯平均组成以一氯和二氯联苯为主,质量百分含量分别为34.26%和23.19%;其次是三到六氯联苯,占比依次为14.86%、6.76%、7.37%、9.61%;七到十氯联苯含量最低,质量百分含量总计仅有3.95%.同时,利用主成分分析方法对表层沉积物中的多氯联苯污染进行了源解析.结果显示,表层沉积物中的多氯联苯主要来源于附近泄漏的电容器、变压器油以及油漆、造纸等行业的排放污水,与多氯联苯商业产品Aroclors系列有较大差别.通过毒性当量因子法和加拿大沉积物环境质量标准评价法对研究区域生态风险进行分析,显示太湖竺山湾及4条入湖河流沉积物中多氯联苯污染的生态风险不容忽视.

The concentrations of 209 polychlorinated biphenyl congeners in 16 surface sediments collected from Zhushan Bay and the inflow rivers(Taige Canal, Caoqiao River, Yincun River and Shedu River) of Lake Taihu were determined by a modified GC-μECD method and the distribution characteristics were discussed. Results showed that 115 PCB congeners were detected and the concentrations of total PCBs ranged from 11.02 ng/g to 84.05 ng/g(d.w.) at the 16 sampling sites. In general, the total PCBs were Yincun River<Caoqiao River<Shedu River<Taige Canal<Zhushan Bay. The average concentration was 26.42 ng/g(d.w.) and the dominant PCB congeners were monochlorobiphenyls and dichlorobiphenyls, which accounted for 34.26% and 23.19% of the total mass, respectively. In addition, tri-to hexa-chlorobiphenyls accounted for 14.86%, 6.76%, 7.37% and 9.61%, respectively. The lowest were hepta-to octa-chlorobiphenyls, which only accounted for 3.95% in total mass. Meanwhile, source apportionment of PCBs in the surface sediments was conducted by principal component analysis(PCA), which revealed that PCBs in the sediments originated mainly from leakage of capacitor, transformer oil and sewage discharged from oil paint and paper mill or other industries. Moreover, the congener compositions of the sediments were different from known commercial Aroclors. Ecological risk in the study area was assessed using toxicity equivalent factors and Canadian sediment quality guidelines. PCBs pollution in the sediments from Zhushan Bay and 4 inflow rivers of Lake Taihu was likely to cause some potential ecological risks.