电子垃圾拆解区土壤中典型手性PCBs分布及对映体特征

龙塘镇位于广东省清远市,是国内最大的进口电子垃圾集中处理处置地之一.通过对龙塘镇土壤中7种手性PCBs对映体浓度和对映体百分数(enantiomer fractions,EF)值的测定,发现龙塘镇土壤样品除PCB45和PCB174外,其余5种手性PCBs在土壤中均有不同程度的检出.土壤中5种目标手性PCBs(PCB91、PCB95、PCB132、PCB136和PCB149)的总浓度为145.4—286.7 ng·g^-1,这与先前文献中测定清远市土壤中手性PCBs污染水平基本一致.5种同系物的含量排序为PCB95>PCB132>PCB136>PCB149>PCB91.在距离电子垃圾拆解区10km以外的区域也检测到手性PCBs,证实这些污染物已经迁移到周边地区.土壤中手性PCB91、PCB95、PCB132、PCB136和PCB149的EFs值分别为0.519±0.005、0.4443±0.006、0.427±0.003、0.379±0.016和0.494±0.008,其中PCB149具有双向选择性.在全部检出样品中26%的PCB91、78%的PCB95、100%的PCB132、86%的PCB136和53%的PCB149具有非外消旋特征,表明该地区土壤中手性对映体选择性降解的显著性.

Distribution and enantioselective characteristics of typical polychlorinated biphenyls in soils at an e-waste site

Longtang Town is a large e-waste dismantling area located in Qingyuan City,Guangdong Province,China.In this study,the enantiomeric concentrations and enantiomer fractions(EF)of chiral PCBs(PCB 45,PCB91,PCB95,PCB132,PCB136,PCB149 and PCB174)in soil were analyzed.The results showed that except for PCB45 and PCB174,the other five chiral PCBs were detected.The total concentrations of seven kinds of PCBs in the e-waste site ranged from 145.4 ng**g_1 to 286.7 ng?g^-1,which were consistent with previous analysis in this area.The contents of these five chiral PCBs in soil in this area order from high to low was PCB95,PCB 132,PCB136,PCB149 and PCB91.Chiral PCBs were also detected in locations 10 km far away from the e-waste dismantling sites,implying that these pollutants have been transported to surrounding regions.The EFs values of chiral PCB91,PCB95,PCB132,PCB136 and PCB149 in soils were 0.519±0.005,0.4443±0.006,0.427±0.003,0.379±0.016 and 0.494±0.008,respectively.26%of PCB91,78%of PCB95,100%of PCB 132,86%of PCB 136 and 53%of PCB 149 got non-racemic characteristics in all detected samples,indicating that the selective degradation of chiral PCBs in the soil was significant.