长江中游干流及22条支流表层水中多氯联苯的分布特征及其潜在风险

Distribution Characteristics and Potential Risk of PCBs in Surface Water from 22 Tributaries and Mainstream in Middle Reaches of Yangtze River

采用GC/MS/MS技术对长江中游重庆至宜昌段22条支流和干流的47个表层水样进行分析.实验发现支流表层水样中PCB8、28、52和118是优势污染物,而干流表层水样中PCB8和28是优势污染物.ΣPCBs在支流和干流表层水样中的几何均值分别为20.71 ng.L-1和13.25 ng.L-1,ΣPCBs最高检出浓度61.79 ng.L-1出现在支流壤渡河,最低浓度3.77 ng.L-1出现在支流草塘河;85%的支流表层水样中ΣPCBs的浓度高于美国环境保护署制定的连续暴露基准浓度14 ng.L-1,但所有支流和干流水样中ΣPCBs的检出浓度都远低于国家饮用水标准限值500 ng.L-1;实验结果与国内外相关文献报道值相比较,也显示该研究区域表层水中PCBs浓度处于较低水平,癌症风险评价结果表明饮用支流和干流的水因摄入PCBs而带来的风险分别为2.07×10-7和1.33×10-7,说明研究区水样中因PCBs污染引起的癌症风险较低.

47 surface water samples were collected from 22 tributaries and mainstream of the Yangtze River from Chongqing to Yichang.The contents of 28 PCB congeners in surface water samples were measured using Varian CP3800/300 GC-MS/MS technique.PCB8,28,52 and 118 are the most predominant PCB congeners in the samples from tributaries,PCB8 and 28 are the most predominant PCB congeners in those from mainstream.The measured level of PCBs in the samples from the tributaries and from the mainstream were 20.71 ng·L-1 and 13.25 ng·L-1 respectively.The highest concentrations of PCBs was detected in the samples from Rangdu River（61.79 ng·L-1）,the lowest concentrations of PCBs was detected in water samples from Caotang River（3.77 ng·L-1）.The average concentrations of PCBs in the samples from more than 85% of tributaries are higher than the USEPA criterion continuous concentration（14 ng·L-1）,however,all the levels of PCBs in mainstream and tributaries are far lower than the Chinese drinking water guideline value（500 ng·L-1）.The concentrations of PCBs in the samples were in the same order of magnitude of those reported on lower levels in European and American countries.The estimated cumulative cancer risk for the local residents who drink water from tributaries and mainstream were 2.07×10-7 and 1.33×10-7,which shows that cancer risk is negligible due to PCBs contamination in these samples.