西藏尼洋河流域饮用水源地重金属健康风险评价

Health Risk Assessment of Heavy Metals in Drinking Water Sources in Nyang River Basin in Tibet

为研究尼洋河流域饮用水源地的重金属污染状况及对人体健康的潜在危害,作者对尼洋河干流水体理化指标和Cd、Cu、Pb等金属含量的空间分布特征进行了分析,利用因子分析方法和综合污染指数法分析重金属污染物的主要来源和污染状况,同时采用美国环保局推荐的健康风险评价模型对流域水源地水体的健康风险进行了评价。结果表明:流域水体偏碱性;Cd、Cu、Pb浓度含量均未超过《地表水环境质量标准》(GB 3838-2002)Ⅲ类水质标准限值;水源地重金属浓度进行Pearson相关性分析中,丰水期水体中Cd、Pb、Cu、TP有相似的来源,而枯水期Cd、Pb、Cu与NH3-N有相似的来源,上游水体重金属来源主要为自然源,中下游水体重金属具有为多源性;下游水体重金属污染状最轻,重金属Cd为水体的主要污染分担指标;流域饮用水源地成人与儿童的平均个人年健康总风险变化幅度分别为2.1×10-5~5.1×10-5a-1和2.7×10-5~6.6×10-5a-1,饮用水源地水体非致癌重金属Pb与Cu的总健康风险程度在10-9a-1为人体可接受风险值,致癌重金属Cd的健康风险程度约是非致癌重金属Pb与Cu健康风险值的104倍,且高于国际辐射防护委员会(ICRP)推荐的Cd最大可接受风险水平值(5.0×10-5a-1),健康风险程度顺序为Cd>Pb>Cu,下游水体健康风险程度最低。Cd是尼洋河流域水体中污染负担最高的污染物,同时也是健康风险的主要污染物,是流域水环境风险管理和控制的主要对象。

In order to study the heavy metal pollution status of drinking water sources in Nyang River Basin and the potential harm to human health, the physical and chemical indicators of the mainstream waters of the River and the spatial distribution characteristics of Cd, Cu, Pb and other metal contents were analyzed. Methods and comprehensive pollution index method were used to analyze the main sources and pollution status of heavy metal pollutants. At the same time, the health risk assessment model recommended by the US Environmental Protection Agency was used to evaluate the health risks of water bodies in the basin. The results showed that the water body was alkaline, and the concentration of Cd, Cu and Pb did not exceed the limit of GradeⅢof Surface Water Quality Standard(GB 3838-2002). Pearson correlation analysis of heavy metal concentration in water source indicates that Cd, Pb, Cu and TP in the high water period have similar sources in the water, while Cd, Pb,Cu and NH3-N have similar sources in the dry season. The upstream water and heavy metal sources are mainly natural sources, and the middle and lower reaches of the water are multi-sourced. The weight of metal in the downstream water is the lightest, and heavy metal Cd is the main pollution sharing index of the water body. The average annual total health risk of adults and children in the drinking water source of the basin is 2.1×10-5~5.1×10-5 a-1 and 2.7×10-5~6.6×10-5 a-1, and total health risk of non-carcinogenic heavy metal Pb and Cu in drinking water source is 10-9 a-1 which is the acceptable risk value of human body.Cd which is the carcinogenic heavy metal causing health risk is about 104 times that of non-carcinogenic heavy metal Pb and Cu, and higher than the maximum acceptable risk level of Cd recommended by the International Commission on Radiological Protection(ICRP)(5.0×10-5 a-1), with health risk degree order as Cd>Pb>Cu, the lowest level of health risk is in downstream waters. Cd as the pollutant with the highest pollution burden in the water body and the main pollutant of health risk, is the main target for water environment risk management and control.