石期河西南子流域地下水重金属来源解析及健康风险评价

Analysis of Heavy Metal Sources in Groundwater and Assessment of Health Risks:An Example from the Southwest Sub-basin of the Shiqi River

为了探讨地下水中重金属元素的污染来源及健康风险状况,以石期河西南子流域为研究区,对该区域内41组具有代表性的地下水样品中的10种重金属元素As、 Cr、 Cd、 Al、 Cu、 Zn、 Ni、 Co、 Mn和Hg进行检测,利用相关性分析和主成分分析解析研究区地下水中重金属元素的可能污染来源,运用单因子污染指数(P_(i))、内梅罗综合污染指数(P_(N))和健康风险评价模型评估10种重金属元素的浓度特征和健康风险水平.结果表明:(1)研究区地下水重金属元素的浓度平均值均未超过地下水质量标准Ⅲ类水标准限值(GB/T 14848-2017),仅Al的浓度最大值超出,其次Al、 Mn和Cr的浓度变幅较大,平均贡献率最大的重金属元素是Al(65.74%).(2)单因子污染指数评价结果显示仅重金属元素Al超出清洁水平,内梅罗综合污染指数评价结果表明研究区处于低污染水平,地下水质良好.(3)多元统计分析结果显示,Zn、 Co和Mn为地质成因和生活废弃物组成的混合源,Al、 As和Cu为农业源,Cd、 Cr和Ni为工业源,Hg来自于大气的长距离传输.(4)研究区各重金属元素的健康风险值均在可接受范围内,儿童经饮用水途径产生的健康风险高于成人,经皮肤入渗途径产生的健康风险低于成人,重金属元素经饮用水途径产生的健康风险高于皮肤入渗途径,表明饮用水途径是重金属元素的主要暴露途径.

In order to explore the sources of pollution and health risk profile of heavy metal elements in groundwater,41 sets of representative groundwater samples from the southwest sub-basin of the Shiqi River were examined for 10 heavy metal elements(As,Cr,Cd,Al,Cu,Zn,Ni,Co,Mn,and Hg),and correlation analysis and principal component analysis were used to resolve the possible sources of heavy metal contamination in groundwater in the study area.The concentration characteristics and health risk levels of the 10 heavy metals were assessed using the single-factor contamination index(P_(i)),the Nemerow comprehensive contamination index(P_(N)),and the health risk model.The results showed that:(1) the average values of heavy metal elements of the groundwater in the study area all met the limit of the class Ⅲ water standard in the quality standard for groundwater(GB/T 14848-2017);only the maximum value of Al was exceeded,followed by a large variation in the concentrations of Al,Mn,and Cr.The heavy metal element with the largest average contribution was Al(65.74%).(2) The results of the single-factor contamination index evaluation showed that only the heavy metal element Al exceeded the cleaning level,and the results of the Nemerow comprehensive contamination index evaluation showed that the study area was basically at low pollution levels,and the quality of groundwater was good.(3) The results of the multivariate statistical analysis showed that Zn,Co,and Mn were from mixed sources consisting of geological formation and domestic waste;Al,As,and Cu were from agricultural sources;Cd,Cr,and Ni were from industrial sources;and Hg came from long-range atmospheric transport.(4) The health risk values for all heavy metals in the study area were within acceptable limits,with higher health risk values for children than for adults from the drinking water route,lower health risk values than in adults from the dermal route,and higher health risk values for heavy metals from the drinking water route than those from the dermal route,indicating that the drinking water route was the main route of exposure to heavy metals.