洋河流域不同时空水体重金属污染及健康风险评价

确定水体重金属污染及健康风险时空变化趋势，对流域水环境管理具有重要指导意义。基于1995年、2005年和2015年洋河流域10个监测断面的重金属监测数据，采用健康风险评价模型，对洋河流域As、Cd、Pb、Hg 和 Cu 的浓度及其引起健康风险的时空变化进行了评价。结果表明，洋河流域重金属污染及其健康风险在时间上呈降低趋势，超过地表水质量标准三类标准的重金属由1995年的Cd、Pb和Hg变为2005年和2015年的Cd、Pb。致癌物质As和Cd所引起的个人年均风险远远高于非致癌物质 Pb、Hg 和 Cu。重金属健康风险总和在1995年所有监测断面均超过国际辐射防护委员会（ICRP）推荐的最大可接受风险水平，2005年全部在最大可接受风险水平以下，2015年只有响水铺略微高于该水平。在空间分布上，重金属污染较为严重及其健康风险较大的区域集中于南洋河下游城区段、清水河下游张家口市区段和洋河干流下游段。

Heavy metals pollution and related health risk assessment of Yang River:Spatial and temporal variation

In the context of water environment management, determining the spatial and temporal variation of heavy metal pollution and related health risks from exposure to watery environments are of great significance. Based on the concentrations of the As, Cd, Hg, Pb, and Cu in water samples from 10 points sampled in 1995, 2005, and 2015;this work involved analysis of the features of spatial and temporal variation of such heavy metals and the related health risk for those using the Yanghe River. Results showed that the concentrations of As, Cd, Hg, Pb, and Cu show a decreasing trend from 1995 to 2015 as a whole. In 1995, the concentrations of Cd, Pb, and Hg exceeded the National Water Quality Standard Ⅲ. In 2005 and 2015, only Cd and Pb did not meet the National Water Quality Standard Ⅲ. The health risk from carcinogens was much higher than that from non-carcinogens. In 1995, the sum of health risks at the 10 sampling points all exceeded the maximum allowance levels recommended by the International Commission on Radiological Protection (ICRP), whereas all sampling points were below the maximum allowance levels in 2005. In 2015, only Xiangshuipu exceeded the maximum allowance levels. The downstream portion of the Nanyang River, the Qingshui River in the Zhangjiakou section, and the downstream portion of the Yang River main stream, faced serious environmental problems from heavy metals.