银川平原饮用地下水健康风险评价及风险控制研究

Study on Health Risk Assessment and Risk Control of Drinking Groundwater in Yinchuan Plain

以地下水污染调查数据为基础,运用健康风险评价模型,对银川平原饮用地下水中25种化学污染物饮水暴露途径的健康风险进行初步评价,结合优先控制污染物的分布特征,提出相应的风险控制措施。结果表明,银川平原饮用地下水存在不同程度的致癌和非致癌健康风险,致癌风险值介于国际上最严格风险尺度1×10 -6 和最宽松风险尺度1×10 -4 之间的地下水比例为50.6%,大于1×10 -4 的地下水比例为14.5%,砷、铅、Cr(Ⅵ)、氟等无机污染物的健康风险大于苯、三氯乙烯、甲苯、1,2-二氯乙烷、1,1-二氯乙烯等有机污染物,其中,砷的致癌和非致癌风险率分别为47.3%、8.6%,远大于其他物质,是银川平原地下水的优先控制污染物;高砷地下水主要呈条带状分布于黄河近岸及冲洪积平原前缘地区,以天然成因为主,浅层水中砷含量高、波动较大,深层水中砷含量低且稳定;通过改进成井工艺、分层开采承压水和优化开采量等技术手段可实现对高砷风险水体的控制,加强污染源管理和水质监测预警是实现可持续风险管理的必要手段。

Based on the survey data of groundwater pollution, the health risk assessment model was used to preliminarily evaluate the health risk of 25 kinds of chemical pollutants in drinking groundwater in Yinchuan Plain, and put forward the corresponding risk control measures based on the distribution characteristics of priority control pollutants.The results showed that drinking groundwater in Yinchuan Plain had different levels of carcinogenic and non-carcinogenic health risks. The proportion of groundwater with carcinogenic risk between the strictest risk scale 1×10 -6 and the loosest risk scale 1×10 -4 internationally was 50.6%.The proportion of groundwater greater than 1×10 -4 was 14.5%.Health risks of arsenic, lead, Cr (Ⅵ), fluoride and other inorganic pollutants was more than benzene, trichloroethylene, toluene, 1, 2 - dichloroethane, 1, 1-2 vinyl chloride and other organic pollutants.Among them, the carcinogenic and non-carcinogenic risk rate of arsenic was 47.3% and 8.6% respectively, which was much higher than other substances and was the priority control pollutant of groundwater in Yinchuan plain.The high-arsenic groundwater was mainly distributed in banding areas near the Banks of the Yellow River and the front edge of the alluvial-diluvial plain. The arsenic content in shallow water was high and fluctuated greatly, while the arsenic content in deep water was low and stable.The control of high arsenic risk water can be achieved by improving well completion technology and optimizing exploitation quantity.Strengthening pollution source management and water quality monitoring and early warning are necessary means to realize sustainable risk management.