龙南稀土矿区周边水体污染特征及风险评价

Characterization and Risk Evaluation of Pollution in Water Bodies Surrounding Longnan Rare Earth Mining Area

为研究龙南稀土矿区地表水和地下水污染物迁移规律及污染成因机制,开展了矿区周边地表水、地下水水质现状监测工作,对研究区周边地表水、地下水中pH、硫酸盐、硝酸盐、亚硝酸盐、氨氮浓度进行分析测定,运用改进内梅罗综合污染指数法和健康风险评价模型对水体污染程度及不同年龄段人群健康风险进行评估。结果表明:地表水料坑处的综合污染指数最高,达到54.19,属于严重污染程度;关西翰岗桥处综合污染指数最低,仅为2.119,属于较清洁程度;料坑、黄沙河和临塘一处理站下游的综合污染指数均达到严重污染程度;地下水采样点综合污染指数均达标,水质清洁。健康风险评价结果表明:研究区地表水及地下水中的硝酸盐对人体造成的健康风险较大,亚硝酸盐与氨氮次之;经非致癌健康风险计算,饮用地下水和地表水对不同年龄人群的影响程度为幼儿>青年>成人,因此应对龙南稀土矿区周边0~6岁幼儿用水安全给予更多关注。

In order to study the migration and formation mechanism and pollution causes of pollutants in surface water and ground water in Longnan rare earth mining area,the present situation of surface water and ground water quality around the mining area was monitored.The pH value and concentrations of sulfate,nitrate,nitrite and ammonia nitrogen in surface water and ground water around the study area were analyzed and determined.The improved Nemero composite pollution index method and health risk assessment model were used to assess the pollution degree and health risk of different age groups.The results show that the highest Composite Pollution Index(CPI)of 54.19 is found at the surface water pit,which is a serious pollution level.The lowest CPI of 2.119 is found at the Hangang Bridge in Guanxi,which is a cleaner level.The integrated pollution index of the downstream of the treatment station in the material pit,Huangsha River and Lintang has reached the serious pollution level.The integrated pollution index of the ground water sampling points have reached the standard,and the water quality is clean.The results of the health risk evaluation show that nitrate in surface water and ground water in the study area poses a greater health risk to human beings,followed by nitrite and ammonia nitrogen.After the calculation of the non-carcinogenic health risk,the impact of drinking ground water and surface water on people of different age groups is that young children>young people>adults,so more attention should be paid to the safety of the water used by young children aged 0-6 years old in the vicinity of the Longnan rare earth mining area.