某集中式饮用水源地保护区土壤重金属监测与评价

采用现场采样与室内测试方法测定了某大型集中式饮用水源地一级保护区土壤中Cd、Hg、As、Pb、Cr、Cu、Zn和Ni的含量,利用污染指数法、地累积指数法和潜在生态指数法对其土壤环境质量进行了评价。结果表明,上述8种重金属都存在不同程度的超标,其中Cd超标最为严重。地累积指数法评价结果表明,研究区只有Cd、Hg存在一定污染,污染程度分别为中度污染到强污染、中度污染和中度污染到强污染。潜在生态指数法结果表明:研究区土壤样品Cd的单因子潜在生态风险指数最高,轻微、中等和较高风险等级中所占比例分别为44.7%、23.7%、31.6%;其次为Hg,有89.5%的土壤样品中Hg处于轻微生态风险水平,10.5%的土壤样品处于中等生态风险水平;土壤样品中As、Pb、Cu、Ni、Zn、Cr都处于轻微生态风险水平。Cd是研究区最主要的污染和生态风险因子,其次是Hg,说明集中式饮用水源地保护区土壤已受到个别重金属的影响。虽然目前尚不存在饮用水源地水体受污染问题,但应引起高度关注。

Monitoring and Evaluation of Heavy Metals in Soil around the Major Centralized Drinking Water Sources

In order to investigate the metals concentration and their potential ecological risks in soil, the total elemental concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn and Ni in the topsoil around the major centralized drinking water sources was analyzed by field sampling and laboratory analysis, and the soil environmental quality was evaluated by pollution index method, geoaccumulation index method and potential ecological index method. The experimental data indicated that the concentration of all above 8 heavy metals was exceeded the standard in different degree, in which Cd was the most serious. The results of geoaccumulation index showed that there was a certain pollution of Cd and Hg in the study area, and the pollution level was moderate pollution to strong pollution, moderate pollution and moderate pollution to strong pollution, respectively. The potential ecological risk of soil calculated by E_Rⁱ revealed that the potential ecological risk index of Cd was the highest, and the proportion of mild, medium and high risk was 44.7%, 23.7% and 31.6%, respectively. The second was Hg, with 89.5% soil samples under mild Hg risk and 10.5% under medium risk. As, Pb, Cr, Cu, Zn and Ni in the samples were all in mild risk. The above results revealed that the soil of research area was polluted, and Cd, Hg were the key factors for the metal pollution in soil. Although the water of the major centralized drinking water sources was clean currently, but it should be paid high attention.