潮白河流域土壤重金属生态风险评价方法研究

Ecological Risk Assessment on Heavy Metals in Surrounding Soils of the Chaobai River Drainage Area

为了研究潮白河流域某段土壤重金属环境质量现状及潜在生态风险评价,系统采集了42件土壤样品,对其7种重金属(Cu、Pb、Zn、Cr、Ni、Cd和As)进行了测试分析,利用《土壤环境质量标准》评价土壤重金属污染现状,并参考北京市土壤重金属背景值,采用环境质量指数与环境潜在生态危害指数、内梅罗综合指数法相结合的方法,探讨土壤中7种重金属的累积污染现状及潜在生态风险。研究表明,土壤样品中Cu、Zn、Cr含量超标分别为97.62%、100%、100%;Cu、Zn、Cr含量重度污染等级以上的分别占2.38%、2.38%、4.76%;潜在生态危害指数法评价表明,Cu、Zn、Cr含量处于轻微生态危害等级分别占97.62%、100%、100%,Cu含量2.38%处于强生态危害等级。内梅罗综合指数法评判表明,所有样点均已污染,其中达到轻度污染、中度污染、重度污染的样点分别占28.57%、42.86%、28.57%;而潜在生态危害指数法评价显示土壤样品点中97.62%处于轻微生态风险等级,根据悲观原则可以判断该段流域重金属污染均处于轻度污染以上。

In order to study the environmental quality of some heavy metals in soil of the Chaobai River basin and potential ecological risk assessment, according to 'Soil Environmental Quality Standards' and soil background values of heavy metals in Beijing, seven kinds of heavy metals(Cu, Pb, Zn, Cr, Ni, Cd and As) from soil samples were tested to evaluate of soil heavy metal pollution. Using environmental quality and environmental potential ecological risk index, and combining Nemerow index method, this paper analyzed cumulative pollution situation and potential ecological risks about seven heavy metals. The research results have shown that Cu, Zn, Cr contents exceeds the standards of 97.62%, 100%; Cu, Zn, Cr accounting for 2.38%, 2.38%, 4.76% at the heavy polluted level or more respectively. Potential ecological risk index evaluation shows that Cu, Zn, Cr contents account for 97.62%, 100%, 100% at slight polluted level, Cu content of 2.38% belongs to the strong polluted level. Nemerow index evaluation shows that all samples have been contaminated, which reached slightly polluted, moderately polluted, heavily polluted levels accounting for 28.57%, 42.86%, 28.57%. The potential ecological risk index shows that 97.62% samples are polluted at slight level. So we consider pessimistically that the heavy metal pollution in the Chaobai River basin is at least light pollution.