丹江口水库迁建区土壤重金属分布及污染评价

为了解丹江口水库迁建区表层土壤重金属污染水平及其潜在的生态风险,对丹江口水库迁建区表层土壤中6种重金属(Cd、Pb、Cu、Zn、Cr、As)的含量及空间分布分别进行了研究,并分别采用综合污染指数法和潜在生态危害指数法对其中重金属污染程度及潜在生态危害进行了评价.结果表明,丹江口水库迁建区表层土壤中Cd、Pb、Cu、Zn、Cr、As的平均含量分别为0.61、23.11、58.25、22.65、58.99、16.95 mg.kg-1;与河南省土壤元素背景值及全国水系沉积物平均值相比,6种重金属元素除Zn外均有一定程度的富集,其中,Cd富集程度最为严重,重金属污染形势不容乐观.Cu、Zn、Pb的空间分布趋势基本相似.与国内典型的水库沉积物中重金属含量相比,丹江口水库迁建区表层土壤中Cd、As的富集程度较严重.6种重金属之间的相关性表明,元素Pb与Cu、Zn两两之间均呈显著性正相关性,Cr与Pb、As之间亦分别呈现显著的正、负相关关系.由2种评价方法可知Cd为丹江口水库迁建区表层土壤中最主要的污染元素,且具有较强的生态危害.

Distribution and Pollution Assessment of Heavy Metals in Soil of Relocation Areas from the Danjiangkou Reservoir

The aim of this article is to explore the pollution level and potential ecological risk of heavy metals in soil of the relocation areas from the Danjiangkou Reservoir. The contents and spatial distribution of Cd, Pb, Cu, Zn, Cr and As in soil of the relocation areas from the Danjiangkou Reservoir were analyzed. The integrated pollution index and potential ecological risk index were used to evaluate the contamination degree and potential ecological risk of these elements. The results indicated that the average contents of Cd, Pb, Cu, Zn, Cr and As in the samples were 0.61, 23.11, 58.25, 22.65, 58.99 and 16.95 mg·kg^-1,respectively. Compared with the background value of soils from Henan province, all these 6 elements except Zn were enriched to some extent, especially Cd. Similar patterns were observed for the spatial distribution of Cu, Zn, and Pb. Compared with the contents of heavy metals in surface sediments of the typical domestic reservoirs, Cd and As in soil of the relocation areas from the Danjiangkou Reservoir were heavily accumulated. The correlation analysis showed that there were significant positive correlations among Pb, Cu, and Zn. And there was also significant positive correlation between Cr and Pb. In contrast, negative correlation was found between Cr and As. To sum up, the comprehensive assessment results showed that Cd was the primary element with high ecological risk.