3种不同功能区绿地土壤Cd和Hg的污染现状及其风险评价

在调查研究工业区、交通区和公园绿地土壤重金属Cd和Hg含量的基础上．对其污染程度进行了评价．结果表明：重金属Cd在工业区和交通区绿地土壤中的平均含量接近，均约为国家环境质量背景标准值的2倍，但在公园绿地土壤中没有明显的积累现象；与Cd不同的是重金属Hg在3种不同功能区中均有明显的积累现象．尤其是公园土壤中重金属Hg的含量为国家背景值的4倍。采用单项污染指数评价法对2种重金属的污染程度进行评价表明，工业区、交通区、公园绿地土壤中Hg的重度污染分别占28％、25％和50％，Cd的重度污染则分别占30．0％、37．5％和0％。通过种子发芽指数评价法进行评价得知．重金属对植物造成影响有一临界值，其含量只有超过该临界值才能对植物造成毒害，小于其临界值时对植物的影响不明显，但关于该临界值的确定还有待进一步研究。

The Pollution Status and Risk Assessments of Cd and Hg in Green-belts Soils from Three Different Functional Areas

Based on the contents of Cd and Hg of the green-belts soils from industrial districts,traffic areas and parks,the green-belts soils were evaluated for heavy metal pollution.The results showed that the average contents of Cd in the green-belts soils from industrial districts and traffic areas were similar,which were twice more than its background values.However,no significant Cd accumulation occured in green-belts soils from the parks.And,compared with Cd,the significant pollution of Hg occurred in green-bel...