长江三角洲典型地区土壤中重金属的污染评价

POLLUTION ASSESSMENT OF SOIL HEAVY METALS IN A REPRESENTATIVE AREA OF THE YANGTZE RIVER DELTA REGION

以长江三角洲典型地区张家港市为例,运用不同评价标准和方法评价土壤中Cd,Hg,Pb,Cu,As和Cr的污染现状,探讨了不同评价标准和方法评价结果的异同.结果表明,以国家土壤环境质量二级标准为标准,Hg,Cu和Cd出现超标,但超标率都很小.以环境背景值为标准,六种元素超标的样点数明显增加.以环境背景值为标准,元素污染指数比地积累指数更能反映外源污染物导致的土壤中重金属的富集状况,而元素潜在生态风险指数则能反映Cd和Hg等对生态系统的危害风险.在六种元素综合污染评价上,内梅罗综合污染指数(P)和多金属综合生态风险指数(RI)对土壤的污染评价总体趋势反映一致.

An intensive soil sampling with total of 547 topsoil samples（0—15cm）was carried out in county, The characteristics of the heavy metal contents were described and the heavy metal po Zhangjiagang llution assessment results were compared in terms of different assessment guidelines and methods. The results indicated that the soil environment quality in Zhangjiagang county was good as a whole and only a few samples had Hg, Cu and Cd contents being greater than guide values （2nd level）of Soil Environmental Quality Standard of China （GB 15618-1995 ）. When the local soil environment background values （LSEBV） were used as the guidelines, the number of samples being greater than the LSEBV significantly increased for soil Hg, Cu, Cd, Pb, As and Cr. Based on the LSEBV, the individual pollution indexes of heavy metals had a better indication of accumulation of the heavy metals due to the heterogenous inputs than the geo-accumulation indexes did, while the individual potentially ecological risk indexes indicated the ecological risks of toxic dements such as Cd and Hg very well. As regard to the integrated pollution assessment, the Nemerow integrated pollution index and multi-element potentially ecological risk index reflected the similar results.