关键词: 长江三角洲, 农田, 重金属, 土壤污染, 评价方法, 常熟

Abstract: With the process of industrialization and modernization moving on,soil pollution in developed areas has become a problem that calls for much concern.How to assess the soil environment quality of this area rationally and properly is now a research topic that deserves study and discussion.Based on discussions about meanings of the background values,determination methods and evaluation criteria of soil environment,contents of seven heavy metals(Cd,Hg,As,Pb,Cr,Cu and Zn)in the soils of Changshu,a typical city in the Yangtze River Delta,were investigated through field sampling and laboratory analysis.Heavy metal pollution of the soils was evaluated with the environmental background values of the soils of Changshu and Grade Ⅱ Criterion of GB 156181995 as benchmarks.Phenomena were found of the concentration of the seven heavy metals in the soils being beyond their respective background values.Especially for Hg,Pb,Cr,Cu and Zn,their overstandard rates varied from 10% to 20%.And heavy metals,Cd,Pb,Cu,Zn and Hg,were found beyond Grade Ⅱ Criterion of GB 156181995 in concentration,and Hg in particular was overstandard in about 30% of the soil samples.As and Cr,however,were not overstandard.The results suggest that it is more advisable to use both of the standards in assessing soil environment quality for a better understanding of the status of heavy metal pollution in the soils investigated.

Key words: Yangtze River Delta, cropland, heavy metal, soil pollution, evaluation method, Changshu