Evaluation of Heavy Metal Pollution in Representative Vegetable Soils in Nanjing Based on GIS

The contents of heavy metals(Pb,Cr,Cu and Cd) in vegetable soils in Baguazhou Town,Nanjing were investigated to evaluate soil environmental pollution of heavy metals by using different evaluation standards of heavy metal pollution for comparison,furthermore,the spatial distribution of pollution index was analyzed with the aid of geographical information system(GIS) technology and potential sources of heavy metal pollutants in vegetable soils were also elucidated.The results showed that the soils were polluted with heavy metals Pb,Cr,Cu and Cd according to natural background values as evaluation standard,While using National Standard(GB 15618-1995) as evaluation standard,soils were not polluted with heavy metals Pb,Cr,Cu except Cd.However,integrated pollution index of soil heavy metals is 1.5 so that the whole studied soils show a slight pollution.It was preliminarily concluded that the chemical industrial areas of Nanjing,the Second Nanjing Changjiang Bridge and agricultural actions may be the major causes leading to soil heavy metal pollution.