Heavy Metal Pollution and Its Assessment in Urban Soil of Guiyang City

At the five functional areas in Guiyang City,namely,industrial,commercial,administrative,cultural and educational as well as residential areas,the heavy metal pollution in soil was tested and evaluated with the pollution index method.The potential ecological hazard from the heavy metal pollution was assessed with potential ecological hazard index method by Hakanson.The result indicated that the contents of heavy metals in soil in the central city were quite different,the contents of heavy metals in the industrial area were relatively high,and in the commercial area were relatively low.Comprehensive pollution index with the value of 1.95 indicated the soil was lightly polluted by heavy metals;the residential area with the highest value was seriously polluted,the cultural and educational area with the lowest value was on alert;the other three functional areas were lightly polluted.From the single pollution index,the industrial,commercial,and administrative areas were mainly As-based,the residential area was mainly Hg-based,while heavy metal pollution in soil in the cultural and educational area was lower than the stipulated pollution level.Ecological risk index with the value of 148.01 showed that Hg was the main factor to cause potential ecological hazard,and the residential area had the highest ecological hazard.