SPATIAL VARIABILITY AND DISTRIBUTION OF HEAVY METALS IN SOIL OF BAOSHAN DISTRICT

Geographical information system(GIS)combined with geostatistics method was applied to reveal the spatial variability of heavy metals including As,Cd,Cr,Hg and Pb in soils of Baoshan district,Shanghai city.All heavy metal elements displayed modest spatial variability.For the global trend,Cd is a single function,and the other four heavy metal elements are dual funtions.All heavy metal elements have obvious directional effect.Cr,Hg and Pb have strong spatial correlation,whereas As and Cd have moderate spatial correlation.The spatial variation of all heavy metal elements is in the order of Hg,Pb,Cr,As and Cd.The average content of As,Cd,Cr,Hg and Pb are 7.31,0.24,107.89,0.15 and 38.54 mg·kg-1 respectively,which are 0.80,1.81,1.44,1.43 and 1.51 times that of the soil background value for Shanghai.The pollution level of agricultural soil in the southern area of baoshan is worse than the northern area.For the pollution level of heavy metals in every town,Cr and Pb pollution is serious,but As is not an issue.In the dustfall survey same period,heavy metals in the dustfall are the most important sources for soil in Baoshan district.