Spatial Variation of Heavy Metals in Soils of Zhengzhou Surburb and Their Origin

The concentrations of Cd,Hg,As,Pb and Cd in soils of Zhengzhou suburb were analyzed,and their spatial variations and origin were characterized with the aid of geostatistics,principle component analysis and Geographic Information System.Results showed that in the past over 10 years,the concentrations of heavy metals in soil increased slightly.In the case of spatial distributions,Hg and Cd in soils exhibited strong and moderately spatial-dependence respectively within the range of 6300 m and 5500 m.However,the concentrations of Pb,Cr and As in soils exhibited no spatial-dependence.The distribution of soil Cd could be viewed as the reflection of its background values.The variation of Cr concentration in soils were influenced mainly by input from outside but also affected by natural background values.The spatial variations of Pb,As and Hg concentrations in soils were induced mainly by anthropogenic activities.Apparently amongst of them,that of Hg were attributed to the differences of land use type.