Pollution Regionalization of Soil Heavy Metals in County Scale

The main objective of this study was to make a pollution regionalization of soil heavy metals in A city, an area with rapid economic development in Yangtze River Delta of China. Therefore, the spatial distribution of soil heavy metals was firstly estimated by optimal space method using 126 data points and performed using ArcGIS9.2 software. The areas of different content grade were computed by overlay analysis between the spatial distribution map and the administration map. Concentrations of heavy metals in each town, therefore, were calculated according to the weighted areas of different content grade. By the cluster analysis to each town´s multi-dimensional sample similarity index of heavy metals pollution, the city was divided into 5 preliminarily pollution zones. Then, 9 indicators were selected as pregnant pollution environmental factors. The forward four principal components were chosen by principal component analysis to these factors. According to agricultural production measure, agricultural equipment investment, industrial investment and environmental policy, the preliminary zones were further divided into 10 secondary pollution zones by cluster analysis to the four principal components. The regionalization methodology and results not only reflect the spatial distribution of soil heavy metals pollution, but also highlight the spatial differentiation of pregnant pollution environment.