Spatial Variability Characteristic of Soil Heavy Metals Due to Industry Development of Typical Regions in Yangtze River Delta of China

This study attempts to evaluate the spatial variability characteristic of soil heavy metals in different industrial types. Therefore, concentrations of heavy metals in soils with different distances from solid, liquid and gas point source and nonpoint source were measured in Yixing, an area with intensive industrialization in Yangtze River Delta of China. The results show that 1) the enrichment of heavy metals in soils around point source is strong and concentrations of heavy metals in soils around solid point source are the highest, followed by liquid, and gas is relatively low. The types of enrichment element depend on the types of point source. Concentrations of heavy metals in soils with distance are significantly decreased. And affected by the prevailing wind, the area influenced by gas point source is the largest, followed by solid, and liquid is relatively small; 2) compared with point source, the enrichment of heavy metals in soils around nonpoint source is relatively weak, but its element types are complex. There are no significant changes of concentrations of heavy metals in soils with distance, but the influenced area is larger; and 3) affected not only by the prevailing wind direction, but also by industry layout, concentrations of soil heavy metals around nonpoint source are of difference in different directions. Due to the complexity of the enrichment element´s types of soil heavy metals and their combined effect in nonpoint source, the spatial variability is more complex. It means that taking effective measures to control nonpoint source is especially difficult.