Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Soil around Lead-Zinc Mining Area

The soil around a lead and zinc smelter in Hunan was taken as the research object. Geostatistics and multistatistics were applied to investigate distribution characteristics of Cd, Pb, As. Then the sources of three elements were explored and the potential ecological risk assessment of the region was conducted. The results indicate that average concentrations of Cd, Pb and As are 434.78, 2 908.27, 320.48 mg/kg, respectively, far exceeding their corresponding limits in National Soil Environmental Quality Standard. Results of spatial distribution maps show that there was a strong correlation between Cd, Pb and As and heavy polluted spots were concentrated in the residue deposit and residential areas, with pollution levels in the descending order as residue deposit residential areas unused areas vegetable field. The analysis of correlation among heavy metals elements indicate that Cd, Pb and As have homology. The cluster analysis show that Cd and As have more closer homology, and they are mainly from the smelter dust and sediment of Xiangjiang River. The potential ecological risk assessment result indicate that except vegetable field with a low value center, soils in other place were engaging in a severe potential ecological risk, especially residue deposit, where the potential ecological risk was the most serious.