[Heavy metals content and pollution risk assessment of cropland soils around a pesticide industrial park].

By the method of concentric circle distribution method, a total of 183 topsoil samples were collected from 30-km2 area around a pesticide industrial park in south Jiangsu Province, with the content and pollution index of soil Cd, Cr, Cu, Ni, Pb, Zn, Hg and As analyzed. The average contents of Hg, Cu, Cd, and Pb in the top soils were higher than those of the natural background values, and the contents of Hg and Cu were the highest. Taking the national standard II as the assessment criterion, the average pollution index values of Cd, Cr, Cu, Ni, Pb, Zn, and As in the top soils were all below 1, while those of the Hg and Cu were 1.59 and 1.05, respectively. In the southeast and northwest to the pesticide industrial park, soil heavy metals contamination was more serious, and, with the increasing distance to the park, the contents of soil Cd, Ni, Pb, Cr, As, Hg, Zn, and Cu increased first and then decreased to a stable level. The comprehensive pollution index of test metals indicated that the areas 200-1000 meter around the industrial park were of high risk in soil heavy metals contamination, while the areas 1000 meter beyond were safety. By using geostatistics and GIS, it was found that the pollution index of the eight heavy metals had significant spatial variability. Based on the principal component analysis and correlation analysis, it was speculated that the Zn, Ni, Cr, Pb, and As were mainly from soil parent materials, while the Hg, Cu, and Cd were mainly related to human activities.