Evaluation of heavy metal contamination in agricultural topsoils in suburban Xuchang City, China

Agricultural topsoils in suburban Xuchang City were analyzed to determine the concentrations of heavy metals (Mn, Cr, Ni, Cu, Pb and Zn). The contamination levels were evaluated using the geo-accumulation index, the enrichment factor and the integrated pollution index. According to the concentration and indices results, Mn, Cr and Ni exhibited non-contaminated levels and minor enrichment, with little to no contribution to the heavy metal contamination. Cu, Pb and Zn showed moderate contamination and enrichment, with moderately severe enrichment at several points. The variable intensities of human activities, such as the traffic flow and the number of industrial factories, explain the contamination levels between the sample sites.