Spatial distribution, sources apportionment and risk assessment of heavy metals in the Changchun black soil area, China

The contamination of cropland with heavy metals poses a significant threat to human health and food security. Black soil, characterized by high organic matter content and associated with high grain yields, is particularly susceptible to heavy metal accumulation. Total of 99 surface soil samples were gathered from the Changchun black soil area in Jilin Province, in order to determine the spatial distribution, the sources, the pollution and risk assessment of seven toxic elements. The average concentrations of Cu, Ni, Cr and Cd are 1.15, 1.08, 1.22 and 1.19 times higher than the respective background values. The spatial variation of seven heavy metals demonstrated that Cu, Cd, and As exhibited significant spatial heterogeneity in the study area. Through spatial distribution and multivariate statistical analysis, the toxic elements Pb, Zn and Ni were mainly derived from a nature source, while Cd, Cr and As mainly comes from anthropogenic sources, with agriculture production and industrial transportation being the primary factors. By geo-accumulation index and the single factor index toxic metals showed that the accumulation of Cu, Cr and Cd in the soil were relatively high. Potential ecological risk and human health risk are at a low level overall, but there are still several points in Gongzhuling City with moderate ecological risk levels.