Characteristics and risk assessment of soil heavy metal pollution in a coal mining area in North Henan Province

To study the degree and risk status of heavy metal pollution in soil of typical coal mining areas in North Henan Province, the content of heavy metals Cd, Pb, Cu, Zn, As, and Hg in soil is measured, and their pollution characteristics are analyzed. The potential ecological risk index method is used to evaluate their risk status, and the sources and spatial distribution characteristics of heavy metal pollution are analyzed using the correlation number method and Kriging interpolation method. The results indicate that heavy metals in soil samples from the study area belong to strong and moderate variability, and are significantly influenced by human factors. The content of six heavy metals exceeds the regional soil background value, with Cd and Pb being the most polluted. The high-risk screening values for Cd, Pb are 56.25%, 6.25%, respectively, indicating a severe pollution situation. The heavy metals with low, relatively high, high, and extremely high ecological risk levels are Cd and Hg, Zn, As and Cu, and Pb, respectively. The potential comprehensive ecological risk index of the research area is 892.86, which is at a very high risk level. The spatial distribution characteristics of Cd, Pb, As, and Hg have significant similarities, all gradually decreasing from south to north. It is recommended to focus on the ecological risks and pollution prevention and control of Cd and Pb.