Spatiotemporal distribution patterns and risk characteristics of heavy metal pollutants in the soil of lead–zinc mines

Abstract

Abstract Background The current soil environmental assessment system is inadequate in terms of the spatiotemporal distribution of heavy metal pollutants. This study employed the numerical simulation technique to predict spatiotemporal distribution patterns of heavy metals within 50 days and to assess the soil risk characteristics of heavy metal pollution near a lead–zinc mine in Hunan Province, China. Results The spatiotemporal distribution results indicate that the soil in the sewage plant and mining areas served as the pollution center, exhibiting a ladder-shaped pollution diffusion trend outward. When the pollution migration time reached 20 days, pollutant migration and changes tended to remain stable, high-pollution areas exhibited no drastic changes within 10 m, and low-pollution and medium-pollution areas revealed obvious changes. Moreover, the low-pollution area width approached 2 m, the depth reached 2 m, the medium-pollution area width was close to 2.5 m, and the depth approached 4 m. The percentage of areas containing lead–zinc mine soil with high to extremely high risks reached 82.88%, and extremely high-risk farmland, mining and residential areas accounted for up to 100%, 95% and 90%, respectively, of the total area. Among the pollution sources, high-risk and extremely high-risk areas in regard to heavy metal Cd accounted for 13.51 and 49.55%, respectively, of the total area. Conclusion This study provides new insights into the migration patterns and risk characteristics of pollutants to address soil environmental assessment system problems.