Prediction of heavy metal contamination in soil-groundwater systems at contaminated sites

The diffusion of heavy metal pollutants in polluted industrial areas can cause severe environmental pollution in surrounding areas. However, the migration of pollutants into groundwater is a complex process that requires consideration of local geological and hydrological conditions, solute transport, and geochemistry factors to better predict the flow paths and plume dispersion of pollutants. This study is based on numerical models of Darcy's law and the Richards equation. A numerical model is used to predict the pollution risk of a certain abandoned metallurgical site. The results indicate that the risk of heavy metal leaching is extremely high under natural conditions, potentially affecting downstream reservoirs after 1500 days. The use of permeable reactive barriers (PRBs) can effectively prevent the migration of heavy metals. However, even with PRBs, 28%-30% of pollutants may still continue to spread outward through lateral flow pathways. The use of impermeable Funnel-and-gate PRB design can effectively reduce lateral pollutant migration, reducing lateral leakage by up to 27%. Based on these results, the rational design of PRBs can effectively reduce remediation costs and time, enhance groundwater remediation effectiveness, and provide strong support for environmental protection and ecological health.