Simulation experiment analysis of heavy metal migration in layered tailings soil by phytoremediation under rainfall conditions

To explore the possibility of heavy metal copper migration in layered soil on groundwater pollution, this study simulated the longitudinal migration law of heavy metal copper in layered remediation tailings soil under different rainfall intensity conditions of surface vegetation and different leach liquid pH values by means of the soil column leaching test. The results showed that copper in the layered soil migrated longitudinally due to leaching. The concentration of copper in the leached solution from the outlet of each soil column increased from top to bottom, and that increased with the increase of copper concentration in the soil. When the pH value of the leach liquid was less than 7, the pH value of the leach liquid from each soil column outlet increased from top to bottom. Surface vegetation, rainfall intensity and pH of leach had an effect on the concentration of heavy metal copper in leach. Within the range of suitable rainfall intensity, the concentration of heavy metal copper in the leached liquid increased with the increase of rainfall intensity. The concentration of heavy metals in the leached liquid of the soil column with vegetation was higher than that of the water outlet except the overflow outlet after rainfall leaching. When the pH value of the leach liquid was less than 7, the concentration of heavy metals in the leach would increase with the decrease in the pH value of the leach liquid, and the acidic leach liquid would promote the precipitation of heavy metals in the leach. The research results provided a theoretical basis for controlling soil pollution and groundwater pollution in actual tailings ponds.