降雨条件下植物修复分层尾矿土壤重金属迁移的模拟分析

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

  • 摘要: 为探究分层土壤中重金属铜迁移对地下水的污染规律,通过土柱淋滤试验方法模拟表层植被、不同降雨强度、不同淋滤液pH条件下分层修复尾矿土壤中重金属铜的纵向迁移规律。结果表明,重金属铜会因为淋滤作用在分层土壤中纵向迁移,各土柱出水口淋出液的重金属铜浓度从上到下呈增加趋势,淋出液中重金属铜浓度随土壤中重金属铜浓度的增加而增加;当淋滤液pH<7时,各土柱出水口淋出液的pH值从上到下呈增加趋势;表层植被、降雨强度及淋滤液pH对淋出液中重金属铜的浓度有影响;在适宜降雨强度范围内,淋出液重金属铜的浓度随淋滤强度增大而增大;表层覆有植被的土柱降雨淋滤后各出水口(除溢流口外)的淋出液重金属浓度较大;当淋滤液pH<7时,各出水口淋出液的重金属浓度随淋滤液pH值的减小而增大,酸性淋滤液会在一定程度上促进淋出液重金属的析出。研究结果为控制实际尾矿库土壤污染和地下水污染提供理论基础。

     

    Abstract: 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.

     

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