模拟酸雨对铅锌冶炼废渣重金属释放及生物毒性的影响

为评价酸雨淋洗对铅锌冶炼废渣中重金属释放及生物毒性的影响，以黔西北酸雨严重区域大量堆存的铅锌冶炼废渣堆场为研究对象，对照组以去离子水为浸提剂，分析不同粒径废渣在不同酸度模拟酸雨浸提下重金属的分布特征及生物毒性变化规律。结果表明，与对照相比，模拟酸雨均可不同程度降低铅锌废渣浸出液的pH，废渣粒径越小浸出液的电导率越高。模拟酸雨可提高铅锌冶炼废渣浸出液中Cu、Zn、Cd的浓度，相同条件下，浸出液中重金属浓度总体上随废渣粒径减小呈增加趋势。模拟酸雨可促进废渣中残渣态Cu、Pb、Zn向其他形态转化而增加铅锌废渣堆存的环境风险。进一步分析表明，废渣浸出液中Zn、Cd含量越高浸出液的生物毒性越大，而低浓度范围内废渣浸出液中Cu含量越高反而生物毒性越小。综上，模拟酸雨能促进不同粒径铅锌冶炼废渣中重金属离子的溶出释放、改变废渣中重金属的形态，并提高废渣浸出液的生物毒性，从而增大了铅锌冶炼废渣堆场的环境生态风险。

Effects of simulated acid rain on heavy metal release and biological toxicity of lead and zinc smelting waste residues

To evaluate the effect of acid rain leaching on the release of heavy metals and biotoxicity in lead-zinc smelting waste residue, a large amount of lead-zinc smelting waste yards piled in the severe area of acid rain in northwestern Guizhou was selected as the research object, and deionized water was used as an extractant in the control group to analyze the distribution characteristics of heavy metals under different acidity values in simulated acid rain leaching. Different sizes of waste residues and the law of biological toxicity were analyzed. The results show that, compared to the control, the simulated acid rain could reduce the pH value of the lead-zinc waste residue leaching solution to varying degrees; the smaller the particle size of the waste residue, the higher the electrical conductivity of the leachate. Simulated acid rain could increase the concentrations of Cu, Zn, and Cd in the extraction solution of lead and zinc smelting waste residues. Under the same conditions, the concentration of heavy metals in the extraction solution generally increased with the decrease in the particle size of the waste residues. The simulated acid rain could promote the transformation of residual Cu, Pb, and Zn in waste residues to other forms and increase the environmental risk of lead and zinc waste residue accumulation. Further analysis shows that the higher the content of Zn and Cd in the waste residue leaching solution, the greater the biological toxicity of the leaching solution, while the higher the Cu content in the waste residue leaching solution in the low concentration range, the less the biological toxicity. In summary, the simulated acid rain could promote the dissolution and release of heavy metal ions in lead and zinc smelting waste residues, changing the forms of heavy metals in waste residue and increasing the biological toxicity of waste residue leachate, thereby increasing the environmental and ecological risks of lead-zinc smelting waste residue yards.