[Objective]The purpose was to study the modified effect of Na-montmorillonite on Cu, Zn, Pb and Cd in heavy metal polluted red soil. [Method]In the indoor experiment by constant temperature culture, with polluted red soil from the Guixi Copper Tailings in Jiangxi Province as samples, 5 treatments of adding 1%, 2%, 4% and 8% Na-montmorillonite and non-adding Na-montmorillonite were set up, the available heavy metal, Na+ in water extract, electric conductivity and pH in soil from each sample were measured and their correlations were analyzed. [Result]Adding 4% and 8% Na-montmorillonite could significantly decrease the contents of available Cu, Zn, Pb and Cd in heavy metal polluted red soil, being 33.8% and 40.2%, 33.2% and 37.2%, 28.4% and 32.7%, 35.7% and 34.5% lower than that in CK, resp ectively. Na+ in water extract, electric conductivity and pH in soils was gradually increased with the increase of Na-montmorillonite adding amount. [Conclusion]Analysis on the passivation mechanism showed that the addition of Na-montmorillonite in heavy metal polluted red soil could rise the pH value of soil and increase its adsorption properties, which made the heavy metal ions produce replacement reaction with Na+ in montmorillonite.%[目的]研究添加钠基蒙脱石对重金属污染红壤中Cu、Zn、Pb和Cd的改良效应.[方法]以采自江西贵溪铜尾矿污染红壤为样品,通过室内恒温培养试验,设5个处理(添加钠基蒙脱石0、1%、2%、4%、8%),测定处理后各样品的土壤有效态重金属含量、水浸提液的Na+、电导率及pH值,分析它们之间相关性.[结果]添加4%和8%的钠基蒙脱石能显著降低重金属污染红壤中有效态Cu、Zn、Pb和Cd的含量,与对照相比,分别降低33.8%和40.2%、33.2%和37.2%、28.4%和32.7%、35.7%和34.5%;随钠基蒙脱石添加量的增加,土壤水浸提液的Na+和电导率以及土壤的pH值逐渐升高.[结论]钝化机理分析表明,重金属污染土壤添加钠基蒙脱石使土壤的pH值升高,增加土壤的吸附性能,使重金属离子与钠基蒙脱石中的Na+发生了置换反应.
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