为了探索石灰水对混合试剂(MC)洗脱后土壤中重金属的淋洗效果,对重金属污染土壤进行了盆栽淋洗试验研究.结果表明:石灰水淋洗MC洗脱土壤,淋出液中Cd、Zn、Pb和Cu浓度均显著高于去离子水淋洗MC洗脱土壤,这主要由于石灰水提高土壤pH,释放土壤所吸附的络合态重金属,这种现象在酸性污染土壤中表现更明显.对于酸性污染土壤,可采用MC+石灰水+去离子水依次进行淋洗处理,其Cd和Zn去除率与MC+去离子水+去离子水依次淋洗处理相比提高22.6%和28.8%;对于中性重金属污染土壤,两处理间重金属去除率差异不显著.石灰水淋洗可提高土壤重金属去除率,并提高土壤pH,改善MC洗脱对土壤的酸化,有利于淋洗后土壤的农业利用.%A pot leaching experiment was carried out in order to study the effects of lime solution on mixture of chelators (MC) extraction of heavy metals from contaminated soil. The results showed that the concentrations of Cd, Zn, Pb and Cu in leachate were significantly increased with lime solution leaching MC-washed soil. The reason was that pH increase caused by lime solution decreased the adsorption of metal-ligand complex by the mineral surface, this phenomenon was more obvious in acid contaminated soil. Compared to the treatment with MC + deionized water + deionized water, the removal rates of Cd and Zn were increased by 22.6% and 28.8% respectively with leaching by MC + lime solution + deionized water in acid contaminated soil. However, the differences were not significant in neutral contaminated soil. This study suggests that soil leaching by lime solution can increase the removal rate of heavy metals and increase MC-washed soil pH, thus is in favor of the agricultural use of the washed-soil.
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