一种改性蒙脱石材料对农田污染土中重金属Zn的钝化应用研究

Application Research of Modified Montmorillonite for Passivation of Heavy Metal Zn in Polluted Farmland

利用合成的新型改性蒙脱石材料作为钝化剂,通过在重金属Zn污染土上的小白菜盆栽修复试验,研究其单独使用或与钠化膨润土混合使用时,对不同污染程度土壤中重金属Zn的钝化效果。结果表明:当按0.1%、0.5%、1%、2%比例施加单纯的新型改性蒙脱石材料时,可逐渐减少高污染土中水溶态Zn的含量,由于减少的并不显著,小白菜植株Zn富集量并未受明显影响,所以新型改性蒙脱石材料对高污染土钝化效果并不显著;当按0.1%、0.5%、1%、2%比例施加由新型改性蒙脱石材料与钠化膨润土组成的混合修复材料时,其对低污染土中重金属Zn的钝化效果要明显优于中、高污染土,同时盆栽研究结果还表明,污染土壤中,水溶态Zn含量依次为低污染土>中污染土>高污染土,且水溶态Zn在土壤含量是影响植物对Zn富集的主要因素,土壤中水溶态Zn含量越高,植物就越易富集土壤中的Zn元素。

In this research, a novel modified montmorillonite material was used as immobilizing agent, and the pot experiment of Chinese cabbage on the Zn-contaminated soil was carried out to study the passivation effects of the Zn-contaminated soil of different levels when it was used alone or mixed with the sodium bentonite. The results showed that the content of water soluble Zn in high-contaminated soil can be reduced gradually when the modified montmorillonite material was adding at the ratio of0.1%, 0.5 %, 1% and 2 %, because the decrease is not significant, the enrichment of Zn was not significantly affected in Chinese cabbage, so the modified montmorillonite material had no significant passivation effect on highly polluted soils. When the mixture material of the modified montmorillonite and sodium bentonite was adding at the ratio of0.1%, 0.5 %, 1% and 2 %, it was tbund that the passivation effect of heavy metal Zn in low-polluted soil was better than that in medium and high-polluted soils. Meanwhile, the results of pot experiment also showed that the content of water soluble Zn in contaminated soil was in the order of low-polluted soil 〉 medium-polluted soil 〉high-polluted soil, and the content of the water soluble Zn in the soil was the main factor that affected the enrichment ofZn for the plant. The higher was the content of water soluble Zn in the soil, the easier enrichment of Zn element for the plant.