胡敏酸改性膨润土钝化污染土壤Pb&Cd及机理

Mechanism of Humic Acid Modified Bentonite for Immobilizing Lead & Cadmium in Contaminated Soils

通过盆栽试验,探讨了胡敏酸改性膨润土对重金属铅、镉污染土壤的钝化效果及机理。结果表明,铅、镉污染土壤中施加胡敏酸改性膨润土能显著降低小白菜中Pb、Cd的含量,在添加Cd(3 mg/kg)/Pb(250 mg/kg)污染土壤和Cd(1 0 mg/kg)/Pb(5 00 mg/kg)污染土壤上小白菜地上部分Pb含量分别比对照降低19.08%和47.91%,Cd含量分别比对照降低9.79%和14.89%。土壤本身对添加的重金属Pb/Cd有一定的耐受力和自我净化能力,在添加重金属后,添加的Pb/Cd元素大部分直接转化为较为稳定的碳酸盐结合态和铁锰氧化结合态。相关性分析显示小白菜的鲜重与小白菜Pb/Cd含量极显著负相关,进一步说明胡敏酸改性膨润土是通过提高小白菜的生物量,从而降低Pb/Cd在小白菜中的含量。

A pot experiment was carried out to investigate the immobilization effect and mechanism of Pb＆Cd in contaminated soils by humic acid modified bentonite. The results showed that the humic acid modified bentonite added into contaminated soils significantly inhibited the cabbage on the absorption and accumulation of Pb, Cd. In Cd （3 mg/kg） / Pb（250 mg/kg） soil and Cd（10 mg/kg）/Pb（500 mg/kg） soil, the Pb content of the cabbage shoot above-ground reduced by 19.08% and 47.91% compared with the control, the Cd content of the cabbage shoot above-ground reduced by 9.79% and 14.89% compared with the control. Soil had certain tolerance and self purification ability to the heavy metal Pb/Cd. Pb/Cd which added to the soil directly transformed into the stable carbonates state and Fe- Mn oxide state. Correlation analysis showed that fresh weight and Pb/Cd content of cabbage had negative correlation significantly, which indicated that humic acid modified bentonite reduced the Pb/Cd content from the cabbage through the improvement of the growth.