膨润土对轻度镉污染土壤钝化修复效应研究

通过盆栽和大田小区试验，研究了膨润土对Cd 污染土壤修复效应。结果表明，盆栽和大田条件下施用膨润土后土壤Cd 交换态含量分别较对照降低了41.3%~86.1%和7.9%~24.6%，铁锰氧化物结合态（OX）和残渣态（RES）Cd 含量则有所上升。水稻各部分Cd 含量总体上随膨润土投加量的增加而降低，与对照相比，盆栽条件下根、茎、叶、糙米中Cd 含量最大降幅分别达到46.0%、49.8%、54.2%和71.8%，大田小区条件下水稻各部分Cd含量最大降幅分别达到35.3%、48.8%、36.0%和40.9%。投加不同浓度膨润土后，水稻幼苗叶片SOD 酶活性和可溶性蛋白含量在一定程度上有所促进，而POD酶活性和MDA含量则表现为明显的抑制效应（P<0.05）。在盆栽和大田实验中，施用膨润土显著提高土壤过氧化氢酶活性（P<0.05），与之相反，在盆栽实验中，土壤Cd 蔗糖酶活性较对照处理显著降低（P<0.05），降幅达44.3%~52.3%，而大田条件下各处理间差异不显著（P>0.05）；脲酶活性随膨润土施加量的增加呈现出先降低后增加的趋势。

Immobilization and Remediation of Low-level Cd Contaminated Soil Using Bentonite

Pot experiments and field trials were conducted to investigate the effects of bentonite on immobilization and remediation of lowlevel Cd contaminated soils. The results showed that under pot and field experiments the concentrations of exchangeable Cd after applied bentonite to soils decreased by 41.3%~86.1% and 7.9%~24.6%, respectively, when compared with the control group, while the contents of Fe-Mn oxides(OX)and residual(RES)fraction of Cd were increased. Cd concentration in the parts of Oryza sativa L. decreased with the increment of bentonite, with the maximal Cd reduction of 46.0%, 49.8%, 54.2%and 71.8%, respectively under pot experiment and of 35.3%, 48.8%, 36.0%and 40.9%, respectively under field experiments in roots, stems, leaves and brown rice in contrast to the CK. SOD and soluable protein(SP)in leaves of rice seedlings was enhanced to some extents, but POD and MDA were significantly inhibited(P<0.05). The ac tivities of catalase were remarkably increased under bentonite treated soils(P<0.05). On the contrary, the invertase activity in pot exper iments was significantly prohibited(P<0.05), with the reduction of 44.3%~52.3% in comparison with the control. However, there was no significant difference among the treatments of bentonite under field trials(P>0.05). The activities of urease first decreased and then increased with the increasing of bentonite contents.