不同淋洗剂对不同性质污染土壤中镉的浸提效率比较

Comparison of Extraction Efficiency for Cadmium by Different Extractants in Different Kinds of Contaminated Soil

以三种外源添加Cd的低污染土壤(酸性、石灰性和高有机质土壤)为研究对象,对比了两种螯合剂,两种酸性溶液对Cd的浸提效果。结果表明,螯合剂的浸提效率高于酸性溶液,并呈现出EDTA>EDDS>柠檬酸和HCl的顺序。三种土壤上,在0.05~0.20 mol L-1的浓度范围内,EDTA和EDDS随浓度的升高对Cd的浸提效率差异不显著,表明螯合剂在过量的情况下并不能显著提高Cd的浸提效率;而柠檬酸和HCl对Cd的浸提效率随浓度的升高而增加,尤其在石灰性土壤上,浓度的升高极显著地提高了浸提效率。外源添加Cd污染土壤上Cd浸提效率极显著高于田间无污染土壤。研究结果显示EDTA用于Fe、Ca含量均较低的土壤效果更好,EDDS宜用于有机质和黏粒含量均较低的土壤,而柠檬酸和HCl宜用于酸性土壤。

The extraction efficiency for cadmium(Cd) from low Cd contaminated soils(acidic, calcareous and high organic matter soils) artificially added was compared between two chelators and two acidic liquids. Results indicated that extraction efficiency by chelator was greater than that by acidic liquids, and it decreased in the following order:EDTA > EDDS > citric acid and HCl. In the range of 0.05 mol L- 1to 0.20 mol L- 1, the difference in Cd extraction efficiency was not significant with the increase in the EDTA and EDDS concentrations, which indicated that excess amounts of chelators did not enhance the extraction efficiency for Cd. Extraction efficiency for Cd by citric acid and HCl increased with the rise of solution concentration, especially in a calcareous soil, which showed the greater extraction efficiency was achieved by higher concentrations. Furthermore, significantly higher extraction efficiency for Cd was also obtained in artificially contaminated soils than in uncontaminated field soils. These results suggested that the good extraction efficiency was taken with EDTA in low Fe and Ca soils, with EDDS in less organic matter and clay soils, and with citric acid and HCl in acidic soils.