土壤固相不同组分对镉、锌吸持的研究

EFFECT OF DIFFERENT SOIL COMPONENTS ON THE RETENTION OF CADMIUM AND ZINC

本文选用三种不同类型的土壤,用连续提取法依次去除土壤固相中碳酸盐(石灰性土壤)、氧比锰、有机质、无定型氧化铁和晶型氧化铁组分,制得分离某一组分或某几个组分后的土壤钙饱和的样品,藉此研究土壤固相各组分对重金属Cd和Zn吸持的影响.研究结果表明.不同土壤去除某一组分或多个组分后对Cd和Zn吸持的影响是下同的.土壤固相中组分的相互作用可能是其主要原因.

The effect of different soil solid components on the retention of Cd and Zn was investigated by equilibrating standard solutions(pH = 7) of Cd and Zn with soil fractions devoid of given soil solid components at constant temperature. The soil fractions were prepared by use of sequential extraction method, and then saturated with Ca. The soils used in this paper were chao soil (calcareous), red soil (acid) and a neutral paddy soil. The soil: solution ratio in the adsorption experiments was 1:10. Results obtained were summerized as follows:The adsorption isotherms of Cd and Zn on all soil samples were fitted quite well by Freundlich equation. No definite trend concerning the effect of a given soil solid component on the retention of Cd and Zn could be found. In general,the retention ability of chao soil for Cd and Zn decreased gradually as the sequential extraction of the soil proceeded. The relation was reversed in case of red soil. For paddy soil,the original soil had the strongest retention ability,followed by the fraction devoid of Mn oxides,organic matter and Fe oxides,and then the fraction devoid of Mn oxides and organic matter. And the fraction without Mn oxides showed the lowest retention ability for Cd and Zn.It seemed that the retention ability of soil was determined largely by the interactions among soil solid components. Both the interactions among soil solid components and the effect of a given component on the retention of Cd and Zn were different for different soils.