钙锌钾共存对赤红壤镉吸附的影响

Effects of co-existing cations,Ca,K and Zn on adsorption of cadmium in Lateritic red soil

采用等温平衡法,测定了钙、钾、锌单一或两两共存下赤红壤镉的吸附量,并应用Freundlich方程log[Cs]=logKf+nlog[Ce]分析了土壤镉的吸附特征。结果表明,与钠离子相比,Zn2+,Ca2+,K+共存均使赤红壤吸附镉的能力减弱,三种离子对分配系数Kf值的影响程度(设符号为y)的次序为y(Zn2+)<y(K+)≈y(Ca2+),锌离子降低土壤镉的吸附能力最强。钙锌、钾锌与钙钾共存也使赤红壤镉的吸附量降低,上述三种离子两两共存降低赤红壤镉吸附能力(设符号为y)的次序是y(锌钾)≈y(钙锌)>y(钙钾)。锌与钙、钾两两共存时,锌对降低赤红壤镉的吸附能力具有决定作用。

The effects of single and compound cations of Ca^2＋, K^＋ and Zn^2＋ on adsorption of cadmium （Cd） in lateritic red soil was measured by batch experiment. The results showed that the adsorption of Cd could be described by Freundlich equation （P〈0.01） well, and co-existing Ca^2＋, K^＋ and Zn^2＋ apparently decreased the adsorption of Cd with the order as follows according to partition coefficient （Kf）： Zn^2＋ 〈 K^＋≈Ca^2＋, which implied that Zn^2＋ had stronger ability to reduce the adsorption of Cd. At the same time, with co-existing binary cations of Ca^2＋, K^＋ and Zn^2＋, adsorption of Cd reduced with the order of K^＋-Zn^2＋=Ca^2＋-Zn^2＋ 〉 Ca^2＋-K^＋, among which Zn^2＋ played a crucial role in reducing the adsorption of Cd on lateritic red soil.