土壤镉污染化学修复方法研究

Study of Chemical Remediation on Cadmium Pollution in Soil

镉污染现在已经成为中国的"阿喀琉斯之踵",深圳、广州市场抽检的大米镉超标达四成之多。严重威胁人民的食品安全。本文尝试用CaCl2、CaCl2+细铁粉及CaCl2+活性炭三种方法对镉污染土壤进行修复。CaCl2+铁粉同时使用能够大大降低土壤中生物有效态镉含量,说明土壤中有效态镉含量与铁粉的使用密切相关,同时也达到修复土壤的目的。此外,用CaCl2溶液修复结果和用CaCl2+活性炭修复结果比较,后者并没有明显的显示出优越性。用CaCl2+铁粉进行试验,CaCl2能和土壤中的镉离子形成复杂化合物,而铁粉能将镉离子还原成不易被吸收的金属态,从而降低土壤中可交换态和有机结合态的镉含量。

We used Calcium chloride,calcium chloride mixed with iron powder and calcium chloride mixed with activated carbon to extract Cd or remediate soil from Cd-contaminated soil. When we chose calcium chloride and iron powder washing the sample,the bioavailable Cd obviously decreased,which indicated that the reduction of the bioavailable Cd were closely associated with the use of iron powder and it could restore Cdcontaminated soil. In addition,the method of calcium chloride and activated carbon didn`t display a superiority of calcium chloride on the remediation of cadmium pollution. Washing with calcium chloride led to the formation of Cd chloride complexes,while iron could restore Cd2 +to metallic state which couldn`t be absorbed by plants. This method could finally reduce the concentration of the exchangeable and organic bonded Cd.