耐镉细菌与土壤胶体作用对镉形态的影响

【目的】探讨耐镉细菌对红壤、赤红壤和棕色石灰土3类型土壤胶体镉吸附性能的影响及细菌—土壤胶体复合体上所吸附镉形态的变化,为重金属污染土壤的生物修复提供理论依据。【方法】从矿区镉污染土壤中筛选分离出一株耐镉细菌,同时提取红壤、赤红壤和棕色石灰土3种土壤胶体,研究接种耐镉细菌后3种土壤胶体吸附镉的变化及细菌—土壤胶体复合体上所吸附镉形态的变化。【结果】接种耐镉细菌能提高3种土壤胶体对镉的吸附,以红壤有机—无机复合胶体的提高幅度最大;接种耐镉细菌使3种类型土壤胶体上弱酸可溶态和残渣态的镉含量降低,而可还原态和可氧化态含量则提高。接菌后,红壤胶体和赤红壤（自然土）无机胶体上不同形态镉含量为残渣态〉可还原态〉弱酸可溶态〉可氧化态,而赤红壤（耕作土）胶体和棕色石灰土胶体则为可还原态〉残渣态〉弱酸可溶态〉可氧化态。【结论】接种耐镉细菌能促进土壤胶体上镉形态由无效态向有效态转化,提高镉的有效性。

Effect of cadmium resistant bacteria and soil colloids on the forms of cadmium

【Objective】The present study was conducted to explore the effect of cadmium resistant bacteria on cadmium adsorption property of red soil, lateritic red soil and brown calcareous soil colloids, and transformation of Cd forms of bacteria -soil colloid complex, and to provide theoretical basis for bioremediation of heavy metal contaminated soils. 【Method】A cadmium resistant bacteria was selected from heavy metal contaminated soil in a mining area, three colloids of red soil, lateritic red earth and brown calcareous soil were extracted to find out the effect of cadmium resistant bacteria on cadmium adsorption, and transformation of Cd forms of bacteria-soil colloid complex. 【Result】Cd adsorption capacity of three soil colloids increased significantly after inoculating cadmium resistant bacteria, and the range of increase in inorganic and organic colloidal complex in the red soils was the highest, while the contents of soluble weak acid and residual Cd form of three soil colloids reduced after inoculation in contrast to contents of reducible and oxidizable Cd form. After inoculating cadmium resistant bacteria, the content of different Cd forms on natural lateritic red earth colloid and red soil colloid were as follows： residual formreducible formweak acid soluble formoxidable form. However, the content of Cd forms on farming lateritic red earth colloid and brown calcareous soil colloid were： reducible formresidual formweak acid soluble for oxidizable form. 【Conclusion】Cadmium resistant bacteria could promote transformation of Cd forms on bacteria soil colloid complex from unavailable forms to bioavailable forms, and improve the effectiveness of cadmium.