生物炭对镉污染土壤中镉形态的影响及其钝化效果

Effects of Biochar Application on Different Chemical Forms of the Pedologic Cadmium and Its Passivation Effect

通过在镉污染的土壤中施用不同用量的生物炭，测定了镉污染的土壤中镉4种化学形态（酸交换态、Fe-Mn氧化结合态、有机结合态、残渣态）含量的变化，初步探讨了生物炭对土壤镉污染的钝化效果。结果表明．施生物炭后的土壤镉酸交换态含量下降了6．58％～17．34％．Fe-Mn氧化结合态含量下降了46-32％。53-40％。有机结合态含量升高了17．33％-67．24％，残渣态含量下降了20．00％-57．60％。施用生物炭可有效改变土壤镉的化学形态．降低镉的生物有效性，减轻镉污染的危害，有效提高酸性土壤的pH。施用生物炭后．各处理生菜镉含量均超过无公害蔬菜要求，但各处理间生菜镉含量没有显著差异。

Through applying different dosage biochar on the cadmium contaminated soil, the changes of the contents of cadmium and its four chemical forms （acid-exchangeable fraction, Fe-Mn oxides fraction, organic fraction, residual fraction） were studied. The results showed that the contents of acid-exchangeable fraction were decreased by 6.58%-17.34%. The contents of Fe-Mn oxides fraction were decreased by 46.32%-53.40%. The contents of organic fraction were increased by 17.33%-67.24%. The contents of residual fraction were decreased by 20.00%-57.60%. Biochar application improved chemical fraction of cadmium and decreased the bio-availability of cadmium. The pH values were improved by biochar application. The cadmium contents of Lactuca sativa in different plots were higher than the level of GB 18406.1-2001, with no significant difference between the plots.