施用生物炭和石灰对土壤镉形态转化的影响

Effects of Biochar and Lime on the Fraction Transform of Cadmium in Contaminated Soil

通过室内培养试验，比较石灰、生物炭及生物炭和石灰配施3种改良剂作用下镉污染草甸土中土壤镉各形态转化以及pH的影响。结果表明，土壤添加生物炭培养60d，土壤pH呈随时间增加逐渐增加的趋势，而添加石灰和生物炭与石灰配施处理，土壤pH呈现先增加至最大值而后缓缓降低趋于稳定的趋势，但均显著高于对照。各改良剂的施用均显著降低土壤可交换态Cd含量。与CK处理相比，添加生物炭、石灰和生物炭石灰混合改良剂后，土壤可交换态Cd含量分别降低8．6％～13．7％，17．8％～21．7％和18．4％～23．3％。相关分析结果表明，土壤可交换态Cd含量与土壤pH之间均存在极显著的负相关关系（R^2=0．74）。土壤添加改良剂后，显著降低土壤可交换态Cd比例，增加碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态Cd比例，从而降低土壤重金属的生物有效性。

Lime and biochar was added into Cd contaminated meadow soil, then the incubation experiment was conducted to investigate pH and the various forms of transformation of heavy metal fractions after the application of amendments. The results turned out that during the 60 days, the soil pH increased with an in- crease in rates of biochar. However, soil pH increased with an increase in rates of lime and lime mix biochar, but decreased with incubation time till last of the incubation period. Soil pH in treatments with these amend- ments was all higher than that of the control. The application of different treatments also significantly re- duced the concentration of soil exchangeable Cd. Compared with CK, the amendment of biochar, lime and the complex of biochar and lime alleviated the concentration of Cd to 8.6%-13.7%, 17.8%-21.7% and 18.4%-23.3%, respectively. There were significant negative correlations between soil pH and concentra- tions of exchangeable Cd （R2= 0. 74）. Application of amendments accelerated the transformation of ex- changeable Cd into carbonate-bound, Fe-Mn oxides-bound, organic-bound, residual Cd by different levels.