天然和热活化蛇纹石对土壤镉赋存形态的影响

Effects of Natural and Thermal Activation Serpentine on Cadmium Formations in Contaminated Soil

以天然蛇纹石粉为原料,应用马弗炉制备不同温度（550℃和700℃）的热活化蛇纹石,通过室内培养试验,探究不同剂量（分别为土重的1%,3%,5%）的天然和热活化处理的蛇纹石对外源镉污染土壤中镉赋存形态的影响。结果表明,土壤pH值随蛇纹石用量增加而增加,随培养时间延长呈现先降低后趋于稳定的趋势,但均显著高于对照。高剂量700℃热活化蛇纹石对土壤pH值影响最大,培养60d时与对照相比提升了1.98个单位。添加天然蛇纹石、550℃和700℃热活化蛇纹石均能降低土壤可交换态镉的含量,与对照相比分别降低了17.42%-28.32%,28.99%-39.63%,33.11%-53.72%。相关性分析表明,各培养时期土壤可交换态镉的含量与土壤pH值呈现极显著负相关关系。各处理对土壤镉各形态含量的影响差异不同,显著降低了土壤可交换态镉的含量,不同程度地提高了碳酸盐结合态、铁锰氧化物结合态和残渣态镉的含量,对有机物结合态镉的影响并不明显。总的来说,蛇纹石添加入土壤后能够提高土壤pH值,促使可交换态镉向其他生物可利用性较低的镉形态转变,且不同剂量、不同热活化温度间存在显著差异。

The thermal activation serpentine was prepared by muffle furnace using natural serpentine powder as raw material at different temperatures（550 ℃ and 700 ℃）.A laboratory incubation experiment was conducted to study the effect of the natural serpentine and thermal activation serpentine on the transformation of cadmium（Cd）formations in exogenous cadmium polluted soil.The results indicated that the soil pH increased with the increasing amount of serpentine,with the extension of the training time the soil pH decreased at first and then kept stability,but for all that both of them were significantly higher than the control treatment.High doses of 700 ℃ thermal activation serpentine had the greatest impact on soil pH,compared with the control treatment it increased 1.98 units when cultured for 60 days.Compared with the control treatment,the application of the natural serpentine,550 ℃ and 700 ℃thermal activation serpentine reduced the concentration of soil exchangeable Cd to 17.42%-28.32%,28.99%-39.63% and 33.11%-53.72%,respectively.Correlation analysis showed that the concentration of exchangeable Cd and the soil pH showed significantly negative correlation.The addition of serpentine could significantly decreased the concentration of exchangeable Cd,improved the concentration of carbonate-bound,Fe-Mn oxidation-bound and residual-bound Cd,but the effect of organic-bound Cd was not obvious.Overall,the addition of serpentine could improve soil pH and promote exchangeable Cd shift to other formations which had lower bioavailability.