不同钝化剂对贵州典型黄壤重金属有效态的影响

Effects of different passivating agents on the effective state of heavy metals in typical yellow soil in Guizhou

【目的】研究不同钝化剂对贵州典型黄壤重金属有效态的影响,筛选出钝化重金属效果较好的钝化剂,为以土壤类型划分的重金属污染钝化修复提供理论依据。【方法】采集贵州典型农田黄壤为研究对象,选取6种材料[玉米秸秆生物炭(CB)、烟杆生物炭(RB)、腐植酸(HA)、菌渣(MR)、蒙脱石(MM)和凹凸棒石(AP)]为土壤重金属钝化剂,设计添加量为0.5%、1.0%、3.0%和5.0%,以不添加钝化剂作对照(CK),通过室内培养试验,采用DTPA浸提法测定土壤重金属有效态含量。【结果】添加CB、RB、MR和AP均能显著提高土壤pH(P<0.05),而添加HA的土壤pH随添加量的增加呈下降趋势;添加量为5.0%时,土壤pH表现为MR=AP=RB>CB>MM>HA。6种钝化剂在不同添加量下对重金属有效态均有不同程度的影响,降低Pb有效态含量的效果依次为3.0%RB>3.0%AP>5.0%CB>5.0%HA>3.0%MM>5.0%MR,分别降低61.2%、26.7%、18.9%、11.5%、8.5%和6.8%。Cd有效态含量降幅最高达24.0%,各处理钝化效果依次为3.0%MM=0.5%AP>1.0%RB>5.0%HA>5.0%CB>5.0%MR,分别降低24.0%、24.0%、20.0%、16.0%、12.0%和8.0%。【结论】针对贵州典型Pb污染黄壤可选用3.0%烟杆生物炭作为修复剂,Cd污染黄壤可选用3.0%蒙脱石作为修复剂,而1.0%烟杆生物炭可作为复合重金属(Pb、Cd)污染土壤修复剂。

【Objective】The effects of different passivating agents on the effective heavy metal state of typical yellow soil in Guizhou were studied,the passivating agents with better passivating effect of heavy metals were selected,it provided a theoretical reference for the passive remediation of heavy metal pollution divided by typical yellow soil in Guizhou.【Method】The typical farmland acquisition of Guizhou yellow soil as the research object,selecting six different materials: corn stover biochar(CB),tobacco stem biochar(RB),humic acid(HA),mushroom residue(MR),montmorillonite (MM),attapulgite(AP)as the soil heavy metal passivators,the design addition amounts were 0.5%,1.0%,3.0% and 5.0% respectively,no passivator was as control(CK)treatment. Through laboratory culture test,DTPA leaching method was used to determine the effective state of heavy metals.【Result】Results showed that adding the passivators CB,RB, MR,MM and AP could significantly increase the soil pH(P<0.05),but pH of soil decreased as HA amount increased. When the concentrations of all passivators were 5.0%,the pH value was MR=AP=RB>CB>MM>HA. Six different passivator effective state under different concentrations affected effective state of heavy metals to various extents. The effects on lowering Pb active state content were 3.0% RB>3.0% AP>5.0% CB>5.0% HA>3.0% MM>5.0% MR,which decreased respectively 61.2%,26.7%,18.9%,11.5%,8.5% and 6.8%. The highestcontent of effective state of Cd was 24.0%. The passivation effects of the treatments were 3.0% MM=0.5% AP>1.0% RB>5.0% HA>5.0% CB>5.0% MR,decreased respectively 24.0%,24.0%,20.0%,16.0%,12.0% and 8.0%.【Conclusion】Based on the results,for typical Pb contaminated yellow soil in Guizhou,3.0% tobacco stem biochar can be selected as the remediation agent,3.0% attapulgite can be used as repair agent for Cd-contaminated yellow soil. However,1.0% tobacco stem biochar can be used as the remediation agent for composite heavy metal(Pb,and Cd)pollution soil.