油枯对镉污染土壤的钝化研究

Study on Passivation of Cd-contaminated Soil by Oil Cake

为了研究油枯对镉(Cd)污染土壤的钝化效果,以油枯为外源添加物(质量比:1%、2%、3%、4%、5%),模拟田间条件在塑料桶中进行为期45 d的培养,对镉污染土壤中Cd形态分布特征、DTPA提取态Cd(DTPA-Cd)含量、pH、有机质含量进行分析。结果表明,添加油枯可显著降低镉污染土壤中可交换态镉(Ex-Cd)的比例,提高碳酸盐结合态镉(Cb-Cd)、铁锰氧化物结合态镉(Fe-Mnb-Cd)以及有机质及硫化物晶格态镉(OMb-Cd)的比例,而残渣晶格结合态镉(RLb-Cd)变化不明显。添加油枯显著降低镉污染土壤中DTPA-Cd含量,降幅最高可达49%。镉污染土壤p H值维持在6.0左右,1%~4%添加处理中土壤pH波动幅度较大;而5%添加处理的土壤pH波动幅度小。添加油枯均能显著提高镉污染土壤中有机质含量。由此可见,油枯对镉污染土壤有较好的钝化效果,这为重金属污染土壤的修复和农业废弃物的循环利用提供了参考。

In order to study the passivation effect of oil cake,an experiment was conducted to simulate field environment for 45 days after added oil cake（ mass ratios of 1%,2%,3%,4% and 5%） to Cd-contaminated soil. The distribution characteristics of cadmium in cadmium-contaminated soil,DTPA-Cd content,organic matters content and soil pH were also measured at the end of incubation. The results showed that addition of oil can significantly reduce the proportion of exchangeable cadmium in cadmium contaminated soil. In contrast,the proportion of carbonate bound Cd（ Cb-Cd）,FeMn oxides bound Cd（ Fe-Mnb-Cd） and organic matter bound Cd（ OMb-Cd） were increased,and residue lattice bound Cd（ RLb-Cd） did not change significantly. The content of DTPA-Cd in cadmium contaminated soil was decreased by up to 49% after amended with oil cake. The pH value of cadmium contaminated soil was about 6. 0,with the larger fluctuation in 1% to 4% addition treatments and little fluctuation in 5% addition treatment. Oil cake addition enhanced Cd-contaminated soil organic matter content in all treatments. In short,the addition of oil cake can significantly increase the content of organic matter in cadmium contaminated soil. Therefore,oil cake is an effective soil amendment,which can provide references for remediation of heavy metals contaminated soil and cyclic utilization of agricultural waste.