γ-聚谷氨酸改性生物炭对镉污染土壤的修复作用

Remediation of Cadmium Contaminated Soil byγ⁃Polyglutamic Acid Modified Biochar

为了强化生物炭对镉污染土壤的修复作用,采用γ-聚谷氨酸对玉米秸秆生物炭进行活化改性,采用扫描电镜和红外光谱对γ-聚谷氨酸改性生物炭的结构进行表征,通过模拟土壤镉污染试验,探究γ-聚谷氨酸改性生物炭对Cd^(2+)的钝化效果。结果表明,γ-聚谷氨酸改性生物炭的羟基和羧基官能团数量显著增加。与施加1.0%原始生物炭处理相比,在镉污染土壤中施加等量的γ-聚谷氨酸改性生物炭处理,其土壤的阳离子交换量、有机质含量及土壤磷酸酶、过氧化氢酶和脲酶的活性均显著提高,分别提高9%、17%、18%、15%、20%;土壤中残渣态Cd的含量增加15%,弱酸可提取态Cd的含量降低27%,土壤中Cd^(2+)的生物有效性明显降低;种植的小白菜根和叶中Cd^(2+)含量显著降低。综上,γ-聚谷氨酸改性可以提高生物炭钝化土壤中镉的能力,γ-聚谷氨酸改性生物炭在镉污染土壤修复中极具潜力。

In order to strengthen the remediation effect of biochar on cadmium-contaminated soil,γ-polyglutamic acid was used to activate and modify corn straw biochar.The structure ofγ-polyglutamic acid modified biochar was characterized by scanning electron microscopy and infrared spectroscopy.The passivation effect ofγ-polyglutamic acid modified biochar on Cd^(2+)was investigated by simulating soil cadmium pollution test.The results showed that the number of hydroxyl and carboxyl functional groups ofγ-polyglutamic acid modified biochar increased significantly.Compared with the application of 1.0%original biochar,applying equal amount ofγ-polyglutamic acid modified biochar in cadmium-contaminated soil significantly increased the soil cation exchange capacity,organic matter content,soil phosphatase,catalase and urease activities by 9%,17%,18%,15%and 20%,respectively.The content of residual Cd in soil increased by 15%,the content of weak acid extractable Cd decreased by 27%,and the bioavailability of Cd^(2+)in soil decreased significantly.The content of Cd^(2+)in roots and leaves of Chinese cabbage decreased significantly.In summary,γ-polyglutamic acid modification can improve the ability of biochar to passivate cadmium in soil,andγ-polyglutamic acid modified biochar has great potential in the remediation of cadmium contaminated soil.