两种产脲酶细菌固定Cd-As复合污染水稻土的研究

Cd and As immobilization in co-contaminated paddy soil using two urease-producing bacteria

微生物诱导碳酸盐沉淀(Microbial induced carbonate precipitation,MICP)是新兴重金属生物修复技术,具有绿色、高效的特点。本研究以镉(Cadmium,Cd)-砷(Arsenic,As)复合污染的水稻土为研究对象,以空白(CK)、尿素添加(UREA)为对照,分析巴氏芽孢杆菌(SP)和蜡样芽孢杆菌(BC)两种细菌对Cd、As的固定效果,并探讨修复后土壤性质及酶活性的变化。结果表明:与CK处理相比,BC处理下CaCl_(2)-Cd、CaCl_(2)-As含量分别显著降低30.2%、9.10%。与CK处理相比,SP、BC处理显著降低可氧化态Cd含量,且增加残渣态Cd含量;而仅BC处理显著降低可氧化态As含量,并显著提高残渣态As含量;且UREA、SP、BC处理下碳酸盐含量均增加。与CK处理相比,UREA、SP、BC处理下脲酶活性,分别显著提高48.0%、32.8%、11.7%,表明3种处理均能刺激MICP过程。与CK处理相比,SP、BC处理可有效提高土壤全氮、全磷、全钾、铵态氮含量,降低硝态氮含量,表明MICP过程不仅提升土壤养分,而且刺激氨化作用,抑制硝化作用。与CK处理相比,BC处理可显著提高磷酸酶、蔗糖酶活性,有效调节土壤生态功能。研究表明,蜡样芽孢杆菌在修复Cd-As复合污染土壤方面具有明显优势,可有效降低Cd、As的有效性,且提升土壤肥力和酶活性,是一种优良的生物修复材料。

Microbial-induced carbonate precipitation(MICP)is a technology for heavy metal bioremediation with the main advantages of being environmentally friendly and effective.In this study,we explored the effects of Sporosarcina pasteurii(SP)and Bacillus cereus(BC)on cadmium(Cd)and arsenic(As)immobilization,soil properties,and soil enzymatic activities in a Cd and As co-contaminated paddy soil under control(CK)and urea addition(UREA)treatments.The results of this study might assist in reducing the risk of agricultural soils containing both Cd and As.CaCl_(2)-Cd and CaCl_(2)-As were significantly reduced by BC treatment compared to CK treatment,by 30.2%and 9.10%,respectively.Compared with CK treatment,SP treatment and BC treatment significantly reduced oxidizable Cd and increased residual Cd,while only BC treatment significantly reduced oxidizable As and increased residual As.With the addition of UREA,SP,and BC treatments,the carbonate content was increased.UREA,SP,and BC treatment significantly increased urease compared to CK treatment by 48.0%,32.8%,and 11.7%,respectively,indicating that these treatments stimulated the process of MICP.Compared to CK treatment,SP treatment and BC treatment considerably increased soil total nitrogen,total phosphorus,total potassium,and ammonium nitrogen,but decreased nitrate–nitrogen,which implied that the MICP method helped enhance soil fertility and stimulated ammonization but inhibited nitrification.BC treatment enhanced soil phosphatase and sucrase in comparison to CK treatment,improving soil function.Taken together,B.cereus immobilized Cd and As,enhanced soil fertility,and increased enzyme activity,making it a promising candidate for bioremediation,particularly for soil that had been contaminated with both Cd and As.