外源氮与钙强化产脲酶细菌固定土壤镉研究

廖桂; 李欣鞠; 李泽雨; 赵文佳; 周雨欣; 胡栋程; 杨刚; 马菁; 徐敏

doi:10.19336/j.cnki.trtb.2025071901

外源氮与钙强化产脲酶细菌固定土壤镉研究

Nitrogen and Calcium Addition Promoted Cadmium Immobilization in Soil by Urease-Producing Bacteria

摘要

摘要:
背景微生物诱导碳酸盐沉淀（Microbial induced carbonate precipitation，MICP）技术是一种利用产脲酶细菌代谢活动固定金属离子的生物修复技术，在土壤重金属修复领域具有较强的应用潜力。其中，尿素与钙是该过程重要的反应底物，影响其对金属离子固定效果，然而它们的用量对该过程的影响尚不清楚。
方法本文以镉（Cd^{2 +}）为研究对象，开展水体、土壤培养试验，以空白（CK）、菌添加（J）为对照，分析外源添加不同量的尿素（0 ~ 3.072%，w/w）、氯化钙（0 ~ 3.072%，w/w）对固定Cd的效果影响。
结果整体而言，尿素及钙源的添加均可显著提高Cd的去除效果，且Cd的去除率受尿素用量影响不大，而受钙源用量影响较大。当CaCl₂添加量为0.048% ~ 0.192%时，利用MICP去除Cd^{2 +}的效果最佳。仅添加尿素时，主要产生菱镉矿（CdCO₃，PDF#99-000-2764），以固定环境中的Cd^{2 +}；而当添加钙时，可刺激产脲酶细菌活性，并促进MICP过程，产生球霰石（CaCO₃，PDF#99-000-4172）与菱镉矿（CdCO₃，PDF#99-000-2764）固定Cd^{2 +}。尿素和氯化钙的添加均会影响氮素的转化，同时降低土壤磷的有效性。
结论通过外部添加氮及钙可有效调控产脲酶细菌活性，增强对Cd的固定，并激活土壤氮循环，研究结果可为土壤Cd的有效固定提供新思路。

Abstract:
Objective Microbial induced carbonate precipitation (MICP) is a bioremediation technology that utilizes the metabolic activities of urease-producing bacteria to immobilize metal ions, showing strong potential for application in the remediation of heavy metal-contaminated soil. Urea and calcium are key substrates influencing the metal ion immobilization efficiency in this process. However, the impact of their dosage on the MICP process remains unclear.
Method This study conducted solution and soil incubation experiments to explore Cd immobilization efficiency under different urea (0 ~ 3.072%, w/w) and calcium chloride (CaCl₂, 0 ~ 3.072%, w/w) dosages, using control (CK) and bacteria-only addition (J) as controls.
Results Overall, the addition of urea and calcium significantly improved the removal rate of Cd, which was less affected by the dosage of urea, but more affected by the dosage of calcium. Adding 0.048% ~ 0.192% CaCl₂ had the highest removal rate. When only urea was added, otavite (CdCO₃, PDF#99-000-2764) formed as the primary phase for immobilizing Cd²⁺. In contrast, adding calcium stimulated urease-producing bacterial activity, enhancing the MICP process. This resulted in the precipitation of both vaterite (CaCO₃, PDF#99-000-4172) and otavite (CdCO₃, PDF#99-000-2764) to fix Cd²⁺. Exogenous addition of urea and calcium chloride both affect nitrogen transformation and reduce the availability of soil phosphorus.
Conclusion The results demonstrate that applying nitrogen and calcium can effectively regulate urease-producing bacterial activity, enhancing Cd immobilization and stimulating the soil nitrogen cycle. These findings offer novel approaches for the effective immobilization of Cd in agricultural soils.

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