土壤中固相腐植酸介导微生物远程还原U(VI)的机理研究

铀（U）是富铀煤矿及周边的重要污染物，对人体健康有潜在威胁。研究表明，土壤中固相腐植酸，与溶解态腐植酸一样，可介导强化微生物胞外电子传递的效率与距离，但其电子传递特性及介导微生物远程还原U(VI)的机理和贡献尚不清楚。本项目拟以伊犁富铀煤矿区铀污染土壤中固相腐植酸为研究对象，应用AFM-IR（原子力显微镜-红外光谱联用系统）对腐植酸颗粒官能团组成、理化性质进行纳米尺度空间成像，结合13C-NMR、电化学分析和微生物实验，研究固相腐植酸电子传递机制，揭示固相腐植酸对微生物远程还原U(VI)介导机理与贡献。研究内容包括：1）固相腐植酸颗粒结构与其电子传递特性的构效关系；2）固相腐植酸对微生物远程还原U(VI)的介导机理与贡献；3）土壤体系验证固相腐植酸对微生物远程还原U(VI)的介导作用。本研究可为铀污染土壤的环境风险评估及微生物修复提供思路和理论支撑。

Uranium is an important pollutant in uranium-rich coal mines and surroundings, which has potential threat to human health. Previous studies have shown that solid humic acids, like dissolved humic acids, can improve the efficiency and distance of microbial extracellular electron transfer via mediating electron transfer, but their electron transfer characteristics, and the mechanism and contribution of solid humic acids enabling long-distance electron transfer for microbial reduction of U(VI) are still unclear. In this project, solid humic acids from uranium contaminated soil in Yili uranium-rich coal mine area will be taken as the research object. AFM-IR (atomic force microscope-infrared spectroscopy) will be used, to image the functional group compositions and physicochemical properties of humic acids particles at nano-scale. Combining with the result of 13C-NMR, electrochemical analysis and microbial experiments, the electron transfer mechanism of solid humic acids will be elucidated, and the mechanism and contribution of solid humic acids enabling long-distance microbial reduction of U(VI) will be revealed. The research contents include: 1) structure-activity relationship between particle structure and electron transfer characteristics of solid humic acids; 2) mechanism and contribution of solid humic acids enabling long-distance electron transfer for microbial reduction of U(VI); 3) verifying the effect of solid humic acids on long-distance microbial reduction of U(VI) in soil. This study can provide ideas and theoretical support for environmental risk assessment and microbial remediation of uranium contaminated soil.