丝状真菌生物对U(VI)在典型黏土矿物-水界面富集行为的调控机制研究

Fungal organisms are widely existing in various environmental systems, and have vital impacts on the environmental behaviors of radionuclides. However, the regulation mechanism of fungal organisms on radionuclides enrichment at clay-water interface is still unclear. In this proposal, typical clay minerals, (i.e., kaolinite, illite, and montmorillonite) and filamentous fungi (i.e., Aspergillus niger) are selected to predominantly study the sorption/desorption, redox, bio-mineralization, and occurrence states of U(VI) on clay, fungi, and fungi-clay combining batch, theory calculation, and spectroscopy approaches (such as extended X-ray absorption fine structure, X-ray photoelectron spectroscopy, and X-ray diffraction). The regulation mechanism of filamentous fungi on U(VI) accumulation at clay-water interface will be elucidated at a molecular scale, and finally a theory model will be constructed to describe and predict the accumulation process of U(VI) at a complicated system in the presence of fungi organisms. The findings can provide important and necessary supports to efficiently predict and evaluate uranium diffusion, migration, transformation behaviors.

真菌生物广泛存在于环境各个系统，可对放射性核素的环境化学行为产生至关重要的影响，然而真菌生物对放射性核素在黏土矿物-水界面富集行为的调控机制仍不清楚。本项目拟选取典型黏土矿物（高岭石、伊利石和蒙脱石）和丝状真菌生物（以黑曲霉为代表）作为研究对象，结合宏观实验、理论计算和微观谱学（如XRD、XPS和EXAFS等），从分子水平上研究不同环境条件下U(VI)在典型黏土矿物及丝状真菌-黏土矿物复合体上的吸附/解吸、氧化/还原、生物矿化等过程，剖析丝状真菌生物调控黏土矿物形貌、结构和吸附位点的方式和途径，阐明丝状真菌生物对U(VI)在黏土矿物-水界面富集行为的微观调控机制，构建可准确预测U(VI)在丝状真菌-黏土矿物复杂体系中的富集模型，为准确、有效地评价和预测环境介质中U(VI)的扩散、迁移、转化等环境化学行为等提供重要的理论基础。

真菌生物广泛存在于环境各个系统，可对放射性核素的环境化学行为产生至关重要的影响 ，然而真菌生物对放射性核素在黏土矿物-水界面富集行为的调控机制仍不清楚。本项目从分子水平上研究不同 环境条件下U(VI)在典型黏土矿物及丝状真菌-黏土矿物复合体上的吸附/解吸、氧化/还原、生 物矿化等过程，阐明了U（VI）在高岭石、伊利石、蒙脱石-黑曲霉复合体表面的吸附机制。主要取得以下进展和认识：1、U(VI)在各黏土矿物-黑曲霉复合体表面均为内层络合。2、U(VI)主要与复合体表面的羧基、酰胺基和磷酸基相结合而被固定。3、复合体中的黑曲霉可以将U(VI)部分还原为U(IV)。4、U(VI)的吸附使得蒙脱石-黑曲霉复合体中蒙脱石层间距缩小。总的来说，黑曲霉可显著改变U(VI)在黏土矿物表面的吸附过程和微观形态，进而调控U(VI)的环境行为，研究结果为准确有效评价和预测环境介质中U(VI)的扩散 、迁移、转化等环境化学行为等提供理论技术支持。