纳米零价铁是地下水污染原位修复领域研究和使用最广泛的纳米材料。因其比表面积大，反应活性高以及独特的物化特性，纳米零价铁可以用胶体悬浮液形式直接注入受污染地下水中，实现简易高效原位修复。尽管纳米零价铁技术应用前景广阔，但其使用过程中的长期稳定性、反应活性和潜在的环境与健康风险等重要科学问题亟待解决（并且工程应用中不同修饰型纳米零价铁表面物化特性各异更增加了问题的复杂性和不确定性）。针对上述问题，本项目将系统考察不同表面修饰剂、天然有机物筛分结构对纳米零价铁胶体稳定性、反应活性和微生物毒性三要素的影响及其规律；着重探究不同表面改性纳米零价铁的物化特性、团聚及沉淀行为，与无机/有机污染物的界面反应机理和动力学，急性和慢性致毒剂量及致毒机理；最终揭示纳米零价铁胶体稳定性、反应活性和微生物毒性三要素之间的内在关联机制。期望在纳米零价铁地下水修复技术的应用及其环境与健康风险评估方面提供理论支撑。

Nanoscale zero-valent iron (nZVI) technology is becoming the most widely studied and used nanotechnology in in-situ groundwater remediation. Due to its large specific surface area, high reactivity and the other unique physicochemical properties, nZVI suspended in the aqueous phase can be conveniently injected into contaminated groundwater to overcome fatal shortcomings of many conventional technologies for effective in-situ remediation. While the use and development of nZVI are understandably heralded as a promising environmental nanotechnology, fundamental questions remain on its long-term stability, reactivity and health risks in the environment. Meanwhile, the application of nZVI with varying physicochemical properties in the environment would enlarge the complexity and uncertainty of the above mentioned problems. In this proposal, systematic experimental designs are outlined to investigate the influence of different surface modifiers and the isolated natural organic matter (NOM) fractions on colloidal stability, reactivity and microbial toxicity of nZVI particles under geochemical conditions relevant to in-situ groundwater remediation. Firstly, the physiochemical properties and surface chemistry of various types of nZVI will be characterized and analyzed to determine the mechanisms for the colloidal stability under varying conditions. Then, the interfacial reactions between the different types of nZVI and inorganic/organic pollutants and the kinetics of the reactions will be respectively investigated to gain insights into the mechanisms underlying the reactions between nZVI and the pollutants. Additionally, the dosage of nZVI for the acute/chronic microbial toxicity will be determined and the potential mechanisms of the microbial toxicity will be analyzed. Overall, a correlation among the colloidal stability, reactivity and microbial toxicity of nZVI modified with different surface modifiers and the NOM fractions will be identified. It is expected that the results of this project will provide a theoretical support for the application of nZVI technology in environmental remediation and the assessment of the environmental and health risks.