DEFINING THE IMPACT OF ION SUBSTITUTION ON MICROBIAL REDUCTION CAPACITY

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 原位刺激异化铁还原菌（DIRB）作为一种有效的环境修复手段受到了广泛关注。DIRB将有机碳的氧化与Fe（III）（氢）氧化物的还原结合起来，从而产生Fe（II）。然后，铁（II）可以与溶液中的污染物一起沉淀，或将可溶性氧化还原活性金属还原至其不溶性还原状态。微生物Fe（III）还原的研究一致地揭示了Fe（III）（氢）氧化物的还原能力最小或减小。基于初步调查，我们假设，固有的Fe（III）相的结构和组成特征是负责其妥协的反应性。特别是，Fe（III）被外来离子取代将改变Fe相的溶解度和反应性，导致Fe（III）还原能力降低和相对于纯Fe（III）相的生物矿化途径改变。因此，本研究的目的是定义四种常见的Fe（III）（氢）氧化物相（水铁矿，纤铁矿，针铁矿，赤铁矿）的Fe（III）还原和二次矿化反应的速率含有一系列共沉淀离子（铝，锰，镍，硅）在DIRB（希瓦氏菌腐败CN 32）和非生物还原剂（亚铁）的存在下。本研究的一个关键组成部分是定义的命运或Fe（II）和还原后形成的第二相的Fe（III）作为一个功能的初始Fe（氢）氧化物结构和取代离子的组成和浓度。考虑到污染物的运输是一个功能的Fe（III）（氢）氧化物基板的还原能力，产生的Fe（II），和第二相沉淀的命运（反应性），这项研究将提高我们的预测能力的潜在成功的Fe（II）为基础的修复方法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The in situ stimulation of dissimilatory iron-reducing bacteria (DIRB) has received considerable attention as an effective means of environmental remediation. DIRB couple the oxidation of organic carbon to the reduction of Fe(III)(hydr)oxides resulting in the generation of Fe(II). Iron(II) can then precipitate with contaminants in solution or reduce soluble redox-active metals to their insoluble reduced states. Investigations of microbial Fe(III) reduction have consistently revealed either a minimal or diminished reductive capacity of Fe(III) (hydr)oxides. Based on preliminary investigations, we hypothesize that structural and compositional characteristics inherent to the Fe(III) phases are responsible for their compromised reactivity. In particular, substitution of Fe(III) by foreign ions will alter the solubility and reactivity of Fe phases resulting in a diminished Fe(III) reduction capacity and altered biomineralization pathway relative to pure Fe(III) phases. Thus, the objective of this research is to define the rates of Fe(III) reduction and secondary mineralization reactions of four common Fe(III) (hydr)oxide phases (ferrihydrite, lepidocrocite, goethite, and hematite) containing a range of co-precipitated ions (Al, Mn, Ni, Si) in the presence of DIRB (Shewanella putrefaciens CN32) and an abiotic reductant (ferrous Fe). A critical component of this research is to define the fate or Fe(II) and the secondary phases formed following reduction of Fe(III) as a function of the initial Fe (hydr)oxide structure and the composition and concentration of substituted ions. Considering that contaminant transport is a function of the reducing capacity of Fe(III)(hydr)oxide substrates, the fate (reactivity) of generated Fe(II), and secondary phase precipitation, this research will enhance our predictive capability of the potential success of Fe(II)-based remediation approaches.