Collaborative Research: Stable isotope investigation of Fe oxide reactivity and natural isotope fractionation

众所周知，铁会改变其氧化状态，例如，金属铁(Fe0)会迅速氧化成铁锈？以Fe3+氧化物和氢氧化物的形式存在。相反的情况可能会发生，例如，微生物过程可以将Fe3+氧化物和氢氧化物矿物还原为Fe2+矿物或水溶液。这些变化被称为？氧化还原？转变，深刻影响氧化铁和氢氧化物颗粒的反应性，进而可能通过吸收特性的变化极大地改变碳、氮和磷等元素的行为。氧化还原转变影响氧化铁和氢氧化物矿物的反应性，特别是在纳米颗粒(定义为直径在纳米范围内的颗粒？十亿分之一米)。现在人们认识到，纳米粒子普遍存在于环境中，是化学反应发生的主要方式之一。由这项合作拨款支持的工作将把来自地质和工程的研究人员和学生聚集在一起，应用一种独特的同位素方法来了解纳米粒子氧化铁和氢氧化物的反应性。通过研究铁的不同同位素(54Fe、56Fe和57Fe)的光谱性质和相对丰度，本工作将为环境中两种非常常见的铁矿物针铁矿和磁铁矿的化学反应活性的变化提供指纹。这项工作将研究颗粒大小和化学成分对颗粒反应性的影响。这些结果反过来将直接应用于古气候、环境修复、农业实践和水质研究。

Iron is well known to change its oxidation state, where, for example, iron metal (Fe0) rapidly oxidizes to ?rust? in the form of Fe3+ oxides and hydroxides. The reverse may occur, where, for example, microbial processes may reduce Fe3+ oxide and hydroxide minerals to Fe2+ minerals or aqueous solutions. These changes, termed ?redox? transformations, profoundly affect the reactivity of iron oxide and hydroxide particles, which in turn may dramatically change the behavior of elements such as carbon, nitrogen, and phosphorus through changes in the absorption properties. Redox transformations affect the reactivity of iron oxide and hydroxide minerals, particularly in nanoparticles (defined as particles that have diameters in the nanometer range ? one-billionth of a meter). It is now recognized that nanoparticles are ubiquitous in the environment and represent one of the major means by which chemical reactions occur.The work supported by this collaborative grant will bring together researchers and students from geology and engineering, applying a unique isotopic approach to understanding the reactivity of nanoparticulate iron oxides and hydroxides. By studying the spectral properties and relative abundance of the different isotopes of Fe (54Fe, 56Fe, and 57Fe), this work will provide a fingerprint for changes in chemical reactivity of the minerals goethite and magnetite, two very common iron minerals in the environment. The work will study the impact of particle size and chemical composition on particle reactivity. These results will in turn have direct application to studies of paleoclimate, environmental remediation, agricultural practices, and water quality.