Low-temperature mineralogy in groundwater systems

必须保护地下水资源不受自然和人为污染源的威胁。 为了保护这一资源，我们必须了解潜在的污染物如何从其来源地区通过地质材料（土壤，基岩，沙子，砾石，粘土等）迁移到含水层。 众所周知，大多数污染物的迁移是通过这些地质材料中矿物颗粒表面发生的化学反应而减缓的。 这项研究旨在提高我们对这些反应的认识，从而更好地了解污染物迁移的控制。 有两个主要目标：1）开发分析（扫描）透射电子显微镜技术，可以提供新的洞察矿物的化学性质和它们形成的地球化学环境，2）将亚微米尺度的确定性低温矿物学调查与地下水地球化学调查相结合，以更好地了解地下水地球化学的固相控制。在纳米尺度上测量和绘制矿物中金属价态的新方法的发展将在地球科学和一般材料科学中具有广泛的应用。 在地球科学中，这项工作将有益于从高温火成岩和变质岩的氧化还原状态的研究，到低温风化过程中的氧化还原状态的研究。 它也将揭示新的光规模的重要性时，集成水的地球化学，矿物学和数值模拟技术的目的是预测地下水系统的地球化学演化。

Groundwater resources must be protected against threats from natural and anthropogenic sources of contamination.  In order to protect this resource, we must understand how potential contaminants migrate from their source areas through geologic materials (soils, bedrock, sand, gravel, clay etc) toward aquifers.  It is known that the migration of most contaminants is slowed by chemical reactions that occur at the surface of mineral grains in these geologic materials.  This research is designed to improve our knowledge of these reactions, and thereby gain a better understanding of controls on the migration of contaminants.     There are two principal objectives: 1) develop techniques for analytical (Scanning) Transmission Electron Microscopy that can provide new insight into chemical properties of minerals and the geochemical environment in which they form, and 2) integrate sub-micron-scale determinative low-temperature mineralogical investigations with groundwater geochemical investigations in order to better understand the solid-phase controls on groundwater geochemistry. The development of new methods for measuring and mapping metal valence in minerals at the nano scale will have broad application within the geosciences, and in material sciences in general.  In the geosciences, this work will benefit research ranging from investigations of the redox state of high temperature igneous and metamorphic rocks, to studies of redox state during low temperature weathering processes.  It will also shed new light on the importance of scale when integrating aqueous geochemical, mineralogical, and numerical modeling techniques for the purpose of predicting the geochemical evolution of groundwater systems.