Chemical and Bacterial Reactions at the Surfaces of Environmentally-Important Metal Sulfide Minerals: Linking Atomic and Field Scales

环境地球化学和生物地球化学项目的这一奖项由地球科学、化学、化学和运输系统工程部门联合支持。威斯康星大学麦迪逊分校地质系的Jillian F.Banfield和化学系的Robert J.Hamers将在原子水平上研究在水溶液和金属硫化物矿物表面之间发生的反应的性质。他们将使用多学科方法，结合生物、地质和化学因素，并整合各种实验方法的结果，包括扫描隧道显微镜、X射线光电子能谱和共聚焦显微镜。将同时进行实地和实验室研究。将把自然的无机和有机风化形成的表面与人工风化的矿物进行比较，以探索实验室研究对自然系统的适用性。研究的目标是确定金属硫化物表面的溶解、沉淀和离子吸附的机制和速率；电化学氧化和还原对表面形态的影响；杂质在表面电化学过程的修饰速率中的作用；以及细菌在控制表面微结构特征和溶解速率中的作用。矿物的化学风化是岩石转化为土壤和沉积物成分的过程。方铅矿、闪锌矿和黄铜矿等硫化物矿物被开采为铅、锌和铜等重要元素的来源，释放金属和酸化水。酸度的增加加速了其他矿物的风化。通过化学和细菌途径了解金属硫化物的溶解和结晶行为，对于建立金属形态和生物有效性的预测模型非常重要。这项研究的目标是提高对自然系统的理解，并开发准确的实验室测试和预测模型。

This award in the Environmental Geochemistry and Biogeochemistry Program is jointly supported by the Divisions of Earth Sciences, Chemistry, and Chemical and Transport Systems Engineering. Jillian F. Banfield, Geology Department, and Robert J. Hamers, Chemistry Department, of the University of Wisconsin-Madison will investigate at an atomic level the nature of reactions occurring at interfaces between aqueous solutions and surfaces of metal sulfide minerals. They will use a multidisciplinary approach, incorporating biological, geological and chemical factors, and integrate results from a wide array of experimental methods, including STM, XPS, and confocal microscopy. Parallel field and laboratory studies will be conducted. Surfaces formed as a consequence of natural inorganically- and organically-mediated weathering will be compared to synthetically-weathered minerals to explore the applicability of laboratory-based studies to natural systems. The goals of the investigation are to determine the mechanisms and rates of dissolution, precipitation, and ion adsorption at metal sulfide surfaces; the effect of electrochemical oxidation and reduction on surface morphology; the role of impurities in modifying rates of electrochemical processes at surfaces; and the role of bacteria in controlling surface microstructural characteristics and dissolution rates. Chemical weathering of minerals is the process by which rocks are converted into the constituents of soils and sediments. Sulfide minerals such as galena, sphalerite, and chalcopyrite are mined as sources of important elements, such as lead, zinc, and copper, releasing the metals and acidifying water. The increase in acidity accelerates weathering of other minerals. Understanding the dissolution and crystallization behavior of metal sulfides, by chemical and bacterial routes, is important to developing predictive models of metal speciation and bioavailability. The goal of this study is to improve understanding of natural systems and to develop accurate laboratory tests and predictive models.