Metal-mineral interactions in dynamic redox environments

点击翻译按钮获取中文摘要

Minerals control the distribution, transport, and bioavailability of metals in soils, sediments, and aquifers. Understanding interactions between metals and minerals is therefore critical because many metals support important biological functions but are potentially hazardous at higher concentrations. Iron (oxyhydr)oxide minerals are particularly important due to their high capacity for metal uptake and common occurrence near Earth's surface. These minerals are relatively stable in the presence of oxygen; however, declining oxygen availability can lead to reactions that decrease their stability and affect metal retention. These reductive reactions have implications for biogeochemical metal cycling on a global scale. The overall research objective is to determine how changing environmental conditions affect the stability of iron (oxyhydr)oxide minerals and the retention of associated metals. This research will examine interactions of the metals molybdenum, tungsten, and vanadium with the iron (oxyhydr)oxide minerals ferrihydrite, lepidocrocite, and goethite. These transition metals form important metalloenzymes, are emerging environmental contaminants, and readily partition onto surfaces of these minerals. Research experiments will examine complexities of metal uptake onto iron (oxyhydr)oxide phases over a range of geochemical conditions. Subsequent experiments will examine metal retention during mineral transformation reactions promoted by addition of ferrous iron or hydrogen sulfide in the absence of oxygen. Final experiments will assess longer-term metal retention under varied redox conditions relevant to environmental conditions on Earth. This research will support training at the undergraduate, graduate and postdoctoral levels. Results will advance understanding of relationships between redox conditions, mineral stability and the distribution, transport and bioavailability of molybdenum, tungsten and vanadium near Earth' surface. This information may inform interpretations of their distribution in the sedimentary rock record, which can offer insight into productivity and redox conditions over geologic time. These metals are also emerging environmental contaminants associated with anthropogenic activities including mining and mineral processing. Therefore, results may also support development of new strategies for mine waste management and reclamation.