We have several projects underway looking at the redox chemistry of Fe minerals in the environment. Much of our effort has been focused on understanding the biogeochemical transformations of Fe oxides and clays under reducing conditions. Specifically, we have used 57-Fe Mössbauer spectroscopy and stable Fe isotope tracers to demonstrate Fe(II) catalyzed recrystallization of Fe oxides and clays. Recrystallization involves several steps including interfacial electron transfer between sorbed Fe(II) and structural Fe(III) and then significant mixing of aqueous Fe with bulk structural Fe. Our applied work is focused on contaminant fate, particularly with regards to uranium, mercury, and arsenic. Currently funded projects include:

Stable Isotope Investigation of Fe Oxide Reactivity and Natural Isotope Fractionation
NSF Division of Earth Sciences
Michelle Scherer, Clark Johnson, and Brian Beard

Electron and Atom Exchange Between Aqueous Fe(II) and Structural Fe(III) in Clays
U.S. Department of Energy Subsurface Biogeochemical Research
Michelle Scherer, Clark Johnson, Brian Beard Kevin Rosso, Ken Kemner, Max Boyanov, Ed O’Loughlin

Linking Molecular Scale Surface Speciation to Interfacial Fe Redox Chemistry.
Environmental Chemical Science Program of NSF
Michelle Scherer, Vicki Grassian, Martin St. Clair

Quantifying Soil Iron Oscillations in Redox Transition Environments: Impacts on Carbon Degradation Rates and Phosphorus Availability.
Soils and Soil Biology Program of USDA.
Aaron Thompson, Michelle Scherer, Christof Meile



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