Biogeosciences

Professor Berhe's research is broadly focused on soil science and global change science. The main goal of her research is to understand the effect of changing environmental conditions on vital soil processes, most importantly the cycling and fate of essential elements in the critical zone. She studies soil processes in systems experiencing natural and/or anthropogenic perturbation in order to understand fundamental principles governed by geomorphology, and contemporary modifications introduced by changes in land use and climate.

Professor Berhe's general research themes are:

• Effect of climate changes (specifically rainfall and temperature) on storage and stabilization of soil organic matter and cation nutrient budgets
• Nano-scale biogeochemistry of iron oxides, especially how the size and concentration of oxides in soil control stabilization and destabilization of organic matter
• Erosion and terrestrial carbon sequestration, specifically temporal evolution of the erosion-induced terrestrial carbon sink and reconstruction of environmental history from sediments
• Political ecology of land degradation and ownership, particularly the contribution of armed conflicts to land degradation and ways people relate to their environment
   

Peggy O'Day is environmental geochemist who studies the chemistry, reaction, and transport of inorganic contaminants and species, primarily metal and metalloid elements, in surface and subsurface systems.  She specializes in the use of spectroscopic and microscopic methods, especially synchrotron X-ray techniques, to determine element speciation and molecular-scale mechanisms of biogeochemical reactions in natural systems and laboratory analogs.  She develops and applies thermodynamic, kinetic and reactive transport models for synthesis and quantitative description of biogeochemical cycling, reactivity, transport, and bioavailability.

Current research projects include:

• Characterization of element speciation and solid phases in natural and engineered airborne particulates, and their impacts on human health through cellular response.
• Surface reactivity of mineral phases with respect to metal ion adsorption using molecular computational methods, spectroscopic characterizations, and geochemical modeling.
• Environmental influences on mercury speciation and methylation.
• Novel methods for remediation of soils and sediments through application of reactive amendments.
• Mechanisms and rates of abiotic and biotic uranium oxidation linked to nitrogen and iron cycling, and dissolution mechanisms and rates of uranyl oxide, silicate, and phosphate phases.