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Biogeosciences

Teamrat Ghezzehei Teamrat A. Ghezzehei
Associate Professor

Professor Ghezzehei's research interest is in the movement and transformation of mass and energy in porous media at a fundamental level, as well as their application to environmental- and energy-related problems. The scale of his interest ranges from sub-pore scale dynamics of water-gas interfaces to water flow and solute transport at scales of tens of meters. The scope of his research includes laboratory and field experiments, theory, and computational modeling.

taghezzehei@ucmerced.edu
(209) 228-4711
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Stephen Hart Stephen C. Hart
Professor

Professor Hart's research explores the controls of biogeochemical processes and productivity in managed and wildland terrestrial ecosystems using methods such as:

  • Ecological genetics to isotopic analyses
  • Computer simulation modeling
  • Elucidate the biotic and abiotic factors that regulate terrestrial ecosystem structure and function

His research group is currently investigating:

  • Biological and geochemical controls on ecosystem development along a three million year, semi-arid soil chronosequence
  • Influence of the genetics of dominant plants on ecosystem processes
  • Effects of forest restoration treatments (e.g., thinning with or without prescribed fire) and wildfire on ecosystem carbon and water balance, soil microbial communities, and belowground processes
  • Efficacy of insect communities as indicators of forest ecosystem health
  • Utility of the 15N natural abundance signature of soil microbes as an integrator of nitrogen cycling processes
  • Impact of climatic change on soil-plant-atmosphere interactions; and the effects of water diversion on riparian forest
shart4@ucmerced.edu
(209) 228-4656
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Samuel J. Traina
Professor and Vice Chancellor for Research and Economic Development

Using a wide range of analytical methods (infra-red spectroscopy, electron microsocpy, x-ray absorption spectroscopy and mass spectroscopy), Professor Traina's group studies:

  • Chemical transformations of pollutants in soils, surface and ground water
  • Linkages between chemical form or speciation of particular pollutants and their relative toxicities in terrestrial and aquatic ecosystems
  • Roles of geoparticle surfaces and bacteria in pollutant fate

Current projects include the study of:

  • Contaminants at Department of Energy waste sites (Cr, Pu and U)
  • Role of Fe(II) and HSe- in transformations of nitroaromatic pesticides in wetlands
  • Fate of pharmaceuticals in the surface waters of National Parks
straina@ucmerced.edu
(209) 228-7964
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Asmeret Asefaw Berhe
Associate Professor

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
      
aaberhe@ucmerced.edu
(209) 228-4712
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Peggy O'Day
Professor

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.
poday@ucmerced.edu
(209) 228-4338
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