Microbial Geochemistry

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Research will focus on quantifying relationships between taxonomic and physiological microbial diversity and spatial-temporal dynamics of hydrogeochemical gradients in surface and groundwater environments. Of immediate concern is the role of ecophysiological diversity among of microorganisms for iron redox cycling in precipitation-dissolution reactions involving oxide and silicate minerals, particularly in terms of coupled processes that contribute to the removal of carbon dioxide from the atmosphere. Studies will encompass laboratory and field investigations; a major advantage of lab work is that it permits evaluation of the dependency and influence of bacteria on geochemical parameters such as pH, redox potential, etc., within the context of widely applied principles of thermodynamic equilibrium and reaction kinetics. At the same time, field studies are crucial not only to establish the limitations, constraints, and validity of theoretical models, but also reveal opportunities to test and exploit results of lab research, inform the development of new experimental directions, help to recognize and evaluate critical knowledge gaps, and permit exploration of new ways to decipher the behavior of complex natural systems. The planned scope of work includes molecular biological and geochemical characterization of groundwater microbial communities, quantitative electrochemical assessment of microbially mediated oxidation-reduction reactions, and establishment of correlations between rates of microbial iron redox transformations, groundwater geochemistry, seasonal variations, and geologic setting (e.g., bedrock, overburden and aquifer mineralogy, glacial history, etc.). This initiative represents an important step forward for microbial geochemistry into a challenging new area of research focused on deciphering the complex spatial and temporal relationships that exist between microbial metabolic diversity and geochemical processes in nature, and understanding potential consequences of disturbances associated with environmental change.