CMG Research: Impact of Mineral Precipitating Biofilms on the Physical and Chemical Characteristics of Porous Media

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The proposed work will develop laboratory, modeling and computational tools for the study of the geological impact of mineral precipitating microbial communities, aiming at elucidating fundamentals and providing quantitative descriptions of the hydrobiogeochemical conditions and processes in carbonate mineral precipitating biofilms in porous media. Outcomes will be (1) characterization of the important physical (e.g. advective and diffusive transport), chemical (e.g. pH distribution), and biological (e.g. microbial metabolic activity) phenomena impacting pore systems, and (2) development of measurement techniques for identified relevant parameters with suitable spatial and temporal resolution. To accomplish this, models will be constructed that allow observation and insight into the roles of hydrodynamics, chemistry, electrochemistry, microbiology, and thermodynamics in the detail that are needed for description of interaction of biofilms with porous media. Thermodynamic principles will be used, necessary for improved description of biofilms in their natural geochemical role as thermodynamic machines. The experimental systems to be employed will allow spatially and temporally resolved non-destructive observation of combined biofilm development and mineral precipitation in capillary and porous media flow reactors. They will aid in closing the existing gap of knowledge between non-flowing (batch) systems often used to elucidate biogeochemical processes and the frequently observed influence of hydrodynamics on biogeochemical processes on the meso- and macroscale.The proposed research focuses on microbially-induced calcium carbonate mineralization. Calcium carbonate formation is responsible for the development of features with enormous scales in the shallow and deep ocean (e.g. reefs and alga and diatom exoskeletons) and in the terrestrial environment. Carbonate rocks (such as limestone, marble, and chalk) are probably the single largest reservoir of inorganic carbon on earth containing approximately 65 million gigatons of carbon. Carbonate mineral formation and dissolution are important parts of the global carbon cycle, have the potential to bind or release large amounts of carbon dioxide, and may therefore affect the global climate.Additionally, engineered, microbially mediated carbonate precipitation has been proposed as a strategy to improve geologic carbon sequestration and to facilitate the precipitation of heavy metals and radionuclides from contaminated groundwater. The investigators will develop laboratory and computational tools to better understand the role and utilize the potential in the environment of microbial communities in all of these processes.