Microbial geochemistry dynamics

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Bacteria are widely recognized as protagonists of a range of geochemical reactions in pristine and contaminated aqueous environments. The behavior of bacteria as geochemically reactive "agents provocateurs" is engendered not only by their ubiquitous distribution and diverse metabolic capabilities, but also stems from their intrinsic cell-surface reactivity and ability to sorb a wide range of dissolved chemicals. Much of our recent work has been on extreme environments (e.g., hot springs in the Andes, the Canadian High Arctic), but not to the exclusion of more "normal" ecosystems (e.g., groundwater springs) that help to define these extremes. Our studies have also been used to quantify the geochemical behavior of microorganisms as sorbents for dissolved mineral-forming elements, and as nucleation substrates for mineral precipitation. Of immediate concern is exploration of bacteriogenic mineral precipitation reactions for sustainable natural remediation of fluoride (F-) in groundwater-supplied drinking water systems in India (where the crippling disease fluorosis is endemic), as well as assessment of the diversity of prokaryotic viruses (i.e., bacteriophage) in the deep subsurface and acid mine drainage environments, and their potential to prevent metal contaminant migration in aqueous systems through sorption and mineral precipitation reactions. Studies will focus additionally on development of dynamic quantitative geospatial models for microbial Fe2+/Fe3+ redox cycling in precipitation-dissolution reactions involving silicate minerals, particularly in terms of coupled processes that contribute to the removal of CO2 from the atmosphere. This initiative represents a groundbreaking 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 and geochemical processes in nature, and understanding impending consequences of disturbances associated with environmental change.