Biogeochemistry of Serpentinizing Systems

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Anthropogenic carbon dioxide (CO2) concentrations are on the rise. We can reduce this CO2 by storing it in the ground as carbonate rock. CO2 can be naturally converted to solid carbonate in groundwaters flowing through rocks high in iron and magnesium and low in silica and potassium (ultramafic). These reactions are known as carbon (C) mineralization of CO2, and they are associated with the process known as serpentinization. Serpentinization is a water-rock reaction that produces groundwater with very high pH values and is enriched in methane (CH4) and hydrogen (H2). C mineralization may be enhanced by injecting CO2 into the groundwater at sites of serpentinization. However, the biogeochemical carbon cycling and the deep biosphere in the ultramafic subsurface are poorly understood. We do not know if injecting this CO2 may result in a greater production of CH4, which is another powerful greenhouse gas. Pure research in tracing the C substrates, transformations, and products in this ultramafic system is required. Additionally, sites of serpentinization could play an integral part in understanding the evolution of life on Earth and life in extreme environments. Sites of serpentinization are also of interest to the search for life on other ultramafic planets and moons. Thus, the 3 long-term goals of my ongoing research program are to: 1) quantify C exchange and enhance C storage between the atmosphere and ultramafic rocks; 2) determine how life survives in the high pH, low nutrient extreme environment of subsurface serpentinization; and 3) discover biosignatures that can be used to determine the presence of extant and fossilized life at sites of serpentinization on Earth and other worlds. To contribute to these long-term goals, over the next 5 years, I will: 1) quantify the natural CO2 and CH4 fluxes and determine how to enhance CO2 sequestration within serpentinizing systems; 2) determine the active microbial and viral communities, and the metabolisms within serpentinization-associated groundwaters; and 3) discover molecular and isotopic indicators of past and present life at sites of serpentinization. I anticipate this research will contribute to: 1) innovative methods for climate change mitigation; 2) novel outcomes with respect to viral and microbial identification, their interactions, and microbial metabolism of carbon; and 3) identification of sites of serpentinization as possible loci of extremophile life elsewhere in the universe, and as targets for space exploration. In addition to contributing to Canada's approach to climate change mitigation and space exploration, Canada will also benefit from the chemical, biological, and geological training of 15 highly qualified people.