Scientists have become increasingly aware of microbial communities living at and below the seafloor where they thrive on chemical energy (chemosynthesis) rather than sunlight. While it is not yet known how abundant and widespread such chemosynthetic communities are, it has been suggested that they may make significant contributions to global biomass and the biogeochemical cycles of carbon and other elements. A primary source of chemical energy that sustains these deep sea microbes is molecular hydrogen (H2), which is generated from the reaction of water with ultramafic rocks, a process known as serpentinization. However, the factors that control the amount of hydrogen generated during serpentinization remain poorly known. This research conducts laboratory experiments at high temperatures and along the vapor pressure curve of H2O that monitor H2 production as water-rock reactions proceed as a way to simulate the serpentinization process. Detailed analysis of the solid reaction products with state-of-the-art high resolution methods make it possible to define the chemical reactions that generate hydrogen. Numerical geochemical models will provide a framework for extrapolating the laboratory results to natural systems. Broader impacts of the work include training for a postdoctoral associate and two undergraduate students. The research will also serve as a focal point for a new university course aimed at training students in a multidisciplinary scientific approach.
