Sources of Organic Compounds in Submarine Hot-Springs: An Experimental Investigation

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Intellectual Merit: Aqueous carbon species in hydrothermal vent fluids have important implications for carbon fluxes to the ocean, biological communities that inhabit vent environments, and the origin of life. Although several organic compounds have been identified in hydrothermal fluids, their origin as either biotic or abiotic is unclear. This research uses laboratory experiments at high temperatures and elevated pressures to assess the chemical and isotopic composition of organic assemblages produced by these two processes. A focus of the work is the carbon and hydrogen isotopic signature of pure gas-phase Fischer-Tropsch type (FT) reactions, abiotic surface catalyzed reactions that have been invoked to explain the presence of pre-biotic hydrocarbons in natural environments. Hydrous pyrolysis experiments will be carried out at buffered hydrothermal pressure and temperature conditions using three types of microbial biomass using seawater dissolved organic carbon that is observed to have depleted concentrations in high-temperature hydrothermal fluids relative to seawater. Resulting isotopic and compositional data will be used to identify potential pyrolysis products in hydrothermal systems that have, to date, been overlooked. Broader Impacts: This research supports a postdoctoral researcher and will engage undergraduates in research. At no cost to this proposal, an undergraduate from Bridgewater State College, a four-year public undergraduate institution, will be intimately involved with the experimental design process and the subsequent analytical efforts, under mentorship by the PIs.