Collaborative Research: Organic Geochemical Investigation of the Rainbow Hydrothermal System, Mid-Atlantic Ridge

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ABSTRACT: Seewald/McCollum (0549829/0550800)The fate of carbon in submarine hot springs has broad implications for a diverse spectrum of chemical, physical, and biological processes occurring within the oceanic crust and water column. Nevertheless, the composition and source of organic compounds in submarine hydrothermal fluids remains poorly known. As a result, this research investigates the origin of organic compounds at the Rainbow hydrothermal system, which is hosted in ultramafic rocks on the Mid-Atlantic Ridge. The site was chosen because ultramafic rocks may play a pivotal role in the abiotic synthesis of aqueous organic compounds because they contain catalytically active minerals and create reducing chemical environments during reaction with seawater-derived hydrothermal fluids. Gases and organic compounds from Rainbow hydrothermal fluids will be analyzed chemically and isotopically, as will their associated sulfide minerals. In particular analyses will target amino acids, carboxylic acids, ammonia, and high molecular weight hydrocarbons. Geochemical analyses of minerals and other inorganic constituents will also be carried out. Results will be modeled using thermodynamics and interpreted in light of laboratory experiments that will allow interpretation of the origin (abiotic, thermal cracking, mantle degassing, or microbial) of the organic compounds. Broader impacts of this work include education and training of students at Woods Hole Oceanographic Institution and the University of Colorado, as well as engaging students who are under represented in the sciences from Bridgewater State College. The work also fosters international collaboration with the National Oceanographic Centre in the UK by bringing one of its students to Woods Hole to work on the project for an extended stay.