CAREER: Investigating the controls on the loss of oceanic organic carbon in aged basaltic crust

One of the largest pools of actively cycling carbon is the organic carbon dissolved in deep-ocean seawater. However, the sources and sinks of organic matter associated with this pool of carbon are not well-understood. This project will investigate organic carbon cycling processes that occur as seawater flows through oceanic crust at low temperatures. A large volume of seawater flows through cool ocean crust as it ages, but these sites are not well-studied. Unlike hydrothermal vent fluids, low temperature seeps are difficult to identify because the temperature and chemistry of bottom seawater and cool crustal fluids are more similar. This makes it difficult to find these sites at the seafloor, leaving them largely unexplored. This study will measure the concentration and composition of dissolved organic matter in fluids from two newly discovered sites where low-temperature fluids discharge from seamounts. In addition, the research will provide new tools for organic matter characterization. As a result, this project will illuminate a part of the oceanic carbon cycle that has often been overlooked. This project also aims to inspire an interest in chemistry and biology among K-12 students by bringing the deep ocean to them. Teachers will develop classroom materials that introduce students to the charismatic octopus families that are attracted to sites of natural fluid discharge, and the fluid chemistry that shapes their behavior, during professional development workshops. The project will also engage students from primarily undergraduate institutions in deep-ocean research. Undergraduate and graduate students at the University of Delaware will also be involved in the project. The scientific objectives of this 5-year project are to: (1) expand the view of cool, aging crust from one study site (North Pond IODP (International Ocean Discovery Program) Site) to three by following the lead of brooding octopus mothers which have recently been found clustered around sites of moderately warm natural discharge from the Dorado and Davidson Seamounts; (2) broaden the analytical window for dissolved organic matter characterization to better identify signatures of microbial activity; and (3) refine the present global estimate of organic carbon loss from the deep ocean by crustal processes. In addition, societal benefits of the project include educational and learning activities for students from the K-12 to the graduate level that are well-integrated with the research. The project will provide training for one graduate student and more than 10 undergraduate students, half of which will come from primarily undergraduate institutions. This project also includes workshops for 30 STEM teachers over 3 years emphasizing hands-on activities that will bring environmental chemistry lessons aligned with Next Generation Science Standards into K-12 classrooms in the State of Delaware. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.