OPP-PRF: Organic Matter Export, Processes, and Transformations Drive Carbon Cycling Patterns in the Arctic Ocean

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Global carbon cycling supports life on Earth and affects marine, terrestrial, and atmospheric ecosystems. Human activities alter the balance of this natural cycle by adding fossil carbon to the contemporary atmosphere, thereby changing our climate. As the climate warms, reduced sea ice cover and increased Arctic river carbon export dramatically change the microscopic organic molecules in the oceans. These compounds play essential roles in Earth’s natural elemental cycles, contribute to the storage of atmospheric greenhouse gasses (e.g., carbon dioxide, CO2) in the ocean, and support marine organisms. Therefore, with large-scale ecosystem changes across the Arctic, the time is now to better understand what microscopic materials in the Arctic Ocean will shape the composition and function of all other Earth’s oceans. Concerning the prediction that the Arctic Ocean will be ice-free around 20–50 years from now, this research is designed to understand Arctic Ocean carbon cycling processes and impacts, such as further biological and chemical feedback loops as well as CO2 outgassing from microscopic carbon-based materials, such as dissolved organic matter (DOM), altered in mineralization processes. Much of the DOM exported from the Arctic is riverine and is funneled through the Fram Strait, a relatively small body of water that connects the Arctic Ocean to the global conveyor belts. This is important because Fram Strait represents a linkage of Arctic terrestrial carbon to other ocean environments. The researchers will measure the amount and type of DOM responsible for the largest transformations in the ocean resulting in increased concentrations of CO2 in the atmosphere. Providing essential molecular-level chemical data is needed to understand DOM signatures within the context of global change and will provide the scientific community with definitive DOM data. The researchers also embrace this work as an ideal opportunity to spearhead a carbon chemistry initiative across diverse Arctic science researchers to lead to safer and healthier carbon characterization practices. Global environmental change impacts Arctic ice sheets, sea ice, ocean, and circulation, affecting ecosystem function and carbon cycling in marine waters. As the climate warms, sea ice diminishes, ice sheet loss from Greenland increases, and Arctic river-carbon (C) outputs increase, making the Arctic Ocean a mixing zone of diverse organic material (OM) that gets funneled through the Fram Strait before circulating globally. Thus, the Fram Strait is poised to dramatically impact marine surface and bottom waters resulting in carbon dioxide (CO2) emissions upon OM mineralization through natural processes. Marine C mineralization processes depend on dissolved OM (DOM) composition, microbes, nutrient availability, and sunlight exposure, all of which shape the mechanisms for CO2 outgassing from transformed DOM. The overarching hypothesis is DOM molecular composition distinctions between microbial and photochemical mineralization of DOM to CO2 in Fram Strait are driven by the heterogeneous nature of diverse Arctic Ocean sources. Advanced analytical chemistry measurements of DOM (ultrahigh resolution mass spectrometry, C isotopic composition, and nuclear magnetic resonance spectroscopy) will be used to decipher molecular composition and unique C markers from biotic and abiotic degradation mechanisms occurring in the Fram Strait. As a result, linkages of DOM composition and CO2 outgassing will be made. This work will target how DOM can persist and be transformed in the Fram Strait across rapid and prolonged time scales. Progress in mapping microbe- and photochemical-DOM interactions in the Fram Strait will address knowledge gaps across seemingly disparate fields, culminating in better understandings of C cycling in the Arctic. The data will provide the community with definitive DOM compositional markers that can be used to better understand Arctic marine waters and help enforce healthy environmental policy as the climate warms and sea levels rise. Analytical and green chemistry expertise will be combined to identify improvements in Arctic C research which will be essential for the next generation of Arctic researchers.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.