Photodissolution of Sedimentary Organic Matter

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ABSTRACTOCE-0623331The field of marine photochemistry has previously focused on dissolved organic matter and trace metals. However, recent studies have shown that sediment suspensions in the ocean are also affected by sunlight and have the potential to dissolve most of their particulate organic carbon to the dissolved organic phase. A researcher from the University of Maine will determine the importance of photodissolution in the coastal Louisiana area, where riverine particulates are quickly deposited in shallow waters. Optical properties of the particulates will be examined to assess the photon fluxes and to determine the quantum yields of this photodissolution reaction. To determine the importance of this reaction, modeling of the turbid nearshore regimes, field-tests of the optical results, and developments of the markers from previous photodissolutions will be carried out. In addition to the optical properties of the particulates, the fate of the photodissolved organic matter will be assessed, addressing both photo-oxidation and biological mineralization reactions. In terms of the broader impacts, this research will provide new insights into the impact of photodegradation of particulate organic matter on the cycling of nutrients in the deltaic region of the Mississippi River. Outreach efforts based on the research activities at the K-12 and community level will be carried out. One graduate student and one undergraduate student will be supported and trained as part of the study.