Collaborative research: Chromophoric dissolved organic matter (CDOM) and lignin phenols as tracers of water masses and biogeochemical processes in the Arctic Ocean

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Benner 0713915University of South CarolinaFunds are provided to investigate the distribution of terrigenous organic matter and its fluorescent properties to improve understanding of ventilation processes in the Arctic halocline as well as the physical, biological, and photochemical fluxes of terrigenous organic carbon in the Arctic Ocean. The principal investigators propose a series of hypotheses for testing:Hypothesis 1: Terrigenous dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) are sensitive tracers of river water that carry unique source information that is not readily available with other freshwater tracers (e.g. salinity, alkalinity, barium, d18O), especially in the Canada Basin.Hypothesis 2: Terrigenous DOM and CDOM are primarily injected below the surface mixed layer during sea-ice formation and brine rejection and are useful tracers of the ventilation of Arctic halocline waters.Hypothesis 3: The Arctic halocline is a multilayer system with each layer having distinct origins. (They believe that detailed fluorescence analyses will allow them to distinguish the different origins and develop more specific in situ probes for the future.)Hypothesis 4: The size distribution of lignin phenols in DOM provides a qualitative index of the extent of decomposition of terrigenous DOM in the Arctic.The freshwater budget of the Arctic Ocean, and its variability of decadal time scales and longer, has the potential for important impacts on global ocean circulation, such as modulation of the meridional overturning circulation, and climate. This project will provide tools for the study of and insights into the pathways and fate of freshwater discharged into the Arctic Ocean from some of the world's major river systems.