Constraining Lateral Carbon Fluxes from a Connecticut Salt Marsh over Multiple Tidal Cycles

Coastal vegetated ecosystems cover a small portion of Earth's land surface but disproportionately bury large amounts of "blue carbon" in their soils and biomass. Despite this, data on the carbon exchanged between these coastal ecosystems and the ocean for large stretches of coastline is lacking. This subsequently limits our ability to assess the potential of these coastal wetlands as solutions to ongoing climate change. Here, we will present lateral organic and inorganic carbon fluxes from a Connecticut saltmarsh collected over multiple months (starting July 2022) and multiple tidal cycles using ISCO portable samplers, EXO2 sondes, and a Picarro gas concentration analyzer. Initial data suggests there is low methane (CH4) and nitrous oxide (N2O) fluxes coming in with the rising tide and high CH4 and N2O fluxes as the tide recedes, consistent with the tidal pumping mechanism. We also see an increase in colored dissolved organic matter (CDOM) with the receding tide, suggesting CDOM input from the saltmarshes into coastal waters. As we continue to sample and perform additional analyses (DOM optical measurements, alkalinity), we will examine the impact of climate (e.g. rainfall, temperature) and physicochemical (e.g. salinity, oxygen) drivers on these carbon fluxes. By better constraining these carbon fluxes, we can improve coastal carbon cycling models and blue carbon policy.