IMPACT OF HURRICANE IAN ON CARBON DIOXIDE (CO2) FLUX IN TIDAL WETLANDS OF NORTH INLET-WINYAH BAY, SOUTH CAROLINA

Atmospheric carbon dioxide (CO₂) concentrations have increasingly accelerated for the past two centuries, impacting global climate change. At the land-ocean margin, tidal wetlands are carbon-dense environments which play a vital role in the global carbon cycle. The global carbon cycle regulates atmospheric CO₂ concentrations through physiochemical pathways. Tidal wetlands serve as a carbon sink by sequestering atmospheric CO₂ concentrations through natural processes of high autotrophic productivity, high accretion rates, organic matter deposition, and anoxic soils. Tidal wetlands also serve as a source of atmospheric CO₂ by releasing carbon from natural degradation and heterotrophic respiration. Hurricanes present a large-scale disturbances at the land-ocean margin and have the potential to disrupt known wetland carbon cycling.

An innovative carbon dioxide (CO₂) soil gas flux monitoring station was deployed during the 2022 Hurricane Season in the North Inlet-Winyah Bay National Estuarine Research Reserve (NI-WB NERR) located in Georgetown, SC. The CO₂ soil gas flux monitoring station was designed to withstand hurricane-level energy by consisting of a polyvinyl chloride (PVC) well, CO₂ sensor, telecommunications, and floating power station. The PVC well extends through the sediment-water-air interface to capture soil gas concentrations fluxing from wetland sediment. The CO₂ analyzer quantifies respired CO₂ concentrations within the PVC well atmosphere. The continuous collection of CO₂ concentrations is applied to a flux equation to determine the net CO₂ exchange.

On Sept. 30, 2022, Hurricane Ian made direct landfall over the NI-WB NERR. CO₂ gas exchange was continuously analyzed at the monitoring station within NI-WB pre-, during, and post-Hurricane Ian. As Hurricane Ian made landfall, NI-WB experienced net CO₂ emission and transitioned to net CO₂ sequestration as the storm's eye passed the tidal wetlands. After Hurricane Ian’s landfall, the NI-WB tidal wetlands experienced a brief (<12 hours) period of elevated CO₂ sequestration, followed by longer periods of net emission. This study represents one of the first to capture the continuous patterns of CO₂ flux in tidal wetlands throughout the immediate passage of a hurricane, providing insight into the effects of high-energy events on net carbon exchange in productive estuarine wetland environments.