DESIGN AND METHODOLOGY FOR INVESTIGATING CARBON (CO2) FLUX DURING HIGH ENERGY STORM EVENTS IN TIDAL WETLANDS: A PRESENT AND HISTORICAL APPROACH

Coastal tidal wetlands are capable of sequestering and storing carbon through processes of photosynthesis, high sedimentation rates, and low decomposition rates. These processes allow tidal wetlands to function as long-term carbon reservoirs, while sequestering 30-50 times more carbon per unit area than forest. High-energy tropical storm events may disturb the carbon footprint and balance of coastal tidal wetlands, ultimately impacting known wetland-climate interactions. Tropical storm-driven carbon flux and storage has been documented in tropical rainforests, however the impact of high-energy storms on carbon storage in tidal wetlands is largely unknown. A better understanding of the interplay between storm events and the potential of periodic pulses of abnormal soil carbon dioxide (CO2) gas flux within tidal wetlands is critical for understanding coastal carbon cycles.

An investigation of modern and historical variations in carbon sequestration during high-energy storm events will be utilized. We have designed and built soil gas wells in tidal wetlands to withstand high tropical storm energy, minimize cost, and measure present carbon sequestration ability. CO2 soil gas sensors protected within constructed PVC wells can be used to quantify soil CO2 gas flux concentrations during three time intervals: (1) steady state conditions pre-storm events, (2) high-energy conditions during storm events, and (3) recalibration to steady-state conditions post-storm events.This well design balances the need for sensitive sensors with a robust design that minimizes threat to and impact of equipment loss during storm events.

Accompanying contemporary in-situ CO2 flux analysis, a multi-proxy approach using paleotempestology methods, isotopic analysis, and organic carbon quantification will assist in quantifying variations in carbon storage following historic storms. The developed multi-proxy approach will be conducted on tidal wetland soil cores to create a historical record of tidal wetland-storm event interactions. The combination of modern and historical methodologies will improve the understanding of how and to what degree tidal wetlands sequester carbon during tropical storm events. The improvement of carbon stock allotment in tidal wetlands will discern global atmospheric CO2 concentrations and refine predisposed climate change projections.