Air-water gas exchange and CO2 flux in a mangrove-dominated estuary

Mangrove forests are highly productive ecosystems, but the fate of mangrove-derived carbon remains uncertain. Part of that uncertainty stems from the fact that gas transfer velocities in mangrove-surrounded waters are not well determined, leading to uncertainty in air-water CO₂ fluxes. Two SF₆ tracer release experiments were conducted to determine gas transfer velocities (k(600) = 8.3 ± 0.4 and 8.1 ± 0.6 cm h⁻¹), along with simultaneous measurements of pCO₂ to determine the air-water CO₂ fluxes from Shark River, Florida (232.11 ± 23.69 and 171.13 ± 20.28 mmol C m⁻² d⁻¹), an estuary within the largest contiguous mangrove forest in North America. The gas transfer velocity results are consistent with turbulent kinetic energy dissipation measurements, indicating a higher rate of turbulence and gas exchange than predicted by commonly used wind speed/gas exchange parameterizations. The results have important implications for carbon fluxes in mangrove ecosystems.