Determination of gas exchange velocities based on measurements of air-sea CO2 partial pressure gradients and direct chamber fluxes in the Duplin River, Sapelo Island, GA

CO2 fluxes were determined directly, using a floating chamber for ten to fifteen minute intervals over the winter between 2006 and 2007 from Marsh Landing Dock on Sapleo Island, Georgia. Air-Sea pCO2 differences were measured alongside the fluxes using a coupled equilibrator and infrared gas detector whereby gas transfer velocities (k) were calculated. In addition, current speeds were measured using an acoustic doppler current profiler and correlated with gas transfer velocities along side wind speeds. In the Duplin River, with the exception of spring tides, wind is an important variable controlling k in agreement with prior empirical measurement of estuarine k values. However, bottom generated turbulence was responsible for more than half of the magnitude of measured gas transfer velocities for 17 out of 100 of the deployments. In addition, gas transfer velocities during spring tides may be able to substantially increase k, however independent verification with an un-tethered floating chamber is needed to verify this in the Duplin River.