Air-water gas transfer influences CO2 and other greenhouse gas fluxes on regional and global scales,yet the magnitude of the transfer is not well known.For sparingly soluble gases,theory predicts that the gas transfer velocity,k,is controlled by turbulence in the surface aqueous boundary layer,which dictates the rate at which gases can be brought into contact with the surface to exchange with the atmosphere.Since gas transfer has been shown to scale with wind-generated turbulence in many field and laboratory wind-wave experiments,wind-based relationships to model k are typically used for gas exchange estimates from the open oceans to estuaries and rivers despite the acknowledged role of physical processes not related to wind (e.g.,tidal currents,rain,stratification,surfactants,and water depth).In an effort to explicitly relate turbulence near the surface aqueous boundary layer to gas exchange,models have been developed for k based on the turbulent kinetic energy dissipation rate,ε.