The transfer of sparingly soluble gases across the air-water interface has significant effects on the distribution of the constituents in aquatic ecosystems. Gas-liquid transfer rate determines the flux of the sparingly soluble gases driven by the concentration difference. Considerable stream-driven gas-liquid transfer rate formulae have been developed. They have reasonable predictions in one-dimensional uniform flows. However, their applications in more complex cases such as three-dimensional flows are problematic. Furthermore, the wind effects are not incorporated into these formulae. New models need to be developed for gas-liquid transfer rate in three-dimensional flows that incorporate the effects of both wind and streamflow. In this study, first, a model of gas-liquid transfer rate in non-isotropic turbulent flows is developed. Second, a general stream-driven gas-liquid transfer rate model is developed for the normal ranges of water depth and flow velocity in natural rivers. Third, a wind-stream-driven gas-liquid transfer rate model is developed. Fourth, a model of surface renewal rate caused by turbulence from transition location of shear flows is developed. Fifth, a gas-liquid transfer rate model for wind and dynamic three-dimensional flow systems is developed. A computer program is coded and applied to various cases from simple one-dimensional uniform flow systems to complex wind and dynamic three-dimensional flow systems. A specific model can be selected from the series models for a specific application based on the application requirements and the acceptable computation complexity.; Key words. gas-liquid transfer rate, model, streamflow, wind, dynamic three-dimensional flow.
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