| Time variations of cross-shore distributions of dissolved carbon dioxide (d-CO2) concentrations and air-water turbulent flow fields in a surf zone are experimentally studied in this paper. Breaking waves entrain many air bubbles and also produce numbers of vortices during wave splashing process、 forming complicated air-water two-phase turbulent flow fields in a surf zone. In a transition region where three-dimensional vortices so-called obliquely descending eddies typically evolve、 many entrained bubbles are rapidly spread over a wide area owing to strong turbulent diffusion、 significantly increasing d-CO2 concentrations via gas dissolution across bubble-water interfaces. Thus gas transfer velocity in a transition region is much higher than that in a bore region where a few bubbles are entrained and fully developed vortices have much smaller scale. |
