Abstract
Spatio-temporal variation of dissolved carbon dioxide (DCO2) concentration and air-water turbulent flow field in a surf zone were measured in a wave flume using a LIF system, a PIV system and a LED back-light system. We observed entrained bubbles and strong turbulence locally enhanced the gas dissolution into water in the transition region. However DCO2 concentration could not totally increase in the region since the strong turbulence extensively diffused the DCO2 in a short time. DCO2 concentration in the bore region increased with time and reached the high level earlier than the transition region. The high concentrated DCO2 in the bore region was transported in a whole surf zone due to the undertow. Therefore, to estimate the gas transfer velocity in a surf zone, we need to evaluate the undertow effect on the DCO2 transport in addition to the breaking wave effects, such as the aeration effect and the turbulence intencity.
