Air-sea gas transfer in a shallow, flowing and coastal environment estimated by dissolved inorganic carbon and dissolved oxygen analyses

Abstract

We estimated gas exchange rates in Kabira Reef at Ishigaki Island, southwest Japan, using a mass balance calculation with dual “biological” tracers: Dissolved Inorganic Carbon (DIC) and Dissolved Oxygen (DO). The nighttime results allowed us to obtain reasonable gas transfer velocity k_w values, all of which exceeded those obtained in wind-dominant studies. The difference is likely due to the contribution of turbulence generated by the interaction between the current and bottom topography. The k_w obtained during high tides is consistent with that reported by Raymond and Cole (2001), whereas k_w during low tides is significantly higher, which seems to be caused by enhanced friction with the bottom of the reef and/or bubble-induced gas transfer by wave breaking at the reef crest.