Abstract
To evaluate the air-sea CO2 flux of Osaka Bay, Harima Nada and Ago Bay, we conducted the spatial distribution surveys of the dissolved inorganic carbon (DIC) and pH. There are low DIC concentration in the inner part of Osaka Bay where external load is large because DIC was consumed by photosynthesis of phytoplankton. On the other hand, there are high DIC concentration in the Ago Bay where much organic carbon was accumulated on the sea floor. We found that CO2 was absorbed basically in all seas at daytime and, especially, Osaka bay had high CO2 absorption potential comparied with the other seas.
CO2 fluxes were calculated based on a chemical equilibrium model of carbonic acid from the measurment data of DIC and pH, air to sea CO2 flux was 12.6 to 14.0 CO2/m2/hr in Osaka bay, 1.5 to 3.7 CO2/m2/hr in Harima Nada and 0.8 mg CO2/m2/hr in Ago Bay. The CO2 Flux of Osaka Bay was larger than the averaged CO2 fluxes of coastal seas reported in around the world.
