A new experimental technique for validating exchange models of carbon dioxide between the atmosphere and sea-water

The mechanism of CO₂-exchange between the atmosphere and sea-water was re-examined by simultaneously measuring pH and pO₂ in artificial sea-water exposed to CO₂ and air atmospheres. The data were fitted to an exchange model by using both the differential and integral forms of the diffusion equation. It was found that the pH and pO₂ data support the assumption that the exchange for these gases is driven by the gradient of the partial pressure of the gas across the imaginary solution-gas boundary layer (the z layer) and is not affected by chemical reaction or hydration rate under the experimental conditions used, viz. 1-100 meq l., alkalinity, pH 4.5-8.3 and z-layer thickness 2-500 μm. It is concluded that the rate of hydration of CO₂ plays an insignificant role in the exchange mechanisms between the atmosphere and the oceans.