Revelle factor

An increase in seawater alkalinity (for example, by the dissolution of CaCOa) would decrease pC02 in seawater and decrease the Revelle factor (10), Thus CaCOa dissolution would provide a a strong negative feedback in response to an increased level of CO2 in the atmosphere and ocean. However, the surface water of temperate and tropical oceans is supersaturated with respect to CaCOa by several fold. It is not likely that the dissolution of CaCOa would provide a negative feedback to the air-sea CO2 transfer process in the near future. 

Revelle and Suess (1957) introduced a dimensionless factor (y), commonly referred to as the Revelle factor, to describe the relation between changes in Pc02 and XCO2 in seawater. The equation for this relation (based on the form of Takahashi et al., 1980a), where A = alkalinity, is ... 

The Revelle factor is about 10 for typical surface seawater. The details of the chemistry of this general relationship and its derivation have also been discussed by Sundquist et al. (1979), who called it the "homogeneous buffer" factor. Of interest is the fact that using the Revelle factor one can calculate for an instantaneous change in the Pco2 °f the atmosphere, the distribution of carbon between the atmosphere and seawater. 

In addition to the effects noted previously, an input of CO2 promotes the dissolution of CaC03(s). The reaction does not proceed to the right without constraint, but rather meets a resistance given by the Revelle factor, R... 

As discussed above, the chemistry of carbon in seawater is such that less than 1% of the carbon exists as dissolved CO2. More than 99% of the DlC exists as bicarbonate and carbonate anions (Table 3). The chemical equilibrium among these three forms of DlC is responsible for the high solubility of CO2 in the oceans. It also sets up a buffer for changes in oceanic carbon. The buffer factor (or Revelle factor), is dehned as follows ... 

The buffer factor. The oceanic buffer factor (or Revelle factor), by which the concentration of CO2 in the atmosphere is determined, increases as the concentration of CO2 increases. The buffer factor is discussed above in Section 8.10.3.1.3. Here, it is sufficient to describe the chemical equation for the dissolution of CO2 in seawater. 

We can now use the knowledge of the Revelle factor to estimate the anthropogenic GO2 uptake by the ocean at equilibrium. Presuming that after some reasonable time the ocean carbonate system comes into equilibrium or nearly so with GO2 in the atmosphere, we can calculate the fraction of the anthropogenic GO2 taken up by the ocean as a function of the depth of the layer into which... 

The change in the uptake factor (L/f) and Revelle factor (R) as a function of the fco, in equilibrium with a seawater solution containing a total alkalinity of 2300 peq kg . ... 

The ratio of the instantaneous fractional change in the partial pressure of C02 (pC02) exerted by seawater to the fractional change in total C02 dissolved in the ocean waters. The buffer factor relates the partial pressure of C02 in the ocean to the total ocean C02 concentration at constant temperature, alkalinity and salinity. The Revelle factor is a useful parameter for examining the distribution of C02 between the atmosphere and the ocean, and measures in part the amount of C02 that can be dissolved in the mixed surface layer, rocketsonde... 

Revelle factor A dimensionless number that expresses the relative sensitivity of the partial pressure of CO2 and total dissolved inorganic carbon in a solution to the incremental additional or removal of CO2, bicarbonate or carbonate ions. 

The Revelle factor ranges from a value of 14 at 0° to 8 at 30°, with a globally averaged value of 10 in seawater. The Revelle factor is the reason that the turnover time for carbon in the upper 100 m of the ocean is 1 instead of 10 years. 

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