Award: OCE-1220289

The principal goal of this project was to improve the equilibrium model that is used to relate the four primary parameters of the marine carbon dioxide (CO2) system: total dissolved inorganic carbon (DIC); total alkalinity (TA); CO2 partial pressure (pCO2); and seawater acidity (pH). Analysis results have shown that, for temperatures between 20 and 25 oC and the usual range of marine salinities, the present model allows accurate determination of all four variables by measuring two of them and calculating the remaining two. Testing determined, however, that the internal consistency of the model is less accurate for much lower temperatures and salinities. In addition, the model may not be valid if pCO2 values continue to increase due to increased CO2 concentration in the atmosphere. In summary, this project aimed to improve the model?s validity over a much wider range of temperatures, salinity, and pCO2. During this project, instrumentation was developed to make measurements of DIC and TA much more routine than previously possible. Measurements of all four primary CO2 system variables were then made in the laboratory over a very wide range of temperature, salinity, and pCO2 levels. This work improved the understanding of the interrelationship of these parameters for a much wider range of temperature, salinity, and pCO2, which helps to improve our understanding of the effects of increasing concentrations of CO2 in our atmosphere (e.g., ocean acidification), particularly in coastal marine environments. However, we also concluded that that better models are required to more accurately describe the interrelationships of the CO 2 system variables for extreme temperature and salinity conditions. Last Modified: 04/03/2018 Submitted by: Robert T Short