THERMODYNAMIC RELATIONSHIP TO ESTIMATE THE EFFECTS OF HIGH CO_2 CONCENTRATION ON THE CO_2 EQUILIBRIUM AND SOLUBILITY IN SEAWATER

摘要

The effects of high CO_2 concentrations on carbonate equilibrium are important in studies related to the disposal of liquid CO_2 into the oceans. Using available thermodynamic data of liquid CO_2 and CO_2 solubility in seawater, an equation of solubility of liquid CO_2 in seawater was developed as a function of temperature, pressure, and salinity. It is shown that the non-ideal behavior of acid-base species subjected to high CO_2 conditions can be accounted for by Pitzer's parameters. The solubility of liquid CO_2 in seawater between values from calculation using thermodynamic equations and those from literature was presented. The pH of seawater equilibrated with liquid CO_2 was calculated to be elevated by approximately 0.20 pH unit due to the non-ideal effects of dissolved CO_2 on acid-base equilibrium. Effects of high CO_2 on seawater alkalinity are discussed.