Ion-interaction approach: Pressure effect on the solubility of some minerls in submarine brines and seawater

The pressure dependence of salt solubility in multiple electrolyte solutions was estimated to 1000 atm. The activity coefficients, thermodynamic solubility products, degrees of saturation, and mineral solubility were calculated with high precision only up to 300 atm because of the absence of compressibility data for mixed electrolyte solutions. The ion-interaction approach developed during the last 2 decades allows the prediction of various thermodynamic properties, including volumetric ones for multiple-solute natural solutions. This approach was applied to the estimation of the depth dependence of solubility for certain evaporite minerals in natural brines. The influence of pressure on solubility products, mean activity coefficients, and degrees of saturation of minerals, such as, halite (NaCl), anhydrite (CaSO₄), gypsum (CaSO₄·2 H₂O), celestite (SrSO₄), and barite (BaSO₄) were calculated for in situ depths in the Orca Basin (Gulf of Mexico), the Tyro and Bannock II depressions (the Mediterranean Sea), and for average seawater.