UCLA

Understanding the interactions between calcite and aqueous solutions is important when studying the deep carbon cycle. The present study investigates the solubility of calcite in salt-H₂O fluids at 700 °C and 8 kbar. The investigated salts included NaCl, KCl, LiCl, and CsCl. All experiments were conducted in a piston cylinder apparatus. The results show that calcite solubility increases with increasing concentration of any individual salt. The data were successfully fit to simple functions of the square of salt mole fraction. At a given salt concentration, the solubility enhancement increases with decreasing salt cation size. Experiments in the fluids with mixtures of multiples of salts were used to derive simple relations that can be used to predict calcite solubility in a wide range of salt solutions at the studied conditions. The results provide a basis for extending this approach to different pressures, temperatures, and salt compositions.