『Abstract
　The effect of ionic strength (I), pCO2, and temperature on the dissolution rate of calcite was investigated in magnesium-free, phosphate-free, low calcium (mCa2+≒0.01 m) simple KCl and NaCl solutions over the undersaturation range of 0.4≦Ωcalcite≦0.8. First-order kinetics were found sufficient to describe the rate data where the rate constant (k) is dependent at the same I indicating that Na⁺ interacts more strongly with the calcite surface than K⁺ or that water is less available in NaCl solutions. Rates increased with increasing pCO2 and temperature, and their influences diminished at high I. Arrhenius plots yielded a relatively high activation energy (Ea≒20±2 kJ mol^-1) which indicated that dissolution was dominated by surface-controlled processes. The multiple regression model (MR) of Gledhill and Morse (2006a) was found to adequately describe the results at high I in NaCl solutions, but caution must be used when extrapolating to low I or pCO2 values. These results are consistent with the hypothesis that the mole fraction of “free” solvent (X“free”H2O) plays a significant role in the dissolution kinetics of calcite with a minimum value of 〜45-55％ required for dissolution to proceed in undersaturated solutions at 25-55℃ and pCO2 = 0.1-1 atm. This hypothesis has been incorporated into a modified version of the MR model of Gledhill and Morse (2006a) where X“free”H2O has replaced I and the Ca²⁺ and Mg²⁺ terms have been dropped:
　kpred = βo + β1T +β2pCO2 + β3X“free”H2O.

Keywords: Calcite; Dissolution kinetics; I』

1. Introduction
2. Materials and methods
3. Calculations
4. Results
5. Discussion
　5.1. I
　5.2. pCO2
　5.3. Temperature
　5.4. Mole faction of “free” water
　5.5. Multiple regression model
6. Conclusions
Acknowledgments
References