『Abstract
　Dissolution rates of calcite, dolomite and magnesite were measured at 25℃ and pH from 3 to 4 as a function of salinity (0.001 M≦[NaCl]≦1 M) and partial pressure of CO2 (10^-3.5≦p CO2≦55 atm) Experiments on calcite and dolomite crystal planes dissolution were performed i a batch reactor under controlled hydrodynamic conditions using the rotating disk technique. Dissolution experiments using mixed-flow reactors were also conducted on calcite and dolomite powders of 100-200μm. Magnesite dissolution rates were measured using a batch titanium high-pressure reactor on 100-200μm powders. The pH was measured in-situ using a solid-contact electrode in a cell without liquid junction. At pH〜4.0 and constant hydrodynamic conditions pH-independent calcite dissolution rate increases by a factor of 3 from 1 to 〜20 atm p CO2 and stays constant at 25 to 50 atm. These rates do not depend on NaCl concentration from 0.01 to 1.0 M and pH of 4 to 8. Calcite dissolution rates depend strongly on stirring between 200 and 2000 rpm at 2, 10, and 50 atm p CO2 suggesting mass transport control at these conditions. Both for polycrystalline samples and cleavage planes, dolomite dissolution rate increases with increasing p CO2 at 1≦p CO2≦10 atm and stays constant when p CO2 is further increased to 50 atm. These rates depend on stirring velocity and increases by a factor of 2-3 from 200 to 2500 rpm reflecting moderate transport contribution to dissolution at these conditions. Within the experimental uncertainty, dolomite dissolution rates are independent of ionic strength between 0.1 and 1 M NaCl and 5 to 50 atm p CO2. This is also confirmed by powder dissolution experiments performed in mixed-flow reactors. Magnesite dissolution rate increases by a factor of 3 at 0 to 5 atm p CO2 but remains constant from 5 to 55 atm p CO2.
　The results obtained in this study demonstrate that carbonate mineral dissolution rates are not proportional to H2CO3^*(aq) and depend only weakly on p CO2. For dolomite (cleavage planes) and magnesite, the surface complexation model (SCM) of Pokrovsky et al. [Pokrovsky,O.S., Schott,J., Thomas,F., 1999a. Processes at the magnesium-bearing carbonates/solution interface. I. A surface speciation model of magnesite. Geochim.Cosmochim.Acta, 63, 863-880; Pokrovsky,O.S., Schott,J., Thomas,F., 1999b. Dolomite surface speciation and reactivity in aquatic systems. Geochim.Cosmochim.Acta, 63, 3133-3143.] predicts dissolution rates up to 50 atm p CO2 with a good accuracy. Because the dissolution of calcite at 3＜pH＜4 is controlled by transport processes, experimental and theoretical difficulties do not permit this mineral dissolution rate to be accurately modeled within the framework of SCM.

Keywords: Calcite; Dolomite; Magnesite; Dissolution; Kinetics; p CO2; Salinity』

1. Introduction
2. Experimental methods
　2.1. Carbonate samples
　2.2. Experimental procedure
　　2.2.1. Mixed-flow reactors
　　2.2.2. Batch reactors
　2.3. In-situ pH measurements in high-pressure batch reactors
　2.4. Analyses
　2.5 Calculations
3. Results and discussion
　3.1. Kinetics of calcite dissolution
　3.2. Kinetics of dolomite dissolution
　3.3. Kinetics of magnesite dissolution
4. Conclusions and geological applications
Acknowledgments
Appendix A
Appendix B
References