Different Carbon Dioxide Partial Pressure Environment Near Equilibrium Of Marine Carbonate Dissolution And Precipitation Kinetics Study

This paper adopts the free-drift open reaction technique to study the dissolution and precipitation procedure of aragonite and calcite in artificial seawater near equilibrium, analyse the influence of carbon dioxide pressure (pCO₂) on aragonite and calcite dissolution and precipitation, and discuss the relationship of dissolution and precipitation rates between aragonite and calcite.Most of the experiments are obtained at 25℃. In order to evaluate the effort of temperature on dissolution rate and kinetics, some experiments are made at 15℃. Dissolution and precipitation rates are calculated from the change rates of the carbonate alkalinity of the reacting solution. By altering the pCO₂ of the CO₂/N2 gas mixture (0/300/3000ppm) bubbled in the reacting solution, we study the influence of pCO₂ on dissolution and precipitation mechanisms.At the same temperature, pCO₂ and saturation state (Ω), whenΩis less than 0.75, the dissolution rate of aragonite is more than that of calcite, and the vice verse whenΩis more than 0.8. At the same temperature and saturation state(Ω), higher pCO₂ will enhance the dissolution rate of aragonite and calcite while pCO₂ has no obvious effort in precipitation experiments.