HR: 14:10h
AN: PP43E-03    [Abstracts]
TI: Calcite Dissolution in Saline Waters
AU: * Finneran, D W
EM: finneran@ocean.tamu.edu
AF: Department of Oceanography, Texas A&M University, TAMU 3146, College Station, TX 77843-3146, United States
AU: Morse, J W
EM: morse@ocean.tamu.edu
AF: Department of Oceanography, Texas A&M University, TAMU 3146, College Station, TX 77843-3146, United States
AB: The specific effect of ionic strength on the reaction kinetics of calcite dissolution in intermediate to high ionic strength (0.5 < I < 6.0) solutions applicable to natural waters has been investigated using classical free-drift methods where all other parameters (m_Ca2+, P_CO2, and T) have been held constant. Both phosphate-free solutions of potassium chloride (KCl) and sodium chloride (NaCl) as the dominant ionic strength determining salt were investigated where calcium concentrations were held constant in all solutions at approximately 0.010 molal. Reaction rates were found to vary significantly as a function of ionic strength of the reacting solution, which we suggest is due to the lowered activity of water with an increase in ionic strength which decreases the rate of cation hydration. When modeled with the general rate equation, R = k(1-Ømega)ⁿ, first-order kinetics (n=1) are sufficient to fit the experimental data. Furthermore, the rate constant (k) appears to be a function of the square root of the ionic strength of the reacting solution. These results may have potential applications to the response of the ocean to acidification by fossil fuel CO₂ as well as CO₂ sequestration in subsurface saline waters in calcium carbonate-hosted reservoirs.
DE: 4203 Analytical modeling and laboratory experiments
DE: 4825 Geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting