Upward-leakage of CO 2 from carbon sequestration sites may alter geochemical conditions in overlying aquifers. This work examines the release of metals in freshwater carbonate aquifers, and identifies the mineral phase controlling their aqueous concentrations. Geochemical modeling of calcite solid-solution dissolution under increasing CO 2 partial pressures results in different release patterns for different impurities. Whole-rock analysis of natural carbonate rocks shows solid phase concentrations of Pb and Cr on the order of several ppm, and of Ba, Co, Ni, Rb, Sc and Zn on the order of tens or hundreds of ppm. The only correlated appearances are of Cr, Mn, Na and Rb. Cluster analysis does not show clear grouping of limestones, dolostones and clayey-limestones based on their metal content. Batch experiments are set up to examine the kinetic release of metals from these carbonate samples, and their equilibrium aqueous concentrations, when exposed to different CO 2 concentrations.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)