Carbonates, congruent dissolution

The sulfete and chloride minerals in evaporites (gypsum, anhydrite, halite) undergo congruent dissolution to produce Ca (aq), S04 (aq), Na (aq), and Cl (aq). The dissolution of evaporite and biogenic carbonates (limestone, dolomite, and calcite) generates... 

South of the Arctic tree-line and into the forest, temperature and precipitation increase. There is much more biomass than in the tundra and the differentiation of the soil profile in an upper and a lower compartment is greatly accentuated. The upper profile is dominated by organic acids, the lower by carbonic acids congruent dissolution is thus expected in the upper horizon (see Section... 

Mass action relationships for aluminosilicate-carbonate-water reactions will be the most important constraint in buffering pH if their reaction rates are fast enough to accommodate changing environmental conditions (kinetic constraint), and there are sufficient amounts of these minerals in the rock (mass balance constraint). To attempt to address the kinetic constraint first, we can consider how fast a mineral typical of low temperature alteration in both sediments and fractured hard rocks (albite) behaves. Albite (Na-plagioclase) has a congruent dissolution... 

Solubilities of annealed skeletal carbonates were estimated by Land (1967) by allowing the system to reach a steady state pH and by determining dissolved Ca2+ and Mg2+ concentrations. Dissolution of the magnesian calcites in Land s experiments appeared to be congruent in the sense that the steady state solution had a molar Ca2+/Mg2+ ratio similar to that of the solid. 

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