Equilibrium composition and properties of soil solutions

• Published in: Eurasian soil science 2011-10, Vol.44 (10), p.1068-1076
• Main Authors: Shoba, V. N., Sen’kov, A. A.
• Format: Article
• Language: English
• Subjects: Calcium; Chemical potential; Earth and Environmental Science; Earth Sciences; Equilibrium; Geochemistry; Geotechnical Engineering & Applied Earth Sciences; Magnesium; Soil Chemistry; Soil properties; Soil sciences; Soil solution; Soils
• ISSN: 1064-2293; 1556-195X
• DOI: 10.1134/S1064229311100139

The high dynamics of their composition are a characteristic feature of soil solutions, which hampers the use of data on the concentrations and activities of elements in the physicochemical studies of soils. The chemical potentials of independent components, whose values depend of the dynamics of the solution composition only slightly, are more stable and efficient parameters. The calculation of the equilibriums by physicochemical simulation and the data on the composition of the water extracts and soil solutions indicated that, in the A1 horizon of a leached chernozem, the chemical potential of the calcium varied from −173.8 to −174.3 kcal/mol and that of magnesium varied from −150.9 to −151.5 kcal/mol when the calcium and magnesium concentrations changed by more than 20 times. In the B1 horizon of the crusted solonetz, the chemical potential of the sodium varied from −81.3 to −82.0 kcal/mol when its concentration changed by 2–3 times. The determination of the chemical potentials of the independent components (K, Na, Ca, Mg, Mn, Fe, Al, and Si) in the relatively simple basis subsystem of the solution and single-component mineral phases with known solubilities allows calculating the standard Gibbs energies of the other soil phases equilibrated with the solution.