DISSOLUTION AND TRANSPORT OF GYPSUM IN SOILS .2. EXPERIMENTAL

Experimental information on the dissolution of gypsum and the subsequent transport of the dissolved species in a soil-water system was obtained by adding distilled water to the top of 30-cm long columns containing a soil-gypsum mixture and by measuring the calcium concentration in the solution phase as a function of time at different positions in the columns. The measured concentration-time curves are compared with results from two models - the first based on equilibrium chemical principles and the mixing-cell concept, and the second based on a combination of the one-dimensional convection-dispersion equation and a first-order kinetic expression describing the dissolution process.