SOLUTE DISPERSION IN SOIL

ABSTRACT An experimental study of solute transport during one-dimensional sorption of a solution of KC1 into a uniformly packed horizontal soil column of Akuse clay, (a tropical clay loam from Ghana which is dominantly montmorillonitic) and Brookston clay of the Huron Catena (dominantly illitic) is reported in this thesis. A hydrodynamic equation based on the existing theories of irreversible thermodynamics is developed to incorporate the effect of anion exclusion in the usual hydrodynamic equation for one-dimensional flow of solute in soil. This equation is used to calculate the. longitudinal dispersion coefficient D^ in horizontal infiltration experiments where anion exclusion effects were observed. Also, the analysis of hydrodynamic dispersion during one-dimensional horizontal flow developed by Smiles eit al. (1978) is extended to include gravitational effects present during one-dimensional vertical infiltration by using the power series form of solution developed by Elrick et aL. (1979). Simulation methods using computer programs written in system/360 Continuous System Modeling Program (CSMP) are used to solve the equations used in this study. The longitudinal dispersion coefficient is in all the analyses presented in this study, assumed to be independent of the Darcy flux and a function of the water content only.