Desorption of Soil Contaminants Due to Rainwater Infiltration

Rainwater infiltration through soils at landfills and other waste sites containing adsorbed chemical contaminants results in the continuous release of leachates into the ground-water environment. Due to continuous desorption of contaminants, the soils are progressively cleansed, and the contaminant concentration of the leachate diminishes with time. This paper presents a simple approach to estimate leachate concentration, residual contaminant levels of soils, and quantities of contaminants released into the ground-water environment after specified years of infiltration. Two desorption processes are analyzed: one using a constant distribution coefficient, and the other following Langmuir's equilibrium adsorption isotherm. This approach can be used to assess preand postremediation impacts of leachates originating at a waste site on ground-water environment in the vicinity.