Interacting precipitation/dissolution waves: The movement of inorganic contaminants in groundwater

Abstract

Chemical reactions with minerals occur in groundwater flow in permeable media to produce zones of constant solid and aqueous phase compositions. These zones are separated by “waves” or step changes in composition. The occurrence of wave‐wave interactions resulting from nonuniform boundary conditions has important implications in inorganic pollutant transport through permeable formations. Three physical flow situations produce these conditions : injection of a finite volume of fluid followed in time by a compositionally different fluid, the flow of a reactive fluid through a compositionally layered media, and reversal in the direction of flow of a chemically reactive fluid. The theory we present when applied to contaminant transport indicates that a significant amount of contaminant initially precipitated can be redissolved during subsequent flow, and the patterns thus evolved can indicate the nature of the contaminating source.