Modelling seawater intrusion in a resin-filled column to study cationic exchange and gypsum precipitation

Abstract

Laboratory column experiments are necessary to the understanding of the reactive transport behavior of inorganic chemical species when dealing with environmental problems such as fresh- or seawater intrusions into aquifers, landfill leaching plumes, or transport of heavy metals in soils and aquifers. In the case of seawater intrusion, cationic exchange is one of the main chemical reactions analyzed. This process occurs when cations from seawater (mainly sodium and magnesium) displace calcium ions on sediment exchange sites. In previous studies of the reactive transport processes of seawater intrusion, column experiments were carried out by displacing synthetic freshwater with seawater along a sediment column 100 cm in length. Moreover, application of a multicomponent reactive model to the experimental data showed gypsum precipitation dissolution to be taking place, in addition to cation exchange.