Multicomponent reactive transport modelling of ammonium contamination at a former coal carbonisation plant

Ammonium is observed as the main inorganic contamination in groundwater at a former coal carbonisation plant in Mansfield UK. Natural attenuation of ammonium occurs primarily due to retardation by cation exchange with the native cations present in the aquifer and to a lesser degree due to re-oxidation by recharge and flushing with oxygenated water. In order to simultaneously account for ion exchange of multiple, competing cations and aqueous complexation reactions, a multicomponent reactive transport model was selected to simulate the fate, i.e., transport and reactions, of ammonium. This paper gives an overview of the employed multicomponent reactive transport model, PHT3D (Prommer, 2002; Prommer et al., 2001) and shows an application to the field site.