Nitrogen transformation and transport modeling in groundwater aquifers

Nitrogen pollution in urban and rural groundwater is a common problem and it poses a major threat to groundwater-based drinking water supplies. In this study, a kinetic model is developed to study nitrification–denitrification reactions in groundwater aquifers. A new reaction module for the reactive transport in three-dimensions (RT3D) code is developed and tested to describe the fate and transport of nitrogen species, dissolved oxygen (DO), dissolved organic carbon (DOC) and biomass. The proposed model is verified against some published numerical results and analytical solutions. The model is later used to study the field-scale nitrogen transformations at a cattle feedlot site within the Vasse Research Station, located south of Busselton in Western Australia. Modeling results compare favorably with the field data. The developed model describing nitrification and denitrification reactions is a useful framework for simulating the fate and transport of nitrogen species in groundwater aquifers.