Spatial and temporal variations in the geochemistry of shallow groundwater contaminated with nitrate at a residential site.

The concentrations of nitrate (NO), major ions, and dissolved inorganic carbon (DIC) and the stable carbon isotopes of DIC (δC) in shallow groundwater below a 45 × 60 m residential property was investigated over a period of 38 months. Our aim was to identify the processes which control the spatial and temporal distribution of NO in the shallow groundwater and assess water-rock interactions linked to denitrification. Groundwater sampled quarterly from eight locations showed an average NO concentration of 36.