Nitrate (NO3-) loss from agriculture to shallow groundwater and transferral to sensitive aquatic ecosystems is of global concern. Denitrifying bioreactor technology, where a solid carbon (C) reactive media intercepts contaminated groundwater, has been successfully used to convert NO3- to di-nitrogen (N-2) gas. One of the challenges of groundwater remediation research is how to track denitrification potential spatially and temporally within reactive media and subsoil. First, using delta N-15/delta O-18 isotopes, eight wells were divided into indicative transformational processes of 'nitrification' or 'denitrification' wells. Then, using N-2/argon (Ar) ratios these wells were divided into 'low denitrification potential' or high denitrification potential' categories. Secondly, using falling head tests, the saturated hydraulic conductivity (K-sat) in each well was estimated, creating two groups of 'slow' (0.06 m day(-1)) and 'fast' (0.13 m day(-1)) wells, respectively. Thirdly, two 'low denitrification potential' wells (one fast and one slow) with high NO3- concentration were amended with woodchip to enhance denitrification. Water samples were retrieved from all wells using a low flow syringe to avoid de-gassing and analysed for N-2/Ar ratio using membrane inlet mass spectrometry. Results showed that there was good agreement between isotope and chemical (N-2/Ar ratio and dissolved organic C (DOC)) and physio-chemical (dissolved oxygen, temperature, conductivity and pH) parameters. To explain the spatial and temporal distribution of NO3- and other parameters on site, the development of predictive models using the available datasets for this field site was examined for NO3-, Cl-, N-2/Ar and DOC. Initial statistical analysis was directed towards the testing of the effect of woodchip amendment. The analysis was formulated as a repeated measures analysis of the factorial structure for treatment and time. Nitrate concentrations were related to K-sat and water level (p <0.0001 and p = 0.02, respectively), but did not respond to woodchip addition (p = 0.09). This non-destructive technique allows elucidation of denitrification potential over time and could be used in denitrifying bioreactor technology to assess denitrification hotspots in reactive media, while developing a NO3- spatial and temporal predictive model for bioreactor site specific conditions. (C) 2011 Elsevier B.V. All rights reserved.