Dissolved inorganic nitrogen and stable isotopes of nitrate in Svalbard runoff

The concentrations of dissolved inorganic nitrogen (mostly nitrate, but also ammonium) in glacial runoff from the Kongsfjorden and Adventalen regions in West Spitsbergen, Svalbard are presented for the interval 1991 to 2025. Also included are chloride concentrations and daily average discharge. All samples were collected, processed and analysed in a standardised manner as described in Hodson et al (In Press). A particularly important reason for the data collection (from 2000 onwards) was to establish the concentrations and sources of non-atmospheric nitrate derived from nitrification. Samples of streamflow in the Adventdalen regions are very strongly influenced by this process, and therefore reveal some of the highest nitrate concentrations in runoff from the glacial and periglacial environments. By contrast, high concentrations in runoff from the Kongsfjorden region show a greater dependence upon atmospheric nitrate release by snowmelt. The nitrate values were determined using either standard colorimetric techniques or ion chromatography with chemical baseline suppression, allowing low limits of detection suitable for glacial meltwaters (ca. 0.01 mg/L or 0.002 mg N/L). Ammonium concentrations were only analysed using colorimetric techniques. Although the series are not continuous, the data are ideal for establishing seasonal changes and runoff fluxes. Stable isotopes of N and O in nitrate are also presented for a smaller subset of the data following their determination using the bacterial denitrification method at the same laboratory (The Kaiser Lab, University of East Anglia, Norwich, UK). A systematic analysis of the data set is presented by Hodson et al (In Press). All sampling locations, including the catchment areas, location (in UTM coordinates), dates of sampling and number of visits are described in Tab 2 of the Excel data file. The analytical processes are described in “Methods.pdf”.