Stream and soil water biogeochemical solute concentrations in four Southwest Greenland watersheds, 2022-2023

We sampled soil water from four watersheds in southwest Greenland to evaluate the range of concentrations of the greenhouse gas nitrous oxide (N2O) and to assess potential sources and sinks of N2O. The soil waters were measured in the field for parameters including temperature, dissolved oxygen concentration, and specific conductivity, and in the lab for concentrations of various bioreactive solutes in addition to N2O, including nitrate, ammonium, dissolved organic carbon, total dissolved nitrogen, and for organic carbon fluorescence and absorbance values, from which organic carbon lability indicators were derived. Sample sites included watersheds near the coast that were exposed following ice retreat ~11 ky (kiloyears) ago, near the ice margin that were exposed following ice retreat ~6.8 ky ago, and a watershed draining modern glacial ice meltwater. Watersheds with old exposure ages represent net sinks of atmospheric N2O caused by complete denitrification, while the watershed draining glacial meltwater represents a source of atmospheric N2O caused by nitrification reactions.