Seasonal dynamics of dissolved nitrogen species in two High Arctic rivers, Melville Island, Canada
// 16th international symposium and workshop "Northern research Basins". Petrozavodsk: KarRC RAS, 2007. Pp. 74-82
Keywords: Nitrogen, High Arctic rivers, nutrient fluxes, DON, NO3-, NH4 +.
This study examines the magnitude, seasonal patterns, and characteristics N export from two small watersheds on Melville Island, in the Canadian High Arctic. The dominant N species in both rivers was dissolved organic nitrogen (DON), comprising >80% of the seasonal nitrogen flux from both rivers. The total DON and dissolved inorganic nitrogen (DIN) mass fluxes from the two catchments were similar (242 and 245 kg DON, and 42-45 kg DIN), but there were differences in the patterns and concentrations of the DIN species in the two catchments. The West river had higher initial DON and DIN concentrations that decreased to stable concentrations around 0.150 ppm and 0 ppm by mid July. The East river had variable early season DON and NO3 -concentrations ranging from 0.138-0.415, and 0-0.125 ppm, respectively. End of season DON and DIN concentrations increased from 0.134 to 0.240, and 0 to 0.085 ppm, respectively. The DOC:DON ratio also decrease from 13 to 6, indicating a change in the composition of dissolved organic matter in this river at the end of season. The total DON fluxes from these two small arctic watersheds are similar to fluxes reported for other catchments in temperate environments.