NITROGEN AND PHOSPHORUS CONCENTRATIONS AND EXPORT FOR THE UPPER KUPARUK RIVER ON THE NORTH SLOPE OF ALASKA IN 1980

Nitrogen and phosphorus concentrations were measured from May to August 1980 in the upper Kuparuk River, a tundra stream on the North Slope of Alaska. Mean values for nitrogen were 10.8 mug N l-1 for ammonium, 21.4 mug N l-1 for nitrate plus nitrite and 248 mug N l-1 for dissolved organic nitrogen. Mean values for phosphorus were 8. 1 mug P l-1 for total dissolved phosphorus and 4.7 mug P l-1 for fine particulate phosphorus. Nitrate concentrations were inversely correlated with flow whereas particulate phosphorus concentrations increased during high flows. Export of nitrogen and phosphorus from the watershed during 1980 was estimated to be 4.69, 3.25 and 91 kg km-2 yr-1 for NO3-N, NH4-N and DON-N, respectively, and 2.86 and 3.03 kg km-2 yr-1 for TDP-P and PP-P. Both the relative concentrations of N and P and the relative amounts exported suggest that phosphorus is in short supply but both nutrients are present in low concentrations comparable to those found previously in tundra ponds at Point Barrow, Alaska.