Nitrogen dynamics in two high elevation catchments during spring snowmelt 1996, Rocky Mountains, Colorado

Snowpack, soil, soil leachate, and streamwater samples were analyzed for inorganic nitrogen (N) to quantify the net effect of soil processes on N export during spring snowmelt. The two catchments used for this work, Snake River and Deer Creek, are located in Summit County, Colorado and range in elevation from 3350 to 4120 m. Atmospheric N loading to the snowpack, 88 mg N m^-2 (=0·88 kg N ha^-1), was representative of low N deposition sites in the Rocky Mountains. Potentially mobile inorganic N in soil, 1252 to 1868 mg N m^-2, was much greater than N inputs from snow. During spring snowmelt, nitrate (NO₃^-) leachate from alpine soil, 702 mg N m^-2, was significantly greater than from sub-alpine forest and meadow soils (p < 0·001). This pattern in soil leachate was consistent with streamwater N concentrations in Deer Creek, indicating the importance of soil processes in regulating N export from these high elevation catchments. Soils may function as sources or sinks of N during spring snowmelt; alpine soils were a significant source of N to the stream, while sub-alpine soils were possible N sinks.