Water, Air, and Soil Pollution

, Volume 165, Issue 1, pp 13-35

First online:

Sources of Nitrate in Snowmelt Discharge: Evidence From Water Chemistry and Stable Isotopes of Nitrate

  • Kathryn B. PiatekAffiliated withDivision of Forestry, West Virginia University Email author 
  • , Myron J. MitchellAffiliated withCollege of Environmental Sciences and Forestry, State University of New York
  • , Steven R. SilvaAffiliated withU.S. Geological Survey
  • , Carol KendallAffiliated withU.S. Geological Survey

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


To determine whether NO3 concentration pulses in surface water in early spring snowmelt discharge are due to atmospheric NO3, we analyzed stream δ15N-NO3 and δ18O-NO3 values between February and June of 2001 and 2002 and compared them to those of throughfall, bulk precipitation, snow, and groundwater. Stream total Al, DOC and Si concentrations were used to indicate preferential water flow through the forest floor, mineral soil, and ground water. The study was conducted in a 135-ha subcatchment of the Arbutus Watershed in the Huntington Wildlife Forest in the Adirondack Region of New York State, U.S.A. Stream discharge in 2001 increased from 0.6 before to 32.4 mm day−1 during snowmelt, and element concentrations increased from 33 to 71 μmol L−1 for NO3, 3 to 9 μmol L−1 for total Al, and 330 to 570 μmol L−1 for DOC. Discharge in 2002 was variable, with a maximum of 30 mm day−1 during snowmelt. The highest NO3, Al, and DOC concentrations were 52, 10, and 630 μmol L−1, respectively, and dissolved Si decreased from 148 μmol L−1 before to 96 μmol L−1 during snowmelt. Values of δ15N and δ18O of NO3 in stream water were similar in both years. Stream water, atmospherically-derived solutions, and groundwaters had overlapping δ15N-NO3 values. In stream and ground water, δ18O-NO3 values ranged from +5.9 to +12.9‰ and were significantly lower than the +58.3 to +78.7‰ values in atmospheric solutions. Values of δ18O-NO3 indicating nitrification, increase in Al and DOC, and decrease in dissolved Si concentrations indicating water flow through the soil suggested a dilution of groundwater NO3 by increasing contributions of forest floor and mineral soil NO3 during snowmelt.


natural abundance isotopes nitrate pulses nitrate sources northern hardwood forest N–saturation snowmelt