Biogeochemistry

, Volume 73, Issue 3, pp 439–455

Whole-system estimation of denitrification in a plains river: a comparison of two methods

  • Alena L. Pribyl
  • James H. Mccutchan
  • William M. Lewis
  • James F. Saunders III
Article

DOI: 10.1007/s10533-004-0565-4

Cite this article as:
Pribyl, A., Mccutchan, J., Lewis, W. et al. Biogeochemistry (2005) 73: 439. doi:10.1007/s10533-004-0565-4

Abstract.

Whole-system denitrification in the South Platte River was measured over a 13-month period using an open-channel N2 method and mass-balance measurements. Concentrations of dissolved N2 were measured with high precision by membrane-inlet mass spectrometry and estimates of denitrification were based on the mass flux of N2, after correction for reaeration and groundwater flux. Open-channel estimates of denitrification ranged from 0 to 3.08 g N m−2 d−1 and the mean annual rate was 1.62 g N m−2 d−1, which corresponds to removal of approximately 34% of the nitrate transported by the river over a distance of 18.5 km. Over the same period of time, estimates of denitrification based on mass-balance measurements ranged from 0.29 to 5.25 g N m−2 d−1 and the mean annual rate was 2.11 g N m−2 d−1. The two methods revealed similar seasonal patterns of denitrification the highest rates were measured from late April to August and the lowest rates were in winter. Both methods provide whole-system estimates of denitrification in running waters; where reaeration rate coefficients are low and flux of groundwater is well quantified, the open-channel method has fewer sources of uncertainty and is easier to implement.

Keywords

DenitrificationMass balanceMembrane-inlet mass spectrometryNitrogenOpen-channel N2 methodSouth Platte River

Copyright information

© Springer 2005

Authors and Affiliations

  • Alena L. Pribyl
    • 1
  • James H. Mccutchan
    • 1
  • William M. Lewis
    • 1
  • James F. Saunders III
    • 1
  1. 1.Center for Limnology, Cooperative Institute for Research in Environmental Sciences and Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderUSA