, Volume 39, Issue 3, pp 327–342 | Cite as

Denitrification as a component of the nitrogen budget for a large plains river

  • Arne L. Sjodin
  • William M. LewisJr.
  • James F. Saunders III


Nitrogen dynamics of a plains reach of the SouthPlatte River were studied over a 12-month cycle forthe purpose of quantifying denitrification rates. The working hypothesis of the study was thatdenitrification would be of extraordinary importancein the system because of large amounts of waterexchange between the channel and an extensivesubsurface alluvium consisting of gravel. Denitrification losses of nitrate were quantifiedthrough the use of a mass-balance model based ondetailed hydrologic information and fieldquantification of the rates of nitrate accrualthrough surface and subsurface input of water aswell as nitrification. Denitrification rates ranged between 2and 100 mg N/m2/hr. Distancerequired to achieve 90% reduction of nitrate was asshort as 6 km during mid-summer and as long as300 km during mid-winter. On an annual basis, closeto half of nitrate input to a 100-km reach was removed bydenitrification (3.6 × 106 kg/yr). Rates of nitrate loss to denitrification (annual mean, 28 mgN/m2/h) and overall percent removalof nitrate by denitrification were approximately 10times as high as rates documented for rivers in theeastern U.S. The study shows that high rates ofhyporheic exchange can support extraordinary ratesof denitrification.

alluvial exchange denitrification hyporheic zone nitrogen budget 


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Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Arne L. Sjodin
    • 1
  • William M. LewisJr.
    • 1
  • James F. Saunders III
    • 1
  1. 1.Center for LimnologyUniversity of ColoradoBoulderU.S.A

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