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This article in JEQ

  1. Vol. 13 No. 4, p. 514-518
     
    Received: Oct 6, 1983


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doi:10.2134/jeq1984.00472425001300040002x

Denitrification Associated with Stream Periphyton: Chamber Estimates from Undisrupted Communities1

  1. J. H. Duff,
  2. F. J. Triska and
  3. R. S. Oremland2

Abstract

Abstract

Undisrupted periphyton communities from a N-rich (NO3 = 63 µmol L−1) and pristine (NO3 = 2.9 µmol L−1) stream were assayed for denitrifying activity (acetylene-blockage technique) in 40-L chambers incubated at in situ temperature and nutrient concentrations. Nitrous oxide formation associated with periphyton from the N-rich stream was immediate and linear (52.1 µmol N2O m−2 h−1) in the dark, anaerobic chamber (50 kPa C2H2). In the corresponding light, aerobic chamber (50 kPa C2H2), N2O production was inhibited by 82% (9.3 µmol N2O m−2 h−1). Nitrous oxide formation was not associated with periphyton from the pristine stream incubated in situ, either with or without NO3 amendment.

Denitrification estimates made with undisrupted periphyton communities at in situ temperature and nutrient concentrations (40-L chambers) were less variable than estimates made with periphyton “scrapings” in small flasks (room temperature). The calculated diel periphyton-associated denitrification rate based on a 14-h light-10-h dark day was 651 µmol N2O m−2 d−1. The data suggest denitrification within periphyton mats may contribute toward removal of NO3 from N-rich fluvial environments.

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