Wednesday, May 28, 2008 - 11:15 AM
400

Nitrification and denitrification response to varying periods of desiccation and inundation in a western kansas stream

Bradley J. Austin, Department of Biological Sciences, Fort Hays State University, 600 Park St., Hays, KS 67601 and Eric A. Strauss, Department of Biology, University of Wisconsin - La Crosse, 1725 State St., La Crosse, WI 54601.

Changing environmental conditions and increased water consumption has transformed many historically perennial stream systems into intermittent systems.  Multiple drying and wetting events throughout the year may impact many stream processes.  Two such processes, nitrification and denitrification, are also key components of the nitrogen cycle.  During summer 2007, an experimental stream constructed adjacent to the Saline River in Western Kansas was used to determine the effects of desiccation and rewetting of stream sediment on nitrification and denitrification potentials.  Mean nitrification and denitrification rates in sediment not dried (controls) were 0.431 ± 0.017 μg NO3--N/cm2/h and 0.926 ± 0.106 μg N2O-N/cm2/h, respectively.  As sediment samples dried, nitrification rates decreased.  Sediments dried less than seven days recovered within one day of being rewetted.  Denitrification rates were not negatively affected by one day of drying, while samples dried greater than one day experienced reduced rates of denitrification.  Denitrification in sediments dried seven days or less recovered by day seven of being rewetted.  Rates in sediments dried greater than seven days did not fully recover, for either process, even after 28 days of being rewetted.  These results demonstrate that alterations in stream’s hydrology can significantly affect nitrogen cycle processes.


Web Page: Nitrification, Denitrification

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