Modeling Nitrogen Transformations in Dry Valley Streams, Antarctica

  1. John C. Priscu
  1. Daryl L. Moorhead1,
  2. Diane M. Mcknight2 and
  3. Cathy M. Tate3

Published Online: 16 MAR 2013

DOI: 10.1029/AR072p0141

Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica

Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica

How to Cite

Moorhead, D. L., Mcknight, D. M. and Tate, C. M. (1998) Modeling Nitrogen Transformations in Dry Valley Streams, Antarctica, in Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica (ed J. C. Priscu), American Geophysical Union, Washington, D. C.. doi: 10.1029/AR072p0141

Author Information

  1. 1

    Department of Biological Sciences, Texas Tech University, Lubbock, Texas

  2. 2

    Civil, Environmental, and Architectural Engineering Department, Instaar, Boulder, Colorado

  3. 3

    United States Geological Survey, Water Resources Division, Denver, Colorado

Publication History

  1. Published Online: 16 MAR 2013
  2. Published Print: 28 JAN 1998

ISBN Information

Print ISBN: 9780875908991

Online ISBN: 9781118668313

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Keywords:

  • Desert ecology—Antarctica—McMurdo Dry Valleys

Summary

Concentrations of ammonium, nitrate, and urea decline along a glacial meltwater stream in Taylor Valley, southern Victoria Land, Antarctica. These reductions accompany increasing concentrations of particulate and dissolved organic nitrogen (other than urea), suggesting that benthic microbial mats present in these systems may be responsible for transforming dissolved inorganic nitrogen into dissolved and particulate organic compounds. A mathematical model of primary production of microbial mats was used to estimate nitrogen transformation, assuming that nitrogen uptake balanced carbon fixation. Export of organic nitrogen was set equal to inorganic uptake driven by net primary production, based on the assumption of steady-state biomass for mat communities. Model results were comparable to observations although transformation rates generally were lower than observed. The model was sensitive to water retention time in the stream, illustrating the critical importance of accurate assessments of stream geometry and hydrology. Application of this model to three other streams feeding Lake Fryxell (Taylor Valley) suggest that dry valley streams have a large potential to transform mineral nitrogen into organic forms.