KochJC, University of Colorado/INSTAAR, Boulder, USA, kochjc@colorado.edu
McKnight, D, M, University of Colorado/INSTAAR, Boulder, USA, 
Gooseff, M, N, Colorado School of Mines, Golden, USA, 
Baeseman, J, , Kent State University, Kent, USA, 
 
QUANTIFYING NITRATE UPTAKE IN AN UNSTEADY, ANABRANCHING, ANTARCTIC STREAM (Abstract ID: 829)
In the McMurdo Dry Valleys of Antarctica, biotic uptake limits nutrient transport in glacial meltwater streams containing abundant cyanobacterial mats. Nutrients are delivered to lakes predominantly from streams without mat growth. We injected nitrate into Huey Creek to understand nutrient dynamics in a stream with minimal mats. Tracer data is typically analyzed with a transient storage model (TSM), which accounts for changes in tracer concentration by modeling storage and biological processes. However, daily flood pulses lead to temporal variations in hyporheic exchange, storage, and nutrient decay, precluding straight-forward use of a TSM. These floods move stream water into lateral branches away from the main channel, potentially creating stable habitats where bacteria may thrive. As flood pulses subside, branch waters become stagnant, eventually seeping into the subsurface. The mean nitrate concentration decreased from 3.25 to 2.82 mg/L along the stream reach, suggesting that bacterial uptake may be occurring. By combining a TSM with a flow routing and groundwater flow model we hope to gain insight into the location, rates, and types of biological processes occurring in Huey Creek.
 
http://www.mcmlter.org/
Presentation is (Oral, Poster or No Preference): Poster
Presentation is given by student: Yes
   
 
           
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