SS3.01 Landscape Control of High Latitude Lake and River Ecosystems
Date: Thursday, June 13, 2002
Time: 10:00:00 AM
Location: Carson A
 
LyonsWB, The Ohio State University, BPRC, Columbus, USA, lyons.142@osu.edu
Welch, K, A, The Ohio State University, BPRC, Columbus, USA, welch.189@osu.edu
McKnight, D, M, University of Colorado, INSTAAR, Boulder, USA, mcknight@snobear.colorado.edu
Fountain, A, G, Portland State University, Portland, USA, bjaf@pdx.edu
Priscu, J, C, Montana State University, Bozeman, USA, jpriscu@montana.edu
 
RECENT GEOCHEMICAL EVOLUTION OF THE MCMURDO DRY VALLEY LAKES: THE ROLE OF LEGACY VS. LANDSCAPE POSITION
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Since the initial measurements in the late 1950s, the geochemistry of the perennial ice-covered lakes in Southern Victoria Land (~78S) have baffled polar limnologists. Some lakes are fresh, some are saline, and major solute chemistry differs from lake to lake. Since the initiation of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program in 1993, we have a better assessment of the controls of geochemical evolution of these lakes. Essentially, there are three important variables that control the chemistries of the lakes and are responsible for their chemical differences. The are: the legacy of previous drawdown events, leading to cryoconcentration and production of the present day hypolimnia, the number, length and gradients of the streams entering the respective lakes, and variations in the glaciochemistry of the alpine glaciers within the valley. The latter two variables affect chemistry of the incoming meltwater, while the former determines the diffusional input of solutes into the surface waters of the lakes from below. The relative importance of these variables allows for the difference in geochemistry found in the surface waters of these lakes.