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Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years. Julie M. Brown*, W. B. Lyons*, K. A. Welch*, P . Doran, C. B. Dowling, D. M. McKnight, and J. C. Priscu *The Ohio State University School of Earth Sciences
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Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W. B. Lyons*, K. A. Welch*, P. Doran, C. B. Dowling, D. M. McKnight, and J. C. Priscu *The Ohio State University School of Earth Sciences 4 November 2012
Taylor Valley Lakes 163° • Geography • Hydrology & meteorology Lake Fryxell 77°35’ 162° Andersen Creek Lake Hoare Lake Bonney 77°45’
Taylor Valley Lake Levels Change in lake depth since January 1972 (meters) ’92 – ’01* ‘02 – ‘11 ’72 – ‘91 * Flood year Year Figure courtesy of Peter Doran, Univ. Illinois, Chicago
lake level lake level lake level lake level Data courtesy of Peter Doran, Univ. Illinois, Chicago
Taylor Valley lakes water isotope vs. depth work • Matsubaya et al. (1979) • Lyons et al. (1999) • Gooseff et al. (2006) • 2005-2006 season courtesy of Carolyn Dowling, Ball State University • 2011-2012 season with the aid of the MCM-LTER group “Limno Team” Photo courtesy of A. Chiuchiolo
Annual/decadal variations in salinityand δ18O of lake surface waters ‘03 – ‘11: lake levels ’92 – ’02: lake levels ’72 – ’91: lake levels
Historical δ18O Canada Glacier ice and melt regimes to Lake Hoare Map -29.5‰ -31.2‰ Andersen Creek -33.7‰ Canada Glacier Lake Hoare (δ18O -35.9‰ to -32.4‰) N Oxygen isotope data compiled by D. Leslie, Ohio State
Lake Hoare basin δ18O December and January Canada Glacier Andersen Creek -31.2‰ to -28.4‰* glacier snow and ice -33.7‰ to -29.5‰ lake ice +3‰ enrichment** freezing (February - November) Lake Hoare surface waters -35.9‰ to -32.4‰ * Anderson Creek data from 2010 and from personal communication with D. Leslie, Ohio State ** O’Neil (1968)
Conclusions • The Taylor Valley lake surface waters vary with time isotopically • Heterogeneous glacier ice • Degree of variability depends on hydrology • Isotopic fractionation processes vary with climate • Lake Hoare surface waters are getting isotopically lighter during last 5-6 years • Significant melting of the foot of Canada Glacier relative to Andersen Creek water
Future work • Continued annual (and seasonal) collection of lake water column isotope data • More spatial Taylor Valley glacier ice isotope samples • Model isotope data of streams, glaciers, and lakes (and lake ice)
Acknowledgements • This work was supported by NSF Grant OPPP-ANT-1115245 • MCM-LTER project • Dr. W. Berry Lyons, Kathleen Welch, Deborah Leslie, Christopher Gardner, ‘11-‘12 MCM-LTER “Limno Team”