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 162° 163° 77°45’ 77°35’ Geography Hydrology & meteorology Lake Bonney Lake Hoare Lake Fryxell Andersen Creek

Taylor Valley Lake Levels Figure courtesy of Peter Doran, Univ. Illinois, Chicago Year Change in lake depth since January 1972 (meters) ’72 – ‘91 ’92 – ’01* ‘02 – ‘11 * Flood year

 lake level  lake level Data courtesy of Peter Doran, Univ. Illinois, Chicago  lake level  lake level

Taylor Valley lakes water isotope vs. depth work Matsubaya et al. (1979) Lyons et al. (1999) Gooseff et al. (2006) season courtesy of Carolyn Dowling, Ball State University season with the aid of the MCM- LTER group “Limno Team” Photo courtesy of A. Chiuchiolo

Annual/decadal variations in salinity and δ 18 O of lake surface waters ’72 – ’91:   lake levels ’92 – ’02:  lake levels ‘03 – ‘11:  lake levels

Map -33.7‰ -31.2‰ -29.5‰ N Canada Glacier Lake Hoare (δ 18 O -35.9‰ to -32.4‰) Historical δ 18 O Canada Glacier ice and melt regimes to Lake Hoare Oxygen isotope data compiled by D. Leslie, Ohio State Andersen Creek

December and January Lake Hoare surface waters -35.9‰ to -32.4‰ Andersen Creek -31.2‰ to -28.4‰* freezing (February - November) lake ice +3‰ enrichment** Canada Glacier ** O’Neil (1968) glacier snow and ice -33.7‰ to -29.5‰ Lake Hoare basin δ 18 O * Anderson Creek data from 2010 and from personal communication with D. Leslie, Ohio State

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 MCM-LTER project Dr. W. Berry Lyons, Kathleen Welch, Deborah Leslie, Christopher Gardner, ‘11- ‘12 MCM-LTER “Limno Team”