Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes,...

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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

Transcript of Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes,...

Page 1: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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 UniversitySchool of Earth Sciences

4 November 2012

Page 2: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

Taylor Valley Lakes

162°

163°

77°4

5’

77°3

5’

• Geography

• Hydrology & meteorology

Lake Bonney

Lake Hoare

Lake

Fryxell

Andersen

Creek

Page 3: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

Taylor Valley Lake Levels

Figure courtesy of Peter Doran, Univ. Illinois, Chicago

Year

Ch

an

ge

in la

ke

de

pth

sin

ce

Jan

ua

ry 1

972

(m

ete

rs)

’72 – ‘91

’92 – ’01*

‘02 – ‘11

* Flood year

Page 4: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

lake level lake level

Data courtesy of Peter Doran, Univ. Illinois, Chicago

lake level lake level

Page 5: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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

Page 6: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

Annual/decadal variations in salinityand δ18O of lake surface waters

’72 – ’91: lake levels

’92 – ’02: lake levels

‘03 – ‘11: lake levels

Page 7: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

Map

-33.7‰

-31.2‰

-29.5‰

N

Canada GlacierLakeHoare(δ18O -35.9‰ to -32.4‰)

Historical δ18O Canada Glacier ice and melt regimes to

Lake Hoare

Oxygen isotope data compiled by D. Leslie, Ohio State

Andersen Creek

Page 8: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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 δ18O

* Anderson Creek data from 2010 and from personal communication with D. Leslie, Ohio State

Page 9: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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

Page 10: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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)

Page 11: Oxygen stable isotopes and chloride concentration in the surface waters of Taylor Valley Lakes, Antarctica, during the past 40 years Julie M. Brown*, W.

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”