Formation and character of an ancient 19-m ice cover and underlying trapped brine in an "ice-sealed" east Antarctic lake.
Lake Vida, one of the largest lakes in the McMurdo Dry Valleys of Antarctica, was previously believed to be shallow (<10 m) and frozen to its bed year-round. New ice-core analysis and temperature data show that beneath 19 m of ice is a water column composed of a NaCl brine with a salinity seven times that of seawater that remains liquid below -10 degrees C. The ice cover thickens at both its base and surface, sealing concentrated brine beneath. The ice cover is stabilized by a negative feedback between ice growth and the freezing-point depression of the brine. The ice cover contains frozen microbial mats throughout that are viable after thawing and has a history that extends to at least 2,800 (14)C years B.P., suggesting that the brine has been isolated from the atmosphere for as long. To our knowledge, Lake Vida has the thickest subaerial lake ice cover recorded and may represent a previously undiscovered end-member lacustrine ecosystem on Earth.
Doran
Peter T
PT
Department of Earth and Environmental Sciences, University of Illinois, 845 West Taylor Street, MS 186, Chicago 60607, USA. pdoran@uic.edu
Fritsen
Christian H
CH
McKay
Christopher P
CP
Priscu
John C
JC
Adams
Edward E
EE
D000864:Antarctic Regions; D007053:Ice; D012623:Seawater; D012965:Sodium Chloride; D013696:Temperature; D013816:Thermodynamics
D007053:Ice; D012965:Sodium Chloride