title: Oxygen supersaturation in ice-covered Antarctic lakes:  biological versus physical contributions.
abstract: Freezing in ice-covered lakes causes dissolved gases to become supersaturated while at the same time removing gases trapped in the ablating ice cover.  Analysis of N2, O2, and Ar in bubbles from Lake Hoare ice shows that, while O2 is approximately 2.4 times supersaturated in the water below the ice, only 11% of the O2 input to this lake is due to biological activity:  89% of the O2 is derived from meltwater inflow.  Trapped bubbles in a subliming ice cover provide a natural "fluxmeter" for gas exchange: in Lake Hoare as much as 70% of the total gas loss may occur by advection through the ice cover, including approximately 75% of the N2, approximately 59% of the O2, and approximately 57% of the Ar losses.  The remaining gas fractions are removed by respiration at the lower boundary (O2) and by molecular exchange with the atmosphere in the peripheral summer moat around the ice.
authors.affiliation: Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093, USA.
authors.forename: H
authors.initials: H
authors.lastname: Craig
authors.forename: R A
authors.initials: RA
authors.lastname: Wharton
authors.forename: C P
authors.initials: CP
authors.lastname: McKay
mesh_terms: D000864:Antarctic Regions; D001128:Argon / Q000032:analysis; D001272:Atmosphere; D003081:Cold Climate; D056890:Eukaryota; D005618:Fresh Water; D007053:Ice; D018535:Mars; D008956:Models, Chemical; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis*; D010788:Photosynthesis
chemical_list: D007053:Ice; D001128:Argon; D009584:Nitrogen; D010100:Oxygen