The geochemistry of supraglacial streams of Canada Glacier, Taylor Valley (Antarctica), and their evolution into proglacial waters

• Published in: Aquatic Geochemistry
• Main Authors: Fortner, SK, Tranter, M, Fountain, A, Lyons, WB, Welch, KA
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: SOUTHERN VICTORIA LAND; MCMURDO DRY VALLEYS; CHEMICAL DENUDATION; ALPINE; GLACIOCHEMISTRY; HYDROCHEMISTRY; CHEMISTRY; TRANSPORT; SEDIMENT; SILICATE; Anderson Creek; Austral; Canada; Canada Glacier; Glacier Taylor; Hoare; Lake Hoare; McMurdo Dry Valleys; Taylor Valley; Victoria Land; Antarc*; Antarctica; glacier*
• Online Access: https://pure.au.dk/portal/en/publications/834f1c14-9d9c-4dff-a956-78bc0989307a; https://doi.org/10.1007/s10498-004-7373-2

We have investigated the geochemistry of supraglacial streams on the Canada Glacier, Taylor Valley, Antarctica during the 2001-2002 austral summer. Canada Glacier supraglacial streams represent the link between primary precipitation (i.e. glacier snow) and proglacial Lake Hoare. Canada Glacier supraglacial stream geochemistry is intermediate between glacier snow and proglacial stream geochemistry with average concentrations of 49.1 mu eq L-1 Ca2+, 19.9 mu eq L-1 SO42-, and 34.3 mu eq L-1 HCO3-. Predominant west to east winds lead to a redistribution of readily soluble salts onto the glacier surface, which is reflected in the geochemistry of the supraglacial streams. Western Canada Glacier supraglacial streams have average SO42-:HCO3- equivalent ratios of 1.0, while eastern supraglacial streams average 0.5, suggesting more sulfate salts reach and dissolve in the western supraglacial streams. A graph of HCO3- versus Ca2+ for western and eastern supraglacial streams had slopes of 0.87 and 0.72, respectively with R-2 values of 0.84 and 0.83. Low concentrations of reactive silicate (> 10 mu mol L-1) in the supraglacial streams suggested that little to no silicate weathering occurred on the glacier surface with the exception of cryoconite holes (1000 mu mol L-1). Therefore, the major geochemical weathering process occurring in the supraglacial streams is believed to be calcite dissolution. Proglacial stream, Anderson Creek, contains higher concentrations of major ions than supraglacial streams containing 5 times the Ca2+ and 10 times the SO42-. Canada Glacier proglacial streams also contain higher concentrations (16.6-30.6 mu eq L-1) of reactive silicate than supraglacial streams. This suggests that the controls on glacier meltwater geochemistry switch from calcite and gypsum dissolution to both salt dissolution and silicate mineral weathering as the glacier meltwater evolves. Our chemical mass balance calculations indicate that of the total discharge into Lake Hoare, the final recipient of Canada Glacier ...