1. Skip to navigation
  2. Skip to content
  3. Skip to sidebar

Comments on Gigapan: Lake Untersee, Queen Maud Land, Antarctica

  2. Lake Untersee, November 2008. Dr. Valery Galchenko of the Winogradsky Institute of Microbiology, Russian Academy of Sciences, Russia is seen walking across the lake back to our camp. Lake Untersee is one of the largest (11.4 km2) and deepest (>160 m) freshwater lakes in East Antarctica. Located at 71•S, the la...

    • 239295-210x140

    • Stats

      Favorites
      0
      Comments
      2
      Snapshots
      1
      Total Views
      1397
      Explore Score
      92

GigaPan Comments (2)

Toggle Minimize gigapan_comment
  1. Dale Andersen

    Dale Andersen (September 28, 2011, 06:36AM )

    The short answer is that the high pH is a result of the weathering of the local rocks (anorthosite) contributing hydroxyl (OH-) ions, along with the presence of the ice-cover that helps keep CO2 from dissolving in the water - which would reduce the pH. The pH of the water is not so high that it burns you - we drink the water and dive in it to explore the lake bottom. Unfortunately the pH of the lake water has been compared to bleach elsewhere online, which is simply not true. The longer answer, which can be found in our paper about the lake (see the link above, you can download the paper for free) is: The high pH has been attributed to weathering of plagioclase supplied by anorthosite in the lake catchment, which produces high calcium, high pH, low dissolved inorganic carbon (DIC) waters. Specifically, plagioclase weathering consumes CO2 and, in water in equilibrium with the atmosphere, raises pH to 8.3. Lake Untersee, however, appears to be isolated from the atmosphere by the ice cover, effectively limiting CO2 influx. Thus, plagioclase weathering is dominated by reaction with water, e.g.: 2NaCaAl3Si5O16 9 H2O = 2Na 2 Ca2 6OH- 4SiO2 3Al2Si2O5(OH)4, which in addition to raising pH, provides abundant calcium (and silica) to solution. Chemical modeling shows that this situation is stable only when DIC is maintained at low concentration (30 μmol/l); any influx of CO2 results in precipitation of calcite and a drop in pH (Andersen et al. 2011).

  2. Tom Nelson

    Tom Nelson (September 27, 2011, 09:19PM )

    What accounts for the extreme alkalinity of the water? Would it be strong enough to cause skin burns?