Wrapping Up – Ulyana

Our last week of work was quite busy and tiring.  Every day, we worked
6-8 hours on the water.  When we weren’t downloading data from weather
stations and temperature buoys, or photos from camera stations, we
were mapping the lake bottom or taking lake temperature, pH and
conductivity measurements.  The whole point of this all is to
characterize the lake basins physically and chemically.  On the
physical side, we want to know temperature variations not only between
the basins, but also with depth.  For example, when the surface of
each basin heats up given the daytime temperatures, how long does it
take for the heat to reach the bottom of the lake?  In addition, how
much heat is it?  This is important, as it can tell us more about how
quickly we can melt a lake ice bottom.  Three out of the four basins
we measured have a layer of debris (rocks and sediment) that act to
insulate the bottom ice from extensive melt, shown through bathymetry,
dredge pulls, and bottom temperatures.

However, in the main basin (the one deepening the most), we measured a
bottom temperature hovering around 0 deg C, indicating ice without a protective
sediment barrier.  This basin is where we expect more lake deepening
due to melt and perhaps subaqueous calving (when ice breaks off from
the bottom of the lake and rises to the surface).  On the chemical
side of things, we are looking at lake waters, ice melt, inflow and
outflow channels.  We are interested in isotopic variations (primarily
oxygen), as well as any stand-out differences in major element
chemistry, the trace element, arsenic (not good in high quantities in
drinking water), and black soot (pollution).

We chose this timeframe on purpose, given that it is right at
post-thaw.  When we return in September to gather more data, it will
be after the lakes have had three months to warm up, given the summer
temperatures.  Then, in mid-November, we will collect data once more,
to represent the post-monsoon season.  All-together, this dataset
should be helpful towards thermal modeling of the lakes and perhaps
even forecasting future changes.


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