Spotlight
On: Air Sampling - for a long time, people wondered
how fish in Lake Superior were contaminated with synthetic organic
chemicals more typically found in large cities, industrial regions,
and agricultural areas in which pesticides are applied. We have
inferred that this happens through the atmospheric transport,
deposition, and biomagnification of these harmful materials
in the food web of the Lake. Our team is measuring the exchange
of chemicals between the air and the water. Air-water exchange
is the entry point for this exchange-biomagnification process
for certain chemicals, making it a critical process to determine
with accuracy. Meteorological and chemical techniques are combined
to carry out the measurements. The field air sampling equipment
is mounted on a mast in the ship's bow. Measurements are made
along offshore transects, for 1-2 hours at each of several locations,
collecting meteorological data and air and water samples. The
measurements are used to refine predictions of actual loadings,
which currently are estimated based on on-shore measurements.
Mark
Rowe was up in the bow downloading meteorological data from
instruments that measure the heat flux between air and water
when a juvenile saw-whet owl flew out from land to visit
the Lake Guardian
