Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

inverted onto the ice surface and the top 10 cm, which had
originally been at the bottom of the core, was cut off with a
hand saw and stored in a polyethylene bag for analysis for
epontic algae. The remaining ice core was cut down with a
solvent cleaned carbon steel blade to fit a solvent cleaned, dry
aluminum melting tank (35 x 30 x 90 cm) placed over it. The tank
and ice'core were then turned over and the core cut off at the
top of the tank leaving a cleanly collected ice block in the
melting tank. A lid was secured to the tank which was taken back
to the lab. Using this procedure, a large (50 - 55 kg) ice
sample could be cleanly collected, contacting only solvent
cleaned metal and teflon surfaces.
Filtration and Extraction
A teflon and glass stopcock was installed into a fitting on
the tank bottom and the tank heated with two 6000 BTU/h stoves
until most of the ice had been melted. The melt water was not
allowed to exceed 5°C during processing. A 142 mm filter with a
Gelman AE glass fibre filter and an Amberlite XAD-2 extraction
column were connected to the stopcock and the melt water run out
through the column at a flow rate of less than 100 mL/min.
2.4 Chlorinated Hydrocarbons in Snow
On the initial two trips, snow was collected using a
solvent cleaned aluminum scoop. A cleaned aluminum melting tank
(30 x 35 x 90 cm) was filled with surface snow (upper 5 cm)
collected from locations at least 1.5 km and up wind from the
main camp and away from any likely source of contamination. The
contents of the tank were compressed to increase sample weight.
The tank was capped, taken back to the lab, fitted with a teflon
in glass stopcock and the snow sample melted using two 6000 BTU/h
camp stoves. To increase sample volume, the tank and melted
contents were taken back to the sample site and refilled with
fresh snow which, when melted, provided a sample of 45 - 55 L.