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Chapter 2: MATERIALS
AND METHODS
2.1 -
Study sites
Forty-one Lakes from the Vestfold Hills (68°S 78°E) and Larsemann Hills
(69°24'S, 76° 20'E), and a single sample from Beaver Lake (latitudes and longitudes, and
depths are shown in Table 2.1) were sampled during 2000 (Figure 2.1 a, b and c). The
salinity of these lakes ranged from freshwater to hypersaline (individual lake salinity is
dealt with in Chapter 3). The lakes showed a range of stratification types from
monomictic (Deep Lake), holomictic (Triple Lake) and meromictic (Ace Lake). Beaver
Lake is a large epishelf lake, an unusual system found between ice shelves and
continental land masses. They are freshwater lakes in hydrological contact with the sea,
in that the lake sits on the colder denser seawater.
2.2 -
Sampling
Water samples were obtained with a 2L Kemmener bottle through a
hole drilled
in the ice with a jiffy drill (AAA Products International, 7114 Harry Hines, Dallas, Texas
75235, United States). When it was possible to take depth samples (i. e. lake had ice cover
capable of supporting personnel and equipment) water was collected from Om, 2m, 4m,
8m and l Om (depth of sampling was dictated by the depth of oxygenated waters or depth
of lake). Om depth was taken as the base of the ice cover, and all other depths were taken
from that point. In the absence of ice cover capable of supporting personnel and
equipment, only surface water samples were taken from approximately 1-4m from the
shore (depending on depth gradient of lake). For each sample, 4L of water was taken and
stored in acid washed (10% HCl) polypropylene containers (for inorganic chemical
analysis) and a further 100mL of water was taken in a sterilised glass Duran bottle (for
microbiological
analysis). Ice cores were taken where possible. The cores were obtained
using a Sipre corer, which had been adapted for use with a Stihl drill (Stihl Inc, Virginia
Beach, VA, USA) to provide faster and easier removal of ice cores. Holes were drilled
into the ice using a Jiffy drill to approximately 1m above the ice-water interface. Then the
ice core was taken from this depth to the ice-water interface.
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