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Report on the Victoria University of Wellington Antarctic Expedition 1963-64: VUWAE 8
Chemistry of Lakes
Chemistry of Lakes
Samples for chemical analysis were pumped from various depths in Lakes Fryxell, Chad, Bonney, Diana (Taylor Valley), and also from two unnamed lakes, one in the Taylor Valley and one in the Wright Valley. Chloride, bicarbonate, end total hardness titrations were performed in the field. These determinations were checked in the laboratory and determination of sodium, potassium, calcium and magnesium is proceeding. Samples of inflow waters were also taken from all the lakes visited.
Lake Don Juan.
This lake is a shallow lake (approximately 3 feet deep) situated in the south fork of the bright Valley, and its waters are composed mainly of saturated calcium chloride solution. A variety of crystals are to be found on the extensive salt flats surrounding the lake, end a number of those were collected for analysis. One of these proved to be calcium chloride hexahydrate, and this appears to be the first time this substance has been found naturally occurring.
Samples of mud from the salt flats surrounding this lake aid samples from the beds of dried up lakes in the same area were also collected.
Damp Line.
A sinuous band of permanently damp soil was observed contouring the scree slopes about 2,000 feet above Lake Vanda in the Wright Valley. Soil samples were collected across this line and brought to New Zealand for analysis.
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Soil Samples.
Soil samples were collected at intervals along vertical lines up the hillsides above Lakes Bonney and Vanda, in an attempt to correlate the chemical composition of the soil with the position of fossil lake levels above the present level. Although no conclusive results were obtained, it is thought that if more time were available this project may give rewarding results.
Interpretation of Results.
This work is far from complete, but an outline is given below of the information which has been obtained.
A considerable amount of interesting palcoclinatic information can be obtained from the salt concentration gradients of the various [unclear: lakes] studied, if the salt gradients are considered to be formed by diffusion of salt upwards from the bottoms of the lakes into a layer of almost pure water. For example it has been found that the large Eastern hole of Lake Bonney has almost doubled its depth in the last 100 years where a the small western lobe has remained at a practically constant height for at least 5,000 years. this means that a climatic change must have occurred in the area about 100 years ago. This feet is supported by the 100 years ago. Similar information can be obtained from the other lakes but the calculations have not yet been made.
The total age of the lakes can also be established approximately by considering the amount of salt being brought in by inflow [unclear: waters] and balancing this figure against the total amount of salts in the lakes. This information coupled with the above gives a considerable amount of poleogeographic information about the dry valley area.