Don Juan Pond

Don Juan Pond in Fig. 19.22 is located at 77°34 S and 161°lLEina topographic basin in the South Fork of Wright Valley about 8 km southwest of Lake Vanda. The pond is about 315 m long, 116 m wide, and less than 

10 cm deep. It is surrounded by a salt flat and is sitnated about 200 m east of an active rock glacier (Harris and Cartwright 1982). Strand lines indicate that the water level in Don Juan Pond was up to 21 m higher in the past than it is at present time (Mndrey et al. 1973, 1975). An evocative photograph of Don Jnan Pond was pnblished by Porter (1978, p. 101). 

Don Jnan Pond was discovered on October 11 of 1961 by a gronp of scientists during a reconnaissance of the ice-free valleys by helicopter. At the time it was discovered, the brine in the pond was not frozen in spite of the fact that the air temperature was -24°C (Meyer et al. 1962). When Japanese scientists visited Don Juan Pond in 1963, the water level and size of the pond had declined markedly (Yamagata et al. 1967). The pond is replenished by two small and intermittent meltwater streams that enter it from the west. 

The density of the water in Don Juan Pond is exceptionally high. Meyer et al. (1962) reported a value of 1.2514 g/mL, whereas Yamagata et al. (1967) obtained 1.351 and 1.380 g/mL. Jones (1969) later determined a value of 1.2744 g/mL at 20°C in one sample of brine collected by D.D. Koob during the summer of 1964/65. The shallow depth of the brine (about 10 cm), the lack of an ice cover, and steady wind all prevent the brine from becoming stratified (Harris et al. 1979). 

The temperature of the brine in Don Juan Pond varies seasonally depending on the air temperature. The freezing point of the brine ranges from -48°C (Meyer et al. 1962) to -57°C (Tedrow et al. 1963) which means that the brine in Don Juan Pond may not freeze even during the Antarctic winter, although BuU (1966) did record a minimum temperature of -62°C at Lake Vida in Victoria Valley. 

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With the suggestion that the last common genetic ancestor is a hyperthermophile, the role of temperature on the origins of life is important. The lower temperature limit in water is limited by the phase transition from liquid to ice. This is a problem because the density of ice is lower than that of water and the increase in volume on freezing will cause the cell structure to become disrupted in the same way that pipes burst in the winter. The lower limit for bacterial growth reported so far is -20°C, which is the temperature at which intracellular ice is formed. Adaptation to the cold requires a considerable salt content to depress the melting point of water the Don Juan Pond in Antarctica, which has a saturated CaCE solution, preserves the liquid phase at temperatures as low as —53°C. 

One of the great virtues of the FREZCHEM model is its ability to examine complex chemistries. The number of independent components for the systems examined in this chapter range from four to eight. Earth seawater consisting of Na+, K+, Mg2+, Ca2+, Cl-, SO4-, and alkalinity has seven independent components (six salts and water). The most complex system evaluated is the snowball Earth seawater (eight independent components), which in addition to the above seven components also includes Fe2+. This ability to cope with complexity makes models like FREZCHEM more realistic in describing natural systems than simpler binary and ternary diagrams we demonstrate this point with data from Don Juan Pond, the most saline body of water on Earth. 

Property Seawaterb Seawater at -20°C Orca Basin, Gulf of Mexico0 Great Salt Lake, USAd Dead Sea, Israel Don Juan Pond, Antarctica1 Basque Lake, Canadad Mono Lake, USAd Lake Magadi, Kenya ... 

Fig. 5.5. A stability diagram for ice and antarcticite in a pure CaCD solution and in Don Juan Pond. Reprinted from Marion (1997) with permission...

Marion CM (1997) A theoretical evaluation of mineral stability in Don Juan Pond, Wright Valley, Victoria Land. Antarctic Sci 9 92-99... 

The principal lakes of southern Victoria Land that attract attention by their size and by the salinities and chemical compositions of the brines they contain are Lake Vida in Victoria Valley (Calkin and Bull 1967), Lake Vanda and Don Juan Pond in Wright Valley, Lake Bonney, Lake Hoare, and Lake Fryxell in Taylor Valley, and Lake Miers in the ice-free valleys along the Koettlitz Glacier (Matsubaya et al. 1979 Matsumoto et al. 1993 Lyons and Finlay 2008). 

The chenucal analyses of the brine in Don Juan Pond in Appendix 19.9.3 demonstrate that the concentrations of and Na in samples collected over a span of 4 years from October 1961 to January 1965 vary widely. Nevertheless, all analyses indicate that the salts dissolved in the brine consists of CaClj (93.0 5.4%), NaCl (4.82 5.42%), MgCl, (2.09 0.44%), and KCl (0.09 0.01%) expressed relative to the sum of the total dissolved soUds (Mndrey et al. 1973,1975). 

Stable only in very dry environments such as exist in the vicinity of Don Juan Pond and in Death Valley, California (Torii et al. 1986). 

The Sr/ Sr ratio of the brine in Don Juan Pond measured by Jones (1969) was confirmed by Friedman et al. (1995) who reported values of 0.7185 for brine collected on January 10, 1975 0.7186 for crystals of antarcticites collected in November of 1973 and 0.7187 for interstitial brine from sediment at a depth of 10.8 m. They also reported that the average Sr/ Sr ratio of glacial meltwater that is discharged into Don Juan Pond is 0.7163 0.0009 and that the average strontium concentration of the meltwater is only 0.086 0.011 ppm. Evidently, the strontium in the meltwater that flows into Don Juan Pond is derived by chemical weathering of silicate minerals in the soil west of the pond and marine strontium is not detectable in the water of the tributary streams. The hterature containing information relevant to the study of Don Juan Pond is listed in Appendix 19.9.4. 

Chemical Analyses of Brine in Don Juan Pond of Wright Valley, Southern Victoria Land (Compiled by Jones 1969)... 

Friedman I, Rafter A, Smith GI (1995) A thermeil, isotopic, and chemical study of Lake Vanda and Don Juan Pond, Antarctica. In Elliot DH, Blaisdell GL (eds) Contributions to Antarctic Research IV. Antarctic Research Series, vol. 67—. American Geophysical Union, Washington, DC, pp 177-194 Friedmemn El (1977) Microorganisms in Antarctic desert rocks from dry vrilleys and Dufek Massif. Antarctic J US 12(4) 26-29... 

Mudrey MG, Shimp NF, Keighin CW, Oberts GL, McGinnis LD (1973) Chemical evolution of water in Don Juan Pond, Antarctica. Antarctic J US 8(4) 164-166... 

Mudrey MG, Torii T, Harris H (1975) Geology of DVDP No. 13, Don Juan Pond, Wright Valley, Antarctica. DVDP 5 78-99... 

The only strong-CaCl2, low-MgCl2 lakes in the world are the very small Don Juan Pond, Antarctica and Bristol Lake. Cadiz Lake (adjacent to Bristol Lake) has a somewhat more dilute, higher magnesium brine. Bristol and Cadiz Lakes are relatively small late (Quaternary dry playas in the Bristol-Danby Trough of the... 

Wright Valley, Antarctica the Lake Vanda data are at 70 m depth also < 0.045 ppm I the Don Juan Pond is late in the summer evaporation period (Goguel and Webster, 1990 Webster and Goguel, 1988). 

One of the most unusual of the world s calcium chloride lakes is Lake Vanda and the nearby Don Juan Pond in Antarctica. The lake is covered with ice, there is nearly fresh water under the ice, and below that a stratified strong calcium chloride... 

Figure 2.24 Location map of Lake Vanda, the Don Juan Pond and Lake Bonney in the Dry Valley Area of Southern Victoria Land, Antarctica (Matsubaya et al, 1979 reprinted from Geochimica et Cosmochimica Acta, vol. 43, 1979, with permission from Elsevier).

Analyses of the Brines of Lake Vanda and the Don Juan Pond, Antarctica (g/kg) (Matsubaya et al., 1979 data from January 1973)... 

Analyses below the line are of groundwater under the Lake (11-1973) or Pond (12-1973), except the first line in Don Juan Pond represents a continuous series of dates. 

The Don Juan Pond (Figs. 2.26 and 2.27) is a very small basin in the same valley and up slope from Lake Vanda, containing such a concentrated calcium chloride brine that it remains at least partly unfrozen all year, even at — 50°C temperatures. During the 1975-1976 season the pond varied in size from 178 X 595 (59,500 m ) to 121 X 406 (40,500 area 7780-3080... 

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