Don Juan Pond is a small and very shallow hypersaline lake in the western end of Wright Valley (South Fork), Victoria Land, Antarctica, 9 kilometres (5.6 mi) west from Lake Vanda. It is wedged between the Asgard Range to the south and the Dais Range to the north. On the west end is a small tributary and a rock glacier. With a salinity level of 33.8%, Don Juan Pond is the saltiest of the Antarctic lakes.[1][2] This salinity causes significant freezing-point depression, allowing the pond to remain liquid even at temperatures as low as −50 °C (−58 °F).
| Don Juan Pond | |
|---|---|
 Satellite image | |
  Don Juan Pond | |
| Location | East Antarctica |
| Coordinates | 77°33′52″S 161°10′20″E / 77.56444°S 161.17222°E |
| Type | Hypersaline lake |
| Basin countries | (Antarctica) |
| Max. length | 300 m (980 ft) |
| Max. width | 100 m (330 ft) |
| Surface area | 0.03 km2 (0.012 sq mi) |
| Average depth | 16 in (410 mm) |
| Max. depth | 3 ft (0.91 m) |
| Water volume | 3,000 m3 (110,000 cu ft) |
| Surface elevation | 116 m (381 ft) |
| Frozen | No |
| Islands | 0 |
| Settlements | Vanda Station (14 km to the east) |
Don Juan Pond was discovered in 1961. It was named for two helicopter pilots, Lt. Don Roe and Lt. John Hickey, who piloted the helicopter involved with the first field party investigating the pond.[2]
Salinity
editDon Juan Pond is a shallow, flat-bottom, hyper-saline pond. It has the second-highest total dissolved solids on record, 1.3 times greater salinity than the Dead Sea. Salinity varies over time from 200 to 474 g/L, dominated by calcium chloride. It is the only Antarctic hypersaline lake that almost never freezes. It has been described as a groundwater discharge zone.[3] The area around Don Juan Pond is covered with sodium chloride and calcium chloride salts that have precipitated as the water evaporated.[4][5]
The area and volume of Don Juan Pond vary over time. According to the United States Geological Survey topographical map published in 1977, the area was approximately 0.25 km2 (62 acres). However, in recent years the pond has shrunk considerably. The maximum depth in 1993–1994 was described as "a foot deep" (30 cm). In January 1997, it was approximately 10 centimetres (3.9 in) deep;[3] in December 1998, the pond was almost dry everywhere except for an area of a few tens of square metres. Most of the remaining water was in depressions around large boulders in the pond.[6]
Life
editStudies of lifeforms in the hypersaline (and/or brine) water of Don Juan Pond have found a "sparse microflora of four species of heterotrophic bacteria and a yeast".[7]
Literature
edit- Yamagata, N.; T. Torii, S. Murata. "Report of the Japanese summer parties in Dry Valleys, Victoria Land, 1963–65; V – Chemical composition of lake waters". Antarctic Record. 29: 53–75.
References
edit- ^ Hammer, U.T. (1986). Saline Lake Ecosystems of the World. Springer. p. 109. ISBN 9789061935353. Retrieved 27 March 2018.
- ^ a b Vanjo, Grobljar. "Don Juan Pond and Lake Vanda". pbase.com. Retrieved April 7, 2017.
- ^ a b Salty Antarctic pond could be a replica of Mars' water. Astrobiology Magazine. 23 November 2017.
- ^ Hammer, U.T. (1986). Saline Lake Ecosystems of the World. Springer. p. 109. ISBN 9789061935353. Retrieved 27 March 2018.
- ^ Oren, Aharon (2007). "Salts and Brines". In Whitton, Brian A.; Potts, Malcolm (eds.). The Ecology of Cyanobacteria: Their Diversity in Time and Space. Springer. p. 287. ISBN 9780306468551. Retrieved 27 March 2018.
- ^ "Lake Levels". McMurdo Dry Valleys Long-Term Ecological Research. Archived from the original (csv) on 4 July 2018. Retrieved 28 March 2018.
- ^ Siegel, B.Z.; McMurty, G.; Siegel, S.M.; Chen, J.; Larock, P. (30 August 1979). "Life in the calcium chloride environment of Don Juan Pond, Antarctica". Nature. 280 (5725): 828–829. Bibcode:1979Natur.280..828S. doi:10.1038/280828a0. S2CID 27550775.
