| Don Juan Pond | |
|---|---|
 Satellite image | |
  Don Juan Pond | |
| Location | East Antarctica |
| Coordinates | 77°33′52″S161°10′20″E / 77.56444°S 161.17222°E /-77.56444; 161.17222 |
| 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 | 30 in (760 mm) |
| Max. depth | 7 ft (2.1 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 is a small and very shallowhypersaline lake in the western end ofWright Valley (South Fork),Victoria Land,Antarctica, 9 kilometres (5.6 mi) west fromLake Vanda. It is wedged between theAsgard Range to the south and the Dais Range to the north. On the west end is a small tributary and arock glacier. With a salinity level of 45.8%, Don Juan Pond is the saltiest of the Antarctic lakes.[1][2] This salinity causes significantfreezing-point depression, allowing the pond to remain liquid even at temperatures as low as −50 °C (−58 °F).
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]
Don Juan Pond is a shallow, flat-bottom, hyper-saline pond. It has the second-highest total dissolved solids on record, 1.3 times greatersalinity than theDead 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 agroundwater discharge zone.[3] The area around Don Juan Pond is covered withsodium chloride andcalcium chloride salts that have precipitated as the water evaporated.[4][5]
The area and volume of Don Juan Pond vary over time. According to theUnited 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]
Studies oflifeforms in thehypersaline (and/orbrine) water of Don Juan Pond have found a "sparse microflora of four species of heterotrophic bacteria and a yeast".[7]
