Don Juan Pond is a small and very shallow

hypersaline lake A hypersaline lake is a landlocked body of water that contains significant concentrations of sodium chloride, brines, and other salts, with saline levels surpassing that of ocean water (3.5%, i.e. ). Specific microbial species can thrive in ...

in the western end of

Wright Valley The Wright Valley, named for Sir Charles Wright, is the central one of the three large Dry Valleys in the Transantarctic Mountains, located west of McMurdo Sound at approximately . Wright Valley contains the Onyx River, the longest river in ...

(South Fork),

Victoria Land Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. I ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

, west from

Lake Vanda Lake Vanda is a lake in Wright Valley, Victoria Land, Ross Dependency, Antarctica. The lake is long and has a maximum depth of . On its shore, New Zealand maintained Vanda Station from 1968 to 1995. Lake Vanda is a hypersaline lake with a salin ...

. It is wedged between the

Asgard Range The Asgard Range is a mountain range in Victoria Land, Antarctica. It divides Wright Valley from Taylor Glacier and Taylor Valley, and was named by the Victoria University of Wellington Antarctic Expedition (1958–59) after Asgard, the home o ...

to the south and the Dais Range to the north. On the west end is a small tributary and a

rock glacier Rock glaciers are distinctive geomorphological landforms, consisting either of angular rock debris frozen in interstitial ice, former "true" glaciers overlain by a layer of talus, or something in-between. Rock glaciers are normally found at high ...

. With a salinity level of 33.8%, Don Juan Pond is the saltiest of the Antarctic lakes. This salinity causes significant

freezing-point depression Freezing-point depression is a drop in the minimum temperature at which a substance freezes, caused when a smaller amount of another, non- volatile substance is added. Examples include adding salt into water (used in ice cream makers and for ...

, allowing the pond to remain liquid even at temperatures as low as . Don Juan Pond was discovered in 1961 by George H. Meyer. 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. Don Juan Pond, McMurdo Dry Valleys, Antarctica

Don Juan Pond, McMurdo Dry Valleys, Antarctica

Salinity

Don 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 Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

than the

Dead Sea The Dead Sea ( he, יַם הַמֶּלַח, ''Yam hamMelaḥ''; ar, اَلْبَحْرُ الْمَيْتُ, ''Āl-Baḥrū l-Maytū''), also known by other names, is a salt lake bordered by Jordan to the east and Israel and the West Ban ...

. 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 Groundwater discharge is the volumetric flow rate of groundwater through an aquifer. Total groundwater discharge, as reported through a specified area, is similarly expressed as: :Q = \fracKA where :''Q'' is the total groundwater discharge ( 3· ...

zone.Salty Antarctic pond could be a replica of Mars' water
''Astrobiology Magazine''. 23 November 2017. The area around Don Juan Pond is covered with

sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35. ...

and

calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide. Ca ...

salts that have precipitated as the water evaporated. The area and volume of Don Juan Pond vary over time. According to the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

topographical map published in 1977, the area was approximately . However, in recent years the pond has shrunk considerably. The maximum depth in 1993–1994 was described as "a foot deep" (). In January 1997, it was approximately deep; 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.

Life

Studies of

lifeforms Life form (also spelled life-form or lifeform) is an entity that is living, such as plants (flora) and animals (fauna). It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billion species, are ex ...

in the

hypersaline A hypersaline lake is a landlocked body of water that contains significant concentrations of sodium chloride, brines, and other salts, with saline levels surpassing that of ocean water (3.5%, i.e. ). Specific microbial species can thrive in hi ...

(and/or

brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for ...

) water of Don Juan Pond have been ambiguous.

Literature

References

External links

Great Zoom into Don Juan Pond, Antarctica
* {{gnis, 3975, type=antarid
Don Juan Pond GigaPan picture
Lakes of Victoria Land Saline lakes of Antarctica Endorheic lakes of Antarctica McMurdo Dry Valleys