Lake Vostok
Encyclopedia
Lake Vostok is the largest of more than 140 subglacial lake
s found under the surface of Antarctica. The overlying ice provides a continuous paleoclimatic record
of 400,000 years, although the lake water itself may have been isolated for 15 to 25 million years. The lake is named after the Vostok, the 900-ton corvette
of Russian Antarctic pioneer Fabian von Bellingshausen
. No water sample has yet been obtained.
Lake Vostok is located beneath Russia's Vostok Station
under the surface of the central East Antarctic Ice Sheet
, which is at 3488 metres (11,444 ft) above mean sea level
. The surface of this fresh water
lake is approx 4000 m (13,123.4 ft) under the surface of the ice, which places it at approx 500 m (1,640.4 ft) below sea level. Measuring 250 km (155.3 mi) long by 50 km (31.1 mi) wide at its widest point, and covering an area of 15690 km² (6,057.9 sq mi), it is similar in area to Lake Ontario
, but with over three times the volume. The average depth is 344 m (1,129 ft). It has an estimated volume of 5400 km³ (1,295.5 cu mi). The lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m (656.2 ft), compared to roughly 400 m (1,312.3 ft) deep in the northern basin and 800 m (2,624.7 ft) deep in the southern.
first proposed the idea of fresh water under Antarctic ice sheet
s at the end of the 19th century. He theorized that the tremendous pressure exerted by the cumulative mass of thousands of vertical meters of ice could increase the temperature at the lowest portions of the ice sheet to the point where the ice would melt. Kropotkin's theory was further developed by Russian glaciologist
I.A Zotikov, who wrote his Ph.D.
thesis on this subject in 1967.
Russian scientist Andrey Kapitsa
(Pyotr Kapitsa
's son) used seismic soundings in the region of Vostok Station
made during the Soviet Antarctic Expedition
in 1959 and 1964 to measure the thickness of the ice sheet. Kapitsa was the first to suggest the existence of subglacial lake in this region and named it Lake Vostok.
When British scientists in Antarctica performed airborne ice-penetrating radar
surveys in the early 1970s, they detected unusual radar readings at the site which suggested the presence of a liquid, freshwater lake below the ice. In 1991, Jeff Ridley, a remote sensing
specialist with the Mullard Space Science Laboratory
at University College London
, directed the ERS-1
satellite to turn its high-frequency array toward the center of the Antarctic ice cap
. The data from ERS-1 confirmed the findings from the 1973 British surveys, but this new data was not published in the Journal of Glaciology until 1993. Space-based radar
revealed that this subglacial body of fresh water was one of the largest lakes in the world—and one of some 140 subglacial lakes in Antarctica. Russian and British scientists delineated the lake in 1996 by integrating a variety of data, including airborne ice-penetrating radar imaging observations and space-based radar altimetry
. It has been confirmed that the lake contains large amounts of liquid water under the more than 3 kilometres (1.9 mi) thick ice cap, promising to be the most unspoiled lake on Earth. The lake has at least 22 cavities of liquid water, averaging 10 kilometres (6.2 mi) each.
In 2005 an island
was found in the central part of the lake. Then, in January 2006, the discovery of two nearby smaller lakes under the ice cap was published; they are named 90 Degrees East
and Sovetskaya
. It is suspected that these Antarctic subglacial lakes may be connected by a network of subterranean river
s. Centre for Polar Observation & Modelling
glaciologists Duncan Wingham
and Martin Siegert published in Nature
in 2006 that many of the subglacial lakes of Antarctica are at least temporarily interconnected. Because of varying water pressure in individual lakes, large subsurface rivers may suddenly form and then force large amounts of water through the solid ice.
, in the early Cretaceous
(about 125 million years ago). About 65 million years ago, Antarctica (then connected to Australia) still had a tropical
to subtropical
climate, complete with marsupial
fauna
and an extensive temperate rainforest.
The Lake Vostok basin is a small (50 km wide) tectonic
feature within the overall setting of a several hundred kilometer wide continental collision
zone between the Gamburtsev Mountain Range
, a subglacial mountain range
and the Dome C
region. The lake water is cradled on a bed of sediments
70 metres (229.7 ft) thick, offering the possibility that they contain a unique record of the climate and life in Antarctica before the ice cap formed.
in the order of one million years. Later research by Robin Bell and Michael Studinger from the Lamont–Doherty Earth Observatory of Columbia University
suggested that the water of the lake is continually freezing and being carried away by the motion of the Antarctic ice sheet
, while being replaced by water melting from other parts of the ice sheet in these high pressure conditions. This resulted in an estimate that the entire volume of the lake is frozen and removed every 13,300 years—its effective mean residence time.
Drilling for sample cores was halted in 1998 at roughly 100 metres (328.1 ft) above the suspected boundary where the ice sheet and the liquid waters of the lake are thought to meet. In November 2010, when the team came up with new, ecologically-safe methods of probing the lake without contamination; the scientists submitted a final environmental evaluation of the project to the Antarctic Treaty System
's environmental protection committee and were given the go-ahead to sample the ancient waters. In January 2011 the head of the Russian Antarctic Expedition, Valery Lukin, announced that his team had only 50 meters of ice left to drill in order to reach the water. The researchers then switched to a new thermal drill head with a "clean" silicone oil
fluid to drill the rest of the way. Instead of drilling all the way into the water, they would stop just above it, when a sensor on the thermal drill detects free water. At that point, the drill will be stopped and extracted from the bore hole, thereby lowering the pressure beneath it and drawing water into the hole and left for quite some time to freeze, creating a plug of frozen ice in the bottom of the hole. Finally, next summer, the team would drill down again to take a sample of that ice and analyze it.
Drilling stopped on 5 February 2011 at a depth of 3720 metres (12,204.7 ft) so that the research team could make it off the ice and onto the last flight before the beginning of the Antarctic winter season. The drilling team left by aircraft on February 6 and will have to wait until the next austral summer begins in December 2011 to try again.
In the Antarctic summer of 2012–13, the Russian team also plans to send an underwater robot into the lake to collect water samples and sediments from the bottom. An environmental assessment of the plan will be submitted at the Antarctic Treaty's consultative meeting in May 2012.
below the normal freezing point
because of high pressure from the weight of the ice above it. Geothermal
heat from the Earth's interior warms the bottom of the lake. The ice sheet itself insulates the lake from cold temperatures on the surface.
Researchers working at Vostok Station produced one of the world's longest ice core
s in 1998. A joint Russian, French, and United States team drilled and analyzed the core, which is 3623 metres (11,886.5 ft) long. Ice samples from cores drilled close to the top of the lake have been assessed to be as old as 420,000 years, suggesting that the lake was sealed under the ice cap 15 million years ago. Drilling of the core was deliberately halted roughly 100 metres (328.1 ft) above the suspected boundary where the ice sheet and the liquid waters of the lake are thought to meet. This was to prevent contamination of the lake from the 60 ton column of freon
and kerosene
Russian scientists filled it with to prevent the borehole from collapsing and freezing over.
From this core, specifically from ice that is thought to have formed from lake water freezing onto the base of the ice sheet, extremophile microbes
were found, suggesting that the lake water supports life. Scientists suggested that the lake could possess a unique habitat for ancient bacteria
with an isolated microbial gene pool
containing characteristics developed perhaps 500,000 years ago.
ic extreme environment, one that is expected to be supersaturated
with nitrogen and oxygen, measuring 2.5 liters of nitrogen and oxygen per 1 kilograms (2.2 lb) of water, that is 50 times higher than those typically found in ordinary freshwater lakes on Earth. The sheer weight and pressure (350 atmospheres
) of the continental ice cap on top of Lake Vostok is believed to contribute to the high gas concentration.
Besides dissolving in the water, oxygen and other gases are trapped in a type of structure called a clathrate
. In clathrate structures, gases are enclosed in an icy cage and look like packed snow. These structures form at the high-pressure depths of Lake Vostok and would become unstable if brought to the surface.
s. Depending on the position of the Sun and the Moon, the surface of the lake rises about 12 millimeters.
s.
Living Hydrogenophilus thermoluteolus
microorganisms have been found in Lake Vostok's deep ice core drillings; they are an extant surface dwelling species. This suggests the presence of a deep biosphere
utilizing a geothermal system of the bedrock encircling the subglacial lake. There is optimism that microbial life in the lake may be possible despite high pressure, constant cold, low nutrient input, potentially high oxygen concentration and an absence of sunlight.
Due to the lake's similarity to Jupiter
's moon Europa
and Saturn
's moon Enceladus
, any confirmation of life living in Lake Vostok is thought to strengthen the prospect for the possible presence of life on Europa or Enceladus.
and scientists who argued that hot-water drilling would do less environmental damage
. The Russians however complained that hot-water drilling required more power than they could generate at their remote camp. Scientists of the United States National Research Council
have taken the position that it should be assumed that microbial life exists in Lake Vostok and that after such a long isolation, any life forms in the lake require strict protection from contamination. Sediments on its floor should give clues to its long-term climate, and isotope
s in its water are expected to help geologists
determine how and when subglacial lakes such as Lake Vostok form. However, meticulously documented decontamination procedures will be required to establish the credibility of the scientific data obtained.
The drilling technique employed thus far by the Russians has involved the use of freon and kerosene to lubricate the borehole and prevent it from collapsing and freezing over; 60 tons of these chemicals have been used thus far on the ice above Lake Vostok. Other countries, particularly the United States and Britain, have failed to persuade the Russians not to pierce to the lake until cleaner technologies such as hot-water drilling are available. Though the Russians claim to have improved their operations, they continue to use the same borehole, which has already been filled with kerosene. According to the head of Russian Antarctic Expeditions, Valery Lukin, the new equipment had been developed by researchers at the St. Petersburg Nuclear Physics Institute that would ensure the lake remains uncontaminated upon intrusion. Lukin has repeatedly reassured other signatory nations to the Antarctic Treaty System that the drilling will not affect the lake. He argues that on breakthrough, water will rush up the borehole, freeze, and seal the chemical fluids out.
The international scientific community however remains unconvinced by these arguments. The Antarctic and Southern Ocean Coalition argues that this is a profoundly misguided step, which endangers not only Lake Vostok itself, but could harm other subglacial lakes in Antarctica, which some scientists are convinced are inter-linked with Lake Vostok. This coalition asserts that "it would be far preferable to join with other countries to penetrate a smaller and more isolated lake, before re-examining whether penetration of Lake Vostok is environmentally defensible. If we are wise, the Lake
will be allowed to reveal its secrets in due course."
Subglacial lake
A subglacial lake is a lake under a glacier, typically an ice cap or ice sheet. There are many such lakes, with Lake Vostok in Antarctica being by far the largest known at present.-Characteristics:...
s found under the surface of Antarctica. The overlying ice provides a continuous paleoclimatic record
Paleoclimatology
Paleoclimatology is the study of changes in climate taken on the scale of the entire history of Earth. It uses a variety of proxy methods from the Earth and life sciences to obtain data previously preserved within rocks, sediments, ice sheets, tree rings, corals, shells and microfossils; it then...
of 400,000 years, although the lake water itself may have been isolated for 15 to 25 million years. The lake is named after the Vostok, the 900-ton corvette
Corvette
A corvette is a small, maneuverable, lightly armed warship, originally smaller than a frigate and larger than a coastal patrol craft or fast attack craft , although many recent designs resemble frigates in size and role...
of Russian Antarctic pioneer Fabian von Bellingshausen
Fabian Gottlieb von Bellingshausen
Fabian Gottlieb Thaddeus von Bellingshausen was an officer in the Imperial Russian Navy, cartographer and explorer, who ultimately rose to the rank of Admiral...
. No water sample has yet been obtained.
Lake Vostok is located beneath Russia's Vostok Station
Vostok Station
Vostok Station was a Russian Antarctic research station. It was at the southern Pole of Cold, with the lowest reliably measured natural temperature on Earth of −89.2 °C . Research includes ice core drilling and magnetometry...
under the surface of the central East Antarctic Ice Sheet
East Antarctic Ice Sheet
The East Antarctic Ice Sheet is one of two large ice sheets in Antarctica, and the largest on the entire planet. The EAIS lies between 45° West and 168° East longitudinally....
, which is at 3488 metres (11,444 ft) above mean sea level
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
. The surface of this fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
lake is approx 4000 m (13,123.4 ft) under the surface of the ice, which places it at approx 500 m (1,640.4 ft) below sea level. Measuring 250 km (155.3 mi) long by 50 km (31.1 mi) wide at its widest point, and covering an area of 15690 km² (6,057.9 sq mi), it is similar in area to Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
, but with over three times the volume. The average depth is 344 m (1,129 ft). It has an estimated volume of 5400 km³ (1,295.5 cu mi). The lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m (656.2 ft), compared to roughly 400 m (1,312.3 ft) deep in the northern basin and 800 m (2,624.7 ft) deep in the southern.
Discovery
Russian scientist Peter KropotkinPeter Kropotkin
Prince Pyotr Alexeyevich Kropotkin was a Russian zoologist, evolutionary theorist, philosopher, economist, geographer, author and one of the world's foremost anarcho-communists. Kropotkin advocated a communist society free from central government and based on voluntary associations between...
first proposed the idea of fresh water under Antarctic ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
s at the end of the 19th century. He theorized that the tremendous pressure exerted by the cumulative mass of thousands of vertical meters of ice could increase the temperature at the lowest portions of the ice sheet to the point where the ice would melt. Kropotkin's theory was further developed by Russian glaciologist
Glaciology
Glaciology Glaciology Glaciology (from Middle French dialect (Franco-Provençal): glace, "ice"; or Latin: glacies, "frost, ice"; and Greek: λόγος, logos, "speech" lit...
I.A Zotikov, who wrote his Ph.D.
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
thesis on this subject in 1967.
Russian scientist Andrey Kapitsa
Andrey Kapitsa
Andrey Petrovich Kapitsa was a Russian geographer. His father was Pyotr Kapitsa, and his maternal grandfather was Aleksey Krylov.Kapitsa was born in Cambridge, United Kingdom, and graduated from Moscow State University in 1953. He is credited with the discovery and naming of Lake Vostok, the...
(Pyotr Kapitsa
Pyotr Kapitsa
Pyotr Leonidovich Kapitsa was a prominent Soviet/Russian physicist and Nobel laureate.-Biography:Kapitsa was born in the city of Kronstadt and graduated from the Petrograd Polytechnical Institute in 1918. He worked for over ten years with Ernest Rutherford in the Cavendish Laboratory in Cambridge...
's son) used seismic soundings in the region of Vostok Station
Vostok Station
Vostok Station was a Russian Antarctic research station. It was at the southern Pole of Cold, with the lowest reliably measured natural temperature on Earth of −89.2 °C . Research includes ice core drilling and magnetometry...
made during the Soviet Antarctic Expedition
Soviet Antarctic Expedition
The Soviet Antarctic Expedition was part of the Arctic and Antarctic Research Institute of the Soviet Committee on Antarctic Research of the Academy of Sciences of the USSR....
in 1959 and 1964 to measure the thickness of the ice sheet. Kapitsa was the first to suggest the existence of subglacial lake in this region and named it Lake Vostok.
When British scientists in Antarctica performed airborne ice-penetrating radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
surveys in the early 1970s, they detected unusual radar readings at the site which suggested the presence of a liquid, freshwater lake below the ice. In 1991, Jeff Ridley, a remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
specialist with the Mullard Space Science Laboratory
Mullard Space Science Laboratory
The UCL Mullard Space Science Laboratory is the United Kingdom's largest university space research group. MSSL is the Department of Space and Climate Physics of the University College London. UCL was one of the first universities in the world to conduct space research...
at University College London
University College London
University College London is a public research university located in London, United Kingdom and the oldest and largest constituent college of the federal University of London...
, directed the ERS-1
European Remote-Sensing Satellite
European remote sensing satellite was the European Space Agency's first Earth-observing satellite. It was launched on July 17, 1991 into a Sun-synchronous polar orbit at a height of 782–785 km.-Instruments:...
satellite to turn its high-frequency array toward the center of the Antarctic ice cap
Ice cap
An ice cap is an ice mass that covers less than 50 000 km² of land area . Masses of ice covering more than 50 000 km² are termed an ice sheet....
. The data from ERS-1 confirmed the findings from the 1973 British surveys, but this new data was not published in the Journal of Glaciology until 1993. Space-based radar
Space-Based Radar
Space-based radar refers to space-borne radar systems that may have any of a variety of purposes. A number of earth-observing radar satellites, such as RadarSat, have employed synthetic aperture radar to obtain terrain and land-cover information about the Earth.Space-Based Radar is a proposed...
revealed that this subglacial body of fresh water was one of the largest lakes in the world—and one of some 140 subglacial lakes in Antarctica. Russian and British scientists delineated the lake in 1996 by integrating a variety of data, including airborne ice-penetrating radar imaging observations and space-based radar altimetry
Altimeter
An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.-Pressure altimeter:...
. It has been confirmed that the lake contains large amounts of liquid water under the more than 3 kilometres (1.9 mi) thick ice cap, promising to be the most unspoiled lake on Earth. The lake has at least 22 cavities of liquid water, averaging 10 kilometres (6.2 mi) each.
In 2005 an island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
was found in the central part of the lake. Then, in January 2006, the discovery of two nearby smaller lakes under the ice cap was published; they are named 90 Degrees East
90 Degrees East
90 Degrees East, also known as 90°E Lake, is a lake in Antarctica. With a surface area of about , it is the second-largest known subglacial lake in Antarctica....
and Sovetskaya
Sovetskaya (lake)
Sovetskaya Lake is a liquid lake found buried under the Antarctic ice sheet, below Sovetskaya Research Station. It covers about .-See also:* Lake Vostok * 90 Degrees East* Sovetskaya...
. It is suspected that these Antarctic subglacial lakes may be connected by a network of subterranean river
Subterranean river
A subterranean river is a river that runs wholly or partly beneath the ground surface – one where the riverbed does not represent the surface of the Earth ....
s. Centre for Polar Observation & Modelling
Centre for Polar Observation & Modelling
The Centre for Polar Observation & Modelling is a centre for research into polar region processes which may affect: polar atmosphere and ocean circulation; the Earth's albedo; and global sea levels...
glaciologists Duncan Wingham
Duncan Wingham
Duncan Wingham is Professor of Climate Physics at University College London, and was the first Director of the Centre for Polar Observation & Modelling. He is a member of the NERC Science and Technology Board and is Principal Scientist for the CryoSat Satellite Mission.In the 90s, Wingham was...
and Martin Siegert published in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
in 2006 that many of the subglacial lakes of Antarctica are at least temporarily interconnected. Because of varying water pressure in individual lakes, large subsurface rivers may suddenly form and then force large amounts of water through the solid ice.
Geological history
Africa separated from Antarctica around 160 million years ago, followed by the Indian subcontinentIndian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
, in the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
(about 125 million years ago). About 65 million years ago, Antarctica (then connected to Australia) still had a tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
to subtropical
Subtropics
The subtropics are the geographical and climatical zone of the Earth immediately north and south of the tropical zone, which is bounded by the Tropic of Cancer and the Tropic of Capricorn, at latitudes 23.5°N and 23.5°S...
climate, complete with marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
and an extensive temperate rainforest.
The Lake Vostok basin is a small (50 km wide) tectonic
Tectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
feature within the overall setting of a several hundred kilometer wide continental collision
Continental collision
Continental collision is a phenomenon of the plate tectonics of Earth that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together...
zone between the Gamburtsev Mountain Range
Gamburtsev Mountain Range
The Gamburtsev Mountain Range is a subglacial mountain range located in Eastern Antarctica, near Dome A. The range was discovered by the 3rd Soviet Antarctic Expedition in 1958 and is named for Soviet geophysicist Grigoriy A. Gamburtsev...
, a subglacial mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
and the Dome C
Dome C
Dome C, also known as Dome Circe or Dome Charlie, located at Antarctica at an altitude of 3,233 m or 10,607 ft above sea level, is one of several summits or "domes" of the Antarctic Ice Sheet...
region. The lake water is cradled on a bed of sediments
Glaciolacustrine deposits
Sediments deposited into lakes that have come from glaciers are called glaciolacustrine deposits. These lakes include ice margin lakes or other types formed from glacial erosion or deposition. Sediments in the bedload and suspended load are carried into lakes and deposited...
70 metres (229.7 ft) thick, offering the possibility that they contain a unique record of the climate and life in Antarctica before the ice cap formed.
Research
The lake water is believed to have been sealed off under the thick ice sheet about 15 million years ago. Initially, it was thought that the same water had made up the lake since the time of its formation, giving a residence timeResidence time
Residence time is the average amount of time that a particle spends in a particular system. This measurement varies directly with the amount of substance that is present in the system....
in the order of one million years. Later research by Robin Bell and Michael Studinger from the Lamont–Doherty Earth Observatory of Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
suggested that the water of the lake is continually freezing and being carried away by the motion of the Antarctic ice sheet
Antarctic ice sheet
The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square km and contains 30 million cubic km of ice...
, while being replaced by water melting from other parts of the ice sheet in these high pressure conditions. This resulted in an estimate that the entire volume of the lake is frozen and removed every 13,300 years—its effective mean residence time.
Drilling for sample cores was halted in 1998 at roughly 100 metres (328.1 ft) above the suspected boundary where the ice sheet and the liquid waters of the lake are thought to meet. In November 2010, when the team came up with new, ecologically-safe methods of probing the lake without contamination; the scientists submitted a final environmental evaluation of the project to the Antarctic Treaty System
Antarctic Treaty System
The Antarctic Treaty and related agreements, collectively called the Antarctic Treaty System or ATS, regulate international relations with respect to Antarctica, Earth's only continent without a native human population. For the purposes of the treaty system, Antarctica is defined as all of the land...
's environmental protection committee and were given the go-ahead to sample the ancient waters. In January 2011 the head of the Russian Antarctic Expedition, Valery Lukin, announced that his team had only 50 meters of ice left to drill in order to reach the water. The researchers then switched to a new thermal drill head with a "clean" silicone oil
Silicone oil
A silicone oil is any polymerized siloxanes with organic side chains. They are formed of alternating silicon-oxygen atoms or siloxane, rather than carbon atoms . Other species attach to the tetravalent silicon atoms, not to the divalent oxygen atoms which are fully committed to forming the...
fluid to drill the rest of the way. Instead of drilling all the way into the water, they would stop just above it, when a sensor on the thermal drill detects free water. At that point, the drill will be stopped and extracted from the bore hole, thereby lowering the pressure beneath it and drawing water into the hole and left for quite some time to freeze, creating a plug of frozen ice in the bottom of the hole. Finally, next summer, the team would drill down again to take a sample of that ice and analyze it.
Drilling stopped on 5 February 2011 at a depth of 3720 metres (12,204.7 ft) so that the research team could make it off the ice and onto the last flight before the beginning of the Antarctic winter season. The drilling team left by aircraft on February 6 and will have to wait until the next austral summer begins in December 2011 to try again.
In the Antarctic summer of 2012–13, the Russian team also plans to send an underwater robot into the lake to collect water samples and sediments from the bottom. An environmental assessment of the plan will be submitted at the Antarctic Treaty's consultative meeting in May 2012.
Temperature
It was at Vostok Station that the coldest temperature ever observed on Earth (-89 °C) was recorded on 21 July 1983. The average water temperature is calculated to be around -3 °C; it remains liquidSupercooling
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid....
below the normal freezing point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
because of high pressure from the weight of the ice above it. Geothermal
Geothermal gradient
Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior. Away from tectonic plate boundaries, it is 25–30°C per km of depth in most of the world. Strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied...
heat from the Earth's interior warms the bottom of the lake. The ice sheet itself insulates the lake from cold temperatures on the surface.
Ice core
Ice core
An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental build up of annual layers of snow, lower layers are older than upper, and an ice...
s in 1998. A joint Russian, French, and United States team drilled and analyzed the core, which is 3623 metres (11,886.5 ft) long. Ice samples from cores drilled close to the top of the lake have been assessed to be as old as 420,000 years, suggesting that the lake was sealed under the ice cap 15 million years ago. Drilling of the core was deliberately halted roughly 100 metres (328.1 ft) above the suspected boundary where the ice sheet and the liquid waters of the lake are thought to meet. This was to prevent contamination of the lake from the 60 ton column of freon
Chlorofluorocarbon
A chlorofluorocarbon is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane. A common subclass are the hydrochlorofluorocarbons , which contain hydrogen, as well. They are also commonly known by the DuPont trade name Freon...
and kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
Russian scientists filled it with to prevent the borehole from collapsing and freezing over.
From this core, specifically from ice that is thought to have formed from lake water freezing onto the base of the ice sheet, extremophile microbes
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
were found, suggesting that the lake water supports life. Scientists suggested that the lake could possess a unique habitat for ancient bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
with an isolated microbial gene pool
Gene pool
In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...
containing characteristics developed perhaps 500,000 years ago.
Oxygen
Lake Vostok is an oligotrophOligotroph
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments...
ic extreme environment, one that is expected to be supersaturated
Supersaturation
The term supersaturation refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances...
with nitrogen and oxygen, measuring 2.5 liters of nitrogen and oxygen per 1 kilograms (2.2 lb) of water, that is 50 times higher than those typically found in ordinary freshwater lakes on Earth. The sheer weight and pressure (350 atmospheres
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
) of the continental ice cap on top of Lake Vostok is believed to contribute to the high gas concentration.
Besides dissolving in the water, oxygen and other gases are trapped in a type of structure called a clathrate
Clathrate hydrate
Clathrate hydrates are crystalline water-based solids physically resembling ice, in which small non-polar molecules or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded water molecules...
. In clathrate structures, gases are enclosed in an icy cage and look like packed snow. These structures form at the high-pressure depths of Lake Vostok and would become unstable if brought to the surface.
Tidal forces
In April 2005, German, Russian, and Japanese researchers found that the lake has tideTide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s. Depending on the position of the Sun and the Moon, the surface of the lake rises about 12 millimeters.
Life
The lake is under complete darkness and expected to be rich in oxygen, so there is speculation that any organisms inhabiting the lake could have evolved in a manner unique to this environment. These adaptations to an oxygen-rich environment might include high concentrations of protective oxidative enzymeOxidative enzyme
An oxidative enzyme is an enzyme that catalyses oxidation reaction. Two most common types of oxidative enzymes are peroxidases, which use hydrogen peroxide, and oxidases, which use molecular oxygen.They increase the rate at which ATP is produced aerobically....
s.
Living Hydrogenophilus thermoluteolus
Hydrogenophilaceae
The Hydrogenophilaceae are a family of Betaproteobacteria, with two genera. Like all Proteobacteria they are Gram-negative. Hydrogenophilus are thermophilic, growing around 50 °C and obtaining their energy from oxidizing hydrogen. It includes the genera Hydrogenophilus and Thiobacillus...
microorganisms have been found in Lake Vostok's deep ice core drillings; they are an extant surface dwelling species. This suggests the presence of a deep biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...
utilizing a geothermal system of the bedrock encircling the subglacial lake. There is optimism that microbial life in the lake may be possible despite high pressure, constant cold, low nutrient input, potentially high oxygen concentration and an absence of sunlight.
Due to the lake's similarity to Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
's moon Europa
Europa (moon)
Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...
and Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
's moon Enceladus
Enceladus (moon)
Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel. Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface...
, any confirmation of life living in Lake Vostok is thought to strengthen the prospect for the possible presence of life on Europa or Enceladus.
Controversy
The drilling project was opposed by some environmental groupsEnvironmental movement
The environmental movement, a term that includes the conservation and green politics, is a diverse scientific, social, and political movement for addressing environmental issues....
and scientists who argued that hot-water drilling would do less environmental damage
Environmental degradation
Environmental degradation is the deterioration of the environment through depletion of resources such as air, water and soil; the destruction of ecosystems and the extinction of wildlife...
. The Russians however complained that hot-water drilling required more power than they could generate at their remote camp. Scientists of the United States National Research Council
United States National Research Council
The National Research Council of the USA is the working arm of the United States National Academies, carrying out most of the studies done in their names.The National Academies include:* National Academy of Sciences...
have taken the position that it should be assumed that microbial life exists in Lake Vostok and that after such a long isolation, any life forms in the lake require strict protection from contamination. Sediments on its floor should give clues to its long-term climate, and isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s in its water are expected to help geologists
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
determine how and when subglacial lakes such as Lake Vostok form. However, meticulously documented decontamination procedures will be required to establish the credibility of the scientific data obtained.
The drilling technique employed thus far by the Russians has involved the use of freon and kerosene to lubricate the borehole and prevent it from collapsing and freezing over; 60 tons of these chemicals have been used thus far on the ice above Lake Vostok. Other countries, particularly the United States and Britain, have failed to persuade the Russians not to pierce to the lake until cleaner technologies such as hot-water drilling are available. Though the Russians claim to have improved their operations, they continue to use the same borehole, which has already been filled with kerosene. According to the head of Russian Antarctic Expeditions, Valery Lukin, the new equipment had been developed by researchers at the St. Petersburg Nuclear Physics Institute that would ensure the lake remains uncontaminated upon intrusion. Lukin has repeatedly reassured other signatory nations to the Antarctic Treaty System that the drilling will not affect the lake. He argues that on breakthrough, water will rush up the borehole, freeze, and seal the chemical fluids out.
The international scientific community however remains unconvinced by these arguments. The Antarctic and Southern Ocean Coalition argues that this is a profoundly misguided step, which endangers not only Lake Vostok itself, but could harm other subglacial lakes in Antarctica, which some scientists are convinced are inter-linked with Lake Vostok. This coalition asserts that "it would be far preferable to join with other countries to penetrate a smaller and more isolated lake, before re-examining whether penetration of Lake Vostok is environmentally defensible. If we are wise, the Lake
will be allowed to reveal its secrets in due course."
See also
Lakes of Antarctica- List of Antarctic expeditions
- List of lakes by volume
- History of AntarcticaHistory of AntarcticaThe history of Antarctica emerges from early Western theories of a vast continent, known as Terra Australis, believed to exist in the far south of the globe...
- Ledoyom (Ice body)