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A prehistoric bacterium is assumed to have been found in Lake Vostok
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Overview -

Lake Vostok (Russian: озеро Восток, lit. "Lake East") is the largest of more than 140 subglacial lakes found under the surface of Antarctica.

 

Lake_Vostok


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.
Lake Vostok is located at the southern Pole of Cold, beneath Russia's Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at 3,488 metres (11,444 ft) above mean sea level.
The surface of this fresh water lake is approximately 4,000 m (13,100 ft) under the surface of the ice, which places it at approximately 500 m (1,600 ft) below sea level. Measuring 250 km (160 mi) long by 50 km (30 mi) wide at its widest point, and covering an area of 15,690 km2 (6,060 sq mi), it is similar in area to Lake Ontario, but with over three times the volume. 

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The average depth is 344 m (1,129 ft). It has an estimated volume of 5,400 km3 (1,300 cu mi).[4] The lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m (700 ft), compared to roughly 400 m (1,300 ft) deep in the northern basin and 800 m (2,600 ft) deep in the southern.


Lake Vostok, which hasn't been touched by light in millions of years, has been a target of scientific exploration because of the unique lifeforms it may contain.

Lake_vostok_antarctica_digging_map


Researchers believe Vostok can give them some fresh insights into the frozen history of Antarctica.

They also hope to find microbial lifeforms that are new to science.
The drilling project has been opposed by some environmental groups and scientists who have argued that hot-water drilling would do less environmental damage.[46] The Russians explained 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 isotopes in its water are expected to help geologists determine how and when subglacial lakes such as Lake Vostok form. Meticulously documented decontamination procedures will be required to establish the credibility of the scientific data obtained.

 

lake_vostok_ice_core


The original drilling technique employed by the Russians 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, new equipment was 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, arguing that on breakthrough, water will rush up the borehole, freeze, and seal the chemical fluids out.
Despite the excitement surrounding the Russians' accomplishment, the project is not without environmental fears. The Washington Post explained that concerns exist that Lake Vostok "could be contaminated by the kerosene, Freon and other materials being used in the drilling."

The Russian Antarctic program's director, Valery Lukin, told that their data may be processed as soon as Wednesday. He said, "We want to be sure we have really reached the surface of Lake Vostok."




Interesting facts
It was at Vostok Station that the coldest temperature ever observed on Earth, -89 °C (-128 °F), was recorded on 21 July 1983. The average water temperature is calculated to be around -3 °C (27 °F); it remains liquid below the normal freezing point because of high pressure from the weight of the ice above it.
Geothermal heat from the Earth's interior may warm the bottom of the lake.The ice sheet itself insulates the lake from cold temperatures on the surface.
Lake Vostok is an oligotrophic extreme environment, one that is expected to be supersaturated with nitrogen and oxygen, measuring 2.5 liters of nitrogen and oxygen per 1 kilogram (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.


Ria Novosti, the Russian news agency reported that near the end of the World War II, the Nazis moved to the South Pole and began constructing a base at Lake Vostok.


lake_vostok_cartografie

On 5 February 2012, after twenty years of drilling, a team of Russian scientists claimed to have completed the longest ever ice core of 3,768 m (12,400 ft) and pierced the ice shield to the surface of the lake




Coordinates     77°30'S 106°00'ECoordinates: 77°30'S 106°00'E
Lake type     subglacial rift lake
Basin countries     - Antarctica
Max. length     250 km (160 mi)
Max. width     50 km (30 mi)
Surface area     15,690 km (9,750 mi)
Average depth     344 m (1,129 ft)
Max. depth     ~1,000 m (3,300 ft)[citation needed]
Water volume     5,400 km3 (1,300 cu mi) ± 1,600 km3 (400 cu mi)
Residence time     13,300 yrs



Lake_Vostok


Recently the russian scientists came back in St.Petersburg after another 190 expedition t Antarctica claiming that they have found an unknown speacies of bacteria.
Just days after Russian scientists announced that they had found a previously unidentified species of bacteria in Antarctica's subglacial Lake Vostok, the discovery has been called into question.
On 7 March, the St. Petersburg Nuclear Physics Institute's Sergei Bulat, who led the Russian team that drilled through 4 kilometers of ice to the surface of the lake last year, told Russian news agency RIA Novosti that they had found a previously unidentified species of bacteria in lake samples collected during an expedition in January.
That they had found life at all was exciting and a reversal of the team's earlier stance from a decade ago that Vostok might be barren.
But on 9 March, the head of the genetics laboratory at the St. Petersburg Institute, Vladimir Korolyov, told Interfax that what the team had found was only contamination. "We found certain specimen, although not many, but all of them belonged to contaminants (microorganisms from the bore-hole kerosene, human bodies or the lab)," he said.
"There was one strain of bacteria which we did not find in drilling liquid, but the bacteria could in principal use kerosene as an energy source. That is why we can't say that a previously-unknown bacteria was found."
Korolyov said that they would need to wait for pure water samples to determine what, if any, life might exist in Vostok—samples that the team hopes to have within the next year. "For now we'd rather not say something we will be unable to whitewash even with the crystal clear Vostok water."

 

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Sergey Bulat of the Petersburg Nuclear Physics Institute in Gatchina said that water from Lake Vostok contained a bacterium whose DNA was less than 86% similar to DNA from known bacterial species. But other researchers argue that announcement was premature because the bacterium might just have been a contaminant from the drilling fluid.
The scientists have not yet established the mysterious microbe’s physiology and biochemistry, and they do not know how it might extract energy from its pitch-dark and nutrient-poor environment. More sophisticated tests, including whole-genome sequencing, will be required to answer these and other questions, says Bulat.
However, he says, the high level of contamination — the current samples contain as much drill fluid as lake water — and the meagre numbers of bacteria, just 167 cells per millilitre, mean that these analyses cannot yet be done.
He hopes that samples from a 54-metre-long ‘fresh-frozen’ ice core drilled during the 2012–13 season and expected to arrive in St Petersburg in May will reveal more about the genetics of microbial life in Lake Vostok, he says.
Other researchers say that they would be surprised if Lake Vostok is totally devoid of life. The US team has already reported the presence of microbes in water and sediment samples retrieved from Lake Whillans. Those samples are currently being analysed in US labs.
But many point out that about 90% of the bacteria on Earth remain uncultured and unsequenced, so finding bacterial DNA that doesn’t fully match that of well-classified taxa is not very surprising.
“It happens quite a lot,” says Brent Christner, a microbiologist at Louisiana State University in Baton Rouge and one of the researchers analysing the Lake Whillans samples.















Sources - text and pics:

http://earthsci.org/education/Lake_Vostok/
http://www.huffingtonpost.com/2012/02/06/lake-vostok-antarctica-russians-penetrated_n_1258440.html
http://www.visualphotos.com
http://www.americanpolar.org
http://www.huffingtonpost.com/2013/03/11/lake-vostok-life-discovery_n_2854270.html
http://www.nature.com/news/russian-scientist-defends-lake-vostok-life-claims-1.12578


US National Science Foundation
Author
Zina Deretsky / NSF

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