Deep beneath the great Antarctic ice sheet scientists have made an astonishing discovery. They've found one of the largest lakes in the world. Its very existence defies belief.
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The Lost World Of Lake Vostok. Video hosted on Google. Scientists are desperate to get into the lake because its extreme environment may be home to unique flora and fauna, never seen before, and NASA are excited by what it could teach us about extraterrestrial life. But 4 kilometres of ice stand between the lake and the surface, and breaking this seal without contaminating the most pristine body of water on the planet is possibly one of the greatest challenges science faces in the 21st century. Lake Vostok (Russian: восток, "east") is the largest of more than 140 subglacial lakes found under the surface of Earth's southern-most continent — Antarctica. It is located at 77°S 105°E / -77, 105, beneath Russia's Vostok Station, 4,000 meters (13,000 ft) under the surface of the central Antarctic ice sheet. It is 250 km long by 50 km wide at its widest point, thus similar in size to Lake Ontario, and is divided into two deep basins by a ridge. The water over the ridge is about 200 m (650 ft) deep, 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 covers an area of 15,690 km² (6,058 mi²). It has an estimated volume of 5,400 km³ (1,300 cubic miles) and consists of fresh water. The average depth is 344 m. In May 2005 an island was found in the center of the lake. Lake Vostok lies in the heart of the Antarctic continent hidden beneath miles of ice. As big as Lake Ontario in North America, Lake Vostok is one of the world's biggest freshwater lakes. Lake Vostok has been covered by the vast Antarctic ice sheet for up to 25 million years. Click image to enlarge. Credit: Columbia University, Lamont-Doherty Earth Observatory "It's almost as if the lakes are capturing the geothermal energy from the entire basin and releasing it to the ice stream," said lead author Bell, a senior research scientist at the Lamont-Doherty Earth Observatory. "They power the engines that drive ice sheet collapse. The more we learn about the lakes, the more we realize how important they are to ice sheet stability." The team's work also suggests that subglacial lakes play a role in sea-level rise as well as regional and global climate change. "Here we found that meltwater at the base of the ice sheet speeds the flow of Recovery ice to the oceans. In turn, that contributes to higher sea levels worldwide," said Shuman. "Floods have been known to originate from the interior of the ice sheet in the past, possibly from systems like these subglacial lakes. These sudden outbursts of fresh water could potentially interfere with nearby ocean currents that redistribute heat around the globe and could disrupt the Earth's climate system."
Researchers working at Vostok Station produced one of the world's longest ice cores in 1998. A joint Russian, French, and U.S. team drilled and analyzed the core, which is 3,623 metres (11,890 ft) long. Ice samples from cores drilled close to the top of the lake have been analyzed to be as old as 420,000 years, suggesting that the lake has been sealed under the icecap for between 500,000 and more than a million years. Drilling of the core was deliberately halted roughly 100 metres (300 ft) above the suspected boundary where the ice sheet and the liquid waters of the lake are thought to meet to prevent contamination of the lake from the 60 ton column of freon and aviation fuel Russian scientists filled it with to prevent it from 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, evidence has been found, in the form of microbes, to suggest 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.
Glaciers sometimes hide a lake under their thick layers of ice. And some of these lakes fascinate researchers, particularly because they may contain as yet unknown life forms. In the Antarctic, beneath the Vostok research station, such a lake, of gigantic proportions (surface area 14,000 km²), is whetting the appetite of researchers.
Researchers have already made some surprising discoveries even though they have not yet been able to collect samples of liquid water, as drilling has not yet entered the last few metres of ice, in order to preserve this extraordinary lake from accidental external contamination, (for example by bacteria or by chemicals used to prevent closure of the drill holes). Most recently, in the autumn of 2004, an international research team from Russia, France and the USA studied the composition of the last 85 metres of a deep ice core (made up of refrozen ice containing water from the lake), sampled at a level of 130 m above the liquid interface with the lake. Analysis suggests that the biological content of Lake Vostok is very limited, and that its waters are virtually sterilised by dissolved oxygen (at a pressure equivalent to that of a fizzy drink’s can) which accumulated after the ice thawed. In addition, traces of DNA discovered in the refrozen ice would appear to be the genetic signature of thermophilic bacteria. Such bacteria are better adapted to very hot environments, like those near hot undersea springs or volcanic chimneys, rather than to cold environments. Yet another mystery to be solved…
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