Posted by: maboulette | March 17, 2017

Largest Subglacial Lake in the World


vostok-station

Deep, dark and mysterious, Lake Vostok is one of the largest subglacial lakes in the world.  I wrote about this lake several years ago so I thought I might check back in on the research.

ONCE SURFACE LIKE

Once a large surface lake in East Antarctica, Lake Vostok is now buried under more than 2 miles (3.7 kilometers) of ice near Russia’s Vostok research station. Covered with ice for millennia, cut off from light and contact with the atmosphere, Lake Vostok is one of the most extreme environments on Earth. “The lake has been ice-covered for at least 15 million years,” said Brent Christner, a Louisiana State University biologist who has examined ice cores collected above the lake.

vostok station1

INTERNATIONAL TEAM

In the 1990s, Christner was part of an international team that discovered microbes in frozen lake water collected above Lake Vostok’s liquid surface, called ‘accretion ice’. The top half-inch (1 centimeter) of the lake surface freezes onto the flowing ice sheet above the lake, scientists believe.

LIFE FORMS

Analysis of the life forms suggests Lake Vostok may harbor a unique ecosystem based on chemicals in rocks instead of sunlight, living in isolation for hundreds of thousands of years. “The types of organisms we found suggested they derived their energy from minerals present in the lake and sources from the underlying bedrock,” Christner said. More recent studies of genetic material in Vostok’s accretion ice revealed snippets of DNA from a wide variety of organisms related to single-celled creatures found in lakes, oceans and streams. These “extremophiles” could mimic life on other moons and planets, such as Jupiter’s icy moon Europa. [Image Gallery: Alien Life of the Antarctic]

NO TEAMS RETRIEVED WATER

Despite several attempts, no teams have successfully regained pristine samples of lake water with evidence of life. A Russian team is currently analyzing water samples collected in 2012 for signs of microbial life. In 2013, scientists exploring Antarctica’s subglacial Lake Whillans reported the presence of microbial life in water retrieved from a buried lake. There are nearly 380 subglacial lakes in Antarctica.

Vostok map

LAKE VOSTOK

Lake Vostok is one of the largest lakes on Earth in size and volume, rivaling Lake Ontario in North America. Its only water supply is meltwater from overlying ice sheet, Christner said. “To my knowledge, there is no evidence for influx or efflux of water from Lake Vostok,” he said. This constant replenishment from melting ice means the water in the lake may be relatively young, just thousands of years old, according to ice core studies. But the true age of the lake water is unknown.

MAPPED

Researchers have mapped Lake Vostok’s shape with remote sensing techniques, such as seismic soundings and ice-penetrating radar. Lake Vostok is much shallower on one end than the other, with the two basins separated by a ridge. Some scientists think the ridge could be a hydrothermal vent, similar to the ocean floor black smokers that teem with tubeworms. The long, narrow lake may lie in a rift valley, similar to Lake Baikal in Russia.

GEOTHERMAL HEAT

Geothermal heat from the Earth keeps the temperature of the lake water hovering around 27 degrees Fahrenheit (minus 3 degrees Celsius), scientists believe. The weighty pressure of the overlying ice keeps the lake liquid despite its below-freezing temperature.

The lake itself is 143 miles (230 km) long, 31 miles (50 km) wide and as much as 2,625 feet (800 meters) deep. Lake Vostok sits near the South Pole in East Antarctica. The presence of a large buried lake was first suggested in the 1960s by a Russian geographer/pilot who noticed the large, smooth patch of ice above the lake from the air. Airborne radar experiments by British and Russian researchers in 1996 confirmed the discovery of the unusual lake.

SUBGLACIAL LAKES

“Lake Vostok is one of the easiest subglacial lakes to detect due to its size,” Christner said. “[Yet] I believe most of its secrets remain.”

 

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