Lake Vostok

Lake Vostok
When photographed from space by radar, Lake Vostok can be seen as a flat area inside the ice sheet. (NASA GSFC)
Coordinates	77°0′S 105°0′E
Type	subglacial rift lake
Basin countries	(Antarctica)
Max. length	250 km
Max. width	50 km
Surface area	15,690 km²
Average depth	344 m
Max. depth	1,000 m
Water volume	5,400 ± 1,600 km³
Residence time	1,000,000 yrs
Islands	1 (found May 2005)
Settlements	Vostok Station

Lake Vostok is the biggest of the seventy lakes in Antarctica that are under sheets of ice. It is at 77° S 105° E. It is under Russia's Vostok Station. It is 4,000 meters (13,000 feet) under Antarctica's surface.

The lake was found by Russian and British scientists. They used radar to find it.

The lake consists of fresh water. The temperature of the water is about -3 °C. The freezing point of water is at 0 °C, but the water in the lake remains liquid because of the high pressure produced by the ice.

There are two separate basins in the lake. These are separated by a ridge. It has been suggested that the ecosystems of the two basins are different.

Pressure and oxygen

Lake Vostok is an oligotrophic extreme environment. It is supersaturated with oxygen. The levels of oxygen are fifty times higher than those typically found in ordinary freshwater lakes on Earth. The weight of the ice on top of Lake Vostok is believed to add to the high concentration of oxygen. Oxygen from the ice gets dissolved into the water of the lake. Deposits of oxygen and other gases are trapped in the lake as well. The structure that traps them is called a clathrate. Gases trapped in clathrates are enclosed in ice and look like packed snow. These structures form at the high-pressure depths of Lake Vostok; they would become unstable if brought to the surface.

Life

No other natural environment on Earth is as rich in oxygen. For this reason, if there are any forms of life in the lake, they would probably need to have adapted to the high levels of oxygen to be able to survive. Some adaptations might include high concentrations of protective enzymes.

The environment in the lake is very similar to that on Jupiter's moon Europa or Saturn's moon Enceladus. Finding life in the lake would therefore make it more probable that life has existed on one of these moons.

Other websites

• "Miles Below Antarctic Ice, a Freshwater Lake May Harbor Ancient Life." Robert Lee Hotz, The Los Angeles Times.