Covering a total area of about 10,000 sq km, Lake Vostok in Antarctica is one of the largest sub-glacial lakes in the world. Lake Vostok in Antarctica is buried under greater than about 3.7 km of ice and is located near the Vostok research station run by Russia.
Lake Vostok in Antarctica was once a large surface lake in eastern Antarctica that is now covered by a layer of ice about 3.7 km deep. Covered by a layer of ice for a millennia, Lake Vostok in Antarctica provides one of Earth’s most extreme environments for any life-form living beneath the ice layer.
Brent Christner, a biologist, estimates that the ice cover over the lake has persisted for at least 15 million years after examining ice cores collected above the lake (B. Oskin, 2015). The palaeo-climatic records as per the ice cover over the lake have revealed a history of about 4,00,000 years, and the water in the lake below a depth of 4,000 m is estimated to have remained isolated for between 15 to 25 million years.
Fig: An estimation of the geomorphological structure of Lake Vostok
Source: Antarctic and Southern Ocean Coalition
Recent Scientific Activities Over Lake Vostok in Antarctica
Gerhard Kuhn with an international research team published a story in the journal Nature Communications on June 1st 2017 after they sampled the sediment layers left behind by sub-glacial lakes in the last glacial period in Antarctica when the ice was much thicker and extended much further offshore. The space beneath the Antarctic ice sheet is a repository for numerous sub-glacial lakes with lake Vostok being the largest. As extractions from Lake Vostok in Antarctica are bound by strict environmental restrictions to avoid exposure to the outside environment, till date the only samples collected by scientists are sourced from the water that had come out of the borehole dug into the ice above the lake.
A team of researchers from the Alfred Wegener Institute (AWI) led by the marine biologist Gerhard Kuhn tested the water for its chloride content – a salinity test for freshwater, which confirmed that the water in Lake Vostok comprise freshwater. This test confirms that the water is not oceanic in origin and indeed represents an inland fresh water body.
This and other studies on unique sediments and their deposits from other former and present sub-glacial lakes in Antarctica according to Kuhn offer insights into the changing environmental conditions in Antarctica between present times to the last period of a glacial maximum in Antarctica 21,000 years ago with sea levels 130 m lower than they are presently.
Using satellites, the team found that water moving from one lake to another due to glaciers that act to drain Antarctic ice can cause glaciers to move at a more rapid rate, accelerating the rate of Antarctic ice joining the ocean (AWI, 2017).
The air near Russia’s Vostok research station has reported a temperature of minus 89oC, which is among the coldest temperatures recorded on Earth. Scientists therefore were understandably skeptical about the prospects of finding life beneath the ice in lake Vostok in Antarctica. In March 2013 however, scientists confirmed that the water extracted from Lake Vostok in Antarctica contained a Vostok-dwelling bacterium (G. Templeton, 2013).
The bacterium was of a species previously uncharacterized although it can be characterized as an extremophile, a category of organisms that have been discovered in many obscure habitats all across the world. Lake Vostok in Antarctica offers highly pressurized conditions although the exact geological habitat in the lake remains a mystery.
Difficulties in Studying Lake Vostok in Antarctica
The confirmed existence of lake Vostok in Antarctica was confirmed only in 1993, although the supposition for a sub-glacial lake in the location was present since the 1950s. This became possible due to J.P. Ripley’s ERS-1 Laser Alimetry study, following which efforts have been made to study the mysterious sub-glacial lake.
The first bafflement with the Lake is the possibility of finding liquid water at so cold a location, which scientists usually attribute to geothermal heat near the layer of ice contributing towards melting the ice. An effort to drill the overlaying layer of ice was made by American, French and Russian scientists in 1989, but was halted 130 m from the surface of the lake to avoid contamination from the antifreeze and the kerosene used as a lubricant.
In the 1990s an international team discovered microbes in frozen lake water above the surface of the principal lake water in the form of accretion ice. This was present in the frozen top of the lake’s water. On analysis of the microbes it was found that their unique characteristics could suggest a unique ecosystem in isolation for millions of years.
The microbes found revealed on analysis that they could possibly derive energy from minerals in the lake and from the surrounding rocks. However, completely pristine samples of water from the Lake have not as yet been recovered with evidence of life existing in the water of lake Vostok in Antarctica (B. Oskin, 2015). The Russians have made attempts at reaching the water’s surface but their results are suspect as the samples were contaminated with fluid used to facilitate the drilling process (C. Brahic, 2015).