Subglacial lake

A subglacial lake is a lake under a glacier. In contrast to a frozen lake just a subglacial lake is under a typically hundreds or thousands of meters thick, permanent ice. It can be used as ecosystem contain simple life forms such as bacteria.

A large number of subglacial lakes exist in Antarctica. By far the largest known subglacial lake in the world is the Lake Vostok. He has more than 112 times the volume of Lake Constance and is almost 30 times as large as this in the area.

Characteristics

For the existence of subglacial lakes, two phenomena are responsible. Firstly, the melting point of water ice decreases under pressure. Among a many hundreds or thousands of meters thick layer of ice, the pressure increases with increasing depth such that the melting point of ice - it is also called the pressure melting point - several degrees Celsius below 0 ° C decreases. At the same time, the temperature increases in depth by geothermal energy. If the temperature is higher than the melting point at a certain depth, the ice liquefied water.

Examples

Under the Antarctic ice sheet more than 150 subglacial lakes have been found by eisdurchdringendem radar and satellite images so far. The largest and most famous of the Lake Vostok, is about 250 km long, 50 km wide, has a depth of up to 1200 m and is in total darkness at depths 3700-4100 meters below the ice. He has a temperature of about -3 ° C and at a pressure of about 35 MPa ( 350 bar). It is believed that the subglacial lakes of Antarctica are connected by a network of subglacial rivers to each other and a pressure equalization and water transport takes place between them.

In Iceland there are many subglacial, therefore covered by glaciers, volcanoes. With geothermal energy have some of them, such as the Grímsvötn, subglacial lakes. However, these lakes are due to the higher geothermal and volcanic activity often in any stable equilibrium, but melt regularly or irregularly on the glacier and then pour in the form of tidal waves, which are called glacier run.

Importance

If Antarctic subglacial lakes, such as Lake Vostok in fact, as has been suggested, contain microbial life, they are interesting for research as unique ecosystems that have extreme living conditions and are isolated from the rest of the world since hundreds of thousands of years. In their research attention to the risk of contamination is given by using special drilling techniques, for example, and special robotic probes, called Kryobots be developed.

The subglacial lakes are also used for space research is important because they have resemblance to the presumed conditions on celestial bodies such as Jupiter 's moon Europa or Saturn's moon Enceladus, apply their Eismondozeane as potential habitats for extraterrestrial life.