Lake Vostok
The Lake Vostok is the largest of more than 370 previously known subglacial lakes under the ice sheet of Antarctica . The freshwater lake lies at a depth of 3700 to 4100 meters under the ice and extends from the eponymous Russian Vostok station almost 250 kilometers to the north, is 50 kilometers wide and has a water depth of up to 1200 meters.
discovery
Andrei Kapiza , a scientist at the Vostok station, developed the thesis about the existence of a lake under the station in the late 1950s , but was unable to prove it. It was not until Christmas 1974 that this thesis could be confirmed by a Scottish team who noticed a particularly flat area during the radar-based investigation of the glacier surface . The existence of the lake was unequivocally confirmed in 1996 by a Russian - British team by combining various data, including airborne radar measurements that reached deep into the ice, space-based radar height measurements and analysis of generated seismic waves.
geography
Due to its location deep under the ice, it is probably the most pristine and pristine lake on earth. The fact that it has not frozen through despite its average temperature of −3 ° C is due to the high pressure of around 35 to 40 megapascals under the ice cover, which drops the freezing point of water to −2.7 ° C to −3.1 ° C leaves.
| location | 77 ° 0 ′ S , 105 ° 0 ′ E |
| length | 250 km |
| width | 40-50 km |
| surface | 15,690 km² |
| Depth (under the ice) | 3700-4100 m |
| Depth (of the water basin) | 400-1000 m |
| Middle deep | 344 m |
| volume | 5,400 km³ |
| temperature | −3 ° C |
The age of the ice was estimated to be 420,000 years.
The glacier above the lake moves at low speed and brings sediments into the lake. On the “outflowing side” of the glacier, the water of the lake freezes. This leads to a height difference of more than 400 meters on the two sides of the lake. The bottom of the lake is also not level, but rather “ islands ” rise above the surface of the lake into the ice.
The Vostoksee offers an extreme habitat. He lies in complete darkness. In addition to the extremely low temperature of its water, its oxygen content is extremely high, namely around 50 times higher than in normal fresh water. The reason for this is, on the one hand, the high pressure of 355 bar and , on the other hand, the occurrence of clathrates in which the gaseous oxygen is embedded in an ice structure.
Nevertheless, as analyzes of DNA and RNA sequences show, Lake Vostok seems to be home to an astonishing diversity of species. Investigations of ice samples from 3563 to 3621 meters depth, which originate from accretion ice formed from seawater, revealed the genetic material of thousands of different organisms, 94 percent of which belonged to bacteria and 6 percent to eukaryotes , mostly from fungi . Only two sequences are from archaea . Since DNA from parasites was also found, the existence of higher, multicellular animals such as worms, sea anemones, crustaceans and even fish cannot be ruled out.
Tidal forces in Lake Vostok
In April 2005, German, Russian and Japanese researchers examined the effects of tidal forces on the lake. Depending on the position of the sun and moon , the tidal range there is between 1 and 2 centimeters. The research team suspects that the tidal forces create currents necessary for the survival of microorganisms.
Research history
In 1957, Soviet researchers built the Vostok station to research the earth's climate history . In 1983, the lowest outside temperature ever recorded on earth was registered there at -89.2 ° C.
In 1990 a joint project to extract an ice core for climate research was started at the Vostok research station with Russian , French and US participation. As it turned out later, the borehole is located exactly above Lake Vostok. The drilling was carried out to a depth of 3,623 meters and was not stopped until January 1998 due to an international agreement about 130 meters above the lake in order to avoid contamination of the lake. One reason was that kerosene and freon were used to keep the well open. When analyzing the drill cores, it turned out that the last 60 meters before the stop no longer consist of glacier ice, but of accreted ice (frozen water of Lake Vostok). Most of the findings about Lake Vostok so far come from this borehole.
Should the lake be contaminated by the introduction of bacteria during the exploration of the lake, the results obtained would be almost worthless and the evaluation of later research missions would be made much more difficult, if any useful knowledge could still be obtained.
Drilling of the Arctic and Antarctic Research Institute
Despite the scientific concerns, the Arctic and Antarctic Research Institute announced in early January 2011 in Saint Petersburg that it would drill holes in the lake and take samples. The method used is intended to rule out contamination. For this purpose, the mechanical drill head is replaced by a thermal one 20 to 30 meters above the surface, which then melts down to the lake. When the surface is reached, the drill head should be pushed back into the borehole by the pressurized water and the water in the borehole should freeze. In a follow-up drilling, samples are taken from this frozen seawater.
On February 5, 2011, the drilling had to be temporarily interrupted shortly before reaching the lake due to the onset of the Antarctic winter. The following summer, in January 2012, the Russian team continued drilling. On February 6, 2012, they reached the surface of Lake Vostok under a 3768 meter thick ice sheet. The seawater flowed into the borehole and froze in it. A few months later, core samples were taken from this frozen lake water. These samples were shipped to Russia for analysis. Results from this were expected in late 2013 or early 2014.
Further projects and studies
Other investigations took place in parallel. In October 2012, analyzes of water samples showed no evidence of life. However, it has not been ruled out that there is life in deeper water layers.
On March 7, 2013, Russian scientists announced that they had found a new, unknown species of bacteria in the samples from the lake. However, this turned out to be wrong.
Samples of accretion ice (not directly from the lake) were taken and analyzed in the 1990s by a US team led by Scott O. Rogers. In July 2013, Rogers announced the above-mentioned results of the nucleic acid analysis of these samples, which indirectly indicate diverse life in Lake Vostok.
See also
literature
- Igor A. Zotikov: The Antarctic Subglacial Lake Vostok. Glaciology, Biology, Planetology. Springer, Berlin / Heidelberg / New York 2006, ISBN 3-540-42649-3 (English).
- Andreas Richter: Lake Vostok - A geoscientific portrait of an Antarctic subglacial lake . In: Polar Research . Volume 88, No. 2, 2018, pp. 65-88, doi: 10.2312 / polarforschung.88.2.65 .
Web links
- Vostok Ice Core Data , NOAA National Climatic Data Center
- News about the formation of Lake Vostok under the ice of the Antarctic
- Thermophilic bacteria in Lake Vostok ( Memento from February 13, 2012 in the Internet Archive )
- TV station Arte - The enchanted world of Lake Vostok ( Memento from January 19, 2009 in the Internet Archive )
- BBC - The Lost World of Lake Vostok, 2000, directed by Jonathan Renouf (English)
- Die Schläfer , radio play about the drilling in Lake Vostok
Individual evidence
- ↑ Bethan Davies: Subglacial Lakes . On: antarcticglaciers.org from February 22, 2014 (last update).
- ^ A. Wright, M. Siegert: A fourth inventory of Antarctic subglacial lakes. In: Antarctic Science. No. 24, 2012, pp. 659-664.
- ^ MJ Siegert, S. Carter, I. Tabacco, S. Popov, DD Blankenship: A revised inventory of Antarctic subglacial lakes. In: Antarctic Science. Volume 17, No. 03, 2005, pp. 453-460.
- ↑ The enchanted world of Lake Vostok. ( Memento from January 19, 2009 in the Internet Archive ), TV documentary, broadcast on Arte , July 31, 2008, 8:15 p.m.
- ↑ Old lake under deep ice - the Antarctic Vostok Sea is opened up. on Spektrumdirekt from January 28, 2011.
- ↑ phase diagram of water , (engl.)
- ↑ YM Shtarkman, ZA Koçer, R. Edgar, RS Veerapaneni, T. D'Elia et al .: Subglacial Lake Vostok (Antarctica) Accretion Ice Contains a Diverse Set of Sequences from Aquatic, Marine and Sediment-Inhabiting Bacteria and Eukarya. In: PLOS ONE . 8 (7), 2013, p. E67221. doi: 10.1371 / journal.pone.0067221
- ^ Vostok Ice Core. National Oceanic and Atmospheric Administration (NOAA) - National Climat Data Center
- ↑ NI Vasiliev et al: Twenty years of drilling the deepest hole in ice. In: Scientific Drilling. No. 11, 2011, pp. 41–45, doi: 10.2204 / iodp.sd.11.05.2011 .
- ^ Russian team prepares to penetrate Lake Vostok. ( Memento of January 7, 2011 in the Internet Archive ) In: wired.co.uk
- ↑ news.sciencemag.org: With 30 Meters Left to Drill, Scientists Leave Subterranean Lake Vostok For The Winter, Amid Controversy. ( Memento of the original from February 14, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Russians drill into previously untouched Lake Vostok below Antarctic glacier. In: The Washington Post.
- ↑ Russia taps the Vostok Sea. In: Tagesanzeiger.
- ↑ Eurasiareview: 'Intrigue' Persists In Hunt For Antarctic Subglacial Life ( Memento of March 3, 2013 in the Internet Archive )
- ↑ Nature: Vostok's microbes elusive in first measurements of surface water
- ↑ Phys.org: Russia finds 'new bacteria' in Antarctic lake
- ↑ Antarctic Sea: Bacteria find turns out to be dirt. In: Spiegel online.
- ^ Antarctica's hidden Lake Vostok found to teem with life. In: TBC News.
