Blood Falls
- 77.716666666667162.26666666667Koordinaten: 77 ° 43 '0 "S, 162 ° 16' 0" E
Blood Falls ( also blood diarrhea or blood flow) is the name of an effluent enriched with iron oxide salt water banner from the tongue of the Taylor Glacier on the ice-covered surface of the Western Bonneysees in Taylor Valley, one of the Antarctic Dry Valleys in Victoria Land, Antarctica, flowing.
Ferrous hyper Dessalines water occurs sporadically by small cracks in the ice cascade. The source of the brine is a subglacial lake of unknown size overlain by about 400 meters of ice, several kilometers away from the small outlet at the blood cases.
The reddish deposit was in 1911 by the Australian geologist Griffith Taylor, a participant of the Terra Nova expedition found. He explored the first to the valley that bears his name. The first pioneers of Antarctica attributed the red color of red algae. However, it was later proven that they are iron oxides.
Geochemistry
It is sparingly soluble hydrous iron oxides (Fe2O3 ), which are deposited on the surface of the ice after the iron ions are oxidized on contact with the atmosphere (oxygen ) in the thawed salt water. Old sea water that is trapped in a subglacial bag, dissolves iron ions from the rock. It dates from the Antarctic Ocean, as a fjord at the end of the Miocene ( about 5 million years ago), when sea level was higher than today, was isolated from the glacier.
Unlike most glaciers of Antarctica to the Taylor glacier is not frozen to the bottom, probably remain in solution during freezing of the trapped beneath ancient sea water due to the presence of salts. The salt cryo - concentration of the remaining ( relict ) seawater is because pure ice crystallized, the dissolved salts displaced and the remaining liquid cooled because of the heat exchange with the enormous masses of ice of the glacier. As a result, the trapped water was concentrated to a brine having a salt content by two to three times of the sea water.
Hypersaline fluids that penetrated through a crack in the ice and were sampled at random, were free of oxygen and rich in iron (II ) sulfate. Sulfate is a residual geochemical signature of marine conditions, was likely to be released during soluble divalent iron under reducing conditions by microbial activity from the minerals of the subglacial foundation.
Microbial ecosystem
The chemical and microbial analyzes indicate that has a rare subglacial ecosystem by autotrophic bacteria develops, the sulphate and iron ions metabolized. After Jill Mikucki, Geomikrobiologin at Dartmouth College, the water samples of blood cases contain at least 17 different types of microbes, and almost no oxygen. One explanation could be that the microbial sulfate breathe as a catalyst with ferric ions and metabolize the microscopic amounts of organic matter that is trapped with them down there. Such a metabolic process that had never previously been observed in nature.
A puzzling observation is the coexistence of Fe2 and SO42 - ions under anoxic conditions. Have been found, in fact, no hydrogen sulfide anion (HS- ) in the system. This suggests that a complex and poorly understood interaction between the biochemical sulfur and iron cycle exists.
Impact on the " Snowball Earth " hypothesis
After Mikucki et al. (2009), who is now inaccessible, subglacial lake was cordoned million years ago, 1.5 to 2 and transformed into a sort of "time capsule ". This isolated the microbial populations for a sufficiently long time independent of others to develop similar marine organisms. It could explain how other microorganisms had previously able to survive when, after the Snowball Earth hypothesis, all the earth may have been frozen.
In fact, ice-covered seas might have been the only refuge for microbial ecosystems, as the Earth during the Proterozoic ( about 650 aeon ago - 750 million years ) may have been down to tropical latitudes covered by glaciers.
Implications for astrobiology
This unusual place offers scientists a unique opportunity to study the tiefenmikrobielle life under extreme conditions - without having to drill deep into the polar ice cap, coupled with the risk of contamination of the fragile and still-intact ecosystem.
The study of harsh environments on Earth is useful to understand the breadth of conditions to which life can adapt; and to provide an estimate of the possibility of life must be made in other parts of the solar system - in places such as Mars or Europa, an icy moon of Jupiter. Scientists at the Astrobiology Institute at the NASA speculate that these worlds could harbor subglacial liquid water. This would create favorable conditions for elementary forms of life that would be better protected in the depth from UV and cosmic radiation than at the surface.