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Blood Falls: Life beneath a rusty glacier
At Blood Falls, on the East Antarctic Ice Sheet, rivers of red, iron-rich minerals spill out from the snout of the Taylor Glacier, dramatically staining the white ice.
Scientists now report that the pools of water beneath the ice, which feed Blood Falls, are home to microbes that have lived there for millions of years. This discovery shows how a microbial system can survive for very long periods of time without photosynthesis or nutrients from outside their environment.
Jill A. Mikucki of Harvard University and colleagues report that the water contains ancient seawater which was trapped some 1.5 to 4 million years ago under the advancing glacier. The water has virtually no oxygen and is loaded with salt and iron.
The water also contains sulphate, a common energy source for microbes that can't carry out photosynthesis because they live in environments without oxygen and sunlight.
By analyzing the chemistry of the water and some of the microbes' genetic information, the scientists figured out that the microbes are getting their energy from a series of chemical reactions involving both iron and sulfur.
In their study, which appears in the 17 April issue of the journal Science, the researchers propose that microbial systems similar to this one might have existed during so-called "snowball Earth" episodes when the planet may have been covered in ice.