Antarctic ice seals l...( Microbes discovered packed in an ice-se...)

Microbes discovered packed in an ice-sealed, briny lake in Antarctica may help advance techniques to search for signs of life locked in the subterranean ice on Mars, and provide a model for what lakes on Earth may have looked like during severe glacial periods. The findings were reported in the online edition of the Proceedings of the National Academy of Sciences the week of Dec. 16.

A team of researchers led by Peter Doran, assistant professor of earth and environmental sciences at the University of Illinois at Chicago, discovered an unusual and extreme aquatic ecosystem in Lake Vida -- among the largest of many lakes in Antarctica's McMurdo Dry Valleys located about 2,000 miles due south of New Zealand.

The team found a liquid lake of super-concentrated salt water, seven times saltier than normal seawater, locked beneath 19 meters (62 feet) of lake ice -- a record lake ice cover on Earth. The salty water has been isolated from the atmosphere for at least 2,800 years.

Ice core samples taken from above the pool of brine revealed frozen bacteria and algae that came back to life after gradual melting. The scientists believe the chilly brine may harbor life as well.

"Any primary producers potentially living in the brine down deep are not getting sunlight, so they would have to be chemosynthetic, that is, getting energy from the surrounding chemicals instead of sunlight," said Doran. "The microbes frozen in the ice above seem to be life that was living shallow in the lake at some time, then water flowed on top of the thick ice cover and froze."

Carbon-14 dating showed microbes gathered from ice near the brine to be more than 2,800 years old. Doran said the brine is likely to be at least that old, forming as salts settled down into it while thick ice grew outward from the sealed, freeze-resistant salty lake.

Doran and his research team bored holes to take ice samples from Lake Vida back in 1996 after scanning the lake
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Contact: Paul Francuch
francuch@uic.edu
312-996-3457
University of Illinois at Chicago
16-Dec-2002

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