Frigid lakes not the “life labs” they were thought to be?
and World Science staff
For years, scientists have been fascinated by the idea that bizarre life forms might dwell in lakes that are locked beneath Antarctic ice, cut off from the outside world. Much soul-searching has surrounded the question of whether researchers should drill deep down explore to the lakes, and risk contaminating their pristine contents.
But a new finding might just render the discussion moot: the lakes may not be cut off from the outside world after all.
Researchers say rivers the size of the Thames, under the ice, may link the lakes to each other and possibly to the oceans, challenging the usual assumption that the lakes evolved in isolation for millions of years and thus may contain microbes that evolved “independently.”
Scientists had suggested that if the lakes house microbes, they could function in the same way as those in the subsurface ocean of Jupiter’s moon Europa or water pockets on Mars.
“It was thought water moves underneath the ice by very slow seepage. But this new data shows that, every so often, the lakes beneath the ice pop off like champagne corks, releasing floods that travel very long distances,” saud Duncan Wingham of University College London, who led the new research.
“A major concern has been that by drilling down to the lakes new microbes would be introduced. Our data shows that any contamination will not be limited to one lake, but will over time extend down the length of the network of rivers. We had thought of these lakes as isolated biological laboratories. Now we are going to have to think again.”
The finding raises the possibility that flood waters from deep inside may sometimes reach the ocean, he added.
Researchers discovered Antarctica’s “subglacial” lakes in the 1960s. Since then over 150 have turned up, though it’s thought thousands may exist. The largest is Lake Vostok, containing an estimated 5,400 cubic kilometres of water—equivalent to London’s water consumption over five millennia.
Wingham’s team used radars on the European Space Agency’s ERS-2 satellite to examine small changes in some of the oldest, thickest ice. They found synchronous changes in the surface height hundreds of kilometers apart, and said the only explanation is a large water flow from one lake into several others.
“The lakes are like a set of beads on a string, where the lakes are the beads connected by a string or river of water,” Wingham said.
“For the most part, there is very little flow along the string. Then, one of the lakes over-pressurizes and a flood occurs that fills the next ‘bead’ down the string…. Once it starts to flow, it melts the ice, and there is a run-away effect.”
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