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(fwd) FWD [forteana] Stinkbomb apocalypse



On Tue, 04 Nov 2003 17:21:29 -0700, "Terry W. Colvin" <fortean1@mindspring.com>
wrote:

< http://education.guardian.co.uk/higher/sciences/story/0,12243,1077287,00.html
>

Foul gas may have killed 95% of life

Tim Radford, science editor
Tuesday November 4, 2003
The Guardian

The biggest-ever mass extinction of life on Earth may have been accompanied
by the smell of rotten eggs or decomposing cabbage, geologists said
yesterday.

At the end of the Permian era, 251 million years ago, 95% of all life went
extinct - and the killer might have been foul-smelling hydrogen sulphide.

Life has been wiped out on a massive scale at least five times in geological
history. The biggest, the Permian mass extinction, opened an evolutionary
doorway for the age of the dinosaurs, which also ended in a mass extinction
65 million years ago, probably by collision with an asteroid.

"The end-Permian is puzzling," Professor Lee Kump of Penn State University
told the Geological Society of America, meeting in Seattle. "There is no
smoking gun, no compelling evidence of asteroid impact."

The deep oceans of the Permian were anoxic, that is, they carried no
dissolved oxygen. If sea levels rose, then many creatures would have died. A
second theory was that for some reason, surface and deep water mixed,
bringing anoxic water to the surface. The decomposition of creatures in the
deep ocean could have caused a carbon dioxide crisis; the gas is lethal in
high concentrations to many animals. However, "plants, in general, love
carbon dioxide, so it is difficult to think of carbon dioxide as a good kill
mechanism," Prof Kump said.

But hydrogen sulphide gas could have been the great exterminator. Humans can
smell the gas at concentrations in parts per million million. At the bottom
of the Black Sea today there are concentrations at 34 parts per million: a
toxic brew for any oxygen-consuming creature. The poisonous soup of the
Black Sea is locked away under a layer of relatively clean water.

Prof Kump added that 251 million years ago, as levels of oxygen in the
atmosphere fell, the levels of hydrogen sulphide and carbon dioxide in the
oceans would have begun to poison sea and air.

He is looking for evidence in the form of photosynthetic sulphur bacteria in
the end-Permian rocks.


-- 
?Only a zit on the wart on the heinie of progress.? Copyright 1992, Frank Rice


Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1@mindspring.com >
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