o for the early Earth.
The Great Oxidation Event
Earth's early atmosphere contained hardly any oxygen but relatively large amounts of carbon dioxide and possibly methane, experts believe. Then during the so-called Great Oxidation Event about 2.3 to 2.5 billion years ago, oxygen levels in the atmosphere rose from vanishingly small amounts to modestly low concentrations.
"This important transition enabled a widespread diversification and proliferation of metabolic strategies and paved the way for a much later climb in oxygen to levels that were high enough to support animal life," Colman says.
The processing of carbon monoxide by the microbial community could have influenced atmospheric chemistry and climate during the Archean, an interval of Earth's history that preceded the Great Oxidation Event.
Previous computer simulations rely on a primitive biosphere as the sole means of removing near-surface carbon monoxide produced when the sun's ultraviolet rays split carbon dioxide molecules. This theoretical sink in the biosphere would have prevented substantial accumulation of atmospheric carbon monoxide.
"But our work is showing that you can't consider microbial communities as a one-way sink for carbon monoxide," Colman says. The communities both produce and consume carbon monoxide. "It's a dynamic cycle."
Colman's calculations suggest that carbon monoxide may have nearly reached percentage concentrations of 1 percent in the atmosphere, tens of thousands of times higher than current concentrations. This in turn would have exerted influence on concentration of atmospheric methane, a powerful greenhouse gas, with consequences for global temperatures.
Toxic concentrations
Furthermore, such high carbon monoxide concentrations would have been toxic for many microorganisms, placing evolutionary pressure on the early biosphere.
"A much larger fraction of the microbial communi
'/>"/>
| Contact: Steve Koppes skoppes@uchicago.edu 773-702-8366 University of Chicago Source:Eurekalert |
Related biology news :
1. Report shows dramatic decline in Siberian tigers
2. International team of students and scientists on month-long field course in Siberian Arctic
3. Siberian jays use complex communication to mob predators
4. Wolverines threatened by climate change, earlier springs
5. Animal evolution springs from Snowball Earth
6. Nanosprings offer improved performance in biomedicine, electronics
7. Montana State grad student to study unique soil around Yellowstone hot springs
8. Will earlier springs throw nature out of step?
9. Resilin springs simplify the control of crustacean limb movements
10. Simple fungus reveals clue to immune system protection
11. Satellite tracking of sea turtles reveals potential threat posed by manmade chemicals
 |
| Copyright © 2003-2012 Bio-Medicine. All rights reserved. ABOUT | CONTACT US | DISCLAIMER | PRIVACY POLICY | TERMS AND CONDITIONS |  |