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The Earth’s original atmosphere would have been unpleasant—deadly in fact—to any organisms that breathe oxygen. There wasn’t any. Not until about 2.4 billion years ago anyway. That’s the time of what scientists call the Great Oxidation Event. Now researchers believe they’ve found clues as to what may have caused the change. They published their report in the April 9 edition of the journal Nature.
Researchers analyzed trace elements in sedimentary rock from dozens of sites. Turns out nickel was 400 times more abundant in primordial oceans than in today’s waters. Microorganisms called methanogens love nickel-rich water, and they release methane into the atmosphere. Methane prevents a buildup of oxygen.
Scientists testing the rocks saw that around 2.7 to 2.4 billion years ago, ocean-dissolved nickel dropped off. This corresponds to the Great Oxidation Event. Lack of nickel could have killed off methanogens and left room for algae and other life forms that release oxygen during photosynthesis.
Researchers don’t know exactly why nickel decreased—possibly because of the cooling and solidifying of the Earth’s mantle. But the nickel disappearance is one more clue about how the planet went from suffocating to a place where a terrestrial tetrapod could take a deep breath.
—Cynthia Graber
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Add CommentIt is a most interesting discovery (4/9/09 Nature) that around 2.7 to 2.4 billion years ago (Ga), ocean-dissolved nickel dropped off. As nickel dropped decreased, methanogens producing methane diminished. Methane production in the Archean was a major obstacle to oxidation. The Great Oxidation Event occurred period between approx. 2.25 and 2.05 Ga (Karhu and Holland, 1996) when a significant accumulation of O2 occurred in the atmosphere. How did this happen? As life emerged on Earth 3.9 Ga, what led to the transition from a anoxic environment of the Archean to the oxygenated atmosphere of the Proterozoic and Phanerozoic? Out of the single cell microbes, single-celled blue-green algae developed 3.2 billion years ago, and some 2 billion years ago came the first sexual reproduction with later multi-cellular algae. The first life on Earth (oxygen producing microbes that emerged in the seas) did not need oxygen to metabolize. But multi-celled life does need oxygen to metabolize. Were these remarkably concurrent developments all haphazard, just chance events?
Reply | Report Abuse | Link to thisFYI, this is probably all nonsense, since there is significant evidence of oxygenated strata below those associated with the "Great Oxygenation Event." - dated at 3.46 BYA.
Reply | Report Abuse | Link to thisSee, e.g., http://sciencenow.sciencemag.org/cgi/content/full/2009/316/3 .
Seems a little strange, if methane is even more greenhouse than co2, that an atmosphere with 20%+ greenhouse gasses was not too hot for photosynthesis, yet some claim that a rise of co2 of a small fraction of 1% would be runaway heating/greatest threat to humanity over 50 years rather than nuclear or biological weapon/mistake threat over 50 years.
Reply | Report Abuse | Link to thisMultilis, the answer to your retohrical question is in your statement: MIcrobials, not humans, were living in that era (unless you believe the "were all cousins" adam and eve genisis of humans) and beyond the fact that microbial life can withstand a greater temperature range collectively between species than humans, they were not airborn microbals, but waterborn where the watertemp will never exceed 120. Additionally, the entire atmosphere could darn near be on fire and deep water microbials would never be effected.
Reply | Report Abuse | Link to thisPlease limit climate change bashing to the appropriate discussion threads...
Correction: I am mistaken, there was no question mark in your post therefore its just a statement.
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