The Mystery of Earthís Oxygen
By Carl Zimmer | NYTimes
To Donald E. Canfield, thereís something astonishing in every breath we take. ďPeople take oxygen for granted because itís just there and we breathe it all the time,Ē said Dr. Canfield, a geochemist at the University of Southern Denmark. ďBut we have the only planet we know of anywhere that has oxygen on it.Ē
Whatís even more astonishing is that the earth started out with an oxygen-free atmosphere. It took billions of years before there was enough of it to keep animals like us alive.
Although scientists have been struggling for decades to reconstruct the rise of oxygen, theyíre still making fundamental discoveries. In just the past two weeks, for example, Dr. Canfield and his colleagues have published a pair of studies that provide significant clues about some of the most important chapters in oxygenís history. Theyíre finding that our weirdly oxygen-rich atmosphere is the result of a complicated dance of geology and biology.
To study the ancient atmosphere, geochemists examine the chemical fingerprints left behind on rocks. Some rocks contain molecules that could have formed only in the presence of oxygen. The more of those molecules geochemists find in a rock, the more oxygen must have been in the atmosphere at the time.
When they look at the oldest rocks on earth, they find no trace of oxygen in the atmosphere. Instead, their research indicates that earthís primordial air was made up mostly of carbon dioxide, methane and nitrogen. The sunís rays created some free oxygen by splitting it off from carbon dioxide and other molecules. But the oxygen disappeared almost as soon as it was formed.
Thatís because oxygen is an enormously friendly element, forming bonds with a wide range of molecules. It attached to the iron in rocks, for example, creating rust. It joined with hydrogen spewed out from volcanoes to form hydrogen peroxide and other compounds. Our planet, in other words, was a giant oxygen vacuum in its early years.
That changed about three billion years ago. In the Sept. 26 issue of Nature, Dr. Canfield and his colleagues reported the fingerprints of oxygen in rocks from that time period. They estimate that the atmosphere three billion years ago had only 0.03 percent of todayís oxygen levels. That may not sound like much, but it marked a huge shift in the earthís chemistry.
Sunlight alone couldnít have put that much oxygen in the atmosphere. Only life could.
By three billion years ago, some microbes had evolved the ability to carry out photosynthesis. Floating at the surface of the ocean, they used energy from sunlight to grow on carbon dioxide and water. They gave off oxygen as waste.
Much of the oxygen released by these photosynthetic microbes was sucked out of the atmosphere by the earthís vacuum. When microbes died, oxygen reacted with their carbon.
But a tiny amount of oxygen remained behind because some of the organic matter from the dead microbes sank from the surface of the ocean to the sea floor, where oxygen couldnít react with it. The oxygen remained in the air.
Read the full article at: nytimes.com
Discoveries of Oxygen
Mars had an oxygen-rich atmosphere four billion years ago
Cosmic Dust --"A Clue to Origin of Earthís Oxygen and Water?"
Worldís oldest fossils: Researchers claim bacteria existed on Earth before OXYGEN
Latest News from our Front Page
Sweden to give over 8 million euros to Turkey for "refugee deal" - Europe to give three billion euros total
Prime Minister Stefan L√∂fven announced on Sunday that Sweden would contribute to a joint action plan agreed by nine EU nations designed to limit the number of refugees arriving in Europe via Turkey.
The deal came after the German Chancellor Angela Merkel held a surprise summit in Brussels involving the leaders of nine countries including Sweden, France and the UK.
The European ...
Swedish woman raped by "refugee" refuses to report it because she feels sorry for him
Victim sympathized with rapist's "difficult situation"
A Swedish woman who was raped by an Iraqi ‚Äúrefugee‚ÄĚ on a train initially refused to report the incident to police because she ‚Äėfelt sorry‚Äô for her attacker.
The incident occurred on a night train between Ume√• and Sundsvall back in October. The Iraqi refugee was traveling back to Sweden because he was unhappy with the ...
ISIS Oil Trade Full Frontal: "Raqqa's Rockefellers," Bilal Erdogan, KRG Crude, And The Israel Connection
"Effectively, we have been financially discriminated against for a long time. By early 2014, when we did not receive the budget, we decided we need to start thinking about independent oil sales‚ÄĚ -- Ashti Hawrami, Kurdistan‚Äôs minister for natural resources
In June of 2014, the SCF Altai (an oil tanker) arrived at Ashkelon port. Hours later, the first shipment of Kurdish ...
Prosecutors ban Soros Foundation as 'threat to Russian national security'
The Russian Prosecutor General‚Äôs Office has recognized George Soros‚Äôs Open Society Institute and another affiliated organization as undesirable groups, banning Russian citizens and organizations from participation in any of their projects.
In a statement released on Monday, prosecutors said the activities of the Open Society Institute and the Open Society Institute Assistance Foundation were a threat to the foundations of Russia‚Äôs ...
Israeli Colonel Caught with Islamic State (IS) Pants Down
This was definitely not supposed to happen. It seems that an Israeli military man with the rank of colonel was ‚Äúcaught with IS pants down.‚ÄĚ By that I mean he was captured amid a gaggle of so-called IS‚Äďor Islamic State or ISIS or DAESH depending on your preference‚Äďterrorists, by soldiers of the Iraqi army. Under interrogation by the Iraqi intelligence ...
|More News » |