The Mystery of Earth’s Oxygen
By Carl Zimmer | NYTimes
To Donald E. Canfield, there’s something astonishing in every breath we take. “People take oxygen for granted because it’s just there and we breathe it all the time,” said Dr. Canfield, a geochemist at the University of Southern Denmark. “But we have the only planet we know of anywhere that has oxygen on it.”
What’s 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, they’re 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 oxygen’s history. They’re 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 earth’s primordial air was made up mostly of carbon dioxide, methane and nitrogen. The sun’s 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.
That’s 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 today’s oxygen levels. That may not sound like much, but it marked a huge shift in the earth’s chemistry.
Sunlight alone couldn’t 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 earth’s 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 couldn’t 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 Earth’s Oxygen and Water?"
World’s oldest fossils: Researchers claim bacteria existed on Earth before OXYGEN
Latest News from our Front Page
Aurora Shooting Victim Parents Face $200K Court Fees, Bankruptcy, After Failing to Sue Ammo Dealers
The 2012 Colorado Theater Shooting still doesn’t add up…
Media character and ‘Shooter’ James Holmes in court in 2012-2013.
In 2014, Sandy and Lonnie Phillips, the mother and stepfather of Aurora Theater Shooting victim Jessica Redfield Ghawi, tried to sue the ammo companies they believe supplied shooter James Holmes with his ammunition, body armor and other items. They bleived that the online retailer BulkAmmo.com had sold Holmes ...
FBI's Joint Terrorism Task Force Investigating Confederate Flags at MLK's Ebenezer Baptist Church
According to the Atlanta Police Department, two White men left four small Confederate Battle Flags outside MLK’s Ebenezer Baptist Church in Atlanta … and get this, the FBI’s Joint Terrorism Task Force is on the scene investigating the incident.
Atlanta police Chief George Turner said his agency was working with federal authorities and they have not determined what charges might be ...
Democratic National Committee Chair Wasserman Schultz Canâ€™t Explain Difference Between Democrat Party and Socialism
Things got very awkward today when Chris Matthews asked DNC Chair Debbie Wasserman Schultz what the difference was between the modern Democratic Party and Socialism.
We havenâ€™t seen that dazed look since Rachel Dolezal was busted as a fraud.
Wasserman Schultz was speechless.
Then changed the subject.
Because we all know there is no difference between todayâ€™s Democrat Party and the radical ...
Catching on slow: Yet Another Study Show Cellphone Radiation Cause Cancer
The scientists were right — your cell phone can give you cancer.
There have long been whispers of a cancer connection from your cell — and a new study backs up the claims.
"These data are a clear sign of the real risks this kind of radiation poses for human health," study author Igor Yakymenko said.
Yakymenko’s meta-study — basically a study of ...
Trump Goes #Cuckservative on Immigration
For weeks, the media have trumpeted the supposed death of the Trump campaign. First, they claimed, Trump’s campaign imploded on launch thanks to his comments about illegal immigration. Then they claimed that Trump was finished because of his slap at Senator’s (R-AZ) war service. But neither of those comments alienated Trump’s base – he’s maintained his seven point lead over ...
|More News » |