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By Charles Q. Choi
Underwater volcanic eruptions may have delayed oxygen from building up in the atmosphere of primeval Earth for hundreds of millions of years, researchers say.
The finding sheds light on how Earth became the oxygenated world it is today, scientists added.
“Our research shows how the high concentrations of iron in the Earth’s past could have limited photosynthesis,” said lead study author Elizabeth Swanner, a geomicrobiologist at the University of Tübingen in Germany. Photosynthesis is the process by which plants and other organisms turn sunlight into sugar, and it produces oxygen as a byproduct.
Although life-sustaining oxygen gas currently makes up about a fifth of the Earth’s air, very early in the planet’s history, oxygen was rare in the atmosphere. The first time the element suffused Earth’s primordial atmosphere to any great extent was about 2.3 billion years ago in what is called the Great Oxidation Event. Prior research suggests this jump in oxygen levels was almost certainly due to cyanobacteria — microbes that, like plants, photosynthesize and produce oxygen.
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