Academic journal article Science and Children

Revisiting Earth's Oxygenation

Academic journal article Science and Children

Revisiting Earth's Oxygenation

Article excerpt

The history of life on Earth is closely connected to the appearance of oxygen in the atmosphere, which scientists think first occurred in significant amounts during a Great Oxidation Event some 2.4 billion years ago. However, until now, little was known of environmental changes prior to this event. New findings by two teams of scientists indicate that significant oxidative changes were occurring in the oceans and atmosphere before the Great Oxidation Event.

The findings appear in two studies published in the journal Science.

"Together these papers provide compelling evidence for a shift in the oxidation state of the surface ocean 50 million years before the Great Oxidation Event," says Alan Jay Kaufman, associate professor of geochemistry at the University of Maryland. "We believe that these findings are a significant step in our understanding of the oxygenation of Earth because they link changes in the environment with that of the biosphere."

Ancient sedimentary rocks contain evidence of oxidation and other chemical reactions that took place in the oceans and atmosphere as the rocks formed. For example, rock formed from sediments deposited in the shallow waters of an ancient ocean contains chemical clues to the conditions of that water and the air above it. Using sophisticated analytical tools called mass spectrometers, scientists can detect and read these clues. …

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