Scientists push back emergence of life-giving element by 100 million years
THURSDAY, Sept. 27 (HealthDay News) -- Traces of oxygen may have been present in Earth's atmosphere 50 million to 100 million years earlier than previously thought, according to two international research teams reporting in the Sept. 28 issue of the journal Science.
Most geoscientists believe that atmospheric oxygen levels increased sharply from very low levels during the Great Oxidation Event, which occurred between 2.3 billion and 2.4 billion years ago. There has been great debate about the amount of oxygen existing before that event, according to background information in a news release about the new research.
The new studies provide "compelling new evidence" of early oxygen and lead to the question of whether it's possible to find evidence that oxygen was produced even earlier, said biogeochemist Ariel Anbar, an associate professor in Arizona State University's School of Earth and Space Exploration and department of chemistry and biochemistry in the College of Liberal Arts and Sciences.
Anbar led one of the research teams and was a member of the other team.
By analyzing layers of a kilometer-long core sample of sedimentary rock taken from the Hamersley Basin in Western Australia, the researchers found evidence that oxygen was present in Earth's oceans and possibly in the atmosphere 2.5 billion years ago.
"We seem to have captured a piece of time before the Great Oxidation Event during which the amount of oxygen was actually changing -- caught in the act, as it were," Anbar said in a prepared statement.
"Studying the dynamics that gave rise to the presence of oxygen in Earth's atmosphere deepens our appreciation of the complex interaction between biology and geochemistry," Carl Pilcher, director of the NASA Astrobiology Institute, said in a prepared statement. The institute helped fund the research.
The findings "support the idea that our planet and the life on it evolved together," Pilcher said.
The American Museum of Natural History has more about oxygen.
-- Robert Preidt
SOURCE: Arizona State University, news release, Sept. 27, 2007
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