Oxygen atmosphere recipe = tectonics + continents + life
http://news.rice.edu/2016/05/16/oxygen-atmosphere-recipe-tectonics-continents-life-2/[font face=Serif][font size=5]Oxygen atmosphere recipe = tectonics + continents + life[/font]
Jade Boyd May 16, 2016
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Rice-led study offers new answer to why Earths atmosphere became oxygenated[/font]
[font size=3]Earth scientists from Rice University, Yale University and the University of Tokyo are offering a new answer to the long-standing question of how our planet acquired its oxygenated atmosphere.
Based on a new model that draws from research in diverse fields including petrology, geodynamics, volcanology and geochemistry, the
teams findings were published online this week in Nature Geoscience. They suggest that the rise of oxygen in Earths atmosphere was an inevitable consequence of the formation of continents in the presence of life and plate tectonics.
Its really a very simple idea, but fully understanding it requires a good bit of background about how the Earth works, said study lead author Cin-Ty Lee, professor of Earth science at Rice. The analogy I most often use is the leaky bathtub. The level of water in a bathtub is controlled by the rate of water flowing in through the faucet and the efficiency by which water leaks out through the drain. Plants and certain types of bacteria produce oxygen as a byproduct of
photosynthesis. This oxygen production is balanced by the sink: reaction of oxygen with iron and sulfur in the Earths crust and by back-reaction with organic carbon. For example, we breathe in oxygen and exhale carbon dioxide, essentially removing oxygen from the atmosphere. In short, the story of oxygen in our atmosphere comes down to understanding the sources and sinks, but the 3-billion-year narrative of how this actually unfolded is more complex.
Lee co-authored the study with Laurence Yeung and Adrian Lenardic, both of Rice, and with Yales Ryan McKenzie and the University of Tokyos Yusuke Yokoyama. The authors explanations are based on a new model that suggests how atmospheric oxygen was added to Earths atmosphere at two key times: one about 2 billion years ago and another about 600 million years ago.
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