What was the amount of oxygen in earths early atmosphere

So oxygen was able to build up in the atmosphere, causing perhaps the most dramatic shift in the history of life on the planet. Before that happened, the amount of oxygen in Earth's atmosphere was about one ten-quadrillionth of the amount present today, Kasting says.

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characterization of nanoparticles is a critical step in nanomaterial production as it provides information of dimension, morphology, surface charge, distribution and degree of surface functionalization.

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there was a variety of food available on island x, but there were only large seeds and nuts on island y.