When the Earth was first formed there was no oxygen in the atmosphere.Explain how the atmosphere changed so that today it is 21% oxygen and only 0.04% carbon dioxide.
Question
When the Earth was first formed there was no oxygen in the atmosphere.Explain how the atmosphere changed so that today it is 21% oxygen and only 0.04% carbon dioxide.
Solution
The Earth's atmosphere has changed dramatically since its formation 4.5 billion years ago. Here's a step-by-step explanation of how it evolved to its current composition:
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Formation of the Earth's Primitive Atmosphere: When the Earth was first formed, it was surrounded by a primitive atmosphere composed mainly of hydrogen and helium. This atmosphere was likely stripped away by solar winds early in the planet's history.
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Volcanic Outgassing: The second atmosphere was formed by volcanic outgassing, a process in which gases like water vapor, carbon dioxide, and nitrogen were released from the interior of the Earth. This resulted in an atmosphere composed primarily of nitrogen and carbon dioxide, with virtually no oxygen.
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Appearance of Cyanobacteria: Around 3.5 billion years ago, simple life forms known as cyanobacteria (or blue-green algae) began to appear. These organisms were capable of photosynthesis, a process that uses sunlight to convert water and carbon dioxide into glucose and oxygen. The oxygen was released into the atmosphere.
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The Great Oxygenation Event: As cyanobacteria proliferated, the amount of oxygen in the atmosphere gradually increased. This led to the Great Oxygenation Event around 2.4 billion
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