Name two of the main gasses found in the primitive atmosphere and where did they come from?
Earth's First Atmosphere
The primitive atmosphere is the term used to describe what Earth's atmosphere was when the planet was first formed billions of years ago. The main theory that has been discussed by scientists is that Earth previously had a reducing atmosphere, meaning that the atmosphere was mostly composed of reducing gases. This would have been due to the effects of thunder shockwaves, or by outgassing of many active volcanoes.
Answer and Explanation:
It should first be noted that the theory of how Earth's origin came to be is still widely debated. Scientists are currently studying some of Earth's oldest rock formations and samples in order to determine what Earth's primitive atmosphere was composed of. One of the main theories that Earth's atmosphere was reducing is due to the amount of active volcanoes and hydrothermal vents, which released large amounts of carbon dioxide into the air and minimized the amount of oxygen. The volcanoes would have also released a large amount of nitrogen. Due to the heat released as a byproduct of the outgassing, water also would have likely remained in a vapour state rather than a liquid.
Today, nitrogen still remains to be one of the biggest components of the atmosphere. As the atmosphere began to become less volatile and the Earth's surface began to cool, bacteria that are able to withstand reducing environments such as Cyanobacteria would have began to use CO2 in photosynthetic processes, and oxygen would be produced. This would eventually allow other forms of life to evolve and survive. Currently, oxygen accounts for approximately 21% of Earth's atmosphere.
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from Science 101: Intro to Natural SciencesChapter 15 / Lesson 1