why was there no oxygen in the early atmosphere

Scientists believe that the Earth was formed about 4. 5 billion years ago. Its early atmosphere was probably
formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence. The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans. It is thought that the atmospheres of Mars and Venus today, which contain mostly carbon dioxide, are similar to the early atmosphere of the Earth.


Scientists cant be sure about the early atmosphere and can only draw evidence from other sources: for example, volcanoes on other planets release high quantities of carbon dioxide or nitrogen and iron-based compounds which are present in very old rocks that could have formed only if there was little or no oxygen. So how did the proportion of carbon dioxide in the atmosphere go down, and the proportion of oxygen go up? The proportion of oxygen went up because of photosynthesis by plants. it was locked up in sedimentary rocks such as limestone, and in fossil fuels photosynthesis The chemical change that occurs in the leaves of green plants.


It uses light energy to convert carbon dioxide and water into glucose. Oxygen is produced as a by-product of photosynthesis. it dissolved in the oceans. The burning of fossil fuels is adding carbon dioxide to the atmosphere faster than it can be removed. This means that the level of carbon dioxide in the atmosphere is increasing. Scientists believe that the Earth was formed about 4. 5 billion years ago. Its early atmosphere was probably formed from the gases given out by volcanoes. It is believed that there was intense volcanic activity for the first billion years of the Earth's existence. The early atmosphere was probably mostly carbon dioxide, with little or no oxygen.


There were small quantities of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans. So how did the proportion of carbon dioxide in the atmosphere go down, and the proportion of oxygen go up? The proportion of oxygen went up because of photosynthesis by plants. it was locked up in sedimentary rocks, such as limestone, and in fossil fuels The burning of fossil fuels is adding carbon dioxide to the atmosphere faster than it can be removed. This means that the level of carbon dioxide in the atmosphere is increasing.

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