QUIZ 20a. Later developments in the earth's atmosphere

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(a) In the early Earth's atmosphere the nitrogen gas formed from was released into the air, partly from the reaction with oxygen, but mainly from living organisms, including bacteria. Ammonia is also converted to by nitrifying .

(b) The in the atmosphere resulted in the development of an layer. This filters out ultraviolet radiation from the Sun allowing the of new living organisms. If the ozone layer is too depleted it can result in more cases of .

(c) Carbon dioxide can be chemically trapped in carbonate rocks in the Earth's crust by but may then be decomposed in volcanic action to return the back into the atmosphere.

(d) The reaction between carbon dioxide and can produce insoluble magnesium and mainly which are deposited as .

(e) Also calcium and magnesium are formed but these do not wholly the additional carbon dioxide released into the atmosphere.

(f) These days the release of carbon dioxide by burning the locked up over hundreds of millions of is released as we burn fossil fuels increasing the of carbon dioxide in the atmosphere. The extra carbon dioxide in the atmosphere might lead to , the so-called ' effect'.