|MadSci Network: Environment & Ecology|
I couldn't find any information on the actual percentage of oxygen that is produced from rain forests versus that which is produced from oceans. But here is the information that I did find out...
The earth's atmosphere is composed of nearly 21% oxygen. Most of this oxygen is produced by rain forests and other vegetation through photosynthesis.
The process by which sunlight splits water vapor molecules into hydrogen and oxygen is called photodissociation. This process is only capable of producing trace amounts of oxygen. Therefore I would venture to guess that 95+ percent of the oxygen comes from vegetation.
Evaporation would contribute to photodissociation, since water must be in the form of vapor for dissociation to occur.
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