The Evolutionary Role of Atmospheric Ozone

The ozone content of the early (or palaeo) atmosphere would have determined the intensity of the solar UV flux reaching the Earth's surface during the early stages of biological evolution. Calculations were made of the ozone content of model palaeoatmospheres containing much less than the prese...

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Bibliographic Details
Published in:Journal of the atmospheric sciences 1977-05, Vol.34 (5), p.720-728
Main Authors: Blake, A J, Carver, J H
Format: Article
Language:English
Online Access:Get full text
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Summary:The ozone content of the early (or palaeo) atmosphere would have determined the intensity of the solar UV flux reaching the Earth's surface during the early stages of biological evolution. Calculations were made of the ozone content of model palaeoatmospheres containing much less than the present level of atmospheric oxygen (1 PAL). The calculations take account of reactions involving water vapor, the hydroxyl and hydroperoxyl radicals, the nitrogen oxides, and methane and carbon dioxide, in addition to the classical ozone chemistry. For a wide range of assumptions covering the nature of the atmospheric model, it is found that the palaeoatmosphere has a biologically effective ozone screen, provided that the atmospheric oxygen content is not less than 10 super(-) super(3) PAL. This result suggests that solar UV radiation could not have been the energy source for the prebiotic synthesis of organic molecules, unless the synthesis took place outside the Earth's environment.
ISSN:0022-4928
1520-0469
DOI:10.1175/1520-0469(1977)034<0720:TEROAO>2.0.CO;2