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Humans affect the earth's
environment by releasing substances that
deplete the protective ozone layer. The Nobel
laureates in Chemistry 1995, Mario
Molina, Sherwood
Rowland and Paul
Crutzen, clarified the mechanisms for the
chemical reactions involved. The results have
led to extensive limitations on the release of
ozone-damaging substances. Read more about the
ozone layer and:
*Plastic foam and
refrigerators
*Nitrogen oxides
*The Ozon Hole over
Antarctica
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Ozone (03) is formed in the
stratosphere through the splitting of ordinary
oxygen molecules (02) by ultraviolet
radiation from the sun. The liberated oxygen
atoms (O) react, through the mediation of some
arbitrary molecule (M), with molecular oxygen
as follows:
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Ozone
in small amounts
If all atmospheric ozone were compressed to the
pressure at the earth's surface, the layer would
be only 3 mm thick.
Even though ozone occurs in such small quantities
it plays a fundamental role for life on
earth.
Ozone for better and for worse
The atmosphere surrounding the earth contains
small quantities of ozone, most of which is in
the ozone layer in the stratosphere, 10-50 km
above the earth's surface.
Stratospheric ozone, together with molecular
oxygen, absorbs most of the ultraviolet radiation
from the sun. This prevents the radiation from
reaching the earths surface where it can damage
plants, animals and humans.
The ozone content in the lower layer of air (the
troposphere, 0-10 km) has increased through the
release of gaseous nitrogen oxides and
hydrocarbons from vehicles, industrial plants and
other sources. Ozone here can damage crops and
people's health and also contribute to raising
the temperature at the surface - the "greenhouse
effect". |
