Náttúrufræðingurinn - 1990, Side 24

vísi við, en eins og stefnt er að víðast
hvar og stöðva notkun og framleiðslu
ósoneyðandi efna.
HEIMILDIR
deZafra, R.L., M. Jaramillo, J. Barrett,
L.K. Emmons, P.M. Solomon, & A.
Parrish 1989. New observations of a
large concentration of CIO in the
springtime lower stratosphere over Ant-
arctica and its implications for ozone-
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Gribbin, J. 1988. The hole in the sky;
man’s threat to the ozone layer. Gorgi
Books, Bretland, 160 bls.
Hofmann, D.J., J.W. Harder, S.R. Rolf,
& J.M. Rosen 1987. Balloonborne ob-
servations of the development and ver-
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hole in 1986. Nature 326. 59-62.
McEwans, M.J. & L.F. Philips 1975.
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SUMMARY
Is the depletion of the ozone
layer due to chemistry?
by
Ágúst Kvaran
Science Institute,
University of Iceland,
IS-107 REYKJA VÍK
Iceland
The proposed effect of chlorofluorocar-
bons on the depletion of the ozone layer is
described. The major chemical reaction of
ozone in the atmosphere is with oxygen
atoms to form oxygen molecules. This de-
pletion reaction is made up for by ozone
formation due to recombination of oxygen
atoms and molecules in a three-body colli-
son. Thus a steady state concentration of
ozone is established with maximum con-
centration at an altitude of just over 20
km. The equilibrium, however, can be
shifted towards a lower ozone concentra-
tion due to halogen atom catalysis, after
halogen atom release from chlorofluoro-
carbon molecules by UV solar radiation
photolyses. Detailed measurements of
chemical concentration of various com-
pounds in the lower stratosphere over
Antarctica support the hypothesis that po-
lar stratospheric clouds play an important
role in ozone depletion by halogen atom
reformation due to surface catalysis.
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