Seven percent of the electromagnetic radiation
emitted from the sun is in the UV range (200–400
nm). As it passes through the atmosphere, the total
flux transmitted is greatly reduced, and the composition
of the UV radiation is modified. Shortwave
UV-C radiation (200–280 nm) is completely absorbed
by atmospheric gases. UV-B radiation (280–320 nm)
is additionally absorbed by stratospheric ozone and
thus only a very small proportion is transmitted to
the Earth’s surface, whereas UV-A radiation (320–400
nm) is hardly absorbed by ozone (Fig. 1). In the past
50 years, the concentration of ozone has decreased by
about 5%, mainly due to the release of anthropogenic
pollutants such as chlorofluorocarbons (Pyle, 1996).
Consequently, a larger proportion of the UV-B spectrum
reaches the Earth’s surface with serious implications
for all living organisms (Xiong and Day, 2001;
Caldwell et al., 2003).
Seven percent of the electromagnetic radiation
emitted from the sun is in the UV range (200–400
nm). As it passes through the atmosphere, the total
flux transmitted is greatly reduced, and the composition
of the UV radiation is modified. Shortwave
UV-C radiation (200–280 nm) is completely absorbed
by atmospheric gases. UV-B radiation (280–320 nm)
is additionally absorbed by stratospheric ozone and
thus only a very small proportion is transmitted to
the Earth’s surface, whereas UV-A radiation (320–400
nm) is hardly absorbed by ozone (Fig. 1). In the past
50 years, the concentration of ozone has decreased by
about 5%, mainly due to the release of anthropogenic
pollutants such as chlorofluorocarbons (Pyle, 1996).
Consequently, a larger proportion of the UV-B spectrum
reaches the Earth’s surface with serious implications
for all living organisms (Xiong and Day, 2001;
Caldwell et al., 2003).
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