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The
late 20
th
century saw an alarming
increase in the size of the ozone hole, with its
diameter spanning the entirety of Antarctica
and beyond. In addition to the health risks for
humans associated with an increase in ultraviolet
ray penetration, an expanding ozone hole has
significant ecological and meteorological impacts.
In nature, ozone, oxygen gas, and free oxygen
atoms are constantly being combined, broken
apart, and recombined in the stratosphere. This
process absorbs radiative energy from UV. Ozone
depleting substances such as chlorofluorocarbons
(CFCs), hydrochlorofluorocarbons (HCFCs), and
hydrofluorocarbons act as catalysts speeding up
the breakup of ozone to oxygen gas. This lack
of recycling of ozone is the main cause of ozone
depletion.
The ozone hole above Antarctica is particularly
large due to the extremely cold temperatures. As
a result, thin layers of ice crystals aggregate into
polar stratospheric clouds, which act as catalysts
exacerbating the ef fects of ex isting ozone-
depleting compounds in the atmosphere, such as
chlorine and bromine. An accumulation of these
gases rapidly depletes the ozone layer in these
coldest areas of the stratosphere.
CFCs have been slowly phased out since
the begi nn i ng of the 80 s under the global
environmental treaty known as the Montreal
Protocol. As a result, the stratospheric ozone
layer may be making a slow recover y. In
2014, a group of geophysicists hypothesised
that the ozone layer has the ability to
mend itself, provided that the depletion
rate is at a level much lower than the
rate of natural stratospheric ozone
production. Scientists forecast that
the Antarctic ozone hole is expected
Did you know
你知道嗎
?
The ozone is distributed among two layers of the atmosphere. 10% of atmospheric ozone lies
within the troposphere, measuring approximately 15 km above sea level, and the remaining 90%
resides in the stratosphere. The ozone layer acts as the primary UV radiation shield, reducing health
risks and photo-oxidative damage brought to both terrestrial and aquatic ecosystems.
臭氧被分佈在對流層及平流層。對流層位於海拔約15公里，約10％的臭氧處於此。而90％臭氧分佈在平流
層的底部。臭氧層是紫外線輻射屏蔽，有效減低對人類健康的影響及保護陸地和水生生態系統。
