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Ozone Layer Depletion
The ozone layer is a layer of a gas (ozone, O3) in the part of the atmosphere called stratosphere. It acts to prevent or shield the harmful ultraviolet rays of the sun from the earth. In 1974, a scientist named Rowland noticed that the ozone layer was being
depleted faster than it was formed. This observation was confirmed in 1985.
Certain gases have been identified to be responsible for the depletion of the ozone layer, these are: the chlorofluorocarbons (CFCs); hydro chlorofluorocarbons (HCFCs); halons; methyl bromide; carbon tetrachloride; and methyl chloroform.
Ozone depleting substances degrade (i.e. break-down) in the stratosphere under intense ultraviolet light to release chlorine or bromine atoms, which then deplete the ozone layer.
Effects of Ozone Layer Depletion
With the depletion of the ozone layer, the earth becomes exposed to the several harmful effects of high level of UVB (a kind of ultraviolet light of wavelength 280-320 nanometres) from the sun.
Effect on human health: it causes nonmelanoma skin cancer and plays a major role in malignant melanoma development. Also, UVB has been linked to cataracts.
Effect on plants: physiological and development processes of plants are affected by UVB.
Effect on marine ecosystems: phytoplankton form foundation of aquatic food webs- their productivity is limited by UVB.
Effect on biogeochemical cycles
Effect on materials: synthetic polymers, naturally occurring biopolymers, as well as some other materials of commercial interest are adversely affected by solar UV radiation.
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