Ozone Layer and Its Depletion
Ozone, in fact is a gas having fishy smell and O3 molecules which works as the protective shield for the life in the earth. It absorbs solar ultraviolet radiations and thereby protects life on the earth from several damage such as DNA mutation, skin cancer, blood cancer, etc.
In the year 1985, NASA detected the thinning out of the ozone layer leading to the formation of ‘ozone hole’ in Antarctica. Since then the scientists have been regularly monitoring the thickness of the ozone layer. They have found that the thickness of the ozone layer has been decreasing day by day at the alarming rate as a result of the environmental pollution. The main culprits of the serious depletion of ozone layer are found to be the manmade chlorofluorocarbons (CFC’s). These CFC (also known as ferons) are stable non-corrosive and inert compounds containing chlorine, fluorine and carbons. They are extensively used as the coolants in refrigerators, air conditioners and as propellants in aerosol cans and in plastic forms. These CFC molecules, once they escape into the atmosphere, migrate to the stratosphere and decompose to release chlorine atoms in the ozone layer.
CCL2F2 CCLF2 + Cl---------- (i)
Then the chlorine atom attacks the ozone moleculs
Cl + O3 ClO + O2-------------(ii)
This reaction is followed by:
ClO Cl + O-------------(iii)
So chlorine atoms are generated in reaction (i), consumed in reaction (ii) and again regenerated in reaction (iii). As a result of this chain reaction, one chlorine atom can destroy 100,000 ozone molecules.
The other agents responsible for the depletion of ozone are NO gas, oxygen radicals(O) and hydroxyl radicals(OH).
The depletion of ozone layer will lead to the penetration of more and more UV radiations which results as skin cancer, blood cancer, cataracts, etc. and also cause harm to the plants and