essay on Ozone depletion
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Some pollutants in the atmosphere like chlorofluoro-carbons (CH3) cause the depletion of ozone layer. ... These CFCs and other similar 'gases when reach to the stratosphere they are broken down by the ultraviolet radiation and as a result they liberate free atoms of chlorine or bromine.
•Ozone (O3) is a triatomic form of oxygen. It is found largely in the stratosphere that extends from about 6 km at the poles and 17 km at the equator to about 50 km above the earth’s surface. It is present in traces less than 1 ppm) in the atmosphere. It has a peak concentration (10 mg kg-1) in the stratosphere.
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Ozone has been the most reactive form of molecular oxygen and the fourth most powerful oxidizing agent. It has a pleasant concentration at about 2 ppm or less, but higher concentration is irritating. It is used as a disinfectant and bleaching agent.
In nature O3 is formed in the stratosphere when ultraviolet light strikes an oxygen molecule. A photon splits the oxygen molecule into two highly reactive oxygen atoms (O). These combine quickly with an oxygen molecule to form ozone. The O3 readily absorbs UV light and dissociates into its constituent components.
Being a natural constituent of the stratosphere, O3 is regularly formed and destroyed in a cyclic manner with solar radiation as the driving force. In the absence of any other disturbances, O3 settles into a dynamic steady state in which the rate of its formation is equal to the rate of its destruction.
Ozone works like an umbrella and protects from the harmful UV radiations coming from cosmic rays to earth. In spite of being a trace gas, it plays a major role in the maintenance of climate and biology of earth. It filters out all radiations below 3000 A0 (UV-B radiations) that are biologically harmful, and controls the heat budget of the earth.