Chemistry > Enviromental Chemistry > 6.0 Stratospherical Pollution: (Ozone Layer & its depletion)
Enviromental Chemistry
1.0 Introduction
2.0 Environmental Pollution
2.1 Pollutant
2.2 Contaminant
2.3 Source
2.4 Sink
2.5 Receptor
2.6 Threshold limit value (TLV)
2.7 Flow sheet of Environmental pollution process
2.8 Atmospheric Pollution
2.9 Tropospheric pollution or Air pollution
3.0 Types Of Pollution
3.1 Primary pollutants
3.2 Particulate Matter
3.3 Inorganic gases
3.4 Secondary Pollutants
3.5 Major air pollutants
4.0 Particulates
5.0 Control Of Air Pollution
6.0 Stratospherical Pollution: (Ozone Layer & its depletion)
7.0 Acid Rain
8.0 Green House Effect & Global Warming
8.1 Green house effect around the earth
8.2 Advantages of green house effect
8.3 Harmful effects of green house effect
8.4 Water Pollution
9.0 BOD Determination
10.0 COD determination
10.1 Control of water pollution
10.2 Land Pollution
10.3 Pesticides
10.4 Control of soil pollution
10.5 Green Chemistry: A new route to protection of environment
6.2 Depletion of Ozone Layer
2.2 Contaminant
2.3 Source
2.4 Sink
2.5 Receptor
2.6 Threshold limit value (TLV)
2.7 Flow sheet of Environmental pollution process
2.8 Atmospheric Pollution
2.9 Tropospheric pollution or Air pollution
3.2 Particulate Matter
3.3 Inorganic gases
3.4 Secondary Pollutants
3.5 Major air pollutants
8.2 Advantages of green house effect
8.3 Harmful effects of green house effect
8.4 Water Pollution
10.2 Land Pollution
10.3 Pesticides
10.4 Control of soil pollution
10.5 Green Chemistry: A new route to protection of environment
The equilibrium between formation & destruction of ozone has been upset by influx of several substances into the atmosphere which react with ozone to destroy it. The rate at which ozone is being destroyed is much faster than the rate at which it is being formed. The factors which accelerate the ozone depletion are as follows:
1. Effect of chlorofluoro carbons (freons)
A very serious threat to the existence of ozone in the stratosphere comes from the use of chlorofluorocarbons (CFC). CFC’s find a wide & varied applications.
Once they enter the atmosphere, they do not react with any substance due to their chemical inertness & thus can not be eliminated from the atmosphere.
In stratosphere they absorb the UV radiations and break up liberating free chloride atoms. The chlorine atoms react with ${O_3}$ to form a species, chlorine monoxide (CIO) which further combines with O to give O2.
2. Use of Halons
Halons are bromo fluorocarbons which are also used as fire extinguishers & pesticides. Halons produce bromine atoms by the similar process which further results in consumption of very large number of ozone molecules.
3. Oxides of Nitrogen
The sources of oxides of nitrogen are mainly explosion of thermonuclear weapons in the atmosphere, industrial emission & agricultural fertilizers. Like Cl & Br atoms NO molecules also catalytically converts ${O_3}$ to ${O_2}.$
