What is Ozone Layer Depletion?
The ozone layer present in the stratosphere acts as a protective shield. It saves the earth from the harmful ultraviolet rays of the sun. The compounds containing CFCs (chlorofluorocarbons) are mainly responsible for ozone layer depletion as these compounds react with ozone in the presence of ultraviolet rays to form oxygen molecules and thus, destroying ozone.
Scientists have already found an ozone hole over the South Pole. Once the ozone layer is depleted, ultraviolet rays will pass through the troposphere and eventually to earth. These rays cause ageing of the skin, skin cancer, cataract and sunburn to humans as well as animals. Phytoplankton dies in the presence of ultraviolet rays which results in a decrease in fish productivity.
Causes & Effects of Ozone Layer Depletion
The evaporation of surface water through the stomata of leaves increases, which results in the decreased moisture content of the soil. The proteins cells in plants undergo harmful mutations, all due to ultraviolet radiation. Paints and fibres are also damaged by the increased levels of ultraviolet rays, causing them to fade faster.
Chlorofluorocarbons and other halocarbons are held responsible for ozone layer depletion, but if we explore more about them we will find that these are major greenhouse gases. These gases absorb heat in the atmosphere and increase the earth’s temperature, resulting in global warming. Increase in earth’s temperature causes the melting of ice caps. This raises the water level of the oceans and seas. Coastal areas get flooded and area under land cover reduces.
The Ozone Hole
In the year 1980 scientists reported the depletion of the ozone layer in the region of Antarctica which is commonly known as the ozone hole. Ozone layer depletion occurs due to unique sets of climatic conditions. In the summer, nitrogen dioxide and methane react with chlorine monoxide and chlorine atoms which results in a shrinkage of chlorine and hence prevents ozone layer depletion.
ClO (g) + NO2 (g) → ClONO2 (g)
Cl (g) + CH4 (g) → CH3 (g) + HCl (g)
During winter, special types of clouds are formed over the Antarctic region. These clouds provide the surface for the hydrolysis of chlorine nitrate to form hypochlorous acid. Chlorine nitrate also reacts with hydrogen chloride thereby producing molecular chlorine.
ClONO2 (g) + H2O (g) → HOCl (g) + HNO3 (g)
ClONO2 (g) + HCl (g) → Cl2 (g) + HNO3 (g)
During spring, sunlight enters Antarctica and breaks up the clouds. Photolysis of HOCl and Cl2 occurs which forms chlorine radicals and this reaction initiates the ozone layer depletion.
Prevention and Measures
Many plants and animals find it difficult to survive in areas having a high temperatures. In such cases, the changes in climatic conditions are the main reason for their extinction. The following measures should be taken to prevent the ozone layer depletion:
- Private vehicle driving should be limited – Vehicular emission results in smog, which harms the ozone layer. Carpooling, using public modes of transportation, walking, cycling etc should be promoted.
- Avoid using pesticides – Pesticides are used for getting rid of weeds but are very harmful to the ozone layer. Natural remedies should be used instead of pesticides.
- Using eco-friendly products – We can use eco-friendly cleaning products for domestic purposes and save the ozone from further deterioration.
- Replacing CFC’s used in air conditioners and refrigerators – Hydrofluorocarbons (HFCs) have been identified as potential replacements for CFCs (which is the major cause of Ozone Layer Depletion) as they have an Ozone Depletion Potential of 0. The use of HFCs in place of CFCs will go a long way in protecting our Ozone layer from getting depleted.
- Proper Waste disposal techniques – Avoid burning waste materials like plastic and other materials. Give non-decomposable products for recycling or try and reuse them for other purposes.
We have seen the various effects of ozone layer depletion and can conclude by saying that it is very important for our survival. Measures should be taken to protect our earth from harmful ultraviolet rays. This can only be done by reducing the use of compounds which react in the atmosphere to harm the ozone layer.
Frequently Asked Questions – FAQs
What is ozone layer depletion? How does it occur?
What are ozone-depleting substances? Give examples.
What is the main aim of the Montreal Protocol?
What are the effects of ozone layer depletion on human health?
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