What is ozone layer and causes of ozone layer depletion

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On the previous page, we have shared the information of tides, so read that post also.

Let us read and understand the information about the ozone layer today.

what is ozone layer

ozone layer

The ozone layer is a layer found in a particular region in the Earth’s stratosphere. Which acts as a shield against the ultraviolet rays coming from the sun.

The ozone layer absorbs about 97–99% of the medium-frequency ultraviolet light emitted by the Sun. The ozone layer is made up of 3 atoms of oxygen and is denoted as O₃.

There is a large amount of ozone in the stratosphere. Surprisingly, it is ultraviolet radiation that forms the ozone layer.

due to the depletion of the ozone layer

The following are the reasons for the depletion of the ozone layer.

1. Chlorofluorocarbons

They are made up of chlorine, fluorine and carbon. Which are released into the atmosphere by refrigerators, aerosols, solvents etc.

CFC molecules break down when exposed to ultraviolet radiation, thus releasing chlorine atoms.

This free chlorine atom reacts with ozone and depletes it.

2. Nitrogen Compounds

nitrogen Compounds such as NO₂, N₂, N₂O are responsible for ozone depletion.

The sources of nitrogen oxides are mainly thermonuclear weapons, agricultural fertilizers and industrial emissions.

3. Bromine compound

These are called hydrobromo furocarbons (HBFCs) and are used in fire extinguishers.

Each bromine atom destroys a hundred times more ozone molecules than a chlorine atom.

4. Natural Causes

Ozone layer gets depleted due to many natural reasons such as sunspot cycle, volcanic eruptions.

However, due to natural causes, only about 1-3% damage is done to it.

what are ozone depleting substances

Ozone depleting substances are those that react with ozone and further thin the ozone layer.

The number of substances and their sources are present in the following table.

number of substances Source
CFCs Refrigerators, air-conditioners, solvents, dry-cleaning agents, etc.
halons fire extinguisher
carbon tetrachloride fire extinguishers, solvents
methyl chloroform aerosol
hydrofluorocarbons fire extinguisher

How is the ozone layer depleting

A major cause of ozone layer depletion is the chemical chlorofluorocarbons or CFCs. CFCs are typically composed of carbon, fluorine and chlorine.

They are quite durable and can withstand harsh conditions. CFCs generally do not react, but only react with sunlight. When it breaks down to release chlorine.

CF₂ Cl₂ + UV light → CF₂ Cl + + Cl

This chlorine reacts with the ozone layer and forms oxygen and chlorine monoxide. There are ozone depletion reactions.

CL + O₃ → CLO + O₂

When chlorine monoxide reacts with another molecule of oxygen, it breaks down again and releases chlorine that can react with ozone again.

ClO + O → Cl + O₂

However, it is not only CFCs that can deplete the ozone layer. Ozone depletion can also occur due to many climatic and natural conditions.

For example, when the Antarctic hole was observed, scientists discovered many reasons for the formation of the ozone hole in Antarctica.

What are the effects of ozone depletion

A decrease in the amount of ozone means an increased penetration of UV rays on the surface of the Earth. It has devastating effects on human health, animals, plants, microorganisms and air quality.

Effects on human health and animal health

  • People become vulnerable due to increase in the incidence of eye diseases, skin cancer.
  • UV rays are the main reason for the development of skin cancer in a population of people with light skin.

effect on plants

  • The psychological processes of plants are affected by UV rays.
  • The response to UV rays varies among different species.
  • In forests and grasslands, it is responsible for changing species composition.

impact on aquatic ecosystem

  • Excess exposure to UV rays has affected the mobility in phytoplankton resulting in reduced survival rates of these organisms.
  • UV rays have been found to cause damage in the developmental stages of fish, crabs, amphibians and various other animals. The more serious effects are decreased fertility.

impact on air quality

  • The products formed due to these reactions have adverse effects on human health and plants.
  • An increase in the tropospheric reaction would lead to an increase in particulate production due to oxidation and nucleation of sulfur from anthropogenic and natural causes.

effect on other objects

  • Substances such as polymers, naturally occurring biopolymers, are affected by UV rays.

Measures to solve the problem of ozone layer depletion

  • Instead of using chemicals, the use of pesticides should be stopped and natural methods should be adopted to get rid of the pests.
  • Cars produce a significant amount of greenhouse gases. Which contribute to global warming as well as ozone depletion. Therefore, the use of vehicles should be reduced as far as possible.
  • Many of the materials used for cleaning contain chemicals that damage the ozone layer. That is why we should use good quality and non-degradable materials.

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