Explain Ozone layer its depletion and effects of depletion layer?
Hint: The ozone layer shields the life on Earth's atmosphere from the UV radiations like UV-B, UV-C. The ozone layer is a region in the earth stratosphere that contains high concentrations of ozone and protects the earth from the harmful ultraviolet rays of the sun. It comprises a high concentration of ozone about 18-50 km above in the atmosphere, which is commonly called an ozone blanket.
Complete answer: - Ozone layer depletion is the gradual thinning of the earth's ozone layer in the upper atmosphere caused due to release of chemical compounds containing gaseous bromine or chlorine from industries and human activities.
- It is being depleted by air pollutants. Chlorofluorocarbons (CFCs) which are synthetic harmful chemicals which are widely used in refrigerators and air conditioners as propellants. These chlorofluorocarbons are air pollutants and are mainly responsible for the depletion of the ozone layer in the atmosphere.
- When these are released in the air, these harmful chemicals produce active chlorine' (Cl and CIO radicals) and fluorine in the presence of UV radiation. These radicals, through a chain reaction, then destroy the ozone by converting it into oxygen.
- Due to this, the ozone layer in the upper atmosphere (i.e., stratosphere) becomes thinner.
- One lakh ozone molecules can destroy a single chlorine atom.
- Chlorofluorocarbons are, therefore, termed major ozone-depleting substances (ODS).
- Other ozone-depleting substances are nitrogen oxides and hydrocarbons.
The thinning of the ozone layer allows more ultraviolet (UV) radiations to pass through it which then strike the earth. These cause the following harmful effects on man, animals, and plants: - Skin cancer. - Damage to the eyes also increases the incidence of cataract disease in the eyes. - Damage to the immune system. - Increased embryonic mortality in animals and humans. - In plants, there will be an increased death rate of seedlings, increased incidence of harmful mutations, and reduction in yields. - Planktons are highly affected, causing an effect in the food chain of the aquatic food chain.
Note: The amount of ozone varies naturally throughout the year as a result of chemical processes that create and destroy ozone molecules. Due to the chemical reactions that break down the ozone molecules, the Ultraviolet absorbing capacity is decreased.