Ozone layer depletion refers to the decline in amount of ozone in Earth's stratosphere (commonly known as Ozone layer) and a large springtime decrease in stratospheric Ozone around the Antarctic region.
Stratospheric ozone is highly beneficial as it protects the living organisms on the Earth's surface from harmful UV radiations of the sun. Ozone is continuously formed and removed in the stratosphere and thus there is an apparent equilibrium in the ozone layer with the concentration of ozone remaining constant.
However satellite data indicated a large hole in the ozone layer over Antarctica. The main process which was responsible was found to be catalytic destruction of ozone by atomic halogens. The main source of these atomic halogens are Chlorofluorocarbons (CFC), Hydrochlorofluorocarbons (HCFC) and Chlorofluorobromine. These gases are used as refrigerants, solvents, propellants and foam-blowing agents. They are very stable and are inert in lower atmospheric regions but get destroyed when exposed to UV rays resulting in release of atomic halogens. This destruction of ozone layer by atomic halogen takes place through the following processes as outlined below.
CF2Cl2 + UV Radiations → CF2Cl + Cl
This free chlorine atom then acts as a catalyst for the following reactions.
Cl + O3 → ClO + O2
ClO + O → Cl + O2
O3 + O → 2O2
The chlorine is thus free to repeat after this two-step cycle. On an average, a single chlorine atom is able to react with 100,000 ozone molecules before it is removed from the catalytic cycle. This fact plus the amount of chlorine released into the atmosphere yearly by chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) demonstrate how dangerous CFCs and HCFCs are to the environment.
Stratospheric ozone is highly beneficial as it protects the living organisms on the Earth's surface from harmful UV radiations of the sun. Ozone is continuously formed and removed in the stratosphere and thus there is an apparent equilibrium in the ozone layer with the concentration of ozone remaining constant.
However satellite data indicated a large hole in the ozone layer over Antarctica. The main process which was responsible was found to be catalytic destruction of ozone by atomic halogens. The main source of these atomic halogens are Chlorofluorocarbons (CFC), Hydrochlorofluorocarbons (HCFC) and Chlorofluorobromine. These gases are used as refrigerants, solvents, propellants and foam-blowing agents. They are very stable and are inert in lower atmospheric regions but get destroyed when exposed to UV rays resulting in release of atomic halogens. This destruction of ozone layer by atomic halogen takes place through the following processes as outlined below.
CF2Cl2 + UV Radiations → CF2Cl + Cl
This free chlorine atom then acts as a catalyst for the following reactions.
Cl + O3 → ClO + O2
ClO + O → Cl + O2
O3 + O → 2O2
The chlorine is thus free to repeat after this two-step cycle. On an average, a single chlorine atom is able to react with 100,000 ozone molecules before it is removed from the catalytic cycle. This fact plus the amount of chlorine released into the atmosphere yearly by chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) demonstrate how dangerous CFCs and HCFCs are to the environment.
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