Ozone is an allotropic form of oxygen in which three atom form one molecule. It has a pungent smell. It is naturally present in the air after a thunder storm. It is produced by a silent discharge of electricity. It is used commercially for sterilizing water, bleaching, purifying air, etc. Ozone is a very powerful oxidizing agent. It is a blue gas. It is present in both the troposphere and the stratosphere, with tropospheric ozone accounting for about 10 per cent of the total ozone column.
In the troposphere, ozone becomes harmful to all the living forms. In troposphere, it is a constituent of photo chemical smog. It is normally considered to be a pollutant irritating to eyes and respiratory tissues, and harmful to plants.
In contrast, in stratosphere, ozone is an essential component of the earth/atmosphere system because of its ability to protect the biosphere from excess ultra violet radiation.
The amount of ozone accumulated in the upper atmosphere is called “Ozone Layer”. This layer fluctuates as much as 30% from day to day, since the formation of Ozone results of a series of dynamic physical and chemical processes. Ozone owes its existence to the impact of ultra violet radiation on Oxygen molecules in the upper atmosphere with the main production taking place in the tropical stratosphere where radiation levels are high. Oxygen molecule normally consists of two atoms. In the lower atmosphere they retain the configuration. At the energy levels by emitting sunrays directly associated with the ultra violet radiation in the upper atmosphere these molecules split apart to produce atomic oxygen.
Before long these free atoms combine with the available molecule oxygen to create triatomic oxygen, which is also called as “Ozone”. The reaction is reversible. The ozone molecule may break down again into its original components – molecular oxygen and atomic oxygen – as a result of further absorption of ultra violet radiations combined with oxygen to be reconverted to the molecular form.
Advantage to Earth by Ozone Layer:
Ozone layer protects our Mother Earth from the powerful sunrays. The sunrays are very powerful and coupled with ultra violet radiation. Suppose, if there is no ozone layer, then the ultraviolet radiations emitted by the powerful sunrays directly reach the Mother Earth. The powerful sun rays coupled with ultra violet radiations would damage the entire biological, physical and chemical structure of the earth.
If there is no ozone layer, there would be no animals and plants. Every living organism would be destroyed by the powerful sunrays’ radioactivity. Thus ozone layer has been protecting us from the destruction and form ultra violet radiation.
Due to Ozone Zone, other mother earth is quite safe. If there is no Ozone Zone, there cannot be climate and climatic changes. There could be no rains. Because, the temperature on the surface on the earth increases to double to ten folds. In that heavy temperature, there could be no seasons, i.e. rainy, summer season and winter season. Only there can be summer with heavy temperatures, perhaps more than 100˚ centigrade to 1000˚ centigrade. In such a situation, our mother earth also will become as a mars plant. There is no question of possibility of existence of any living organisms on the earth.
There are several scientists, viz. Rodriguez, Crutzen, Fishman, Hammond, Maugh, etc. found that there is a considerable danger causing to the ozone layer by the human activities. Increased urbanization, industrialization, nuclear weapons, nuclear wastages, environmental pollution, etc., the ozone layer has been affected causing it to reduce its size year by year.
The decrease of width of the ozone layer, the decrease of ozone in stratosphere is called “Ozone Depletion”.
Causes of Ozone Depletion:
The date collected on stratospheric ozone showed that as far as backed 1950’s ozone levels were remained relatively stable and within the normal limits. However since 1970s the data has been showing that ozone levels are fluctuating and alarming degrading. The causes are several. Some of them are stated under:-
1. Modern Technology:
The modern Technology developments in warfare, computers, aviation, agriculture, lifestyle, etc. involve a variety of complex chemical compounds; both old new are the main reasons.
2. Nuclear Weapons, Nuclear Wastages, etc.:
Nuclear war, Supersonic transport, cruising in the stratosphere and agriculture techniques are also causing the damage to ozone layer. These are dependant upon Nitrogen-based chemicals. Fertilizers are also potential sources of increasing amounts of oxides of Nitrogen, a group of highly potential destroyers of ozone. Computer simulations suggested that following a major nuclear conflict 50-70 percent of the ozone layer might be destroyed mainly as a result of the synthesis of oxides of nitrogen from atmospheric oxygen and nitrogen at the high temperatures produced by the thermo nuclear explosions. Nuclear wastages thrown by the Nuclear Thermal Projects, and Nuclear Weapon Factories emit several noxious and hazardous substances it the environment. Example: Accident in Chernobyl Nuclear thermal Power Plant.
3. Hydrogen Oxides
It is found that hydrogen oxides are the most powerful ozone-destroying pollutants. These are produced in the atmosphere on the earth by thousands of chemical industries. Especially nitrogen-based industries emit hydrogen oxides in the environment. They reach the stratosphere and cause ozone depletion.
Chlorofluorocarbons, Bromoflurocarbons or Halons are continuously emitted into the atmosphere causing threat to ozone layer. CFCs are used in refrigeration and air-condition systems, propellants, polymers foams, etc. the use of refrigerators, air conditions etc. have been increasing in the world. Proportionately the release of CFCc is also increased.