Ozone layer is depleted by reactions involving a variety of compounds reaching the Stratosphere. The important once are chlorofluorocarbons (CFCs), Halos ( a combination of Bromine and Iodine), water vapour, nitrous oxide, methyl bromide, dichloromethane, carbon tetrachloride etc.
Chlorine nitrate lias reduced catalytic cycles of CI and NOx for 03 destruction, lowering the overall O, depletion rates it is estimated that for each chlorine released 100,000 molecules of ozone are destroyed.
2. Nuclear explosions produce a large quantity of NOx, which directly a stratosphere. It is found that nuclear tests conducted by the USSR and the reduced 03 concentration by about 4 percentages. Such reduction definitely food production
The loss of stratospheric ozone is now an established fact and there is genuine c about its impact on humankind. Only recently have researchers turned their attention to out how humans, vegetation and aquatic ecosystems may be affected by ozone depletion, effects are –
1. Direct exposure to ultraviolet radiation can damage the human immune system, cataracts and increase the incidence of skin cancer.
2. Studies with some 200-plant species have shown almost two-thirds of them too susceptible. They include members of the bean, pea and cabbage families. Among visible harmful effects of exposure to high doses of ultraviolet radiation were red – leaf size, stunted growth, poor seed quality and increased susceptibility to weeded and pests.
3. A study by marine biologists in the seas around Antarctica showed that higher level ultraviolet radiation reduces algal productivity by 6-12 per cent. It also causes dam to various forms of aquatic larvae and other organisms.
4. The long-term effects of such changes could be catastrophic. For example, in waters reduced productivity of photo plankton could affect krill-the tiny like creatures that lie at the bottom of the Antarctic food chain. Krill would in affect fish, birds and marine animals including seals and whales that feed on them.
5. The global warming, depletion of ozone layer are some of the immediate threats environment. The average global temperature during the 1980s exceeded that of any? Other decade since reliable temperature recording began a century ago and 1990 was the warmest year on record.
The elevated concentration of greenhouse gases is responsible for rise in temperature. Troposphere 03 is a greenhouse gas so it is also responsible for rise in temperature. This could lead to complex climatic changes including the rise in sea level. CFCs (Chlorofluorocarbons) are the dominant sources of chlorine in the stratosphere.
It may be observed that from global point of view C02 is the most important greenhouse gas, which constitutes 60-65 percentages in total heat trapping followed by methane. The contribution of CFCS in heat trapping is less but these gases also cause depletion of ozone layer along with others.
The protective shield of ozone is depleting. Thus radiation absorbed by ozone layer is partly re- emitted the earth’s surface. The effect is that a phenomenon known as “Greenhouse effect” heats up the earth’s surface.