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The visible part of solar radiation can be detected by the human eye, which enables us to see. The heat that we feel, not just from sunlight, but also from fire, heating devices, etc., is due to infrared radiation. The ultraviolet radiations from sunlight can cause skin burns and darkening of skin, while prolonged exposure can lead to skin cancer. These radiations have to be prevented from entering the Earth’s surface. Their entry is prevented by the ozone layer present in the stratosphere.
In recent years, the ozone layer has depleted rapidly. This is mainly due to an increased concentration of chlorine in the stratosphere. One atom of chlorine can destroy around 100,000 molecules of ozone, which results in its depletion.
Consequences of Ozone depletion
Ozone depletion has occurred widely in the stratosphere, but is more prominent over the Antarctic region. The depletion of ozone in this region has created an ozone hole.
It causes skin darkening, skin cancer, ageing, and corneal cataracts in human beings. It can even result in the death of many phytoplanktons.
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ozone hav 3 oxygen atom ( refer txt hw itz formed ).its poisonous in atmosphere bt act as protective layer in atmosphere from UV rays !
As a "shield", it prevents certain wavelengths of UV from passing.As an occasional event (lightning), it destroys odorous compounds.With chronic (long term) exposure. it damages / destroys plants ability to respire, and animal's lung tissue.Ozone is used by marigolds to fight root parisitism, and by white blood cells to fight infection.
In aquaria, ozone plays an important part in purification of water (reactivation of natural bromine), with similar damage to fish's gill structures under high ozone concentrations or long term exposure.
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If this ozone becomes depleted, then more UV rays will reach the earth. Exposure to higher amounts of UV radiation could have serious impacts on human beings, animals and plants, such as the following:
- Damage to marine life:
- In particular, plankton (tiny organisms in the surface layer of oceans) are threatened by increased UV radiation. Plankton are the first vital step in aquatic food chains.
- Decreases in plankton could disrupt the fresh and saltwater food chains, and lead to a species shift in Canadian waters.
- Loss of biodiversity in our oceans, rivers and lakes could reduce fish yields for commercial and sport fisheries.
- Animals:
- In domestic animals, UV overexposure may cause eye and skin cancers. Species of marine animals in their developmental stage (e.g. young fish, shrimp larvae and crab larvae) have been threatened in recent years by the increased UV radiation under the Antarctic ozone hole.
- In domestic animals, UV overexposure may cause eye and skin cancers. Species of marine animals in their developmental stage (e.g. young fish, shrimp larvae and crab larvae) have been threatened in recent years by the increased UV radiation under the Antarctic ozone hole.
- Materials:
- Wood, plastic, rubber, fabrics and many construction materials are degraded by UV radiation.
- The economic impact of replacing and/or protecting materials could be significant.
- Harm to human health:
- More skin cancers, sunburns and premature aging of the skin.
- More cataracts, blindness and other eye diseases: UV radiation can damage several parts of the eye, including the lens, cornea, retina and conjunctiva.
- Cataracts (a clouding of the lens) are the major cause of blindness in the world. A sustained 10% thinning of the ozone layer is expected to result in almost two million new cases of cataracts per year, globally (Environment Canada, 1993).
- Weakening of the human immune system (immunosuppression). Early findings suggest that too much UV radiation can suppress the human immune system, which may play a role in the development of skin cancer.
- Adverse impacts on agriculture, forestry and natural ecosystems:
- Several of the world's major crop species are particularly vulnerable to increased UV, resulting in reduced growth, photosynthesis and flowering. These species include wheat, rice, barley, oats, corn, soybeans, peas, tomatoes, cucumbers, cauliflower, broccoli and carrots.
- The effect of ozone depletion on the Canadian agricultural sector could be significant.
- Only a few commercially important trees have been tested for UV (UV-B) sensitivity, but early results suggest that plant growth, especially in seedlings, is harmed by more intense UV radiation.
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