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Ozone layer depletion
- 1. OZONE LAYER DEPLETION ANJUSHA.M B.Ed. PHYSICAL SCIENCE 2018-2020 batch P.K.M.COLLEGE OF EDUCATION, MADAMPAM
- 2. INTRODUCTION The ozonelayer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it. This natural sunscreen, known as Earth's ozone layer, absorbs and blocks the majority of the sun's UV radiation. Without this barrier in place, all of the radiation would reach Earth, damaging the DNA of plants and animals, like us humans. Within days of the ozone layer's disappearance, many plants would die.
- 3. Ozone layer Ozoneis formed in the atmosphere when energetic ultra violet radiation dissociates molecules of oxygen into separate oxygen atoms. Free oxygen atoms can recombine to form oxygen molecules but if a free oxygen atom collides with an oxygen molecule, it joins up , forming ozone. Over the Earth’s surface, the ozone layer’s average thickness is about 300 Dobson Units or a layer that is 3 millimeters thick.
- 5. Ozone layer depletion ozonelayer depletion consist of two related events observed since the late 1970s:a steady lowering of about four percent in the total amount of ozone in Earth’s atmosphere, and a much larger springtime decrease in stratospheric ozone around Earth’s polar regions. The latter phenomenon is reffered to as the ozone hole.
- 6. Causes The ozone layerdepletion is a major concern and is associated with a number of factors. The main causes responsible for the depletion of the ozone layer are listed below: Chlorofluorocarbons Chlorofluorocarbons or the CFC are the main cause of ozone layer depletion. These are released by soaps, solvents, spray aerosols, refrigerators, air-conditioners, etc. The molecules of chlorofluorocarbons in the stratosphere are broken down by the ultraviolet radiations and release chlorine atoms. These atoms react with ozone and destroy it.
- 7. Unregulated RocketLaunches The unregulated launching of rockets result in much more depletion of ozone layer than the CFCs do. Nitrogenous Compounds The nitrogenous compounds such as NO2, NO, N2O. Natural Causes Sun-spots and stratospheric winds. But it does not cause more than 1-2% of the ozone layer depletion. The volcanic eruptions.
- 8. Ozone-Depleting Substances Sources Chlorofluorocarbons(CFCs) Refrigerators, air-conditioners, solvents, dry- cleaning agents, etc. Halons Fire-extinguishers Carbon tetrachloride Fire extinguishers, solvents Methyl chloroform Adhesives, aerosols Hydrofluorocarbons Solvent cleaning, fire extinguishers, solvent cleaning
- 9. Effects of ozonelayer depletion For humans, direct exposure to UV rays can lead to: •Skin cancer such as melanoma, basal cells or squamous cell carcinomas. •Premature aging and other skin damage. •Eye damage such as cataract problems, photokeratitis or snow blindness. •Damage or weak the immune system. In plants, ozone layer depletion can cause problems such as changes on how nutrients are distributed, on developmental timing phases and on secondary metabolism.
- 10. Prevention •Buying and usingrecycled products. •Saving of energy: • Change your light bulbs to CFL • Use less heat and air conditioning • Buy energy-efficient products • Use less hot water • Use the “off” switch •Reducing fossil fuels emissions by using public transport. •Plant a tree (or two!). •Spread awareness and encourage others to make a change.
- 11. Conclusion 2019 Ozone Holeis the Smallest on Record Since Its Discovery. Abnormal weather patterns in the upper atmosphere over Antarctica dramatically limited ozone depletion in September and October, resulting in the smallest ozone hole observed since 1982, NASA and NOAA scientists reported today. We all have the responsibility to save our Earth for the next generation.