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Ozone Depletion at the Poles

What is ozone layer. Ozone is a bluish, reactive gas, with chemical formula O3. Nearly 90% of the Earth's ozone concentrates in the stratosphere. These ozone forms a shielding layer around the Earth which prevents excessive ultraviolet rays from entering the Earth.Excessive ultraviolet rays is ha

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Ozone Depletion at the Poles

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    1. Ozone Depletion at the Poles

    2. What is ozone layer Ozone is a bluish, reactive gas, with chemical formula O3. Nearly 90% of the Earths ozone concentrates in the stratosphere. These ozone forms a shielding layer around the Earth which prevents excessive ultraviolet rays from entering the Earth. Excessive ultraviolet rays is harmful to health as they can cause skin cancer and suppress human immune systems.

    3. Ozone depletion The amount of ozone in the stratosphere is decreasing due to certain chemicals released in human activities, such as chlorofluorocarbons (CFCs). CFC is used as cooling sources in air-conditions and refrigerators. Nowadays, CFCs can be replaced by other chemicals which have less negative effect on the ozone layer.

    4. Chemical reactions CCl3F + UV Light => CCl2F + Cl CCl2F2 + UV Light => CClF2 + Cl The chlorine atoms formed in the above reactions readily depletes ozone via a chain reaction: Cl + O3 => ClO + O2 ClO + O => Cl + O2

    5. Ozone depletion at the poles Ozone depletion occurs mainly at the poles. The extremely cold conditions and darkness and isolation facilitate the above reaction. Ozone depletion is the worst at Antarctica. An ozone hole appears over Antarctica and is increasing each year.

    6. The ozone hole

    7. Ozone depletion at the poles However, the situation in Arctic is not that serious because the air is not as cold as Antarctic air.

    8. Ozone depletion at the poles By international agreement, most countries have halted the production of CFCs. But an ozone hole occurs every year because of CFC molecules that remain in the atmosphere.

    9. References Ozone hole, World Book, 2008 ed. http://www.science.org.au/nova/004/004key.htm http://www.gsfc.nasa.gov/topstory/20010917arctictemps.html http://www.research.noaa.gov/climate/t_ozonelayer.html http://it.geocities.com/allfonsit/ozlain.html http://www.atm.ch.cam.ac.uk/tour/part1.html http://www.doc.ic.ac.uk/~kpt/terraquest/va/ecology/ecology.html#A

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