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Ozone depletion
- 1. OZONE LAYER DEPLETION AHole Story A Hole Story
- 2. he Ultraviolet SpectrumheUltraviolet Spectrum UV light: 100 to 400 nm UV spectrum – 4 regions o Far UV: 100 – 200 nm o UV – C : 200 – 280 nm o UV – B : 280 – 315 nm UV light: 100 to 400 nm UV spectrum – 4 regions o Far UV: 100 – 200 nm o UV – C : 200 – 280 nm o UV – B : 280 – 315 nm o UV – A : 315 – 400 nm Radio IR Visible Light UV X-Rays UV-A UV-B UV-C Far UV 400nm 100nm DNA damaging range 200nm300nm λ
- 3. Ultraviolet Radiation 230-280 nmdamages nucleic acids Stops reproduction of cells by breaking apart the DNA bonds Ozone production peaks at 185nm Ozone absorbance and destruction at 200-320nm Ozone destructionOzone formation
- 4. UV ozone generation anddestruction: equilibrium O2 + hυ185 2O. O. + O2 + M O3 + M O3 + hυ254 O2 + O. Equilibrium between production and destruction
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- 6. Ozone Formation andDepletion
- 8. The catalyzed cycleof stratospheric ozone production and destruction 1. hυ + O2 2O. 1. O. + O2 O3 1. O3 + X O2 + OX 4. OX + O. O2 + X X could be Cl from a CFC
- 10. Halogen catalysis ofozone destruction
- 11. Halogen removal from atmosphere Cl+ CH4 HCl + CH3 . ClO + NO2 ClONO2 Both HCl and ClONO2 inactive: rain out Br + O3 BrO + O2 Br + CH4 HBr + CH3 . HBr can photolytically provide Br again Halons and CH3Br provide Br
- 12. List of ozone depletingsubstances Table 8.13 Masters http://www.epa.gov/ozone/ods.html Ozone Depleting Substances Halons
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- 14. Strong circulatory winds around Antarcticaisolate the air in the lower and middle stratosphere Ice crystals form in vortex Antarctic Vortex during Winter
- 15. Antarctic Reactions Winter reactions Polarvortex: -90 o C Ice clouds ClONO2 + H2O HOCl + HNO3 HOCl + HCl Cl2 + H2O Spring reactions Cl2 + hυ 2 Cl in early spring Cl + O3 ClO + O3 destructive loop HNO3 + Cl ClONO2 in photocatalysis
- 16. Global total ozonechange
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- 20. Studying Ozone Layerchanges
- 22. The Nobel Prizein Chemistry 1995 "for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone" The Netherlands USA USA Max-Planck-Institute MIT, USA Department of Chemistry, for Chemistry Mainz, Germany Cambridge, MA University of California Irvine, CA, USA 1933 - 1943 - 1927 - Paul J. Crutzen Mario J. Molina F. Sherwood Rowland
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- 30. Ozone Hole Growth: October27, 1980 September 21, 2006 September 17, 2009
- 32. Ozone hole sizein recent years
- 34. EARTH IS INOUR HANDS WE CAN SAVE IT. THINK AS A HUMAN, BE A HUMAN
- 35. A Proud Presentation by HARSHAVARDHANBABU ThankYou Powered by ©BVG STUDIOS, All rights reserved.
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