Stratospheric Ozone Depletion

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Active Cl species can rapidly yield Cl atoms when light is available • Active Cl species include Cl2 , HOCl, and ClNO2 • Active Cl species readily photolyze to yield Cl atoms when daylight returns in the springtime. Cl2 + hv 2Cl HOCl + hv HO + Cl ClNO2 + hv Cl + NO2
Polar ClOx cycle to remove O 3 • Polar regions: lack of O atom because of low sun elevation The ordinary ClOx cycle is not operative since it requires the presence of O atom. • Under polar atmospheric conditions, the reaction sequence to remove O3 is as follows Cl + O3 ClO + O2 ClO + ClO ClO-OCl ClO-OCl + hv ClOO + Cl ClOO + hv Cl + O2 2 [Cl + O3 ClO + O2 ] Net of the last FOUR reactions: 2O3 + hv 3O 2
Page 1 and 2: Environmental Chemistry Part 2 Atmo
Page 3 and 4: The ozone layer
Page 5 and 6: Ultraviolet protection by ozone The
Page 7 and 8: Typical ozone column values • Tot
Page 9 and 10: Ozone formation and destruction in
Page 11 and 12: Prediction by Chapman theory vs. Ob
Page 13 and 14: The important catalysts for stratos
Page 15 and 16: Chlorine atom Sources: Photolysis o
Page 17 and 18: Chlorine atom (Continued) Terminati
Page 19 and 20: The two-sided effect of NOx • NOx
Page 21 and 22: Numbering system for CFCs and HCFCs
Page 23: The discovery of the ozone hole •
Page 26 and 27: Features of the ozone hole • Ozon
Page 28 and 29: Polar vortex • The polar vortex i
Page 30 and 31: Why do PSCs occur at heights of 15-
Page 32 and 33: PSCs promote the conversion of inor
Page 36 and 37: How does the polar ClOx cycle stop?
Page 38 and 39: Denitrification by PSCs enhances po
Page 40 and 41: Summary of the roles played by PSCs
Page 42 and 43: Schematic of photochemical and dyna
Page 44 and 45: Does ozone hole occur in the north
Page 46 and 47: Summary on ozone hole (Continued)
Page 48 and 49: What influences ODP? • Lifetime i
Page 50 and 51: ODPs of Selected Compounds Compound

Stratospheric Ozone Depletion

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