Stratospheric Ozone Depletion

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ODPs of Selected Compounds Compound ODP CFC-11 (CFCl 3 ) 1.0 CFC-113 (CCl 2 FClF 2 ) 0.8 CCl 4 CFBr 3 1.20 12 CH3 CCl3 0.12 HCFC-22 (CF2 HCl) 0.055 CH 3 Cl 0.02 CH 3 Br 0.64
CFC substitutes • The main strategy has been to explore the suitability of hydrochlorofluorocarbons – The Cl and/or F substituents lend HCFCs some of the desirable properties of CFCs (e.g. low reactivity, fire suppression, good insulating and solvent characteristics, boiling point suitable for use in refrigerator cycles) – The presence of C-H bond reduces the tropospheric lifetime significantly • HCFCs are only transitional CFC substitutes
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 34 and 35: Active Cl species can rapidly yield
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

Stratospheric Ozone Depletion

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