Stratospheric Ozone Depletion

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Chlorofluorocarbons (CFCs) • CFCs is the abbreviated form of ChloroFluoroCarbons, a collective name given to a series of compounds containing chlorine, fluorine and carbon atoms. Examples: CFCl 3 , CF 2 Cl 2 , and CF 2 ClCFCl 2 . • Related names – HCFCs: Hydrochloroflorocarbons, halocarbons containing hydrogen atoms in addition to chlorine, fluorine and carbon atoms. – HFCs: hydroflorocarbons, halocarbons containing atoms of hydrogen in addition to fluorine and carbon atoms. – Perhalocarbons: halocarbons in which every available carbon bond contains a haloatoms. – Halons: bromine-containing halocarbons, especially used as fire extinguishing agents.
Chlorine atom (Continued) Termination reactions for Cl Cl . + CH 4 ClO . + NO 2 + M Reservoir species CH 3 . + HCl Stable in the stratosphere Removed from air by precipitation when it migrates to the troposphere ClONO 2 + M Relatively unreactive but can regenerate reactive species upon suitable conditions ClONO 2 + hvClO + NO 2 ClONO 2 + hvCl + NO 3
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: Chlorine atom Sources: Photolysis o
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
Page 50 and 51: ODPs of Selected Compounds Compound

Stratospheric Ozone Depletion

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