1. Ozone

2. Ozone – Two Faces Troposphere – Bad Ozone Stratosphere – Good Ozone
Pollution
Photochemical smog
Eye irritant
Stratosphere – Good Ozone
Blocks some UV radiation
Hole caused by depletion due
to ODC’s (Ozone Depleting Chemicals)

3. O2 + uv  O + O
O + O2 O3
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4. Natural destruction of the ozone..…
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5. Continuous
cycle!

6. UVA – very little is blocked by the ozone layer
Ozone production in the stratosphere is important as it blocks some UV radiation
UVA – very little is blocked by the ozone layer
UVB – partially blocked by the ozone layer, causes burning & skin cancer

8. Anthropogenic disruption of the stratospheric ozone cycle is caused by ……

9. Production of…….
Ozone Depleting Chemicals (ODCs)

10. Ozone Depleting Chemicals (ODCs)
Chlorofluorocarbons (CFCs)
(most common)
Halons
Methyl Bromide
fumigant used in agriculture to control pests
Carbon Tetrachloride (CCl4)

13. Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and leaving
CFCl2.
Sun Cl Cl
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again. C Cl F
UV radiation Cl Cl O O
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
The chlorine atom attacks
an ozone (O3) molecule, pulling an oxygen atom
off it and leaving
an oxygen
molecule (O2). Cl Cl O O O O O
The chlorine
atom and the
oxygen atom join
to form a chlorine
monoxide molecule (ClO) Cl O O O

15. A single chlorine atom removes about 100,000 ozone molecules before it is taken out of operation by other substances

16. Ozone Thinning Winter = no sunlight at poles
Air in the polar vortex can get very cold -80C
Special clouds called Polar Stratospheric Clouds form
PSCs are crucial for ozone loss to occur
Since there is no sunlight, the air within the polar vortex can get very cold

17. The frozen crystals that make up polar stratospheric clouds provide a surface for the reactions that free chlorine atoms in the Antarctic stratosphere

18. The ozone hole builds up over the winter months, peaking at around September and breaking up again by December, this data set from 2005
                               July
                          August
                               September
           October
                               November
December

19. September 21-30, 2006 the average area of the ozone hole was the largest ever observed, at 10.6 million square miles

20. Why should we be concerned about more UV B radiation reaching the surface of Earth?

21. effects of more UV radiation
Skin cancer such as melanoma
Cataracts and sun burning
Suppression of immune systems
Lower crop yields
Reduction in the growth of ocean phytoplankton
Deeper penetration into bodies of water
Degradation of paints and plastic material

22. melanoma
matrix.ucdavis.edu/tumors/tradition/ gallery-ssmm.html

23. cataract
cataract.asp

24. Solutions?

25. an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion.
Five revisions
1990 (London)
1992 (Copenhagen)
1995 (Vienna)
1997 (Montreal)
1999 (Beijing)

26. Hopefully closed by end of the century 