Earths Atmosphere

1
Earths Atmosphere
Strahler, A. and Strahler, A., 2004. Physical
Geography. Wiley, NY.
2
Chapman Mechanism

• O2 UV ? O O
• O O2 m ? O3 m heat
• O3 UV ? O O2
• O O3 ? 2O2 heat

3
Catalytic Reactions

• X O3 ? XO O2
• XO O ? X O2
• Catalysts include OH, H, NO, and Cl.

4
Three Types of Ultra Violet

• UV-A (320 400 nm)
• Negligibly absorbed by O3 layer.
• UV-B (290 320 nm)
• Mostly absorbed by O3 layer.
• UV-C (lt 290 nm)
• Totally absorbed by O3 layer.

5
Effects of Excessive Exposure to UV Radiation

• Skin cancer (basal and squamous cell carcinoma
  and melanoma).
• Cataracts.
• Immune system depression.
• ? photosynthesis, water use efficiency, leaf area
  and yield.
• ? growth of marine phytoplankton, zooplankton,
  and fish larvae.

6
Chlorofluorocarbons

• First synthesized by Thomas Midgley Jr. in 1930.
• Non-toxic, non-flammable, inexpensive,
  non-odorous and versatile.
• Uses include coolant, foam production, aerosol
  propellant, and solvent.

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Uses of CFCs 1986
5 Aerosol propellant miscellaneous uses
12 Solvent for metal electronics
22 Unallocated production
4 Sterilization of medical equipment
19 Mobile air conditioning
9 Refrigeration stationary air conditioning
28 Production of plastic foam insulation
8
Global CFC Use 1986
14 Other developing countries
2 China and India
14 Warsaw Pact countries
70 Industrial countries
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Other Ozone Depleting Substances

• Carbon tetrachloride.
• Methyl chloroform.
• Halon.
• Methyl bromide.

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Process of Depletion

• Photodissociation
• CF2Cl2 UV ? CF2Cl Cl
• Destruction
• Cl O3 ? ClO O2
• Regeneration
• ClO O ? Cl O2
• Destruction
• ClO O3 ? ClO2 O2

11
Termination Reactions

• Termination agent nitrogen dioxide
• NO2 ClO ? ClNO3
• Termination agent methane
• CH4 Cl ? HCl CH3
• HCl OH ? Cl H2O

12
Nitric Oxide and Ozone

• Liberation of chlorine
• NO ClO ? NO2 Cl
• Regeneration
• NO2 visible light ? NO O
• Catalytic decomposition of ozone
• NO O3 ? NO2 O2
• NO2 O ? NO O2

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Anthropogenic Sources of Nitrogen Oxides

• Use of nitrogenous fertilizers.
• High altitude aircraft.
• Detonation of nuclear weapons.

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Springtime Ozone Data
http//www.cmdl.noaa.gov/ozwv/ozsondes/spo/ozdob.h
tml
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Antarctica
http//www.travellerspoint.com/map.cfm?countryAnt
arctica
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Ice Crystal Reactions

• Stable chlorine transformed into reactive forms.
• Termination agents neutralized.

17
Restoration Factors

• Ozone rich tropical air migrates poleward.
• Local production of ozone occurs.
• Icy stratospheric clouds disappear.

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Path to the Protocol

• 1976 Manufacture of CFC aerosol spray cans for
  non-essential uses banned by several countries.
• 1977 Coordinating Committee on the Ozone Layer
  established by UNEP.
• 1981 Decision to develop a global convention.
• 1985 Vienna Convention on Substances that
  Deplete the Ozone Layer signed.

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Montreal Protocol I

• Signed in September 1987.
• Initially 50 ? production and consumption of
  CFCs and halons by 1999.
• Ban on import from non-signatory countries.

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Montreal Protocol II

• 10 year grace period for low income countries.
• Monitored by international scientific panel.
• In effect 1 January 1989.
• Baseline year is 1991.

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Amendments

• London in 1990, Copenhagen in 1992, Vienna in
  1995, Montreal in 1997.
• 100 ? in production and consumption of CFCs and
  halons by 2000.
• Other ODS added carbon tetrachloride, methyl
  chloroform, HCFCs, HBFCs, methyl bromide.
• International fund established.

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Alternatives to ODSRequirements

• Perform same function.
• Reasonable cost.
• Without major equipment modifications.
• Environmentally benign.
• Non-toxic to workers and consumers.

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Alternatives to ODSExamples

• HCFCs.
• Ammonia.
• Propane.
• Bioact EC7.
• CF3I.

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Efficiency in ODS Use

• Use of solvents in closed system with recycling
  of captured CFCs.
• Plugging leaks in cooling systems.
• Suction systems and carbon adsorption to recover
  CFCs.

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Methyl Bromide Exemptions 2005
http//www.pan-uk.org/pestnews/pn64/pn64p18.htm
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Factors for the Success of the Montreal Protocol

• Clear ongoing science.
• Negotiations.
• Funding for low income countries.
• Industry recognized advantage of developing
  alternatives.
• Alternatives.
• Licensing system.
• Annual statistical data.