Ozone Depletion

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Ozone Depletion
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The ozone layer is found in the stratosphere
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The ozone layer is in the stratosphere
Good up high! ?
Bad nearby! ?
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Ozone Layer is located in the stratosphere

• It protects the Earth from ultraviolet rays
  emitted by the sun.
• The wavelengths of ultraviolet radiation are
  absorbed by the ozone molecules.

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• Ozone absorbs
• uv-b radiation

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There is a natural cycle of formation and
depletion of ozone
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The depletion of the ozone layer has been big
news since the 1980s
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Sherwood Rowland, Mario Molina, Paul Crutzen
1995 Nobel Prize Winners for Atmospheric chemistry

• Whats the use of having developed a science
  well enough to make predictions if, in the end,
  all were willing to do is stand around and wait
  for them to come true? - Rowland

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Ozone Depletion

• Chlorofluoro carbons (CFCs) and other
  halogenated hydrocarbons contribute to the
  destruction of stratospheric ozone.
• Just one chlorine and bromine atom can catalyze
  the destruction of 100,000 ozone molecules

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Halogenated hydrocarbons

• CFCs (chlorofluorocarbons)
• Other harmful compounds include HCFCs, halons,
  methyl bromide, carbon tetrachloride, NO2, and
  methyl chloroform.
• CFCs were used in refrigerators, home insulation,
  aerosols, plastic foam, and throwaway food
  containers.
• Note Both chlorine and bromine from halogenated
  hydrocarbons deplete the ozone.

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Ozone depletion

• Chlorine and bromine-containing compounds (CFCs)
  are stable in the troposphere, but degraded under
  intense ultraviolet light in stratosphere.
• UV rays release the chlorine (Cl) from the CFCs,
  causing ozone (O3) to be depleted
• The chlorine and bromine atoms catalyze the
  destruction of stratospheric ozone.

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The ozone hole is a seasonal decrease in
stratospheric ozone at the polar regions during
spring A polar vortex isolates the stratosphere
above the poles in the arctic and antarctic
winters. The CFCs are concentrated in this
vortex. The chlorine atoms break off the CFCs
in the spring when the sun hits them.
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Research..
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Measurements of the ozone above Antarctica
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A comparison of arctic and Antarctic ozone
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Is this showing the ozone over Antarctica or the
Arctic?
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Effects of UV Radiation to humans

• Linked to skin cancer a deadly cancer
• Linked to cataracts on the lens of the eye
  causing blindness

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Uv light changes DNA in the skin, this can cause
tumors, and can lead to cancer
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UV light and skin cancers

• Melanoma

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Cataracts
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Effects of UV Radiation on biological
productivity

• Disruption of plant cycles and food chains
• May limit plant growth and change plant form, how
  nutrients are distributed,
• Lowers levels of surface phytoplankton in the
  ocean
• Damages the base of the ocean food chain

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Productivity of phytoplankton
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Research
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How to Ozone depletion is reduced

• Limiting the use of CFCs is difficult
• Ban the production and use of CFCs
• Use CFC substitutes such as HCFCs and HFCs
• Recycling refrigerants
• Alternatives to gas-blown plastics
• Alternative propellants
• Alternatives to methyl bromide, a fungicide

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The role of the UNEP

• Montreal Protocol (1987) 30 countries agreed to
  reduce CFC, also encouraging other countries.
• Effectiveness As a result of the Protocol,
  ozone-depleting gases have been reduced in recent
  years. Expected to be completely reduced by 2050.
• Countries are required to report annually on
  their consumption and emission of ozone depleting
  substances to the UNEP
• London Convention (1990)
• Copenhagen (1992)

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http//www.nasa.gov/centers/jpl/images/content/156
227main_ozone-20060830-graph-browse.jpg
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Without the Montreal Protocol, skin cancers would
have been much worse
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It will take time for the ozone layer to recover.
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Bibliography

• "Data Reporting and Access." The Ozone
  Secretariat - Home. 05 Mar. 2009
  lthttp//ozone.unep.org/Data_Reporting/gt. "Data
  Reporting and Access.
• " The Ozone Secretariat Home. 05 Mar. 2009
  lthttp//ozone.unep.org/Data_Reporting/gt.
• NOAA Earth System Research Laboratory. 05 Mar.
  2009 lthttp//www.esrl.noaa.gov/csd/assessments/200
  2/qandas16.pdfgt.
• "Ozone Depletion - Causes." Oracle ThinkQuest
  Library. 05 Mar. 2009 lthttp//library.thinkquest.o
  rg/26026/Environmental_Problems/ozone_depletion_-_
  causes.htmlgt.
• "Ozone Depletion - Effects." Oracle ThinkQuest
  Library. 05 Mar. 2009 lthttp//library.thinkquest.o
  rg/26026/Environmental_Problems/ozone_depletion_-_
  effects.htmlgt.
• "The Ozone Depletion Pheno... - The Problem." 05
  Mar. 2009 lthttp//www.beyonddiscovery.org/content/
  view.page.asp?I77gt.
• "Science - Ozone Depletion." NOAA Stratospheric
  Ozone Webpage. 05 Mar. 2009 lthttp//www.ozonelayer
  .noaa.gov/science/o3depletion.htmgt.
• "UNEP Environmental Effects of Ozone Depletion
  Executive Summary." Socioeconomic Data and
  Applications Center. 05 Mar. 2009
  lthttp//sedac.ciesin.org/ozone/docs/UNEPsummary96.
  htmlgt.