Ozone Depletion - Download as PowerPoint by K8lvGu

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									The ozone layer is found in the stratosphere
The ozone layer is in the stratosphere




Good up high! 




     Bad nearby! 
◦ It protects the Earth from ultraviolet rays emitted by
  the sun.

◦ The wavelengths of ultraviolet radiation are
  absorbed by the ozone molecules.
Ozone
absorbs
uv-b
radiation
There is a natural cycle of formation
and depletion of ozone
The depletion of the ozone layer has
been big news since the 1980’s
Sherwood Rowland, Mario Molina,
Paul Crutzen– 1995 Nobel Prize
Winners for Atmospheric chemistry




   “What’s the use of having developed a science
    well enough to make predictions if, in the
    end, all we’re willing to do is stand around
    and wait for them to come true?” - Rowland
   Chlorofluoro carbons (CFC’s) 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
   CFC’s (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.
   Chlorine and bromine-containing
    compounds (CFC’s) 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.
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 CFC’s are concentrated in
this vortex.

The chlorine atoms break off the
CFC’s in the spring when the
sun hits them.
Research..
Measurements of the ozone above
Antarctica
A comparison of arctic and Antarctic
ozone
Is this showing the ozone over Antarctica or the
Arctic?
   Linked to skin cancer – a deadly cancer

   Linked to cataracts on the lens of the eye
    causing blindness
Uv light changes DNA in the skin,
this can cause tumors, and can
lead to cancer
UV light and skin cancers
                       Melanoma
Cataracts
   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
Productivity of
phytoplankton
Research
   Limiting the use of CFC’s is difficult
   Ban the production and use of CFC’s
   Use CFC substitutes such as HCFC’s and
    HFC’s
   Recycling refrigerants
   Alternatives to gas-blown plastics
   Alternative propellants
   Alternatives to methyl bromide, a fungicide
   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)
http://www.nasa.gov/centers/jpl/images/content/156227main_ozone-
20060830-graph-browse.jpg
Without the
Montreal
Protocol, skin
cancers would
have been
much worse
It will take time for the ozone layer to recover.
   "Data Reporting and Access." The Ozone Secretariat - Home. 05 Mar. 2009
    <http://ozone.unep.org/Data_Reporting/>. "Data Reporting and Access.
   " The Ozone Secretariat – Home”. 05 Mar. 2009
    <http://ozone.unep.org/Data_Reporting/>.
   NOAA Earth System Research Laboratory. 05 Mar. 2009
    <http://www.esrl.noaa.gov/csd/assessments/2002/qandas16.pdf>.
   "Ozone Depletion - Causes." Oracle ThinkQuest Library. 05 Mar. 2009
    <http://library.thinkquest.org/26026/Environmental_Problems/ozone_depletion_
    -_causes.html>.
   "Ozone Depletion - Effects." Oracle ThinkQuest Library. 05 Mar. 2009
    <http://library.thinkquest.org/26026/Environmental_Problems/ozone_depletion_
    -_effects.html>.
   "The Ozone Depletion Pheno... - The Problem." 05 Mar. 2009
    <http://www.beyonddiscovery.org/content/view.page.asp?I=77>.
   "Science - Ozone Depletion." NOAA Stratospheric Ozone Webpage. 05 Mar. 2009
    <http://www.ozonelayer.noaa.gov/science/o3depletion.htm>.
   "UNEP Environmental Effects of Ozone Depletion: Executive Summary."
    Socioeconomic Data and Applications Center. 05 Mar. 2009
    <http://sedac.ciesin.org/ozone/docs/UNEPsummary96.html>.

								
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