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Unit 7.1 Minidoc: The Hole in
the Ozone Layer
The minidocumentary deals with the importance of understanding
the chemistry of the environment. The causes for the formation
of the hole in the ozone layer are discussed.
Video program cues: 00:30-4:354:35
Introducing ozone
"Ozone is actually a very simple molecule.
It is made up of three oxygen atoms, and it has a chemical
formula of O3, but it plays a very complicated
role in the earth’s atmosphere. It can either be harmful
or beneficial to humans, depending on where in the atmosphere
it resides."
Dr. Laurie Geller
National Academy of Science
Links
- This page has links to dozens of resources on the science
of ozone depletion. Some of the sources are intended
for a technical audience, but there is more than enough
here for students and teachers.
- This is NASA’s
Total Ozone Mapping Spectrometer (TOMS) home page with
a link to visual images of the ozone hole from 2000 and
2001 compared, as well as other current ozone images and
data.
Reading
Pirjola, L. (2000)' Local Atmospheric Chemistry and Ozone
Model (LACOM), 'Journal of Chemical Education, Vol.
77, No. 12, pp: 1650-1653.
CFCs in the atmosphere
"When they created CFCs, they purposely
made them very strong, because that made them very useful
for industrial processes. But that also made them different
in that they basically survive in the lower atmosphere for
quite a long time, and unlike most molecules, which get
washed out, they hang out there for a long time and eventually
make their way up to the stratosphere. When CFC molecules
get to the upper atmosphere, they get exposed to strong
UV radiation, that has enough energy to break the chemical
bonds of the molecule, and finally the CFC molecules meet
their destruction in the atmosphere. The problem is that
what you are left with is a free chlorine atom, which is
very reactive. The basic reaction is between chlorine and
ozone, and in the next step a lone chlorine atom is regenerated;
such that one chlorine atom may destroy up to 100,000 ozone
molecules."
Dr. Laurie Geller
National Academy of Science
Link
- A glossary of ozone depletion terms from
EPA.
The hole in the ozone Layer
"There have been many efforts to design
alternatives [to the repair of the ozone hole]. We have
a whole group working on looking for compounds which decompose
before they reach the ozone layer."
Dr. Laurie Geller
National Academy of Science
"There have been lots of ideas about
how to fix the chemistry of what is going on in the atmosphere.
The only way that we know that will work and is safe, is
to stop releasing these CFCs into the atmosphere."
Dr. Carlos Gonzalez
Carnegie Mellon University
Link
- Complete background, including the chemistry, on ozone
depletion, from the University
of Cambridge. Includes illustrations, a glossary and
links to other sources. Ideal for student use.
Reading
Zurer, P. (1999)' Slow Road to Ozone Recovery, 'Chemical
and Engineering News, Vol. 77, No. 17, pp: 8-9.
| Proceed
to Unit 7.2 |
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