I.  Molecule or Report of the Week:  Ozone Depletion

(text p. 340-343)

OZONE DEPLETION

In 1987, an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer was signed by many nations. The Protocol required the that CFC production would be reduced to one-half of the 1986 levels by 1998. Based upon a growing understanding of the cause of the ozone hole and the potential for global ozone depletion, approximately 100 nations in 1990, agreed to a complete ban on the use of CFCs in 2000.

Brief explanation for the ozone hole. The inactive forms of chlorine in hydrochloric acid and chlorine nitrate can react with ice crystals and nitric acid trihydrate crystals in very high cold clouds in the stratosphere over Antarctica. This reaction on the surface produces diatomic chlorine molecule and nitric acid, which quickly dissociate into chlorine atoms in the sunlight of the Antarctic spring. The reactive chlorine atoms start a cycle of destruction of ozone. Chlorine atoms react with ozone to make chlorine monoxide molecules and oxygen molecules. Chlorine monoxide reacts with atomic oxygen to make diatomic oxygen and reactive chlorine atoms to cycle over again. Since there are few gaseous water molecules and virtually no nitrogen dioxide molecules to react with and inactivate the chlorine, the reactive chlorine builds up as chlorine monoxide and recycles to chlorine atoms which continue to destroy more ozone.  For more details see Part III. of the Ozone Tour.

Caused by synthesis and use of chlorofluorocarbons (CFCs)

General set of ozone links from EPA
Simple graphic of Ozone depletion
Ozone Hole Tour - Cambridge University, UK - four pages linked - excellent explanations and graphics.
General information on ozone science - a general review
Ozone Meets CFC on YouTube 2min,
Ozone Depletion - Specific brief Questions and Answers on ozone depletion only.
Ozone's Problem -with Polar Stratospheric Clouds and chemical reactions and explains the ozone hole
Ozone Hole Watch - NASA - click on all of the links on the top menu - Gives maps for August - December of each year.

Animated Graph of Ozone concentrations over Antarctica for a complete year - can click on latest years, keep watching into September/October/November.  Watch the graph go to lower Dobson values - this is the ozone hole with low ozone  concentration.
Graph of Ozone Concentrations - 1967-present

Ozone maps - South Pole 1979-1997
Ozone maps - North Pole 1979-1998
Archive of ozone hole maps - See bottom of page to select dates.
Controversy surrounding ozone depletion - This is a brief review of two opposing papers on several questions concerning ozone depletion.
Some myths about ozone - about the nonexistence of the ozone problem - a series of links.

Ozone Depletion Report:

The following information should be included in the report:

What is the ozone (formula)?  What is the purpose of the ozone is the stratosphere?  How is ozone formed?  How does ozone block UV radiation? (last two questions should be both words and chemical formula equations)
What are CFC’s and how do they effect the ozone (equations and words)?

Continue your report with three more specific questions 1abc.  A series of questions relating to Satellite Images of the Ozone Hole.   Keep reading and going down for the actual final questions to be included in the ozone report.

Visualization of the Ozone Hole:  Ozone Maps  - Please say WOW when you see these!

Probably the easiest site to get ozone images is Ozone Watch.  This is useful from August to December.  Click on the top menu “historical” to get other years.  Go to the bottom of the page to select dates.  You can get a whole series of maps on one page for a month. Click on the month under the globe to go back to Sept, August, July.  The color contour coding shows low ozone concentrations measured in Dobson units of dark blue, purple, violet colors. Low Dobson units mean low ozone concentrations. This site can be used for up to date or back to 1979.  

TOMS: EARTH PROBE TOMS HOME Page. Another site that is available to access contour color maps of the ozone concentrations in various locations in the world. The longest archived series is from a satellite carrying TOMS - Total Ozone Mapping Spectrometer. Various satellites have provided coverage over the years.  Near the bottom of the page you can make selections of various dates.
For the whole globe choose Output menu  - global image - PNG
For the South Pole -choose Out put menu - south pole image - PNG
then Select Satellite coverage - should be OMI - 2004 -present
Finally select a date.
TOMS: EARTH PROBE TOMS HOME Page.

Note: use the above two sites to find answers to the above questions and those that follow. It is also possible to get the year 1997 in GIF animation of polar views. This may play slowly.

QUES. 1a: What day(s) does the ozone hole begin(probably sometime in August or early September) and end (probably near end of November or early December) ? For the Antarctica Ozone Hole give the approximate date and lowest concentration of ozone, in Dobson units, observed. These dates do not have to be exact, just trying to get some approximate dates. Tell how you know and what colors for Dobson units that you are observing.

First concentrate on the Antarctica, look at a series of images starting with July 1 and look at one or two dates every month until December. You can use the 2005 dates up to the present, but you may need to go back and get some of the dates for November and December to find when the ozone hole ends. Which months show evidence of the "ozone hole"? Evidence of the ozone hole is when you begin to see contours of blue, purple, pink, or dark purple. See the color bar for the Dobson Units near the bottom of the graphic. In July and August you will see a black spot on the south pole - this is NOT the ozone hole, but only a lack of data due to the fact that the satellite can not work when it is completely dark at the poles as it is in the winter which is July and August. Try to refine the dates for the optimal duration of the ozone hole. Try some dates that are about 15 days apart. You only need to look through one year of data.

QUES. 1b: Comment about the ozone hole growing in area size and the minimum concentration as the years have increased. Do these graphs show that that ozone levels in the ozone hole are getting better, worse, or staying the same?

Series of monthly ozone maps.
Yearly Ozone Hole Progress - daily up date on graphs of concentration and size compared to earlier years.  Need to click on the small graphs to get a larger graph.

QUES. 1c: Based upon the below analysis, where would you NOT want to live on a permanent basis because of increased exposure to UV due to lower ozone concentrations and possible increased risk of skin cancer? Closer to poles or closer to the equator? Northern U.S. or Southern U.S.? 

From Earth Probe TOMS, Near the bottom of the page you can make selections of various dates.
For the whole globe choose Output menu  - global image - PNG
For the South Pole -choose Out put menu - south pole image - PNG
then Select Satellite coverage - should be OMI - 2004 -present
Finally select a date.  For this exercise pick some dates January, March, June.
Use the color contours to list the approximate ozone concentrations in Dobson units over three zones: near the equator, in the mid latitudes (North America/Europe/Asia) and polar regions. Is the distribution of ozone uniform over the surface of the globe? Explain. Be sure that you understand the color codes for the Dobson units.
Ozone levels at various latitudes.

U.V, Map of U.S. showing contours of where the most U.V . of the type that damages DNA is located. Lower numbers equals less U.V. equals more ozone overhead.  (Contrast aqua contour with purple or brown contour AND correlate that with the %per year cancer rate.
Also look at: UV Index - Country wide or can get specific for your zip code.  Lower numbers are better than higher numbers.  Lower number means more ozone to block the UV rays.
UV Exposure Maps

2. II.Content Questions A:
   

1. Types and sources of air pollutants (text chap 11)

 General Reference and Definition -  General Definitions

 A. Outdoor Air Pollution Sources - Photochemical Smog

Text p. 327-336

Photochemical Smog and Ground-Level Ozone - A brief Review

Photochemical Smog - brief with simple graphic
General Air Quality Index -includes 5 pollutants, ozone, particles, carbon monoxide, sulfur dioxide, and nitrogen oxide.
Photochemical Smog - explained with chemical equations.
Photochemical Smog - graphic

Nitrogen Oxides - NO, NO2, (N2O) - from synthesis of nylon and natural denitrification rxs.)

Nitrogen oxides

Volatile Organics (VOCs)- gasoline vapors, unburned hydrocarbons, industrial processes

VOC or unburned hydrocarbons
Ground level Ozone and VOC -

 Ozone - O3   (Text p. 337-339)

Ozone-Smog - Definition and graphic
Ozone: good up vs. bad nearby - Briefly explains the difference between ozone in the troposphere vs. the stratosphere.

Smog - How does it hurt? - Health Effects of ozone

Destructive ozone

What is smog - ground level ozone

Automobiles and Ozone - pdf file
Air Quality Index for Ozone - AQI

Animated Ozone Maps - Current daily maps for regions of the country (May - September)

Archive Maps for whole U.S. may select regions or cities

Try this one for June 23, 2005 - Midwest

QUES. 2:  Vehicle Pollution Calculator - Non Methane Hydrocarbons (NMH) = VOC, CO, NOx, Particulates
Report how much your car contributed in a year.

For each the following air pollutants:    nitrogen oxides, VOCs, Ozone,  describe each of the following: source or how made and then how they interact with each other and the sun to make photochemical smog with the production of ozone.  Use some chemical reactions as well as words of explanation.

Text p. 327-339 and internet links on above.

Suspended Particles  (Text p. 335-337)

Basics on particulates
Smog Pictures from China
Air Pollution in China

QUES. 3: Is ozone depletion of proven significance enough to warrant government regulation of CFC's? Give some specific chemicals (names or formulas and/or reactions)

Summarize the YES and NO positions to this question. Each student pick either YES or NO.

Controversy surrounding ozone depletion - This is a brief review of two opposing papers on several questions concerning ozone depletion.
Myth on CFCs -

QUES. 4: Will the the additional amount of UV exposure be significant to humans?

Summarize the YES and NO positions to this question. Each student pick either YES or NO.

Go about half way down to find this question.
Controversy surrounding ozone depletion - This is a brief review of two opposing papers on several questions concerning ozone depletion.  Scroll to the bottom half of the article.

UV Exposure Effects -
UV Index - Country wide or can get specific for your zip code.  Lower numbers are better than higher numbers.
Myth on Ozone and UV link -

QUES. 5: In the Oct. 19, 1997 issue of the Chicago Tribune the following editorial appeared:

"The Tribune reports (page 4, Oct. 11) that the ozone "hole" in the atmosphere is the same size as it has been for several years despite costly environmental regulations prohibiting the use of chlorofluorocarbons that destroy ozone. These CFCs had been used in refrigeration. The article goes on to report that a reduction of ozone can lead to skin cancer and cataracts.
On page 6 is a story about new costly environmental standards to reduce ozone pollution from Midwest coal burning power plants. While power plants to not emit ozone, they do emit nitrogen oxide and hydrocarbons that can form ozone - which is claimed to be "debilitating to the young, elderly, and anybody with respiratory problems." The new regulations will dramatically increase the electric power costs.
So, environmentalists have caused a significant increase in refrigeration costs to prevent the destruction of ozone, and now they want to further increase the cost of electric power to prevent the formation of ozone. Is it no wonder that they are completely losing public confidence?"

 Write a reply in the form of an editorial that could be understood by the general public that would clarify several points about ozone in this editorial. There are at least two misunderstandings that could be corrected in your reply. Give some specific chemicals (names or formulas and/or reactions)

 Reference if you missed it earlier: Ozone: good up vs. bad nearby - Briefly explains the difference between ozone in the troposphere vs. the stratosphere.  Click on the two main categories “Good up high” and “Bad nearby”

Smog - How does it hurt? - Health Effects of ozone

QUES. 6: "Air pollution (smog) is causing the ozone hole and increasing global warming". Many people will say this statement is true, but from what you have learned in this chapter, describe why this statement is completely false. Briefly summarize the molecules that are the causes of all three problems (smog, ozone hole, global warming) and briefly explain the definitions of each problem. 

Text Chap. 11

Content Questions B - shall precede the final issue debate question.  The issue question is given here to give context for the content questions.  Look further down for the start of the Content B questions.

DEBATE QUESTION: Should the United States and other countries in the Montreal Protocol ban the production and use of methyl bromide because it is an ozone depleting chemical? (As of 2005 the production of methyl bromide has been largely banned according to the treaty, however there are still many exceptions for the use in this country and others around the world. So perhaps the question could be rephrased to say banning ALL uses, including the exceptions.)

The instructor has divided the students into "YES" and "NO" groups for the purposes of the issue debate.

Option # 1 NO: Students ID's (1 - 7 & 14 - 20)

 Option # 2 YES: Students ID's ( 8 - 13 & 21 - 30)

INTRODUCTION:

Use of Methyl bromide in Agriculture:

Methyl bromide is a toxic pesticide that is injected into soil before planting strawberries, grapes, almonds and other crops (85% of its use).

It is also used to kill pests in stored and quarantine treatment of commodities, in agricultural shipments and in buildings. In this use, the methyl bromide is pumped as a gas into sealed containers or room containing various commodities which may include various fruits and vegetables. Some countries require this treatment before import or export of certain fruits or vegetables. For example, lumber from certain Asian countries is treated with methyl bromide to kill the long horned beetle which has infested some trees in the Chicago area.

Strawberries: Here are a couple of links to a site where methyl bromide is used as a soil fumigant before planting strawberries. Dave Peck of Manzanita Farms was kind enough to respond to one of our debate discussion forums. As a result, I asked him for some more information about the use of methylbromide in his operation. He wrote the following letter/essay in response:

Manzanita Farms - growing strawberries - look in particular at (B.) Soil Preparation

Essay Explaining the use of methyl bromide in growing strawberries - Dave Peck, Manzanita Farms - further info

Alternative to Methyl Bromide: A communication from Dave Peck, Nov. 21, 2002: "We have forsaken methyl-bromide for good, opting to use the chloropicrin and Telone 2 (Dow Chemical's "Inline") on 100% of our 300 acres this year. It is an economically reasonable alternative and works well with our berry variety.

Montreal Protocol on Ozone Depletion:

In 1987, an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer was signed by many nations. The Protocol required the that CFC production would be reduced to one-half of the 1986 levels by 1998. Based upon a growing understanding of the cause of the ozone hole and the potential for global ozone depletion, approximately 100 nations in 1990, agreed to a complete ban on the use of CFCs in 2000. Subsequently, in 1992, President George Bush ordered the complete halt to CFC production in the United States after December 31, 1995.  As time has progressed other bromide containing compounds were also included.

Debate on Future Restrictions of Ozone Depleting Chemicals

Montreal Protocol on Substances that Deplete the Ozone Layer
UNEP Supplement to the 1994 Assessments
"4. Summary
This synthesis report examines the scientific, technical, and economic implications for a range of scenarios of possible action that could be considered by the Parties to the Montreal Protocol. The report highlights that, from the scientific perspective of reducing the risks of future ozone depletion, key steps that the Parties may want to consider include:
* Insuring full compliance with the Montreal Protocol as amended in Copenhagen;
* Actions to reduce production and consumption of methyl bromide in non-Article 5(1) countries.
* Actions to collect and destroy existing CFC and halon stocks; and
* Actions to limit future growth in HCFCs and methyl bromide in Article 5(1) countries."

Optional Reference: For further information see:

The following contains the most definitive assessments and answers to questions about ozone depletion - fairly technical in nature but the Executive summary is somewhat readable.

Montreal Protocol - Ozone Depletion Assessment - 2006

"Twenty Questions and Answers About the Ozone Layer" - contains many links to good graphics and explanations.

3. III.Content Questions B:
   
   

See below for internet sites:

Ques. 7: What is methyl bromide?  List some of the specific uses for methyl bromide. Is methyl bromide a toxic chemical in its own right? Explain.

Ques. 8: How does methyl bromide get up into the stratosphere and what happens to it there in the presence of ultraviolet light?  In some cases, is there evidence that the methyl bromide never gets to the stratosphere because it is mostly absorbed in the soil?

Ques. 9: How do bromine atoms effect the ozone reactions? Be specific and give some word equations.  How does one bromine atom recycle and destroy hundreds of thousands of ozone molecules? Be specific and give some word equations.

Ques. 10: How strong is the evidence that bromine from methyl bromide causes depletion of the ozone layer?

Ques. 11: Some people do not believe that CFC's or bromine causes depletion of the ozone layer. Can you cite any evidence to support this side of the issue?

Ques. 12: Should methyl bromides be allowed to protect the food supply or banned to protect from skin cancers?

Ques. 13: Ethical:  Should all necessary actions to prevent ozone destruction be taken to protect future generations of people?  Should the protection of the environment be the highest priority - no matter what the costs?

Ques. 14: Ethical: Should food growers and importers suffer economic losses if methyl bromide is banned in the United States, but not in some other parts of the world?

Research Sites:
Please note that the resources do NOT specifically match the questions.  There may be some general headings that will help.

General Information on Ozone Depletion

Ozone Multimedia Tour
EPA Science of Ozone: Look especially at: Environmental Indicators - Ozone Depletion
Ozone Depletion - Wikipedia - full range of topics
Series of Graphics on Ozone Hole - Climate Prediction Center
Stratospheric Ozone Explanations
Methyl Bromide Page - EPA
Critical Use exemptions -  Various groups may petition for an exemption on the ban

Sites that support the ban of Methyl Bromide

Methyl Bromide Use Map in the U.S.
EPA methyl bromide home page
ARS Methyl bromide Research and Alternatives

Methyl Bromide Alternatives
Alternatives- EPA just a list

Sites that support the continued use of Methyl Bromide

Essay Explaining the use of methyl bromide in growing strawberries - Dave Peck, Manzanita Farms

Manzanita Farms - growing strawberries (look in particular at B. Soil Preparation)

Methyl Bromide Does Not Stick Around -
Oceans remove methyl bromide -

Alternatives to Methyl Bromide: Skip down to Introduction for reasons not to ban methyl Br

Rumors about the phaseout of methyl bromide - gives the rumor about why methyl bromide should not be banned and then gives an answer.

Critical Use exemptions -  Various groups may petition for an exemption on the ban

Methyl Bromide and Ozone - Solution: tax rather than ban

Loss of Methyl Bromide - Impact on the Strawberry Nursery Industry

1. IV.  Issue Question:
   

ISSUE DEBATE QUESTION: The original question was:  Should the United States and other countries in the Montreal Protocol ban the production and use of methyl bromide because it is an ozone depleting chemical?

(As of 2005 the production of methyl bromide has been largely banned according to the treaty, however there are still many exceptions for the use in this country and others around the world.)

So the question is now rephrased to say:   Should the United States and other countries in the Montreal Protocol ban ALL uses, including the exceptions, of methyl bromide?

The instructor has divided the students into "YES" and "NO" groups for the purposes of this issue question.

Option # 1 NO: Students ID's (1 - 7 & 14 - 20)

 Option # 2 YES: Students ID's ( 8 - 13 & 21 - 30)

The report should include the following:   Need to have four to six paragraphs.

What is methyl bromide and what is it used for (give at least two examples)?
What effect does methyl bromide have on the ozone layer?  How strong is this evidence?
What are some of the exemptions for continued use of methyl bromide?  Are there viable alternatives to the use of methyl bromide?  What is your overall answer to the question?

1. V.  Response or Ask a Question - respond or comment to someone else, or use General Questions to ask a general question that the Prof or others might answer.  Extra responses earn extra credit (1 pt/ques. up to 2 points)
   
   Response Format:  What or why is something interesting?  Then add a new perspective or viewpoint.  Needs to be longer than one sentence.
   
   Ask a question Format:  Give a little background of what you already know or what is your interest, then add what you already know, then finally ask your question.
   

Charles E. Ophardt, Professor of Chemistry, Elmhurst College, Elmhurst, IL 60126, charleso at elmhurst.edu, Copyright 2009

Content Question A

Ques. No.      Student ID #

Ques. 2       4, 9, 12, 16, 21, 26         

Ques. 3       5, 10, 17, 22, 27

Ques. 4       1, 7, 8, 11, 18, 24, 28

Ques. 5       2, 6, 13, 15, 19, 29

Ques. 6      3, 14, 20, 23, 25, 30