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1. The Layers of the Atmosphere
One fact about the universe revealed in the verses of the
Qur'an is that the sky is made up of seven layers.
"It is He Who created everything on the earth for you and
then directed His attention up to heaven and arranged it
into seven regular heavens. He has knowledge of all
things."
(The Qur'an, 2:29)
"Then He turned to heaven when it was smoke. In two
days He determined them as seven heavens and revealed,
in every heaven, its own mandate."
(The Qur'an, 41:12)
The verse 11 of Sura Tarik in the Qur'an, refers to the
"returning" function of the sky.
"By Heaven with its cyclical systems."
(The Qur'an, 86:11)
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2. Ozone Layer
Depletion
RABIA AZIZ
BS-III Chemistry
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3. 8/27/2017 RABIA AZIZ 3
WHAT IS OZONE?
Ozone Profile:
Ozone: Trioxygen Molecule
Chemical Formula: O3.
Color: Pale Blue Gas
Odour: Pungent Smell
Chemical Property: Powerful
oxidant
Formation: Ozone Is Formed From
Dioxygen By The Action Of
Ultraviolet Light And Also
Atmospheric Electrical Discharges.

4. OZONE LAYER
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5. 8/27/2017 RABIA AZIZ 5
Ozone Layer Discovery:
The ozone layer was
discovered in 1913 by the
French physicists Charles
Fabry and Henri Buisson.
Its properties were
explored in detail by the
British meteorologist G.
M. B. Dobson.

6. What and Where Is The Ozone
Layer?
The ozone layer or ozone shield is a region of Earth's stratosphere
that absorbs most of the Sun's ultraviolet (UV) radiation. Ozone
Makes Up Only 0.6 Ppm Of The Atmosphere.
The ozone layer is found in the lower portion of the stratosphere
from about 20 to 30 km above earth’s surface.
It’s thickness varies seasonally and geographically.
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The total
mass of
ozone
produced per
day over the
globe is
about 400
million metric
tons.
The global mass
of ozone is
relatively
constant at about
3 billion metric
tons, meaning the
Sun produces
about 12% of the
ozone layer each
day.

7. Incoming Solar
energy…
Percentage
Reflected 35%
Absorbed by atm
(ozone)
18%
Scattered to Earth
from blue sky
10%
Scattered to Earth
from clouds
15%
Radiation going
directly to Earth
surface
22%
100%
Ozone is the only major atmospheric
constituent that absorbs significantly
between 210 and 290 nm.
Why is the Ozone layer
Important?
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8. Chapman Cycle,
Ozone–Oxygen Cycle,
Natural Production of Ozone–
Oxygen
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9.  The oxygen get photolyzed by U.V.rays to form oxygen radical.
O2 + ℎν → 2 O•
 The oxygen radical then react with molecular oxygen and forms ozone
molecule (O3).
O• + O2 → O3
 Ozone absorbs UV-rays and breaks into diatomic oxygen molecule and
oxygen atom.
 At the same time ozone gets reduce to oxygen by reacting with oxygen
radical.
O3 + ℎν(240–310 nm) → O2 + O
 So, ozone is constantly get created and destroyed by Chapman cycle,
which is a natural process.
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10. Ozone depletion
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11. OZONE DEPLETION
“Decrease in concentration of ozone and
thinning of ozone layer is called Ozone
depletion.”
Sources:
1. Ozone Depleting Substances
2. Volcanic Eruption
3. polar stratospheric clouds
(PSCs)
4. Broadcasting
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12. THEIR DISOVERY, LOCATION, AND
THE PROBLEMS THEY CAUSE
The Hole
In the Ozone layer
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13. When was the hole discovered?
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Scientists from British Antarctic Survey
began monitoring ozone.
Scientists discovered that since the mid
1970s ozone values over Halley and
Faraday research stations had been
steadily dropping when the sun
reappeared each spring.
Antarctica
Where are the holes?

14. Why Antarctica?
Chemical reactions on polar
stratospheric clouds (PSCs) in
the cold Antarctic
stratosphere caused a
massive, though localized and
seasonal, increase in the
amount of chlorine present in
active, ozone-destroying
forms.
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These clouds are only formed when there are
very low temperatures, as low as −80 °C. In such
conditions the ice crystals of the cloud provide a
suitable surface for conversion of unreactive
chlorine compounds into reactive chlorine
compounds, which can deplete ozone easily.
HCl + ClONO2 Cl2 + HNO3
Cl2 + hv 2Cl

15. What is Arctic Hole?
The situation is not as severe in the warmer Arctic
region, where the vortex does not persist quite as
long. Studies have shown that ozone levels in this
region have declined between 4 and 8 percent in
the past decade. Volcanic eruptions, such as that of
Mount Pinatubo in the Philippines in 1991, inject
large quantities of dust-sized particles and sulfuric
acid aerosols into the atmosphere. These particles
perform the same catalytic function as the ice
crystals at the South Pole. As a result, the Arctic
hole is expected to grow larger during the next few
years.
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16. Do You Know?
AM broadcast 1.45MHz causes ozone
depletion
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Radio waves have been proven to effect electron precipitation, a
known depletion mechanism of stratospheric ozone, for nearly 30
years! It can also be seen in the global temperature graph from when
broadcast first began in 1909. They have satellite observations of
direct heating high above areas of major broadcast activity as well as
an increase in lightning activity and lightning induced electron
precipitation. Power line harmonic radiation has also been observed in
magnetospheric electron precipitation.

17. What are Ozone Layer Depleting
Substances?
Ozone Depleting Substances
Substances that cause the depletion of the ozone layer are called Ozone Depleting
Substances (ODS). The different ODS are
⦁ CFCs
⦁ Halons
⦁ Methyl Chloroform
⦁ Carbon Tetrachloride
⦁ Hydrofluorocarbons (HCFCs)
• Bromochloromethane
• Methyl Bromide
• Hydrobromofluorocarbons
Sources: They are found in Refrigerators, Cleaning agents, sprays, Pesticides, Air
conditioners, car emissions, fire extinguishers etc.
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18. What does ODP mean in
Environmental?
• Ozone Depleting Potential: A measure of the
capability of a particular chemical to destroy
ozone, measured against CFC-11 which has an
ozone-depleting potential of 1.
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19. 8/27/2017 RABIA AZIZ 19
Sources of Stratospheric Chlorine
Chlorine act as a catalyst in ozone depletion
An individual chlorine atom can destroy as many as 10,000 different ozone
molecules before the chlorine atom is removed from the stratosphere by other
reactions.

20. Ozone Depletion Process BY CFC
• UV radiation breaks off a chlorine atom from a CFC
molecule.
• The chlorine atom attacks an ozone molecule , breaking it
apart and destroying the ozone.
• The result is an ordinary oxygen molecule and a chlorine
monoxide molecule (ClO).
• The chlorine monoxide molecule (ClO) is attacked by a
free oxygen atom releasing the chlorine atom and forming
an ordinary oxygen molecule .
• The chlorine atom is now free to attack and destroy
another ozone molecule. One chlorine atom can repeat this
destructive cycle thousands of times.
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21. Ozone Depletion Process BY
Nitrogen Oxides
Another group of compounds that can destroy stratospheric ozone are the
nitrogen oxides, generally denoted as NOx. (Examples of NOx are NO
and NO2.) These compounds come from the exhausts of high-altitude
supersonic aircraft and from human and natural activities on Earth.
Solar radiation decomposes a substantial amount of the other nitrogen
oxides to nitric oxide (NO), which participates in the destruction of
ozone as follows:
• O3 O2 + O
• NO + O3 NO2 + O2
• NO2 + O NO + O2
Overall: 2O3 3O2
In this case, NO is the catalyst and NO2 is the intermediate. Nitrogen
dioxide also reacts with chlorine monoxide to form chlorine nitrate:
ClO + NO2 ClONO2
Chlorine nitrate is relatively stable and serves as a “chlorine reservoir,”
which plays a role in the depletion of the stratospheric ozone over the
North and South Poles.
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22. EFFECTS OF OZONE
LAYER DEPLETION
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23. Melting Of Ice
Ozone hole leads to melting of ice of
Antarctica, increase in sea land other
harmful effects on it’s environment
level.
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24. • 1) Effect on Human Health:
*Human immune system is said to be severely affected through the
ultraviolet radiations that the human body come in contact with.
* One of the causes of blinding-cataracts is also another consequence
of this.
*There are also skin cancers, skin burns and premature aging which are
the subsequent results.
2) Harmful to the fauna:
*The increased exposure to UV Radiation is also harmful to the animals.
This may result in the extinction of several species too.
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Problems the hole causes Biological

25. Problems the hole causes
• 4) Degradation of materials:
Just like the living organisms, ultraviolet
radiations can also be termed as harmful to
the materials like wood, fabrics and plastic
as they can suffer degradation.
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Environmental
5. UV kills many crops by destroying the
bacteria that Retain nitrogen on the roots of
many plants.
6. Phytoplankton form the foundation of
aquatic food webs, and production of them is
negatively impacted by UV light
7. UV radiation has been found to cause
damage to the early developmental stages of
fish, shrimp, crab, amphibians and other
animals

26. Solution
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27. Suggestion-1
An intense effort is under way to find CFC substitutes that are
effective refrigerants but not harmful to the ozone layer. One
of the promising candidates is hydrochlorofluorocarbon 134a, or
HCFC-134a (CH2FCF3). The presence of the hydrogen atoms
makes the compound more susceptible to oxidation in the lower
atmosphere, so that it never reaches the stratosphere.
Specifically, it is attacked by the hydroxyl radical in the
troposphere:
• CH2FCF3 + OH CHFCF3 + H2O
The CHFCF3 fragments react with oxygen, eventually decomposing
to CO2, water, and hydrogen fluoride that are removed by
rainwater. Although it is not clear whether the CFCs already
released to the atmosphere will eventually result in catastrophic
damage to life on Earth, it is conceivable that the depletion of
ozone can be slowed by reducing the availability of Cl atoms.
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28. Suggestion-2
Indeed, some chemists have suggested sending a
fleet of planes to spray 50,000 tons of ethane
(C2H6) or propane (C3H8) high over the South
Pole in an attempt to heal the hole in the ozone
layer. Being a reactive species, the chlorine atom
would react with the hydrocarbons as follows:
• Cl + C2H6 HCl + C2H5
• Cl + C3H8 HCl + C3H7
The products of these reactions would not affect
the ozone concentration.
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29. Suggestion-3
A less realistic plan is to rejuvenate the ozone
layer by producing large quantities of ozone
and releasing it into the stratosphere from
airplanes. Technically this solution is feasible,
but it would be enormously costly and it
would require the collaboration of many
nations.
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30. • There are several ways we can stop this depletion too.
1) Using public transport or carpooling as an alternative
2) Always buy energy efficient appliances to reduce the
release of CFC’s.
3) Plant more trees. Try maintaining a garden around your
house in order to reduce the amount of ultraviolet
radiations, since trees can absorb most of it.
4) Stop the excessive usage of insecticides and pesticides.
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31. World Ozone Day
• 16 September as a World
Ozone Day
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