Essay On Ozone Depletion

ozone layer is a spherical layer surrounding the earth. It is mainly lie in the

lower portion of the stratosphere from about 20 to 30 kilometers above the

earth. Ozone layer is very important for the earth because it provide a protection

against UV (Ultraviolet) radiation of the sun so it is described as the shield of the

earth.

The science of ozone depletion

The depletion of ozone layer became a major environmental problem by the

middle of the last century after the discovery of CFCs which has been damaging

our natural shield since its discovery till the current moment. Due to the

importance of this matter there have been an international consensus on the

science of ozone depletion has. The scientific community issues periodic

reports on the science of ozone depletion. Over 300 scientists worldwide

drafted and reviewed the most recent analysis.

Formation of the ozone layer “Chapman Cycle”

Oxygen molecules normally consist of two atoms at the surface of the earth. At

many kilometers above the earth there is a high level of UV radiation and this

lead to photo-dissociating the Oxygen molecules after absorbing ultraviolet

photon whose wavelength is shorter than 240 nm. Every oxygen molecule is

being dissociated into two free atoms.

ℎ��

→ �� + �� (Reaction 1)

��2

Because these free atoms are not stable and highly reactive they have a

tendency to make bonds with Oxygen molecules in the presence of a catalyst

(M) to form the triatomic Oxygen which is known as “Ozone”.

��

→ ��3 (Reaction 2)

�� + ��2

The Ozone molecules are rapidly dissociated again with UV radiation into both

Oxygen gas and atomic Oxygen.

ℎ��

→ �� + ��2 (Reaction 3)

��3

Oxygen gas molecules start over to spli...

... middle of paper ...

...ause ODS work just as catalysts in the process of ozone

depletion so they remain in the ozone layer for a long time.

Consequences of ozone layer depletion

A depleted ozone shield allows more UV radiation to reach the ground, which is

very dangerous because it leads to:

1- The widening ozone hole in Antarctica may lead to melting the glaciers

which can flood a great area of the earth.

2- Very dangerous diseases such as: Skin cancer, cataract problems, DNA

damage, changes in immune system, increasing incidences of eye

diseases and blindness moreover many other health problems.

3- Excessive heat from the sun due to this Ozone hole is a major contributor

to the global warming.

4- Field and greenhouse studies have shown that growth and

photosynthesis are negatively affected by enhanced UV-B radiation in

some tree species such as the loblolly pine.