Definition:
The fragile shield of ozone is been damaged by chemicals
released on earth. The main chemicals that are depleting stratospheric ozone
are chlorofluorocarbons which are used in refrigerators, aerosols, and as
cleaners in many industries, and halons, which are used in fire extinguishers.
The damage is caused when these chemicals release highly reactive forms of
chlorine and bromine .Other
ozone-depleting substances (ODS), include hydro chlorofluorocarbons (HCFCs),
and volatile organic compounds (VOCs)
Causes of Ozone Layer Depletion:
CFC's
accounts for almost 80% of the total depletion of ozone. Other ozone-depleting substances
(ODS), include hydro chlorofluorocarbons (HCFCs), and volatile organic
compounds (VOCs) ODS
are relatively stable in the lower atmosphere of the Earth, but in the
stratosphere, they are exposed to ultraviolet radiation and thus, they break
down to release a free chlorine atom.
This free chlorine atom reacts with an ozone molecule (O3), and forms chlorine monoxide (ClO), and a molecule of oxygen. Now, ClO reacts with an ozone molecule to form a chlorine atom, and two molecules of oxygen. The free chlorine molecule again reacts with ozone to form chlorine monoxide. The process continues, and this results in the depletion of the ozone layer.
This free chlorine atom reacts with an ozone molecule (O3), and forms chlorine monoxide (ClO), and a molecule of oxygen. Now, ClO reacts with an ozone molecule to form a chlorine atom, and two molecules of oxygen. The free chlorine molecule again reacts with ozone to form chlorine monoxide. The process continues, and this results in the depletion of the ozone layer.
Possible Effects of Ozone Depletion
As ozone depletes in the stratosphere, it forms a 'hole' in the layer. This hole enables harmful ultraviolet rays to enter the Earth's atmosphere. Ultraviolet rays of the Sun are associated with a number of health-related, and environmental issues:
Impact on Humans
Skin cancer: Exposure to ultraviolet rays poses an increased risk of developing several types of skin cancers, including malignant melanoma, basal and squamous cell carcinoma.
Eye damage: Direct exposure to UV radiations can result in photokeratitis (snow blindness), and cataracts.
Immune system damage: Effects of UV rays include impairment of the immune system. Increased exposure to UV rays weakens the response of the immune system.
Accelerated aging of skin: Constant exposure to UV radiation can cause photo allergy, which results in the outbreak of rash in fair-skinned people.
Other effects: Ozone chemicals can cause difficulty in breathing, chest pain, throat irritation, and hamper lung functioning.
Effects on Amphibians
As ozone depletes in the stratosphere, it forms a 'hole' in the layer. This hole enables harmful ultraviolet rays to enter the Earth's atmosphere. Ultraviolet rays of the Sun are associated with a number of health-related, and environmental issues:
Impact on Humans
Skin cancer: Exposure to ultraviolet rays poses an increased risk of developing several types of skin cancers, including malignant melanoma, basal and squamous cell carcinoma.
Eye damage: Direct exposure to UV radiations can result in photokeratitis (snow blindness), and cataracts.
Immune system damage: Effects of UV rays include impairment of the immune system. Increased exposure to UV rays weakens the response of the immune system.
Accelerated aging of skin: Constant exposure to UV radiation can cause photo allergy, which results in the outbreak of rash in fair-skinned people.
Other effects: Ozone chemicals can cause difficulty in breathing, chest pain, throat irritation, and hamper lung functioning.
Effects on Amphibians
Some of the effects are mentioned below:
1.Hampers growth and development in larvae
2.Changes behavior and habits
3.Causes deformities in some species
4.Decreases immunity. Some species have become more vulnerable to diseases and death
5.Retinal damage and blindness in some species
Effects on Marine Ecosystems
1.Hampers growth and development in larvae
2.Changes behavior and habits
3.Causes deformities in some species
4.Decreases immunity. Some species have become more vulnerable to diseases and death
5.Retinal damage and blindness in some species
Effects on Marine Ecosystems
In
particular, plankton (phytoplankton and bacterioplankton) are threatened by
increased UV radiation. Marine phytoplankton play a fundamental role in both
the food chain as well as the oceanic carbon cycle. Plankton play an important
role in converting atmospheric carbon dioxide into oxygen. Ultraviolet rays can
influence the survival rates of these microscopic organisms, by affecting their
orientation and mobility. This eventually disturbs and affects the entire
ecosystem.
Impact on Plants
In some species of plants, UV radiation can alter the time of flowering, as well as the number of flowers.
Plant growth can be directly affected by UV-B radiation. Despite mechanisms to reduce or repair these effects, physiological and developmental processes of plants are affected.
Learning Activity:
Impact on Plants
In some species of plants, UV radiation can alter the time of flowering, as well as the number of flowers.
Plant growth can be directly affected by UV-B radiation. Despite mechanisms to reduce or repair these effects, physiological and developmental processes of plants are affected.
Learning Activity:
Q1. What is the name of a common
Man- made substance that causes ozone depletion?
a.
TLC b. CFC
c. DDT
d. MCC
Q2.
Where is the majority of Ozone found in the atmosphere?
a.
Thermosphere b. Troposphere
c. Mesosphere
d. Stratosphere
Q3. What type of harmful radiations
is blocked by ozone?
a.
Radiowaves b. Infrared
c. Ultraviolet
d. X-rays
Q4. Between what heights is the
ozone layer found in the atmosphere?
a.
2-3 km b. 0-1km
c. 19-30 km
d. 70-80 km
