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JSS3: BASIC SCIENCE - 1ST TERM

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  1. Family Traits | Week 1
    6Topics
    |
    1 Quiz
  2. Environmental Hazards I - Soil Erosion | Week 2
    3Topics
  3. Environmental Hazards I - Flooding | Week 3
    5Topics
    |
    1 Quiz
  4. Environmental Hazards II - Bush Burning | Week 4
    4Topics
  5. Environmental Hazards II - Deforestation | Week 5
    4Topics
    |
    1 Quiz
  6. Environmental Hazards III - Desertification | Week 6
    4Topics
    |
    1 Quiz
  7. Environmental Hazards III - Description of the Ozone Layer and its Location in the Atmosphere | Week 7
    3Topics
    |
    1 Quiz
  8. Drug and Substance Abuse | Week 8
    4Topics
    |
    1 Quiz
  9. Resources from Living Things | Week 9
    4Topics
  10. Resources from Non-Living Things | Week 10
    2Topics
    |
    1 Quiz
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Scientists’ studies of the atmosphere, show that the ozone layer of the atmosphere has been gradually depleting (that is reducing) since 1975.

Polluting activities of human beings lead to the release of dangerous gases into the atmosphere, such as chlorofluorocarbon, CFC, carbon dioxide, oxides of nitrogen, and radiation, which is an invisible and extremely dangerous form of pollution.

Chlorofluorocarbons (CFCs) are found in various applications such as in air-conditioning, refrigeration, deodorants, insecticides,blowing agents in plastic formation, insulations and packing materials, propellants in aerosol cans, and as solvents.

The manner in which chlorofluorocarbon destroys the ozone layer is briefly described as follows:

1. Chlorine from CFC reacts with ozone (O3) forming chlorine monoxide (Cl.O) and oxygen (O2)

Cl + O3 →  Cl.O + O2.

2. When the molecule of chlorine monoxide (Cl.O) meets another molecule of oxygen (O) it breaks up, releasing chlorine (Cl), which can “destroy” another molecule of ozone (O3), creating the catalytic cycle of chlorine.

Cl.O + O = Cl + O2.

The chlorine atoms keep cycling through the process of breaking up ozone, and it has upset the balance of the ozone system. This reaction happens over and over again, allowing one chlorine atom to destroy many ozone molecules.

depletion of the ozone layer

Effects of Depletion of the Ozone Layer:

The depletion of the ozone layer leads to the following consequences.

1. Global Warming or Climate Change: This is an increase in the world’s temperature. A measurable increase in the average temperature of Earth’s atmosphere, oceans, and landmasses.

2. Health Hazards: Increase in skin cancer among human beings and other organisms leading to death.

3. Damage to Plankton: Plankton are tiny animal and plant life of a body of water. The marine food web is also affected.

4. Damage to Crops: Plants are sensitive to enhanced ultraviolet rays, and this brings about reduced growth, and subsequently a reduction in crop yields.

5. Greenhouse Effect: This is a process by which thermal radiation, from a planetary surface, is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone, and some artificial chemicals such as chlorofluorocarbons (CFCs)

Since part of this re-radiation is back towards the surface, the temperature is higher than it would be. This refers to the capacity of certain gases in the atmosphere to trap heat emitted from the earth’s surface, thereby insulating and warming the planet. 

The most important greenhouse gas is CO2, and it is a major cause of the greenhouse effect and global warming.

Green house effect
Greenhouse Effect.

6. Ice Melting and Flooding: The heat intensity is causing ice melting which results in flooding; due to flooding, houses are destroyed and thousands of lives are lost.

7. Material Damage: Exposure to ultraviolet rays is a significant cause of degradation of materials, for example, roofing sheets.

Control Measures Against Ozone Depletion:

Fossil fuels such as gasoline, diesel, natural gas, etc., when used, emit harmful greenhouse gasses such as CO, CO2, SO2, etc.  Reducing greenhouse gases, and the human activities that produce them, will help stop the depletion of the ozone layer.

Some of the control measures include the following;

1. Control of bush burning: Bush burning produces high quantities of carbon (IV) oxide which causes the greenhouse effect, hence the depletion of the ozone layer. Reducing bush burning will also reduce carbon (IV) oxide in the atmosphere.

2. Stoppage of the burning of gas (called gas flaring)

3. Tree planting to help in absorbing greenhouse gases. 

4. Stoppage of the burning of refuse.

5. Controlling the use of generators for electricity generation. 

6. Regular servicing of automobiles to prevent the production of bad smoke, alongside Methane, which causes the depletion of the ozone layer.

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