Chapter 22 Our Impact on the Ecosystem Lesson 2 - Air pollution

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Chapter 22 Our Impact on the Ecosystem Lesson 2 - Air pollution

  1. 1. 3) Pollution - process by which harmful substances are added to the environment
  2. 2. Pollution <ul><li>Definition </li></ul><ul><li>Pollution is the addition of substances to the environment that damage it, making it undesirable or unfit for life. </li></ul><ul><li>The substances that cause pollution are called pollutants </li></ul>
  3. 4. Lesson objectives: <ul><li>Air pollution </li></ul><ul><ul><li>Sulfur dioxide & nitrogen oxides (acid rain) </li></ul></ul><ul><ul><li>Smog </li></ul></ul><ul><ul><li>Lead </li></ul></ul><ul><ul><li>Carbon monoxide (CO) </li></ul></ul><ul><ul><li>Carbon dioxide (CO 2 ) </li></ul></ul><ul><ul><li>CFCs (chlorofluorocarbons) </li></ul></ul>S uper N anny S ays L et’s C ry 3
  4. 5. Air pollution <ul><li>Mainly from incomplete burning of fuels e.g. coal, oil, petrol and wood </li></ul><ul><li>May be due to </li></ul><ul><li>(i) human activities </li></ul><ul><li> 1) Exhaust fumes from motor vehicles </li></ul><ul><li> 2) Chimney fumes from industries (burning of fossil fuel) </li></ul><ul><li> 3) Burning of garbage </li></ul><ul><li>4) Use of CFCs in foam packaging </li></ul><ul><li>(ii) natural occurrences </li></ul><ul><li> 1) biological decay </li></ul><ul><li> 2) forest fires </li></ul><ul><li> 3) volcanic eruptions </li></ul>Releases ammonia into the air
  5. 6. Pollutants <ul><li>Air pollution </li></ul><ul><li>Sulfur dioxide + nitrogen oxides (formation of acid rain) </li></ul><ul><li>Smog </li></ul><ul><li>Lead </li></ul><ul><li>CO </li></ul><ul><li>CO 2 </li></ul><ul><li>CFCs (chlorofluorocarbons) </li></ul>
  6. 7. Sulfur dioxide + nitrogen oxides <ul><li>From the burning of fossil fuels </li></ul><ul><li>Effects : </li></ul><ul><li>Plants </li></ul><ul><li>- sulfur dioxide penetrates leaves through stomata -> damages leaves and kill the plants </li></ul><ul><li>Humans </li></ul><ul><li>- sulfur dioxide irritates and damages the sensitive lining of the eyes, air passages and lungs </li></ul><ul><li>- prolonged exposure -> respiratory diseases </li></ul><ul><li>Acid rain formation </li></ul>
  7. 8. Acid rain <ul><li>Reaction of sulphur dioxide and oxides of nitrogen with O 2 and rainwater to form sulphuric acid + nitric acid </li></ul>
  8. 9. Acid rain <ul><li>Effects of acid rain : </li></ul><ul><li>-> dissolves aluminium salts in soil + washes them into rivers and lakes </li></ul><ul><li>-> death of fish in lakes + rivers (due to high salt concentration/ acidity ) </li></ul>
  9. 10. Effects of acid rain Effect of acid rain on statues Effect of acid rain on rainforest in Germany
  10. 11. Acid Precipitation Collector
  11. 12. 2) Smog <ul><li>Sulphur dioxide (main component) </li></ul><ul><li>A mixture of smoke and fog </li></ul>
  12. 13. Understanding how smog is formed…
  13. 14. How is smog formed? <ul><li>Normally smoke rises + blown away by wind </li></ul><ul><li>Sometimes inversion happens (layer of warm air traps the cool air + pollutants) </li></ul><ul><li>Accumulation of pollutants in stagnant air </li></ul><ul><li>May cause respiratory diseases (e.g. chronic bronchitis + emphysema) </li></ul><ul><li>May be lethal when it reaches high concentrations </li></ul>
  14. 15. Lead <ul><li>Lead poisoning -> accumulation of lead in body over long periods </li></ul><ul><li>Lead may be present in </li></ul><ul><ul><li>Air </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Food we eat </li></ul></ul><ul><li>Effects : </li></ul><ul><li>Cramps </li></ul><ul><li>Loss of control of the hands and feet </li></ul><ul><li>Coma </li></ul><ul><li>Death </li></ul>
  15. 17. CO <ul><li>From exhaust of motor vehicles </li></ul><ul><li>Combines with haemoglobin in RBCs -> carboxyhaemoglobin </li></ul><ul><li>Reduces capacity of blood in O 2 transport </li></ul><ul><li>Harmful and fatal in high concentrations </li></ul>
  16. 18. CO 2 <ul><li>From the burning of organic compounds </li></ul><ul><li>High concentrations in atmosphere due to industrialization and increasing car populations </li></ul><ul><li>Retains heat radiated from the Earth’s surface ( greenhouse effect ) -> global warming </li></ul><ul><li>Effects of global warming: </li></ul><ul><li>-> world temperature may rise </li></ul><ul><li>-> melting of icebergs </li></ul><ul><li>-> rising sea levels </li></ul><ul><li>-> submerge/flood low-lying countries </li></ul>
  17. 21. CFCs (chlorofluorocarbons) <ul><li>Non-toxic unreactive chemicals </li></ul><ul><li>Used as: </li></ul><ul><li>(i) aerosol propellants </li></ul><ul><li>(ii) cooling agents (refrigerators + air conditioners) </li></ul><ul><li>(iii) foam packaging </li></ul><ul><li>Break down the ozone layer -> allowing more UV rays to penetrate into the Earth -> increases risk of skin cancer </li></ul>
  18. 24. Air pollution
  19. 25. Summary
  20. 27. Ways of reducing air pollution <ul><li>Catalytic converters in cars </li></ul><ul><li>Reduce frequency of car usage (car pool) </li></ul><ul><li>Filters/ scrubbers in chimneys (removes SO 2 ) </li></ul><ul><li>Use Non-fossil fuels </li></ul><ul><li>Less usage of fossil fuels near densely populated areas </li></ul><ul><li>Alkalis to neutralise acidic waste products from factories before release into environment </li></ul><ul><li>Ozone-friendly products </li></ul>Note: We can only prevent/reduce pollutants from human activities. Pollutants from natural causes cannot be avoided.
  21. 28. TYS questions <ul><li>Describe the ways in which air may be polluted and the possible consequences. [7] </li></ul><ul><li>[N2005 2B 8 Or] </li></ul>

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