How Clean is Our Air and Water? - Pollution
SKILLS: Observing, gathering information, critical thinking and communication |
OBJECTIVE: Students will discover from this activity that some of the changes people cause in habitats are unhealthy to plants, animals, and people themselves. The students survey for physical and biological indicators of urban pollution and learn how pollution affects
This class activity is best done in groups of two to four.
FOR THE CLASS
- jar of petroleum jelly (KY or Vaseline)
- pH test kit
FOR EACH GROUP
- glass slides (a plastic yogurt carton top or white cardboard will do)
- old white socks
- clear glass jars and funnels for collecting rain
FOR EACH STUDENT
- paper for a data sheet
- magnifying glass
The goal of this activity is for students to learn some effects of pollution on both wildlife and people. Talk with them about what pollution is, how they have experienced pollution, and how they think it affects other living things.
Divide the students into groups and distribute paper for data sheets and other materials. Students will observe various pollutants, following the directions below, and record their observations for the following activities:
- Particulate air pollution - Coat one side of a glass slide, weighted plastic yogurt top or white cardboard with a thin layer of petroleum jelly. Leave it exposed outdoors (on a window ledge, tree or curb) for 24 hours. Examine the particles stuck to the petroleum jelly with a magnifying glass. This activity may be repeated at different times or in different places to check for variations in the pollution level.
- Acid pollution (sulfur dioxide) - is often emitted in burning fossil fuels. Collect rainwater running off trees (some increase or decrease in pH may occur because of deposits on trees). Neutral pH is 7. The average pH of rainwater is dependent on the location. In industrialized nations it is between 4.0 and 4.5. In some areas rainfall may be as low as 3.2 or as high as 7.0. Many plants and animals cannot tolerate a pH below 5.5.
- Noise Pollution - Have students stand about 1 metre apart near street traffic or some other usual city noise. They should try to talk to each other without raising their voices. If they cannot hear each other clearly, the noise is potentially harmful.
- Air pollution from automobiles - To demonstrate how cars pollute, tie an old white sock or other white material over a cold exhaust pipe. Run the car for two minutes. Carefully remove and examine the sock. Also tell the students that some harmful parts of the exhaust are the invisible gases. Car exhaust contains carbon monoxide, nitrogen dioxide, and hydrocarbons; exhaust gases can be converted by sunlight into ozone.
Caution: Discuss the need to be careful of hot exhaust pipes and of breathing exhaust fumes.
- Oil Pollution - Can students find oil spots on streets or in parking lots? What happens to this oil when it rains? (eg. oil washed into storm sewers). Where might it eventually end up?
- Acid pollution (sulfur dioxide) - Acid rain can dissolve some types of stone, particularly limstone. Record signs of rapid weathering of statues, gravestones, or building stones.
- Air pollution - Students can discover and record the daily air quality index published in the local paper, given over the radio or weather-related internet sites. Investigate how the index is computed and what it measures.
- Air pollution - Examine leaves for soot covering and for brown spots. These signs often indicate air pollution damage.
- Animal waste - Students should look for presence of dog waste on streets, sidewalks and lawns. Is there much of it? This waste is often washed into local waterways.
- Water pollution (industrial or municipal waste) - If there is a safe place to walk along a lake, river or stream, the students should check the banks for discharge pipes. Are wastes being added to the water in this way? What other signs of pollution can they see (garbage, scum on the water surface, etc.)?
After the students have observed and recorded signs of pollution, they should research its effects on living things. They can gather additional information by having speakers come into the
class, obtaining information from local health and wildlife organizations, or by library or internet research. Research or speakers should center on pollutants the students have actually seen, such as the following examples.
Examples of pollution effects on animals (the effects are often similar on humans):
- Particulates in the air are harmful to birds which feed on insects by flying with their mouth open. Soot-covered vegetation supports fewer insects.
- Acid pollution in rivers eventually kills fish and other aquatic life. Sulfur dioxide has been shown to decrease reproduction in rabbits. Most cities adjust pH of drinking water through costly chemical treatment.
- Carbon monoxide cuts down the amount of oxygen carried in the blood and may destroy brain cells and retard metabolism.
- Ozone has been shown to cause lung damage in rabbits.
- Oil and hydrocarbons affect birds. Many have been killed by oil on their feathers and hydrocarbons in their bodies. Oil on eggs, sometimes rubbed off from the parentsŐ bodies, can prevent eggs from hatching.
- Water pollution, from industrial wastes and agricultural runoff, may add nutrients to the aquatic habitat or poison fish and other aquatic organisms.
When the data sheets are completed, the students should prepare a report to compare the effects of pollution on animals and people. Stress that the presence of healthy wildlife and plants will indicate an environment that is also healthy for people.
The class may also want to initiate a project to help clean up pollution in their neighbourhood or school yard.