1. WALT – Explain how we can use organisms to monitor pollution levels Pollution Indicators

2. What are pollution indicators? The organisms in polluted water tell you that there is something wrong.

3. Examples of pollution indicators Lichens are plants that grow in exposed places such as rocks or tree bark. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution. For example: bushy lichens need really clean air leafy lichens can survive a small amount of air pollution crusty lichens can survive in more polluted air no lichens air is heavily polluted with sulfur dioxide.

4. Examples of pollution indicators Some invertebrates like mayfly nymphs and rat- tailed maggots, are able to survive in polluted waters

5. This is what happens when a stream or river becomes polluted 1. Pollutant is added, which kills some living things. 2. Micro-organisms decompose them, they respire and use up the oxygen 3. Lack of oxygen kills other organisms, but a few species stay alive 4. As the water flows, oxygen levels gradually increase 5. Other living things recover too.

6. Sewage pollution and invertebrates Distance downstream from where sewage enters the river (m) What the water is like Invertebrates found (not drawn to scale)Oxygen levels Sewage enters here 0- 10 Dark and cloudy v. smelly Chironomous larvarat-tailed maggotFalling quickly 10-100Cloudy bad smell Tubiflex worm mosquito larvaVery low

7. 100-200Slight smell beginning to clear Flatwormcaddis fly larvaGradually rising 200+ClearStonefly larvamayfly larva Freshwater shrimp Back to normal Sewage pollution and invertebrates

8. Sulphur dioxide, cities and lichens A scientist surveyed the distribution of lichens. She counted the number of different species that grew on tree trunks at various distances from the centre of a polluted city. She also measured how much sulfur dioxide there was in the air. Distance to the town centre (Km) 012345678910 Number of different species of lichen 012681030445156 SO2 levels/(arbitrary units) 180160145119937149351150

9. Sulfur dioxide, cities and lichens Think : Is the data continuous or discreet? What are you : changing? (x-axis) Measuring? (y-axis) Distance to the town centre (Km) 012345678910 Number of different species of lichen 012681030445156 SO2 levels/(arbitrary units) 180160145119937149351150

10. Graph Questions 1. What is the relationship between the number of species of lichen and the distance from the centre of the city. 2. Name one invertebrate that can survive where there is little oxygen and another one that needs normal clear water to live in

11. How you will be graded Graph : 4 marks 1 for scale 1 for well labelled axes 1 for plotting 1 for line of best fit Question 1 = 2 marks Question 2 = 2 marks

12. Pollution in the Thames