walt – explain how we can use organisms to monitor pollution levels pollution indicators

WALT – Explain how we can use organisms to monitor pollution levels

Pollution Indicators

What are pollution indicators?

The organisms in polluted water tell you that there is something wrong.

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.

Examples of pollution indicators

Some invertebrates like mayfly nymphs and rat-tailed maggots, are able to survive in polluted waters

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.

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 larva rat-tailed maggot Falling quickly

10-100 Cloudy bad smell

Tubiflex worm mosquito larva Very low

100-200 Slight smell beginning to clear

Flatworm caddis fly larva Gradually rising

200+ Clear Stonefly larva mayfly larva

Freshwater shrimp

Back to normal

Sewage pollution and invertebrates

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)

 0 1 2 3 4 5 6 7 8 9 10

Number of different species of lichen

 0 1 2 6 8 10 30 44 51 56 56

SO2 levels/(arbitrary units)

 180

160

145

119

93 71 49 35 11 5 0

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)

 0 1 2 3 4 5 6 7 8 9 10

Number of different species of lichen

 0 1 2 6 8 10 30 44 51 56 56

SO2 levels/(arbitrary units)

 180

160

145

119

93 71 49 35 11 5 0

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

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

Pollution in the Thames

Pollution in the Thames