Eutrophication

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Eutrophication

• Learning objective
• To know the stages involved in eutrophication

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How do we get from this.
Farmer spraying fertiliser on his land
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to this.
Algal blooms
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to this?.
Dead fish
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Spray fertilisersWashed away by rainPlant
growth(bloom)ShadingPlant deathDecomposition
by bacteriaOxygen used up Aquatic animals die
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Eutrophication Eutrophication is a process
whereby lakes, estuaries, or slow-moving streams
receive excess nutrients that stimulate excessive
plant growth (algae and nuisance plants weeds).
This enhanced plant growth, often called an algal
bloom, results in a reduction of dissolved oxygen
in the water. The blooms block out the sunlight
to plants beneath them. The plants algae die
due to lack of light space. They are then
decomposed (rotted) by bacteria which use up the
oxygen in the water as they respire. As a result,
many water animals die from lack of oxygen.
Nutrients can come from many sources, such as
fertilizers applied to agricultural fields, golf
courses, and suburban lawns and sewage treatment
plant discharges. Water with a low concentration
of dissolved oxygen is called hypoxic.
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Eutrophication
Copy out the title into your book. Cut out the
boxes below and put them in the right order.
Fertilisers are sprayed onto fields by farmers
Bacteria use up more more oxygen as they
reproduce
Large fish die due to lack of oxygen food
Plants algae grow excessively due to the
increased nitrates phosphates in the fertiliser
Bacteria use up the oxygen in the water as they
respire
When it rains, the fertilisers are washed into
nearby streams lakes
Plants algae die due to lack of light/space
Small fish die due to lack of oxygen
Bacteria start to decompose the dead plants
algae
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Fertilisers are sprayed onto fields by farmers
When it rains, the fertilisers are washed into
nearby streams lakes
Plants algae grow excessively due to the
increased nitrates phosphates in the fertiliser
Plants algae die due to lack of light/space
Bacteria start to decompose the dead plants
algae
Bacteria use up the oxygen in the water as they
respire
Bacteria use up more more oxygen as they
reproduce
Small fish die due to lack of oxygen
Large fish die due to lack of oxygen food