Eutrophication
Biology: IB Diploma Higher Level, topic 8.1.7
Eutrophication
Using fertilisers can have negative impacts on the environment. For example, eutrophication can happen when too much fertiliser is used. The process of eutrophication is:
1) Leaching and overflow
- Fertilisers that are sprayed onto fields can leach through the soil or flow into ponds, rivers and lakes.
- Leaching is when water-soluble plant nutrients are lost from the soil.
- This causes a build up of nutrients in the water.
2) Algal overgrowth
- The excess of nutrients cause algae to rapidly grow on the surface of the water.
- As algae accumulate, light is prevented from reaching the plants in the water beneath.
3) Plant death
- The plants underneath the algae eventually die because there is insufficient light for them to photosynthesise.
4) Increase in numbers of bacteria
- Bacteria decompose the dead plants.
- As numbers of bacteria increase, the oxygen concentration in the water decreases.
- Fish and other organisms will now die because there is not enough oxygen.
Test yourself on Eutrophication
Stages of Eutrophication
What is the impact of excess nutrients in ponds, rivers and lakes on algae?
Which of the following statements about eutrophication is true?
What is the cause of plants in the water dying during eutrophication?