Topic 8 - Water Pollution and Deforestation

Question 1

what causes eutrophication?

Answer 1

nitrates and phosphates are put onto fields as mineral fertilisers. if too much is applied and it rains afterwards, they’re leached into rivers and lakes.

Question 2

what happens when a lake goes through eutrophication?

Answer 2

1. extra nutrients cause an algal bloom, which blocks out light
2. plants in the lake can’t photosynthesis due to lack of light and die
3. decomposers increase in number because there’s more food, and deplete the oxygen in the water
4. organisms that need oxygen die

Question 3

what can also cause eutrophication?

Answer 3

pollution by sewage