How do lakes become eutrophic?

Answer 1

Eutrophication

Eutrophication is usually the result of fertilisers being washed into a body of water e.g. lake or river.

1) farmers add fertilisers (containing nitrates and Phosphates) to their crops to help them grow.

2)Heavy rain washes the fertilisers off and the nitrates and phosphates dissolve.

3) The nitrates and phosphates that aren't taken up by plants are washed into a stream or river.

4)The high concentrations of phosphates and nitrates encourage rapid plant and algae growth.

5) surface plants (in the body of water) block sunlight. so plants in the water can't photosynthesize and die (so no more oxygen is being made through photosynthesis.)

6) the decomposing bacteria that break down the dead plants thrive (because of all the dead plants) and use up more oxygen.

7) oxygen concentrations in the water decreases and animals (e.g. fish) die due to lack of oxygen.