When you have finished check your answers.
Eutrophication Questions
Extra nutrients can also come from sewage discharges into rivers. Look at the graph and answer the questions on paper.Check your answers when you have finished.
1. Where do the phosphates and nitrates come from?
2. What causes the very sudden increase in the number of bacteria?
3. Why does the oxygen concentration in the water fall just downstream of the sewage outlet?
4. Why are there no fish just downstream of the sewage outlet?
5. Why does the number of algae increase downstream of the sewage outlet?
6. What causes the concentration of oxygen to recover to its original levels some way downstream of the sewage outlet?
7. Name one resource that the algae may be competing for.
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