Water Pollution and Deforestation

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  • Nitrates and phosphates are put onto fields as mineral fertilisers
  • If too much fertiliser is applied and it rains, it leaches (washes through the soil) into rivers and lakes
  • This results in eutrophication

1)     Fertilisers enter the water, adding extra nutrients (nitrates and phosphates)
2)     The extra nutrients causes algae to grow fast and block out the light
3)     Plants can’t photosynthesise due to a lack of light and start to die
4)     With more food available, microorganisms that feed on dead plants increase in number and deplete (use up) all the oxygen in the water
5)     Organisms that need oxygen (e.g. fish) die

  • Another cause of eutrophication is pollution by sewage. Sewage contains lots of phosphates from detergents, e.g.


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