Eutrophication

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Eutrophication
Peter Fergie
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What is the problem?

• Eutrophication is a process by which an excess of
  nitrates can kill of populations of water-based
  organisms.
• This is due to the build up in nitrates
  increasing the population sizes of some plants in
  the water through increased fertility.
• When these plants die, there is an excess of
  organic dead matter.
• This dead matter is then used by bacteria in
  aerobic respiration, allowing the bacteria to
  absorb more oxygen from the water.

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How does that affect other organisms?

• With more oxygen being absorbed by the bacteria,
  there is less available for larger organisms
  which dont have the necessary adaptations to
  cope with lower oxygen levels.
• These organisms, often fish, can then no longer
  respire aerobically and will therefore die.
• This affects the whole cycle exponentially, as
  there is now more dead matter, and therefore more
  bacteria respiring aerobically, causing the O2
  levels to decrease further, therefore causing
  more and more fish to die.

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Why is this happening?

• This problem occurs when farmers use artificial
  chemical fertilizers on their land.
• These fertilizers contain large amounts of
  Potassium, Phosphorus and Nitrogen.
• Its the nitrogen which causes all the problems,
  in the form of nitrates.
• An excess of these will be washed out from the
  fields by the rain in a process called run-off,
  where the nitrates then accumulate in nearby
  rivers and ponds.
• This then links back to the original slide where
  the water plant population increases.

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How can the problem be overcome?

• The magnitude of the problem can be decreased by
  a number of factors.
• These include not overly fertilizing fields,
  using an organic fertilizer, and not releasing
  raw sewage into rivers and lakes.
• A reduction in fertilizer usage would leave the
  land with less excess nitrates going to waste and
  causing eutrophication.