Eutrophication by ert554898


   Peter Fergie
           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
• This dead matter is then used by bacteria in aerobic
  respiration, allowing the bacteria to absorb more oxygen
  from the water.
How does that affect other organisms?
• With more oxygen being absorbed by the bacteria, there is
  less available for larger organisms which don’t 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.
         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.
• It’s 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.
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.

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