Bioaccumulation - PowerPoint PPT Presentation

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Bioaccumulation

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As these chemicals move through the food chain there concentrations increase in ... osprey eagles, pelicans, falcons and hawks ... – PowerPoint PPT presentation

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Title: Bioaccumulation


1
Bioaccumulation
2
Principles
  • Non-biodegradable pesticides are taken up into
    environments and food chains and stored in fatty
    tissues.
  • As these chemicals move through the food chain
    there concentrations increase in the creatures
    increase. This process is bio magnification.
  • When the chemicals reach a tertiary consumer or
    higher in a food chain they reach toxic levels
    and so effect the live cycles of animals.
  • This is mainly seen with birds in the thinning of
    bird shells or the premature hatching of eggs. Or
    in extreme cases the the levels of toxins
    increasing to fatal levels.
  • The most well documented example of this is DDT.

3
Consequences of DDT
  • 0.1 µg (micrograms) of DDT per litre can slow
    down growth and photosynthesis in green algae.
  • Molluscs retain a lot of the DDT in their bodies
    this makes it dangerous for those predators who
    eat these organisms.
  • Some problems associated with DDT include
    reproductive/development impairment and nervous
    system disorders.
  • In fish DDT interferes with the plasma membrane
    where many important reactions occur.

4
Consequences of DDT
  • In birds DDT causes the thinning of eggshells
    this is caused by interferences with enzymes
    involved with reproduction.
  • Some species affected by DDT osprey eagles,
    pelicans, falcons and hawks
  • When DDT gets into our bodies, it is stored
    primarily in such fatty organs as the adrenals,
    testes, and thyroid. DDT is also stored in
    smaller concentrations in the liver and kidneys.
  • Concentration of 6-10 mg/kg leads to such
    symptoms as headache, nausea, vomiting,
    confusion, and tremors.

5
Ways to counter effects.
  • DDT was banned in the 60s to prevent further
    accumulation of chemicals. The most obvious
    effect of which has been increasing levels of
    peregrine falcons from near extinction due to
    increased shell strength.
  • Use of biodegradable pesticides prevents build up
    within organisms, despite being more expensive to
    produce and often less effect due to a short
    shelf lives.
  • Restrictions are in place for non-biodegradable
    pesticides but this is often ignored in
    developing countries trying to increase yield so
    chemicals are still entering food chains.
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