water pollution and deforestation

• how does eutrophication take place?

  • Fertilisers enter water - add extra nutrients (nitrates and phosphates)
  • extra nutrients cause algae to grow fast and block light
  • plant can't photosynthesis due to lack of light - start to die
  • more food available - microorganisms that feed on dead plants increase number and deplete all of the oxygen in water
  • organisms needing oxygen therefore die
• how does leaching have a negative effect on deforestation?

  • trees take up nutrients from soil before they are washed away by rain - return them to the soil when leaves die
  • when trees are removed nutrients get leached away and don't ger replaced leaving infertile soil
• how does soil eroision have a negative effect on deforestation?

  • Tree roots hold the soil together
  • when a tree is removed - soil can be washed away by rain leaving infertile ground
• how does disturbed balance of CO2 and O2 have a negative effect on deforestation?

  • forest take up CO2 by photosynthesis, store it in wood and slowly release it when they decompose
  • when tree cut down and burnt - stored carbon released at once as CO2 - disturbs carbon cycle and contributes to global warming
  • fewer trees in the forest also means less photosynthesis which releases less oxygen causes oxygen levels to drop
• how does disturbing evapotranspiration negatively effect deforestation?

  • Evapotranspiration includes both the process of water evaporating from the Earth's surface and from plant transpiration
  • this water falls back to earth as rain
  • when trees are cut down - evapotranspiration is reduced which makes local climate drier
• whats another form of eutrophication?

  • in sewage as it contains lots of phosphates from detergents and nitrates from urine and faeces which cause eutrophication same as fertilisers