Biology 3

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  • Created by: A.B.
  • Created on: 22-04-13 21:11
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  • How humans can affect the environment Part 1
    • The effects of population explosion
      • The human population is growing rapidly and the standard of living is increasing.
        • This is because we do not have predators, lack of food, build up of waste product or disease.
        • The improvement in the standard of living means we use vast amounts of fossil fuels.
      • More waste is being produced. If it is not handled properly it can pollute the water, the air and the land.
        • Dumping of the waste also uses up land.
        • Increase in manufacturing leads to industrial waste.
        • Water can be polluted by sewage or fertilisers or toxic chemicals.
          • Can be washed into water.
        • Air can be polluted by smoke and poisonous gasses such as sulphur dioxide.
        • The land can be polluted with toxic chemicals such as herbicides and pesticides or contaminated with industrial waste.
          • Can be washed into water.
      • The activities of humans reduce the amount of land available for other animals and plants.
      • Raw materials, including non-renewable resources, are being used up rapidly.
    • Land and water pollution
      • Toxic chemicals such as pesticides and herbicides can pollute the land.
        • Also problem in industrial waste.
      • If sewage is not properly handled and treated it can pollute the water.
        • Increased by increased population. Soil polluted by chemicals and gut parasites.
      • Fertilisers and chemicals can be washed from the land into the water and pollute it.
        • Side effect of farming.
      • Untreated sewage and fertilisers that wash into water contain high levels of nitrates. These make the water plants grow rapidly and die quickly due to light competition.
        • This causes an increase in the microorganisms that feed on dead plants and there is a fall in oxygen levels which kills fish and add to the decomposers.
          • Eutrophication
        • Toxic chemical which are washed into water build up in the largest animals which die.
      • Bioindicators are species that can only be found in certain cleanliness of water and are used to measure pollution.
    • Air Pollution
      • When we burn fossil fuels, carbon dioxide is released into the atmosphere,
      • Sulfur dioxide and nitrogen oxides can be released when fossil fuels are burnt. These gasses dissolve in rainwater to make it more acidic.
        • The sulfur dioxide comes from sulfur impurities which react with oxygen.
      • Acid rain may damage trees directly. It can make lakes and rivers too acidic so plants and animals cannot live in them.
        • To try and reduce acid rain, low sulfur petrol and diesel are used in vehicles and cars and factories are fitted with catalytic converters.
      • Air pollution can cause global dimming as tiny solid particles in the air reflect away the sunlight.
        • Sulfur particles and smoke.
    • Deforestation and peat destruction.
      • Deforestation is the destruction or removal of areas of forest or woodland.
        • To produce land, fuel and food.
        • When the land is cleared for farming, the trees are are felled and burned but nor used which increases the amount of carbon dioxide in the atmosphere. When we lose trees, we lose a vital carbon 'sink' which the trees have stored.
      • Large - scale deforestation has led to an increase in the amount of carbon dioxide released into the atmosphere (from burning and the actions of microorganisms). It has also reduced the rate at which carbon dioxide is removed from the air by plants.
        • Also lost biodiversity - species die out that have not been identified or studied. They could be vital sources of medicine or food.
      • More rice fields and cattle have led to increased levels of methane in the atmosphere because rice and cattle both produce methane as they grow.
      • The destruction of peat bogs releases carbon dioxide into the atmosphere.
        • Peat bogs form over thousands of years. They are made of plant material that cannot decay completely because the conditions are very acidic and lack oxygen.
        • Peat can be burned as fuel and is also used by gardeners. When it is used, the carbon dioxide is released into the atmosphere.
        • Peat is formed very slowly so it is destroyed faster than it is made.
    • Global Warming
      • Increasing levels of carbon dioxide and methane in the atmosphere give an increased global warming effect, leading to global warming - an increase in the temperature od the surface of the earth.
        • Where the gasses absorb some of the sun's radiation so it cannot escape.
      • Global warming may cuase a number of changes including climate change, a rise in sea level, loss of biodiversity and changes in migration patterns and distribution of pspecies.
        • The change is only about 0.55 degrees from the 1970s to now.
      • Carbon dioxide is sequestered in plants nad water ( act as carbon sinks).


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