Biology 3 Part 4

Human Activities and Waste
1. The population of the world has increased from about 0.2 billion six thousand years ago up to over 7 billion today. In the developed world the population has increased but this is now leveling off. Most of the population increase has been in the third world countries and this is still going on.
  1. Although the population of more developed countries provides the lower proportion of people, their demands are far greater. The need for high tech gadgets such as mobile phones and TVs, the need for the latest fashions in clothing and furniture means that the world's resources are being used up in manufacture, packaging and transport as well as generating unnecessary waste. In addition, as the standard of living improves the urban infrastructure increases, needing more houses, road, schools and hospitals. The raw materials for these mean that some large parts of the natural environment becomes quarries. These developments further reduce the natural space available for wildlife.
2. Dealing with Waste
  1. Much household waste can be recycled or composted. In England the proportion of waste dealt with in this way has increased since 1996 but it costs money and energy to collect and sort it.
    1. The larger portion of household waste still ends up in landfill sites. Here the decaying matter produces methane gas that could be collected and used for fuel but it can also produce toxic liquid that can pollute water ways. More recently incineration has become more common. Modern incinerators remove many chemicals from the smoke produced while the heat energy produced can be used.
      1. Air pollution is mainly due to the combustion of fossil fuels. As the fuel is dead organic matter from millions of years ago, the resultant pollutants mainly arise from oxygen recreating with elements in organic molecules
        Water pollution can be from toxic waste from industry but most comes from intensive farming practices. Fertilisers can leach from fields and enter water systems. Here it causes an algal bloom. This can block out light to reduce photosynthesis or it can lead to an increase in aerobic micro-organisms that use up oxygen as the decompose the excess algae. Both ways reduce the oxygen in the water and larger organisms die- EUTROPHICATION.
        Pesticides are used in low concentration but may bioaccumulate on going up the food chain. Eventually they reach a dangerous concentration in an organism. Therefore it is best of pesticides are biodegradable.
Deforestation
1. Problems
  1. Trees are massive carbon stores, taking in carbon dioxide from the air to produce sugar. Therefore deforestation reduces this.
  2. Burning felled trees releases carbon dioxide
  3. Dead trees decay and aerobic micro-organisms release carbon dioxide
  4. Tropical rain forests are the most biodiverse ecosystem on the planet.
    1. Humidity, warmth and light means that over 50% of all species live there.
  5. Each level of the rain forest, from ground to canopy, support different species
  6. 40% of pharmaceutical products come from rain forest plants
2. Why?
  1. Space for arable farming, pasture for cattle, human settlement (roads, houses, buildings), wood for fuel, wood for furniture, paper and hydroelectic power stations
3. Peat
  1. Peat bogs worldwide hold more carbon than all the forests
  2. It is bound into the decaying matter that forms peat
  3. Digging up peat to use as fuel reduces this and returns carbon dioxide into the air
4. Food
  1. The increased human population needs feeding
  2. The rise in fast food chains has increased the demand for beef, so more cattle farming
    1. The use of rice as a staple food in many parts of the world means lots of flooded paddy fields
      1. Both release methane
Climate Change
1. Shortwave radiation from the sun reaches earth
  1. The ground warms up and emits longwave radiation (Infra-red)
    1. Some is trapped by carbon dioxide, methane, nitrogen oxide, CFC’s and water vapour in the atmosphere.
      1. Some escape into space
        It is important to realise that the greenhouse effect is a natural, essential process. Without it, the average temperature on Earth would be about 17C and life would be impossible
        There are computer models of the effects on climate but there is disagreement about these. However, the belief is that continued temperature rise will lead to: more rainfall, storms and flooding, movement of suitable habitats for the organisms, the northward shift of forests, a decrease in biodiversity and possible extinction of species, changing migration patterns in birds, melting ice caps, rise in sea levels and loss of coastal shorelines.
2. Sequesting
  1. Remove carbon dioxide from the atmosphere and storing it in the sea
    1. At depths beyond 3000m it is denser than water
      1. However, there are questions as to the necessity of such a measure and insufficient data as to whether it would work.
3. Data on Climate Change
  1. Pre- 1860- indirect data: Tree width and width of xylem rings, timings if crop harvests in the past
  2. Ice Core data: Bubbles in the ice give data on gases present thousands of years ago. These give data on both carbon dioxide in the air and the temperature.
Biofuels
1. Palm Oil
2. Alcohol
  1. Is it Carbon Neutral?
3. Small Scale Biogas Production
4. Family Biogas Producer
5. Large Scale Biogas Production
6. Biogas from Landfill
7. Biogas from Lagoons
Mycoprotein
Food Chains
Energy in Living Things
1. Where does the energy go?
2. Intensive farming
3. Zero Grazing Dairy
4. Free Range Farming
Fish Stock
Feeding the World

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Biology 3 Part 4

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