Environmental Issues

The main man-made causes are thought to be carbon dioxide and methane from factory, power station and car emissions, the waste products of respiration, logging, the mining of fossil fuels and the breakdown of plant matter in swamps. The long-term effects may include melting of glaciers and a rise in sea level, and a global change in climate and type of vegetation.


  1. Sewage is all household waste water. Many detergents contain phosphates which act as plant fertilisers. When these phosphates and the sewerage reach rivers, they help water plants to grow in abundance, reducing the dissolved oxygen in the river water. The result is death of aquatic animals due to suffocation by the algal blooms. This harmful effect is called eutrophication.
  2. Biodegradable detergents are more environmentally friendly because they are readily broken down to harmless substances by decomposing bacteria.
  3. Suspended solids in water such as silt reduce the amount of light that reaches the depths of the water in lakes and rivers. This reduces the ability of aquatic plants to photosynthesise and the result is less plant and animal life. Turbidity is the measure of 'cloudiness' or the depth to which light can reach in water.



Energy Crisis & Energy Alternatives

With population growth comes increased usage of energy. The energy crisis is the inability of the earth's resources to keep pace with the population's needs. The solution to the energy crisis is twofold - build more power stations to supply more energy, or reduce the usage of energy by building more energy-efficient devices.

There are 2 types of energy sources - non-renewable and renewable.

NON-RENEWABLE ENERGY SOURCES
  • e.g. fossil fuels (coal, oil, natural gas) and nuclear energy (uranium, plutonium)
  • Takes a long time to form (e.g. millions of years)
  • Cannot be reused
  • Advantages
  • Cheap
  • Readily available
  • Efficient
  • Multipurpose (e.g. oil for cars, heating)
  • Disadvantages
  • Polluting or radioactive
  • Running out
RENEWABLE ENERGY SOURCES
  • e.g. biomass, solar, wind, wave, tidal, hydroelectric, geothermal
  • Takes a shorter time to form (e.g. decade or two)
  • Can be reused or is very abundant
  • Advantages
  • Won't run out
  • Environmentally friendly
  • Disadvantages
  • Inefficient
  • Geographically selected


NON-RENEWABLE ENERGY SOURCES


RENEWABLE ENERGY SOURCES