Other Pollution (Cambridge (CIE) O Level Biology): Revision Note

Air Pollution

Methane and Carbon Dioxide

• Both gases insulate the Earth and act as a 'blanket' around the atmosphere

• Higher levels of both have led to global warming and climate change

• Human activity has increased levels of both gases in the atmosphere

  • Burning fossil fuels increases carbon dioxide

  • Keeping livestock generates methane gas

  • Global warming melts the permafrost in sub-polar regions, which results in even more trapped methane being released into the atmosphere

  • Other effects include more frequent extreme weather events (floods, hurricanes, droughts) that cause damage to habitats, including human habitats

The enhanced man-made greenhouse effect

Insecticide & Herbicide Pollution

Insecticide and Herbicide Pollution

• Pesticides in runoff from land can get into rivers and oceans

• Even though they are in small concentrations, the effect can be magnified along each trophic level

• This is called biomagnification and is worst for the top predator of the food chain

Biomagnification and bioaccumulation of a pesticide in an aquatic ecosystem

Plastic Pollution

• Plastics are non-biodegradable, so can have a negative impact on marine and terrestrial habitats

• In marine habitats:

  • Animals often try to eat plastic or become caught in it, leading to injuries and death

  • As the plastic breaks down it can release toxins that affect marine organisms

  • Once it has broken down into very small pieces, known as microplastics, it is commonly ingested by animals and enters the food chain

Oregon State University, CC BY-SA 2.0 , via Wikimedia Commons

Microplastics found in the ocean pose a danger of ingestion by aquatic organisms

• On land:

  • Plastic is generally disposed of by burying it in landfills

  • As it breaks down, it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals and can only be used for building, several decades after burial