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Environmental Systems and Societies

 

Access to freshwater

Water pollution results in the death of 10 people per minute, and nearly 500 000 people do not have access to safe drinking water (Rutherford, 2015).

 

Water Systems and pollution

Environmental systems are generally in a state of equilibrium. Inputs and outputs may vary but the system remains balanced. Pollution is a disturbance that can drastically alter characteristics of a water source. If the pollution causes enough of a disturbance in the water it can reach a tipping point, and enter a new state of equilibrium.

 

Point source versus non-point source pollution

If the pollution is coming from one specific source, we can call it point-source pollution. An example of point-source pollution is a sewage outlet pipe in a river.

 

Non-point source pollution comes from many diffuse sources. An example of non-point source pollution is air pollution, which is a result of small additions of pollutants from car exhaust, chimneys, and industrial smokestacks from all over the world. Water sources are also vulnerable to non-point source pollution. Rainfall on land leads to surface runoff that picks up all types of pollutant before returning either to groundwater or rivers, lakes, and oceans.

 

Water pollution can be caused by:

  • toxic substances

  • pathogens that cause disease

  • invasive species

  • excessive nutrients

 

Eutrophication is a problem of too much of a good thing. This type of water pollution caused by excessive amounts of nutrients (nitrogen or phosphorus) entering to a water source. Algae populations start to increase without limit and cause algal blooms. Some algae produce dangerous toxins. When all of the algae eventually die we get a new phase of increased decomposition. This increase in decomposition draws more oxygen out of the water leaving an anoxic (oxygen poor) environment for the rest of the organisms. (Rutherford, 2015)

 

Resources

Rutherford, J. (2015). Environmental systems and societies. Oxford University Press.

 

US Department of Commerce, National Oceanic and Atmospheric Administration. (2004, December 19). NOAA’s National Ocean Service Education: Estuaries. Retrieved November 29, 2017, from https://oceanservice.noaa.gov/education/kits/estuaries/media/supp_estuar09a_toxic.html

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