Environmental StudiesIDC3O3

Ms. Nguyen

*HYDROSPHERE

*Lack Access to Clean Water*More than two thirds of the world’s households must fetch

water from outside the home*When water is scarce and difficult to obtain, it discourages

proper sanitation*Availability doesn’t always mean affordability

*Water sellers offer delivery to homes in most countries, but the quality often is questionable

*Price may be more than most families can afford

*For example:*A typical family in in Lima, Peru uses one-sixth as much

water as a middle class American household but pays three times as much for it

*If government recommendations were followed to boil the water to prevent diseases, up to one-third of poor family’s income could be used in acquiring and purifying water

*Water Pollution*Water pollution is anything that degrades water quality

*Two types of pollution:*Point source: discharge pollution from specific location such

as drain pipes, ditches or sewer outfalls*Example: factories, power plants, sewage treatment plants,

underground coal mines and oil wells

* Nonpoint source: water pollution are scattered or diffuse, having no specific locations where they discharge into a particular body of water*Run-off from farm fields and feedlots, golf courses, lawns and

gardens, construction sites, logging areas, roads, streets and parking lots

*Difficult to monitor, regulate and treat than point sources

*Continue…* a major nonpoint pollution is atmospheric deposition of

contaminates carried by air currents and precipitated into watersheds or directly onto surface water as snow, rain or dry particles.

*For example:*The Great Lakes have been found to be accumulating

industrial chemicals such as PCBs, dioxins, and agricultural toxins such as insecticide toxaphene

*26,000 metric tons of PCBs over the past 12 years have “disappeared” from Lake Superior and carried by air currents to other areas

*Point and nonpoint sources of pollution

*What is a good indicator of water quality?* Amount of oxygen dissolved in water

is a good indicator of water quality*Oxygen with a water content above 6

parts per million (ppm) will support many forms of aquatic life

*Less than 2ppm, oxygen will only support worms, bacteria, fungi and other detritus feeders and decomposers

*We use aquatic microorganisms as bioindicators*Caddisflies and dragonfly larvae =

good water quality; worms = poor

*How is oxygen cycled in water?

*Oxygen is added to water by diffusion from the air, especially when turbulence and mixing rates are high*By photosynthesis of green plants, algae and

cyanobacteria (blue –green bacteria)

* Oxygen is removed from water by respiration and chemical processes that consume oxygen

*The Impact of Eutrofication*Eutrophication = process by which a body of

water acquires a high concentration of nutrients, especially phosphates and nitrates or organic wastes*E.g. Organic waste such as sewage, paper pulp or

food waste are rich in nutrients*Impact = Increases plant and algae growth

*The Impact of Eutrofication*With increased growth comes increased rate of

death and decay results in the growth of oxygen demanding decomposing bacteria *Biochemical oxygen demand (BOD) = measure of the oxygen used by microorganisms to decompose organic matter

*High levels of BOD mean low levels of dissolved oxygen in the water

* Since low levels of DO is available in the water, fish & other aquatic organisms may not survive

*The affects of oxygen-demanding wastes on rivers depends to a great extent on the volume, flow and temperature of the river water

*Continue…*Oxygen decline downstream is called the

oxygen sag

*Continue…*http://www.scivee.tv/node/14602