ENV341H1 Chapter Notes - Chapter 3: Neural Tube Defect, Miscarriage, Cyanosis
DepartmentSchool of Environment
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Chapter 3: water quality and water resources:
•Diarrheal deaths, most due to waterborne infectious agents,.
•While the widespread use of oral rehyderation thearphy has substantially reduced
the mortality associated with waterborne disease, intensive efforts to provide
improve water and sanitary infrastructure in developing nations have been less
•Growing evidence indicates that updating the means of disposal of human wastes
improves human health to a greater extent than purveying clean water supplies.
•Sources of water:
•Drinking water is obtained primarily from surface water, such as streams, rivers and
lakes or from ground water through artesian or other types of wells.
•Other means of obtaining water include collecting rainwater, desalinating seawater.
•Surface water is in general, more prone to contamination by both microbial
pathogens and chemicals since it directly receives industrial and municipal
wastewater and runoff from the land.
•Ground water usually less contaminated than surface water because the soil through
which it proclates serves as a filter.
•Uses of water:
•Most water is used by toilets, and then cloth washers, showers, faucets, leaks, other
domestic and dishwasher.
•Sources of contamination:
•Contaminants can enter drinking water by a variety of mechanism.
•Many chemicals such as pesticides and fertilizers enter drinking water sources after
being deliberately applied to the land and washing into surface or ground waters.
•Can also enter water through moving through the soil
•Our methods of treating and distributing drinking water lead to some chemical
being present within our drinking water supplies.
•Sources of contaminants that discharge into receiving waters from a pope or other
identifiable device are called point sources.
•Point sources include industrial wastes and sewage treatment plants.
•Sources of contaminations that cannot be defined by discrete pipes or other devices
are called non-point sources.
•Water treatment process:
•The developed world reduced the burden of waterborne disease outbreaks by
implementing a process to treat drinking water in the late nineteenth and early 20th
•First water is pumped from its sources. The next step involves adding a chemical
•Water with chemical contamination may need to undergo additional treatment at
this stage, such as activated charcoal or special ion exchange resins.
•Boiling water is the traditional method of water purification, but since it requires
substantial energy production.
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