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Lecture 3

Lecture 3 Water

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Environmental Studies
ENSC 203
Rob Beamish

Lecture 3 Water (Liquid Natural Capitol)  Water is in the air and in our body (60% of our body)  Earth is a water planet and is 71% percent of it is covered with water  However this water is mostly salt water and this limits its usages and more expensive to use the limited fresh water.  To convert salt water to drinking water is expensive, corrosive and difficult to do.  No species can exist without water  Water changes the surfaces of the Earth (e.g. hill, valley, canyons) due to erosion of the soil, rain, weathering  Water moderates climates  It is also used to remove and dilute wastes and pollutants  Human usage: withdrawal – total amount of water removed from a river, lake or aquifer for any purpose. Some of this water can be returned to its source. o Water cycle is one of the most important cycles on the Earth and reuses and renews water the supply on Earth o Humans use 54% of the world’s reliable run-off (surface water). In 2025, humans would have consumed 70%-90% of available surface water. o Raises two questions: 1) how much water is available and 2) what is the quality of available reliable water.  Globally, there is a very low amount of fresh water available. 2.6% of all available water is fresh water and only 0.14% is readily accessible water.  Some areas of the planet lack a good amount of water (less than 1700 cubic meters/year/person) (e.g. USA, Africa, and lower Asia). Under water stress.  Canada has 20% of all freshwater in the world. o Some World’s Problems:  Some areas have a lot of water but the largest rivers are far from agricultural and population centres. It is very expensive to transport to where it is needed.  Lot of precipitation arrives during short periods which cannot and stored because it is very expensive  Lakes and rivers are shrinking due to climate change o How do we use our water?  64% of available water is used for industrial purposes such as power plant cooling  A lot of water is being used in the agricultural centers of the USA, not so much in Canada. In China, most of the water is used for agriculture purposes (87%).  85% of water available is consumed and not returned to its water basin (source).  In Canada, one household would use for showering (35%) and flushing the toilet.  Majority of world lives in hydrological poverty. 1 of 6 people doesn’t have access to clean water.  Poor quality water can lead to diarrhea and kills 2 million children annually. Water and Your Health Drinking Water  Municipal government reports annually on local drinking water quality  Is there any naturally pure water? No, all water contains other minerals like potassium, sodium and magnesium. These minerals are good for one’s health.  Distillate water is a not good for drinking because it is lacking minerals.  Water percolates with the soil and then rocks and then minerals dilute within the water. However, some minerals are not good, such as arsenic.  Surface water (e.g. rivers, lakes, and reservoirs) are sources of water for urban areas. Ground water in rural areas (e.g. wells and water below ground reservoir) is used to attain water.  Ground water is fed from the ground and moves slowly and thus it is hard to contaminate. However, once contaminated, it is harder to clean it of impurities. Ground water can be either deep or shallow.  Water found in different sources undergoes different process and treatments. Mechanical Aspect o Mechanical impurities are removed (e.g. organic material, plant parts) –put in tanks to let water settle. o Some compounds are added to clump impurities and allow settling at the bottom of the water basin. o Water undergoes filtration. Chemical Aspect o Water undergoes chemical disinfection. o Chlorination is a popular technique in disinfecting water. o Before the chlorination technique, in the end of 19 century, many people in England died from cholera because of microbes in water. When chlorination of water became a practice, water quality improved greatly. o Research found out that a special type of coal can remove many type of organic materials but cannot remove inorganic materials from water. However, they are only in use when necessary. For example, used if water is contaminated with metals and no water supply is around, these treatments may be used.  Ground Water is naturally filtered water and contains less organic matter. It often does not need any treatment.  Contaminants in Drinking Water: o Contaminants vs. Pollutants  Contaminants are any agents that can be found in water, soil or other mediums but does not necessarily hurt an individual but may cause health effects in high
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