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Lecture 3

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Environmental Science
Jovan Stefanovic

Week 3 – Lecture 3 Water Hazards and Human Health Liquid Capitol - The earth is composed of 71% water – mostly saltwater - Moderates climate, dilutes and removes pollutants and wastes - Every living creature needs water – Human body is 60% water World’s Water Problem Quantity - Withdrawal – the amount of water removed from a river, lake, or aquifer. - Some may be returned to the source for reuse - Fresh water = 2.6% of all water available o Mostly in glaciers, ice caps, and groundwater o Readily accessible freshwater can be found in lakes, rivers, soil moisture - Stress on the World’s river basins? o Water stress = <1700 cubic meters/year/person o Water Scarcity = <1000 cubic meters/year/person - Some areas have lots of water – some are too far from population and agriculture – not distributed to key areas properly - Precipitation cannot be collected and stored effectively - As a result, lakes and rivers shrink eg. Aral Sea - How do we use water? o 85% is used for irrigation and not returned to the water basin o Canada = mainly used to cool power plants  In homes = showering, toiler, laundry, drinking, cleaning o China = agriculture o USA = both o All = mainly delivered to the public and industries - Hydrological Poverty – not enough water eg. Asia/Africa (1 out of 6 don’t have access to clean water) o People in these areas need to walk and get water = increased chances of contracting diseases/death eg. Diarrhea – kills 2 million children annually (dehydration) o Bad hygiene at home and body = host to diseases and parasites - Water and your health o Drinking water  Let the water system go for a few minutes in the morning because the water in the system has been idle overnight and might have higher traces of minerals and chemicals  Annual reports of water quality  Tap water – checked everyday o Hot water accumulates more lead o Acidic waters dissolves more metal and lead o Soft water attracts more metals o Surface water – mostly in urban areas – come from lakes, basins, rivers o Ground water – mostly in rural areas – come from wells, underground  Bottled water - not checked everyday o Plastic use may be a danger – strip some essential minerals eg. Calcium and Magnesium  Mineral water – higher salt level o Sources of water  Runoff from the mountain reaches the soil and lakes  Ground water is naturally purified in rocks and sand  Unconfined aquifer  Easier to contaminate  Less often used  Confined Aquifer  Cleaner and harder to get  Need to drill to get access o Effects of Urbanization  Surface runoff is smaller in urbanized areas because of concrete  In rural areas, there is more soil = more ground water, runoff is also slow due to vegetation Quality How is drinking water treated? - Water from rivers, lakes, streams o In settling tanks – treated with coagulants so dirt and contaminants settle at the bottom of the tank. o It is then filtered and particles are removed o Chemical filtration – reverse osmosis, chlorination, resins, charcoal  Chlorination – important in the process as it makes the water safe for drinking  prolonged effect of disinfection - Groundwater o Naturally filtered through rocks, sand o Has less organic matter and is fine without any treatment o Problem arises when there is contamination of the soil as it can leak to these sources Contaminants in drinking water Overview - Pesticides and fertilizers o Used in agriculture o Produced nitrates and contaminates water  can be washed off by runoffs and be fed into streams/rivers/lakes - Underground storage tanks o Age of these tanks  old tank can start leaking chemicals and contaminate ground water eg. Septic tanks o Sewers and lagoons can leak nitrogen - Landfills/Factories o Lead leak from plastic liners 1) Microbes – causes poop disorders (except for Hepatitis A) - Fecal Coliform and E. coli bacteria o Human and animal wastes contamination – causes diarrhea, n/v, headaches, renal failure, coagulation disorders o Fecal Coliform test  Sample in filtering apparatus  filter disk for 24 hours  after incubation, count the number of colonies present.  Each colony of E.coli came from a single coliform bacterium o Case study  Walkerton (May 2001)  6 deaths d/t contaminated water  Arose from manure used in agriculture  rains assisted the bacteria to seep through the soil  contaminate water  Officials failed to inform the public  budget cuts = no testers  after incident = more water testers - Salmonella typhi o Typhoid fever – fever, constipation, abdo pain - Shigella – abdo cramps with blood in stool/mucous - Vibrio cholera (Cholera) – rice-water stools, life threat - Norwalk virus, enterovirus, adenovirus – diarrhea - Hepatitis A – liver inflammation - Parasites– enters lakes and rivers through sewages and animal wastes o Cryptosporidium o Giardia lamblia  diarrhea, cramps, vomiting 2) Radionuclides – damage DNA  increased risk of cancers - Alpha emitters, beta/photon emitters - Radium 226/228 - Radon gas – colourless and odourless o From radioactive decay of Uranium 238 (half-life of 4.5 billion
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