Lecture 3: Water hazards and Human health
Note: Assignments to be submitted to SW223
Liquid natural capitol
Ø Earth is water planet
Ø Water covers 71% of Earth surface but not all the water is available for our consumption
Not much fresh water
Ø Mostly salt water
Ø No species can do without water
Ø Sculpturing the Earth’s surface: Water change the shape of the planet Earth i.e. water erosion
Ø Moderating climate
Ø Removing and diluting wastes and pollutants
Percentages on how water is used up?
Flushing toilets (30%), Showering (35%), Cleaning (5%), Laundry (20%), Drinking (10%)
Canada has plenty of water available for us.
But some countries don’t have water for basic purposes
Ø One out of six people do not have regular access to clean water
- People are walking miles to get some clean water
Ø Diarrheal deaths kill over 2 million children annually
Water and Your Health
Ø Drinking water: NEED CLEAN WATER!
Ø Swimming water
Ø Annual reports on local drinking water quality
- Our right to know what we are drinking: what are we consuming?
Ø Naturally pure water & distillate water: Never purely 100% - we need some minerals in water. Distilled
water is free of salts. Water we drink is coming from the Lake Ontario from deep inside reservoir.
Ø Natural content of minerals in water
Ø Surface water - In urban areas mostly from rivers, lakes and reservoirs
Ø Ground water- In rural areas (wells). It’s underground.
How is drinking water treated?
Ø Water from rivers, lakes and reservoirs
• Settling tanks
• Addition of coagulants –dirt and contaminants form clumps that settle to the bottom of the tank
• Chemical treatment (disinfection, granulated activated charcoal (very good for organic
contaminants), ion exchange resins, reverse osmosis)
www.notesolution.com • Naturally filtered: Soil has different chemicals which purifies water.
• Less organic matter
• Often does not need any treatment
Chemical Treatment of the Drinking Water
Chlorination of Drinking Water: Its Benefits and Risks
Chlorine is widely used to disinfect drinking water. Common disinfectant. All about
chlorination: could be diff chemicals. That chemical react with organic matter in water with
algae, plant material. Some bio products DVP: 3 halo methane very complex materials. Adverse
effect to our health. Recent research say that they have adverse effects. Data is not clear. More
data needed regarding the problems. Cancerogenic and cause instant abortion. Benefits: killing
all germs. Make the water safe to drink. In the assignment we have to balance the good vs bad.
Contaminants in Drinking Water
- EPA sets standards for approximately 90 contaminants
- Microbes: animal and human waste
- Inorganic Contaminants
- Synthetic Organic Contaminants (including pesticides and herbicides)
- Volatile Organic Compounds (VOC)
- Disinfection byproducts
Microbes in Drinking Water
- Fecal Coliform and E. coli bacteria – contamination with human and animal wastes,
diarrhea, cramps, nausea, headaches, renal failure, coagulation disorders
- Salmonella typhi – typhoid fever (high fever, abdominal pain, constipation)
- Shigella sp.- more severe abdominal cramping with blood and mucus in the stool
- Vibrio cholerae – life threatening, rice-water stools
- Norwalk viruses, enteroviruses, adenoviruses - diarrheal illness
- Hepatites A- liver inflammation (transmitted by contaminated water) [Only water borne
disease that does not affect gastrointestinal]
- Cryptosporidium – parasite that enters lake and rivers through sewage and animal wastes