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Lecture

EESA10H3 Lecture Notes - Pentachlorophenol, Geomorphology, Ion Exchange


Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic

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Human Health and the Environment
Lecture 3: Waterborne Hazards and Human Health
Liquid natural capitol
Water generally is a liquid capitol, natural capitol
Why is it natural? Water is available everywhere in nature, we are surrounded by
water
Even our body is mostly consisted of water
Earth is a water planet – 71% of our surface is covered with water
Not all of this water is available for us for our consumption
Why? Mostly salty water – we are surrounded by huge oceans and huge seas
Not much fresh water that we can use for human consumption and animal
consumption
Why is water so important? No living species (animals, plants, or humans) can
survive and live without water
We always think about drinking though water is not just for drinking
Everything in household from cleaning to cooking, industrial purposes, agriculture
(for watering plants and crops)
There is a science called geomorphology that discusses sculpting the Earth’s
surface
Water is one of the factors that changes the shape of planet Earththis is called
water erosion
One of the types of erosion is water soil erosion - changes, moving of the soil by
water – water streams, surface runoff
Moderating climate – mild winter, hot summers (not that hot)
Water is a universal solvent – solve many different chemicals, same is the thing in
nature
Water is involved in dissolving and diluting particles – can be good and something
that we might not want
Water also dilutes wastes and pollutants – what happens is move water together
with water stream/flow and reach rivers, lakes, ponds, oceans
How much fresh water is available?
Not much fresh water is available on Earth
97.4% of all water is found in oceans and saline lakes
2.6% in fresh water is available
Of the 2.6% in fresh water most of it is captured as ice caps and glaciers (1.984%)
Water from ice caps and glaciers is not readily available (might be if global
warming continues)
Groundwater composes of a significant amount of the fresh water
Groundwater is available for us but we need to pump it out to use it and consume
it and also not use it more than it is replenished
There is only 0.014% of readily available fresh water
Of this, 0.007% is found in lakes, 0.005% as soil moisture, some significant
amount of water is in atmosphere as water vapour and some as biota (all living
organisms)
There are huge amounts of water stored in leaves and vegetation
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How do we use the world’s fresh water?
There is a comparison between three countries – Canada, U.S. and China
There is a significant difference in the use of fresh water between these three
countries
We are most interested in Canada – 64% of the fresh water is used for power plant
cooling, 15% in industry, 12% in public and 9% in agriculture
If you look at the graph of the U.S. much more water is used in the agricultural
sector (41%)
United States uses much more water for irrigation in agriculture; China uses even
much more (61%)
More specifically how do we use water in households? Too much water is used for
conventional use – flushing toilet (30%), showering (35%), laundry (20%), drinking
10% and cleaning (5%)
Hydrological poverty
Canada has plentiful water available but what about the people in some areas of
the world
People in many developing countries just don’t have enough water for basic things
such as drinking or cooking
One out of six people do not have regular access to clean water (safe water to
drink)
In many areas such as North Africa and Western Asia people travel far distances to
just get a couple of litres of water (they spend half of the day doing it)
They need to do it just to survive (often use polluted water because that is all they
can find)
As a result of this diarrheal deaths is very common in developing countries
It is the number one cause of death in children younger than five years old
The biggest risk – 2 million kids die every year due to diarrheal death
Adults are also under high risk but definitely children are at a huge risk
Water and Your health
We are in desperate need for help – drinking water and swimming water
Drinking Water
It is our right to know what it is that we drink – what other chemicals that we have
in a glass of water that we consume today
Our municipals must provide us with record – they are checking our tap water
everyday
Provide us with annual reports on local drinking water quality
On water bottles it says naturally pure water – water cannot be 100% pure
because water naturally has to have some minerals
We need calcium, potassium, magnesium, sodium and salts
There is no such thing as naturally pure water
Distillate water is water without salts – our body needs salts
Our tap water comes from Lake Ontario, an example of surface water
Surface water – in urban areas mostly from rivers, lakes and reservoirs
Ground water can also be used for water supply – wells are very common in rural
areas
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Ground water reservoirs can be very small or extremely huge
There is one ground water reservoir in the U.S. thousands of metres deep
underground that runs in 6 states
If we withdraw all this water more than can be naturally replenished that water
reservoir will shrink and it will not last forever
How is drinking water treated?
What do the municipalities do after they take water from rivers, lakes and
reservoirs?
They need to clean it, it is not for drinking
First they leave water in tanks to settle down – it is easier later to purify
Then they add coagulants agents (some specially designed chemicals) for this
purpose
The chemicals make clumps that settle down the smaller particles – it is easy to
remove them from the water in that way
Water then goes through mechanical filtering and some types of chemical filtering
There are different types of filters to filter bacteria, viruses and protozoa (some
microbes that are possibly found in water)
Filters are very good for filtering bacteria but not very good for filtering viruses
There is such a tiny and very small special techniques that need to be used for this
types of germs
Water then goes for disinfection (addition of chemicals)
Question 2 on your assignment is about addition of chlorine (one type of
disinfectant that can be added to water)
More new and advanced techniques are now often implemented and slowly
replace convention disinfection
One is granulated activated charcoal – chemical cleaning mostly of organic
contaminants
Ion exchange resins – better with heavy metals (mercury, lead)
Reverse osmosis – is a good technique for metals and inorganic contamination
Ground water is cleaner with less concentration of toxic chemicals
This is because it is naturally filtered – soil (consists of different types of
chemicals) is working as a natural filter
Water particulating through the soil reacting from different chemicals purify in that
way
Thus groundwater often does not need any treatment – it is pure and clean
enough already
Groundwater particulating through the soil can dissolve some minerals
That is how you can get mineral water or alga mineral water depends on the
percentage of each mineral
Some people cannot consume mineral water because of their health (because of
the rich minerals) or can be used as a mineral supplement
Chlorination of Drinking Water; Its Benefits and Risks (Assignment 1)
The most common disinfectants used for as infection of the water are chlorine,
chloramines and hypochlorite – all about chlorination, could be different chemicals
not just one
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