Explain with a diagram how reverse osmosis works. What is the process of biomagnification? Give the cause and an example. Discuss mercury in fish and what problems they can cause to human health. What...

2012 SU1 NASE 328 Water Quality Name _____________________________
2012 SU1 NASE 328 Water
Quality Name
_____________________________
May Intensive email final
exam
Date ___________________
Select 20 out of the following 25 short questions to answer. They are
worth 5 points each. Only the first 20 answered will be graded. Read
through all 25 and answer the questions you are most comfortable with

first. You may use class notes, discussions, or the web. But each
question must be given a specific reference. The reference may be
class notes, the field trips or give the specific web site you visited. Points
will be deducted if there is no reference.
1. Explain with a diagram how reverse osmosis works.
Ans. Reverse osmosis (RO) is a membrane-technology filtration technique
which helps to remove various types of big molecules and ions from
solutions by applying pressure to the solution when it is on one side of a
selectively permeable membrane. The results in retainment of solute on
the pressurized side of the membrane and the pure solvent are permitted
to pass to the other side.
(Reference: http://wattsupmarine.blogspot.in/2011/01/yes-you-can-build-your-own-water-maker.html)
http://wattsupmarine.blogspot.in/2011/01/yes-you-can-build-your-own-water-maker.html
2. What is the process of biomagnification? Give the cause and an
example.
Ans. Process of accumulation of poisonous substances in the organisms at
different trophic levels is called biomagnifications. For example, let us
consider the following food chains where poisonous substances enter the
food chain at the producer’s level: grasses  sheep, goat or cow  man.
In this food chain, grasses are the producers. These absorb harmful
chemicals from the soil. These chemicals reach the body of the sheep or
goat on eating the grass. These harmful chemicals along along with the
milk and meat of sheep or goat reach man’s body and accumulate there.
Recently DDT which is a poisonous chemical has been found in
concentration higher than the permissible limit. It enters the food chain at
the producer’s level and accumulates in the body of sheep, goat or cow.
Through milk DDT reaches the man’s body.
3. Discuss mercury in fish and what problems they can cause to human
health. What fish are most dangerous and which are safe?
Ans. mercury which is present in air can be deposited in water. It is then
converted to methyl mercury by certain microorganisms present in water.
Methyl mercury is very toxic and can enter fish and shell fish. Methyl
mercury can also enter the body of human beings who eat fishes and it
can cause harm to human health. The most common adverse effect of
methyl mercury poisoning is that it affects neurological development of the
fetus. It affects the brain and nervous system of the baby and leads to
defects in speech, vision, cognitive development, language development
as well as motor skills. Muscles can also become weak. It can also lead to
memory loss and fatigue. The most dangerous which contains highest
amount of mercury are Tuna, Shark, Sword fish, Marlin. These fishes
should not be eaten. The safest fish which have lowest amount of mercury
are catfish, shrimp, and whitefish, salmon. (Reference: Stibich Mark, The
best Types of fish for Health, 2009,
http://longevity.about.com/od/lifelongnutrition/a/fish_mercury.htm)
4. Compare the cost of Cambridge tap water with that of bottled water.
Give an advantages and disadvantage of each.
http://longevity.about.com/od/lifelongnutrition/a/fish_mercury.htm
Ans. Cambridge bottled water is expensive. It costs approximately $2 for 1
liter of bottled water and approximately $7.60 for 1 gallon of bottled
water. But still many people prefer to drink bottled water. Bottled water
are hygienic and purified. Thus bottled water is more healthy, but at the
same time it is very expensive and plastics are use to make bottles which
is harmful for the environment. But tap water may not be as healthy than
bottled water. It may not be completely hygienic, but more cheap and
ecofriendly.
(References:
http://cambridgesciencefestivalblog.blogspot.in/2010/04/bottled-water-vs-
tap-water-who-wins.html)
5. Why was it necessary to use both distillation and charcoal filtration to
remove the contaminants from drinking water?
Ans. Distillation is the process in which water is boiled to produce water
vapor. The water vapor then comes in contact with a cool surface where it
condenses to form liquid. But the solutes are usually not vaporized. They
remain in the boiling solution. But distillation does not lead to complete
purification of water, because some contaminants with comparable boiling
points and droplets of unvapourised liquid might be carried with the
steam. Thus charcoal filtration is used. Charcoal is made of elemental
carbon. Carbon filters are efficient for to remove chlorine, mercury, iodine,
and some inorganic compounds as well as many difficult organic pollutants
like hydrogen sulphide (H2S), formaldehyde (HCOH), and volatile orgnanic
compounds (VOCs) (Reference:
http://www.aqsolutions.org/resources/Charcoal_Filtration.pdf)
6. Describe what is meant by a watershed. Name the two types and give
an example.
Ans. A watershed is an area in which all water flowing into it goes to a
universal opening. Watersheds include all surface water and it also
includes lakes, streams, reservoirs and wetlands, as well as all
groundwater and aquifers. The most important function of watershed is to
collect the arriving precipitation and then to dispose it. This is the real
meaning of conservation of soil and water. There are generally two
different classifications used to describe watersheds.
http://cambridgesciencefestivalblog.blogspot.in/2010/04/bottled-water-vs-tap-water-who-wins.html
http://cambridgesciencefestivalblog.blogspot.in/2010/04/bottled-water-vs-tap-water-who-wins.html
http://www.aqsolutions.org/resources/Charcoal_Filtration.pdf
One type of watershed is called a major drainage divide. For example,
Drainage divide is present between the Yellow River (Huang He) basin and
the Yangtze River in China but they both have the same outlet.
The other type of drainage divide is called a minor drainage divide. An
example of this situation is shown with the Mississippi and Missouri Rivers.
(Reference: Briney Armanda, Watersheds,...