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ESS IB, all the Case studies with Complete Solutions
Evaluate the uses of DTT. - -Pros:
- Relatively cheap
- Highly persistent so that it continues for months
after application to kill insects such as mosquitoes
that carry disease
- Used to virtually* eliminate malaria dengue fever
and filariasis*
- Estimated to have *saved about 50 million human
lives* and to have prevented more than *a thousand
million* human illnesses
Cons:
- kills all insects that come in contact with it.
- thinning birds' eggshells; reducing their population
numbers
- it is *persistent* -> fall into the food chain =>
*bioaccumulate and biomagnified*
- affect the development of children e.g in *Yaqui
Valley, Mexico*
More detail:
https://old.iupac.org/publications/cd/essential_toxicol
ogy/IUPACDDTcase.pdf
Evaluate a named historical event that lead to the
banning of DTT. - -*Rachel Carson: Silent
Spring* - *1962*: Shows the impacts of DTT on the
environment and human's health.
Leading to the ban of DTT by world agriculture in
*2001*
Pros:
- reduce/stop biomagnification of DDT
- improvement in child's development
- reduce cancer, asthma, pregnancy loss
- environmental system can recover
Cons:
- Malaria risk increases; more death
- Fewer affective alternative for DDT
- Alternative pesticides are more expensive
Outline the water conservation strategies with
reference to a named example. - -*Singapore
water conservation strategies*
1. Follow the scheme of *conserve, value, enjoy*
2. Increases the *pricing* of water
The Singapore's National Water agency - *PUB* has
helped by:
1. *Educate* the population about ways of reducing
water demand while doing different activities at home,
school, workplace...
2. Provide *water saving kits* for free: help to control
the flowing rate of water
3. Develop a * water efficiency labelling scheme* on
the products such as washing machines: more ticks =
more water efficient
Describe and evaluate *the sustainability of
freshwater resource usage* with reference to a case
study. - -• *Middle East Water shortage*:
o Area contains only *0.5% of the world's freshwater
supply and 5%* of the world's population.
o Major drought in *2008 in Israel*. Forced to stop
pumping from sea of *Galilee* and draw from aquifers
instead.
Did not restrict water supply to its neighbor *Jordan*.
Israel has *two desalination plants* that supply *one
third* of used water for households.
Potential future conflict over water supplies.
"Discuss, with reference to a case study, the
controversial harvesting of a named species." -
-*Salmon farming in British Columbia, Canada*
- overfishing in the sea -> not enough salmon to meet
the damands
- salmon farms increase; causing pollution
1 . chemicals used in the farm to kill lices are toxic;
fishes in the surrounding area have *high level of
tumours lesions and I-parasite*
2 . Food web is affected
3. . When drug *loss efficiency* -> lices may become
*stronger*-> affect wild salmon population
4. *Genetically modified* farmed-fishes escape into
the wild; interbreed with wildfish -> reduce their ability
