Human impact on Ecosystems

1. CHAPTER 22
Our
Impact
on the
Ecosystem

2. Learning Outcomes
After this section, you should be able to:
• evaluate the effects of deforestation and
uncontrolled fishing practices;
• evaluate the effects of water pollution by sewage,
fertilisers and inorganic waste; and
• understand the phenomenon of bioaccumulation.
22.1 How Do We Affect the Ecosystem?

3. CHAPTER 22.1
i. Effect of Water
pollution Due to
Untreated Sewage

4. 22.1
Pollution is the process whereby harmful substances
are added to the environment.
Substances that cause pollution are terms pollutants
Pollution
How Do We Affect the Ecosystem?
Water pollution is the contamination of water
bodies.
It can be caused by:
(a) discharge of untreated sewage into water bodies,
(b)dumping of inorganic waste material into water
bodies.
(c) excessive use of fertilisers and insecticides

5. 22.1
(a) Untreated sewage
• Sewage refers to waste materials from homes and
industries.
• Untreated sewage may contain disease-causing
bacteria and that can result in epidemics if discarded into
water bodies. (e.g Chlolera)
How Do We Affect the Ecosystem?
• Untreated sewage also contains phosphates and nitrates
that can lead to eutrophication.

6. 3. The dead bodies of the
algae and aquatic plants
are decomposed by
bacteria.
4. Bacteria grow and
multiply rapidly, using up
the oxygen in the water.

10. 22.1
microQuestion
How Do We Affect the Ecosystem?
1. Excess phosphates, from fertilisers used in agricultural
farms, are a common water pollutant that result in algae
blooms. Algae blooms lead to the death of submerged
aquatic plants. Which of the following factors causes the
death of the submerged aquatic plants?
A) Too much bacteria
B)Too much carbon dioxide
C)Lack of sunlight
D)Lack of oxygen
( )

11. 22.1
Inorganic waste includes poisonous metals (e.g.
mercury, arsenic and cadmium) and some types of
pesticides.
(b) Inorganic waste
How Do We Affect the Ecosystem?
• Poisonous metals that are dumped into rivers or
lakes are extremely harmful to humans.
• A tragic example would be the case of mercury
poisoning in 1971 in Minamata, Japan.

12. 22.1
Mercury poisoning at Minamata Bay, Japan in 1971.
How Do We Affect the Ecosystem?
A plastic factory
discharged waste
water containing
mercury into
Minamata Bay.
Mercury was
absorbed by the
water weeds.
The water weeds
were eaten by fish.
Fish caught
contained high
concentrations
of mercury.
Villagers ate the
contaminated fish
and suffered from
mercury poisoning.
http://www.youtube.com/watch?v=ihFkyPv1jtU

13. 22.1
(c) Chemical fertilisers
How Do We Affect the Ecosystem?
• Chemical fertilisers that contain nitrates and phosphates
are used to increase crop yield.
• Excessive use of these fertilisers can lead to a phenomena
called eutrophication.
Excess fertilisers
are washed into a
water body.
Nutrients in fertilisers increase the growth of
algae and water plants in the water body.
Submerged plants die due to lack of sunlight.
Bacteria grow rapidly and use up dissolved
oxygen as they decompose the dead plants.
Other organisms
die due to lack of
oxygen.

14. CHAPTER 22.2
Effect of
Pollution Due
to Insecticides

15. Effect of Pollution Due to Insecticides
Insecticides
contain
inorganic waste
substances that
are non-
biodegradeable
Insecticides
contain
inorganic waste
substances that
are non-
biodegradeable
22.2
DDT cannot be
excreted but instead
stored in the fatty tissue of
the organism.
Furthermore, organism
cannot breakdown the
DDT.
DDT cannot be
excreted but instead
stored in the fatty tissue of
the organism.
Furthermore, organism
cannot breakdown the
DDT.
Hence it got accumulated in the body of the consumers,
increasing in concentration in the bodies of organisms

16. • Insecticide can enter the food chain by the aquatic
plant absorbing it.
•
• When the primary consumer feeds on the plant, the
insecticide is transferred from the plant into the body of
the consumer.
• Since the DDT is insoluble and is stored in the fatty
tissues of organisms, it will be accumulated in the
organism and pass down to the next higher trophic
level in the food chain.
Effect of Pollution Due to Insecticides
Bioaccumulation
22.2

17. • The insecticide
concentration
increases and
remains highest in
the bodies of the
final consumers.
22.2

18. Example: Agent Orange used in Vietnam War
http://www.youtube.com/watch?v=kkbnFfldsOcWatch this:

19. 22.2
Bioaccumulation:
Chemicals that are not excreted, accumulate in bodies
of organisms that consume them.
1
1
1
1
1
5
15
45
15
15
5
5
The chemicals are then passed along the food chain and
become concentrated in the bodies of the final consumers.
Effect of Pollution Due to Insecticides

20. The 1986 Chernobyl disaster triggered the release of substantial amounts of radioactivity into the
atmosphere. It is one of the most significant unintentional releases of radioactivity into
the environment to date.

21. Fukushima
Nuclear Plant Explosion

22. How does this affect the food chain?
http://www.whoi.edu/oceanus/feature/how-is-fukushimas-
fallout-affecting-marine-life

23. 22.2
microQuestion
How Do We Affect the Ecosystem?
2. In recent years, lakes in many parts of the world have
become more acidic. What has caused this change?
A) Air pollution by sulfur dioxide
B) Deforestation
C) Increased use of insecticides
D) Increased use of nitrate fertilisers
( )

24. 22.2
microQuestion
How Do We Affect the Ecosystem?
3. Which property of modern insecticides helps to keep
environmental pollution at the lowest level?
A) They accumulate in the bodies of the prey.
B) They are biodegradable.
C) They are easily soluble in water.
D) They are easily taken up by the plant roots.
( )

25. 22.2
microQuestion
How Do We Affect the Ecosystem?
4. Discuss how overuse of fertilizer on the agriculture land
has a negative impact on aquatic biodiversity.
…………………………………………………………………
…………………………………………………………………
…………………………………………………………………
…………………………………………………………………
…………………………………………………………………
……………………………………………………………….[4]

26. CHAPTER
22.3
Conservation

28. Learning Outcomes
After this section, you should be able to:
• discuss reasons for conservation of species with
reference to the maintenance of biodiversity;
• outline the roles of microbes in sewage disposal as
an example of environmental biotechnology; and
• discuss the conservation of species with reference
to management of timber production and fisheries.
22.3 Conservation

29. 22.3
Natural resources
Renewable
- can be replaced via
natural cycles as long
as they are not
overused
Examples: Air, water,
soil, and wildlife
Non-renewable
- cannot be replaced
once they are used
Examples: Fossil fuel
and minerals
Conservation

30. 22.3
Forest is a :
• Major source of oxygen
• Help to moderate the water
• Protection of soil
Management of Timber Production
Conservation

31. 22.3
• Law is introduced to restrict the number of
trees felled for timber. Tree below the
stipulated measurement are not allowed to be
cut.
• New seedling are planted to replace those
trees that were cut down for timber
(reforestation).
• Setting up of forest reserves that prohibit
felling of tree for timber to maintain the
Management of Timber Production
Conservation
Ways

32. 22.3
• destroy coral reefs and
organisms that live on the
sea bed
Fishing techniques that are detrimental to the
aquatic environment involve the use of:
1) Dredges:
2) Drift nets and trawlers:
• catch marine life indiscriminately
drift net
dredge
dredger
trawler
Management of Fisheries
Conservation

33. 22.3
• Fish is an important food source for humans.
• As the human population increases, the
demand for fish increases.
• Uncontrolled and unregulated fishing can
result in reduced aquatic biodiversity.
• Fishing ground are carefully manage to
prevent over-fishing and indiscriminate fishing
Management of Fisheries
Conservation

34. 22.3
•Banning of drift nets which traps all form of marine life
•Impose law to use nets of certain mesh size so that young
fish are not caught
•Regulating ship entering fishing group
•Limit period of fishing
•Ban harvesting of endangered species
•Building of hatcheries to artificially raise endangered fish
Management of Fisheries
Conservation
Ways

35. CHAPTER 22.4
Main Reason
for
Conservation

36. http://www.babble.com/pets/10-extinct-animals-my-kids-will-
never-see/

37. 7 Main Reasons for Conservation
1. Prevent extinction of plant & animal species.
2. Maintain large gene pool.
3. Ensure conservation of marine life because
they are a major source of food.
4. Preserves natural scenery & wildlife for people
to appreciate

38. 5. Conservation is of scientific values
6. Maintain biodiversity because many
plants are of great economic importance
as sources of raw materials for drugs &
food.
7. Maintain stable and balanced ecosystem.
7 Main Reasons for Conservation
22.4

39. Maintenance of
a large gene
pool
Prevents
extinction of
animal and
plant species
Preservation of
natural scenery
and wildlife
Scientific value
Studies on wildlife
give us insight on
human beings
Maintenance of
biodiversity
Maintenance of a
balanced
ecosystem
Economic importance
Rainforests are a source
of raw materials for
industries
Food source
Marine life are a
major source of
human food
22.4
Reasons for
conservation
Main reason of Conservation

40. 5(a) Discuss the effects of deforestation on ecosystem.
………………………………………………………………………………
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………………………………………………………………………… [3]
(b)Explain the importance of preventing any species from being
extinct.
………………………………………………………………………………
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………………………………………………………………………………
………………………………………………………………………… [3]
Main Reasons for Conservation
22.4
microQuestion

41. CHAPTER 22.5
Environment
Biotechnology

42. Singapore new water reclaimation
plant@Jurong:
http://www.youtube.com/watch?
v=7xoWmXO0GfM
Source:
http://www.pub.gov.sg/LongTer
mWaterPlans/gwtf.html

43. 22.5
Wastewater treatment process
Environment Biotechnology
Wastewater is
channelled into
water reclamation
plants.
Heavy solids settle to the
bottom of the tank and
are removed as sludge.
Wastewater
enters the
primary
settling
tank.

44. 22.2 Conservation
Sludge is treated in anaerobic
digesters before being dewatered
and disposed into a soil container.
Sludge removed
from primary
settling tanks
Sludge removed
from final settling
tanks
Wastewater treatment process

45. 22.5
Partially treated
wastewater is
transferred to the
aeration tank and
mixed with bacteria.
The bacteria breaks down
the organic pollutants into
harmless substances.
Treated
wastewater is
discharged
into the sea.
Wastewater is sent to
final settling tank
where the bacteria are
removed.
Wastewater treatment process
Environment Biotechnology

46. 22.5
• Used water (i.e. sewage) has to be treated before being
removed
• The usage of microorganisms in sewage treatment helps
to speed up the water treatment process.
Environmental biotechnology refers to the use of
biological sciences to provide environmentally
friendly solutions in reducing pollution.
Example:
Environment Biotechnology

47. 1. Primary settling tank
• Used water enters the primary settling tank.
• Heavy solids settle to the bottom and removed as
sludge.
• Sludge is treated in the anaerobic digesters and
dewatered and disposed of as a soil conditioner
(fertilisers).
Environment Biotechnology22.5

48. 2. Aeration tank
•Air is mixed with bacteria.
•Oxygen present allow Aerobic Respiration to take place
in the bacteria
•Bacteria secretes enzymes to digest organic pollutants into
harmless soluble substances and carbon dioxide.
3. Final settling tank
•Microorganisms are removed from the treated water.
•
Environment Biotechnology22.5

49. 22.5
microQuestion
6. Untreated sewage is continuously discharged into a river at point
X.
Which graph shows the effects on the concentrations of oxygen and
bacteria?
Environment Biotechnology
D
(apparently no
answer )

50. 22.5
microQuestion
7.Which of the following shows the process of sewage
treatment in the correct order?
A) Primary settling tank  final settling tank  aeration tank
 sea
B) Primary settling tank  aeration tank  final settling tank 
sea
C) Primary settling tank  aeration tank  sea  final settling
tank
D) Aeration tank  primary settling tank  final settling tank 
sea
( )
Environment Biotechnology