Biology Form 4 Chapter 9 : 9.2-9.3 Endangered Ecosystem

1. BIOLOGY FORM 4
CHAPTER 9
9.2 ENDANGERED ECOSYSTEM

2. Depletion of Atmospheric Ozone
 Life on Earth is protected from the damaging
effects of UV radiation
 By a protective layer of ozone molecules present
in the atmosphere

3. Role of the ozone layer:
absorbs UV rays

4. Earth’s Atmosphere

5. Ozone layer (O3) – in the Stratosphere

6.  Scientists first described an “ozone hole”
 Over Antarctica in 1985; it has increased in size as
ozone depletion has increased
(a) October 1979 (b) October 2000
Figure 54.28a, b

7. HOLE IN THE OZONE LAYER
1999 Sept 2000 Sept 2001

8.  Satellite studies of the atmosphere
 Suggest that the ozone layer has been
gradually thinning since 1975
Figure 54.26
Ozone layer thickness (Dobson units)
Year (Average for the month of October)
350
300
250
200
150
100
50
0
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

9. Chemical
Mechanism
 Different chemicals are responsible for the destruction of
the ozone layer
 Topping the list :
 chlorofluorocarbons (CFC’s)
 man-made, non-toxic and inert in the troposphere
 In the stratosphere are photolysed, releasing reactive
chlorine atoms that catalytically destroy ozone

10. CFC’s destroy the ozone layer (O3)

11. A combination of low temperatures and elevated
chlorine and bromine concentrations are responsible
for the destruction of ozone in the upper stratosphere
thus forming a “hole”. (Kerr, 1987)
www.met.sjsu.edu/~cordero/ education/education.htm

12. Chlorofluorocarbons (CFC’s)
Used in
 Air conditioners
 Refrigerators
 Aerosol spray
 Making plastic foams

14. Chlorine in CFC’s
changes:
ozone into oxygen
and keeps on doing
this

15. What happens if the ozone layer is
destroyed?
Solar UV rays Solar UV
rays

19. Too much ultra-violet light can result
in:
 Skin cancer
 Eye damage such as cataracts
 Immune system damage
 Reduction in phytoplankton
 Damage to the DNA in various life-forms
 this has been as observed in Antarctic ice-fish that
lack pigments to shield them from the ultra-violet
light (they've never needed them before)
 Possibly other things too that we don't know
about at the moment

20. Aquatic
Ecosystems
www.ciesin.org/docs/ 011-558/011-558.html
oceancolor.gsfc.nasa.gov/. ../phyto_zoo.jpg
Krill

21. UV-B radiation is still high on the list for
the decline in amphibians seen around the
world
 Causes damage to many species of
amphibians at every stage of their life cycle,
from egg to adult
 Affects growth and development in larvae
 Causes
 Changes in behavior
 Deformities
 Make amphibians more vulnerable to disease
and death
 In adults, causes retinal damage and blindness

22. Effects on Human
Health
 Over exposure may
 Increase risk of non-melanoma
and
malignant melanoma
skin cancer
Non-malignant
malignant
www.ldeo.columbia.edu/.../ lectures/ozone_health/

23. Over Exposure
 Suppress immune system
 Accelerate aging of skin due high exposure
 Cause an outbreak of rash in fair skinned people due to
photo allergy – can be severe
d

24. Skin Protection
 Protect the skin against the solar radiation using skin
creams with SPF
 The greater the numerical value of the SPF the greater the
protection
 Use lip balm with SPF
 Cover up

25. Manifestations of…
Cancer
Cataracts
Pterygium
brought on by
over exposure to
UV-B

26. Protection
 Sunglasses with 100% UV
block
 Wrap around sunglasses
 Eye protection for children
 Hats

27. What Is Being Done to Counter the
Effects of Ozone Depletion?
 Montreal Protocol (adopted in 1987) – panel of
experts was formed to investigate substances
responsible for hole formation
 Established policies that prevent future use of certain
types of chemicals
 Stipulated that the production and consumption of
compounds contributing towards depletion of ozone in the
stratosphere were to be phased out by the year 2000
(2005 for methylchloroform)

28. To avoid damage by CFC’s:
1. use ozone-friendly
products eg HCFC
2. ban of products
containing
substances that
damage the ozone
layer eg CFC

29. Images of Antarctica Taken Indicate A Slow
Recovery

30. Question:
Give a biological explanation for each of the following
statements.
In many countries aerosols containing
chlorofluorocarbons (CFC’s) have been reduced. (5)
CFCs are very unreactive compounds that spread
through the atmosphere without reacting with other
substances and drift into the upper atmosphere. There
they meet ozone that oxidises CFCs and in doing so is
converted into oxygen. This is causing thinning of the
ozone layer that protects animals and plants from
ultraviolet radiation.
Thus countries are taking measures to reduce the use of
CFCs or substitute CFC with HCFC.

31. THE GREENHOUSE EFFECT

32. Air warms up
inside a
greenhouse

33. The Greenhouse Effect
Some sunlight that hits the earth
is reflected. Some becomes heat.
Some sunlight that hits
the earth is reflected.
Some becomes heat.
Greenhouse gases in
the atmosphere trap
heat, keeping the air
warm.

34. Earth’s Atmosphere
77% N2 , 21% O2, 1% Ar, + trace gases (CO2, CH4, H2O)
Absorbs incoming solar radiation and warms the planet.
Important component of global climate.

35. The Greenhouse Effect
 Earth’s surface receives energy from
2 sources: the sun & the atmosphere
 As a result the Earth’s surface is ~33C warmer
than it would be without an atmosphere
 Thus the atmosphere stores energy
Without atmosphere, average Earth
temperatures would be a cool –17°C!!

36. Animation

37. The Greenhouse Effect

38. The Greenhouse Effect

39. The Greenhouse Effect
Greenhouse gasses
CO2, CH4, N2O, CFC’s, O3, H2O vapor

40. Selected Greenhouse Gases
 Carbon Dioxide (CO2)
 Source: Fossil fuel burning, deforestation
 Methane (CH4)
 Source: Rice cultivation, cattle & sheep ranching,
decay from landfills, mining
 Nitrous oxide (N2O)
 Source: Industry and agriculture (fertilizers)

41. The greenhouse effect

42. Methane is also a greenhouse gas

43. The Greenhouse Effect
The concentration of greenhouse gases, particularly
CO2, is important in global climate regulation
What regulates the amount of CO2??

44. The CO2 Cycle
Sources: volcanism, metamorphism,
respiration, fossil fuel burning,
deforestation
Sinks: photosynthesis, rock
weathering, carbonate deposition,
ocean absorption

45. Greenhouse Effect & Global Warming
 The “greenhouse effect” & global
warming are not the same thing.
 Global warming refers to a rise in the
temperature of the surface of the earth

 An increase in the concentration of
greenhouse gases leads to an
increase in the the magnitude of the
greenhouse effect. (Called enhanced
greenhouse effect)
 This results in global warming

46. The Greenhouse Effect

47. The Greenhouse Effect

48. The Greenhouse Effect
 Melting of icebergs at poles causes sea level
to rise
 Global warming
 Flooding at low land areas
 Drought
 Inland lakes & rivers may dry up & deserts
expand
 Greater climate extremes
 Wind & rainfall patterns may change
 Decline in the yield of crops, water supplies &
forests are altered
 More outbreaks of tropical disease

49. Ice melts as
temperature
rises
 some animals lose
their habitat

50. How can a rise in air temperature be:
1. helpful to plants?
 Higher rate of photosynthesis
2. harmful to plants?
 Lose water and wilt.

51. Mention 4 ways of how release of
greenhouse gases can be reduced
from passenger vehicles

52. 1. Increase number of car-free
days
2. Use public transport

53. 3. Encourage car-sharing

54. 4. Encourage people
to use the bicycle.
- provide lanes &
parking places

55. The Greenhouse Effect
Summary
Greenhouse gases absorb infrared radiation and prevent it
from escaping to space.
Carbon dioxide, methane, and nitrous oxide are very good
at capturing energy at wavelengths that other compounds
Miss.

56. THE END
OF 9.2

57. 9.3 ENDANGERED ECOSYSTEM

59. What is ‘conservation’?
To conserve something means to protect
it and keep it in a healthy state.

60. The Importance of Proper Management of
Development Activities and The Ecosystem
Steps taken to maintain the balance of nature
• Enforcement of the environmental laws
• Environmental Quality Act 1974
- Controls & prevents the pollution of the environment.
- Controls the type of licensing, content & quality of
environment
- Tests & examines the samples of substances &
disposal of smoke and gas from industries
• Factories and Machinery Act, 1967/1983
• Pesticides Act, 194
• National Forestry Act, 1984

61. Use of Technology
• Use modern equipments & chemicals to control oil
spills
• Recycle rubbish
• To look for methods to do research
• Change organic rubbish to biogas
• Use less polluting & clean fuels in motor vehicles
• Control & treat the toxic and dangerous waste
before disposing

62. Remember the 3R’s with regards to
waste management

63. Some landfill sites are engineered
 To capture methane
 methane is used to
generate energy

64. To reduce pollutants in air, cars are fitted
with: 1. Filters – diesel engines

65. 2. catalytic converters – petrol engines
Normal exhaust consists of:
 unburnt petrol
 carbon monoxide
 oxides of nitrogen
The catalytic converter causes a reaction between these badly
polluting exhaust gases to produce harmless gases which
include:
 nitrogen
 oxygen
 carbon dioxide
 water vapour

66. To reduce pollutants in air,
chimneys are fitted with
filters

67. Education
• To increase the awareness and sensibility of the
individual to the environment.
• To provide the basic knowledge of environmental
problems and effects of pollutions
• To teach the public the necessary skills to protect
and maintain a healthy society
• To help the individuals to become responsible and
sensitive to the environment.

68. Three ways to reduce soil erosion:
1. contour ploughing - ploughing around hill
instead of up-down
Ploughing vertically
increases soil erosion.
Contour ploughing
reduces soil erosion.

69. Water settles in furrows.

70. 2. strip cropping
alternate strips of crops are planted in the same field

71. Crops are planted:
2. at right angles
to the wind
direction.
1. following the natural
contours of the land.

72. 3. terracing

73. Preservation And Conservation Of
The Ecosystem
• Force the development companies to
replant forest trees after reforestation.
• Retain mangrove swamps
• Restore mining & used land for
agriculture
• Clean rivers

74. Ways to conserve the environment:
1. Setting up of
nature reserves
to protect
endangered
species

75. What are ‘endangered species’?
Endangered species are present in small
numbers that risk extinction.
e.g. of endangered species in Malta:
Great white shark Basking shark
A great white shark was caught in Malta by
Alfredo Cutajar in April 16, 1987. This shark was
also estimated to be around 7.13 m (24 ft).

76. Ways to conserve the environment:
2. Setting up laws to prevent
overhunting and overfishing.
Police stop illegal bird
trapping in Malta

77. Overhunting/overfishing is when more
individuals are caught than nature can replace
Bison skulls
(1890)

78. Overhunting/overfishing is when more
individuals are caught than nature can replace
Overfishing of cod.

79. What are ‘protected species’?
Species that cannot be caught, sold or killed
Examples:
 Dolphins
 Turtles
 Frogs
Narcissus
Loggerhead turtle [Narcis]

80. Maltese Rock Centaury
Widnet il-Bahar
Blue Rock
Thrush 'Merill'
Sandarac gum tree is-
Sigra tal-Gharghar

81. Ways to conserve the environment:
3. Helping rare animals to reproduce in zoos to
prevent their extinction.
Artificial insemination of a
panda in a zoo.

82. 4. Afforestation:
the planting of trees

83. Ways to conserve the environment:
5. When fishing, nets
must have large
holes to let the
young escape.

84. Practice Biological Control
 Method-Controlling animal pests by using natural
predators instead of chemical substances.
How to choose:
 -the predators do not cause infection / disease
 - the predators don’t eat other organisms in the
same habitat.
Eg.
 Owls & rats in oil palm estates
 Guppy fish & mosquito larvae in water
 Ichneumon(female) & caterpillars in the paddy
stems

85. We can get rid of pests by:
1. x Chemical control:
 spray with chemicals
2./ Biological control:
 making use of other organisms which kill
the pest

86. Eficient Use Of Energy & Use Of Renewable
Energy
• Energy plays an important role in our life
• Non-renewable energy will be exhausted in
one day. Eg. Coal, oil & fossil fuels
• Solar energy replace fuels
• Renewable energy eg. Solar , wave & tidal
power are environmentally friendly & need
to be developed.

87.  Clean energy

88. Solar energy
Wind energy

89. THE END
OF 9.3