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3

The Tai Hu () isthe third largest lake

in China.

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4

Algal bloom appearedthere occasionally.

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5

In 2007, the algalbloom was so serious

that the water became

smelly and unsuitable

for use. Many fish die.

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6

Some people claimedthat the algal bloom

was caused by global

warming and

insufficient rain.

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Others suggested thatit was caused by

pollutants.

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What is an algal

bloom1

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9

Why do many fish

die when algal blooms

occur

2

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Why may

global warming and

insufficient rain leadto algal blooms

3

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What types of

pollutants may cause

algal blooms

4

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1.1 Human population growth

The pattern of humanpopulation growth

How has the world

human populationchanged?

1 1 Human population growth

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1.1Human population growth

0 400 800 1200 1600 2000

12

3

45

6

78

9

billionofp

eople

year

population

increased slowly


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0 400 800 1200 1600 2000

12

3

45

6

78

9

billionofp

eople

year

Industrial

Revolution

economic growth

living standard improved


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0 400 800 1200 1600 2000

12

3

45

6

78

9

bi

llionofp

eople

year

Industrial

Revolution

better nutrition, medical care and

sanitation

great decrease in

death rate


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16


0 400 800 1200 1600 2000

12

3

45

6

78

9

bi

llionofp

eople

year

Industrial

Revolution

birth rate remains high

population increased

exponentially


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Human population is

increasing at a rate ofone billion people every

13 years.

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Why is population control

necessary? the earth has limited resources

carrying capacity():the maximum size of population whichthe available resources can support


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increased exhaustion of naturalresources

rapid growth of human population


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environmental degradation

rapid growth of human population


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1.1 p p g

e.g. through birth control methods

and other measures

population controlhelps solve

the problems


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and improved

1Since the Industrial Revolution, thelarge scale use of fossil fuel-

powered machinery has led to greateconomic growth

1.1 p p g

living standard. The death rate

decreases significantly and the birthrate remains high. Thus, the human

population rapidly.increases


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2The rapid growth in humanpopulation will increase the

exhaustion ofnatural resources

and .

can help


1.1 p p g

Population control

ensure a continuous supply of naturalresources for our current needs and

for the future generations.

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1.2 Use of natural resources

What natural resources dowe have?

renewable

resources

()non-renewable

resources

()

1.2 Use of natural resources

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1 Renewable resources

1.2

can be replaced after use

timber fish

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1.2Use of natural resources

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1.2

overexploitation

some non-renewable resources will

soon become depleted even some renewable resources

have become limited


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What are the environmental

impacts of malpractices infisheries?

- heavy demand for fish

as food

- destructive fishing

methods

causes:


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1 Depletion of fish stock

overfishing

humphead wrasse

3/4 of marine fisheries are exploited

up to or beyond the rate that the fish

stock can recover

I may become

extinct!


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2 Killing of non-target species

cyanide fishing

used to stun fish


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cyanide fishingkills large numbers of non-target fish

and invertebrates such as coral


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drift net fishing


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drift net fishingbycatch: dolphins, sea turtles,

seabirds,juvenile fish


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3 Destruction of marine habitats

dynamite fishing and bottom trawling

damage coral reefs()


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4 Disturbance of ecological

balance large decrease in the number of fish

threatens predatorsalters the structure and functioning

of the ecosystems


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impacts of malpractices inforestry?

- heavy demand for land

and timber

- deforestation

causes:


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1 Destruction of natural habitats

forests are clearedreduces biodiversity


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2 Soil erosion

trees are removedtop soilbecomes easily washed away

by rainwater or blown away by wind


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3 Global warming

forests are burnt for land clearingCO2level in the atmosphere increases

greenhouse effect

() is enhancedglobal warming

()


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Greenhouse effect

Solar radiation passes through theatmosphere.

Animation

atmospheresun

earth


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The earths surface absorbs mostradiation and becomes warm.

Greenhouse effect


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Some solar radiation is reflected intospace by the earth and the atmosphere.

Greenhouse effect


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Infrared radiation is emitted fromthe earths surface.

Greenhouse effect


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Some of the infrared radiation is trappedand re-emitted by the greenhouse gases

in the atmosphere.

Greenhouse effect

water vapour

carbon dioxide

methanenitrous oxide

ozone

CFCs


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Greenhouse effect

The earths surface gain more heat.


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Greenhouse effect

a naturalprocess important in maintaining a relatively

stable temperature

however


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Greenhouse effect

There has been an

increasing level ofgreenhouse gases in

the atmosphere.

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Greenhouse effect

the greenhouse effect is enhanced atmospheric temperaturegradually

increases

global warming


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3 Global warming

increases melting of icebergs

loss of habitats

shortage of food


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3 Global warming

rise in sea level

flooding of

low-lying areas

increases melting of icebergs

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3 Global warming

some species may move to higherlatitudes or altitudes

some species may become extinct


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3 Global warming

spread of infectious diseases tonew regions

e.g. malaria and dengue fever


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impacts of malpractices inagriculture?

- clearing large areas of land for

agriculture

- overgrazing

()

causes:


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impacts of malpractices inagriculture?

- extensive use of pesticides

and chemical fertilizers

- use of chemicals in rearing livestock

causes:

- monoculture ()


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1 Destruction of natural habitats

forests are clearedreduces biodiversity


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2 Soil erosion

reasons:i) Clearing forests

ii) Use of chemical fertilizers

iii) Overgrazing

loss of humus

grass is consumed faster

than it can recovery

may lead to desertification 1.2Use of natural resources

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i) Effects of pesticides toxic

3 Chemical pollution

- harm the beneficial insects, aquatic

organisms or humans


DDT

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stable


- the concentration

of the chemicals

accumulated in

organisms increasesup the food chain

DDT

i) Effects of pesticides


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ii) Effects of chemical fertilizers


eutrophication()leaching()

algal bloom()


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algal bloom

- algae uses up the

oxygenat night

suffocation


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algal bloom

- algae prevents

penetration of light

no photosynthesis


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algal bloom

- decomposition

of dead algae by

bacteriafurther

consumes oxygen- bacteria produce

toxic substances

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growth hormones or drugs


- to promote growth

iii) Effects of chemicals used in rearinglivestock

- leakage may cause

unpredictable healthrisk


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antibiotics


- to protect against diseases

iii) Effects of chemicals used in rearinglivestock

- indiscriminate use may speed up

the development of resistancein pathogens


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4 Impact of monoculture

growing the same crop on the same pieceof land for many years

wheat 1.2Use of natural resources

4 f

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i) Increased soil erosion


when a crop is harvested, soil is

left bare


4 I f l

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ii) Depletion of certain minerals fromthe soil


soil becomes infertile

extensive use of chemical fertilizers

can lead to soil erosionand chemical

pollution


4 I f l

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iii) Increased pest population


when the same type of crop is growth

continuously, the peststhat feed on

the crop are readily provided withfood and they grow quickly

removal becomesmore difficult


4 I f l

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iii) Increased pest population


extensive use of pesticides

chemical pollution

development of resistancein pests


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They come from organisms andcan be replaced after use.

a resources1Natural resources:

Renewable


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They cannot be replaced afteruse. They have a limited supply.

b resources1Natural resources:

Non-renewable


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- Heavy demand for fish as

Causes:

2aEnvironmental impact ofmalpractices in fisheries:

food

- fishing methodsDestructive


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- Depletion of

Impact:

2aEnvironmental impact ofmalpractices in fisheries:

fish stock

- Killing of organismsnon-target

- Destruction of marine habitats

- Disturbance of

ecological balance 1.2Use of natural resources

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- Heavy demand for land and

timber leads to

Cause:

2bEnvironmental impact ofmalpractices in forestry:

deforestation


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Impact:

- Destruction of natural

and reduced

habitats

- Soil and increasedrisk of

erosion

2bEnvironmental impact ofmalpractices in forestry:

biodiversity

flooding

- Global warming 1.2Use of natural resources

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- Clearing of large areas of land

for agriculture

Causes:

2cEnvironmental impact ofmalpractices in agriculture:

pesticides

- Overgrazing

- Extensive use of and

chemical fertilizers 1.2Use of natural resources

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- Use of in rearing

livestock

Causes:


- Monoculture

chemicals


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Impact:

- Destruction of natural habitats

and reduced biodiversity

- Soil erosion and increased riskof flooding

-


Desertification 1.2Use of natural resources

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Impact:

- in pesticides

harm other non-target organisms


Toxic chemicals


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Impact:

- Concentration of toxic chemicals

along , causing

harm to consumers attrophic levels


food chains

higher


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Impact:

- Leaching of chemical fertilizers

causes


algal blooms


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Impact:

- The use of

and drugs in rearing livestock

may cause health risks to wildorganisms and humans


growth hormones


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Impact:

- The indiscriminate use of

antibiotics may speed up the

development of inpathogens


resistance


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Impact:

- Increased soil erosion,

of certain minerals from the soil

and increased pest populationdue to


depletion

monoculture

1 3 Environmental effects of

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0

2

4

8

6

1950 1970 1990 2010 2030

1.3 Environmental effects of

urbanization and industrialization

popu

lation(b

illion)

year

world urban

population

world ruralpopulation

1.3Environmental effects of urbanization and industrialization

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require large areas of land

land obtained by land clearance orreclamation

damage the habitats


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pollution


Impact of land clearance1.3Environmental effects of urbanization and industrialization

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Impact of land clearance

and reclamation destructionand loss of habitats

decrease in population of wildlife

Chek Lap Kok Island

was cleared for the

construction of theairport


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and reclamation

decrease in population of wildlife

I lost my

breeding

ground.

destructionand loss of habitats


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and reclamation soil erosionand flooding


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and reclamationreclaimed land


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and reclamation coastal habitatsare

destroyed

dredging()disturbs seabed

habitats and upsetsmarine ecosystems


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suspended mud

particles may clog

the gillsof fish andblock sunlight

dredged materialmay contain toxic

chemicals


and reclamation

Air pollution1.3

Environmental effects of urbanization and industrialization

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Air pollution

major sources:

exhaust fumesand dust

from burning of fossil fuels

Air pollution1.3


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Air pollution

major sources:

exhaust fumesand dust

containair pollutantssuch ascarbon particles, lead particles,

carbon dioxide, carbon monoxide,

sulphur dioxide and nitrogen oxides

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Air pollution1.3


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Air pollution

1 Health problems caused by air

pollutants

lead particles

damage thenervous system

and the kidneys

Air pollution1.3


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Air pollution


pollutants

carbon monoxide

reduces oxygen-carrying capacity

of the blooddizziness and

headaches

Air pollution1.3


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Air pollution


pollutants

sulphur dioxide and

nitrogen oxidesirritation to the

breathing system,heart and eyes

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Normal condition

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sunlightcool air

warm air

Warm air rises, carrying smoke upwards.


Normal condition

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sunlightcool air

warm air

Wind quickly blows smoke away.


Smog formation in windless condition

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sunlightwarm air

cool air

Cool air at ground level forms fog.


Smog formation in windless condition

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sunlightwarm air

cool air

Smoke and pollutants mix with fog

to form smog.

Air pollution1.3


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Air pollution

2 Global warming

carbon dioxide,nitrogen oxidesand

chlorofluorocarbons(CFCs)are greenhouse gases

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Air pollution1.3


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p

3 Ozone depletion

ozone layerscreens the earths surface

from the suns harmful ultraviolet light

destroyed by CFCs

110 220 330 440 550

total ozone

(Dobson Units)

Air pollution1.3


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p

3 Ozone depletion

ozone layerscreens the earths surface

from the suns harmful ultraviolet light

destroyed by CFCs

skin cancer in humans

reduces crop yield

Air pollution1.3


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p

4 Acid rain () sulphur dioxideand nitrogen oxides

dissolve in rain water to form acid rain

lowers pH of surface water and soil

corrodes man-made material

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1.1


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1.1

Design and perform an investigation to

study the relationship between the level of

air pollution and the lichen distribution in

different locations.

1.2


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1.2

Investigation of the air quality indifferent locations

Choose five locations with different levels

of air pollution.

Video

1.2


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A

Investigating the amount of particulatesin different locations

1 Place a microscope slide in a Petri dish.

2 Use a clean brush to smear the upper surfaceof the slide with a thin layer of vaseline.

3 Repeat steps 1and 2to prepare 14 more

set-ups.

1.2

1.2


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4 Put three set-ups in each of the locations.Collect all the set-ups after 24 hours.

5 Cover the microscope slide with a

transparent grid.6 Observe the slide under a microscope.

Count and record the number of

particulates for a total area of 100 mm2

.

7 Repeat steps 5and 6with other set-ups.

1.2


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121

B

Investigating the acidity of air indifferent locations

1 Use three plastic bags to collect three air

samples in location A.2 Tie the open end of the plastic bags.

3 Repeat steps 1and 2to collect air

samples in locations B to E.

1.2


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4 Rinse the probe of the pH meter withdistilled water.

5 Calibrate the pH meter.

6 Add 50 cm3

of distilled water into a beaker.7 Insert one end of a length of rubber tubing

into the plastic bag. Put the other end into

the beaker with distilled water.

1.2


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8 Squeeze the bag slowly so that the air in

the plastic bag bubbles through the distilled

water.

9 Rinse the probe of the pH meter withdistilled water.

10 Put he probe into the distilled water bubbled

with air sample. Record the reading.

11 Repeat steps 6 to 10 with other air samples.

Water pollution1.3


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p

main pollutants:

sewage(), solid wasteand oil


Water pollution

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1 Health problems caused by sewage

discharge

domestic sewagecontains faeces,

urine and dirty water that holdmany bacteria and viruses

p

e.g. acute conjunctivitis ()cholera, dysentery, gastroenteritis

infection and diseases


Water pollution

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discharge

hot water

p

reduces solubilityof oxygen

suffocation


Water pollution

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discharge

hot water

the dead bodies ofmarine organisms

decay and spread

diseases


Water pollution

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discharge

chemical poisoning

- concentrations of cyanidesand heavymetal ionscan increase along the food

chains


Water pollution

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2 Algal bloom

industrial sewageand detergents contain

phosphatesand nitrates

nutrients for algae


Water pollution

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3 Solid waste at sea

harms the habitats and marine organisms


Water pollution

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4 Oil spill

poisonous oil sticks to feathers of

waterbirds

damages the insulation andwaterproofing capability

die of freezing,drowning and

poisoning


Water pollution

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4 Oil spill

oil prevents atmospheric

oxygen from dissolving

into the sea watersuffocation


1.3

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133

Comparison of the oxygen content

of clean and polluted water using a

data logger

Part 1:Computer set-up

1 Connect the data logger interface to the

computer. Turn on the interface and the

computer.2 Connect the dissolved oxygen sensor

to the interface.

Video


1.3

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3 Run the software and open the

pre-configured file.

Part 2:Equipment set-up

1 Use the software to calibrate the dissolved

oxygen sensor.

2 Rinse the dissolved oxygen probe withdistilled water.


1.3

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Part 3:Data recording

1 Put the tip of the dissolved oxygen probe

into the clean water sample.

2 Start recording data by clicking the STARTor REC button on the computer screen.

3 Stir the sample gently with the probe.


1.3

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136

4 Record data for 1 minute and then stop.

5 Rinse the probe with distilled water.

Repeat steps 1 to 4 using the polluted

water sample.


1.3

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Part 4:Data analysis

1 Use the graph display function to display

the data.

2 Calculate the minimum, maximum andmean dissolved oxygen concentration for

each sample using the built-in functions of

the software.

1.4


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138

Design an investigation to study the

types, sources and effects of

pollutants in a freshwater stream or a

shore habitat

1.4


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139

There is a lot

of rubbish.

Its too bad!The stream is

polluted.

1.4


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140

Design and perform an investigation to find

out the types, sources and effects of pollutants

in a freshwater stream or a shore habitat.

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142

Destruction and loss of

2Impact of land clearance on theenvironment:

natural habitats

Soil and floodingerosion


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Destruction and loss of naturalhabitats

3Impact of reclamation on theenvironment:

suffocate

The suspended mud particles

may marine

organisms and block fromlight

penetrating into the water 1.3Environmental effects of urbanization and industrialization

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The toxic chemicals releasedfrom the dredged material may

3Impact of reclamation on theenvironment:

poison marine organisms

4Urbanization and industrialization

produce many .pollutants


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released from the

burning of fossil fuels in vehicles,

power plants and factories

aSources of pollutants

5Air pollution:

Exhaust fumes

Dust produced in constructionsites


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caused by

air particulates such as carbon

particles

5Air pollution:

Respiratory illnesses

kidneys Damage to nervous system and

by lead particles

bEffects on human health


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Irritation of the system,

heart and eyes by sulphur dioxide,nitrogen oxides and

Dizziness and headaches due to

5Air pollution:

carbon monoxide

breathing


smog

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formation due to the

release of sulphur dioxide and

nitrogen oxides

5Air pollution:

Acid rain

cEffects on the global environment


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sewage containing

inorganic nutrients, bacteria,

viruses and organic waste

aSources of pollutants

6Water pollution:

Domestic

sewage containingtoxic chemicals and hot waterIndustrial

Oil spill


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by bacteria and viruses


6Water pollution:

Infection

Hot water causes marine organisms

to ; the dead bodies

decay and spread

suffocate

diseases


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Chemical poisoning, accumulation

of mercury ions in body tissues

through feeding


6Water pollution:

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What is an algal bloom?1Algal bloom is the rapid growth of

algae resulting from an increase innutr ient supply in water.

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Why do many fish die when algal

blooms occur?2The f ish die of suffocation as the algae

use up the oxygen in the water at night.

When the algae die, their

decomposition further consumes the

oxygen in the water.

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Why may global warming and

insufficient rain lead to algal blooms?3The growth of the algae may be

promoted by an increase in

temperature, together with high

concentrations of nutr ients in the lake

due to insuff icient rain.

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What types of pollutants may cause

algal blooms?4Sewage from homes, farms andfactories contain many nutr ients for

the growth of algae.

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are mainly caused by

Human impact on the environment

urbanizationand

industrialization

rapid humanpopulation

growth

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rapid human population growth

leads to

overexploitation of resources

types of natural resources include

non-renewable

resources

renewable resources

depletion

overexploitation

will soon lead to

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may be exploited due

to malpractices in

renewable resources

agriculturefisheries

lead to

forestry


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obtain land from

land clearance and reclamation

lead to


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such as


disturbanceof ecological

balance

soilerosion

pollution

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including

pollution

water pollutionair pollutionmay result in

global warming

and acid rain

may result in

algal bloom

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