science f5 chapter 3

8/2/2019 Science F5 Chapter 3

1/24

Chapter 3

Preservation and Conservation

of the Environment

Science Form 5


2/24

Balance in Nature

Definition: condition in which all interactionsamong living organisms and non-living thingsare able to provide the living organisms with

their daily basic needs. Can be maintained through natural cycles. Eg.

nitrogen cycle, carbon cycle and water cycle.

These cycles are able to recycle all basic needsuch as oxygen, nitrogen, carbon, water andminerals needed


3/24

Nitrogen cycle


4/24

Carbon

cycle


5/24

Water cycle


6/24

Environmental pollution

Pollution = existence of pollutants in theenvironment in quantities so large that livingorganisms and the environment are harmed

and thrown into disorder


7/24


Source ofpollution

Pollutant Effect

Uncontrolled useof fossil fuels

Acidic gases (sulphurdioxide, nitrogen dioxide,carbon dioxide)

Hydrocarbons & smoke

Produce acid rainthat damage trees,aquatic ecosystems& buildings

Acidic gases corrodethe respiratorytract of organisms

Smoke particlescause asthma & lung

disease


8/24


Source ofpollution

Pollutant Effect

By-productsfrom factories

Toxic waste (heavymetals)

Radioactive materials Smoke Heat

Damage the nervoussystem & cause deformedbabies (Minamatadisease)

Cause mutation & cancers Cause respiratory & lung

diseases Destroy aquatic

ecosystems


9/24


Source of

pollution

Pollutant Effect

Agriculturalindustry

Excessive chemicalfertilisers

Excessive pesticides& fungicides

Excessive fertilizers thatflow into rivers causewater pollution and algae togrow rapidly

Cause damage in the liver,foetal deformation &infertility


10/24


Source ofpollution

Pollutant Effect

Vehicles andmachinery

Poisonous gases (carbonmonoxide, sulphurdioxide, nitrogen oxides)

Smoke Lead Noise

Cause carbonmonoxide poisoning

Acidic gases such as

sulphur dioxide &nitrogen oxide causeacid rain

Smoke particles causeair pollution

Cause nerve and braindamage

Cause noise pollution


11/24


Source ofpollution

Pollutant Effect on environment& human health

Improperdisposal ofrubbish

Plastic materials Leftover food and

sewage

Non-biodegradableitems take up spacein dump sites andcause air pollution ifburnt

Attract vectors &encourage the spread

of diseases


12/24


13/24


Environmental pollution has thefollowing negative effects onenvironment:

a. Decline in human health

b.Loss of economic resourcesc. Damage to natural habitats

d.Extinction of species

e. Damage to the beauty ofnature


14/24

Global warming

Definition: an increase in the globaltemperature

Caused by greenhouse effect

Greenhouse effect = natural phenomenon thatkeeps the Earth warm

A rapid increase in carbon dioxide (main

greenhouse gas) produced by human activitiescauses more heat than usual to be trapped inatmosphere


15/24

Global warming

Effects:

a. Increase in average global temperature

b.Ice at the poles melts faster & increase sealevels

c. Flooding in low-lying areas

d.Increase in extreme weather phenomena


16/24

Global warming


17/24

Thinning of the ozone layer

An ozone molecule is made up of 3 oxygen atoms

Ozone molecules form the ozone layer surroundingthe Earth & prevent harmful ultraviolet rays from

reaching the Earths surface CFC is used in air-conditioners, refrigerators,

aerosol cans & in the making of polystyrene products

The use & release of CFC destroys ozone molecules,leading to the thinning of the ozone layer


18/24

Thinning of the ozone layer

The thinning of ozone layerenables more dangerous ultravioletrays to reach the Earth. Theeffects of this include:

a. Skin cancer

b. Cataract (eye lens becomingopaque)

c. Lowering of body immunityd. Decrease in crops yield

e. More phytoplanktons die (themain products in the sea)


19/24

Pollution control

1. Factories that produce radioactive substances

Build far away from populated areas

Dispose of waste & by-products properly

2. Factory

Build higher chimneys

Install electrostatic precipitators in chimneys toreduce the release of toxic gases


20/24

Pollution control

3. Sewage Channel to proper sewage treatment system

4. Vehicles

Fix catalytic converter in the exhaust system

5. Solid rubbish

Dispose of in properly-run landfills Bury in soil

Turn in compost


21/24

Pollution control

6. Agriculture Use biological controls

Reduce the use of chemicals fertilisers andpesticides


22/24

Proper management ofnatural resources

Naturalresources

Forest

Activity LumberingEffect ofimpropermanagement

affect the weather Soil erosion & floods destroys natural habitats

extinction of speciesPropermanagement

Establish more forest reserves Replanting forests Selective lumbering


23/24


24/24

Proper management ofnatural resources

Naturalresources

Sea

Activity Fishing

Effect ofimpropermanagement

Imbalance in aquatic ecosystems Death of aquatic mammals (e.g.

dolphin)

Propermanagement

Catch only mature fish Encourage the rearing of

freshwater & marine life

science f5 chapter 3

Documents