1.4.9 Human Impact on an
Ecosystem 1
Pollution
Need to know
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Define the term: Pollution.
State areas affected by pollution.
State mechanisms to control pollution.
Explain the difference between the terms
pollutant and pollution.
• Discuss the ecological impact of one human
activity.
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Pollution
What it is
Types of pollution
Pollutants
Effects of pollutants
Control of pollutants
Ecological impact of one human activity
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Pollution
Pollution is any human addition
(contamination) to a habitat or the
environment that leaves it less able to
sustain life.
It is the most harmful human impact and
affects air, fresh water, sea, soil and land.
Chemicals of human origin that harm the
environment are called pollutants.
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Industrial/Air
Pollution
Agricultural
Pollution
– slurry, if it gets
into a river/pond
Some types of Pollution
Domestic
Pollution
River/Water
Pollution
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Learning check
Explain the difference between Pollution and
Pollutant
Pollution is any human addition
(contamination) to a habitat or the
environment that leaves it less able to
sustain life.
Pollutants are chemicals of human origin that
harm the environment.
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Pollutants
are produced by human activities
• CO2 from respiration is not a pollutant –
why?
• excess CO2 from burning fossil fuels is
• SO2 from marshes & volcanoes is not –
why?
• SO2 from factory chimney is
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Pollutants
Some pollutants are normally present in an
environment, e.g. CO2, but levels are
increased by human activity.
Other pollutants never exist in an environment
e.g. oil slick, CFCs
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Learning check
List some types of pollution
•Industrial
•Agricultural
•Domestic
•River/Water
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From the Syllabus & Guidelines
The Syllabus states: “Study the effects of
any one pollutant.”
The Guidelines for Teachers states: “Give
the effects of one pollutant from any of the
following areas: domestic, agricultural,
industrial.” and
“Give an example of one way in which
pollution may be controlled in the selected
area.”
What follows is only a sample of the
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pollutants available.
Effect of one pollutant from one area
- Agricultural, Industrial or Domestic
Area
Pollutant
Source
Effects
Washed or Formation of algal
Slurry &
Agricultural
leached
blooms and
Fertiliser
from land eutrophication
Forms ‘acid rain’
Sulphur
Burning
Industrial
dioxide
fossil fuels More detail later
Non-biodegradable
Domestic
Plastic bags Shopping Suffocate small
animals, Litter
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Eutrophication & Algal bloom
eutrophication: a condition where lakes
become over-enriched with nutrients,
resulting from excess artificial fertilisers
washed into rivers and lakes.
There is a rapid increase in the growth of alga
(algal bloom) as they use up the nutrients.
When all the nutrients are used up the algae
die and are broken down by bacteria, which
use up the oxygen in the water resulting in
the death of aquatic organisms such as fish.12
Eutrophication of a River
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Control of Pollutants
in the selected area - Agricultural, Industrial or Domestic
Area
Pollutant
Control Measures
Agricultural
Slurry &
Fertiliser
Avoid spreading these:
• on wet, waterlogged, frozen
or steeply sloping land
• within 1.5m of any
watercourse.
Industrial
Sulphur
dioxide
Fit catalytic scrubbers in
factory chimneys
Domestic
Bag tax/levy. Reuse/Recycle
Plastic bags
bags
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Learning check
CO2 is produced by all living things as a reuslt
of respiration. Is CO2 a pollutant? Explain
your answer.
No
Explanation: Pollutants are produced by
human activities
•CO2 from respiration is not a pollutant
•excess CO2 from burning fossil fuels is
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Ecological impact of one
human activity
Burning Fossil Fuels
Acidic oxides and acid rain
• All rain is acidic – but not the same pH
• CO2 in the air dissolves in rainwater to form
carbonic acid – pH = 5.5 in unpolluted air
• Acid rain refers to very acidic rain with a
pH of 4.5 or less (Note: pH 4.5 is 10 times
more acidic than pH 5.5)
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Acid rain
• Burning of fossil fuels (e.g. …) releases
acidic oxides into the air, especially SO2
and nitrogen oxides (NOx)
• SO2 dissolves in rainwater to form
sulphurous acid (H2SO3) or reacts with
particles in the air to form sulphuric acid
(H2SO4)
• The resulting rain is very acidic and can be
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carried far by the wind
Effects of acid rain
• Reduces soil pH
• Phosphorus (P) binds to soil particles and is
unavailable to plant roots
• Al becomes soluble and poisonous and with
K, Ca and Mg is washed (leached) from the
soil into lakes and water supplies
Soil is impoverished and fish die in highly
mineralised water. Why?
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Effects of acid rain
• Erodes limestone buildings
• Causes breathing difficulties – irritates the
delicate lining of the lungs
• Inhibits chlorophyll formation and burns the
leaves of plants
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Learning check
What is acid rain?
•Acid rain refers to very acidic rain with a pH
of 4.5 or less
How is acid rain formed?
•Burning fossil fuels releases SO2 and nitrogen
oxides (NOx)
•SO2 dissolves in rainwater to form sulphurous
acid (H2SO3) or reacts with particles in the air
to form sulphuric acid (H2SO4)
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•The resulting rain is acid rain
Effects of acid rain
Acid rain is a ‘trans-boundary problem’ i.e. it
is formed in one country but transported or
blown huge distances to another.
Norway ‘imported’ its acid pollutions from
the English Midlands and the Ruhr valley in
Germany.
• Ireland is lucky that the prevailing winds
are from the Atlantic and not from Europe.
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Dealing with acid rain
• Reducing the quantity of fossil fuels burned
• Using catalysts to treat chimney gases
(‘scrubbers’ are fitted to the insides of
chimneys)
• Catalytic converters fitted to modern cars
• Developing alternative ‘clean’ energy
sources
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Learning check
List some of the effects of acid rain
•Reduces soil pH
•Phosphorus (P) becomes unavailable to plant
roots
•Al, K, Ca and Mg is washed (leached) from the
soil into lakes and water supplies
•Fish die in highly mineralised water
•Erodes limestone buildings
•Causes breathing difficulties
•Inhibits chlorophyll formation
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•Burns the leaves of plants
END
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