1.4.9 Human Impact on an Ecosystem 1

Pollution

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Human Impact on Ecosystems

We are going to look at 3 ways that humans affect ecosystems:

1. Pollution2. Conservation3. Waste Management

Note: from Syllabus Clarifications – Pollution must be related to habitat studied.

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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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Some types of Pollution

Industrial/Air Pollution

Domestic Pollution

River/Water Pollution

Agricultural Pollution

– slurry, if it gets into a river/pond

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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 & GuidelinesThe 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 pollutants available.

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Effect of one pollutant from one area- Agricultural, Industrial or Domestic

Area Pollutant Source Effects

Agricultural Slurry & Fertiliser

Washed or leached from land

Formation of algal blooms and eutrophication

Industrial Sulphur dioxide

Burning fossil fuels

Forms ‘acid rain’More detail later

Domestic Plastic bags ShoppingNon-biodegradable 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.

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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 Plastic bags Bag tax/levy. Reuse/Recycle 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.

NoExplanation: Pollutants are produced by human activities•CO2 from respiration is not a pollutant

•excess CO2 from burning fossil fuels is

Ecological impact of one human activity

Burning Fossil Fuels

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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 carried far by the wind

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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 suppliesSoil 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 checkWhat is acid rain?•Acid rain refers to very acidic rain with a pH of 4.5 or lessHow 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)•The resulting rain is acid rain

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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 checkList some of the effects of acid rain•Reduces soil pH•Phosphorus (P) becones 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•Burns the leaves of plants

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Need to know

• 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.Go to next topic

Conservation

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END