11 Pollution

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- GCSE Bitesize - Pollution

//www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollutionrev_print.shtml[10/21/2013 8:15:49 PM]

Science

Pollution

Human beings compete with other living things for

resources and space. As the worlds population continues

to increase, and standards of l iving improve, there isserious danger of a permanent change to the global

environment.

Human activities have led to the pollution of the

environment, particu larly in water and the air.

Eutrophication is one example of this.

Global population change

Population growth

Like all living things, humans exploit their surroundings for

resources. Before the beginning of agriculture about 10,000

years ago, small groups of humans wandered across large

areas, hunting and gathering just enough food to stay alive.

Population numbers were kept low because of the difficulty of

finding food.

The development of agriculture led to a population explosion that

has accelerated enormously during the past 500 years. Unlike

other species, humans can adapt to and survive in almost all

habitats and climates.


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Standards of living

People in the developed world enjoy a high standard of living,

with abundant food, cars and comfortable housing. People in the

developing world have a lower standard of living, but many

countries are catching up quickly.

Impact of humansThe worlds human population has passed 6 billion and

continues to increase. The growth in the human population and

the increase in the standard of living are putting strains on the

global environment. Here are some of the ways in which this is

happening:

non-renewable energy resources, such as coal, oil and

natural gas, are being used up rapidlyraw materials are being used up rapidly

more waste is being produced

more pollution is being caused.

Air pollution

The most common source of air

Human population growth over the past 10,000 years


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pollution is the combustion offossil

fuelsfossil fuels : Fuels such as

coal, oil and natural gas, made from

the remains of ancient plants and

animals.. This usually happens in

vehicle engines and power stations.

Some common air pollutants and their effect

pollutant typical effect

smoke deposits soot on buildings and trees, causing

them damage. Permeates the air, making itdifficult for living creatures to breathe.

carbon

monoxide

poisonous gas

carbon

dioxide

greenhouse gas that contributes to global

warming

sulfur

dioxide

contributes to acid rain

Indicators of air pollution

Lichens are plants that grow in exposed places such as rocks or

tree bark. They need to be very good at absorbing water and

nutrients to grow there, and rainwater contains just enough

nutrients to keep them alive. Air pollutants dissolved in

rainwater, especially sulfur dioxide, can damage lichens, andprevent them from growing. This makes lichens natural

ndicators of air pollution. For example:

bushy lichens need really clean air

leafy lichens can survive a small amount of air pollution

crusty lichens can survive in more polluted air.

Factories can cause air

pollution


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n places where no lichens are growing, it's often a sign that the

air is heavily polluted with sulfur dioxide.

Another indicator of air quality is the blackspot fungus on

roses. Blackspot fungus grows well on roses in unpolluted areas

because it is killed by the presence of sulfur dioxide that would

be found in polluted air.

Water pollution

Water pol lutants

ncreasing human population has led to an increase in pollution.

Some of this is due to:

more fossil fuels being burnt for heat and power

more food being grownland taken over for industry and housing.

As a result there has been an increase in levels of water

pollution.

Nitrate fertilisers are very soluble in water and are easily

washed off fields by the rain and then into rivers and

reservoirs. Because nitrates are all soluble they cannot

easily be removed from the water.Pesticides used by farmers to kill weeds or insects may

be washed or blown into streams and rivers.

Sulfur dioxide in the air can dissolve in water to form an

acidic solution.

Pollution indicators

The level of pollution in water can be indicated by the species

iving there. This is known as an indicator species.

Species that indicate pollution levels

pollution level of water species

polluted bloodworm


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polluted sludgeworm

clean water stonefly

clean water fresh water shrimp


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Eutrophication

A major problem with the use of fertilisers occurs when they're

washed off the land by rainwater into rivers and lakes. The

resulting increase of nitrate or phosphate in the water

encourages algae growth, which forms a bloom over the water

surface. This prevents sunlight reaching other water plants,which then die. Bacteria break down the dead plants and use

up the oxygen in the water so the lake may be left completely

ifeless.

Now try a Test Bite.

Back to Revision Bite

The increase of nitrate or phospate from fertilisers into water causes

eutrophication
http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollution/quiz/q60835011/http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollutionrev1.shtmlhttp://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollutionrev1.shtmlhttp://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollution/quiz/q60835011/


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