POLLUTION

Noadswood Science, 2011

Pollution

To understand how we can use organisms as indicators of pollution

Wednesday, April 19, 2023

Developing & Developed

Look at the following – a recent scene from the Glastonbury festival and a shanty town in South America

What issues are involved with this many people?

Developing & Developed

In a given area if the population becomes this vast there is a huge strain on resources needed: space / shelter; food; water (and mates)

There is also a great strain on removal of waste This impacts not only human populations, but any surrounding flora

and fauna

Human Population Projection Human beings compete with other living things for resources

and space – as the world’s population continues to increase, and standards of living improve, there is serious danger of a permanent change to the global environment

Human activities have led to the pollution of the environment, and a reduction in the amount of land available for other animals and plants, which makes it difficult for some species to survive

There is a need to achieve a level of development that also sustains the environment for future generations…

Human Population Projection 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

Human Population Projection Using the data in the table below plot a graph showing how the

human population has changed over the last 10’000 years: -

YearHuman Population Numbers

(Thousands)

8’000 BCE 5’000

6’000 BCE 10’000

4’000 BCE 20’000

2’000 BCE 35’000

0 200’000

2000 CE 6’000’000

Human Population Projection Human population graph over the past 10’000 years: -

Human Population

In the last 200 years or so the human population has grown very quickly – why? We can grow more food We can cure and prevent illness or disease We have no natural predators Standard of living has improved (electricity, fuel, heat,

cars etc…)

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

Strains on the global environment include: - Non-renewable energy resources (e.g. coal, oil and

natural gas) are being used up rapidly Raw materials are being used up rapidly More waste is being produced More pollution is being caused

Waste

Pollution is the addition of substances to the environment that may be harmful to living organisms

Population growth and increases in the standard of living cause more waste to be produced – If this waste is not handled correctly, it leads to pollution

Pollution can be categorised into the following: - Land pollution Water pollution Air pollution

Land Pollution

Most rubbish is buried in landfill sites and not all of it comprises safe materials – even common household items can contain toxic chemicals such as poisonous metals (many smoke alarms contain radioactive americium)

Industrial waste is also discharged onto the land – many farmers apply pesticides to improve their crops, but these can damage living things (toxic chemicals can be washed from the land into rivers, lakes and seas causing eutrophication)

Eutrophication in the Caspian Sea (turbidity in North)

Fertiliser Problems

Fertiliser problems arise when the fertiliser finds its way out of the soil and into rivers and streams

This can happen easily if too much fertiliser is applied or it rains immediately after it has been applied

The result is called eutrophication

Caspian Sea (rapid algae growth can be seen in the northern part increasing the water’s turbidity

(cloudiness))

Eutrophication

Eutrophication occurs when excess nitrates make their way into rivers and lakes causing rapid growth of some plants and algae

Some plants then start dying due increased competition for light which results in micro-organisms feeding on the dead plant (they respire using up lots of oxygen)

This increased level of decomposition results in high levels of oxygen being taken from the water, making it very difficult for larger organisms such as fish to survive - a real danger

Eutrophication

Excess nitrates make their way into rivers and lakes causing rapid growth of some plants and algae

Some plants and algae then start dying due increased competition for light

Micro-organisms feed on the dead plant (which respire using up lots of oxygen)

A lack of oxygen in the water can be very bad news for larger organisms such as fish

Water Pollution

Water pollution is caused by the discharge of harmful substances into rivers, lakes and seas

Many aquatic invertebrate animals cannot survive in polluted water, so their presence or absence indicates the extent to which a body of water is polluted

Pollutant Typical Effect

Fertilisers Damage to aquatic ecosystems

SewageDamage to aquatic ecosystems and

humans

Toxic chemicalsDamage to aquatic ecosystems and

humans

Air Pollution

The most common source of air pollution is the combustion of fossil fuels

Pollutant Effect

Smoke

Deposits soot on buildings and trees, causing them damage – permeates the air,

making it difficult for living creatures to breathe

Carbon monoxide Poisonous gas

Carbon dioxideGreenhouse gas that contributes to global

warming

Sulphur dioxide Contributes to acid rain

Pollution Indicators

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 sulphur dioxide, can damage lichens, and prevent them from growing – this makes lichens natural indicators of air pollution, e.g. Bushy lichens need really clean air Leafy lichens can survive a small amount of air pollution Crusty lichens can survive in more polluted air

In places where no lichens are growing, it's often a sign that the air is heavily polluted with sulphur dioxide

Lichens

Lichens can be used as air pollution indicators: -

Lichens (very clean air) Lichens (clean air) Lichens (dirty air)

Insects

Insects can be used as water pollution indicators: -

More species such as dragonfly and cranefly

survive (average water)

Leeches and midges survive (dirty water)

Many species such as mayfly and caddisfly survive (clean water)

Non-Living Indicators

Environmental changes can be measured using non-living indicators including: - Oxygen levels Carbon dioxide levels Particulate levels (ppm) Temperature (global average / maximum and minimum in

areas) Rainfall (global average / maximum and minimum in areas)