Waste management (AQA GCSE Biology Combined Science): Revision Notes
Waste management
What is pollution?
Pollution happens when harmful or poisonous substances get released into our environment. These dangerous materials can kill animals and plants. This leads to fewer living things in our world, which we call a reduction in biodiversity.
Biodiversity refers to the variety of all living things in an ecosystem - from the smallest bacteria to the largest mammals. When pollution damages or kills these organisms, we lose this natural variety.
Sources of pollution
Pollution affects three main areas of our environment:
Land pollution
- Pesticides - chemicals farmers spray on crops to kill insects and other pests
- Herbicides - chemicals used to kill weeds that compete with crops
- Landfill waste - rubbish dumped in large sites underground
Air pollution
- Smoke and gases from factories and vehicles
- Sulfur dioxide - a gas that mixes with water in clouds to make acid rain
Water pollution
- Sewage - dirty water containing human waste from toilets and sinks
- Fertiliser - plant food chemicals that wash off farmland into rivers
- Toxic chemicals - poisonous substances that leak from factories
Each type of pollution can travel between environments. For example, air pollution can settle on land and water, while water pollution can evaporate into the air. This means pollution in one area often affects all three environments.
Human population and increasing pollution
The number of people on Earth is growing very quickly. More people means higher living standards and more waste being produced.
As the population grows, we need:
- More land for building houses and towns
- More quarrying to get materials for construction
- More farming to grow food for everyone
- More places to dump our rubbish
All of this leaves less space for wild animals and plants to live. It also creates much more pollution if we don't handle waste properly.
The global population is expected to reach nearly 10 billion people by 2050. This rapid growth means we must find better ways to manage waste and reduce pollution to protect our environment.
Real example - sulphur dioxide emissions
Real World Example: Reducing Sulphur Dioxide Pollution in the UK
Coal and oil power stations release sulphur dioxide when they burn fuel. This creates toxic gases that harm the environment.
The situation: In the UK, most sulphur dioxide comes from power stations.
What happened: Between 2000 and 2014, the total amount released went down significantly.
Why the improvement occurred:
- Electricity companies started using more natural gas instead of coal and oil
- Natural gas produces less sulphur dioxide than coal
- However, when coal became cheaper between 2010-2012, emissions went up again temporarily
Key finding: This shows how changing fuel types can significantly reduce pollution levels.
Sulphur dioxide is one of the main causes of acid rain, which damages forests and buildings. When it mixes with water vapour in the atmosphere, it forms sulfuric acid that falls as acidic precipitation.
Effects on biodiversity
When pollution increases, it directly harms wildlife through several mechanisms:
- Animals and plants die from poisoning
- Their habitats get destroyed
- Food chains get disrupted
- Some species may become extinct
This is why proper waste management is so important for protecting biodiversity. When we reduce pollution, we give ecosystems a better chance to recover and thrive.
The loss of even one species can have cascading effects throughout an entire ecosystem. For example, if pollinators like bees are harmed by pesticides, it affects plant reproduction, which then impacts all the animals that depend on those plants.
Summary
Key Points to Remember:
- Pollution kills - harmful substances released into the environment damage plants and animals
- Three types matter - land, air, and water pollution all reduce biodiversity
- Population growth = more waste - more people create more pollution if not managed properly
- Examples help - sulphur dioxide from power stations shows how pollution can be reduced by changing fuels
- Biodiversity suffers - poor waste management leads to fewer species surviving in the wild