Types and Sources of Pollution Revision Notes | GCSE OCR Foundation Biology

What this lesson covers

Explore the different types of pollution that occur in water, air, and on land, examining specific sources like sewage, fertilisers, toxic chemicals, sm...

• Identify the three main types of pollution and their sources
• Explain how sewage, fertilisers and toxic chemicals pollute water
• Describe how smoke and acidic gases cause air pollution
• Evaluate the impact of landfill and toxic chemicals on land pollution

Key ideas to keep in view

Use this lesson to stay inside B6.1 Monitoring and maintaining the environment while connecting the detail back to the wider B6: Global challenges topic.

• B6: Global challenges
• B6.1 Monitoring and maintaining the environment
• GCSE OCR Foundation Biology

Lesson notes preview

Read the core explanations from Types and Sources of Pollution before testing yourself from memory.

• Every day, millions of tonnes of waste enter our environment. From the plastic bottle you threw away yesterday to the exhaust fumes from cars, pollution surrounds us. But here's what makes this topic crucial for your exams: pollution doesn't stay put. A chemical dumped in one place can end up affecting ecosystems hu...
• Understanding pollution isn't just about memorising facts. You need to trace the journey - how does sewage from your local treatment plant affect fish populations? Why does burning coal in one country cause acid rain in another? These connections are exactly what examiners test.
• The contamination of the environment with harmful substances that damage ecosystems and human health. Can occur in water, air or on land.
• Trap: Many students think pollution only affects the immediate area where it's released. Actually, pollutants travel through air currents, water systems and food chains, causing widespread damage far from their source.
• Water pollution is particularly dangerous because it spreads quickly and affects entire food webs. Picture a river system like a highway - once pollutants enter, they travel downstream affecting everything in their path.
• There are three main sources you need to know for your exam: sewage, fertilisers, and toxic chemicals. Each causes different problems, but all can devastate aquatic ecosystems.
• Sewage pollution occurs when untreated human waste enters water systems. This introduces harmful bacteria like E. coli and increases nutrient levels, particularly nitrogen and phosphorus. The bacteria can cause disease in humans and wildlife, while the excess nutrients trigger eutrophication.
• The process where excess nutrients in water cause algae blooms, leading to oxygen depletion and ecosystem damage. Results in fish kills and loss of biodiversity.
• Fertiliser pollution happens when nitrogen and phosphorus from agricultural runoff enter rivers and lakes. Farmers use fertilisers to boost crop growth, but rain washes the excess into waterways. This creates the same eutrophication problem as sewage, but on a much larger scale.
• Toxic chemical pollution includes heavy metals like mercury and lead, pesticides, and industrial chemicals. These don't break down easily and accumulate in organisms through bioaccumulation. A small amount in water becomes concentrated as it moves up the food chain.

Continue through the topic

Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.