Pollution at HL: This introduction to pollution is the same for SL and HL. At HL you connect it to the deeper cycle disruption (nitrogen and carbon) and to the economics of who pays to clean it up.
No HL-only material here — just get the types and effects of pollution clear.
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🏭 Pollution basics
Pollution means adding something where it doesn’t belong (or adding too much, too fast).
- Plastic: 8 million tonnes enter oceans yearly — turtles mistake bags for jellyfish 🐢
- Air pollution: Factory smoke causes smog and acid rain
- Water pollution: Fertilizers cause algal blooms that kill fish
- Energy pollution: Noise disturbs whales, light confuses migrating birds
How this affects food webs: Pollution is a direct human impact because it damages or kills organisms. Polluted organisms are less healthy or die before being eaten, so less usable energy is passed between trophic levels, weakening the food web.
Pollution can be matter (chemicals, plastics) or energy (noise, light, heat).
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Chemical pollution
Chemical pollution comes from many sources, including factories, agriculture, fuel use, and poorly managed waste. Some chemicals are especially harmful because they do not break down easily.
- Some pollutants persist for long periods in the environment
- They can enter food webs through water, soil, or air
- Top predators are often the most affected
Non-biodegradable pollutants remain in ecosystems and can build up inside living organisms.
Plastic pollution
Plastics are widely used because they are strong and flexible, but most plastics do not break down naturally. Instead, they fragment into smaller pieces.
Microplastics are found in water, air, soil, and living organisms across the planet.
- Plastic travels long distances through rivers and oceans
- Many organisms mistake plastic for food
- Plastics can enter food webs at very low trophic levels
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Impacts on organisms and humans
Plastic and chemical pollutants affect organisms at all trophic levels. These substances can cause physical harm, reduce survival, and disrupt normal biological processes.
- Wildlife can be injured or starve after ingesting plastic
- Toxins move up food webs and reach humans
- Some chemicals interfere with hormones and development
Humans are exposed to pollutants through food, water, and air.