This deck covers the impact of human activities on the environment, focusing on pollution. We'll examine how substances like sewage, fertilisers, plastics, and certain gases can damage ecosystems.

Let's start with water pollution. Untreated sewage from homes and industries can sometimes be released into rivers and lakes. This sewage contains harmful microorganisms and organic waste that can seriously damage aquatic ecosystems.

Another major water pollutant comes from farming. Farmers use fertilisers to provide mineral ions for crop growth, but excess fertiliser can be washed off the land by rain and enter rivers and lakes.

When excess mineral ions like nitrates enter the water, they trigger a damaging process called eutrophication. This is a critical causal chain for your exams, so we'll go through it step-by-step.