Environmental Systems and Societies · Topic 4: Water
ES4.4 — Water pollution
Environmental Systems and Societies · SL / HL · syllabus-mapped notes
Sources of pollution and plastics
The multiple sources of water pollution and the accumulation of plastic debris and microplastics in marine environments.
Measuring water quality and BOD
The chemical, physical and biological parameters that define water quality, and biochemical oxygen demand as an indirect measure of organic matter.
Eutrophication and its management
How nutrient inputs cause algal blooms, the oxygen-depletion cascade with positive feedback, and the three levels of management.
Pollutants, harmful algal blooms and dead zones
The range of water pollutants, harmful algal blooms and their toxins, and why anoxic dead zones are becoming more frequent.
Treatment, indicators and quality indices
Primary/secondary/tertiary sewage treatment, indicator species, biotic indices and the water quality index.
Standards and citizen action
WHO guidelines and statutory standards, and the actions individuals and citizen groups take to reduce water pollution.