Guiding questions
- How does pollution affect the sustainability of environmental systems?
- How do different perspectives affect how pollution is managed?
SL and HL knowledge statements
Here’s a set of flashcards for the essential vocabulary and concepts in the SL and HL content of ESS topic 4.4 Water pollution.
Play some games to see how well you have mastered the keywords and essential understandings for ESS topic 4.4 Water pollution.
4.4.1 Water pollution has multiple sources and has major impacts on marine and freshwater systems.
4.4.2 Plastic debris is accumulating in marine environments. Management is needed to remove plastics from the supply chain and to clear up existing pollution.
4.4.3 Water quality is the measurement of chemical, physical and biological characteristics of water. Water quality is variable and is often measured using a water quality index. Monitoring water quality can inform management strategies for reducing water pollution.
4.4.4 Biochemical oxygen demand (BOD) is a measure of the amount of dissolved oxygen required by microorganisms to decompose organic material in water.
4.4.5 Eutrophication occurs when lakes, estuaries and coastal waters receive inputs of mineral nutrients, especially nitrates and phosphates, often causing excessive growth of phytoplankton.
4.4.6 Eutrophication leads to a sequence of impacts and changes to the aquatic system.
4.4.7 Eutrophication can substantially impact ecosystem services.
4.4.8 Eutrophication can be addressed at three different levels of management.
Knowledge statements for HL only
4.4.9 There is a wide range of pollutants that can be found in water.
4.4.10 Algal blooms may produce toxins that threaten the health of humans and other animals.
4.4.11 The frequency of anoxic/hypoxic waters is likely to increase due to the combined effects of global warming, freshwater stratification, sewage disposal and eutrophication.
4.4.12 Sewage is treated to allow safe release of effluent by primary, secondary and tertiary water treatment stages.
4.4.13 Some species are sensitive to pollutants or are adapted to polluted waters, so these can be used as indicator species.
4.4.14 A biotic index can provide an indirect measure of water quality based on the tolerance to pollution, relative abundance and diversity of species in the community.
4.4.15 Overall water quality can be assessed by calculating a water quality index (WQI).
4.4.16 Drinking water quality guidelines have been set by the World Health Organization (WHO), and local governments can set statutory standards.
4.4.17 Action by individuals or groups of citizens can help to reduce water pollution.
Practical activities
- 4.4.3 Application of skills: Use methods to measure key abiotic factors in aquatic systems, for example, dissolved oxygen, pH, temperature, turbidity, and concentrations of nitrates, phosphates and total suspended solids. Possible methods may include the use of oxygen and pH probes, a thermometer, a Secchi disc, nitrate/phosphate tests.
- 4.4.6 Application of skills: Create a systems model to show the impacts and changes of eutrophication in an aquatic system. This model should include examples of positive feedback (for example, increase in nutrients>increase in death of organisms>increase in decomposition>increase in nutrients).
- 4.4.14a Application of skills: Apply protocols to assess biological oxygen demand of water samples from different sources.
- 4.4.14b Application of skills: Apply protocols to assess water quality using a named biotic index.
- Add from existing PSOW booklet.
Possible engagement opportunities
Turn these into CAS suggestions connected to the UN SDGs:
- Investigate the effects of pollution on aquatic systems in the local area or region. Health and safety, and ethical issues, should be considered.
- Produce an information film about red tides, if this is a problem in the local area.
- Engage in plastic pollution clean-ups.
- Visit a water treatment plant.
Happy learning!
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