Students should understand how the properties of materials and energy forms interact to result in environmental change. They should apply this knowledge to suggest solutions to minimise current pollution problems and prevent future problems. Students should apply their understanding through a range of different historic and contemporary pollution events.
3.4.1 The properties of pollutants
Students should consider how the properties of pollutants affect behaviour in the environment, their harmful impacts and the strategies that can be used to minimise problems.
Content | Additional information |
|---|
Pollutant properties | - State of matter: solid/liquid/gas.
- Energy form.
- Density.
- Persistence/degradability.
- Toxicity.
- Reactivity.
- Adsorption.
- Solubility in lipids/water.
- Bioaccumulation.
- Bomagnification.
- Synergism.
- Mutagenic action.
- Carcinogenic action.
- Teratogenic action.
|
3.4.2 How environmental features affect the severity of pollution
Students should use examples to explain how environmental features affect the behaviour of pollutants and the severity of pollution caused.
3.4.2.1 Factors that affect dispersal
Students should understand the effect of point and diffuse sources on the dispersal and concentration of pollutants.
Content | Additional information |
|---|
| Air currents: | |
| Water currents: | |
3.4.2.2 Environmental factors that affect rates of degradation
Students should understand how environmental features can affect the chemical changes to pollutants, including the changes that convert primary pollutants to secondary pollutants.
Content | Additional information |
|---|
Temperature | The rate of decomposition of sewage. |
Light | The role of light in:- photochemical smogs
- degradation of pesticides.
|
Oxygen | Aerobic decay of organic wastes. |
pH | Neutralisation of acids by basic/alkaline rocks. |
The presence of other chemicals | The role of oxidation by ozone in producing secondary pollutants. |
Temperature inversions | The role of temperature inversions in the dispersal of atmospheric pollutants. |
The presence of adsorbent materials | The adsorption of toxic metal ions on clay particles. |
3.4.3 Strategies to control pollutants based on their properties and features of the environment
3.4.3.1 Principles of control
Content | Additional information |
|---|
| Critical Pathway Analysis: to predict pollutant mobility and inform monitoring programmes | Application to monitoring discharges of pollutants such as radioactive materials, heavy metals and persistent organic pollutants eg chlorinated organic compounds. |
| Critical Group Monitoring: to identify members of the public most at risk | Application to monitoring the health risks caused by pollutants such as radioactive discharges and heavy metals. |
| Emission location | Increased concentrations in valleys, enclosed water bodies. |
| Emission timing | Restriction of activities during temperature inversions. |
3.4.3.2 Selection of control technologies: to reduce production, reduce release and mitigate damage caused
Students should consider the following pollutants to identify their properties to analyse their environmental impacts and to plan control strategies
Students should understand the properties of pollutants and environmental features so they can analyse and evaluate the changes in human activities and strategies that can be used to minimize pollution.
3.4.3.2.1 Smoke/PM10 (Particulate matter less than 10 microns in diameter)
Content | Additional information |
|---|
Sources | Incomplete combustion of coal, diesel, wood, crop waste. |
Impacts | - Respiratory disease.
- Increased albedo of atmosphere.
- Smoke smogs during temperature inversions.
|
Controls | - Legislation: Clean Air Act (1956).
- Coal treatment: heating to remove tar.
- Electrostatic precipitators.
- Cyclone separators.
- Bag filters.
|
3.4.3.2.2 Acid precipitation
Content | Additional information |
|---|
Primary and secondary pollutants: - SOx : sulfurous and sulfuric acids
- NOx : nitric acid
- ozone involved in production of secondary pollutants.
| |
| Sources | - Combustion of fossil fuels.
- Smelting of sulphide ores.
|
Impacts | - Non-living objects: damage to limestone buildings, metal structures.
- Living organisms.
- Direct effects of acids.
- Damage to proteins.
- Damage to exoskeletons.
- Respiratory effects in humans.
|
Controls | SOx : - fuel desulfurization
- Flue Gas Desulfurization (FGD) wet FGD and dry FGD.
NOx : - catalytic converters
- urea sprays.
Ozone: control of NOx reduces ozone formation. |
3.4.3.2.3 Oxides of nitrogen (NO x)
Content | Additional information |
|---|
Sources | - Reaction of nitrogen and oxygen in hot combustion processes.
- NOx release due to fertiliser use.
|
Effects | - Photochemical smogs.
- Global climate change.
|
Controls | - Catalytic converters.
- Urea sprays.
- Control of fertilizer use.
|
3.4.3.2.4 Hydrocarbons
Content | Additional information |
|---|
Sources | - Unburnt hydrocarbon fuels.
- Gaseous emissions from fossil fuel exploitation.
- Solvents.
- Aerosol propellants.
|
Effects | - Greenhouse gases.
- Photochemical smogs.
|
Controls | - Catalytic converters.
- Improved combustion efficiency.
- Vapour collection and incineration.
- Activated carbon filters.
|
3.4.3.2.5 Carbon monoxide
Content | Additional information |
|---|
Source | Incomplete combustion of hydrocarbons. |
Effect | If inhaled reduced carriage of oxygen by haemoglobin. |
Controls | - Catalytic converters.
- Improved combustion efficiency.
|
3.4.3.2.6 Thermal pollution
Content | Additional information |
|---|
Scientific principles | The relationship between temperature and maximum dissolved oxygen level. |
Source | Hot water from steam turbine power station condensers. |
Effect | Deoxygenation of water. |
Control | Temperature reduction using cooling towers. |
3.4.3.2.7 Oil pollution
Content | Additional information |
|---|
Sources | - Waste lubricating oil.
- Ship tank washing.
- Ship tanker accidents.
- Other ship accidents.
- Oil refinery spills.
- Pipeline leaks.
- Leakage during drilling.
|
Effects | - Toxicity.
- Asphyxiation.
- Loss of insulation.
- Less time to feed young.
- Foodchain effects.
|
Controls | - Recycling of waste oil.
- Reduced leakage: equipment maintenance.
- Bund walls.
- Ship tanker design.
- Double hulls.
- Twin engines/rudders.
- Ship tanker operation:
- inert gas oil tank systems
- recirculation of washing water
- improved navigation systems eg GPS
- offshore shipping routes
- oil interceptors
- oil spill clean-up:
- inflatable booms
- skimmers
- absorbent materials
- polymerising materials
- dispersants
- steam cleaning
- bioremediation.
|
3.4.3.2.8 Pesticides
Content | Additional information |
|---|
Examples of different pesticide groups should be used to illustrate the main pollutant properties: | - Toxicity.
- Systemic/contact action.
- Specificity.
- Persistence.
- Liposolubility.
- Bioaccumulation.
- Biomagnification.
- Mobility.
- Synergism.
|
Effects | - Direct toxic impacts on non-target species.
- Toxic impacts after increased concentration.
- Indirect effects: food chain impacts, loss of inter-species relationships.
|
Control | Restrictions on use of selected pesticides, eg organochlorines, organophosphates. |
3.4.3.2.9 Nutrient pollution
Inorganic nutrients: nitrates and phosphates
Content | Additional information |
|---|
| Source | Nitrates (leachate/runoff) and phosphates (sewage effluent). |
Effect | Eutrophication (combined effects of nitrates and phosphates). |
Nitrates and human health | - Methaemoglobinaemia/blue baby syndrome.
- Possible human carcinogen.
|
Controls | Nitrates: - use of low solubility fertilisers
- nitrate vulnerable zones.
Phosphates: iron phosphate precipitation. |
Organic nutrient pollutants
Content | Additional information |
|---|
Sources | Organic wastes (sewage, manure, silage fluids, effluent from processing of wood and paper). |
Effect | Deoxygenation caused by microbial aerobic decomposition. |
Controls | The major stages in treatment of organic wastes: - pre-treatment:
- primary treatment
- secondary treatment
- aerobic bacterial decomposition: activated sludge/filter beds
- secondary sedimentation.
- tertiary treatment
- phosphate removal
- bacterial microfilters.
- anaerobic sludge digestion.
|
3.4.3.2.10 Acid mine drainage
Content | Additional information |
|---|
Sources | - Oxidation of sulfide ores in mine spoil/rocks.
- Drainage water/leachate.
|
Effects | - Reduced pH – acid damage.
- Increased solubility and mobilisation of toxic metals.
|
| Control | Collection of drainage water and neutralization with lime. |
3.4.3.2.11 Heavy metals
Content | Additional information |
|---|
The properties of heavy metals should be analysed to understand why they have caused pollution problems and the strategies used to prevent pollution. | |
Lead
Content | Additional information |
|---|
Properties | - Neurotoxicity.
- Liposolubility.
- Bioaccumulation.
- Biomagnification.
|
Controls | - Discontinued uses, eg paint, petrol additives, lead pipes, solder for water pipes, lead fishing weights.
- Waste storage at high pH to reduce solubility.
|
Mercury
Content | Additional information |
|---|
Properties | - Neurotoxicity.
- Liposolubility.
- Bioaccumulation.
- Biomagnification.
|
The effect of chemical form on pollutant toxicity | - Elemental mercury.
- Inorganic mercury.
- Organic mercury.
|
3.4.3.2.12 Solid wastes
Content | Additional information |
|---|
Students should understand that the treatment method for solid wastes depends upon its properties. The methods appropriate for each waste type should be analysed. | |
Domestic wastes | The advantages and disadvantages of the treatment options should be evaluated: - landfill
- incineration
- recycling
- composting.
|
Specialist solid wastes | Solid wastes with particular risks should be separated and treated individually. |
| Radioactive waste | The sources and properties of the three waste categories should be understood to identify appropriate disposal methods: - high-level waste
- intermediate-level waste
- low-level waste.
The need for sealed storage, monitoring, encapsulation, use of absorbers and cooling should be evaluated for each waste level. |
Asbestos | Secure, permanent, sealed storage. |
Cyanide | Incineration. |
3.4.3.2.13 Noise
Content | Additional information |
|---|
The scientific principles of sound that affect noise pollution: - frequency range of human hearing
- logarithmic nature of the dB scale
- volume
- threshold of human hearing.
| |
The effects of noise on non-living objects:- acoustic fatigue
- shock impacts.
| |
The effects of noise on living organisms: - Humans:
- hearing damage
- stress, ulcers, heart disease
- behavioural changes.
| |
Other organisims:- livestock injuries
- disturbance of breeding birds
- reduced feeding success: bats, owls, dolphins
- hearing damage/behavioural changes: cetaceans.
| |
The sources and control of noise
Students should be able to explain how different control methods can be used to control noise in a wide range of situations.
Aircraft noise
Content | Additional information |
|---|
Sources | - Engine noise, especially at high thrust.
- Air turbulence.
|
Controls | Airport design and location: - location away from major population centres
- taxi areas away from residential areas
- provision of acoustic insulation
- land-use restrictions
- baffle mounds/acoustic insulation.
Aircraft design: - engine designs to reduce noise emissions
- aerodynamic surfaces.
Airport operation: - the use of airport take-off and landing noise footprints in planning mitigation programmes
- flight paths avoid urban areas
- altitude restrictions
- constant descent angle
- night flight restrictions
- noisy aircraft banned
- fines for excessive noise
- engine test restrictions
- reduced use of reverse thrusters.
|
Railway noise
Content | Additional information |
|---|
Sources and controls | - Wheel vibration – track polishing, sound absorbing ballast.
- Engine noise – sound absorbing suspension.
- Pantograph turbulence – aerodynamic fairing.
- Wheel squeal on corners – lubrication of wheels/track.
- Braking squeal – use of composite material brakes.
|
Road traffic noise
Content | Additional information |
|---|
Sources and controls | - Wheel vibration/tyre noise – sound absorbing road surface, acoustic fences.
- Engine noise – acoustic insulation.
- Air turbulence – improved aerodynamics.
|
Industrial noise
Content | Additional information |
|---|
Sources | - Air compressors.
- Pile drivers, stamping machines.
- Drills.
- Mine blasting, military sonar.
|
Controls | - Worker ear protection/remote operation.
- Acoustic insulation/mats/baffle mounds.
- Restrictions on timing of operations.
- Alternative procedures, eg pressing instead of stamping.
- Drilling instead of pile-driving.
|
Domestic noise
Content | Additional information |
|---|
Sources | - Appliances – acoustic insulation.
- Music – volume limiters.
|
3.4.3.2.14 Ionising radiation
Content | Additional information |
|---|
Uses | - Nuclear weapons.
- Nuclear electricity.
- Ship propulsion.
- Manufacturing industry.
- Healthcare.
- Agriculture.
|
Scientific principles | - Half-life and health risk.
- Type of radiation and health risk: Relative Biological Effectiveness (RBE).
- Exposure vs contamination.
- Activation products.
- Units: Becquerels, Grays, Sieverts.
|
Effects | - Free radical production, DNA damage.
- Acute and chronic effects.
- Somatic and gonadic effects.
|
Control of exposure to radioactive materials. | |
Principles of control | - Exposure should be: As Low As Reasonably Achievable (ALARA).
- Equipment should be: Best Available Technology Not Entailing Excessive Cost (BATNEEC).
- The use of Risk:Benefit analysis.
|
Controls | - Closed sources to prevent contamination.
- Radiation absorbers.
- Distance from source: the inverse square law.
- Reduced period of exposure.
- Worker monitoring at work/on leaving work.
|
Radioactive waste management (see specialist solid wastes) | - High-level waste.
- Intermediate-level waste.
- Low-level waste.
|
The principles of environmental monitoring | Critical Pathway Analysis (CPA), involves identifying the most likely route a material will take, based on its properties and features of the environment, eg: - wind and water current velocity and direction
- geology and hydrology
- food chain pathways.
Environmental sampling: - atmospheric dust
- soil
- water
- seaweeds, molluscs, fish
- milk, vegetables, meat.
Critical Group Monitoring (CGM). CGM involves identifying those members of the public who, because of their lifestyles, are most at risk. They are monitored. If they are safe, everyone else should be safe too. |
3.4.3.3 The use of scientific knowledge to develop new pollution control technologies
Students should understand that a wide range of new technologies is available to provide better control of pollution.
Content | Additional information |
|---|
Control technologies | - Methods to prevent pollutant release.
- Monitoring impacts.
- Treating contaminated areas by leachate collection.
- Satellite monitoring of oil spills.
- GPS ship tracking to monitor navigation and reduce accidents.
- Adsorption of heavy metals using polymers.
- Phytoremediation of land contaminated with heavy metals.
- Bioremediation of hydrocarbon spills.
|
3.4.4 Opportunities for skills development and independent thinking
| Mathematical skill number | Opportunities for skills development and independent thinking |
|---|
| MS 0.3 | Students could calculate percentage yields, eg in pollution control. |
| MS 0.5 | Students could use a calulator to find and use logarithmic values for noise levels. |
| MS 1.4 | Students could use the term probability appropriately when investigating casual relationships such as the link between human health problems and urban pollutants. |
| MS 1.5 | Students could analyse data collected using random or systematic sampling, eg Simpson's index of diversity to compare the biodiversity of habitats exposed to different pollution types. |
| MS 1.9 | Students could use the chi-squared test to assess the impacts of different pesticides on non-target insect species. |
| MS 1.10 | Students could calculate the standard deviation of tropospheric ozone levels in a city. |
| MS 2.5 | Students could convert between the logarithmic dB scale and linear scales of relative sound pressure. |
| MS 3.1 | Students could interpret a 3-D graph of fish mortality at different concentrations of a toxic metal and different pHs. |
| MS 3.2 | Students could demonstrate their understanding that data may be presented in a number of formats and be able to use these data, eg dissolved oxygen levels expressed numerically as percentage saturation or mg l-1 and in table or graphical form. |
| MS 3.3 | Students could select an apppropriate format for presenting data, bar charts, histograms, graphs and scatter graphs, eg organic matter and oxygen depletion in water. |
| MS 3.5 | Students could read the intercept point from a graph to find the temperature at which oxygen levels fall too low to support particular aquatic species. |
| MS 3.6 | Students could calculate rates of temperature change with altitude in the atmosphere, in the context of photochemical smogs. |
Working scientifically
Students could plan activities to investigate environmental issues related to pollution which they could carry out eg:- students could monitor atmospheric pollution using a lichen biotic index at different distances downwind of an urban centre
- students could monitor water pollution at different locations using an aquatic invertebrate biotic index
- students could measure the effect of inorganic nutrient concentration on the growth of algae.
Students could plan activities in a range of broader environmental contexts related to pollution, including ones where first hand experience of practical activities may not be possible eg:- students could plan a study to collect the information needed for a Critical Pathway Analysis around a pollutant source
- students could plan a study to investigate the impact of a new potential pollutant on long-term human health.
| Practical skill number | Opportunities for skills development and independent thinking |
|---|
| PS 1.2 | Students could assess the information needed to construct a Critical Pathway Analysis:- wind direction and velocity patterns
- precipitation patterns
- impact of geology on movements
- impact of hydrology on movements
- biota.
|
| PS 1.3 | Students could identify the properties that may be important in predicting problems that may be caused by a new industrial waste. |
| PS 4.1 | The practical skills of using equipment within scientific studies are expanded, as appropriate, in detail in the selected methodologies and sampling techniques below. |
Opportunities to investigate the required methodologies of which students must have first hand experience. Further details can be found in Appendix A: Working scientifically
| Methodology skill number | Opportunities for skills development and independent thinking |
|---|
| Me 2 | Students could use a transect to measure noise levels with increasing distance from a road. |
| Me 5 | Students could investigate the effect of sample timing on noise levels near a road. |
Opportunities to investigate the required sampling techniques of which students must have first hand experience. Further details can be found in Appendix A: Working scientifically
| Sampling technique skill number | Opportunities for skills development and independent thinking |
|---|
| ST 1 | Students could measure nitrate and phosphate levels to monitor water pollution in different locations. |
| ST 2 | Students could use an appropriate quadrat to measure percentage cover and species present to monitor atmospheric pollution. |
| ST 6 | Students could use pond nets, kick sampling or surber samplers to collect samples for biotic index analysis. |
