3.4 Pollution

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.

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.

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.

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: velocity direction.
Water currents: velocity direction.

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.

Strategies to control pollutants based on their properties and features of the environment

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.

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.

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.

Acid precipitation

Content	Additional information
Primary and secondary pollutants: SO_x: sulfurous and sulfuric acids NO_x: 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	SO_x: fuel desulfurization Flue Gas Desulfurization (FGD) wet FGD and dry FGD. NO_x: catalytic converters urea sprays. Ozone: control of NO_x reduces ozone formation.

Oxides of nitrogen (NO x)

Content	Additional information
Sources	Reaction of nitrogen and oxygen in hot combustion processes. NO_x release due to fertiliser use.
Effects	Photochemical smogs. Global climate change.
Controls	Catalytic converters. Urea sprays. Control of fertilizer use.

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.

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.

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.

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.

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.

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: grit traps, screens. primary treatment primary sedimentation secondary treatment aerobic bacterial decomposition: activated sludge/filter beds secondary sedimentation. tertiary treatment phosphate removal bacterial microfilters. anaerobic sludge digestion.

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:
- grit traps, screens.
primary treatment
- primary sedimentation
secondary treatment
- aerobic bacterial decomposition: activated sludge/filter beds
- secondary sedimentation.
tertiary treatment
- phosphate removal
- bacterial microfilters.
anaerobic sludge digestion.

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.

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.

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.

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.

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.

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.

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.

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 scientificallyStudents 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.

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3.5 Biological resources