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Teacher Resource Bank
GCE Environmental Studies
Unit 3 ENVS3 Energy Resources and
Environmental Pollution
• Teachers notes
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Unit 3 ENVS3 Energy Resources and
Environmental Pollution
Introduction
Future problems of energy supply and how these may be resolved are investigated through
the study of the energy resources which are available for use.
The properties of pollutants are considered to explain why some materials or forms of energy
cause environmental damage. These issues are developed through the study of a range of
atmospheric, aquatic and terrestrial pollutants. The strategies that may be used to minimise
releases, treat effluents and manage the damage caused are considered. These issues allow
consideration of the issues related to Units 1 and 2 that involve pollution.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
UNIT 3 – Energy Resources and Environmental Pollution
3.3.1 Energy
Energy use
Factors affecting energy use now and in the future
Candidates should understand that the per capita energy consumption varies between different countries,
know the main factors that influence it and its importance in development and quality of life.
Economic factors
eg affluence and the ability to buy energy-using appliances, relative cost of energy and the disposable
income available to pay for it.
Level and type of industry
• Any energy used by industry adds to total energy use and per capita use.
• Heavy industry such as mining, ore processing and the chemical industry use a lot of energy.
Climate
• A cold climate increases energy use for heating.
eg Canada
• A hot climate increases energy use for air conditioning.
eg Australia, some parts of USA
Social / environmental awareness
• Some countries have a high level of awareness of the need to conserve energy and the benefits
of doing so.
eg Germany, Sweden, Denmark
• Other countries have a lower awareness, often caused by local availability and affluence.
eg USA, UK
National and global trends in energy demands
Changes in amount and type of industry
• Many countries that develop primary industry such as mining also develop secondary industry
such as manufacturing which uses less energy. The primary industry may decline as resources
are depleted or other countries compete with cheaper labour costs. Tertiary industry such as the
service industries use much less energy.
• The use of more efficient technologies in MEDCs may require less energy per unit of output than
in LEDCs.
eg the steel industry in the USA compared with India or China.
Changes in affluence
• Increased income generally increases per capita energy use as it allows the purchase of energyusing devices and activities. Conversely, it can also allow expensive more efficient equipment to
be bought.
Changes in population size
• An increase in population size will produce a proportional increase in energy use even if there is
no change in per capita use.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Global energy use continues to rise as population and per capita use both increase. The slow growth or
comparative stability of energy use in MEDCs may be misleading as the high energy use of the primary
industry needed to support their economies may have moved to LEDCs. A true assessment of per-capita
energy use will include all uses of energy by the individual and the energy used in producing all the
goods and services they use.
The availability of energy has a significant impact on quality of life and the development of societies.
A shortage of energy inhibits many developments that could benefit a communities.
eg mechanization of labour-intensive processes, energy to process materials, transport, water pumping
and purification.
Energy resources
Candidates should have knowledge of the available energy resources where this helps to understand the
environmental impacts of their use and the features that affect their usefulness.
The study of technical detail should be limited to aspects that increase the understanding of these issues.
The concept of non-renewable and renewable resources.
The advantages and disadvantages of non-renewable and renewable resources should be considered in
terms of their application to particular uses and their environmental impacts.
eg the high energy density and ease of storage of fossil fuels, the intermittency of wind power and the low
levels of pollution caused by most renewable energy resource.
The importance of sustainable use of those renewable resources which can be depleted.
eg wood, water
Non-renewable energy resources
Candidates should be able to use examples to illustrate the factors affecting the ease of use of
non-renewable energy resources and therefore their likely use in the future.
Finite resource
• The processes that produce fossil fuels are too slow to replace what has been used by humans.
Uranium is not being formed. Although none of these will be totally used up, exploitable deposits
may be depleted.
Energy density
• Energy density is measured as the amount of energy released from a given mass of fuel or
equipment.
• The high energy density of fossil fuels means a small amount of fuel releases a large amount of
energy, so the amount of fuel that has to be carried or stored is low and it is easier to produce
high temperatures. It also makes it possible to transport large amounts of energy without needing
to use a lot of energy eg by ship, train, truck or pipeline.
• Uranium and plutonium have very high energy densities so reactors do not need continual
refueling and they can be used where the delivery of bulky fuels may be difficult.
• By comparison, renewable energy resources have low energy densities.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Available resource
• The quantity of fossil fuels that exist is very large. Uranium is abundant but usually at very low
concentrations. Improvements in technology have continually increased the amounts that can be
found and extracted.
eg remote sensing exploration, mechanization of coal mining, drainage water pumping, deep
drilling, coal gasification, secondary and tertiary oil recovery, nuclear fuel concentration and
plutonium breeding.
• It is still very difficult to exploit some deposits.
eg those that are deep, fragmented, thin, under deep water or ice.
Level of technological development
• Fossil fuels had such advantages that they took over from the use of wood, water and wind in
industrial societies. New technologies developed that could only use fossil fuels.
eg petrol and diesel vehicle engines, steel furnaces, jet engines, gas lighting
• To replace fossil fuels may require the development of new technologies to use the energy in
addition to those needed to harness it.
• The complexity of nuclear power has hindered its economic viability.
eg plutonium fast breeder reactors, nuclear fusion, the safe decommissioning of reactors and
waste storage
Environmental impact
• Fossil fuel use can cause a lot of habitat damage during extraction and pollution during use.
eg coal mining, oil spills, emissions of CO2, SO2, NOx
• Many of these problems can be solved or minimized.
eg spoil restoration, better oil tanker design, flue-gas desulfurisation, carbon sequestration
• The use of civil nuclear power has caused few major problems but individual events can be very
serious.
eg Chernobyl , 1986, Soviet Union (now Ukraine)
• These issues are studied in greater detail in 3.3.2 Pollution.
Political and international trade problems
• Shortages in supplies or the need to import fuel when there are insufficient local supplies can
cause tension between countries. Control of resources that are in great demand can be used by
countries as a negotiating tool in discussions about other issues.
eg oil from the Middle East, natural gas from Russia
Economic issues
• The relatively high cost of fossil fuels during their early development was not a major problem as
they allowed new activities to develop and did not have to compete with similar resources.
• New energy technologies must be able to compete with existing fossil fuel technology for which
the development costs have already been paid. This may be difficult as their development costs
are still being paid and they do not have the benefit of cheap mass production.
• As the most accessible fossil fuel deposits become depleted prices are likely to rise. Prices may
also rise if the financial costs of environmental damage are included or if environmental taxes
increase.
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Background details on non-renewable energy resources
This section includes examples of the issues related to non-renewable energy resources that can be
used to discuss their environmental advantages and disadvantages. Candidates can use other suitable
examples if preferred.
Fossil fuels
Extraction techniques
These need to be understood where they affect the ease of resource use and their environmental impact.
Coal
•
•
Deep mining involves extracts less non-coal material than open-cast mining but it is relatively
labour intensive, cannot use the largest equipment and suffers from problems of ventilation,
overburden support, drainage and subsidence of the ground surface.
Open-cast mining can use large machinery but cannot access deeper coal. It also affects a larger
area of land and causes more problems of noise, dust and visual impact.
Crude oil or Petroleum
• Primary oil recovery involves the extraction of crude oil that is forced to the surface by the natural
pressure of water beneath the oil or natural gas above or dissolved in it.
• Some oil is difficult to extract.
eg oil that is very deep below the surface (> 5km) is difficult to reach as friction increases and
pumping fluids in to carry out the rock fragments becomes harder.
Oil beneath deep water (>2km) is hard to exploit as anchoring the floating rig is difficult.
Oil that is very viscous or is in impermeable rock will not flow to the extraction well.
Many oil fields are too small to be exploited profitably.
Natural gas
• Natural gas is forced to the surface by its natural pressure.
Principal uses of the fossil fuels
• Building and process heating, vehicle fuels, electricity generation, petrochemicals.
Nuclear power
The source of nuclear energy: E = mc 2
Large amounts of energy are released when small amounts of matter from the nuclei of atoms are
destroyed.
Nuclear fission
Environmental issues
• Candidates should have knowledge of nuclear technology to aid understanding of the issues that
affect the contribution of nuclear power to present and future energy supplies:
Energy density of the fuel
• The high energy density of nuclear fuel makes it suitable for power stations where access for fuel
deliveries is a problem and for ship propulsion (although its complexity has limited its use mainly
to warships, especially submarines).
Uranium 235 concentration of the mined ore
• Most uranium ores are less than 1% U, of which 0.7% is the fissile U235.
Energy inputs of the nuclear industry required to support energy production
• The nuclear industry is very complex and relies upon energy inputs for mining, fuel manufacture,
power station construction and waste disposal. Most of these are currently provided by fossil
fuels.
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Public opposition
• In many countries there is public opposition to nuclear power. This is based on a lack of
understanding of the technology, poor public relations and, possibly, genuine dangers.
Complexity of the technology and its usefulness in less technologically advanced societies.
• Nuclear power relies on a high level of technological support.
eg the construction industry, clean water, external electricity supplies, worker training, waste
management.
Economic factors
• The high complexity of technology makes nuclear power expensive, especially power station
construction and waste management.
Political factors
• Some governments have encouraged the development of nuclear power for a variety of reasons.
eg isolation from unreliable fossil fuel supplies, the kudos of high profile developments and the
opportunity to develop nuclear weapons.
Radioactive waste
• The amount of radioactive waste produced is small compared with coal fired power stations but it
has unique properties. Good waste processing, storage and monitoring should reduce the risks to
the range that are acceptable for other activities.
Reactor safety
• Some reactor designs have poor safety margins and poor safety systems in case of incidents.
Good design and planning can reduce these problems.
eg gravity-drop control rods that can shut down a reactor very quickly
a strong containment building should prevent releases if there was a reactor explosion
Radioactive waste
• Any material that has, or could have been, contaminated with radioactive materials may be
treated as radioactive waste, but the treatment method depends upon the properties of the waste
and the associated risks.
• High level waste comes from used fuel rods and requires encapsulation in a secure container with
heat absorption and radiation screening. Waste half lives may be long. Vitrification involves
storage of the dried powdered waste in solid glass in stainless steel cylinders in cooled concrete
buildings.
• Intermediate level waste comes from used fuel rod cases and waste processing filters. It does not
generate heat and has shorter half lives than high level waste. Solid intermediate waste is stored
in cement or concrete in stainless steel drums.
• Low level waste includes general equipment with low levels of radioactivity. Solid low level waste
is sealed in polythene bags in steel drums in steel box-like containers in a concrete lined landfill
site.
• Wastes are easier to manage in solid form than if they are liquids or gases.
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Renewable energy resources
Candidates should be able to use examples to illustrate the factors affecting the ease of use of renewable
energy resource and therefore their likely use in the future:
Intermittence
• Some resources may not be available all the time and the available power can vary.
eg solar, wind, wave and tidal powers (although tidal power is very predictable)
•
The lack of control of when energy will be available makes the use of energy from these
resources less flexible. It can be difficult to match supplies to demand.
Unreliability
• The availability of energy may be unpredictable.
eg solar, wind and wave powers
• It is impossible to predict when and how much energy will be supplied from these resources so
they cannot be relied on as the only sources of energy.
Energy density
Most have a lower energy density than fossil or nuclear fuels. This may be measured in several ways:
• energy content kg-1 of fuel
eg biofuels
• energy harnessed kg-1 of equipment
eg solar panels
• energy density m-3
eg straw
Solar, wind and wave powers have low energy densities, while that of HEP and biofuels is higher but is
still often below that of fossil fuels.
Ease of storage
• The surplus energy from some renewable energy resources can be stored when demand is low
and released when required.
eg potential energy of water in the reservoir of HEP stations and chemical energy in biofuels.
• However the energy of some resources cannot be stored directly.
eg the light of solar power and the kinetic energy of wind and wave power.
Environmental impacts
• Most renewable energy resources have low environmental impacts but they all have some impact.
eg solar power causes pollution and habitat damage during the extraction and processing of the
materials used to make the equipment eg copper, aluminium, plastics, glass, paint.
• Some cause habitat damage when equipment is installed.
eg the habitat loss in locating the aerogenerators in windfarms
• Tidal barrages cause damage during construction and change the environment due to altered
water flow.
eg extraction and processing of rock, concrete, metals and other construction materials
access roads and power cables
reduced tidal range and altered habitat distribution
changed water flow rates
changed sedimentation and turbidity
pollutant retention
altered drainage in surrounding areas
barrier to fish migration
In-stream tide turbines have a much lower impact as they are not a barrier to water flow or organisms.
Most renewable energy resources can only be harnessed where natural processes or geographical
conditions are suitable.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Solar power
• season fluctuations make use in higher latitudes more variable
• changes in insolation caused by cloud cover
Wind power
• uplands
• plains
• coastal areas, both onshore and offshore
• higher latitudes
HEP
•
•
•
•
•
regular heavy precipitation
a large catchment area
impermeable rock
stable geology
no unacceptable land use conflicts
Tidal power
• high tidal range
• suitable coastal shape to concentrate the tidal flow
• no unacceptable land use conflicts
Geothermal power
• hot rocks near the ground surface
• natural springs that bring hot water to the surface
• fractured or permeable rock through which water can be pumped to absorb heat
Suitability for current uses of energy
• Energy use is controlled by the activity involved and by the technologies that have previously
been developed to provide energy.
• Many renewable resources produce heat or electricity which cannot easily be used to power
vehicles that currently run on fossil fuels.
Level of technological development
• The technology used to harness many renewable technologies are not yet fully developed but
improvements are continually being made.
• Very few in-stream tidal turbines have been installed and tested.
• More efficient photovoltaic cells are still being developed such as crystalline silicon cells, while
lower efficiency cells may have advantages of low manufacturing costs such as amorphous silicon
cells.
• Photothermal panels are being developed that are more efficient such as evacuated tubes and
more absorbant surface coatings.
• Larger wind turbines with higher electricity outputs are being developed and less well-developed
designs such as vertical axis aerogenerators are being researched.
Economic issues
• A variety of economic factors has hampered the development of renewable energy resources.
eg fossil fuel technology is well developed and early development costs have been paid.
• Fossil fuel technology has the advantage of the economies of scale of mass production.
• More recent economic initiatives have helped to make renewable energy resources more
economically competitive.
eg tax free profits on money invested in renewable technologies
carbon emission taxes on fossil fuels
guaranteed higher sale price for electricity from renewable resources
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Background details on renewable energy resources
This section includes examples of the issues related to renewable energy resources that can be used to
discuss their environmental advantages and disadvantages. Candidates can use other suitable examples
if preferred.
Solar-derived energy resources
Direct solar power
Fluctuating supplies:
• Daily, seasonal, climatic fluctuations
• Effect of clouds and suspended particles on scattering
The range of equipment used to harness solar power more effectively:
• Hot water panels
• Matt black surface, glazed, insulation, water pipe, thermostatically operated pump
• Passive solar architecture
• Large windows facing the direction of most intense sunlight
• Heliostats that rotate solar panels to face the sun
• Parabolic reflectors that focus the sunlight onto a collector
Hydroelectric power
Factors affecting location of HEP plants:
• Water supply, geology, topography, land-use conflicts, infrastructure (see also: location of water
collection reservoirs).
Wind power
Factors affecting the location of wind farms:
Windiest areas are usually uplands, coasts, shallow seas or open plains. Not all latitudes are equally
windy.
Site-specific problems:
Visual intrusion, local noise, bird strikes and radio interference can be problems
Land area:
Windfarms require a large area of open land over which the aerogenerators can be dispersed. The land
between can still be used for other purposes, eg farming.
Wind power is unreliable as fluctuations in wind speed cause variations in power output.
Doubling the wind velocity increases the available kinetic energy eight-fold.
Biofuels
• Types of biofuel:
• Waste materials: Organic wastes from crop and forestry production, sewage and dung including
biogas
• from anaerobic digestion, combustible domestic and industrial wastes.
• Energy crops: Wood, eg coppiced willow; carbohydrates, eg sugar/alcohol; vegetable oils;
• Miscanthus (elephant grass).
Advantages
• The supply rate can be controlled by deliberately producing more; they can be stored to match
supplies to demand.
• Some are liquid fuels or can be converted into them and can be used as vehicle fuel.
eg vegetable oils to make ‘biodiesel’; alcohol from sugar.
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Disadvantages
• Large areas of farmland may be required which may compete with food production or cause the
clearance of important habitats such as tropical rainforest.
• Some have a low density so they are bulky and difficult to transport.
eg straw, coppiced willow, Miscanthus
• Limited supplies
eg wastes from other activities: straw, manure.
• Uses of biofuels vehicle fuels, heating, electricity generation, cooking.
Non-solar renewable energy resources
Geothermal power
• Uses of geothermal energy
• Electricity generation: eg Wairekai, New Zealand
• Space heating: eg Southampton
• Water heating: eg Iceland, Bath
Advantage
• Low environmental impact: little pollution in use.
Disadvantage
• Only available where hot rocks are found near the surface.
Tidal power
Locational factors
• where the tidal range is large so large volumes of water are moved, preferably at high velocity.
The technology used to harness tidal power:
• a barrage with turbines for one-way or two-way generation
• in-stream turbines anchored to the seabed
Advantages of using tidal power:
• periods of generation are predictable
• power output may be large compared with other renewable resources
Disadvantages of using tidal power:
• limited number of suitable sites, intermittent generation
Environmental effects of barrages:
eg reduced tidal range, current changes, reduced feeding areas for birds, increased sedimentation
Secondary fuels
Secondary fuels are energy resources that are produced from primary energy resources.
Candidates should be able to give examples of the energy conversions necessary to convert primary
fuels into secondary fuels.
eg HEP: Solar > PE > KE > Electricity
Geothermal: Nuclear > Heat > PE > KE > Electricity
Fossil fuel power station: Chemical energy > Heat > Potential energy > Kinetic energy > Electricity
Electrolysis of water: Any method of generating electricity > Hydrogen
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Electricity
• Candidates should be familiar with the different methods used to generate electricity (details of the
chemistry or physics of operation are not required).
• From kinetic energy: the generator
• From light energy: photovoltaic cells.
• From chemical energy: fuel cells.
Hydrogen
Production of hydrogen:
• Hydrogen can be produced by the electrolysis of water.
Advantages of using hydrogen:
• The generation of hydrogen allows the conversion of surplus electricity, which could not be stored
on a large scale, into chemical energy which can be stored more easily.
• The stored chemical energy can be released by combustion to produce heat, drive vehicle
engines or it can be converted directly into electricity in fuel cells.
• It has a high energy density.
Disadvantage of using hydrogen:
• Hydrogen storage methods have not been fully developed.
Energy storage
The supply of energy and demand for it may vary, often at different times. If surplus energy can be stored
when supply exceeds demand then it can be used later when demand exceeds supply.
Storing a surplus to meet a later shortage is called peak shaving.
Many renewable resources can be harnessed only when natural processes make them available.
eg wind, solar, wave, tidal power
Pumped-Storage Hydroelectric Power Stations:
• Short-term surpluses of electricity may be stored as potential energy by using it to pump water
from a lower reservoir up to a higher one.
• The stored potential energy can be used later to generate electricity during times of high demand.
• These differ from normal HEP stations by having two reservoirs. Because the water is reused
there is no need for a large catchment area to collect rainwater.
• Electricity can be generated within 15 seconds of being switched from standby to generation. This
is much faster than conventional power stations.
Chemical energy:
• Electricity can be converted into chemical energy in rechargeable batteries and by the electrolysis
of water to produce hydrogen.
The environmental impacts of energy use
Candidates should have an outline knowledge of the environmental impacts associated with the
generation, transport and use of energy, including fuel extraction, site development and operation,
pipelines and cables, and waste disposal.
Fuel extraction
• Coal mining - habitat loss, dust, turbid or acidic drainage water
• Oil extraction - seismic surveys can harm whales, oil spills
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Fuel processing
• Oil refining
• Gaseous emissions such as carbon dioxide, oxides of nitrogen, particulates and hydrocarbon
vapours.
• Oil spills can pollute water bodies.
Manufacture of equipment
• The manufacture of any equipment used to harness energy will cause habitat loss from material
• extraction and pollution from manufacture eg metals, concrete, plastics.
Site development and operation
• Power stations and tidal barrages - site clearance, access roads, materials extraction and supply,
ash
• disposal
Waste disposal
• Coal spoil - aesthetics, habitat loss, acidic drainage, land-slip risk
• Radioactive waste - health risks: acute radiation poisoning, chronic cancer risk
Energy transport
• Pipelines - habitat disturbance
• Electricity cables - aesthetics, bird strikes
Future energy supplies
Candidates should be aware of the problems facing future energy supplies.
Depletion of existing resources
eg fossil fuels, wood
Environmental damage
eg combustion of fossil fuels releasing oxides of carbon, sulfur and nitrogen, smoke etc ,oil spills,
resource extraction, nuclear waste disposal, nuclear reactor accidents, impact of HEP reservoirs.
Increasing demand for energy
• caused by increasing affluence and population growth.
New technologies
New technologies may increase the amount of energy available for use by:
• increasing the amount of energy available from existing energy resources
eg underground gasification of coal;
• secondary oil recovery – gas or water pumped down an injection well to force oil to surface;
• tertiary oil recovery – steam, detergents or solvents injected into an injection well to force oil to
surface;
• use of fertile nuclear fuels, eg U238 converted to U239;
• parabolic solar reflectors to intensify light and increase energy density;
• heliostats to maintain the optimum angle of solar collectors.
o allowing new resources to be exploited
eg nuclear fusion – joining the atoms of isotopes of hydrogen at very high temperatures;
hydrogen as a secondary fuel.
Energy conservation
• Increasing the efficiency of energy use reduces the amount needed to perform tasks or allows
more to be achieved with the same amount of energy.
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Domestic energy conservation
• Low energy appliances
eg compact fluorescent tubes instead of filament light bulbs, low water use washing machines,
ovens with more insulation.
• Insulation of roof, walls, floors
eg with materials of low thermal conductivity – fibreglass, mineral wool, polystyrene, coir, paper
• Windows
eg shutters, thick curtains, double glazing, triple glazing
• Reduced wastage
eg turn off appliances when not required – lights, space heating, TVs, computers,
• occupancy sensors to turn lights off in unoccupied rooms.
Transport energy conservation:
Bulk transport
eg vehicles are used most efficiently if the minimum number of full vehicles is used and hence the most
appropriate choice is made between:
• car/bus/train for passengers;
• van/truck/train for goods.
Vehicle design
eg high aerodynamic efficiency to reduce friction losses as vehicle pushes air aside;
• good ignition control (eg electronic ignition) to ensure spark is timed to provide most efficient
combustion;
• thermostatically controlled fan to prevent unnecessary engine cooling before it has reached the
temperature for most efficient combustion;
• reduced mass by using fibre glass less strength required, shorter cable routes, more rounded
shape so less metal is needed;.
• fuel injection to deliver the optimum amount of fuel;
• energy recovery braking systems in ‘hybrid’ vehicles to generate electricity.
Modes of use
eg free-flow traffic systems avoid unnecessary stopping and starting, variable speed speed limits, eg
M25;
• do not use vehicles unnecessarily;
• travelling at speeds above or below the optimum (often 56 mph) increases fuel consumption.
Industrial energy conservation:
Heat recovery
eg heat exchangers to recover the heat from waste gases or liquids –. blast furnaces;
• heat recovery in Combined Heat and Power stations.
• The high voltage-low current electricity ‘supergrid’ allows the transport of high electrical power
with low energy losses.
Insulation
eg on furnaces and holding tanks for hot liquids.
Recycling
eg recycling used materials such as aluminium and glass avoids using energy for the extraction and
processing of new raw materials.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Integrated manufacture
eg combined iron and steel works where molten metal is processed rather than allowing it to cool which
would require re-heating.
Energy use and supply mix
The choices made within a society about the amount of energy used and the sources to be
exploited can affect other groups of people and societies.
Extravagant energy use in richer societies creates shortages that increases prices so some people do
not have access to sufficient energy or have to use sources which create other problems:
• unsustainable use of wood
• burning dung instead of using it as a soil conditioner
• the inability to pay for energy for use in homes, hospitals, water supply, food processing,
refrigerated
• food storage.
The NIMBY (Not In My Back Yard) approach of people to proposed new developments in there are may
cause more damaging developments in areas where people are less socially empowered.
3.3.2 Pollution
Pollution is energy or matter released into the environment with the potential to cause adverse changes
to an ecosystem. They are usually released by human activities but natural events can produce similar
effects.
General properties of pollutants
An understanding of the properties of familiar pollutants and why they have caused problems should
make it possible to predict the behaviour of new materials and therefore anticipate pollution problems.
Candidates should be able to give examples of pollutants which display:
States of matter
eg gases: carbon dioxide, CFCs, SO2
liquids: hot water, oil
solids: smoke particles, suspended solids in water, solid domestic waste
The state of matter affects dispersal in the environment
Density
eg dense ash, smoke or suspended solids in water settle close to the source
Point sources – identifiable source and effects.
eg tanker oil spill, power station, sewage outfall
Diffuse sources – many sources with combined impacts.
eg vehicle exhausts, agricultural pesticides
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Persistence/degradability – measure of length of time before the material breaks down.
eg pesticides, CFCs, dioxins
Toxicity
Most toxins damage proteins, usually by enzyme inhibition.
eg heavy metals, pesticides
Chemical reactivity
• Highly reactive substances are likely to be biologically damaging.
eg tropospheric ozone, acids
• They also tend to be less persistent.
• Secondary pollutants are produced by chemical reactions involving primary pollutants.
eg PANs in photochemical smogs
Solubility in water/lipids
• Water soluble pollutants are often mobile in the hydrosphere.
eg nitrates
• Liposoluble pollutants are more likely to bioaccumulate.
eg DDT, PCBs, heavy metals.
Mobility – the measure of the degree to which the pollutant is carried by wind, water or organisms.
eg smoke, acid rain, CFC, PCBs
Bio-accumulation – the absorption and storage of pollutants in the tissues of organisms.
eg heavy metals, chlorinated organic compounds (e.g. DDT, PCBs, dioxins)
Bio-magnification – the increase in concentration as a pollutant passes along a food chain.
eg heavy metals, chlorinated organic compounds
Synergistic action – the interaction of pollutants to create a greater impact than the sum of their
individual impacts.
eg SO2 and NOx, cadmium and zinc
Mutagenic action – the alteration of the structure of DNA.
eg many metals, ionising radiation, asbesto.
Carcinogenic action – mutagenic action which causes cells to become cancerous.
eg many metals, ionising radiation, asbestos
Teratogenic action – the interruption of DNA function so that the genes of an unborn embryo cannot
cause normal growth and development. Birth abnormalities may be produced (which are not inherited by
future generations).
eg dioxins, mercury
The behaviour of pollutants in the environment
All pollutants have sources, pathways and sinks.
A potential pollutant can only cause problems after it has been released from its source and become
mobile. The route it follows is called the pathway. This will determine its destination or 'sink'.
eg metals that are immobile in rock can become pollutants when leached from spoil by acid mine
drainage water.
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The properties of a material determine its behaviour, where it travels to and for how long it acts.
eg SO2 dissolves in rainwater so causes problems relatively close to the source.
CFCs are chemically stable and have low solubility in water so they persist in the atmosphere for years.
Environmental monitoring is used to detect and quantify pollutants.
Sampling sites are usually:
• where winds or water are most likely to carry the pollutants;
• where people may be harmed;
• where human activities occur. eg farming, fisheries
Critical Pathway Analysis is used to predict the movement of pollutants and to plan monitoring
programmes.
eg the movement of radioactive materials released from a nuclear power station or waste processing
site.
Direct and indirect effects
Direct effects – the pollutant causes harm by contact with or ingestion by living organisms.
eg toxic pesticides; acid rain damaging roots and leaves; oil smothering shore life.
Indirect effects – the pollutant does not harm the organism directly but causes harmful environmental
changes.
eg ozone depletion; global climate change; deoxygenation by organic matter; leaching of plant nutrients
and mobilisation of toxic ions by acid drainage water.
Candidates should appreciate the distinctions between chronic and acute effects of pollution:
• Chronic: symptoms or effects are long lasting or appear gradually.
eg bioaccumulation of small doses of lead
• Acute: symptoms or effects are short term or appear rapidly.
eg oil spills
Atmospheric pollution
Global atmospheric system
Effective controls require national and international legislation and agreement to control trans-boundary
pollutants.
eg UN Convention on Long-range Transboundary Pollution (1979) (The Geneva Convention) - an
agreement to control acid rain and other atmospheric pollutants.
Kyoto Protocol (1997) - an agreement to reduce emissions of greenhouse gases.
Montreal Protocol (1987) - an agreement to reduce emissions of ozone depleting substances.
Mediterranean Action Plan (1975) - an agreement to protect the Mediterranean Sea, including the control
of oil pollution and waste dumping.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Acid rain
Rain is naturally acidic (pH 5.6) as carbon dioxide dissolves from the atmosphere and produces carbonic
acid.
The major causes of acid rain
• SO2 and SO3 from the burning of fossil fuels, especially coal.
• NOx released from hot combustion processes such as internal combustion engines and power
stations.
• Other gases increase the impact of the acidic gases, eg ozone which oxidizes SO2 to SO3 which
dissolves to produce a more powerful acid (sulfuric instead of sulfurous).
The direct effects of acid rain
On non-living material:
• damage to some building stones such as limestone.
• corrosion of metal structures such as railway track and overhead power cables.
On living organisms:
• phytotoxicity as acids damage cells in stomata, root hairs.
• seed germination is inhibited by acidic conditions.
• lichens are especially sensitive to acids.
• death of aquatic organisms due to damaged exoskeleton development as the calcium compounds
become more soluble.
• respiratory illness such as asthma and bronchitis are more common and can lead to pulmonary
(heart) disease.
The indirect effects of acid rain
Acid rain can also harm organisms by causing other changes that are harmful to living organisms.
• soil can be deflocculated by acids where the particles that form peds separate causing the peds to
collapse, filling the soil spaces and making the soil less permeable.
• acids increase solubility of ions of metals such as calcium and aluminium ions.
• sulfur is an important plant nutrient, although it is rare for it to be a limiting factor.
• heavy metals such as lead and mercury are more soluble under acidic conditions.
• increased susceptibility to pests and disease
The use of biotic indices to monitor sulfur dioxide concentrations.
The presence/absence and state of development of different species can be used to monitor acid rain
pollution and estimate the mean concentration of sulfur dioxide.
Some areas are more sensitive to the effects of acid rain.
eg areas with naturally acidic soil, shallow soils, winter snows and spring melts, low soil calcium levels.
Tropospheric ozone
The origins of tropospheric ozone
Tropospheric ozone is produced by the photochemical breakdown of primary pollutants (NOx, CO,
hydrocarbons) and their interaction with oxygen.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
The harmful effects of tropospheric ozone
• Ozone causes inflammation and damage to sensitive tissues such as eyes, nasal tissue, lung
tissue and plant leaves.
• Health effects include respiratory irritation, asthma and permanent lung damage.
• Ozone can oxidise other substances to produce secondary pollutants.
eg in photochemical smogs or SO2 to SO3 in acid rain
Formation of smogs in basin topography with temperature inversions
Air temperature in the troposphere normally declines with increasing altitude. A temperature inversion
occurs when there is a layer of unusually cold air near the ground. Pollutant gases in this layer are
cooled, become more dense, less buoyant and disperse less.
Temperature inversions are most likely:
• when there is little or no wind;
• when night skies are cloudless;
• mist or fog reflects sunlight;
• valley topography allows cold air to collect.
Lapse rate diagrams are used to show the change in temperature with change in altitude under normal
conditions and when there is a temperature inversion.
Candidates should be aware of the two forms of smog
Smoke smogs
• If smoke and fog are present at the same time then a 'smog' will form.
The sources of smoke
Suspended particulate matter (SPM) from:
• deforestation and burning crop waste
• incomplete combustion of fossil fuels and organic matter. eg combustion of coal, diesel, biofuels
The effects of smoke smogs
• Corrosion and disfiguration of buildings and other structures;
• respiratory disease eg bronchitis;
• damage to leaf cuticles, blockage of light and a reduction in photosynthetic efficiency.
Photochemical smogs
• The word 'smog' is misused here as photochemical smogs do not involve smoke or fog. The
similarity is that they also involve temperature inversions.
Causes of photochemical smogs
• NOx, waste hydrocarbons and tropospheric ozone react in the presence of sunlight to produce
PANs (peroxy acetyl nitrates). Dispersal is reduced and concentrations are greatest when there is
a temperature inversion.
The effects of photochemical smogs
• respiratory problems eg asthma, breathing difficulty and an increased risk of heart attack.
• damage to leaf cuticles.
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Air pollution controls
General methods
Legislation
Examples:
Clean Air Act (1956) - smoke pollution
• use of fuels that release a lot of smoke eg untreated coal, is banned in most large cities in the UK
Montreal Protocol (1987) - ozone depleting substances
• manufacture of CFCs and most uses are banned
Environmental Protection Act (UK,1990) - various pollutants, including dust
• water sprays may be required to suppress dust from industrial sites
Conventions on world climate such as Kyoto (1997), Cape Town (2003).
• a range of provisions, including targets for reductions in greenhouse gas emissions
Efficient use of energy; energy conservation
Any activity that reduces energy use will produce a proportional reduction in pollutant emissions.
Fuel substitution
eg natural gas releases less smoke and carbon dioxide than coal per unit of energy released.
Specific methods
SO2, SO3
Flue-gas desulfurisation (FGD)
eg wet FGD; SOx are dissolved in a wet scrubber spray. Dry FGD: SOx are reacted with calcium
carbonate (crushed limestone) to produce calcium sulfate.
Some processes produce sulfur, sulfuric acid or gypsum (calcium sulfate) which can be used as raw
materials in the chemical industry.
NOx
•
•
•
•
Low temperature combustion reduces the amount of NOx produced. eg in fluidized bed power
stations
Catalytic converters in vehicle exhausts.
NOx undergo chemical reduction back to O2 and NO2.
Urea sprays in power stations and boilers convert NOx to nitrogen, carbon dioxide and water.
Smoke
• More efficient combustion produced by increasing oxygen supply or the mixing of the combustion
gases reduces the amount of smoke produced.
• Electrostatic precipitators reduce smoke releases by attracting the smoke particles to wires or
plates that have a static electrical charge.
• Cyclone separators use the rotation of the exhaust gases in a cylindrical chamber to separate the
smoke particles (thrown to the outside) from the cleaner gases for discharge (in the middle).
• Scrubbers trap suspended smoke particles using a fine spray of water.
Methane
• Methane release from landfill sites can be reduced by collecting it for use as a fuel, or by using
alternative disposal methods eg recycling or incineration.
• Coal mining and oil extraction can release methane which can be collected and burnt to convert it
to carbon dioxide. The energy can be used if large enough amount of energy are involved to make
it economically viable.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
CFCs
CFC releases have been reduced in several ways:
• use of alternative materials eg HCFCs in refrigerators, hydrocarbons in aerosol sprays, alcohols
as solvents.
• use of alternative techniques eg trigger action sprays instead of aerosol sprays.
• waste CFCs can be broken down by incineration.
Water pollution
Water bodies, including coastal waters and oceans are often the final sink for pollutants. Pollutants in
water are relatively mobile, being carried by moving water such as rivers, ocean currents and
groundwater flow.
Factors that influence pollutant concentration:
(many of these are inter-connected)
Size of emissions
• Larger emissions will produce higher concentrations.
Volume of water
• Releases into small water bodies will produce a higher concentration, such as a lake or bay
compared with an ocean.
Residence time of water
• Pollutants in a lake with a short residence time will reach a lower concentration than in one where
the inputs and outputs of water are lower.
Degradation
• Pollutant concentrations will be lower if they are chemically broken down. The rate may be
increased by light (photodegradation) or living organisms (biodegradation). Other factors such as
temperature, pH and the presence of oxygen can also affect the rate of degradation.
Removal rate of the pollutant
• Removal of the pollutant from a particular location by degradation or moving air or water will
reduce the concentration.
Dispersal.
• Dispersal by air, water or living organisms will reduce the local concentration but may increase the
area that is affected.
Thermal pollution
• Heat pollution is mainly caused by hot condenser water from power stations.
Ecological consequences
• Many species have a limited range of thermal tolerance. Excessively high temperatures may
cause enzyme inhibition.
• The temperature-dependence of gas solubility in water means that the concentration of dissolved
gases such as oxygen is lower at higher temperatures. This may kill sensitive species eg trout.
• Increased rates of chemical reactions occur at higher temperature, such as the breakdown of
sewage by aerobic bacteria.
The use of cooling towers to lower effluent water temperature
• The heat from the water can be dispersed into the atmosphere using a water spray in a cooling
tower. The water can then be safely discharged back into the river or lake.
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Oil pollution
Causes:
• disposal of used vehicle lubricants into drains or where they may wash into rivers
• accidental damage or leakage from ships, oil tankers, storage tanks, oil pipelines, oil refineries, oil
drilling rigs
discharge of tank washing water from oil tankers.
Effects:
• oil smothers aquatic life, especially on shores. It stops light penetration, gaseous exchange and
prevents movement and feeding
• some hydrocarbons are toxic
• oil reduces the thermal insulation of birds’ feathers, leading to hypothermia
• floating oil provides a barrier that inhibits the dissolving of oxygen from the atmosphere
• contamination with oil means birds must spend more time cleaning which reduces the time
available for feeding and feeding of their young.
Control:
• waste oil can be recycled to make more lubricating oil or burnt as fuel
• better maintenance and operation of ships and oil rigs
• double hulled tankers are less likely to leak oil if the ship is damaged
• separate oil and water ballast tanks on tankers means that emptying ballast water does not
release oily water
• oily waste water can be unloaded at refineries rather than being discharged at sea
• oil traps can be used to collect oil from drainage water
• a range of techniques can be used to treat oil pollution:
o detergents/dispersants to break up oil into smaller droplets;
o absorbent materials pick up oil and can be removed from the water ;
o floating booms prevent the dispersal of the oil;
o skimmers use rotating wheels to which the oil sticks. The oil can then be scraped off.;
o bioremediation breaks the oil down by bacterial respiration. This works most effectively in
warm climates;
o contaminated seashores can be cleaned by steam washing.
Pesticide pollution
• Most pollutants are released by accident or because the methods that could have prevented
release are not used. Pesticides are spread because they are toxic, but they may kill more than
the intended target organisms.
Properties of pesticides which make them more likely to cause pollution:
Specificity
• No pesticides are exclusively toxic to the pests. Insecticides that kill pests also kill butterflies, bees
and other beneficial insects.
Persistence
• Some pesticides are chemically stable and do not break down quickly eg DDT. This gives them
time to spread more widely and have longer-term effects.
Bio-accumulation
• Liposoluble pesticides tend to build up in fat and oil droplets in cells. eg DDT. Small, regular
doses may eventually build up to levels that are toxic.
Bio-magnification
• Bio-accumulation in individual organisms can lead to further increases in concentration along a
foodchain.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Mobility
• Pesticides that are persistent and dissolve in water are present in living organisms or form
atmospheric droplets can be spread widely in the environment.
• A comparison of pesticides which are more and less harmful.
eg Organochlorine, organophosphate and pyrethroid insecticides.
• Organochlorine insecticides, eg DDT, lindane, aldrin, dieldrin, are very persistent, are liposoluble,
bio-accumulate and bio-magnify. They have high insect toxicity but low mammal toxicity and do
not normally cause mammal deaths at application concentrations.
• Organochlorine insecticides, eg malathion and parathion, are not persistent and do not cause the
same problems as organochlorines, but they have much higher mammal toxicity. They are
derived from chemicals that were developed as nerve gases for use as weapons.
• Pyrethroid insecticides, eg pyrethrum, permethrin, are not persistent and have low mammal
toxicity, although they are toxic to other insects and to fish.
Effects:
Direct effects:
• death/ill health of non-target species, especially taxa closely related to the pests and organisms
near the end of food chains eg birds of prey, pelicans, otters, humans.
Indirect effects:
• other species are affected eg due to lack of food, pollinating insects, organisms involved in
nutrient cycling or the death of the predators of their competitors
Control methods:
• most harmful pesticides banned or restricted, especially those that biomagnify up food chains or
are very toxic to humans eg DDT, dieldrin and 2,4,5 T are banned in most countries,
organophosphate use is restricted;
• preferred use of non-persistent, non bio-accumulative, specific pesticides, eg pyrethroids;
• no spraying on windy days, to reduce spray drift onto surrounding areas;
• only spray when the risk of pest damage is high, to reduce unnecessary use;
• avoid use in more sensitive areas, eg next to rivers and hedgerows;
• use other non-chemical methods when possible, eg biological control, crop rotation, selective
breeding of pest-resistant varieties;
• careful disposal of containers eg to avoid spillage into streams.
Nutrient pollution
A nutrient is a substance that increases the growth of an organism. Surplus nutrients in water cause
excessive growth that can cause problems, but inorganic and organic nutrients do this in different ways.
Inorganic pollutants
Nitrates
Sources:
• fertiliser runoff from farmland
• released during decomposition of organic matter
Effects:
• on humans: blue-baby syndrome (methaemoglobinanaemia), stomach cancer
• on aquatic environment (cultural eutrophication) (see below).
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Control:
• use of slow release fertilisers
• nitrate control areas
• oil not ploughed and fertilisers not applied during wet weather
• buffer strips left uncultivated near rivers
Phosphates
Sources:
• sewage effluent, silage fluids, fertiliser runoff
Effects:
• cultural eutrophication: algal blooms release toxins, shade macrophytes, break normal food
chains and cause deoxygenation when the dead algae decompose.
Organic pollutants
Sources:
• many plant and animal products: sewage, manure, silage fluids, food-processing waste, effluent
from paper mills and leather tanneries.
Effects:
• deoxygenation due to bacterial decomposition
• pathogens may spread disease eg typhoid, dysentery, cholera, E. coli
Control – effluent treatment
Candidates should be familiar with the purposes and principles of the processes in a sewage treatment
works.
Screens: metal grills or filters to trap paper, plastic and large non-faecal solids
Grit trap: effluent slows and dense road grit is deposited
Primary sedimentation: effluent is allowed to stand so faecal solids sink and form sludge
Aeration/activated sludge treatment: aerobic bacteria digest remaining organic matter
Trickling filter beds: microorganisms living in a bed of inert rock particles digest the remaining organic
matter (an alternative to activated sludge treatment)
Secondary sedimentation: the effluent is allowed to stand so remaining solids settle
Tertiary treatment:
• phosphate removal, by adding iron sulphate to produce an insoluble phosphate sludge
• microstraining to remove any remaining bacteria
Sludge treatment: anaerobic bacteria partially digest the organic matter, producing a smaller volume of
less hazardous sludge and methane that can be used as a fuel.
Sludge disposal: use as a fertiliser, incineration or landfill.
Acid mine drainage
Sources:
• The oxidation of sulfur from sulfide ores can produce sulfuric acid leading to acidic leachate water
that may contain dissolved toxic metals from the mine spoil heaps.
Water pollution monitoring
Candidates should be aware of the advantages and disadvantages of the assessment of water quality by
physical, chemical and biological methods.
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Physical and chemical tests for pollutants can give precise, accurate, quantitative results but the results
are instantaneous and do not give a longer-term assessment or a measure of how values vary.
Turbidity is measured as Total Suspended Solids (TSS). The units used are mg l-1.
Acidity is measured using the pH scale.
Nitrates can be measured using a colourimeter.
Concentrations of organic wastes are not measured directly. Biological Oxygen Demand (BOD) estimates
the amount present by the amount of oxygen used up by bacterial respiration.
The coliform count is used to monitor sewage pollution through the abundance of the bacterium E. coli
which is always present in human sewage.
Biotic Indices and Indicator Species give an assessment of pollution now and in the recent past. The
results are given numerical values but these do not relate to precise pollutant concentrations.
eg Trent Biotic Index for aquatic invertebrates
BMWP (biological monitoring working party)index for aquatic invertebrates
the abundance of the dipper, which is a bird that is absent from polluted rivers
Species that are most suitable for pollution monitoring are sensitive to pollution, normally present, easy to
find and identify, and generally distributed.
Heavy metal pollution
Most heavy metals have no physiological functions and cause damage by enzyme inhibition, especially of
the nervous system and, in high doses, the liver and kidneys.
General properties of heavy metals
Bio-accumulation
• small doses of heavy metals can build up to toxic levels
Bio-magnification
• concentrations can build up along food chains
Synergistic action
• the combined effects of some metals can be much greater than the sum of their individual effects
e.g. of cadmium and zinc
Control by increasing pH
• because most heavy metals are more soluble at low pH, treatment with lime or an alkali will
reduce the solubility and mobility
Lead
Sources:
• lead from water pipes can dissolve into drinking water
• lead used as an anti-knock agent in petrol can be inhaled as fine particles
• lead in paint can be inhaled as dust or fumes during paint removal
• lead dust in industry can be inhaled or dissolved in sweat and absorbed through the skin
Controls:
• in most countries lead is no longer used in water pipes, petrol or paints
• in industries using lead dust is removed by filters, respirators are worn by workers and regular
blood tests are used to check for raised levels
• low temperature paint removal using chemical strippers reduces atmospheric concentrations
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Mercury
• To illustrate the importance of chemical form on the severity of pollution: all mercury compounds
are toxic, but organic compounds are much more toxic than inorganic compounds or elemental
mercury. They are also more fully absorbed into the body in the gut or dermally through the skin
eg methyl mercury.
Noise pollution
Effects of noise pollution
Effects on organisms
• deafness (damage to hair of cells of cochlea), especially to high frequency sounds
• tinnitus
• stress leading to raised blood pressure and possibly to increased risk of heart disease
• nervous disorders or behavioral changes
• reduced educational attainment caused by the inability to work or communicate effectively when it
is noisy
• livestock disturbance can cause injury or miscarriage
• wildlife can be disturbed, leading to breeding failure eg cliff nesting birds deserting their nests
when disturbed by aircraft
Effects on objects
• noise vibrations can cause ‘acoustic fatigue’ where stress cracks appear resulting in structural
damage.
• sudden loud noises can cause damage to windows, roofs etc
Sources of noise and its control
Industrial machinery noise
• Especially equipment with metal on metal contact
eg stamping machines or expanding air such as compressors for driving pumps or pneumatic
drills
• Controlled by: sound insulation, hearing protection, limited periods of exposure, changed
industrial processes eg presses instead of stamping machines, education.
Transport noise
Road vehicle noise
Controls:
• vehicle design: quieter engines with better noise insulation, better exhaust systems with more
acoustic baffles
• vehicle use: no excessive acceleration or breaking
• vehicle routing: to avoid residential areas
• noise absorption: embankments, baffle mounds, tree planting, double glazing of buildings, noise
absorbing road surfaces
Aircraft noise
Controls:
• aircraft design:
o quieter engines eg high bypass turbofans used on modern civilian airliners, compared with
low bypass turbofans used on jet fighters. Older civil airliners can be fitted with ‘hushkits’
which mix the exhaust gases with the surrounding air.
o more aerodynamic surfaces eg landing gear fairings
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
•
•
•
•
•
aircraft operation:
o ban or phase out noisy aircraft eg Concorde, Boeing 707, 727, 737
o constant approach angle (3o)
o delay extension of flaps and landing gear
airport location:
o away from residential areas
airport design:
o taxi areas, engine test areas away from nearest residential areas
airport operation:
o flight paths not over residential areas
o restricted night flights
acoustic insulation:
o double glazing of nearby houses
Railways
Controls:
• vibration absorbing ballast under the rails
Domestic sources of noise (kitchen appliances, garden equipment, music)
Controls:
• improved sound insulation eg using ear defenders
• considerate use eg the timing of use of DIY and garden equipment
• education regarding the dangers of exposure to noise
Measuring noise pollution
The units used take into account the sensitivity of human hearing (volume and frequency range):
• dB scale for sounds that are audible to humans
• dBA scale - weighted for the sounds to which the human ear is most sensitive
• NNI scale - used for aircraft noise, includes the number of aircraft and their individual noise levels
Ionising radiation
Effects of ionising radiation on living organisms
Production of free radicals resulting in tissue damage (mutations, cancer).
Energy of ionising radiation absorbed and converted into chemical energy, causing abnormal chemical
reactions.
These may affect DNA and therefore general cell function and future cell division, leading to cancer or
birth abnormality. High doses may damage membranes and enzymes, causing reduced function and
possibly death.
Exposure levels related to source, distance and period of exposure and use of barriers
Sources of radiation exposure
Natural (eg granite and products of its weathering) and caused by human activity (eg uranium mining,
nuclear fuel cycle, TVs).
Uses of radioactive materials
Candidates should be aware of the range of uses of radioactive materials which involve risks but provide
benefits. The principle of Risk:Benefit Analysis.
eg the nuclear power industry, research – radio labelling, medical uses, pest control, food preservation.
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Environmental monitoring
Candidates should know the materials which are likely to be sampled to test for contamination by
radioactive materials.
eg water, air, dust, grass, fish, milk, soil, seaweed and human populations
Critical Pathway Analysis: the prediction of the movement of pollutants in the environment.
Critical Group Studies: the identification of those members of the public that, due to their lifestyles, are
most at risk.
Solid wastes
The sources of the different types of solid waste:
• Mining and construction
• Municipal (domestic and commercial)
• Industrial
• Agricultural
Properties of solid waste:
• Composition relating to bulk and mobility
• Degradability
• Hazardous nature including fire risk
• Radioactivity
• Toxicity
Control of solid waste
The link between waste and affluence
Built-in obsolescence, convenience, disposable products, over-packaging.
Methods of solid waste treatment
The advantages and disadvantages (including economic and environmental) of disposal by:
• Landfill and land raising on derelict land/exhausted quarries.
• Incineration and pyrolysis of household and industrial wastes.
• Encapsulation / vitrification of high-level radioactive waste.
Salvaging and recycling
The reduction of resource exhaustion and waste production including:
Efficient use of resources within a manufacturing enterprise to include extraction efficiency and
production loops
Trimmings from plastic mouldings/paper cutting.
Resource substitution to use a more abundant material instead of a less abundant one, eg
plastics replacing wood/metal
eg car interiors, furniture
Re-use and recycling of resource materials to include composting
eg local authority organic waste shredding and composting
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Teacher Resource Bank / GCE Environmental Studies / Teachers’ Notes Unit 3 / Version 1.0
Economic assistance
Recycling of building rubble is made more economic by the Aggregates Tax which puts a tax on
quarrying sand, gravel and crushed rock.
Candidates should be aware of the scientific/technological, social and economic limitations of these
procedures with reference specifically to aluminium and the relative energy costs of extraction from
bauxite or recycled cans.
eg:
•
•
•
•
•
•
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some material is unavoidably dispersed and lost;
mixed alloys of metals cannot be recycled for use where pure metal or a different alloy is required;
the extra transport required for collection creates other resource use and pollution problems;
recycling schemes can be labour-intensive;
used materials which are not separated and sorted by the user may be difficult to recycle;
good recycling schemes require the cooperation of the consumer.
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