Pollution Flashcards
What is a pollutant?
A substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource.
- Can be naturally forming or anthropogenic forming.
Examples of gaseous pollutants:
- Sulphur dioxide from fossil fuels
- Carbon dioxide form fossil fuels
- Nitrous oxides from car exhausts
- CFCs from aerosols, fridges etc
Examples of liquid pollutants:
- Oil form leaks or spills
- Pesticides
- Fertilisers
- Liquid industrial waste
- Sewage
- Hot water form power stations
Examples of solid pollutants:
- Smoke particles
- Suspended solids in water
- Solids domestic waste (rubbish)
- Mining waste
- Solid industrial waste
Examples of energy pollutants:
- Noise
- Ionising radiation
- Heat
- Light
How does the density of a pollutant affect pollution?
The denser the particles of solid the closer to the source they settle.
In gases denser air sinks nearer source
In liquid denser particles sink more quickly
How does the source of pollution affect the pollution caused?
Point of source - from a definite place has a definite effect e.g. oil spills from a tanker
Diffuse source - from many sources with combined impacts e.g. car exhausts
How does persistence/degradability affect pollution?
- A measure of the length of time before a material breaks down
- Have to biodegrade within a certain amount of time in the lab to be sold
What are POPs and what has been done to reduce them?
- Persistent organic pollutants (POP) do not degrade in the environment and have negative health effects
- Stockholm convention 2001 took action to reduce/eliminate production of POPs
What are the effects of POPs?
- Nearly wiped out the bald eagle
- Transboundary pollution threatening Antarctica
- Decline of wildlife
- Disease and abnormalities on living creatures
- Reproductive impairment
How does toxicity affect pollution?
And what is an example of a persistent heavy metal?
Toxic chemicals = inhibit enzymes, damage the nervous system and damage organs.
E.g. lead. It is a neurotoxin, accumulates in soft tissues and bones, causes blood and brain disorders
How does chemical reactivity affect pollution?
- Very reactive chemicals do not last long in the environment, may be highly toxic though
- Chemicals can react to form a secondary pollutant which is WORSE
What are PANs?
How are they mad?
What issues do they cause?
Peroxy Acetyl Nitrates
- Made from NOx from car exhausts and oxygen in the air and unborn hydrocarbons
- Reacts in sunlight to make PANs
- Toxic and irritating to eyes, lungs and plants
How does specificity affect pollution?
And an example?
- Specific toxin will affect specific organisms
- Non-specific toxins will affect all organisms
E.g. Pyrethroids
How does adsorption affect pollution?
What’s the problem?
When molecules stick onto the outside of another particle
E.g. pollutants sticking to soil particles
PROBLEM: they can be releases later on
Examples of adsorbents?
- Ice clouds adsorb chlorine
- Silica
- Activated carbon/zeolite in H2O purification
- Uranium clean up using polymer resins
- Catalytic converters honey comb shape or platinum to convert pollutants
How does solubility in water/lipids affect pollution?
- Water soluble pollutants are often mobile in the hydrosphere e.g. nitrates
- Liposoluble pollutants are soluble in fats and are more likely to bioaccumulate e.g. DDT, PCBs and heavy metals
How does mobility affect pollution?
Mobility is the measure of the degree to which the pollutant is carried by wind, water or organisms.
E.g. smoke, acid rain, CFCs, PCBs
What is bioaccumulation and how does it affect pollution?
- The absorption and storage of pollutant in the tissues of organisms e.g. heavy metals, DDTs, PCBs
- It occurs when an organism absorbs a toxic substance at a greater rate than that at which the substance is lost.
So the longer the biological half-life of the substance the greater the risk of chronic poisoning.
What is biomagnification and how does it affect pollution?
It is the increase in concentration as a pollutant passes along a food chain, up the tropic levels.
E.g. heavy metals, chlorinated organic compounds, the chlorine makes them resistant to degradation.
What is synergism and how does it affect pollution?
And what is an example of this?
- When two or more pollutants effects interact to create a different effect, usually a more serious one.
E.g. ozone damages leaf cuticles which enables sulphur dioxide to cause more damage to the newly exposed cells.
What is mutagenic action and how does it affect pollution?
- Agents which cause changes in the chemical structure of DNA by damaging chromosomes by rearrangement of the DNA structure (mutations)
- Gonadic effects = birth abnormality in the offspring produced.
- Somatic effects = most are harmless, can cause cancer, where uncontrolled cell division produced a tumour.
E.g.s ionising radiation, UV light, Chlorinated organic substances, cadmium, asbestos.
What is carcinogenic action?
- Mutagens that cause cancer, creating tumours that can prevent normal tissue function.
What is teratogenic action?
- Causes birth abnormalities by preventing normal gene expression.
- Do not change DNA but inhibit the function of proteins and enzymes that the DNA would normally have controlled
- Cannot be inherited by future generations because the DNA structure is not affected.
How does temperature affect degradation?
Chemical reactions will speed up as temp increase, so degradable pollutants will break down more rapidly at higher temperate, but more rapid degradation can lead to problems like deoxygenating.
How does light levels affect degradation?
Provide the activation energy that drives chemical reactions involving pollutants e.g. photochemical smogs and the photo-degradation of some pesticides.
How does oxygen affect degradation?
Aerobic bacterial decomposition of sewage, oxidation of sulphide ores producing sulphur dioxide, oxidation state affects the solubility if many metals.
How does pH affect degradation?
Affects the solubility of substances, many heavy metals are more soluble and therefore mobile under more acidic conditions.
How do pollutant interactions affect degradation?
Behaviour of a pollutant may be affected by the presence of other pollutants e.g. interaction of NOx and hydrocarbons in photochemical smogs, the combined effect of phosphates and and nitrates in eutrophication.
How does water and wind currents affect dispersal?
Velocity and direction of air and water currents will affect how far a pollutant is dispersed and how much it is diluted.
How do temperature inversions affect dispersal?
Temperature inversion traps pollution close to the ground especially smog.
How does presence of an adsorbent material help to reduce pollution?
- Pollutants may adsorb onto materials such as clay particles or organic materials in aquatic sediments.
- It may immobilise the pollutant and stop it causing problems
What is CPS and how does it help to control pollution?
- Predict the movement of potential pollutants in the environment to assess the severity and location of the pollution that may occur
Factors that may be included in CPA: - Properties of pollutant = state of matter, density, solubility in water/lipids, chemical stability
- Features of the environment = wind and water currents, geology, pH, oxygen availability, temperature
What is CGM and how does it help to control pollution?
- Assessing the risk of public exposure to pollutants
- It assess the risk to members of the public who are most at risk
- If their risk is acceptably low, then it is assumed that all other members of public have an even lower risk
How does control of emissions location help to control pollution?
Severity of pollution is affected by the location where the discharges are released.
E.g. water currents will dilute and disperse emissions, emissions downwind of urban areas, not discharging waste onto permeable rock above an aquifer.
How does control of emission timing help to control pollution?
Changes in the timing of emissions can affect the severity of pollution e.g. tidal cycle and temperature inversion
What is the polluter pays principle?
Organisation or person that causes pollution is responsible for any problems caused, giving them an obligation to prevent it
What is the precautionary principle?
Assumes that a waste will cause pollution if released, until research confirms it is unlikely to do so when release may be permitted. It is safer than releasing waste that has not been analysed on the hope it is safe.
What is selection of the control methods?
Production prevention, prevention of release, post-release remediation, alternative processes.
What is the problem with efficiency of pollution control?
- Can be expensive
- ALARA approach = emissions should be As Low As Reasonably Achieved
E.g. selecting new equipment that is BATNEEC - Best Available Technology, Not Entailing Excessive Costs
What does photochemical smogs need to form?
When the ultraviolet light from the sun reacts with nitrogen oxides or VOCs present in the atmosphere.
What are PANs?
Peroxyacetyl nitrates = a group of chemicals formed when pollution soup reacts with sunlight
- It is a secondary pollutant
- Serves as a carrier for oxides of nitrogen into rural regions and causes tropospheric ozone formation.
What is lapse rate?
The atmospheric lapse rate - the change of an atmospheric variable with a change of altitude, the variable concerned is temperature.
How do temperature inversions occur?
The normal temperature gradient in the atmosphere is altered as the air temperature at the earth’s surface is cooler than the air at higher altitudes.
- this traps pollution close to the ground.
What are the favourable conditions for a temperature conversion?
- Long winter nights
- Cloudless and clear sky
- Dry air near the ground surface
- Slow movement of air that reduces mixing of heat in the lower layers of the atmosphere
Ground surface covered with snow that reflects light
How can VOCs be reduced?
Bans/legislation
How can reduced combustion be achieved?
Electric vehicles/heating , reduce temperature of industrial processes
How can reduction of solid emissions (PM10) be achieved?
Catch and filter pollutants, catalytic converters, use of smokeless fuels
How do Electrostatic Precipitators work?
By changing the smoke particles:
- electrodes cause particles to become negatively charged
- the negatively charged particles are attracted to the walls made of positively charged plates
What are the advantages of electrostatic precipitators?
- Good for very fine particles
- Don’t constrict air flow = so factory doesn’t overheat and fill with smoke, or catch on fire
- Filter doesn’t need replacing so the process doesn’t need to stop
How do cyclone separators work?
Centrifugal and inertial forces are used in a cyclone to separate particulate from the contaminated gas stream as it spirals through the cyclone
What are the advantages of cyclone separators?
- For larger particles
- Simple
- Cost effective
- Low every needed
How does a Wet Scrubber work?
- Sodium sulphite reacts with the acidic gases making sodium hydrogen sulphite.
- This can be heated to release the sulphur dioxide
- Can be used to make solid sulphur or sulphuric acid.
How does a Dry Scrubber work?
- Calcium carbonate reacts with the sulphur dioxide to form Calcium sulphate.
- This is known as gypsum and key ingredient in making plaster
How can coal be treated before burning?
- Heated the coal vaporises the tar, and thus makes smokeless coal
- Bag filters - they trap the PM10 in a fabric bag
How about fuel burning the fuel more efficiently?
- Burning fuel in O2 so it burns more cleanly.
- Fitting a turbo charger to burn diesel more efficiently.
What is acid rain and how does it form?
Acid rain = any rain with a pH lower than 5.2
- When fossil fuels are burnt they react with water and other solutions to form NOx and SO2.
How is sulphuric acid formed?
- Hydrocarbons containing sulphur compounds in them are burnt the sulphur reacts with oxygen to form sulphur dioxide gas (SO2)
- This then dissolves in water to form sulphurous acid (H2SO3)
- Sulphurous acid is then oxidised by oxygen in the air to from sulphuric acid (H2SO4)
How are oxides of nitrogen formed?
Nitrogen and oxygen in the atmosphere —> car engines ‘internal combustion’ —> fuel is mixed with the air and is ignited —> nitrogen and oxygen react —> NOx + water in clouds forms dilute acid
What is nitrogen dioxide?
What problems does it cause?
And how can they be reduced?
- Nitrogen dioxide is a toxic red-brown gas, and it causes respiratory diseases such as bronchitis.
- Catalytic converters in cars convert most of the NOx in exhaust gases into harmless nitrogen.
What are the three important legislations?
- The Clean Air Act 1956
- Roland and Molina 1974
- Kyoto protocol 1997
What is emissions trading?
Countries are able to trade ‘excess’ carbon = this is the amount that they have saved through efficiency measures e.g. legislations and amount of forests
What is the EU trading scheme?
January 2005, where companies are issued with pieces of paper that grant them permission to emit a certain quantity of CO2 into the atmosphere in a a year.
Companies that don’t have enough permissions to cover their emissions can buy them from someone who does.
How can attitude to pollution emissions change change as countries become more developed?
More affluent countries = more money individually so can afford more cars increasing pollution. But can also pay for offshoring where other counties have the factories and cause the pollution elsewhere.
More developed countries = more education, more money for research so make action plans to reduce emissions and can afford to be more sustainable.
How does carbon tax work?
- Industries which emit carbon dioxide will have to pay a tax of up to $12 a tonne of carbon dioxide emissions from 2007.
- This results in raise of petroleum price by 12% and gas/electricity prices by 8%.
- The tax revenue obtained would be used to offset other taxes and into climate change.
How is the UK trying to reduce carbon emissions?
- UK climate change levy 2001, a domestic objective to reduce carbon dioxide emissions by 20% by 2010 and 60% by 2050
What’s a biotic indicator?
- Species which have narrow range of tolerance
- Can only live in specific conditions
What is an example of a biotic indicator?
Lichens as they are very intolerant of pollution specifically SO2 and acid rain
Lichens are a partnership between fungi and algae
What are the types of lichen?
- Crusty lichen = most tolerant of polluted air
- Frilly, shrubby, leafy = clean air spaces
- String of sausages = super clean air spaces
How does degradation influence pollutant concentration?
- Pollutant concentration decreases if it is chemically broken.
- The rate can be increased by light or living organisms.
How does residence time of water affect pollutant concentration?
- Pollutants in a lake with short residence time will reach lower concentration than in one where the inputs and outputs of water are lower.
How does volume of water affect pollutant concentration?
- Releases of pollutants into small bodies will produce a higher concentration.
How does removal rate of a pollutant affect pollutant concentration?
Removal of the pollutant from a particular location by degradation or moving air or water will reduce the concentration.
How does dispersal affect pollutant concentration?
Dispersal by air, water or living organisms will reduce the local concentration but may increase the area that is affected.
How does size of emissions affect pollutant concentration?
Larger emissions will produce higher concentrations.
What’s the EU trading scheme?
- January 2005 companies were issued pieces of paper that grant them permission to emit a certain quantity of CO2 in a year
- If they don’t have enough permissions to cover their emissions they will have to buy them from someone who does
How can attitude to pollution emissions change as a country becomes more developed?
More affluent countries - have more money individually so can afford more cars which increases pollution, however they can also afford to pay for offshoring, where other countries have the factories and are causing the pollution elsewhere where.
More developed countries - more education, more money for research so can make action plans to reduce emissions and can afford to be more sustainable.
How does carbon tax work?
- Industries which emit carbon dioxide will have to pay a tax of up to $12 a tonne of carbon dioxide emissions from 2007.
- This results in raise of petroleum price by 12% and gas/electricity prices by 8%.
- The tax revenue obtained would be used to offset other taxes and into climate change.
How is the Uk trying to reduce carbon emissions?
- UK Climate Change Levy 2001 = domestic objective to reduce carbon dioxide emissions by 20% by 2010 and 60% by 2050
What is a biotic indicator?
- A species with a narrow range of tolerance
- Can only live in specific conditions
What is an example of a good biotic indicator?
Lichens = very intolerant of pollution, specifically so2 and acid rain
They are a partnership between fungi and algae
What are the three types of lichen?
Crusty = most tolerant
Frilly, shrubby, leafy = clean air
String of sausages = very super clean air
How does degradation influence pollutant concentration?
How does volume of water influence pollutant concentration?
How does size of emissions influence pollutant concentration?
How does removal rate of pollutant influence pollutant concentration?
How does dispersal influence pollutant concentration?
How does residence time of water influence pollutant concentration?
What happens to aquatic animals at higher water temperatures?
- Not enough O2 to survive
- Increases their metabolic rate so they will need more oxygen
- Grow to fast
- Eggs hatch earlier
- Warmer climate species may invade
- Toxicity greater of some pollutants
- Resistance to disease may reduce
What is thermal pollution?
- Heat pollution mainly caused by hot condense water from power stations
What are the ecological consequences of thermal pollution?
- Many species have a limited range of tolerance, rlly high temps may cause enzymes to denature.
- Temp-dependent of gas solubility in water means that the concentration of dissolved gases such as oxygen is lower at higher temps.
- May kill sensitive species
- Increased rates of chemical reactions occur at higher temps
How does a cooling tower work?
- Water needs to be low mineral content, neutral pH , zero particulates = internal circuit of water.
- Hot water sprayed down.
- Cold air is wafted up.
- Cold water collects at bottom.
- Hot air and steam leaves at top.
What are the main causes of oil pollution?
- Poor disposal of vehicle lubricants
- Damage to or leakage from oil rigs, pipelines, tankers, etc
- Discharge of tank washing water (to prevent accumulation of tarry residues) from oil tankers
What are the effects of oil pollution?
(Indirect)
- Reduces dissolution of O2 at water surface
- reduced breeding success as birds unable to locate mates by sense of smell - affects pheromones
What are the effects if pollution?
(Direct)
- Smothers and asphyxiates molluscs
- Some components are toxic - carcinogen
- Water proofing and thermal insulation of bird feathers lost -> hypothermia
- Ingested oil prevents digestion -> starvation
What ways are there of treating oil pollution?
- Detergents will break up the oil into smaller droplets which disperses it.
- Absorbent materials e.g. straw picks up oil
- Skimmers use rotating wheels to which the oil sticks and can be scraped off.
- Oil-digesting bacteria can be sprayed on the oil
- Floating booms
- Steam washing can clean contaminated shorelines - heats the oil makes it less viscous = runny
What are the adaptations made to an oil tanker?
- Multiple engines + navigation systems
- Multiple propellers and rudders
- Double hull
- Smoke/exhaust gas back filing to stop explosion
- Separate water ballast tank -> to stop ship from capsizing so it keeps the ship as a balanced weight
What are the adaptations of liquid oil storage?
- Impermeable oversight
- Volume inside bund wall must be equal to the storage tank
What are the properties of a pesticides?
- Mixed specificity
- Poisonous, carcinogenic, toxic, neurotoxic to humans
- Toxic to non target species = bees and butterflies
- Enters water ways = Kills water plants and invertebrates
- Persistent = low water solubility
- Lipid soluble = go into organisms = bioaccumulation = biomagnification
- Synthetic = often not biodegradable
What does MDAF stand for ?
Minimum does always fatal = the least you can use which kills everything
What does MDNF stand for?
Maximum dose never fatal = the most you can use which doesn’t kill anything
What is the correct dose control to not kill non-target species?
MDAF less than MDNF of the non target species
No overlap = not accidental killing of non target species.
What are the main sources of inorganic nutrients?
- Phosphates in sewage effluent and eroded soil particles
- Nitrates washed off farmland from manure and artificial fertilisers
What is cultural eutrophication and the process?
Eutrophication is the enrichment of a water body with nutrients, usually with an excess amount of nutrients.
What causes cultural eutrophication?
- Human activities such as the discharge of phosphate-containing detergents, fertilisers, or sewage.
- Clearing of land and runoff
What is an Oliotrophic lake?
Few nutrients, little plant growths e.g. Mountain lakes
What is an eutrophic lake?
Rich in nutrients, abundant plant growth e.g. Lowland lakes
What happens during eutrophication?
- Influx of nutrients results in algal bloom
- Floating algae shade the submerged macrophytes so they cannot photosynthesise = death = anaerobic respiration = deoxygenation
- Death and decay of algae = deoxygenation
- Cyanobacteria can release harmful toxins = affects livestock, pets and people in contact/drinking the water
What are the human health effects of of nitrates?
Nitrates are very soluble and may be ingested from water sources, where the bacteria in the gut converts it into nitrites which react with haemoglobin and reduce its ability to carry oxygen.
What are the effects of nitrates on babies?
Babies have high levels of the bacteria so it can cause diseases such as methaemoglobinaemia AKA blue baby syndrome
How can nitrates cause cancer?
Gut bacteria can convert nitrates into nitrosamines which are carcinogenic and can cause stomach cancer.
What ways can we control inorganic nutrients?
- Reduced use of nitrate fertilisers
- reduced ploughing at times of heavy rain
- Use soluble, rapid-release fertilisers
- the deposition of waste manure where the nutrients will not leach into the ground or be washed into a river
- Reduce high nitrogen requiring crops
- reduce reliance on artificial fertilisers
What are NVZs?
Nitrate Vulnerable Zones = where aquifers may be exposed at the surface and can become contaminated
What are other ways to mange and limit the effects of inorganic nutrients?
- Adding iron (III) sulphate to remove phosphates from liquid effluents released by sewage treatment works, the phosphates are precipitated as a fine sediment of iron phosphate.
- Dredgin
G lakes and rivers that have phosphate rich sediment from past pollution or adding iron (III) sulphur to reduce the solubility of the phosphates
What are the main sources of organic nutrients?
Sewage works, manure disposal, silage storage, leather tanneries, paper mills and food processing plants.
- Carbohydrates, lipids and proteins.
What are the effects of organic nutrient pollution?
- Deoxygenation: organic nutrients provide food for microorganisms in the water. Their aerobic digestion deoxygenates the water and may kill aerobic organisms such as fish and insects. Eutrophication can also occur with organic nutrient pollution as microbial decay releases inorganic nutrients.
- Pathogens: Sewage can contain pathogens from infected people. This can allow diseases to spread through sewage and water e.g. cholera, typhoid and dysentery.
- Inorganic nutrient release: organic nutrients do not cause eutrophication directly as they provide nutrients for heterotrophs not nutrients for photo autotrophs. However, as they decay they may release inorganic nutrients which can cause eutrophication.
What ways can we treat organic effluents?
- Ban on dumping sewage into rivers
- The effluent received by a sewage works so the concentration of sewage in the water is low.
What are the main groups of treatment processes involving activated sludge treatment?
- Pre-treatment = the removal of solid objects such as paper, plastic, road grit.
- Primary treatment = the separation of most organic solids from fluids.
- Secondary treatment = the digestion and break down of the remains organic matter in the fluids.
- Tertiary treatment = additional treatment to remove phosphates or bacteria
- Sludge treatment
What are pre-treatment methods?
- Screens: metal grills or sieves are used to trap floating and suspended items.
- Grit traps: for stones and grit traps. Wide channels reduce the velocity of the effluent so the grit sinks and doesn’t flow with the effluent,
- Comminutors: chop up suspended faecal solids, increasing the exposed surface area and speeding up later processes.
What is primary treatment?
Sedimentation: effluent is left to stand in large tanks where the faecal solids sink to bottom so that they can removed separately. Removing 95% of the organic matter.
What is secondary treatment?
- Destroys the small amount of organic matter that remains in the effluent from the primary sedimentation tank.
- Aeration tanks/oxidation pods: remaining organic matter broken down by bacteria, air is mixed in by paddle wheels or air stones.
- Secondary sedimentation tanks: removes suspended bacteria
- Trickling filter beds: four rotating arms spray liquid effluents over large cylindrical tanks, contains lumps of solid material such as gravel, coke or blast furnace.
What is tertiary treatment?
- Used if the discharge site for the treated effluent is particularly ecologically sensitive or important to humans.
- Phophates can be removed by adding solution of iron (III) sulphate producing insoluble iron phosphate as fine as sediments which can be used as a fertiliser
- can be strained through micro-strainers, the remains bacteria killed by UV light
What is sludge treatment?
- Sludge removed from primary sedimentation tanks probably contains pathogens.
- Anaerobic microbes digest the sludge in a warm digestion tank for about four weeks
- Killing most pathogens and the odours are reduced.
How can the remains after sludge treatment be disposed of?
- Landfill: cheap and simple but wastes nutrient content
- Dispersal in the sea: pollution
- incineration: expensive and needs a lot of fuel, creating further waste
- Agriculture use: used as a fertiliser
- Anaerobic respiration also produced biogas which can be used as a fuel.
What is acid mine drainage?
Many igneous metal ores are sulphides. In spoil heaps chemical reactions take place between the small amounts of remaining sulfide ores and oxygen from air in the spaces between the waste particles. This may leave metal oxides and oxides of sulfur which dissolve in drainage water to produced sulfuric acid.
What are the effects of acid mine drainage?
Acidic solutions that leach put of the spoil heap have a similar effect to acid rain. The pH of the solutions is often very low and may contain toxic metals if they were present in the mine waste.
How can we control acid mine drainage?
The pH of the drainage water can be increased by passing it through crushed limestone to neutralise the acids. This will also reduce the solubility of many toxic metals.
Describe the logarithmic nature of the dB scale:
- each bel is divided into ten decibels
- an increase in volume of 10dB represents a tenfold increase in sound volume
- an increase of 3dB represents a doubling volume
What is the frequency range of human hearing?
20-20000Hz
What is acoustic fatigue?
- some objects have a frequency at which they will naturally vibrate = natural resonant frequency
- if exposed to a sound of this frequency then they will vibrate, which may cause stress cracking and structural failure
What is vibration damage?
- repetitive vibration can cause structural damage to buildings, bridges and underground pipes
- this can be caused by the vibrations created by the wheels of heavy vehicles
What are shock impacts?
- force of the impact of a sudden very loud noise can cause damage such as the sonic boom of supersonic aircraft jet engines causing structural damage to buildings
What are the effects of noise on humans?
- hearing damage: long-term exposure to loud machinery
- stress-related health problems: ulcers, high blood pressure, heart disease
- behavioural changes: irritability, aggression, lack of concentration
- communication problems: difficult to hear others talking
What are the effects of noise on other living organisms?
- livestock: sudden noises may cause panic leading to injuries or failure to breed
- disturbance of breeding birds: birds that sing to establish their territories or attract mates may have difficulties in urban areas because of noise levels, may be sacred away by noise abandoning their nests
- reduced feeding success: animals that use hearing to find food e.g. bats, owls, dolphins may not be able to do so
- hearing damage/behavioural changes: cetaceans such as whales and dolphins can be harmed by noises like military sonar to detect submarines, cause it mass stranding of cetaceans
How do airforces plan low flying training flights to minimise noise nuisance problems?
- major urban areas are avoided
- UK has 13 major avoidance areas
- flight paths are varied
- UK divided into 20 low flying areas of which three are tactical training areas
- it is possible to request a temporary stop to low flying e.g. for horse shows
- low flying times are published when practical
- compensation may be paid for damage caused to livestock
- flight may avoid ecologically sensitive sites such as seabird cliff breeding colonies
How are civil aircraft flights kept to reduce as much noise as possible?
- civil aircraft cruise altitude is high enough that little or no sound reaches the ground
- many airports are located close to urban areas to reduce travel times to and from the airport
Why are airports located away from major population centres?
- minimise the number of people affected
Why’s re taxi areas away from residential areas?
- taxiing before takeoff can increase noise levels for nearby residents
What are engine test areas?
- where engines are tested on the ground at high thrust, are located away from residential area, are only used during the day and are surrounded by acoustic screens
What is acoustics insulation?
- buildings affected by aircraft noise may have free acoustic insulation provided e.g. double glazing
What are land use restrictions?
- may be restrictions on land-uses near airports allowing industry but not housing developments
What is noise deflection/absorption?
- baffle mounds and acoustic barriers can deflect or absorb noise around a busy airport
What are the point of multiple landing runaways?
- allows for more time for slowing down, so the wheel brakes can be used which are quieter then reverse thrusters
What’s are high bypass-ratio engines?
Modern jet engines have a second cowling and a turbofan on the front of the jet that forces ‘bypass air’ around the inner cowling
- the bypass air smooths the flow of the exhaust air and reduces noise levels, the bypass ratio is the ratio of bypass air: jet exhaust gases, the higher the ratio the quieter the engine
What are chevron nozzles?
- used on high bypass engines to make them even quieter
- a serrated trailing edge on the outer cowling mixes the bypass air with the surrounding air more smoothly
What are engine hush kits?
- work like chevron nozzles and can be fitted to low bypass ratio engines to make them quieter
What are engine acoustic liners?
- used inside the outer cowling and around the inner cowling to absorb noise
What is a blended wing aircraft?
- engines are located on the top of the aircraft so the body acts as a barrier reducing the noise that reaches the ground
What are aerodynamics?
- fairings on the undercarriage reduce turbulence around the wheels and leg struts
- fairings covering wing flap hinges reduce turbulence around
- riveted construction creates surface indentations which create turbulence and noise, welded panels create less turbulence
How are aircraft’s made lighter?
- using composite materials such as carbon fibre, makes aircraft lighter so less engine thrust is needed
How can take of angle reduce noise?
- aircraft’s are nosier when taking off then landing as the engines are running at a higher power so if the take off angle is steep it allows the aircraft to climb more rapidly where it reaches an altitude where it isn’t heard on ground
How can flight path planning reduce noise?
- flight path routes are planned to avoid densely populated areas whenever possible
How does a constant decent angle reduce noise?
- constant angle for the final decent before landing makes the engine noise less intrusive, no periods of high thrust as there are with a stepped decent
- steeper decent angles allows aircraft’s to stay at greater altitudes for longer, so ground level noise is further reduced
How do night flight restrictions reduce noise?
Most airports near large residential areas restrict the number of night flights especially take offs
How do noises limits help to control noisier aircraft’s?
- aircrafts are categorised into groups according to whether they meet increasingly strict noise limits
How do charges for nosier aircraft reduce noise?
- aircraft pay charges do using airports, at many airports the charge is based on noise levels, at Heathrow noisiest aircrafts pay 10 times as much as similar sized quieter ones.
- night flights cost nearly three times as much as day flights
- fines for breaking noise limits
His do restricted flight times reduce noise?
- airports near high population density areas often restricts or ban night flights
- takeoffs are controlled more than landings because they are nosier
What is a quota count system?
- airports encourage airlines to operate quieter aircraft’s by resting flight times for nosier aircraft’s or using a points system
- aircraft types are allocated points, each airline are allocated a certain number of points, the total point score of the actual fights must not exceed their allocation
How does control of supersonic flights reduce noise?
- no longer any supersonic civil airlines
How is wheel vibration from trains controlled?
Track polishing and sound absorbing ballast
How is engine noise from trains controlled?
Sound absorbing suspension
How is pantograph turbulence from trains controlled?
Aerodynamic fairing
How is wheel squeal on corners from trains controlled?
Lubrication of wheels/track
How is breaking squeal from trains controlled?
Use of composite material breaks
How is wheel noise from trains controlled?
Good carriage suspension
How is wheel noise from road traffic controlled?
Sound absorbing road materials such as porous asphalt or asphalt that includes shredded rubber from old vehicles
How is vehicle air turbulence from road traffic controlled?
Improved vehicle aerodynamics
How is engine noise from road traffic controlled?
Acoustic insulation around the engine = quieter exhaust pipes
How is general road vehicle noise from road traffic controlled?
- traffic may be rerouted to avoid more sensitive areas
- fences, embankments, walls and dense tree planting can reduce noise
- double glazing windows
How industrial noises controlled?
Air compressors and pumps = silences to reduce explosive expansion of air
Stamping machines = alternative processes
Metal conveyers = use of nylon bearings, wheels or rollers
Mine blasting = regular timing, baffle mounds
Pile driving on land = drilling instead
Pile driving at sea = air bubble curtains
Marine seismic surveys = acoustic survey decides to detect cetaceans before use
What are general methods used to control industrial noise?
- sound absorbing surfaces in the room
- sound absorbing materials around equipment
- machinery placed on acoustic mat
- sound absorbing materials as part of the equipment
- remote machinery operation
- worker ear protection
How is domestic noise controlled?
- domestic appliances with acoustic absorbers
- wearing ear defenders while using power tools
- volume limiters on music equipment
- selection of quieter domestic appliances
- control of pet dogs
What modifications are being made to the dB scale?
It takes into account the sensitivity of human hearing by weighing sounds between 1000 and 4000Hz
How can road traffic noise levels be measured?
LA10 = measures noise exceeded for 10% in any set period = good for noisiest
LA90 = measures noise level exceeded for 90% in any set period = good for quiet
Traffic Noise Index (TNI) = produces a representative measure of traffic noise using LA10 and LA90
L10 (18h) = measure assumes that noise is only a problem during the 18 hours between 6am and midnight
How can aircraft noise levels be measured?
Effective Perceived Noise Levels (EPNL) = estimate of the relative loudness of a particular type of aircraft during takeoff and landing
Noise and Number Index (NNI) = combines the number of flights and the noise levels of aircrafts above 80dB as it is presumed that aircraft below 80dB do not cause serious annoyance
Let 57 dB: let is an average sound level over a particular period, for UK airports and average of 57dB between 7am and 11pm in the summer is used, levels above this are considered annoying
What factors determine what method of monitoring water pollution is used?
- speed of data collection
- level of expertise required
- degree of accuracy
- indication of long-term historical pollutant levels
- methods that are specific to individual pollutants
- measurement of the effects of pollution rather than the levels of pollutant itself
What is biochemical oxygen demand (BOD)?
- organic materials of plant or animal origin can provide food for bacteria and lead to deoxygenation as they respire anaerobically
- organic pollution is monitored through the level of deoxygenation that is caused, the amount of oxygen being used is measured under standardised conditions
What are the standardised conditions for BOD?
1 litre of water
20’C
5 days long
In the dark = to prevent oxygen replacement by photosynthesis
What is chemical oxygen demand?
COD = measures the amount of oxygen needed to chemically oxidise all the organic and inorganic substances in a water sample
What is a coliforms count?
- E.coli is a common gut bacteria, presence in water is taken as confirmation of faecal matter
- the health risk can be determined by measuring the number of coliform bacteria in a sample as this indicates how serious the contamination is
What are biotic indices?
Biotic index is a scale for showing the quality of an environment by indicating the types of organisms that are present
What characteristics of species are used in biotic indices?
- have different sensitivities to pollution
- are easy to find
- are easy to identify
- are normally present
- are usually common
- are generally distributed
What are the advantages and disadvantages of biotic indices?
ADV:
- rapid assessment of current and recent pollution can be made
- equipment needed is not expensive
DIS:
- sorting samples is time consuming
- identification involves skill
- further tests are required using other techniques to detect the specific pollutant present
What are two commonly used biotic indices?
Lichens to monitor atmospheric acidic pollution
Aquatic invertebrates to monitor water pollution
What are the key properties of heavy metals?
- heavy metals inhibit enzyme function esp. in three nervous system
- heavy metals are liposoluble meaning they may be stored in fat, which can cause bioaccumulation, which can pass along the food chain and may lead to biomagnification
- if they act in conjunction with other pollutants it can cause synergism
- they are more soluble at low pH, therefore pollution caused by heavy metals can be reduced by increasing pH
What are the sources of lead pollution?
- lead-acid batteries, lead flashing used in building construction
- industrial workers may inhale lead or dust or absorb it through their skin if it dissolves in sweat
What are the effects of acute lead exposure?
- brain damage, paralysis, death, very high doses can kill by causing liver and kidney failure
How can water pipes control lead pollution?
How can petrol additives control lead pollution?
How can electrical solder control lead pollution?
How can lead-based paint control lead pollution?
How can fishing weights control lead pollution?
How can shotgun pellets control lead pollution?
What are the sources of mercury?
- disposal of items containing mercury e.g. batteries, thermometers
- chemical plants that produce chlorine using mercury electrodes
- combustion of coal
What are the effects of chemical form on the toxicity of mercury?
- liquid mercury is not easily absorbed through the skin or gut, although vapours may be absorbed in the lungs if they are inhaled
- inorganic mercury can be absorbed in the gut
- organic mercury e.g. methyl mercury are absorbed easily through the skin, gut and as vapours, they are liposoluble so can affect the brain, kidneys, placenta to harm unborn babies.
How is mercury pollution controlled?
- mercury thermometers have been replaced with alcohol or electronic
- mercury can be removed from effluents by reverse osmosis or activated carbon filters
- ion exchange filters
- disposal at high pH to reduce solubility
What are the sources of cadmium?
- disposal of old nickel-cadmium batteries
- incineration of wastes containing cadmium pigments
- drainage water from cadmium and zinc mines
What are the effects of cadmium?
Liposoluble and bioaccumulates so chronic exposure can lead to toxic concentrations which:
- brain damage and paralysis
- lung cancer
- kidney failure
- skeletal collapse caused by bone decalcification
How is cadmium pollution controlled?
- restriction or bans on cadmium such as its use in pigments
- cadmium waste should be disposed of in a hazardous waste landfill site or may be recycled
What were the previous uses/sources of tin?
- antifouling paint on the bottom of boats to control growth of marine organisms that create friction
- the chemical was tri-butyl tin TBT which is an endocrine disruptor that alters the growth and reproductive philology of marine organisms which can pass to humans when they eat them
- it is now prohibited and replaced with copper
What are the effects of iron pollution?
- iron is not toxic but it can cause deoxygenation when it is oxidised in water
- it is soluble in its chemically reduced form
How is iron pollution controlled?
Spoil heap drainage water is collected and passed over mesh screens where the iron becomes oxidised and is deposited on the mesh when the water flows into the river there is no longer a risk of deoxygenation
