Atmospheric Pollution Flashcards
Name 2 ways in which pollutants can behave differently because they are dispersed in the atmosphere and not in water
- more rapid movement due to wind leads to dispersal over wider areas
-secondary pollutants occur more often because of the more frequent interactions with electromagnetic radiation can cause more chemical reactions
Name the 5 different types of atmospheric pollution you need to know
Smoke smogs
Photochemical smogs
Acid rain
Tropospheric ozone
Carbon monoxide
What are the 5 types of atmospheric pollution to learn?
Smoke and smoke smogs
Photochemical smogs
Acid rain
Tropospheric ozone
Carbon monoxide
What is smoke made up of?
Particles produced by the incomplete combustion of carbon based materials
How is smoke categorised
By the size range of particles
What does PM10 mean?
Particulate matter that is less than 10 microns in diameter
what does PM5 mean?
Particulate matter that is less than 5 microns in diameter
What does PM1 mean?
Particulate matter that is less than 1 micron in diameter
Why is particle size important?
Because smaller particles remain in the atmosphere for longer so are more likely to be inhaled
What are some toxic chemicals that can be found in smoke?
Fluorides,Aluminium,Lead,Acids,Organic compounds like phenol
How does smoke act with with other atmospheric pollutants? Can you give a named example?
Act synergistically
Sulfur dioxide
What does the exact composition of smoke depend on?
The source
What is the main source of smoke in urban areas?
Combustion of coal,diesel and general combustible wastes
What is the main source of smoke in rural areas?
The combustion of crop waste, wood fuel, grasslands and forests
What are the effects of smoke pollution on humans?
Respiratory diseases e.g. Bronchitis, asthma and lung cancer
Chemicals on/in smoke particles can kill cilia in bronchioles
This can make it more difficult to clear the lungs of inhaled particles and bacteria
Which can increase the risk of infections and some of the chemicals might be carcinogenic
What is the impact of smoke pollution on living organisms (other than humans)?
It can reduce photosynthesis in plants because the smoke blocks the light
Substances in smoke may be toxic for them, such as heavy metals and acids
What effect can smoke pollution have on non-living things?
It can damage buildings due to acids and organic solvents they may contain
It is also expensive to clean buildings that are dirty from smoke
Summarise the impacts of smoke pollution on the climate
Reduction of temperature
A ‘Nuclear winter’
Particles can remain in the atmosphere for long time periods
Ozone depletion
How can smoke pollution reduce temperatures?
Because smoke has a high albedo, meaning it reflects light so the light doesnt reach the ground where it may have been absorbed and converted to heat
Where can smoke particles remain for a long period of time?
They are small and can remain suspended in the atmosphere
Especially in the stratosphere where there is no rain to wash it out
What is the link between smoke and the ozone layer?
Smoke in the stratosphere can deplete the ozone layer
What is it called when smoke and fog are present together?
Smog
When does fog form?
When moist air is cooled until it reaches dew point so the water vapour condenses as airborne water droplets
What makes fog formation more likely?
Temperature inversions
What is concerning about the smoke in smogs?
It is very easily inhaled
What is a property of smogs that relates to the length of a temperature inversion?
Smog has a high albedo so the temperature inversion can last for long periods of time
This allows pollutant levels to increase to a high level
Example of a serious smog event
London smog 1952
Describe the geographical position of London that made the smog more likely
London is in a valley, there has been pollution problems since the 1200s which have increased as the city has
What weather conditions led to the smog in 1952?
There was 5 days of anti cyclonic weather in December 1952, which produced clear. Skies and low wind velocities so a temperature inversion formed, and atmospheric pollutant levels rose
How may died in the 1952 London Smog?
12’000
Mainly old people or very young or those with existing respiratory problems
What legislative measures are there to control smoke pollution in the UK?
The Clean Air Act (1956)
Which restricted the use of fuels that produce smoke in large urban areas of the UK
What control measures are there for smoke pollution from domestic sources?
An increase in fuels that dont produce smoke e.g. Natural gas, electricity
What control measures are there for smoke pollution from transport sources?
DPFs are fitted in the exhaust pipes of diesel engines which trap up to 80% of smoke particles
DPF
Diesel particulate filter
What control measures are there for smoke pollution from industrial sources?
Electrostatic precipitators
Cyclone separators
Scrubber
Coal treatment
Bag filters
How do electrostatic precipitators control industrial smoke pollution?
Effluent gases are passed through a chamber that has electrically charged wires/plates
The smoke particles in the gases are attracted to these so collect together
As they accumulate, they fall to the floor as fly ash
Where are electrostatic precipitators often used as a pollution control method?
In coal-fired power stations
How are cyclone separators a pollution control method/ how do they work?
Like air/waste in a vacuum cleaner, effluent gases are forced to rotate in a cylindrical chamber
This throws particles to the outer surface of chamber, causing them to fall and collect
This cleanses gases and they are then discharge via a pipe in the centre of the cylinder
How can a ‘scrubber’ be a smoke pollution control method/ how does it work?
It uses a fine what’re spray to wash suspended solid particulate matter and dissolve soluble gaseous pollutants
How does coal treatment control smoke pollution?
Heating coal so the tar that causes smoke production is drained off
This produces smokeless coal
How do bag filters control industrial smoke pollution?
Remove smoke particles from effluent gases by trapping them on a fabric filter
Describe how combustion technology could be more efficient and the role of oxygen
A lot of smoke particles are made from organic matter that hasn’t burnt completely so if oxygen is supplied and efficiently mixed with some particles then they can completely be burnt to gases
What kind of engines produce the most smoke and why?
Diesel engines when the driver accelerates too quickly
Too much fuel enters the engine for the amount of oxygen available to burn it
Give an example of more efficient combustion technology
Turbo chargers
They enable more air so more oxygen is delivered to combustion chamber, it increases the efficiency of combustion
Why is the term ‘photochemical smog’ slightly inaccurate ?
They dont involve smoke or fog so no conventional smog
How are photochemical smogs similar to smoke smogs ?
Because they involve urban pollution during temperature inversions in valleys
What pollutants are involved in photochemical smogs?
There are a wide variety of reactions that happen between primary and secondary pollutants in the presence of sunlight, including UV light
NOx are one of the primary pollutants that are involved in photochemical smogs. What releases them?
Exhaust gases from petrol/diesel engines are a source in urban areas
NOx are formed by fuel combustion. True or false?
False
They are formed by the nitrogen and oxygen from the air that is drawn into the engine and they react with each other under the high temperature and pressure conditions in the engine
Why in Nitrogen dioxide dangerous/involved in photochemical smogs?
It is toxic at high concentrations but they are only normally reached in more polluted cities.
However, in the presence of sunlight and other pollutants, they can produce more toxic secondary pollutants like PANS
What is another pollutant, that when present causes nitrogen dioxide to result in the production of the secondary pollutant, PANs?
Hydrocarbon vapours
Unburnt hydrocarbons are what?
A primary pollutant involved in photochemical smogs
What are the source of unburnt hydrocarbons?
Unburnt fuel in engine exhaust gases
Fuel evaporation from fuel tanks
Spillages
Name 3 photochemical pollutants
NOx
PANs
Tropospheric ozone
PANs
Peroxy Acetyl Nitrates
What are the effects of NOx as a photochemical pollutant?
They increase the risk of respiratory infection e.g. colds,flu. Bronchitis
They can make health conditions worse e.g. asthma and heart disease
What are the effects of PANs as photochemical pollutants?
They are toxic at lower concentrations than NOx
They cause eye irritation, breathing difficulty, asthma, emphysema
They can also result in an increased risk of heart attacks
What is the effect of tropospheric ozone as a photochemical pollutant?
They contribute to the production of PANs but they are toxic themselves
The cause asthma, bronchitis and heart disease
Why are some cities prone to photochemical smogs?
Because of their topography
Areas were the traffic congestion is severe, the climate is sunny and temperature inversions are common
What are some cites prone to photochemical smogs?
LA, México city,Paris,Beijing,Athens
How can NOx and hydrocarbons be controlled to control photochemical smogs?
Using catalysts like platinum and palladium in exhaust pipe catalytic converters
NOx can be chemically reduced in the converters to re-form oxygen and nitrogen
How can unburnt hydrocarbons be controlled to control photochemical smogs?
Catalytic converters can oxidise them to CO2 and water
Vapours at filling stations can be collected, condensed and returned to the main fuel tan, or they can be collected and passed through an activated carbon filter where hydrocarbons absorb onto the carbon particles
How can photochemical smogs be controlled?
By controlling the release of primary pollutants to prevent the formation of secondary pollutants that they react with
What PH is rain naturally?
5.6
Slightly acidic
Why is all rain naturally acidic?
Because naturally occurring CO2 in the atmosphere dissolves in it to produce a dilute carbonic acid, which is a weak acid
What is acid rain?
The name given to any precipitation that is more acidic than a PH of 5.6
What is the cause of acidic rain?
A combination of pollution problems that is caused by a range of acidic gases, and other pollutants that contribute to the problems
What gases are involved in acid rain?
The main gases are sulphur dioxide, and oxides of nitrogen, but other gases include hydrogen chloride and ozone
How is sulphur dioxide involved in acid rain?
It dissolves in water to produce sufurous acid or it may be oxidised by ases in the atmosphere like ozone to make sulphur trioxide
Sulphur trioxide is dissolved to produce sulphuric acid which is a more powerful acid than sulfuros acid
Sulfuros acid or sulphuric acid. Which is a more powerful acid?
Sulphuric
How are oxides of nitrogen involved in acid rain?
They dissolve to produce nitrous and nitric acids
How is hydrogen chloride involved in acid rain?
They dissolve to form hydrochloric acids
How is ozone involved in acid rain?
In the oxidation of sulphur dioxide to trioxide
It also directly harms plants
What is the source of the sulphur dioxide that is involved in acid rain?
The combustion or oxidation of material containing sulphur, especially the burning of coal and smelting sulphide ores
What is the source of oxides of nitrogen that are involved in acid rain?
High temperature combustion, especially in power stations and petrol/diesel combustion engines
What is the source of ozone that is involved in acid rain?
It is a secondary pollutant that is produced by photochemical reactions involving NOx
What is the source of hydrogen chloride that is involved in acid rain?
The combustion of coal or the incineration of wastes containing chlorine like PVC plastic waste
What is the source of sulfur trioxide that is involved in acid rain?
The oxidation of sulfur dioxide by ozone
What effects does acid rain have on non-living things?
Acid deposition corrodes meta, so can damage railway lines,metal railings,water pipers,pylons & overhead power lines
Buildings and statues that are limestone can be damaged by acids because they issolve the surface layers and weaken the stone structure of porous limestone
In what 2 ways can acid pollution harm living organisms?
Directly by the acids in the rain
Indirectly where they cause environmental changes that can be harmful
Acids can be harmful to all living organisms, but why can the effects differ between species?
Different species have different ranges of tolerance
How does acid rain affect cells?
Low PHs (Acidic) can denature proteins in cell membranes and can inhibit enzyme action
Tissues that have living cells that are exposed to the environment are most likely to be damaged by acid rain
Examples of tissues most likely to be damaged by acid rain
Cells inside leaf stomata
Plant root hairs
Germinating seeds
Fish eggs
Fish gills
How might invertebrates be affected by acid rain?
Those what exoskeletons may die because the acids dissolve the calcium compounds that form the skeleton
What species may be used to monitor acid rain pollution and why?
Lichens because they are very sensitive to acidic conditions
Their size, state of health, abundance and diversity may be used in a biotic index to monitor acid rain pollution
How can sulphur dioxide involved in acid rain pollution, affect humans?
It can create breathing difficulties and increase the frequency of respiratory problems like asthma attacks
How can acid rain pollution affect metal ions and how can this indirectly affect living organisms?
The solubility of metal ions is effected by PH, more soluble at a low PH
The acidic solutions can percolate soil,leach metal ions, so plant nutrients like calcium and magnesium are lost
Once these are gone, other ions are mobilised which usually aren’t as they are absorbed onto the surface of clay particles
These include aluminio and lead which are toxic
The toxic ions that are mobilised in soil because of acidic solutions from acid rain leaching metal ions, such as aluminum and lead, have what effect?
The toxic ions inhibit enzyme action in plant root hair cells and other soil organisms e.g. detrivores & decomposers
The mobilised toxic ions may be leached into rivers/lakes where they can harm aquatic animals
How can metal ions leached out of the soil because of acid rain affect human health?
Lead is a neurotoxin, and there is some evidence that aluminium ions may be a factor associated with some neurological disorders
Name 3 environmental factors that can affect the severity of acid rain
Soil lime content
Fog
Snow
How can soil lime content affect the severity of acid rain?
Soils with high lime content include CaCO3 which neutralises acids and reduces the impacts of acids on soil PH
How can fog affect the severity of acid rain?
Acid precipitation in rain only has brief contact with leaves of vegetation
In areas with fog, acidic water droplets might be in contact with leaves of trees for longer periods, so damage by acids might increase
How can snow affect the severity of acid rain?
Areas that have alo of snow may accumulate acidic snow
If it melts quickly, meltwater will be very acidic and can harm life in soil and rivers
What are the methods of controlling oxides of sulphur in order to control acid rain?
Natural gas desulfurisation
Crude oil desulfurisation
Coal desulfurisation
FGD
Dry FGD
Wet FGD
FGD
Flue gas Desulfurisation
How is sulfur controlled in areas like the North Sea and california?
Only low sulphur fuels can be used by ships
Why is natural gas desulphursaition important?
Hydrogen sulphide is removed from natural gas after it has been extracted to prevent corrosion damage to refinery and pipeline equipment and to the appliance in which the gas is used.
This also prevents the production of sulphur dioxide when burned
How is natural gas desulphurised?
By dissolving it in amine solution or reacting it with iron particle
What is crude oil desulphurisation?
The removal of sulphur compounds from crude oil during distillation using molybdenum catalysts in the process of hydro desulfurisation
How does coal desulfurisation work?
It is removed by washing and streaming
The coal is crushed then put in a stream of flowing water
The flow rate is fast enough to carry coal away but leave denser pyrites
When are the different Flue-gas desulfurisation processes used?
To remove sulfur dioxide from power station emissions that are released after combustion
Describe the process of Dry FGD
Flue gases are passed through a bed of crushed calcium carbonate
The sulphur dioxide reacts with calcium carbonate producing solid calcium sulfur
If the effluent gases in dry FGD have ben cleaned to remove smoke particles, what can they be used for?
The calcium sulfate produced might be pure enough to produce gypsum building plaster
What is the reaction for dry FGD?
2CaCO3 + 2SO2 -> 2CaSO2 + 2CO2
What happens in wet FGD?
Involves sodium sulfate scrubbing where the flue gases are bubbled through a sodium sulfate solution
Sodium hydrogen sulfate is reduced because it absorbs the sulfur dioxide
What can the sodium hydrogen sulfite produced in wet FGD be used for?
It can be heated so it breaks down to produce sodium sulfite and water which are reused, and concentrated to prue sulphur dioxide
This is a valuable industrial raw material and can be converted to solid sulphur or sulfúrico acid
What is the chemical reaction for wet FGD?
Na2SO3 + H20 + SO2 -> 2NaHSO3
What are 3 methods of controlling the oxides of nitrogen to control acid rain?
Low temperature combustion
Catalytic converters
Urea sprays
How does low temperature combustion control oxides of nitrogen?
Less NOx are produced with lower temp techniques
Techniques like fluidised bed combustion where an increase SA for combustion maintains rapid combustion without the need for high temperatures
How can catalytic converters control oxides of nitrogen?
A chamber in exhaust pipes with a catalyst like platinum which can reduce NOx to nitrogen and oxygen gases
How do Urea sprays control oxides of nitrogen?
They remove it
Urea + nitrogen monoxide + oxygen -> nitrogen + carbon dioxide + water
Ozone occurs naturally but is also an atmospheric pollutant- why?
Stratospheric ozone occurs naturally and reduces the exposure of life on earth to harmful UV light
Tropospheric ozone is a pollutant produced because of human activities and is toxic to living organisms
How can ozone impact plants?
It can reduce the growth rate of trees and agricultural crops
How can ozone affect humans?
Cause breathing difficulties and increase asthma rates
What atmospheric pollution is tropospheric ozone involved in?
The production of secondary pollutants in photochemical smogs
Acid rain
How is tropospheric ozone produced
Nitrogen dioxide is broken down by UV-A sunlight ( a photochemical reaction)
The monatomic oxygen produced reacts with normal (diatomic) oxygen to produce ozone
How can tropospheric ozone be controlled?
It is a secondary pollutant so levels can be controlled by reducing levels of primary pollutants that produce it e.g. nitrogen dioxide
How is carbon monoxide produced?
When carbon-based materials are burned with a shortage of oxygen e.g. incomplete combustion of hydrocarbons especially in petrol/diesel engines
What is the effect of carbon monoxide?
It can bind to Hb and prevent it carrying oxygen from lungs to tissue round the body
If too much Hb is inactivated by CO the brain damage may occur and possibly death
What can low concentrations of CO in the body do?
Increase the health problems caused by chronic heart disease
How can carbon monoxide be controlled?
Exhaust catalytic converters
They oxides CO to CO2
CO2 is still a pollutant but in comparison to other emissions, those from CO are small
