Pollution Flashcards
What are the properties of pollutants?
State of matter, energy form, density, persistence, toxicity, reactivity, adsorption, solubility in lipids/water, bioaccumulation, biomagnification, synergism, mutagenic action, carcinogenic action and teratogenic action
What is pollution?
Energy or matter released into the environment with the potential to cause adverse changes to an ecosystem
How can pollutants be categorised?
Direct v Indirect
Anthropogenic v Natural
Primary v Secondary
What are the major types of pollution?
Air, water, thermal and soil or land
How does state of matter impact a pollutant?
Affects the ability to be dispersed by moving water or air
How does density impact a pollutant?
Affects what happens to the particles of a solid, the more dense they are the closer to the source they will settle out
Gases denser than air will sink if the wind is sufficient to disperse them
Liquids will sink quicker if they are more dense
How are sources of pollution categorised?
Point: from a defined place with a definite affect e.g. oil spills from a tanker
Diffuse: from many sources with combined impacts e.g. car exhausts
How is persistence measured?
The time taken for half a pollutant to break down, this is known as environmental half life (Tl ENV)
What environmental conditions can impact the rate of breakdown of pollutants?
Light, temp, oxygen levels, pH or the presence of bacteria
What are some pollutants with high persistence?
CFCs and organochlorine insecticides (DDT)
What are some pollutants with low persistence?
Sewage and pyrethroid insecticides
What does POP stand for and what are they?
Persistent Organic Pollutants and they do not degrade in the environment
Why are POPs bad?
Have negative health effects, they nearly wiped out the bald eagle, transboundary pollution threatening Antarctica, decline of wildlife, disease and abnormalities in living creatures and reproductive impairment
How many main POPs are there and name a few?
21 main: aldrin, chlordane, dichlorodiphenyl trichloroethane (DDT), PCBs and dioxins
What impacts can lead have as a pollutant?
Persistent heavy metal, neurotoxin, it accumulates in the soft tissues and bones, it can cause blood and brain disorders, it affects all organs but especially the nervous system
What are some of the symptoms of lead poisoning?
Abdominal pain, weakness, impaired cognitive function, brain damage, kidney damage and death
What are some other toxic pollutants?
Carbon monoxide, acids and cyanide
How is cyanide toxic?
Inhibits enzymes involved in aerobic respiration
What are PANs?
PeroxyAcetyl Nitrates are made from nitrous oxides with oxygen in the air and unburnt hydrocarbons when reacted in sunlight
How are PANs toxic?
Irritating to eyes and lungs and they kill plants
How does specificity impact pollutants?
Variations in toxicity to different groups of organisms
How does specificity affect use of pyrethroid insecticides?
High toxicity to insects and low toxicity to mammals so safe for use, however they have high toxicity to fish so shouldn’t be used near lakes or rivers
How does adsorption impact pollution?
Immobilise them so they cannot cause pollution problems, but it’s also possible they may be released later to cause other problems e.g. the disturbance of lake sediments by storms may release phosphates or PCBs
What’s the harm of water soluble pollutants?
Very mobile and can lead to eutrophication
What’s the harm of liposoluble pollutants?
Mor soluble in fats so they can pass through phospholipid membranes and stored as oil or fat in cells, allowing biomaginification
What are some lipid soluble pollutants?
DDT, PCBs and heavy metals e.g. Mercury
What are the negative effects of DDT?
Cancer, poisoning wildlife (especially birds) and poisoning aquatic animals
What are PCBs used for?
Coolants, insulating fluids, plasticisers, pesticides, flame retardants, adhesives, paints etc
What is mobility?
The measure of the degree to which a pollutant can be carried by wind, water or organisms
How does mobility impact a pollutant?
High mobility may mean it impacts larger area however dilution means impact may not be as strong
What is bioaccumulation.
The absorption and storage of pollutants in the tissues of organisms, the amount of substance increases over time
How does biological half life impact bioaccumulation?
Greater half life means greater risk of chronic poisoning
What is biomagnification?
The increase in concentration as a pollutant passes along a food chain, becoming concentrated into a progressively smaller biomass with each successive trophic level
How does biomagnification link to the food chain?
Many of the producers are eaten by the primary consumers and the toxins move from originally dispersed area to one organism
What is synergy?
When the combined effects of different pollutants has a much worse effect, they DO NOT combine to create a new pollutant
What’s an example of ozone in synergy?
Ozone damages leaf surface cuticle so sulphur dioxide can access the newly exposed living cells and accuse more damage
What’s an example of synergy in heavy metals?
Lead and cadmium, the impact of one allows the impact of the other to be even stronger but unclear which starts
What are some of the toxic effects of cadmium?
Carcinogenic, linked to osteoporosis, heart disease and learning difficulties
Where can cadmium poisoning come from?
Pigments, steel plating, batteries, smoking or the environment
What are some mutagens?
Ionising radiation, UV light, asbestos, cadmium, chlorinated organic substances
What are some examples of carcinogens?
Asbestos, DDT, cadmium and cigarette smoke
What are teratogens?
Chemicals or energy that cause non-inherited birth abnormalities
What do teratogens do?
Inhibit the function of proteins and enzymes that the DNA would have normally controlled
What is an example of teratogen?
Herbicide 2,4,5T (Agent Orange)
What are some key facts about dioxins?
POPs, bioaccumulate, 90% of human exposure is through food, highly toxic, reproductive and developmental problems, damage immunity, interfere with hormones, carcinogenic, background exposure won’t affect human health and prevention is done via source directed measures
What environmental factors affect the rate of degradation?
Temp, light, pH, oxygen levels, the presence of other chemicals, temperature inversions and the presence fo absorbent material
What abiotic factors affect the dispersal of pollutants?
Velocity/direction of air and water currents
What’s a problem with fast degradation?
Deoxygenation
When does light impact degradability?
Photochemical smogs, photo-degradation of some pesticides
When does oxygen impact degradation?
Aerobic bacterial decomposition and oxidation of sulphide ores producing sulphur dioxide
What happens when warm pollutants are released at higher colder altitudes?
They are less dense and more buoyant than the cooling surrounding air, this allows them to rise disperse and become diluted, they cool but surrounding air is still cooler so they continues to rise and disperse
How does normal temperatures cause the dispersal of pollutants?
As they are warmer than the surrounding air they continue to rise and are dispersed
How do temperature inversions prevent the dispersal of pollutant gases?
When the layer of air closest to the ground is colder than normal, the pollutants become colder and more dense quicker, they cannot disperse easily and become concentrated
What factors allows a temperature inversion to form?
Low wind velocity, valleys, cloudless skies and mist or fog during the day
Why are low wind velocities needed for temperature inversions?
So the two layers of air do not mix
Why are valleys needed for temperature inversions?
Colder denser air can collect
Why are cloudless skies desired for temperature inversions?
IR energy can be radiated from the ground allowing the ground to cool
Why does mist or fog during the day allows for temperature inversions?
Water vapour that condenses in the cooler ground layer had a high albedo and will reflect sunlight and slow the heating of the ground that would cause the temperature inversion broken down
What happened to the Caesium-137 at Chernobyl?
Washed out of the atmosphere by rain and adsorbed onto the clay particles in the soil so any radiation is absorbed by the ground
What is the purpose of CPA?
Critical Pathway Analysis predicts the movement of potential pollutants in the environment to assess the severity and location of the pollution that may occur
What factors are included when determine the critical analysis pathway?
Properties of pollutant and features of the environment
What is CPA mainly used for?
Monitor the dispersal of radioactive waste discharges
How can the accuracy of CPA be checked?
Environmental sampling
What is CGM?
Critical Group Monitoring is a specific method of assessing the risk of public exposure to pollutants
What does CGM do?
Assesses the risk to members of the public who , because of their lifestyle, are most likely to be at risk. It monitors exposure to assess potential risks before health impacts occur
What factors affecting the dispersal of pollutants can be managed?
Emission location and timing
What are some examples of controlling emission location?
Marine discharges where currents disperse and dilute emissions, emissions downwind of urban areas and not discharging waste onto permeable rock above an aquifer
What are some examples of controlling the timing of emissions?
Tidal cycles- emissions into tidal rivers when tide is coming is will be carried upstream and when tide is going out will allow dispersal
Temperature inversions- restricting time and area of activity if inversions may happen
What is the precautionary principle?
This assumes a waste will cause pollution if released until research confirms it doesn’t, this is safer than releasing a waste that hasn’t been analysed
What is an example of production prevention?
Desulfurisation of fossil fuels before combustion
What is an example of prevention of release?
Electrostatic precipitators for smoke control, catalytic converters for control of NOx, CO and hydrocarbons in vehicle exhaust emissions
What is an example of post release remediation?
Oil spill clean ups and phytoremediation of land contaminated with heavy metals
What are some examples of alternative processes?
Electric vehicles, pyrethroid pesticides instead of DDT and use of renewables
What is the ALARA approach to emission control?
As low as reasonable achievable, meaning paying a efficient amount to clean up as cleaning all is rarely possible anyway
What is BATNEEC?
Best available technology, not entailing excessive costs
What is smoke made up of?
Atmospheric particulates produced by the incomplete combustion of carbon-based materials
How is smoke categorised?
Size range on the particles e.g. PM10 is less than 10 microns in diameter and PM5, PM1 are commonly used
What are some sources of smoke?
Combustion of coal, diesel, general combustible wastes especially in urban areas and combustion of crop waste, wood fuel, grasslands, forests in rural areas
What are the effects of smoke on humans?
Respiratory disease, e.g. bronchitis, asthma, lung cancer. Chemicals on or in smoke can kill the cilia in the bronchioles which makes it more difficult to clear inhaled particles and bacteria from the lung, this can increase the risk of infection
What are the effects of smoke on other living organisms?
Reduced photosynthesis as smoke blocks light, some substances in the smoke may also be toxic e.g. acids and heavy metals
What are the effects of smoke on non-living objects?
Smoke particles can damage buildings due to the acids and organic solvents they may contain, cleaning dirty buildings is expensive
What are the effects of smoke on the climate?
Large releases of smoke can reduce temperatures because the high albedo of the smoke reflects the light so it does not reach the ground, where it may be absorbed and converted to heat, crops may die, livestock may die and many natural ecosystems would be disrupted
Why do smoke particles remain in the stratosphere longer than the troposphere?
No rain to wash them away
How can smoke damage the stratosphere?
Disruption of ozone
What makes fog more likely?
Temperature inversion
What are the dangers of smoke in fog?
More easily inhaled
How is smoke controlled by legislation?
Clean Air Act (1956), which restricted the use of fuels that do not produce smoke, for example, natural gas, electricity
How are domestic sources of smoke controlled?
Increased use of fuels that do not produce smoke, for example natural gas, electricity
How are diesel transports controlled for smoke?
Diesel Particulate Filters (DPF) fitted in the exhaust pipes of engines that trap up to 80% of smoke particles
What are electrostatic precipitators?
Effluent gases are passed through a chamber with many electrically charges wired or plates, smoke particles within the gases are attracted to the charged wires and plates and collect together, as the particulates accumulate they fall to the floor as ‘fly ash’, this is often used in coal-fired power stations
What are cyclone separators?
Based on the same principle as vacuum cleaners, the effluent gases are forced to rotate in a cylindrical chamber, which throws the suspended particles to then outside surfaces of the chamber where they fall and collect, this cleans the gases which are then discharged via a pipe from the centre of the cylinder
What is a scrubber?
Fine water spray to wash out suspended solid particulate matter and dissolve soluble gaseous pollutants
What is coal treatment?
Heating coal allows the tar that causes smoke production to be drained off
What are bag filters?
Remove smoke particles from effluent gases by trapping them on fabric filter
How are Diesel engines developed to be more efficient and create less smoke?
Turbo chargers enable more air to be delivered to the combustion chamber, to reduce smoke formation and increase efficiency as more of the organic matter is completely burnt when accelerating
When do photochemical smogs occur?
Urban pollution during temperature inversions
How do NOx form in exhaust gases of vehicles?
N2 and O2 form the air react under the high temperature and pressure in the engine, it’s unrelated to the fuel
What are the dangers of PANs?
They are more stable than ozone and act as global formation of global tropospheric ozone as they carry nitrous oxides
What are the effects of nitrous oxides?
Increases the risk of respiratory infections, such as colds, flu and bronchitis, they can also making existing conditions worse
What are the effects of PANs?
Eye irritation, breathing difficulty, emphysema and increased risk of heart disease
What can make cities prone to photochemical smogs?
Topography, heavy vehicle use and climate
Athens, LA, Paris, Beijing and Mexico City
What are control methods for photochemical smogs?
NOx and HCs can be controlled with catalysts such as platinum and palladium
NOx reforms N2 and O2
How are hydrocarbons controlled?
Catalytic converters create carbon dioxide and water by oxidation, unburnt hydrocarbons can be managed by collecting and condensing fumes back into fuel at petrol stations, vapours can also be collected and passed through an activated carbon filter where the hydrocarbons adsorb onto the carbon particles
What is the natural pH of rain?
5.6
What happens when sulphurous and nitrous oxides react with oxygen and water in the atmosphere?
They form secondary pollutants as acids
What other gases can form acid rain?
Hydrogen chlorides and sulphur trioxide (reaction with ozone)
What are the impacts of acid rain on non-living things?
Acid corrodes metal , causing damage to railway lines, metal railings, water pipes, pylons and overhead power lines. Limestone structures such as building and statues are damaged as the acids dissolve the surface layers and weaken the stone structure of porous limestone
What are the direct impacts of acid rain on living things?
Denature proteins in cell membranes and can inhibit enzyme action, exposed living cells likely damaged and invertebrates with exoskeletons may die, the acid dissolves calcium compounds that form the skeleton and lichens are very sensitive
What are biotic indicators?
Species which have a narrow range of tolerance e.g. lichens
What is a lichen?
Composite organisms consisting of a fungus (the mycobiont) and a photosynthetic partner (photobiont) growing together in a symbiotic relationship
Which lichens are most tolerant of polluted air?
Crusty lichens
What are the indirect impacts of acid rain on living things?
Low pH makes metal ions more soluble, which may lead to leaching and important plant nutrient (calcium and magnesium ions) are normally lost first, ions such as aluminium and lead become mobile and are no longer adsorbed onto clay, these may inhibit enzyme action, leaching can lead to death of aquatic organisms and consumption by humans (water or animals)
How does fog affect the severity of acid rain?
Can cause acid rain to be in contact with vegetation longer as no water potential gradient leading to more harmful effects
How does soil lime content affect the severity of acid rain?
Neutralises acid pH and minimises effect
How does snow impact the severity of acid rain?
PH of meltwater will be much lower, harming soil and aquatic life in fresh waterways
Why is hydrogen sulphide removed from natural gas?
To prevent corrosion damage to refinery and pipeline equipment and to the appliances in which the gas is used, this also prevent the production of sulphur dioxide when it is burnt
How is hydrogen sulphide removed form natural gas?
Dissolving it in amine solution or reacting it with iron particles
What processes can be used to remove sulphur form power station emissions?
Dry flue gas desulphurisation and wet flue-gas desulphurisation
What happens in dry flue-gas desulphurisation?
Flue gases are passed through a bed of crushed calcium carbonate, the sulphur dioxide reacts with the lime to produce calcium sulphur, if the effluent gases have been cleaned to remove smoke particles, then calcium sulphate may be pure enough to make gypsum building plaster
What happens in wet flue-gas desulphurisation?
Sodium sulphite scrubbing where the flue gases are bubbled through a sodium sulphite solution, the sodium hydrogen sulphite is then heated and breaks down to sodium sulphite and water, which are rescued, and concentrated sulphur dioxide, which is valuable industrial raw material can be converted to solid sulphur or sulphuric acid
What are the control methods for oxides of nitrogen?
Low temperature combustion, lean-burn engines, catalytic converters and urea sprays
Tropospheric ozone- effects, production and control
Toxic to plants, breathing difficulties and increased asthma, produces secondary pollutants (photochemical smog and acid rain)
NO2 broken down by UVA, releasing O radical to react with O2
Reducing NO2 release
Carbon monoxide- effects and control
Binds to haemoglobin causing brain damage and death
Exhaust catalytic converters oxides to carbon dioxide
How does effluent quantity impact water pollution?
The amount of pollutant released affects concentration, if the concentration of pollutant in the water is low many pollutants are not harmful
How does volume of water impact water pollution?
The anger the body of water the more the waste will be diluted
How does the residence time of the water impact water pollution?
The shorter the residence time of the water the more likely that the pollutant will be carried away by flowing water and not accumulate
What factors affect the rate of degradation in water?
Light levels, temperatures, environmental conditions making new substances by oxidation or reduction
How can reduction of pollutants be harmful?
Inorganic mercury wastes can be reduced to methyl mercury which is much more hazardous
How do sediments within the water impact water pollution?
Pollutants may absorb onto the sediments which effectively removes them from the water
What factors can be considered when locating suitable sites for effluent discharge?
Dispersal by currents, however if pollutants don’t degrade large water bodies can make problems harder to solve later
How can warm effluent water impact ecology?
Lower the possible dissolved oxygen level, denatures proteins in aquatic organisms
How can warm effluent water cause physiological changes?
Increased metabolic rate of many organisms, so more energy is used leaving less surplus energy for growth, increased rate of development of eggs so they hatch sooner, non-indigenous species may thrive and outcompete indigenous, toxins can be metabolised more rapidly, resistance to disease may be reduced
What are some of the control methods used for thermal pollution?
Cooling towers are used to cool power station effluent water so that it does not cause deoxygenation, water used to condense steam in a power station is taken from a nearby water source, after absorbing heat the water is returned to the natural source at higher temperatures
How do cooling towers work?
Spray hot water from shower floor, the air absorbs the heat from the water and rises up the tower, escaping into the open atmosphere, this causes an up-draught, which draws more air through the shower spray.
How much higher is the temperature of the water returned?
5 to 8 degrees Celsius
Where are cooling ponds used?
In places with sufficient land
What is the water in a cooling pond used for?
Reused by the plant
What are the causes of oil pollution?
Waste lubricating oil, accidental releases and oil exploitation
What are some accidental releases?
Shipping accidents, oil rig accidents, oil pipeline leaks, storage tank leakage and discharge of waste water from washing tanks on ship tankers
What are the effects of oil pollution?
Reduced dissolution of O2, smothers and asphyxiates molluscs, some components are toxic, waterproofing and thermal insulation of bird feathers lost leads to hypothermia, ingested oil prevents digestion and reduced breeding success as birds are unable to locate mated by sense of smell
What are drill pipes lubricated with?
Fine clay suspended in water (mud)
What are the effects of oil pollution?
Planktonic organisms killed by toxicity Algae cannot access sunlight or carbon dioxide for photosynthesis
Bird feathers stick so they drown
Less O2 can dissolve from atmosphere
How can waste lubrication oil be reused?
Contaminants can be removed and chemical reforming and distillation can produce commercially valuable lubricant again
How can oil pollution be controlled by improving tanker operation?
Better shipping routes, better navigation systems, inert gas systems, tank washing procedures and oily waster water disposal
What is the AIS and what does it do?
Automatic Identification System allows the position of other ships to be monitored to avoid collisions
Why are inert gas systems used?
Using air to fill the tankers can cause an explosive mix of air and oil vapours
Why must oil tanks be washed?
To prevent the build up of tar sludges
How were tanks previously washed?
Washed with sea water which was then discharged back into the sea
How is oily waste water disposed of?
Unloaded at an oil terminal when the tanker docks
How can tanker design be improved to control oil pollution?
Double hull, double rudder, double engine, double fuel tanks, separate oil and ballast tanks, oil interceptors and bund walls
What is the hull and how does doubling it help?
The layer of steel between the oil and sea, doubling it means any damage to the outer hull doesn’t release any oil as there is typically a 2m gap
How can doubling engine/rudder/fuel tanks prevent pollution?
Any mechanical failure on a tanker that affects propulsion/steering can be serious as the ship could be carried by wind or currents onto a rocky coastline
How do separate oil and ballast tanks help prevent oil pollution?
Ballast water pumped back into the sea can carry oil residue with it
What do oil interceptors do?
Separate oil from watery waste, the water flows to the main drainage system or river but the oil is retained and can be removed for later treatment
What do bund walls do?
Contains the oil if the tank were to split, the volume enclosed by the bund wall is greater than the tank so it cannot overflow
What happens to the oil in spill?
Light fractions can evaporate, medium fractions will be digested by bacteria, but heavier fractions will remain as tar balls for many years
When is oil pollution most serious?
When it occurs inshore, or in an enclosed body of water, where dispersal is prevented, where there are more sensitive ecosystems, where there are more concentrated human activities to be effected
What are booms and how are they used?
Inflatable tubes that restrict movement of floating oil, a skirt below the boom can retain oil if there is a water current
Where are booms mainly used?
Sheltered areas where they can reduce the dispersal of oil as open currents are too strong