Pollution (AS) (Complete) Flashcards
What is pollution and what is it usually caused by?
-Release of substances/forms of energy into environment that cause harm, especially to living organisms
-Usually caused by human activities, but natural processes can have same effects; eg oil leaks from natural oilfields, smoke from forest fires, volcano eruptions releasing acidic gases & dust
What do the properties of pollutants determine?
-Length of time it may cause a problem
-Level of harm it can cause
-Where, how for it may travel
Properties of pollutants; how does the state of matter affect a pollutant?
-Whether a polluting material= solid, liquid or gas affects its ability to be dispersed by moving water/air
-In general, solids are deposited close to source while gases are transported easily in atmosphere
Properties of pollutants; how does energy form affect a pollutant?
The different pollutants that are energy forms like noise, heat, ionising radiation or light have widely varying impacts due to way energy behaves
Properties of pollutants; how does density affect a pollutant?
-Density of material will affect its dispersal
-Denser materials need more kinetic energy to keep them suspended, so are more likely to be deposited closer to source, eg lead dust has ↑ density
-Same gases= denser than air, settle close to ground if there’s insufficient wind to disperse them, eg hydrogen cyanide released at Bhopal, India 1984 remained very close to source
Properties of pollutants; what is persistence, how is it measured + why is this not precise?
-Measure of length of time pollutant remains in environment before breaking down chemically (degrading)
-Can be measured as time it takes for 1/2 of pollutant to break down= environmental half-life. It’s not a precise measure as rate of breakdown can be affected by environmental conditions Ike light, temp, O2 levels, pH, presence of bacteria
Properties of pollutants; what are examples of pollutants with high & low persistences?
-High= CFCs, organochlorine insecticides like DDT
-Low= sewage, pyrethroid insecticides
Properties of pollutants; what is the process of pollutant breakdown and how is it categorised?
-Degradation
-Categorised according to feature causing breakdown;
-Biodegradation: caused by living organisms, usually bacteria
-Photodegradation: caused by light
-Thermal degradation: caused by heat
Properties of pollutants; what is toxicity and how is harm usually caused?
-Measure of how poisonous a substance to living organisms
-Harm usually caused by damage to proteins, especially inhibition of enzyme action
Properties of pollutants; what are examples of toxic pollutants and their actions?
-Carbon monoxide; prevents blood from carrying oxygen by binding to haemoglobin in red blood cells
-Lead; inhibits enzyme action in nerve cells
-Acids; inhibit protein action by changing molecular shape, eg active site of enzyme
-Cyanide; inhibits enzymes involved in aerobic respiration
Properties of pollutants; why is specificity used for and how does it affect pollutants? + eg
-Used to describe variations in toxicity to different groups of organisms
-Specific toxins= more toxic to some groups than others
-Non-specific pollutants= similar toxicities to all groups
-Pyrethroid insecticides have ↑ toxicity to insects &↓ toxicity to mammals so is relatively safe for humans to use in pest control in areas of livestock, but have ↑toxicity in fish so shouldn’t be used near rivers or fish farms
Properties of pollutants; how does reactivity affect pollutants?
-Can affect severity of pollution caused, either↑or ↓ problems caused
-Reactive pollutant may degrade rapidly like sewage, or may react w/ other substances to produce secondary pollutants, eg action of ozone in acid rain & photochemical smog
Properties of pollutants; what are primary and secondary pollutants?
Primary - released by human activities
Secondary - produced by chemical reactions between one or more primary pollutants, often w/ non-pollutants
Properties of pollutants; what is adsorption and how does this affect the pollutant?
-Some pollutants can become attached to surface of materials, eg soil particles/aquatic sediments
-This can immobilize them so can’t cause pollution problems but it’s also possible they may be released later to cause problems after period of time when their presence isn’t obvious, eg disturbance of lake sediments by storms releasing phosphates/PCBs
Properties of pollutants; how does solubility in lipids/water affect pollutants?
-Substances w/ ↑ solubility in water= easily dispersed in water bodies, eg nitrates. Can ↓ pollutant conc but may allow pollutant to affect larger area
-Lipids= organic compounds, fatty acids/derivatives and are insoluble in water. Substances dissolving in lipids may be able to pass through phospholipid cell membranes & be stored in oil/fat deposits within cells, eg mercury/DDT
Properties of pollutants; what is bioaccumulation and what does this involve?
-Process by which # of substance within organism ↑
-Often involves long-term ingestion of small doses of liposoluble pollutant
-OG doses may’ve been too small to be toxic, but may eventually build up to reach toxic levels
-Liposoluble pollutants= more likely to bio-accumulate as may be stored in lipids
-Water-soluble pollutants tend to be excreted from body more easily
Properties of pollutants; what is biomagnification and what does it involve?
-Substances bioaccumulating may become more conc as they pass along food chains, becoming concentrated into progressively ↓ biomass w/ each successive tropic level
-Organisms in later trophic levels often have longer lifespans & build up even ↑ conc, esp if they’re endotherms (warm-blooded) that have ↑ food intake bc of their ↑ metabolic rates so are likely to ingest more of pollutant
Properties of pollutants; what is synergism and what does it involve?
-Involves 2+ pollutants where their effects interact to create diff effect, usually more serious one
-Pollutants themselves don’t interact to produce new pollutant (would be secondary pollutant), it’s their effects that interact, eg ozone damages leaf cuticles & enables sulfur dioxide to cause more damage to newly exposed living cells
Properties of pollutants; what is mutagenic action?
Mutagens= agents causing changes in chemical structure of DNA by damaging chromosomes by rearrangement of DNA structure. Changes are known as mutations
Properties of pollutants; mutagenic action- what are gonadic and somatic effects?
-Gonadic effects (cells in ovaries/testes); mutation in egg/sperm cell/embryo may cause birth abnormality in offspring produced
-Somatic effects (general body cells); mutation in body cell may make it behave abnormally as damaged DNA can’t control normal cell function. Death of individual cells—> rarely issue as can be replaced by division of other healthy cells. Serious consequences of these are if not killed= cancer
Properties of pollutants; mutagenic action- what are examples of mutagenic pollutants?
-Ionizing radiation
-UV light
-Chlorinated organic substances, eg PCBs, dioxins
-Cadmium
-Asbestos
Properties of pollutants; mutagenic action- what is carcinogenic and teratogenic action?
-Carcinogens; mutations causing cancer. Cell multiplication due to a carcinogen produces mass of tissue (tumour). This may eventually cause health issues by preventing normal tissue function
-Teratogens; cause birth abnormalities by preventing normal gene expression. They don’t change DNA structure but inhibit function of proteins & enzymes that DNA would’ve normally controlled. The abnormality can’t be inherited by future generations bc DNA structure isn’t affected. Examples= mercury, herbicide 2,4,5-T
Properties of pollutants; what is mobility and how does it affect a pollutant?
-Ability of pollutant to move in environment depends upon other properties, esp state of matter, density & solubility in water
-More mobile pollutants= likely to travel greater distances & affect larger areas, although dilution may ↓ severity of effect
Properties of pollutants; what are examples of pollutants with different degrees of mobility?
-Lead dust; ↑ density of atmospheric lead dust causes most particles to be deposited close to source
-Smoke particles; easily washed out of atmosphere by rain/settle if air is relatively static. Smaller particles settle more slowly
-Sulfur dioxide gas; is soluble in water & easily removed from atmosphere by rain, usually within 250km of source
-CFCs; chemically stable & ↓ solubility in water, so remain in atmosphere for long time & disperse throughout whole atmosphere
Features affecting degradation of pollutants; how does temperature affect this?
-Most chemical reactions occur more rapidly if temp is ↑
-Degradable pollutants like sewage will break down more rapidly at higher temps, but more rapid degradation can ↑ problems eg deoxygenation
Features affecting degradation of pollutants; how do light Ievels affect this?
Light can provide activation energy driving chemical reactions involving pollutants like photochemical smogs & photodegradation of some pesticides
Features affecting degradation of pollutants; how does oxygen affect this?
Oxygen is involved in many chemical & biological reactions involving pollution like;
-Aerobic bacterial decomposition of sewage
-Oxidation of sulfide ores producing sulfur dioxide
Oxidation state affects solubility of many metals
Features affecting degradation of pollutants; how does pH affect this?
-Can affect solubility of substances
-Many heavy metals like lead are more soluble and so mobile under more acidic conditions
Features affecting degradation of pollutants; how do pollutant interactions affect this?
Behavier of a pollutant may be affected by presence of other pollutants like;
-Interaction of NOx & hydrocarbons in photochemical smogs
-Combined effects of phosphates & nitrates in eutrophication
Factors affecting dispersal of pollutants; how do wind & water currents affect this?
Velocity & direction of air + water currents will affect how for pollutant is dispersed, also how much it’s diluted
Factors affecting dispersal of pollutants; how do temperature inversions affect this?
-Atmospheric temps in troposphere normally ↓w/ ↑ altitude
-Temp of warm pollutant gases, released at ground level, makes them less dense & more buoyant than cooler surrounding air
-This allows them to rise, dispense & become diluted. They cool down as they rise but as surrounding air is also cooler, they remain buoyant & continue to rise & disperse
Factors affecting dispersal of pollutants; what are the factors allowing temperature inversions to form?
-Valleys; where colder denser air can collect
-Low wind velocity; so air layers w/ diff temps don’t mix
-Cloudless skies; so infrared energy can be radiated from ground, allowing ground to cool down
-Mist/fog during day; water vapour that condenses in cooler ground layer has ↑ albedo & will reflect sunlight + slow heating of ground that would cause temp inversion to ke broken down
Factors affecting dispersal of pollutants; how does the presence of adsorbent materials affect this?
-Pollutants may adsorb onto materials like clay particles/organic materials in aquatic sediments
-Adsorption may immobilise pollutant & stop it causing problems
-Radioactive caesium-137 released → atmosphere by nuclear accident, at Chernobyl in 1986, was washed out of atmosphere by rain
-Much of the caesium washed into soil had adsorbed onto clay particles, so is immobile & any radiation released is absorbed in ground
-Many naturally occurring toxic metal ions are immobilised by being adsorbed onto soil clay particles, eg aluminium & lead
General strategies to control pollution; what is the purpose of the Critical Pathway Analysis (CPA)?
-Predict movement of potential pollutants in environment to assess severity & location of pollution that may occur
-If potential pollutant would be diluted & dispersed/carried to locations where impacts would be acceptable—> no further action may be needed
-If potential pollutant would become concentrated/would be carried to important or sensitive areas → may be necessary to control these releases
-Could be used to monitor movements of any mobile, persistent pollutant but is mainly used to monitor dispersal of radioactive waste discharges; means env monitoring can focus on focus on sites more at risk of pollution, w/ no need to sample areas never likely to be polluted
General strategies to control pollution; what are the factors that may be included in Critical Pathway Analysis (CPA)?
-Properties of the pollutant; state of matter, density, solubility in water/lipids, chemical stability
-Features of the environment; wind & water currents, geology, pH, O2 availability, temperature
General strategies to control pollution; what is Critical Group Monitoring (CGM) and what does it assess?
-Specific method of assessing risk of public exposure to pollutants
-Assesses risk to members of public who, due to their lifestyle, are most likely at risk. Group of people= the Critical Group
-If their risk is acceptably low, then it’s assumed all other members of public have even lower risk
-Isn’t normally used to detect damage to health due to pollution. It’s used to monitor exposure & assess potential risks before health impacts occur
-If unacceptable risk is identified, emissions can be controlled to ↓future exposure
Emission control strategies; what environmental factors affect the dispersal of pollutants?
-Air quality
-Meteorological conditions
-Hydrology
-Emission source
Emission control strategies; why and how can emission location be controlled?
Severity of pollution → affected by location where discharges are released
Although emission location is normally determined by location of source, there may be some choices affecting severity of pollution caused, like;
-Marine discharges where water currents will dilute & disperse emissions
-Emissions downwind of urban areas
-Not discharging waste onto permeable rock above aquifer
Emission control strategies; why and how can emission timing be controlled?
Changes in timing of emissions can affect severity of pollution;
-Tidal cycle; emissions into tidal rivers when tide is coming in’ll be carried upstream. Emissions when tide is going out will be carried out to sea where they’ll disperse
-Temp inversions; atmospheric emissions during temp inversion= less likely to disperse. Polluting activities may be restricted in some cities during temp inversions like use of diesel vehicles/industrial combustion
Principles of pollution control; what is the polluter pays principle?
-If organisation/person causing pollution is responsible for any issues caused then there’s an obligation to prevent it
-If costs of preventing damage due to pollution → less than costs of damage, there’s a clear financial incentive to prevent it
-This approach works best if there’s little chance of polluter escaping responsibilities
-Incentive to comply → greater if financial penalties are ↑
Principles of pollution control; what is the precautionary principle and why is it advantageous?
-Assumes waste will cause pollution if released, until research confirms it’s unlikely to do so when release may be permitted
-This is safer than releasing waste that hasn’t been analysed in hope it’s safe, then waiting to see if problems occur
-Principle means being unaware of a problem that isn’t yet understood isn’t an excuse & doesn’t ↓ responsibility
Principles of pollution control; what are examples of pollution control methods?
-Production prevention; desulfurisation of fossil fuels before combustion
-Prevention of release; electrostatic precipitators for smoke control & catalytic converters for control of NOx, CO, hydrocarbons in vehicle exhaust emissions
-Post-release remediation; oil spill clean-up methods & phytoremediation of land contaminated w/ heavy metals
-Alternative processes; use of electric vehicles instead of diesel/petrol ones, use of pyrethroid pesticides instead of more polluting organochlorines, eg DDT & use of renewable energy resources instead of fossil fuels
Principles of pollution control; how is efficiency of pollution control maintained?
-Pollution control can be expensive; relationship betw cost & efficiency isn’t linear
-It’s rarely practical to reduce pollutant emissions to 0; impact of low level emissions may be acceptable so paying for higher may be seen as unnecessary
-In general emissions should follow the ‘ALARA’ approach; should be As Low As Reasonably Achievable
-Can be done by selecting new equipment that’s ‘BATNEEC’; the Best Available Technology, Not Entailing Excessive Cost
-To achieve best env conditions, changes are often needed to emission controls; as cities grow, there’s more pollution sources so original methods may not be sufficient
Atmospheric pollution; how do atmospheric pollutants often behave differently to those from water/ground?
-Rapid movement due to winds leads to dispersal over large area
-Interaction w/ electromagnetic radiation like UV/visible light from sun can cause chemical reactions to occur—> production of secondary pollutants
Smoke and smoke smogs; what is smoke made up of and how is it categorised?
-Made up of atmospheric particulates produced by incomplete combustion of carbon-based materials
-Often categorised by size range of particles;
-PM10: particulate matter >10microns diameter, PM5: >5microns diameter, PM1: >1micron diameter
Smoke and smoke smogs; what toxic chemicals can be found in smoke?
Fluorides, aluminium, lead, acids & organic compounds like phenol
Smoke and smoke smogs; what can smoke act synergistically with?
Other atmospheric pollutants like sulfur dioxide
Smoke and smoke smogs; what are the main sources of smoke and why is this significant?
-Combustion of coal, diesel, general combustible wastes, esp in urban areas
-Combustion of crop waste, wood fuel, grasslands, forests in rural areas
-Significant as exact composition of smoke depend upon its source
Smoke and smoke smogs; what are the effects of smoke pollution on humans?
-Respiratory disease, like bronchitis, asthma, lung cancer
-Chemicals on/in smoke particles can kill cilia in bronchioles → makes it more difficult to clear inhaled particles & bacteria from lungs. Can ↑ risk of infection
-Some of the chemicals may be carcinogenic
Smoke and smoke smogs; what are the effects of smoke pollution on other living organisms?
-↓ photosynthesis as smoke blocks
-Substances in smoke particles may be toxic, eg heavy metals & acids
Smoke and smoke smogs; what are the effects of smoke pollution on non-living objects?
-Smoke particles can damage buildings due to acids & organic solvents they may contain
-Cleaning dirty buildings → expensive
Smoke and smoke smogs; what are the effects of smoke pollution on the climate?
-Large releases of smoke can ↓ temps as high albedo of some smoke reflects light so doesn’t reach ground where it may’ve been absorbed & converted to heat
-Was thought that impact of large-scale nuclear war= so much smoke reaching stratosphere that Earth would cool significantly for several years; called ‘Nuclear Winter’. This could make survival on Earth much more difficult as crops would fail, livestock would die & many natural ecosystems would be disrupted
Smoke and smoke smogs; what are the effects of smoke pollution on the stratosphere/atmosphere?
-Smoke particles = small & can remain suspended in atmosphere for long periods, esp in stratosphere where there’s no rain to wash it out
-Smoke in stratosphere can deplete ozone layer
Smoke and smoke smogs; how is smog formed and what are its features?
-When smoke & fog are present together a smog may occur; smoke + fog = smog
-Fog tends to form when moist air is cooled until reaching its dew point. -Water vapour condenses as airborne droplets of water. Temp inversions make formation of fog more likely
-Smoke that’s part of a fog= more easily inhaled
-Smog → v high albedo so temp inversion can last for long periods of time, allowing pollutant levels to ↑ to high level
Smoke and smoke smogs; how was the London smog of 1952 caused and what were its impacts?
-Position of London in a valley has caused atmospheric pollution issues since 1200s, became worse as city grew
-December 1952; 5 day period where anticyclonic weather conditions produced clear skies, ↓ wind velocities so temp inversion formed & atmospheric pollutant levels ↑
-About 12,000 deaths were caused by the smog, mainly old & young people as well as those w/ existing respiratory health issues
Smoke and smoke smogs; what legislation was put in place as a smoke pollution control measure?
Clean air act (1956) restricted use of fuels producing smoke in large urban areas of UK
Smoke and smoke smogs; how can domestic sources be smoke pollution control measures?
↑ use of fuels not producing smoke, eg natural gas & electricity
Smoke and smoke smogs; how can transport sources be smoke pollution control measures?
Diesel Particulate Filters (DPF) fitted in exhaust pipes of diesel engines trap up to 80% of smoke particles
Smoke and smoke smogs; industrial sources- how can electrostatic precipitators be control measures for smoke pollution?
-Effluent gases passed through chamber w/ many electrically charged wires/plates
-Smoke particles within gases are attracted to charged wires & plates, collect together
-As particles accumulate, fall to floor as ‘fly ash’
-This pollution control method is often used in coal-fired power stations
Smoke and smoke smogs; industrial sources- how can cyclone separators be used as smoke pollution control measures?
-Process based on same principles as many vacuum cleaners
-Like air & waste drawn into vacuum cleaner, effluent gases are forced to rotate in cylindrical chamber → throws suspended particles to outside surfaces of chamber where they fall & collect
-This cleans gases, which are discharged via pipe from centre of cylinder
Smoke and smoke smogs; industrial sources- how can scrubbers be used as smoke pollution control measures?
Uses fine water spray to wash out suspended solid particulate matter & dissolve soluble gaseous pollutants
Smoke and smoke smogs; industrial sources- how can coal treatment be used as smoke pollution control methods?
Heating coal allows tar causing smoke production to be drained off → produces smokeless coal
Smoke and smoke smogs; industrial sources- how can bag filters be used as smoke pollution control measures?
Remove smoke particles from effluent gases by trapping them on fabric titter
Smoke and smoke smogs; what are examples of more efficient combustion technologies and how are they smoke pollution control measures?
-A lot of smoke particles → made of organic matter not completely burnt. If more oxygen is supplied & efficiently mixed, smoke particles can be completely burnt to gases
-Diesel engines produce most smoke when driver accelerates too quickly → too much fuel enters engine for # of oxygen available to burn. Turbo chargers enable more air & so oxygen to be delivered to combustion chamber, ↑efficiency of combustion
Photochemical smog; why is the word ‘smog’ here misleading but also not?
They don’t involve smoke/fog but do involve urban pollution during temp inversions, often in valleys so there’s some similarities w/ ‘true’ smoke smogs
Photochemical smog; what are the pollutants involved in photochemical smog?
Wide variety of reactions betw primary & secondary pollutants, in presence of sunlight, including UV light
Photochemical smogs; what are the sources of primary pollutants in photochemical smog?
-In urban areas, most oxides of nitrogen (NOx) → released in exhaust gases from petrol & diesel engines
-NOx aren’t produced by fuel combustion itself but by oxygen & nitrogen from air drawn into engine, then reacting w/ each other under ↑ temp & pressure conditions in engine
-Nitrogen dioxide= toxic at ↑ conc but normally only reached in more polluted cities
-In presence of sunlight & other pollutants like hydrocarbon vapours much more secondary pollutants can be made like Peroxy Acetyl Nitrates (PANs)
Photochemical pollutant effects; what are the effects of NOx?
↑ risk of respiratory infections like colds, flu, bronchitis. Can also make existing health issues worse like asthma and heart disease
Photochemical pollutant effects; what are the effects of PANs (peroxyacyl nitrates)?
-Are toxic at conc much ↓ than those at which NOx become toxic
-Can cause eye irritation, breathing difficulties, asthma, emphysema & ↑risk of heart attacks
Photochemical pollutant effects; what are the effects of tropospheric ozone?
-Contributes to production of PANs but is also toxic itself; cause asthma, bronchitis & heart disease
Photochemical smog; what cities are more prone to photochemical smogs and why?
-LA, Mexico City, Paris, Beijing, Athens
-Due to topography
-Where traffic congestion is more severe, climate is sunny & temp inversions common
Control of photochemical smogs; how can both NOx and hydrocarbons be controlled?
Using catalysts like platinum & palladium in exhaust pipe catalytic converters
Control of photochemical smogs; how are catalytic converters used?
-NOx are chemically reduced in catalytic converters to re-form oxygen & nitrogen gas originally reacting w/ each other
-Are used in exhaust systems of vehicles w/ petrol engines & many w/ diesel engines
Control of photochemical smogs; how can unborn hydrocarbons be controlled?
Catalytic converters oxidise hydrocarbons to CO2 & H2O
-Vapours at filling stations can be collected, condensed & returned to main fuel tank
-Vapours can be collected & passed through activated carbon filter where hydrocarbons absorb onto carbon particles
Control of photochemical smogs; why does the control of primary pollutants also guarantee this for secondary pollutants?
The reactants won’t be present for them to be formed
What is acid rain and how is it formed?
-All rain → slightly acidic (pH 5.6) due to naturally occurring CO2 in atmosphere dissolves to make carbonic acid (weak acid)
-‘Acid rain’= general name to any precipitation more acidic than 5.6
-It’s the combo of pollution issues due to range of acidic gases & other pollutants contributing to the problem
Acid rain; what are the pollutant gases involved in acid rain?
-Sulfur dioxide dissolves in water—> sulforous acid
-Sulfur dioxide may be oxidised in atmosphere by gases like ozone—> Sulfur trioxide, is dissolved to make sulfuric acid (much more powerful than sulforous acid)
-NOx dissolve—> nitrous & nitric acid
-Hydrogen chloride dissolves—> hydrochloric acids
-Ozone involved in oxidation of Sulfur dioxide to Sulfur trioxide
Acid rain; what are the sources of the pollutant gases involved in acid rain?
-Sulfur dioxide; combustion/oxidation of materials containing Sulfur, esp burning coal & smelting sulfide ores
-NOx; high temp combustion, esp in power stations & petrol + diesel internal combustion engines
-Ozone; secondary pollutant made by photochemical reactions, involve NOx
-Hydrogen chloride; Combustion of coal & incineration of wastes containing chlorine,eg PVC plastic waste
-Sulfur trioxide; oxidation of sulfur dioxide by ozone
Acid rain; what are the effects of acid rain on non-living things?
-Acid deposition corrodes metals, causing damage to railway line, metal railings, water pipes, pylons & overhead powerlines
-Limestone structures like buildings & statues are damaged as acids dissolve surface layers & weaken stone structure of porous limestone
Acid rain; what are the direct effects of acid rain on living organisms?
-Acids= harmful to all living organisms, but range of tolerance differs betw species
-Low pHs denture proteins in cell membranes & can inhibit enzyme action
-Tissues w/ living cells exposed to environment= most likely to be damaged by acid rain, eg cells inside leaf stomata, plant root hairs, germinating seeds, fish eggs & gills
-Invertebrates w/ exoskeletons may die as acids dissolve calcium compounds forming skeleton
-Lichens= v sensitive to acidic conditions
-Sulfur dioxide can cause breathing difficulties & increase freq of respiratory issues like asthma attacks
Acid rain; what are the indirect effects of acid rain on living organisms?
-Solubility of many metal ions—> affected by pH, often becoming more soluble at low pH
-Acidic solutions produced by acid rain that percolate through soil can leach metal ions from soil; important plant nutrients like calcium & magnesium usually lost first
-Once these have gone, other are mobilised—> normally adsorbed onto surface of clay particles & so would be immobile, not take part in normal soil chemistry. Include toxic ions like aluminium & lead
-These toxic ions inhibit enzyme action in plant root hair cells & other soil organisms like detritivores & decomposers. Mobilised toxic ions may leach into rivers & lakes and harm aquatic organisms
-Metal ions leached out of soil may affect human health; lead= neurotoxin. There’s some evidence aluminium ions may be factor associated with/ neurological disorders
What are the environmental factors that affect the severity of acid rain?
-Soil lime content; soils w/ ↑ lime content include CaCO3 which neutralises acids & reduces impact of acids on soil pH
-Fog; acid precipitation falling as rain may have relatively brief contact w/ leaves of vegetation. In areas w/ long periods of fog, acidic water droplets may be in contact w/ leaves of trees for long periods of time so damage caused by acids maybe ↑
-Snow; In areas where all precipitation= rain, impact of acids may be spread over long periods of time. Areas that have a lot of snow may accumulate acidic snow → is this melts quickly, pH of meltwater may be v↓, harming life in soil & rivers
Control of acid rain- oxides of Sulfur; how is natural gas desulfurised?
-Hydrogen sulfide removed from natural gas after it’s been extracted to prevent corrosion damage to refinery & pipeline equipment & to appliances in which gas is used
-Also prevents production of Sulfur dioxide when it’s burned. It’s removed by dissolving it in amine solution/reacting it w/ iron particles
Control of acid rain- oxides of Sulfur; how is crude oil desulfurised?
Sulfur compounds are removed from crude oil during distillation using molybdenum catalysts in process of hydrodesulfurisation
Control of acid rain- oxides of Sulfur; how is coal desulfurised?
-Most sulfur in coal → present as solid iron pyrites (FeS2)
-Can be removed by washing & streaming
-Coal is crushed then put in stream of flowing water
-Flow rate = fast enough to carry coal away but leave denser pyrites behind
Control of acid rain- oxides of Sulfur; how is dry flue-gas (FGD) desulfurised? + what are products used for?
-Gases passed through bed of crushed calcium carbonate
-Sulfur dioxide reacts w/ calcium carbonate → solid calcium sulfur
2CaCO^3 + 2SO² + O² → 2CaSO^4 + 2CO²
Calcium carbonate, Sulfur dioxide, Oxygen —> calcium sulfate
-If effluent gases have been cleaned to remove smoke particles, calcium sulfate made may be pure enough to make gypsum building plaster
Control of acid rain- oxides of Sulfur; how is wet flue-gas (FGD) desulfurised? + what are products used for
-Involves sodium sulfite scrubbing where flue gases are bubbled through sodium sulfite solution
NaSO^3 + H²O + SO² → 2NaHSO^3
Sodium sulfite, water, sulfur dioxide, sodium hydrogen sulfite
-Sodium hydrogen sulfite can be heated. Breaks down to make sodium sulfite & water; reused, concentrated pure sulfur dioxide → valuable industrial raw material, can be converted to solid sulfur/sulfuric acid
Control of acid rain- oxides of nitrogen; how is low temperature combustion used?
Less NOx made in low temp combustion techniques, like fluidised bed combustion, where ↑S.A for combustion maintains rapid combustion w/out need for high temps
Control of acid rain- oxides of nitrogen; how are catalytic converters used?
Chamber in exhaust pipes contain catalyst like platinum; chemically reduces NOx back to N² & O² gas
Control of acid rain- oxides of nitrogen; how are urea sprays used?
NOx can be removed by reacting it w/ urea
Tropospheric ozone; what is the difference between stratospheric and tropospheric ozone?
-Stratospheric ozone occurs naturally, is important for life on Earth as ↓ exposure to harmful UV light
-Tropospheric ozone is a pollutant, produced as result of human activities & is toxic to living organisms
Tropospheric ozone; what are the effects of tropospheric ozone?
-Ozone= toxic to plants, ↓ growth rates of trees & agricultural crops
-In humans ozone causes breathing difficulties, ↑asthma rates
-Is also involved in producing secondary pollutants in photochemical smogs & acid rain
Tropospheric ozone; what are the sources of tropospheric ozone?
Secondary pollutant produced by photochemical reactions
1.) nitrogen dioxide broken down by UV-A sunlight
2.) monatomic oxygen reacts w/ diatomic oxygen to produce ozone
NO² → NO + O O + O² → O^3
UV-A
Tropospheric ozone; how can tropospheric ozone be controlled?
-Is a secondary pollutant so levels can be controlled by ↓ levels of primary pollutants producing it
-Nitrogen dioxide → produced by internal combustion engines, power stations, other high temp combustion involving air
-Methods to ↓ releases will ↓ ozone levels by preventing its formation
Carbon monoxide; when is carbon monoxide (CO) produced?
When carbon-based materials are burned w/ shortage of oxygen, eg incomplete combustion of hydrocarbons, esp petrol & diesel in vehicle designs
Carbon monoxide; what are the effects of CO?
-Binds to haemoglobin, prevents it from carrying oxygen from lungs to tissues around body
-If too much of haemoglobin in red blood cells= inactivated by CO, brain damage may occur & possible death
- ↓conc of CO can ↑ health issues due to chronic heart disease
Carbon monoxide; how can CO be controlled?
-Exhaust catalytic converters oxidise CO to CO²
-Although CO² is a pollutant, ↑in CO² emissions due to oxidising CO= v small compared w/ other emissions
Water pollution; what factors affect the concentration of pollutants?
-Water cycle; natural purification process. When water evaporates as water vapour, its pure
-It then falls as rain, flows to sea carrying dissolved & suspended materials (including pollutants) w/ it
-When water evaporates, pollutants are left behind & may become more concentrated
Water pollution; what are the factors that affect dilution?
-Effluent quantity; # of pollutant released will clearly affect concentration. If concentration of pollutant in water= low, many pollutants aren’t harmful
-Vol of water; larger bodies of water dilute waste more
-Residence time of water; shorter residence time of water= more likely pollutant will be carried away by flowing water & not accumulate
Water pollution; what is degradation/biodegradation?
-The process by which substances are broken down
-Involves both biotic & abiotic factors
-Biodegradation involves microorganisms, while physical processes include chemical & photochemical reactions
Water pollution; what are the factors which affect degradation?
-↑ levels of sunlight/UV may cause photochemical degradation
-Dissolved oxygen; ↑ rate at which aerobic bacteria break down sewage
-↑ temps; ↑ rate of most reactions
-Environments conditions will also control new substances produced. In aerated surfaces water pollutants= more likely to be oxidised. Oxidation of organic pollutants often causes them to break down → less harmful substances. In deeper water where pollutants are part of sediments they’re likely to be chemically reduced, eg inorganic mercury wastes being changed to methyl mercury (more hazardous)
Water pollution; how does removal rate affect the pollutant?
-Pollutants become less of issue if they become part of sediment in body of water
-This effectively removes them from the water
-Pollutants like phosphates & pesticides can become adsorbed onto sediment particles
Water pollution; what is dispersal and how does this affect the pollutant?
-Currents in water will move pollutants away, dispersing them through water & diluting them
-Understanding where & how this occurs can help determine where to locate suitable sites for effluent discharge
-Dilution of pollutant through dispersal in lakes & sea can ↓ harmful effects & may give impression they’ve disappeared but they persist over time & don’t biodegrade + may gradually become ↑ conc. If this becomes an issue → may be hard to solve due to large vol of water affected
-May be processes causing pollutant to re-concentrate, eg bioaccumulation dong food chain of heavy metals & some pesticides
Water pollution; what are examples of water bodies likely to be polluted and the cause?
-Rivers Tees, Tyne, Danube, Rhine—> industrial areas
-River Ganges—> areas w/ large human populations
-Mediterranean Sea, Great Lakes of N America—> lakes & enclosed seas in which pollutants may collect
-English Channel, Persian Gulf, St Lawrence Seaway—> heavy shipping
-Rotterdam, Persian Gulf—> Oil terminals & ports
Thermal pollution; what is the source of thermal pollution?
Main source of hot water= steam turbine power stations using cold water from lake, river, sea to condense steam
Coolant water is returned to its source at higher temp
Thermal pollution; what are the ecological effects of thermal pollution?
-Warm effluent water can have ecological effects, esp on dissolved oxygen conc, as max amount of oxygen that can dissolve in water is controlled by temp
-Most aquatic organisms will be killed by high temps as proteins are denatured. Solubility of oxygen declines as temp increases
-Some aquatic organisms—> often near lower end of range of tolerance for dissolved oxygen. Increase in temp may cause oxygen to come out of solution—> death of sensitive organisms
Thermal pollution; what are the physiological changes that thermal pollution causes?
High water temps can cause physiological effects like;
- ↑metabolic rates of many organisms, so more energy is used, leaving less surplus energy for growth
- ↑rate of development of eggs so hatch earlier
-Non-indigenous species, introduced from habitats w/ warmer climates may thrive & out-compete indigenous species
-Pollutant toxicity= often greater as toxins are metabolised more rapidly
-Resistance to disease may be ↓
Thermal pollution; how can thermal pollution be controlled?
-Cooling towers—> used to cool power station effluent water so doesn’t cause deoxygenation
-Water used to condense steam in power station is taken from nearby water source like lake & after absorbing heat from steam, water is returned at higher temp
-In larger bodies of water, warmer water will disperse & be diluted into large vol of cooler water so has no significant effects
-If heated water goes into relatively small body of water, may cause harmful temp rise. In situations where this is likely, cooling towers are used to ↓waste water temp by dispersing heat into atmosphere, so returning cooler water to source
Thermal pollution; control of thermal pollution- how do cooling towers work?
-Spraying hot water from shower floor in lower part of tall hollow tower
Air in tower absorbs heat from water, rises up tower & escaping into open atmosphere
-This causes updraught, draws more air through shower spray, aiding cooling
Oil pollution- causes; how does waste lubricating oil cause oil pollution?
-Vehicle engine lubricating oil which leaks/is deliberately discarded into environment
-Industrial machine oil; washed into drains/mixed w/ other effluents
Oil pollution- causes; how do accidental releases cause oil pollution?
-Shipping accidents esp oil tankers
-Oil rig accidents
-Oil pipeline leaks
-Leakage from storage tanks
-Discharge of waste water from washing tanks on ship tankers
Oil pollution- causes; how does oil exploration cause oil pollution?
-Drilling; drill pipes need to be lubricated to ↓friction as bore through rock
-Is usually done w/ fine clay suspended in water. Sometimes, oil-based clays are used, eg where rock would absorb water & expand
-Pollution risk w/ modern oil-based clay is ↓by using diesel & low toxicity oils rather than heavier oils
Oil pollution; what is the effect of oil pollution in marine ecosystems?
-Some components of crude oil → toxic, eg benzene & xylene. Planktonic organisms that float near water surface = most likely to be affected
-Oil can cover aquatic life living on seashore/at sea surface. Animals like molluscs & crustaceans can be asphyxiated. Algae on seashore would be unable to absorb sunlight/carbon dioxide for photosynthesis
-Oil can form v thin layer on water surface, ↓# of oxygen that can dissolve from atmosphere into water. Can ↓ survival of aerobic organisms
-Marine organisms which find mates/food using sense of smell may have difficulties doing so due to masking odour/narcotising effect of oil
Oil pollution; what are the effects of oil pollution on birds?
-Severe covering of oil can cause birds to drown
-Oil causes birds’ feathers to stick together so lose insulating properties. Birds may die of hypothermia
-Birds may be able to clean their feathers it have a small # of oil on them, but this may ↓ time available to find food for themselves/their young
Control of oil pollution; what method is used to prevent oil releases?
Recycling of waste lubrication oil;
used lubricating oil from vehicle engines/engineering machinery shoudn’t be treated as waste material
Contaminants can be removed, chemical reforming & distillation can produce commercially valuable lubricants again. Waste oil that cannot be recycled can be burnt as fuel, ↓ demand for fuel from other sources
Control of oil pollution- improved oil tanker operation; how can better shipping routes control oil pollution?
Oil tankers may have to stay greater distance away from shore when possible. If tanker has mechanical difficulties, like engine failure, would give more time to deal w/ it before it may be carried ashore by water currents/winds
Control of oil pollution- improved oil tanker operation; how can better navigation systems control oil pollution?
-New technologies like GPS enable more accurate navigation
-The Automatic Identification System (AIS) allows positions of most ships to be monitored & coordinated to help avoid collisions
Control of oil pollution- improved oil tanker operation; how can inert gas systems control oil pollution?
-In past when tankers unloaded their tanks at oil terminal, space left by oil used to fill up w/ air
-Can produce explosive mix of air & oil vapours → caused loss of some tankers, causing pollution by remaining oil in tanks
-Modern tankers used cooled exhaust gases from engines to replace oil. This has no oxygen in it so explosions aren’t possible
Control of oil pollution- improved oil tanker operation; how can tank washing procedures control oil pollution?
-Oil tanks must be washed to prevent build-up of tar sludges
-Tanks used to be washed out w/ seawater then oily water was discharged into sea
-This pollution → prevented by recirculating oil in tanks during unloading so sludges are mixed up removed w/ cargo
Control of oil pollution- improved oil tanker operation; how can oily waste water disposal control oil pollution?
-Any oily waste water produced can be unloaded at oil terminal when tanker docks
-Oil & water can be separated, then oil can be recycled/incinerated while treated water is discharged
Control of oil pollution- improved tanker designs; how can double hulls control pollution?
-Tankers used to have single layer of steel betw oil & sea
-Any damage to steel hull could allow release of oil → sea
-All large tankers now have twin hulls w/ gap of up to 2m betw hulls so damage to outer hull doesn’t necessarily cause release of oil
Control of oil pollution- improved tanker designs; how can twin engine/rudder/fuel tanks control oil pollution?
-Any mechanical failure on tanker affecting propulsion/steering can be serious as ship may be carried by currents/winds onto rocks or coast
-Having pairs of essential equipment can save ship if one set breaks down
Control of oil pollution- improved tanker designs; how can separate oil & ballast tanks control oil pollution?
-When oil tanker isn’t carrying oil it must carry ballast water so hull is kept down in water, propeller & rudder still work
-In past, ballast water was carried in empty oil tanks
-When ballast water was pumped back into sea it’d carry some residual oil from tanks
-Modern tankers have separate oil & ballast water tanks so no pollution is caused by emptying ballast tanks → sea
Control of oil pollution; how do oil inceptors work?
-Separate oil from watery waste like drainage water from major roads/car parks, where may be some floating oil
-Water flows into main drainage system/river but oil is retained & can be removed later for treatment
Control of oil pollution; how do bund walls work?
-Oil storage tanks = built on impermeable bases surrounded by bund wall which would contain oil if tank were to split
-Vol enclosed by bund wall > that of tank so can’t overflow
Treatment of oil spills; when is oil pollution most serious?
When it occurs inshore/in an enclosed body of water, where dispersal is prevented, where there are more sensitive ecosystems/more concentrated human activities to be affected
Treatment of oil spills; What are booms + their limitation?
-Inflatable tubes that restrict movement of floating oil
-A ‘skirt’ below boom can retain oil if there’s a water current
-Don’t work in open water where current/waves are too strong, so their main uses are in sheltered areas where they can ↓ dispersal of oil from pollution source/protect sensitive areas
Treatment of oil spills; what are skimmers & how do they work?
Rotating metal discs that pick up oil that can be scraped off & stored for later disposal by incineration/landfill
Treatment of oil spills; how can absorbent materials be used for oil spill treatment?
-High S.A materials like textile mops can help to absorb oil
-The absorbent material & oil can be removed + disposed of by incineration/in landfill sites
Treatment of oil spills; how can detergents/dispersants be used to treat oil spills?
-Break up oil to produce emulsion of oil droplets in water
-Allow oil to become more mobile & disperse, possibly to be broken down by bacteria but don’t ↓ # of oil pollution themselves
-Can be spread at sea by aircraft & ships/ using backpack sprayers on shore
Treatment of oil spills; how do polymerising agents help treat oil spills?
Chemicals have been developed causing oil molecules to join together, producing more solid materials that can be collected more easily
Treatment of oil spills; what is steam washing and how can it be used to treat oil spills?
-Oil on beaches can be washed off w/ sprays of steam & hot water
-Doesn’t destroy oil but can remove it from particularly sensitive habitats
-The steam jets may kill organisms deeper in beach sediments that weren’t affected by oil
Treatment of oil spills; what is bioremediation and how effective is it?
-Some bacteria break down hydrocarbons & help to remove residual pollution left after other clean-up methods have been used
-Rate of bacterial action depends on environmental conditions & is most rapid where temps, oxygen levels, nutrient levels are ↑
-Bioremediation of soil may be accelerated by irrigation, addition of nutrients & ploughing to aerate soil
Pesticide pollution; why are pesticides unusual pollutants?
-Are intended to be toxic, are deliberately spread → environment
-They don’t just harm the target species
Pesticide properties causing pollution; how does specificity affect the pesticide?
-No pesticides are so specific that they only kill the target organisms & are completely harmless to non-target organisms
-Harm to non-target species may be ↓ by controlling dose applied
Pesticide properties causing pollution; what is MDAF & MDNF?
-MDAF; lowest dose that’ll kill every member of a population. Can be used to estimate dose needed to control pests
-MDNF; highest dose that can be used w/out killing any members of the population. Ideally, pesticide dose wouldn’t exceed MDNF of non-target species
Pesticide properties causing pollution; how does persistence affect the pesticide?
Persistent pesticides may remain in environment long enough to disperse over larger areas & are more likely to have time to bioaccumulate & biomagnify
Pesticide properties causing pollution; how does bioaccumulation affect the pesticide?
-Liposoluble pesticides → those which dissolve into fats, eg within human body
-If organisms are unable to excrete them/break them down fast enough some will accumulate in the body
-Over a long period of time exposure, even to small doses, may eventually produce toxic concentrations
Pesticide properties causing pollution; how does biomagnification affect the pesticide?
Pesticides which have bioaccumulated in one type of organism may become more concentrated when they’re eaten by their predators
Pesticide properties causing pollution; how does mobility affect the pesticide?
-Is controlled by other properties like persistence, solubility, ease of vapourisation
-Some may be transported within living organisms to new areas where they may be excreted
Effects of pesticide pollution; what are the direct effects of pesticide pollution on living organisms?
-Cause harm to non-target species by being toxic
-Doses not in themselves lethal may inhibit metabolic processes & cause ill health. Higher doses may kill
-Eg; DDT affected many birds by being concentrated within food chains. ↓doses caused eggs to have thin shells which broke easily. ↑ doses caused sterility & much ↑ doses caused death
-As a result, lower doses can still cause species to die out as breeding success is ↓ to below rate needed to maintain population
Effects of pesticide pollution; what are the indirect effects of pesticide pollution on living organisms?
-↓ in population of one species can affect other inter-dependent species
-Some species become rarer as have lost food supply/ecosystem service like pollinationor seed dispersal
-Other species may become more common as they’ve ↓ competitors/predators
Environmental impacts of insecticides- organochlorines; how were organochlorine insecticides first used?
-1940s to control pests that transferred human pathogens like mosquitoes carrying malaria & the ticks, lice, fleas carrying typhus fever
-This use of DDT saved many thousands of lives
Environmental impacts of insecticides- organochlorines; what were organochlorines then used as and how did their properties make them ideal?
-As an agricultural insecticide. Ideal properties;
-↑ toxicity to insects
-↓ toxicity to vertebrates like mammals, so farm workers were unlikely to suffer acute toxic effects
-↑ persistence so continued to protect crops for some time after application
-↑ liposolubility & low solubility in water so it wasn’t easily washed off fields by heavy rain
Environmental impacts of insecticides- organochlorines; what was DDT also used for in homes?
Control pests by incorporating it in paint, wallpaper, or pest sprays
Environmental impacts of insecticides- organochlorines; what environmental impacts occurred due to the properties of DDT?
↑ toxicity to insects led to deaths of many non-target insects like bees, butterflies, beetles
↑ persistence & liposolubility allowed DDT to bioaccumulate & biomagnify up food chains.↑ in conc occurring produced levels toxic to predatory vertebrates at top of food chain like birds of prey, herons, otters
-Use of organochlorines killed top predators in many areas
-Rate of degradation of DDT depends upon environmental conditions but can remain in environment for decades
Environmental impacts of insecticides- organochlorines; what are examples of other major organochlorine insecticides?
Dieldrin, aldrin, lindane
Environmental impacts of insecticides- organochlorines; are organochlorine insecticides still in use?
-Use of all of them are now banned/heavily restricted
-DDT is still used to control malaria mosquitoes in houses; considered to be safe as shouldn’t cause toxic exposure/lead to DDT entering human food chain where could biomagnify
Environmental impacts of insecticides- organophosphate; what are organophosphate pesticides and examples of them?
-Neurotoxins that inactivate acetylcholinesterase enzyme so nerve function is damaged
-Eg; nerve gees Sarin, developed during WW2 as weapon
-Others developed as insecticides like malathion & parathion
Environmental impacts of insecticides- organophosphate; what are the positives and negatives of organophosphates?
-Have low persistence & liposolubility so don’t bioaccumulate/biomagnify
-Have ↑ mammalian toxicity so farm workers can be at risk of acute exposure to toxic doses → possible death
-Chronic exposure to ↓ doses is associated w/ impaired memory, depression, behavioural changes, ADHD, Alzheimer’s disease
-Some organophosphates are suspected carcinogens
Environmental impacts of insecticides- pyrethroids; what are pyrethroids and their properties?
-Synthetic insecticides developed from natural pyrethrin insecticides extracted from plants
-Have ↑insect toxicity & ↓mammal toxicity
-Not persistent so don’t bioaccumulate/biomagnify
Environmental impacts of insecticides- pyrethroids; how safe are pyrethroids for humans and aquatic organisms?
-Use is generally safe for humans unless v large dose is absorbed
-Are most commonly used domestic insecticides
-Are toxic to fish so shouldn’t be used near rivers/fish farms
Environmental impacts of insecticides- neonicotinoids; what are neonicotinoids and how do they act?
-Most widely used insecticides, chemically similar to nicotine
-Neurotoxins, inhibit action of neurotransmitter acetylcholine
Environmental impacts of insecticides- neonicotinoids; what are properties of neonicotinoids and how do they affect them?
-Have ↑ insect toxicity but ↓er toxicity to vertebrates as can’t cross blood-brain barrier of vertebrates
-Relatively persistent & water soluble so remain in soil long enough to be absorbed by roots & translocated within crop plants; then protected from insect pests
Environmental impacts of insecticides- neonicotinoids; what are the environmental effects of neonicotinoids?
-Very toxic to bees use has been linked to ↓ of many bee populations
-Have neurotoxic effects, ↓ ability to navigate &↓ immunity to disease
-Toxic effects most likely when are sprayed into crop/when neonicotinoid dust is carried by wind
-Impact on non-target species appears to be ↑ by synergistic action w/ some fungicides that may be present at same time
-Research suggests they may build up in aquifers which may cause issues in future
Environmental impacts of insecticides- neonicotinoids; how can neonicotinoids be used to reduce harmful impacts?
Using them as coated seed treatment minimises harmful impacts on non-target species
Environmental impacts of insecticides- neonicotinoids; when are neonicotinoids broken down most rapidly?
In the presence of sunlight & soil microbes
Methods of reducing pesticide pollution; what are examples of pesticides being restricted for use and how has this reduced pesticide pollution?
-Some pesticides have been banned/use has been restricted where could create issues or when benefit of use is > disadvantages
-Use of organochlorines DDT, dieldrin& aldrin is banned in most countries. DDT is still used in some countries for control of malaria mosquitoes
-Organophosphate methyl parathion is still used as agricultural insecticide, but use is generally prohibited for control of garden/domestic pests
Methods of reducing pesticide pollution; how has the use of non-persistent pesticides reduced pesticide pollution + examples of this?
-Low persistent pesticides will break down more rapidly & can’t become more conc/travel long distances after application
-Organophosphate insecticides= less persistent than organochlorine insecticides
Methods of reducing pesticide pollution; how can the use of more specific pesticides reduce pesticide pollution + example?
Pyrethroid & organochlorine insecticides= both toxic to insects but pyrethroids are less toxic to mammals
Methods of reducing pesticide pollution; how do systemic pesticides work and why can they reduced pesticide pollution?
-Are absorbed by crop & translocated within it
-They don’t need to be sprayed into all surfaces, aren’t washed off after they’ve been absorbed & will protect new growth
-As systemic pesticides are present within plant tissue, may be eaten by humans if still present when crop is eaten
Methods of reducing pesticide pollution; how can application timing reduce pesticide pollution?
-Spraying on still days results in less spray drift onto surrounding habitats
-Spraying at night/when crops aren’t in flower will ↓impact on bees
-Newer spraying techniques use smaller droplets to produce more even coverage which ↓# required to adequately cover all areas of crop leaves
Inorganic nutrient pollution and cultural eutrophication; what are the sources of inorganic nutrients?
-Phosphates in sewage effluent & eroded soil particles
-Nitrates washed off farmland from manure & artificial fertilisers
Inorganic nutrient pollution and cultural eutrophication; what is eutrophication and how can it be caused?
-Enrichment of water body w/ nutrients, usually w/ excess # of nutrients
-As result, plants & algae grow + may result in O² depletion of water body
-Can happen naturally over time but also result of human activities like discharge of phosphate-containing detergents/fertilisers/sewage in aquatic systems
-Can occur via clearing land & run-off, resulting in large # of nutrients that build up relatively rapidly
Inorganic nutrient pollution and cultural eutrophication; what are the main nutrients involved in eutrophication and why?
Nutrients & phosphates as these are often limiting factors on plant growth in aquatic ecosystems
Inorganic nutrient pollution and cultural eutrophication; what are the two categories of lakes resulting from eutrophication?
-Oligotrophic lakes; few nutrients, little plants growth, eg mountain lakes
-Eutrophic lakes; rich in nutrients, abundant plant growth, eg lowland lakes
Inorganic nutrient pollution and cultural eutrophication; what problems does the growth of algae lead to?
-Cyanobacteria can release harmful toxins, can affect livestock/pets/people who drink or are in contact w/ water
-Floating algae shade submerged/rooted macrophytes (larger plants) which can’t photosynthesise. Plants may die; disrupts food webs & decay by aerobic bacteria may cause deoxygenation
-Algae= unreliable food source & don’t support rich food webs as can die rapidly if nutrients are depleted/other conditions aren’t ideal like light or temp
Inorganic nutrient pollution and cultural eutrophication; what are the effects of nitrates on human health?
-Very soluble & may get into drinking water supplies
-May be ingested in processed food
Inorganic nutrient pollution and cultural eutrophication; what are the effects of nitrates on babies?
-Nitrates aren’t very toxic but bacteria in gut convert them to nitrites, which react w/ haemoglobin in blood & reduce its ability to carry O²
-High levels may cause disease methaemoglobinaemia/‘blue baby syndrome’. Infants= more at risk as have more of necessary bacteria so haemoglobin reacts more rapidly w/ nitrites
-Usually only issue w/ water from shallow wells receiving drainage water from arable farmland
-Nitrites are also ingested as food additives in meat, fish, cheese products
Inorganic nutrient pollution and cultural eutrophication; how are nitrates linked to cancer?
-Gut bacteria convert nitrates into nitrites
-These may be converted in gut to nitrosamines which are carcinogens & may cause stomach cancer
-Most research has been carried out in rats & link between nitrates in water supplies & cancer in humans isn’t conclusive
Control of inorganic nutrients; what are the ways in which inorganic nutrients, like nitrates, can be controlled?
-Reduced nitrate fertiliser use
-Reduced ploughing at times of heavy rain
-Use of soluble, rapid-release fertilisers
-Deposition of waste manure where nutrients won’t leach into ground/be washed into river
-Reducing cultivation of crops that have higher nitrogen requirements, eg replacing wheat w/ triticale
-Reducing reliance on artificial fertilisers, eg by growing more legume crops w/ nitrogen-fixing root nodules bacteria
Control of inorganic nutrients; where are techniques to control inorganic nutrients most important?
In Nitrate Vulnerable Zones where aquifers may be exposed at surface & can easily become contaminated
Control of inorganic nutrients; what are other ways of managing and limiting the effects of inorganic nutrients?
-Adding iron (III) sulfate to remove phosphates from liquid effluents released by sewage treatment works. Phosphates are precipitated as fine sediments of iron phosphates
-Dredging lakes & rivers that have phosphate-rich sediments from past pollution/adding iron (III) sulfur to reduce solubility of phosphates
Organic nutrient pollution; what are the sources of organic nutrients?
-Many processes produce liquid effluents containing organic nutrients like carbohydrates, lipids & proteins
-The processes include sewage works, manure disposal, silage storage, leather tanneries, pepper mills & food processing plants
Effects of organic nutrient pollution; how can organic nutrient pollution cause deoxygenation + disrupt photosynthesis?
-Untreated organic nutrients which flow → rivers/lakes provide food for microorganisms in water
-As a result, their aerobic digestion deoxygenates water & may kill aerobic organisms like fish & insects
-Microorganisms can also cover river/lake bed. Will prevent light reaching normal water plants so photosynthesis is inhibited, killing plants & disrupting food webs
Effects of organic nutrient pollution; how can organic nutrient pollution spread pathogens/diseases + what examples?
-Sewage can contain pathogens from infected people
If other people come in content, either directly/via contaminated food or water, disease can spread
-Diseases include cholera, typhoid & dysentery
Effects of organic nutrient pollution; how could organic nutrient pollution possibly cause eutrophication?
-Don’t cause eutrophication directly as provide nutrients for heterotrophs (can’t provide own food, eats others) not nutrients for photoautotrophs (photosynthesise)
-However as they decay, may release inorganic nutrients causing eutrophication
Treatment of organic effluents; how were organic effluents dealt with before vs now?
-Used to be common to discharge untreated sewage → rivers & sea, now banned in many countries
-Each sewage treatment works is designed to treat specific effluent, eg to prevent deoxygenation & pathogens so fluids can be discharged w/out causing unacceptable pollution
Treatment of organic effluents; how is the effluent received by sewage works produced and how concentrated is it?
Toilet flushing water, water from washing clothes, dishes, personal hygiene, road drainage water & non-toxic industrial waste
So actual conc of sewage is very low
Treatment of organic effluents; what are the main groups of treatment processes in activated sludge treatment?
-Pre-treatment; removal of solid objects like paper, plastic, road grit
-Primary treatment; separation of most organic solids from fluids
-Secondary treatment; digestion & breakdown of remaining organic matter in fluids
-Tertiary treatment; additional treatment to remove phosphates/bacteria
-Sludge treatment
Treatment of organic effluents; what are the methods used In pre-treatment?
-Screens; metal grills/sieves used to trap floating & suspended items like plastic & paper items → then treated by incineration/disposed of in landfill site
-Grit traps for stones & road grit. Usually channel widens out so effluent flows more slowly & grit drops to bottom as there’s no longer enough kinetic energy to carry it along. Grit can later be removed from tank then disposed of in landfill sites/sterilisation & reuse
-Communicators chop up suspended faecal solids,↑ exposed s.a & speeding up later processes
Treatment of organic effluents; what occurs in primary treatment?
-Primary sedimentation= most important process
-Effluent left to stand in large tanks where faecal solids sink to bottom so can be removed & treated separately
-Results in 95%+ of organic matter being removed from fluid effluent so risk of deoxygenation in river/lake greatly ↓
Treatment of organic effluents; what methods are used in sludge treatment and why?
-Sludge removed from primary sedimentation tanks probably contains pathogens & its foul smell makes storage/disposal near urban areas difficult
-To solve these issues anaerobic digestion is used → anaerobic microbes digest sludge in warm digestion tank for about 4 weeks
-Kills pathogens & odours ↓
-What remains after process has ↓ vol, disposed of in many ways
Treatment of organic effluents; what are the advantages & disadvantages of the contents of post-sludge treatment being disposed of in a landfill
Simple & relatively cheap but wastes their nutrient content
Treatment of organic effluents; what is the advantage & disadvantage of the contents of post-sludge treatment being disposed of in the sea?
-Relatively straightforward for coastal communities
-Most countries now ban this to ↓ pollution
Treatment of organic effluents; what is the advantage & disadvantage of the contents of post-sludge treatment being disposed of by incineration?
-A lot of fuel (usually natural gas) required, so expensive
-Also creates further waste in form of gas & small # of ash, deposited in Iandfill sites
Treatment of organic effluents; how can the contents of post-sludge treatment be disposed of in agricultural use?
-Sludge can be used as agricultural fertilisers → has better C:N ratio, ↓ vol &↓ odour than undigested sludge
-It’s crucial to time spread carefully as application during growing season would cover crops, while application during winter can cause damage to damp soils as farm vehicles compact soil
-Heavy metals from urban wastes & road runoff may be present in sludge & could be absorbed by crops, then consumed w/ food. Can be ↓ by adding lime to ↓ solubility of heavy metals
-Remaining pathogens can be destroyed by heat treatment of sludge before use
Treatment of organic effluents; what does secondary treatment destroy?
Small # of organic matter remaining in effluent from primary sedimentation tank
Treatment of organic effluents - secondary treatment methods; how are oxidation ponds/aeration tanks used?
-Remaining organic matter in fluid effluent = broken down by bacteria
-Shortage of oxygen can be limiting factor as slows aerobic processes
-To prevent this, large amounts of air are mixed in by paddle wheels/air stones. Pure oxygen may also be used
Treatment of organic effluents - secondary treatment methods; how are secondary sedimentation tanks used?
-Effluent from aeration tanks contains suspended bacteria, mustn’t be wasted → collected in secondary sedimentation tank & returned to aeration tank as ‘activated sludge’
-Most sewage works → clear effluent from secondary treatment discharged into river/lake/sea. Should have no pathogens, other organic materials, but may have some dissolved inorganic nutrients that could cause cultural eutrophication
Treatment of organic effluents - secondary treatment methods; how and why are trickling filter beds used?
-Provide alternative process to aeration tanks
-Older technique, has been largely replaced by use of aeration tanks in activated sludge treatment
-4 rotating arms spray liquid effluent over large cylindrical tanks w/ lumps of solid material like gravel, coke
-S.A is maximised for bacteria, fungi, algae, worms, other invertebrates to digest remaining organic matter
-Nitrates may also be denitrified by bacteria so liquid effluent will cause less eutrophication
Treatment of organic effluents; when is tertiary treatment used?
If discharge site for treated effluent is particularly ecologically sensitive/important for humans
Treatment of organic effluents; what methods are used in tertiary treatment?
-Phosphates can be removed by adding solution of iron (III) sulfate producing insoluble iron phosphate as fine sediment, can be used as agricultural fertiliser
-Effluent can be strained through v fine sieves (micro-strainers). Remaining suspended bacteria killed by UV light/by adding sterilising chemical like chlorine
Organic nutrient pollution; how do weather-related fluctuations affect flow volume?
-While vol of sewage remains relatively stable through year, vol of effluent received by treatment works can vary significantly w/ changes in weather, eg, as a result of storm/drought
-Sewage works= designed to cope w/ some extra flow but not max flow that’s possible, to do this would incur great extra expense to allow v rare extreme storm events
-Most sewage works have storm overflow tanks, can be used to hold surplus effluent after a storm → treated later when the vol of effluent arriving returns to normal
Organic nutrient pollution; in the UK, when were the majority of sewage systems developed?
Over the last 150 years
Organic nutrient pollution; what kind of sewage collection systems are there?
-Underground pipes laid to collect all solid & liquid effluents often incl drainage water from roads & roofs
-Originally were discharged into river/sea untreated/onto fields in ‘sewage farms’
-Sewage treatment works were added later, approach produces large vol of dilute sewage effluent
-It’s more efficient to have 2 separate waste collection systems; one collects only foul waste from toilets, needs full treatment but smaller vol involved allows construction of smaller & so cheaper, sewage treatment works
-Also means system isn’t affected by flow fluctuations due to weather changes. 2nd system collects larger vol of cleaner water, requires little treatment before discharge
What is acid mine drainage?
-Many igneous metal ores are sulfides
-In spoil heaps, chemical reactions take place betw the small # of remaining sulfide ores & O² from air in spaces betw waste particles
-May leave metal oxides & oxides of sulfur → dissolve in drainage water to make sulfuric acid, known as acid mine drainage
Acid mine drainage; what are the effects of acid mine drainage?
-Acidic solutions leaching out of spoil heap have similar effects to acid rain leaching through soil
-pH of solutions= often v ↓& may contain dissolved toxic metals if were present in mine waste
Acid mine drainage; how can acid mine drainage be controlled?
-Ph of drainage water can be ↑ by passing it through crushed limestone to neutralise acids
-Will also ↓ solubility of many toxic metals
Monitoring water pollution; what kind of methods can be used?
-Wide range of physical, chemical & biological methods can be used
-Most pollutants can be monitored using chemical/physical method
-Modern methods usually use calibrated electronic meter
Monitoring water pollution; what factors determine which methods are selected?
-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 effects of pollution rather than levels of pollutant itself
Monitoring water pollution; what is Biological/Biochemical Oxygen Demand (BOD)?
-Organic materials of plant/animal origin can provide food for bacteria, lead to deoxygenation as they respire anaerobically
-It’s difficult to measure/forecast levels of organic pollutants as there’s so many that could be present & have diff potentials to cause deoxygenation
-So, organic pollution → monitored via level of deoxygenation caused
-# of O² used is measured using standardised conditions
Monitoring water pollution; what are the standardised conditions for BOD measurement?
Water level; 1 litre of water
Temperature; 20°C
Time period; 5 days
Light level; In dark, to prevent O² replacement by photosynthesis if algae present in water
Monitoring water pollution; what is Chemical Oxygen Demand (COD)?
Similar to BOD but measures # of oxygen needed to chemically oxidise all organic & inorganic substances in water sample
Monitoring water pollution; what is coliform count and why is it measured?
-One of more common gut bacteria= E. coli.
-Its presence in water is → confirmation of faecal contamination
-Health risk can be determined by measuring # of coliform bacteria in sample as indicates how serious contamination is
-It’s better to monitor this than presence of pathogens like typhoid as won’t always be present & whose absence wouldn’t confirm that water is uncontaminated
Monitoring water pollution; what are biotic indices and the characteristics of species used in them?
-Scale for showing quality of environment by indicating types of organisms present
Characteristics of species used;
-Have diff sensitivities to pollution
-Are easy to identify
-Are easy to find
-Are normally present
-Are usually common
-Are generally distributed
Monitoring water pollution; what are the advantages and disadvantages of biotic indices?
-Advantages; rapid assessment of current & recent pollution can be made & expensive equipment isn’t required
-Disadvantages; sorting samples can be time-consuming, identification of diff taxa involves some skill, further tests required using other techniques to detect specific pollutants present
Monitoring water pollution; what are 2 commonly used biotic indices?
-Lichens to monitor atmospheric acid pollution
-Aquatic invertebrates to to monitor water pollution
Heavy metals; what is pollution caused by heavy metals affected by?
Properties like liposolubility, synergism & solubility
Heavy metals; what do many heavy metals inhibit?
Enzyme function, especially enzymes of nervous system
Heavy metals; how do the key properties of heavy metals affect their impacts?
-Liposoluble heavy metals may be stored in fat droplets in living cells so chronic exposure to small doses may eventually cause toxic conc by bioaccumulation
-Passage along food chain may lead to biomagnification
-Some cause more serious pollution if act in conjunction w/ other pollutants like synergism betw cadmium & zinc
-Most= v soluble at ↓ pH, so pollution caused by heavy metal wastes can be ↓ by ↑ pH to ↓ solubility
Heavy metals; what products has lead been used for and why have some of these been reduced?
-Car batteries, pipes, solder, paint, anti-knock petrol additives & flashing for roofs & windows on buildings
- some ↓/ stopped due to ↑ awareness of toxicity of lead
Heavy metals- lead; what are the different sources of lead pollution?
-Biggest uses of lead don’t necessarily cause pollution as they may not cause release of lead → environment
-Uses of lead causing pollution have been ↓ but uses not causing pollution continue, eg lead-acid batteries
-Industrial workers may inhale lead dust/absorb it through skin if dissolves in sweat
-Acute exposure to large doses may cause several symptoms like brain damage, paralysis, even death. Very ↑ doses can kill by causing liver & kidney failure
-Problems only likely in industrial accidents, prevented by good working practices, eg wearing facemasks
Control of lead pollution; why and how has lead pollution in pipes been controlled?
-Lead has been used to maker water pipes for 4,500+ years
-Small amounts of lead dissolve → water so people drinking may suffer chronic exposure
-UK→ most lead pipes replaced in 20th century w/ copper pipes but lead solder was still used to join them. This has now been replaced by solder based on tin, zinc, copper
-UK water companies no longer use lead pipes but some remain in old buildings
-In↑ risk areas, small amounts of phosphoric acid are added to water supply & produce insoluble layer of lead phosphate in pipes, preventing lead dissolving → water
Control of lead pollution; why and how has lead pollution been controlled in petrol additives?
-Anti-knock agents, eg tetra ethyl lead (TEL) were added → petrol to smooth explosion of combustion &↓ engine wear
-However, lead particulates were released → atmosphere, creating public health threat
-Since 1980s, lead has been replaced w/ other chemicals like benzene. -Other fuels like diesel, LPG, hydrogen & alcohol don’t need lead additives
Control of lead pollution; why and how has lead pollution in electrical solder been controlled?
-Lead-based solder used in electrical connections isn’t a significant threat to public health during use
-But, the lead can be vapourised & inhaled when it’s melted in soldering/if it’s melted in recycling after use
-Lead-free solder is now widely used & contains tin, silver, copper
Control of lead pollution; why and how has lead pollution in lead-based paint been controlled?
-Lead commands have been added to paint to accelerate drying &↑ durability
-Paint layers intact on surfaces pose ↓ health risk but dusty, flaking old paint poses ↑ one, esp to children who pick up particles under fingernails
-Removal of old paint can be health risk as dust/vapours made may be inhaled. Use of lead-based point has been phased out in many countries since 1980s
-Chemical paint strippers & hot air guns = safer paint removal methods as don’t make dust/vapours w/ lead
Control of lead pollution; why and how has lead pollution in fishing weights been controlled?
-Lead weights used on fishing lines may be discarded/lost then swallowed by waterfowl like swans mistaking them for snails, who may be killed by lead poisoning
-Lead has been phased out in UK for smaller fishing weights & replaced w/ metals like tungsten (less toxic)
Control of lead pollution; why and how has lead pollution in shotgun pellets been controlled?
-Most miss their target & land on ground
-Water birds line ducks & geese feeding on wetlands, where shooting has taken place, may swallow pellets & be poisoned
-Some voluntary schemes use alternative materials like tungsten steel for shotgun pellets used over wetlands
Heavy metals- mercury; what are the sources of mercury pollution?
Mercury is released → environment by;
-Disposal of items w/ mercury, eg batteries, fluorescent lights, thermometers
-Chemical plants producing chlorine w/ mercury electrodes
-Combustion of coal
Heavy metals- mercury; what does the severity of mercury pollution depend upon?
Its chemical form
Heavy metals- mercury; how does mercury being liquid (elemental) affect its toxicity?
Isn’t easily absorbed through skin/gut but vapours may be absorbed in lungs if inhaled
Heavy metals- mercury; how do mercury compounds being inorganic, eg mercury oxide, affect its toxicity?
Are absorbed moderately well in gut
Heavy metals- mercury; how do mercury compounds being organic, eg methyl mercury, affect its toxicity?
-Are absorbed easily through skin, gut & as vapours if inhaled
-They’re liposoluble so pass through cell membranes easily, including through blood-brain barrier → brain where impacts can be more serious
-Can also cross placenta & harm unborn babies
-Also causes kidney failure
Heavy metals- mercury; what are the impacts of less toxic forms of mercury?
-Some situations → less toxic forms of mercury have been released but pollution issues created have been v severe
-Relatively ↓ toxicity inorganic mercury compounds entering anaerobic sediments in lakes/sea may be changed → organic compounds like methyl mercury by anaerobic microbes
-Mercury then bioaccumulates & biomagnifies along foodchains, often reaching conc that are much ↑ than when was released → environment
Heavy metals- mercury; how can mercury pollution be controlled?
Many uses of mercury & effluent disposal methods have been restricted as understanding of mercury pollution problems have ↑, eg;
-Mercury thermometers have been replaced by alcohol/electronic ones
-Mercury can be removed from effluents by reverse osmosis/by using activated carbon filters
-Ion exchange filters
-Disposal at ↑pH to ↓ solubility
Heavy metals- cadmium; what are the sources of cadmium pollution?
-Disposal of old nickel-cadmium batteries
-Incineration of wastes containing cadmium pigments, eg some plastics & paints
-Drainage water from cadmium & zinc mines (cadmium & zinc are often found together)
-New uses of cadmium in cadmium-telluride photovoltaic solar panels; manufacture & eventual disposal of old panels may cause pollution
Heavy metals- cadmium; what are the effects of cadmium?
It’s liposoluble & bioaccumulates so chronic exposure can lead to toxic conc & can biamagnify in food chains.it causes;
-Brain damage & paralysis
-Lung cancer
-Kidney failure
-Skeletal collapse due to bone decalcification
Heavy metals- cadmium; how can cadmium pollution be controlled?
-Most uses of cadmium have been restricted/banned, eg use in pigments
-Cadmium waste should be disposed of in hazardous waste landfill site/may be recycled, eg nickel-cadmium batteries
Heavy metals- Tin; how has tin been used in the past + consequences of this?
-In past, tin was used in antifouling paint on bottom of boats to control growth of marine organisms creating friction, slowing boats down
-Active chemical was tri-butyl tin (TBT), toxic to marine organisms like molluscs & crustaceans so prevented their growth
Heavy metals- Tin; what kind of issues can TBT cause?
-Had been assumed ↓ # of TBT dissolving into sea wouldn’t be conc enough to cause issues
-But, it’s an endocrine disruptor that alters growth & reproductive physiology of marine organisms like oysters & whelks
-Can also then pass → humans when such shellfish are eaten
Heavy metals- Tin; how has TBT been controlled?
-Now prohibited in anti-fouling paint
-Has been replaced w/ less toxic metals like copper
-Some countries also require paint residues made by boat cleaning to be disposed of in chemical waste landfill site rather than being washed → sea
Heavy metals- iron; what are the effects of iron pollution?
-Not toxic pollutant but can cause deoxygenation when oxidised in water
-Is soluble in its chemically reduced form (↓O² conditions)
-Iron in mine spoil heaps, where there’s little oxygen, may be leached → river by water draining through spoil heap. In river, may be oxidised & deposited as insoluble sediment of iron oxide
-Process of oxidation may deoxygenate river, causing death of aerobic organisms
Heavy metals- iron; how can iron pollution be controlled?
-Spoil heap drainage water is collected & passed over mesh screens where iron becomes oxidised & deposited on mesh son when water flows into river there’s no longer risk of deoxygenation
-Solid iron= periodically removed from mesh
What are solid wastes produced by and are they harmful?
-Many human activities
-Environmental impacts & choice of disposal method depend on materials involved
-Some made in large # but relatively harmless, others in small # but may be v hazardous
Sources of solid wastes; how can solid wastes be produced by mining and construction wastes?
Produce large # of waste; most non-hazardous but some can cause issues as include particular hazardous materials=
-Mine overburden heaps; usually non-toxic
-Mine spoil heals; may have toxic metals
-Demolition waste; may have hazardous materials like asbestos
Sources of solid wastes; how can solid wastes be produced by domestic & commercial municipal waste?
-Main categories= packaging & containers, paper, domestic appliances, organic materials, eg food & garden waste, clothing + other textiles
-Waste management issues; large # of waste made, collection labour expensive & intense due to all households creating waste, waste varies through year, eg garden waste in summer, many diff types of wastes mixed together
Sources of solid wastes; how can solid wastes be produced by industrial waste?
-Majority of industries make solid wastes
-Disposal issues will depend on properties of specific waste involved, amount produced
Solid wastes; what are the important properties of solid wastes influencing disposal method?
-Degradability; how rapidly waste breaks down
-Conditions affecting degradation, eg oxygen, pH, temp, bacteria presence
-Flammability
-Release of radioactivity
-Toxicity
Solid wastes; how does affluence affect the amount of waste generated?
More affluent people are more likely to;
-Purchase more consumer goods
-Purchase disposable items
-Throw items away rather than repair them
These also ↑ in manufacture of goods & mineral extraction required to make items
Solid wastes; how may manufacturing/retail industries attempt to increase sales using strategies increasing waste?
-Built-in obsolescence; items designed to have short lifespan. Eg are made to be non-durable/wear out or may be changing fashions so items become out-dated & discarded. Customer can then upgrade
-Disposable products; items intended to have limited usable life so need to be replaced sooner like disposable razors, ballpoint pens
-Over packaging; items may be made more attractive w/ unnecessary package likely to be thrown away
Solid waste disposal; what are the factors affecting waste disposal methods?
Many disposal methods are available for solid wastes, the one selected can be affected by;
-Pop density, eg collection costs are ↑ where there’s fewer people & wastes are dispersed
-Mass of waste made per capita
-Properties of waste, eg flammability, toxicity
-Land availability
-Availability of recycling technology
-Degree of environmental awareness & willingness of people to recycle, reuse, repair
-Regulatory framework & legislation
-Household income
-Waste processing costs for labour/machinery
Solid waste disposal; why are landfill sites often the simplest option for disposal + why can they still be a not ideal method?
-Requires little/no treatment of waste itself
-Early landfill sites were poorly managed, being used for mixed wastes w/ little attempt to prevent escape of harmful fluids & gases
Solid waste disposal; what are the features of good landfill site management?
-Separation of diff waste types & recording of composition & locations
-Polymer liner to prevent escape of leachate fluids
-Perimeter fence to trap litter blown by winds
-Regular covering w/ soil to ↓ pest issues
-Collection & treatment of leachate fluids
-Collection of methane & its use as fuel
-Impermeable cap to prevent water entering once site is complete; usually layers of clay & polymer
-Deodorising spray to control odours
-Dispersal of flammable materials rather than dumping large # in 1 place
-Chemicals which may react w/ each other shoudn’t be dumped together
Solid waste disposal; what are the disadvantages of landfills?
-Potential resource value lost, eg metals, glass, plastics
-Use large areas of land
-Organic matter decays anaerobically, release methane gas & CO²; contributing to global warming
-Toxic leachate may leak from poorly managed landfill sites
-Wildlife habitats & farmland may be lost
-Contaminants in site may prevent later development of landfill sites for uses like housing/agriculture
-Transport delivering waste → site & infrastructure around it generate noise & congestion in local area
Solid wastes- spoil heaps; what is industrial waste and what are the problems with it?
-Large # of non toxic solids
-Main issue = quantity but can also make polluting leachate fluids
Solid wastes- spoil heaps; what are the industrial activities that make spoil?
-Mining & quarrying, eg coal, china clay, metal ores
-Coal-fired power stations & incinerators produce ash
-Iron blast furnaces produced slag
Solid wastes- spoil heaps; why should spoil heaps be managed?
-Minimise environmental problems
-To make site reuse easier after site closure
Solid wastes- management of spoil heaps; why and how does the problem of stability in spoil heaps need to be solved?
-Landslips are a danger
-Surface erosion can be ↓ by establishing vegetation so roots hold spoil together
-Stability can be improved via compaction, either compacting it as spoil heap is built up/constructing buildings on concrete rafts to ↓ uneven settling, ↓ danger of subsidence
Solid wastes- management of spoil heaps; why and how does the problem of drainage in spoil heaps need to be solved?
Natural/artificial drainage may be essential where spoil heaps are tall/on hillsides to ↓ risk of landslides after heavy rain
Solid wastes- management of spoil heaps; why and how does the problem of a lack of nutrients in spoil heaps need to be solved?
-Some contain ↓ levels of plant nutrients, eg sand left after china clay extraction/shale spoil from coal mining
-Addition of topsoil, sewage sludge, fertilisers are common techniques to improve nutrient content &↑ plant growth
Solid wastes; management of spoil heaps; why and how does the problem of pH in spoil heaps need to be solved?
-Addition of lime can ↓ acidity in spoil, eg where sulfides in spoil make sulfuric acid
-Spoil is rarely too alkaline to support plant growth
-Old steel works can leave alkaline waste, can be valuable for uncommon plants, eg cowslips
Solid wastes- management of spoil heaps; why and how does the problem of contamination in spoil heaps need to be solved?
-Phytoremediation can be used where plants are used for absorption & storage of pollutants like heavy metal mercury
-Petrochemical waste like oil can be treated by bioremediation; certain species of bacteria will digest oil if appropriate conditions of temp, water supply & aeration are maintained
Solid wastes- management of spoil heaps; why and how does the problem of topography in spoil heaps need to be solved?
-Spoil heaps can be unattractive w/ steep slopes & angular shapes
-Landscaping can be used to reshape heap, but may require more land
Solid wastes- management of spoil heaps; why and how does the problem of toxic leachates in spoil heaps need to be solved?
-Should be collected & treated to prevent them entering water courses
-Deeper layers of soil should be applied in restoration so plant roots can’t reach layer containing toxic materials
-Could bring toxins to surface & cause their dispersal into wider environment
Solid wastes- management of spoil heaps; why and how does the problem of heavy metals in spoil heaps need to be solved?
-Problem when are mobile in environment
-Can be inhaled/ingested in food or water
-This can be prevented by disposing of them in solid form under alkaline conditions → means metals should remain insoluble as solubility is usually ↓ w/↑ pH
-To prevent dust particles, heavy metals should be covered so they can’t become airborne
Solid wastes- management of spoil heaps; why and how does the problem of flammable wastes in spoil heaps need to be solved?
-Coal/shale oil production spoil can have ↑ proportions of hydrocarbons which can result in spontaneous combustion within heap
-Can be ↓w/ regular layers of fine-grained material to ↓ air flow
Solid wastes; what does incineration involve?
Destruction of wastes by high temp oxidation
Solid wastes; what are the advantages of incineration?
-Vol of ash made is much less than OG waste
-Heat made may be used for district heating generation of electricity
-No sorting/complicated management needed
-Flammable materials like plastics & dirty paper can be separated & burnt in purpose-built power stations/used for industrial heat like cement manufacture. Large # of single flammable waste can be used to make fuel for specific purposes
Solid wastes; what are the disadvantages of incineration?
-Resource value of recyclable materials is lost
-Toxic dioxins may be produced by reaction of organic wastes & chlorine
-Fuel used to maintain combustion of wet/non-flammable wastes is expensive
-Wastes may need to be separated to remove wet wastes,↑ processing costs
-Treatment of atmospheric pollutants in effluent gases ↑ costs
Solid wastes; what are features of good domestic waste incinerators?
-Recyclable wastes removed before incineration
-Wastes w/ ↑ water content are removed, eg compostable wastes
-Combustion temp kept high & waste gases cooled rapidly to ↓ dioxin production
-Heat made harnessed for use
-Atmospheric pollution controlled; SO2, NOx, HCl, CO, smoke, PM10
-Flammable organic wastes may be chemically broken down by incineration. Hydrocarbon component of molecule will be converted to CO² & water. Aren’t serious issues as will be made in small quantities, compared w/ other sources like vehicle fuel use
-Some materials made in process may need additional treatment
-Heavy metals can be removed by scrubbing then stored in solid form at high pH, making them insoluble & ↓ mobile
Solid wastes; what are specialist wastes and how should they be treated?
-If highly hazardous wastes → released into environment, they’ll cause serious pollution
-Specialist storage/treatment techniques likely to be required to avoid such pollution
-Diff techniques used for diff types of hazardous wastes
Solid wastes- specialist wastes; how is asbestos dangerous?
-Is dangerous if disintegrates & fibres become airborne so can be inhaled
-Fibres can cause irritation, lead to asbestosis
-Scar tissue made in lungs thickens alveoli so gaseous exchange ↓& breathing becomes more difficult
-Can cause particular type of cancer; mesothelioma, cancer of tissue covering many internal organs like lungs
-Can take decades to develop but isn’t usually difficult to identify cause as 80%+ mesothelioma cases are caused by asbestos
Solid wastes- specialist wastes; what has asbestos been used for and how can it be made less dangerous?
-Has been used to strengthen cement roof panels
-Also found in textured ceilings coverings
-As long as its encapsulated, remains intact; isn’t dangerous
-Asbestos wastes require special handling
-Need to be double wrapped in heavy-duty polythene bags in specialised landfill site where waste contents are recorded
Solid wastes- specialist wastes; what are cyanide compounds and what are they used for?
-Cyanide compounds include x3 bonds betw C & N atoms
-4th bond links C atom to element like hydrogen/sodium
-Compounds used in manufacture of paper, textiles, plastics
-Electroplating, metal cleaning, gold extraction all use salts of cyanide
Solid wastes- specialist wastes; how can cyanide wastes be dangerously and how can this be prevented?
-Can be v toxic enzyme exhibitors, may be inhaled/ingested
-Incineration= safest way to dispose of cyanide wastes so carbon & nitrogen are separated & oxidised
-CO² & NOx made are much smaller pollution issues
Solid wastes- specialist wastes; what is encapsulation and vitrification used for and why?
Some wastes= so hazardous they must be stored using method where they become immobile & couldn’t leak out in future
Solid wastes- specialist wastes; what does encapsulation involve?
-Hazardous wastes w/ heavy metals, eg arsenic, mercury, nickel, chromium residues & intermediate level radioactive waste are mixed w/ cement slurry; poured into containers made of impermeable & unreactive material
-Solid cement encapsulates waste so is immobilised
Solid wastes- specialist wastes; what does vitrification involve?
-Specialist encapsulation technique used for storage of high-level radioactive waste that’s been extracted from used nuclear fuel
-Powdered radioactive waste is mixed w/ molten glass, poured into stainless steel containers, then sealed
-Glass solidifies encapsulating waste
-Even if glass shattered, waste would remain encapsulated in fragments
-Steel containers are placed in cylindrical passages inside concrete building
-Passages are ventilated to remove heat generated within waste
What is noise and how can its pollution have impacts?
-Sound that’s unwanted as is disturbing/causes damage
-Has limited impact on wildlife & ability of Earth to sustain life, but can have serious impacts on human quality of life & health
Noise; what is the logarithmic dB scale used for and what do the categories represent?
-Human ear is sensitive to v wide range of sound power levels so logarithmic scale is used; the Bel, divided into 10 decibels
-↑in vol of 10dB represents x10 ↑in sound vol
-↑ of 3dB represents x2 in vol
-0dB doesn’t = no sound. It’s set at quietest sound that can be heard at 1000Hz, is called threshold of human hearing
Noise; how does the frequency range of human hearing vary and why?
-Sound vibrations passing through air —> detected in cochlea of inner ear by hair-like projections on sensitive nerve cells
-Each group of cells= sensitive to particular sound freq
-Typical range of hearing for young people is 20-20,000Hz. Older people generally have ↓ freq range, esp at ↑ frequencies & need ↑ vol for sounds to be detectable
-Exposure to excessive noise & some health issues can also ↓ sensitivity & range
Effects of noise on non-living objects; what is acoustic fatigue and how is it caused + prevention?
-Some objects have freq at which they’ll naturally vibrate; their natural resonant freq
-May eventually cause stress cracking & structural failure called ‘acoustic fatigue’
-This, in early aircraft jet engines, led to improved designs to prevent cracking in engine cowling
Effects of noise on non-living objects; how is vibration damage caused and what is its impact?
-Repetitive vibration can cause structural damage to buildings, bridges, underground pipes
-Can be caused by vibrations created by wheels of heavy vehicles
Effects of noise on non-living objects; how can shock impacts be caused and what are its effects?
Force of impact of sudden v loud noise can cause damage, eg ‘sonic boom’ of supersonic aircraft causing structural damage to buildings like broken windows & dislodged masonry
Effects of noise on living organisms (humans); how can hearing damaged by caused?
Usually caused by long-term occupational exposure to loud machinery, esp to ↑ freq sounds
Effects of noise on living organisms (humans); how can stress-related health problems be caused?
Long-term exposure to ↑ noise levels can cause ulcers, ↑ BP & heart disease
Effects of noise on living organisms (humans); how can behavioural changes be caused?
Can cause irritability, aggression, lack of concentration → may lead to accidents
Effects of noise on living organisms (humans); how can communication problems be caused?
-High background noise levels can make it hard to hear others talking
-Children in schools beneath airport flight paths may underperform educationally
Effects of noise on living organisms; how can livestock be affected?
Sudden noises like low-flying aircraft may cause animals to panic → injuries/breeding failure
Effects of noise on living organisms; how can breeding birds be disturbed?
-Birds singing to establish their territories/attract mates may have difficulties in urban areas due to background noise levels
-Birds scared by sudden noises may leave their nests, allowing predators to take eggs/chicks
-Cliff-nesting birds may knock eggs/chicks → sea if are frightened by low-flying aircraft
Effects of noise on living organisms; how can noise cause reduced feeding success?
Animals using hearing to find food, eg bats, owls, dolphins may not be able to find food as easily if there’s background noise
Effects of noise on living organisms; how can hearing damage/behavioural changes be caused?
-Cetaceans like whales & dolphins can be harmed by loud noises like military sonar used to detect submarines
-If are close to source of sonar, may suffer hearing damage
-Mass-strandings of cetaceans may be linked to use of sonar
Aircraft noise-military aircraft; when can this cause disruption?
-There are fewer than those of civil aircraft
-Most are away from urban areas so there’s limited annoyance to public in take-off & landing
-But, low-level training flights can cause annoyance over large areas
Aircraft noise-military aircraft; what are the ways low-level training flights can minimise noise nuisance issues?
-Major urban areas are avoided, unless close to airfield
-In UK → 13 major avoidance areas including major conurbations, civil airports, & certain key industrial + medical sites
-Flight paths varied
-UK is divided into 20 Low Flying Areas (min flying height 250ft) of which 3 are Tactical Training Areas (min flying height 100ft at specific limited times)
-It’s possible to request temporary stop to low flying, eg for agricultural/horse show
-Low flying timetables may be published when practical
-Compensation may be paid for damage caused to property/harm to wildlife
-Flights may avoid sensitive ecological sites like seabird cliff breeding colonies
Aircraft noise- civil aircraft; when can civil aircrafts cause noise nuisance + how is it also avoided?
-Civil airliners cruise at altitudes ↑ enough that little/no sound reaches ground, so noise nuisance is usually limited to area around airports where aircraft are close to ground
-Many airports = located close to urban areas to ↓ travel times to & from airport for passengers.↑ risk of noise causing annoyance in urban area
-Level of noise nuisance around airport → affected by timing & number of flights each day & by sound level produced by each aircraft
Aircraft noise; how is airport noise nuisance reduced via location?
-Location away from major population centres; to ↓ people affected
-Taxi areas away from residential areas; aircraft taxiing before take-off can ↑ noise levels for nearby residents. Layout of airport can separate taxi areas & residential areas
-Engine test areas; areas where engines are tested on ground at ↑ thrust are located away from residential area, only used during day, are surrounded by acoustic scrams
Aircraft noise; how is airport noise nuisance reduced via design?
-Acoustic insulation; buildings affected by aircraft noise may’ve free acoustic insulation provided, eg double glazing
-Land-use restrictions; near airports, eg allowing industry but not housing developments
-Noise deflection/absorption; baffle mounds & acoustic barriers can deflect/absorb noise trend airport
-Multiple landing runways; at busy airport w/ single runway for landing, aircraft may have to use noisy reverse thrusters to slow down so can get off runway before next aircraft arrives. Multiple runways allows more time to slow down, so wheel brakes can be used → quieter than reverse thrusters
Aircraft noise- engine design; how have high bypass-ratio engines been designed to reduce noise?
-Early jet engines had single cowling (tube) around jet w/ turbulent exhaust gases providing thrust but also creating a lot of noise
-Modern jet engines have second cowling & turbofan on front of jet forcing ‘bypass air’ around inner cowling
-Bypass air smooths flow of exhaust air,↓ noise levels
-Bypass-ratio = ratio of bypass air: jet exhaust gases, ↑ ratio = quieter engine
Aircraft noise- engine design; how have chevron nozzles been designed to reduce noise?
-Used on high bypass engines to make them even quieter
-Serrated trailing edge on outer cowling mixes bypass air w/ surrounding air more smoothly
Aircraft noise- engine design; how have engine hush kits been designed to reduce noise?
Work like chevron nozzles & can be fitted to low bypass ratio engines to make them quieter
Aircraft noise- engine design; how have engine acoustic liners been designed to reduce noise?
Used inside outer cowling & around inner cowling to absorb noise
Aircraft noise- aircraft body design; how have blended wing aircrafts been designed to reduce noise?
Engines can be located on top of aircraft so body acts as barrier, ↓ noise reaching ground
Aircraft noise- aircraft body design; how do examples of aerodynamic designs reduce noise?
-Fairings on undercarriage ↓ turbulence around wheels & leg struts
-Fairings covering wind flap hinges ↓ turbulence
-Riveted construction creates surface indentations, creating turbulence & noise. Welded panels create less turbulence
Aircraft noise- engine design; how have lighter aircrafts been designed to reduce noise?
-Using composite materials like carbon fibre makes aircraft lighter so less engine thrust is needed
-Eg; Airbus A380 uses lightweight composite materials for 25% of its structure. The newer A350 uses 53% composite materials
Aircraft noise- aircraft operation; how does the take-off angle reduce noise?
Aircraft are noisier when taking off than landing as engines are running at ↑ power & take-off angle = steeper to allow aircraft to climb rapidly to altitude where it can’t be heard on the ground
Aircraft noise- aircraft operation; how does the flight path planning reduce noise?
Flight path routes are planned to avoid densely populated areas whenever possible
Aircraft noise- aircraft operation; how does a constant descent angle reduce noise?
-Having one (usually 3°) for final descent before landing makes engine noise less intrusive
-There are no periods of ↑ thrust as there are w/ a stepped descent
-Steeper descent angle allows aircraft to stay at greater altitudes for longer, so ground-level noise = further ↓
Aircraft noise- aircraft operation; how do night flight restrictions reduce noise?
Most airports near large residential areas restrict # of night flights, esp take-offs
Control of noisier aircraft; how have noise limits been implemented to control aircraft noise pollution?
-Aircraft are categorised into groups according to whether they meet increasingly strict noise limits
-Older noisiest ‘chapter 2’ aircraft were banned from most major airports in 2002, when ‘chapter 3’ limits were introduced (15dB ↓ in max noise)
-All new aircraft since 2006 must meet ‘chapter 4’ noise limits (10dB lower than chapter 3). Chapter 3 aircraft are being phased out
-New regulations being introduced from 2017 will make noise regulations stricter w/ further 7dB ↓
Control of noisier aircraft; how have charges for noisier aircraft been implemented to control aircraft noise pollution?
-Aircraft pay charges for using airports
-At many airports charge is based on noise levels; at Heathrow, noisiest aircraft pay X10 as much as similar sized quiet aircraft
-Night flights cost nearly x3 as much as day flights
-There are fines for breaking flight noise limits
-Fines in 2015 were £500 per dB above limit for day flights & £4000 per dB above limit for night flights
Control of noisier aircraft; how have restricted flight times been implemented to control aircraft noise pollution?
-Airports near ↑ pop density areas often restrict/ban night flights
-Take-offs are controlled more than landings because they’re noisier
Control of noisier aircraft; how have quota count systems been implemented to control aircraft noise pollution?
-Airports may encourage airlines to operate quieter aircraft by restricting flight times for noisier aircraft/using points system
-System is used at Heathrow, Gatwick, Stansted airports, has been adapted for use at other airports
-Aircraft types are allocated points depending on their noise levels
-Each airline is allocated a certain # of points. Total point score of actual flights mustn’t exceed their allocation. It’s easier to keep within point total if new purchases are of quieter aircraft
Control of noisier aircraft; how has the control of supersonic flights been implemented to control aircraft noise pollution?
-There are no longer any supersonic civil airliners
-Concorde ceased commercial flights in 2003. It was banned from almost all airports & wasn’t allowed to fly supersonic over most countries
Railway noise; how is train noise from different sources controlled?
-Wheel vibration; track polishing, sound-absorbing ballast
-Engine noise; sound-absorbing suspension
-Pantograph turbulence; aerodynamic fairing
-Wheel squeal on corners; lubrication of wheels/track
-Braking squeal; use of composite material brakes
-Wheel noise; good carriage suspension
Road traffic noise; how is road noise from different sources controlled?
-Wheel noise; sound absorbing road materials like porous asphalt/asphalt w/ shredded rubber from old vehicle tyres
-Vehicle air turbulence; improved vehicle aerodynamics
-Engine noise; acoustic insulation around engine; quieter exhaust pipes
-General road vehicle noise; traffic may be rerouted to avoid more sensitive areas, traffic management to make free-flow of traffic ↓ louder noise made in acceleration, lenses, embankments, walls + dense tree planting to help absorb noise around roads, x2 glazing can ↓ noise levels within buildings
How is industrial noise impactful?
-Most is produced within industrial buildings so pollution is only likely to affect workers
-But, some industrial activities can affect public & wildlife
Industrial noise; how is industrial noise from different sources controlled?
-Air compressors & pumps; silencers to ↓ explosive expansion of air
-Stamping machines; use of alt process, eg pressing/moulding
-Metal conveyors (metal on metal contact); use of nylon bearings, wheels, rollers
-Mine blasting; regular timing to ↓ public concerns, battle mounds
-Pile-driving on land; drilling instead of pile-driving
-Pile driving at sea for foundations of bridges/wind turbines; air bubble curtains around pile driver absorb noise &↓ impact on dolphins & whales
-Marine seismic surveys & military sonar harming cetaceans; acoustic survey to detect cetaceans before use. ↑ noise activities = delayed if present. ↑ vol gradually so cetaceans can leave if present
Industrial noise; what are the general methods used to control industrial noise?
-Sound absorbing surfaces in room
-Sound absorbing materials around equipment; acoustic curtain
-Machinery placed on acoustic mat
-Sound absorbing materials as part of equipment
-Remote machinery operation
-Worker ear protection
What is domestic noise pollution mainly caused by?
-Domestic appliances like washing machines, music equipment, garden machinery, DIY power tools & barking dogs
-Aren’t technically complex but can have serious impacts on qualify of life
Domestic noise; what are the ways in which it can be controlled?
-Domestic appliances w/ acoustic absorbers, eg washing machines, vacuum cleaners
-Wearing ear defenders when using power tools
-Volume limiters on music equipment
-Selection of quieter domestic appliances → requires availability of good info to help in making choices
-Control of pet dogs
Measuring noise pollution; how is the loudness of sound measured
-Decibel scale; can be modified for specific applications
-Other scales derived from dB scale are used to give overall measure of how noise levels change over time/for events where loudness isn’t constant, eg aircraft takeoff
Measuring noise pollution; how has the dB scale been modified + how does this work?
-dB(A) scale is used for human hearing
-Takes into account sensitivity of human hearing by ‘weighting’ sounds betw 1000 & 4000Hz, as nerve cells in ear are more sensitive to sounds in this frequency range so are heard more easily
Measuring noise pollution; what are the ways in which road traffic noise levels can be measured?
-LA10; measures noise exceeded for 10% in any set period. It’s a good measure of noisiest periods
-LA90; measures noise level exceeded for 90% in any set period. It’s a good measure of quietest periods
-Traffic Noise Index (TNI); produces representative measure of traffic noise using LA10 & LA90
-L10 (18h); measure assumes traffic noise is only issue during 18h betw 6am & midnight. Noise level that’s exceeded during noisiest 10% of each of these 18hrs is measured. Mean of these is calculated
Measuring noise pollution; what are the ways in which aircraft noise levels are measured?
-Effective Perceived Noise Levels (EPNL); estimate of relative loudness of particular type of aircraft during takeoff, overflight & landing. Calculated from many observations, recorded at 450m to side of flight path
-Noise & Number Index (NNI); combines number of nights & noise levels of aircraft above 80dB as it’s presumed that aircraft ↓ that don’t cause serious annoyance. It’s been replaced w/ Leq 57dB
-Leq 57dB; leq= average sound level over particular period. For UK airports, average of 57 dB betw 7am & 11 pm in summer is used. Levels above this → considered annoying. Areas w/ noise ↑ this level will experience ‘significant community annoyance’
Ionising radiation; how does ionising radiation occur and what does it result in/from?
-Naturally occurring phenomenon which has been used in wide range of applications
-Presents threat to health & radioactive materials need to be managed
-Pollution due to radioactive materials has resulted from past nuclear weapon testing, nuclear waste disposal, accidents at nuclear power plants, transportation, processing & storage of radioactive materials
Ionising radiation; how are radioactive materials and ionising radiation used in industry?
-Measuring thickness of rolled metals & paper
-Testing aircraft jet engine turbines
-Strengthening polymers. Radiation can= cross-links in molecules. Used to improve properties of latex rubber for surgical gloves, balloons used in heart surgery & vehicle tyres
-Oil & gas exploration to test rock porosity
Ionising radiation; how are radioactive materials and ionising radiation used in healthcare?
-Sterilising heat-sensitive surgical equipment
-Cancer treatment
-X-ray photography & CT scans
Ionising radiation; how are radioactive materials and ionising radiation used in agriculture?
-Pest control; stored food sterilisation
-Sterile male insect pest control
-Production of mutations in crop breeding programmes
Ionising radiation; how are radioactive materials and ionising radiation used in scientific research?
Radio-labelled tracers to track movement of materials within organisms/environment
Ionising radiation; how are radioactive materials and ionising radiation used in nuclear fission/fusion?
-Nuclear weapons use nuclear fission & fusion. About 500 nuclear test explosions took place in atmosphere up to 1980
-Nuclear electricity; fission using uranium & plutonium is used in nuclear reactors to generate electricity
-Ship propulsion; ↑ energy density of nuclear fuel means ships propelled by nuclear reactors rarely need to be refuelled & don’t need air for combustion; very useful in submarines
Ionising radiation; why can analysing the risk & benefits of using ionising radiation be difficult?
-Symptoms may take long time to develop, esp those due to chronic exposure to ↓ doses
-Some effects of exposure to ionising radiation may be hard to identify as may be alternative causes of same symptoms
-Accurate data on impacts on human often not available
-Accurate data on exposure often not available after accidental releases
People who benefit from use of ionising radiation & those who take risks may not be in the some place, eg people who benefit from nuclear electricity may live in diff countries from miners extracting uranium fuel used in power station
-Risks associated w/ using radioactive materials may be offset by ↓ of other risks, eg of using X-ray photography must be offset by ↓ risks of invasive surgery
Ionising radiation; what are natural and human activity sources of radiation exposure?
-Natural; cosmic radiation from sun, gamma rays from lithosphere, internal sources in body, radon from ground
-Human; medical/occupational exposure, weapons fallout, consumer products, industrial effluent discharges
Ionising radiation- natural sources; how is cosmic radiation produced?
-Large amounts of charged sub-atomic particles are released by natural processes occurring in the Sun
-When particles reach Earth’s atmosphere they’re absorbed, releasing high-energy electromagnetic radiation, including gamma rays
Ionising radiation- natural sources; how can radiation be released internally in the body?
-Activation products from upper atmosphere & radioisotopes from ground can enter body via food & water/by been inhaled
-Can decay inside body- release radiation
Ionising radiation- natural sources; how can radon in the ground cause radiation exposure?
-When radioisotopes in underground rocks decay, radiation is usually absorbed by nearby rocks
-When some uranium atoms decay, gaseous radionuclide is made
-Radon= unstable, makes alpha radiation → travels up cracks in overlying rocks & escapes into atmosphere. Can pass through foundations of buildings above uranium-bearing rocks & become conc inside buildings
-Some parts of UK, Devon & Cornwall, have relatively ↑ radon levels as result of underground rocks here
-Ventilating building foundations can be used to blow out radon before entered building
Ionising radiation- human activities; How can radiation exposure occur in medical procedures?
Ionising radiation is used in many medical procedures, have benefits but also risks. Risk:benefit analysis should be made. Medical procedures incl;
-X-ray photography for info about inside of body, eg broken bones
-X-ray radiography, after injecting radio-opaque dyes, can be used to find blockages like kidney stones
-High doses of radiation can kill cancerous tissue
-Use of radio-labelled substances to track passage of substance in body & assess blockages
Ionising radiation- human activities; how can occupation result in radiation exposure?
Working in many industries can ↑ exposure to radiation, including;
-Nuclear electricity generation
-Manufacturing industry making items w/ radioactive materials
-Mining
-Medical radiographers & radiologists
-Dentists & dental technicians
-Workers using radioactive sources to test thickness of paper/steel
-Research scientists using radio-labelled tracer substances
-Aircraft flight crews
Ionising radiation- human activities; how can atomic weapon fallout cause radiation exposure?
-Atmospheric testing & use of nuclear explosives released radioactive material → was carried by winds & contaminated all parts of Earth’s surface although degree of contamination varied greatly
-No nuclear weapon tests have been conducted in atmosphere since 1980
Ionising radiation- human activities; how can consumer products cause radiation exposure?
-Common consumer products like smoke detectors & some camping gas mantles, containing radionuclides
-Small amounts of radioactive materials may be present in ceramics, granite worktops, fertilisers; result in small increased dose in public
Ionising radiation- human activities; how can industrial discharges cause radiation & how can this be reduced?
-Most industries using radionuclides release some radioactive wastes into environment
-Majority comes from nuclear electricity generation & nuclear weapons manufacture
-Improved processes, eg use of filters on gaseous emissions & ion-exchange sands in liquid releases, have reduced amount of radioactive materials released
Ionising radiation; what kind of radiation exposure cannot be avoided and where can this be found?
-Background radiation
-Sun, rocks, food
Ionising radiation; what is the effect of ionising radiation determined by and some examples of this?
-Properties of different types of ionising radiation
-Eg; power to penetrate other materials, distance they can travel, ease w/ which they can be absorbed
Ionising radiation; how does penetrating power impact ionising radiation and its effects?
-Ionising radiation w/ poor penetrating power is more easily absorbed; workers can be protected relatively easily
-But, if ionising radiation penetrates living cells then energy from a less penetrating type will be absorbed in smaller amount of tissue & can cause more serious local damage
Ionising radiation; what is Relative Biological Effectiveness (RBE) and what does a higher measure of it mean?
-Measure of comparative effects of diff types of ionising radiation on living tissues
-More damaging forms of radiation have higher RBEs
Types of ionising radiation; what are the properties and health risks of alpha radiation?
-Very easily absorbed & travels short distances
-RBE of 20
Health risks;
-Particles are absorbed by clothing & dead skin so alpha emitters outside body are usually safe
-Ingested alpha emitters are very dangerous as particles are all absorbed in smaller amount mass of tissue, creating more conc damage & increasing risk of free radical interactions
Types of ionising radiation; what are the properties and health risks of beta radiation?
-Moderately easily absorbed & travels medium distances
-RBE of 1
Health risks;
-Moderately dangerous
-Sources near to body still pose risk
Types of ionising radiation; what are the properties and health risks of gamma and x rays?
-Not easily absorbed & travel long distances
-RBE of 1
Health risks;
-Lower danger
-Longer distance of travel= distant sources still risk
Types of ionising radiation; what are the properties and health risks of ionising radiation neutrons?
-Moderately easily absorbed & travel medium distances
-RBE of 2-10
Health risks;
-V dangerous
-Still pose risk after being absorbed
-Some atoms are changed when bombarded by neutrons so become activation products
-Stable nucleus becomes radionuclide when bombarded by neutrons, may later decay & release ionising radiation
Ionising radiation; what determines how far ionising radiation travels?
-The density of the material through which it passes
-The denser the material, the more easily the radiation will be absorbed by material
Ionising radiation; what is half-life & what does it represent?
-All atoms of an unstable isotope have same probability of decaying during specific time period
-Likelihood of atom decaying isn’t affected by # of atoms present
-For mass of individual isotope, there’s a predictable rate at which atoms will spontaneously decay & emit ionising radiation
-Rate is usually expressed as its half-life; length it takes for 1/2 of original isotope to decay. If mass is observed for several half-lives then remaining proportion will be 1/2, 1/4, 1/8, 1/16, 1/32, etc of OG amount
Ionising radiation; how does half-life of isotope influence the health risks?
-Isotopes w/ short half-lives release all radiation quickly. Are dangerous but don’t pose danger for long. So, short-term precautions may be sufficient to protect workers & public
-Isotopes w/ long half-lives pose danger for a long time. Emit small amounts of radiation in any given time period so level of danger may be quite low
-Isotopes w/ half-lives of several decades generate concern as rate of radiation release is quite high. People can be exposed for most/all of their lives & short-term protection measures are inadequate
Ionising radiation; how does ionising radiation affect living tissue?
-When it’s absorbed by living tissue, unusual ions; ‘free radicals’ are made
-They have unpaired electrons, are highly reactive & can cause biologically damaging reactions
-Most common molecule in cells → water, so it’s most likely to be affected by radiation
-Free radicals made are often short lived but may make more stable molecules which can cause damage within cell
Effects of ionising radiation on living tissue; how can damage to the nucleus of the cell due to ionising radiation be observed and when is it likely?
-Most likely to be observed as it affects existing cell & all future cells made from its chromosomes when it divides
-Such change in DNA = mutation
-Rapidly dividing cells like skin & gut are more easily affected as cells are more genetically active
Effects of ionising radiation on living tissue; how can ionising radiation cause damage to other parts of the cell, how can this be minimal?
-May mean cell can’t function properly & may die
-↓ levels of damage may cause no long-term effects as intact nucleus can co-ordinate repair of damage
Effects of ionising radiation on living tissue; what are somatic and gonadic effects?
-Somatic; damage to general body cells & organs
-Gonadic; damage to cells in ovaries/testes
Effects of ionising radiation on living tissue; what are chronic and acute effects + example?
-Chronic; effects appearing slowly & in proportion to radiation doses received
-Acute; collection of health effects appearing quickly. If radiation is received over shorter period, more damage is likely as may be more damaging free-radical interactions & cells have ↓ time to repair themselves. If person receives v large doses of radiation, eg in nuclear power accident, impact will be severe & can cause rapid death as result of damage to bone marrow, immune system & gut → haemorrhage & blood leas
Ionising radiation; what is exposure and contamination?
-Exposure; involves absorption of ionising radiation. For it to occur, person must be close enough to source for radiation to reach them
-Contamination; physically carrying radioactive materials which, when releasing radiation, may cause exposure. If someone’s contaminated, exposure will continue as long as they carry source on/in them
-Sealed ionising radiation sources inside a container may expose people nearby to radiation but can’t become contaminated
Ionising radiation; what are activation products, how do they work & where are they found?
-Exposure to most types of radiation doesn’t cause material that absorbs it to become radioactive as nuclei are unaltered
-But, exposure to neutrons can cause previously stable nuclei to become radioactive as absorption of neutron will convert it → new isotope
-Activation products = most often found in structures of nuclear reactors
Control of exposure to ionising radiation; what are the two basic principles for managing safety & radioactive materials + explain?
-ALARA; situation should be managed such that exposure should be ‘As Low As Reasonably Achievable’ (ALARA)
-BATNEEC; ↓ exposure can be achieved by using ‘Best Available Technology Not Entailing Excessive Cost’ (BATNEEC). Assessment of ‘excessive cost’ depends upon level of risk & ease w/ which adequate safety can be achieved
Control of exposure to ionising radiation- strategies; how can closed sources reduce radiation exposure + what can be done if this isn’t possible?
-Prevent workers from coming into direct contact w/ source by enclosing radioactive source in container
-Workers aren’t contaminated by picking up radioactive material which would’ve continued their exposure when they moved away from that location
-Closed source of alpha-emitters may ↓ exposure to 0 as container will probably absorb all radiation
-Remote handling techniques can be used to ↓ contamination. If source can’t be enclosed, worker can wear sealed suit w/ separate air source
Control of exposure to ionising radiation- strategies; how can materials absorbing radiation reduce exposure + what affects type of material used?
-If possible, materials should be used as barriers to prevent radiation from reaching workers
-Choice & thickness of material used will depend upon type of radiation involved & space available
Control of exposure to ionising radiation- strategies; how can protective clothing be used to reduce radiation exposure?
Can be used to minimise contamination
Control of exposure to ionising radiation- strategies; how does distance from the source reduce radiation exposure?
-Radiation follows Inverse Square Law so when distance from source is ↑, there’s more than proportional drop in exposure
-So, x2 distance from source ↓ exposure to 1/4 of previous level
-Dose received= 1/Distance
Control of exposure to ionising radiation- strategies; how does reducing the period of exposure reduce radiation exposure?
Working arrangements should ↓ time worker is close to source
Control of exposure to ionising radiation- strategies; how does decontamination reduce radiation exposure?
-Washing, scrubbing & exfoliating scrubs removes surface contamination
-Swallowing stable potassium iodide tablets prevents uptake of radioactive iodine
Ionising radiation- good waste management; what are the origins and storage methods of high level waste?
-Origin; used uranium fuel rods: split nuclei form highly radioactive isotopes
Storage method;
-Vitrification: dried powdered solid waste mixed w/ molten glass & allowed to solidify in stainless steel containers, surrounded by concrete to absorb radiation. Air cooling removes heat of radioactive decay
-In the UK its stored at Sellafield, Cumbria
Ionising radiation- good waste management; what are the origins and storage methods of intermediate level waste?
-Origins; metal tubes surrounding fuel rods become radioactive in reactor, filters from waste processing
-Storage method; mixed w/ cement & stored in stainless steel drums. In the UK it’s stored at Sellafield
Ionising radiation- good waste management; what are the origins and storage methods of low level waste (solid)?
-Origins; general equipment & clothing that became contaminated by coming in contact w/ radioactive material
-Storage method; sealed in thick polythene bags, inside steel drums/steel truck containers in a concrete-lined landfill site. In the UK, its stored at Drigg near Sellafield
Ionising radiation- good waste management; what are the origins and storage methods of low level waste (liquid)?
-Origin; waste solutions from used fuel reprocessing & storage
-Storage method; filtered, including ion exchange, then discharged
Ionising radiation- good waste management; what are the origins and storage methods of low level waste (gas)?
-Origin; gases released from used fuel during storage & reprocessing
-Storage methods; filtered then released
Ionising radiation- good waste management; what are the origins and storage methods of low level waste (gas)?
-Origin; gases released from used fuel during storage & reprocessing
-Storage methods; filtered then released
Monitoring radioactive materials; what are the units used to measure ionising radiation?
-Becquerel to measure the activity of the source
-The Gray to measure absorbed dose; 1 Gy = absorption of 1 joule of radiation energy/ kg of matter
-The Sievert to measure effective dose that allows for differing effects of diff types of radiation
-N°. of Sieverts= N° of Grays x a radiation weighting factor for type of radiation. Weighting factor for alpha radiation → 20 for gamma & beta radiation is 1
Monitoring radioactive materials; what are the range of radiation monitors used for workers?
-Personal dosemeters which give reading of current exposure
-Photographic film badges, measure long-term measure exposure
-Air monitors to detect atmospheric particles, incl alpha-emitters
-Contamination monitors, monitor workers as they leave premises & detect any contamination
Monitoring radioactive materials; what does Critical Pathway Analysis (CPA) identify, allow and why?
-Normal discharges from nuclear establishments release v small # of radioactive materials
-But, it can’t be assumed they’ll be dispersed & diluted so that risks ↓ to insignificant level. It’s possible that natural processes may conc them in locations where they could be hazardous
-CPA identifies possible environmental routes radioactive materials may take in environment after release → analysis makes it possible to prefect where discharges could cause issues by becoming more conc
Monitoring radioactive materials; what factors does CPA involve?
-Physical state of effluent; solid/liquid/gas/solution
-Density
-Meteorological conditions that determine atmospheric dispersion incl wind speed & direction
-River flow & ocean currents
-Physical nature of environment, including geology; porous/permeable, vegetation cover
-Effect of pH & O² availability on solubility
-Bioaccumulation & food-chain conc
-Food sources & consumption by local people
-Half-lives & isotopes involved
Monitoring radioactive materials; what is Critical Group Monitoring (CGM) and what does it comprise of?
-If there’s a concern about radioactive contamination, it’s important to determine level of risk to people; most effectively by reviewing risk to the Critical Group
-Comprised of members of public most at risk due to where they live/where their water comes from/what they eat/what they do in their spare time/where they work. Doesn’t include occupational workers, monitored in other ways
-If group is safe, all other public members should be safe
Monitoring radioactive materials; what are the factors considered in identifying the critical group?
-Where individuals live in relation to source
-Time spent outside, eg farmers, dog walkers, anglers, walkers
-Sources of food, eg local food; milk, seafood, vegetables
-Source of water, eg local well
Monitoring radioactive materials; why is environmental monitoring undertaken and what does it assume?
-If places in environment where radioactive materials are likely to be most conc are identified & monitored + its established levels are acceptable, its assumed everywhere else is safe
-But, its important to recognise this assumes pathways have been predicted correctly
Monitoring radioactive materials; what should be assessed in environmental monitoring and why?
-Atmospheric dust, soil, water, grass, milk, meat, fish & vegetables
-As are materials most likely to be contaminated & those indicating direct risk to humans
