Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA A-Level Environmental Science > Pollution (AS) > Flashcards

Pollution (AS) Flashcards

1
Q

What is pollution and what is it usually caused by?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do the properties of pollutants determine?

A

-Length of time it may cause a problem
-Level of harm it can cause
-Where, how for it may travel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Properties of pollutants; how does the state of matter affect a pollutant?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Properties of pollutants; how does energy form affect a pollutant?

A

The different pollutants that are energy forms like noise, heat, ionising radiation or light have widely varying impacts due to way energy behaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Properties of pollutants; how does density affect a pollutant?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Properties of pollutants; what is persistence, how is it measured + why is this not precise?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Properties of pollutants; what are examples of pollutants with high & low persistences?

A

-High= CFCs, organochlorine insecticides like DDT
-Low= sewage, pyrethroid insecticides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Properties of pollutants; what is the process of pollutant breakdown and how is it categorised?

A

-Degradation
-Categorised according to feature causing breakdown;
-Biodegradation: caused by living organisms, usually bacteria
-Photodegradation: caused by light
-Thermal degradation: caused by heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Properties of pollutants; what is toxicity and how is harm usually caused?

A

-Measure of how poisonous a substance to living organisms
-Harm usually caused by damage to proteins, especially inhibition of enzyme action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Properties of pollutants; what are examples of toxic pollutants and their actions?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Properties of pollutants; why is specificity used for and how does it affect pollutants? + eg

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Properties of pollutants; how does reactivity affect pollutants?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Properties of pollutants; what are primary and secondary pollutants?

A

Primary - released by human activities
Secondary - produced by chemical reactions between one or more primary pollutants, often w/ non-pollutants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Properties of pollutants; what is adsorption and how does this affect the pollutant?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Properties of pollutants; how does solubility in lipids/water affect pollutants?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Properties of pollutants; what is bioaccumulation and what does this involve?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Properties of pollutants; what is biomagnification and what does it involve?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Properties of pollutants; what is synergism and what does it involve?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Properties of pollutants; what is mutagenic action?

A

Mutagens= agents causing changes in chemical structure of DNA by damaging chromosomes by rearrangement of DNA structure. Changes are known as mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Properties of pollutants; mutagenic action- what are gonadic and somatic effects?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Properties of pollutants; mutagenic action- what are examples of mutagenic pollutants?

A

-Ionizing radiation
-UV light
-Chlorinated organic substances, eg PCBs, dioxins
-Cadmium
-Asbestos

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Properties of pollutants; mutagenic action- what is carcinogenic and teratogenic action?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Properties of pollutants; what is mobility and how does it affect a pollutant?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Properties of pollutants; what are examples of pollutants with different degrees of mobility?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Features affecting degradation of pollutants; how does temperature affect this?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Features affecting degradation of pollutants; how do light Ievels affect this?

A

Light can provide activation energy driving chemical reactions involving pollutants like photochemical smogs & photodegradation of some pesticides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Features affecting degradation of pollutants; how does oxygen affect this?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Features affecting degradation of pollutants; how does pH affect this?

A

-Can affect solubility of substances
-Many heavy metals like lead are more soluble and so mobile under more acidic conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Features affecting degradation of pollutants; how do pollutant interactions affect this?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Factors affecting dispersal of pollutants; how do wind & water currents affect this?

A

Velocity & direction of air + water currents will affect how for pollutant is dispersed, also how much it’s diluted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Factors affecting dispersal of pollutants; how do temperature inversions affect this?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Factors affecting dispersal of pollutants; what are the factors allowing temperature inversions to form?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Factors affecting dispersal of pollutants; how does the presence of adsorbent materials affect this?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

General strategies to control pollution; what is the purpose of the Critical Pathway Analysis (CPA)?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

General strategies to control pollution; what are the factors that may be included in Critical Pathway Analysis (CPA)?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

General strategies to control pollution; what is Critical Group Monitoring (CGM) and what does it assess?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Emission control strategies; what environmental factors affect the dispersal of pollutants?

A

-Air quality
-Meteorological conditions
-Hydrology
-Emission source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Emission control strategies; why and how can emission location be controlled?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Emission control strategies; why and how can emission timing be controlled?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Principles of pollution control; what is the polluter pays principle?

A

-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 ↑

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Principles of pollution control; what is the precautionary principle and why is it advantageous?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Principles of pollution control; what are examples of pollution control methods?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Principles of pollution control; how is efficiency of pollution control maintained?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Atmospheric pollution; how do atmospheric pollutants often behave differently to those from water/ground?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Smoke and smoke smogs; what is smoke made up of and how is it categorised?

A

-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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Smoke and smoke smogs; what toxic chemicals can be found in smoke?

A

Fluorides, aluminium, lead, acids & organic compounds like phenol

47
Q

Smoke and smoke smogs; what can smoke act synergistically with?

A

Other atmospheric pollutants like sulfur dioxide

48
Q

Smoke and smoke smogs; what are the main sources of smoke and why is this significant?

A

-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

49
Q

Smoke and smoke smogs; what are the effects of smoke pollution on humans?

A

-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

50
Q

Smoke and smoke smogs; what are the effects of smoke pollution on other living organisms?

A

-↓ photosynthesis as smoke blocks
-Substances in smoke particles may be toxic, eg heavy metals & acids

51
Q

Smoke and smoke smogs; what are the effects of smoke pollution on non-living objects?

A

-Smoke particles can damage buildings due to acids & organic solvents they may contain
-Cleaning dirty buildings → expensive

52
Q

Smoke and smoke smogs; what are the effects of smoke pollution on the climate?

A

-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

53
Q

Smoke and smoke smogs; what are the effects of smoke pollution on the stratosphere/atmosphere?

A

-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

54
Q

Smoke and smoke smogs; how is smog formed and what are its features?

A

-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

55
Q

Smoke and smoke smogs; how was the London smog of 1952 caused and what were its impacts?

A

-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

56
Q

Smoke and smoke smogs; what legislation was put in place as a smoke pollution control measure?

A

Clean air act (1956) restricted use of fuels producing smoke in large urban areas of UK

57
Q

Smoke and smoke smogs; how can domestic sources be smoke pollution control measures?

A

↑ use of fuels not producing smoke, eg natural gas & electricity

58
Q

Smoke and smoke smogs; how can transport sources be smoke pollution control measures?

A

Diesel Particulate Filters (DPF) fitted in exhaust pipes of diesel engines trap up to 80% of smoke particles

59
Q

Smoke and smoke smogs; industrial sources- how can electrostatic precipitators be control measures for smoke pollution?

A

-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

60
Q

Smoke and smoke smogs; industrial sources- how can cyclone separators be used as smoke pollution control measures?

A

-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

61
Q

Smoke and smoke smogs; industrial sources- how can scrubbers be used as smoke pollution control measures?

A

Uses fine water spray to wash out suspended solid particulate matter & dissolve soluble gaseous pollutants

62
Q

Smoke and smoke smogs; industrial sources- how can coal treatment be used as smoke pollution control methods?

A

Heating coal allows tar causing smoke production to be drained off → produces smokeless coal

63
Q

Smoke and smoke smogs; industrial sources- how can bag filters be used as smoke pollution control measures?

A

Remove smoke particles from effluent gases by trapping them on fabric titter

64
Q

Smoke and smoke smogs; what are examples of more efficient combustion technologies and how are they smoke pollution control measures?

A

-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

65
Q

Photochemical smog; why is the word ‘smog’ here misleading but also not?

A

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

66
Q

Photochemical smog; what are the pollutants involved in photochemical smog?

A

Wide variety of reactions betw primary & secondary pollutants, in presence of sunlight, including UV light

67
Q

Photochemical smogs; what are the sources of primary pollutants in photochemical smog?

A

-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)

68
Q

Photochemical pollutant effects; what are the effects of NOx?

A

↑ risk of respiratory infections like colds, flu, bronchitis. Can also make existing health issues worse like asthma and heart disease

69
Q

Photochemical pollutant effects; what are the effects of PANs (peroxyacyl nitrates)?

A

-Are toxic at conc much ↓ than those at which NOx become toxic
-Can cause eye irritation, breathing difficulties, asthma, emphysema & ↑risk of heart attacks

70
Q

Photochemical pollutant effects; what are the effects of tropospheric ozone?

A

-Contributes to production of PANs but is also toxic itself; cause asthma, bronchitis & heart disease

71
Q

Photochemical smog; what cities are more prone to photochemical smogs and why?

A

-LA, Mexico City, Paris, Beijing, Athens
-Due to topography
-Where traffic congestion is more severe, climate is sunny & temp inversions common

72
Q

Control of photochemical smogs; how can both NOx and hydrocarbons be controlled?

A

Using catalysts like platinum & palladium in exhaust pipe catalytic converters

73
Q

Control of photochemical smogs; how are catalytic converters used?

A

-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

74
Q

Control of photochemical smogs; how can unborn hydrocarbons be controlled?

A

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

75
Q

Control of photochemical smogs; why does the control of primary pollutants also guarantee this for secondary pollutants?

A

The reactants won’t be present for them to be formed

76
Q

What is acid rain and how is it formed?

A

-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

77
Q

Acid rain; what are the pollutant gases involved in acid rain?

A

-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

78
Q

Acid rain; what are the sources of the pollutant gases involved in acid rain?

A

-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

79
Q

Acid rain; what are the effects of acid rain on non-living things?

A

-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

80
Q

Acid rain; what are the direct effects of acid rain on living organisms?

A

-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

81
Q

Acid rain; what are the indirect effects of acid rain on living organisms?

A

-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

82
Q

What are the environmental factors that affect the severity of acid rain?

A

-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

83
Q

Control of acid rain- oxides of Sulfur; how is natural gas desulfurised?

A

-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

84
Q

Control of acid rain- oxides of Sulfur; how is crude oil desulfurised?

A

Sulfur compounds are removed from crude oil during distillation using molybdenum catalysts in process of hydrodesulfurisation

85
Q

Control of acid rain- oxides of Sulfur; how is coal desulfurised?

A

-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

86
Q

Control of acid rain- oxides of Sulfur; how is dry flue-gas (FGD) desulfurised? + what are products used for?

A

-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

87
Q

Control of acid rain- oxides of Sulfur; how is wet flue-gas (FGD) desulfurised? + what are products used for

A

-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

88
Q

Control of acid rain- oxides of nitrogen; how is low temperature combustion used?

A

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

89
Q

Control of acid rain- oxides of nitrogen; how are catalytic converters used?

A

Chamber in exhaust pipes contain catalyst like platinum; chemically reduces NOx back to N² & O² gas

90
Q

Control of acid rain- oxides of nitrogen; how are urea sprays used?

A

NOx can be removed by reacting it w/ urea

91
Q

Tropospheric ozone; what is the difference between stratospheric and tropospheric ozone?

A

-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

92
Q

Tropospheric ozone; what are the effects of tropospheric ozone?

A

-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

93
Q

Tropospheric ozone; what are the sources of tropospheric ozone?

A

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

94
Q

Tropospheric ozone; how can tropospheric ozone be controlled?

A

-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

95
Q

Carbon monoxide; when is carbon monoxide (CO) produced?

A

When carbon-based materials are burned w/ shortage of oxygen, eg incomplete combustion of hydrocarbons, esp petrol & diesel in vehicle designs

96
Q

Carbon monoxide; what are the effects of CO?

A

-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

97
Q

Carbon monoxide; how can CO be controlled?

A

-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

98
Q

Water pollution; what factors affect the concentration of pollutants?

A

-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

99
Q

Water pollution; what are the factors that affect dilution?

A

-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

100
Q

Water pollution; what is degradation/biodegradation?

A

-The process by which substances are broken down
-Involves both biotic & abiotic factors
-Biodegradation involves microorganisms, while physical processes include chemical & photochemical reactions

101
Q

Water pollution; what are the factors which affect degradation?

A

-↑ 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)

102
Q

Water pollution; how does removal rate affect the pollutant?

A

-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

103
Q

Water pollution; what is dispersal and how does this affect the pollutant?

A

-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

104
Q

Water pollution; what are examples of water bodies likely to be polluted and the cause?

A

-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

105
Q

Thermal pollution; what is the source of thermal pollution?

A

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

106
Q

Thermal pollution; what are the ecological effects of thermal pollution?

A

-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

107
Q

Thermal pollution; what are the physiological changes that thermal pollution causes?

A

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 ↓

108
Q

Thermal pollution; how can thermal pollution be controlled?

A

-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

109
Q

Thermal pollution; control of thermal pollution- how do cooling towers work?

A

-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

110
Q

Oil pollution- causes; how does waste lubricating oil cause oil pollution?

A

-Vehicle engine lubricating oil which leaks/is deliberately discarded into environment
-Industrial machine oil; washed into drains/mixed w/ other effluents

111
Q

Oil pollution- causes; how do accidental releases cause oil pollution?

A

-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

112
Q

Oil pollution- causes; how does oil exploration cause oil pollution?

A

-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

113
Q

TBC effects of oil pollution p258

A

AQA A-Level Environmental Science (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions