Pollution Flashcards

Question

How environmental features affect the severity of pollution- Factors that affect dispersal- how does the velocity (speed) of air currents affect dispersal?

Answer 1

- determines distance travelled - higher velocity, increases mobility, pollutant gases would move further, increasing dispersal range and possible area

Answer 2

surface currents in the ocean are driven by global wind systems that are fuelled by energy from the sun, patterns of surface currents are determined by wind direction, Coriolis forces from the earth's rotation, and the position of landforms that interact with the currents - the earths rotation results in the Coriolis effect which also influences ocean currents. Winds and ocean water gets deflected from a straight line path as they travel across the rotating Earth.

Answer 3

- air pollutant can be transported long distances. It will travel in the direction of the winds. winds do change direction but the direction is driven by the sun causing areas of high and low pressure. They generally go in one direction and change by small degrees. In the northern hemisphere this wind spiral flows in an anticlockwise direction around areas of low pressure and a clockwise direction around areas of high pressure - the opposite is the case in the Southern hemisphere as the Coriolis force acts in the other direction - the earths rotation results in the Coriolis effect which also influences ocean currents. Winds and ocean water gets deflected from a straight line path as they travel across the rotating Earth. - thermohaline circulation (rivers flow from high altitude to low altitude) (aquifers high pressure to low pressure) location of release

Answer 4

"A situation in the troposphere where the temperature is lower than normal so that relatively warm air lies above cold air." atmospheric temperatures in the troposphere normally decline with increasing altitude. The temperature of warm pollutant gases, released at ground level, makes them less dense and more buoyant than the cooler surrounding air. This allows them to rise, disperse, and become diluted. They cool down as they rise but, because the surrounding air is also cooler, they remain buoyant and continue to rise and disperse. - air above the pollutant site is much warmer than at ground level - this cools the pollutants making them more dense than the air above (trapping and concentrating them) cold air warm air - inversion layer cooler air pollutant smog normal dispersal- temperature in the troposphere cools with altitude - this allows gases to rise, disperse, and dilute - this is because the warmer air makes the pollutants less dense and more buoyant (increase degradability cant disperse = impacted for longer in greater concentrations)

Answer 5

- valleys: where colder denser air can collect - low wind velocity: so that the air layers with different temperatures do not mix - cloudless skies: so that infrared energy can be radiated from the ground, allowing the ground to cool down - mist or fog during the day: water vapour that condenses in the cooler ground layer has a high albedo and will reflect sunlight and slow the heating of the ground that would cause the temperature inversion to be broken down many cities are in valleys where high pollutant emissions may cause serious problems as they become concentrated during temperature inversions such as smoke smog's and photochemical smog's

Answer 6

pollution is the term given to a wide variety of events and processes that do harm to the planet, especially to living organisms 1- a material (eg CO2, particulates, oil) 2- forms of energy (eg noise, radiation, heat, chemical)

Answer 7

-Temperature -Light -Oxygen -pH -The presence of other chemicals -Temperature inversions -The presence of adsorbent materials

Answer 8

- bio-degradation→ broken down by living organisms - phyto-degradation→ broken down by plants - photo-degredation→ broken down by light - thermal-degradation→ broken down by heat - acid-degradation→ broken down from acidic conditions - "oxic"-degradation→ (an) aerobic condition affects breakdown

Answer 9

Bio-degredation → involves, bacteria, decomposers, detritivores (links to mineral resources) "accidental bioleaching" Bacteria will naturally feed on pollutants - what sort of pollutants would be affected by bio-leaching? nitrogen, metals break down of metal minerals

Answer 10

Phyto-degredation → break down of metal minerals (links to minerals resources) - "accidental phytomining" - plants will naturally degrade pollutants - involves plants/ photosynthesising organisms - which pollutant property make this process dangerous? bioaccumulation, biomagnification, toxic, persistence (if long = bad) -absorption of metal minerals

Answer 11

Acidic-degredation (links to mineral resources) - acidic conditions, changing pH - more acidic pH causes metals to become more soluble thus increasing dispersal - metals are move soluble in acids - acidic metals are neutralised by crushed limestone

Answer 12

oxic-degredation → high or low oxygen levels - oxygenates metals - speeds up aerobic decay in organic compounds - sulphide and oxygen → sulphur dioxide (secondary pollutant) -increases aerobic decay of organic wastes - increases risk of anoxic conditions

Answer 13

Photo- and thermal-degradation (links to atmosphere) light and temperature provides activation energy for biological processes to occur speeds up decay (eg organic wastes), warps plastic, forms ozone and results in photochemical smog and photodegradation of some pesticides photo-degradation (light/ photons) degrades pesticides and causes photochemical smogs thermal-degradation (heat) increases the rate of organic decay (eg sewage, organic fertilisers)

Answer 14

Application to monitoring discharges of pollutants such as radioactive materials, heavy metals and persistent organic pollutants eg chlorinated organic compounds. The purpose of CPA is to predict the movement of potential pollutants in the environment to asses the severity and location of the pollution that may occur. If a potential pollutant would be diluted and dispersed, or carried to locations where the impacts would be acceptable, then no further action may be needed. If the potential pollutant would become concentrated, or would be carried to important or sensitive locations, then it may be necessary to control these releases. CPA could be used to monitor the movements of any mobile, persistent pollutant but it is mainly used to monitor the dispersal of radioactive waste discharges. Predicting the pollutant pathways means that environmental monitoring can focus on the sites most at risk of pollution with no need for sampling of sites that were never likely to be polluted. Environmental sampling can be used to check the accuracy of the CPA predictions.

Answer 15

Properties of the pollutant- - state of matter - density - solubility in water/ lipids - chemical stability features of the environment- - wind and water currents - geology - pH - oxygen availability - temperature

Answer 16

Application to monitoring the health risks caused by pollutants such as radioactive discharges and heavy metals. CGM is a specific method of assessing the risk of public exposure to pollutants. It assesses the risk to members of the public who, because of their lifestyle, are most likely to be at risk. This group of people is the critical group. If their risk is acceptably low, then it is assumed that all other members of the public have an even lower risk. CGM is not normally used to detect damage to health caused by the pollutant. It is used to monitor exposure and assess potential risks before health impacts occur. If an unacceptable risk is identified then emissions can be controlled to reduce future exposure.

Answer 17

"The prediction of the routes that an effluent will take in the environment, to assess pollution risk."

Answer 18

"A method of monitoring pollutants, particularly radioactive discharges. If the members of the public that are most at risk are safe, then so is everyone else."

Answer 19

Increased concentrations in valleys, enclosed water bodies. Environmental factors such as air quality, meteorological conditions, hydrology and emission source affect the dispersal of pollutants. Some factors can be managed, for example, emission location and timing. control of emission location- the severity of pollution is affected by the location where the discharges are released. Although the emission location is normally determined by the location of the source, there may be some choices that affect the severity of the pollution caused, such as: - marine discharges where water currents will dilute and disperse emissions; - emissions downwind of urban areas; - not discharging waste into permeable rock above an aquifer;

Answer 20

Restriction of activities during temperature inversions. Environmental factors such as air quality, meteorological conditions, hydrology and emission source affect the dispersal of pollutants. Some factors can be managed, for example, emission location and timing. Control of emission timing- changes in the timing of emissions can affect the severity of pollution. timing impact on pollution tidal cycle - emissions into tidal rivers when the tide is coming in will be carried upstream. Emissions when the tide is going out will be carried out to sea where they will disperse. temperature inversions- atmospheric emissions during a temperature inversion are less likely to disperse. Polluting activities may be restricted in some cities during temperature inversions for example, the use of diesel vehicles or industrial combustion.

Answer 21

Pollutants in the atmosphere often behave very differently from those in water, or on the ground. For example: - rapid movement due to winds leads to dispersal over a large area; - interaction with electromagnetic radiation such as UV (ultra violet) or visible light from the sun can cause chemical reactions to occur, leading to the production of secondary pollutants.

Answer 22

smoke is made up of the atmospheric particulates produced by the incomplete combustion of carbon-based materials. Smoke is often categorised by the size range of its particles; - PM10: particulate matter less than 10 microns in diameter; - PM5: particulate matter less than 5 microns in diameter; - PM1: particulate matter less than 1 micron in diameter; particle size is important because smaller particles remain in the atmosphere for longer so they are more likely to be inhaled toxic chemicals found in smoke can include fluorides, aluminium, lead, acids and organic compounds such as phenol smoke can act synergistically with other atmospheric pollutants such as sulphur dioxide. The exact composition of smoke depends on its source. The main sources of smoke are: Incomplete combustion of coal, diesel, wood, crop waste. urban areas coal diesel combustible waste rural areas crop waste wood fuel grasslands clearing forests by burning

Answer 23

-Respiratory disease. -Increased albedo of atmosphere. -Smoke smogs during temperature inversions.

Answer 24

-on humans: respirator disease, for example, bronchitis, asthma lung cancer. Chemicals on or in smoke particles can kill the cilia in the bronchioles which makes it more difficult to clear inhaled particles and bacteria from the lungs. This can increase the risk of infections. Some of the chemicals may be carcinogenic.

Answer 25

- on other living-organisms reduced photosynthesis as smoke blocks light. Substances in the smoke particles may be toxic, for example, heavy metals and acids - on non-living objects smoke particles can damage buildings due to the acids and organic solvents they may contain. Cleaning dirty buildings is also expensive - on the climate large releases of smoke can reduce temperatures because the high albedo of the smoke reflects light so it does not reach the ground where it may have been absorbed and converted to heat. It was thought that an impact of large-scale nuclear war would result in so much smoke reaching the stratosphere that the Earth would cool significantly for several years. This scenario is called a 'nuclear winter'. it could make survival on earth much more difficult as crops would fail, livestock would die, and many natural ecosystems would be disrupted - smoke particles are small and can remain suspended in the atmosphere for long periods, especially in the stratosphere where there is no rain to wash it out; - smoke in the stratosphere can also deplete the ozone layer - smoke reduces light= decreased photosynthesis - pm10 difficult to remove with rain (does not settle/ persistent)

Answer 26

when smoke and fog are present together a smog may occur. smoke + fog = smog Fog tends to form when moist air is cooled until it reaches its dew point. The water vapour condenses as airborne droplets of water. Temperature inversions make the formation of fog more likely. smoke that is part of a smog is more easily inhaled smog has a very high albedo so the temperature inversion can last for long periods of time. allowing pollutant levels to rise to a high level

Answer 27

the position of London in a valley has caused atmospheric pollution problems since the 1200s. These became worse as the city grew. In December 1952, there was a five day period when anticyclonic weather conditions produced clear skies and low wind velocities so a temperature inversion formed and atmospheric pollutant levels rose. About 12,000 deaths were caused by this smog, mainly people who were old, very young, or had existing respiratory health problems.

Answer 28

-Legislation: Clean Air Act (1956). -Coal treatment: heating to remove tar. -Electrostatic precipitators. -Cyclone separators. -Bag filters.

Answer 29

- clean air act (1956) → this restricted the use of fuels that produce smoke in large urban areas of the UK - introduced pre- and post- coal treatements - banned fuels that produced black smoke in urban settings - implemented the earliest recordings of air pollution coal treatment - pre-cleaning and heating to remove toxic tar post combustion techniques 1. bag filters → put coal etc. in bag filters 2. electrostatic precipitators 3. cyclone separators

Answer 30

"UK legislation to control smoke pollution by the establishment of Smoke Zones by making Control Orders in large urban areas."

Answer 31

- particle matter that is below/ is less than 10 micrometres e.g. dust, pollen, mould etc. - PM2.5 combustion particles, organic compounds, metals etc. → below 2.5 micrometres in diameter (we also have PM2.5 . often contains toxic compounds (acts synergistically with SO2 (sulphur dioxide)

Answer 32

effluent gases are passed through a chamber with many electrically charged wires or plates. The smoke particles within the gases are attracted to the charged wires and plates and collect together. As the particles accumulate they fall to the floor as 'fly ash.' This pollution control method is often used in coal-fired power stations. . Electrostatic precipitators (ESP) - removes fine particles from a gas using electrostatic forces - charges particles, then attracts them to oppositely charged collector plates

Answer 33

"Equipment used to remove suspended particles from gaseous effluents."

Answer 34

"Equipment used to remove suspended particles from gaseous effluents by attracting them to electrically charged wires or plates."

Answer 35

"A method reducing atmospheric pollution caused by smoke and particulate matter."

Answer 36

heating coal allows the tar that causes smoke production to be drained off. This produces smokeless coal.

Answer 37

this process is based on the same principles as many vacuum cleaners. Like the air and waste drawn into a vacuum cleaner the effluent gases are forced to rotate in a cylindrical chamber, which throws the suspended particles to the outside surfaces of the chamber where they fall and collect. This cleans the gases which are then discharged via a pipe from the centre of the cylinder. - pass watered coal particles through - use centrifugal force to separate particles from a gas or liquid stream - leaves cleaner air afterwards

Answer 38

"A method of reducing atmospheric pollution caused by smoke and particulate matter." bag filters remove smoke particles from effluent gases by trapping them on a fabric filter (more efficient combustion or complete combustion with more oxygen will also reduce smoke particles. We could also use less fossil fuel or more renewable energy sources)

Answer 39

photochemical smogs involve a wide variety of reactions between primary and secondary pollutants, in the presence of sunlight, including UV light

Answer 40

-Reaction of nitrogen and oxygen in hot combustion processes. -NOx release due to fertiliser use. [In urban areas most oxides of nitrogen (NOx) are released in the exhaust gases from petrol and diesel engines. NOx are not produced by the fuel combustion itself. They are formed by the nitrogen and oxygen from the air that are drawn into the engine, then react with each other under the high temperature and pressure conditions in the engine. Nitrogen dioxide is toxic at high concentrations but these are normally only reached in more polluted cities. However, in the presence of sunlight and other pollutants such as hydrocarbon vapours, much more toxic secondary pollutants can be produced such as Peroxy Acetyl Nitrates (PANs) - unburnt hydrocarbons come from a variety of sources, especially unburnt fuel in engine exhaust gases, fuel evaporating from fuel tanks, and spillages]

Answer 41

-Photochemical smogs. -Global climate change. - NOx increase the risks of respiratory infections such as colds, flu, and bronchitis. - They can also make existing health problems worse such as asthma and heart disease. PANs are toxic at concentrations much lower than those at which NOx become toxic. They cause eye irritation, breathing difficulty, asthma, emphysema, and an increased risk of heart attacks. Tropospheric ozone contributes to the production of PANs but is also toxic itself, causing asthma, bronchitis, and heart disease. Some cities are particularly prone to photochemical smogs because of their topography, heavy vehicle use, and climate. These include Los Angeles, Mexico city, Paris, Beijing, and Athens where traffic congestion is severe, the climate is sunny and temperature inversions are common.

Answer 42

-Catalytic converters. -Urea sprays. -Control of fertilizer use. NOx and hydrocarbons can both be controlled using catalysts such as platinum and palladium in exhaust pipe catalytic converters. NOx are chemically reduced in catalytic converters to re-form the oxygen and nitrogen gases that originally reacted together. Catalytic converters are used in the exhaust systems of vehicles with petrol engines and many with diesel engines. Unburnt hydrocarbons can be controlled using several methods: - catalytic converters oxidise hydrocarbons to carbon dioxide and water - vapours at filling stations can be collected, condensed, and returned to the main fuel tank - vapours can be collected and passed through an activated filter where the hydrocarbons absorb onto the carbon particles if the primary pollutants are controlled, the secondary pollutants will not be formed because the reactants will not be present unbalanced chemical reduction of NOx NOx → N2 + O2 unbalanced oxidation of hydrocarbons HC + O2 → H2O + CO2

Answer 43

"Atmospheric pollution events in which pollutants such as hydrocarbons, NOx and tropospheric ozone interact to produce more toxic pollutants such as PANs (peroxy acetyl nitrates)."

Answer 44

"Atmospheric pollution event involving smoke and fog (see also photochemical smog)."

Answer 45

SOx : sulfurous and sulfuric acids NOx : nitric acid ozone involved in production of secondary pollutants. Main gases - sulphur dioxide dissolves in water to produce sulfurous acid - sulfur dioxide may be oxidised in the atmosphere by gases such as ozone to produce sulfur trioxide. Sulfur trioxide is dissolved to produce sulfuric acid which is a much more powerful acid than sulfurous acid - oxides of nitrogen dissolve to produce nitrous and nitric acids

Answer 46

- Hydrogen chloride dissolves to form hydrochloric acids. - ozone is involved in the oxidation of sulfur dioxide to sulfur trioxide. → It also harms plants directly

Answer 47

All rain is slightly acidic (pH 5.6) because naturally occurring carbon dioxide in the atmosphere dissolves to produce a dilute solution of carbonic acid which is a weak acid. 'Acid Rain' is the general name given to any precipitation that is more acidic than pH 5.6. Acid rain is the combination of the pollution problems caused by a range of acidic gases and other pollutants that contribute to the problem.

Answer 48

-Combustion of fossil fuels. -Smelting of sulphide ores. --------------------------------------------------------------- - sulfur dioxide → combustion or oxidation of materials containing sulfur, especially burning coal and smelting sulphide ores - oxides of nitrogen → high temperature combustion, especially in power stations and petrol and diesel internal combustion engines - ozone → a secondary pollutant produced by photochemical reactions involving oxides of nitrogen - hydrogen chloride → the combustion of coal and the incineration of wastes containing chlorine, for example, PVC plastic waste - sulfur trioxide → oxidation of sulfur dioxide by ozone

Answer 49

-Non-living objects: damage to limestone buildings, metal structures. -Living organisms. -Direct effects of acids. -Damage to proteins. -Damage to exoskeletons. -Respiratory effects in humans.

Answer 50

Acid deposition corrodes metals, causing damage to railway lines, metal railings, water pipes, pylons, and overhead powerlines. Limestone structures such as buildings and statues are damaged as the acids dissolve the surface layers and weaken the stone structure of porous limestone

Answer 51

Acid rain can harm living organisms directly by the acids in the rain, or indirectly where they cause other environmental changes that are harmful.

Answer 52

Acids are harmful to all living organisms although the range of tolerance differs between species. - Low pHs denature proteins in cell membranes and can inhibit enzyme action. - Tissues which have lining cells exposed to the environment are most likely to be damaged by acid rain, for example, the cells inside leaf stomata, plant root hairs, germinating seeds, fish eggs, and fish gills. - Invertebrates with exoskeletons may die as the acids dissolve the calcium compounds that form the skeleton. - Lichens are very sensitive to acidic conditions and their size, state of health, abundance and diversity may be used in biotic index to monitor acid rain pollution - sulfur dioxide can create breathing difficulties and increase the frequency of respiratory problems such as asthma attacks

Answer 53

the solubility of many metal ions is affected by pH, often becoming more soluble at low pH. - The acidic solutions, produced by acid rain that percolate through soil, can leach metal ions from the soil. - Important plant nutrients such as calcium (Ca2+) and magnesium (Mg2+) are usually lost first. - Once these have gone, other ions are mobilised which would normally be adsorbed onto the surface of clay particles and would therefore be immobile and would not take part in normal soil chemistry. - They include toxic ions such as aluminium (Al3+) and lead (Pb+). - These toxic ions inhibit enzyme action in plant root hair cells and other soil organisms such as detritivores and decomposers. - The mobilised toxic ions may be leached into rivers and lakes where they can harm aquatic organisms. - Metal ions leached out of the soil may also affect human health. . Lead is a neurotoxin and there is some evidence that aluminium ions may be a factor associated with some neurological disorders.

Answer 54

the spreading of pollutants from a point of release in air, soil and water.

Answer 55

- smoke PM10 - acid rain - nitrous oxide - carbon monoxide - hydrocarbons - acid mine drainage - noise - oil - thermal - ionising - pesticides - nutrient - solid waste - heavy metal

Answer 56

- eye irritation - asthma - emphysema - heart attacks

Answer 57

- bronchitis - heart disease

Answer 58

Formed from a synergistic reaction between nitric oxide (NO) and ozone (O3). NOx is toxic at high concentrations, however; this level is rarely met outside of large cities. PANs becomes toxic at lower concentrations and are more dangerous

Answer 59

"The process where a substance fixes onto a surface." Surfaces of clay and organic materials tend to adsorb materials - eg Chernobyl's "elephant foot" - caesium-137 was washed out of air by rain and bound to the clay sediments below - adsorption may immobilise a pollutant and stop it causing problems (however it can concentrate it)

Answer 60

- soil lime content - fog - snow

Answer 61

soils with a high lime content include CaCO3 (calcium carbonate) which neutralises acids and reduces the impact of acids on soil pH

Answer 62

acid precipitation that falls as rain may have a relative brief contact with the leaves of vegetation. In areas that have long periods of fog, the acidic water droplets may be in contact with the leaves of trees for long periods of time so the damage caused by the acids may be increased.

Answer 63

in areas where all precipitation is rain, the impact of the acids may be spread over long periods of time. Areas that have a lot of snow may accumulate acidic snow. If this melts quickly then the pH of the meltwater may be very low, harming life in the soil and rivers.

Answer 64

-SOx : . fuel desulfurization . Flue Gas Desulfurization (FGD) wet FGD and dry FGD. -NOx : . catalytic converters . urea sprays. -Ozone: . control of NOx reduces ozone formation.

Answer 65

"The removal of sulfur or compounds containing sulfur such as sulfur dioxide."

Answer 66

"Processes that remove oxides of sulphur from gaseous effluents."

Answer 67

"A method of removing sulfur oxides from effluent gases using a slurry of crushed lime (mainly calcium carbonate)."

Answer 68

"A method of removing sulfur oxides from effluent gases by dissolving them in a solution such as a spray of sodium sulphite solution."

Answer 69

"A device that reduces emissions of pollutant gases from petrol and diesel engines. Catalysts such as platinum, palladium and rhodium catalyse reactions with oxides of nitrogen, carbon monoxide and unburnt hydrocarbons."

Answer 70

"A method of reducing NOx emissions eg from coal-fired powered power stations."

Answer 71

Involves the removal of sulfur from the fuel before it is burned. In some areas of the sea, for example, the North Sea and within 25 miles of California Coast, only low sulfur fuels may be used by ships - natural gas = hydrogen sulphide is removed from natural gas after it has been extracted to prevent corrosion damage to refinery and pipeline equipment and to the appliances in which the gas is used. This also prevents the production of sulfur dioxide when it is burned. It is removed by dissolving it in an amine solution or reacting it with iron particles.

Answer 72

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

Answer 73

most of the sulfur in coal is present as solid iron pyrites (FeS2). This can be removed by washing and streaming. The coal is crushed then put in a stream of flowing water. The flow rate is fast enough to carry the coal away but leave the denser pyrites behind.

Answer 74

Several processes can be used to remove sulfur dioxide from the power station emissions released after fuel combustion.

Answer 75

Flue gases are passed through a bed of crushed calcium carbonate. The sulfur dioxide reacts with the calcium carbonate producing solid calcium sulfur. if the effluent gases have been cleaned to remove smoke particles, then the calcium sulfate produced may be pure enough to make gypsum building plaster.

Answer 76

this involves sodium sulfite scrubbing where the flue gasses are bubbled through a sodium sulfite solution. the sodium hydrogen sulfite produced by the absorption of sulfur dioxide can be heated. It breaks down to produce sodium sulfite and water, which are reused, and concentrated pure sulfur dioxide, which is a valuable industrial raw material that can be converted to solid sulfur or sulfuric acid

Answer 77

less NOx is produced using lower temperature combustion techniques, such as fluidised bed combustion, where an increased surface area for combustion maintains rapid combustion without the need for high temperatures.

Answer 78

a chamber in the exhaust pipes contains a catalyst such as platinum which chemically reduces NOx back to nitrogen and oxygen gases.

Answer 79

Tropospheric ozone is a secondary pollutant produced by photochemical reactions involving oxides of nitrogen.

Answer 80

NOx can be removed by reacting it with urea. 2CO(NH2)2+4NO+O2→4N2+2CO2+4H2O urea + Nitrogen monoxide + oxygen → nitrogen + carbon dioxide + water

Answer 81

-Ozone is toxic to plants and reduces growth rates of trees and agricultural crops. -in humans, ozone causes breathing difficulties and increases asthma rates. -tropospheric ozone is also involved in the production of secondary pollutants in photochemical smogs and acid rain.

Answer 82

Tropospheric ozone is a secondary pollutant produced by photochemical reactions involving oxides of nitrogen Summary reactions- 1. Nitrogen dioxide is broken down by UV-A sunlight. This is a 'photochemical reaction.' UV-A NO2 → NO + O nitrogen + nitrogen + (monatomic) oxygen dioxide monoxide 2. The monatomic oxygen reacts with 'normal' (diatomic) oxygen to produce ozone O + O2 → O3 monatomic + diatomic → ozone (triatomic oxygen oxygen oxygen)

Answer 83

Tropospheric ozone is a secondary pollutant so levels can be controlled by reducing levels of the primary pollutants that produce it. Nitrogen dioxide is produced by internal combustion engines, power stations, and other high temperature combustion involving air. Methods to reduce these releases will reduce ozone levels by preventing its formation.

Answer 84

-Incomplete combustion of hydrocarbons. Carbon monoxide (CO) is produced when carbon-based materials are burned with a shortage of oxygen, such as the incomplete combustion of hydrocarbons, especially petrol and diesel in vehicle engines.

Answer 85

-If inhaled reduced carriage of oxygen by haemoglobin. Carbon monoxide binds to haemoglobin and prevents it from carrying oxygen from the lungs to tissues around the body. If too much of the haemoglobin in the red blood cells is inactivated by carbon monoxide then brain damage may occur and possibly death. Low concentrations of carbon monoxide can increase the health problems caused by chronic heart disease.

Answer 86

-Catalytic converters. -Improved combustion efficiency. (so less CO produced in first place) Exhaust catalytic converters oxidise carbon monoxide to carbon dioxide. Although carbon dioxide is also a pollutant, the increase in CO2 emissions caused by oxidising the CO is very small compared with other emissions of CO2

Answer 87

-Unburnt hydrocarbon fuels. -Gaseous emissions from fossil fuel exploitation. -Solvents. -Aerosol propellants.

Answer 88

-Greenhouse gases - A gas that absorbs infra-red radiation emitted by the Earth’s surface and causes atmospheric heating. Carbon dioxide and water vapour are the main naturally occurring greenhouse gases. Anthropogenic greenhouse gases include carbon dioxide, methane, NOx, CFCs and tropospheric ozone. -Photochemical smogs - Atmospheric pollution events in which pollutants such as hydrocarbons, NOx and tropospheric ozone interact to produce more toxic pollutants such as PANs (peroxy acetyl nitrates).

Answer 89

-Catalytic converters - A device that reduces emissions of pollutant gases from petrol and diesel engines. Catalysts such as platinum, palladium and rhodium catalyse reactions with oxides of nitrogen, carbon monoxide and unburnt hydrocarbons. -Improved combustion efficiency. -Vapour collection and incineration - The breakdown of a waste by burning it. -Activated carbon filters - A filter that reduces emissions of pollutants such as complex organic molecules that adsorb onto the surface of the activated carbon particles.

Answer 90

A filter that reduces emissions of pollutants such as complex organic molecules that adsorb onto the surface of the activated carbon particles.

Answer 91

The breakdown of a waste by burning it.

Answer 92

(Rivers, lakes and the sea have been used as a place to dump wastes for a long time.) The water cycle is a natural purification process. When water evaporates as water vapour it is pure. It then falls and flows to the sea carrying dissolved and suspended materials (including pollutants) with it. When the water evaporates, the pollutants are left behind and may becomes more concentrated.

Answer 93

When wastes are releases into the water they cause pollution. However, whether this becomes a problem is determined by the features of the water body and properties of the waste material released. - effluent quantity- the amount of pollutant released will clearly affect the concentration. If the concentration of pollutant in the water is low many pollutants are not harmful. - volume of water- the larger the body of water the more the waste will be diluted. - residence time of the water- the shorter the residence time of the water the more likely that the pollutant will be carried away by flowing water and not accumulate.

Answer 94

- Degradation - High levels of sunlight or UV may cause photochemical degradation - dissolved oxygen - higher temperatures

Answer 95

(degradability ="A measure of the ease with which a material breaks down.") - Degradation = is the process by which substances are broken down. It involves both biotic and abiotic processes. Biodegradation involves microorganisms, while physical processes include chemical and photochemical reactions. A number of factors determine the rate

Answer 96

this increases the rate at which aerobic bacteria can break down sewage

Answer 97

-these increase the rate of most reactions; -environmental conditions will also control the new substances produced. In aerated surface waters pollutants are more likely to be oxidised. Oxidation of organic pollutants often causes them to break down into less harmful substances. In deeper water where pollutants are part of the sediments they are likely to be chemically reduced, for example, inorganic mercury wastes being changed to methyl mercury, which is much more hazardous

Answer 98

pollutants becomes less of a problem if they become part of the sediment in a body of water. This effectively removes them from the water. Pollutants such as phosphates and pesticides can become adsorbed onto sediment particles.

Answer 99

currents in the water will move pollutants away, dispersing them through the water so that the pollutants become diluted. Understanding where and how this happens can help determine where to locate suitable sites for effluent discharge. The dilution of pollutants through dispersal in lakes and the sea can reduce the harmful effects and may give the impression that the pollutants have disappeared. In fact, pollutants that persist over time and do not biodegrade may gradually become more concentrated. If this becomes a problem, it may be difficult to solve due to the large volume of water affected. There may also be processes which cause the pollutants to re-concentrate, for example, the bioaccumulation along a food chain of heavy metals and some pesticides. (industrial areas, heavy shipping, areas with large human populations, oil terminals and ports, lakes and enclosed seas in which pollutants may collect. → at high risk)

Answer 100

- Hot water from steam turbine power station condensers. the main source of hot water is steam turbine power stations that use cold water from a lake, river, or the sea to condense steam. The coolant water is returned to its source at a higher temperature.

Answer 101

- Deoxygenation of water. The warm effluent water can have ecological effects, especially on dissolved oxygen concentrations, as the maximum amount of oxygen that can dissolve in water is controlled by the temperature. Most aquatic organisms will be killed by high temperatures because proteins (especially enzymes) are denatured. The few organisms that can survive above 40°C are said to be thermophilic (heat-loving). These high temperatures are rarely reached in aquatic ecosystems, even where hot effluents are being discharged. However, water at lower temperatures can still harm aerobic organisms indirectly because the solubility of oxygen declines as the temperature increases. Low oxygen levels are rarely a problem in the atmosphere because each litre of air contains about 210cm³ of oxygen. Anaerobic conditions are normally only found where a volume of air has become enclosed and deoxygenating processes have occurred, for example, in the decomposition of organic matter. Deoxygenation is much more likely to be a problem in water because at 20°C a litre of water holds a maximum of 6cm³ of dissolved oxygen which is less than 3% of the amount found in air. Some aquatic organisms are often near the lower end of their range of tolerance for dissolved oxygen. An increase in temperatures may cause oxygen to come out of solution, leading to the death of sensitive organisms.

Answer 102

- not enough oxygen to survive/ out of their range of tolerance - grow too fast (more food as more plant life) - eggs hatch earlier → malformed - warmer climate = species may invade - toxicity greater of some pollutants (thermal-degradation) - resistance to disease may be reduced

Answer 103

Scientific principles = The relationship between temperature and maximum dissolved oxygen level. as temperature increases solubility of dissolved oxygen decreases so higher temp = lower dissolved oxygen

Answer 104

- increased metabolic rates of many organisms, so more energy is used, leaving less surplus energy for growth; - increased rate of development of eggs so they hatch earlier; - non-indigenous species, introduced from habitats with warmer climates may thrive and out-compete indigenous species; - pollutant toxicity is often greater as toxins are metabolised more rapidly; - resistance to disease may be reduced.

Answer 105

-Temperature reduction using cooling towers. cooling towers are used to cool power station effluent water so that it does not cause deoxygenation. Water used to condense steam in a power station is taken from a nearby water source such as a river, lake or the sea. After absorbing the heat from the steam, the water is returned at a higher temperature. In large bodies of water, such as lakes or the sea, the warmer water will disperse and be diluted into the large volume of cooler water so it has no significant effects. If the heated water goes into a relatively small body of water, such as a river or small lake, then it may cause a harmful temperature rise. In situations where this is likely to be the case, cooling towers are used to reduce the waste water temperature by dispersing the heat into the atmosphere, thereby returning cooler water to the source. Cooling towers work by spraying the hot water from a shower floor in the lower part of a tall hollow tower. The air in the tower absorbs the heat from the water and rises up the tower, escaping into the open atmosphere. This causes an updraught which draws more air through the shower spray, aiding cooling. A large (2000MW) power station uses 200 million litres of cooling water each hour which is returned at a temperature 5 to 8°C higher than its original temperature. The shower mixes the water with air so it is usually saturated with dissolved oxygen. ( - hot water enters towers - air absorbs the heat from the water, leaving through the top - this causes cooler air to be drawn into the base of the tower - mixes water with air, allowing oxygen to re-dissolve) → or sedimentation lagoons to naturally cool

Answer 106

-Waste lubricating oil. -Ship tank washing. -Ship tanker accidents. -Other ship accidents. -Oil refinery spills. -Pipeline leaks. -Leakage during drilling. waste lubricating oil . vehicle engine lubricating oil which leaks or is deliberately discarded into the environment. . industrial machine oil which is washed into drains, or mixed with other effluents. Accidental releases . shipping accidents especially oil tankers . oil rig accidents . oil pipeline leaks . leakage from storage tanks . discharge of waste water from washing tanks on ship tankers Oil exploration . Drilling: drill pipelines need to be lubricated to reduce friction as they bore through rock. This is usually done with fine clay suspended in water. Sometimes, oil-based clays are used, for example, where the rock would absorb the water and expand. The pollution risk with modern oil-based clay is reduced by using diesel and low toxicity oils rather than heavier oils.

Answer 107

-Toxicity. (A measure of how poisonous a substance is, usually caused by its ability to cause enzyme inhibition.) -Asphyxiation. -Loss of insulation. -Less time to feed young. -Food chain effects (loss of food/ oil obscures prey/ food sources/ toxins in food). - Some components of crude oil are toxic, such as benzene and xylene. Planktonic organisms that float near the water surface are most likely to be affected. - Oil can cover aquatic life that lives on the seashore or at the sea surface. Animals such as molluscs and crustaceans can be asphyxiated. Algae on the seashore would be unable to absorb sunlight or carbon dioxide for photosynthesis. - A severe covering of oil can cause birds to drown - Oil cause birds' feathers to stick together so they lose their insulating properties. The birds may die of hypothermia. - Birds may be able to clean their feathers if they have a small amount of oil on them, but this may reduce the time available to find food for themselves or their young - oil can form a very thin layer on the waters surface which reduces the amount of oxygen that can dissolve from the atmosphere into the water. This can reduce the survival of aerobic organisms. - marine organisms which find mates or food using their sense of smell may have difficulties doing so because of the masking odour or narcotising effect of the oil.

Answer 108

-Recycling of waste oil. -Reduced leakage: equipment maintenance. -Bund walls. Ship tanker design: -Double hulls. -Twin engines/rudders.

Answer 109

.inert gas oil tank systems .recirculation of washing water .improved navigation systems eg GPS .offshore shipping routes .oil interceptors

Answer 110

* inflatable booms * skimmers * absorbent materials * polymerising materials * dispersants * steam cleaning * bioremediation.

Answer 111

- recycling of waste lubrication oil: Used lubricating oil from vehicle engines, or engineering machinery, should not be treated as a waste material. Contaminants can be removed and chemical reforming and distillation can produce commercially valuable lubricants again. Waste oil that cannot be recycled can be burnt as fuel which reduces the demand for fuel from other sources. - reduced leakage: equipment maintenance → maintain and check equipment more regularly to prevent leakage

Answer 112

No control for drilling or oil rigs

Answer 113

"A wall that surrounds a tank which would contain the contents if the tank leaked or burst."

Answer 114

- better shipping routes - oil tankers may have to stay a greater distance away from the shore when possible. If a tanker has mechanical difficulties, such as engine failure, this would give more time to deal with it before it may be carried ashore by water currents or winds - better navigation systems - new technologies such as GPS enable more accurate navigation. The automatic identification System (AIS) allows the position of most ships to be monitored and coordinated to help avoid collisions - inert gas systems - in the past when tankers unloaded their tanks at an oil terminal the space left by the oil used to fill up with air. This can produce an explosive mix of air and oil vapours which caused the loss of some tankers, causing pollution by the remaining oil in the tanks. Modern tankers use cooled exhaust gases from the engines to replace the oil. This has no oxygen in it so explosions are not possible. - tank washing procedures - oil tanks must be washed to prevent the build-up of tar sludges. Tanks used to be washed out with seawater then the oily water was discharged into the sea. This pollution is prevented by recirculating oil in the tanks during unloading so that the sludges are mixed up and removed with the cargo - oily waste water disposal - any oily waste water that is produced can be unloaded at an oil terminal when the tanker docks. The oil and water can be separated, then the oil can be recycled, or incinerated, while the treated water is discharged.

Answer 115

- double hull - tankers used to have a single layer of steel between the oil and the sea. Any damage to the steel hull could allow the release of oil into the sea. All large tankers now have twin hulls with a gap of up to 2m between the hulls so that damage to the outer hull does not necessarily cause the release of oil. - twin engine/ rudder/ fuel tanks - any mechanical failure on a tanker that affects propulsion or steering can be serious as the ship may be carried by currents or winds onto rocks or the coast. Having pairs of essential equipment can save the ship if one set breaks down. - separate oil and ballast tanks: when an oil tanker is not carrying oil it must carry ballast water so that the hull is kept down in the water and the propeller and rudder still work. In the past, the ballast water was carried in empty oil tanks. When the ballast water was pumped back into the sea it would carry some residual oil from the tanks. Modern tankers have separate oil and ballast water tanks so no pollution is caused by emptying the ballast tanks into the sea.

Answer 116

These separate oil from watery waste such as drainage water from major roads or car parks where there may be some floating oil. The water flows into the main drainage system or river but the oil is retained and can be removed later for treatment.

Answer 117

oil storage tanks are built on impermeable bases surrounded by a bund wall which would contain the oil if the tank were to split. The volume enclosed by the bund wall is greater than that of the tank so it cannot overflow.

Answer 118

In turbulent conditions in open water, most oil spills disperse in a few days or weeks. Lighter fractions such as petrol can evaporate and medium fractions will be digested gradually by bacteria, but heavier fractions may remain as tar balls for many years. Oil pollution is most serious when it occurs inshore, or in an enclosed body of water, where dispersal is prevented, where there are more sensitive ecosystems or where there are more concentrated human activities to be affected.

Answer 119

- (inflatable) booms - skimmers - absorbent materials - detergents/ dispersants - polymerising agents (materials) - steam washing - bioremediation

Answer 120

Booms are inflatable tubes that restrict the movement of floating oil. A (weighted) 'skirt' below the boom can retain oil if there is a water current. Booms do not work in open water where current or waves are too strong (as oil just flows under and out of the skirt), so their main uses are in sheltered areas where they can reduce dispersal of oil from the pollution source or protect sensitive areas. (control dispersal)

Answer 121

Skimmers are rotating metal discs that pick up oil that can be scraped off and stored for later disposal by incineration or landfill.

Answer 122

High surface-area materials such as textile mops can help to absorb oil. The absorbent material and oil can be removed and disposed of by incineration or in landfill sites.

Answer 123

(say dispersants as that is what is on spec) Detergents or dispersants break up the oil to produce an emulsion of oil droplets in water. They allow the oil to become more mobile and disperse, possibly to be broken down by bacteria but they do not reduce the amount of oil pollution themselves. They can be spread at sea by aircraft and ships or using backpack sprayers on the shore.

Answer 124

Chemicals have been developed that cause the oil molecules to join together, producing more solid materials that can be collected more easily.

Answer 125

Oil on beaches can be washed off using sprays of steam and hot water. This does not destroy the oil, but it can remove it from particularly sensitive habitats. However, the steam jets may kill organisms deeper in the beach sediments that were not affected by the oil.

Answer 126

Some bacteria break down hydrocarbons and help to remove the residual pollution left after other clean-up methods have been used. The rate of bacterial action depends om environmental conditions and is most rapid where temperatures, oxygen levels and nutrient levels are high. Bioremediation of soil may be accelerated by irrigation, the addition of nutrients and ploughing to aerate the soil.

Answer 127

There is no control for drilling or oil rigs

Answer 128

Two from: - (large amounts of data) can be collected very quickly - continuous data collection (over time)/ extent of spread can be accurately measured - wider area can be covered - can detect spills quickly/ planes have to respond to known spills

Answer 129

Three from: - improved shipping routes/ shipping routes moved away from coastlines where possible; - improved navigation systems/ GPS/ AIS; - inert gas systems/ cooled exhaust gas to fill tanks after unloading; - recirculating oil in oil tanks rather than washing of oil tanks (sludges not discharged); - oily waste water disposal/ oil separated from water at terminal; - double hulls/ gap between hulls (so damage to outer hull reduces risk of oil leaking)/ reinforced/ strengthened hulls; - twin engines/ rudders/ fuel tanks (if one fails there is a back-up to avoid collisions); - separate oil and ballast tanks (avoid oily water being discharged when cargo is loaded); - fewer but larger oil tankers/ fewer but larger oil spills;

Answer 130

Two from: - reduces light available for photosynthesis - reduces dissolved oxygen for respiration (by coral polyps) - toxic effects on coral/ food sources of polyps - reduces filter feeding/ clogs cilia of polyps - named example of species interdependence eg food source of coral eg. plankton, reducing nutrients

Answer 131

"Cleaning up a contaminated site using living organisms such as bacteria that chemically degrade the pollutants or plants that absorb the pollutants."

Answer 132

-Toxicity. -Systemic/contact action. -Specificity. -Persistence. -Liposolubility. -Bioaccumulation. -Biomagnification. -Mobility. -Synergism.

Answer 133

"A substance that is absorbed and transported throughout an organism eg by sap in plants."

Answer 134

"A pesticide that kills pests by coming in contact with them after spraying. Unlike systemic pesticides, they are not absorbed and translocated around the crops."

Answer 135

No pesticides are so specific that they only kill the target organism and are completely harmless to non-target organisms. Harm to non-target species may be reduced by controlling the dose applied. MDAF is the lowest dose that will kill every member of a population. It can be used to estimate the dose needed to control pests. MDNF is the highest does that can be used without killing any members of the population. Ideally, the pesticide does would not exceed the MDNF of non-target species.

Answer 136

Persistent pesticides may remain in the environment long enough to disperse over larger areas and are more likely to have time to bioaccumulate and biomagnify.

Answer 137

Liposoluble pesticides are those which dissolve into fats, for example, within the human body. If organisms are unable to excrete them or 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.

Answer 138

pesticides which have bioacccumulated in one type of organism may become more concentrated when they are eaten by their predators.

Answer 139

The mobility of a pesticide is controlled by other properties such as persistence, solubility and ease of vaporisation. Some pollutants may be transported within living organisms to new areas where they may be excreted.

Answer 140

Pesticides are unusual pollutants because they are intended to be toxic and are deliberately spread in the environment. However, they do not just harm the target species.

Answer 141

-Direct toxic impacts on non-target species. -Toxic impacts after increased concentration. -Indirect effects: food chain impacts, loss of inter-species relationships.

Answer 142

Pesticides cause harm to non-target species by being toxic. Doses which are not in themselves lethal may inhibit metabolic processes and cause ill health. Higher doses may kill. For example, DDT affected many birds by being concentrated within food chains. Low doses caused eggs to have thin shells which broke easily. Higher doses caused sterility. Much higher doses caused death. As a result, lower doses can still cause a species to die out as breeding success is reduced to below the rate needed to maintain the population.

Answer 143

A reduction in the population of one species can affect other inter-dependent species. Some species become rarer because they have lost a food supply or an ecosystem service such as pollination or seed dispersal. Other species may become more common because they have fewer competitors or predators.

Answer 144

"Hydrocarbon-based compounds that include chlorine. They include pesticides such as DDT and industrial chemicals such as PCBs. Their use is now banned or restricted."

Answer 145

"Insecticide group eg parathion, malathion. They are not persistent but have high mammalian toxicity."

Answer 146

"Synthetic insecticide pesticides, based on the natural chemicals originally extracted from chrysanthemum flowers (pyrethrins). They are not persistent and have low mammalian toxicity."

Answer 147

"A widely used group of insecticides. They have been linked with the deaths of bees, especially when they act synergistically with some fungicides."

Answer 148

"A poison that affects the nervous system."

Answer 149

Organochlorine insecticides were first used in the 1940s to control pests that transferred human pathogens such as the mosquitoes that carry malaria and the ticks, lice and fleas that carry typhus fever. This use of DDT saved many thousands of lives. It was then used as an agricultural insecticide for which it had some ideal properties: - high toxicity to insects - low toxicity to vertebrates including mammals, so farm workers were unlikely to suffer acute toxic affects - high persistence, so it continued to protect crops for some time after application - high liposolubility and low solubility in water so it was not easily washed off fields by heavy rain. DDT was also used to control pests in homes by incorporating it in paint, wallpaper or in pest sprays. However, its properties led to major environmental problems that were not initially understood. The high toxicity to insects led to the deaths of many non-target insects such as bees, butterflies and beetles. High persistence and liposolubility allowed DDT to bioaccumulate and biomagnify up the food chains. The increase in concentration that occurred produced levels that are toxic to predatory vertebrates at the top of the food chain such as birds of prey, herons, and otters. The use of organochlorines killed the top predators in many areas. The rate of degradation of DDT depends upon environmental conditions but it can remain in the environment for decades. Other major organochlorine insecticides include dieldrin, Aldrin, and lindane. The use of all organochlorine insecticides is now either banned or heavily restricted. DDT is still used to control malaria mosquitoes in houses. This is considered to be safe as it should not cause toxic exposure or lead to DDT entering the human food chain where it could biomagnify.

Answer 150

Organophosphate pesticides are neurotoxins that inactivate the enzyme acetylcholinesterase so nerve function is damaged. The nerve gas sarin is an organophosphate that was developed during the 2nd world war as a weapon. Other organophosphates were developed as insecticides, such as malathion and parathion. Organophosphate use increased as the use of organochlorines declined. They have low persistence and liposolubility so they do not bioaccumulate or biomagnify. However, they have high mammalian toxicity so farm workers can be at risk of acute exposure to toxic doses, possibly causing death. Chronic exposure to low doses is associated with impaired memory, depression, behavioural changes, ADHD, Alzheimer's disease. Some organophosphates are suspected carcinogens.

Answer 151

Pyrethroids are synthetic insecticides that have been developed from natural pyrethrin insecticides extracted from plants. They have a high insect toxicity and low mammalian toxicity. They are not persistent so they do not bioaccumulate or biomagnify. Their use is generally safe for humans unless a very large dose is absorbed. Pyrethroids are the most commonly used domestic insecticides. Pyrethroids are toxic to fish so should not be used near rivers or fish farms.

Answer 152

These are the most widely used insecticides and are chemically similar to nicotine. They are neurotoxins, inhibiting the action of the neurotransmitter acetylcholine. They have high insect toxicity but lower toxicity to vertebrates as they cannot cross the blood-brain barrier of vertebrates. They are relatively persistent and water soluble, so they remain in the soil long enough to be absorbed by roots and translocated within the crop plants which are them protected from insect pests (systemic action). Neonicotinoids are very toxic to bees and their use has been linked to the decline of many bee populations. They have neurotoxic effects, reducing their ability to navigate, and reducing their immunity to disease. Toxic effects are most likely when the neonicotinoids are sprayed onto the crop or when neonicotinoid dust is carried by the wind. Using neonicotinoids as a coated seed treatment minimises harmful impacts on non-target species. The impact on non-target species appears to be increased by a synergist action with some fungicides that may be present at the same time. Neonicotinoids are broken down most rapidly in the presence of sunlight and soil microbes. Some research suggests that neonicotinoids may build up in aquifers which may cause problems in the future.

Answer 153

-Restrictions on use of selected pesticides, eg organochlorines, organophosphates. (alternative pest control methods, alterations to how they are used) - restrictions on use - use of non-persistent pesticides - use of more specific pesticides - use of systemic pesticides - application timing - non-pesticide techniques

Answer 154

Some pesticides have been banned, or their use has been restricted where they could cause problems, or when the benefit of use is greater than the disadvantages. The use of the organochlorines DDT, dieldrin, and aldrin is banned in most countries. DDT is still used in some countries for the control of malaria mosquitoes. The organophosphate methyl parathion is still used as an agricultural insecticide, but its use is generally prohibited for control of garden or domestic pests.

Answer 155

Pesticides which have low persistence will break down rapidly and cannot become more concentrated or travel long distances after application. Organophosphate insecticides are less persistent than organochlorine insecticides.

Answer 156

Pyrethroids and organochlorine insecticides are both toxic to insects but pyrethroids are less toxic to mammals.

Answer 157

Systemic pesticides are absorbed by the crop and translocated within it. They do not need to be sprayed onto all surfaces, are not washed off after they have been absorbed, and will protect new growth. As the systemic pesticides are present within the plant tissue, they may be eaten by humans if they are still present when the crop is eaten.

Answer 158

Spraying on still days results in less spray drift onto surrounding habitats. Spraying at night or when crops are not in flower will reduce the impacts on bees. Newer spraying techniques use smaller droplets to produce a more even coverage which reduces the amount required to adequately cover all areas of the crop leaves.

Answer 159

- multicropping - A form of polyculture where two or more different crops are grown in an area at the same time. - barrier crops - A crop that is grown around another crop to protect the neighbouring crop, usually by producing a scent that deters the pests. - cultural pest control - biological control - The control of pests using living organisms, usually predators or pathogens. - companion crops- These are crops that are grown together to benefit one or both crops by actions such as providing nutrients, controlling pests or attracting beneficial insects. - pheromone trap - A trap that attracts organisms using the scent of pheromones. They can be used to try to catch all the members of one gender of a species to stop breeding, but are usually used to show the presence of a pest species. - sterile male techniques - A method of insect pest control that uses the release of males that have been sterilised. If they mate, no offspring will be produced. - crop rotation - The practise of growing a different crop in a field on a cycle of three, four or five years.

Answer 160

Nitrates (leachate/runoff) and phosphates (sewage effluent). - phosphates in sewage effluent and eroded soil particles - nitrates washed off farmland from manure and artificial fertilisers

Answer 161

"The process by which nutrient levels in a water body increase to excessive levels such that the growth and subsequent die-off of plants and algae cause deoxygenation."

Answer 162

1- aquatic plants grow exponentially since nitrate level is no longer a limiting factor 2- algal bloom on water surface prevents light from reaching the bottom and plants die 3- oxygen levels decrease as population of aerobic saprobionts increase to decay dead matter, so fish die 4- anaerobic organisms reproduce exponentially and produce toxic waste which makes water putrid

Answer 163

Eutrophication (combined effects of nitrates and phosphates). Cultural eutrophication- Eutrophication is the enrichment of a water body with nutrients, usually with an excess amount of nutrients. As a result, plants and algae grow and may result in oxygen depletion of the water body. It can happen naturally over time, however it can also be a result of human activities such as the discharge of phosphate-containing detergents, fertilisers, or sewage, into an aquatic system. This 'cultural eutrophication,' can also occur through clearing land and run-off, resulting in large quantities of nutrients that build up relatively rapidly. The main nutrients involved are nitrates and phosphates as these are often the limiting factors on plant growth in aquatic ecosystems. - algae and cyanobacteria absorb their nutrients directly from the water not from the sediments. This means that dissolved nutrients are used more easily although their levels may fluctuate rapidly. The growth of algae leads to a range of problems: . cyanobacteria can release harmful toxins which can affect livestock, pets, and people who drink or are in contact with the water . floating algae shade the submerged or rooted macrophytes (larger plants) which cannot photosynthesise. The plants may die which disrupts food webs and their decay by aerobic bacteria may cause deoxygenation . algae are an unreliable food source and do not support rich food webs as they can die off rapidly if nutrients become depleted, or if other conditions are not ideal, for example, light or temperature . increased mortality increases decay . removes nutrients/ food chains . results in deoxygenation At the end of summer, when warm temperatures cause dead vegetation to decay rapidly, the resulting deoxygenation kills off animal life. Deoxygenation is a particular problem at night when there is no photosynthesis to replace lost oxygen.

Answer 164

- oligotrophic lakes - few nutrients, little plant growth, for example, mountain lakes - Eutrophic lakes - rich in nutrients, abundant plant growth, for example, lowland lakes - mesotrophic - waters that fall in between eutrophic and oligotrophic

Answer 165

-Methemoglobinemia/blue baby syndrome. -Possible human carcinogen. Nitrates are very soluble and may get into drinking water supplies. They may also be ingested in processed food. - can look for nitrate pollution by doing critical group monitoring looking for blue baby syndrome

Answer 166

- bacteria in babies intestine convert nitrates to nitrites - this reduces haemoglobin's oxygen carrying ability - lead to methemoglobinemia, a condition in which oxygen is not delivered to tissues

Answer 167

Nitrates are not very toxic but bacteria in the gut convert them to nitrites. Nitrites react with haemoglobin in the blood and reduce its ability to carry oxygen. High levels may cause the disease Methaemoglobinaemia or 'blue-baby syndrome'. Infants are especially at risk as they have more of the necessary bacteria and their haemoglobin reacts more rapidly with nitrites. This is usually only a problem with water from shallow wells that receive drainage water from arable farmland. Nitrites are also ingested as food additives in meat, fish, and cheese products.

Answer 168

"A health problem with several possible causes, where the haemoglobin in a baby’s blood does not carry enough oxygen. Nitrates in drinking water can be converted to nitrites which reduce the ability of haemoglobin to carry oxygen."

Answer 169

Gut bacteria convert nitrates to nitrites. These may then be converted in the gut to nitrosamines which are carcinogenic and may cause stomach cancer. Most research has been carried out on rats and the link between nitrates in water supplies and cancer in humans is not conclusive.

Answer 170

*Nitrates: -use of low solubility fertilisers -nitrate vulnerable zones. *Phosphates: iron phosphate precipitation. There are several ways that inorganic nutrients such as nitrates an be controlled through: - reduced use of nitrate fertilisers - reduced ploughing at times of heavy rain - use of soluble, rapid-release fertilisers - the deposition of waste manure where the nutrients will not leach into the ground or be washed into a river - reducing cultivation of crops that have higher nitrogen requirements, for example, replacing wheat with triticale (hybrid between wheat and rye) - reducing the reliance on artificial fertilisers, for example, by growing more legume crops that have nitrogen-fixing root nodule bacteria These techniques are especially important in Nitrate Vulnerable zones where aquifers may be exposed at the surface and can easily become contaminated: Other ways to manage and limit the effect include: * phosphorus - adding iron (III) sulfate to remove phosphates from liquid effluents released by sewage treatment works. The phosphates are precipitated as a fine sediment of iron phosphate - iron (III) sulphate reduces solubility - dredging lakes and rivers that have phosphate-rich sediments from past pollution or adding iron (III) sulfur to reduce the solubility of the phosphates.

Answer 171

- no rivers - buffer strips - flat ground (less runoff) reduce reliance on nitrates - crops that need less nitrogen - legumes testing for nitrates? - test strips - compare reaction to colour chart - photometer/ colorimeter/ spectrometer - absorbs different amount of UV light. Darker = more nitrates - ion selective electrodes - probe measures the amount of nitrate ions in the water 2-3% error margin tests for NO3- ions

Answer 172

- ATP = energy for all cells - bones and proteins → there is no gaseous form of phosphorus thus none in the atmosphere * only 0.1% of the earth's crust is phosphorus * 70% of this phosphorus is found in Morocco making it a major mineral resource → also contains lots of uranium

Answer 173

*Organic wastes (sewage, manure, silage fluids, effluent from processing of wood and paper). *Many Processes involving animal and plant products produce liquid effluents containing organic nutrients such as: - carbohydrates, - lipids, - proteins. These processes include - sewage works, - manure disposal, - silage storage, - leather tanneries, - paper mills, - food processing plants.

Answer 174

Deoxygenation caused by microbial aerobic decomposition. and eutrophication. - this may kill aerobic organisms, such as fish and insects - however, organic pollution has two further issues; * it introduces new organic material rather than just inorganic (helps multiple trophic levels → population booms) * organic materials breaks down into inorganic components: - nitrates - phosphates -deoxygenation (eutrophication) -pathogens -inorganic nutrient release

Answer 175

"Organisms that cause disease."

Answer 176

Untreated organic nutrients which flow into rivers or lakes provide food for microorganisms in the water. As a result, their aerobic digestion deoxygenates the water and may kill aerobic organisms such as fish and insects. The microorganisms can also cover the river or lake bed. This will prevent light reaching the normal water plants so that photosynthesis is inhibited, killing the plants and disrupting food webs. Eutrophication can also occur with organic nutrient pollution as microbial decay releases inorganic nutrients.

Answer 177

Sewage can contain pathogens from infected people. If other people come into contact with these pathogens, either directly or through contaminated food or water, the disease can spread. Diseases which spread via sewage and contaminated water include cholera, typhoid, and dysentery.

Answer 178

Organic nutrients do not cause eutrophication directly as they provide nutrients for heterotrophs not nutrients for photoautotrophs. However, as they decay, they may release inorganic nutrients that cause eutrophication.

Answer 179

The major stages in treatment of organic wastes: -pre-treatment: removal of solid objects (goes to landfill) .grit traps, screens. -primary treatment .primary sedimentation, separates organic waste from sludge -secondary treatment .aerobic bacterial decomposition: activated sludge/filter beds (collect methane → biogas) .secondary sedimentation. -tertiary treatment .phosphate removal .bacterial microfilters. -anaerobic sludge digestion till inert. . disposal - landfill or incinerate - release of untreated sewage is now banned in many countries - effluent received by a sewage treatment works is produced by a range of activities, such as: . toilet flushing water . water from washing clothes/ dishes . personal hygiene . road drainage water . non-toxic industrial waste - the actual concentration of sewage is actually very low (typically 250kg of water containing 2-3Kg of liquid and solid sewage per person per day.

Answer 180

- pre-treatment - the removal of solid objects such as paper, plastic, road grit - primary treatment - the separation of most organic solids from fluids - secondary treatment - the digestion and breakdown of the remaining organic matter in the fluids - tertiary treatment - additional treatment to remove phosphates or bacteria - sludge treatment

Answer 181

- screens - metal grills or sieves are used to trap floating and suspended items such as plastic and paper items. These are then treated by incineration or disposal of in a landfill site - grit traps for stones and road grit. Usually the channel widens out so that the effluent flows more slowly and the grit drops to the bottom as there is no longer enough kinetic energy to carry it along. The grit can later be removed from the tank then disposed of in a landfill site or by sterilisation and reuse.

Answer 182

Primary sedimentation is the most important process. The effluent is left to stand in large tanks where the faecal solids sink to the bottom so that they can be removed and treated separately. This results in over 95% of the organic matter being removed from the fluid effluent so the risk of deoxygenation in the river or lake is greatly reduced.

Answer 183

The sludge removed from the primary sedimentation tanks probably contains pathogens and its foul smell makes storage or disposal near urban areas difficult. To solve these problems anaerobic digestion is used. Anaerobic microbes digest the sludge in a warm digestion tank for about four weeks. This kills most pathogens and the odours are reduced. What remains after this process has a smaller volume which is disposed of in several ways: - landfill: simple and relatively cheap but wastes their nutrient content - dispersal in the sea: relatively straightforward for coastal communities but most countries now ban this to reduce pollution - incineration: a lot of fuel (usually natural gas) is required and is therefore expensive. This also creates further waste in the form of gas and a small amount of ash which is deposited in landfill sites - agricultural use: the sludge can be used as an agricultural fertiliser. It has a better C:N ratio, has a lower volume and a lower odour than undigested sludge. It is important to time spreading carefully as application during the growing season would cover the crops, while application during the winter can cause damage to the damp soils as farm vehicles compact the soil. Heavy metals from urban wastes and road runoff may be present in the sludge and could be absorbed by crops and then be consumed with food. This can be reduced by adding lime to reduce the solubility of the heavy metals. Remaining pathogens can be destroyed by heat treatment of the sludge before use. Anaerobic digestion also produces biogas which is mainly methane with some carbon dioxide. This can be used as a fuel, for example, to heat the digester, nearby buildings, or to generate electricity

Answer 184

Secondary treatment destroys the small amount of organic matter that remains in the effluent from the primary sedimentation tank. - aeration tanks/ oxidation ponds: the remaining organic matter in the fluid effluent is broken down by bacteria. Shortage of oxygen can be a limiting factor as it slows down this aerobic process. To prevent this happening, large amounts of air are mixed in by paddle wheels, or air stones. Pure oxygen may also be used. - secondary sedimentation tanks: the effluent from the aeration tanks contains suspended bacteria which must not be wasted. These are collected in the secondary sedimentation tank and returned to the aeration tank as 'activated sludge.' In most sewage works, the clear effluent from secondary treatment is discharged into the river, lake, or sea. It should contain no pathogens, or other organic materials, but it may contain some dissolved inorganic nutrients which could cause cultural eutrophication. - trickling filter beds: Four rotating arms spray the liquid effluent over large cylindrical tanks containing lumps of a solid material such as gravel, coke, or blast furnace clinker. The surface area is maximised for bacteria, fungi, algae, worms, fly larvae, and other invertebrates to digest remaining organic matter. Nitrates may also be denitrified by bacteria so the liquid effluent will cause less eutrophication.

Answer 185

Tertiary treatment is used if the discharge site for the treated effluent is particularly ecologically sensitive or important for humans. - phosphates can be removed by adding a solution of iron (III) sulfate producing insoluble iron phosphate as a fine sediment which can be used as an agricultural fertiliser - the effluent can be strained through very fine sieves called micro-strainers. The remaining suspended bacteria are killed by UV light or by adding a sterilising chemical such as chlorine.

Answer 186

While the volume of sewage remains relatively stable throughout the year the volume of effluent received by a treatment works can vary significantly with changes in weather, for example, as a result of a storm or a drought. Sewage works are designed to cope with some extra flow but not the maximum flow that is possible. To do this would incur great extra expenses to allow for very rare extreme storm events. Most sewage works have storm overflow tanks that can be used to hold surplus effluent after a storm. This is treated later when the volume of effluent arriving returns to normal.

Answer 187

In the UK, the majority of sewage systems were developed over the last 150 years. Underground pipes were laid to collect all solid and liquid effluents often including drainage water from roads and roofs. Originally these were discharged into the river or sea untreated, or onto fields in 'sewage farms'. Sewage treatment works were added later. This approach produces large volumes of dilute sewage effluent. It is more efficient to have two separate waste collection systems. One collects only foul waste from toilets which requires full treatment but the smaller volume allows the construction of smaller, and therefore cheaper, sewage treatment works. It also means that the system is not effected by flow fluctuations caused by weather changes. the second system collects the larger volumes of cleaner water. This requires little treatment before discharge.

Answer 188

-Oxidation of sulfide ores in mine spoil/rocks. (can dissolver very easily into water) -Drainage water/leachate (from metal/ coal mines → these oxides further degrade into sulphuric acid). Many igneous metal ores are sulfides. In spoil heaps chemical reactions take place between the small amounts of remaining sulfide ores and oxygen from air in the spaces between the waste particles. This may leave metal oxides and oxides of sulfur which dissolve in drainage water to produce sulfuric acid. This is known as acid mine drainage.

Answer 189

-Reduced pH – acid damage. -Increased solubility and mobilisation of toxic metals. The acidic solutions that leach out of the spoil heap have similar effects to acid rain leaching through soil. (denaturation of proteins, inhibiting enzyme action etc.). The pH of the solutions is often very low and may contain dissolved toxic metals if they were present in the mine waste. impacts = contaminated water → turns yellow-orange → indicates high levels of iron and smells like rotten eggs (pyrite iron sulfides (FeS2) from mining when disturbed, it reacts with oxygen = iron and aluminium sulphate)

Answer 190

Collection of drainage water and neutralization with lime. The pH of the drainage water can be increased by passing it through crushed limestone to neutralise the acids. This will also reduce the solubility of many toxic metals. → limestone - porous limestone absorbs and neutralises acidity Increased mobility of toxic metals - bioremediation (similar to bioleaching), phytoremediation (similar to phytomining) Use acidophiles to "clean-up" pollution)

Answer 191

A wide range of physical, chemical and biological methods can be used to monitor water pollution. Most pollutants can be monitored using a chemical or physical method. Modern methods usually use a calibrated electronic meter. A number of 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 the effects of pollution rather than the levels of the pollutant itself; Some methods of pollution monitoring measure the impacts rather than the cause. This is usually done when a range of pollutants may be involved and it is difficult to distinguish between their individual effects or which direct measure should be used.

Answer 192

organic materials of plant or animal origin can provide food for bacteria and lead to deoxygenation as they respire anaerobically. It is difficult to measure or forecast the levels of organic pollutants because there are so many that could be present and they have different potentials to cause deoxygenation. So, organic pollution is monitored through the level of deoxygenation that it caused. The amount of oxygen being used is measured under standardised conditions.

Answer 193

1- 1 litre of water 2- 20°C 3- 5 days 4- In the dark (to prevent oxygen replacement by photosynthesis if algae are present in the water)

Answer 194

This is similar to BOD but measures the amount of oxygen needed to chemically oxidise all the organic and inorganic substances in a water sample.

Answer 195

One of the most common gut bacteria E. coli. Its presence in water is taken as confirmation of faecal contamination. The health risk can be determined by measuring the number of coliform bacteria in a sample as this indicates how serious the contamination is. It is better to monitor this than the presence of pathogens such as typhoid as these will not always be present and whose absence would not confirm that the water is uncontaminated.

Answer 196

A biotic index is a scale for showing the quality of an environment by indicating the types of organism that are present. Characteristics of species used in biotic indices: - have different sensitivities to pollution; - are easy to identify; - are easy to find; - are normally present; - are usually common; - are generally distributed. Commonly used biotic indices: - lichens to monitor atmospheric acidic pollution - aquatic invertebrates to monitor water pollution e.g. sycamore "Tar spots'" caused by a fungus called Rhytisma acerinum the fungus loves cold, damp conditions

Answer 197

"A measure of pollution based on the presence, abundance and state of health of selected living organisms eg lichens for acid rain, aquatic invertebrates for water pollution."

Answer 198

Advantages- - A rapid assessment of current and recent pollution can be made. - Expensive equipment is not required. Disadvantages- - Sorting samples can be time-consuming. - Identification of different taxa involves some skill. - Further tests are required using other techniques to detect the specific pollutants present.

Answer 199

"The properties of heavy metals should be analysed to understand why they have caused pollution problems and the strategies used to prevent pollution." Pollution caused by heavy metals is affected by properties such as liposolubility, synergism, and solubility. Many heavy metals inhibit enzyme function, especially the enzymes of the nervous system. (neurotoxicity) Heavy metals that are liposoluble may be stored in fat droplets in living cells so that chronic exposure to small doses may eventually produce toxic concentrations by bioaccumulation. Passage along a food chain may lead to biomagnification. Some heavy metals cause more serious pollution if they act in conjunction with other pollutants such as synergism between cadmium and zinc. Most heavy metals are more soluble at low pH. Therefore pollution caused by heavy metal wastes can be reduced by increasing the pH to reduce solubility.

Answer 200

water → algae (primary producers) mercury concentration is x20,000 higher for every trophic level above algae about 7X higher mercury concentration bottom to top of food chain x 49,000,000 more mercury

Answer 201

- egg shell thinning - interference with mammalian reproduction - damage to the immune system

Answer 202

since 1988, over 20,000 seals in the North sea have dies of viral infections = PCB poisoning - in Canada, Inuit nursing mothers have 5X more PCB in their milk than mothers in southern Canada

Answer 203

-Neurotoxicity. (Neurotoxin=A poison that affects the nervous system.) -Liposolubility. (A measure of how easily a substance dissolves in fats and oils.) -Bioaccumulation. (The increase in concentration of a substance in living tissue as it is absorbed and stored faster than it is broken down and excreted.) -Biomagnification. (The progressive bioaccumulation of a material along a food chain eg organochlorine insecticides, PCBs, heavy metals.) Lead has been used to make many products including car batteries, pipes, solder, paint, anti-knock petrol additives and flashing for roofs and windows on buildings. Some of these uses have been reduced or stopped because of the increasing awareness of the toxicity of lead.

Answer 204

The biggest uses of lead do not necessarily cause pollution because they may not cause the release of lead into the environment. The uses of lead that cause pollution have been restricted but uses that do not cause pollution continue, for example, lead-acid batteries, lead flashing used in building construction (inhibits growth of moss ad lichens). Industrial workers may inhale lead dust or absorb it through the skin if it dissolves in sweat. Acute exposure to large doses may cause severe symptoms including brain damage, paralysis and eventually death. Very high doses can kill by causing liver and kidney failure. These problems are only likely in industrial accidents and are prevented by good working practices, for example, wearing facemasks, using water sprays or remote operations.

Answer 205

-Discontinued uses, eg paint, petrol additives, lead pipes, solder for water pipes, lead fishing weights. -Waste storage at high pH to reduce solubility. - water pipes (replacing old lead pipes with copper pipes) - petrol additives (lead is replaced with other substances such as benzene) - electrical solder (lead-free solder is now widely used and contains tin, silver and copper) - lead-based paint (have been phased out in many countries) - fishing weights - shotgun pellets (alternative materials (tungsten) is now used)

Answer 206

- inorganic mercury mercury oxides moderate liposolubility - organic mercury high liposolubility (skin and gut) can be present as vapours susceptible to bioaccumulation and biomagnification - liquid mercury hard to absorb (low liposolubility) vapours can be inhaled

Answer 207

methylmercury (synergism with carbon and mercury) → very harmful → can't remove from gut - teratogenic action (affects placental barrier) - carcinogenic action

Answer 208

lead has been used to make water pipes for over 4,500 years. Small amounts of lead dissolve into the water so people drinking the water may suffer chronic exposure. In the UK, most lead piping was replaced in the 20th century with copper pipes, although lead solder was still used to join copper pipes. Lead solder has now been replaced with solder based on tin, zinc, and copper. Water companies in the UK no longer use lead pipes, but some may remain in old buildings. In high risk areas, small amounts of phosphoric acid are added to the water supply. This produces an insoluble layer of lead phosphate in the pipes which prevents lead dissolving into the water.

Answer 209

anti-knock agents such as tetra ethyl lead (TEL) were added to petrol to smooth the explosion of combustion and reduce engine wear. However, lead particulates were released into the atmosphere which created a public health threat. Since the 1980s lead has been replaced with other chemicals such as benzene. Other fuels such as diesel, LPG, hydrogen and alcohol do not need lead additives.

Answer 210

Lead-based solder used in electrical connections is not a significant threat to public health during use. However, the lead can be vapourised and inhaled when it is melted during soldering, or if it is melted during recycling after use. Lead-free solder is now widely used and contains tin, silver, and copper.

Answer 211

Lead compounds have been added to paint to accelerate drying and increase durability. Paint layers that are intact on surfaces pose a small health risk but dusty, flaking old paint dose pose a much greater health risk, especially to children who pick up particles under their fingernails and suck their fingers. The removal of old paint can be a health risk as dust or vapours produced may be inhaled. The use of lead-based paints has been phased out in many countries since the 1980s. Chemical paint stripper and hot air guns are safer paint removal methods as they do not produce dust or vapours containing lead.

Answer 212

Lead weights that are used on fishing lines may be discarded or lost then swallowed by waterfowl such as swans who mistake then for snails. The swans may be killed by lead poisoning. Lead has been phased out in the UK for smaller fishing weights and replaced with metals such as tungsten which is less toxic.

Answer 213

Most shotgun pellets miss their target and land on the ground. Water birds such as ducks and geese then feed on wetlands, where shooting has taken place, may swallow pellets and be poisoned. Some voluntary schemes use alternative materials such as tungsten steel for shotgun pellets that are used over wetlands.

Answer 214

-Neurotoxicity. (Neurotoxin=A poison that affects the nervous system.) -Liposolubility. (A measure of how easily a substance dissolves in fats and oils.) -Bioaccumulation. (The increase in concentration of a substance in living tissue as it is absorbed and stored faster than it is broken down and excreted.) -Biomagnification. (The progressive bioaccumulation of a material along a food chain eg organochlorine insecticides, PCBs, heavy metals.)

Answer 215

Mercury is released into the environment in a number of ways: - Disposal of items containing mercury, for example, batteries, fluorescent lights, thermometers; - chemical plants that produce chlorine using mercury electrodes; - combustion of coal.

Answer 216

The severity of mercury pollution depends upon its chemical form: -Elemental mercury. -Inorganic mercury. -Organic mercury. In some situations, less toxic forms of mercury have been released but the pollution problems created have been very severe. Relatively low toxicity inorganic mercury compounds that enter anaerobic sediments in lakes or the sea may be changed into organic compounds such as methyl mercury by anaerobic microbes. The mercury then bioaccumulates and biomagnifies along food chains, often reaching concentrations that are much higher than when it was released into the environment.

Answer 217

- liquid (elemental) mercury is not easily absorbed through the skin or gut, although vapours may be absorbed in the lungs if they are inhaled;

Answer 218

- inorganic mercury compounds such as mercury oxide are absorbed moderately well in the gut;

Answer 219

- organic mercury compounds such as methyl mercury are absorbed easily through the skin, by the gut, and as vapours if they are inhaled. Organic mercury compounds are liposoluble so they pass through cell membranes easily, including through the blood-brain barrier into the brain where the impacts can be more serious. It can also cross the placenta and harm unborn babies. Mercury also causes kidney damage.

Answer 220

Many uses of mercury and effluent disposal methods have been restricted as the understanding of mercury pollution problems have increased, for example: - mercury thermometers have been replaced by alcohols or electronic thermometers; - mercury can be removed from effluents by reverse osmosis, or by using activated carbon filters; - ion exchange filters; - disposal at high pH to reduce solubility.

Answer 221

(Students should understand that the treatment method for solid wastes depends upon its properties. " Refers to any discarded or unwanted materials" The methods appropriate for each waste type should be analysed. Disposal methods depend on their properties: 1- degradability 2- environmental conditions 3- flammability 4- radioactivity 5- toxicity - mining and construction wastes - domestic and commercial municipal waste - industrial waste Produced Human activities- -Mining creates spoil heaps -Demolition waste including asbestos -Packaging from goods -Paper -Food and garden waste -Clothing and textiles -Industrial waste

Answer 222

Mining and the construction industry produce large quantities of waste. Most are non-hazardous but some can cause problems because they include particular hazardous materials. - mine overburden heaps - usually non-toxic - mine spoil heaps - may contain toxic metals - demolition waste - may contain hazardous materials such as asbestos

Answer 223

Main categories: - packaging and containers - paper - domestic appliances - organic materials - food and garden waste - clothing and other textiles Waste management problems: - large quantities of waste are produced - every household across the country produces waste which makes collection labour intensive and expensive - the mix of waste varies through the year, for example, more garden waste during the summer - many different types of waste are mixed together

Answer 224

The majority of industries generates solid wastes. Disposal problems will depend on the properties of the specific waste involved and the amount produced.

Answer 225

Important properties of solid wastes that influence the choice of disposal methods include: - degradability - how rapidly the waste breaks down; -conditions that affect degradation, for example, oxygen, pH, temperature, presence of bacteria; - flammability; - release of radioactivity; - toxicity. (A measure of how poisonous a substance is, usually caused by its ability to cause enzyme inhibition.)

Answer 226

Affluence has a significant affect on the amount of waste generated as more affluent people are more likely to do the following: - purchase more consumer goods; - purchase more trivia; - purchase disposable items; - throw items away rather than repair them. These activities also increase the wastes produced in the manufacture of goods and the mineral extraction required to make the items. Manufacturing and retail industries may attempt to increase sales using strategies that also increase wastes, for example: - built-in obsolescence: items are designed to have a short lifespan. For example, they are made to be non-durable or wear out. Or there may be changing fashions so that items become outdated and are discarded. The customer can then 'upgrade' to the latest models. - disposable products: items intended to have a limited usable life so they need to be replaced sooner such as disposable razors, cigarette lighters, ballpoint pens. - Over-packaging: items may be made more attractive with unnecessary packaging that is likely to be thrown away.

Answer 227

-landfill -incineration -recycling -composting.

Answer 228

Large amounts of solid wastes are deliberately or accidentally dumped into the environment. Such waste including litter can harm wildlife that becomes caught in it or swallows it. Plastic wastes can degrade to becomes small particles that can chock marine organisms or release chemicals that may be endocrine disruptors. --------------------------------------------------------------- Factors affecting waste disposal methods: Many disposal methods are available for solid wastes. The method selected can be affected by the following factors: - population density, for example, collection costs are higher where there are fewer people and the wastes are dispersed; - mass of waste produced per capita; - properties of the wastes, for example, toxicity, flammability; - land availability; - availability of recycling technology; - degree of environmental awareness and willingness of people to recycle, reuse, repair; - regulatory framework and legislation; - household income; - waste processing costs for labour or machinery.

Answer 229

- reduces food waste - enriches soil/ add nutrients to increase fertility of soil - stores carbon - sustainable gardening practices - water conservation - saves money → mitigation - cardboard → less smelly - biogas → produces energy

Answer 230

- it can be smelly - composting can attract pests - space requirements - time and effort - not aesthetically pleasing

Answer 231

This is often the simplest option for disposal as it requires little or no treatment of the waste itself. However, early landfill sites were poorly managed, being used for mixed wastes with little attempt to prevent escape of harmful fluids and gases. Polymer liner prevents escape of leachate. (limestone) Layers of soil reduce pest problems. Clay prevents entry of water. Methane collected to be used as fuel. Leachate collected and treated. Flammable materials dispersed amongst water. Features of good landfill site management - separation of different waste types and recording of their composition and locations. - polymer liner to prevent the escape of leachate fluids. - perimeter fence to trap litter blown by winds. - regular covering with soil to reduce pest problems. - collection and treatment of leachate fluids. (bioleaching) - collection of methane and its use as a fuel. (waste-based biofuel) - impermeable cap to prevent water entering once site is complete: usually layers of clay and polymer. - deodorising spray to control odours. - dispersal of flammable materials rather than dumping large quantities in one place. - chemicals which may react with each other should not be dumped together.

Answer 232

-This is often the simplest option for disposal - as it requires little or no treatment of the waste itself - inexpensive

Answer 233

- the potential resource value is lost, such as metals ,glass, plastics. - landfill sites use large areas of land. - Organic matter decays anaerobically, releasing methane gas and carbon dioxide contributing to global warming. - toxic leachate may leak from poorly managed landfill sites. - wildlife habitats and farmland may be lost. - contaminants in the landfill site may prevent the later development of landfill sites for uses such as housing or agriculture. - transport delivering the wate to the site and the infrastructure around it generate noise and congestion in the local area.

Answer 234

Industrial spoil usually involves large quantities of non-toxic solids so the main problem is the quantity, but it can also produce polluting leachate fluids. A wide range of industrial activities produce spoil, such as: - mining and quarrying, for example, coal, China, clay, metal ores; - coal-fired power stations and incinerators produce ash; - iron blast furnaces produce slag.

Answer 235

Spoil heaps need to be managed to minimise environmental problems. They can also be managed to make site reuse easier after site closure. To do this successfully a range of possible problems need to be managed: - stability - drainage - lack of nutrients - pH - contamination - topography - toxic leachates - heavy metals - flammable wastes

Answer 236

Landslips are a danger. Surface erosion can be reduced by establishing vegetation so the roots hold the spoil together. Stability can be improved through compaction, either by compacting the spoil heap as it is built up, or by constructing buildings on concrete rafts to reduce uneven settling. This reduces the danger of subsidence.

Answer 237

natural or artificial drainage may be essential where spoil heaps are tall or on hillsides to reduce the risk of landslides following heavy rain.

Answer 238

some spoil contains low levels of plant nutrients, for example, the sand left after China clay extraction or shale spoil from coal mining. The addition of topsoil, sewage sludge and fertilisers are common techniques to improve the nutrient content and increase plant growth.

Answer 239

the addition of lime can reduce the acidity of spoil, for example, where sulfides in the spoil produce sulfuric acid. Spoil is rarely too alkaline to support plant growth. Old steel works can leave alkaline wastes which can be valuable for uncommon plants such as cowslips.

Answer 240

phytoremediation can be used where plants are used for the absorption and storage of pollutants such as heavy metals, mercury. Petrochemical waste such as oil can be treated by bioremediation. Certain species of bacteria will digest the oil if appropriate conditions of temperature, water supply, and aeration are maintained.

Answer 241

spoil heaps can be unattractive with steep slopes and angular shapes. Landscaping can be used to reshape the heap, although this may require more land.

Answer 242

these should be collected and treated to prevent them entering water courses. Deeper layers of soil should be applied during during restoration so that plant roots cannot reach the layer containing toxic materials. This could bring toxins to the surface and cause their dispersal into the wider environment.

Answer 243

these are a problem when they are mobile in the environment. They can be inhaled or may be ingested in food or water. This can be prevented by disposing of them in solid form under alkaline conditions. This means the metals should remain insoluble so their solubility is usually reduced with increasing pH. To prevent dust particles, heavy metals should be covered so that they cannot become airborne.

Answer 244

coal or shale oil production spoil can contain high proportions of hydrocarbons which can result in spontaneous combustion within the heap. This risk can be reduced with regular layers of fine-grained material to reduce airflow.

Answer 245

"The breakdown of a waste by burning it." This involves the destruction of wastes by high temperature oxidation. - the volume of ash produced is much less than the original waste - the heat produced may be used for district heating or the generation of electricity - no sorting or complicated management is needed - flammable materials such as plastics and dirty paper and card can be separated and burnt in purpose-built power stations, or used for industrial heat such as cement manufacture. Large quantities of a single flammable waste can be used to produce a fuel for specific purposes. fuels can be created, for example, refuse-derived fuel (RDF) pellets of shredded compacted flammable municipal waste and tyre-derived fuel (TDF) made from shredded vehicle tyres, sometimes mixed with coal, wood or other fuels.

Answer 246

"The breakdown of a waste by burning it." This involves the destruction of wastes by high temperature oxidation.

Answer 247

- the resource value of recyclable materials is lost - toxic dioxins may be produced by reaction of organic wastes and chlorine - the fuel used to maintain combustion of wet or non-flammable wastes is expensive - the wastes may need to be separated to remove wet wastes, increasing processing costs - the treatment of atmospheric pollutants in the effluent gases increases costs

Answer 248

- recyclable wastes are removed before incineration - wastes with a high water content are removed, for example, compostable waste - the combustion temperature is kept high and waste gases are cooled rapidly to reduce dioxin production - the heat produced is harnessed for use - atmospheric pollution is controlled: SO2, NOx, HCL, CO, smoke/ PM10 - flammable organic wastes may be chemically broken down by incineration. The hydrocarbon component of the molecule will be converted to carbon dioxide and water. These are not serious problems as they will be produced in small quantities, compared with other sources such as vehicle fuel use - some materials produced during the incineration process may need additional treatment chlorine atoms, for example, from CFCs, will react to create hydrogen chloride. This dissolves to form hydrochloric acid and causes acid pollution. A water spray 'scrubber' can be used to dissolve and remove it from gaseous emissions. The acid produced can then be neutralised by treating it with an alkali or crushed limestone. - heavy metals can be removed by scrubbing then stored in solid form at high pH, making them insoluble and less mobile.

Answer 249

- reduces need for extraction - decreases landfill volume - mimics natural cycles (e.g. decomposers) - environmental benefit - recycling creates jobs - recycling raises overall environmental consciousness - recycling reduces the energy used to manufacture goods

Answer 250

- mixed materials difficult to separate (increases processing costs) - requires consumer cooperation -collection and processing is time-consuming and expensive - energy-intensive - can lead to pollution

Answer 251

"Solid wastes with particular risks should be separated and treated individually." If highly hazardous wastes are released into the environment they will cause serious pollution. Specialised storage or treatment techniques are likely to be required to avoid such pollution. Different techniques are used for different types of hazardous waste.

Answer 252

"Secure, permanent, sealed storage." Asbestos is dangerous if it disintegrates and the fibres become airborne so they can be inhaled. The fibres can cause irritation and lead to asbestosis. Scar tissue produced in the lungs thickens the alveoli so gaseous exchange is slowed and breathing becomes more difficult. Asbestos can also cause a particular type of cancer: mesothelioma. This is a cancer of the tissue that covers many internal organs, including the lungs. It can take decades to develop but it is not usually difficult to identify the cause as over 80% of mesothelioma cases are caused by asbestos. Asbestos has been used to strengthen cement roof panels. It can also be found in textured ceiling coverings. As long as the asbestos is encapsulated and remains intact it is not dangerous. Asbestos wastes require special handling. They need to be double wrapped in heavy-duty polythene bags in a specialised landfill site where the waste contents are recorded.

Answer 253

"Incineration." cyanide compounds include triple bonds between carbon and nitrogen atoms. A fourth bond links the carbon atom to an element such as hydrogen or sodium. Cyanide compounds are used in the manufacture of paper, textiles and plastics. Electroplating, metal cleaning and gold extraction all use salts of cyanide. Cyanide compounds can be very toxic enzyme inhibitors that may be inhaled or ingested. Incineration is the safest way to dispose of cyanide wastes so that the carbon and nitrogen are separated and oxidised. The carbon dioxide and oxides of nitrogen produced are a much smaller pollution problem.

Answer 254

The sources and properties of the three waste categories should be understood to identify appropriate disposal methods: -high-level waste -intermediate-level waste -low-level waste. The need for sealed storage, monitoring, encapsulation, use of absorbers and cooling should be evaluated for each waste level.

Answer 255

used uranium fuel rods - split nuclei form highly radioactive isotopes Vitrification- dried powdered solid waste mixed with molten glass and allowed to solidify in stainless steel containers, surrounded by concrete to absorb radiation. Air cooling removes the heat of radioactive decay. In the UK it is stored at Sellafield, Cumbria

Answer 256

- The metal tubes that surrounded the fuel rods became radioactive in the reactor. Filters from waste reprocessing. - Mixed with cement and stored in stainless steel drums. In the UK it is stored at Sellafield.

Answer 257

-General equipment and clothing that become contaminated by coming in contact with radioactive material. - Sealed in thick polythene bags, inside steel drums, inside steel truck containers in a concrete-lined landfill site. In the UK it is stored at Drigg near Sellafield.

Answer 258

- Waste solutions from used fuel reprocessing and storage - Filtered, including ion exchange, then discharged.

Answer 259

- gases released from used fuel during storage and reprocessing - filtered then released

Answer 260

Some wastes are so hazardous that they must be stored using a method where they become immobile and could not leak out in the future. -Encapsulation: Hazardous wastes containing heavy metals such as arsenic, mercury, nickel, and chromium residues and intermediate level radioactive waste are mixed with a cement slurry which is poured into containers made of an impermeable and unreactive material. The solid cement encapsulates the waste so it is immobilised.

Answer 261

Some wastes are so hazardous that they must be stored using a method where they become immobile and could not leak out in the future. - Vitrification: This is a specialist encapsulation technique used for the storage of high-level radioactive waste that has been extracted from used nuclear fuel. Powered radioactive waste is mixed with molten glass and poured into stainless steel containers which are then sealed. The glass solidifies encapsulating the waste. Even if the glass were shattered, the waste would remain encapsulated in the fragments. The steel containers are placed in cylindrical passages inside a concrete building. The passages are ventilated to remove the heat generated within the waste.

Answer 262

The scientific principles of sound that affect noise pollution: -frequency range of human hearing -logarithmic nature of the dB scale -volume -threshold of human hearing.

Answer 263

Noise is sound that is unwanted because it is disturbing or causes damage. Noise pollution has limited impact on wildlife and the ability of the Earth to support life. However, it can have serious impacts on human quality of life and health. -The logarithmic nature of the dB scale: The human ear is sensitive to a very wide range of sound power levels so a logarithmic scale is used: the Bel. Each Bel is divided into ten decibels. An increase in volume of 10dB represents a ten-fold (ten times as great) increase in sound volume. An increase of 3dB represents a doubling in volume. 0dB does not mean there is no sound. It is set as the quietest sound that can be heard at 1,000Hz and is called the threshold of human hearing.

Answer 264

Sound vibrations passing through the air are detected in the cochlea of the inner ear by hair-like projections on sensitive nerve cells. Each group of cells is sensitive to a particular sound frequency. The typical range of hearing for young people is 20 - 20,000 Hz. Older people generally have a reduced frequency range, especially at higher frequencies and require a higher volume for sounds to be detectable. Exposure to excessive noise and some health issues can also reduce sensitivity and range.

Answer 265

20 - 20,000 Hz

Answer 266

0 dB/ 1,000 Hz is called the threshold of human hearing

Answer 267

15 minutes

Answer 268

-acoustic fatigue -shock impacts.

Answer 269

Some objects have a frequency at which they will naturally vibrate: their natural resonant frequency. If they are exposed to sound at this frequency then they will vibrate. This may eventually cause stress cracking and structural failure called 'acoustic fatigue'. Acoustic fatigue in early aircraft jet engines led to improved designs to prevent cracking in the engine cowling. ( vibration damage = repetitive vibrations can cause structural damage to buildings, bridges, and underground pipes. This can be caused by vibrations created by the wheels of heavy vehicles. (off spec) )

Answer 270

The force of the impact of a sudden very loud noise can cause damage, such as the 'sonic boom' of supersonic aircraft causing structural damage to buildings, for example, broken windows and dislodged masonry.

Answer 271

-hearing damage -stress, ulcers, heart disease -behavioural changes.

Answer 272

this is usually caused by long-term occupational exposure to loud machinery, especially to high frequency sounds.

Answer 273

Long-term exposure to high noise levels can cause ulcers, high blood pressure, and heart disease.

Answer 274

Noise can also cause behavioural changes such as irritability, aggression, or a lack of concentration, which may lead to accidents.

Answer 275

-livestock injuries -disturbance of breeding birds -reduced feeding success: bats, owls, dolphins -hearing damage/behavioural changes: cetaceans.

Answer 276

Sudden noises such as low-flying aircraft may cause animals to panic, leading to injuries or breeding failure.

Answer 277

Birds that sing to establish their territories or attract mates may have difficulties in urban areas because of background noise levels. Birds scared by sudden noises leave their nests, allowing predators to take eggs or chicks. Cliff-nesting birds may knock eggs or chicks into the sea if they are frightened by low-flying aircraft.

Answer 278

animals that use hearing to find food, for example, bats, owls, dolphins, may not be able to find food as easily if there is background noise.

Answer 279

Cetaceans such as whales and dolphins can be harmed by loud noises such as the military sonar used to detect submarines. If they are close to the source of the sonar they may suffer hearing damage. Mass-strandings of cetaceans may be linked to the use of sonar.

Answer 280

-Engine noise, especially at high thrust. -Air turbulence.

Answer 281

-location away from major population centres -taxi areas away from residential areas -provision of acoustic insulation -land-use restrictions -baffle mounds/acoustic insulation.

Answer 282

engine designs to reduce noise emissions aerodynamic surfaces. - blended wing aircraft - aerodynamics - lighter aircraft

Answer 283

In this design the engines can be located on top of the aircraft so the body acts as a barrier reducing the noise that reaches the ground

Answer 284

Fairings on the undercarriage reduce turbulence around the wheels and leg struts. Fairings covering wing flap hinges reduce turbulence. Riveted construction creates surface indentations which create turbulence and noise. Welded panels create less turbulence.

Answer 285

using composite materials, such as carbon fibre, makes aircraft lighter so less engine thrust is needed. For example, the Airbus A380 uses lightweight composite materials for 25% of its structure. The newer A350 uses 53% composite materials.

Answer 286

-the use of airport take-off and landing noise footprints in planning mitigation programmes -flight paths avoid urban areas -altitude restrictions -constant descent angle -night flight restrictions -noisy aircraft banned -fines for excessive noise -engine test restrictions -reduced use of reverse thrusters.

Answer 287

New airport developments are located in areas with a low population density to minimise the number of people affected.

Answer 288

Aircraft taxiing before take-off can increase noise levels for nearby residents. The layout of the airport can separate taxi areas and residential areas.

Answer 289

Buildings affected by aircraft noise may have free acoustic insulation provided, for example, double glazing.

Answer 290

There may be restrictions on land-uses near airports, for example, allowing industry but not housing developments.

Answer 291

baffle mounds and acoustic barriers can deflect or absorb noise around an airport.

Answer 292

- High bypass-ratio engines - chevron nozzles - engine hush kits - engine acoustic liners-

Answer 293

- High bypass-ratio engines: early jet engines had a single cowling (tube) around the jet with the turbulent exhaust gases providing thrust but also creating a lot of noise. Modern jet engines have a second cowling and a turbofan on front of the jet that forces 'bypass air' around the inner cowling. The bypass air smooths the flow of the exhaust air and reduces noise levels. The bypass-ratio is the ratio of bypass air: jet exhaust gases. The higher the ratio, the quieter the engine. e.g. engine, example of aircraft, bypass-ratio, first use, RR Olympus, Concorde, 0:1, Early 1950s, RR Trent 1000, Boeing 787, 10:1, 2011

Answer 294

- chevron nozzles- these are used on high bypass engines to make them even quieter. A serrated trailing edge on the outer cowling mixes the bypass air with the surrounding air more smoothly.

Answer 295

- engine hush kits- these work like chevron nozzles and can be fitted to low bypass ratio engines to make them quieter

Answer 296

- engine acoustic liners- acoustic liners are used inside the outer cowling and around the inner cowling to absorb noise

Answer 297

fairings on the undercarriage reduce turbulence around the wheels and leg struts. Fairings covering wind flap hinges reduce turbulence. Riveted construction creates surface indentations which create turbulence and noise. Welded panels create less turbulence.

Answer 298

flight path routes are planned to avoid densely populated areas whenever possible

Answer 299

flight path routes are planned to avoid densely populated areas wherever possible.

Answer 300

having a constant decent angle (usually 3°) for the final descent before landing makes the engine noise less intrusive. There are no periods of high thrust as there are with a stepped descent. A steeper descent angle allows aircraft to stay at greater altitudes for longer, so ground-level noise is further reduced.

Answer 301

most airports near large residential areas restrict the number of night flights, especially take-offs (airports near high population density areas often restrict or ban night flights. Take-offs are controlled more than landings because they are noisier.)

Answer 302

Aircrafts 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 reduction in maximum noise). All new aircraft since 2006 must meet 'chapter 4' noise limits (10dB lower than chapter 3). Chapter 3 aircrafts are being phased out. New regulations being introduced from 2017 will make noise regulations stricter with a further 7dB reduction. --------------------------------------------------------------- Quota count system- airports may encourage airlines to operate quieter aircraft by restricting flight times for noisier aircraft, or by using a points system. The quota count system is used at Heathrow, Gatwick, and Stansted airports. It has also been adapted for use at other airports. Aircraft types are allocated points depending in their noise levels. Each airline is allocated a certain number of points. The total point score of the actual flights must not exceed their allocation. It is easier to keep within the point total if new purchases are of quieter aircraft. --------------------------------------------------------------- control of supersonic flights- there are no longer any supersonic civil airliners. Concorde ceased commercial flights in 2003. Concorde was banned from almost all airports and was not allowed to fly supersonic over most countries.

Answer 303

aircraft pay charges for using airports. At many airports the charge is based on noise levels. At Heathrow, the noisiest aircraft pay 10 times as much as similar sized quiet aircraft. Night flights cost nearly three times as much as day flights. There are fines for breaking flight noise limits. Fines in 2015 were £500 per dB above the limit for day flights and $4000 per dB above the limit for night flights.

Answer 304

Areas where engines are tested on the ground at high thrust are located away from residential areas, are only used during the day, and are surrounded by acoustic screens.

Answer 305

-Avoid urban areas -Varied flight paths -Avoidance areas such as conurbations -Avoid low flying areas -Compensation paid for damage to -buildings / harmed livestock -Seabird cliff breeding colonies / ecologically sensitive sites avoided

Answer 306

-Fly at Hugh altitude so less sound reaches ground. -New airports located in areas with low population density. -Taxi areas at airports separated from Urban areas. -Engine test areas surrounded by acoustic screens (away from urban areas). -Free acoustic glazing for buildings near airports (triple glazing). -Land use restrictions near airports e.g. industrial not residential. -Baffle mounds and acoustic barriers deflect / absorb sound around airports. -prevent aeroplanes using loud thrusters to get off landing runways ASAP.

Answer 307

Railway noise pollution affects a small proportion of the population but it can be a serious local problem. High speed passenger trains are noisiest but freight trains are often very long and travel slowly, so they can take a long time to pass. -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. off spec - Wheel noise - good carriage suspension

Answer 308

Road traffic noise affects more people than any other form of noise pollution. -Wheel vibration/tyre noise – sound absorbing road surface such as porous asphalt or asphalt that includes shredded rubber from old vehicle tyres, acoustic fences. -Engine noise – acoustic insulation around the engine. -Air turbulence – improved vehicle aerodynamics.

Answer 309

Most industrial noise is produced within industrial buildings so the noise pollution is only likely to affect workers. However, some industrial activities can affect the public and wildlife. -Air compressors. -Pile drivers, stamping machines. -Drills. -Mine blasting, military sonar.

Answer 310

-Worker ear protection/remote operation. -Acoustic insulation/mats/baffle mounds. -Restrictions on timing of operations. -Alternative procedures, eg pressing instead of stamping. -Drilling instead of pile-driving.

Answer 311

embankments that absorb and deflect noise

Answer 312

Domestic noise pollution is mainly caused by domestic appliances such as washing machines, music equipment, garden machinery, DIY power tools, and barking dogs. These are not technically complex but they can have serious impacts on quality of life. -Appliances – acoustic insulation. -Music – volume limiters. --------------------------------------------------------------- off spec controls- - domestic appliances with acoustic absorbers, for example, washing machines, vacuum cleaners - wearing ear defenders when using power tools - volume limiters on music equipment - selection of quieter domestic appliances. This requires the availability of good information to help in making choices - control of pet dogs

Answer 313

The loudness of sound is measured using the decibel scale. This can be modified for specific applications. Other scales derived from the dB scale are used to give an overall measure of how noise levels change over time for events where the loudness is not constant, for example, an aircraft take-off. Modifications to the dB scale- The dB(A) scale is used for human hearing. It takes into account the sensitivity of human hearing by 'weighting' sounds between 1000 and 4000Hz. This is because the nerve cells in the ear are more sensitive to sounds in this frequency range so they are heard more easily.

Answer 314

- LA 10 measures noise exceeded for 10% in any set period. It is a good measure of the noisiest periods. - LA 90 measures the noise level exceeded for 90% in any set period. It is a good measure of the quietest periods. - Traffic noise index (TNI): this produces a representative measure of traffic noise using LA10 and LA90. - L10(18h): this measure assumes that traffic noise is only a problem during the 18 hours between 6am and midnight. The noise level that is exceeded during the noisiest 10% of each of these 18 hours is measured. The mean of these 18 levels is then calculated.

Answer 315

- effective perceived noise levels (EPNL) - this is an estimate of the relative loudness of a particular type of aircraft during take-off, overflight, and landing. It is calculated from many observations, recorded at 450m to the side of the flight path. - Noise and Number Index (NNI) - this combines the number of flights and the noise levels of aircraft above 80dB as it is presumed that aircraft below 80dB do not cause serious annoyance. It has been replaced with the leq 57dB. - Leq 57dB - leq is an average sound level over a particular period. For UK airports, an average of 57dB between 7am and 11 pm in the summer is used. levels above this are considered annoying. Areas with noise above this level will experience 'significant community annoyance.'

Answer 316

Pollution caused by radioactive materials has resulted from past nuclear weapons testing, nuclear waste disposal, accidents at nuclear power plants, as well as from transportation, processing and storage of radioactive materials. Ionizing (UV, X-rays, gamma rays) → alpha, beta particles and neutrons (radiation dosage is measured in sieverts (Sv) 1 sievert in a short time can cause radiation sickness; 10 sieverts in a short time can kill.)

Answer 317

-Nuclear weapons. -Nuclear electricity. -Ship propulsion. -Manufacturing industry. -Healthcare. -Agriculture.

Answer 318

Nuclear weapons use nuclear fission and fusion. About 500 nuclear test explosions took place in the atmosphere up to 1980.

Answer 319

nuclear fission using uranium and plutonium is used in nuclear reactors to generate electricity

Answer 320

the high energy density of nuclear fuel means that ships propelled by nuclear reactors rarely need to be refuelled and don't need air for combustion which is very useful in submarines.

Answer 321

- measuring the thickness of rolled metals and paper - testing aircraft jet engine turbines - strengthening polymers. Radiation can create cross-links in molecules. This is used to improve the properties of latex rubber for surgical gloves, balloons used in heart surgery and vehicle tyres - in oil and gas exploration to test rock porosity

Answer 322

- sterilising heat-sensitive surgical equipment - cancer treatment - x-ray photography and CT scans

Answer 323

- pest control: stored food sterilisation - sterile male insect pest control - production of mutations in crop breeding programmes

Answer 324

-Half-life and health risk. -Type of radiation and health risk: Relative Biological Effectiveness (RBE). -Exposure vs contamination. -Activation products. -Units: Becquerels, Grays, Sieverts.

Answer 325

All atoms of an unstable isotope have the same probability of decaying during a specific time period. The likelihood of an atom decaying is not affected by the number of atoms present. For mass of an individual isotope there is a predictable rate at which the atoms will spontaneously decay and emit ionising radiation. This rate is usually expressed as its half-life. [This is the length of time it takes for half of the original isotope to decay]. So, if a mass is observed for several half-lives then the remaining proportion will be 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, etc. of the original amount. e.g. uranium-238 half life = 4.5x 109 years and it occurs naturally in rocks iodine-131 half life = 8 days and is produced in fission in nuclear reactors

Answer 326

isotopes with short half-lives release all their radiation quickly. They are dangerous but they do not pose a danger for long. Therefore short-term precautions may be sufficient to protect workers and the public - acute effects?

Answer 327

isotopes with long half-lives pose a danger for a long time. They emit small amounts of radiation in any given time period so the level of danger may be quite low. - chronic effects?

Answer 328

isotopes with half-lives of several decades generate concern because the rate of radiation release is quite high. People can be exposed for most or all of their lives and short-term precaution measures are inadequate.

Answer 329

Alpha Beta Gamma Neutron ← (increasing) No. of free radicals → (increasing) penetration power -they can be stopped by . alpha - paper . beta - aluminium . gamma - lead . neutron - concrete

Answer 330

- ease of absorption/ distance travelled- very easily absorbed travels short distances - RBE- 20 - Comparative health risks- alpha particles are absorbed by clothing and dead skin so alpha emitters outside the body are usually safe. Ingested alpha emitters are very dangerous as the particles are all absorbed in a small mass of tissue, creating more concentrated damage and increasing the risk of free radical interactions

Answer 331

- ease of absorption/ distance travelled- moderately easily absorbed travels medium distances - RBE- 1 - Comparative health risks- moderately dangerous sources near to the body still pose a risk

Answer 332

- ease of absorption/ distance travelled- not easily absorbed travel long distances - RBE- 1 - Comparative health risks- lower danger longer distance of travel means distant sources are still a risk

Answer 333

- ease of absorption/ distance travelled- moderately easily absorbed travel medium distances - RBE- 2-10 - Comparative health risks- very dangerous ionising radiation neutrons still pose a risk after they have been absorbed some atoms are changed when bombarded by neutrons so they become activation products. A stable nucleus becomes a radionuclide when bombarded by neutrons and may later decay and release ionising radiation

Answer 334

"A measure that considers the energy absorbed from ionising radiation and its damaging effects."

Answer 335

"An object or person receiving radiation, but not necessarily coming in contact with the source." exposure involves the absorption of ionising radiation. For exposure to occur, the person must be close enough to the source for the radiation to reach them

Answer 336

"Pollution caused by mixing with materials" contamination refers to physically carrying radioactive materials which, when they release radiation, may cause exposure. If someone is contaminated, then exposure will continue as long as they carry the source on or in them sources of ionising radiation which are sealed inside a container may expose people nearby to radiation but they cannot become contaminated

Answer 337

"Atomic nuclei that become radioactive because they have absorbed neutrons" Exposure to most types of radiation does not cause the material that absorbs it to become radioactive because the nuclei are unaltered. however, exposure to neutrons can cause previously stable nuclei to become radioactive as the absorption of a neutron will convert it into a new isotope. Activation products are most often found in the structures of nuclear reactors

Answer 338

- The Becquerel = "The unit of activity of a radioactive source" - The gray = "A unit of energy absorbed from ionising radiation." the gray is a measure of absorbed dose. 1Gy is the absorption of one joule of radiation energy per kilogram of matter - The sievert = "A unit measuring ionising radiation absorption, considering energy and RBE." is a measure of effective dose that allows for the differing effects of the different types of radiation {N°. of sieverts = N°. of Grays x a radiation weighting factor for the type of radiation. The weighting for alpha radiation is 20, for gamma and beta radiation it is 1}

Answer 339

-Free radical production, DNA damage. -Acute and chronic effects. -Somatic and gonadic effects.

Answer 340

alpha beta gamma neutron no

Answer 341

- Free radical production: When ionising radiation is absorbed by living tissue, unusual ions called 'free radicals' are produced. These have unpaired electrons, are highly reactive, and can cause biologically damaging reactions. The most common molecule in cells is water so it is most likely to be affected by the radiation. The free radicals produced are often short lived but they may produce more stable molecules which can cause damage within the cell.

Answer 342

- Damage to the nucleus of the cell: This is most likely to be observed as it affects the existing cell and all future cells produced from its chromosomes when it divides. Such a change in the DNA is called a mutation. Rapidly dividing cells such as the skin and gut are more easily affected because their cells are more genetically active. [this may mean the cell cannot function properly and may die. Lower levels of damage may cause no long-term effects as the intact nucleus can co-ordinate the repair of the damage.]

Answer 343

"Exposure to a substance or symptoms that appear rapidly" These are a collection of health affects which appear quickly. If radiation is received over a shorter period of time then more damage is likely as there may be more damaging free-radical interactions and the cells have less time to repair themselves. If a person receives very large doses of radiation, for example, in a nuclear power accident, the impact will be severe and can cause rapid death as a result of damage to the bone marrow, immune system, and the gut causing haemorrhage and blood loss.

Answer 344

"Exposure to a substance or symptoms that appear over long periods of time" effects which appear slowly and in proportion to the radiation doses received

Answer 345

"Issues related to general body cells, excluding gonads." damage to general body cells and organs

Answer 346

"Relating to ovaries and testes." damage to cells in ovaries or testes

Answer 347

-Exposure should be: As Low As Reasonably Achievable (ALARA). -Equipment should be: Best Available Technology Not Entailing Excessive Cost (BATNEEC). -The use of Risk:Benefit analysis.

Answer 348

ALARA: the situation should be managed such that the exposure should be: 'as low as reasonably achievable' (ALARA)

Answer 349

BATNEEC: the low exposure can be achieved by using the Best Available Technology Not Entailing Excessive Cost (BATNEEC). The assessment of 'Excessive cost' depends upon the level of risk and the ease with which adequate safety can be achieved.

Answer 350

"A method comparing risks and benefits of an activity for decision making. " No activity is completely safe. The risk of engaging in the activity must be compared with the benefits to decide whether the benefits outweigh the risks and whether the risks can be reduced. The benefits are often obvious in the new activities that become possible, but the risks can be much more difficult to assess. Assessing the risks and benefits of using ionising radiation can be difficult for example: - symptoms may take a long time to develop, especially those caused by chronic exposure to low doses - some effects of exposure to ionising radiation may be difficult to identify as there may be alternative causes of the same symptoms - accurate data on the impacts on humans is often not available - accurate data on exposure is often not available following accidental releases - the people who benefit from the use of ionising radiation and those who take risks may not be in the same place, for example, the people who benefit from nuclear electricity may live in a different country from the miners who extract the uranium fuel used in the power station. - the risks associated with using radioactive materials may be offset by the reduction of other risks, for example, the risks of using x-ray photography must be offset by the reduced risk of invasive surgery.

Answer 351

-Closed sources to prevent contamination. -Radiation absorbers. -Distance from source: the inverse square law. -Reduced period of exposure. -Worker monitoring at work/on leaving work.

Answer 352

closed sources prevent workers from coming into direct contact with the source by enclosing a radioactive source in a container. Workers are not contaminated by picking up radioactive material which would have continued their exposure when they moved away from that location. A closed source of alpha-emitters may reduce exposure to zero as the container will probably absorb all the radiation. Remote handling techniques can be used to minimise contamination. If the source cannot be enclosed then the worker can wear a sealed suit with a separate air source.

Answer 353

if possible, materials should be used as barriers to prevent the radiation from reaching the workers. The choice and thickness of the material used will depend upon the type of radiation involved and the space available.

Answer 354

radiation follows the inverse square law so when the distance from the source is increased there is a more than proportional drop in exposure. So, doubling the distance from the source reduces the exposure to one quarter of its previous level. 1 dose received = ------------------- Distance²

Answer 355

worker arrangements should minimise the time a worker is close to the source.

Answer 356

- protective clothing can be used to minimise contamination - decontamination: washing, scrubbing and exfoliating scrubs remove surface contamination. Swallowing stable potassium iodide tablets prevents uptake of radioactive iodine - worker monitoring: monitoring the work environment and testing the workers themselves can be used to ensure exposure is kept low. A range of monitors may be used: - personal dosemeters which give a reading of current exposure - photographic film badges which measure long-term measure exposure - air monitors to detect atmospheric particles, including alpha-emitters - contamination monitors which monitor workers as they leave the premises and detect any contamination

Answer 357

-High-level waste. -Intermediate-level waste. -Low-level waste.

Answer 358

origin of the waste: used uranium fuel rods - split nuclei from highly radioactive isotopes storage method: Vitrification - dried powdered solid waste mixed with molten glass and allowed to solidify in stainless steel containers, surrounded by concrete to absorb radiation. Air cooling removes the heat of radioactive decay. In the UK it is stored at Sellafield, Cumbria.

Answer 359

origin of the waste: The metals tubes that surrounded the fuel rods become radioactive in the reactor. Filters from waste reprocessing. storage method: Mixed with cement and stored in stainless steel drums. In the UK it is stored at Sellafield

Answer 360

origin of the waste: General equipment and clothing that become contaminated by coming in contact with radioactive material storage method: Sealed in thick polythene bags, inside steel drums, inside steel truck containers in a concrete-lined landfill site. In the UK it is stored at Drigg near Sellafield.

Answer 361

origin of the waste: waste solutions from used fuel reprocessing and storage storage method: Filtered, including ion exchange, then discharged.

Answer 362

origin of the waste: Gases released from used fuel during storage and reprocessing. storage method: Filtered then released.

Answer 363

"Predicting pollution risk by assessing effluent routes"

Answer 364

"Monitoring pollutants focusing on the most at-risk public members"

Answer 365

Normal discharges from nuclear establishments release very small amounts of radioactive materials. However, it cannot be assumed that they will be dispersed and diluted so that the risk drops to an insignificant level. It is possible that natural processes may concentrate them in locations where they could be hazardous. Critical pathway analysis identifies the possible environmental routes that radioactive materials may take in the environment after release. The analysis makes it possible to predict where discharges could cause problems by becoming more concentrated. CPA involves the following factors: - the physical state of the effluent - solid/ liquid/ gas/ solution; - density; - meteorological conditions that determine atmospheric dispersion including wind speed and direction; - river flow and ocean currents; - the physical nature of the environment including its geology - porous/ permeable, vegetation cover; - effects of pH and oxygen availability on solubility; - bioaccumulation and food-chain concentration; - food sources and consumption by local people; - half-lives of isotopes involved.

Answer 366

If there is concern about radioactive contamination it is important to determine the level of risk to people. The effective way to do this is to review the risk to the Critical Group. This group is comprised of those members of the public who are most at risk because of where they live, where their water comes from, what they eat, what they do in their spare time, and where they work. If the Critical Group is found to be safe then all other members of the public should be safe as well. There is no need to monitor all members of the public. The Critical Group does not include occupational workers who are monitored in other ways. Factors that would be considered in identifying the critical group: - where individuals live in relation to the source; - time spent outside, for example, farmers, dog walkers, anglers, walkers; - sources of food, for example, local food: milk, seafood, vegetables; - source of water, for example, a local well. The critical group near one nuclear establishment was identified as livestock farmers who lived downwind of the establishment, who worked outside, grew their own vegetables, ate meat and milk from their own farms, and obtained their water from a local well.

Answer 367

If places in the environment, where radioactive materials are likely to be most concentrated, are identified and monitored and it is established that levels are found to be acceptable, then it us assumed that everywhere else is safe. However, it is important to recognise that this assumes that the pathways have been predicted correctly. Atmospheric dust, soil, water, grass, milk, meat, fish and vegetables should be assessed as they are the materials that are most likely to be contaminated ad those that indicate direct risk to humans.

Answer 368

*Critical Pathway Analysis (CPA). CPA involves identifying the most likely route a material will take, based on its properties and features of the environment, eg: -wind and water current velocity and direction -geology and hydrology -food chain pathways. Environmental sampling: -atmospheric dust -soil -water -seaweeds, molluscs, fish milk, vegetables, meat. *Critical Group Monitoring (CGM). CGM involves identifying those members of the public who, because of their lifestyles, are most at risk. They are monitored. If they are safe, everyone else should be safe too.

Answer 369

- state of matter: solid/liquid/gas eg lead dust, acid mine water drainage, sulfur dioxide, CFCs → gaseous and liquid pollutants have potential to travel further - depends on velocity of wind/ currents and direction. eg of transboundary pollutants eg acid rain in Scandinavia, Cs-137 chernobyl. Denser pollutants eg lead source (unless mobile through food chains) - energy from eg noise, heat, light, ionising radiation → noise, light may have local/restricted impacts ionising radiation → local regional, transboundary - persistence eg high persistence - CFCs, organochlorine insecticides - DDT - low persistence - sewage. pyrethroid insecticides → affected by environmental conditions such as abiotic factors : oxygen availability, temperature (thermal degradation), light (photodegredation), Ph, presence of other pollutants, topography, temperature inversions and biotic factors such as presence of bacteria (biodegredation) - Reactivity/ chemical stability eg CFCs low reactivity except in the presence of UV light NOx, ozone, hydrocarbons high → reactive pollutants may degrade quite quickly eg sewage or react with other pollutants to produce more toxic secondary pollutants. eg as in photochemical smog Rate of degredation/ reactivity affected by abiotic factors: oxygen, temperature, light, pH chemically stable pollutants may remain in the environment for a long time - adsorption attachment to soil or sediments → can immobilise pollutants until disturbed eg PCBs - solubility in lipids/ water eg DDT in lipids, nitrates in water → water soluble pollutants easily dispersed. Liposoluble pollutants can bioaccumulate and biomagnify impact on living organisms and food chains/ webs - synergism (two pollutants interact to cause a more serious effect) → examples to illustrate eg ozone and sulfur dioxide in acid rain damaging coniferous forests - specificity (variations in toxicity to different groups) → eg pyrethroid insecticides have high toxicity to insects and low toxicity to mammals - toxicity (how poisonous a substance is eg CO, lead, cyanide) → inhibits enzyme action. CO binds to haemoglobin instead of O2. Lead inhibits enzyme action in nerve cells. Cyanide inhibits aerobic respiration enzymes - carcinogenic action (mutagens that cause cancer eg asbestos, radon → causes uncontrolled cell division in various tissues to produce an undifferentiated mass o cells known as a tumour - mutagenic actions (cause change in DNA structure - mutations eg ionising radiation/ UV/ PCBs → gonadic effects - abnormality in offspring/ somatic effects - cancers - teratogenic action normal gene expression inhibited affecting foetal development eg mercury → cause birth abnormalities in offspring. The birth abnormality cannot be inherited by future generations because the DNA structure is not affected methods/ strategies to reduce impact the following can be applied for most pollutants. 1) monitoring: a) to identify and predict pollutant mobility post discharge: critical pathway analysis b) to identify health risks from pollutants and those members of public at greatest risk; critical group monitoring 2) control technologies to: reduce production and release 3) development of alternatives. substitutes to perform the same function as original

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