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ENVIRONMENTAL SCIENCE 4. Pollution > General and Properties > Flashcards

General and Properties Flashcards

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1
Q

What is pollution?

A

energy or matter released into the environment with potential to cause adverse changes to an ecosystem
- usually caused by human activities but similar effects can be caused by natural events

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2
Q

What is the difference between pollution and pollutants?

A

POLLUTION is the undesirable change in the environment
POLLUTANTS cause the damage to the environments

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3
Q

How can we split pollution damage into two categories?
Give examples

A

DIRECT e.g. effluent discharge from factories or wastewater treatment plants which can kill aquatic organisms
INDIRECT e.g. sulfur dioxide emissions cause acid rain which can damage or kill trees and crops

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4
Q

How can we split the causes of pollutants into two categories?

A

Natural or anthropogenic

but the effect they have on the environment remains the same

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5
Q

How do we classify pollution?

A

based on the part of the environment which they affect, or result caused by a particular pollution

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6
Q

What are the major types of pollution?

A

air
water
noise
soil or land

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7
Q

Why do we need to understand existing chemicals?

A

chemical industry produces a large number of new chemicals each year - understanding the behaviour of existing chemicals helps in predicting the behaviour of new chemicals so decisions can be made about setting acceptable emissions, developing control methods and establishing monitoring programmes

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8
Q

Why is it important to understand the properties of pollutants?

A

they determine:
- the length of time it may be a problem
- level of harm caused
- where and how far it will travel

understanding how they cause problems can help anticipate and prevent pollution

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9
Q

How does state of matter affect a pollutant?

A

being a solid, liquid or gas affects a pollutants ability to be dispersed by moving water or air
- in general, solids are deposited close to the source while gases are transported easily in the atmosphere

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10
Q

How does energy form affect a pollutant?

A

the different pollutants that are energy forms such as noise, heat, ionising radiation of light, have widely varying impacts because of the way the energy behaves

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11
Q

How does density affect a pollutant?

A

affects what happens to dispersal of the particles of a solid - the denser they are, the closer to source they settle out
- gases denser than air sink nearer the source and close to the ground if there is insufficient wind to disperse them
- in liquids, denser particles sink more quickly
- denser materials sink nearer the source because they require more kinetic energy to keep them suspended e.g. lead dust = high density

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12
Q

What is and how does persistence and degradability affect a pollutant?

A

= the measure of the length of time that a pollutant remains in the environment before it breaks down chemically (degrades)

long term = generally worse effects, but also could be small amounts over a longer time

short term = generally better, but also could be a huge amount which is impossible to cope with

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13
Q

What is and how does toxicity affect a pollutant?

A

= the effect the thing has on the chemicals in the body, most harm to proteins (enzyme inhibition)

TOXICITY CAN
- inhibit enzymes
- damage nervous system
- damage other organ

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14
Q

How does chemical reactivity affect a pollutant?

A
  • affects severity

Very reactive chemicals do not last long in the environment
- may be highly toxic but are not around long/degrade quickly e.g. acids
- chemicals may react together to make something worse… a secondary pollutant

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15
Q

What is and how does specificity affect a pollutant?

A

= property of toxic pollutants describing variations in how different organisms respond in different ways to the same pollutant

  • specific toxins will affect specific organisms
  • non-specific toxins affect ALL organisms similarly
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16
Q

What is and how does adsorption affect a pollutant?

A

= molecules sticking to the outside of other particles

PROBLEMS: they can be released at a later date when their presence is not obvious, so they will have a bigger impact
BENEFITS: cleans up pollutants/reduces emission volume, can immobilise them

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17
Q

How does solubility affect a pollutant?

A

WATER SOLUBLE pollutants are often super mobile in the hydrosphere
CONS: may affect larger areas, water based effects e.g. eutroph affects whole ecosystem
PROS: reduces concentration and disperses it

LIPOSOLUBLE pollutants are insoluble in water but store well
CONS: pass through phospholipid cell membranes, store in oil/fat deposits in cells
PROS: do not affect large area

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18
Q

What is and how does mobility affect a pollutant?

A

= the measure of the degree to which a pollutant can be carried by wind/water/organisms
- can depend on other properties, especially state of matter, density and water solubility

VERY MOBILE: impact a wider area, but dilution may reduce effect severity

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19
Q

What is and how does bioaccumulation affect a pollutant?

A

= adsorption and storage of pollutants in the tissues of organisms (concentration increases)

  • original dose may have been too small to be toxic, but builds up to toxic levels
  • often involves long term ingestion of a liposoluble pollutant, which are more likely to bioaccumulate than water soluble ones
  • occurs when organisms absorb toxic substances at a rate greater than that at which the substance is lost
  • the longer the biological half-life of the substance, the greater the risk of chronic poisoning even is environmental levels of the toxin are not very high
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20
Q

What is and how does biomagnification affect a pollutant?

A

= increase in conc of a pollutant as it passes along a food chain, becoming concentrated into a progressively smaller biomass with each trophic level

  • orgs at higher trophic levels have longer lifespans and build up higher conc as they are likely to ingest more of the pollutant to keep up with higher metabolic rates (endotherms)
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21
Q

What is and how does synergism affect a pollutant?

A

= 2 or more pollutants where their effects interact to create a different effect t their own individual ones, usually a more serious one

NOT A SECONDARY POLLUTANT - effects no pollutants interacting)

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22
Q

What is and how does mutagenicity affect a pollutant?

A

Mutagens = agents causing changes in the chemical structure of DNA by damaging chromosomes by rearrangement of DNA structures - MUTATIONS

GONADIC: mutation in egg/sperm/embryo
SOMATIC: other general body cells
CARCINOGENIC

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23
Q

How does carcinogenicity affect a pollutant?

A

CARCINOGENS = mutagens that cause cancer
- a substance or energy causing body cells to reproduce in an uncontrolled way, creating a tumour (can be slow or fast)
- the tumour may eventually cause health problems by preventing normal tissue function

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24
Q

What is an how does teratogenicity affect a pollutant?

A

TERATOGENS: chemicals or energy that causes birth abnormalities by preventing normal gene expression
- they do not change DNA structure but inhibit function of proteins and enzymes in an embryo that the DNA would normally have controlled

  • the birth abnormality cannot be inherited by future generations because the DNA structure is not affected
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25
What is a diffuse source? Give examples
pollution from many sources with combined impacts e.g. car exhausts
26
What is a point source? Give examples
pollution from a defined place with a definitive effect e.g. oil spills from a tanker
27
What are the categories of sources for pollution?
point source diffuse source
28
How does persistence and degradability in terms of a pollutant? How do we measure it?
a measure of the length of time that a pollutant remains in the environment before it breaks down chemically (degrades) - measured as the time it takes for half a pollutant to break down (environmental half life) T1/2 ENV
29
Why environmental half life not a precise measure of persistence and degradability?
can be affected by environmental conditions - light - temp - oxygen levels - pH - presence of bacteria
30
What is degradation? How do we categorise degradation? What categories can degradation fall into?
The process of breakdown Categorised according to the feature causing breakdown biodegradation: caused by living orgs, usually bacteria photodegradation: caused by light thermal degradation: caused by heat
31
What are the environmental features that can have an effect on pollution?
- Factors affecting degradation - Factors affecting dispersal
32
What are the features affecting degredation?
Temperature Light levels Oxygen pH Pollutant Interactions
33
How does temperature affect pollutant/pollution degradation?
- most chemical reactions occur more rapidly if the temperature is higher - degradable pollutants (e.g. sewage) will break down more rapidly at higher temps but rapid degradation can increase problems such as deoxygenation
34
How do light levels affect pollutant/pollution degradation? Give an example
Light can provide activation energy that drives chemical reactions involving pollutants e.g. photochemical smogs and the photodegradation of some pesticides
35
How does oxygen affect pollutant/pollution degradation? Give examples
O2 involved in many chemical and biological reactions e.g. aerobic bacterial decomposition of sewage e.g. oxidation of sulfide ores producing sulfur dioxide - oxidation state affects the solubility of many metals
36
How does pH affect pollutant/pollution degradation? Give an example
affects solubility of many substances e.g. heavy metals such as lead are more soluble and therefore mobile under more acidic conditions
37
How do pollutant interactions affect pollutant/pollution degradation?
behaviour of pollutant may be affected by presence of other pollutants e.g. interaction of NOx and hydrocarbons in photochemical smogs e.g. combined effects of phosphates and nitrates in eutrophication
38
What are the factors affected dispersal?
- wind and water currents - temperature inversions - presence of adsorbent materials
39
How do wind and water currents affect dispersal?
Velocity and direction of air and water currents affect how far the pollutant is dispersed and how diluted it will be
40
How do temperature inversions affect dispersal?
IN NORMAL CIRCUMSTANCES: - atmospheric temperatures in the troposphere normally decline with increasing altitude - the temp of warm pollutant gases released at ground level make them less dense/more buoyant than the cooler surrounding air - they can 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 IN A TEMP INVERSION: - under certain circumstances (e.g. rapid cooling at night) the layer of air closest to the ground may be colder than normal - colder air is more dense/less buoyant so any pollutants released released there may also become cold and dense - this inhibits vertical air movement, and atmospheric mixing - this means they cannot disperse easily and become more concentrated
41
What factors/circumstances allow temperature inversions to form?
1. VALLEYS - colder denser air can collect - many cities are in valleys where high pollutant emissions may cause serious problems as they become concentrated during temp inversions e.g. smoke smogs and photochemical smogs 2. LOW WIND VELOCITY - air layers with different temperatures do not rise 3. CLOUDLESS SKIES - infrared energy can be radiated from the ground, allowing the ground to cool down 4. 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 temp inversion to be broken
42
How does the presence of adsorbent materials affect dispersal? Give an example of a substance
Pollutants may adsorb onto materials e.g. clay particles or organic materials in aquatic sediments - adsorption may immobilise the pollutant and stop it causing problems BUT could just store them for release at a later date when we are unprepared e.g. many naturally occurring toxic metal ions are immobilised by being adsorbed onto soil clay particles e.g. aluminium and lead
43
Give an example of where the presence of adsorbent materials prevented/softened a major problem
CHERNOBYL 1986 - radioactive caesium-137 released into atmosphere, then washed out by rain - much of the caesium that was washed into soil has adsorbed onto clay particles, so is immobile and any radiation released is absorbed in the ground
44
What are the general strategies for controlling pollution?
- Critical Pathway Analysis (CPA) - Critical Group Monitoring (CGM) - Emission control strategies - Principles of pollution control
45
What is the purpose of a CPA?
(Critical Pathway Analysis) - to predict movement of potential pollutants in the environment and assess severity and location of pollution that may happen RESULTS: - if potential pollutant is diluted/dispersed/carried to a location where the impacts are acceptable, then no further action may be needed - if potential pollutant is concentrated/carried to sensitive locations, then it may be necessary to control the releases
46
What are the factors that may be included in a CPA?
PROPERTIES OF THE POLLUTANT: - state of matter - density - solubility in water/lipids - chemical stability FEATURES OF THE ENVIRONMENT: - geology -pH - temperature - oxygen availability - wind and water currents
47
What substances are CPAs normally used for? How can we check accuracy of CPAs?
Can be any mobile persistent pollutant BUT is normally for the dispersal of radioactive waste discharges - predicting pollutant pathways means env monitoring can focus on sites at most risk of pollution, with no need for sampling of sites that were never likely to be polluted - env monitoring can be used to check the accuracy of the CPA predictions though
48
What is the purpose of a CGM?
(Critical Group Monitoring) Assessing the risk of public exposure to pollutants, focusing on member of the public who are most likely to be at risk due to their lifestyle = CRITICAL GROUP If the Critical Group risk is relatively low then it can be assumed that the rest of the public risk is even lower - NOT normally used to detect health damage caused by the pollutant, only to monitor exposure and assess potential risks before health impacts occur - if the risk is deemed unacceptable then emissions can be controlled to reduce further exposure
49
What are the emission control strategies?
- Control of emission location - Control of emission timing
50
Why are emission control strategies needed? (physical)
env factors e.g. - air quality - meteorological conditions - hydrology - emission source affect dispersal of pollutants, and some factors can be manage to reduce the effects
51
How does the control of emission location reduce the effects of pollution?
- severity of pollution is affected by the location where the discharges are released - emission location is normally determined by the location of the source by there may be some factors that affect severity MARINE DISCHARGES: - water currents disperse/dilute emissions EMISSIONS DOWNWIND OF URBAN AREAS AQUIFERS - not discharging waste onto the permeable rock above an aquifer
52
How can emission timing affect pollution?
affects severity TIDAL CYCLE 1. emissions while tide is coming in - carried upstream 2. emissions while tide is going out - carried out to sea where they will disperse TEMPERATURE INVERSIONS 1. during - atmospheric emissions less likely to disperse - polluting activities restricted in some cities during, e.g. using diesel vehicles or industrial combustion
53
What are the principles of pollution control?
- polluter pays principle - precautionary principle - selection of control method
54
What is the polluter pays principle?
the organisation of person who causes problems with the pollution is obligated to prevent it - if the cost of preventing the damage is less than the costs of damage then there is clear financial incentive to prevent it
55
When does the polluter pays principle work best?
- if there is little chance of the polluter escaping their responsibilities - the incentive to comply is greater if the financial penalties are high
56
What is the precautionary principle?
assuming that a waste will cause pollution if released, until proven otherwise by research - much safer than releasing waste that has not yet been analysed in the hope it is safe, then waiting to see if problems occur MEANING: being unaware of a problem that is not yet understood is not an excuse and does not reduce responsibility
57
What are the pollution control methods?
- production prevention - prevention of release - post-release remediation - alternative processes
58
Give an example of production prevention as a pollution control strategy
Desulfurisation of fossil fuels before combustion
59
Give examples of prevention of release as a pollution control strategy?
- electrostatic precipitators for smoke control - catalytic converters for NOx, CO and hydrocarbon control in vehicle exhaust emissions
60
Give examples of post-release remediation as a pollution control strategy
- oil spill clean up methods e.g. adsorption with hair - phytoremediation of land contaminated with heavy metals
61
Give examples of using alternative processes as a pollution control strategy
- electric vehicles instead of diesel/petrol - pyrethroid insecticides instead of organochlorides e.g. DDT - renewables instead of fossil fuels
62
How efficient is pollution control?
CONTROL = EXPENSIVE - not a linear relationship between cost and efficiency of control - rarely practical to reduce emissions to 0 because the impact of low levels may be acceptable so paying for controls for a higher standard may be unnecessary - decisions must be made about acceptable level of emission
63
What approach should be used to control and efficiently find the acceptable level of emissions?
ALARA - As Low As Reasonably Acceptable This can be achieved by selecting new equipment that is BATNEEC - Best Available Technology, Not Entailing Excessive Cost
64
What changes must be brought about to achieve acceptable environmental conditions?
changes in emission controls - as industries/cities grow the number of pollutant sources may - so methods originally used may no longer be sufficient - must use an ITERATIVE approach

ENVIRONMENTAL SCIENCE 4. Pollution (2 decks)

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