L2 - Definitions and Types of Pollution and Pollutants Flashcards
How does Mellanby define environmental pollution (environmentalist view)?
“…the introduction of foreign materials into the environment should be kept at a level at which no detectable biological change results.” - outlines perspective about foreign materials and biological change
What is the economic view of environmental pollution?
“Discharge or other actions which occasions economic damage to man” - things that cause damage to man
What is Holdgate’s definition of pollution (1979)?
“The introduction by man into the environment of substances or energy liable to cause hazards to human health, harm to living resources and ecological systems, damage to structures or amenity, or interferences with legitimate uses of the environment.”
Describe Holdgate’s definition of environmental pollution
- More detail
- Detects humans as the cause of environmental pollution, hazards to human health
- More of a full definition
- More key terms
What is the U.S. President Advisory Committee in Environmental Pollution definition of EP (1965)?
“…environmental pollution is the unfavourable alteration of our surroundings wholly or largely as a by-product of man’s actions, through direct or indirect effects of the change of patterns, radiation levels, chemical and physical constitution and abundance of organisms. These changes may affect man directly through his supplies of water and agricultural or other bodies, his physical objects or his opportunities to recreation and appreciation of nature.”
Describe the definition of environmental pollution by US President Advisory Committee on Environmental Pollution (1965)
- 1965 = midst of the Cold War - radiation levels
- Energy patterns - thermal? (amongst others)
- Reference to populations of organisms (“abundance”)
What is the current definition of environmental pollution from USA Environmental Protection Agency?
“…any substance in water, soil, or air that degrade the natural quality of the environment, offend the senses of sight, taste, or smell, or a health hazard. The usefulness of the natural recourse is usually impaired by the presence of pollutants and contaminants.”
Describe the USA EPA current definition of Environmental Pollution
- A little more brief
- Talks about visual intrusion/taste/smell & health hazards
- Refers to how we use natural resources - by whom or what?
What are the common characteristics of pollution events?
- The pollutant = causes the effect
- The source(s) if the pollutants
- The transport medium (air, water, and/or soil) (could be more than 1)
- The target (organism, ecosystem or object - sometimes receptor)
- Helps identify pollution events and how they work
What is Holdgate’s Pollution Model?
- Model illustrating the processes involved in pollution
- Have 4 common elements represented
- There are additions and extensions to the idea
- Rate of transport is critical
What might happen when a pollutant reaches its target?
- May not have the same chemical form as what was released from the source - May undergo chemical transformations whilst moving through the environment
- Amount of pollutant teaching the target is critical - pollutant undergoes different processes
- When pollutant reaches the target it may not have a direct effect - could also be processes within the target - organisms may excrete pollutants
What are the common approaches to pollution transport?
- Source (e.g. agriculture)
- Media affected or travelled through (air, water, land)
- Nature and properties of the pollutant (e.g. heavy metals, organic material, sewage)
What are the sources of pollutants?
- Discrete point sources = readily identify exactly where it is released into the environment
- Diffuse (nonpoint) sources = things in which pollutants come from or are applied to a wide area without a specific source point
What are examples of discrete point sources?
- Sewage effluent pipe
- Industrial wastewaters
What are example of diffuse (nonpoint) sources?
- Acid rain
- Fertilisers
- Pesticides
What are sources of pollution?
- Agriculture
- Electricity generation (byproducts from fossil fuel combustion)
- Derelict has works (used to gasify coal)
- Metal mining (chemical residue)
- Metal industries (gaseous discharges, byproducts, metal cocktail)
- Urban & industrial sources (Road runoff = cocktail of pollutants - car tyres, vanadium & fuel hydrocarbon residues)
- Waste disposal (legacy landfills = leachate’s)
- Transport (tyre particles/hydrocarbon residue, carbon di/monoxide)
What are effect-generating properties?
What the effect is of the polluter in the target of the receptor
What are examples of effect-generating properties?
- Toxin = effect is toxic and could be lethal or sub lethal on living organisms
- Corrosion of metals = acidification of rain water corrodes metal structures which runs into ground water
What are pathway-determining properties?
- Properties that determines where a pollutant goes in the environment
- Includes the distance travelled, rate of dispersion
- Where it goes to is determined by the pathway it takes
What are examples of pathway-determining properties?
Primary settlement tank in sewage works:
- Scum on top of water is called FOG (fats, oils & greases) all of these rise to the top because they are hydrophobic - skimmed off the top as it goes through treatment works
- Different properties means where it ends up is different than the rest of the water
What are primary pollutants?
Pollutants that exert harmful effects in the form which they enter the environment
What is an example of a primary pollutant?
Discharge pipe has a direct effect in its primary form
What are secondary pollutants?
Pollutants that are synthesised as a result of chemical processes in the environment, often (not always) from less harmful precursors (chemical change or process) - less harmful precursors are something relatively benign but becomes a problem because it changes as it moves through the environment
- Referred to by a specific part of Holdgate’s model that deals specifically with chemical transformations in environmental media
What is an example of a secondary pollutant?
Microplastics
What are the key aspects of transport and dispersion of pollutants?
- Fluid media = water & air (both behave as fluid in a physical sense)
- Settlement and leaching of liquids (driven by gravitational forces)
- Anthropogenic (transport and placement)
What are the 2 key mechanisms in the transport and dispersion of water?
- Advection (aligns with gravity) = movement of a pollutant with water mass
- Diffusion (driven by turbulence & particle motion) = spreading within water mass
What is an example of advection?
Ink speeding down-stream
What is an example of diffusion
Ink speeding outwards/widening in water
What results from a mixture of advection and diffusion?
A loss in concentration of pollutant in water
What restricts the vertical movement of pollutants in ponds/lakes?
- Depth of water body
- Stratification (layers within water body)
How does accumulation of pollutants in water occur?
- When there are inputs without loss
- Can become sinks for pollution (net accumulation)
- Lakes & seas
- Lakes & sea sediments
How is the oceanic system an example of net accumulation of pollutants?
Things that are delivered don’t tend to be removed e.g. the sea is saline because evaporation doesn’t remove the salts that are washed in
What is stratification?
Layering of water in water body
What is the impact of stratification?
Impacts the way pollutants have an effect on aquatic ecosystems and in the way they move through the system
What does stratification underpin?
Temperature and density of water
What does density of water depend on?
Temperature of water
How does density of water effect buoyancy?
Less dense = more buoyant
How does temperature, density & buoyancy interact?
- If decrease temp. of water from 4 degrees C to 1 degrees C water becomes less dense and more buoyant
- Water at 8 degrees C is more buoyant and less dense than at 4 degrees and therefore will float in top unless disturbed
At what temperature is water at it’s most dense (least buoyant)?
4 degrees C
What happens to stratification of a lake during the winter?
- Less dense cold water sits over warm, more dense water = physical separation
What happens to the stratification of a lake during spring months?
- Wind rises and mixes the water
- Low solar heating
- Solar heating could make the surfaces of the water warmer and therefore more buoyant but wind prevents this through overturn
- Not strong enough buoyancy difference
What happens to the stratification of a lake during summer months?
- Generally, in northern hemisphere there is more sun and less wind
- Solar warming makes the surface water warmer and less dense which floats over cooler layer
- Less wind means stratification isn’t disrupted
- Summer stratification
What happens to the stratification of a lake during the autumn months?
- Levels of solar radiation reduce and wind increases
- Less warming and more mixing
- Autumn overturn
- No density difference
What happens when stratification occurs?
- Separation of water layers
- Limited mixing between epilimnion (upper) and hypolimnion (lower)
- Thermocline separates layers
What happens to a pollutant during stratification of water?
- If there is a pollutant in the hypolimnion it won’t mix through to the epilimnion
- Entrapment of pollutants
- Makes a big difference to how pollutants work and how the water body is effected
What does the dispersion of pollutants in air depend on?
- The height the pollutant can reach in the atmosphere
- Particle size
- Climate factors
What is important about air being a fluid medium?
- Diffusion and advection processes also occur (like in water)
- Shares concept and pollution transport in water
Human society lives how many meters from Earth’s surface?
First few 100m
What is the boundary layer in the atmosphere?
- The area where the velocity in air movement increases
- When it levels out and becomes uniform this is the top of the boundary layer
Where is the velocity of air movement low?
Very close to the Earth’s surface
What happens to air velocity as you get higher in atmosphere?
Velocity of air movement increases - gradient of increase in velocity from the Earth’s surface
What is the size of particles at atmospheric boundary?
1-10um
What pollutants can travel to troposphere (up to 10-16km)?
- Gases & aerosols (<5um)
- Transferred by plumes, thermals and elevation (mountains)
What exchange occurs at the equator?
Some exchange between troposphere and stratosphere - mainly separated
What is meant by a ‘constrained system’ in the stratosphere?
- Gases in the stratosphere tend to stay there (no “wash-out”)
- Unless they are degraded
How can gases be degraded in the stratosphere?
- Strong radiation above ozone layer = higher in the atmosphere
- Absorbance of radiation decreases so radiation is stronger and can precipitate our in different chemicals
Why is there limited cross-equator exchange of air pollutants in the troposphere?
Constrained by hemispheres and air convection cells
Describe dispersion in the horizontal plane
- Generally less restricted than dispersion in the vertical plane
- Transport tends to be with wind in the (turbulent) boundary layer - structures on wait that and the topography means that dispersion is more rapid horizontally than vertically
- Tend to determine where and how pollutants move in air masses
- Turbulence and this dispersion is controlled by solar radiation (patterns), wind speed, cloud cover and topography (roughness and landforms make rougher wind)
What happened when pollutants are absorbed in soil?
- Soil is physically associated with the surface and sticks to it
- Different association determines how pollutant travels through soil (e.g. absorbed = won’t travel through soil matrix)
What affects how pollutants are bound/absorbed in soil?
- Quality of soil makes a big difference
- Capacity if pollutant to absorb
- Association between soil and pollutant
Why is strength of absorption between soil and pollutant important?
- Determines whether the pollutant is retained within the soil is whether us flows through
- If there is a strong association/bond then what happens to the soil will happen to the pollutant - fates are interlinked
Where can phosphorous (P) be in soil?
- Can be structural element in soil
- May be around particle in water
- May be absorbed/stuck to the surface
What happens to Phosphorous (P) in soil if you add more P e.g. P based fertiliser?
- Won’t see any difference of concentration of P inside soil particle
- More P is absorbed (stuck to side)
- More P in water
- Won’t change P in soil particle itself but only increase P in soil system and some P will remain in free solution around particle
What happens if you reduce the amount of Phosphorous (P) in soil matrix?
- Equilibrium will be maintained
- Some P stuck to surface of soil particle will be released into surrounding water
- No change inside soil particle
What happens to Phosphorous (P) around a soil particle?
- Some = exchangeable
- Can attach to surface or be released
What is assumed about Phosphorous (P) within a soil particle?
- Assumed to be fixed and non-exchangeable
- Unless break soil particle open
What happens to non-exchangeable Phosphorous (P) within the soil matrix?
Goes wherever the soil particle goes
What happens to exchangeable P within the soil matrix?
- P around soil particle absorbed to the side might go where the soil goes or might be washed through depending on bond
- P in surrounding water will be washed through soil
What are important factors that impact how pollutants are transported through soil?
- Soil composition and structure
- Wet/dry = dry soil/no wet phase - pollutant won’t flow through
- Anaerobic/aerobic = different chemical reactions
- Acid/Alkaline = change absorption/chemical structure
- Minerals
- Clays
- Humus
- Hydrous
- Oxides of rock-derived metals
- Ionic composition
What matters in terms of pollutant properties?
- Physical and chemical structure
- Polar/non-polar = capacity to associate with soils depends on their structure and affinity
- Hydrophobic/hydrophilic
- Liquid
- Gas
- Colloids
Describe the soil textural triangle
- Wide-range of would types which correspond to a specific mixture or mixtures of clays, silts and sands
What is important about sans having an open structure?
Water can run through quickly, largely inert to most interactions with pollutants
What is important about clay being watertight?
Water can be mixed in very much slower and becomes sticky - same for pollutants - clay can be bound to pollutants that have similar properties
What are the variations in soils?
- Depth (profile) at a location
- Surface = more organic
- Further down = more mineral (stony)
What happens if a pollutant hits a more organic part of soil?
Probably stay there
What happens if a pollutant hits more mineral rich soil?
There are different attributes it encounters which might mean the absorption rate might change
What happens to water/pollutants when they hit dry soil?
- Will go through the cracks
- Accelerated movement down through soil
- Only soil they will encounter is inside faces of cogs of earth
- No percolation
What happens when water/pollutants hit a wet ploughed field?
- Percolate downwards
- Encounter more soil more slowly through the system
- Ruts from ploughing great potential river channels = water/pollutants can be washed out quickly into other systems e.g. rivers
What is the exposure pathway of air pollution?
Inhalation
E.g. urban environments associated with internal combustion engines
What is the exposure pathway of water pollution?
Direct consumption
E.g. drinking polluted water
E.g. ingestion if aquatic organism - eating fish contaminated with microplastics or oysters that accumulate toxins through filter feeding
What are the exposure pathways of soil pollution?
Plant pathways, ingestion & diet
E.g. eating plants grown in contaminated land = root systems are absorbing pollutants which are incorporated in the biomass we eat
What are examples of pesticides?
- Insecticides
- Herbicides
- Fungicides
What are pesticides recognised as?
- Global problem - substances appear on priority list
- Ubiquitous = global distribution/widespread - traces found in tissues of Antarctic penguins
How many pesticides are there?
Ca. 10,000 formulations of 450 compounds
Why have pesticides been developed?
To enhance production of agricultural systems and increase yield by removing pests
How do we apply pesticides?
Spraying of in water form
Where to we apply pesticides?
In/on soil or plants
What are the pathway determining properties of pesticides?
- How wet soil is
- Chemical composition of soil
- Soil structure
- Affinity of pollutant to soil
What are types of indoor pollution?
- Fabric of a building (e.g. asbestos = asbestosis)
- Importing substances (e.g. lead workers = people working in lead industry would become saturated with particles on their clothes, take home and expose family)
- Activities (e.g. office working = photocopiers)
How did hat making in Victorian times act as a indoor pollutant?
- Made hats out of beaver pelts
- Stirred bags of boiling mercury nitrate solution with no PPE in closed room
- Inhaled fumes
- Short exposure pathway (direct - little dilution)
