pollution Flashcards
what is pollution?
-a term given to a wide variety of events and processes that do harm to the planet, especially to living organisms
what can pollutants be?
-either a material (co2, oil) or forms of energy (noise, radiation)
-they do harm by causing changes that wouldn’t normally have occurred
-pollution is usually caused by human activities, but similar effects can be caused by natural events such as volcanic eruptions, natural oil leakage & forest fires
what are the properties of pollutants?
-state of matter (liquid, solid, gas)
-energy form
-absorption
-bioaccumulation ability
-biomagnification ability
-synergism
-mutagenic action
-carcinogenic action
-teratogenic action
-solubility in lipids/water
-reactivity
-toxicity
-persistence
-density
what is absorption?
pollutants become attached to the surface of materials
what is bioaccumulation?
-process by which the amount of 1 substance within an organism increases
what is biomagnification?
-substances that bioaccumulate may become more concentrated as they pass along a food chain
what is synergism?
-involves two or more pollutants where their effects interact to create a different effect
what is mutagenic action?
-agents which cause changes in the chemical structure of DNA
-somatic effects= a change in DNA may cause a cell to behave abnormally. effect cells
-gonadic effects= effects sperm & eggs, can be passed onto future generations
what is carcinogenic action?
-mutagens that cause cancer
what is teratogenic action?
-teratogens cause birth abnormalities by preventing normal gene expression
what factors affect the dispersal of pollutants?
-water currents
-air and wind currents
-temperature inversions
-presents of adsorbent materials
what are air and wind currents?
-the velocity and direction of air, wind and water currents will affect how pollutants are dispersed:
•how far pollutants are dispersed
•the direction and area it disperse over
•how much the pollutent is diluted
how do pollutants normally disperse?
-temperature in the troposphere normally decline with increasing altitude
-this allows pollutant gases to rise, disperse and become diluted
-because the warm air causes the pollutants to become less dense & more boyant
what is temperature inversion?
-a temperature inversion is a break from normal troposphere temperature gradients
-air higher in the troposphere is warmer than air closer to the ground
what factors affect the formation of temperature inversions?
-valleys- colder,denser air can collect
-low wind velocity- temp layers don’t mix
-cloudlessness- infrared energy radiates out allowing the ground to cool more quickly
-water vapour- if mist or fog forms close to the ground this reflects more sunlight, so ground is warmed less
what effect do temperature inversions have on the dispersal of pollutants?
-pollutants become trapped by the temp inversion
-they remain more dense and less buoyant
-so don’t disperse and dilute
-the pollutants become concentrated and can form smogs and photochemical smogs
what is presents of absorbent materials?
-pollutants may absorb onto materials such as clay particles or organic materials in aquatic sediments
-adsorption may immobilise the pollutant and stop it causing problems
what factors affect the degradation of pollutants?
-link: persistence-measure of the length of time a pollution remains in the environment before it’s chemically broken down
-temp
-light levels
-oxygen
-pH
-interactions with other pollutants
how does temp affect the degradation of pollutants?
-chemical reactions occur more rapidly when temps are higher, including biological degradation
-warmer temps also cause deoxygenation of water bc oxygen is less soluble
-case study example-insecticides degrade quicker in warmer temps, mosquitoes become resistant to insecticide, mosquito life cycle time shortens, as temps rise so do survival odds of insecticide resistant mosquitoes
how do light levels affect the degradation of pollutants?
-light levels can provide the activation energy for chemical reactions
-indulging pollutants, such as photodegradation of pesticides
-case study example- photochemical smog is a mixture of pollutants that form when nitrogen oxides & volatile organic compounds react in sunlight
how does oxygen affect the degradation of pollutants?
-oxygen is required for many chemical and biological reactions. including those involving pollutants
-fast flowing and turbulent waters have higher dissolved oxygen levels
-examples- aerobic bacterial decomposition of sewage, oxidation of sulphide ore, producing sulphur dioxide, oxidation of metals
how does pH affect the degradation of pollutants?
-pH can affect the solubility of substances
-heavy metals (eg lead) are more soluble in acidic conditions and therefore more mobile
how does pollutant reactions affect the degradation of pollutants?
-the behaviour of a pollutant can be effected by its interactions with other pollutants
-some interactions may increase the effects of a pollutant or its toxicity
-example-allergens, irritants, and pollutants may inc asthma, NOx and hydrocarbons in smogs, phosphates and nitrates in eutrophication
what is the point source of carbon?
-a single, identifiable source of pollution, such as a pipe or a drain
-industrial wastes are commonly discharged to rivers and the sea in this way
-high risk point source waste discharges are regulated by the environmental protection authority (EPA)
-EPA receives and assess applications to issue licences and works approvals
-licences cover the actual operation of the site, & set operating conditions, waste discharge limits and waste acceptance conditions, as appropriate
what is the non- point source of carbon?
-often termed ‘diffuse’ pollution and refer to those inputs and impacts which occur over a wide area and are not easily attributed to a single source
-they’re often associated with particular land uses, as opposed to individual point source discharges, e.g.:
•urban land use
•agricultural land use
•forestry land use
what is critical pathway analysis?
-used to predict the movement of pollutants in environment
-asses locations that will be affected by the pollutant and the severity with which it will be affected
-if the CPA predicts that the pollutant will be diluted, adequately dispersed or otherwise moved to an area it will cause no damage, no action will be taken.
-if the CPA predicts the pollutant will become concentrated, will not disperse or will be carried to a sensitive location, control measures will be put in place
what do the CPA take into consideration?
-involves identifying the most likely route a material will take, based on its properties & features of the environment
-pH, oxygen, light levels, water currents, air & wind currents
-toxicity, biomagnification, bioaccumulation
how can environmental sampling be used?
-when a pollutant is released the environment is monitored to check if it’s becoming concentrated in places that are considered to pose a threat to humans or areas we consider to be important
-e.g. when soil, water, grass, milk, meat, fish, vegetables, atmospheric dust
-the monitoring program should confirm the accuracy of the CPA
-if levels are found to be acceptable, then it can be assumed that everywhere else is safe, as long as the CPA has been done accurately
what is critical group monitoring?
-assess risk to members of public, who are most likely to be at risk, due to their lifestyle
•where they live
•where their drinking water & food comes from
•what they do in their spare time & where they work
what is polluter pays principle?
-if the person that causes pollution is responsible for problems caused, there is an obligation to prevent it
-if cost of preventing damage caused by pollution are less than cost of damage, there is financial incentive to prevent it
what is precaution principle?
-assumes waste will cause pollution if released, until research confirms it’s unlikely
-safer than releasing a waste that hasn’t been analysed, then waiting to see if problem occurs
what is control method?
-production prevention- desulfurisation of fossil fuels before combustion
-prevention of release- electrostatic precipitators for smoke control
-post release remediation-oil spill clean up methods
-alternative processes- use of electric vehicles rather than diesel or petrol vehicles
what is pm10?
particulate matter less than 10 microns in diameter
what is atmospheric pollution?
-pollutants in atmosphere often behave differently from those in water or on ground
-they move very rapidly due to winds & hence dispersal over a large area
-can interact easily with EM radiation coming from sun
-can interact either infrared energy radiated from the earth
what are particulates?
-smoke is produced by incomplete combustion of material
-smoke made up of atmospheric particulates
-particulates are small particles less than 10 microns
-smoke often contains toxic compounds depending on source
what are sources of particulate matter?
-incomplete combustion
-urban areas- burning coal, diesel, combustible waste
-rural areas- burning of crop waste, fuel wood , grassland, forest
what are smoke pollution control methods?
-legislation- clean air act (1956): restricted use of fuels that produce in large urban areas
-cyclone separators- effluent gases forced to rotate in cylindrical chamber. throws suspended particles to outside surfaces of chamber where they fall and collect ‘fly ash’
-electronic precipitators l- effluent gases passed through chamber with many electrically charged wires/plates. smoke particles in gases attracted to wires/ plates and collect together. ‘fly ash’
-scrubber-uses fine water sprays to wash out suspended solid particulate matter
-bag filters-remove smoke particles from effluent gases by trapping them on fabric filter
what are the effects of smoke pollution?
-on humans- respiratory disease, more difficult to clear inhaled particles & bacteria from lungs
-other living organisms- reduced photosynthesis
-non living objects- smoke particles can damage buildings due to acids
-on climate- reduce temps because high albedo of smoke reflects light. nuclear winter
what are smoke smogs?
-smoke+fog=smog
-fog tends to form when moist air is cooled until it reaches dew point. water vapour condenses as airborne water droplets
-smog has high albedo so temp inversion can last long periods of time, allowing pollutant levels to rise
-london smog (1952)- five days where anticyclonic weather conditions produced clear skies & low wind velocities so temp inversion is formed & pollutant levels rose. around 12,000 deaths
what are the effects of NOx?
-low MOx levels can ciase irritation to eyes, nose, throat, lungs leading to coughing and shortness of breath
-can damage foliage, reduce growth, decrease crop yields
-can react to other pollutants to form ground level ozone, can damage human health and trigger asthma attacks
what are the sources of NOx?
human
-burning fossil fuels
-smoking tobacco
-using explosives
-food manufacturing
-refining petrol and metals
natural sources
-lightning
-bacteria
-volcano eruptions
-oceans
-microbial processes in soil
what are NOx cycles?
-NOx= NO and NO2
-uv light splits up NO2 to give NO and an O atom- combines with molecular oxygen to give ozone
-eventually, NO2 is oxidised to nitric acid, absorbed directly at the ground, converted into nitrate containing particles
how to control NOx?
-catalytic converters
•NOx->N2+O2
-urea sprays
•adblue in diesel cars
•NO+CH4N2O->N2+CO2+4H2O
-control fertiliser use
sources of hydrocarbons
-solvents
-aerosol propellants
-gaseous emissions from fossil fuel exploitation
-unburnt hydrocarbon fuels
effects of hydrocarbons
-lead to global warming
-contribute to smogs
-pollute water- harms aquatic life
-contaminates soil- impacts plant growth & food chains
-inhalation- cancer, respiratory disease
-contact with skin- irritate or burn
