Pollution Flashcards
(63 cards)
Properties of pollutants
State of matter - dispersability
Energy form-noise, heat etc
Density- dispersal, desire materials req more energy to more
Persistence- length of time it remains in the environment before it breaks down
Toxicity
Specificity- more toxic to some groups than others
Reactivity
Primary and secondary pollutant-primary is released by humans
Secondary is produced by chemical reactions between on or more primary pollutants
Adsorption
Solubility is lipids/water
Bioaccumulation - about of substance within an organism increases, long term indigestion of small doses
Biomagnification - substances become more concentrated up the food chain
Synergism- 2 or more pollutants react and create a different effect (usually more serious)
Mutagenic action:
Change chemical structure of DNA
-gonadic effects (cells in ovaries and testes), a mutation in egg or sperm cell may cause birth abnormalities
-somatic affect(general body cells)
A series of mutations can lead to cancer
-carcinogenic action, mutagens that cause cancer
Teratogenic action-prevent normal gene expression, birth abnormalities(mercury)
Mobility
Features of affecting degradation
Temp- durable pollutants (sewage) will break down quicker in higher temp
Lights - can provide activation energy that drives chemical reactions(photochemical smogs)
O levels:
-aerobic decomposition of sewage
-oxidation of sulfide ores producing sulfur dioxide
pH-can lead to higher/lower mobility in acidic/akaline conditions (lead more soluble in acidic)
Pollutant interactions:
-NOx and hydrocarbons = photochemical smogs
-phosphates + nitrates = eutrophication
How is a temp inversion created
The effluent is colder(denser) than the air above, this means that they can’t rise.
Factors where a temp inversion can form
Valleys - colder air can be collected
Low wind velocity - air temp with different temps don’t mix
Cloudless skies - infrared can radiate from the ground, the ground cools down
Mist/fog- water vapour condenses in the cooler ground and has a high albedo, so sunlight is reflected, slowing the heating of the ground (which disperses the temp inversion)
How to pollutants in the atmosphere behave
Rapid movement due to wind, large dispersal
Interaction with UV or visible light from the sun can cause chemical reactions to occur, leading to secondary pollutants
Size range for smoke
PM10<10 microns (diameter)
PM5<5 microns
PM1<1 micron (remain the longest in the atmosphere )
Smoke properties
Can contain toxic chemicals (fluorides, lead, acids)
Can act synergistically with sulfur dioxide
Sources are-
-combustion of coal, diesel
-Combustion of crop wastes, grasslands, wood fuels
Effects of smoke pollution
Respiratory diseases (asthma, lung cancer)
Reduced photosynthesis
Smoke particles can damage buildings, due to the acids they contain
Large scale smoke can reduce temp and they have a large albedo
What is smog
A mix of smoke and fog
What caused the clear air act of 1952
The London smog of 1952 where 12,000 people died (lasted 5 days)
What causes smog
Temp inversions make fog likely, this is them mixed with smoke
Smoke pollution control measures
Legislation-clean air act 1956, restricted use of fossil fuels
Domestic sources- increased use of fuels that don’t produce smoke (natural gas)
Transport sources- diesel particulate filters trap 80% of smoke particles in diesel engines (cars)
Industrial sources:
-electrostatic precipitators, effluent gases go through a chamber of electrically charged wires. The smoke particles in the gas attract to the wires and collect creating “fly ash”
-cyclone separators, effluent gasses are forced to rotate in a cylinder, this throws suspended particles to the side where they fall down and are collected
-scrubber, uses a fine water spray to wash out suspended solids and dissolve soluble gaseous solutions
-bag filters, removes smokes by trapping them on fabric filters
Primary pollutants of photochemical smog
NOx are leased from exhaust gases
Unburnt hydrocarbons come from many sources, unburnt fuel in engine, exhaust gases, spillages
What creates photochemical smog
No2 -> NO + O
O + O2 -> O3
O3 + Hydrocarbons + NO = PANS
Photochemical pollutant effects
NOx- increases risk of respiratory infections
PANS-toxic at much lower concentrations than NOx, eye irritation, asthma, increased risk of heart attacks
Tropospheric ozone- asthma, bronchitis
Control of photochemical smogs
NOx and hydrocarbons can be controlled using catalyst such as platinum in the exhaust pipes of catalytic converters
NOx re-form O2 and N2 (catalytic converter)
NOx can be removed via urea sprays
Hydrocarbons are controlled by:
-catalytic converters (HC + O2 = H2O + CO2)
-vapours at filling stations can be collected
Pollutants involved in acid rain
Sulfur dioxide dissolves into water to produce sulfurous acid
Sulfur dioxide can be oxidised by gasses like ozone to produce sulfur trioxide, which is dissolved to produce sulfuric acid
Oxides of N dissolve and produce nitrous and nitric acids
Effects of acid rain
Non-living-corrodes metal, damaged rail ways, water pipes, overhead pylons. Limestone structures (statues) are damaged
Living:
Direct effect-
Low PH denatures proteins and inhibits enzyme activity, tissues will be damaged. Sulfur dioxide can cause breathing difficulties (asthma)
Indirect effects-
Solubility of ions increases (more soluble at lower PH). ions such as calcium and Mg are lost, and toxic ions will become mobilised (lead). They inhibit enzyme action, and can leach into aquifers and rivers causing harm to aquatic organisms.
Control of acid rain
Natural gas desulfurisation- removal of sulfur from the fuel before it’s burnt.
- natural gas, H sulfide is removed from natural gas by dissolving it in an amine solution or reaction with iron
-crude oil desulfurisation- sulfur components are removed from crude oil
-coal desulfurisation- solid iron pyrites removed via washing and streaming
-wet/dry flue-gas desulfurisation:
Dry- flue gases passes through a bed of crushed calcium carbonate. Sulfur dioxide reacts and produces solid calcium sulfur
Wet- sodium sulfite scrubbing where flue gases are bubbled through a sodium sulfite solution. Sodium H sulfite is produced.
Effects of tropospheric ozone
Plants - toxic and reduces growth rates
Humans - breathing difficulties (asthma)
Sources of tropospheric ozone
NO2 -> NO + O
O + O2 -> O3
Control of tropospheric ozone
Controlling NOx
Carbon monoxide source, effects and control
From incomplete combustion (lack of O)
Effects - binds to haemoglobin in the blood so no O is carried. can lead to death if lost of CO is present
Control- catalytic converters oxidise CO to CO2
Effects of thermal pollution
Proteins are denatured so many aquatic organisms die
A higher temp leads to less dissolved O
Can lead to:
Increased metabolic rates of many organisms, less growth and more energy used
-eggs hatch earlier
-non- indigenous species may thrive and out compete indigenous
-pollutant toxicity is greats as toxins are mobilised quicker
