Geography - Environment and Wellbeing Flashcards
What do we mean by air quality?
Synonymous with air pollution
“Air pollution is defined as a mixture of gases and particles that have been emitted into the atmosphere by man-made processes”
Short-term and long-term effects on health, and to the natural environment
“The air quality in Scotland is generally better now than it has been at any time since before the Industrial Revolution.”
How can we compare air quality with water quality: physical, chemical and biological aspects of water?
Physical – temperature, suspended solids, radioactivity, conductivity, turbidity, colour/taste/odour
Chemical – solute load: water a universal solvent
Biological – living organisms supported in/by water
What incident regarding smog had London seen in the 1950s?
Smog – a mix of smoke and fog
Atmospheric conditions prevent the dispersion of pollution
One of the worst cases known was the Great Smog of December 1952 in London:
In some areas, people could not see their feet!
4000 deaths
Coal-burning fires
Clean Air Acts 1956 and 1968
Emissions of black smoke banned
Introduced requirement for use of smokeless fuels
What evidence has been shown regarding air quality problems?
300-year old burial ground discovered
20 000 skeletons from over 170 yrs
Analysis of human bones reveals evidence of epidemic of childhood deaths
Shift from wood-burning to coal coincident with childhood mortality
What is the structure of the earth’s atmosphere?
50% of atmospheric mass is in lowest 5-6 km above surface
Total mass of atmosphere: 5.1x1018 kg
Total mass of hydrosphere: 1.4x1021 kg
What is the atmosphere made of?
Nitrogen N2 78.08 Oxygen O2 20.94 Argon Ar 0.93 Carbon dioxide CO2 0.03 (variable) Neon Ne 0.0018 Helium He 0.0005 Ozone O3 0.00006 Hydrogen H 0.00005 Water vapour H2O variable: ppm to %
What is the difference between primary and secondary pollutants?
Primary: directly emitted into the air e.g. particulates, SO2, CO, NOx, various hydrocarbons (HC)
Secondary: produced through reactions between primary pollutants and normal atmospheric compounds
e.g. ozone forms over urban areas as a result of chemical reactions involving primary pollutants, sunlight and naturally-occurring gases
State naturally occurring pollutants.
Release of sulphur dioxide (SO2) from volcanic eruptions – volcanic smog (“vog”)
Hydrogen sulphide (H2S) emissions from geysers, hot springs, bogs & marshes
Ozone (O3) formation in lower atmosphere caused by thunderstorms/lightning
Products of windstorms and wildfires
Natural hydrocarbon (HC) seeps
Natural emissions may exceed human emissions, but not in urban areas
What is sulphur dioxide? (SO2)
Naturally occurring gas
Released in burning fossil fuels – esp. coal in power stations
Complex oxidation reactions can cause conversion into particulate form – then removed by wet or dry deposition
Death and injury to plants and animals, inc. to the lungs
Contributes to acid rain formation
What is nitrogen oxide? (NOx)
Principally nitric oxide (NO) and nitrogen dioxide (NO2)
Both contribute to smog
NO2 contributes to acid rain
May be converted by complex reactions into NO32- ion within water droplets
Nearly all NO2 is anthropogenic – principally from vehicle and fossil fuel power stations
Human effects – irritation of eyes, nose, throat, lungs; increased susceptibility to viral infections.
May suppress plant growth, but fertilise soil in nitrite form.
What is carbon monoxide? (CO)
Toxic to animals (inc. humans) at ‘low concentrations’
Toxicity arises from natural attraction between CO and haemoglobin in blood (250x greater attraction than to O2)
High risk of asphyxia when incomplete combustion occurs CO monitors (CO: “silent killer”)
In UK each year, 50 people die and 4000 hospitalised due to CO poisoning
1 in 10 thought to have suffered CO poisoning
Global emissions principally through vehicle tailpipes
Reducing owing to cleaner-burning engines, despite growth in vehicle numbers
Name characteristics of the ozone (O3) and other photochemical oxidants.
Originates with burning fossil fuels (inc vehicles exhausts), creating NO2
Formed by effects of sunlight on NO2
Ozone is unstable, so available to support burning/oxidation not allowed by O2
Because of its chemical activity, O3 very harmful to living things, but in the stratosphere, it helps protect Earth from solar UV rays
Causes damage to animals, plants, rubber, paint, textiles…
What are volatile organic compounds?
Organic compounds used as solvents in industrial processes, e.g. dry cleaning, de-greasing
Hydrocarbons include one group of VOCs
Thousands of HC compounds exist – inc. natural gas (methane – CH4), butane (C4H10) and propane (C3H8)
Some VOCs found in urban air cause photochemical smog
Many are directly toxic to plants and animals – or may form other harmful compounds through chemical reactions in the atmosphere
What is particulate matter?
Sources include: Asbestos Bare soils Volcanic eruptions Heavy metals (As, Cu, Pb, Zn…)
Some particulates are invisible to the eye – below ~ 7 µm (human hair is 60-150 µm in diameter)
Easily inhaled into lungs – embedded into lungs, arteries or carried in blood
Particulate air pollution estimated to cause 60 000 premature deaths annually in USA
What is lead?
Formerly used as additive to petrol
Still used in batteries
Widely spread with vehicle exhausts into soils take-up by plants terrestrial food chains
Transport in waters to the rivers and oceans aquatic food chains
Found in Greenland ice cores, i.e. worldwide distribution
Use in petrol discontinued in UK in 1999
Industrial emissions remain
Impact on brain function
