Atmospheric pollution

?

atmospheric pollution - go over textbook 

problem: 1 billion people exposed to outdoor air pollution, 90% of air pollution in LEDCs comes from oil motor vehicles which are poorly maintained 

primary pollutants: emitted direclty from polluting prcocesses, source be natural/anthroprogenic. greatest emitter fossil fuel combustion creates primary polllutants:  carbon monoxide, carbon dioxide, unburned hydrocarbons, nitrogen oxides, sulphur oxides, particulate matter 

secondary pollutants: formed when primary pollutants undergo reactiosn with other chemicals present in the atmosphere, sometimes this is a photochemica reaction in the presence of sungligh e.g. tropospheric ozone, particles produced from gaseous primary pollutants, peroxyacetyl nitrate 

atmospheric pollution behvaiour: 

  • behave differently compared to on ground/in water, pollutants in atmosphere behave differently from those on ground/in water 
  • rapid movement due to winds leads to dispersal over large area 
  • interactions with electromagnetic radiation e.g. UV/visible light from sun cause chemical reactions to occur, leading to production of secondary pollutants 
  • transboundry, large areas of dispersal 
  • interact easily with electromagnetic radiations e.g, UV from the suns visible light = photochemical reactions = secondary pollutans 
  • interact with infra read energy radiated from earth 

smoke ( + smoke smogs) 

 

sources: inomplete combustion of carbon based materials produce smoke, combustion of wood fuel = small suspended solid particles in the atmosphere = measured by size range of particles

particle size important: smaller particles remain in atmosphere for longer likely be inhaled 

PM10: <10 microns in diameter 

PM5: <5 microns in diameter 

PM1: <1 micron in diameter 

smoke is made of particles of varying size. smaller they are the more damaging they are to humans. smoke is made up of particulates produced by incomplete combustion of carbon based materials . smoke categorised by size of particles 

toxic chemicals found in smoke include aluminium, lead, organic compounds 

smoke act synergistically with other atmospheric pollutants e.g. sulfur dioxide, exact composition of smoke depends upon its source. sources of smoke: combustion of coal, diesel. combustion of crop wastes, wood fuel 

smoke smogs (smoke + fog = smog) 

  • when smoke + fog present togetjer a smog may occur: smoke + fog = smog 
  • fog forms when moist air is cooled until it reaches a dew point, the water vapour condenses as airborne droplets of water, temp inversions make formation of fog more likely, smoke thats part of a smog is easily inhaled. smoke has very high albedo so the temp inversion can last for longer periods of time, allowing pollutant levels to rise 
  • the london smog of 1952 
  • fog formation occurs when cooled moist air reaches dew point - smoke that is part of smog easily inhaled 
  • water vapour condenses as a water layer of airbore droplets - smoke has very high albedo as it reflects light to temp inversion can last for long period of time = increase in pollutant levels 
  • temperature inversions more likley to cause fog formation - does not reach the ground to be absorbed/converted into heat 

thermal inversion: normal warm air from city wll rise, allowing pollutant to escape, on warm days a hot layer…

Comments

No comments have yet been made