Chemistry of the atmospher

• Phase 1: volcanos gave out gases

  • the early atmosphere mostly consisted of CO2 and virtually no oxygen (much like mars)
  • Volcanic activity released nitrogen which built up over time as well as water vapour and small amounts of methane and ammonia
• Phase 2 -oceans, algae and green plants absorbed carbon dioxide

  • Water vapour from the atmosphere condensed and formed oceans
  • Lots of CO2 was removed from the early atmosphere as it was dissolved in the oceans
  • Green plants and algae evolved and absorbed some of the CO2 so that they could carry out photosynthesis
• formation of crude oil:

  • when plants, plankton and marine animals die, they fall to the seabed and get buried by layers of sediments, over millions of years they become compressed and form sediments, oil and gas- trapping the carbon within them to keep atmospheric CO2 levels down
  • crude oil and natural gas are formed from deposits of plankton
  • coal is a sedimentary rock made from thick plant sediments
• Phase 3- green plants and algae produced oxygen

  • As well as absorbing CO2 in the atmosphere, green plants and algae produced oxygen by photosynthesis
  • Algae evolved first (around 2.7 billion years ago), then over the next billion years plants evolved
  • As oxygen levels built up in the atmosphere over time, more complex life (like animals) could evolve
  • Eventually around 200 million years ago the atmosphere reached a composition similar to what it is today
• the atmosphere today:

  • 80% nitrogen
  • 20% oxygen
  • small amounts of other gasses each of which make up less than 1% of the atmosphere
• the 3 main greenhouse gasses:

  • Carbon dioxide
  • methane
  • water vapout
• what type of radiation do greenhouse gasses absorb and re-radiate ?

  long wavelength radiation

  • they dont absorb the short wavelength radiation from the sun
  • they absorb the long wavelength radiation that gets reflected back off the earth
  • they then re radiate it in all directions (including back to earth)
  • long wavelength radiation is thermal radiation so it results in the warming of the earth
  • this is the greenhouse effect
• human activities that increase the levels of CO2

  • deforestation
  • burning fossil fuels
  • agriculture
  • creating waste
• increasing CO2 is directly linked to climate change
• dangerous consequences of climate change:

  • increase in global temps could lead to polar ice caps melting- causing a sea level rise so increased flooding and erosion in costal areas
  • changes in rainfall patterns
  • increased frequency and intensity of storms
  • changes in temperatures and amounts of water available could cause extinction
• measuring carbon footprints is almost impossible to do accurately as there are so many different factors to consider
• ways of reducing carbon footprints:

  • renewable. energy sources or nuclear energy used instead of fossil fuels
  • governments taxing people or companies based on amount of CO2 they emit
• what is incomplete combustion?

  when fossil fuels are burned without enough oxygen some of the fuel isn’t burnt, this causes particulates (solid particles)of soot (carbon) and unburnt fuel are released and carbon monoxide can be produced as well as CO2
• problems caused by particulates in the air

  • if inhaled they can get stuck in the lungs and cause damage- leading to respiratory problems
  • theyre bad for the environment- they themselves and the clouds they produce reflect sunlight back into space, causing less light to reach Earth which causes global dimming
• Carbon monoxide

  • Dangerous as it can stop your blood from carrying oxygen around the body
  • It causes this by binding to haemoglobin in your body that normally carries O2 so less oxygen is transported around your body
  • A lack of oxygen can lead fainting, a coma or death
  • It doesnt have any colour or smell so it is very hard to detect
• what gasses cause acid rain?

  sulphur dioxide and nitrogen oxides

  • SO2 is released during the combustion of fossil fuels
  • NO is created from a reaction between the nitrogen and oxygen in the air caused by the heat of the burning
  • both are also bad for respitory health