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Question 4 Explain how information on changes in atmospheric ozone concentrations is obtained

Question 4 Explain how information on changes in atmospheric ozone concentrations is obtained. Anita and Lily. Ozone (O 3 ). Pale blue and highly reactive gas with a pungent odour Allotrope of oxygen Troposphere = 10% Stratosphere = 90%

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Question 4 Explain how information on changes in atmospheric ozone concentrations is obtained

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  1. Question 4 Explain how information on changes in atmospheric ozone concentrations is obtained Anita and Lily

  2. Ozone (O3) • Pale blue and highly reactive gas with a pungent odour • Allotrope of oxygen • Troposphere = 10% • Stratosphere = 90% • In the stratosphere it acts as a primary UV radiation shield

  3. Vast majority of the atmospheric ozone occurs in the stratosphere

  4. Photochemical Smog • N2(g) + O2(g) 2NO(g) due to the high temperature in engines • 2NO(g) + O2(g) 2NO2(g) released from car exhaust and oxidised in air • NO2(g) + UVlight  NO(g) + O (g) forming oxygen radical • O (g) + O2(g) O3(g)

  5. Causes for ‘ozone hole’ • Thinning of the ozone layer • CFCs • They remain in the troposphere for decades and eventually find their way to the stratosphere • CCl3F(g) + UVlight  Cl● (g) + CCl2F● (g) CCl2F● (g) + UVlight  Cl● (g) + CClF● (g) • Cl● (g) + O3(g) ClO● (g) + O2(g) • ClO● (g) + O● (g) O2(g) + Cl● (g)

  6. Halons • Produces bromine radicals which are even more detrimental than Cl radicals • Br●(g) + O3(g) BrO● + O2(g) • Carbon Tetrachloride • Solvents • Cl2 + u.v light  2Cl - Can destroy ozone in the same way as Cl atoms from CFC’s

  7. Effects of the ‘ozone hole’ • Cellular damage e.g. sunburn on mammalian skin • Changes in plant growth • Plankton and the ecosystem • Terrestrial plants, in particular agricultural crops • Skin cancer • Damage to the immune system (diseases) • Respiratory problems

  8. Ways to obtain changes in atmospheric ozone concentrations • UV Spectrophotometers • UV light from satellite • High-flying aircraft • Balloons • Lasers fired from ground

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