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Prof. Dudley Shallcross ACRG Tim Harrison Bristol ChemLabS 2008. A Pollutant’s Tale. Comparison of the Earth with other planets Nitrogen and oxygen Temperature structure Tropospheric pollutants. Talk outline. 3 most abundant gases in each planetary atmosphere

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Prof. Dudley Shallcross ACRG Tim Harrison Bristol ChemLabS 2008


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    1. Prof. Dudley Shallcross ACRGTim Harrison Bristol ChemLabS2008 A Pollutant’s Tale

    2. Comparison of the Earth with other planets Nitrogen and oxygen Temperature structure Tropospheric pollutants Talk outline

    3. 3 most abundant gases in each planetary atmosphere Jupiter H2 (93%) He (7%) CH4 (0.3 %) Saturn H2 (96%) He (3%) CH4 (0.45 %) Uranus H2 (82%) He (15%) CH4 (2.3 %) Neptune H2 (80%) He (19%) CH4 (1-2 %) VenusCO2 (96%) N2 (3.5%) SO2 (0.015 %) Mars CO2 (95%) N2 (2.7%) Ar (1.6 %) Earth N2 (78%) O2 (21%) Ar (0.93 %)

    4. Nitrogen NN bond energy = 944 kJ/mol 78% of the atmosphere inert Gas at 25 OC, liquid at – 196 OC TGH

    5. Bacterial scrapheap challenge by Dr. Hazel Mottram

    6. Oxygen O=O bond energy = 496 kJ/mol 21% of the atmosphere Gas at 25 OC, liquid at -183 OC Photosynthesis is the main source of O2 6CO2+ 6H2O + sunlight  C6H12O6 + 6O2 2H2O2  2H2O + O2 TGH

    7. Life spring by Dr. Adrian Mulholland

    8. Urban Atmospheric Chemistry 10 km The Tropopause The Boundary Layer 1 km NO, NO2, VOC VOCs ? 0 km Compounds of both biogenic and anthropogenic origin

    9. What happens to VOCs (volatile organic compounds)? • Plants and trees emit a vast range of organic material; alkenes, alcohols, carbonyls, acids • Vehicles emit hydrocarbons and aromatic species Many of these species are insoluble and are not rained out, how are they removed? TGH

    10. High temperature combustion VOCs can be burned in air (combustion) and oxidised in the process CaC2 + 2H2O  Ca(OH)2 + C2H2 C2H2 + (5/2)O2 2CO2 + H2O CH3OH + (3/2)O2  CO2 + 2H2O The atmosphere oxidises VOCs using free radicals

    11. VOCs broken down by the OH radical, generated by sunlight O3 + sunlight O * + O2  < ~ 330 nm O* + H2O OH + OH OH + R-H  R + H2O

    12. Air measurements in Bristol of NO2 Data from 21st January 2001: Combustion is the main source of NO2 TGH

    13. Photochemical smog NO2 + sunlight O * + NO  < ~ 400 nm O* + O2 O3 TGH

    14. Photochemical smog in Bristol: 27/07/2001

    15. CO2measurements in Bristol CO2 has been measured for several years at the top of Old Park Hill.

    16. CO2 measurements at Bristol

    17. Longer term CO2 measurements CO2measurements have been made at Mauna Loa for many many years, and show that CO2 has been rising steadily for some time

    18. The enhanced greenhouse effect

    19. Secrets in the Ice Secrets in the Ice • Snow accumulation lays down record of environmental conditions • Compacted to ice preserving record • Drill ice core & date

    20. CO2 levels over the last 1000 years Gases are extracted from bubbles trapped in ice cores and provide record of past atmospheric concentrations

    21. Frog chorus by Dr. Simon Hall

    22. Methane (CH4) and Nitrous Oxide (N2O)

    23. Increased global temperature

    24. Impacts of global warming • Impacts associated with changes in • Precipitation • Sea level • Extreme weather 1941 2004

    25. Model simulation of recent climate Natural forcings only(solar, volcanic etc. variability) Anthropogenic forcings only(human-induced changes) The Met Office

    26. 1.0 Observed simulated by model 0.5 Temperature rise o C 0.0 Hadley Centre 1850 1900 1950 2000 Simulated global warming 1860-2000:Natural & Man-made factors

    27. Impacts of Climate on the world: Temperature

    28. Impacts of Climate on the World: Rainfall

    29. Stabilisation Wedges

    30. The Stabilization Wedge – Two Scenarios Billion of Tons of Carbon Emitted per Year 14 Historical emissions 7 0 2105 1955 2005 2055

    31. The Stabilization Wedge – Two Scenarios Billion of Tons of Carbon Emitted per Year 14 Historical emissions 7 0 2105 1955 2005 2055

    32. Billion of Tons of Carbon Emitted per Year 14 Currently projected path Historical emissions 7 Flat path 0 2105 1955 2005 2055

    33. Billion of Tons of Carbon Emitted per Year Easier CO2 target 14 ~850 ppm Currently projected path Stabilization Triangle Historical emissions 7 Flat path Tougher CO2 target ~500 ppm 0 2105 1955 2005 2055

    34. Billion of Tons of Carbon Emitted per Year 14 14 GtC/y Currently projected path Seven “wedges” Historical emissions 7 GtC/y 7 Flat path 0 2105 1955 2005 2055

    35. Current technology options to provide a wedge • Improve fuel economy • Reduce reliance on cars • More efficient buildings • Improved power plant efficiency • Decarbonisation of Electricity and Fuels • Substitution of Natural gas for coal • Carbon capture and storage • Nuclear fission • Wind electricity • Photovoltaic electricity • Biofuels

    36. 3 most abundant gases in each planetary atmosphere Jupiter H2 (93%) He (7%) CH4 (0.3 %) Saturn H2 (96%) He (3%) CH4 (0.45 %) Uranus H2 (82%) He (15%) CH4 (2.3 %) Neptune H2 (80%) He (19%) CH4 (1-2 %) VenusCO2 (96%) N2 (3.5%) SO2 (0.015 %) Mars CO2 (95%) N2 (2.7%) Ar (1.6 %) Earth N2 (78%) O2 (21%) Ar (0.93 %) TGH

    37. Thanks to Bristol ChemLabS British Council Sci Fest Africa 2008 t.g.harrison@bris.ac.uk d.e.shallcross@bris.ac.uk www.chemlabs.bris.ac.uk/outreach