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Anthropogenic C Emissions: Fossil Fuel

1850. 1870. 1890. 1910. 1930. 1950. 1970. 1990. 2010. Anthropogenic C Emissions: Fossil Fuel. 2006 Fossil Fuel: 8.4 Pg C. [2006-Total Anthrop. Emissions:8.4+1.5 = 9.9 Pg]. 1990 - 1999: 1.3% y -1 2000 - 2006: 3.3% y -1. Raupach et al. 2007, PNAS; Canadell et al 2007, PNAS.

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Anthropogenic C Emissions: Fossil Fuel

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  1. 1850 1870 1890 1910 1930 1950 1970 1990 2010 Anthropogenic C Emissions: Fossil Fuel 2006 Fossil Fuel: 8.4 Pg C [2006-Total Anthrop. Emissions:8.4+1.5 = 9.9 Pg] • 1990 - 1999: 1.3% y-1 • 2000 - 2006: 3.3% y-1 Raupach et al. 2007, PNAS; Canadell et al 2007, PNAS

  2. Friedlingstein et al. 2010

  3. Nitrogen Cycle Units=teragrams yr-1

  4. Nitrogen Cycle Largest pool of nitrogen=atmospheric N2 vegetation = 4,000 Tg soils = 100,000 Tg atmosphere = 3,900,000,000 Tg Biological N fixation has historically been the major input of N into ecosystems Oceans = 100 Tg/yr Land = 140 Tg/yr Denitrification is major output of N back to the atmosphere Oceans = 110 Tg/yr Land = 200 Tg/yr Balance?

  5. Nitrogen Cycle N is most commonly limiting element in terrestrial ecosystems, and in some aquatic ecosystems (estuaries, coastal seas) Amount that cycles within terrestrial ecosystems is 9 times the land N fixation rate Amount that cycles within ocean ecosystems is 80 times the ocean N fixation rate

  6. Changing Nitrogen Cycle Humans have doubled the N fixation rates over natural levels Haber-Bosch 3CH4 + 6H2O --> 3CO2 + 12H2 4N2+12H2 --> 8NH3 (high T,pressure, Fe) Bread AND Bombs

  7. Changing Nitrogen Cycle About half of human additions come from fertilizer production About a quarter from increasing amount of biological N fixation The other quarter inadvertently from fossil fuel combustion

  8. Changing Nitrogen Cycle Increased fertilizer inputs can: volatilize from fields, pastures (NH3) increase nitrification (NO, N2O,NO3- leaching) increased denitrification (NO, N2O, N2)

  9. Townsend et al. 2003

  10. Other Changes in the Nitrogen Cycle • Mobilization of N from long term storage • incomplete fossil fuel combustion releases NOx • biomass burning releases NH3, NOx • land clearing, conversion, drainage, or permafrost thaw can increase leaks in the N cycle

  11. GWP=200 Changing N Cycle: Effects on Atmosphere N2O (nitrous oxide) N2O (Nitrous oxide) Reacts with excited O in stratosphere to form NO and catalyze destruction of O3 IPCC 2007

  12. Changing N Cycle: Effects on Atmosphere NOx (Nitric oxides) high concentrations contribute to O3 formation in troposphere stratospheric ozone = good (but, ozone hole = bad) tropospheric ozone = bad (smog, greenhouse gas)

  13. Trophospheric ozone formation and destruction Net reaction at high [NOx]: CO + 2O2 + hv --> CO2 + O3 Net reaction at low [NOx]: CO + O3 + hv --> CO2 + O2

  14. Trophospheric ozone OH + CO + O2 --> CO2 + HO2 HO2 + NO --> NO2 + OH NO2 + hv --> NO+ O O2 + O + M --> O3 + M net: CO + 2O2 + hv --> CO2 + O3

  15. Changing N Cycle: Effects on Atmosphere NOx contributes to nitric acid formation in troposphere HO2 + NO --> NO2 + OH NO2 + H2O --> H+ + HNO3- N transfer to “downwind” terrestrial and aquatic ecosystems

  16. Acid deposition and atmosphere pH • Wetfall: deposition of nutrients by precipitation (easy to • measure with exception of fog) • Acid rain = pH  5.6, bad for ecosystems! • NO3-  HNO3 • SO42-  H2SO4 • NH3 and Ca2+ important for neutralizing atm.’s acidity • Globally, 22% of acidity is neutralized by NH3 • Regionally: • Southern hemisphere: NH3 most important • NE US and Europe: SO42- drives acidity • Western US: acid ions interact with CaCO3

  17. Dry deposition • Dryfall: gravitational sedimentation of particles without rain • NH4+, NO3- • Dust • NO2 and NH3 gases • Acid vapors • Controlled by wind and canopy structure • Hard to measure and poorly constrained

  18. Effects of N Transfers on Ecosystems Nitrogen deposition downwind from NH3 and NOx sources unpolluted areas = 1 kg N/ha/yr Northeastern US = 10-20 kg N/ha/yr some parts of Europe = 50-100 kg N/ha/yr How much N is this?

  19. National Atmospheric Deposition Program

  20. NADP animations • http://nadp.sws.uiuc.edu/data/animaps.aspx

  21. (1 g N m-2 yr-1 = 10 kg ha-1 yr-1) Galloway et al. 2008

  22. Next Monday: Ecosystem-level effects of N deposition Fertilization Saturation Biogeochemical feedbacks

  23. Fig. 1. N contained in internationally traded (A) fertilizer (31 Tg N), (B) grain (12 Tg N), and (C) meat (0.8 Tg N). J N Galloway et al. Science 2008;320:889-892 Published by AAAS

  24. Fig. 3. Conceptual model of where interventions in the N cycle can be used to decrease the amount of Nr created or the amount of Nr lost to the environment. J N Galloway et al. Science 2008;320:889-892 Published by AAAS

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