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Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide. Mao-Chang Liang Research Center for Environmental Changes, Academia Sinica Y. L. Yung Divisions of Geological and Planetary Sciences, California Institute of Technology

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Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

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  1. Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Mao-Chang Liang Research Center for Environmental Changes, Academia Sinica Y. L. Yung Divisions of Geological and Planetary Sciences, California Institute of Technology European Geosciences Union General Assembly 2009, Vienna, Austria, 19 – 24 April 2009 EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

  2. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

  3. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

  4. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Courtesy of SJ Kao

  5. ISI 200 EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

  6. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide 14N14N16O (446) _ 14N15N16O (456) --N 15N14N16O (546) --N 14N14N18O (448) --18O (δ15N = ½ [δN + δN]) # Source: natural -- land -- ocean anthropogenic -- agriculture, fossil fuels & industry, biomass burning,… # Sink: (stratosphere) -- photolysis and chemistry (~160-220 nm) N2O continues to increase in the atmosphere. However, contribution of each source is not well-quantified.

  7. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Kim and Craig 1993

  8. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Liang and Yung 2007

  9. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Method – a simple box model F_sink Available measurements: 1. N2O trend 2. 18O 3. 15N ( and ) Troposphere F_ocean F_land F_anthro. (1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source (3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary. (6) The lifetimes do not vary with time.

  10. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Method – a simple box model F_sink Available measurements: 1. N2O trend 2. 18O 3. 15N ( and ) Troposphere F_ocean F_land F_anthro. (1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source (3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary. (6) The lifetimes do not vary with time.

  11. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide

  12. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide x: Machida et al. [1995] +: Bernard et al. [2006]

  13. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Time evolution of δ18O(N2O) and δ15N (N2O) x: Rockmann and Levin [2005] x: Park et al. [2009]

  14. Sources and sinks EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide OC -- ocean LD -- land AN -- anthropogenic Total = OC+LD+AN SK -- sink TD -- trend

  15. 5 TgN/yr 1 TgN/yr 150 GtC (Broecker 2007)

  16. EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide Conclusion • Better measurements are needed as present data have large errors. • Large source of N2O from ocean fertilization needs to be considered Use the Caltech/JPL 2-D and MOZART/CAM-CHEM 3-D models for better estimates.

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