atmospheric nitrogen deposition causes indirect no and n 2 o emissions in (semi-)natural ecosystems...
TRANSCRIPT
Atmospheric nitrogen deposition causes indirect NO and N2O emissions in (semi-)natural ecosystems
Tobias Bühlmann (University of Basel)
Beat Achermann (FOEN)Simon Liechti (FOEN)
Beat Rihm (Meteotest)Erika Hiltbrunner (University of Basel)Christian Körner (University of Basel)
TFEIP, Milano, 11 May 2015
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Indirect N2O and N emissions
• (Semi-)natural ecosystems are used extensively only or not at all; no net N input besides atmospheric N deposition
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Exceedance of CLN
• Correlation between atmospheric N deposition and NO/N2O emission (Butterbach et al. 1998)
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Today’s methods
• Indirect N2O emissions (Guidelines for National Greenhouse Gas Inventories 2006, IPCC)
– N2O-N = (NH3-N + NOx-N emissions) x EF4
• EF4 = 1%
• Indirect NO emissions (Emission Inventory Guidebook 2013, EMEP/EEA)
– Simpler methodology (Skiba et al. 1997)
• NO = N input x EFNOx + 0.1 ng NO-N m-2 s-1
– EFNOx = 0.3%
– Detailed methodology (Novak and Pierce 1993)
• Not suitable for annual emissions
• Attention: EF4 and EFNOx are based on agriculture data only
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Methods
• Aim: Calculate indirect NO and N2O emissions of Swiss (semi-)natural ecosystems
– EMEP/EEA and IPCC compatibility: “Activity x EF”
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Methods
• Literature research– Studies measuring NO or N2O emission in (semi-)natural
ecosystems• Total N deposition known (measured or modelled)• Similar climatic conditions as Switzerland• Long time measurements• No fertilizer, no N2-fixing plants
• N deposition dependent emission rates- SWC, soil pH, soil temperature etc. could not be involved in
analyses
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Results & discussion
• 57 N2O long-term emission measurements
• N deposition inducessignificant N2O emissions;confirmed byMachefert et al. 2002and Skiba et al. 2012
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Bühlmann et al. 2015
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Results & discussion
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• 16 NO long-term emission measurements
Bühlmann et al. 2015
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Results & discussion
• Emission rates differ between (semi-)natural ecosystems (Bühlmann et al. 2015; Groffman et al. 2000)
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de.wikipedia.org
N2O NO
N2
O NO
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Results & discussion
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Stehfest and Bouwman 2006
N input
EFN2O-N:0.9 %
EFNO-N:0.6 %
N input
EFN2O-N:3.7 %
EFNO-N:12.5 %
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Application
• Calculation of ecosystem specific indirect NO and N2O emissions– Indirect N emission = N deposition x emission rate– Ecosystem specific emission rate (this study)
• Ecosystem type: Land Use Statistics, WMG-100– 100 m resolution
– N deposition (Meteotest)• 100 m resolution, for the years 1990, 2000, 2007, 2010
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Results & discussion
• Indirect N2O emissions of (semi-)natural ecosystems
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Bühlmann et al. 2015
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Results & discussion
• Indirect NO emissions of (semi-)natural ecosystems
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Bühlmann et al. 2015
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Results & discussion
• Indirect N2O emissions of (semi-)natural ecosystems for the year 2000
• IPCC approach underestimates N2O emissions of (semi-) natural ecosystems in Switzerland
• In 2010 21 % of the total N2O emission were emitted from (semi-)natural ecosystems
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N2O (Gg N)This study
N2O (Gg N)IPCC (modified)
N2O (Gg N)Kesik et al. 2005
Forests 1.45 ± 0.40 0.18 0.75
Grass- and wetlands 0.24 ± 0.04 0.03 -
total 1.69 ± 0.34 0.21 -
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Results & discussion
• Indirect NO emissions of (semi-)natural ecosystems for the year 2000
• EMEP/EEA approach underestimates NOx emissions of (semi-) natural ecosystems in Switzerland
• In 2010 10 % of the total NOx emission were emitted from (semi-)natural ecosystems
TFEIP, Milano, 11 May 2015
NO (Gg N)This study
NO (Gg N)EMEP/EAA
NO (Gg N)Kesik et al. 2005
Forests 2.56 ± 0.64 0.06 0.58
Grass- and wetlands 0.03 ± 0.04 0.03 -
total 2.61 ± 0.55 0.09 -
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Conclusion
• Indirect N2O and NO emissions from (semi-)natural ecosystems are substantial.
• EFs for indirect N emissions differ between ecosystems.– EFs for agricultural land are unsuitable for (semi-)natural
ecosystems.
• Indirect N2O and NO emissions of (semi-)natural ecosystems are currently underestimated by the international approaches.– High uncertainty for NO emissions.
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Acknowledgements
• University of Basel– Erika Hiltbrunner, Christian Körner
• FOEN– Beat Achermann, Richard Ballaman, Martin Schiess, Simon
Liechti
• Meteotest– Beat Rihm
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Application in emission inventories
• indEmistotal = indEmis(semi-)nat. ecosystems + indEmisrest
• N deposition missing in emission inventories– Relate indirect emissions of (semi-)natural ecosystems to
the sum of direct NOx-N and NH3-N emissions Efemis
• Switzerland– Indirect N2O emissions are calculated for direct emissions
of agriculture only.
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Application of results: NO
• Indirect NO emissionsNOind. = NOind. nat. ecosystems + NOind. rest
= Activity x EFnat. Ecosystems + activity x EFNOx
= Activity x (EFnat. Ecosystems + EFNOx)
• Activity = sum of national NOx-N and NH3-N emissions
• EFnat. ecosystems = (NO-Nnat. ecosystems)/(sum of national NOx-N and NH3-N emissions)– Available for the years 1990, 2000, 2007, 2010– Only valid for Switzerland!
• EFNOx = (NO-Nrest)/(sum of national NOx-N and NH3-N emissions)
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Application of results: N2O
• Indirect N2O emissionsN2Oind. = N2Oind. nat. ecosystems + N2Oind. rest
= Activity x EFnat. Ecosystems + activity x EF4 x 0.543
• Activity = sum of national NOx-N and NH3-N emissions
• EFnat. ecosystems = (N2O-Nnat. ecosystems)/(sum of national NOx-N and NH3-N emissions)– Available for the years 1990, 2000, 2007, 2010– Only valid for Switzerland!
• EF4 = 0.01
TFEIP, Milano, 11 May 2015