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dc.contributor.author
Laubach, Johannes
dc.contributor.author
Barthel, Matti
dc.contributor.author
Fraser, Anitra
dc.contributor.author
Hunt, John E.
dc.contributor.author
Griffith, David W.T.
dc.date.accessioned
2018-10-12T13:30:24Z
dc.date.available
2017-06-12T02:52:02Z
dc.date.available
2018-10-12T13:30:24Z
dc.date.issued
2016
dc.identifier.other
10.5194/bg-13-1309-2016
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/114308
dc.identifier.doi
10.3929/ethz-b-000114308
dc.description.abstract
New Zealand's largest industrial sector is pastoral agriculture, giving rise to a large fraction of the country's emissions of methane (CH4) and nitrous oxide (N2O). We designed a system to continuously measure CH4 and N2O fluxes at the field scale on two adjacent pastures that differed with respect to management. At the core of this system was a closed-cell Fourier transform infrared (FTIR) spectrometer, which measured the mole fractions of CH4, N2O and carbon dioxide (CO2) at two heights at each site. In parallel, CO2 fluxes were measured using eddy-covariance instrumentation. We applied two different micrometeorological ratio methods to infer the CH4 and N2O fluxes from their respective mole fractions and the CO2 fluxes. The first is a variant of the flux-gradient method, where it is assumed that the turbulent diffusivities of CH4 and N2O equal that of CO2. This method was reliable when the CO2 mole-fraction difference between heights was at least 4 times greater than the FTIR's resolution of differences. For the second method, the temporal increases of mole fractions in the stable nocturnal boundary layer, which are correlated for concurrently emitted gases, are used to infer the unknown fluxes of CH4 and N2O from the known flux of CO2. This method was sensitive to “contamination” from trace gas sources other than the pasture of interest and therefore required careful filtering. With both methods combined, estimates of mean daily CH4 and N2O fluxes were obtained for 56% of days at one site and 73% at the other. Both methods indicated both sites as net sources of CH4 and N2O. Mean emission rates for 1 year at the unfertilised, winter-grazed site were 8.9 (±0.79)nmolCH4m−2s−1 and 0.38 (±0.018)nmolN2Om−2s−1. During the same year, mean emission rates at the irrigated, fertilised and rotationally grazed site were 8.9 (±0.79)nmolCH4m−2s−1 and 0.58 (±0.020)nmolN2Om−2s−1. At this site, the N2O emissions amounted to 1.21 (±0.15)% of the nitrogen inputs from animal excreta and fertiliser application.
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.title
Combining two complementary micrometeorological methods to measure CH4 and N2O fluxes over pasture
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
dc.date.published
2016-03-02
ethz.journal.title
Biogeosciences
ethz.journal.volume
13
en_US
ethz.journal.issue
4
en_US
ethz.pages.start
1309
en_US
ethz.pages.end
1327
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.identifier.nebis
006289717
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02703 - Institut für Agrarwissenschaften / Institute of Agricultural Sciences::03982 - Six, Johan / Six, Johan
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02703 - Institut für Agrarwissenschaften / Institute of Agricultural Sciences::03982 - Six, Johan / Six, Johan
ethz.date.deposited
2017-06-12T02:53:50Z
ethz.source
ECIT
ethz.identifier.importid
imp5936543bf193459551
ethz.ecitpid
pub:176086
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-19T09:08:13Z
ethz.rosetta.lastUpdated
2019-01-02T14:30:09Z
ethz.rosetta.versionExported
true
ethz.COinS
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