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| Titel |
Eddy covariance flux measurements of ammonia with eTR-MS |
| VerfasserIn |
Jörg Sintermann, Uwe Kuhn, Albrecht Neftel |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042586
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| Zusammenfassung |
| Micrometerological flux measurements of ammonia (NH3) are very difficult due to the
stickiness of the NH3 molecule to all surfaces. Only recently, sensitive and fast responding
instruments became available that opened the posibility to perform an Eddy Covariance
approach to measure NH3 fluxes. Norman et al. (2006, 2007) showed that a modified
commercial Proton Transfer Reaction-Mass Spectrometer from IONICON using
charged oxygen molecules instead of protons reliably measured concentrations,
but had too strong damping within the drift tube and the inlet lines for EC flux
measurements.
In the mean time a new smaller drift tube became available that can be heated up to
180-C. With this configuration the response time was below 1 sec. Heating also the whole
inlet line to temperature above 100-C enabled NH3 EC flux measurements. The performance
of the system was tested during two fertilization events (organic manure and urea application)
at the Oensingen grassland site in Switzerland. The measured fluxes were in good agreement
with an Aerodynamic Gradient approach and showed a similar dynamic range. The sensitivity
of the eTR-MS systems seems to be in the same order of magnitude as state of the art
gradient systems.
References:
Norman, M., Wisthaler, A., and Hansel, A. (2007). O2+ as primary reagent ion in the
PTR-MS instrument: Detection of gas-phase ammonia, International Journal of Mass
Spectrometry 265, 382–387.
Norman, M., Spirig, C., Wolff, V., Trebs, I., Flechard, C., Wisthaler, A., Schnitzhofer, R.,
Hansel, A., and Neftel, A.: Intercomparison of ammonia measurement techniques at an
intensively managed grassland site (Oensingen, Switzerland), Atmospheric Chemistry and
Physics, 9, 2635-2645, 2009. |
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