Intercomparison of ammonia measurement techniques at an intensively managed grassland site (Oensingen, Switzerland)

Norman, Michael; Spirig, C.; Wolff, V.; Trebs, Ivonne; Fléchard, Christophe; Wisthaler, Armin; Schnitzhofer, R.; Hansel, Armin; Neftel, A.

doi:10.5194/acp-9-2635-2009

Cited by 83 publications

(69 citation statements)

References 39 publications

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“…Higher temperatures may be used, but temperatures that are too high could result in volatilization of NH 4 NO 3 . Inlet configurations can also affect signals, as condensation in the tubing can lead to NH 3 losses (Norman et al, 2009). The sampling line effects, such as RH and NH 3 concentrations, can also play a role in background measurements , although in our case the background signals did not have a clear dependence on RH, but varied with the sampled NH 3 level.…”

Section: Discussionmentioning

confidence: 99%

A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

et al. 2010

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Abstract. This study presents a chemical ionization mass spectrometer (CIMS) for fast response, in-situ measurements of gas phase ammonia (NH 3 ). The NH 3 background level detected with the CIMS ranged between 0.3-1 ppbv, with an uncertainty of 30 pptv under optimized conditions. The instrument sensitivity varied from 4-25 Hz/pptv for >1 MHz of reagent ion signals (protonated ethanol ions), with a 30% uncertainty estimated based on variability in calibration signals. The CIMS detection limit for NH 3 was ∼60 pptv at a 1 min integration time (3 sigma). The CIMS time response was <30 s. This new NH 3 -CIMS has been used for ambient measurements in Kent, Ohio, for several weeks throughout three seasons. The measured NH 3 mixing ratios were usually at the sub-ppbv level and higher in spring (200 ± 120 pptv) than in winter (60 ± 75 pptv) and fall (150 ± 80 pptv). High emissions of SO 2 from power plants in this region, and thus possible high acidity of aerosol particles, may explain these low NH 3 mixing ratios in general.

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Section: Discussionmentioning

confidence: 99%

A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

et al. 2010

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“…Two adjacent fields cultivated as cropland (wheat) and intensively managed grassland (grass-clover mixture) were fertilised with liquid cattle slurry. The grassland is one of the level 3 sites of the NitroEurope project (www.nitroeurope.eu) and NH 3 concentrations as well as exchange patterns had been investigated here previously (Norman et al, 2009;Spirig et al, 2010;Wolff et al, 2010;Flechard et al, 2010Flechard et al, , 2011. The climate is temperate continental with mean annual temperature and rainfall of 9.5 • C and 1200 mm, respectively.…”

Section: Field Experimentsmentioning

confidence: 99%

“…The HT-CIMS, based on PTR-MS (Hansel et al, 1995;Lindinger et al, 1998), is a chemical ionisation technique making use of electron transfer reactions to on-line ionise continuously sampled gas with subsequent detection of selected ion products (Norman et al, 2007(Norman et al, , 2009. It operates with positively charged oxygen instead of protonated water as a source for charge transfer.…”

Section: Ht-cimsmentioning

confidence: 99%

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

et al. 2011

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Abstract.At a cropland and a grassland site field scale ammonia (NH 3 ) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH 3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. A consistency test with concentrations measured by impingers showed very low systematic deviations for the EC/HT-CIMS results (<8 %) but larger deviations for the bLS/FTIR results. For both slurry application events, the period during fertilisation and the subsequent two hours contributed by more than 80 % to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3 % loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3 % over the grassland field.

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“…This attenuates fast concentration changes (Lenschow and Raupach, 1991;Brodeur et al, 2008;Massmann and Ibrom, 2008;Whitehead et al, 2008) and may even introduce severe NH 3 concentration alteration in special situations, e.g. during periods of condensation inside the tube (Norman et al, 2009) and NH 3 evaporation from the tube walls induced by drying of the inner surface Ellis et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Norman et al (2007) published a CIMS approach to measure NH 3 with a modified commercial PTR-MS from Ionicon Analytik GmbH (Innsbruck, Austria), using chemical ionisation of the analyte via electron transfer instead of proton transfer. The instrument reliably measured NH 3 concentrations (Norman et al, 2009), but had a response time too slow for EC measurements. To a major part, adsorption and desorption of NH 3 on surfaces inside the instrument restricted the time resolution.…”

Section: Introductionmentioning

confidence: 99%

Eddy covariance flux measurements of ammonia by high temperature chemical ionisation mass spectrometry

et al. 2011

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Abstract.A system for fast ammonia (NH 3 ) measurements with chemical ionisation mass spectrometry (CIMS) based on a commercial Proton Transfer Reaction-Mass Spectrometer (PTR-MS) is presented. It uses electron transfer reaction as ionisation pathway and features a drift tube of polyetheretherketone (PEEK) and silica-coated steel. Heating the instrumental inlet and the drift tube to 180 • C enabled an effective time resolution of ∼1 s and made it possible to apply the instrument for eddy covariance (EC) measurements. EC fluxes of NH 3 were measured over two agricultural fields in Oensingen, Switzerland, following fertilisations with cattle slurry. Air was aspirated close to a sonic anemometer at a flow of 100 STP L min −1 and was directed through a 23 m long 1/2" PFA tube heated to 150 • C to an airconditioned trailer where the gas was sub-sampled from the large bypass stream. This setup minimised damping of fast NH 3 concentration changes between the sampling point and the actual measurement. High-frequency attenuation loss of the NH 3 fluxes of 20 to 40% was quantified and corrected for using an empirical ogive method. The instrumental NH 3 background signal showed a minor interference with H 2 O which was characterised in the laboratory. The resulting correction of the NH 3 flux after slurry spreading was less than 1‰. The flux detection limit of the EC system was about 5 ng m −2 s −1 while the accuracy of individual flux measurements was estimated 16% for the high-flux regime during these experiments. The NH 3 emissions after broad spreading of the slurry showed an initial maximum of 150 µg m −2 s −1 with a fast decline in the following hours.

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Intercomparison of ammonia measurement techniques at an intensively managed grassland site (Oensingen, Switzerland)

Cited by 83 publications

References 39 publications

A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

A Chemical Ionization Mass Spectrometer for ambient measurements of Ammonia

Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods

Eddy covariance flux measurements of ammonia by high temperature chemical ionisation mass spectrometry

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