Technical note: Laboratory evaluation of a tunable diode laser system for eddy covariance measurements of ammonia flux

Brodeur, Jason; Warland, J.; Staebler, R. M.; Wagner-Riddle, Claudia

doi:10.1016/j.agrformet.2008.08.009

Cited by 25 publications

(26 citation statements)

References 23 publications

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“…The findings emphasize the importance of appropriate inlet characteristics (length, material, temperature, filter use) especially for EC measurements of highly reactive and/or soluble compounds, like NH 3 . This problem, partly with corresponding solutions, has already been presented for HNO 3 by Munger et al (1996), Horii et al (2006) and Farmer et al (2006) and also for NH 3 by Brodeur et al (2008), Whitehead et al (2008), Ellis et al (2010) and Sintermann et al (2011). Beside the use of appropriate inert material, the omission of an inlet filter and (strong) heating of the entire inlet tube were the main recommendations.…”

Section: Improvement Of the Convertermentioning

confidence: 99%

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

Ammann

Wolff

Marx³

et al. 2012

Biogeosciences

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Abstract. The (net) exchange of reactive nitrogen (N r ) with the atmosphere is an important driver for ecosystem productivity and greenhouse gas exchange. The exchange of airborne N r includes various trace compounds that usually require different specific measurement techniques, and up to now fast response instruments suitable for eddy covariance measurements are only available for few of these compounds.Here we present eddy covariance flux measurements with a recently introduced converter (TRANC) for the sum of all N r compounds ( N r ). Measurements were performed over a managed grassland field with phases of net emission and net deposition of N r and alternating dominance of oxidized (NO X ) and reduced species (NH 3 ). Spectral analysis of the eddy covariance data exhibited the existence of covariance function peaks at a reasonable time lag related to the sampling tube residence time under stationary conditions. Using ogive analysis, the high-frequency damping was quantified to 19 %-26 % for a low measurement height of 1.2 m and to about 10 % for 4.8 m measurement height.N r concentrations and fluxes were compared to parallel NO and NO 2 measurements by dynamic chambers and NH 3 measurements by the aerodynamic gradient technique. The average concentration results indicate that the main compounds NO 2 and NH 3 were converted by the TRANC system with an efficiency of near 100 %. With an optimised sample inlet also the fluxes of these compounds were recovered reasonably well including net deposition and net emission phases. The study shows that the TRANC system is suitable for fast response measurements of oxidized and reduced nitrogen compounds and can be used for continuous eddy covariance flux measurements of total reactive nitrogen.

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Section: Improvement Of the Convertermentioning

confidence: 99%

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

Ammann

Wolff

Marx³

et al. 2012

Biogeosciences

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“…The largest difficulty and strongest potential limitation of the EC approach for NH 3 is the correct quantification of the attenuation of fast and turbulent high-frequent concentration fluctuations between the sample location and actual measurement (Brodeur et al, 2009). To our knowledge, the only other study of NH 3 EC flux measurements that simultaneously compared the results to the fluxes obtained from an established (gradient) method discovered substantial high-frequency attenuation losses that could not be quantified by inherent methods (Whitehead et al, 2008).…”

Section: Uncertainty Of the Ec/ht-cims Approachmentioning

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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“…In field applications, the majority of instruments require an inlet tube of several metres length. 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%

“…The conditions in the field are best suited to test the applicability of the system for EC measurements as they provide the entire range of turbulent structures in the atmospheric surface layer with corresponding concentration changes that could be simulated only with a very complex laboratory experiment (e.g. Brodeur et al, 2008). The performance of our setup was tested during two slurry applications on an arable and a grassland field.…”

Section: Introductionmentioning

confidence: 99%

“…This leads to attenuation of concentration changes and thus most severely limits the application of the EC technique for NH 3 . Brodeur et al (2008) evaluated a TDLAS, including inlet lines for NH 3 EC measurements. In the laboratory, they proved the setup to highly underestimate fluxes in most potential measurement situations due to attenuation of fast NH 3 fluctuations in the inlet tube.…”

Section: Introductionmentioning

confidence: 99%

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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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Technical note: Laboratory evaluation of a tunable diode laser system for eddy covariance measurements of ammonia flux

Cited by 25 publications

References 23 publications

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

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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