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Article Dans Une Revue Atmospheric Measurement Techniques Année : 2022

Intercomparison of in situ measurements of ambient NH 3 : instrument performance and application under field conditions

Marsailidh Twigg
Augustinus Berkhout
Nicholas Cowan
  • Fonction : Auteur
Enrico Dammers
  • Fonction : Auteur
Volker Ebert
  • Fonction : Auteur
Marty Haaima
  • Fonction : Auteur
Christoph Häni
Lewis John
  • Fonction : Auteur
Matthew Jones
  • Fonction : Auteur
Bjorn Kamps
  • Fonction : Auteur
John Kentisbeer
  • Fonction : Auteur
Thomas Kupper
Sarah Leeson
  • Fonction : Auteur
Daiana Leuenberger
  • Fonction : Auteur
Nils Lüttschwager
  • Fonction : Auteur
Ulla Makkonen
  • Fonction : Auteur
Nicholas Martin
  • Fonction : Auteur
David Missler
  • Fonction : Auteur
Duncan Mounsor
  • Fonction : Auteur
Albrecht Neftel
  • Fonction : Auteur
Chad Nelson
  • Fonction : Auteur
Eiko Nemitz
Rutger Oudwater
  • Fonction : Auteur
Celine Pascale
Jean-Eudes Petit
Andrea Pogany
  • Fonction : Auteur
Jörg Sintermann
  • Fonction : Auteur
Amy Stephens
  • Fonction : Auteur
Mark Sutton
Yuk Tang
Rens Zijlmans
  • Fonction : Auteur
Christine Braban
Bernhard Niederhauser
  • Fonction : Auteur

Résumé

Abstract. Ammonia (NH3) in the atmosphere affects both the environment and human health. It is therefore increasingly recognised by policy makers as an important air pollutant that needs to be mitigated, though it still remains unregulated in many countries. In order to understand the effectiveness of abatement strategies, routine NH3 monitoring is required. Current reference protocols, first developed in the 1990s, use daily samplers with offline analysis; however, there have been a number of technologies developed since, which may be applicable for high time resolution routine monitoring of NH3 at ambient concentrations. The following study is a comprehensive field intercomparison held over an intensively managed grassland in southeastern Scotland using currently available methods that are reported to be suitable for routine monitoring of ambient NH3. In total, 13 instruments took part in the field study, including commercially available technologies, research prototype instruments, and legacy instruments. Assessments of the instruments' precision at low concentrations (< 10 ppb) and at elevated concentrations (maximum reported concentration of 282 ppb) were undertaken. At elevated concentrations, all instruments performed well and with precision (r2 > 0.75). At concentrations below 10 ppb, however, precision decreased, and instruments fell into two distinct groups, with duplicate instruments split across the two groups. It was found that duplicate instruments performed differently as a result of differences in instrument setup, inlet design, and operation of the instrument. New metrological standards were used to evaluate the accuracy in determining absolute concentrations in the field. A calibration-free CRDS optical gas standard (OGS, PTB, DE) served as an instrumental reference standard, and instrument operation was assessed against metrological calibration gases from (i) a permeation system (ReGaS1, METAS, CH) and (ii) primary standard gas mixtures (PSMs) prepared by gravimetry (NPL, UK). This study suggests that, although the OGS gives good performance with respect to sensitivity and linearity against the reference gas standards, this in itself is not enough for the OGS to be a field reference standard, because in field applications, a closed path spectrometer has limitations due to losses to surfaces in sampling NH3, which are not currently taken into account by the OGS. Overall, the instruments compared with the metrological standards performed well, but not every instrument could be compared to the reference gas standards due to incompatible inlet designs and limitations in the gas flow rates of the standards. This work provides evidence that, although NH3 instrumentation have greatly progressed in measurement precision, there is still further work required to quantify the accuracy of these systems under field conditions. It is the recommendation of this study that the use of instruments for routine monitoring of NH3 needs to be set out in standard operating protocols for inlet setup, calibration, and routine maintenance in order for datasets to be comparable.
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Dates et versions

hal-03969442 , version 1 (02-02-2023)

Identifiants

Citer

Marsailidh Twigg, Augustinus Berkhout, Nicholas Cowan, Sabine Crunaire, Enrico Dammers, et al.. Intercomparison of in situ measurements of ambient NH 3 : instrument performance and application under field conditions. Atmospheric Measurement Techniques, 2022, 15 (22), pp.6755-6787. ⟨10.5194/amt-15-6755-2022⟩. ⟨hal-03969442⟩
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