Diffusion scrubber technique used for measurements of atmospheric ammonia

Sørensen, Lise Lotte; Granby, Kit; Nielsen, Helle Lykke; Asman, W. A. H.

doi:10.1016/1352-2310(94)00189-r

Cited by 37 publications

(18 citation statements)

References 33 publications

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“…The FAL and RISOE systems use a fluorescence detection technique (Blatter et al, 1993;Sørensen et al, 1994). The analytical detection is based on the reaction between ophthaldialdehyde, a reducing agent and ammonia to produce a fluorescent compound (Rapsomanikis et al, 1988).…”

Section: Detection and Response Characteristicsmentioning

confidence: 99%

Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

et al. 2009

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Abstract. The exchange of Ammonia (NH 3 ) between grassland and the atmosphere was determined using Relaxed Eddy Accumulation (REA) measurements. The use of REA is of special interest for NH 3 , since the determination of fluxes at one height permits multiple systems to be deployed to quantify vertical flux divergence (either due to effects of chemical production or advection). During the Braunschweig integrated experiment four different continuous-sampling REA systems were operated during a period of about 10 days and were compared against a reference provided by independent application of the Aerodynamic Gradient Method (AGM). The experiment covered episodes before and after both cutting and fertilizing and provided a wide range of fluxes −60-3600 ng NH 3 m −2 s −1 for testing the REA systems. The REA systems showed moderate to good correlation with the AGM estimates, with r 2 values for the linear regressions between 0.3 and 0.82. For the period immediately after fertilization, the REA systems showed average fluxes 20% to 70% lower than the reference. At periods with low fluxes REA and AGM can agree within a few %. Overall, the results show that the continuous REA technique can now be used to measure NH 3 surface exchange fluxes. While REA requires greater analytical precision in NH 3 measurement than the AGM, a key advantage of REA is that reference sampling periods can be introduced to remove bias Correspondence to: A. Hensen (hensen@ecn.nl) between sampling inlets. However, while the data here indicate differences consistent with advection effects, significant improvements in sampling precision are essential to allow robust determination of flux divergence in future studies. Wet chemical techniques will be developed further since they use the adsorptive and reactive properties of NH 3 that impedes development of cheaper optical systems.

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Section: Detection and Response Characteristicsmentioning

confidence: 99%

Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

et al. 2009

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“…The liquid was heated to 60 • C to enhance the formation of the fluorescent compound before injection into the fluorescence detector. Detailed information of the WEDD and the analytical 4580 K. Hansen et al: Ammonia emissions from deciduous forest after leaf fall system can be found in Sorensen et al (1994). To prevent freezing of the fluent when air temperature was near freezing point, the water was mixed with ethanol.…”

Section: Relaxed Eddy Accumulation (Rea)mentioning

confidence: 99%

“…The aqueous NH 3 solution from the two WEDDs was pumped with a constant flow directly to the analytical detection system which was located at the top floor of a scaffolding tower. A fluorescent compound was produced by mixing o-phthaldialdehyde (OPA), sulphite, and the aqueous NH 3 solution (Sorensen et al, 1994). The liquid was heated to 60 • C to enhance the formation of the fluorescent compound before injection into the fluorescence detector.…”

Section: Relaxed Eddy Accumulation (Rea)mentioning

confidence: 99%

Ammonia emissions from deciduous forest after leaf fall

et al. 2013

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The understanding of biochemical feedback mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH₃) exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH₃ fluxes during a 25-day period during autumn 2010 (21 October to 15 November) for the Danish beech forest Lille Bøgeskov to address the hypothesis that NH₃ emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH₃ fluxes and model calculations. Vegetation status was observed using plant area index (PAI) and leaf area index (LAI). NH₃ fluxes were measured using the relaxed eddy accumulation (REA) method. The REA-based NH₃ concentrations were compared to NH₃ denuder measurements. Model calculations of the atmospheric NH₃ concentration were obtained with the Danish Ammonia MOdelling System (DAMOS). The relative contribution from the forest components to the atmospheric NH₃ flux was assessed using a simple two-layer bi-directional canopy compensation point model. A total of 57.7% of the fluxes measured showed emission and 19.5% showed deposition. A clear tendency of the flux going from deposition of −0.25 ± 0.30 μg NH₃-N m⁻² s⁻¹ to emission of up to 0.67 ± 0.28 μg NH₃-N m⁻² s⁻¹ throughout the measurement period was found. In the leaf fall period (23 October to 8 November), an increase in the atmospheric NH₃ concentrations was related to the increasing forest NH₃ flux. Following leaf fall, the magnitude and temporal structure of the measured NH₃ emission fluxes could be adequately reproduced with the bi-directional resistance model; it suggested the forest ground layer (soil and litter) to be the main contributing component to the NH₃ emissions. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall, but during and after leaf fall, the modelled concentrations are too low. The results indicate that the missing contribution to atmospheric NH₃ concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH₃ for forest ecosystems. Finally, diurnal variations in the measured NH₃ concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH₃ sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes

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“…Diffusion-based methods such as the diffusion denuder [11][12][13][14] and the diffusion scrubber 4,15,16 are used for the separate sampling of gaseous and particulate species in the atmosphere. Using a diffusion denuder, water soluble gases are absorbed into the thin film of the absorbent, typically water or an aqueous solution, which flows over the surface of chemically-treated glass.…”

Section: 10mentioning

confidence: 99%

Development of an Automated Diffusion Scrubber-Conductometry System for Measuring Atmospheric Ammonia

Lee

Lee³

2011

Bulletin of the Korean Chemical Society

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A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with r 2 = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, r 2 = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia.

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Diffusion scrubber technique used for measurements of atmospheric ammonia

Cited by 37 publications

References 33 publications

Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

Ammonia emissions from deciduous forest after leaf fall

Development of an Automated Diffusion Scrubber-Conductometry System for Measuring Atmospheric Ammonia

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