Recent advances in measurement techniques for atmospheric carbon monoxide and nitrous oxide observations

Zellweger, Christoph; Steinbrecher, R.; Olivier, Laurent; Lee, Hoesung; Kim, Sumin; Emmenegger, Lukas; Steinbacher, Martin; Buchmann, B.

doi:10.5194/amt-12-5863-2019

Cited by 23 publications

(9 citation statements)

References 36 publications

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“…The precision of common GC analysers is < 0.5 ppb (Rapson and Dacres, 2014;van der Laan et al, 2009) while the precision of QCL was found to be about 0.3 ppb for measurements made at 10 Hz and 0.05 ppb for 1 Hz; but in some cases might be even higher (~1 ppt) (Curl et al, 2010;Rapson and Dacres, 2014;Savage et al, 2014). Zellweger et al (2019), for instance, used laboratory QCL for the calibration of N2O reference standards to inform the internationally accepted calibration scale of the Global Atmosphere Watch Programme of the World Meteorological Organisation. Similarly, Rosenstock et al (2013) preferred lab-based QCL to verify the accuracy and precision of different photoacoustic spectrometers.…”

Section: Measurement Performance Of Qcl Analysismentioning

confidence: 94%

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Wecking¹,

Cave²,

Liang³

et al. 2020

Preprint

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Abstract. The development of fast-response analysers for the measurement of nitrous oxide (N2O) has resulted in exciting opportunities for new experimental techniques beyond commonly used static chambers and gas chromatography (GC) analysis. For example, quantum cascade laser absorption spectrometers (QCL) are now being used with eddy covariance (EC) or automated chambers. However, using a field-based QCL EC system to also quantify N2O concentrations in gas samples taken from static chambers has not yet been explored. Gas samples from static chambers are commonly analysed by GC that often requires labour and time consuming procedures off-site. Here, we developed a novel, field-based injection technique that allowed the use of a single QCL for: (1) micrometeorological EC; and (2) immediate manual injection of headspace samples taken from static chambers. To test this approach across a range of low to high N2O fluxes, we applied ammonium nitrate (AN) at 0, 300, 600 and 900 kg N ha−1 (AN0, AN300, AN600, AN900) to plots on a pasture soil. After analysis, calculated N2O fluxes from QCL (FN2O_QCL) were compared with fluxes determined by a standard method, i.e. here laboratory-based GC (FN2O_GC). Subsequent comparison of QCL and GC derived data was tested using orthogonal regression, Bland Altman and bioequivalence statistics. For the AN treated plots, the mean cumulative N2O emissions across the seven day campaign were 0.97 (AN300), 1.26 (AN600) and 2.00 (AN900) kg N2O-N ha−1 for FN2O_QCL and 0.99 (AN300), 1.31 (AN600) and 2.03 (AN900) kg N2O-N ha−1 for FN2O_GC. These FN2O_QCL and FN2O_GC were highly correlated (r = 0.996, n = 81) based on orthogonal regression, in agreement following the Bland Altman approach (i.e. within ± 1.96 standard deviations of the mean) and shown to be for all intents and purposes the same (i.e. bioequivalent). The FN2O_QCL and FN2O_GC derived under near-zero flux conditions (AN0) were weakly correlated (r = 0.306, n = 27) and not found to agree or to be bioequivalent. This was likely caused by the calculation of small but apparent positive and negative FN2O when in fact the actual flux was zero, i.e. below the detection limit of static chambers. Our study demonstrated (1) that the capability of using one QCL to measure N2O at different scales, including manual injections, offered a great potential to advance field measurements of N2O (and other greenhouse gases) in future; and (2) that suitable statistics have to be adopted when formally assessing the agreement and difference (not only the correlation) between two methods of measurement.

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Section: Measurement Performance Of Qcl Analysismentioning

confidence: 94%

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Wecking¹,

Cave²,

Liang³

et al. 2020

Preprint

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“…This process for N 2 O is described in detail by Zellweger et al. (2019). Atmospheric research laboratories, including the NIWA Gas Laboratory in Wellington, produce their own working standards and quantify them on the current WMO scale by means of the scale transfer gases supplied by the CCL.…”

Section: Calibrationmentioning

confidence: 99%

Global Research Alliance N₂O chamber methodology guidelines: Recommendations for air sample collection, storage, and analysis

et al. 2020

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Certain aspects in the collection, handling, storage, and subsequent analysis of discrete air samples from non-steady-state flux chambers are critical to generating accurate and unbiased estimates of nitrous oxide (N 2 O) fluxes. The focus of this paper is on air sample collection and storage in small vials (<12 ml) primarily for gas chromatography (GC) analysis. Sample integrity is assured through following simple procedures including storage under pressure and analysis within a few months of collection. Concurrent storage of standards in an identical manner to samples is recommended and allows the storage period to be reliably extended. In the laboratory, an autosampler is typically used in batch analysis of ∼200 sequentially analyzed samples by GC with an electron capture detector (ECD). Some comparisons are given between GC and alternatives including optical N 2 O detectors that are increasingly being used for high-precision N 2 O measurement. The importance of calibration and traceability of gas standards is discussed, where high-quality standards ensure the most accurate assessment of N 2 O concentration and comparability between laboratories. The calibration allows a consistent and best estimate of flux to be derived.

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“…With respect to applying these WMO compatibility goals it should be mentioned that these precisions should be seen as the scientifically desirable level of compatibility for concurrent measurements of wellmixed background air by different laboratories, while they may not be the currently achievable best 1σ measurement uncertainty (Crotwell and Steinbacher, 2017). Indeed, a recent study by Zellweger et al (2019) indicated that the N 2 O network compatibility goal of 0.1 ppb remains quite challenging to meet even with current state-of-the-art measurement techniques. In Fig.…”

Section: Effects On Other Atmospheric Trace Gasesmentioning

confidence: 99%

Evaluation of a field-deployable Nafion™-based air-drying system for collecting whole air samples and its application to stable isotope measurements of CO<sub>2</sub>

et al. 2020

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Abstract. Atmospheric flask samples are either collected at atmospheric pressure by opening a valve of a pre-evacuated flask or pressurized with the help of a pump to a few bar above ambient pressure. Under humid conditions, there is a risk that water vapor in the sample leads to condensation on the walls of the flask, notably at higher than ambient sampling pressures. Liquid water in sample flasks is known to affect the CO2 mixing ratios and also alters the isotopic composition of oxygen (17O and 18O) in CO2 via isotopic equilibration. Hence, for accurate determination of CO2 mole fractions and its stable isotopic composition, it is vital to dry the air samples to a sufficiently low dew point before they are pressurized in flasks to avoid condensation. Moreover, the drying system itself should not influence the mixing ratio and the isotopic composition of CO2 or that of the other constituents under study. For the Airborne Stable Isotopes of Carbon from the Amazon (ASICA) project focusing on accurate measurements of CO2 and its singly substituted stable isotopologues over the Amazon, an air-drying system capable of removing water vapor from air sampled at a dew point lower than −2 ∘C, flow rates up to 12 L min−1 and without the need for electrical power was needed. Since to date no commercial air-drying device that meets these requirements has been available, we designed and built our own consumable-free, power-free and portable drying system based on multitube Nafion™ gas sample driers (Perma Pure, Lakewood, USA). The required dry purge air is provided by feeding the exhaust flow of the flask sampling system through a dry molecular sieve (type 3A) cartridge. In this study we describe the systematic evaluation of our Nafion™-based air sample dryer with emphasis on its performance concerning the measurements of atmospheric CO2 mole fractions and the three singly substituted isotopologues of CO2 (16O13C16O, 16O12C17O and 16O12C18O), as well as the trace gas species CH4, CO, N2O and SF6. Experimental results simulating extreme tropical conditions (saturated air at 33 ∘C) indicated that the response of the air dryer is almost instantaneous and that approximately 85 L of air, containing up to 4 % water vapor, can be processed staying below a −2 ∘C dew point temperature (at 275 kPa). We estimated that at least eight flasks can be sampled (at an overpressure of 275 kPa) with a water vapor content below −2 ∘C dew point temperature during a typical flight sampling up to 5 km altitude over the Amazon, whereas the remaining samples would stay well below 5 ∘C dew point temperature (at 275 kPa). The performance of the air dryer on measurements of CO2, CH4, CO, N2O, and SF6 and the CO2 isotopologues 16O13C16O and 16O12C18O was tested in the laboratory simulating real sampling conditions by compressing humidified air from a calibrated cylinder, after being dried by the air dryer, into sample flasks. We found that the mole fraction and the isotopic composition difference between the different test conditions (including the dryer) and the base condition (dry air, without dryer) remained well within or very close to, in the case of N2O, the World Meteorological Organization recommended compatibility goals for independent measurement programs, proving that the test condition induced no significant bias on the sample measurements.

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Recent advances in measurement techniques for atmospheric carbon monoxide and nitrous oxide observations

Abstract: fraction reported by near-IR CRDS instruments. This is reflected in the results of parallel measurement campaigns, which clearly indicate that drying the sample air leads to an improved accuracy of CO measurements with such near-IR CRDS instruments.

Cited by 23 publications

References 36 publications

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Global Research Alliance N₂O chamber methodology guidelines: Recommendations for air sample collection, storage, and analysis

Evaluation of a field-deployable Nafion™-based air-drying system for collecting whole air samples and its application to stable isotope measurements of CO<sub>2</sub>

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Recent advances in measurement techniques for atmospheric carbon monoxide and nitrous oxide observations

Abstract: fraction reported by near-IR CRDS instruments. This is reflected in the results of parallel measurement campaigns, which clearly indicate that drying the sample air leads to an improved accuracy of CO measurements with such near-IR CRDS instruments.

Cited by 23 publications

References 36 publications

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Global Research Alliance N2O chamber methodology guidelines: Recommendations for air sample collection, storage, and analysis

Evaluation of a field-deployable Nafion™-based air-drying system for collecting whole air samples and its application to stable isotope measurements of CO&lt;sub&gt;2&lt;/sub&gt;

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Product

Resources

About

Global Research Alliance N₂O chamber methodology guidelines: Recommendations for air sample collection, storage, and analysis

Evaluation of a field-deployable Nafion™-based air-drying system for collecting whole air samples and its application to stable isotope measurements of CO<sub>2</sub>