Fractionation of N2O isotopomers in the stratosphere

Toyoda, Sakae; Yoshida, Naohiro; Urabe, Taichiro; Aoki, Shuji; Nakazawa, Takakiyo; Sugawara, Satoshi; Honda, Hiroaki

doi:10.1029/2000jd900680

Cited by 57 publications

(115 citation statements)

References 32 publications

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“…This was demonstrated for the reaction-diffusion system (Kaiser et al, 2002a;Kaye, 1987;Morgan et al, 2004), but is still valid even if advection is included due to the linearity of the corresponding differential equation (Kaiser and Röckmann, 2006 1 ). As noted in most previous publications on stratospheric N 2 O isotopes (e.g., Rahn et al, 1998;Röckmann et al, 2001;Toyoda et al, 2001), the stratospheric measurements clearly fall below the δ−µ relationship defined by the intrinsic isotope effect, which is due to transport and mixing effects. The magnitude of the intrinsic isotope effect used here is only an estimate because, on the one hand, the photolytic isotope effect is larger at lower (stratospheric) temperatures (Kaiser et al, 2002b;von Hessberg et al, 2004) and, on the other hand, the contribution of the photo-oxidation sink may vary (Sect.…”

Section: Isotope Variations In a Rayleigh Fractionation Frameworkmentioning

confidence: 80%

“…In a first step, we will interpret the data in a Rayleigh fractionation framework, as applied in past studies of stratospheric N 2 O Park et al, 2004;Rahn and Wahlen, 1997;Röckmann et al, 2001;Toyoda et al, 2001). As a second step and partly in response to a question raised by Park et al (2004), we explore to what extent simple two-end-member mixing can describe the covariation between isotope and mixing ratios and whether a more complex "continuous weak mixing" scheme (Plumb et al, 2000) can give a better description for part of the data.…”

Section: Resultsmentioning

confidence: 99%

“…The new analytical techniques were used for further stratospheric measurements, as evidenced by six publications Park et al, 2004;Röckmann et al, 2001;Toyoda et al, 2001Toyoda et al, , 2004Yoshida and Toyoda, 2000). The paper by Toyoda et al (2004) also contains the data from the earlier two papers by the same principal authors.…”

Section: Introductionmentioning

confidence: 99%

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Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N2O isotope distribution

et al. 2006

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Abstract.A comprehensive set of stratospheric balloon and aircraft samples was analyzed for the position-dependent isotopic composition of nitrous oxide (N 2 O). Results for a total of 220 samples from between 1987 and 2003 are presented, nearly tripling the number of mass-spectrometric N 2 O isotope measurements in the stratosphere published to date. Cryogenic balloon samples were obtained at polar (Kiruna/Sweden, 68 • N), mid-latitude (southern France, 44 • N) and tropical sites (Hyderabad/India, 18 • N). Aircraft samples were collected with a newly-developed whole air sampler on board of the high-altitude aircraft M55 Geophysica during the EUPLEX 2003 campaign. For mixing ratios above 200 nmol mol −1 , relative isotope enrichments (δ values) and mixing ratios display a compact relationship, which is nearly independent of latitude and season and which can be explained equally well by Rayleigh fractionation or mixing. However, for mixing ratios below 200 nmol mol −1 this compact relationship gives way to meridional, seasonal and interannual variations. A comparison to a previously published mid-latitude balloon profile even shows large zonal variations, justifying the use of three-dimensional (3-D) models for further data interpretation.In general, the magnitude of the apparent fractionation constants (i.e., apparent isotope effects) increases continuously with altitude and decreases from the equator to the North Pole. Only the latter observation can be understood qualitatively by the interplay between the time-scales of N 2 O photochemistry and transport in a Rayleigh fractionation framework. Deviations from Rayleigh fractionation behavior also occur where polar vortex air mixes with nearly N 2 O-free upper stratospheric/mesospheric air (e.g., during the boreal winters of 2003 and possibly 1992). Aircraft observations Correspondence to: J. Kaiser (J. Kaiser@uea.ac.uk) in the polar vortex at mixing ratios below 200 nmol mol −1 deviate from isotope variations expected for both Rayleigh fractionation and two-end-member mixing, but could be explained by continuous weak mixing between intravortex and extravortex air (Plumb et al., 2000). However, it appears that none of the simple approaches described here can capture all features of the stratospheric N 2 O isotope distribution, again justifying the use of 3-D models. Finally, correlations between 18 O/ 16 O and average 15 N/ 14 N isotope ratios or between the position-dependent 15 N/ 14 N isotope ratios show that photo-oxidation makes a large contribution to the total N 2 O sink in the lower stratosphere (possibly up to 100% for N 2 O mixing ratios above 300 nmol mol −1 ). Towards higher altitudes, the temperature dependence of these isotope correlations becomes visible in the stratospheric observations.

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Section: Isotope Variations In a Rayleigh Fractionation Frameworkmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

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Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N2O isotope distribution

et al. 2006

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“…The analysis of a single sample takes 30-60 min. The precision reported in earlier studies is typically 0.1-0.5 ‰ for 1 nmol of N 2 O (e.g., Toyoda et al, 2001) (See Sect. 2.4 for notation of isotopocule ratios), which is worse than the ultimate precision expected from the shot-noise limit of the IRMS (Potter et al, 2013) and which is insufficient to resolve the secular trend of atmospheric N 2 O isotopocule ratios.…”

Section: Introductionmentioning

confidence: 95%

Development of automated preparation system for isotopocule analysis of N2O in various air samples

Toyoda

Yoshida

2016

Atmos. Meas. Tech.

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Abstract. Nitrous oxide (N 2 O), an increasingly abundant greenhouse gas in the atmosphere, is the most important stratospheric ozone-depleting gas of this century. Natural abundance ratios of isotopocules of N 2 O, NNO molecules substituted with stable isotopes of nitrogen and oxygen, are a promising index of various sources or production pathways of N 2 O and of its sink or decomposition pathways. Several automated methods have been reported to improve the analytical precision for the isotopocule ratio of atmospheric N 2 O and to reduce the labor necessary for complicated sample preparation procedures related to mass spectrometric analysis. However, no method accommodates flask samples with limited volume or pressure. Here we present an automated preconcentration system which offers flexibility with respect to the available gas volume, pressure, and This precision is comparable to that of other automated systems, but better than that of our previously reported manual measurement system.

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“…Stratospheric photolysis of OCS occurs near the center of the cross section where the fractionation constant is close to zero. In contrast, N 2 O photolysis occurs on the low energy shoulder of the cross section giving rise to a large enrichment of heavy N 2 O in the stratosphere (Kim and Craig, 1993;Rahn and Wahlen, 1997;Toyoda et al, 2001;Röckmann et al, 2001;Prakash et al, 2005;Chen et al, 2008Chen et al, , 2010.…”

Section: Photolytic Isotope Effectsmentioning

confidence: 99%

OCS photolytic isotope effects from first principles: sulfur and carbon isotopes, temperature dependence and implications for the stratosphere

et al. 2013

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The isotopic fractionation in OCS photolysis is studied theoretically from first principles. UV absorption cross sections for OCS, OC33S, OC34S, OC36S and O13CS are calculated using the time-depedent quantum mechanical formalism and a recently developed ab-initio description of the photodissociation of OCS which takes into account the lowest four singlet and lowest four triplet electronic states. The calculated isotopic fractionations as a function of wavelength are in good agreement with recent measurements by Hattori et al. (2011) and indicate that photolysis leads to only a small enrichment of 34S in the remaining OCS. The photodissociation dynamics provide strong evidence that the photolysis quantum yield is unity at all wavelengths for atmospheric UV excitation, for all isotopologues. A simple stratospheric model is constructed taking into account the main sink reactions of OCS and it is found that overall stratospheric removal slightly favors light OCS in constrast to the findings of Leung et al. (2002). These results show, based on isotopic considerations, that OCS is an acceptable source of background stratosperic sulfate aerosol in agreement with a recent model study of of Brühl et al. (2012). The 13C isotopic fractionation due to photolysis of OCS in the upper stratosphere is significant and will leave a clear signal in the remaining OCS making it a candidate for tracing using the ACE-FTS and MIPAS data sets

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Fractionation of N₂O isotopomers in the stratosphere

Cited by 57 publications

References 32 publications

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N<sub>2</sub>O isotope distribution

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N<sub>2</sub>O isotope distribution

Development of automated preparation system for isotopocule analysis of N<sub>2</sub>O in various air samples

OCS photolytic isotope effects from first principles: sulfur and carbon isotopes, temperature dependence and implications for the stratosphere

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Fractionation of N2O isotopomers in the stratosphere

Cited by 57 publications

References 32 publications

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N&lt;sub&gt;2&lt;/sub&gt;O isotope distribution

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N&lt;sub&gt;2&lt;/sub&gt;O isotope distribution

Development of automated preparation system for isotopocule analysis of N&lt;sub&gt;2&lt;/sub&gt;O in various air samples

OCS photolytic isotope effects from first principles: sulfur and carbon isotopes, temperature dependence and implications for the stratosphere

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Fractionation of N₂O isotopomers in the stratosphere

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N<sub>2</sub>O isotope distribution

Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N<sub>2</sub>O isotope distribution

Development of automated preparation system for isotopocule analysis of N<sub>2</sub>O in various air samples