N and O isotope (δ15Nα, δ15Nβ, δ18O, δ17O) analyses of dissolved NO3− and NO2− by the Cd‐azide reduction method and N2O laser spectrometry

Wassenaar, Leonard I.; Douence, Cedric; Altabet, Mark A.; Aggarwal, Pradeep

doi:10.1002/rcm.8029

Cited by 28 publications

(13 citation statements)

References 30 publications

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“…Our findings confirm that natural abundance isotope studies of N 2 O provide a way to trace N 2 O production or destruction pathways, in particular when combined with supportive parameters or isotope modelling approaches (Denk et al, 2017). However, the complexity of N 2 O production pathways could not be fully accounted for, in particular abiotic processes; for example, N 2 O production by NH 2 OH oxidation (Heil et al, 2014) or NO − 2 reduction (Wei et al, 2017a) were not considered. These reactions yield N 2 O with high (34 ‰-35 ‰) or variable (8 ‰-12 ‰) SP and might therefore be falsely interpreted as nitrification-derived N 2 O.…”

Section: Comparisonmentioning

confidence: 54%

Attribution of N2O sources in a grassland soil with laser spectroscopy based isotopocule analysis

et al. 2019

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Nitrous oxide (N 2 O) is the primary atmospheric constituent involved in stratospheric ozone depletion and contributes strongly to changes in the climate system through a positive radiative forcing mechanism. The atmospheric abundance of N 2 O has increased from 270 ppb (parts per billion, 10 −9 mole mole −1 ) during the pre-industrial era to approx. 330 ppb in 2018. Even though it is well known that microbial processes in agricultural and natural soils are the major N 2 O source, the contribution of specific soil processes is still uncertain. The relative abundance of N 2 O isotopocules ( 14 N 14 N 16 N, 14 N 15 N 16 O, 15 N 14 N 16 O, and 14 N 14 N 18 O) carries process-specific information and thus can be used to trace production and consumption pathways. While isotope ratio mass spectroscopy (IRMS) was traditionally used for high-precision measurement of the isotopic composition of N 2 O, quantum cascade laser absorption spectroscopy (QCLAS) has been put forward as a complementary technique with the potential for on-site analysis. In recent years, pre-concentration combined with QCLAS has been presented as a technique to resolve subtle changes in ambient N 2 O isotopic composition.From the end of May until the beginning of August 2016, we investigated N 2 O emissions from an intensively managed grassland at the study site Fendt in southern Germany. In total, 612 measurements of ambient N 2 O were taken by com-bining pre-concentration with QCLAS analyses, yielding δ 15 N α , δ 15 N β , δ 18 O, and N 2 O concentration with a temporal resolution of approximately 1 h and precisions of 0.46 ‰, 0.36 ‰, 0.59 ‰, and 1.24 ppb, respectively. Soil δ 15 N-NO − 3 values and concentrations of NO − 3 and NH + 4 were measured to further constrain possible N 2 O-emitting source processes. Furthermore, the concentration footprint area of measured N 2 O was determined with a Lagrangian particle dispersion model (FLEXPART-COSMO) using local wind and turbulence observations. These simulations indicated that nighttime concentration observations were largely sensitive to local fluxes. While bacterial denitrification and nitrifier denitrification were identified as the primary N 2 O-emitting processes, N 2 O reduction to N 2 largely dictated the isotopic composition of measured N 2 O. Fungal denitrification and nitrification-derived N 2 O accounted for 34 %-42 % of total N 2 O emissions and had a clear effect on the measured isotopic source signatures. This study presents the suitability of on-site N 2 O isotopocule analysis for disentangling source and sink processes in situ and found that at the Fendt site bacterial denitrification or nitrifier denitrification is the major source for N 2 O, while N 2 O reduction acted as a major sink for soil-produced N 2 O.

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Section: Comparisonmentioning

confidence: 54%

Attribution of N2O sources in a grassland soil with laser spectroscopy based isotopocule analysis

et al. 2019

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“…The term δ 15 N bulk is used to express the average δ 15 N value and is equivalent to δ 15 N bulk = (δ 15 N α + δ 15 N β )/2. Extensive evidence has shown that SP, δ 15 N bulk and δ 18 O can be used to differentiate N 2 O source processes and biogeochemical cycling (Decock and Six, 2013;Denk et al, 2017;Heil et al, 2014;Lewicka-Szczebak et al, 2014Ostrom et al, 2007;Sutka et al, 2003Sutka et al, , 2006Toyoda et al, 2005Toyoda et al, , 2017Wei et al, 2017). Isotopocule abundances have been measured in a wide range of environments, including the troposphere (Harris et al, 2014;Röckmann and Levin, 2005;Toyoda et al, 2013), agricultural soils (Buchen et al, 2018;Ibraim et al, 2019;Köster et al, 2011;Mohn et al, 2012;Ostrom et al, 2007;Park et al, 2011;Pérez et al, 2001Pérez et al, , 2006Toyoda et al, 2011;Verhoeven et al, 2018Verhoeven et al, , 2019Well et al, 2008;Well and Flessa, 2009;Wolf et al, 2015), mixed urban-agricultural environments (Harris et al, 2017), coal and waste combustion (Harris et al, 2015b;Ogawa and Yoshida, 2005), fossil fuel combustion (Toyoda et al, 2008), wastewater treatment (Harris et al, 2015a, b;Wunderlin et al, 2012Wunderlin et al, , 2013, groundwater (Koba et al, 2009;Minamikawa et al, 2011;…”

Section: Introductionmentioning

confidence: 99%

N2O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison

et al. 2020

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Abstract. For the past two decades, the measurement of nitrous oxide (N2O) isotopocules – isotopically substituted molecules 14N15N16O, 15N14N16O and 14N14N18O of the main isotopic species 14N14N16O – has been a promising technique for understanding N2O production and consumption pathways. The coupling of non-cryogenic and tuneable light sources with different detection schemes, such as direct absorption quantum cascade laser absorption spectroscopy (QCLAS), cavity ring-down spectroscopy (CRDS) and off-axis integrated cavity output spectroscopy (OA-ICOS), has enabled the production of commercially available and field-deployable N2O isotopic analyzers. In contrast to traditional isotope-ratio mass spectrometry (IRMS), these instruments are inherently selective for position-specific 15N substitution and provide real-time data, with minimal or no sample pretreatment, which is highly attractive for process studies. Here, we compared the performance of N2O isotope laser spectrometers with the three most common detection schemes: OA-ICOS (N2OIA-30e-EP, ABB – Los Gatos Research Inc.), CRDS (G5131-i, Picarro Inc.) and QCLAS (dual QCLAS and preconcentration, trace gas extractor (TREX)-mini QCLAS, Aerodyne Research Inc.). For each instrument, the precision, drift and repeatability of N2O mole fraction [N2O] and isotope data were tested. The analyzers were then characterized for their dependence on [N2O], gas matrix composition (O2, Ar) and spectral interferences caused by H2O, CO2, CH4 and CO to develop analyzer-specific correction functions. Subsequently, a simulated two-end-member mixing experiment was used to compare the accuracy and repeatability of corrected and calibrated isotope measurements that could be acquired using the different laser spectrometers. Our results show that N2O isotope laser spectrometer performance is governed by an interplay between instrumental precision, drift, matrix effects and spectral interferences. To retrieve compatible and accurate results, it is necessary to include appropriate reference materials following the identical treatment (IT) principle during every measurement. Remaining differences between sample and reference gas compositions have to be corrected by applying analyzer-specific correction algorithms. These matrix and trace gas correction equations vary considerably according to N2O mole fraction, complicating the procedure further. Thus, researchers should strive to minimize differences in composition between sample and reference gases. In closing, we provide a calibration workflow to guide researchers in the operation of N2O isotope laser spectrometers in order to acquire accurate N2O isotope analyses. We anticipate that this workflow will assist in applications where matrix and trace gas compositions vary considerably (e.g., laboratory incubations, N2O liberated from wastewater or groundwater), as well as extend to future analyzer models and instruments focusing on isotopic species of other molecules.

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“…However, IRMS instruments are usually not suitable for field deployment. Recently, quantum cascade laser absorption spectroscopy (QCLAS) (Waechter et al, 2008;McManus et al, 2015), cavity ring-down spectroscopy (CRDS, Erler et al, 2015), and off-axis cavity output spectroscopy (OA-ICOS, Wassenaar et al, 2018) were introduced as alternatives for greenhouse gas (GHG) stable isotope analysis, with the capability for real-time, on-site analysis even at remote locations (Tuzson et al, 2011;Wolf et al, 2015;Eyer et al, 2016;Röckmann et al, 2016). Another advantage of spectroscopic techniques is 35 their ability for direct selective analysis of intra-molecular isotopic isomers (isotopomers) such as 14 N 15 N 16 O and 15 N 14 N 16 O, while the determination of the SP using IRMS is only possible via a detour of measuring δ 15 N-NO + in combination with δ 15 N bulk and a correcting for scrambling (Toyoda et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Attribution of N2O sources in a grassland soil with laser spectroscopy based isotopocule analysis

Ibraim¹,

Wolf²,

Harris³

et al. 2018

Preprint

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Abstract. Nitrous oxide (N2O) is the primary atmospheric constituent involved in stratospheric ozone depletion and contributes strongly to changes in the climate system through a positive radiative forcing mechanism. The atmospheric abundance of N2O has increased from 270&#8201;ppb during the pre-industrial era to approx. 330&#8201;ppb in 2018. Even though it is well known that microbial processes in agricultural and natural soils are the major N2O source, the contribution of specific soil processes is still uncertain. The relative abundance of N2O isotopocules (14N14N16N, 14N15N16O, 15N14N16O and 14N14N18O) carries process-specific in-formation and thus can be used to trace production and consumption pathways. While isotope ratio mass spectroscopy (IRMS) was traditionally used for high-precision measurement of the isotopic composition of N2O, quantum cascade laser absorption spectroscopy (QCLAS) has been put forward as a complementary technique with the potential for on-site analysis. In recent years, preconcentration combined with QCLAS has been presented as a technique to resolve subtle changes in ambient N2O isotopic composition. From the end of May until the beginning of August 2016, we investigated N2O emissions from an intensively managed grassland at the study site Fendt in Southern Germany. In total, 612 measurements of ambient N2O were taken by combining preconcentration with QCLAS analyses, yielding &#948;15N&#945;, &#948;15N&#946;, &#948;18O and N2O concentration with a temporal resolution of approximately one hour and precisions of 0.46&#8201;&#8240;, 0.36&#8201;&#8240;, 0.59&#8201;&#8240; and 1.24&#8201;ppb, respectively. Soil &#948;15N-NO3&#8722; values and concentrations of NO3&#8722; and NH4+ were measured to further constrain possible N2O-emitting source processes. Furthermore, the concentration footprint area of measured N2O was determined with a Lagrangian particle dispersion model (FLEXPART-COSMO) using local wind and turbulence observations. These simulations indicated that night-time concentration observations were largely sensitive to local fluxes. While bacterial denitrification and nitrifier denitrification were identified as the primary N2O-emitting processes, N2O reduction to N2 largely dictated the isotopic composition of measured N2O. Fungal denitrification and nitrification-derived N2O accounted for 34&#8211;42&#8201;% of total N2O emissions and had a clear effect on the measured isotopic source signatures. This study presents the suitability of on-site N2O isotopocule analysis for disentangling source and sink processes in-situ and found that at the Fendt site bacterial denitrification/nitrifier denitrification is the major source for N2O, while N2O reduction acted as a major sink.

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N and O isotope (δ¹⁵N^α, δ¹⁵N^β, δ¹⁸O, δ¹⁷O) analyses of dissolved NO₃⁻ and NO₂⁻ by the Cd‐azide reduction method and N₂O laser spectrometry

Cited by 28 publications

References 30 publications

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis

N<sub>2</sub>O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis

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N and O isotope (δ15Nα, δ15Nβ, δ18O, δ17O) analyses of dissolved NO3− and NO2− by the Cd‐azide reduction method and N2O laser spectrometry

Cited by 28 publications

References 30 publications

Attribution of N&lt;sub&gt;2&lt;/sub&gt;O sources in a grassland soil with laser spectroscopy based isotopocule analysis

Attribution of N&lt;sub&gt;2&lt;/sub&gt;O sources in a grassland soil with laser spectroscopy based isotopocule analysis

N&lt;sub&gt;2&lt;/sub&gt;O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison

Attribution of N&lt;sub&gt;2&lt;/sub&gt;O sources in a grassland soil with laser spectroscopy based isotopocule analysis

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N and O isotope (δ¹⁵N^α, δ¹⁵N^β, δ¹⁸O, δ¹⁷O) analyses of dissolved NO₃⁻ and NO₂⁻ by the Cd‐azide reduction method and N₂O laser spectrometry

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis

N<sub>2</sub>O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison

Attribution of N<sub>2</sub>O sources in a grassland soil with laser spectroscopy based isotopocule analysis