First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland
The analysis of the four main isotopic N<sub>2</sub>O species (<sup>14</sup>N<sup>14</sup>N<sup>16</sup>O, <sup>14</sup>N<sup>15</sup>N<sup>16</sup>O, <sup>15</sup>N<sup>14</sup>N<sup>16...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-04-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/2517/2015/bg-12-2517-2015.pdf |
| _version_ | 1811257202086772736 |
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| author | B. Wolf L. Merbold C. Decock B. Tuzson E. Harris J. Six L. Emmenegger J. Mohn |
| author_facet | B. Wolf L. Merbold C. Decock B. Tuzson E. Harris J. Six L. Emmenegger J. Mohn |
| author_sort | B. Wolf |
| collection | DOAJ |
| description | The analysis of the four main isotopic N<sub>2</sub>O species
(<sup>14</sup>N<sup>14</sup>N<sup>16</sup>O, <sup>14</sup>N<sup>15</sup>N<sup>16</sup>O,
<sup>15</sup>N<sup>14</sup>N<sup>16</sup>O, <sup>14</sup>N<sup>14</sup>N<sup>18</sup>O) and especially the
intramolecular distribution of <sup>15</sup>N ("site preference", SP) has been
suggested as a tool to distinguish source processes and to help constrain the
global N<sub>2</sub>O budget. However, current studies suffer from limited spatial
and temporal resolution capabilities due to the combination of discrete flask
sampling with subsequent laboratory-based mass-spectrometric analysis.
Quantum cascade laser absorption spectroscopy (QCLAS) allows the selective
high-precision analysis of N<sub>2</sub>O isotopic species at trace levels and is
suitable for in situ measurements.
<br><br>
Here, we present results from the first field campaign, conducted on an
intensively managed grassland site in central Switzerland. N<sub>2</sub>O mole fractions
and isotopic composition were determined in the atmospheric surface layer
(at 2.2 m height) at a high temporal resolution with a modified state-of-the-art
laser spectrometer connected to an automated N<sub>2</sub>O preconcentration unit.
The analytical performance was determined from repeated measurements of a
compressed air tank and resulted in measurement repeatability of 0.20, 0.12
and 0.11‰ for δ<sup>15</sup>N<sup>α</sup>, δ<sup>15</sup>N<sup>β</sup>
and δ<sup>18</sup>O, respectively. Simultaneous eddy-covariance N<sub>2</sub>O flux
measurements were used to determine the flux-averaged isotopic signature of
soil-emitted N<sub>2</sub>O.
<br><br>
Our measurements indicate that, in general, nitrifier-denitrification and
denitrification were the prevalent sources of N<sub>2</sub>O during the campaign
and that variations in isotopic composition were due to alterations in
the extent to which N<sub>2</sub>O was reduced to N<sub>2</sub> rather than to other pathways, such
as hydroxylamine oxidation. Management and rewetting events were
characterized by low values of the intramolecular <sup>15</sup>N site preference
(SP), δ<sup>15</sup>N<sup>bulk</sup> and δ<sup>18</sup>O, suggesting that nitrifier-denitrification and incomplete heterotrophic bacterial denitrification
responded most strongly to the induced disturbances. The flux-averaged isotopic
composition of N<sub>2</sub>O from intensively managed grassland was
6.9 ± 4.3, −17.4 ± 6.2 and 27.4 ± 3.6‰ for SP,
δ<sup>15</sup>N<sup>bulk</sup> and δ<sup>18</sup>O, respectively. The approach
presented here is capable of providing long-term data sets also for other
N<sub>2</sub>O-emitting ecosystems, which can be used to further constrain global
N<sub>2</sub>O inventories. |
| first_indexed | 2024-04-12T17:52:45Z |
| format | Article |
| id | doaj.art-7297d5766ec84995bd5f1fa2ca6cd373 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-12T17:52:45Z |
| publishDate | 2015-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-7297d5766ec84995bd5f1fa2ca6cd3732022-12-22T03:22:26ZengCopernicus PublicationsBiogeosciences1726-41701726-41892015-04-011282517253110.5194/bg-12-2517-2015First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grasslandB. Wolf0L. Merbold1C. Decock2B. Tuzson3E. Harris4J. Six5L. Emmenegger6J. Mohn7Laboratory for Air Pollution/Environmental Technology, Empa, Überlandstrasse 129, 8600 Dübendorf, SwitzerlandDepartment of Environmental Systems Science, ETH Zurich, Universitätsstrasse 2, 8092 Zürich, SwitzerlandDepartment of Environmental Systems Science, ETH Zurich, Universitätsstrasse 2, 8092 Zürich, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Empa, Überlandstrasse 129, 8600 Dübendorf, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Empa, Überlandstrasse 129, 8600 Dübendorf, SwitzerlandDepartment of Environmental Systems Science, ETH Zurich, Universitätsstrasse 2, 8092 Zürich, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Empa, Überlandstrasse 129, 8600 Dübendorf, SwitzerlandLaboratory for Air Pollution/Environmental Technology, Empa, Überlandstrasse 129, 8600 Dübendorf, SwitzerlandThe analysis of the four main isotopic N<sub>2</sub>O species (<sup>14</sup>N<sup>14</sup>N<sup>16</sup>O, <sup>14</sup>N<sup>15</sup>N<sup>16</sup>O, <sup>15</sup>N<sup>14</sup>N<sup>16</sup>O, <sup>14</sup>N<sup>14</sup>N<sup>18</sup>O) and especially the intramolecular distribution of <sup>15</sup>N ("site preference", SP) has been suggested as a tool to distinguish source processes and to help constrain the global N<sub>2</sub>O budget. However, current studies suffer from limited spatial and temporal resolution capabilities due to the combination of discrete flask sampling with subsequent laboratory-based mass-spectrometric analysis. Quantum cascade laser absorption spectroscopy (QCLAS) allows the selective high-precision analysis of N<sub>2</sub>O isotopic species at trace levels and is suitable for in situ measurements. <br><br> Here, we present results from the first field campaign, conducted on an intensively managed grassland site in central Switzerland. N<sub>2</sub>O mole fractions and isotopic composition were determined in the atmospheric surface layer (at 2.2 m height) at a high temporal resolution with a modified state-of-the-art laser spectrometer connected to an automated N<sub>2</sub>O preconcentration unit. The analytical performance was determined from repeated measurements of a compressed air tank and resulted in measurement repeatability of 0.20, 0.12 and 0.11‰ for δ<sup>15</sup>N<sup>α</sup>, δ<sup>15</sup>N<sup>β</sup> and δ<sup>18</sup>O, respectively. Simultaneous eddy-covariance N<sub>2</sub>O flux measurements were used to determine the flux-averaged isotopic signature of soil-emitted N<sub>2</sub>O. <br><br> Our measurements indicate that, in general, nitrifier-denitrification and denitrification were the prevalent sources of N<sub>2</sub>O during the campaign and that variations in isotopic composition were due to alterations in the extent to which N<sub>2</sub>O was reduced to N<sub>2</sub> rather than to other pathways, such as hydroxylamine oxidation. Management and rewetting events were characterized by low values of the intramolecular <sup>15</sup>N site preference (SP), δ<sup>15</sup>N<sup>bulk</sup> and δ<sup>18</sup>O, suggesting that nitrifier-denitrification and incomplete heterotrophic bacterial denitrification responded most strongly to the induced disturbances. The flux-averaged isotopic composition of N<sub>2</sub>O from intensively managed grassland was 6.9 ± 4.3, −17.4 ± 6.2 and 27.4 ± 3.6‰ for SP, δ<sup>15</sup>N<sup>bulk</sup> and δ<sup>18</sup>O, respectively. The approach presented here is capable of providing long-term data sets also for other N<sub>2</sub>O-emitting ecosystems, which can be used to further constrain global N<sub>2</sub>O inventories.http://www.biogeosciences.net/12/2517/2015/bg-12-2517-2015.pdf |
| spellingShingle | B. Wolf L. Merbold C. Decock B. Tuzson E. Harris J. Six L. Emmenegger J. Mohn First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland Biogeosciences |
| title | First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland |
| title_full | First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland |
| title_fullStr | First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland |
| title_full_unstemmed | First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland |
| title_short | First on-line isotopic characterization of N<sub>2</sub>O above intensively managed grassland |
| title_sort | first on line isotopic characterization of n sub 2 sub o above intensively managed grassland |
| url | http://www.biogeosciences.net/12/2517/2015/bg-12-2517-2015.pdf |
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