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| Titel |
Continuous measurements of Nitrous Oxide isotopomers during incubation experiments |
| VerfasserIn |
Malte Nordmann Winther, Thomas Blunier, David Balslev-Harder, Bo Elberling, Anders Priemé, Søren Christensen |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126497
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| Publikation (Nr.) |
 EGU/EGU2016-6228.pdf |
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| Zusammenfassung |
| Nitrous oxide (N2O) is an important and strong trace greenhouse gas in the atmosphere;
it is part of a feed-back loop with climate. N2O is produced by microbes during
nitrification and denitrification in the terrestrial and oceanic realm where today 1∕3 of the
production is estimated to stem from oceanic sources. The position of the isotope 15N in
the linear N=N=O molecule can be distinguished between the central or terminal
position (the isotopomers of N2O). It has been demonstrated that nitrification and
denitrification have a relative preference for the terminal and central position, respectively.
Therefore it is claimed that measuring the site preference in N2O allows to determine
the responsible production process i.e. nitrification or denitrification. Our recent
instrument development in collaboration with Picarro Inc. allows for continuous position
dependent δ15N measurements. We present continuous results from incubation
experiments with denitrifying bacteria, Pseudomonas Fluorescens and Pseudomonas
Chlororaphis. We find bulk isotope effects of -11.3‰ to -8.3‰ for P. Chlororaphis. For P.
Fluorescens the isotope effect during production of N2O is in the range -47.7‰ to
-35.4‰ and between 1.9‰ and 12.6‰ during N2O reduction. The values for P.
Fluorescens is in line with earlier findings, whereas the values for P. Chlororaphis is
larger than previously published δ15Nbulk measurements from production. The
calculations of the site preference (SP) isotope effect from the measurements of P.
Chlororaphis results in values between 8.6‰ and 1.6‰. For P. Fluorescens the
calculations results in SP values between -11.6‰ and -0.8‰ during production
of N2O and between -8.1‰ and 5.0‰ during reduction of N2O. All measured
values of SP are in the range of previously published results for denitrifying bacteria. |
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