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Isotopomer labeling and oxygen dependence of hybrid nitrous oxide production

dc.contributor.authorC. L. Kelly
dc.contributor.authorC. L. Kelly
dc.contributor.authorN. M. Travis
dc.contributor.authorP. A. Baya
dc.contributor.authorC. Frey
dc.contributor.authorX. Sun
dc.contributor.authorB. B. Ward
dc.contributor.authorK. L. Casciotti
dc.contributor.authorK. L. Casciotti
dc.contributor.otherDepartment of Earth System Science, Stanford University, Stanford, CA 94305, USA
dc.contributor.otherDepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
dc.contributor.otherDepartment of Earth System Science, Stanford University, Stanford, CA 94305, USA
dc.contributor.otherDepartment of Earth System Science, Stanford University, Stanford, CA 94305, USA
dc.contributor.otherDepartment of Environmental Science, University of Basel, Basel, Switzerland
dc.contributor.otherDepartment of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USA
dc.contributor.otherDepartment of Geosciences, Princeton University, Princeton, NJ 08544, USA
dc.contributor.otherDepartment of Earth System Science, Stanford University, Stanford, CA 94305, USA
dc.contributor.otherOceans Department, Stanford University, Stanford, CA 94305, USA
dc.date.accessioned2024-07-17T06:34:12Z
dc.date.accessioned2025-10-08T09:23:17Z
dc.date.available2025-10-08T09:23:17Z
dc.date.issued01-07-2024
dc.identifier.urihttp://digilib.fisipol.ugm.ac.id/repo/handle/15717717/40183
dc.description.abstract<p>Nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O) is a potent greenhouse gas and ozone depletion agent, with a significant natural source from marine oxygen-deficient zones (ODZs). Open questions remain, however, about the microbial processes responsible for this N<span class="inline-formula"><sub>2</sub></span>O production, especially hybrid N<span class="inline-formula"><sub>2</sub></span>O production when ammonia-oxidizing archaea are present. Using <span class="inline-formula"><sup>15</sup></span>N-labeled tracer incubations, we measured the rates of N<span class="inline-formula"><sub>2</sub></span>O production from ammonium (NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="3fe22ea21bb8c3940d1d54b092ea883d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-3215-2024-ie00001.svg" width="8pt" height="15pt" src="bg-21-3215-2024-ie00001.png"/></svg:svg></span></span>), nitrite (NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">2</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="f7a532d5ce2f1361c746623f9ea69b14"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-3215-2024-ie00002.svg" width="9pt" height="16pt" src="bg-21-3215-2024-ie00002.png"/></svg:svg></span></span>), and nitrate (NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="7de8959157e6c258409d4c11688ca166"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-3215-2024-ie00003.svg" width="9pt" height="16pt" src="bg-21-3215-2024-ie00003.png"/></svg:svg></span></span>) in the eastern tropical North Pacific ODZ and the isotopic labeling of the central (<span class="inline-formula"><i>α</i></span>) and terminal (<span class="inline-formula"><i>β</i></span>) nitrogen (N) atoms of the N<span class="inline-formula"><sub>2</sub></span>O molecule. We observed production of both doubly and singly labeled N<span class="inline-formula"><sub>2</sub></span>O from each tracer, with the highest rates of labeled N<span class="inline-formula"><sub>2</sub></span>O production at the same depths as the near-surface N<span class="inline-formula"><sub>2</sub></span>O concentration maximum. At most stations and depths, the production of <span class="inline-formula"><sup>45</sup></span>N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sup><i>α</i></sup></span> and <span class="inline-formula"><sup>45</sup></span>N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sup><i>β</i></sup></span> were statistically indistinguishable, but at a few depths there were significant differences in the labeling of the two nitrogen atoms in the N<span class="inline-formula"><sub>2</sub></span>O molecule. Implementing the rates of labeled N<span class="inline-formula"><sub>2</sub></span>O production in a time-dependent numerical model, we found that N<span class="inline-formula"><sub>2</sub></span>O production from NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M24" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d615913ec88b34ee0c05b0f0374db64d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-3215-2024-ie00004.svg" width="9pt" height="16pt" src="bg-21-3215-2024-ie00004.png"/></svg:svg></span></span> dominated at most stations and depths, with rates as high as 1600 <span class="inline-formula">±</span> 200 pM N<span class="inline-formula"><sub>2</sub></span>O d<span class="inline-formula"><sup>−1</sup></span>. Hybrid N<span class="inline-formula"><sub>2</sub></span>O production, one of the mechanisms by which ammonia-oxidizing archaea produce N<span class="inline-formula"><sub>2</sub></span>O, had rates as high as 230 <span class="inline-formula">±</span> 80 pM N<span class="inline-formula"><sub>2</sub></span>O d<span class="inline-formula"><sup>−1</sup></span> that peaked in both the near-surface and deep N<span class="inline-formula"><sub>2</sub></span>O concentration maxima. Based on the equal production of <span class="inline-formula"><sup>45</sup></span>N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sup><i>α</i></sup></span> and <span class="inline-formula"><sup>45</sup></span>N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sup><i>β</i></sup></span> in the majority of our experiments, we infer that hybrid N<span class="inline-formula"><sub>2</sub></span>O production likely has a consistent site preference, despite drawing from two distinct substrate pools. We also found that the rates and yields of hybrid N<span class="inline-formula"><sub>2</sub></span>O production were enhanced at low dissolved oxygen concentrations ([O<span class="inline-formula"><sub>2</sub></span>]), with hybrid N<span class="inline-formula"><sub>2</sub></span>O yields as high as 20 % at depths where [O<span class="inline-formula"><sub>2</sub></span>] was below detection (880 nM) but nitrification was still active. Finally, we identified a few incubations with [O<span class="inline-formula"><sub>2</sub></span>] up to 20 <span class="inline-formula">µ</span>M where N<span class="inline-formula"><sub>2</sub></span>O production from NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M48" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="256fee4a33a420f3414d74c50d919438"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-21-3215-2024-ie00005.svg" width="9pt" height="16pt" src="bg-21-3215-2024-ie00005.png"/></svg:svg></span></span> was still active. A relatively high O<span class="inline-formula"><sub>2</sub></span> tolerance for N<span class="inline-formula"><sub>2</sub></span>O production via denitrification has implications for the feedbacks between marine deoxygenation and greenhouse gas cycling.</p>
dc.language.isoEN
dc.publisherCopernicus Publications
dc.subject.lccEcology
dc.titleIsotopomer labeling and oxygen dependence of hybrid nitrous oxide production
dc.typeArticle
dc.description.pages3215-3238
dc.description.doi10.5194/bg-21-3215-2024
dc.title.journalBiogeosciences
dc.identifier.e-issn1726-4189
dc.identifier.oaioai:doaj.org/journal:7a52158e3f6e43a1b068d3f6886163d1


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