Identifying the sources and drivers of variable nitrous oxide concentrations across the Eastern Tropical North Pacific
Abstract/Contents
- Abstract
- Nitrous oxide (N2O) is a powerful greenhouse gas, and oceanic sources account for up to one third of total flux to the atmosphere. In oxygen-deficient zones (ODZs) like the Eastern Tropical North Pacific (ETNP), N2O can be produced and consumed by several biological processes. In this study, the concentration and isotopocule ratios of N2O from a 2016 cruise to the ETNP were analyzed to examine the sources of and controls on N2O cycling across the region. Along the ~1000 km north-south transect, three distinct biogeochemical regimes were identified: background, core-ODZ, and high-N2O stations. Background stations were characterized by smaller variations in N2O concentration and isotopic profiles relative to the other regimes. Core-ODZ stations were characterized by co-occurring N2O production and consumption at anoxic depths, indicated by high δ18O-N2O (> 90‰) and low δ15N2Oβ (< -10‰) values, and confirmed by a time-dependent model, which indicated that N2O production via denitrification was significant and may occur with a non-zero site preference. High-N2O stations, located at the periphery of a mesoscale eddy, were defined by [N2O] reaching 126.07±12.6 nM and low oxygen concentrations expanding into near-surface isopycnals. At these stations, model results indicated significant N2O production from ammonia-oxidizing archaea and denitrification from nitrate at the N2O maximum within the oxycline, while bacterial nitrification and denitrification from nitrite were insignificant. This study also represents the first in the ETNP to link the magnitudes of N2O production mechanisms to a mesoscale eddy through isotopocule measurements, suggesting the importance of eddies to the spatiotemporal variability in N2O cycling and emissions from this region.
Description
| Type of resource | text |
|---|---|
| Date modified | December 5, 2022 |
| Publication date | June 16, 2022; May 24, 2022 |
Creators/Contributors
| Author | Monreal, Patrick |
https://orcid.org/0000-0001-5343-4142
(unverified)
|
|---|---|---|
| Thesis advisor | Casciotti, Karen |
https://orcid.org/0000-0002-5286-7795
(unverified)
|
| Thesis advisor | Francis, Christopher |
https://orcid.org/0000-0001-7557-631X
(unverified)
|
| Department | Earth Systems Program, Stanford University |
Subjects
| Subject | Nitrogen cycle |
|---|---|
| Subject | Greenhouse gases |
| Subject | Anoxic environments |
| Subject | Stable isotopes |
| Subject | Climate and interannual variability |
| Subject | Chemical oceanography |
| Subject | Oceanography > Research |
| Subject | Biogeochemistry |
| Genre | Text |
| Genre | Thesis |
Bibliographic information
| Related item | |
|---|---|
| DOI | https://doi.org/10.25740/wg105nm5963 |
| Location | https://purl.stanford.edu/wg105nm5963 |
Access conditions
- Use and reproduction
- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 4.0 International license (CC BY-NC).
Preferred citation
- Preferred citation
- Monreal, P. J. (2022). Identifying the sources and drivers of variable nitrous oxide concentrations across the Eastern Tropical North Pacific. Stanford Digital Repository. Available at https://purl.stanford.edu/wg105nm5963
Collection
Undergraduate Honors Theses, Doerr School of Sustainability
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- Contact
- pmonreal@stanford.edu
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