Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study
It is well known that most primary production is fueled by regenerated nitrogen in the open ocean. Therefore, studying the nitrogen cycle by focusing on uptake and regeneration pathways would advance our understanding of nitrogen dynamics in the marine ecosystem. Here, we carry out a basin-scale mod...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2009-11-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/6/2647/2009/bg-6-2647-2009.pdf |
| _version_ | 1811287378934890496 |
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| author | R. Le Borgne R. Murtugudde X. J. Wang |
| author_facet | R. Le Borgne R. Murtugudde X. J. Wang |
| author_sort | R. Le Borgne |
| collection | DOAJ |
| description | It is well known that most primary production is fueled by regenerated nitrogen in the open ocean. Therefore, studying the nitrogen cycle by focusing on uptake and regeneration pathways would advance our understanding of nitrogen dynamics in the marine ecosystem. Here, we carry out a basin-scale modeling study, by assessing model simulations of nitrate and ammonium, and rates of nitrate uptake, ammonium uptake and regeneration in the equatorial Pacific. Model-data comparisons show that the model is able to reproduce many observed features of nitrate, ammonium, such as the deep ammonium maximum (DAM). The model also reproduces the observed de-coupling of ammonium uptake and regeneration, i.e., regeneration rate greater than uptake rate in the lower euphotic zone. The de-coupling largely explains the observed DAM in the equatorial Pacific Ocean. Our study indicates that zooplankton excretion and remineralization of organic nitrogen play a different role in nitrogen regeneration. Rates of zooplankton excretion vary from &lt;0.01 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> to 0.1 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> in the upper euphotic zone while rates of remineralization fall within a narrow range (0.015–0.025 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> . Zooplankton excretion contributes up to 70% of total ammonium regeneration in the euphotic zone, and is largely responsible for the spatial variability of nitrogen regeneration. However, remineralization provides a steady supply of ammonium in the upper ocean, and is a major source of inorganic nitrogen for the oligotrophic regions. Overall, ammonium generation and removal are approximately balanced over the top 150 m in the equatorial Pacific. |
| first_indexed | 2024-04-13T03:17:26Z |
| format | Article |
| id | doaj.art-4ee25ec9b103453b905460b4bc0088cc |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-13T03:17:26Z |
| publishDate | 2009-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-4ee25ec9b103453b905460b4bc0088cc2022-12-22T03:04:52ZengCopernicus PublicationsBiogeosciences1726-41701726-41892009-11-0161126472660Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling studyR. Le BorgneR. MurtuguddeX. J. WangIt is well known that most primary production is fueled by regenerated nitrogen in the open ocean. Therefore, studying the nitrogen cycle by focusing on uptake and regeneration pathways would advance our understanding of nitrogen dynamics in the marine ecosystem. Here, we carry out a basin-scale modeling study, by assessing model simulations of nitrate and ammonium, and rates of nitrate uptake, ammonium uptake and regeneration in the equatorial Pacific. Model-data comparisons show that the model is able to reproduce many observed features of nitrate, ammonium, such as the deep ammonium maximum (DAM). The model also reproduces the observed de-coupling of ammonium uptake and regeneration, i.e., regeneration rate greater than uptake rate in the lower euphotic zone. The de-coupling largely explains the observed DAM in the equatorial Pacific Ocean. Our study indicates that zooplankton excretion and remineralization of organic nitrogen play a different role in nitrogen regeneration. Rates of zooplankton excretion vary from &lt;0.01 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> to 0.1 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> in the upper euphotic zone while rates of remineralization fall within a narrow range (0.015–0.025 mmol m<sup>&minus;3</sup> d<sup>&minus;1</sup> . Zooplankton excretion contributes up to 70% of total ammonium regeneration in the euphotic zone, and is largely responsible for the spatial variability of nitrogen regeneration. However, remineralization provides a steady supply of ammonium in the upper ocean, and is a major source of inorganic nitrogen for the oligotrophic regions. Overall, ammonium generation and removal are approximately balanced over the top 150 m in the equatorial Pacific.http://www.biogeosciences.net/6/2647/2009/bg-6-2647-2009.pdf |
| spellingShingle | R. Le Borgne R. Murtugudde X. J. Wang Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study Biogeosciences |
| title | Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study |
| title_full | Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study |
| title_fullStr | Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study |
| title_full_unstemmed | Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study |
| title_short | Nitrogen uptake and regeneration pathways in the equatorial Pacific: a basin scale modeling study |
| title_sort | nitrogen uptake and regeneration pathways in the equatorial pacific a basin scale modeling study |
| url | http://www.biogeosciences.net/6/2647/2009/bg-6-2647-2009.pdf |
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