Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean
The overarching goal of this study is to simulate subsurface N* (sensu, Gruber and Sarmiento, 1997; GS97) anomaly patterns in the North Atlantic Ocean and determine the basin wide rates of N 2 -fixation that are required to do so. We present results from a new Atlantic implementation of a coupled ph...
Main Authors: | , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2007
|
Subjects: | |
Online Access: | https://doaj.org/article/e19c630d4dc94b739a3b2a311a3f523b |
id |
ftdoajarticles:oai:doaj.org/article:e19c630d4dc94b739a3b2a311a3f523b |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:e19c630d4dc94b739a3b2a311a3f523b 2023-05-15T17:36:46+02:00 Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean R. R. Hood V. J. Coles 2007-07-01T00:00:00Z https://doaj.org/article/e19c630d4dc94b739a3b2a311a3f523b EN eng Copernicus Publications http://www.biogeosciences.net/4/455/2007/bg-4-455-2007.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 https://doaj.org/article/e19c630d4dc94b739a3b2a311a3f523b Biogeosciences, Vol 4, Iss 4, Pp 455-479 (2007) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2007 ftdoajarticles 2022-12-31T13:58:10Z The overarching goal of this study is to simulate subsurface N* (sensu, Gruber and Sarmiento, 1997; GS97) anomaly patterns in the North Atlantic Ocean and determine the basin wide rates of N 2 -fixation that are required to do so. We present results from a new Atlantic implementation of a coupled physical-biogeochemical model that includes an explicit, dynamic representation of N 2 -fixation with light, nitrogen, phosphorus and iron limitations, and variable stoichiometric ratios. The model is able to reproduce nitrogen, phosphorus and iron concentration variability to first order. The latter is achieved by incorporating iron deposition directly into the model's detrital iron compartment which allows the model to reproduce sharp near surface gradients in dissolved iron concentration off the west coast of Africa and deep dissolved iron concentrations that have been observed in recent observational studies. The model can reproduce the large scale N* anomaly patterns but requires relatively high rates of surface nitrogen fixation to do so (1.8×10 12 moles N yr −1 from 10° N–30° N, 3.4×10 12 moles N yr −1 from 25° S–65° N). In the model the surface nitrogen fixation rate patterns are not co-located with subsurface gradients in N*. Rather, the fixed nitrogen is advected away from its source prior to generating a subsurface N* anomaly. Changes in the phosphorus remineralization rate (relative to nitrogen) linearly determine the surface nitrogen fixation rate because they change the degree of phosphorus limitation, which is the dominant limitation in the Atlantic in the model. Phosphorus remineralization rate must be increased by about a factor of 2 (relative to nitrogen) in order to generate subsurface N* anomalies that are comparable to the observations. We conclude that N 2 -fixation rate estimates for the Atlantic (and globally) may need to be revised upward, which will help resolve imbalances in the global nitrogen budget suggested by Codispoti et al. (2001) and Codispoti (2007). Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Sarmiento ENVELOPE(-68.000,-68.000,-72.000,-72.000) |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 R. R. Hood V. J. Coles Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The overarching goal of this study is to simulate subsurface N* (sensu, Gruber and Sarmiento, 1997; GS97) anomaly patterns in the North Atlantic Ocean and determine the basin wide rates of N 2 -fixation that are required to do so. We present results from a new Atlantic implementation of a coupled physical-biogeochemical model that includes an explicit, dynamic representation of N 2 -fixation with light, nitrogen, phosphorus and iron limitations, and variable stoichiometric ratios. The model is able to reproduce nitrogen, phosphorus and iron concentration variability to first order. The latter is achieved by incorporating iron deposition directly into the model's detrital iron compartment which allows the model to reproduce sharp near surface gradients in dissolved iron concentration off the west coast of Africa and deep dissolved iron concentrations that have been observed in recent observational studies. The model can reproduce the large scale N* anomaly patterns but requires relatively high rates of surface nitrogen fixation to do so (1.8×10 12 moles N yr −1 from 10° N–30° N, 3.4×10 12 moles N yr −1 from 25° S–65° N). In the model the surface nitrogen fixation rate patterns are not co-located with subsurface gradients in N*. Rather, the fixed nitrogen is advected away from its source prior to generating a subsurface N* anomaly. Changes in the phosphorus remineralization rate (relative to nitrogen) linearly determine the surface nitrogen fixation rate because they change the degree of phosphorus limitation, which is the dominant limitation in the Atlantic in the model. Phosphorus remineralization rate must be increased by about a factor of 2 (relative to nitrogen) in order to generate subsurface N* anomalies that are comparable to the observations. We conclude that N 2 -fixation rate estimates for the Atlantic (and globally) may need to be revised upward, which will help resolve imbalances in the global nitrogen budget suggested by Codispoti et al. (2001) and Codispoti (2007). |
format |
Article in Journal/Newspaper |
author |
R. R. Hood V. J. Coles |
author_facet |
R. R. Hood V. J. Coles |
author_sort |
R. R. Hood |
title |
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
title_short |
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
title_full |
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
title_fullStr |
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
title_full_unstemmed |
Modeling the impact of iron and phosphorus limitations on nitrogen fixation in the Atlantic Ocean |
title_sort |
modeling the impact of iron and phosphorus limitations on nitrogen fixation in the atlantic ocean |
publisher |
Copernicus Publications |
publishDate |
2007 |
url |
https://doaj.org/article/e19c630d4dc94b739a3b2a311a3f523b |
long_lat |
ENVELOPE(-68.000,-68.000,-72.000,-72.000) |
geographic |
Sarmiento |
geographic_facet |
Sarmiento |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Biogeosciences, Vol 4, Iss 4, Pp 455-479 (2007) |
op_relation |
http://www.biogeosciences.net/4/455/2007/bg-4-455-2007.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 https://doaj.org/article/e19c630d4dc94b739a3b2a311a3f523b |
_version_ |
1766136359664222208 |