Data-based assessment of environmental controls on global marine nitrogen fixation
There are a number of hypotheses concerning the environmental controls on marine nitrogen fixation (NF). Most of these hypotheses have not been assessed against direct measurements on the global scale. In this study, we use ~ 500 depth-integrated field measurements of NF covering the Pacific and Atl...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/691/2014/bg-11-691-2014.pdf |
| _version_ | 1818562531375972352 |
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| author | Y.-W. Luo I. D. Lima D. M. Karl C. A. Deutsch S. C. Doney |
| author_facet | Y.-W. Luo I. D. Lima D. M. Karl C. A. Deutsch S. C. Doney |
| author_sort | Y.-W. Luo |
| collection | DOAJ |
| description | There are a number of hypotheses concerning the environmental controls on marine
nitrogen fixation (NF). Most of these hypotheses have not been assessed
against direct measurements on the global scale. In this study, we use
~ 500 depth-integrated field measurements of NF covering the Pacific
and Atlantic oceans to test whether the spatial variance of these
measurements can be explained by the commonly hypothesized environmental
controls, including measurement-based surface solar radiation, mixed layer
depth, average solar radiation in the mixed layer, sea surface temperature,
wind speed, surface nitrate and phosphate concentrations, surface excess
phosphate (P<sup>*</sup>) concentration and subsurface minimum dissolved oxygen
(in upper 500 m), as well as model-based P<sup>*</sup> convergence and
atmospheric dust deposition. By conducting simple linear regression and
stepwise multiple linear regression (MLR) analyses, surface solar radiation
(or sea surface temperature) and subsurface minimum dissolved oxygen are
identified as the predictors that explain the most spatial variance in the
observed NF data, although it is unclear why the observed NF decreases when
the level of subsurface minimum dissolved oxygen is higher than
~ 150 μM. Dust deposition and wind speed do not appear to
influence the spatial patterns of NF on global scale. The weak correlation
between the observed NF and the P<sup>*</sup> convergence and concentrations
suggests that the available data currently remain insufficient to fully
support the hypothesis that spatial variability in denitrification is the
principal control on spatial variability in marine NF. By applying the
MLR-derived equation, we estimate the global-integrated NF at 74 (error range
51–110) Tg N yr<sup>−1</sup> in the open ocean, acknowledging that it could be
substantially higher as the <sup>15</sup>N<sub>2</sub>-assimilation method used by most
of the field samples underestimates NF. More field NF samples in the Pacific
and Indian oceans, particularly in the oxygen minimum zones, are needed to
reduce uncertainties in our conclusion. |
| first_indexed | 2024-12-14T01:04:58Z |
| format | Article |
| id | doaj.art-3db9aa1950104ace98a98dd0d150b7bd |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-14T01:04:58Z |
| publishDate | 2014-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-3db9aa1950104ace98a98dd0d150b7bd2022-12-21T23:23:00ZengCopernicus PublicationsBiogeosciences1726-41701726-41892014-02-0111369170810.5194/bg-11-691-2014Data-based assessment of environmental controls on global marine nitrogen fixationY.-W. Luo0I. D. Lima1D. M. Karl2C. A. Deutsch3S. C. Doney4Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USACenter for Microbial Oceanography: Research and Education, University of Hawaii, Honolulu, Hawaii, USASchool of Oceanography, University of Washington, Seattle, Washington, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USAThere are a number of hypotheses concerning the environmental controls on marine nitrogen fixation (NF). Most of these hypotheses have not been assessed against direct measurements on the global scale. In this study, we use ~ 500 depth-integrated field measurements of NF covering the Pacific and Atlantic oceans to test whether the spatial variance of these measurements can be explained by the commonly hypothesized environmental controls, including measurement-based surface solar radiation, mixed layer depth, average solar radiation in the mixed layer, sea surface temperature, wind speed, surface nitrate and phosphate concentrations, surface excess phosphate (P<sup>*</sup>) concentration and subsurface minimum dissolved oxygen (in upper 500 m), as well as model-based P<sup>*</sup> convergence and atmospheric dust deposition. By conducting simple linear regression and stepwise multiple linear regression (MLR) analyses, surface solar radiation (or sea surface temperature) and subsurface minimum dissolved oxygen are identified as the predictors that explain the most spatial variance in the observed NF data, although it is unclear why the observed NF decreases when the level of subsurface minimum dissolved oxygen is higher than ~ 150 μM. Dust deposition and wind speed do not appear to influence the spatial patterns of NF on global scale. The weak correlation between the observed NF and the P<sup>*</sup> convergence and concentrations suggests that the available data currently remain insufficient to fully support the hypothesis that spatial variability in denitrification is the principal control on spatial variability in marine NF. By applying the MLR-derived equation, we estimate the global-integrated NF at 74 (error range 51–110) Tg N yr<sup>−1</sup> in the open ocean, acknowledging that it could be substantially higher as the <sup>15</sup>N<sub>2</sub>-assimilation method used by most of the field samples underestimates NF. More field NF samples in the Pacific and Indian oceans, particularly in the oxygen minimum zones, are needed to reduce uncertainties in our conclusion.http://www.biogeosciences.net/11/691/2014/bg-11-691-2014.pdf |
| spellingShingle | Y.-W. Luo I. D. Lima D. M. Karl C. A. Deutsch S. C. Doney Data-based assessment of environmental controls on global marine nitrogen fixation Biogeosciences |
| title | Data-based assessment of environmental controls on global marine nitrogen fixation |
| title_full | Data-based assessment of environmental controls on global marine nitrogen fixation |
| title_fullStr | Data-based assessment of environmental controls on global marine nitrogen fixation |
| title_full_unstemmed | Data-based assessment of environmental controls on global marine nitrogen fixation |
| title_short | Data-based assessment of environmental controls on global marine nitrogen fixation |
| title_sort | data based assessment of environmental controls on global marine nitrogen fixation |
| url | http://www.biogeosciences.net/11/691/2014/bg-11-691-2014.pdf |
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