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Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability

Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability
Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability
Oceanic fixed-nitrogen concentrations are controlled by the balance between nitrogen fixation and denitrification1, 2, 3, 4. A number of factors, including iron limitation5, 6, 7, can restrict nitrogen fixation, introducing the potential for decoupling of nitrogen inputs and losses2, 5, 8. Such decoupling could significantly affect the oceanic fixed-nitrogen inventory and consequently the biological component of ocean carbon storage and hence air–sea partitioning of carbon dioxide2, 5, 8, 9. However, the extent to which nutrients limit nitrogen fixation in the global ocean is uncertain. Here, we examined rates of nitrogen fixation and nutrient concentrations in the surface waters of the Atlantic Ocean along a north–south 10,000 km transect during October and November 2005. We show that rates of nitrogen fixation were markedly higher in the North Atlantic compared with the South Atlantic Ocean. Across the two basins, nitrogen fixation was positively correlated with dissolved iron and negatively correlated with dissolved phosphorus concentrations. We conclude that inter-basin differences in nitrogen fixation are controlled by iron supply rather than phosphorus availability. Analysis of the nutrient content of deep waters suggests that the fixed nitrogen enters North Atlantic Deep Water. Our study thus supports the suggestion that iron significantly influences nitrogen fixation5, and that subsequent interactions with ocean circulation patterns contribute to the decoupling of nitrogen fixation and loss2, 4, 8.
1752-0894
867-871
Moore, C. Mark
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Mills, Matthew M.
eecbae85-0ebf-4d17-beb6-84b8862e7cf9
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Geider, Richard J.
f1432d5c-8c1d-48ab-ac52-e81ee5ce7f42
LaRoche, Julie
21d1685a-3dbd-4ccd-9ae4-e968c8792297
Lucas, Mike I.
3bb72027-86ed-4063-bf0d-ed9a667fc50e
McDonagh, Elaine L.
47e26eeb-b774-4068-af07-31847e42b977
Pan, Xi
ff91c9f9-28c6-465b-a4aa-51b879dbd611
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Rijkenberg, Micha J.A.
549cc6d0-6f1a-432f-863a-2988abcb25d3
Suggett, David J.
9100a791-1264-40e4-9403-8491190c3430
Ussher, Simon J.
089623db-1a7d-42b8-87d1-1f17395373b1
Woodward, E. Malcolm S.
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5
Moore, C. Mark
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Mills, Matthew M.
eecbae85-0ebf-4d17-beb6-84b8862e7cf9
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Geider, Richard J.
f1432d5c-8c1d-48ab-ac52-e81ee5ce7f42
LaRoche, Julie
21d1685a-3dbd-4ccd-9ae4-e968c8792297
Lucas, Mike I.
3bb72027-86ed-4063-bf0d-ed9a667fc50e
McDonagh, Elaine L.
47e26eeb-b774-4068-af07-31847e42b977
Pan, Xi
ff91c9f9-28c6-465b-a4aa-51b879dbd611
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Rijkenberg, Micha J.A.
549cc6d0-6f1a-432f-863a-2988abcb25d3
Suggett, David J.
9100a791-1264-40e4-9403-8491190c3430
Ussher, Simon J.
089623db-1a7d-42b8-87d1-1f17395373b1
Woodward, E. Malcolm S.
3a11b7bf-b110-448a-b1ee-ae1ce7d0fef5

Moore, C. Mark, Mills, Matthew M., Achterberg, Eric P., Geider, Richard J., LaRoche, Julie, Lucas, Mike I., McDonagh, Elaine L., Pan, Xi, Poulton, Alex J., Rijkenberg, Micha J.A., Suggett, David J., Ussher, Simon J. and Woodward, E. Malcolm S. (2009) Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability. Nature Geoscience, 2 (12), 867-871. (doi:10.1038/NGEO667).

Record type: Article

Abstract

Oceanic fixed-nitrogen concentrations are controlled by the balance between nitrogen fixation and denitrification1, 2, 3, 4. A number of factors, including iron limitation5, 6, 7, can restrict nitrogen fixation, introducing the potential for decoupling of nitrogen inputs and losses2, 5, 8. Such decoupling could significantly affect the oceanic fixed-nitrogen inventory and consequently the biological component of ocean carbon storage and hence air–sea partitioning of carbon dioxide2, 5, 8, 9. However, the extent to which nutrients limit nitrogen fixation in the global ocean is uncertain. Here, we examined rates of nitrogen fixation and nutrient concentrations in the surface waters of the Atlantic Ocean along a north–south 10,000 km transect during October and November 2005. We show that rates of nitrogen fixation were markedly higher in the North Atlantic compared with the South Atlantic Ocean. Across the two basins, nitrogen fixation was positively correlated with dissolved iron and negatively correlated with dissolved phosphorus concentrations. We conclude that inter-basin differences in nitrogen fixation are controlled by iron supply rather than phosphorus availability. Analysis of the nutrient content of deep waters suggests that the fixed nitrogen enters North Atlantic Deep Water. Our study thus supports the suggestion that iron significantly influences nitrogen fixation5, and that subsequent interactions with ocean circulation patterns contribute to the decoupling of nitrogen fixation and loss2, 4, 8.

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More information

Published date: 1 November 2009
Organisations: Ocean and Earth Science, National Oceanography Centre,Southampton

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Local EPrints ID: 71613
URI: http://eprints.soton.ac.uk/id/eprint/71613
ISSN: 1752-0894
PURE UUID: 34bddadd-30e7-4201-83a4-9e252eac0c17

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Date deposited: 15 Dec 2009
Last modified: 19 Jul 2019 23:44

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