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Impact of atmospheric deposition on the contrasting iron biogeochemistry of the North and South Atlantic Ocean

Impact of atmospheric deposition on the contrasting iron biogeochemistry of the North and South Atlantic Ocean
Impact of atmospheric deposition on the contrasting iron biogeochemistry of the North and South Atlantic Ocean
Dissolved iron (dFe) distributions and atmospheric and vertical subduction fluxes of dFe were determined in the upper water column for two meridional transects of the Atlantic Ocean. The data demonstrate the disparity between the iron biogeochemistry of the North and South Atlantic Ocean and show well-defined gradients of size fractionated iron species in surface waters between geographic provinces. The highest dFe and lowest mixed layer residence times (0.4–2.5 years) were found in the northern tropical and subtropical regions. In contrast, the South Atlantic Gyre had lower dFe concentrations (<0.4 nM) and much longer residence times (>5 years), presumably due to lower atmospheric inputs and more efficient biological recycling of iron in this region. Vertical input fluxes of dFe to surface waters ranged from 20 to 170 nmol m–2 d–1 in the North Atlantic and tropical provinces, whereas average fluxes of 6–13 nmol m–2 d–1 were estimated for the South Atlantic. Our estimates showed that the variable dFe distribution over the surface Atlantic (<0.1–2.0 nM) predominantly reflected atmospheric Fe deposition fluxes (>50% of total vertical Fe flux to surface waters) rather than upwelling or vertical mixing. This demonstrates the strength of the connection between land-derived atmospheric Fe fluxes and the biological cycling of carbon and nitrogen in the Atlantic Ocean.
iron, Atlantic Ocean, atmospheric deposition, aluminum
0886-6236
1096-1107
Ussher, Simon J.
089623db-1a7d-42b8-87d1-1f17395373b1
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Powell, Claire
3162d7c0-d237-4c19-9640-15650cf5dd23
Baker, Alex R.
3a011c8c-c15a-4080-9602-6f3628fdca4a
Jickells, Tim D.
b3d89e13-a093-41bf-b721-786c25504962
Torres, Ricardo
13e75325-69fe-415c-ad37-f9518d49fffc
Worsfold, Paul J.
27675f89-7eee-45c5-821e-a381d8db9693
Ussher, Simon J.
089623db-1a7d-42b8-87d1-1f17395373b1
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Powell, Claire
3162d7c0-d237-4c19-9640-15650cf5dd23
Baker, Alex R.
3a011c8c-c15a-4080-9602-6f3628fdca4a
Jickells, Tim D.
b3d89e13-a093-41bf-b721-786c25504962
Torres, Ricardo
13e75325-69fe-415c-ad37-f9518d49fffc
Worsfold, Paul J.
27675f89-7eee-45c5-821e-a381d8db9693

Ussher, Simon J., Achterberg, Eric P., Powell, Claire, Baker, Alex R., Jickells, Tim D., Torres, Ricardo and Worsfold, Paul J. (2013) Impact of atmospheric deposition on the contrasting iron biogeochemistry of the North and South Atlantic Ocean. Global Biogeochemical Cycles, 27 (4), 1096-1107. (doi:10.1002/gbc.20056).

Record type: Article

Abstract

Dissolved iron (dFe) distributions and atmospheric and vertical subduction fluxes of dFe were determined in the upper water column for two meridional transects of the Atlantic Ocean. The data demonstrate the disparity between the iron biogeochemistry of the North and South Atlantic Ocean and show well-defined gradients of size fractionated iron species in surface waters between geographic provinces. The highest dFe and lowest mixed layer residence times (0.4–2.5 years) were found in the northern tropical and subtropical regions. In contrast, the South Atlantic Gyre had lower dFe concentrations (<0.4 nM) and much longer residence times (>5 years), presumably due to lower atmospheric inputs and more efficient biological recycling of iron in this region. Vertical input fluxes of dFe to surface waters ranged from 20 to 170 nmol m–2 d–1 in the North Atlantic and tropical provinces, whereas average fluxes of 6–13 nmol m–2 d–1 were estimated for the South Atlantic. Our estimates showed that the variable dFe distribution over the surface Atlantic (<0.1–2.0 nM) predominantly reflected atmospheric Fe deposition fluxes (>50% of total vertical Fe flux to surface waters) rather than upwelling or vertical mixing. This demonstrates the strength of the connection between land-derived atmospheric Fe fluxes and the biological cycling of carbon and nitrogen in the Atlantic Ocean.

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More information

Published date: December 2013
Keywords: iron, Atlantic Ocean, atmospheric deposition, aluminum
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 361695
URI: http://eprints.soton.ac.uk/id/eprint/361695
ISSN: 0886-6236
PURE UUID: c47f7847-6cfa-423c-8faf-eb20f260d8d9

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Date deposited: 30 Jan 2014 11:11
Last modified: 08 Jan 2022 09:12

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Contributors

Author: Simon J. Ussher
Author: Claire Powell
Author: Alex R. Baker
Author: Tim D. Jickells
Author: Ricardo Torres
Author: Paul J. Worsfold

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