Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean
Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean
Atmospheric iron and underway sea-surface dissolved (<0.2 m) iron (DFe) concentrations were investigated along a north–south transect in the eastern Atlantic Ocean (27°N/16°W–19°S/5°E). Fe concentrations in aerosols and dry deposition fluxes of soluble Fe were at least two orders of magnitude higher in the Saharan dust plume than at the equator or at the extreme south of the transect. A weaker source of atmospheric Fe was also observed in the South Atlantic, possibly originating in southern Africa via the north-easterly outflow of the Angolan plume. Estimations of total atmospheric deposition fluxes (dry plus wet) of soluble Fe suggested that wet deposition dominated in the intertropical convergence zone, due to the very high amount of precipitation and to the fact that a substantial part of Fe was delivered in dissolved form. On the other hand, dry deposition dominated in the other regions of the transect (73–97%), where rainfall rates were much lower. Underway sea-surface DFe concentrations ranged 0.02–1.1 nM. Such low values (0.02 nM) are reported for the first time in the Atlantic Ocean and may be (co)-limiting for primary production. A significant correlation (Spearman's RHO=0.862, p<0.01) was observed between mean DFe concentrations and total atmospheric deposition fluxes, confirming the importance of atmospheric deposition on the iron cycle in the Atlantic. Residence time of DFe in the surface waters relative to atmospheric inputs were estimated in the northern part of our study area (17±8 to 28±16 d). These values confirmed the rapid removal of Fe from the surface waters, possibly by colloidal aggregation.
Dissolved iron, Aerosol iron, Sea surface, Iron supply, Atmospheric (wet and dry) deposition, Residence time
1339-1352
Sarthou, G.
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Baker, A.R.
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Blain, S.
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Achterberg, E.P.
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Boye, M.
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Bowie, A.R.
9e60fe12-98c0-4ea7-9c2f-126a997a9f7b
Croot, P.
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Laan, P.
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De Baar, H.J.W.
c23aa060-a4a6-4fb6-a4ed-892b022d2410
Jickells, T.D.
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Worsfold, P.J.
2edcddc5-ce8e-4f9f-8628-216a26921979
2003
Sarthou, G.
06d8eba4-f933-4093-a5f3-4e4c8bf602ef
Baker, A.R.
2e470bae-1030-49cb-999e-1a0bfb0abfc9
Blain, S.
45cb2a77-ae57-4524-a737-350f43cedb7e
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Boye, M.
6a3fb926-e1ed-40cc-87a0-63c9870f782b
Bowie, A.R.
9e60fe12-98c0-4ea7-9c2f-126a997a9f7b
Croot, P.
16ae23f9-d3c9-4d1b-9afe-966acd88cf20
Laan, P.
bbf648a3-0a1e-4d95-8dc6-9e08ea200e18
De Baar, H.J.W.
c23aa060-a4a6-4fb6-a4ed-892b022d2410
Jickells, T.D.
d85be7a3-239c-402f-83a6-8014b78cc4cc
Worsfold, P.J.
2edcddc5-ce8e-4f9f-8628-216a26921979
Sarthou, G., Baker, A.R., Blain, S., Achterberg, E.P., Boye, M., Bowie, A.R., Croot, P., Laan, P., De Baar, H.J.W., Jickells, T.D. and Worsfold, P.J.
(2003)
Atmospheric iron deposition and sea-surface dissolved iron concentrations in the eastern Atlantic Ocean.
Deep Sea Research Part I: Oceanographic Research Papers, 50 (10-11), .
(doi:10.1016/S0967-0637(03)00126-2).
Abstract
Atmospheric iron and underway sea-surface dissolved (<0.2 m) iron (DFe) concentrations were investigated along a north–south transect in the eastern Atlantic Ocean (27°N/16°W–19°S/5°E). Fe concentrations in aerosols and dry deposition fluxes of soluble Fe were at least two orders of magnitude higher in the Saharan dust plume than at the equator or at the extreme south of the transect. A weaker source of atmospheric Fe was also observed in the South Atlantic, possibly originating in southern Africa via the north-easterly outflow of the Angolan plume. Estimations of total atmospheric deposition fluxes (dry plus wet) of soluble Fe suggested that wet deposition dominated in the intertropical convergence zone, due to the very high amount of precipitation and to the fact that a substantial part of Fe was delivered in dissolved form. On the other hand, dry deposition dominated in the other regions of the transect (73–97%), where rainfall rates were much lower. Underway sea-surface DFe concentrations ranged 0.02–1.1 nM. Such low values (0.02 nM) are reported for the first time in the Atlantic Ocean and may be (co)-limiting for primary production. A significant correlation (Spearman's RHO=0.862, p<0.01) was observed between mean DFe concentrations and total atmospheric deposition fluxes, confirming the importance of atmospheric deposition on the iron cycle in the Atlantic. Residence time of DFe in the surface waters relative to atmospheric inputs were estimated in the northern part of our study area (17±8 to 28±16 d). These values confirmed the rapid removal of Fe from the surface waters, possibly by colloidal aggregation.
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Published date: 2003
Keywords:
Dissolved iron, Aerosol iron, Sea surface, Iron supply, Atmospheric (wet and dry) deposition, Residence time
Identifiers
Local EPrints ID: 12535
URI: http://eprints.soton.ac.uk/id/eprint/12535
ISSN: 0967-0637
PURE UUID: 8b4f8748-b155-4a3d-b562-59bfb82ad7f7
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Date deposited: 26 Nov 2004
Last modified: 15 Mar 2024 05:06
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Contributors
Author:
G. Sarthou
Author:
A.R. Baker
Author:
S. Blain
Author:
M. Boye
Author:
A.R. Bowie
Author:
P. Croot
Author:
P. Laan
Author:
H.J.W. De Baar
Author:
T.D. Jickells
Author:
P.J. Worsfold
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