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| Titel |
An assessment of the vertical diffusive flux of iron and other nutrients to the surface waters of the subpolar North Atlantic Ocean |
| VerfasserIn |
S. C. Painter, S. A. Henson, A. Forryan, S. Steigenberger, J. Klar, M. C. Stinchcombe, N. Rogan, A. R. Baker, E. P. Achterberg, C. M. Moore |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 8 ; Nr. 11, no. 8 (2014-04-16), S.2113-2130 |
| Datensatznummer |
250117364
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| Publikation (Nr.) |
 copernicus.org/bg-11-2113-2014.pdf |
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| Zusammenfassung |
| In this study we report diapycnal diffusive fluxes of dissolved iron (dFe),
dissolved aluminium (dAl) and the major macronutrients to the surface waters
of the North Atlantic subpolar gyre. Turbulent diffusivities at the base of
the summer mixed layer ranged from 0.01 to 0.5 (median 0.07) cm2 s−1
and daily macronutrient fluxes into the surface mixed layer typically
represented < 0.5% of integrated mixed layer inventories,
although fluxes were highly variable. Elevated nutrient fluxes of up to
4% of mixed layer inventories were identified on the Greenland Shelf,
where integrated nutrient pools were lowest due to localised shoaling of the
mixed layer. Diffusive fluxes of dFe and dAl were typically <0.1% of mixed layer inventories but were also highly variable between
stations. Approximations of daily phytoplankton nutrient and Fe uptake
indicate that the diffusive flux may at best represent <10% of
phytoplankton macronutrient uptake, and only 1% of daily phytoplankton Fe
uptake. The daily turbulent diffusive flux of dFe was comparable in
magnitude to coincident estimates of aeolian Fe supply but despite shallower
than normal convective mixing in winter 2010 the diffusive supply was 22 and 59 times smaller than the annual convective supply of Fe to the Irminger and
Iceland basins respectively. The general picture obtained from this study is
one of small magnitude diffusive nutrient and Fe fluxes to the subpolar
North Atlantic during the period of annual nutrient minima and indicates
that the diffusive supply mechanism is unlikely to alleviate the recently
identified presence of seasonal iron limitation within the North Atlantic
subpolar gyre; a condition exacerbated by low dFe:NO3− ratios in
subsurface source waters. |
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