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Aluminium in the North Atlantic Ocean and the Labrador Sea (GEOTRACES GA01 section): roles of continental inputs and biogenic particle removal

Authors :
J.-L. Menzel Barraqueta
C. Schlosser
H. Planquette
A. Gourain
M. Cheize
J. Boutorh
R. Shelley
L. Contreira Pereira
M. Gledhill
M. J. Hopwood
F. Lacan
P. Lherminier
G. Sarthou
E. P. Achterberg
Source :
Biogeosciences, Vol 15, Pp 5271-5286 (2018)
Publication Year :
2018
Publisher :
Copernicus Publications, 2018.

Abstract

The distribution of dissolved aluminium (dAl) in the water column of the North Atlantic and Labrador Sea was studied along GEOTRACES section GA01 to unravel the sources and sinks of this element. Surface water dAl concentrations were low (median of 2.5 nM) due to low aerosol deposition and removal by biogenic particles (i.e. phytoplankton cells). However, surface water dAl concentrations were enhanced on the Iberian and Greenland shelves (up to 30.9 nM) due to continental inputs (rivers, glacial flour, and ice melt). Dissolved Al in surface waters scaled negatively with chlorophyll a and biogenic silica (opal) concentrations. The abundance of diatoms exerted a significant (p R2 > 0.76) west of the Iberian Basin, suggesting net release of dAl at depth during remineralization of sinking opal-containing particles. Enrichment of dAl at near-bottom depths was observed due to the resuspension of sediments. The highest dAl concentrations (up to 38.7 nM) were observed in Mediterranean Outflow Waters, which act as a major source of dAl to mid-depth waters of the eastern North Atlantic. This study clearly shows that the vertical and lateral distributions of dAl in the North Atlantic differ when compared to other regions of the Atlantic and global oceans. Responsible for these large inter- and intra-basin differences are the large spatial variabilities in the main Al source, atmospheric deposition, and the main Al sink, particle scavenging by biogenic particles.

Details

Language :
English
ISSN :
17264170 and 17264189
Volume :
15
Database :
Directory of Open Access Journals
Journal :
Biogeosciences
Publication Type :
Academic Journal
Accession number :
edsdoj.7f765957965c4519b0f07d2d5a7c6937
Document Type :
article
Full Text :
https://doi.org/10.5194/bg-15-5271-2018