The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

Type Article
Date 2018-09
Language English
Author(s) Sutton Jill N.1, de Souza Gregory F.2, Garcia-Ibiliez Maribel I.3, 4, de La Rocha Christina L.1
Affiliation(s) 1 : Univ Brest, UMR 6539, CNRS, IFREMER,UBO,IRD,LEMAR,IUEM, F-29280 Plouzane, France.
2 : Swiss Fed Inst Technol, Inst Geochem & Petrol, Clausiusstr 25, CH-8092 Zurich, Switzerland.
3 : Bjerknes Ctr Climate Res, Uni Res Climate, N-5008 Bergen, Norway.
4 : CSIC, IIM, Eduardo Cabello 6, Vigo 36208, Spain.
Source Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2018-09 , Vol. 15 , N. 18 , P. 5663-5676
DOI 10.5194/bg-15-5663-2018
WOS© Times Cited 9
Note Special issue GEOVIDE, an international GEOTRACES study along the OVIDE section in the North Atlantic and in the Labrador Sea (GA01) Editor(s): G. Henderson, C. Jeandel, M. Lohan, G. Reverdin, and L. Bopp
Abstract

The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60°N) and Labrador Sea. Variations in δ30SiDSi below 500m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution.

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