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

• Published in: Biogeosciences
• Main Authors: Sutton, Jill N., Souza, Gregory F., García-Ibáñez, Maribel I., Rocha, Christina L.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Arctic; Arctic Ocean; Southern Ocean; Labrador Sea; North Atlantic
• Online Access: https://doi.org/10.5194/bg-15-5663-2018; https://www.biogeosciences.net/15/5663/2018/

The stable isotope composition of dissolved silicon in seawater ( δ 30 Si DSi ) 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 δ 30 Si DSi below 500 m were closely tied to the distribution of water masses. Higher δ 30 Si DSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ 30 Si DSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ 30 Si DSi 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 δ 30 Si DSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ 30 Si DSi 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 δ 30 Si DSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ 30 Si DSi 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 δ 30 Si DSi distribution.