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

<p>The stable isotope composition of dissolved silicon in seawater (<i>δ</i>³⁰Si_DSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60°&thinsp;N) and Labrador Sea. Variations in <i>δ</i>³⁰Si_DSi below 500&thinsp;m were closely tied to the distribution of water masses. Higher <i>δ</i>³⁰Si_DSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower <i>δ</i>³⁰Si_DSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest <i>δ</i>³⁰Si_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 <i>δ</i>³⁰Si_DSi distribution is marked clearly by Labrador Sea Water (LSW), whose high <i>δ</i>³⁰Si_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 <i>δ</i>³⁰Si_DSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE <i>δ</i>³⁰Si_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 <i>δ</i>³⁰Si_DSi distribution.</p>