Distal and proximal controls on the silicon stable isotope signature of North Atlantic Deep Water ...

It has been suggested that the uniquely high δ30Si signature of North Atlantic Deep Water (NADW) results from the contribution of isotopically fractionated silicic acid by mode and intermediate waters that are formed in the Southern Ocean and transported to the North Atlantic within the upper limb o...

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Bibliographic Details
Main Authors: de Souza, Gregory F., Slater, Richard D., Hain, Mathis P., Brzezinski, Mark A., Sarmiento, Jorge L.
Format: Text
Language:English
Published: ETH Zurich 2015
Subjects:
biogeochemical cycles
silicon isotopes
meridional overturning circulation
Southern Ocean
NADW
North Atlantic Deep Water
North Atlantic
Online Access:https://dx.doi.org/10.3929/ethz-b-000106285
http://hdl.handle.net/20.500.11850/261833
Description
Summary:It has been suggested that the uniquely high δ30Si signature of North Atlantic Deep Water (NADW) results from the contribution of isotopically fractionated silicic acid by mode and intermediate waters that are formed in the Southern Ocean and transported to the North Atlantic within the upper limb of the meridional overturning circulation (MOC). Here, we test this hypothesis in a suite of ocean general circulation models (OGCMs) with widely varying MOCs and related pathways of nutrient supply to the upper ocean. Despite their differing MOC pathways, all models reproduce the observation of a high δ30Si signature in NADW, as well showing a major or dominant (46–62%) contribution from Southern Ocean mode/intermediate waters to its Si inventory. These models thus confirm that the δ30Si signature of NADW does indeed owe its existence primarily to the large-scale transport of a distal fractionation signal created in the surface Southern Ocean. However, we also find that more proximal fractionation of Si upwelled ... : Earth and Planetary Science Letters, 432 ...

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