Southern ocean nitrogen and silicon dynamics during the last deglaciation

Silicon isotopes indicate enhanced carbon export efficiency in the North Atlantic during deglaciation

“…3), suggesting total Si(OH) 4 utilization. Such large and rapid changes in utilization exceeded any deglacial change in Si utilization in the Southern Ocean or Eastern Equatorial Pacific upwelling zones 31,32 , and are indicative of significant changes in upwelling and mixing at the inception of HS1. We can use the simple Si isotope fractionation model (after ref.…”

“…Palaeoceanographic records show that, during the deglacial, there were widespread pulses of diatom production, which we suggest were due to the abrupt breakdown of stratification, similar to-but to a greater extent than-today, as a result of different wind-driven mechanisms linked by atmospheric teleconnections, which supplied nutrients to large regions of the surface ocean rather than slow diffusion processes [4][5][6]31,41 . The E. rex pulse studied here either occurs at a similar time as, or at the inception of, increased diatom accumulation throughout Atlantic upwelling regions (for example, Northwest Atlantic 6,8,42 ).…”

A Review of the Stable Isotope Bio-geochemistry of the Global Silicon Cycle and Its Associated Trace Elements

“…To date, ∼10 studies have used diatom-bound δ 15 N obtained from sediment cores to reconstruct palaeo N cycling, with a strong focus on the Southern Ocean (e.g., Crosta and Shemesh, 2002;Robinson et al, 2004Robinson et al, , 2005Robinson and Sigman, 2008;Horn et al, 2011). Shemesh et al (1993) was the first to develop a method that used the organic matter contained within the hydrated SiO 2 matrix of the diatom, making it possible to measure diatom-bound N stable isotopes ( 15 N and 14 N).…”

“…To a certain extent, this can be estimated using simple box models (e.g., Beucher et al, 2007), and/or deep-water archives [see section Palaeoceanographic (and Palaeolimnological) Applications below Horn et al, 2011;Egan et al, 2013]. There is a potential that changes in water mass circulation, or end-member composition, could impact the distribution of silicon isotope ratios in the oceans ) (see section Global Water Column Distribution).…”

MESMO 2: a mechanistic marine silica cycle and coupling to a simple terrestrial scheme

“…Measurements of δ 30 Si in deep sea sediments offer an exciting possibility to investigate past changes in the marine silica cycle. Already a number of studies have made measurements of different sedimentary fractions such as opal (Horn et al, 2011) and sponge spicules .…”