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

Hendry, Katharine R.; Robinson, Laura F.; McManus, Jerry F; Hays, James D.

doi:10.1038/ncomms4107

Cited by 36 publications

(40 citation statements)

References 59 publications

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“…In contrast, Hendry et al . [] recently measured a wide range of δ 30 Si for radiolarian (from 0.73 to 2‰) in the Sargasso Sea sediments. Hence, the trend of silicon isotopic composition of BSi in early spring could reflect the concomitant effect of a shift in water ventilation as well as a change in the composition of settling particles.…”

Section: Resultsmentioning

confidence: 99%

Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Closset

Cardinal

Bray

et al. 2015

Global Biogeochemical Cycles

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The Southern Ocean plays a pivotal role in the control of atmospheric CO 2 levels, via both physical and biological sequestration processes. The biological carbon transfer to the ocean interior is tightly coupled to the availability of other elements, especially iron as a trace-limiting nutrient and dissolved silicon as the mineral substrate that allows diatoms to dominate primary production. Importantly, variations in the silicon cycling are large but not well understood. Here we use δ 30 Si measurements to track seasonal flows of silica to the deep sea, as captured by sediment trap time series, for the three major zones (Antarctic, AZ; Polar Frontal, PFZ; and Sub-Antarctic, SAZ) of the open Southern Ocean. Variations in the exported flux of biogenic silica (BSi) and its δ 30 Si composition reveal a range of insights, including that (i) the sinking rate of BSi exceeds 200 m d À1 in summer in the AZ yet decreases to very low values in winter that allow particles to remain in the water column through to the following spring, (ii) occasional vertical mixing events affect the δ 30 Si composition of exported BSi in both the SAZ and AZ, and (iii) the δ 30 Si signature of diatoms is well conserved through the water column despite strong BSi and particulate organic carbon (POC) attenuation at depth and is closely linked to the Si consumption in surface waters. With the strong coupling observed between BSi and POC fluxes in PFZ and AZ, these data provide new constraints for application to biogeochemical models of seasonal controls on production and export.

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Section: Resultsmentioning

confidence: 99%

Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Closset

Cardinal

Bray

et al. 2015

Global Biogeochemical Cycles

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“…The red points are calibration data of handpicked (microscopic) mixed species from Wille et al (), Hendry et al (), and Hendry and Robinson (). The lightly shaded points represent “high silica” data (Griffiths et al, ; Hendry et al, , , ; Hendry & Robinson, ). The black crosses are “living” biogenic silica (outer rim in contact with seawater) of monospecific M. chuni samples (this paper).…”

Section: Methodsmentioning

confidence: 99%

Whole‐Ocean Changes in Silica and Ge/Si Ratios During the Last Deglacial Deduced From Long‐Lived Giant Glass Sponges

Jochum

Schuessler

Wang

et al. 2017

Geophysical Research Letters

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Silicon is a keystone nutrient in the ocean for understanding climate change because of the importance of Southern Ocean diatoms in taking up CO2 from the surface ocean‐atmosphere system and sequestering carbon into the deep sea. Here we report on silicon isotopes and germanium‐to‐silicon ratios in giant glass spicules of deep‐sea sponge Monorhaphis chuni over the past 17,000 years. In situ measurements of Si isotopes and Ge concentrations show systematic variations from rim to center of the cross sections. When calibrated against seawater concentrations using data from modern spicule rims, sponge data indicate that dissolved silica concentrations in the deep Pacific were ~12% higher during the early deglacial. These deep Pacific Ocean data help to fill an important global gap in paleo‐nutrient records. Either continental sources supplied more silica to the deglacial ocean and/or biogenic silica burial was lower, both of which may have affected atmospheric CO2.

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“…In that study, smaller Δ 30 Si values were associated with lower DSi concentrations, reflecting minimal fractionation at high degrees of DSi utilization as predicted by the closed‐system model, and the larger values of Δ 30 Si are thus probably closer to true 30 ε. Hendry et al . [] documented substantial Δ 30 Si variation in E . rex , from −0.46‰ to −1.4‰ (based on δ 30 Si diatom of +0.2‰ to +1.14‰ and an AAIW source δ 30 Si of +1.6‰; Figure ).…”

Section: Discussionmentioning

confidence: 98%

“…from diatom mats in surface waters of the central North Pacific is +0.9‰ to +1.9‰ [ De La Rocha et al ., ] and (2) the δ 30 Si of the >63 µm E . rex fraction extracted from a sediment core in the North Atlantic ranged from +0.2‰ to +1.14‰ [ Hendry et al ., ]. Differences in δ 30 Si between modern and ancient diatom species and E .…”

Section: Discussionmentioning

confidence: 99%

The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum

Xiong

Algeo

et al. 2015

Paleoceanography

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The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the easternPhilippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (δ 30 Si E. rex ) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, δ 30 Si E. rex varies from À1.23‰ to À0.83‰ (average À1.04‰), a range that is atypical of marine diatom δ 30Si and that corresponds to the lower limit of reported diatom δ 30Si values of any age. A binary mixing model (upwelled silicon versus eolian silicon) accounting for silicon isotopic fractionation during DSi uptake by diatoms was constructed. The binary mixing model demonstrates that E. rex dominantly utilized DSi from eolian sources (i.e., Asian dust) with only minor contributions from upwelled seawater sources (i.e., advected from Subantarctic Mode Water, Antarctic Intermediate Water, or North Pacific Intermediate Water). E. rex utilized only~24% of available DSi, indicating that surface waters of the EPS were eutrophic with respect to silicon during the LGM. Our results suggest that giant diatoms did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool, thus revising previously proposed models for the formation of E. rex LDMs.

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

Cited by 36 publications

References 59 publications

Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Seasonal variations, origin, and fate of settling diatoms in the Southern Ocean tracked by silicon isotope records in deep sediment traps

Whole‐Ocean Changes in Silica and Ge/Si Ratios During the Last Deglacial Deduced From Long‐Lived Giant Glass Sponges

The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum

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