Silicon isotopic fractionation in marine sponges: A new model for understanding silicon isotopic variations in sponges

Wille, Martin; Sutton, Jill; Ellwood, Michael J.; Sambridge, Malcolm; Maher, William A.; Eggins, Stephen; Kelly, Michelle

doi:10.1016/j.epsl.2010.01.036

Cited by 87 publications

(123 citation statements)

References 32 publications

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“…A clear trend between 30 Si and silicic acid concentration is observed in the mixed layer (Fig. 3b, non-linear regression using a power function, 30 Si = 0.40*[Si(OH) 4 ] 0.36 , R 2 = 0.61, p-value < 0.01), similar to the one obtained with sponge spicules (Wille et al, 2010;Hendry and Robinson, 2012 towards the surface (Table 1; see Fripiat et al, 2011b for a more complete discussion on water-column profiles of δ 30 Si Si(OH) 4 ), similar to previous studies (e.g. Cardinal et al, 2005).…”

Section: F Fripiat Et Al: Si-isotopic Composition In the Southern Osupporting

confidence: 65%

Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography

et al. 2012

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Abstract. Southern Ocean biogeochemical processes have an impact on global marine primary production and global elemental cycling, e.g. by likely controlling glacial-interglacial pCO 2 variation. In this context, the natural silicon isotopic composition (δ 30 Si) of sedimentary biogenic silica has been used to reconstruct past Si-consumption:supply ratios in the surface waters. We present a new dataset in the Southern Ocean from a IPY-GEOTRACES transect (BonusGoodHope) which includes for the first time summer δ 30 Si signatures of suspended biogenic silica (i) for the whole water column at three stations and (ii) in the mixed layer at seven stations from the subtropical zone up to the Weddell Gyre. In general, the isotopic composition of biogenic opal exported to depth was comparable to the opal leaving the mixed layer and did not seem to be affected by any diagenetic processes during settling, even if an effect of biogenic silica dissolution cannot be ruled out in the northern part of the Weddell Gyre. We develop a mechanistic understanding of the processes involved in the modern Si-isotopic balance, by implementing a mixed layer model. We observe that the accumulated biogenic silica (sensu Rayleigh distillation) should satisfactorily describe the δ 30 Si composition of biogenic silica exported out of the mixed layer, within the limit of the current analytical precision on the δ 30 Si. The failures of previous models (Rayleigh and steady state) become apparent especially at the end of the productive period in the mixed layer, when biogenic silica production and export are low. This results from (1) a higher biogenic silica dissolution:production ratio imposing a lower net fractionation factor and (2) a higher Si-supply:Si-uptake ratio supplying light Si-isotopes into the mixed layer. The latter effect is especially expressed when the summer mixed layer becomes strongly Si-depleted, together with a large vertical silicic acid gradient, e.g. in the Polar Front Zone and at the Polar Front.

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Section: F Fripiat Et Al: Si-isotopic Composition In the Southern Osupporting

confidence: 65%

Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography

et al. 2012

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“…Using a calibrated relationship between spicule δ 30 Si and sponge Si isotope fractionation (Wille et al, 2010;Hendry and Robinson, 2012), they show that from 60 to 30 Ma DSi concentrations in the North Atlantic were consistently low, meaning that the transition to a low DSi ocean had to have begun prior to the Early Cenozoic ( Figure 4A). Subsequent cores from the Pacific Ocean, showed ( Figure 4B) that deep water DSi concentrations were also lower prior to 37 Ma .…”

Section: Transition To An Ocean Dominated By Biosilicificationmentioning

confidence: 99%

Biosilicification Drives a Decline of Dissolved Si in the Oceans through Geologic Time

et al. 2017

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Biosilicification has driven variation in the global Si cycle over geologic time. The evolution of different eukaryotic lineages that convert dissolved Si (DSi) into mineralized structures (higher plants, siliceous sponges, radiolarians, and diatoms) has driven a secular decrease in DSi in the global ocean leading to the low DSi concentrations seen today. Recent studies, however, have questioned the timing previously proposed for the DSi decreases and the concentration changes through deep time, which would have major implications for the cycling of carbon and other key nutrients in the ocean. Here, we combine relevant genomic data with geological data and present new hypotheses regarding the impact of the evolution of biosilicifying organisms on the DSi inventory of the oceans throughout deep time. Although there is no fossil evidence for true silica biomineralization until the late Precambrian, the timing of the evolution of silica transporter genes suggests that bacterial silicon-related metabolism has been present in the oceans since the Archean with eukaryotic silicon metabolism already occurring in the Neoproterozoic. We hypothesize that biological processes have influenced oceanic DSi concentrations since the beginning of oxygenic photosynthesis.

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“…A compilation of modern sponge spicules, and core top spicules, reveals that there is a statistically significant nonlinear relationship between sponge δ 30 Si, or the difference between seawater and spicule δ 30 Si (denoted by 30 Si), and ambient DSi concentrations during sponge growth (Hendry et al, 2010;Wille et al, 2010;. This empirical calibration means that there is a great potential for spicule δ 30 Si in sediment cores to be used as a proxy for bottom water DSi concentrations in the past, providing key information about the supply of waters that feed diatom productivity (Hendry et al, 2010;.…”

Section: Siliceous Spongesmentioning

confidence: 99%

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

et al. 2018

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Silicon isotopic fractionation in marine sponges: A new model for understanding silicon isotopic variations in sponges

Cited by 87 publications

References 32 publications

Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography

Processes controlling the Si-isotopic composition in the Southern Ocean and application for paleoceanography

Biosilicification Drives a Decline of Dissolved Si in the Oceans through Geologic Time

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

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