Data/hora: 02/06/2024 16:16:35

Provedor de dados: 	5	
País: 	France	
Título: 	Relevance of silicon isotopes to Si-nutrient utilization and Si-source assessment in Antarctic	
Autores: 	Cardinal, D; Alleman, Ly; Dehairs, F; Savoye, N; Trull, Tw; Andre, L.	
Data: 	2005-04	
Ano: 	2005	
Palavras-chave: 	Δ29Si; Δ30Si; Diatoms; Spring Southern Ocean; Fractionation factor.	
Resumo: 	We analyzed delta(29) Si of dissolved silicate for eight water column profiles across the Southern Ocean ( south of Australia in spring 2001) from the Seasonal Ice Zone (SIZ) north to the Subantarctic Zone (SAZ), including the first isotopic compositions measured for Si-depleted seawaters. All profiles display mixed layer enrichments in heavy Si isotopes relative to deep water in accordance with preferential uptake of the light isotope by diatoms. As silicate levels decrease from the SIZ northward across the Polar Front Zone (PFZ) to the SAZ, surface and mesopelagic delta(29) Si signatures generally become progressively heavier, but the most Si-depleted SAZ waters do not exhibit delta(29) Si values heavier than in the PFZ. This intricacy appears to derive from variations in the vertical and horizontal supply of silicate to surface waters, and by applying a steady state open system model, we estimate a fractionation factor, (29)epsilon, between diatoms and seawater of -0.45 +/- 0.17%, independently of zones and phytoplankton community. Though encouraging, these results are related to latitudinal changes in mesopelagic delta(29) Si values, complexity in surface silicate - delta(29) Si correlations, and differences from previous studies, which underline the need for caution in the use of silicon isotopes in paleoceanographic studies until systematic efforts have been undertaken to better understand modern variations.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	https://archimer.ifremer.fr/doc/00233/34424/32838.pdf

DOI:10.1029/2004GB002364

https://archimer.ifremer.fr/doc/00233/34424/	
Editor: 	Amer Geophysical Union	
Formato: 	application/pdf	
Fonte: 	Global Biogeochemical Cycles (0886-6236) (Amer Geophysical Union), 2005-04 , Vol. 19 , N. 2/GB2007 , P. 1-13	
Fonte: 	Copyright 2005 by the American Geophysical Union.

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