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Mg isotopes in biocarbonates New insights into vital effects associated to echinoderm and bivalve calcification F. Planchon, J. Hermans, C. Borremans,

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Presentation on theme: "Mg isotopes in biocarbonates New insights into vital effects associated to echinoderm and bivalve calcification F. Planchon, J. Hermans, C. Borremans,"— Presentation transcript:

1 Mg isotopes in biocarbonates New insights into vital effects associated to echinoderm and bivalve calcification F. Planchon, J. Hermans, C. Borremans, Ph. Dubois, C. Poulain, Y.-M. Paulet and L. André

2 δ 26 Mg in Biocarbonates: Introduction Mg/Ca tool Mg Fluid Ca Carbonate + Mg Carbonate + Ca Fluid K d Mg/Ca ≈ D Mg = f(T)

3 δ 26 Mg in Biocarbonates: Introduction Mg/Ca tool T Proxy BioCaCO 3 Mg Fluid Ca Carbonate + Mg Carbonate + Ca Fluid K d Mg/Ca ≈ D Mg = f(T) From Gaetani (2006), Lear (2002), Elderfield and Ganssen (2000), Mashiota (1999) Vital Effects Metabolism Age Salinity, etc.

4 δ 26 Mg in Biocarbonates: Introduction Mg/Ca tool T Proxy BioCaCO 3 Mg Fluid Ca Carbonate + Mg Carbonate + Ca Fluid Vital Effects 26 Mg 25 Mg 24 Mg δ 26 Mg Fluid δ 26 Mg Carbonate Δ Carbonate-Fluid δ 26 Mg Biocarbonate Δ Inorg-org δ 26 Mg δ 25 Mg Galy (2001) Metabolism Age Salinity, etc.

5 δ 26 Mg in Biocarbonates: Methodology Sample Purification  Cationic exhange chromatography (Chang, 2003)  Full Mg recovery  Clean techniques

6 δ 26 Mg in Biocarbonates: Methodology Sample Purification  Cationic exhange chromatography (Chang, 2003)  Full Mg recovery  Clean techniques Analysis  MC-ICP-MS (Nu instrument)  Desolvation (Aridus II)  High sensitivity ng/g  Standard bracketing Relative to DSM3

7 δ 26 Mg in Biocarbonates : Overview Chang (2003, 2004), Wombacher (2006) and Tipper (2006) Mass-dependent fractionation line

8 δ 26 Mg in Biocarbonates: Samples Echinoderms  Starfish  Sea Urchin Morphology Culture Exp (T, S) Bivalves  Clams (Ruditapes Ph.)  Salinity Gradient (2 sites) Auray River  Shell  Internal fluids  Soft tissus

9 Echinoderms Sea urchin and starfish

10 δ 26 Mg in Biocarbonates : Echinoderms (Starfish and Sea urchin) Chang (2003, 2004), Wombacher (2006) and Tipper (2006) Planktonic Forams Coccoliths Inorganic Calcite (theo) Δ water-mineral 26 Mg: -2.7±0.2‰ Biological effects 0.5 < Δ Inorg-org 26 Mg < 1.5 ‰ Galy (2002)

11 δ 26 Mg in Biocarbonates : Sea urchin  Morphological variability  Interambulacral plates record Endoskeleton characteristics

12 δ 26 Mg in Biocarbonates : Sea urchin Culture experiment (T & S control)  δ26 : f(T)  δ26 : f([Mg]) Proxy implication Low metabolism impact

13 δ 26 Mg in Biocarbonates : Sea urchin Calcification δ 26 Mg seawater -0.8 ‰  Intra-cellular Calcification δ 26 Mg Biocarbonate -2.2 to -2.7 ‰ δ 26 Mg intracell Metabolism ACC  Equilibrium-like fractionation  Biological mediation  Cell membrane transport  Amorphous phase regulation

14 δ 26 Mg in Biocarbonates : Starfish  Low interspecies variability  Moderate biological control

15 Bivalves Aragonitic Clams (Ruditapes philippinarum)

16 δ 26 Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum) Le Bono Locquemariaquer Poulain (2006)

17 δ 26 Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)

18 Conclusions : δ26 Mg– δ25Mg in biocarbonates New tool to explore biocalcification processes  Identification of mass-dependent fractionation  Potential reservoirs involved Paleoceanographic Proxy  Direct relationship with T and S  Constrain biocalcification model Theoretical approach is needed  System evolution (closed-open)  Equilibrium – disequilibrium  Complex mixing model (metabolism, energy consumption, etc.)

19 Thanks for your attention

20 δ 26 Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum) Adapted from Carré (2006)


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