Atomic emission spectroscopy (AES)

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Table of contents

Chapter 1 Introduction
1.1a. General introduction (English version)
1.1b. Introduction génerale (Version française)
1.2. Aqueous chemistry
1.2.1. Chemical equilibrium
1.2.1. Speciation and complexation in aqueous solution
1.3. Principles of stable isotope fractionation
1.3.1. Stable isotopes
1.3.2. Stable isotope fractionation
1.3.3. Stable isotope fractionation processes
1.3.4. Influence of aqueous speciation on isotope fractionation
1.4. Silicon and magnesium isotopic systems
1.4.1. Silicon isotopes
1.4.2. Magnesium isotopes
Chapter 2 Materials and Methods
2.1. Theoretical Background
2.1.1. Three-isotope method
2.1.2. Kinetics of isotopic exchange reactions
2.2. Materials
2.2.1. Amorphous Silica (SiO2,am)
2.2.2. Brucite synthesis
2.2.3. Aqueous Solutions
2.2.3.1. Inorganic solutions
2.2.3.2. Aqueous organic solutions
2.2.4. Isotopic spike solutions
2.3. Experimental design
2.3.1. Chemical equilibration of reactive fluids
2.3.2. Isotope exchange experiments
2.4. Analytical methods
2.4.1. Characterization of solid phases
2.4.1.1. Scanning electron microscopy (SEM)
2.4.1.2. Transmission electron microscopy (TEM)
2.4.1.3. Surface area
2.4.1.4. Thermogravimetric analysis
2.4.1.5. X-ray Powder Diffraction (P-XRD)
2.4.2. Characterization of aqueous solutions
2.4.2.1. pH measurements
2.4.2.2. Atomic absorption spectroscopy (AAS)
2.4.2.3. Atomic emission spectroscopy (AES)
2.4.2.4. Colorimetry
2.4.2.5. Organic carbon measurements
2.4.2.6. Quadrupole – ICP-MS
2.3.2.7. High Resolution – ICP-MS (HR-ICP-MS)
2.4.3. Isotopic Analysis
2.4.3.1. Silicon sample preparation and ion-exchange chromatography
2.4.3.2. Magnesium sample preparation and ion chromatography
2.4.3.3. Principles of the Neptune® Multi Collector ICP-MS (MC-ICP-MS)
2.4.3.4. Silicon isotope measurements
2.4.3.5. Magnesium isotope measurements
2.4.3.6. Analytical reproducibility
2.5. Geochemical calculations with PHREEQC
2.5.1. Thermodynamic modelling
2.4.2. Si speciation calculations
2.4.3. Mg speciation calculations
Chapter 3 The experimental determination of equilibrium Si isotope fractionation factors among H4SiO4 o, H3SiO4 – and amorphous silica (SiO2·0.32 H2O) AT 25 and 75 °C using the three isotope method
3.1. Introduction
3.2. Theoretical background
3.2.1. Geochemical calculations of amorphous silica dissolution rates
3.2.2. Si isotope systematics
3.2.3. Three-isotope method
3.2.4. Kinetics of isotopic exchange
3.3. Methods
3.3.1. Experimental approach
3.3.1.1. Starting powder – amorphous silica
3.3.1.2. Initial aqueous solutions
3.3.1.3. Characterization of the aqueous solutions
3.3.1.4. Experiment design: Step 1 Equilibration of reactive fluids
3.3.1.5. Experiment design: Step 2 Isotopic exchange experiments
3.3.2. Si isotope analysis
3.4. Results
3.4.1. Attainment of fluid-amorphous SiO2 equilibrium during the fluid equilibration75
3.4.2. Results of Isotope exchange experiments
3.4.2.1. Observations on the solid phases
3.4.2.2 Chemical and isotopic evolution of the isotope exchange experiments
3.4.3. Silicon isotope fractionation factors
3.4.4. Isotope exchange kinetics
3.5. Discussion
3.5.1. Silicon isotope fractionation between amorphous silica and aqueous solution 83
3.5.2. Isotope fractionation among Si aqueous species
3.5.3. Kinetics of Si isotope exchange
3.5.4. Can Si fractionation be used as a paleo pH and temperature proxy?
3.6. Conclusion
Chapter 4 Extreme silicon isotope fractionation between silicic acid and aqueous organosilicon complexes: Implication for silica biomineralization
4.1. Introduction
4.2. Experimental methods
4.2.1. Starting materials
4.2.2. Experimental design
4.2.2.1. Step 1: Equilibration of the reactive aqueous solutions with amorphous SiO2
4.2.2.2. Step 2: Isotopic exchange experiments
4.2.3. Analytical methods
4.2.3.1. Characterization of aqueous solutions
4.2.3.2. Data reporting and Si isotope analysis
4.3.3. Speciation calculations
4.4. Ab initio calculations
4.5. Results
4.5.1. Attainment of equilibrium between the fluid and amorphous SiO2
4.5.2. Results of isotope exchange experiments
4.5.3. Experimental and theoretical silicon isotope fractionation factors
4.5.4. Isotope exchange kinetics
4.6. Discussion
4.6.1. Silicon isotope fractionation in the presence of catechol
4.6.2. Si isotope exchange kinetics in the presence of catechol
4.6.3. Implications for biomineralization
4.7. Conclusion
Chapter 5 Determination of the equilibrium magnesium isotope fractionation factors between brucite and aqueous Mg inorganic and organic species
5.1. Introduction
5.2. Methods
5.2.1. Starting materials
5.2.1.1. Brucite synthesis
5.2.1.2. Initial reactive aqueous solutions
5.2.1.3. Characterization of sampled experimental fluids
5.2.2. Experimental design
5.2.2.1. Step 1: Equilibration of initial aqueous solutions with Mg(OH)2
5.2.2.2. Step 2: Isotopic exchange experiments
5.2.3. Data reporting and Mg isotope analysis
5.2.4. Geochemical and speciation calculations with PHREEQC
5.3. Results
5.3.1 Equilibrium between fluid and brucite
5.3.2 Results of isotope exchange experiments
5.3.3. Determination of magnesium equilibrium isotope fractionation factors
5.3.4. Isotope exchange kinetics
5.4. Discussion
5.4.1. Magnesium isotope fractionation between brucite and Mg2+
5.4.2. Magnesium isotope fractionation between Mg2+ and aqueous Mg organic and inorganic complexes
5.4.3. Mg isotope exchange kinetics
5.4.3. Implications for natural systems
5.5. Conclusion
Chapter 6 Conclusions and outlook
6.1 General conclusions and outlook (English version)
6.2. Conclusion générale et perspectives (Version française)
Bibliography