- Moutin, T. Wagener (M1S1)
Objective
Introduction to chemical oceanography. The aim of this course (balanced between lectures, tutorials and practical work) is to study the chemical composition of major elements in the oceans and the main processes explaining their distribution.
► Theoretical courses : 24 h
- Descriptive chemical oceanography. Review of the main physical characteristics of the ocean, essential for explaining the composition and distribution of chemical elements in seawater. Use of chemical tracers in oceanography.
2. Major components of seawater (Seawater, a complex medium, main constituents, salinity). Examples of variations in the relative composition of major elements. Origin and evolution of the chemical composition of seawater. 3. Distribution of dissolved gases in the ocean (inert and reactive gases). Dissolution and solubility. Gas exchange at the air/sea interface. Processes affecting conservative gases in seawater. Special case of biologically active gases. Comparative study of the distribution of a conservative gas and a reactive trace gas.
4. The carbonate system (seawater pH, alkalinity, thermodynamic equilibrium of the system, measurable variables and quantities).
5. Distribution of nutrients in the ocean and relationship to general circulation. Measurable forms and fractions of nitrogen, phosphate and silica in seawater. Use of nutrients as tracers of water masses.
► Tutorials : 16 h
Notion of practical and absolute salinity (use of international oceanographic tables, equation of state for seawater, TEOS10), Dissolved oxygen (assays, expression of results, solubility, notion of AOU, study of profiles), Macronutrients (measurable fractions of nitrogen and phosphate, measurement methods, concentration and gradient calculations, notion of flux), Carbonate equilibrium (construction of log-log diagrams).
► Practical work 20 h (booklet at bottom of page)
Determination of the main chemical components of seawater: dissolved oxygen, salinity, density, nutrient salts, chlorophyll a (biomass indicator), pH, alkalinity, calcium, dissolved and particulate organic nitrogen (biomass indicator).
References : Millero, F.J. 2006. Chemical Oceanography. 3rd ed. CRC press. ISBN 0-8493-2280-4. Copin-Montégut G. 1996. Chimie de l’Eau de Mer, Institut Océanographique de Paris, 319 pp. ISBN 2923581142 Sarmiento J.L. & N. Gruber. 2006. Ocean Biogeochemical Dynamics. Princeton University Press/ Princeton and Oxford. ISBN-13: 978-0-691-01707-5
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Practical work room at Endoume marine station