00452 - Geochemistry

Course Unit Page

SDGs

This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

Good health and well-being Clean water and sanitation Oceans Life on land

Academic Year 2019/2020

Learning outcomes

 The main targets of this course are to provide the following abilities:

1)  to gain the basic knowledge about geochemistry and its applications in different geological and environmental fields;

2) to gain the basic knowledge about thebehaviour of the elements in the superficial environment;

3) to gain  analytical laboratory experiences;

4) to gain the ability to analyse the chemical composition of natural waters in order to assess origin, interactions with the hosting rocks, mixing, dilution etc.

Course contents

Recalls of some concepts of chemistry (for example: atomic properties, types of bonds, states of valence ....) and of mineralogy (classification and characteristics of silicates, types of minerals) useful for the development of the course. Rules of Goldschmidt and substitution between elements in the minerals. Consideration on the average composition of common rock types.

Origin of the elements and their abundances. Meteorites: Chemical-mineralogical composition, age, classification

Origin and evolution of the solar system an of the Earthlike planets. Origin of the Earth: condensation vs homogeneous/heterogeneous accretion. Contribution of geochemistry. Internal structure of the Earth. Core-Mantle segregation. Primary geochemical differentiation.  Geochemical classification of the elements: lithophile, siderophile and chalcophile. Genesis and evolution of the continental crust.

Elements of high temperature geochemistry. Overview of genesis and evolution of magmas. Major, minor and trace elements. Goldschmidt replacement rules. Partition coefficient and mass partition coefficient.

Thermodynamics and phase diagrams. Elementary recalls of thermodynamics, Enthalpy (H), Entropy (S) and Gibbs free energy (G). Relation between Equilibrium constant and free energy. Relationship between free energy and equilibrium constant. Phase diagrams with complete miscibility, with eutectic and with peritectic.

The critical zone: processes of mechanical disintegration and chemical alteration of minerals and rocks. Dissolution, oxidation, hydration and hydrolysis. Congruent and incongruent reactions. The engines of alteration reactions. the importance of CO2 in alteration reactions, CO2 control factors in the environment. The characteristics of clay minerals, classification, reactivity, environmental importance. Isoelectric point, definition and effects.

Hydrosphere - Main characteristics of fresh water and marine waters. origin of the dissolved components. processes that condition the chemistry of water (type of rock, degradation of organic matter, adsorption reactions, classification of water on the basis of chemical and physical characteristics, ionic strength and activity) Diagrams Eh/pH and chemical speciation in aqueous solution: definition and applications.
More details on the processes of degradation of organic matter (aerobic and anaerobic decomposition). effects on the characteristics of the environment and on the chemistry of the solutions.

Isotope geochemistry - Geochemistry of unstable isotopes. The radioactive decay. Radiometric dating, principles and applications. Geochemistry of stable isotopes. Principles of isotope fractionation. Formulations of the isotopic compositions and related applications.

Outline of environmental geochemistry: characteristics and examples of geochemical studies applied to soils, to alluvial and marine sediments, to waters. geochemical cartography and data processing.

Readings/Bibliography

Konrad B. Krauskopf - Introduction to Geochemistry - McGraw-Hill Ed.

Gunter Faure - Principles and Applications of Geochemistry - Prentice Hall Ed.

Brian Mason - Principles of Geochemistry - John Wiley and Sons Ed.

C.A.J. Appelo and D. Postma - Geochemistry, groundwater and pollution - A.A. Balkema Publishers Ed.

James I. Drever - The Geochemistry of Natural Waters - Prentice Hall Ed.

Peter C. Ryan - Environmental and low temperature geochemistry -Wiley Blackwell- 2014

Teaching methods

Lectures.

Laboratory exercises, based on real geochemical data elaboration

Assessment methods

oral exam on the topics covered during the course, with attention to the development of aspects related to several macro themes developed during the course. Candidates are expected to be able to write the chemical formulas of the main minerals and to write and balance chemical reactions.

Office hours

See the website of Enrico Dinelli