Water on Earth E-Book

Christophe Lécuyer

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 297

Veröffentlichungsjahr: 2013

Beschreibung

The presence of water on Earth is discussed in this book using various theories about its origin as a basis. These theories include a massive degassing of the primitive parent bodies that built our planet as well as a late addition from comets that collided with the Earth’s surface. The extraordinary physico-chemical properties of the water molecules, combined with its abundance and distribution over the Earth’s surface, have contributed to regulating the global climate and favoring species’ evolution for more than 4 billion years. The early emergence of life in the deep ocean and its further diversification were closely linked to the global water cycle whose dynamics result from the energy balance between solar radiation and the internal heat flux of the Earth.

Chapter 1 of this book deals with the extraordinary physico-chemical properties of the water molecule while Chapter 2 provides insight on theories regarding the origin of water on Earth. In the third chapter, the author focuses on the chemical composition of the main water reservoirs of our planet. Chapters 4 and 5 discuss water’s relationship with plate tectonics and life, respectively. The sixth and final chapter uses stable isotope tracking to look into the water cycle and past climates.

Leseprobe

Table of Contents

Preface

Acknowledgments

Chapter 1 Water: A Molecule Endowed with Extraordinary Physicochemical Properties

1.1. Molecular geometry and electrical properties

1.2. Phase diagram

1.3. Stable isotopes of hydrogen and oxygen

1.4. Thermodynamic properties

1.5. Optical properties

1.6. Underwater propagation of sound

1.7. Synthesis and electrolysis

1.8. Bibliography

Chapter 2 Theories about the Origin of Water on Earth

2.1. The blue planet of the solar system

2.2. Comets

2.3. Carbonaceous chondrites and icy asteroids

2.4. Small magnitude evolution of the D/H ratio of the oceans

2.5. Chemical composition of the primordial Earth’s oceans

2.6. Bibliography

Chapter 3 The Main Water Reservoirs on Earth and their Chemical Composition

3.1. Masses of water reservoirs

3.2. The superficial hydrological cycle, water fluxes and residence times

3.3. Chemical composition of rivers

3.4. Ocean chemical composition

3.5. Chemical composition of rainfall

3.6. Why are oceans salty?

3.7. Hypersaline waters

3.8. Geothermal waters and the “petrifying springs”

3.9. Bibliography

Chapter 4 Water and Plate Tectonics

4.1. A brief introduction to the theory of “plate tectonics”

4.2. Catastrophic events related to global tectonics: tsunamis

4.3. Oceanic hydrothermal activity

4.4. Water in the Earth’s mantle

4.5. Subduction and volcanic activity

4.6. Continental growth and recycling

4.7. Bibliography

Chapter 5 Water and Life

5.1. Cell functioning and metabolic activity

5.2. Adaptation and readaptation of tetrapods to the aquatic environment

5.3. Biodiversity in the aquatic environment

5.4. Bibliography

Chapter 6 Stable Isotope Tracking: Water Cycles and Climates of the Past

6.1. Principles of stable isotope fractionation between substances

6.2. The surface water cycle

6.3. The stable isotope memory of fossil biominerals

6.4. Aqueous inclusions trapped in minerals

6.5. Bibliography

Index

First published 2014 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd 27-37 St George’s Road London SW19 4EU UKwww.iste.co.uk

John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USAwww.wiley.com

©ISTE Ltd 2014

The rights of Christophe Lécuyer to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number:2013948546

British Library Cataloguing-in-Publication Data

Preface

The presence of water on the Earth is discussed on the basis of various theories about its origin, such as a massive degassing of the primitive parent bodies that built our planet as well as a late addition from comets that collided with its surface. The extraordinary physico-chemical properties of the water molecule combined with its abundance and repartition at the Earth’s surface have contributed to regulate the global climate and favor the evolution of species for more than 4 billion years. The early emergence of life in the deep ocean and its further diversification were closely linked to the global water cycle whose dynamics resulted from the energy balance between the solar radiation and the internal heat flux of the Earth.

Christophe LÉCUYER

October 2013

Acknowledgments

I would like to acknowledge my mentors and colleagues without whom my scientific career would certainly have been different, and surely would not have lived up to my childhood dreams: F. Albarède, J.-M. Caron, S. Fourcade, P. Gillet, G. Gruau, H. Lapierre, A. Mariotti, A. Nicolas, J.R. O’Neil, J. Schott and S.M.F. Sheppard. I would like to thank my colleagues and friends who kindly agreed to read certain chapters of this book: E. Buffetaut, N. Coltice, J.-P. Flandrois, M. Lemaire, A. Mariotti and F. Robert. I am grateful to A. Royer for all the drawings he provided. I would also like to thank the two magic “mass spec” guys F. Fourel and F. Martineau.

I would like to thank those young people, my former students, from whom I have learned much, listening to them about the ways of teaching and researching: R. Amiot, D. Angst, A.-C. Auclair, A. Bernard, A. Barral–Cuesta, M. Fabre, C. Fleutelot, M.-A. Héran, C. Langlois, G. Manach’, N. Navarro, S. Picard, E. Pucéat, T. Rigaudier, A. Royer, L. Simon, A. Touzeau and A. Zazzo.

These last years, I have been happy simply to either collaborate or discuss with these researchers: P. Allemand, R. Amiot, F. Atrops, V. Balter, J. Blichert-Toft, A.-M. Bodergat, J.-P. Brugal, E. Buffetaut, M. Chaussidon, V. Courtillot, V. Daux, J.-P. Flandrois, C. France-Lanord, J. Gaillardet, D. Grosheny, F. Guyot, S. Legendre, M. Lemaire, A.-M. Lézine, B. Marty, J.-M. Mazin, O. Otero, B. Reynard, Y. Ricard, F. Robert, D.-D. Rousseau and J. Trotter. Special thanks go to P. Fortin and N. Pierre. Finally, I thank my parents, as well as M. Lécuyer and T. Junior for their patience.

Chapter 1

Water: A Molecule Endowed with Extraordinary Physicochemical Properties

1.1. Molecular geometry and electrical properties

A water molecule consists of an oxygen atom bonded to two hydrogen atoms. In water, each hydrogen atom is bound to the oxygen by a pair of electrons. However, only two of the six outer-shell electrons of oxygen are used to form covalent bonds, the remaining four being organized into two non-bonding pairs (Figure 1.1). The four electron pairs surrounding the oxygen tend to arrange themselves as far from each other as possible in order to minimize repulsions between these clouds of negative charge. However, the two non-bonding pairs exert a strong repulsion against the two covalent bonding pairs, which results in a deformed tetrahedral geometry with a angle of 105° instead of the theoretical angle of 109°. As a result, the H2O molecule is electrically neutral even though the electrical charges are not distributed uniformly. Indeed, a negative charge is associated with the oxygen atom while the hydrogen atom carries a positive charge (Figure 1.2). This electronic configuration defines the polar structure of water molecules, which consequently have a mutual attraction and tend to stick together.

This process is called “hydrogen bonding” and explains why water is a liquid instead of a gas under standard conditions (close to the Earth’s surface pressure and temperature conditions). In comparison to a covalent bond, the hydrogen bond is so weak that the timescale of its life expectancy is in the order of the picosecond (10−12 s), therefore explaining the low molecular viscosity of water ( at 20°C) compared to many other liquids at a given temperature. This low molecular viscosity plays a key role in the regulation of osmotic pressure in body fluids.

Figure 1.1.Bonding and non-bonding electronic pairs of the outer shell in the water molecule

Figure 1.2.The dipolar water molecules forming hydrogen bonding

In ordinary ice, each water molecule forms four hydrogen bonds to the nearest oxygen neighbors with distances of 2.76 (Figure 1.3). The triple O angles are 109° according to a lattice structure with a tetrahedral coordination. This basic unit is repeated in three dimensions to build the ordinary ice crystals with hexagonal symmetry that can be observed in snowflakes.

Figure 1.3.A tetrahedral coordination and hexagonal symmetry of the crystal lattice of water ice

When ice starts melting and forms a thin layer of liquid water (Figure 1.4), the crystal lattice breaks down as thermal motions distort and finally break hydrogen bonds.