An Introduction to Environmental Chemistry SECOND EDITION J.E. Andrews, P. Brimblecombe, T.D. Jickells, P.S. Liss and B. Reid School of Environmental Sciences University of East Anglia United Kingdom An Introduction to Environmental Chemistry An Introduction to Environmental Chemistry SECOND EDITION J.E. Andrews, P. Brimblecombe, T.D. Jickells, P.S. Liss and B. Reid School of Environmental Sciences University of East Anglia United Kingdom © 2004 by Blackwell Science Ltd a Blackwell Publishing company 350 Main Street, Malden, MA 02148-5020, USA 108 Cowley Road, Oxford OX4 1JF, UK 550 Swanston Street, Carlton, Victoria 3053, Australia The right of J.E. Andrews, P. Brimblecombe, T.D. Jickells, P.S. Liss and B. Reid to be identified as the Authors of this Work has been asserted in accordance with the UK Copyright, Designs, and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs, and Patents Act 1988, without the prior permission of the publisher. First published 1996 by Blackwell Science Ltd Second edition 2004 Library of Congress Cataloging-in-Publication Data An introduction to environmental chemistry / J.E. Andrews . [et al.]. – 2nd ed. p. cm. Includes bibliographical references and index. ISBN 0-632-05905-2 (pbk.: alk. paper) 1. Environmental geochemistry. I. Andrews, J.E. ( Julian E.) QE516.4.I57 2004 551.9 – dc21 2003002757 A catalogue record for this title is available from the British Library. 1 Set in 9–2 /12 pt Janson by SNP Best-set Typesetter Ltd., Hong Kong Printed and bound in the United Kingdom by TJ International, Bodmin, Cornwall For further information on Blackwell Publishing, visit our website: http://www.blackwellpublishing.com Contents List of boxes ix Preface to the second edition xi Preface to the first edition xii Acknowledgements xiv Symbols and abbreviations xviii 1 Introduction 1 1.1 What is environmental chemistry? 1 1.2 In the beginning 2 1.3 Origin and evolution of the Earth 2 1.3.1 Formation of the crust and atmosphere 4 1.3.2 The hydrosphere 5 1.3.3 The origin of life and evolution of the atmosphere 8 1.4 Human effects on biogeochemical cycles? 9 1.5 The structure of this book 11 1.6 Internet keywords 12 1.7 Further reading 13 1.8 Internet search keywords 13 2 Environmental chemist’s toolbox 14 2.1 About this chapter 14 2.2 Order in the elements? 14 2.3 Bonding 19 2.3.1 Covalent bonds 19 2.3.2 Ionic bonding, ions and ionic solids 20 vi Contents 2.4 Using chemical equations 21 2.5 Describing amounts of substances: the mole 22 2.6 Concentration and activity 22 2.7 Organic molecules – structure and chemistry 23 2.7.1 Functional groups 25 2.7.2 Representing organic matter in simple equations 26 2.8 Radioactivity of elements 27 2.9 Finding more chemical tools in this book 29 2.10 Further reading 30 2.11 Internet search keywords 30 3 The atmosphere 31 3.1 Introduction 31 3.2 Composition of the atmosphere 32 3.3 Steady state or equilibrium? 35 3.4 Natural sources 38 3.4.1 Geochemical sources 39 3.4.2 Biological sources 41 3.5 Reactivity of trace substances in the atmosphere 44 3.6 The urban atmosphere 45 3.6.1 London smog – primary pollution 46 3.6.2 Los Angeles smog – secondary pollution 48 3.6.3 21st-century particulate pollution 52 3.7 Air pollution and health 53 3.8 Effects of air pollution 55 3.9 Removal processes 56 3.10 Chemistry of the stratosphere 58 3.10.1 Stratospheric ozone formation and destruction 59 3.10.2 Ozone destruction by halogenated species 61 3.10.3 Saving the ozone layer 63 3.11 Further reading 64 3.12 Internet search keywords 65 4 The chemistry of continental solids 66 4.1 The terrestrial environment, crust and material cycling 66 4.2 The structure of silicate minerals 70 4.2.1 Coordination of ions and the radius ratio rule 70 4.2.2 The construction of silicate minerals 73 4.2.3 Structural organization in silicate minerals 73 4.3 Weathering processes 76 4.4 Mechanisms of chemical weathering 77 4.4.1 Dissolution 77 4.4.2 Oxidation 77 4.4.3 Acid hydrolysis 83 4.4.4 Weathering of complex silicate minerals 84 4.5 Clay minerals 87 Contents vii 4.5.1 One to one clay mineral structure 88 4.5.2 Two to one clay mineral structure 88 4.6 Formation of soils 93 4.6.1 Parent (bedrock) material (p) 94 4.6.2 Climate (cl) 94 4.6.3 Relief (r) 97 4.6.4 Vegetation (v) 99 4.6.5 Influence of organisms (o) 99 4.7 Wider controls on soil and clay mineral formation 104 4.8 Ion exchange and soil pH 111 4.9 Soil structure and classification 112 4.9.1 Soils with argillic horizons 113 4.9.2 Spodosols (podzols) 113 4.9.3 Soils with gley horizons 117 4.10 Contaminated land 119 4.10.1 Organic contaminants in soils 119 4.10.2 Degradation of organic contaminants in soils 125 4.10.3 Remediation of contaminated land 129 4.10.4 Phytoremediation 137 4.11 Further reading 139 4.12 Internet search keywords 140 5 The chemistry of continental waters 141 5.1 Introduction 141 5.2 Element chemistry 142 5.3 Water chemistry and weathering regimes 145 5.3.1 Alkalinity, dissolved inorganic carbon and pH buffering 151 5.4 Aluminium solubility and acidity 155 5.4.1 Acidification from atmospheric inputs 156 5.4.2 Acid mine drainage 156 5.4.3 Recognizing acidification from sulphate data – ternary diagrams 159 5.5 Biological processes 161 5.5.1 Nutrients and eutrophication 163 5.6 Heavy metal contamination 170 5.6.1 Mercury contamination from gold mining 170 5.7 Contamination of groundwater 174 5.7.1 Anthropogenic contamination of groundwater 176 5.7.2 Natural arsenic contamination of groundwater 178 5.8 Further reading 180 5.9 Internet search keywords 180 6 The oceans 181 6.1 Introduction 181 6.2 Estuarine processes 182 6.2.1 Aggregation of colloidal material in estuaries 183 6.2.2 Mixing processes in estuaries 184 viii Contents 6.2.3 Halmyrolysis and ion exchange in estuaries 186 6.2.4 Microbiological activity in estuaries 187 6.3 Major ion chemistry of seawater 189 6.4 Chemical cycling of major ions 191 6.4.1 Sea-to-air fluxes 194 6.4.2 Evaporites 194 6.4.3 Cation exchange 195 6.4.4 Calcium carbonate formation 196 6.4.5 Opaline silica 205 6.4.6 Sulphides 206 6.4.7 Hydrothermal processes 208 6.4.8 The potassium problem: balancing the seawater major ion budget 214 6.5 Minor chemical components in seawater 216 6.5.1 Dissolved gases 216 6.5.2 Dissolved ions 216 6.5.3 Conservative behaviour 218 6.5.4 Nutrient-like behaviour 218 6.5.5 Scavenged behaviour 223 6.6 The role of iron as a nutrient in the oceans 227 6.7 Ocean circulation and its effects on trace element distribution 229 6.8 Anthropogenic effects on ocean chemistry 233 6.8.1 Human effects on regional seas 1: the Baltic 233 6.8.2 Human effects on regional seas 2: the Gulf of Mexico 235 6.8.3 Human effects on total ocean minor element budgets? 235 6.9 Further reading 237 6.10 Internet search keywords 238 7 Global change 239 7.1 Why study global-scale environmental chemistry? 239 7.2 The carbon cycle 240 7.2.1 The atmospheric record 240 7.2.2 Natural and anthropogenic sources and sinks 242 7.2.3 The global budget of natural and anthropogenic carbon dioxide 251 7.2.4 The effects of elevated carbon dioxide levels on global temperature and other properties 257 7.3 The sulphur cycle 262 7.3.1 The global sulphur cycle and anthropogenic effects 262 7.3.2 The sulphur cycle and atmospheric acidity 265 7.3.3 The sulphur cycle and climate 271 7.4 Persistent organic pollutants 274 7.4.1 Persistent organic pollutant mobility in the atmosphere 274 7.4.2 Global persistent organic pollutant equilibrium 278 7.5 Further reading 281 7.6 Internet search keywords 281 Index 283 Colour plates fall between pp. 138 and 139. Boxes 1.1 Elements, atoms and isotopes 3 3.1 Partial pressure 34 3.2 Chemical equilibrium 37 3.3 Acids and bases 40 3.4 Gas solubility 43 3.5 The pH scale 49 3.6 Reactions in photochemical smog 51 3.7 Acidification of rain droplets 58 3.8 Removal of sulphur dioxide from an air parcel 59 4.1 Properties of water and hydrogen bonds 69 4.2 Electronegativity 74 4.3 Oxidation and reduction (redox) 78 4.4 Metastability, reaction kinetics, activation energy and catalysts 80 4.5 Dissociation 81 4.6 Isomorphous substitution 91 4.7 Van der Waals’ forces 93 4.8 Chemical energy 98 4.9 Mineral reaction kinetics and solution saturation 99 4.10 Biopolymers 100 4.11 Base cations 106 4.12 Solubility product, mineral solubility and saturation index 107 4.13 Radon gas: a natural environmental hazard 120 4.14 Physical and chemical properties that dictate the fate of organic contaminants 122 x Boxes 4.15 Use of clay catalysts in clean up of environmental contamination 126 4.16 Mechanisms of microbial degradation and transformation of organic contaminants 128 5.1 Ionic strength 150 5.2 Measuring alkalinity 150 5.3 Worked examples of pH buffering 154 5.4 Eh-pH diagrams 164 5.5 Essential and non-essential elements 171 6.1 Salinity 185 6.2 Salinity and major ion chemistry of seawater on geological timescales 190 6.3 Residence times of major ions in seawater 192 6.4 Ion interactions, ion pairing, ligands and chelation 198 6.5 Abiological precipitation of calcium carbonate 202 6.6 Oceanic primary productivity 220 7.1 Simple box model for ocean carbon dioxide uptake 248 7.2 The delta notation for expressing stable isotope ratio values 269 7.3 Chiral compounds 279 Preface to the Second Edition In revision of this book we have tried to respond to constructive criticism from reviewers and students who have used the book and at the same time have pruned and grafted various sections where our own experience as teachers has prompted change.