Chemistry of the Environment

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Third Edition

Thomas G. Spiro Kathleen L. Purvis-Roberts William M. Stigliani

University Science Books www.uscibooks.com

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Library of Congress Cataloging-in-Publication Data

Spiro, Thomas G., 1935– Chemistry of the environment / Thomas G. Spiro, Kathleen Purvis-Roberts, William M. Stigliani ; foreword by Harry Gray. — 3rd ed. p. cm. ISBN 978-1-891389-70-2 (alk. paper) 1. Environmental chemistry. I. Purvis-Roberts, Kathleen. II. Stigliani, William M. III. Title. TD193.S7 2012 540—dc23 2011013139

Printed in North America 10 9 8 7 6 5 4 3 2 1

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Foreword xvii Preface xix

Part I. Sustainability and Green Chemistry 1 Chapter 1. Sustainability and Chemistry 3 Chapter 2. Green Chemistry 11

Part II. Atmosphere 21 Chapter 3. Air Pollution 23 Chapter 4. Nitrogen Oxides, Ozone, and Gasoline 49 Chapter 5. Stratospheric Ozone Shield 77 Chapter 6. Climate Change 105

Part III. Energy and Materials 155 Chapter 7. Energy Flows and Supplies 157 Chapter 8. Fossil Fuels 169 Chapter 9. Nuclear Energy 205 Chapter 10. Renewable Energy 245 Chapter 11. Energy Utilization 279

Part IV. Hydrosphere and Lithosphere 329 Chapter 12. Water Resources 331 Chapter 13. Water as Solvent: Acids and Bases 349 Chapter 14. Water and Lithosphere 369

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Chapter 15. Oxygen and Life 399 Chapter 16. Water Pollution and Treatment 435

Part V. Biosphere 457 Chapter 17. Nitrogen and Food Production 459 Chapter 18. Pest Control 491 Chapter 19. Toxicity of Chemicals 523

Appendix A: Organic Structures 579 Appendix B: Mathematical Fundamentals 589 Index 595

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Foreword xvii 2.3f Reducing Toxic Metals 17 Preface xix 2.3f.i Yttrium Replaces Lead in Automobile Coatings 17 Part I. Sustainability and Green 2.3f.ii Removing Arsenic and Chemistry 1 Chromium from Pressure-Treated Chapter 1. Sustainability and Chemistry 3 Wood 18 2.3g Atom Economy: Reducing Waste in 1.1 What Is Sustainability? 3 Ibuprofen Manufacture 18 1.2 From Environmentalism to Sustainability 4 2.3h Materials Substitution: Recyclable 1.3 Sustainability Connections among Carpet 18 Environmental Spheres 6 2.3i Environmentally Benign Pesticides 19 1.4 Applying Sustainability 7 Problems 20 Additional Reading 8 Additional Reading 20

Chapter 2. Green Chemistry 11 Part II. Atmosphere 21 2.1 Sustainable Living through Chemistry 11 Chapter 3. Air Pollution 23 2.2 Green Chemistry Principles 12 3.1 Pollutants and Their Effects 23 2.3 Green Chemistry Examples 13 3.2 Carbon Monoxide 24 2.3a Eliminating Chlorofluorocarbons 13 3.3 Sulfur Dioxide 27 2.3b Greener Solvents: Liquid and 3.3a Sulfur Dioxide Emission Controls 28 Supercritical Carbon Dioxide 13 3.4 Toxic Organics 29 2.3b.i Dry Cleaning 14 3.4a Formaldehyde and Acetaldehyde 29 2.3b.ii Cleaning Computer Chips 14 3.4b Benzene 31 2.3c Biomass Plastics 14 3.4c Polycyclic Aromatic Hydrocarbons 32 2.3c.i Polylactic Acid 15 2.3c.ii Cellulose 15 3.5 Particulate Matter 32 2.3c.iii Paint 16 3.6 Nitrogen Oxides and Volatile Organics 36 2.3d Replacing Chlorine 16 3.7 Ozone and Other Oxidants 37 2.3e Biodegradable Chelating Agent 17 3.7a Control of Ozone Precursors 38

3.8 Indoor Air Pollution 42 5.5 Catalytic Destruction of Ozone 90 Problems 45 5.5a Hydroxyl Radical 91 Additional Reading 46 5.5b Chlorine and Bromine 91 5.5c Nitric Oxide 93 Chapter 4. Nitrogen Oxides, Ozone, and 5.5d Summary of Ozone Destruction Gasoline 49 Chemistry 94 4.1 Aerobic Earth 49 5.6 Polar Ozone Destruction 95 4.2 Nitrogen Oxides: Free Energy 50 5.7 Ozone Projections 98 4.2a Free Energy and Equilibrium 50 5.8 The Chlorofluorocarbon Substitutes 98 Worked Problem 4.1: Atmospheric NO Problems 101 Concentration 52 Additional Reading 102 4.2b Free Energy and Temperature 52 Worked Problem 4.2: High-Temperature Chapter 6. Climate Change 105 NO 53 6.1 Overview 105 4.3 Nitrogen Oxides: Kinetics 53 6.2 Energy Flows 105 4.4 Free Radical Chain Reactions 56 6.3 Radiation Balance and the Greenhouse 4.5 Photochemistry 57 Effect 107 4.6 Photochemical Smog 59 Worked Problem 6.1: Human Energy and 4.6a Smog Photochemistry 59 Earth’s Temperature 110 4.6b The C H Bond Strengths and 6.4 Infrared Absorption by Greenhouse Gases: Photochemical Activity 61 Molecular Vibrations 111 4.6c Role of Olefins 64 Worked Problem 6.2: Beer–Lambert Law and

4.6d Atmospheric Reactions of Organic CO2 Saturation 114 Radicals 64 6.5 Water: Positive Feedback, Latent Heat, and 4.6e Additional Smog Contributions 66 Energy Flows 115 4.7 Gasoline and Its Formulations 67 Worked Problem 6.3: Energy in Rain 116 4.7a Knocking and Octane 67 6.6 Greenhouse Computations: Radiative 4.7b Diesels and Cetane 69 Forcing 117 4.7c Lead in Gasoline 70 6.7 Carbon Dioxide and the Carbon Cycle 120 4.7d Reformulated Gasoline 71 6.8 Reservoirs, Flows, and Residence Times 125 Problems 73 Worked Problem 6.4: Carbon Residence Additional Reading 74 Time 125 6.9 Other Greenhouse Gases 126 Chapter 5. Stratospheric Ozone Shield 77 6.10 Albedo, Particles, and Clouds 129 5.1 Overview 77 6.10a Raindrops and Condensation 5.2 Structure of the Atmosphere 79 Nuclei 131 Worked Problem 5.1: How Much Ozone? 82 Worked Problem 6.5: Cloud 5.3 Ultraviolet Radiation Damage 83 Seeding 133 5.3a Transmission of UV Light through 6.10b Aerosol Particles 133 Ozone 85 Worked Problem 6.6: Volcanic 5.4 Reactions that Create and Destroy Cooling 135 Stratospheric Ozone 86 6.10c Sulfur Cycle 136 5.4a Calculating the Ozone Steady State 87 6.10d Black Carbon 138

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6.11 Geoengineering to Raise the Albedo 140 8.6b Disadvantages 195 6.12 Climate Modeling 140 8.6c When Will the Coal Run Out? 197 6.13 Global Warming Impacts 145 8.7 Coal-Derived Fuels 197 6.14 International Agreements 146 8.8 Carbon Capture and Storage 199 Problems 150 8.8a Capture 199 Additional Reading 152 8.8b Geological Storage 200 8.8c Biological Storage 202 Part III. Energy and Materials 155 Problems 203 Chapter 7. Energy Flows and Supplies 157 Additional Reading 204 7.1 Human Energy Consumption 157 Chapter 9. Nuclear Energy 205 7.2 Exponential Growth 160 Worked Problem 7.1: World Energy 9.1 Curve of Binding Energy 205 Consumption 162 9.2 Nuclei, Isotopes, and Radioactivity 206 7.3 Human Energy Sources 163 9.3 Half-Lives and Naturally Occurring Radioisotopes 209 Problems 167 Worked Problem 9.1: Radiocarbon Dating 210 Additional Reading 167 9.4 Decay Chains: The Radon Problem 211 Chapter 8. Fossil Fuels 169 9.5 Radioactivity: Biological Effects of Ionizing 8.1 Closing the Carbon Cycle 169 Radiation 213 Worked Problem 8.1: Will We Run Out of 9.5a Alpha Rays 214 Oxygen? 171 9.5b Beta and Gamma Rays, and Neutrons 215 8.2 Origins of Fossil Fuels 172 9.6 Radiation Exposure 215 8.2a Petroleum and Natural Gas 172 Worked Problem 9.2: Radon Exposure 219 8.2b Coal 174 9.7 Power from Fission 219 8.3 Fuel Energy 174 9.7a Fission Reactors 221 8.3a Hydrogen Combustion and Bond 9.7b Isotope Separation 223 Enthalpies 174 9.7c Breeder Reactor 224 8.3b Comparison of Fuel Energies 177 9.7d Reprocessing 225 Worked Problem 8.2: Methane 9.8 Hazards of Nuclear Power 226 Combustion 179 9.8a Reactor Safety 226 8.4 Petroleum 180 9.8b Weapons Proliferation 229 8.4a Composition and Refining 180 9.8c Nuclear Waste Disposal 231 8.4b Advantages 182 9.8d New Reactor Designs and the Thorium 8.4c Disadvantages 182 Fuel Cycle 233 8.4c.i Oil Spills 182 9.9 The Future of Nuclear Power 236 8.4c.ii Carbon Dioxide Emissions 188 9.10 Fusion 237 8.4d When Will the Oil Run Out? 188 9.10a Fusion Reactions 237 8.5 Gas 190 9.10b Inertial Confinement 239 8.5a Advantages 191 9.10c Magnetic Confinement 240 8.5b Disadvantages 191 9.10d Is Fusion the Energy Source of the 8.5c When Will the Gas Run Out? 192 Future? 242 8.6 Coal 193 Problems 242 8.6a Advantages 194 Additional Reading 243

Chapter 10. Renewable Energy 245 11.4b Hydrogen Storage 297 10.1 Forms of Renewable Energy 245 11.5 The Materials Connection 299 10.2 Solar Heating 247 11.5a Materials Properties: Paper versus 10.3 Solar Electricity 248 Plastics 300 10.3a Solar Thermal Electricity and Solar 11.5b Recycling 302 Chemical Processing 248 11.5b.i Energy of Refining Al versus 10.3b Photovoltaic Electricity 251 Fe 304 10.4 Principles of the Photovoltaic Cell 252 11.5c Concrete 305 11.5d Dematerialization 306 10.5 Photosynthesis and Photoelectrochemistry 256 11.6 Systems Efficiency 307 11.6a Industrial Ecology 309 10.6 Biomass 258 11.6b Transportation 311 10.6a Ethanol from Biomass 260 11.6c Energy Efficiency in Automobiles 314 10.6b Ethanol from Starch or Cellulose? 261 11.6d The “Smart Grid” 316 10.6c Biodiesel 263 11.6e Hydrogen Economy 317 10.6d Methane from Biomass 264 11.7 Connecting Energy Use and Climate Change: 10.7 Hydroelectricity 265 Stabilization Wedges and Cost Curves 319 Worked Problem 10.1 267 10.8 Wind Power 267 Problems 324 10.9 Ocean Energy 270 Additional Reading 326 10.9a Tides 270 Part IV. Hydrosphere and 10.9b Waves 271 10.9c Salt Gradient 271 Lithosphere 329 10.9d Thermal Gradients 271 Chapter 12. Water Resources 331 10.9e Deep Ocean Current 272 12.1 Global Perspective 331 10.10 Geothermal Energy 272 12.2 Irrigation 334 Problems 276 12.3 “Virtual” Water and the Issue of Meat Additional Reading 277 Production 337 12.4 Groundwater 338 Chapter 11. Energy Utilization 279 12.5 United States Water Resources 340 11.1 Efficiency and Heat: The Role of Entropy 279 12.6 The Oceans 341 11.1a Heat Engine Efficiencies 280 12.7 Water as Solvent and as a Biological Worked Problem 11.1: Power Plant Medium 344 Efficiency 282 Problems 345 11.1b Energy to Heat: The Heat Pump 283 Additional Reading 346 11.2 Chemical Energy: Fuel Cells 285 Worked Problem 11.2: Fuel Cell Chapter 13. Water as Solvent: Acids and Efficiency 286 Bases 349 11.2a A PEM Fuel Cell 288 13.1 Unique Properties of Water 349 11.2b Other Fuel Cells 291 13.1a Hydrogen Bonding 349 11.2c Microbial Fuel Cell 292 13.1b Clathrates and Water Miscibility 352 11.3 Space Heating, Cogeneration 293 13.2 Ions, Autoionization, and pH 354 11.4 Electricity Storage 294 13.2a The pH Scale 355 11.4a Batteries 295

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13.3 Weak Acids and Bases: Buffers 357 14.5c Acid Deposition and Watershed 13.3a Weak Acids 357 Buffering 390 13.3b The pH of a Weak Acid 357 14.5d Ecosystem Effects of Acid Rain 393 Worked Problem 13.1: The pH of 14.5e Acid Mine Drainage 394 a Weak Acid 358 14.5f Global Acidification 395 13.3c Weak Bases 358 Problems 396 13.3d The pH of a Weak Base 359 Additional Reading 397 Worked Problem 13.2: The pH of a Weak Base 359 Chapter 15. Oxygen and Life 399 13.3e Conjugate Acids and Bases: 15.1 Redox Reactions and Energy 399 Buffers 359 15.2 Biological Oxygen Demand 400 13.4 Water in the Atmosphere: Acid Rain 361 Worked Problem 15.1: Biological Oxygen 13.5 Polyprotic Acids 362 Demand 401 Worked Problem 13.3: Phosphate 15.3 Oxidation Levels and Water 401 Protonation 365 Worked Problem 15.2: Calculating the Worked Problem 13.4: Ocean Carbonate 366 Oxidation State and Balancing Redox 13.6 Alkalinity 366 Equations 402 Problems 367 15.4 Reduction Potentials 403 Additional Reading 368 15.5 Natural Sequence of Biological Reductions 405 Chapter 14. Water and the Lithosphere 369 15.6 Concentration Dependence of the Potential: 14.1 The Earth as an Acid–Base Reactor 369 pH and Eh 408

14.2 Organic and Inorganic Carbon Cycles 372 Worked Problem 15.3: Eh and Ksp of

14.2a The Carbonate Control 373 Fe(OH)3 409 14.2b Carbonate Sequestration 375 Worked Problem 15.4: Effective Oxygen 14.2c Carbon Dioxide, Water, and Earth’s Potential 409 Planetary Neighbors 377 15.7 Electron and Proton Affinities Are Linked: 14.3 Weathering and Solubilization pE versus pH 410 Mechanisms 377 15.8 Biological Oxidations 413 14.3a Ionic Solids and the Solubility 15.9 Aerobic Earth 413 Product 377 15.10 Water as an Ecological Medium 416 Worked Problem 14.1: Barium Sulfate 15.10a The Euphotic Zone and the Solubility 378 Biological Pump 416 14.3b Solubility and Basicity 379 15.10b Eutrophication in Freshwater Worked Problem 14.2: Calcium Lakes 418 Carbonate Solubility in Equilibrium 15.10c Nitrogen and Phosphorus: The with the Atmosphere 379 Limiting Nutrients 420 14.3c Ocean Acidification 380 15.10d Anoxia and Its Effects on Coastal 14.4 Ion Exchange: Clays and Humic Marine Waters 423 Substances 382 15.10e Wetlands as Chemical Sinks 427 14.5 Effects of Freshwater Acidification 386 15.10f Redox Effects on Metals 14.5a Soil Neutralization 386 Pollution 429 14.5b Hardness and Detergents 388 15.10g Fertilizing the Ocean with Iron 430

Problems 431 Chapter 18. Pest Control 491 Additional Reading 433 18.1 Insecticides 491 18.1a Persistent Insecticides: Chapter 16. Water Pollution and Water Organochlorines 492 Treatment 435 18.1b Molecular Shape and Biological 16.1 Water Use and Water Quality: Point and Activity 494 Nonpoint Sources of Pollution 435 18.1c Ecosystem Effects: 16.2 Regulation of Water Quality 439 Bioaccumulation 495 16.3 Water and Sewage Treatment 441 18.1d Bioaccumulation and the Partition 16.4 Desalinization of Seawater 443 Coefficient 498 16.5 Health Hazards 445 18.1e Nonpersistent Insecticides: 16.5a Pathogens and Disinfection 445 Organophosphates and Carbamates 499 16.5b Organic and Inorganic Contaminants 448 18.1f Molecular Mechanism of 16.5b.i Waste Sites 448 Cholinesterase Inhibitors 501 16.5b.ii Agriculture 449 18.1g Natural Insecticides 503 16.6 Low-Cost Water Technology for Developing 18.1h Integrated Pest Management 504 Countries 450 18.2 Herbicides 506 16.7 Trace Pollutants 451 18.2a Molecular Mechanism of Glyphosate 16.8 Perchlorate Pollution 452 Inhibition; Genetic Engineering 509 16.9 Summary of Hydrosphere–Lithosphere 18.3 Genetically Modified Organisms 511 Interactions 452 18.3a Genetically Modified Plants: Actualities and Potential 511 Problems 453 18.3b Resistance to Genetically Modified Additional Reading 454 Foods 514 18.3b.i Moral Issues 514 Part V. Biosphere 457 18.3b.ii Political Issues 516 Chapter 17. Nitrogen and Food Production 459 18.3b.iii Health and Environment 17.1 Nitrogen Cycle 459 Issues 516 17.2 Agriculture 463 Problems 519 17.2a Fertilizer and the Green Additional Reading 520 Revolution 463 17.2b Environmental Degradation 468 Chapter 19. Toxicity of Chemicals 523 17.2c Confined Animal Feeding 19.1 Acute and Chronic Toxicity 523 Operations 469 19.2 Cancer 526 17.2d Organic Farming and Sustainable 19.2a Mechanisms 527 Agriculture 470 19.2b Cancer Incidence and Testing 532 17.3 Nutrition 472 19.3 Hormonal Effects 536 17.3a Energy and Calories 472 19.3a Bisphenol A 539 17.3b Protein 473 19.4 Persistent Organic Pollutants: Dioxins and 17.3c Minerals and Vitamins 478 Polychlorinated Biphenyls 541 17.3d Antioxidants 483 19.4a Dioxins and Furans 542 17.3e Antioxidant Mechanisms 484 19.4a.i Toxicity 534 Problems 486 19.4a.ii Paper Bleaching and Additional Reading 487 Combustion Sources 544

19.4a.iii Natural Sources? 546 19.5d.i Exposure 567 19.4a.iv Exposure 548 19.5d.ii Bioavailability 571 19.4b Polychlorinated Biphenyls 549 19.5d.iii Toxicity 571 19.4c Polybrominated Diphenyl Ethers 552 Problems 574 19.4d Perflouroctanoic Sulfonate 552 Additional Reading 575 19.4e Global Transport 553 19.5 Toxic Metals 554 Appendices 19.5a Mercury 557 Appendix A: Organic Structures 579 19.5b Cadmium 562 Appendix B: Mathematical Fundamentals 589 19.5c Arsenic 565 19.5d Lead 567 Index 595

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Chemistry of the Environment by Spiro, Purvis-Roberts, and Stigliani fills a critical need by providing a coherent chemical account of the environmental issues we face. From air pollution and climate change, to acid rain and oil spills, to food security and genetically modified plants, to carcinogens and lead poisoning, Chemistry of the Environment puts the environmental story in chemical context, showing how the problems arise, and pointing ways to their solutions. I am particularly pleased that the authors have devoted an entire unit of their book to Energy and Materials, as I firmly believe that energy production and utilization are key to human welfare as well as the source of most environmental problems. The Energy and Materials unit sets out the challenges we face, and points to the many opportunities to develop new chemistry for effi- cient energy production and use. It will be especially helpful to young inves- tigators entering the field. Spiro, Purvis-Roberts, and Stigliani write in a clear and engaging style. They organize the material in a logical and compelling manner, emphasizing the many cross-connections among environmental topics. The bottom line is that this is the book on environmental chemistry that we all have been waiting for! It is a must read for young and old alike.

Harry Gray

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Environmental Chemistry Lessons “Here’s a short chemistry lesson”, wrote Bill McKibben in a 1995 New York Times Magazine feature story.a “Grasp it and you will grasp the reason the environmental era has barely begun. . . .” McKibben’s lesson is about the difference between two molecules, carbon monoxide (CO) and carbon dioxide

(CO2). Today’s automobiles release half a pound of carbon as CO per gallon of gasoline burned, around half as much as they did a generation ago, and the rate is going down with continuing improvements in technology. As a result, the air is now cleaner than it used to be in Los Angeles and in many other cities. But the same gallon of gasoline releases almost five and one-half

pounds of carbon as CO2, and this rate cannot be decreased. The atmospheric

concentration of CO2 is increasing worldwide, and bringing global warming with it. The two molecules capture two sides of the environmental coin, local versus global effects of human activity. Environmental quality has improved in many localities, thanks to environmental controls and new technologies, but the global problems are just beginning to be addressed, and they are much more difficult to solve. Carbon monoxide is a side product of combustion, and

is subject to emission controls, but CO2 is the end product of combustion and is the inevitable accompaniment of our reliance on fossil fuels. “Carbon monoxide versus carbon dioxide,” says McKibben, “one damn oxygen atom, and all the difference in the world”. McKibben’s story is a wonderful illustration of the power of chemistry to illuminate environmental issues. Chemistry is all around us, and it really does make a difference. The chemical cycles of the planet are increasingly dis- turbed by human activities. These disturbances can degrade the quality of life, as when auto emissions overwhelm the atmosphere’s capacity to clean the air over our cities. We are capable of ameliorating these effects, as the experience

a B. McKibben, “Not So Fast”, New York Times Magazine, July 23, 1995, pp. 24 –25.

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of Los Angeles demonstrates. But first we must understand the chemistry. In the case of Los Angeles, initial attempts to alleviate smog back in the 1960s actually made things worse. Standards were imposed on CO and hydrocarbon levels in auto emissions, and auto makers met those standards by increasing the air/fuel ratio to burn the fuel more completely. But smog levels increased because higher air/fuel ratios made combustion hotter, thereby increasing the

nitrogen oxide ( NOx) emissions. Only then was it discovered that nitrogen oxides and hydrocarbons are both key players in smog formation and that both have to be controlled. This kind of surprise is not unusual in environmental affairs. The world is a marvelously complex place, chemically, as in other ways. We are just beginning to understand how it works. This book tells the environmental story in the language of chemicals. It is grounded in the flows of chemicals and energy through nature on the one hand, and through our industrial civilization on the other. The parts of the book, Sustainability and Green Chemistry, Atmosphere, Energy and Materials, Hydrosphere and Lithosphere, and Biosphere, reflect this holistic perspective. Environmental issues frequently cut across these divisions, and the resulting interconnections add richness to the story. For example, leaded gasoline is linked to the issue of auto emission controls, a subject that arises in Part II, the Atmosphere, but it is also a major health hazard, as discussed in Part V, the Biosphere. Interconnections are even more numerous at the level of the underlying

chemistry. For example, the reactivity of dioxygen (O2) is a leitmotif for all parts of the book. Thus energy flow through industrial civilization (as well as through the biosphere itself ) depends on the oxygen–oxygen bond being rela-

tively weak, so that energy is released when O2 combines with organic mole-

cules. Yet, because of its unusual electronic structure, O2 is quite unreactive

until it encounters a free radical or a transition metal ion. These O2 activators determine most aspects of atmospheric chemistry, including how smog is

formed. They are also vitally important for the biosphere, since O2 metabo- lism gone awry is a threat to the integrity of biological molecules and has been implicated as a factor in cancer and aging. These interconnections provide a satisfying context for understanding the chemical world we live in and the environmental issues we face.

What This Book Is About This book is about the natural chemical cycles that form our world, and how humans are altering these cycles. Our world contains many chemical ele- ments, which combine into a much larger number of compounds. Under the influence of the energy flowing out of earth’s molten core and from the sun, these compounds are continually transformed into one another and back. These transformations occur in earth’s crust, in its waters, and in its atmosphere. The cycles are linked, one reaction depending on others, according to the laws of chemistry.

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Life evolved in harmony with these cycles, and has also altered them substantially. The rise of human civilizations has magnified this impact, first through the spread of agriculture, and then through the development of manu- facturing technologies. The modern industrial era accelerated the pace of chemical change, and now we see evidence everywhere of chemical imbal- ances that threaten human well-being, and even the continued existence of entire ecosystems. Increasingly, we are concerned whether our practices are sustainable. What are the key threats to our environment, and how can they be averted? How can chemistry contribute to the sustainablility of our world? These are the questions that animate this book. It is organized around the environmental story, and it brings science in as needed to illuminate that story. Some famil- iarity with chemistry is assumed, but freshman chemistry, or a good high school course should be sufficient. The book considers the following topics:

• Sustainability, and the role of “green chemistry” in reducing human impacts. • The chemistry of the atmosphere, and how it determines the issues of climate change, protection from ultraviolet (UV) radiation, and air pollution. • Energy, and how we obtain and use it, with emphasis on how we can reduce its environmental impact, particularly on climate. • The chemistry of the hydrosphere, and the problems of acidification of fresh and ocean waters, and of water overfertilization and pollution. • The biosphere, focusing on the role of agriculture and the spread of toxic compounds, both organic and inorganic.

Through these chapters, readers will learn about the critical role of chemistry in the great environmental issues of our time. This understanding can help to inform their actions as participants in our human enterprise.

Acknowledgments This book is a successor to Chemistry of the Environment, eds. 1 and 2 by Spiro and Stigliani (Prentice Hall, 1996, 2003). The material has been exten- sively revised, reflecting the rapid evolution of all areas of environmental science and of environmental concerns. Much of the text has been rewritten for clarity, and the organization has been simplified for smoother flow. Additional worked and end-of-chapter problems have been provided, and the lists of additional readings have been updated. We are indebted to a number of individuals who helped us improve the book. Douglas Fox, John Perona, and Richard Treptow, read parts or all of the book, and provided extensive suggestions. Keith Kuwata tested several sec- tions of the book in class, and provided thoughtful feedback from his students.

Special thanks go to Kirk Smith, Jim Purvis, Alexandra Soldatova, and Robert Socolow, for help with the Air Pollution, Nuclear Energy, Renewable Energy and Energy Utilization chapters, and to Bruce Ames and Lois Gold for a helpful critique of the material on carcinogens in Chapter 19, Toxicity of Chemicals. We are especially grateful to Helen Spiro and Jon Roberts for reading and helping revise some of the material, and for their patient and loving support and advice during the long and arduous process of crafting the book.

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