Tropospheric Ozone And Associated Photochemical Oxidants 871

I. Environmental Chambers 872

a. Types of Chambers 872

b. Preparation of Reactants, Including " Clean Air" 876

c. Light Sources 876

d. Typical Time - Concentration Profiles of Irradiated

VOC - NOx - Air Mixtures 878 e. Advantages and Limitations of Environmental Chambers 880

2. Isopleths for Ozone and Other Photochemically Derived Species 882

3. Models 886

a. Simple Models 886

b. Mathematical Models 887

c. Simple Mathematical Models 892

d. Grid Models: Urban to Regional Scales 893

e. Models Incorporating Particles 907

B. REACTIVITY OF VOC 907

1. Typical Reactivity Scales 907

2. Application to Control of Mobile Source Emissions 909

C. FIELD OBSERVATIONS OF VOC, NOx, AND O, 913

D. ALTERNATE FUELS 918

1. Reformulated Gasolines 918

2. Compressed Natural Gas (CNG) 919

3. Liquefied Petroleum Gas (LPG) 920

4- Alcohol Fuels and Blends with Gasoline 920

5. Hydrogen 921

6. Electric Vehicles 921

E. CONTROL OF ACIDS 921

F. CONTROL OF PARTICLES 923

G. ATMOSPHERIC CHEMISTRY AND RISK ASSESSMENTS OF HAZARDOUS AIR POLLUTANTS 925

H. PROBLEMS 930 REFERENCES 932

Appendix I: Enthalpies of Formation of Some Gaseous Molecules, Atoms, and Free Radicals at 298 K 943 Appendix II: Bond Dissociation Energies 945 Appendix III: Running the OZIPR Model 947 Appendix IV: Some Relevant Web Sites 949 Appendix V: Pressures and Temperatures for Standard

Atmosphere 951 Appendix VI: Answers to Selected Problems 952 Subject Index 957

This Page Intentionally Left Blank

Preface

What is written without effort is in general read without pleasure.

Samuel Johnson (1709- 1784) In William Seward Biographia

Given this admonition, written long ago by English poet and critic Samuel Johnson, we trust that this book may be read with some pleasure by a "spectrum" of readers.

The field of atmospheric chemistry has undergone dramatic changes since our first book on this subject was published in 1986. Since then, a number of new, exciting, and highly relevant research areas have emerged. We treat these here, along with the fundamentals of spectroscopy, photochemistry, and reaction kinetics and mechanisms of atmospheric systems. For example, the discovery of the Antarctic ozone hole has left no doubt that chlorofluorocarbons (CFCs) have led to depletion of stratospheric ozone and has highlighted the importance of heterogeneous chemistry on polar stratospheric clouds. Atmospheric measurements of the CFCs have documented changes in their global concentrations in response to control measures. The importance of emissions and chemistry for climate changes on a global scale has become an area of intense popular interest and scientific research. Furthermore, the formation, chemistry, and fates of airborne particulate matter, particularly that less than 2.5 /jlm in diameter (i.e., PM2.5), are now recognized not only as important to global climate issues but also as of concern for their toxicological effects. The similarity in much of the chemistry of indoor air pollutants and those outdoors is now evident, and the importance of understanding the chemistry of airborne toxic chemicals (also known as "hazardous air pollutants," HAPs) for the development of sound risk assessments is clear. A great deal more is known about the role of emissions and atmospheric reactions of polycyclic aromatic hydrocarbons in the mutagenicity and carcinogenicity of urban atmo spheres. In addition to these major developments in the field, there has been a significant increase in our understanding of the gas-phase atmospheric chemistry and photochemistry of organics, oxides of nitrogen, and S02 and rapidly increasing evidence for the importance of a wide range of heterogeneous reactions in the troposphere.

We have attempted in this new book to present the current understanding of the chemistry of the natural and polluted upper and lower atmosphere in such a way that it will be useful to a range of atmospheric chemists as well as to atmospheric scientists and engineers working in this field. However, the fundamentals (e.g., theories, rates, and mechanisms of homogeneous and heterogeneous reactions and of spectroscopic and photochemical processes) are also emphasized. We believe that this approach is useful in providing the necessary background and tools for graduate students as well as for scientists and engineers in related fields who wish to enter this exciting and dynamic area. Problems are provided at the end of most chapters (and answers to selected problems are in Appendix VI) to enhance the book's use in teaching.

The literature is assessed through the end of 1998 and, in some cases, into 1999. We have cited only papers in the peer-reviewed literature or, in a few instances, government agency reports that are readily available. Our approach has been to consider primarily typical examples of major papers in the refereed literature in the relevant areas. Because of the enormous breadth of the field today, we have not been able to reference all papers in all relevant areas, which will unavoidably lead to some omissions. We apologize in advance to our colleagues whose work might not have been cited in the relevant area.

We are deeply indebted to our many colleagues in the field whose outstanding work, generous sharing of results, and helpful discussions have made this work possible. It is our hope that this book does justice to the current state of this exciting, rapidly maturing, and scientifically and societally relevant discipline.

Barbara J. Finlayson-Pitts James N. Pitts, Jr.

Fawnskin, California August 19, 1999

About the Authors

Barbara J. Finlayson-Pitts is Professor of Chemistry at the University of California, Irvine. Her research program focuses on laboratory studies of the kinetics and mechanisms of reactions in the atmosphere, especially those involving gases with liquids or solids of relevance in the troposphere. Reactions of sea salt particles to produce photochemically active halogen compounds and the subsequent fates of halogen atoms in the troposphere are particular areas of interest, as are reactions of oxides of nitrogen at aqueous and solid interfaces. Her research is currently supported by the National Science Foundation, the Department of Energy, the California Air Resources Board, the Dreyfus Foundation, and NATO. She has authored or coau-thored more than 80 publications in this area, as well as a previous book, Atmospheric Chemistry: Fundamentals and Experimental Techniques.

At UCI, she teaches graduate-level courses in atmospheric chemistry on a regular basis. In addition, she teaches such classes as undergraduate instrumental analysis, in which she is developing a new laboratory curriculum centered around the analysis of complex environmental mixtures. This work has been supported by the Dreyfus Foundation and UCI.

She received her undergraduate B.Sc. (Hons) in 1970 from Trent University in Peterborough, Ontario, Canada, where her interest in atmospheric chemistry was first sparked by discussions of the spectroscopy of auroras in a physical chemistry class taught by Professor R. E. March. She obtained her master's degree (1971) and Ph.D. (1973) from the University of California, Riverside. After a year's postdoctoral work at UCR, she joined the faculty of California State University, Fullerton, where she taught and carried out research in physical and atmospheric chemistry. In 1994, she joined the faculty at UCI.

Dr. Finlayson-Pitts is a member of a number of professional societies, including the American Chemi cal Society, the American Geophysical Union, the American Association for the Advancement of Science, and Iota Sigma Pi. She is the recipient of a number of awards, including the Governor General's Medal at Trent University, a Woodrow Wilson Fellowship, a National Research Council of Canada Science Scholarship, Golden Key National Honor Society, and a Japan Society for the Promotion of Science Fellowship. She has been elected a Fellow of the American Association for the Advancement of Science and has several awards for undergraduate teaching.

James N. Pitts, Jr., is a Research Chemist at the University of California, Irvine, and Professor Emeritus from the University of California, Riverside. He was Professor of Chemistry (1954-1988) and cofounder (1961) and Director of the Statewide Air Pollution Research Center (1970-1988) at the University of California, Riverside. His research has focused on the spectroscopy, kinetics, mechanisms, and photochemistry of species involved in a variety of homogeneous and heterogeneous atmospheric reactions, including those associated with the formation and fate of mutagenic and carcinogenic polycyclic aromatic compounds. He is the author or coauthor of more than 300 research publications and three books: Atmospheric Chemistry: Fundamentals and Experimental Techniques, Graduate School in the Sciences—Entrance, Survival and Careers, and Photochemistry. He has been coeditor of two series, Advances in Environmental Science and Technology and Advances in Photochemistry. He served on a number of panels in California, the United States, and internationally. These included several National Academy of Science panels and service as Chair of the State of California's Scientific Review Panel for Toxic Air Contaminants and as a member of the Scientific Advisory Committee on Acid Deposition.

He received his B.S. (1945) and Ph.D. (1949) from the University of California, Los Angeles; his research advisor was Professor Francis E. Blacet, who first identified the photolysis of NOz as the anthropogenic source of ozone in photochemical air pollution. From 1942 to 1945, he participated in laboratory and field studies in chemical warfare. He was on the faculty at Northwestern University from 1949 to 1954, leaving to join the faculty at the new University of California, Riverside, campus. He was a Guggenheim Fellow at University College, Oxford, in 1961 and a Research Fellow of Merton College, Oxford, in 1965.

Dr. Pitts is a member of a number of professional societies, including the American Chemical Society, the American Geophysical Union, the American Association for the Advancement of Science, and the Ameri can Physical Society. He has received a number of awards for his research, including the Clean Air Award of the California Lung Association (1979), the Frank A. Chambers Award for "Outstanding Achievement in the Science and Art of Air Pollution Control" from the Air Pollution Control Association (1982), the Richard C. Tolman Medal (1983), the UCR Faculty Research Lectureship (1965), the F. J. Zimmerman Award in Environmental Science, and the Clean Air Award (1992) from the South Coast Air Management District. He is an elected Fellow of the American Association for the Advancement of Science. He has also received numerous commendations from local, state, and federal legislators for his application of fundamental atmospheric chemistry to air pollution problems.

Acknowledgments

Many individuals and organizations contributed to making this book a reality. First, our assistant, Mae Minnich, devoted innumerable long hours to the manuscript; her organization and professional talents were indispensable. Without her outstanding skills in word processing and manuscript preparation, combined with her patience, wonderful sense of humor, and tireless enthusiasm, this undertaking would not have been possible. Kelly Donovan took almost indecipherable drafts of figures and turned them into clear and attractive drawings, some of which reflect major creativity on her part. The cheerful dedication, professional skills, and willingness to "go the extra mile" on the part of both of these individuals helped the authors through some long days.

The assistance of a number of undergraduate and graduate students, postdoctoral fellows, and colleagues was critical in this effort. Christopher Elliott and Ellen Fleyshman assembled and organized the thousands of references and, along with Lisa Wingen, Alisa Ezell, and John Elliott, also provided computer and technical assistance. Their unflagging assistance in the midst of the final fray and the moral and concrete support of others, including Stacie Tibbets and Mike and Connie Ezell, reenergized us during the final "countdown." The assistance of Bill Barney, Mike and Alisa Ezell, Krishna Foster, Michael Gebel, Matt Lakin, Lisa Wingen, and Weihong Wong with figures and final page proofing was very helpful, as was the able library assistance of Jean Miller.

Sasha Madronich generously not only reviewed the section on atmospheric radiation, but provided his unpublished calculations of actinic fluxes at different altitudes in a form useful to the atmospheric chemistry community for estimates of photolysis rates from the troposphere through the stratosphere. A number of colleagues reviewed chapters or portions of chapters, and their insightful comments and suggestions are greatly appreciated. They include Janet Arey, Roger Atkinson, Thorsten Benter, Theo Brauers, Carl Berkowitz, Don Blake, Chris Doran, Anders Feilberg, Mario Molina, Ole John Nielsen, Torben Nielsen, Joyce Penner, F. Sherwood Rowland, David Rusch, Stephen Schwartz, Chet Spicer, Jochen Stutz, Darin Toohey, Douglas Worsnop, Y. L. Yung, and Paul Ziemann.

We are indebted to many colleagues who provided figures, data, and stimulating discussions, especially Ed Baum, John Barker, Thorsten Benter, William Carter, Glenn Cass, Ralph Cicerone, Bart Croes, David Crosely, Donald Dabdub, Paul Davidovits, Leon Dolislager, Alisa Ezell, Michael Ezell, Jerome Fast, Jeff Gaffney, David Golden, Les Grant, Bill Harger, John Holmes, John Jayne, John Johnson, Jake Hales, John Hemminger, Wolfgang Junkermann, George Kirk, Charles Kolb, William Lockett, Alan Lloyd, Nancy Marley, Mike Nicovich, Randy Pasek, Shankar Prasad, Michael Prather, Ralph Propper, Scott Samuelsen, Rolf Sander, Jim Seiber, Brian Toon, Ernie Tuazon, Ken Schere, Charles Weschler, Hal Westberg, Arthur Winer, Paul Wine, Ed Yotter, Mark Zahniser, and Barbara Zielin-ska.

Michael Gery, who developed the OZIPR model, graciously provided advice on its use as well as electronic copies of the documentation. This model, which contains the two major chemical mechanism schemes for gas-phase, VOC-NO^ chemistry in use in atmospheric chemistry, is available on the Academic Press Web site (http://www.academicpress.com/pecs/down-load). A number of problems using this model are included in the book, and it is a valuable teaching tool for assessing the effects of various model input parameters on predicted concentrations of a wide variety of gas-phase species. His assistance and that of Marcia Dodge of the U.S. EPA in making it available are appreciated.

The authors have been very fortunate over the years to have a number of accomplished and creative mentors who generously shared their knowledge of, and enthusiasm for, the fields of fundamental photochemistry, spectroscopy, and kinetics; these include F. E. Blacet, E. J. Bowen, P. A. Leighton, W. A. Noyes, Jr., E. W. R. Steacie, and R. E. March. We hope that the central importance of these fundamentals to understanding atmospheric chemistry is evident in this book. We also appreciate the tremendously talented and enthusiastic researchers, too numerous to mention here, who have spent time in our research groups over the years. Many of them have gone on to careers in atmospheric chemistry; it has given us a great deal of satisfaction and delight to see the "academic lineage" being passed on from our mentors to them.

The authors have also very much appreciated the scientific interactions with, and financial support of, a number of public and private agencies and foundations, which have allowed us to conduct research in various areas in atmospheric chemistry. Over several decades, key individuals at these organizations have been helpful in many ways, and we are grateful to them. Agencies and individuals include Jarvis Moyers, Anne-Marie Schmoltner, and the late Richard Carrigan at the National Science Foundation; David Ballantine, George Stapleton, Ari Patrinos, Michael Riches, Michelle Broido, Rickey Petty, and Peter Lunn at the Department of Energy; John Holmes, Bart Croes, Ralph Propper, Jack Suder, Randy Pasek, and Eileen Mc-Cauley at the California Air Resources Board; Ron Patterson and Marcia Dodge at the Environmental Protection Agency; Brian Andreen and the late Hal Ramsey at The Research Corporation; and Robert Lichter at the Dreyfus Foundation.

We have been impressed indeed by the professional skills, patience, thoughtful and imaginative ideas, and dedication of the staff at Academic Press. Special thanks and appreciation go to Executive Editor David Packer, as well as his colleagues at AP, including Cheryl Uppling (Senior Production Editor), Mike Early (Book Production Manager), Liz Novelozo and Kim Schettig (Marketing), Linda Klinger (Editorial Coordinator), design artist Amy Stirnkorb, and David Phanco.

On a more personal note, the support of our colleagues at the University of California, Irvine, particularly the Chairs in the Department of Chemistry, John Hemminger and Richard Chamberlin, has been essential to the completion of this project. The hospitality and encouragement of the Science Education Project staff, especially Ann and George Miller, Lynne Davanzo, and Frank Potter, are appreciated. We are also grateful to Edward J. Mclntyre for his professional skills and wise and effective counsel and to Bill and Maura Dickerson for their timely advice during an interesting period in the genesis of this book.

Successful completion of this project was only possible through the professional and personal support of our friends and neighbors, particularly in University Hills at UCI as well as in our Fawnskin mountain "hamlet" (population 360 and elevation 6500 ft), especially Doris Layne and Linda Neuman. Regular visits to our home in Fawnskin by a variety of wildlife of the nonhuman type, including eagles, coyotes, bear, quail, and wild turkeys, provided much sanity and perspective during the writing of this book.

Finally, we are very grateful to all of our colleagues, families, and friends, as well as to our golden retriever contingent, Babe, Maj, and BR, who have been extremely patient with our being "missing in action" for too many years while finishing this book. They (and we, at times) wondered if it would ever end... but in large part through all of their patience, support, and encouragement, it finally has!

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