McKay, Donald. "Front matter" Multimedia Environmental Models Edited by Donald McKay Boca Raton: CRC Press LLC,2001 Multimedia Environmental Models The Fugacity Approach Second Edition Donald Mackay LEWIS PUBLISHERS Boca Raton London New York Washington, D.C. Multimedia Environmental Models The Fugacity Approach Second Edition ©2001 CRC Press LLC Preface This book is about the behavior of organic chemicals in our multimedia envi- ronment or biosphere of air, water, soil, and sediments, and the diversity of biota that reside in these media. It is a response to the concern that we have unwisely contaminated our environment with a large number of chemicals in the mistaken belief that the environment’s enormous capacity to dilute and degrade will reduce concentrations to negligible levels. We now know that the environment has only a finite capacity to dilute and degrade. Certain chemicals have persisted and accumu- lated to levels that have caused adverse effects on wildlife and even humans. Some chemicals have the potential to migrate from medium to medium, reaching unex- pected destinations in unexpectedly high concentrations. We need to understand these processes, not only qualitatively in the form of assertions that DDT evaporates and bioaccumulates, but quantitatively as statements that DDT in a particular region evaporates at a rate of 100 kg per year and bioaccumulates from water at a concen- tration of 1 ng/L to fish at levels of 1 m g/g. We have learned that chemical behavior in the complex assembly of environ- mental media is not a random process like leaves blowing in the wind. The chemicals behave in accordance with the laws of nature, which dictate chemical partitioning and rates of transport and transformation. Most fundamentally, the chemicals are subject to the law of conservation of mass, i.e., a mass balance exists for the chemical that is a powerful constraint on quantities, concentrations, and fluxes. By coupling the mass balance principle with expressions based on our understanding of the laws of nature, we can formulate a quantitative accounting of chemical inputs and outputs. This book is concerned with developing and applying these expressions in the form of mathematical statements or “models” of chemical fate. These accounts or models are invaluable summaries of chemical behavior. They can form the basis of remedial and proactive strategies. Such models can confirm (or deny) that we really understand chemical fate in the environment. Since many environmental calculations are complex and repetitive, they are particularly suitable for implementation on computers. Accordingly, for many of the calculations described in this book, computer programs are described and made available on the Internet with which a variety of chemicals can be readily assessed in a multitude of environmental situations. The models are formulated using the concept of fugacity, which was introduced by G.N. Lewis in 1901 as a criterion of equilibrium and has proved to be a very convenient and elegant method of calculating multimedia equilibrium partitioning. It has been widely and successfully used in chemical processing calculations. In this book, we exploit it as a convenient and elegant method of explaining and deducing the environmental fate of chemicals. Since publication of the first edition of this book ten years ago, there has been increased acceptance of the benefits of using fugacity to formulate models and interpret environmental fate. Multimedia fugacity models are now routinely used for evaluating chemicals before and after production. Much of the experience gained in these ten years is incorporated in this second edition. Mathematical simulations of chemical fate are now more accurate, compre- ©2001 CRC Press LLC hensive, and reliable, and they have gained greater credibility as decision-support tools. No doubt this trend will continue, especially as young environmental scientists and engineers take over the reins of environmental science and continue to develop new fugacity models. This book has been written as a result of the author teaching graduate-level courses at the University of Toronto and Trent University. It is hoped that it will be suitable for other graduate courses and for practitioners of the environmental science of chemical fate in government, industry, and the private consulting sector. The simpler concepts are entirely appropriate for undergraduate courses, especially as a means of promoting sensitivity to the concept that chemicals, which provide modern society with so many benefits, must also be more carefully managed from their cradle, in the chemical synthesis plant, to their grave of ultimate destruction. At the end of most chapters is a “Concluding Example” in which a student may be asked to apply the principles discussed in that chapter to one or more chemicals of their choice. Necessary data are given in Table 3.5 in Chapter 3. I have found this useful as a method of assigning different problems to a large number of students, while allowing them to explore the properties and fate of substances of particular interest to them. We no longer regard the environment as a convenient, low-cost dumping ground for unwanted chemicals. When we discharge chemicals into the environment, it must be with a full appreciation of their ultimate fate and possible effects. We must ensure that mistakes of the past with PCBs, mercury, and DDT are not repeated. This is best guaranteed by building up a quantitative understanding of chemical fate in our total multimedia environment, how chemicals will be transported and transformed, and where, and to what extent they may accumulate. It is hoped that this book is one step toward this goal and will be of interest and use to all those who value the environment and seek its more enlightened stewardship. Donald Mackay ©2001 CRC Press LLC Acknowledgments It is a pleasure to acknowledge the contribution of many colleagues. Much of the credit for the approaches devised in this book is due to the pioneering work by George Baughman, who saw most clearly the evolution of multimedia environmental modeling as a coherent and structured branch of environmental science amid the often frightening complexity of the environment and the formidable number of chemicals with which it is contaminated. Brock Neely, Russ Christman, and Don Crosby were instrumental in encouraging me to apply the fugacity concept to environmental calculations. I am indebted to my former colleagues at the University of Toronto, especially Wan Ying Shiu and Sally Paterson, whose collaboration has been crucial in devel- oping the fugacity approach. I am grateful to my more recent colleagues at Trent University, and our industrial and government partners who have made the Canadian Environmental Modelling Centre a successful focus for the development, validation, and dissemination of mass balance models. This second edition was written in part when on research leave at the Department of Environmental Toxicology at U.C. Davis, where Marion Miller, Don Crosby, and their colleagues were characteristically generous and supportive. At Trent, I was greatly assisted by David Woodfine, Rajesh Seth, Merike Perem, Lynne Milford, Angela McLeod, Adrienne Holstead, Todd Gouin, Alison Fraser, Ian Cousins, Tom Cahill, Jenn Brimecombe, and Andreas Beyer. I am particularly grateful to Steve Sharpe for the figures, to Matt MacLeod and Christopher Warren for their critical review and comments, and to Eva Webster for her outstanding scientific and editorial contributions. Without the support and diligent typing of my wife, Ness, this book would not have been possible. Thank you. I dedicate this book to Ness, Neil, Ian, Julia, and Gwen, and especially to Beth, who was born as this edition neared completion. I hope it will help to ensure that her life is spent in a cleaner, more healthful environment. ©2001 CRC Press LLC Contents Chapter 1 Introduction Chapter 2 Some Basic Concepts 2.1 Introduction 2.2 Units 2.3 The Environment as Compartments 2.4 Mass Balances 2.5 Eulerian and Lagrangian Coordinate Systems 2.6 Steady State and Equilibrium 2.7 Diffusive and Nondiffusive Environmental Transport Processes 2.8 Residence Times and Persistence 2.9 Real and Evaluative Environments 2.10 Summary Chapter 3 Environmental Chemicals and Their Properties 3.1 Introduction and Data Sources 3.2 Identifying Priority Chemicals 3.3 Key Chemical Properties and Classes 3.4 Concluding Example Chapter 4 The Nature of Environmental Media 4.1 Introduction 4.2 The Atmosphere 4.3 The Hydrosphere or Water 4.4 Bottom Sediments 4.5 Soils 4.6 Summary 4.7 Concluding Example Chapter 5 Phase Equilibrium 5.1 Introduction 5.2 Properties of Pure Substances 5.3 Properties of Solutes in Solution 5.4 Partition Coefficients 5.5 Environmental Partition Coefficients and Z Values 5.6 Multimedia Partitioning Calculations 5.7 Level I Calculations 5.8 Concluding Examples Chapter 6 Advection and Reactions 6.1 Introduction ©2001 CRC Press LLC 6.2 Advection 6.3 Degrading Reactions 6.4 Combined Advection and Reaction 6.5 Unsteady-State Calculations 6.6 The Nature of Environmental Reactions 6.7 Level II Computer Calculations 6.8 Summary 6.9 Concluding Example Chapter 7 Intermedia Transport 7.1 Introduction 7.2 Diffusive and Nondiffusive Processes 7.3 Molecular Diffusion within a Phase 7.4 Turbulent or Eddy Diffusion within a Phase 7.5 Unsteady-State Diffusion 7.6 Diffusion in Porous Media 7.7 Diffusion between Phases: The Two-Resistance Concept 7.8 Measuring Transport D Values 7.9 Combining Series and Parallel D Values 7.10 Level III Calculations 7.11 Level IV Calculations 7.12 Concluding Examples Chapter 8 Applications of Fugacity Models 8.1 Introduction, Scope, and Strategies 8.2 Level I, II, and III Models 8.3 An Air-Water Exchange Model 8.4 A Surface Soil Model 8.5 A Sediment-Water Exchange Model 8.6 QWASI Model of Chemical Fate in a Lake 8.7 QWASI Model of Chemical Fate in Rivers 8.8 QWASI Multi-segment Models 8.9 A Fish Bioaccumulation Model 8.10 Sewage Treatment Plants 8.11 Indoor Air Models 8.12 Uptake by Plants 8.13 Pharmacokinetic Models 8.14 Human Exposure to Chemicals 8.15 The PBT–LRT Attributes 8.16 Global Models 8.17 Closure Appendix Fugacity Forms References and Bibliography McKay, Donald. "Introduction" Multimedia Environmental Models Edited by Donald McKay Boca Raton: CRC Press LLC,2001 ©2001 CRC Press LLC C HAPTER 1 Introduction Since the Second World War, and especially since the publication of Rachel Carson’s Silent Spring in 1962, there has been growing concern about contamination of the environment by “man-made” chemicals. These chemicals may be present in indus- trial and municipal effluents, in consumer or commercial products, in mine tailings, in petroleum products, and in gaseous emissions. Some chemicals such as pesticides may be specifically designed to kill biota present in natural or agricultural ecosys- tems. They may be organic, inorganic, metallic, or radioactive in nature. Many are present naturally, but usually at much lower concentrations than have been estab- lished by human activity. Most of these chemicals cause toxic effects in organisms, including humans, if applied in sufficiently large doses or exposures. They may therefore be designated as “toxic substances.” There is a common public perception and concern that when these substances are present in air, water, or food, there is a risk of adverse effects to human health. Assessment of this risk is difficult (a) because the exposure is usually (fortunately) well below levels at which lethal toxic effects and even sub-lethal effects can be measured with statistical significance against the “noise” of natural population variation, and (b) because of the simultaneous multiple toxic influences of other substances, some taken voluntarily and others involuntarily. There is a growing belief that it is prudent to ensure that the functioning of natural ecosystems is unimpaired by these chemicals, not only because ecosystems have inherent value, but because they can act as sensing sites or early indicators of possible impact on human well-being. Accordingly, there has developed a branch of environmental science concerned with describing, first qualitatively and then quantitatively, the behavior of chemicals in the environment. This science is founded on earlier scientific studies of the condition of the natural environment—meteorology, oceanography, limnology, hydrology, and geomorphology and their physical, energetic, biological, and chem- ical sub-sciences. This newer branch of environmental science has been variously termed environmental chemistry, environmental toxicology, or chemodynamics . [...]... the first (19 91) edition I have benefited greatly from the efforts of those who have sought to understand environmental phenomena and who have applied the fugacity approach when deducing the fate of chemicals in the environment There is no doubt that, as we enter the new millennium, environmental science is becoming more quantitative It is my hope that this book will contribute to that trend ©20 01 CRC Press... characterize the equilibrium that exists between environmental phases such as air, water, and soil Most of the emphasis is placed on organic chemicals, which are fortunately more susceptible to generalization than metals and other inorganic chemicals when assessing environmental behavior The concept of fugacity, which was introduced by G.N Lewis in 19 01 as a more convenient thermodynamic equilibrium... determine the dominant environmental phenomena We develop these mathematical procedures from a foundation of thermodynamics, transport phenomena, and reaction kinetics Examples are presented of chemical fate assessments in both real and evaluative multimedia environments at various levels of complexity and in more localized situations such as at the surface of a lake These calculations of environmental fate... readers can write their own programs using the system of their choice Microsoft Windows® software for performing model calculations is available from the Internet site www.trentu.ca/envmodel Older DOS-based models are also available They are updated regularly and are subject to revision In all cases, the equations correspond closely to those in this book (unless otherwise stated), and they are totally... the benefits of chemicals are enjoyed while the risk of adverse effects from them is virtually eliminated To do this, we must exert effective and cost-effective controls over the use of such chemicals, and we must have available methods of calculating their environmental behavior in terms of concentration, persistence, reactivity, and partitioning tendencies between air, water, soils, sediments, and biota... fugacity, which was introduced by G.N Lewis in 19 01 as a more convenient thermodynamic equilibrium criterion than chemical potential, has been widely used in chemical process calculations Its convenience in environmental chemical equilibrium or partitioning calculations has become apparent only in the last two decades It transpires that fugacity is also a convenient quantity for describing mathematically... to write computer programs in languages such as FORTRAN, BASIC, and C The first edition of this book was regarded as very advanced by including a diskette of programs in BASIC Such programs have the ©20 01 CRC Press LLC immense benefit that the sequence and details of calculations are totally transparent Executable versions can be run on any computer Unfortunately, it is not always easy to change input . Treatment Plants 8 .11 Indoor Air Models 8 .12 Uptake by Plants 8 .13 Pharmacokinetic Models 8 .14 Human Exposure to Chemicals 8 .15 The PBT–LRT Attributes 8 .16 Global Models 8 .17 Closure Appendix . Calculations 7 .11 Level IV Calculations 7 .12 Concluding Examples Chapter 8 Applications of Fugacity Models 8 .1 Introduction, Scope, and Strategies 8.2 Level I, II, and III Models 8.3 An Air-Water. McKay, Donald. "Front matter" Multimedia Environmental Models Edited by Donald McKay Boca Raton: CRC Press LLC,20 01 Multimedia Environmental Models The Fugacity Approach Second Edition Donald