Why "A Study of Interrelationships?"
Environmental science is an interdisciplinary field. Because environmental disharmonies occur as a result of the interaction between humans and the natural world, we must include both when seeking solutions to environmental problems. It is important to have a historical perspective, appreciate economic and political realities, recognize the role of different social experiences and ethical backgrounds, and integrate these with the science that describes the natural world and how we affect it. Environmental Science: A Study of Interrelationships incorporates all of these sources of information when discussing any environmental issue. Furthermore, the authors have endeavored to present a balanced view of issues, diligently avoiding personal biases and fashionable philosophies.
     Environmental Science: A Study of Interrelationships is intended as a text for a one-semester, introductory course for students with a wide variety of career goals. They will find it interesting and informative. The central theme is interrelatedness. No text of this nature can cover all issues in depth. What we have done is to identify major issues and give appropriate examples that illustrate the complex interactions that are characteristic of all environmental problems. There are many facts presented in charts, graphs, and figures that help to illustrate the scope of environmental issues. However, this is not the core of the text, since the facts will change.

Organization and Content
This book is divided into five parts and twenty chapters. It is organized to provide an even, logical flow of concepts and to provide clear illustrations of the major environmental issues of today. In this ninth edition, each part opens with a guest author's essay highlighting an environmental issue close to their home.

Part 1 establishes the theme of the book by looking at the kinds of environmental issues typical of different regions of North America. In each region, the specific issues selected involve scientific, social, political, and economic components typical of environmental problems. Chapter 2 focuses on the philosophical base needed to examine environmental issues by discussing various ethical and moral stands that shape how people approach environmental issues. Chapter 3 introduces economic issues and the concept of risk analysis. Both of these topics will be also brought up at several points later in the text.

Part 2 provides an understanding of the ecological principles that are basic to organism interactions and the flow of matter and energy in ecosystems. The nature of food chains and how they affect the flow of matter and energy are discussed. Other topics include: the efficiency of energy flow through ecosystems, the intricacies of organism-to-organism interaction, and the creative role of natural selection in shaping ecological relationships. Principles of population structure and organization are also developed in this section, with particular attention to the implications of these principles to the growth and impact of human populations.

Part 3 focuses on energy. A major emphasis is on the historically important, nonrenewable fossil fuels that have stimulated economic success of the developed economies of the world. Renewable sources of energy are discussed, but with the recognition that they currently are a small part of the world energy picture. Weapons production and nuclear power plants use enormous amounts of energy that can be released from the nucleus of the atom. Both of these uses have caused fear among the public related to the dangers of radiation and the adequacy of waste disposal. These issues are discussed in this section.

Part 4 emphasizes the impact of human activity on natural ecosystems. As human populations grow, and technology changes, the magnitude of human actions becomes more apparent. The natural ecosystems on land and water are modified to meet human needs. The heavy use of pesticides in agriculture is discussed in this section.

Part 5 deals with the major types of pollution. Pollution affects the health and welfare of humans and other organisms. Air pollution, solid waste, and hazardous and toxic substances are discussed in this section. The cost of pollution cannot always be measured in financial terms, but may be reflected in the mental and physical health of the populace. Ultimately, governments must address environmental concerns and develop policy to address the concerns. Increasingly, the concerns are international in scope and require negotiations between governments with very different economic conditions and concerns.

What makes this text unique?
This text is written with the student in mind. Both authors have many years of teaching experience and use their knowledge of what helps students learn to shape the text. All aspects of the text, writing style, illustrations, review materials, and boxed readings are designed to be informative without being overly complex. Many of the factual details are included in illustrations and tables rather than in the narrative of the text. For the person who wants facts, they are present, but do not obscure the general concepts and principles being described.
     Often the clearest way to present information is with an illustration. Each drawing, chart, graph, or photograph is designed to help students visualize an idea or concept, or create a mental picture that enhances the written text. The review materials at the end of each chapter are designed as learning tools. Review questions, vocabulary lists, and concept maps are all useful aids to help students assess whether they have a firm grasp of the content of the chapter.
     The authors work very hard to present a balanced, unbiased presentation of the material. It is not the purpose of a textbook to tell you what to think. The purpose of a text is to provide access to information and the conceptual framework needed to understand complex issues so that you can understand the nature of environmental problems and formulate your own views.

Pedagogy and Learning Aids
1.      A world map with political boundaries can be found immediately following this preface. We believe that this will help the reader to more fully understand and appreciate global environmental issues. Each of the five parts of the text begins with an introduction that places the upcoming chapters in context for the reader by recalling previously discussed material and by describing the organization of the chapters to come.
2.      Each chapter begins with a set of learning objectives, an outline, and a conceptual diagram, all of which give the student a broad overview of the interrelated forces that are involved in the material to be discussed. The student is encouraged to refer to these resources while reading and reviewing the chapter.
3.      Chapters conclude with an Issues and Analysis case study, a summary, a list of key terms, review questions, critical thinking questions, a list of topics that correspond to specific Internet links on the accompanying web site, and a new feature-concept mapping. This new exercise helps to reinforce understanding of basic concepts and principles through creating concepts maps from a list of key words. Combined with the introductory conceptual diagram at the beginning of the chapter, these mapping exercises help to illustrate the connections between environmental principles, issues, and possible solutions.
4.      To dramatize and clarify text material, each chapter includes a number of tables, charts, graphs, maps, drawings, or photographs. Each illustration has been carefully chosen to provide a pictorial image or an organized format for showing detailed information, which helps the reader comprehend the chapter material by reinforcing the copy in the surrounding textual content.
5.      Each chapter also includes boxed readings. These provide an in-depth consideration of a specific situation that is relevant to the content, an alternative viewpoint, or a wider worldview of the issues discussed in the chapter.
6.      The text concludes with several appendices that deal with the following topics: critical thinking, the metric system, the periodic table of the elements, some thoughts on what you can do to make the world a better place in which to live, and how to write to public officials. In addition there is a complete glossary and index.

Acknowledgements
The creation of a textbook requires a dedicated team of professionals who provide guidance, criticism, and encouragement. It is also important to have open communication and dialog in order to deal with the many issues that arise during the development and production of a text. Therefore, we would like to thank Marge Kemp, Kathy Loewenberg, Heather Wagner, Peggy Selle, COPYEDITOR, Jamie O'Neal, and Lou Ann Wilson for their suggestions and kindnesses. We would also like to acknowledge our many colleagues who have reviewed all, or part, of Environmental Science: A Study of Interrelationships. Their valuable input has continued to shape this text and help it meet the growing needs of instructors.