Chemical Biomarkers in Aquatic Ecosystems
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December 28, 2010 Time: 10:31am fm.tex Chemical Biomarkers in Aquatic Ecosystems i This page intentionally left blank December 28, 2010 Time: 10:31am fm.tex Chemical Biomarkers in Aquatic Ecosystems THOMAS S. BIANCHI AND ELIZABETH A. CANUEL PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD iii December 28, 2010 Time: 10:31am fm.tex Copyright c 2011 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TW press.princeton.edu All Rights Reserved Library of Congress Cataloging-in-Publication Data Bianchi, Thomas S. Chemical biomarkers in aquatic ecosystems/Thomas S. Bianchi and Elizabeth A. Canuel. p. cm. Includes bibliographical references and index. ISBN 978-0-691-13414-7 (cloth : alk. paper) 1. Aquatic ecology. 2. Biochemical markers. I. Canuel, Elizabeth A., 1959– II. Title. QH541.5.W3B53 2011 577.6—dc22 2010029921 British Library Cataloging-in-Publication Data is available This book has been composed in Sabon and Din Pro Printed on acid-free paper. ∞ Typeset by S R Nova Pvt Ltd, Bangalore, India Printed in the United States of America 10987654321 iv December 28, 2010 Time: 10:31am fm.tex We dedicate this book to our spouses, Jo Ann Bianchi and Emmett Duffy, and our children, Christopher Bianchi and Conor Duffy, for their unending support and patience, without which we could never have completed this book. v This page intentionally left blank December 28, 2010 Time: 10:31am fm.tex Several current characteristics of organic geochemical research serve to limit advances toward a deeper understanding of global biogeochemical cycles. For the most part, these problems are shared by all organic geochemists (author included), but are not unique to our guild. The first of these is that geochemical research is decidedly provincial. That is, functionally similar processes occurring in weathering rocks, soils, lakes, rivers and the ocean tend to be studied by different types of geochemists with dissimilar backgrounds, terminologies and methodologies. This geographic specialization has limited the scope of both our fieldwork and insight, and has resulted in lost research and interpretive opportunities. At present, there is insufficient information to obtain unique solutions at the global scale, even for bulk carbon. The main constraint is that meaningful rate constants for in situ degradation within key environment are not known. — John I. Hedges, 1992 vii This page intentionally left blank December 28, 2010 Time: 10:31am fm.tex Contents Preface xi Acknowledgments xix 1. Metabolic Synthesis 1 2. Chemical Biomarker Applications to Ecology and Paleoecology 19 3. Stable Isotopes and Radiocarbon 30 4. Analytical Chemical Methods and Instrumentation 49 5. Carbohydrates: Neutral and Minor Sugars 79 6. Proteins: Amino Acids and Amines 98 7. Nucleic Acids and Molecular Tools 127 8. Lipids: Fatty Acids 144 9. Isoprenoid Lipids: Steroids, Hopanoids, and Triterpenoids 169 10. Lipids: Hydrocarbons 185 11. Lipids: Alkenones, Polar Lipids, and Ether Lipids 207 12. Photosynthetic Pigments: Chlorophylls, Carotenoids, and Phycobilins 221 13. Lignins, Cutins, and Suberins 248 14. Anthropogenic Markers 267 Appendix I. Atomic Weights of Elements 287 Appendix II. Useful SI Units and Conversion Factors 291 Appendix III. Physical and Chemical Constants 293 Glossary 295 Bibliography 309 Index 385 This page intentionally left blank Preface Due to the complexity of organic matter sources in aquatic systems, the application of chemical biomarkers has become widespread in limnology and oceanography. We define biomarker molecules in this book as compounds that characterize certain biotic sources and selectively retain their source information, even after stages of decomposition and diagenesis (after Meyers, 2003). Hence, the term biomarker molecule should not be confused with the terms commonly used by ecotoxicologists or molecular biologists (see Timbrell, 1998; Wilson and Suk, 2002; Decaprio, 2006, and references therein). Early definitions of biological markers, or simply biomarkers or chemical biomarkers, described these compounds as molecular fossils derived from formerly living organisms (Eglinton et al., 1964; Eglinton and Calvin, 1967). More recently, biomarkers have been defined as complex organic compounds composed of carbon, hydrogen, and other elements, which occur in sediments, rocks, and crude oils, and show little to no change in their chemical structure from their precursor molecules that once existed in living organisms (Hunt et al., 1996; Peters et al., 2005; Gaines et al., 2009). Biomarkers have also been defined recently as lipid components found within bitumen in coal as well as kerogens that provide an unambiguous link to biological precursor compounds, because of their stability through diagenesis and catagenesis (Killops and Killops, 2005; Gaines et al., 2009). Additionally, the term geolipid has commonly been used to describe decay-resistant biomarkers in sediments because lipids are typically recalcitrant compared with other biochemical components of organic matter, making them more long- lived in the sedimentary record (Meyers, 1997). The first convincing linkage made between geolipids and living organisms was made by Treibs (1934), when a correlation was made between chlorophyll a in photosynthetic organisms and porphyrins in petroleum. This important discovery essentially marked the beginning of organic geochemistry. Chemical biomarkers have provided numerous insights about present and past aspects of Earth history, including (1) the food and energy sources available to microbes and higher organisms, (2) microbial chemotaxonomy, (3) sources of fossil fuels, and (4) the evolution of life on Earth. A greater knowledge of the biogeochemical cycling of organic matter, which involves the transformation, fate, and transport of chemical substances, is critical in understanding the effects of natural and human- induced environmental changes—from a regional and global context. Approaching aquatic sciences from a biogeochemical perspective requires a fundamental understanding in the biochemistry of organic matter. Our motivation for writing this book is that many of the books on chemical biomarkers are edited volumes, too diffuse and difficult to use as textbooks for advanced undergraduate and graduate courses. We also wanted to develop a book with examples of the applications of biomarkers to a range of aquatic environments, including riverine, estuarine, and oceanic ecosystems. December 28, 2010 Time: 10:31am fm.tex xii I Preface This book is designed for advanced undergraduate and graduate level classes in aquatic and marine biogeochemistry, organic geochemistry, and global ecosystem dynamics. Prerequisites for such a course may include introductory courses in inorganic and organic chemistry, oceanography and/or limnology, and environmental and/or ecosystem ecology. The book should also prove to be a valuable resource for researchers in limnological, estuarine, marine, and environmental sciences. The basic organization of the book is derived from classes we have taught in global biogeochemistry, organic geochemistry, and marine/estuarine biogeochemistry. It is structured around individual classes of biomarkers, with each chapter describing the structure and synthesis of each class of compounds, their reactivity, and examples of specific applications for each class of biomarkers. In chapter 1, we provide a general background on the synthesis of chemical biomarkers and their association with key metabolic pathways in organisms, as related to differences in cellular structure and function across the three domains of life. We discuss photosynthesis, the dominant pathway by which biomass is synthesized. Additionally, we present information about chemoautotrophic and microbial heterotrophic processes. The holistic view of biosynthetic pathways of chemical biomarkers here also provides a roadmap for other chapters in the book, where more specific details on chemical pathways are presented for each of the respective biomarker groups. While other organic geochemistry books have generally introduced the concepts of chemical biomarkers in the context of physical and chemical gradients found in natural ecosystems (e.g., anaerobic, aerobic), we begin by examining biosynthetic pathways at the cellular level of differentiation. Chapter 2 provides a brief historical account of the success and limitations of using chemical biomarkers in aquatic ecosystems. This chapter also introduces the general concepts of chemical biomarkers as they relate to global biogeochemical cycling. The application of chemical biomarkers in modern and/or ancient ecosystems is largely a function of the inherent structure and stability of the molecule, as well as the physicochemical environment of the system wherein it exists. In some cases, redox changes in sediments have allowed for greater preservation of biomarker compounds; in well- defined laminated sediments, for example, a strong case can be made for paleo-reconstruction of past organic matter composition sources. However, many of the labile chemical biomarkers may be lost or transformed within minutes to hours of being released from the cell from processes such as bacterial and/or metazoan grazing, cell lysis, and photochemical breakdown, just to name a few. The role of trophic effects versus large-scale physiochemical gradients in preserving or destroying the integrity of chemical