The processes occurring in surface marine sediments have a profound effect on the local and global cycling of many elements. This graduate text presents the fundamentals of marine sediment geochemistry by examining the complex chemical, biological, and physical processes that contribute to the conversion of these sediments to rock, a process known as early diagenesis. Research over the past three decades has uncovered the fact that the oxidation of organic matter deposited in sediment acts as a causative agent for many early diagenetic changes. Summarizing and discussing these findings and providing a much-needed update to Robert Berner's Early Diagenesis: A Theoretical Approach, David J. Burdige describes the ways to quantify geochemical processes in marine sediment. By doing so, he offers a deeper understanding of the cycling of elements such as carbon, nitrogen, and phosphorus, along with important metals such as iron and manganese. No other book presents such an in-depth look at marine sediment geochemistry. Including the most up-to-date research, a complete survey of the subject, explanatory text, and the most recent mathematical formulations that have contributed to our greater understanding of early diagenesis, Geochemistry of Marine Sediments will interest graduate students of geology, geochemistry, and oceanography, as well as the broader community of earth scientists. It is poised to become the standard text on the subject for years to come. TABLE OF CONTENTS: Preface xv Common Abbreviations and Symbols xvii CHAPTER ONE: Introduction 1 CHAPTER TWO: The Components of Marine Sediments 5 2.1 Detrital Components 5 2.2 Biogenic Components 8 2.2.1 Biogenic Carbonates 9 2.2.2 Biogenic Silica 10 2.2.3 Distribution of Biogenic Components in Marine Sediments 10 2.3 Authigenic Minerals 12 2.3.1 Nonbiogenic Carbonates 13 2.3.2 Mn Crusts, Layers, and Nodules 13 2.3.3 Phosphorites 14 2.3.4 Sulfides 15 2.4 Clays and Clay Minerals 15 2.4.1 Distribution of Clay Minerals in Surface Marine Sediments 18 2.4.2 Ion Exchange/Adsorption 20 2.5 The Classification of Marine Sediments and Sedimentary Regimes 24 CHAPTER THREE: Isotope Geochemistry 27 3.1 Introduction 27 3.2 Principles of Isotope Fractionation 28 3.2.1 Terminology 30 3.2.2 Equilibrium Isotope Exchange Reactions 31 3.3 Isotope Fractionation in Inorganic Materials in Nature 32 3.3.1 Isotope Fractionation in the Hydrosphere and in Ice Cores 32 3.3.2 Isotope Fractionation during Clay Mineral Formation 34 3.3.3 Oxygen and Carbon Isotopes in Calcite 35 3.4 Carbon Isotopes in Organic Matter 36 3.4.1 Photosynthesis 37 3.4.2 Respiration (Early Diagenesis in Sediments) 38 3.5 Oxygen and Carbon Isotopes in Sediment Pore-Waters 38 3.5.1 Carbon Isotopes 38 3.5.2 Oxygen Isotopes 39 3.6 Nitrogen Isotopes 39 3.7 Sulfur Isotopes 40 3.8 Radioactive Isotopes 40 3.8.1 Basic Principles 40 3.8.2 Radiocarbon 43 CHAPTER FOUR: Physical Properties of Sediments 46 4.1 Grain Size 46 4.2 Porosity and Sediment Density 47 4.3 Permeability 55 CHAPTER FIVE: An Introduction to Transport Processes in Sediments 59 5.1 Diffusion 59 5.2 Sediment Accumulation, Steady State,and the Frame of Reference for Processes in Marine Sediments 61 5.3 An Introduction to Bioturbation and Bioirrigation 65 5.4 Time and Space Scales of Sediment Processes 67 5.5 The Classification of Marine Sediments on the Basis of Their Functional Diagenetic Characteristics 70 CHAPTER SIX: Models of Sediment Diagenesis 72 6.1 The General Diagenetic Equation 72 6.1.1 Diffusion 74 6.1.2 Advection, Sediment Compaction, and Bioturbation 78 6.1.3 Adsorption 83 6.2 Solutions to the Diagenetic Equation 84 6.2.1 Boundary Conditions 86 6.3 Solutions to Specific Diagenetic Equations 87 6.3.1 Organic Matter Remineralization without Bioturbation 88 6.3.2 Organic Matter Remineralization with Bioturbation 89 6.3.3 Organic Matter Remineralization Coupled to Sulfate Reduction 91 6.3.4 Ammonium Production in Anoxic Sediments 92 6.3.5 Determination of Sediment Accumulation Rates 95 CHAPTER SEVEN Biogeochemical Processes in Sediments 97 7.1 Bacterial Metabolism: General Considerations 98 7.2 Bacterial Respiration and Biogeochemical Zonation in Sediments 99 7.3 Bacterial Respiration: Specific Processes 105 7.3.1 Aerobic Respiration 105 7.3.2 Denitrification 105 7.3.3 Manganese and Iron Reduction 107 7.3.4 Sulfate Reduction 110 7.3.5 Methanogenesis 111 7.4 Chemolithotrophic Reactions 114 7.4.1 Aerobic Processes 114 7.4.2 Anaerobic Processes 116 7.4.3 Linkages between Chemolithotrophic and Organic Matter Remineralization Processes 116 7.5 The Distribution of Organic Matter Remineralization Processes in Marine Sediments 120 7.5.1 Depth Scales of Biogeochemical Zonation 120 7.5.2 General Trends with Water Column Depth or Sediment Type 124 7.6 Dynamics of Organic Matter Decomposition in Sediments 134 7.6.1 General Considerations 134 7.6.2 Anaerobic "Foodchains" 135 7.6.3 Dynamics of Organic Matter Decomposition under Mixed Redox Conditions 139 CHAPTER EIGHT: Quantifying Carbon and Nutrient Remineralization in Sediments 142 8.1 Models of Organic Matter Decomposition in Sediments 142 8.2 Sediment Budgets for Reactive Components 150 8.2.1 Theoretical Considerations 151 8.2.2 Sediment Nutrient Budgets Using Cape Lookout Bight as an Example 153 8.3 Carbon Burial in Sediments 161 8.4 Layered and Coupled Models of Sediment Diagenesis 162 CHAPTER NINE: An Introduction to the Organic Geochemistry of Marine Sediments 171 9.1 General Considerations 172 9.2 Concentrations and Sources of Organic Matter in Marine Sediments 174 9.3 The Bulk Chemical Composition of Marine Sediment Organic Matter 175 9.4 Amino Acids 179 9.5 Carbohydrates 189 9.6 Lignins 193 9.7 Lipids 194 9.8 Humic Substances and Molecularly Uncharacterized Organic Matter 204 9.8.1 Black Carbon 206 9.8.2 Molecularly Uncharacterized Organic Matter (MU-OM): General Considerations 207 9.8.3 Geopolymerization: The Formation of Humic Substances 209 9.8.4 Selective Preservation of Refractory Biomacromolecules 212 9.8.5 Physical Protection 213 9.9 Organic Nitrogen Diagenesis in Sediments 215 CHAPTER TEN: Dissolved Organic Matter in Marine Sediments 218 10.1 General Observations 218 10.2 Diagenetic Models of Pore-Water DOM Cycling in Sediments 227 10.3 Pore-Water DOM Compositional Data 228 10.3.1 Short-Chain Organic Acids 230 10.3.2 Carbohydrates 231 10.3.3 Amino Acids 231 10.4 Fluxes of DOM from Marine Sediments 232 10.5 DOM Adsorption and Sediment-Organic Matter Interactions 234 CHAPTER ELEVEN: Linking Sediment Organic Geochemistry and Sediment Diagenesis 237 11.1 The Sources of Organic Matter to Marine Sediments 237 11.1.1 Carbon and Nitrogen Isotopic Tracers of Organic Matter Sources 238 11.1.2 Elemental Ratios as Tracers of Organic Matter Sources 241 11.1.3 Spatial Trends in the Sources of Organic Matter to Marine Sediments:Marine versus Terrestrial 244 11.1.4 Other Sources of Organic Matter to Marine Sediments: Black Carbon and Recycled Kerogen 249 11.1.5 Production of Bacterial Biomass in Sediments 250 11.2 The Composition of Organic Matter Undergoing Remineralization in Marine Sediments 253 11.2.1 Pore-Water Stoichiometric Models for Nutrient Regeneration/Organic Mater Remineralization 254 11.2.2 Benthic Flux and Sediment POM Stoichiometric Models for Nutrient Regeneration 260 11.2.3 The Composition of Organic Matter Undergoing Remineralization: Elemental Ratios and Stable Isotopic Composition 261 11.2.4 The Composition of Organic Matter Undergoing Remineralization: Organic Geochemical Composition 265 CHAPTER TWELVE: Processes at the Sediment-Water Interface 271 12.1 The Determination of Benthic Fluxes 272 12.2 Diffusive Transportand the Benthic Boundary Layer 274 12.3 Sediment-Water Exchange Processes in Permeable Sediments 283 12.4 Bioturbation 286 12.4.1 General Considerations 286 12.4.2 Models of Bioturbation 289 12.4.3 Nonlocal Sediment Mixing 299 12.5 Bioirrigation 302 12.5.1 The Diffusive Openness of Bioirrigated Sediments 313 12.5.2 Methods for Quantifying Bioirrigation in Sediments 316 12.5.3 Rates of Bioirrigation in Marine Sediments 319 12.6 Other Sediment-Water Interface Processes: Methane Gas Ebullition 326 CHAPTER THIRTEEN: Biogeochemical Processes in Pelagic (Deep-Sea) Sediments 328 13.1 Organic Matter Remineralization 328 13.2 Trace Metal Diagenesis 332 13.3 Manganese Nodules and Crusts 344 13.4 Diagenesis of Opaline Silica 352 13.5 Diagenesis of Calcium Carbonate 359 CHAPTER FOURTEEN: Nonsteady-State Processes in Marine Sediments 373 14.1 General Considerations 373 14.2 Periodic Input Processes 374 14.3 Seasonality in Sediment Processes 378 14.4 Diagenetic Processes in Deep-Sea Turbidites 382 14.4.1 Organic Geochemical Studies of Turbidite Diagenesis 391 14.5 Multiple Mn Peaks in Sediments: Nonsteady-State Diagenetic Processes Associated with Paleoceanographic Changes 395 14.5.1 Multiple Mn Peaks and the Glacial-Holocene Transition 400 14.5.2 Multiple Mn Peaks and Pleistocene Climate Cycles 402 14.5.3 Multiple Mn Peaks in Holocene Sediments 404 CHAPTER FIFTEEN: The Controls on Organic Carbon Preservation in Marine Sediments 408 15.1 Organic Matter-Mineral Interactions 412 15.2 The Role of Oxygen in Sediment Carbon Remineralization and Preservation 417 15.3 The Role of Benthic Macrofaunal Processes in Sediment Carbon Remineralization and Preservation 419 15.4 Oxygen Exposure Time as a Determinant of Organic Carbon Preservation in Sediments 421 15.4.1 What Exactly Does Sediment Oxygen Exposure "Mean"? 425 15.4.2 Organic Carbon Burial and Controls on Atmospheric O2 428 15.5 The Composition of Organic Matter Preserved in Marine Sediments and the Fate of Terrestrial Organic Matter in Marine Sediments 432 15.6 The Relationship between Physical Protection, Oxygen Exposure,and Possible Abiotic Condensation Reactions in Sediment Carbon Preservation 439 CHAPTER SIXTEEN: Biogeochemical Processes in Continental Margin Sediments. I. The CO2 System and Nitrogen and Phosphorus Cycling 442 16.1 Pore-Water pH and Carbonate Chemistry under Suboxic and Anoxic Conditions 442 16.2 Sediment Nitrogen Cycling 452 16.2.1 Benthic DON Fluxes 463 16.3 Sediment Phosphorus Cycling 464 16.3.1 Formation of Authigenic CFA and Phosphorus Burial in Sediments 474 CHAPTER SEVENTEEN: Biogeochemical Processes in Continental Margin Sediments. II. Sulfur, Methane, and Trace Metal Cycling 478 17.1 Sediment Sulfur Cycling 478 17.1.1 Sulfur Burial Efficiency 486 17.1.2 Long-Term Changes in the Sedimentary Sulfur Cycle 489 17.2 Methanogenesis and Anaerobic Methane Oxidation 490 17.2.1 Shallow (Coastal) Sediments 490 17.2.2 Continental Margin Sediments 493 17.3 Trace Metal Cycling 500 CHAPTER EIGHTEEN: Linking Sediment Processes to Global Elemental Cycles: Authigenic Clay Mineral Formation and Reverse Weathering 509 18.1 Sediment Silica Budgets 514 18.2 Final Thoughts 515 Appendix Some of the Field Sites Discussed in the Text 517 References 521 Index 593