1  Cover

      2  Title Page

      3  Copyright Page

      4  LIST OF CONTRIBUTORS

      5  PREFACE

      6  Biome I: Continental Margins 1 Biogeochemistry of Marine Oxygen Minimum Zones with Special Emphasis on the Northern Indian Ocean 1.1. INTRODUCTION 1.2. PRESERVATION OF ORGANIC MATTER AND SEDIMENT BIOGEOCHEMISTRY 1.3. PORE FLUID GEOCHEMISTRY 1.4. SEDIMENTARY SULFIDIZATION AND SULFURIZATION 1.5. BENTHIC BIOLOGY 1.6. MICROBIAL METABOLISM IN THE MARINE OXYGEN MINIMUM ZONE WATER COLUMN AND SEDIMENT 1.7. NITROGEN METABOLISM IN THE MARINE MARINE OXYGEN MINIMUM ZONE WATER COLUMN 1.8. MICROBIOLOGICAL PERSPECTIVE OF SULFUR METABOLISM IN THE MARINE OXYGEN MINIMUM ZONE WATER COLUMN 1.9. MICROBIOLOGY OF METHANE CYCLING IN THE OXYGEN MINIMUM ZONE WATER COLUMN 1.10. MICROBIAL METABOLISM IN MARINE OXYGEN MINIMUM ZONE SEDIMENTS 1.11. OXYGEN MINIMUM ZONE EXPANSION 1.12. CONCLUSION ACKNOWLEDGMENT REFERENCES 2 Sedimentary Records of Present and Past Marine Sulfur Cycling 2.1. INTRODUCTION 2.2. STABLE SULFUR ISOTOPES – A TOOL FOR RECONSTRUCTING SPATIAL AND TEMPORAL CHANGES IN SULFUR CYCLING 2.3. THE MODERN MARINE REALM 2.4. OCEANIC SULFATE AND ITS EVOLUTION THROUGH TIME 2.5. PYRITE AND ORGANIC‐BOUND SULFUR AS RECORDERS OF MICROBIAL SULFUR CYCLING IN THE PAST 2.6. MASS‐INDEPENDENTLY FRACTIONATED SULFUR ISOTOPES – A RECORD OF EARTH’S OXYGENATION 2.7. SUMMARY AND DIRECTION OF FUTURE RESEARCH ACKNOWLEDGMENTS REFERENCES 3 The Role of Microorganisms in Iron Reduction in Marine Sediments 3.1. INTRODUCTION 3.2. THE REDOX ZONES IN SHALLOW MARINE SEDIMENTS 3.3. BIOCHEMICAL PATHWAYS OF IRON REDUCTION 3.4. DIVERSITY OF POTENTIAL IRON‐REDUCING AND IRON‐OXIDIZING ORGANISMS 3.5. SUMMARY AND CONCLUSIONS REFERENCES 4 Biogeochemistry of Nitrogen in the Marine System with Special Emphasis on the Arabian Sea and Bay of Bengal 4.1. INTRODUCTION 4.2. SOURCES OF NITROGEN FOR THE OCEAN 4.3. MARINE NITROGEN BIOGEOCHEMISTRY 4.4. N‐CYCLE IN MARINE SEDIMENTS 4.5. NITROGEN CYCLING IN THE NORTHERN INDIAN OCEAN 4.6. NITROGEN ISOTOPIC VALUES IN SINKING PARTICULATES 4.7. SUMMARY ACKNOWLEDGEMENT REFERENCES 5 Organic Carbon in Sediments of the Western Indian Margin 5.1. INTRODUCTION 5.2. ORGANIC MATTER AND ORGANIC CARBON 5.3. ORGANIC CARBON DISTRIBUTION IN THE WORLD OCEAN AND THE ARABIAN SEA 5.4. METHODS ADOPTED TO DETERMINE OC IN THE ARABIAN SEA 5.5. PROCESSES RESPONSIBLE FOR PRIMARY PRODUCTIVITY AND TRANSPORT OF ORGANIC CARBON 5.6. OXYGEN MINIMUM ZONE AND ORGANIC CARBON 5.7. STUDIES CARRIED OUT ON ORGANIC CARBON FROM THE WESTERN MARGIN OF INDIA 5.8. SUMMARY AND FUTURE WORK ACKNOWLEDGEMENT REFERENCES

      7  Biome II: Ocean Depths 6 Deep Subsurface Microbiomes of the Marine Realm 6.1. INTRODUCTION 6.2. ECOSYSTEM CONSTRAINTS IN THE MARINE DEEP SUBSURFACE 6.3. FACTORS CONSTRAINING THE STUDY OF MARINE DEEP SUBSURFACES 6.4. BIOGEOCHEMISTRY OF MARINE DEEP SUBSURFACES 6.5. SUMMING UP THE GEOMICROBIOLOGY OF THE MARINE DEEP