SCOPE 57 Particle Flux in the Ocean Edited by VENUGOPALAN ITTEKKOT PETRA SCHAFER SCOPEIUNEP International Carbon Unit Universitat Hamburg, Germany SUSUMU HON JO Woods Hole Oceanographic Institution Woods Hole, MA, USA PEDRO J. DEPETRIS Universidad National de Cordoba Cordoba, Republica Argentina Published on behalf of the Scientific Committee on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (ICSU), and the United Nations Environment Programme (UNEP) by JOHN WILEY & SONS Chichester New York Brisbane Toronto Singapore
Contents Foreword Hartmut Grassl Preface John W. B. Stewart Bibliography - Carbon Unit Contributors xv xvii xix xxi 1 Particle Flux in the Ocean: Introduction 1 V. Ittekkot 1.1 Background 1 1.2 Particle Flux and the Marine Carbon Cycle 2 1.3 Acknowledgments 6 1.4 References 6 2 Remote Sensing of Parameters Relevant to the Particle Flux in the Ocean Using Meteorological Satellites 7 P. Schliissel 2.1 Introduction 7 2.2 Meteorological Parameters Influencing the Environment of Phytoplankton Blooms 9 2.3 Quantities Driving the Vertical Exchange in the Upper Ocean 13 2.4 Parameters Relevant to Transport and Deposition of Lithogenic Particles 14 2.5 Future Perspectives 14 2.6 References 15 3 The Atmospheric Transport of Particles to the Ocean 19 J. M. Prospero 3.1 Introduction 19 3.2 Aerosol Distributions Over the Oceans 20 3.3 Mineral Dust 22 3.3.1 Introduction 22 3.3.2 North Africa and the North Atlantic 24 3.3.2.1 Concentrations and Seasonal Trends 24 3.3.2.2 Aerosol Chemical Properties 26 3.3.2.3 Relationship of Dust Transport to Rainfall in Africa 27 3.3.2.4 Meteorology of Long Range African Dust Transport 28
viii 3.3.3 Pacific Studies 29 3.3.4 Indian Ocean and the Arabian Sea 33 3.3.5 Summary 34 3.4 Mineral Particle Deposition to the Oceans 35 3.4.1 Source Strengths 35 3.4.2 Dust Deposition Rates 36 3.4.3 Comparison With Aeolian Deposition Rates 38 3.4.4 Long Range Dust Transport and Climate 39 3.4.4.1 Wind Erosion and Climate 39 3.4.4.2 The Role of Humans 40 3.4.4.3 Modeling Dust Generation and Transport 41 3.5 Effects of Aeolian Inputs to the Oceans 41 3.6 Conclusions 43 3.7 Acknowledgments 44 3.8 References 45 4 Riverine Transfer of Particulate Matter to Ocean Systems 53 P. J. Depetris 4.1 Introduction 53 4.2 Riverine Transport of Carbon and Minerals 54 4.3 Factors Controlling Sediment Yield 56 4.4 The Role of Exceptional Climatic Events 59 4.5 An Assessment of Sediment Inputs into the SW Atlantic: A Case Study 63 4.6 Concluding Remarks 66 4.7 References 66 5 Particle Flux in the Ocean: Oceanographic Tools 71 V. L. Asper 5.1 Introduction 71 5.2 Direct Flux Measurements 71 5.2.1 Hydrodynamic Bias 73 5.2.2 Swimmers 75 5.2.3 Remineralization/Decomposition of the Sample 76 5.3 Particle Abundances 77 5.3 Sinking Speeds 78 5.4 Summary 79 5.5 References 81 6 Evaluation of Sediment Traps with Naturally Occurring Radionuclides 85 M. P. Bacon 6.1 Introduction 85 6.2 Moored Sediment Traps in the Deep Ocean 85 6.3 Sediment Traps in the Upper Ocean 88 6.4 Conclusions 89
ix 6.5 Acknowledgments 90 6.6 References 90 7 Fluxes of Particles to the Interior of the Open Oceans 91 S. Honjo 7.1 Introduction 91 7.2 Ocean Particle Flux: Definition, Units and Attributes 94 7.3 Methods of Studying Ocean Particles 95 7.3.1 Sediment Traps 95 7.3.2 Time-Series Array and Synchronization 95 7.3.3 Constraints in Measuring Particle Fluxes with Sediment Traps 96 7.3.4 Sample Integrity 98 7.3.4.1 Swimmers 98 7.3.4.2 Microbial Growth and Degradation of Samples 98 7.3.5 In Situ Sediment Trap Intercomparison in the Deep Water Column 101 7.3.6 Self Calibration of Particle Fluxes by Radionuclides 102 7.4 Sample Sharing and Laboratory Analyses 103 7.5 What are Settling Particles? 105 7.5.1 Origin of Settling Particles 105 7.5.2 The Constituents of Settling Particles 107 7.5.2.1 The CaCCb Component 108 7.5.2.2 The SiCb Component 108 7.5.2.3 Organic Matter 108 7.5.2.4 The Lithogenic Component 109 7.6 Particle Removal Processes 112 7.6.1 Removal Processes of Primary Production by Particles 112 7.6.2 "Leaky" Belt Conveyor 112 7.6.3 Need for Ballast 114 7.6.4 Settling Particles vs. Suspended Particles 115 7.7 SettlingRates of Particles 117 7.7.1 Estimation of the Residence Time of Particles from Off-Setting Benchmarks 117 7.7.2 Settling Speed of Particles 118 7.7.3 Reverse Estimate of the Succession of an Upper Ocean Event 123 7.8 Mesoscale Eddies and Vertical Variability of Fluxes 125 7.9 Alteration of Settling Particles 126 7.9.1 Inorganic Carbon: CaCO 3 126 7.9.2 Organic Matter and Organic Carbon 127 7.9.3 Biogenic S1O2 130 7.9.4 Vertical Increase of Lithogenic Particle Fluxes 132 7.9.5 Particle Flux in the Interior of the Very Deep Ocean Trenches in the Pacific 132 7.10 Seasonal and Geographical Variability 133
x 7.10.1 Particle Fluxes in the Margin 133 7.10.2 Contrast Between and in the Global Basins 134 7.10.3 Seasonal and Interannual Variability of Particle Fluxes 135 7.10.4 North Atlantic and North Pacific 137 7.10.5 Pacific and Atlantic Southern Ocean 139 7.10.6 Equatorial Pacific 141 7.11 Summary and Conclusions 141 7.12 Outlook 143 7.13 Acknowledgments 144 7.14 References 145 8 Nitrogen and Carbon Isotopic Tracers of the Source and Transformation of Particles in the Deep Sea 155 M. A. Altabet 8.1 Introduction 155 8.2 Isotopic Fractionation During Biogeochemical Reactions 156 8.3 Source Effects - 15 N 158 8.4. Source Effects - 13 C 163 8.5 Transformation Effects - Surface Ocean 165 8.6 Transformation Effects - Water Column and Sediment Surface 167 8.7 The JGOFS North Atlantic Bloom Experiment - A Case Study 169 8.7.1 Near-Surface Time-Series Signals in 5 13 N and 8 13 C 169 8.7.2 Near-Surface Formation of Sinking Particles 173 8.7.3 Comparison of Near-Surface and 1000 m Isotopic Signals... 175 8.7.4 Modifications of the Large Particle Flux Below 1000 m 178 8.8 Summary and Recommendations for Further Research 179 8.9 References 180 9 Temporal Variability of Particle Flux in the Deep Sargasso Sea 185 W. G. Deuser 9.1 Introduction 185 9.2 The Annual Cycle 185 9.3 Other Periods 187 9.4 Episodic Events 192 9.5 What is Needed? 195 9.6 Acknowledgments 197 9.7 References 198 10 Seasonal and Interannual Particle Fluxes in the Eastern Equatorial Atlantic from 1989 to 1991: ITCZ Migrations and Upwelling 199 G. Fischer and G. Wefer 10.1 Introduction 199 10.2 Material and Methods 200 10.3 Oceanographic and Biological Setting 200 10.4 Ocean Currents 202 10.5 Results and Discussion 203
xi 10.5.1 Seasonality and Interannual Variability of Fluxes and Compositions 203 10.5.1.1 Northern Guinea Basin Sites (GBN) 203 10.5.1.2 Southern Guinea Basin Sites (GBS) 206 10.5.1.3 Annual Fluxes and Year-to-Variations 208 10.5.1.4 Comparison Between the Northern (GBN) and Southern Sites( GBS) 210 10.6 Summary and Conclusions 212 10.7 Acknowledgments 213 10.8 References 213 11 Preliminary Data on Particle Flux off the Sao Francisco River, Eastern Brazil 215 T.C. Jennerjahn, V. Ittekkot and C.E. V. Carvalho 11.1 Introduction 215 11.2 Materials and Methods 215 11.3 Results and Discussion 217 11.4 Acknowledgements 222 11.5 References 222 12 Organic Carbon Fluxes and Sediment Biogeochemistry on the French Mediterranean and Atlantic Margins 223 H. Etcheber, S. Heussner, O. Weber, A. Dinet, X. Durrieu de Madron, A. Monaco, R. Buscail andj.c. Miquel 12.1 Introduction 223 12.2 Sampling Sites and Strategy 223 12.2.1 Mediterranean Sites 224 12.2.2 Atlantic Sites 224 12.3 Results 226 12.3.1 Spatial Variations in Total Mass and Organic Carbon Fluxes 226 12.3.1.1 Mediterranean Sites 226 12.3.1.2 Atlantic Sites 226 12.3.2 Seasonal Variations in Total Mass and Organic Carbon Fluxes 228 12.3.2.1 Mediterranean Sites 228 12.3.2.2 Atlantic Sites 228 12.3.3 Biogeochemistry of Surficial Slope Sediments 231 12.4 Discussion 234 12.4.1 Importance of Dynamical Factors on the Transfer of Particles 234 12.4.2 Importance of Advection 235 12.4.3 Seasonal Variability 236 12.4.4 Benthic Response to Organic Particle Fluxes on Margins 237 12.4 Conclusions 238 12.5 References 239
xii 13 Abiotic and Biotic Forcing on Vertical Particle Flux in the Southern Ocean 243 U. V. Bathmann 13.1 The Scenarios 243 13.2 Winter 243 13.3 Spring. 244 13.4 Autumn 247 13.5 Conclusion 248 13.6 Acknowledgments 248 13.7 References 248 14 Processes Determining Seasonality and Interannual Variability of Settling Particle Fluxes to the Deep Arabian Sea 251 B. Haake, T. Rixen, T. Reemtsma, V. Ramaswamy and V. Ittekkot 14.1 Introduction 251 14.2 Study Area 251 14.3 Methods 252 14.4 Sample Analyses 253 14.5 Results and Discussion 254 14.5.1 Processes Determining Seasonalities of Biogenic and Lithogenic Fluxes 254 14.5.2 Sources and Decomposition of Organic Matter 261 14.5.3 Interannual Variations 266 14.5 Conclusions 267 14.6 Acknowledgments 268 14.7 References 268 15 Fresh Water Influx and Particle Flux Variability in the Bay of Bengal 271 P. Schdfer, V. Ittekkot, M. Bartsch, R. R. Nair andj. Tiemann 15.1 Introduction 271 15.2 Study Area 271 15.3 Methods 273 15.3.1 Sampling 273 15.3.2 Analyses 274 15.3.3 Wind Speed and Sea Surface Temperature 274 15.4 Total and Component Fluxes 274 15.4.1 Northern Bay of Bengal 274 15.4.2 Central Bay of Bengal 278 15.4.3 Southern Bay of Bengal 279 15.5 Interannual Variability 285 15.5.1 Seasonal Signals 285 15.5.2 Total and Component Fluxes 285 15.6 Comparison With Other Marine Regions 286 15.7 General Discussion 286
xiii 15.8 Conclusions 289 15.9 Acknowledgments 290 15.10 References 290 16 Fluxes of Paniculate Matter in the South China Sea 293 M. G. Wiesner, L. Zheng, H. K. Wong, Y. Wang and W. Chen 16.1 Introduction 293 16.2 Climate and Hydrography 294 16.3 Materials and Methods 295 16.4 Results 297 16.4.1 Northern South China Sea 297 16.4.2 Central South China Sea 299 16.5 Discussion 303 16.6 Conclusions 308 16.7 Acknowledgments 309 16.8 References 309 17 Vertical Particle Flux in the Western Pacific Below the North Equatorial Current and the Equatorial Counter Current 313 S. Kempe and H. Knaack 17.1 Introduction 313 17.2 Materials and Methods 313 17.3 Discussion of Results 314 17.4 Acknowledgments 323 17.5 References 323 18 Vertical Particle Flux in Lake Baikal 325 S. Kempe and M. Schaumburg 18.1 Introduction 325 18.2 Lake Baikal 326 18.3 Material and Methods 332 18.3.1 Sediment Trap Mooring 332 18.3.2 Analytical Methods 332 18.4 Discussion of Results 335 18.4.1 Dissolved Fraction and Remineralization 335 18.4.2 Paniculate Fraction... 339 18.4.3 Organic Matter 344 18.4.4 SEM Investigations 345 18.5 Conclusions 347 18.6 Acknowledgments 349 18.7 References 349 18.8 Appendix 351 19 Particle Flux in the Ocean: Summary 357 V. Ittekkot 19.1 Introduction 357
xiv 19.2 Particle Sources 358 19.3 Methods and Problems 358 19.4 Results from Experiments 359 19.5 Environmental Signals 361 19.6 Particle Flux and Carbon Storage in the Deep Sea 362 19.7 General Conclusions 363 19.8 References 365 Index 367