U-Th Series Nuclides in Aquatic Systems

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Dedication to Karl K. Turekian......Page 5
Contributors......Page 7
Overview......Page 9
Organization of the Volume......Page 12
Acknowledgements......Page 15
References......Page 16
U- and Th-Series Nuclides in the Atmosphere: Supply, Exchange, Scavenging, and Applications to Aquatic Processes......Page 19
Components of soil and volcanic dust......Page 20
Diffusion from soil and sea surface......Page 21
U, Th and Ra isotopes......Page 24
Radon-222......Page 26
Lead-210......Page 28
Lead-210 in conjunction with Be-7......Page 29
Steady state box model......Page 31
210Bi/210Pb- and 210Po/210Pb-based residence times......Page 32
Comparison of residence times tauR (Bi-Pb) and tauR (Po-Pb)......Page 33
Direct measurements......Page 35
Lead-210 flux from natural repositories......Page 37
Flux of 210Pb over the continents and oceans......Page 38
Accumulation in snow and ice......Page 39
Accumulation in marshes and bogs......Page 40
Mixing and particle scavenging in upper ocean water......Page 41
Deposition fluxes of atmospheric constituents......Page 42
Radon exchange models across the air-sea interface......Page 43
Evidence of 210Pb and 210Po volatility in air-sea processes......Page 44
Sources of excess 210Po in the marine atmosphere......Page 45
Perspectives and Future Directions......Page 47
References......Page 48
U-Series Geochemistry in Weathering Profiles, River Waters and Lakes......Page 56
Fractionation linked to chemical properties of radionuclides in solution......Page 57
Chemical speciation of radionuclides in solution......Page 58
Interactions with solids......Page 59
Reactions with colloids......Page 60
Fractionation due to radioactive decay......Page 61
Physics of recoil......Page 62
Kinetics of U-series nuclide exchange......Page 64
U-series disequilibria in weathering profiles......Page 66
Dating of soil minerals......Page 68
U Series in Rivers......Page 70
Diagnostic for steady-state erosion......Page 71
Time-scales and rates of chemical weathering......Page 72
Weathering fluxes......Page 76
Atmospheric and anthropogenic fluxes......Page 81
Adsorption processes......Page 82
Influence of speciation and colloids......Page 84
Review of Models for U-Series Fractionation in Surficial Environments......Page 88
Adsorption/desorption......Page 91
Recoil effects......Page 92
Lake water studies......Page 93
226Ra dating technique......Page 94
238U-234U-230Th dating methods......Page 95
Paleo-environmental reconstruction......Page 96
Future Perspectives......Page 97
References......Page 98
Investigating Groundwater Processes Using U- and Th-Series Nuclides......Page 112
Introduction......Page 113
Behavior of U in groundwater......Page 115
Behavior of Th in groundwater......Page 116
Behavior of Rn in groundwater......Page 118
Processes controlling nuclide distributions......Page 119
Adsorbed nuclides......Page 122
Distributions in host rock minerals......Page 123
Colloids......Page 124
Obtaining Solutions to the Model Equations......Page 125
Radionuclide concentrations along a flow line......Page 126
The 238U decay chain......Page 127
The 232Th decay chain......Page 131
Radon recoil......Page 132
Recoil rates of other nuclides......Page 135
Other Rn applications......Page 136
(224Ra/228Ra) ratios......Page 137
(226Ra/228Ra) ratios......Page 139
(223Ra/226Ra) ratios......Page 140
228Th and Th/Ra retardation factors......Page 141
234Th and sorption rate constants......Page 142
U Isotopes......Page 143
Measured U isotope compositions......Page 144
Interpreting U isotope compositions......Page 146
Preferential leaching of oxidized U......Page 147
Dating groundwater......Page 148
210Pb......Page 150
Summary of radionuclide behavior......Page 151
Future studies......Page 152
References......Page 154
Uranium- and Thorium-Series Nuclides as Tracers of Submarine Groundwater Discharge......Page 161
Introduction......Page 162
How U-Th Isotopes are Used to Quantify Submarine Groundwater Discharge (SGD)......Page 164
Applications to estimate SGD......Page 166
Applications for determination of water residence times......Page 170
Seasonality in SGD......Page 172
Processes controlling endmember Ra concentrations......Page 173
Applications to determine nutrient flux......Page 174
Applications to SGD......Page 177
Applications to short (tidal) time-scale variation in SGD......Page 180
Applications to mapping Rn distribution in the coastal ocean......Page 182
Processes controlling endmember 222Rn......Page 183
Impact of SGD on uranium cycling in the coastal ocean......Page 184
Uranium as a potential new tracer of SGD......Page 185
Synthesis of Existing Studies......Page 187
Towards a Global Estimate of SGD......Page 190
Acknowledgments......Page 191
References......Page 192
Introduction: Estuarine Processes......Page 198
Riverine and oceanic endmembers......Page 201
Dissolved uranium in river endmembers......Page 202
Particulate and colloidal uranium in river endmembers......Page 205
Dissolved uranium......Page 207
Removal of U in marshes and mangroves:......Page 209
Role of suboxic bottom sediments......Page 210
Implications for global uranium budgets......Page 213
Short-lived isotopes: 234Th and 228Th......Page 214
Estuarine behavior of Ra isotopes......Page 217
Radon......Page 220
Lead-210 and Polonium-210......Page 221
Future Studies......Page 222
References......Page 223
U- and Th-Series Nuclides as Tracers of Particle Dynamics, Scavenging and Biogeochemical Cycles in the Oceans......Page 231
Protactinium......Page 232
Actinium......Page 234
Radon......Page 235
Introduction to Particle Cycling and Scavenging in the Ocean......Page 236
The Scavenging Process as Understood from Thorium Isotopes......Page 241
Scavenging and Th Speciation......Page 244
226Ra-210Pb-210Po......Page 246
The Role of Particle Composition......Page 248
230Th/231Pa......Page 249
210Po/210Pb......Page 252
Boundary Scavenging......Page 253
Basis......Page 255
Surface waters......Page 256
Deep waters......Page 258
Summary and Outlook......Page 262
References......Page 264
Introduction......Page 273
Radionuclides of Interest and their Bioavailability......Page 274
Models of Uptake and Trophic Transfer......Page 285
Biodetritus and Vertical Transport......Page 287
Potential Impacts of Natural Radioactivity......Page 294
Synthesis and Conclusions......Page 299
Future Outlook and Perspectives......Page 300
References......Page 303
Introduction......Page 310
Conservation of mass: The continuity equation......Page 312
Parameterization of ocean mixing processes......Page 313
‘‘Jc’’ for the decay-series isotope tracers......Page 315
One-dimensional diffusion model......Page 316
One-dimensional diffusion-advection model......Page 317
Two-dimensional diffusion-advection model......Page 318
Radium Isotopes for Tracing Oceanic Mixing/Circulation......Page 319
Radium-226 as a large-scale oceanic mixing tracer......Page 320
Radium-228 as an oceanic tracer......Page 326
Horizontal mixing away from the shelf......Page 327
Mixing in nearshore basins......Page 328
Thermocline......Page 329
Deep ocean......Page 330
Tracing coastal mixing with 224Ra and 223Ra......Page 331
Radon-222 as a Vertical Mixing Tracer in the Deep Sea......Page 332
Actinium-227 as a Diapycnal Mixing Tracer in the Deep Sea......Page 335
Tracing Ocean Circulation Using Particle-Reactive Radionuclides......Page 337
Closing Remarks and Future Prospects......Page 340
References......Page 341
Introduction......Page 348
Modeling U- and Th-series radionuclides in marine groundwaters......Page 349
U- and Th-Series Radionuclides in High-Temperature Marine Groundwaters: Hydrothermal Fluids......Page 352
Fluid crustal residence time......Page 354
210Pb/Pb ratio and the crustal residence time of hydrothermal fluids......Page 355
Dating of hydrothermal deposits......Page 357
228Th/228Ra method......Page 358
Radon-222 as a tracer of subsurface processes......Page 360
U- and Th-Series Radionuclides in Low-Temperature Marine Groundwaters: Sediment Pore Water......Page 361
Deep-sea sediments......Page 362
Estuarine sediments......Page 368
Uranium in sediment pore water......Page 372
The oceanic U balance......Page 376
Future Directions......Page 377
References......Page 378
Introduction......Page 386
Long-Lived U-Series Nuclides in Sediments......Page 387
Short-Lived U-Series Nuclides in Sediments: Application to Sediment Mixing and Accumulation......Page 389
Authigenic Uranium as a Tracer of Sediment Redox State......Page 391
Use of 230Th as a Constant Flux Proxy......Page 393
Applications of 230Th-normalization......Page 396
The equatorial Pacific: Are the assumptions of the 230Th method violated here?......Page 398
231Pa/230Th: Proxy for Particle Flux and Productivity......Page 400
Proxy evaluation using sediment traps......Page 402
Applications of the Pa/Th flux proxy......Page 407
231Pa/230Th: Proxy of Ocean Circulation......Page 408
Modeling Studies......Page 409
Manganese Crusts and Nodules......Page 411
Summary and Outlook......Page 412
References......Page 413
Introduction......Page 420
Sources of Data......Page 421
References......Page 426
Overview of Decay Equations......Page 427
Rates of sediment accumulation or authigenic deposit formation......Page 430
Ages of fossil corals......Page 431
References......Page 432
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