Chemical Oceanography and the Marine Carbon Cycle

Cover......Page 1
Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Preface......Page 11
Acknowledgements......Page 12
I Introduction to chemical oceanography......Page 15
1.1 A chemical perspective......Page 17
1.2 Constituents of seawater......Page 19
1.2.1 The salinity of seawater......Page 20
1.2.2 Element classification......Page 24
Conservative elements......Page 26
Bioactive elements......Page 27
Gases......Page 30
1.3.1 Wind-driven circulation......Page 31
1.3.2 Thermohaline circulation......Page 35
1.4 Ocean biology......Page 38
Bacteria......Page 39
Phytoplankton......Page 40
1.4.2 Marine metabolism: estimates of abundance and fluxes......Page 42
References......Page 45
2 Geochemical mass balance: dissolved chemical inflow and outflow from the ocean......Page 47
2.1.1 Weathering and river fluxes to the ocean......Page 48
2.1.2 Residence times of seawater constituents......Page 50
2.1.3 Mackenzie and Garrels mass balance......Page 53
2.2 Reverse weathering......Page 57
2.3 Hydrothermal circulation......Page 60
2.3.1 The chemistry of hydrothermal waters......Page 61
Geochemical mass balance......Page 64
Heat flow and seawater convection at hydrothermal regions......Page 65
Hydrothermal water fluxes......Page 68
2.3.3 Estimates of water chemistry changes on the ridge flanks......Page 69
2.4 Summary and conclusions......Page 71
Igneous rocks......Page 72
Appendix 2.2 The meaning of residence time......Page 73
References......Page 75
3 Thermodynamics background......Page 77
3.1.1 The structure of water......Page 78
3.1.2 Water–ion interactions......Page 82
3.2.1 Activity–ionic strength relations......Page 84
3.2.2 The mean salt method......Page 85
3.3 Thermodynamic basics......Page 87
3.3.1 Free energy change during reaction......Page 88
3.3.2 Thermodynamic equilibrium......Page 89
3.4.1 Speciation of ions in seawater......Page 91
3.4.2 Equilibrium among coexisting phases: the phase rule......Page 95
3.4.3 Solid–solution equilibrium: CaCO3......Page 96
3.4.4 Solid–solution adsorption reactions......Page 97
3.4.5 Gas equilibrium between the air and water......Page 99
3.5.1 The standard electrode potential,…......Page 103
3.5.2 Environmental redox reactions......Page 108
References......Page 113
4 Carbonate Chemistry......Page 115
4.1 Acids and bases in seawater......Page 117
Carbonic acid......Page 118
Boric acid......Page 122
4.1.2 The alkalinity of seawater......Page 123
4.2 Carbonate equilibria: calculating the pH of seawater......Page 126
4.3 Kinetics of CO2 reactions in seawater......Page 130
4.4.1 Global ocean, atmosphere, and terrestrial processes......Page 132
4.4.2 Alkalinity changes within the ocean......Page 133
(a) Using carbonate alkalinity, AC......Page 141
(c) Using the total alkalinity,… but without the acids HSO…, HF, H3PO4 and H…......Page 142
4A1.2......Page 143
(a) The Henry’s Law constant for CO2 in seawater (mol kg…atm…), Eq. (4.14)......Page 144
4A2.2 The pressure dependence (from Millero, 1995)......Page 145
References......Page 146
5 Stable and radioactive isotopes......Page 148
5.1.1 Measuring stable isotopic abundances......Page 151
5.1.2 Equilibrium isotope effects......Page 154
5.1.3 Kinetic isotope effects......Page 159
5.1.4 Rayleigh distillation......Page 164
5.2.1 Radioactive decay processes......Page 167
5.2.2 Radioactive decay equations......Page 168
5.2.3 Radiochemical sources and distributions: carbon-14......Page 172
5.2.4 Radiochemical sources and distributions: uranium decay series......Page 177
Appendix 5.1 Relating K, Alpha, Delta  and Epsioln in stable isotope terminology......Page 183
Appendix 5.2 Derivation of the Rayleigh distillation equation......Page 184
References......Page 185
6 Life processes in the ocean......Page 187
6.1 A simple model of ocean circulation and biological processes......Page 188
6.2.1 Photosynthesis......Page 193
6.2.2 Respiration in the upper ocean......Page 200
6.3 Biologically driven export from the euphotic zone......Page 202
6.3.1 Particle flux......Page 203
6.3.2 The Th method of determining particle fluxes......Page 207
6.3.3 Dissolved O2 mass balance......Page 209
6.3.4 Carbon isotopes of dissolved inorganic carbon in surface waters......Page 213
6.3.5 Comparison of methods for determining organic carbon export......Page 216
6.4 Respiration below the euphotic zone......Page 217
6.4.1 Apparent oxygen utilization (AOU) and preformed nutrients......Page 219
6.4.2 Oxygen utilization rate (OUR)......Page 224
6.4.3 Aphotic zone respiration summary......Page 236
References......Page 237
7 Paleoceanography and paleoclimatology......Page 241
7.1 The marine sedimentary record: 0–800 ky......Page 242
7.1.1 Ice volume and temperature change during the Pleistocene......Page 243
7.1.2 Dating the marine sedimentary archives......Page 247
7.1.3 Changes in ocean chemistry......Page 257
7.2.1 Glacial–interglacial changes in atmospheric chemistry......Page 265
7.2.2 Correlating atmosphere and ocean changes......Page 268
7.3 Abrupt (millennial-scale) climate change......Page 271
References......Page 278
II Advanced topics in marine geochemistry......Page 281
8 Marine organic geochemistry......Page 283
8.1 The nature of organic matter......Page 286
8.2 Methods of characterizing organic matter......Page 288
Elemental composition......Page 290
Isotopic composition......Page 292
Spectroscopic methods......Page 294
Chromatographic methods......Page 296
Mass-based characterizations......Page 297
8.3 Major organic carbon compounds as biomarkers......Page 299
8.3.1 Amino acids......Page 300
8.3.2 Carbohydrates......Page 302
8.3.3 Lipids......Page 304
Hydrocarbons......Page 305
Fatty acids, fats and waxes......Page 307
Alkenones......Page 309
8.3.4 Pigments......Page 310
8.3.5 Lignin and tannins......Page 312
8.4 Dissolved organic matter in seawater......Page 316
References......Page 321
9 Molecular diffusion and reaction rates......Page 325
9.1.1 The diffusion equation......Page 326
9.1.2 Molecular diffusion coefficients in water......Page 330
9.2.1 Reaction mechanisms and reaction order......Page 332
9.2.2 Mineral–water reaction......Page 337
9.2.3 Characteristic life time......Page 341
9.2.4 The temperature dependence of reaction rates......Page 344
9.3 Reaction rate catalysis......Page 348
9.3.1 The mechanism of reaction rate catalysis......Page 349
9.3.3 Heterogeneous catalysis......Page 352
9.3.4 Enzyme catalysis......Page 356
References......Page 359
10 Gases and air–water exchange......Page 362
10.1 Air–sea gas transfer models......Page 365
10.1.1 Rigid wall model......Page 367
10.1.2 Stagnant film model......Page 368
10.1.3 Surface renewal model......Page 369
10.2 Measurements of gas exchange rates in nature......Page 372
10.2.1 The radiocarbon method......Page 373
10.2.2 The Rn method......Page 375
10.2.3 Tracer release experiments......Page 378
10.3 Gas saturation in the oceans......Page 379
10.3.1 Bubble processes......Page 381
10.3.2 Inert gas saturation in the ocean......Page 386
10.4.1 The effect of surfactants on air–sea transfer......Page 388
10.4.2 The effect of chemical reactions on the gas exchange rate of CO2......Page 389
References......Page 391
11 The global carbon cycle: interactions between the atmosphere and ocean......Page 394
11.1 The global carbon cycle......Page 395
11.2 The biological and solubility pumps of the ocean......Page 398
11.2.1 The solubility pump......Page 401
11.2.2 The biological pump......Page 403
11.3 The fate of anthropogenic CO2 in the ocean......Page 406
11.3.1 The carbonate buffer factor (Revelle factor)......Page 408
11.3.2 Methods of measuring anthropogenic CO2 uptake......Page 415
11.3.3 Partitioning anthropogenic CO2 among the ocean, atmosphere, and terrestrial reservoirs......Page 420
References......Page 424
12 Chemical reactions in marine sediments......Page 426
12.1.1 Pillars of organic matter diagenesis......Page 428
12.1.2 Organic matter diagenesis down the redox progression......Page 433
12.1.4 Factors controlling organic matter degradation......Page 437
12.2 Diagenesis and preservation of calcium carbonate......Page 441
12.2.1 Mechanisms of CaCO dissolution and burial: thermodynamics......Page 442
12.2.2 Mechanisms of CaCO dissolution and burial: kinetics......Page 446
12.3 Diagenesis and preservation of silica......Page 450
12.3.1 Controls on the H4SiO4 concentration in sediment porewaters: thermodynamics......Page 451
12.3.2 Controls on H4SiO4 concentration in sediment porewaters: kinetics......Page 452
12.3.3 The importance of aluminum and the rebirth of ‘‘reverse weathering’’......Page 453
12.4 Diagenesis and preservation of metals......Page 455
12.4.1 Oxic diagenesis......Page 456
12.4.2 Sediment anaerobic processes: oxic bottom water......Page 457
12.4.3 Sediment anaerobic processes: anoxic bottom water......Page 459
12.5 Conclusions......Page 461
References......Page 462
Index......Page 467