Preface ................................................. page xiii
Preface to first edition ....................................... xv
A note about software ......................................... xix
1 Introduction ................................................. 1
1.1 Development of chemical modeling ........................ 2
1.2 Scope of this book ...................................... 5
2 Modeling overview ............................................ 7
2.1 Conceptual models ....................................... 7
2.2 Configurations of reaction models ...................... 12
2.3 Uncertainty in geochemical modeling .................... 22
Part I Equilibrium in natural waters ........................... 27
3 The equilibrium state ....................................... 29
3.1 Thermodynamic description of equilibrium ............... 30
3.2 Choice of basis ........................................ 36
3.3 Governing equations .................................... 38
3.4 Number of variables and the phase rule ................. 50
4 Solving for the equilibrium state ........................... 53
4.1 Governing equations .................................... 53
4.2 Solving nonlinear equations ............................ 55
4.3 Solving the governing equations ........................ 60
4.4 Finding the stable phase assemblage .................... 67
5 Changing the basis .......................................... 71
5.1 Determining the transformation matrix .................. 72
5.2 Rewriting reactions .................................... 75
5.3 Altering equilibrium constants ......................... 76
5.4 Reexpressing bulk composition .......................... 77
6 Equilibrium models of natural waters ........................ 81
6.1 Chemical model of seawater ............................. 82
6.2 Amazon River water ..................................... 93
6.3 Red Sea brine .......................................... 97
7 Redox disequilibrium ....................................... 103
7.1 Redox potentials in natural waters .................... 103
7.2 Redox coupling ........................................ 105
7.3 Morro do Ferro groundwater ............................ 107
7.4 Energy available for microbial respiration ............ 110
8 Activity coefficients ...................................... 115
8.1 Debye-Hiickel methods ................................. 117
8.2 Virial methods ........................................ 123
8.3 Comparison of the methods ............................. 127
8.4 Brine deposit at Sebkhat El Melah ..................... 133
9 Sorption and ion exchange .................................. 137
9.1 Distribution coefficient (Kd) approach ................ 137
9.2 Freundlich isotherms .................................. 140
9.3 Langmuir isotherms .................................... 141
9.4 Ion exchange .......................................... 143
9.5 Numerical solution .................................... 146
9.6 Example calculations .................................. 150
10 Surface complexation ....................................... 155
10.1 Complexation reactions ................................ 156
10.2 Governing equations ................................... 160
10.3 Numerical solution .................................... 161
10.4 Example calculation ................................... 164
11 Automatic reaction balancing ............................... 169
11.1 Calculation procedure ................................. 169
11.2 Dissolution of pyrite ................................. 175
11.3 Equilibrium equations ................................. 176
12 Uniqueness ................................................. 181
12.1 The question of uniqueness ............................ 182
12.2 Examples of nonunique solutions ....................... 182
12.3 Coping with nonuniqueness ............................. 189
Part II Reaction processes .................................... 191
13 Mass transfer .............................................. 193
13.1 Simple reactants ..................................... 193
13.2 Extracting the overall reaction ...................... 196
13.3 Special configurations ............................... 198
14 Polythermal, fixed, and sliding paths ...................... 201
14.1 Polythermal reaction paths ........................... 201
14.2 Fixed activity and fugacity paths .................... 203
14.3 Sliding activity and fugacity paths .................. 207
15 Geochemical buffers ........................................ 217
15.1 Buffers in solution .................................. 218
15.2 Minerals as buffers .................................. 222
15.3 Gas buffers .......................................... 228
16 Kinetics of dissolution and precipitation .................. 231
16.1 Kinetic rate laws .................................... 232
16.2 From laboratory to application ....................... 236
16.3 Numerical solution ................................... 238
16.4 Example calculations ................................. 240
16.5 Modeling strategy .................................... 242
17 Redox kinetics ............................................. 245
17.1 Rate laws for oxidation and reduction ................ 246
17.2 Heterogeneous catalysis .............................. 248
17.3 Enzymes .............................................. 250
17.4 Numerical solution ................................... 252
17.5 Example calculation .................................. 254
18 Microbial kinetics ......................................... 257
18.1 Microbial respiration and fermentation ............... 257
18.2 Monod equation ....................................... 260
18.3 Thermodynamically consistent rate laws ............... 261
18.4 General kinetic model ................................ 263
18.5 Example calculation .................................. 265
19 Stable isotopes ............................................ 269
19.1 Isotope fractionation ................................ 270
19.2 Mass balance equations ............................... 272
19.3 Fractionation in reacting systems .................... 275
19.4 Dolomitization of a limestone ........................ 279
20 Transport in flowing groundwater ........................... 285
20.1 Groundwater flow ..................................... 285
20.2 Mass transport ....................................... 287
20.3 Advection-dispersion equation ........................ 292
20.4 Numerical solution ................................... 294
20.5 Example calculation .................................. 299
21 Reactive transport ......................................... 301
21.1 Mathematical model ................................... 301
21.2 Numerical solution ................................... 306
21.3 Example calculations ................................. 310
Part III Applied reaction modeling ............................ 317
22 Нуdrothermal fluids ........................................ 319
22.1 Origin of a fluorite deposit ......................... 320
22.2 Black smokers ........................................ 325
22.3 Energy available to thermophiles ..................... 331
23 Geothermometry ............................................. 341
23.1 Principles of geothermometry ......................... 342
23.2 Hot spring at Hveravik, Iceland ...................... 347
23.3 Geothermal fields in Iceland ......................... 350
24 Evaporation ................................................ 357
24.1 Springs and saline lakes of the Sierra Nevada ........ 357
24.2 Chemical evolution of Mono Lake ...................... 362
24.3 Evaporation of seawater .............................. 367
25 Sediment diagenesis ........................................ 373
25.1 Dolomite cement in the Gippsland basin ............... 374
25.2 Lyons sandstone, Denver basin ........................ 378
26 Kinetics of water-rock interaction ......................... 387
26.1 Approach to equilibrium and steady state ............. 387
26.2 Quartz deposition in a fracture ...................... 393
26.3 Silica transport in an aquifer ....................... 395
26.4 Ostwald's step rule .................................. 397
26.5 Dissolution of albite ................................ 400
27 Weathering ................................................. 405
27.1 Rainwater infiltration in an aquifer ................. 405
27.2 Weathering in a soil ................................. 409
28 Oxidation and reduction .................................... 415
28.1 Uranyl reduction by ferrous iron ..................... 415
28.2 Autocatalytic oxidation of manganese ................. 418
28.3 Microbial degradation of phenol ...................... 422
29 Waste injection wells ...................................... 427
29.1 Caustic waste injected in dolomite ................... 428
29.2 Gas blowouts ......................................... 431
30 Petroleum reservoirs ....................................... 435
30.1 Sulfate scaling in North Sea oil fields .............. 436
30.2 Alkali flooding ...................................... 442
31 Acid drainage .............................................. 449
31.1 Role of atmospheric oxygen ........................... 450
31.2 Buffering by wall rocks .............................. 453
31.3 Fate of dissolved metals ............................. 456
32 Contamination and remediation .............................. 461
32.1 Contamination with inorganic lead .................... 462
32.2 Groundwater chromatography ........................... 468
33 Microbial communities ...................................... 471
33.1 Arsenate reduction by Bacillus arsenicoselenatis ..... 471
33.2 Zoning in an aquifer ................................. 477
Appendix 1 Sources of modeling software ...................... 485
Appendix 2 Evaluating the HMW activity model ................. 491
Appendix 3 Minerals in the LLNL database ..................... 499
Appendix 4 Nonlinear rate laws ............................... 507
References .................................................... 509
Index ......................................................... 536
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