Front Cover	1
	Soil and Environmental Chemistry	4
	Copyright	5
	Dedication	6
	Contents	8
	Preface	16
	Chapter 1: Elements	18
	1.1. Introduction	18
	1.2. A Brief History of the Solar System and Planet Earth	19
	1.3. The Composition of Earth's Crust and Soils	20
	1.4. The Abundance of Elements in the Solar System, Earth's Crust, and Soils	20
	1.5. Elements and Isotopes	21
	1.6. Nuclear Binding Energy	23
	1.7. Enrichment and Depletion during Planetary Formation	25
	1.8. Planetary Accretion	26
	1.9. The Rock Cycle	29
	1.10. Soil Formation	30
	1.11. Concentration Frequency Distributions of the Elements	33
	1.12. Estimating the Most Probable Concentration and Concentration Range Using the LOGARITHMIC TRANSFORMATION	35
	1.13. Summary	38
	Appendix 1A. Factors Governing Nuclear Stability and Isotope Abundance	39
	1A.1. The Table of Isotopes and Nuclear Magic Numbers	39
	1A.2. Nuclear Magic Numbers	39
	Appendix 1B. Nucleosynthesis	42
	1B.1. Nuclear Reactions	42
	1B.2. Nuclear Fusion	43
	1B.3. Neutron Capture	45
	1B.4. Cosmic Ray Spallation	47
	1B.5. Transuranium Elements	47
	Appendix 1C. Thermonuclear FUSION Cycles	49
	1C.1. The CNO Cycle	49
	1C.2. The Triple-Alpha Process	50
	1C.3. Carbon Burning	51
	Appendix 1D. Neutron-Emitting Reactions that Sustain the S-Process	51
	Appendix 1E. Random Sequential Dilutions and the Law of Proportionate Effect	52
	Appendix 1F. The Estimate of Central Tendency and Variation of a Log-Normal Distribution	54
	Chapter 2: Soil Moisture and Hydrology	58
	2.1. Introduction	58
	2.2. Water Resources and the Hydrologic Cycle	59
	2.3. Water Budgets	60
	2.4. Residence Time and Runoff Ratios	60
	2.5. Groundwater Hydrology	62
	2.5.1. Water in the Porosphere	62
	2.5.2. Hydrologic Units	64
	2.5.3. Darcy’s Law	65
	2.5.4. Hydrostatic Heads and Hydrostatic Gradients	66
	2.5.5. Intrinsic Permeability	71
	2.5.6. Groundwater Flow Nets	73
	2.6. Vadose Zone Hydrology	75
	2.6.1. Capillary Forces	75
	2.6.2. Soil Moisture Zones	77
	2.6.3. The Water Characteristic Curve and Vadose Zone Hydraulic Conductivity	79
	2.7. Elementary Solute Transport Models	79
	2.7.1. The Retardation Coefficient Model	79
	2.7.2. Plate Theory: Multiple Sequential Partitioning	82
	2.8. Summary	88
	Appendix 2A. Soil Moisture Recharge and Loss	88
	Appendix 2B. The Water-Holding Capacity of a Soil Profile	89
	Appendix 2C. Predicting Capillary Rise	92
	Appendix 2D. Symbols and Units in the Derivation of the Retardation Coefficient Model of Solute Transport	93
	Appendix 2E. Symbols and Units in the Derivation of the Plate Theory Model of Solute Transport	94
	Appendix 2F. Empirical Water Characteristic Function and Unsaturated Hydraulic Conductivity	96
	Chapter 3: Clay Mineralogy and Clay Chemistry	102
	3.1. Introduction	102
	3.2. Mineral Weathering	103
	3.2.1. Mineralogy	103
	3.3. The Structure of Layer Silicates	106
	3.3.1. Coordination Polyhedra	107
	3.3.2. The Phyllosilicate Tetrahedral Sheet	108
	3.3.3. The Phyllosilicate Octahedral Sheet	109
	3.3.4. Kaolinite Layer Structure	110
	3.3.5. Talc Layer Structure	110
	3.3.6. Mica-Illite Layer Structure	111
	3.3.7. Chlorite and Hydroxy-Interlayered Smectite Layer Structure	113
	3.3.8. Layer Structure of the Swelling Clay Minerals: Smectite and Vermiculite	114
	Appendix 3A. Formal Oxidation Numbers	121
	Appendix 3B. The Geometry of Pauling's Radius Ratio Rule	122
	Appendix 3C. Bragg's Law and X-Ray Diffraction in Layer Silicates	126
	Appendix 3D. Osmotic Model of Interlayer Swelling Pressure	126
	Appendix 3E. Experimental Estimates of Interlayer Swelling Pressure	128
	Chapter 4: Ion Exchange	134
	4.1. Introduction	134
	4.2. The Discovery of Ion Exchange	135
	4.3. Ion Exchange Experiments	136
	4.3.1. Preparing Clay Saturated with a Single Cation	136
	4.3.2. Measuring Cation Exchange Capacity	137
	4.3.3. Measuring the Cation Exchange Isotherm	137
	4.3.4. Selectivity Coefficients and the Exchange Isotherm	139
	4.4. Interpreting the Ion Exchange Isotherm	142
	4.4.1. The Ion Exchange Isotherm for Symmetric Exchange	143
	4.4.2. The Ion Exchange Isotherm for Asymmetric Exchange	144
	4.4.3. Effect of Ionic Strength on the Ion Exchange Isotherm	146
	4.4.4. Effect of Ion Selectivity on the Ion Exchange Isotherm	148
	4.4.5. Other Influences on the Ion Exchange Isotherm	155
	4.5. Summary	157
	Appendix 4A. Thermodynamic and Conditional Selectivity Coefficients	159
	Appendix 4B. Nonlinear Least Square Fitting of Exchange Isotherms	160
	Appendix 4C. Equivalent Fraction-Dependent Selectivity Coefficient for (Mg2+, Ca2+) Exchange on the Libby Vermiculite	161
	Chapter 5: Water Chemistry	168
	5.1. The Equilibrium Constant	168
	5.1.1. Thermodynamic Functions for Chemical Reactions	168
	5.1.2. Gibbs Energy of Reaction and the Equilibrium Constant	169
	5.2. Activity and the Equilibrium Constant	170
	5.2.1. Concentrations and Activity	170
	5.2.2. Ionic Strength I	171
	5.2.3. Empirical Ion Activity Coefficient Expressions	171
	5.3. Modeling Water Chemistry	173
	5.3.1. Simple Equilibrium Systems	173
	5.3.2. Water Chemistry Simulations	187
	5.3.3. Modeling the Chemistry of Environmental Samples: Groundwater, Soil Pore Water, and Surface Water	196
	5.4. Summary	204
	Appendix 5A. ChemEQL Result Data File Format	204
	Appendix 5B. Validating Water Chemistry Simulations	205
	Appendix 5C. Validation Assessment for Examples 5.13 and 5.16	210
	Appendix 5D. Cinnabar Solubility in an Open System Containing the Gas Dihydrogen Sulfide	213
	Appendix 5E. Simultaneous Calcite-Apatite-Pyromorphite Solubility	216
	Appendix 5F. Simultaneous Gibbsite-Variscite Solubility	217
	Appendix 5G. Apatite Solubility as a Function of pH	217
	Appendix 5H. Effect of the Citrate on the Solubility of the Calcium Phosphate Mineral Apatite	218
	Appendix 5I. Effect of the Fungal Siderophore Desferrioxamine B on the Solubility of the Iron Oxyhydroxide Goethite	220
	Chapter 6: Natural Organic Matter and Humic Colloids	226
	6.1. Introduction	226
	6.2. Soil Carbon Cycle	226
	6.2.1. Carbon Fixation	227
	6.2.2. Carbon Mineralization	229
	6.2.3. Oxidation of Organic Compounds by Dioxygen	230
	6.3. Soil Carbon	234
	6.3.1. Carbon Turnover Models	234
	6.3.2. Soil Carbon Pools	238
	6.4. Dissolved Organic Carbon	240
	6.4.1. Organic Acids	240
	6.4.2. Amino Acids	241
	6.4.3. Extracellular Enzymes	241
	6.4.4. Siderophores	241
	6.4.5. Biosurfactants	245
	6.5. Humic Substances	246
	6.5.1. Extraction and Fractionation	246
	6.5.2. Elemental Composition	247
	6.5.3. Chemical Composition	248
	6.6. Humic Colloids	262
	6.7. Summary	263
	Appendix 6A. Hydroxamate and Catecholamide Siderophore Moieties	264
	Appendix 6B. Surface Microlayers	267
	Appendix 6C. Humic Oxygen Content and Titratable Weak Acids	269
	Appendix 6D. Hydrophobic and Hydrophilic Colloids	269
	Chapter 7: Acid-Base Chemistry	274
	7.1. Introduction	274
	7.2. Principles of Acid-Base Chemistry	275
	7.2.1. Dissociation: The Arrhenius Model of Acid-Base Reactions	275
	7.2.2 Hydrogen Ion Transfer: The Br nsted-Lowery Modelof Acid-Base Reactions	276
	7.2.3 Conjugate Acids and Bases	276
	7.2.4 Defining Acid and Base Strength	277
	7.2.5 Water Reference Level	278
	7.2.6 The Aqueous Carbon Dioxide Reference Level	279
	7.3. Sources of Environmental Acidity and Basicity	280
	7.3.1. Chemical Weathering of Rocks and Minerals	282
	7.3.2. Silicate Rocks	282
	7.3.3. Carbonate Rocks	284
	7.3.4. Sulfide Minerals	285
	7.3.5. Evaporite Rocks	286
	7.4. Atmospheric Gases	286
	7.4.1. Carbon Dioxide: Above Ground	286
	7.4.2. Carbon Dioxide: Below Ground	288
	7.4.3. Sulfur Oxides	288
	7.4.4. Nitrogen Oxides	290
	7.5. Ammonia-Based Fertilizers and Biomass Harvesting	293
	7.6. Charge Balancing in Plant Tissue and the Rhizosphere	295
	7.6.1. Water Alkalinity	297
	7.6.2. Carbonate Alkalinity	298
	7.6.3. Silicate Alkalinity	298
	7.6.4. The Methyl Orange End-Point	299
	7.6.5. Mineral Acidity	300
	7.7. Mechanical Properties of Clay Colloids and Soil Sodicity	300
	7.7.1. Clay Plasticity and Soil Mechanical Properties	301
	7.7.2. Clay Content and Granular Particle Contacts	303
	7.7.3. Sodicity	305
	7.7.4. Sodium-Ion Accumulation on the Clay Exchange Complex: ESP	306
	7.7.5. Pore Water Electrical Conductivity ECW	309
	7.7.6. Extreme Alkalinity: Soil pH>8.4	310
	7.7.7. Predicting Changes in Pore Water SAR	313
	7.8. Exchangeable Acidity	315
	7.8.1. Exchangeable Calcium and Soil Alkalinity	315
	7.8.2. Gibbsite Solubility	315
	7.8.3. The Role of Asymmetric (Al3þ,Ca2þ) Exchange	317
	7.8.4. Neutralizing Exchangeable Soil Acidity	318
	7.9. Summary	319
	Appendix 7A. Buffer Index	320
	Appendix 7B. Converting Mass Fraction to Sum-of-Oxides Composition	322
	Appendix 7C. Saturation Effect: Atmospheric Conversion of Sulfur Trioxide to Sulfuric Acid	322
	Appendix 7D. Bicarbonate and Carbonate Reference Levels	323
	Appendix 7E. Calculating the pH of a Sodium Carbonate Solution	325
	Appendix 7F. Calculating the Aqueous Carbon Dioxide Concentration in a Weak Base Solution	326
	Appendix 7G. Ion Exchange Isotherm for Asymmetric (Ca2+, Al3+) Exchange	327
	Appendix 7H. The Effect of (Na+, Ca2+) Exchange on the Critical Coagulation Concentration of Montmorillonite	330
	Appendix 7I. Predicting Changes in SAR by Water Chemistry Simulation	333
	Chapter 8: Redox Chemistry	338
	8.1. Introduction	338
	8.2. Redox Principles	339
	8.2.1. Formal Oxidation Numbers	339
	8.2.2. Balancing Reduction Half Reactions	341
	8.2.3. Reduction Half Reactions and Electrochemical Cells	343
	8.2.4. The Nernst Equation	344
	8.3. Interpreting Redox Stability Diagrams	348
	8.3.1. Environmental Redox Conditions	348
	8.3.2. Measuring Environmental Reduction	350
	8.3.3. Pourbaix Stability Diagrams: Preparationand Interpretation	351
	8.3.4. Water Stability Limits	351
	8.3.5. The Solute-Solute Reduction Boundary	353
	8.3.6. The Solute-Solute Hydrolysis Boundary	355
	8.3.7. The Solute-Precipitate Boundary	356
	8.3.8. The Solute-Precipitate Reduction Boundary	357
	8.3.9. The Precipitate-Precipitate Reduction Boundary	358
	8.3.10. Simple Rules for Interpreting Pourbaix Diagrams	360
	8.4. Microbial Respiration and Electron Transport Chains	362
	8.4.1. Catabolism and Respiration	364
	8.4.2. Electron Transport Chains	366
	8.4.3. Environmental Redox Conditions and Microbial Respiration	377
	8.5. Summary	378
	Appendix 8A. Assigning Formal Oxidation Numbers	379
	Appendix 8B. Converting (pe, pH) Redox Coordinates into (EH, pH) Coordinates	380
	Appendix 8C. Limitations in the Measurement of the Environmental Reduction Potential Using Platinum ORP Electrodes	382
	Chapter 9: Adsorption and Surface Chemistry	388
	9.1. Introduction	388
	9.2. Mineral and Organic Colloids as Environmental Adsorbents	389
	9.3. The Adsorption Isotherm Experiment	391
	9.4. Hydrophobic and Hydrophilic Colloids	396
	9.5. Interpreting the Adsorption Isotherm Experiment	396
	9.5.1. The Langmuir Adsorption Model	397
	9.5.2. Ion Exchange Adsorption Isotherms	399
	9.5.3. Linear Adsorption or Partitioning Model	400
	9.6. Variable-Charge Mineral Surfaces	404
	9.7. The Adsorption Envelope Experiment: Measuring pH-Dependent Ion Adsorption	405
	9.7.1. Adsorption Edges	406
	9.7.2. Measuring pH-Dependent Surface Charge	407
	9.7.3. Proton Surface Charge Sites	408
	9.8. Valence Bond Model of Proton Sites	409
	9.8.1. Interpreting pH-Dependent Ion Adsorption Experiments	411
	9.9. Surface Complexes	412
	9.10. Summary	416
	Appendix 9A. Particle Sedimentation Rates in Water: Stokes's Law	417
	Appendix 9B. Linear Langmuir Expression	418
	Appendix 9C. Hydrolysis Model of Proton Sites	419
	Chapter 10: Risk Assessment	426
	10.1. Introduction	426
	10.2. The Federal Risk Assessment Paradigm	428
	10.2.1. Risk Assessment	428
	10.2.2. Risk Management and Mitigation	428
	10.3. Dose-Response Assessment	428
	10.3.1. Dose-Response Distributions	429
	10.3.2. The No-Threshold One-Hit Model	430
	10.3.3. Low-Dose Extrapolation of Noncarcinogenic Response Functions	431
	10.3.4. Estimating the Steady-State Body Burden	432
	10.3.5. Reference Dose RfD	433
	10.3.6. Low-Dose Extrapolation of Carcinogenic Response Functions	433
	10.4. Exposure Pathway Assessment	436
	10.4.1. Receptors	436
	10.4.2. Exposure Routes	437
	10.4.3. Exposure Points	439
	10.4.4. Fate and Transport	440
	10.4.5. Primary and Secondary Sources	441
	10.4.6. Exposure Assessment	442
	10.5. Intake Estimates	442
	10.5.1. Averaging Time	442
	10.5.2. Exposure Factors	444
	10.6. Risk Characterization	445
	10.6.1. The Incremental Excess Lifetime Cancer Risk	445
	10.6.2. The Hazard Quotient	447
	10.7. Exposure Mitigation	448
	10.8. Summary	451
	Appendix 10A. Chemical- and Site-Specific Factors that May Affect Contaminant Transport by Surface Water	452
	Appendix 10B. Chemical- and Site-Specific Factors that May Affect Contaminant Transport by Groundwater	453
	Appendix 10C. Chemical- and Site-Specific Factors that May Affect Contaminant Transport Involving Soils or Sediments	454
	Appendix 10D. Chemical- and Site-Specific Factors that May Affect Contaminant Transport Involving Air and Biota	455
	Appendix 10E. The Water Ingestion Equation	455
	Appendix 10F. Soil Ingestion Equation	458
	Appendix 10G. Food Ingestion Equation	459
	Appendix 10H. Air Inhalation Equation	459
	Appendix 10I. Hazard Index-Cumulative Noncarcinogenic Risk	460
	Appendix 10J. Cumulative Target Risk-Cumulative carcinogenic Risk	461
	References	466
	Index	480