Environmental Soil Properties and Behaviour
Contents Preface......................................................................................................................xv The Authors.......................................................................................................... xix 1. Origin and Function of Soils........................................................................1 1.1 Introduction............................................................................................ 1 1.1.1 Why Are We Concerned with Environmental Issues?........ 1 1.2 Soil Origin and Formation.................................................................... 2 1.2.1 Parent Material..........................................................................2 1.2.2 Weathering of Rock.................................................................. 3 1.2.2.1 Natural Processes......................................................3 1.2.2.2 Physical Weathering................................................. 4 1.2.2.3 Chemical Weathering............................................... 4 1.2.3 Processes of Chemical Weathering........................................ 6 1.2.4 Parent Material and Other Influences...................................7 1.2.4.1 Parent Material..........................................................7 1.2.4.2 Climate and Vegetation............................................ 7 1.2.4.3 Topography and Time..............................................8 1.3 Soil Classification................................................................................... 8 1.3.1 Subdivision of Surficial Deposits............................................ 9 1.3.2 Soil Horizons............................................................................. 9 1.3.3 Classification for Engineering Purposes............................. 11 1.3.3.1 Particle-Size Differentiation and Textural Classification............................................ 12 1.3.3.2 Particle-Size Distribution Curves......................... 13 1.3.3.3 Atterberg Limits Classification............................. 14 1.3.3.4 Unified Soil Classification System........................ 15 1.4 Basic Soil Functions............................................................................. 17 1.4.1 Natural in Situ Role................................................................ 19 1.4.2 In Situ Role with Human Intervention................................ 20 1.4.3 Soil as a Resource Material.................................................... 21 1.5 Concluding Remarks...........................................................................22 1.5.1 Soil Functionality....................................................................22 References........................................................................................................ 24 2. Nature of Soils............................................................................................... 25 2.1 Introduction.......................................................................................... 25 2.1.1 Soil Composition..................................................................... 25 2.1.2 Coarse-Grained Soils.............................................................. 26 2.1.3 Fine-Grained Soils.................................................................. 26 v © 2012 by Taylor & Francis Group, LLC
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2.2
2.3
2.4
2.5
2.6
2.7
Clay Minerals........................................................................................ 28 2.2.1 Unit Cell, Layer, and Mineral Structure.............................. 28 2.2.2 Surface Functional Groups.................................................... 30 2.2.3 Kaolin Group........................................................................... 31 2.2.3.1 Mineral Structure.................................................... 31 2.2.3.2 Surface Functional Groups.................................... 32 2.2.4 Chlorites................................................................................... 33 2.2.4.1 Mineral Structure.................................................... 33 2.2.4.2 Surface Functional Groups.................................... 33 2.2.5 Smectites................................................................................... 33 2.2.5.1 Mineral Structure.................................................... 33 2.2.5.2 Surface Functional Groups.................................... 35 2.2.6 Micas, Illites, and Mixed-Layer Clays.................................. 35 2.2.7 Allophane................................................................................. 38 2.2.7.1 Mineral Structure.................................................... 38 2.2.7.2 Surface Functional Groups.................................... 38 Nonclay Minerals................................................................................. 38 2.3.1 Oxides, Hydroxides, and Oxyhydroxides........................... 39 2.3.1.1 Basic Structure......................................................... 39 2.3.1.2 Surface Functional Groups.................................... 40 2.3.2 Carbonates and Sulphates..................................................... 41 Soil Organic Matter.............................................................................. 41 2.4.1 Characterization and Classification..................................... 41 2.4.2 Structure and Surface Functional Groups..........................42 2.4.2.1 Structure...................................................................42 2.4.2.2 Surface Functional Groups....................................43 Soil Particles.......................................................................................... 46 2.5.1 Size, Shape, and Texture of Particles.................................... 46 2.5.1.1 Size and Shape......................................................... 46 2.5.1.2 Texture...................................................................... 47 2.5.2 Electrical Charges................................................................... 47 2.5.2.1 Sources of Electrical Charges................................ 47 2.5.2.2 Net Surface Charges and Surface Charge Density........................................................ 48 2.5.3 Exchangeable Cations and Cation Exchange Capacity (CEC)........................................................................ 51 2.5.4 Anion Sorption and Exchange..............................................54 2.5.5 Specific Surface Area (SSA)................................................... 55 Soil Structure........................................................................................ 59 2.6.1 Soil Fabric and Structure....................................................... 59 2.6.2 Granular Soil Packing............................................................ 60 2.6.3 Microstructure of Clays......................................................... 62 Interparticle Bonds..............................................................................64 2.7.1 Forces and Bonding................................................................ 65
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Microorganisms in Soils..................................................................... 66 2.8.1 Types of Microorganisms...................................................... 66 2.8.1.1 Protozoa.................................................................... 66 2.8.1.2 Fungi......................................................................... 67 2.8.1.3 Algae......................................................................... 68 2.8.1.4 Viruses...................................................................... 68 2.8.2 Bacteria..................................................................................... 68 2.8.3 Ecology in Soils....................................................................... 70 2.8.4 Bacterial Growth Kinetics...................................................... 71 2.9 Laboratory Determinations................................................................ 74 2.9.1 Scope of Tests........................................................................... 74 2.9.2 Soil Type and Mineral Analysis........................................... 75 2.9.2.1 Soil Type................................................................... 75 2.9.2.2 Mineral Analysis..................................................... 76 2.9.2.3 Soil Fabric and Microstructural Features............ 78 2.10 Concluding Remarks........................................................................... 78 References........................................................................................................ 79 2.8
3. Soil–Water Systems.......................................................................................83 3.1 Introduction..........................................................................................83 3.2 Water Retention.................................................................................... 83 3.2.1 Granular (Cohesionless) Soils...............................................84 3.2.1.1 Wetting and Drying................................................85 3.2.2 Cohesive Soils.......................................................................... 86 3.2.2.1 Hydration of Clays.................................................. 87 3.3 Clay–Water Interactions...................................................................... 88 3.3.1 Electrified Interface and Interactions................................... 88 3.3.1.1 Diffuse Double Layers............................................ 89 3.3.1.2 Electric Potential ψ..................................................90 3.3.2 Interaction Energies................................................................ 93 3.3.2.1 Energies of Interaction in the Stern Layer........... 93 3.3.2.2 London–van der Waals Energy and Total Intermolecular Pair Potential................................ 93 3.3.2.3 DLVO Model and Particle Interaction Energies.............................................94 3.3.2.4 Energies in Particle Interaction and in Interlayer Space................................................... 97 3.3.2.5 Calculated Swelling Pressures from Interaction Models.................................................. 99 3.4 Soil–Water Energy Characteristics.................................................. 100 3.4.1 Concept of Soil–Water Potential......................................... 100 3.4.1.1 Components of Soil–Water Potential.................. 103 3.4.2 Measurements of Soil–Water Potentials............................ 106 3.4.2.1 Tensiometer for in Situ Measurements.............. 106
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3.4.2.2 Tensiometer-Type Device for Laboratory Use..................................................107 3.4.2.3 Pressure-Membrane Techniques......................... 109 3.4.2.4 Vapour Pressure Technique................................. 111 3.4.2.5 Thermocouple Psychrometer Measurements.......111 3.4.3 Hysteresis of Soil–Water Potential Relationships............. 113 3.5 Water Uptake and Transfer............................................................... 114 3.5.1 Moisture Transfer................................................................. 115 3.5.1.1 Water Transfer and Wetting Front...................... 116 3.5.1.2 Vapour Transfer..................................................... 121 3.6 Chemical Reactions in Porewater.................................................... 123 3.6.1 Acids, Bases, and pH............................................................ 124 3.6.2 Acid-Base Reactions, Hydrolysis........................................ 126 3.6.3 Oxidation-Reduction (Redox) Reactions........................... 126 3.7 Physical Reactions and Hydration................................................... 127 3.7.1 Hydrated Cations and Clay Minerals—From EXAFS Analyses................................................................... 128 3.8 Concluding Remarks......................................................................... 129 References...................................................................................................... 131 4. Swelling Clays............................................................................................. 133 4.1 Introduction........................................................................................ 133 4.2 Swelling Phenomena......................................................................... 134 4.2.1 Pertinent Soil Characteristics.............................................. 134 4.2.2 Mechanisms of Swelling...................................................... 136 4.2.2.1 Scoping Calculations for Swelling Pressures........139 4.2.3 Swelling—Effect of Salt Concentration and Porewater Composition........................................................ 141 4.2.3.1 Higher Valences and Mixtures of Cations......... 141 4.2.3.2 Influence of Exchangeable Cations..................... 142 4.2.4 Compositional Effects.......................................................... 143 4.2.4.1 Surface Charge and Attractive Forces................ 143 4.2.4.2 Mineralogical Effect.............................................. 145 4.3 Water Uptake and Swelling.............................................................. 146 4.3.1 Nature of Interlayer Water—From Molecular Dynamics Simulation........................................................... 147 4.3.1.1 Interlayer Water..................................................... 149 4.4 Water Movement................................................................................ 150 4.4.1 Wetting Front Advance........................................................ 150 4.4.1.1 Analysis Using Material Coordinate System........152 4.4.1.2 Soil Particle Diffusivity Analysis........................ 153 4.4.2 Water and Solid Content Profiles in Confined Swelling Clays....................................................................... 154
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Concluding Remarks......................................................................... 156 4.5.1 Swelling and Water Movement........................................... 156 4.5.2 Laboratory Measurement of Swelling............................... 157 References...................................................................................................... 160 4.5
5. Stressors, Impacts, and Soil Functionality............................................. 163 5.1 Introduction........................................................................................ 163 5.2 Stressor Sources and Stressors......................................................... 164 5.2.1 Soil Environment.................................................................. 164 5.2.2 Types of Stressor Sources and Stressors............................ 165 5.2.3 Natural Stressor Sources and Stressors............................. 166 5.2.4 Anthropogenic Stressor Sources and Stressors................ 168 5.2.4.1 Industry Sources of Stressors.............................. 169 5.2.4.2 Constructed Facility—Geologic Containment of HLW........................................... 170 5.3 Stressor Impacts................................................................................. 172 5.3.1 Impacts on Soil Environment.............................................. 172 5.3.2 Impacts on Soil Mass............................................................ 174 5.3.2.1 Hydraulic................................................................ 175 5.3.2.2 Mechanical............................................................. 175 5.3.2.3 Thermal.................................................................. 176 5.3.2.4 Chemical................................................................. 176 5.4 Soil Functionality Index (SFI)........................................................... 177 5.4.1 Soil Functionality Indicators............................................... 178 5.4.1.1 Selection of Indicators.......................................... 180 5.4.2 Indicators and Soil Functionality Index............................ 181 5.4.3 Application of SFI—An Example........................................ 183 5.5 Time-Related Change of Functionality........................................... 186 5.5.1 Time-Related Functionality................................................. 186 5.5.1.1 Time-Related Changes of Soil Attributes.......... 187 5.5.2 Time-Related Changes of Long-Term Functionality........ 189 5.5.2.1 Influence of Anthropogenic Stressors................ 189 5.5.2.2 Influence of Natural Stressors............................. 190 5.6 Concluding Remarks......................................................................... 191 References...................................................................................................... 192 6. Mechanical Properties................................................................................ 193 6.1 Introduction........................................................................................ 193 6.2 Mechanical Attributes....................................................................... 194 6.2.1 Soil Deformation under Load............................................. 195 6.2.1.1 Yield and Failure in Soils..................................... 195 6.2.2 Plastic Potential..................................................................... 197 6.2.3 Flow Function........................................................................ 198
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6.3
Concept of Effective Stress............................................................... 200 6.3.1 Physical Concept................................................................... 200 6.3.2 Physical Concept in Relation to Clays............................... 201 6.3.2.1 Clays with Adsorbed Water Layers.................... 201 6.3.2.2 High-Swelling Clays............................................. 203 6.4 Shear Strength of Soils...................................................................... 204 6.4.1 Laboratory Determinations................................................. 204 6.4.1.1 Triaxial Test System.............................................. 205 6.4.1.2 Other Strength Test Systems................................ 205 6.4.2 Yield and Failure Theories.................................................. 207 6.4.2.1 Principal Stress Space........................................... 207 6.4.2.2 Yield Criteria.......................................................... 209 6.4.3 Mohr–Coulomb Theory....................................................... 211 6.4.4 Yield/Failure Models........................................................... 214 6.4.4.1 One-Parameter Models......................................... 214 6.4.4.2 Two-Parameter Models......................................... 215 6.4.4.3 Plasticity Models................................................... 216 6.5 Mechanisms in Granular Soil Strength.......................................... 216 6.5.1 Frictional Resistance............................................................. 216 6.5.2 Mohr Failure Envelopes—Sliding and Interlocking Friction............................................................. 220 6.5.3 Volumetric Strain.................................................................. 221 6.6 Cohesive Soil Strength......................................................................223 6.6.1 Analytical and Physical Strength Parameters.................. 223 6.6.2 Analytical Shear Strength Parameters...............................223 6.6.3 Mechanistic Analyses.......................................................... 224 6.6.4 c and φ Parameters and Properties....................................225 6.7 Porewater Pressure............................................................................ 226 6.7.1 Partly Saturated Soil Porewater Pressures........................ 227 6.7.1.1 Pore Pressures in Granular Medium.................. 227 6.7.1.2 Pore Pressures in Clays........................................ 229 6.7.2 Porewater Pressure Coefficients......................................... 229 6.8 Shear Resistance Mechanisms......................................................... 232 6.8.1 Gravity Controlled................................................................ 232 6.8.2 Bonding Effects..................................................................... 232 6.9 Compressibility and Consolidation.................................................234 6.9.1 One-Dimensional Consolidation........................................ 236 6.9.1.1 Laboratory Test Data............................................. 237 6.9.2 Consolidation of Swelling Clays......................................... 241 6.10 Creep Behaviour................................................................................ 242 6.10.1 Creep in Clay: The Role of Microstructure....................... 243 6.11 Concluding Remarks......................................................................... 245 6.11.1 Integrity and Environment Stressor Impacts................... 245
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6.11.2 Soil Performance under Loading Stresses........................ 246 6.11.2.1 Yield and Failure Theories................................... 246 6.11.2.2 Porewater Pressure............................................... 247 References...................................................................................................... 248 7. Thermal and Hydraulic Properties.......................................................... 249 7.1 Introduction........................................................................................ 249 7.2 Thermal Properties............................................................................ 250 7.2.1 Heat-Mass Simultaneous Flow........................................... 250 7.2.2 Fourier-Type Heat Flow....................................................... 251 7.2.3 Thermal Properties............................................................... 253 7.2.3.1 Thermal Conductivity..........................................254 7.2.3.2 Thermal Diffusivity.............................................. 255 7.2.3.3 Heat Capacity......................................................... 255 7.3 Water Movement under Thermal Gradient.................................... 256 7.3.1 Thermally Induced Vapour Movement............................. 256 7.3.2 Thermally Induced Liquid Water Movement................... 257 7.3.3 Thermal Gradients and Water Content Profiles............... 259 7.4 Hydraulic Properties......................................................................... 261 7.4.1 Water Permeability............................................................... 263 7.4.1.1 Darcy Model........................................................... 263 7.4.1.2 Darcy Permeability Coefficient........................... 264 7.4.1.3 Effect of High Hydraulic Gradients.................... 266 7.4.1.4 Darcy Model with Permeant Properties............ 267 7.4.2 Permeability and Soil Structure......................................... 268 7.4.2.1 Kozeny–Carman Permeability Coefficient........ 268 7.4.3 Soil Strata and Hydraulic Properties................................. 270 7.4.3.1 Finger Flow............................................................ 271 7.4.3.2 Water Flow in Layered Soils................................ 273 7.4.4 Void Space and Hydraulic–Thermal Properties............... 273 7.4.4.1 Flow-Through Channels...................................... 274 7.4.4.2 Deep Percolation of Water.................................... 275 7.5 Swelling Clay Hydraulic Conductivity........................................... 276 7.5.1 Hydraulic Conductivity and Clay Structure.................... 276 7.5.2 Laboratory Test for Permeability........................................ 277 7.5.2.1 Oedometer-Type Permeameter............................ 278 7.5.2.2 Triaxial-Type Permeameter.................................. 278 7.6 Vapour and Gas Conductivities....................................................... 279 7.6.1 Steady-State Experiments.................................................... 279 7.6.2 Unsteady-State Experiments............................................... 280 7.7 Concluding Remarks......................................................................... 281 References...................................................................................................... 282
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8. Sorption Properties and Mechanisms..................................................... 285 8.1 Introduction........................................................................................ 285 8.2 Solutes, Contaminants, and Pollutants........................................... 285 8.2.1 Transport of Contaminants................................................. 287 8.3 Contaminant Interactions with Soil Particles................................ 289 8.3.1 Contaminants of Interest..................................................... 289 8.3.1.1 Inorganic Contaminants...................................... 289 8.3.1.2 Organic Contaminants......................................... 291 8.3.2 Surface Properties and Interactions................................... 292 8.3.2.1 Clay Minerals......................................................... 293 8.3.2.2 Oxides and Soil Organic Matter......................... 294 8.3.2.3 Surface Functional Groups of Organic Chemical Contaminants....................................... 294 8.3.2.4 Clay Particle Interaction with Organic Chemical Functional Groups............................... 297 8.4 Contaminant Sorption Mechanisms............................................... 298 8.4.1 Physical Adsorption (Physisorption)................................. 299 8.4.2 Chemical Adsorption (Chemisorption)............................. 301 8.4.3 Specific Adsorption.............................................................. 302 8.4.4 Rate-Limiting Processes—Heavy Metals..........................304 8.5 Laboratory Determination of Partitioning..................................... 305 8.5.1 Batch Equilibrium Tests and Adsorption Isotherms....... 307 8.5.1.1 Inorganic Contaminants...................................... 307 8.5.1.2 Organic Chemical Contaminants....................... 310 8.5.2 Column Leaching Tests........................................................ 314 8.5.2.1 Breakthrough Curves........................................... 318 8.6 Partitioning and Soil Composition.................................................. 320 8.6.1 Inorganic Contaminants...................................................... 320 8.6.1.1 Selective Sequential Extraction (SSE) Technique............................................................... 320 8.6.2 Organic Chemical Contaminants....................................... 324 8.7 Concluding Remarks......................................................................... 328 References...................................................................................................... 330 9. Mobility and Attenuation of Contaminants.......................................... 333 9.1 Introduction........................................................................................ 333 9.2 Interactions and Mobility.................................................................334 9.2.1 Inorganic Contaminants......................................................334 9.2.1.1 Soil Fractions and Sorption Sites........................334 9.2.1.2 pH and Chemical Buffering................................ 336 9.2.1.3 pH and Precipitation............................................. 336 9.2.1.4 Selectivity, Affinity, and Preferential Sorption.......................................... 338 9.2.1.5 Ligands in Porewater............................................340
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9.2.2
Organic Chemical Compounds..........................................343 9.2.2.1 NAPLs Mobility.....................................................344 9.2.2.2 Vapour Phase and Volatilization.........................346 9.3 Mobility and Attenuation................................................................. 347 9.3.1 Physicochemical Forces and Transport of Contaminants........................................................................348 9.3.2 Modelling for Macroscopic Transport of Contaminants.......................................................................351 9.3.2.1 Diffusion and Advection...................................... 351 9.3.2.2 Irreversible and Reversible Sorption/ Partition Models.................................................... 354 9.3.2.3 Coupled Flow of Water and Contaminants....... 356 9.4 Microstructure and Diffusive Transport........................................ 358 9.4.1 Soil Structure Control.......................................................... 359 9.4.2 Molecular Diffusion Coefficient......................................... 361 9.5 Attenuation of Organic Chemicals.................................................. 362 9.5.1 Abiotic and Biotic Processes................................................ 363 9.5.1.1 Hydrolysis..............................................................364 9.5.1.2 Oxidation-Reduction Reactions.......................... 366 9.5.2 Organic Halogen Compounds............................................ 367 9.6 Concluding Remarks......................................................................... 369 References...................................................................................................... 370 10. Environmental Soil Behaviour................................................................. 375 10.1 Introduction........................................................................................ 375 10.2 Soil Evolution and Ageing Processes.............................................. 376 10.2.1 Natural Ageing Processes................................................... 376 10.2.2 Soil Fractions and Natural Ageing Processes................... 377 10.2.3 Transformation of Clay Minerals....................................... 378 10.2.3.1 Weathering Processes........................................... 378 10.2.3.2 Illitization from Smectite..................................... 379 10.2.4 Biotransformation of Clay Minerals................................... 381 10.2.4.1 Structural Iron Reduction.................................... 383 10.2.4.2 Microbial Dissolution of Clay Minerals.............384 10.3 Time-Related Changes and Soil Evolution..................................... 386 10.3.1 Stressors and Time-Related Activities............................... 388 10.3.2 Transported Contaminants and Soil Permeability.......... 388 10.3.3 Transported Contaminants and Soil Compression......... 390 10.4 Biodegradation and Biotransformation of Contaminants........... 392 10.4.1 Biodegradation of Organic Contaminants........................ 394 10.4.1.1 Alkanes and Cycloalkanes................................... 394 10.4.1.2 Gasoline Components BTEX and Methyl Tertiary-Butyl Ether (MTBE)................................ 395 10.4.1.3 Halogenated Aliphatic and Aromatic Compounds............................................................ 395
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10.4.2 Biotransformation of Inorganic Contaminants................ 396 10.4.2.1 Bacterial Metabolism of Nitrogen and Sulphur................................................................... 397 10.4.3 Natural Attenuation of Contaminants............................. 398 10.4.3.1 Monitored Natural Attenuation.......................... 398 10.4.3.2 Attenuation of Organic Chemical Compounds............................................................400 10.4.3.3 Attenuation of Heavy Metals.............................. 402 10.4.4 Enhanced and Engineered Natural Attenuation of Contaminants.................................................................... 403 10.4.4.1 Biostimulation........................................................ 403 10.4.4.2 Bioaugmentation................................................... 403 10.4.4.3 Geochemical and Biogeochemical Intervention............................................................404 10.4.4.4 Permeable Reactive Barriers (PRBs).................... 404 10.5 Freeze–Thaw Seasonal Impact......................................................... 406 10.5.1 Freezing and Frost Penetration........................................... 406 10.5.1.1 Freezing Index....................................................... 406 10.5.1.2 Geothermal Profiles.............................................. 407 10.5.1.3 Frost Penetration...................................................408 10.5.1.4 Frost Heave and Heaving Pressures.................. 411 10.5.1.5 Cyclical Effect of Freeze–Thaw........................... 414 10.5.2 Unfrozen Water in Frozen Soils.......................................... 415 10.5.3 Water Movement in Frozen Soils........................................ 416 10.5.4 Salt Concentration and Unfrozen Water Content— Swelling Clays....................................................................... 417 10.6 Concluding Remarks......................................................................... 420 References...................................................................................................... 421 Index......................................................................................................................425
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2.2
2.3
2.4
2.5
2.6
2.7
Clay Minerals........................................................................................ 28 2.2.1 Unit Cell, Layer, and Mineral Structure.............................. 28 2.2.2 Surface Functional Groups.................................................... 30 2.2.3 Kaolin Group........................................................................... 31 2.2.3.1 Mineral Structure.................................................... 31 2.2.3.2 Surface Functional Groups.................................... 32 2.2.4 Chlorites................................................................................... 33 2.2.4.1 Mineral Structure.................................................... 33 2.2.4.2 Surface Functional Groups.................................... 33 2.2.5 Smectites................................................................................... 33 2.2.5.1 Mineral Structure.................................................... 33 2.2.5.2 Surface Functional Groups.................................... 35 2.2.6 Micas, Illites, and Mixed-Layer Clays.................................. 35 2.2.7 Allophane................................................................................. 38 2.2.7.1 Mineral Structure.................................................... 38 2.2.7.2 Surface Functional Groups.................................... 38 Nonclay Minerals................................................................................. 38 2.3.1 Oxides, Hydroxides, and Oxyhydroxides........................... 39 2.3.1.1 Basic Structure......................................................... 39 2.3.1.2 Surface Functional Groups.................................... 40 2.3.2 Carbonates and Sulphates..................................................... 41 Soil Organic Matter.............................................................................. 41 2.4.1 Characterization and Classification..................................... 41 2.4.2 Structure and Surface Functional Groups..........................42 2.4.2.1 Structure...................................................................42 2.4.2.2 Surface Functional Groups....................................43 Soil Particles.......................................................................................... 46 2.5.1 Size, Shape, and Texture of Particles.................................... 46 2.5.1.1 Size and Shape......................................................... 46 2.5.1.2 Texture...................................................................... 47 2.5.2 Electrical Charges................................................................... 47 2.5.2.1 Sources of Electrical Charges................................ 47 2.5.2.2 Net Surface Charges and Surface Charge Density........................................................ 48 2.5.3 Exchangeable Cations and Cation Exchange Capacity (CEC)........................................................................ 51 2.5.4 Anion Sorption and Exchange..............................................54 2.5.5 Specific Surface Area (SSA)................................................... 55 Soil Structure........................................................................................ 59 2.6.1 Soil Fabric and Structure....................................................... 59 2.6.2 Granular Soil Packing............................................................ 60 2.6.3 Microstructure of Clays......................................................... 62 Interparticle Bonds..............................................................................64 2.7.1 Forces and Bonding................................................................ 65
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Microorganisms in Soils..................................................................... 66 2.8.1 Types of Microorganisms...................................................... 66 2.8.1.1 Protozoa.................................................................... 66 2.8.1.2 Fungi......................................................................... 67 2.8.1.3 Algae......................................................................... 68 2.8.1.4 Viruses...................................................................... 68 2.8.2 Bacteria..................................................................................... 68 2.8.3 Ecology in Soils....................................................................... 70 2.8.4 Bacterial Growth Kinetics...................................................... 71 2.9 Laboratory Determinations................................................................ 74 2.9.1 Scope of Tests........................................................................... 74 2.9.2 Soil Type and Mineral Analysis........................................... 75 2.9.2.1 Soil Type................................................................... 75 2.9.2.2 Mineral Analysis..................................................... 76 2.9.2.3 Soil Fabric and Microstructural Features............ 78 2.10 Concluding Remarks........................................................................... 78 References........................................................................................................ 79 2.8
3. Soil–Water Systems.......................................................................................83 3.1 Introduction..........................................................................................83 3.2 Water Retention.................................................................................... 83 3.2.1 Granular (Cohesionless) Soils...............................................84 3.2.1.1 Wetting and Drying................................................85 3.2.2 Cohesive Soils.......................................................................... 86 3.2.2.1 Hydration of Clays.................................................. 87 3.3 Clay–Water Interactions...................................................................... 88 3.3.1 Electrified Interface and Interactions................................... 88 3.3.1.1 Diffuse Double Layers............................................ 89 3.3.1.2 Electric Potential ψ..................................................90 3.3.2 Interaction Energies................................................................ 93 3.3.2.1 Energies of Interaction in the Stern Layer........... 93 3.3.2.2 London–van der Waals Energy and Total Intermolecular Pair Potential................................ 93 3.3.2.3 DLVO Model and Particle Interaction Energies.............................................94 3.3.2.4 Energies in Particle Interaction and in Interlayer Space................................................... 97 3.3.2.5 Calculated Swelling Pressures from Interaction Models.................................................. 99 3.4 Soil–Water Energy Characteristics.................................................. 100 3.4.1 Concept of Soil–Water Potential......................................... 100 3.4.1.1 Components of Soil–Water Potential.................. 103 3.4.2 Measurements of Soil–Water Potentials............................ 106 3.4.2.1 Tensiometer for in Situ Measurements.............. 106
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3.4.2.2 Tensiometer-Type Device for Laboratory Use..................................................107 3.4.2.3 Pressure-Membrane Techniques......................... 109 3.4.2.4 Vapour Pressure Technique................................. 111 3.4.2.5 Thermocouple Psychrometer Measurements.......111 3.4.3 Hysteresis of Soil–Water Potential Relationships............. 113 3.5 Water Uptake and Transfer............................................................... 114 3.5.1 Moisture Transfer................................................................. 115 3.5.1.1 Water Transfer and Wetting Front...................... 116 3.5.1.2 Vapour Transfer..................................................... 121 3.6 Chemical Reactions in Porewater.................................................... 123 3.6.1 Acids, Bases, and pH............................................................ 124 3.6.2 Acid-Base Reactions, Hydrolysis........................................ 126 3.6.3 Oxidation-Reduction (Redox) Reactions........................... 126 3.7 Physical Reactions and Hydration................................................... 127 3.7.1 Hydrated Cations and Clay Minerals—From EXAFS Analyses................................................................... 128 3.8 Concluding Remarks......................................................................... 129 References...................................................................................................... 131 4. Swelling Clays............................................................................................. 133 4.1 Introduction........................................................................................ 133 4.2 Swelling Phenomena......................................................................... 134 4.2.1 Pertinent Soil Characteristics.............................................. 134 4.2.2 Mechanisms of Swelling...................................................... 136 4.2.2.1 Scoping Calculations for Swelling Pressures........139 4.2.3 Swelling—Effect of Salt Concentration and Porewater Composition........................................................ 141 4.2.3.1 Higher Valences and Mixtures of Cations......... 141 4.2.3.2 Influence of Exchangeable Cations..................... 142 4.2.4 Compositional Effects.......................................................... 143 4.2.4.1 Surface Charge and Attractive Forces................ 143 4.2.4.2 Mineralogical Effect.............................................. 145 4.3 Water Uptake and Swelling.............................................................. 146 4.3.1 Nature of Interlayer Water—From Molecular Dynamics Simulation........................................................... 147 4.3.1.1 Interlayer Water..................................................... 149 4.4 Water Movement................................................................................ 150 4.4.1 Wetting Front Advance........................................................ 150 4.4.1.1 Analysis Using Material Coordinate System........152 4.4.1.2 Soil Particle Diffusivity Analysis........................ 153 4.4.2 Water and Solid Content Profiles in Confined Swelling Clays....................................................................... 154
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Concluding Remarks......................................................................... 156 4.5.1 Swelling and Water Movement........................................... 156 4.5.2 Laboratory Measurement of Swelling............................... 157 References...................................................................................................... 160 4.5
5. Stressors, Impacts, and Soil Functionality............................................. 163 5.1 Introduction........................................................................................ 163 5.2 Stressor Sources and Stressors......................................................... 164 5.2.1 Soil Environment.................................................................. 164 5.2.2 Types of Stressor Sources and Stressors............................ 165 5.2.3 Natural Stressor Sources and Stressors............................. 166 5.2.4 Anthropogenic Stressor Sources and Stressors................ 168 5.2.4.1 Industry Sources of Stressors.............................. 169 5.2.4.2 Constructed Facility—Geologic Containment of HLW........................................... 170 5.3 Stressor Impacts................................................................................. 172 5.3.1 Impacts on Soil Environment.............................................. 172 5.3.2 Impacts on Soil Mass............................................................ 174 5.3.2.1 Hydraulic................................................................ 175 5.3.2.2 Mechanical............................................................. 175 5.3.2.3 Thermal.................................................................. 176 5.3.2.4 Chemical................................................................. 176 5.4 Soil Functionality Index (SFI)........................................................... 177 5.4.1 Soil Functionality Indicators............................................... 178 5.4.1.1 Selection of Indicators.......................................... 180 5.4.2 Indicators and Soil Functionality Index............................ 181 5.4.3 Application of SFI—An Example........................................ 183 5.5 Time-Related Change of Functionality........................................... 186 5.5.1 Time-Related Functionality................................................. 186 5.5.1.1 Time-Related Changes of Soil Attributes.......... 187 5.5.2 Time-Related Changes of Long-Term Functionality........ 189 5.5.2.1 Influence of Anthropogenic Stressors................ 189 5.5.2.2 Influence of Natural Stressors............................. 190 5.6 Concluding Remarks......................................................................... 191 References...................................................................................................... 192 6. Mechanical Properties................................................................................ 193 6.1 Introduction........................................................................................ 193 6.2 Mechanical Attributes....................................................................... 194 6.2.1 Soil Deformation under Load............................................. 195 6.2.1.1 Yield and Failure in Soils..................................... 195 6.2.2 Plastic Potential..................................................................... 197 6.2.3 Flow Function........................................................................ 198
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6.3
Concept of Effective Stress............................................................... 200 6.3.1 Physical Concept................................................................... 200 6.3.2 Physical Concept in Relation to Clays............................... 201 6.3.2.1 Clays with Adsorbed Water Layers.................... 201 6.3.2.2 High-Swelling Clays............................................. 203 6.4 Shear Strength of Soils...................................................................... 204 6.4.1 Laboratory Determinations................................................. 204 6.4.1.1 Triaxial Test System.............................................. 205 6.4.1.2 Other Strength Test Systems................................ 205 6.4.2 Yield and Failure Theories.................................................. 207 6.4.2.1 Principal Stress Space........................................... 207 6.4.2.2 Yield Criteria.......................................................... 209 6.4.3 Mohr–Coulomb Theory....................................................... 211 6.4.4 Yield/Failure Models........................................................... 214 6.4.4.1 One-Parameter Models......................................... 214 6.4.4.2 Two-Parameter Models......................................... 215 6.4.4.3 Plasticity Models................................................... 216 6.5 Mechanisms in Granular Soil Strength.......................................... 216 6.5.1 Frictional Resistance............................................................. 216 6.5.2 Mohr Failure Envelopes—Sliding and Interlocking Friction............................................................. 220 6.5.3 Volumetric Strain.................................................................. 221 6.6 Cohesive Soil Strength......................................................................223 6.6.1 Analytical and Physical Strength Parameters.................. 223 6.6.2 Analytical Shear Strength Parameters...............................223 6.6.3 Mechanistic Analyses.......................................................... 224 6.6.4 c and φ Parameters and Properties....................................225 6.7 Porewater Pressure............................................................................ 226 6.7.1 Partly Saturated Soil Porewater Pressures........................ 227 6.7.1.1 Pore Pressures in Granular Medium.................. 227 6.7.1.2 Pore Pressures in Clays........................................ 229 6.7.2 Porewater Pressure Coefficients......................................... 229 6.8 Shear Resistance Mechanisms......................................................... 232 6.8.1 Gravity Controlled................................................................ 232 6.8.2 Bonding Effects..................................................................... 232 6.9 Compressibility and Consolidation.................................................234 6.9.1 One-Dimensional Consolidation........................................ 236 6.9.1.1 Laboratory Test Data............................................. 237 6.9.2 Consolidation of Swelling Clays......................................... 241 6.10 Creep Behaviour................................................................................ 242 6.10.1 Creep in Clay: The Role of Microstructure....................... 243 6.11 Concluding Remarks......................................................................... 245 6.11.1 Integrity and Environment Stressor Impacts................... 245
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6.11.2 Soil Performance under Loading Stresses........................ 246 6.11.2.1 Yield and Failure Theories................................... 246 6.11.2.2 Porewater Pressure............................................... 247 References...................................................................................................... 248 7. Thermal and Hydraulic Properties.......................................................... 249 7.1 Introduction........................................................................................ 249 7.2 Thermal Properties............................................................................ 250 7.2.1 Heat-Mass Simultaneous Flow........................................... 250 7.2.2 Fourier-Type Heat Flow....................................................... 251 7.2.3 Thermal Properties............................................................... 253 7.2.3.1 Thermal Conductivity..........................................254 7.2.3.2 Thermal Diffusivity.............................................. 255 7.2.3.3 Heat Capacity......................................................... 255 7.3 Water Movement under Thermal Gradient.................................... 256 7.3.1 Thermally Induced Vapour Movement............................. 256 7.3.2 Thermally Induced Liquid Water Movement................... 257 7.3.3 Thermal Gradients and Water Content Profiles............... 259 7.4 Hydraulic Properties......................................................................... 261 7.4.1 Water Permeability............................................................... 263 7.4.1.1 Darcy Model........................................................... 263 7.4.1.2 Darcy Permeability Coefficient........................... 264 7.4.1.3 Effect of High Hydraulic Gradients.................... 266 7.4.1.4 Darcy Model with Permeant Properties............ 267 7.4.2 Permeability and Soil Structure......................................... 268 7.4.2.1 Kozeny–Carman Permeability Coefficient........ 268 7.4.3 Soil Strata and Hydraulic Properties................................. 270 7.4.3.1 Finger Flow............................................................ 271 7.4.3.2 Water Flow in Layered Soils................................ 273 7.4.4 Void Space and Hydraulic–Thermal Properties............... 273 7.4.4.1 Flow-Through Channels...................................... 274 7.4.4.2 Deep Percolation of Water.................................... 275 7.5 Swelling Clay Hydraulic Conductivity........................................... 276 7.5.1 Hydraulic Conductivity and Clay Structure.................... 276 7.5.2 Laboratory Test for Permeability........................................ 277 7.5.2.1 Oedometer-Type Permeameter............................ 278 7.5.2.2 Triaxial-Type Permeameter.................................. 278 7.6 Vapour and Gas Conductivities....................................................... 279 7.6.1 Steady-State Experiments.................................................... 279 7.6.2 Unsteady-State Experiments............................................... 280 7.7 Concluding Remarks......................................................................... 281 References...................................................................................................... 282
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8. Sorption Properties and Mechanisms..................................................... 285 8.1 Introduction........................................................................................ 285 8.2 Solutes, Contaminants, and Pollutants........................................... 285 8.2.1 Transport of Contaminants................................................. 287 8.3 Contaminant Interactions with Soil Particles................................ 289 8.3.1 Contaminants of Interest..................................................... 289 8.3.1.1 Inorganic Contaminants...................................... 289 8.3.1.2 Organic Contaminants......................................... 291 8.3.2 Surface Properties and Interactions................................... 292 8.3.2.1 Clay Minerals......................................................... 293 8.3.2.2 Oxides and Soil Organic Matter......................... 294 8.3.2.3 Surface Functional Groups of Organic Chemical Contaminants....................................... 294 8.3.2.4 Clay Particle Interaction with Organic Chemical Functional Groups............................... 297 8.4 Contaminant Sorption Mechanisms............................................... 298 8.4.1 Physical Adsorption (Physisorption)................................. 299 8.4.2 Chemical Adsorption (Chemisorption)............................. 301 8.4.3 Specific Adsorption.............................................................. 302 8.4.4 Rate-Limiting Processes—Heavy Metals..........................304 8.5 Laboratory Determination of Partitioning..................................... 305 8.5.1 Batch Equilibrium Tests and Adsorption Isotherms....... 307 8.5.1.1 Inorganic Contaminants...................................... 307 8.5.1.2 Organic Chemical Contaminants....................... 310 8.5.2 Column Leaching Tests........................................................ 314 8.5.2.1 Breakthrough Curves........................................... 318 8.6 Partitioning and Soil Composition.................................................. 320 8.6.1 Inorganic Contaminants...................................................... 320 8.6.1.1 Selective Sequential Extraction (SSE) Technique............................................................... 320 8.6.2 Organic Chemical Contaminants....................................... 324 8.7 Concluding Remarks......................................................................... 328 References...................................................................................................... 330 9. Mobility and Attenuation of Contaminants.......................................... 333 9.1 Introduction........................................................................................ 333 9.2 Interactions and Mobility.................................................................334 9.2.1 Inorganic Contaminants......................................................334 9.2.1.1 Soil Fractions and Sorption Sites........................334 9.2.1.2 pH and Chemical Buffering................................ 336 9.2.1.3 pH and Precipitation............................................. 336 9.2.1.4 Selectivity, Affinity, and Preferential Sorption.......................................... 338 9.2.1.5 Ligands in Porewater............................................340
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9.2.2
Organic Chemical Compounds..........................................343 9.2.2.1 NAPLs Mobility.....................................................344 9.2.2.2 Vapour Phase and Volatilization.........................346 9.3 Mobility and Attenuation................................................................. 347 9.3.1 Physicochemical Forces and Transport of Contaminants........................................................................348 9.3.2 Modelling for Macroscopic Transport of Contaminants.......................................................................351 9.3.2.1 Diffusion and Advection...................................... 351 9.3.2.2 Irreversible and Reversible Sorption/ Partition Models.................................................... 354 9.3.2.3 Coupled Flow of Water and Contaminants....... 356 9.4 Microstructure and Diffusive Transport........................................ 358 9.4.1 Soil Structure Control.......................................................... 359 9.4.2 Molecular Diffusion Coefficient......................................... 361 9.5 Attenuation of Organic Chemicals.................................................. 362 9.5.1 Abiotic and Biotic Processes................................................ 363 9.5.1.1 Hydrolysis..............................................................364 9.5.1.2 Oxidation-Reduction Reactions.......................... 366 9.5.2 Organic Halogen Compounds............................................ 367 9.6 Concluding Remarks......................................................................... 369 References...................................................................................................... 370 10. Environmental Soil Behaviour................................................................. 375 10.1 Introduction........................................................................................ 375 10.2 Soil Evolution and Ageing Processes.............................................. 376 10.2.1 Natural Ageing Processes................................................... 376 10.2.2 Soil Fractions and Natural Ageing Processes................... 377 10.2.3 Transformation of Clay Minerals....................................... 378 10.2.3.1 Weathering Processes........................................... 378 10.2.3.2 Illitization from Smectite..................................... 379 10.2.4 Biotransformation of Clay Minerals................................... 381 10.2.4.1 Structural Iron Reduction.................................... 383 10.2.4.2 Microbial Dissolution of Clay Minerals.............384 10.3 Time-Related Changes and Soil Evolution..................................... 386 10.3.1 Stressors and Time-Related Activities............................... 388 10.3.2 Transported Contaminants and Soil Permeability.......... 388 10.3.3 Transported Contaminants and Soil Compression......... 390 10.4 Biodegradation and Biotransformation of Contaminants........... 392 10.4.1 Biodegradation of Organic Contaminants........................ 394 10.4.1.1 Alkanes and Cycloalkanes................................... 394 10.4.1.2 Gasoline Components BTEX and Methyl Tertiary-Butyl Ether (MTBE)................................ 395 10.4.1.3 Halogenated Aliphatic and Aromatic Compounds............................................................ 395
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10.4.2 Biotransformation of Inorganic Contaminants................ 396 10.4.2.1 Bacterial Metabolism of Nitrogen and Sulphur................................................................... 397 10.4.3 Natural Attenuation of Contaminants............................. 398 10.4.3.1 Monitored Natural Attenuation.......................... 398 10.4.3.2 Attenuation of Organic Chemical Compounds............................................................400 10.4.3.3 Attenuation of Heavy Metals.............................. 402 10.4.4 Enhanced and Engineered Natural Attenuation of Contaminants.................................................................... 403 10.4.4.1 Biostimulation........................................................ 403 10.4.4.2 Bioaugmentation................................................... 403 10.4.4.3 Geochemical and Biogeochemical Intervention............................................................404 10.4.4.4 Permeable Reactive Barriers (PRBs).................... 404 10.5 Freeze–Thaw Seasonal Impact......................................................... 406 10.5.1 Freezing and Frost Penetration........................................... 406 10.5.1.1 Freezing Index....................................................... 406 10.5.1.2 Geothermal Profiles.............................................. 407 10.5.1.3 Frost Penetration...................................................408 10.5.1.4 Frost Heave and Heaving Pressures.................. 411 10.5.1.5 Cyclical Effect of Freeze–Thaw........................... 414 10.5.2 Unfrozen Water in Frozen Soils.......................................... 415 10.5.3 Water Movement in Frozen Soils........................................ 416 10.5.4 Salt Concentration and Unfrozen Water Content— Swelling Clays....................................................................... 417 10.6 Concluding Remarks......................................................................... 420 References...................................................................................................... 421 Index......................................................................................................................425
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