Geochemistry, Groundwater and Pollution, Second Edition (HBK)

Building on the success of its 1993 predecessor, this second edition of Geochemistry, Groundwater and Pollution has been thoroughly re-written, updated and extended to provide a complete and authoritative account of modern hydrogeochemistry. Offering a quantitative approach to the study of groundwater quality and the interaction of water, minerals, gases, pollutants and microbes, this book shows how physical and chemical theory can be applied to explain observed water qualities and variations over space and time. Integral to the presentation, geochemical modelling using PHREEQC code is demonstrated, with step-by-step instructions for calculating and simulating field and laboratory data. Numerous figures and tables illustrate the theory, while worked examples including calculations and theoretical explanations assist the reader in gaining a deeper understanding of the concepts involved. A crucial read for students of hydrogeology, geochemistry and civil engineering, professionals in the water sciences will also find inspiration in the practical examples and modeling templates. Half Title Title Copyright Preface Contents LIST OF EXAMPLES NOTATION 1 INTRODUCTION TO GROUNDWATER GEOCHEMISTRY 1.1 Groundwater as drinking water 1.1.1 Standards for drinking water 1.2 Units of analysis 1.3 Groundwater quality 1.4 Sampling of groundwater 1.4.1 Depth integrated or depth specific sampling 1.4.2 Procedures for sampling of groundwater 1.5 Chemical analysis of groundwater 1.5.1 Field analyses and sample conservation 1.5.2 Accuracy of chemical analysis Problems References 2 FROM RAINWATER TO GROUNDWATER 2.1 The hydrological cycle 2.2 The composition of rainwater 2.2.1 Sources and transport of atmospheric pollutants 2.3 Stable isotopes in rain 2.3.1 Isotopic ratios and the δ notation 2.3.2 The Rayleigh process 2.3.3 The isotopic composition of rain 2.4 Dry deposition and evapotranspiration 2.5 Mass balances and ecosystem dynamics 2.5.1 Water quality profiles in the unsaturated soil 2.6 Overall controls on water quality Problems References 3 FLOW AND TRANSPORT 3.1 Flow in the unsaturated zone 3.2 Flow in the saturated zone 3.2.1 Darcy’s law 3.2.2 Flowlines in the subsoil 3.2.3 Effects of non-homogeneity 3.2.4 The aquifer as a chemical reactor 3.3 Dating of groundwater 3.4 Retardation 3.4.1 The retardation equation 3.4.2 Indifferent and broadening fronts 3.4.3 Sharpening fronts 3.4.4 Solid and solute concentrations 3.5 Diffusion 3.5.1 Diffusion coefficients 3.5.2 Diffusion as a random process 3.5.3 Diffusive transport 3.5.4 Isotope diffusion 3.6 Dispersion 3.6.1 Column breakthrough curves 3.6.2 Dispersion coefficients and dispersivity 3.6.3 Macrodispersivity Problems References 4 MINERALS AND WATER 4.1 Equilibria and the solubility of minerals 4.2 Corrections for solubility calculations 4.2.1 Concentration and activity 4.2.2 Aqueous complexes 4.2.3 Combined complexes and activity corrections 4.2.4 Calculation of saturation states 4.3 Mass action constants and thermodynamics 4.3.1 The calculation of mass action constants 4.3.2 Calculation of mass action constants at different temperature 4.4 Equilibrium calculations with PHREEQC 4.4.1 Speciation calculations using PHREEQC 4.4.2 The PHREEQC database 4.4.3 Mineral equilibration 4.5 Solid solutions 4.5.1 Basic theory 4.5.2 The fractionation factor for solid solutions 4.5.3 Kinetic effects on the fractionation factor 4.6 Kinetics of geochemical processes 4.6.1 Kinetics and equilibrium 4.6.2 Chemical reactions and rates 4.6.3 Temperature dependency of reaction rates 4.6.4 Mechanisms of dissolution and crystallization 4.6.5 Rate laws for mineral dissolution and precipitation Problems References 5 CARBONATES AND CARBON DIOXIDE 5.1 Carbonate minerals 5.2 Dissolved carbonate equilibria 5.2.1 The carbonic acid system 5.2.2 Determining the carbonate speciation in groundwater 5.3 Carbon dioxide in soils 5.4 Calcite solubility and PCO2 5.4.1 Calcite dissolution in systems open and closed for CO2 gas 5.4.2 Two field examples 5.5 Carbonate rock aquifers 5.5.1 Dolomite and dedolomitization 5.5.2 Pleistocene carbonate aquifers 5.6 Kinetics of carbonate reactions 5.6.1 Dissolution 5.6.2 Precipitation 5.7 Carbon isotopes 5.7.1 Carbon-13 trends in aquifers 5.7.2 14C and groundwater age 5.7.3 Retardation by sorption and stagnant zone diffusion Problems References 6 ION EXCHANGE 6.1 Cation exchange at the salt/fresh water interface 6.2 Adsorbents in soils and aquifers 6.2.1 Clay minerals 6.3 Exchange equations 6.3.1 Values for exchange coefficients 6.3.2 Calculation of exchanger composition 6.3.3 Calculation of exchanger composition with PHREEQC 6.3.4 Determination of exchangeable cations 6.4 Chromatography of cation exchange 6.4.1 Field examples of freshening 6.4.2 Salinity effects on cation exchange 6.4.3 Quality patterns with salinization 6.4.4 Fronts and chromatographic sequences 6.4.5 Modeling chromatographic sequences with PHREEQC 6.5 Physical non-equilibrium 6.5.1 Modeling stagnant zones 6.6 The Gouy-Chapman theory of the double layer 6.6.1 Numerical integration of the double layer equations 6.6.2 Practical aspects of double layer theory 6.7 Irrigation water quality Problems References 7 SORPTION OF TRACE METALS 7.1 The origin and occurrence of heavy metals in groundwater 7.2 Sorption isotherms and distribution coefficients 7.2.1 Distribution coefficients from ion exchange 7.3 Variable charge surfaces 7.3.1 Titration curves with suspended oxide particles 7.3.2 Surface charge and point of zero charge, PZC 7.3.3 Sorption edges 7.3.4 Sorption, absorption, and coprecipitation 7.4 Surface complexation 7.4.1 Surface complexation models 7.4.2 The ferrihydrite (Fe(OH)3) database 7.4.3 Diffuse double layer concentrations in surface complexation models 7.5 Complexation to humic acids 7.5.1 The ion association model 7.5.2 Tipping and Hurley’s discrete site model “WHAM” 7.5.3 Distribution models 7.5.4 Humic acids as carriers of trace elements 7.6 Kinetics of surface complexation 7.6.1 Extrapolation of adsorption kinetics for other metal ions 7.7 Field applications Problems References 8 SILICATE WEATHERING 8.1 Weathering processes 8.2 The stability of weathering products 8.3 Incongruent dissolution of primary silicates 8.4 The mass balance approach to weathering 8.5 Kinetics of silicate weathering 8.6 Field weathering rates 8.7 Acid groundwater 8.7.1 Buffering processes in aquifers Problems References 9 REDOX PROCESSES 9.1 Basic theory 9.1.1 The significance of redox measurements 9.1.2 Redox reactions and the pe concept 9.2 Redox diagrams 9.2.1 Stability of water 9.2.2 The stability of dissolved species and gases: Arsenic 9.2.3 The stability of minerals in redox diagrams 9.3 Sequences of redox reactions and redox zoning 9.3.1 Decomposition of organic matter 9.4 Oxygen consumption 9.4.1 Pyrite oxidation 9.4.2 Kinetics of pyrite oxidation 9.4.3 Oxygen transport and pyrite oxidation 9.5 Nitrate reduction 9.5.1 Nitrate reduction by organic matter oxidation 9.5.2 Nitrate reduction by pyrite and ferrous iron 9.6 Iron reduction and sources of iron in groundwater 9.6.1 Iron in aquifer sediments 9.6.2 Reductive dissolution of iron oxides 9.7 Sulfate reduction and iron sulfide formation 9.7.1 The formation of iron sulfides 9.8 The formation of methane Problems References 10 POLLUTION BY ORGANIC CHEMICALS 10.1 Gas-water exchange 10.1.1 Evaporation of a pure organic liquid 10.2 Transport of pure organic liquids through soil 10.3 Sorption of organic chemicals 10.3.1 Sorption of charged organic molecules 10.3.2 Sorption in stagnant zones 10.3.3 Release from stagnant zones and blobs 10.4 Transformation reactions of organic chemicals 10.4.1 Monod biotransformation kinetics 10.5 Kinetic complexation of heavy metals on organics Problems References 11 NUMERICAL MODELING 11.1 Numerical modeling of transport 11.1.1 Only diffusion 11.1.2 Advection and diffusion/dispersion 11.1.3 Non-linear reactions 11.2 Examples of hydrogeochemical transport modeling 11.2.1 Tritium-Helium age dating 11.2.2 Toluene degradation in an aquifer 11.2.3 Remediation of a BTEX polluted site 11.2.4 Acid drainage from a Uranium mine 11.2.5 In-situ iron removal from groundwater 11.2.6 Arsenic in Bangladesh groundwater 11.2.7 Fractionation of isotopes References APPENDIX A: HYDROGEOCHEMICAL MODELING WITH PHREEQC APPENDIX B: ANSWERS TO PROBLEMS INDEX "Building on the success of its 1993 predecessor, this 2[superscript nd] edition of Geochemistry, Groundwater and Pollution has been thoroughly re-written, updated and extended into a complete and authoritative account of modern hydrogeochemistry. Offering a quantitative approach to the study of groundwater quality and the interaction of water, minerals, gases, pollutants and microbes, this book shows how physical and chemical theory can be applied to explain observed water qualities and variations over space and time." "This book is intended for students in hydrogeology, geochemistry and civil engineering, while professionals in the water sciences will find inspiration in the practical examples and modeling templates."--Jacket