Environmental and Low Temperature Geochemistry

Content: Acknowledgements, xii    About the Companion Website, xiii     1 BACKGROUND AND BASIC CHEMICAL PRINCIPLES: ELEMENTS, IONS, BONDING, REACTIONS, 1     1.1 An overview of environmental geochemistry     history, scope, questions, approaches, challenges for the future, 1     1.2 The naturally occurring elements     origins and abundances, 2     1.3 Atoms and isotopes: a brief review, 6     1.4 Measuring concentrations, 8     1.4.1 Mass-based concentrations, 8     1.4.2 Molar concentrations, 9     1.4.3 Concentrations of gases, 10     1.4.4 Notes on precision and accuracy, significant figures and scientific notation, 10     1.5 Periodic table, 11     1.6 Ions, molecules, valence, bonding, chemical reactions, 14     1.6.1 Ionic bond strength, 14     1.6.2 Covalent bonds, 16     1.6.3 Electronegativity, 17     1.6.4 Metallic bonds, hydrogen bonds and van der Waals forces, 18     1.7 Acid   base equilibria, pH, K values, 19     1.8 Fundamentals of redox chemistry and chemical reactions, 21     1.9 Chemical reactions, 23     1.10 Equilibrium, thermodynamics and driving forces for reactions: systems, gibbs energies, enthalpy and heat capacity, entropy, volume, 23     1.10.1 Systems, species, phases and components, 24     1.10.2 First law of thermodynamics, 26     1.10.3 Second law of thermodynamics, 27     1.10.4 Enthalpy, 27     1.10.5 Heat capacity, 29     1.10.6 Gibbs free energy, 30     1.10.7 Gibbs free energy and the equilibrium constant, 31     1.11 Kinetics and reaction rates: distance from equilibrium, activation energy, metastability, 33     1.11.1 Reaction rate, reaction order, 34     1.11.2 Temperature and the Arrhenius equation, 36     Review questions, 37     References, 37     2 SURFICIAL AND ENVIRONMENTAL MINERALOGY, 39     2.1 Introduction to minerals and unit cells, 40     2.2 Ion coordination, Pauling   s rules and ionic substitution, 42     2.2.1 Coordination and radius ratio, 42     2.2.2 Bond-strength considerations, 45     2.2.3 Pauling   s and Goldschmidt   s rules of ionic solids, 45     2.3 Silicates, 48     2.3.1 Nesosilicates, 49     2.3.2 Inosilicates, 50     2.3.3 Phyllosilicates, 52     2.3.4 Tectosilicates, 58     2.4 Clay minerals (T   O minerals, T   O   T minerals, interstratified clays), 58     2.4.1 Smectite, 59     2.4.2 Smectites with tetrahedrally derived layer charge, 60     2.4.3 Smectites with octahedrally derived layer charge, 60     2.4.4 Vermiculite, 62     2.4.5 Illite, 62     2.4.6 Chlorite and Berthierine, 63     2.4.7 Kaolin (kaolinite and halloysite), 63     2.4.8 Interstratified clay minerals, 64     2.4.9 Trace metals and metalloids in clay minerals, 64     2.5 Crystal chemistry of adsorption and cation exchange, 64     2.5.1 Cation exchange, 66     2.5.2 Double-layer complexes, 68     2.6 Low-temperature non-silicate minerals: carbonates, oxides and hydroxides, sulfides, sulfates, salts, 70     2.6.1 Carbonates, 70     2.6.2 Oxides and hydroxides, 71     2.6.3 Sulfides and sulfates, 72     2.6.4 Halide and nitrate salts, 74     2.7 Mineral growth and dissolution, 74     2.8 Biomineralization, 78     Review questions, 79     References, 80     3 ORGANIC COMPOUNDS IN THE ENVIRONMENT, 82     3.1 Introduction to organic chemistry: chains and rings, single, double, and triple bonds, functional groups, classes of organic     compounds, organic nomenclature, 82     3.1.1 Definition of organic compounds, 82     3.1.2 Hybridization of carbon atoms in organic compounds, 83     3.1.3 Alkanes, 84     3.1.4 Alkenes, 86     3.1.5 Functional groups, 86     3.1.6 Aromatic hydrocarbons and related compounds, 88     3.1.7 Nitrogen, phosphorus and sulfur in organic compounds, 92     3.1.8 Pharmaceutical compounds, 93     3.2 Natural organic compounds at the earth surface, 94     3.2.1 Fossil fuels, 95     3.3 Fate and transport of organic pollutants, controls on bioavailability, behavior of DNAPLs and LNAPLs, biodegradation, remediation schemes, 96     3.3.1 Solid   liquid   gas phase considerations, 96     3.3.2 Solubility considerations, 97     3.3.3 Interactions of organic compounds and organisms, 98     3.3.4 Adsorption of organic compounds, 99     3.3.5 Non-aqueous phase liquids (NAPLs) in the environment, 103     3.3.6 Biodegradation, 104     3.3.7 Remediation, 105     3.4 Summary, 106     Questions, 106     References, 106     4 AQUEOUS SYSTEMS     CONTROLS ON WATER CHEMISTRY, 108     4.1 Introduction to the geochemistry of natural waters, 108     4.1.1 Geochemistry and the hydrologic cycle, 108     4.2 The structure of water     geometry, polarity and consequences, 113     4.3 Dissolved versus particulate: examples of solutions and suspensions, 114     4.3.1 Dissolved vs. particulate vs. colloidal, 115     4.4 Speciation: simple ions, polyatomic ions and aqueous complexes, 116     4.5 Controls on the solubility of inorganic elements and ions, 117     4.5.1 The ratio of ionic charge: ionic radius and its effect on solubility, 119     4.5.2 Reduction   oxidation reactions, 120     4.5.3 Half-cell reactions, 120     4.5.4 Redox reactions in the environment, 122     4.5.5 pH and acid   base consideration, 123     4.5.6 Ligands and elemental mobility, 124     4.6 Ion activities, ionic strength, TDS, 125     4.6.1 Ion activity product, 126     4.6.2 Ionic strength, 126     4.6.3 Total dissolved solids, 126     4.7 Solubility products, saturation, 127     4.8 Co-precipitation, 128     4.9 Behavior of selected elements in aqueous systems, 129     4.9.1 Examples of heavy metals and metalloids, 129     4.9.2 Eh   pH diagrams, 132     4.9.3 Silicon in solutions, 136     4.10 Effect of adsorption and ion exchange on water chemistry, 137     4.10.1 Ionic potential, hydration radius and adsorption, 138     4.10.2 Law of mass action and adsorption, 138     4.10.3 Adsorption edges, 140     4.10.4 Adsorption isotherms, 142     4.11 Other graphical representations of aqueous systems: piper and stiff diagrams, 143     4.12 Summary, 146     Questions, 147     References, 147     5 CARBONATE GEOCHEMISTRY AND THE CARBON CYCLE, 149     5.1 Carbonate geochemistry: inorganic carbon in the atmosphere and hydrosphere, 149     5.1.1 Atmospheric CO2, carbonate species and the pH of rain, 150     5.1.2 Speciation in the carbonate system as a function of pH, 151     5.1.3 Alkalinity, 152     5.1.4 Carbonate solubility and saturation, 155     5.1.5 The effect of CO2 partial pressure on stability of carbonate minerals, 157     5.1.6 The effect of mineral composition on stability of carbonate minerals, 157     5.2 The carbon cycle, 158     5.2.1 Oxidation states of carbon, 158     5.2.2 Global-scale reservoirs and fluxes of carbon, 159     5.2.3 Fixation of carbon into the crust, 161     5.2.4 Rates of flux to and from the crust, 164     5.2.5 The ocean reservoir, 166     5.2.6 Fixation of C into oceans, 166     5.2.7 Long-term viability of oceans as C sink, 168     5.2.8 The atmospheric reservoir, 171     5.2.9 Sequestration, 174     Questions, 175     References, 176     6 BIOGEOCHEMICAL CYCLES     N, P, S, 177     6.1 The nitrogen cycle, 180     6.1.1 Nitrogen valence, nitrogen species, 181     6.1.2 Processes operating within the nitrogen cycle, 182     6.1.3 Global scale reservoirs and fluxes of nitrogen, 184     6.1.4 Human perturbation of the nitrogen cycle and resulting environmental impacts, 186     6.2 The phosphorus cycle, 190     6.2.1 P cycling in soils, 191     6.2.2 The global phosphorus cycle, 193     6.2.3 Phosphorus and eutrophication, 194     6.3 Comparison of N and P, 195     6.4 The sulfur cycle, 196     6.4.1 Sulfur valence, sulfur species, 196     6.4.2 The global S cycle, 197     6.4.3 The marine S cycle, 198     6.4.4 Soils and biota, 200     6.4.5 Atmosphere, 200     6.4.6 River flux, 201     6.5 Integrating the C, N, P and S cycles, 202     Questions, 203     References, 203     7 THE GLOBAL ATMOSPHERE: COMPOSITION, EVOLUTION AND ANTHROPOGENIC CHANGE, 206     7.1 Atmospheric structure, circulation and composition, 206     7.1.1 Structure and layering of the atmosphere, 207     7.1.2 Geological record of atmospheric composition, 208     7.1.3 Climate proxies, 209     7.1.4 Orbital control on C, 210     7.1.5 Composition of the current atmosphere, 213     7.1.6 Air circulation, 214     7.2 Evaporation, distillation, CO2 dissolution and the composition of natural precipitation, 218     7.3 The electromagnetic spectrum, greenhouse gases and climate, 219     7.3.1 Electromagnetic spectrum, 219     7.3.2 Re-radiation from earth surface, 219     7.3.3 Greenhouse effect and heat trapping, 222     7.4 Greenhouse gases: structures, sources, sinks and effects on climate, 223     7.4.1 Molecular structures and vibrations of greenhouse gases, 223     7.4.2 Greenhouse gases, radiative forcing, GWPs, 224     7.4.3 Global warming, 227     Questions, 228     References, 228     8 URBAN AND REGIONAL AIR POLLUTION, 230     8.1 Oxygen and its impact on atmospheric chemistry, 231     8.2 Free radicals, 232     8.3 Sulfur dioxide, 234     8.4 Nitrogen oxides, 237     8.5 Carbon monoxide, 238     8.6 Particulate matter, 240     8.7 Lead (Pb), 242     8.8 Hydrocarbons and air quality: tropospheric ozone and photochemical smog, 242     8.9 Stratospheric ozone chemistry, 245     8.10 Sulfur and nitrogen gases and acid deposition, 249     8.11 Trace elements in atmospheric deposition: organochlorine pesticides, mercury and other trace elements, 252     8.11.1 Pesticides in air, 252     8.11.2 Hg in air, 253     8.11.3 As, Cd and Ni, 254     Questions, 255     References, 256     9 CHEMICAL WEATHERING AND SOILS, 258     9.1 Primary minerals, mineral instability, chemical weathering mechanisms and reactions, soil-forming factors, and products of chemical weathering, 258     9.1.1 Goldich stability sequence, 259     9.1.2 Weathering rates, 260     9.1.3 Chemical weathering, 261     9.1.4 Consequences of chemical weathering: dissolved species and secondary minerals, 264     9.1.5 Geochemical quantification of elemental mobility in soil, 265     9.1.6 Quantifying chemical weathering: CIA, 267     9.1.7 Soil profile, 268     9.1.8 Soil-forming factors, 268     9.1.9 Soil classification     soil orders and geochemical controls, 273     9.2 Secondary minerals, controls on their formation, and mineral stability diagrams, 275     9.2.1 Factors controlling soil mineralogy, 275     9.2.2 Mineral stability diagrams, 276     9.3 Soils and the geochemistry of paleoclimate analysis, 281     9.4 Effects of acid deposition on soils and aquatic ecosystems, 282     9.4.1 Increased solubility of Al in acidic soil solution, 283     9.4.2 Displacement of adsorbed nutrient cations, 284     9.4.3 Leaching of base cations enhanced by increased NO3 and SO4, 285     9.4.4 Decrease of soil buffering capacity and base saturation, 286     9.4.5 Acid deposition and heavy metals, 287     9.5 Soils and plant nutrients, 287     9.6 Saline and sodic soils, 289     9.7 Toxic metals and metalloids, 290     9.8 Organic soil pollutants and remediation (fuels, insecticides, solvents), 294     Questions, 295     References, 296     10 STABLE ISOTOPE GEOCHEMISTRY, 299     10.1 Stable isotopes     mass differences and the concept of fractionation, 299     10.2 Delta (  ) notation, 302     10.3 Fractionation: vibrational frequencies, temperature dependence, 304     10.3.1 Stable isotopes and chemical bond strength, 305     10.3.2 Temperature-dependent stable-isotope fractionation, 305     10.3.3 Equilibrium and non-equilibrium isotope fractionation, 307     10.4   18O and   D, 309     10.4.1 Paleotemperature analysis using oxygen and hydrogen isotopes, 314     10.4.2 Oxygen and hydrogen isotopes as tracers in the hydrologic cycle, 314     10.4.3 Application of oxygen and hydrogen isotopes to paleosol climate records, 316     10.5   15N, 316     10.6   13C, 318     10.6.1 Carbon isotope analysis of paleoenvironment, 320     10.6.2 Carbon isotopes in hydrology and chemical weathering, 321     10.7   34S, 321     10.7.1 Fraction of sulfur isotopes, 322     10.8 Non-traditional stable isotopes, 324     10.8.1   65/63Cu, 325     10.8.2   56/54Fe, 326     10.8.3   202/198Hg, 326     10.8.4   26Mg and   44/42Ca, 328     10.8.5   37/35Cl, 330     10.9 Summary, 330     Questions, 331     References, 331     11 RADIOACTIVE AND RADIOGENIC ISOTOPE GEOCHEMISTRY, 335     11.1 Radioactive decay, 335     11.1.1 Decay mechanisms and products, 336     11.1.2 Half-lives, decay rates and decay constants, 337     11.2 Radionuclides as tracers in environmental geochemistry, 341     11.2.1 206Pb/207Pb, 341     11.2.2 87Sr/86Sr, 342     11.3 Radionuclides as environmental contaminants, 342     11.3.1 Controls on U, Th and their decay products, 342     11.3.2 Refined uranium ores and associated nuclear wastes, 346     11.3.3 Geological disposal of high-level radioactive wastes, 349     11.4 Geochronology, 350     11.4.1 14C, cosmogenic radionuclides and earth-surface dating techniques, 350     11.4.2 Common radioactive decay methods of dating sediments and minerals, 359     11.4.3 234U/238U and 234U disequilibrium, 364     Questions, 367     References, 367     APPENDIX I CASE STUDY ON THE RELATIONSHIP OF VOLATILE ORGANIC COMPOUNDS (VOCs), MICROBIAL ACTIVITY, REDOX REACTIONS, REMEDIATION AND ARSENIC MOBILITY IN GROUNDWATER, 371     I.1 Site information, contaminant delineation, 371     I.2 Remediation efforts, 372     I.3 Sources of PCE and As, 374     I.4 Mobilization of arsenic, 374     References, 377     APPENDIX II INSTRUMENTAL ANALYSIS, 378     II.1 Analysis of minerals and crystal chemistry, 378     II.1.1 Electron microscopy (SEM, TEM and many other acronyms), 378     II.1.2 X-ray diffraction, 379     II.1.3 FTIR, 382     II.1.4 Elements in solution by ICP-AES, ICP-MS, AAS, 384     II.1.5 XRF, 385     II.1.6 X-ray absorption spectroscopy (XAS) techniques (EXAFS, XANES), 385     II.1.7 Isotopic analysis: mass spectrometry, 387     II.1.8 Chromatography, 389     References, 389     APPENDIX III TABLE OF THERMODYNAMIC DATA OF SELECTED SPECIES AT 1 ATM AND 25  C, 390     Index, 394