Environmental and Low-Temperature Geochemistry

PETER RYAN is Professor of Geology and Environmental Studies at Middlebury College where he teaches courses in environmental geochemistry, hydrology, sedimentary geology and interdisciplinary environmental studies. He received a Ph.D. in geology at Dartmouth College, an M.S. in geology from the University of Montana and a B.A. in earth sciences from Dartmouth College. He has served as Director of the Program in Environmental Studies and as Chair of the Department of Geology at Middlebury College. His research interests fall into two main areas: (1) understanding the geological and mineralogical controls on trace element speciation, particularly the occurrence and mobility of arsenic and uranium in bedrock aquifers; and (2) the temporal evolution of soils in the tropics, with emphasis on mechanisms and rates of mineralogical reactions, nutrient cycling and application of soil geochemical analysis to correlation and geological interpretation.

• Preface xiiiAcknowledgements xv1 Background and Basic Chemical Principles: Elements, Ions, Bonding, Reactions 11.1 An Overview of Environmental Geochemistry – History, Scope, Questions, Approaches, Challenges for the Future 11.2 The Naturally Occurring Elements – Origins and Abundances 31.3 Atoms, Isotopes, and Valence Electrons 61.4 Measuring Concentrations 81.5 Periodic Table 121.6 Ions, Molecules, Valence, Bonding, Chemical Reactions 131.7 Acid–Base Equilibria, PH, K Values 181.8 Fundamentals of Redox Chemistry 201.9 Chemical Reactions 221.10 Equilibrium, Thermodynamics, and Driving Forces for Reactions: Systems, Gibbs Energies, Enthalpy and Heat Capacity, Entropy, Volume 231.11 Kinetics and Reaction Rates 31Questions 35References 362 Surficial and Environmental Mineralogy 392.1 Introduction to Minerals and Unit Cells 392.2 Ion Coordination, Pauling’s Rules, and Ionic Substitution 412.3 Silicates 462.4 Clay Minerals (1 : 1 and 2 : 1 Minerals, Interstratified Clays) 552.5 Crystal Chemistry of Adsorption and Cation Exchange 602.6 Low-Temperature Non-Silicate Minerals: Carbonates, Oxides and Hydroxides, Sulfides, Sulfates, Salts 642.7 Mineral Growth and Dissolution 682.8 Biomineralization 72Questions 72References 733 Organic Compounds in the Environment 753.1 Introduction to Organic Chemistry: Chains and Rings, Single, Double, and Triple Bonds, Functional Groups, Classes of Organic Compounds, Organic Nomenclature 753.2 Natural Organic Compounds at the Earth Surface 873.3 Fate and Transport of Organic Pollutants, Controls on Bioavailability, Behavior of DNAPLS and LNAPLS, Biodegradation, Remediation 883.4 Summary 96Questions 96References 974 Aqueous Systems and Water Chemistry 994.1 Introduction to the Geochemistry of Natural Waters 994.2 The Structure of Water – Implications of Geometry and Polarity 1034.3 Dissolved versus Particulate, Solutions, and Suspensions 1044.4 Speciation: Simple Ions, Polyatomic Ions, and Aqueous Complexes 1064.5 Controls on the Solubility of Inorganic Elements and Ions 1064.6 Ion Activities, Ionic Strength, TDS 1134.7 Solubility Products, Saturation 1154.8 Coprecipitation 1164.9 Behavior of Selected Elements in Aqueous Systems 1174.10 Eh–pH Diagrams 1194.11 Silicon in Solution 1234.12 Effect of Adsorption and Ion Exchange on Water Chemistry 1234.13 Other Graphical Representations of Aqueous Systems: Piper and Stiff Diagrams 1284.14 Summary 131Questions 131References 1315 Carbonate Geochemistry and the Carbon Cycle 1335.1 Inorganic Carbon in the Atmosphere and Hydrosphere 1335.2 The Carbon Cycle 141Questions 154References 1556 Biogeochemical Systems and Cycles (N, P, S) 1576.1 Systems and Elemental Cycles 1576.2 Elemental Cycles 159Questions 178References 1787 The Global Atmosphere: Composition, Evolution, and Anthropogenic Change 1817.1 Atmospheric Structure, Circulation, and Composition 1817.2 Evaporation, Distillation, CO2 Dissolution, and the Composition of Natural Precipitation 1907.3 The Electromagnetic Spectrum, Greenhouse Gases, and Climate 1917.4 Greenhouse Gases: Structures, Sources, Sinks, and Effects on Climate 194Questions 198References 1998 Air Quality: Urban and Regional Pollutants 2018.1 Air Pollution: Definitions and Scope 2018.2 Oxygen and its Impact on Atmospheric Chemistry 2028.3 Free Radicals 2028.4 Sulfur Dioxide 2048.5 Nitrogen Oxides 2068.6 Carbon Monoxide 2098.7 Particulate Matter 2098.8 Lead (Pb) 2108.9 Hydrocarbons and Air Quality: Tropospheric Ozone and Photochemical Smog 2118.10 Stratospheric Ozone Chemistry 2138.11 Sulfur and Nitrogen and Acid Deposition 2158.12 Organochlorine Pesticides, Mercury, and Other Trace Constituents in the Atmosphere 219Questions 222References 2229 Chemical Weathering, Soils, and Hydrology 2259.1 Chemical Weathering of Primary Minerals in Soils 2259.2 Products and Consequences of Chemical Weathering 2319.3 Soil Profiles, Nomenclature, Soil-Forming Factors 2399.4 Soils and the Geochemistry of Paleoclimate Analysis 2439.5 Effects of Acid Deposition on Soils and Aquatic Ecosystems 2459.6 Soils and Plant Nutrients 2489.7 Saline and Sodic Soils 2499.8 Toxic Metals and Metalloids 2519.9 Organic Soil Pollutants and Remediation (Fuels, Insecticides, Solvents) 254Questions 256References 25610 Stable Isotope Geochemistry 25910.1 Stable Isotopes – Mass Differences and the Concept of Fractionation 25910.2 Delta (δ) Notation 26110.3 Fractionation: Vibrational Frequencies, Mass, and Temperature Dependence 26310.4 δ18O and δD 26710.5 δ15N 27310.6 δ13C 27510.7 δ34S 27810.8 Nontraditional Stable Isotopes 28010.9 Summary 285Questions 285References 28611 Radioactive and Radiogenic Isotopegeochemistry 28911.1 Radioactive Decay 28911.2 Radionuclide Tracers in Environmental Geochemistry 29411.3 Radionuclides as Environmental Contaminants 29511.4 Geochronology 30111.5 Radioactive Decay Methods of Dating Sediments and Minerals 309Questions 315References 315Appendix I Case Study on the Relationships among Volatile Organic Compounds (VOCS), Microbial Activity, Redox Reactions, Remediation, and Arsenic Mobility in Groundwater 319I.1 Site Information, Contaminant Delineation 319I.2 Remediation Efforts 320I.3 Sources of PCE and ARSENIC 320I.4 Mobilization of Arsenic 322References 323Appendix II Case Study of PFOA Migration in a Fractured Rock Aquifer: Using Geochemistry to Decipher Causes of Heterogeneity 325II.1 Geologic Framework 326II.2 Inorganic Chemistry of Groundwater 326II.3 Stable Isotope Compositions of Groundwater 327II.4 Groundwater Age-Dating 328II.5 Conceptual Model for the Groundwater System 328References 329Appendix III Instrumental Analysis 331III.1 Analysis of Minerals and Crystal Chemistry 331III.2 Chemical Analysis of Rocks and Sediments: XRF 337III.3 Elements or Compounds in Solution 338III.4 Isotopic Analysis: Mass Spectrometry 339References 340Appendix IV Table of Thermodynamic Data of Selected Species at 1 ATM and 25 ∘C 341References 344Index 345