CHEMICAL AND ISOTOPIC GROUNDWATER HYDROLOGY
CONTENTS 1 INTRODUCTION—CHEMICAL AND ISOTOPIC ASPECTS OF HYDROLOGY THE CONCEALED NATURE OF GROUNDWATER GROUNDWATER COMPOSITION INFORMATION ENCODED INTO WATER DURING THE HYDROLOGICAL CYCLE QUESTIONS ASKED PHENOMENOLOGICAL CONCEPTUAL MODELS AND MATHEMATICAL MODELS ECONOMIC CONSIDERATIONS OF FIELD HYDROCHEMISTRY ENVIRONMENTAL ISSUES SUMMARY EXERCISES PART I PHYSICAL AND GEOLOGICAL CONCEPTS 2 BASIC HYDROLOGICAL CONCEPTS THE AERATED INTAKE ZONE THE SATURATED ZONE AND THE WATER TABLE AQUIFERS AND AQUICLUDES RECHARGE DISCHARGE EVAPOTRANSPIRATION PERMEABILITY, IMPERMEABILITY, AND THE SELECTION OF REPRESENTATIVE VALUES THROUGH-FLOW SYSTEMS: UNCON?NED AND CON?NED KARSTIC SYSTEMS: PATHS OF PREFERRED FLOW FLOW VELOCITY AND GROUNDWATER AGE FLOW OF WATER: BASIC OBSERVATIONS TWO BASIC EXPERIMENTS OF WATER FLOW A MODEL OF L-SHAPE THROUGH-FLOW PATHS AND ZONES OF STAGNATION DEEP BASIN COMPARTMENTS OF PRESSURIZED WATER, PETROLEUM, AND GEOTHERMAL FLUIDS THE TRADITIONAL MODEL OF U-SHAPE FLOW PATHS DISCUSSION OF THE U-SHAPE FLOW PATHS MODEL SUMMARY OF MODES OF GROUNDWATER FLOW 3 GEOLOGICAL DATA LITHOLOGY AND ITS BEARING ON WATER COMPOSITION PROPERTIES OF GEOLOGICAL MATERIALS AND THEIR BEARING ON RECHARGE AND GROUNDWATER STORAGE LAYERING AND ITS CONTROL ON GROUNDWATER FLOW FOLDED STRUCTURES AND THEIR BEARING ON FLOW DIRECTION, CON?NEMENT, AND ENTRAPMENT FAULTS CONTROLLING GROUNDWATER FLOW INTRUSIVE BODIES IN?UENCING GROUNDWATER FLOW HYDROCHEMICAL AND ISOTOPIC CHECKS OF GEOLOGICAL AND HYDROLOGICAL MODELS 4 PHYSICAL PARAMETERS WATER TABLE MEASUREMENTS INTERPRETATION OF WATER TABLE DATA GRADIENT AND FLOW DIRECTION THE NEED FOR COMPLEMENTING DATA TO CHECK DEDUCED GRADIENTS AND FLOW DIRECTIONS VELOCITIES AND PUMPING TESTS CHEMICAL AND PHYSICAL MEASUREMENTS DURING PUMPING TESTS TEMPERATURE MEASUREMENTS TRACING GROUNDWATER BY TEMPERATURE—A FEW CASE STUDIES: THE MOHAWK RIVER COLD AND HOT GROUNDWATER SYSTEMS DISCHARGE MEASUREMENTS AND THEIR INTERPRETATIVE VALUE PART II CHEMICAL TOOLS OF GROUNDWATER HYDROLOGY 5 ELEMENTS, ISOTOPES, IONS, UNITS, AND ERRORS ELEMENTS ISOTOPES ATOMIC WEIGHT IONS AND VALENCES IONIC COMPOUNDS CONCENTRATION UNITS REPRODUCIBILITY, ACCURACY, RESOLUTION, AND LIMIT OF DETECTION ERRORS AND SIGNI?CANT FIGURES CHECKING THE LABORATORY EVALUATION OF DATA QUALITY BY DATA PROCESSING TECHNIQUES PUTTING LIFE INTO A DRY TABLE EVALUATION OF CALCULATED REPRODUCIBILITIES AND REACTION ERRORS 6 CHEMICAL PARAMETERS: DATA PROCESSING DATA TABLES FINGERPRINT DIAGRAMS COMPOSITION DIAGRAMS MAJOR PATTERNS SEEN IN COMPOSITION DIAGRAMS ESTABLISHING HYDRAULIC INTERCONNECTIONS MIXING PATTERNS END MEMBER PROPERTIES AND MIXING PERCENTAGES WATER–ROCK INTERACTIONS AND THE TYPES OF ROCKS PASSED WATER COMPOSITION: MODES OF DESCRIPTION COMPOSITIONAL TIME SERIES SOME CASE STUDIES SATURATION AND UNDERSATURATION WITH REGARD TO HALITE AND GYPSUM: THE HYDROCHEMICAL IMPLICATIONS SEA-DERIVED (AIRBORNE) IONS: A CASE STUDY DEMONSTRATING THE PHENOMENON SOURCES OF CHLORINE IN GROUNDWATER EVAPOTRANSPIRATION INDEX: CALCULATION BASED ON CHLORINE AS A HYDROCHEMICAL MARKER CO2-INDUCED WATER–ROCK INTERACTIONS REVEALED BY CHLORINE SERVING AS A HYDROCHEMICAL MARKER 7 PLANNING HYDROCHEMICAL STUDIES REPRESENTATIVE SAMPLES DATA COLLECTION DURING DRILLING DEPTH PRO?LES DATA COLLECTION DURING PUMPING TESTS IMPORTANCE OF HISTORICAL DATA REPEATED OBSERVATIONS, OR TIME-DATA SERIES SEARCH FOR MEANINGFUL PARAMETERS SAMPLING FOR CONTOUR MAPS SAMPLING ALONG TRANSECTS RECONNAISSANCE STUDIES DETAILED STUDIES POLLUTION-RELATED STUDIES SUMMARY: A PLANNING LIST 8 CHEMICAL PARAMETERS: FIELD WORK FIELD MEASUREMENTS SMELL AND TASTE TEMPERATURE ELECTRICAL CONDUCTANCE DISSOLVED OXYGEN ALKALINITY SAMPLING FOR DISSOLVED ION ANALYSES SAMPLING FOR ISOTOPIC MEASUREMENTS PRESERVATION OF SAMPLES EF?ORESCENCES EQUIPMENT LIST FOR FIELD WORK PART III ISOTOPIC TOOLS OF GROUNDWATER HYDROLOGY: WATER IDENTI?CATION AND DATING 9 STABLE HYDROGEN AND OXYGEN ISOTOPES ISOTOPIC COMPOSITION OF WATER MOLECULES UNITS OF ISOTOPIC COMPOSITION OF WATER ISOTOPIC FRACTIONATION DURING EVAPORATION AND SOME HYDROLOGICAL APPLICATIONS THE METEORIC ISOTOPE LINE TEMPERATURE EFFECT AMOUNT EFFECT CONTINENTAL EFFECT ALTITUDE EFFECT TRACING GROUNDWATER WITH DEUTERIUM AND 18O: LOCAL STUDIES TRACING GROUNDWATER WITH DEUTERIUM AND 18O: A REGIONAL STUDY THE NEED FOR MULTISAMPLING SAMPLE COLLECTION FOR STABLE HYDROGEN AND OXYGEN ISOTOPES AND CONTACT WITH RELEVANT LABORATORIES 10 TRITIUM DATING THE RADIOACTIVE HEAVY HYDROGEN ISOTOPE NATURAL TRITIUM PRODUCTION MANMADE TRITIUM INPUTS TRITIUM AS A SHORT-TERM AGE INDICATOR TRITIUM AS A TRACER OF RECHARGE AND PISTON FLOW: OBSERVATIONS IN WELLS THE SPECIAL ROLE OF TRITIUM IN TRACING INTERMIXING OF OLD AND RECENT WATERS AND CALCULATION OF THE EXTRAPOLATED PROPERTIES OF THE END MEMBERS TRITIUM, DISSOLVED IONS, AND STABLE ISOTOPES AS TRACERS FOR RAPID DISCHARGE ALONG FRACTURES: THE MONT BLANC TUNNEL CASE STUDY THE TRITIUM-3HE GROUNDWATER DATING METHOD SAMPLE COLLECTION FOR TRITIUM MEASUREMENTS 10 10 SUMMARY EXERCISES 11 RADIOCARBON DATING THE ISOTOPES OF CARBON NATURAL 14C PRODUCTION MANMADE 14C DILUTION AND ADDITION 14C IN GROUNDWATER: AN INTRODUCTION TO GROUNDWATER DATING LOWERING OF 14C CONTENT BY REACTIONS WITH ROCKS 13C ABUNDANCES AND THEIR RELEVANCE TO 14C DATING OF GROUNDWATER APPLICATION OF D13C TO CORRECT OBSERVED 14C VALUES FOR CHANGES CAUSED BY INTERACTIONS WITH CARBONATE ROCKS DIRECTION OF DOWN-GRADIENT FLOW AND GROUNDWATER AGE STUDIED BY 14C: CASE STUDIES FLOW DISCONTINUITIES BETWEEN ADJACENT PHREATIC AND CON?NED AQUIFERS INDICATED BY 14C AND OTHER PARAMETERS 11 10 MIXING OF GROUNDWATERS REVEALED BY JOINT INTERPRETATION OF TRITIUM AND 14C DATA 11 11 PISTON FLOW VERSUS KARSTIC FLOW REVEALED BY 14C DATA 11 12 SAMPLE COLLECTION FOR 14C AND 13C ANALYSES AND CONTACT WITH RELEVANT LABORATORIES 11 13 SUMMARY EXERCISES 12 CHLORINE-36 DATING THE RADIOACTIVE ISOTOPE OF CHLORINE AND ITS PRODUCTION A POTENTIAL TOOL FOR GROUNDWATER DATING PROCESSES CONTROLLING THE 36CL CONCENTRATION IN GROUNDWATER GROUNDWATER DATING BY 36CL A NUMBER OF CASE STUDIES SUMMARY 13 THE NOBLE GASES RARE, INERT, OR NOBLE? ATMOSPHERIC NOBLE GASES AND THEIR DISSOLUTION IN WATER GROUNDWATER AS A CLOSED SYSTEM FOR ATMOSPHERIC NOBLE GASES STUDIES ON ATMOSPHERIC NOBLE GAS RETENTION IN GROUNDWATER SYSTEMS: COLD GROUNDWATER FURTHER CHECKS ON ATMOSPHERIC NOBLE GAS RETENTION: WARM GROUNDWATER IDENTI?CATION OF THE NATURE OF THE UNSATURATED RECHARGE ZONE: A POROUS MEDIUM OR A KARSTIC SYSTEM DEPTH OF CIRCULATION AND LOCATION OF THE RECHARGE ZONE PALEOTEMPERATURES SAMPLE COLLECTION FOR NOBLE GAS MEASUREMENTS 13 10 SUMMARY EXERCISES 14 HELIUM-4 AND ARGON-40 LONG RANGE DATING SOURCES OF RADIOGENIC 4HE DISSOLVED IN GROUNDWATER PARAMETERS DETERMINING HELIUM CONCENTRATION IN GROUNDWATER CASE STUDIES AND OBSERVED TRENDS IN THE DISTRIBUTION OF HELIUM CONCENTRATIONS IN GROUNDWATER SYSTEMS MANTLE HELIUM THE HELIUM-BASED GROUNDWATER AGE EQUATION COMPARISON OF HELIUM-BASED WATER AGES AND HYDRAULICALLY CALCULATED AGES DOES HELIUM DIFFUSE THROUGH THE UPPER CRUST? HELIUM CONCENTRATION INCREASES WITH DEPTH: GROUNDWATER ACTS AS A SINK OF HELIUM EFFECT OF MIXING OF GROUNDWATERS OF DIFFERENT AGES ON THE OBSERVED HELIUM CONCENTRATION 14 10 HELIUM LOSS OR GAIN DUE TO PHASE SEPARATION UNDERGROUND OR DURING ASCENT TO THE SAMPLING POINT: MODES OF IDENTI?CATION AND CORRECTION 14 11 INTERNAL CHECKS FOR HELIUM AGES 14 12 THE ISSUE OF VERY OLD GROUNDWATERS 14 13 CONCLUSIONS 14 14 SUMMARY EXERCISES 15 PALEOCLIMATE, PALEOHYDROLOGY, AND GROUNDWATER DATING INTERRELATIONS SCOPE OF THE PROBLEM THE NEED TO RECONSTRUCT PALEO-INPUT VALUES STAGNANT SYSTEMS AS FOSSIL THROUGH-FLOW SYSTEMS SCREENING OF DATA FOR SAMPLES OF ‘‘LAST MINUTE’’ MIXING OF GROUNDWATERS OF DIFFERENT AGES PALEOHYDROLOGICAL CHANGES PALEOCLIMATE CHANGES SELECTING SITES FOR NOBLE GAS BASED PALEOTEMPERATURE STUDIES STAGES OF DATA PROCESSING PART IV MAN AND WATER 16 DETECTING POLLUTION SOURCES DETECTION AND MONITORING OF POLLUTANTS: SOME BASIC RULES GROUNDWATER POLLUTION CASE STUDIES SUMMARY OF CASE STUDIES 17 SUSTAINABLE DEVELOPMENT OF GROUNDWATER—URBAN AND STATEWIDE MANAGEMENT SUSTAINABLE DEVELOPMENT MAN AND GROUNDWATER: A HISTORICAL PERSPECTIVE THE CONCERN OVER GROUNDWATER QUALITY: A LEVER FOR THE DEMAND OF CLEAN NATIONWIDE MANAGEMENT THE VALUE OF THE ENVIRONMENT: AN ESSENTIAL PARAMETER IN ECONOMIC CALCULATIONS RECHARGE AND ITS CONTROLS OVERPUMPING POLICY: THE THROUGH-FLOW SYSTEMS OPTIMIZATION OF PUMPING RATES IN THE THROUGH-FLOW SYSTEM OPTIMAL UTILIZATION OF THE GROUNDWATER RESOURCE GROUNDWATER ASPECTS OF URBAN AND STATEWIDE DEVELOPMENT PLANNING AND MANAGEMENT 17 10 SUMMARY EXERCISES 18 WATER QUALITY STANDARDS, MONITORING, DATA BANKS, AND EDUCATION ACTIVITIES DRINKING WATER STANDARDS WATER MONITORING NETWORKS ACTIVE AND EF?CIENT DATA BANKS—THE STRUCTURE AND THE CHALLENGES WATER-RELATED EDUCATION ACTIVITIES 19 HYDROCHEMISTS’ REPORTS WHY REPORTS? TYPES OF REPORTS INTERNAL STRUCTURE OF REPORTS ANSWERS TO EXERCISE QUESTIONS REFERENCES XII GROUNDWATER COMPOSITION WATER MOLECULES ARE BUILT OF TWO ELEMENTS: HYDROGEN (H) AND OXYGEN (O) THE GENERAL FORMULA IS H2O DIFFERENT VARIETIES OF ATOMS WITH DIFFERENT 4 ), DISCUSSED IN SECTION 5 5 THE COMPOSITION OF GROUNDWATER, THAT IS, THE CONCENTRATION OF THE DIFFERENT IONS, VARIES OVER A WIDE RANGE OF VALUES WATER ALSO CONTAINS DISSOLVED GASES A MAJOR SOURCE IS AIR, CONTRIBUTING NITROGEN (N2), OXYGEN (O2), AND NOBLE GASES (CHAPTER 13)— HELIUM (HE), NEON (NE), ARGON (AR), KRYPTON (KR), AND XENON (XE) OTHER GASES, OF BIOGENIC ORIGIN, ARE ADDED TO THE WATER IN THE GROUND, FOR EXAMPLE, CARBON DIOXIDE (CO2), METHANE (CH4), AND HYDROGEN SUL?DE (H2S) BIOGENIC PROCESSES MAY CONSUME THE DISSOLVED OXYGEN COSMIC RAYS INTERACT WITH THE UPPER ATMOSPHERE AND PRODUCE A VARIETY OF RADIOACTIVE ISOTOPES, THREE OF WHICH ARE OF SPECIAL HYDROLOGICAL INTEREST: (1) 3H, BETTER KNOWN AS TRITIUM (T), THE HEAVIEST HYDROGEN ISOTOPE, (2) CARBON-14 (14C), THE HEAVIEST ISOTOPE OF CARBON, AND (3) CHLORINE-36 (36CL), A RARE ISOTOPE OF CHLORINE THE RATE OF RADIOACTIVE DECAY IS EXPRESSED IN TERMS OF HALF-LIFE, THAT IS, THE TIME REQUIRED FOR ATOMS IN A GIVEN RESERVOIR TO DECAY TO HALF THEIR INITIAL NUMBER THE THREE RADIOACTIVE ISOTOPES—TRITIUM, 14C, AND 36CL—ARE INCORPORATED INTO GROUNDWATER THEY DECAY IN THE SATURATED ZONE (SECTION 2 2), PROVIDING THREE SEMIQUANTITATIVE DATING TOOLS—FOR PERIODS OF A FEW DECADES, TO 25,000 YEARS, AND 105 TO 106 YEARS (RESPECTIVELY, SECTIONS 10 4, 11 4, AND 12 2) THE THREE ISOTOPES ALSO HAVE BEEN PRODUCED BY NUCLEAR BOMB TESTS, COMPLICATING THE PICTURE BUT PROVIDING ADDITIONAL INFORMATION ROCKS CONTAIN URANIUM AND THORIUM IN SMALL CONCENTRATIONS, AND THEIR RADIOACTIVE DECAY RESULTS IN THE PRODUCTION OF RADIOGENIC HELIUM-4 (4HE) THE HELIUM REACHES THE GROUNDWATER AND IS DISSOLVED AND STORED WITH TIME, CHAPTER