Groundwater Age

Acknowledgments.

Chapter 1. Introduction.

1.1 Age and lifetime.

1.2 Age determination in geology (Geochronology) and in other disciplines.

1.2.1 Absolute age and relative age.

1.2.2 Determination of absolute age of rocks.

1.2.3 Geological time table.

1.3 Groundwater age and groundwater residence time.

1.3.1 Young, old and very old groundwaters.

1.3.2 Dead water and active water.

1.3.3 Age gradient.

1.3.4 Age mass.

1.3.5 Mixing, dispersion and transport of groundwater age, mean age and distribution of ages.

1.3.6 Average residence time of water in various compartments of the hydrologic cycle .

1.3.7 Hydrogeochronolgy, interdisciplinary groundwater age science and hydrologic time concept.

1.3.8 Event markers.

1.4 Life expectancy.

1.5 Isochrone and life expectancy maps.

1.6 Some groundwater age related terms.

1.6.1 Isotopic age, radiometric age and decay age.

1.6.2 Hydraulic age.

1.6.3 Piston-flow age, streamtube age and advective age .

1.6.4 Model age and apparent age.

1.6.5 Storage time, mean transit time, turn over time, flushing time and travel time.

1.6.6 Reservoir theory and its relation with groundwater residence time.

Chapter 2. History of groundwater age dating research.

2.1 Pioneer of Groundwater Age discipline-sequence of the earliest publications.

2.2 Laboratories worldwide for dating groundwater samples.

2.3 Major contributors to Groundwater Age dating discipline.

2.4 Names familiar in the Groundwater Dating business.

2.5 Important publications.

2.5.1 Book chapters.

2.5.2 PhD and MSc theses.

2.5.3 Journals.

2.5.4 Reports (mainly by the USGS) .

2.6 Aquifers subjected to extensive dating studies.

Chapter 3. The applications of groundwater age data.

3.1 Renewability of the groundwater reservoirs.

3.2 An effective communication tool for scientists and managers- and curiosity to laymen as well.

3.3 Age monitoring for the prevention of over exploitation and contamination of aquifers.

3.4 Estimation of the recharge rate.

3.5 Calculation of the groundwater flow velocity.

3.6 Identification of the groundwater flow paths.

3.7 Assessing the rates of groundwater and contaminants transport through aquitards.

3.8 Constraining the parameters of groundwater flow and transports models (estimation of large scale flow and transport properties).

3.9 Identification of the mixing between different end members.

3.10 Study of the pre-Holocene (late Pleistocene) climate.

3.11 Evaluation of the groundwater pollution.

3.12 Calculation of the travel time of the groundwater plume to the points of interest.

3.13 Mapping vulnerability of the shallow aquifers.

3.14 Performance assessments for radioactive waste disposal facilities.

3.15 Site specific applications.

3.15.1 Identification of the seawater level fluctuations.

3.15.2 Calculating the timescale of seawater intrusion.

3.15.3 Disposal of wastes into the deep old saline groundwater systems.

3.15.4 Management of the dryland salinity in Australia.

3.15.5 Hydrograph separation.

Chapter 4. Age-dating young groundwaters.

4.1 Important points.

4.2 Tritium.

4.2.1 Production of tritium.

4.2.2 Sampling, analyzing and reporting the results.

4.2.3 Age dating groundwater by tritium.

4.2.4 Advantages and disadvantages.

4.2.5 Case studies.

4.3 3H/3He.

4.3.1 Sources of 3He.

4.3.2 Sampling, analysis and reporting the results.

4.3.3 Dating groundwater by 3H/3He.

4.3.4 Advantages and disadvantages.

4.3.5 Case studies.

4.4 Helium-4.

4.5 Krypton-85.

4.5.1 Production of 85Kr.

4.5.2 Sampling and analyzing groundwater for 85Kr.

4.5.3 Age dating groundwater with 85Kr.

4.5.4 Advantages and disadvantages.

4.5.5 Case studies.

4.6 CFCs.

4.6.1 Sampling and analyzing groundwater for CFCs.

4.6.2 Dating groundwater by CFCs.

4.6.3 Limitations and possible sources of error in CFCs dating technique.

4.6.4 Advantages and disadvantages.

4.6.5 Case studies.

4.7 SF6.

4.7.1 Sampling and analyzing groundwater for SF6.

4.7.2 Age dating groundwater with SF6.

4.7.3 Advantages and disadvantages.

4.7.4 Case studies.

4.8 36Cl/Cl.

4.8.1 Dating groundwater by 36Cl/Cl ratio and case studies.

4.9 Indirect methods.

4.9.1 Stable isotopes of water.

4.9.2 Case study.

Chapter 5. Age-dating old groundwaters.

5.1 Silicon-32.

5.1.1 Production of 32Si.

5.1.2 Sampling and analyzing groundwater for 32Si.

5.1.3 Dating groundwater with 32Si.

5.1.4 Advantages and disadvantages.

5.1.5 Case studies.

5.2 Argon-39.

5.2.1 Production and sources of 39Ar.

5.2.2 Sampling and analyzing groundwaters for 39Ar .

5.2.3 Age dating groundwater by 39Ar.

5.2.4 Advantages and disadvantages.

5.2.5 Case studies.

5.3 Carbon-14.

5.3.1 Production of 14C.

5.3.2 Sampling, analysis and reporting the results.

5.3.3 Groundwater dating by 14C.

5.3.4 Advantages and disadvantages.

5.3.5 Case study.

5.4 Indirect methods.

5.4.1 Deuterium and oxygen-18.

5.4.2 Conservative and reactive ions.

Chapter 6. Age-dating very old groundwaters.

6.1 Krypton-81.

6.1.1 Production of 81Kr.

6.1.2 Sampling, analysis and reporting the results.

6.1.3 Age-dating groundwater by 81Kr.

6.1.4 Advantages and disadvantages.

6.1.5 Case studies.

6.2 Chloride-36.

6.2.1 Production of 36Cl.

6.2.2 Sampling, analysis and reporting the results.

6.2.3 Groundwater dating by 36Cl.

6.2.4 Advantages and disadvantages.

6.2.5 Case studies.

6.3 Helium-4.

6.3.1 Production and sources of 4He.

6.3.2 Sampling, analysis and reporting the results.

6.3.3 Age-dating groundwater by 4He.

6.3.4 Advantages and disadvantages.

6.3.5 Case studies.

6.4 Argon-40.

6.4.1 Sampling, analysis and reporting the results.

6.4.2 Age-dating groundwater by 40Ar and obstacles.

6.4.3 Case studies.

6.5 Iodine-129.

6.5.1 Production of 129I .

6.5.2 Sampling, analysis and reporting the results.

6.5.3 Age-dating groundwater by 129I.

6.5.4 Advantages and disadvantages.

6.5.5 Case studies.

6.6 Uranium disequilibrium series.

6.6.1 Sampling, analysis and reporting the results.

6.6.2 Dating groundwater by UDS.

6.6.3 Case studies.

Chapter 7. Modeling of groundwater age and residence time distributions.

7.1 Overview and state-of-the-art.

7.2 Basics in groundwater age transport.

7.2.1 The reservoir theory.

7.2.2 Determination of age and residence time distributions.

7.3 Selected typical examples.

7.3.1 Aquifer with uniform and localized recharge.

7.3.2 Hydro-dispersive multilayer aquifer.

7.3.3 The Seeland phreatic aquifer.

Chapter 8. Issues and thoughts in groundwater dating.

8.1 The need for more dating methods and the currently proposed potential method.

8.2 Translating simulation of groundwater ages techniques into practice- More applications for age data.

8.3 Worldwide practices of groundwater age-dating.

8.4 Proposal for a groundwater age map - Worldwide groundwater age maps.

8.5 Works which can and need to be done to enhance groundwater age science.

8.5 Major problems facing groundwater dating discipline.

8.7 Some thoughtful questions - Concluding remarks and Future of groundwater dating.

References.

Appendix 1: Decay Curves of Groundwater Dating Isotopes. That of Tritium Is Shown in Chapter 4.

Appendix 2: Some Useful Information for Groundwater Dating Studies and Table of Conversion of Units.

Appendix 3: Concentration of Noble Gases (Used in Groundwater Dating) and Some Important Constituents of the Atmosphere.

Index.