Evaluation of Salinisation Processes in the Spicers Creek Catchment, Central West Region of New South Wales, Australia

EVALUATION OF SALINISATION PROCESSES IN THE SPICERS CREEK CATCHMENT, CENTRAL WEST REGION OF NEW SOUTH WALES, AUSTRALIA.

KARINA MORGAN

A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy

School of Biological, Earth and Environmental Sciences The University of New South Wales

March 2005

Concern for man himself and his safety must always form the chief interest of all our technical endeavours. Never forget this in the midst of your diagrams and equations. Albert Einstein

Originality Statement ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project’s design and conception or in style, presentation and linguistic expression is acknowledged.’

------Karina Morgan March 2005

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ABSTRACT Spicers Creek catchment is located approximately 400 km west of Sydney in the Central West region of New South Wales, Australia. Dryland salinity has been recognised as a major environmental issue impacting soil and water resources in the Central West region of NSW for over 70 years. Due to the geological complexity of the catchment and the presence of high salt loads contained within the soils, groundwater and surface waters, the Spicers Creek catchment was identified as a large contributor of salinity to the Macquarie River catchment. Over fifty-two dryland salinity occurrences have been identified in the Spicers Creek catchment and it appears that dryland salinity is controlled by the presence of geological structures and permeability contrasts in the shallow aquifer system. Combinations of climatic, geological and agricultural factors are escalating salinity problems in the catchment. The main aim of this thesis was to identify the factors affecting salinisation processes in the Spicers Creek catchment. These include the role of geological structures, the source(s) of salts to the groundwater system and the geochemical processes influencing seepage zone development. To achieve these aims a multidisciplinary approach was untaken to understand the soils, geology, hydrogeology and hydrogeochemistry of the catchment. Investigative techniques employed in this project include the use of geophysics, soil chemistry, soil spectroscopy, hydrogeochemistry and environmental isotopes. Evaluation of high-resolution airborne magnetics data showed a major north-east to south-west trending shear zone. This structure dissects the catchment and several other minor faults were observed to be splays off this major structure. These structures were found to be conducive to groundwater flow and are influencing the groundwater chemistry in the fractured aquifer system. Two distinctive groundwater chemical types were identified in the catchment; the saline Na(Mg)-Cl-rich groundwaters associated with the fractured Oakdale Formation and the Na-HCO3-rich groundwaters associated with the intermediate groundwater system. The groundwater chemistry of other deep groundwaters in the catchment appears to be due to mixing between these end-member groundwaters within the fractured bedrock system. The spatial distribution of electrical conductivity, Cl-, Sr2+ and 87Sr/86Sr isotopic ratios showed the correlation between saline groundwaters and the location of faults. Elevated salinities were associated with the location of two crosscutting fault zones. The spatial - + + 13 distribution of HCO3 , K , Li and δ CDIC highlighted the extent of Na-HCO3-rich groundwaters in the catchment and showed that these groundwaters are mixing further east than previously envisaged. These findings show that Na(Mg)-Cl-rich groundwaters are geochemically distinctive and have evolved due to extensive water-rock interaction processes within the fracture zones of the Oakdale Formation. These saline groundwaters contain elevated concentrations of trace elements such as As, V and Se, which pose a potential risk for water resources in the area. 87Sr/86Sr isotopic ratios indicated that the source of salinity to the Na(Mg)-Cl-rich groundwaters was not purely from marine or aerosol input. Salt is most likely contributed from various allochthonous and autochthonous sources. This research found that the main mechanism controlling the formation of dryland salinity seepage zones in the Spicers Creek catchment is due to the presence of geological structures. These groundwater seepage zones act as mixing zones for rainfall recharge and deeper groundwaters. The main sources of salt to the seepage zones are from deeper Na(Mg)-Cl-rich groundwaters and rainfall accession. The major importance of this research highlights the need for an integrated approach for the use of various geoscientific techniques in dryland salinity research within geologically complex environments.

ACKNOWLEDGEMENTS

Firstly, I would like to thank my wonderful husband Gavin Meredith for all his unconditional love, perseverance and patience. Thankyou so much for your editorial assistance, entering references and checking that the final copy was in “order”. You’re the absolute best! It’s hard to believe that we can finally start living again. I can’t wait!

I would now like to thank Dr Wendy McLean for all her encouragement and support. Without you, this thesis would not be what it is today. Thankyou so much for reviewing the manuscript and for help with the last minute details such as entering references. Most of all thankyou for being my “mucho besto”. Here’s to everything seeming so much easier!

Thankyou to my family Peter, Barbara, Braddon and Haydon Morgan and my extended family Barry, Robyn and Tina Meredith for their constant love and support.

I would like to thank Department of Infrastructure, Natural Resources and Planning for funding towards this project and to the Australian Postgraduate Award for financial support. I would like to thank my supervisor Dr Jerzy Jankowski for his guidance, technical assistance and help in the field. I would also like to thank my co-supervisor Associate Professor Geoffrey Taylor for his support and help with reviewing the manuscript. Thankyou for your constant enthusiasm it has been inspiring.

A huge thankyou goes out to the marvellous people who assisted me in the field with hydrochemical analyses; Jessica Northey, Sarah Groves, Gavin Meredith and Jerzy Jankowski. To Dorothy Yu for ICP-MS and ICP-AES analysis. To Ramin Nikrov and Derek Palmer for help with the geophysics. To Casey Edwards and Geoff Taylor for their help with the soil spectroscopy component of the project. I would also like to thank Russel Millard for drilling and technical assistance in the field and to the Simpson family who provided me with rainfall data and allowed me to drill holes in their paddocks.

To my fellow PhD students at UNSW and ERM work mates, thankyou all so much for your friendship, support and encouragement, you are all great people.

Lastly, I would like to thank the landholders of the Spicers Creek catchment for giving me the opportunity to conduct this research.

PUBLICATIONS Morgan K, Jankowski J. 2002. Determination of the source of salinity within the dryland salinity affected Spicers Creek catchment, central west, NSW, Australia. In Proceedings of the 27th Hydrology and Water Resources Symposium, Melbourne, May 20-23.

Morgan, K, Jankowski J. 2002. Dryland salinity and its impact on agricultural activities in Spicers Creek catchment, Central West, NSW, Australia. In Proc 32nd Congr Int Association Hydrogeology. Bocanegra E, Martinez D, Massone H (eds). 21-25 October 2002, Universidad Nacional de Mar Del Plata, Argentina pp 443- 453.

Morgan K, Jankowski J, Taylor G. 2002. Identification of dryland salinity using combined hydrogeochemistry and spectroscopy techniques. In: Proceedings EERE 2002, Environmental Engineering Research Event. Blackheath, NSW, 3-6th December, 2002.

Morgan K, Jankowski J. 2003. Seasonal variation in groundwater chemistry in a shallow aquifer: development and management of seepage zones. In: The Institute of Engineers, Australia. 28th International Hydrology and Water Resources Symposium. 10 – 14 November 2003, Wollongong, NSW.

Morgan K, Jankowski J. 2003. Origin of salts in a fractured bedrock aquifer in the central west region, NSW, Australia. IN: Groundwater in Fractured Rocks (IAH), Prague, Czech Republic, 15-19 September, 2003.

Morgan K, Jankowski J. 2004. Saline groundwater seepage zones and their impact on soil and water resources in the Spicers Creek catchment, central west, New South Wales, Australia. Environmental Geology 46:273-285.

Morgan K, Jankowski J. 2004. Seepage zone formation in relation to structural features in the Spicers Creek catchment, New South Wales. In: Inaugural Australasian Hydrogeology Research Conference. University College. Melbourne, Australia. December 2-3, 2004.

Morgan K, Jankowski J. 2004. Origin of salinity within salt affected groundwaters of the Spicers Creek catchment: An isotopic approach. In: 8th Australasian Environmental Isotope Conference. University College. Melbourne, Australia. 29 November – December 1, 2004.

Morgan K, Jankowski J, Taylor G. 2005. Structural controls on groundwater flow and groundwater salinity within a dryland affected catchment, Central West region, New South Wales. Hydrological Processes. In press.

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TABLE OF CONTENTS

No. Title Page No Abstract i Acknowledgements ii Publications iii Table of Contents iv List of Figures ix List of Tables xviii

Chapter 1 - Introduction 1 1.1 BACKGROUND 2 1.1.1 Introduction to the problem 3 1.2 PROJECT AIMS 4 1.3 PROJECT OBJECTIVES 4 1.4 SCOPE OF WORKS 4 1.5 HYPOTHESES 5 1.6 OUTLINE OF THESIS 6 Chapter 2 – Spicers Creek catchment 8 2.1 LOCATION 9 2.2 CLIMATE 9 2.3 TOPOGRAPHY 12 2.4 SURFACE WATER HYDROLOGY 13 2.5 SOILS 15 2.6 NATIVE VEGETATION AND FAUNA 17 2.7 LANDUSE HISTORY 19 2.8 PREVIOUS INVESTIGATIONS 19 2.9 SUMMARY 21 Chapter 3 – Literature review 22 3.1 SALINITY WITHIN THE ENVIRONMENT 23 3.1.1 Introduction 23 3.1.2 Dryland salinity in Australia 23 3.2 SOURCE OF SALT 27 3.2.1 Introduction 27 3.2.2 Allochthonous salt sources 28 3.2.2.1 Meteoric salts 28 3.2.2.2 Terrestrial aerosols 29 3.2.3 Autochthonous salt sources 30 3.3 GROUNDWATER SEEPAGES 30 3.3.1 Terminology 31 3.3.2 Formation of seepage zones 31 3.3.3 Mechanisms controlling salinity seeps 33 3.3.3.1 Break of slope 33 3.3.3.2 Permeability contrasts 34 3.3.3.3 Dykes and minor faults 35 3.3.3.4 Major Faults 35 3.4 STRUCTURALLY CONTROLLED SEEPAGE ZONES 36 3.4.1 Structural influences on groundwater flow 36

3.4.2 Structurally controlled dryland salinity 38 3.5 GEOCHMEMICAL PROCESSES IN SEEPAGES ZONES 40 3.5.1 Introduction 40 3.5.1.1 Waterlogging and redox effects 41 3.5.1.2 Weathering reactions 42 3.5.1.3 Salt accumulation processes 43 3.5.1.4 Soil sodicity and salinity within seepage zones 44 3.5.1.5 Surficial precipitates 46 3.6 SUMMARY 48

Chapter 4 – Geological complexity of the Spicers Creek catchment 50 4.1 INTRODUCTION 51 4.2 REGIONAL GEOLOGY 51 4.2.1 Lachlan Fold Belt in the Dubbo Region 53 4.2.2 Sydney –Gunnedah Basin 57 4.2.3 Surat Basin 58 4.2.4 Cainozoic Sediments 58 4.3 LOCAL GEOLOGY 58 4.3.1 Palaeozoic basement rocks 60 4.3.1.1 Oakdale Formation (Oco) 60 4.3.1.2 Gleneski Formation (Sms) 62 4.3.1.3 Cuga Burga Vocanics (Dgc) 62 4.3.1.4 Cunningham Formation (Dn) 63 4.3.2 Mesozoic cover rocks 63 4.3.2.1 Early Permian undifferentiated (Pe) 64 4.3.2.2 Dunedoo Formation (Pd) 64 4.3.2.3 Boulderwood Formation (Rb) 65 4.3.2.4 Napperby Formation (Rp) 65 4.3.2.5 Purlawaugh Formation (Ju) 66 4.3.2.6 Pilliga Sandstone (Jp) 66 4.3.2.7 Alluvial (Qa) and Colluvial (Qc) unconsolidated sediments 66 4.4 STRUCTURAL COMPLEXITY 67 4.4.1 Structural Interpretation 68 4.4.1.1 Identification of previously unmapped structures 69 4.4.1.2 Identification of lithological boundaries 71 4.5 GEOLOGICAL MODEL OF SPICERS CREEK CATCHMENT 72 4.5.1 North to South 73 4.5.2 West to East 74

Chapter 5 – Hydrogeological assessment of the Spicers Creek catchment 82 5.1 INTRODUCTION 83 5.2 FRACTURED AQUIFERS OF THE DEEP SYSTEM 85 5.2.1 The Oakdale Formation Aquifer 86 5.2.2 The Gleneski Formation Aquifer 89 5.2.3 The Cunningham Formation Aquifer 92 5.3 GROUNDWATER FLOW WITHIN THE DEEP AQUIFERS 92 5.3.1 Regional groundwater flow 92

5.3.2 Structural controls on groundwater flow 95 5.4 INTERMEDIATE GROUNDWATER SYSTEM 99 5.4.1 The Deep cell 99 5.4.2 The Intermediate cell 100 5.4.3 The Shallow cell (Pilliga Sandstone) 100 5.4.4 Aquifer properties in the intermediate system 101 5.4.5 Groundwater flow direction in the intermediate system 102 5.5 SHALLOW GROUNDWATER SYSTEM 104 5.5.1 Shallow aquifer properties 104 5.5.2 Groundwater flow in the shallow aquifer 105 5.5.3 Water level dynamics in the shallow aquifer 108 5.5.4 Water level response in the seepage zones 109 5.5.5 Water budget 113 5.6 CONCEPTUAL HYDROGEOLOGICAL MODEL 114 Chapter 6 – Soil and water categorisation 117 6.1 INTRODUCTION 118 6.2 SOIL CATEGORISATION 118 6.2.1 Physical properties of soils 119 6.2.1.1 Site 1 119 6.2.1.2 Site 2 121 6.2.1.3 Site 3 123 6.2.2 Chemical attributes of soils 123 6.2.2.1 Site 1 125 6.2.2.2 Site 2 127 6.2.2.3 Site 3 128 6.2.3 Clay mineralogy of soils 129 6.2.3.1 Site 1 129 6.2.3.2 Site 2 130 6.2.4.3 Site 3 130 6.2.4 Electrical resistivity results 130 6.2.4.1 Site 1 131 6.2.4.2 Site 2 133 6.2.4.3 Site 3 133 6.2.5 Summary of soil characteristics in the seepage zones 134 6.3 HYDROCHEMICAL CATEGORISATION GROUNDWATERS 135 6.3.1 Hydrochemical categorisation of deep groundwaters 137 6.3.1.1 Oakdale Formation groundwaters 138 6.3.1.2 Gleneski Formation groundwaters 139 6.3.1.3 Intermediate groundwaters 141 6.3.1.4 Na-HCO3-rich groundwaters (intermediate system) 142 6.3.2 Hydrochemical categorisation of shallow groundwaters 143 6.3.2.1 Shallow groundwaters 144 6.3.2.2 Site 1 shallow groundwaters 147 6.3.2.3 Site 2 shallow groundwaters 148 6.3.2.4 Site 3 shallow groundwaters 150 6.3.4 Vertical distribution of ions with depth 151 6.3.5 Spatial distribution of ions 154 6.3.6 General chemical characteristics of groundwaters 168 6.4 MECHANISMS CONTROLLING SALINITY DISTRIBUTION 170 6.4.1 Seepage zone formation in relation to structural features 170 6.4.2 The location of salt in the groundwater system 173

6.5 HYDROCHEMISTRY OF SURFACE WATERS 175 6.6 HYDROCHEMISTRY OF RAIN WATER 178

Chapter 7 – Hydrogeochemical processes influencing deep end-member groundwaters 180 7.1 INTRODUCTION 181 7.2 DEFINING END-MEMBER GROUNDWATERS 181 7.3 Na(Mg)-Cl-RICH END-MEMBER GROUNDWATERS 182 7.3.1 Origin of Na(Mg)-Cl-rich groundwaters 182 7.3.2 Evaporation trend in Na(Mg)-Cl-rich groundwaters 184 7.3.3 Geochemical evolution of Na(Mg)-Cl-rich groundwaters 185 7.3.3.1 Geochemical evolution of Na(Mg)-Cl-rich groundwaters 185 7.3.3.2 Chemical reactions influencing Na(Mg)-Cl-rich groundwaters 189 7.3.4 Carbonate system with respect to Na(Mg)-Cl-rich 7.3.5 Groundwaters 191 7.3.4.1 Carbon-13 in Na(Mg)-Cl-rich groundwaters 193 7.3.4 Weathering reactions in Na(Mg)-Cl-rich groundwaters 194 7.3.4.1 Aluminosilicate weathering 194 7.3.4.2 Halogen-bearing biotite weathering 196 7.3.4.3 Clay mineral stability 197 7.3.5 Reverse Ion exchange in Na(Mg)-Cl-rich groundwaters 198 7.3.6 Trace elements in Na(Mg)-Cl-rich groundwaters 199 7.3.7 The origin of strontium to the Na(Mg)-Cl-rich groundwaters 202 7.3.7.1 Sources and sinks of strontium 204 7.3.7.2 87Sr/86Sr isotopic evidence 205 7.3.8 Mass balance modelling for Na(Mg)-Cl-rich groundwaters 209 7.3.8.1 Model constraints 210 7.3.8.2 Phases 210 7.3.8.3 Evaluation of Na(Mg)-Cl-rich groundwater model 211 7.4 Na-HCO3-RICH END-MEMBER GROUNDWATERS 213

Chapter 8 – Geochemical processes influencing seepage zone development 216 8.1 INTRODUCTION 217 8.2 CHLORIDE BEHAVIOR IN THE SHALLOW AQUIFER 217 8.2.1 Volume of Cl- in the shallow aquifer 217 8.2.2 Solute composition of the soils 218 8.2.3 Elucidating the source of salinity 219 8.2.3.1 Oxygen-18 and deuterium 219 8.2.3.2 Carbon-13 221 8.2.4 Allochthonous versus autochthonous source(s) of Cl- 222 8.2.5 Recharge rate estimation 224 8.2.6 Chloride accession from rainfall 225 8.2.7 Chloride transport in the shallow aquifer 226 8.3 AGE OF SHALLOW GROUNDWATERS 227

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8.3.1 Groundwater residence time 227 8.3.2 Age of groundwaters in the seepage zones 227 8.3.2.1 Carbon-14 dating 227 8.3.3 Summary of Cl- data 228 8.4 STRUCTURALLY CONTROLLED SEEPAGE ZONE 229 8.4.1 Seepage zone at Site 1 229 8.4.2 Chloride balance of Site 1 230 8.4.3 A comparison of Na(Mg)-Cl-rich and seepage zone groundwaters 230 8.4.3.1 Vertical distribution of δ18O 230 8.4.3.2 Vertical distribution of Cl- 233 8.4.4 Hydrochemical evolution of seepage zone groundwater 233 8.4.4.1 Relationship between major ions in groundwater 233 8.4.4.2 Soil chemistry trends in the seepage zone 236 8.4.4.3 Sodicity in the seepage zone 238 8.4.4.4 Trace elements 239 8.4.4.5 Behaviour of carbonates in the seepage zone 242 8.4.4.6 Clay mineral transformation in the seepage zone 244 8.4.4.7 Ion exchange processes 246 8.4.5 Modelling mixing in the seepage zone at Site 1 248 8.4.5.1 Constraints 249 8.4.5.2 Phases 249 8.4.5.3 Model interpretation 250 8.5.6 Hydrogeological and hydrogeochemical model of Site 1 251 Chapter 9 – Conclusions 254 9.1 REVIEW OF THE PROBLEM 255 9.2 SUMMARY OF MAJOR FINDINGS 256 9.2.1 Geology 256 9.2.2 Hydrogeology 256 9.2.3 Hydrogeochemistry and isotopes 257 9.3 RECOMMENDATIONS 260 9.4 FINAL COMMENTS 261 References 262 Appendix A Appendix B

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LIST OF FIGURES

No. Title Page No

2.1 Location of the Spicers Creek Catchment and sub-catchments; Snake Gully catchment and Racecourse Gully catchment (modified from DMR, 2000). 10

2.2 (a) Average monthly minimum and maximum temperatures for Wellington Research Station from 1997 to 2004. (b) Average rainfall and average pan evaporation data for Wellington Research Station from 1997 to 2004 (data obtained from Wellington Research Station). 11

2.3 Average monthly rainfall (a) Binginbar Farm from 1934 to 2003 (data obtained from M. Simpson) (b) Wellington Research Station from 1946 to 2003 (data obtained from Wellington Research Station). 12

2.4 Stream EC data for Spicers Creek, Talbragar and Macquarie River for period July 1999 to July 2004 (www.waterinfo.dlwc.nsw.gov.au). 14

2.5 Soil landscapes of the Spicers Creek catchment (modified from Murphy and Lawrie, 1998). 16

2.6 Native vegetation distribution in the Spicers Creek catchment overlayed onto a Landsat image of the Spicers Creek catchment (modified from DMR, 2000). 18

3.1 Classification of salt affected land in Australia (Williams and Bullock, 1989) 32

3.2 Mechanisms associated with seepage zone development with respect to (a) break of slope (b) permeability contrast in shallow aquifer (NSCP, 2000). 34

3.3 Mechanisms associated with seepage zone development with respect to (a) bedrock high (b) change in hydraulic conductivity (NSCP, 2000). 35

3.4 Mechanisms associated with seepage zone development with respect to (a) dyke (b) fault (NSCP, 2000). 36

3.5 Examples of surficial precipitates in that have formed on the land surface in seepage zones, Spicers Creek catchment. 47

3.6 Examples of surficial precipitates in that have formed on the land surface in seepage zones, Spicers Creek catchment. 48

4.1 Simplified geological framework of the Dubbo 1:250 000 map sheet area (modified from Meakin and Morgan, 1999). 52

4.2 Geological environment of the Ordovician period for the Dubbo region (modified from Schofield, 1998). 54

4.3 Schematic block diagram of the palaeogeography of the central and western parts of the Dubbo 1: 250,000 during the Late Silurian (modified Morgan, 1999). 56

4.4 Schematic block diagram of the palaeogeography of the central and western parts of the Dubbo 1: 250,000 during the Early Devonian (modified Morgan, 1999). 57

4.5 The geology and location of cross-sections within the Spicers Creek catchment (modified from DMR, 2000). 59

4.6 A subsection of the structural map of the Dubbo 1:250,000 showing structural zones (modified from Glen (1999) in Meakin and Morgan (1999)). 68

4.7 First derivative Total Magnetic Intensity (TMI) image that illustrates the different basement lithologies in the Spicers Creek catchment. 69

4.8 Total Magnetic Intensity (TMI) image with an east to west sun angle illumination applied to further emphasise structural features in the Spicers Creek catchment. 70

4.9 Red Blue Green (RGB) radiometric colour composite with a high, pass filter applied to delineate of sedimentary cover units in the Spicers Creek catchment. 72

4.10 Drill core assay results for COM2 south of Spicers Creek catchment (MIM, 2002). 73

4.11 Drill core assay results for YAR1 within the Spicers Creek catchment (MIM, 2002). 75

4.12 Geological cross-section A to A’ through the Spicers Creek catchment (see Figure 4.17 for location). 76

4.13 Geological cross-section B’ to B through the Spicers Creek catchment (see Figure 4.17 for location). 77

4.14 Geological cross-section C to C’ through the Spicers Creek catchment (see Figure 4.17 for location). 78

4.15 Geological cross-section D to D’ through the Spicers Creek catchment (see Figure 4.17 for location). 79

4.16 Geological cross-section E to E’ through the Spicers Creek catchment (see Figure 4.17 for location). 80

4.17 Location of cross-section in the Spicers Creek catchment (refer to Figure 4.5 for map legend). 81

5.1 Schematic models of the groundwater circulation systems of the Ballimore region (modified from Schofield, 1998). 84

5.2 Location of groundwater piezometers within the Spicers Creek catchment. 85

5.3 Rock chip samples of the Oakdale Formation aquifer from (a) 190 to 192 m bgs, (b) 192 to 194 m and (c) 194 to 196 m bgs (MIM, 2002). 86

5.4 Core sample of the Oakdale Formation obtained from 235 to 236 m bgs (MIM, 2002). 87

5.5 Core sample of the Oakdale Formation obtained from 239 to 241 m bgs (MIM, 2002). 87

5.6 Down-hole geophysical logs of gamma ray (cps) and EM39 (m/Sm) for the Oakdale Formation in piezometer 96133 (adapted Acworth, 2002, pers com). 89

5.7 Down-hole geophysical logs of gamma ray (cps) and EM39 (m/Sm) for the Gleneski Formation in piezometer 96121 (adapted from Acworth, 2002, pers com). 91

5.8 Yield versus depth in the Gleneski Formation. 91

5.9 Groundwater flow direction in the deep aquifers in the Spicers Creek catchment. 93

5.10 Hydrographs for the shallow (96128/2) and Gleneski Formation (96128/3) from January 2002 to May 2002 in the Spicers Creek catchment (Smithson, 2002). 94

5.11 Hydrographs of the Oakdale Formation aquifer (a) nested piezometers 96121/1-2-3 and (b) nested piezometers 96133/1-2 and nested piezometers 96127/1-2, in the Spicers Creek catchment. 96

5.12 Hydrographs of the Gleneski Formation (a) nested piezometers 96128/1-2-3 and (b) nested piezometers 96122/1-2-3-4, in the Spicers Creek catchment. 97

5.13 Hydrographs of the Cunningham Formation aquifer in nested piezometers 96129/1-2-3 in the Spicers Creek catchment. 99

5.14 The relationship between yield versus depth for the intermediate aquifers contained within the Spicers Creek catchment (DLWC, 2003). 101

5.15 Groundwater flow direction for the intermediate aquifers of the Spicers Creek catchment. 103

5.16 Hydrographs of the intermediate groundwater system in nested piezometers 96130/1-2 and 96132/1-2 in the Spicers Creek catchment. 103

5.17 Groundwater flow direction for the shallow aquifers in the Spicers Creek catchment. 106

5.18 Groundwater flow movement at Site 1 in the Spicers

Creek catchment. 107

5.19 Groundwater flow movement at Site 2 in the Spicers Creek catchment. 108

5.20 (a) Rainfall data for Binginbar Farm from June 2001 to February 2003 (b) hydrographs of nested piezometers S4 and S3 located at the top of the transect (c) nested piezometers S2 located at the top of the seepage zone and (d) nested piezometers S1 located within the seepage zone in the shallow groundwater system, Spicers Creek catchment. 110

5.21 Hydrographs of the shallow aquifer at Site 2 (a) piezometers S8 and S7 located at the top of the transect (b) piezometers S5 and S6 located within seepage zones and p56 located at the bottom of the seepage zone, Spicers Creek catchment. 111

5.22 Hydrographs of the shallow aquifer at Site 3 (a) piezometers S12 and S13 located at the top of the transect (b) piezometers S14 located at the bottom of the seepage zone and (c) piezometers S15, p62 and p65 located near the creek within the seepage zone, Spicers Creek catchment. 113

5.23 Conceptual hydrogeological model for the Spicers Creek catchment groundwater system (see Figure 4.4 for location of cross section). 116

6.1 Location of soil sampling points and geophysical investigations in Spicers Creek catchment. 119

6.2 Cross section of soil profiles within Site 1 with soil textures, colours, clay mineral percentage, soil water EC1:5 and soil moisture percentage depicted. 120

6.3 Cross section of soil profiles within Site 2 with soil textures, colours, clay mineral composition, soil water EC1:5 and soil moisture percentage depicted. 122

- + 2+ 2+ 6.4 Vertical distribution of Cl 1:5, Na 1:5, Mg 1:5, Ca 1:5 and pH1:5 for soils water extracts from site 1. Soil profile (a) S3 not affected by salinity (b) S4 not affected by salinity (c) S2 slightly saline (d) S1 salt affected soils in the Spicers Creek catchment (soil texture legend refer to Figure 6.2). 126

+ - 6.5 Vertical distribution of (a) moisture and EC1:5 (b) Na 1:5, Cl 1:5, 2+ Sr 1:5 and B1:5 for soils from site 3, in the Spicers Creek catchment. 129

6.6 Electrical resistivity image profile of line 1, at Site 1 with generalised groundwater flow direction and bedrock contact. 132

6.7 Electrical resistivity image profile of line 2, at Site 1 with generalised groundwater flow direction and bedrock contact. 132

6.8 Electrical resistivity image profile of line 3, at Site 1 with generalised groundwater flow direction and bedrock contact. 133

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6.9 Electrical resistivity image profile of line 1, at Site 2 with generalised groundwater flow direction and bedrock contact. 134

6.10 Electrical conductivity image profile of line 1, at Site 3 with generalised groundwater flow direction and bedrock contact. 134

6.11 Piper diagram of groundwaters from the Spicers Creek catchment. 137

6.12 Vertical distribution of (a) EC (b) Cl- (c) Na+ and (d) Mg2+ for deep, intermediate and shallow groundwaters from the Spicers Creek catchment. 152

2- - 2+ 6.13 Vertical distribution of (a) SO4 (b) HCO3 (c) Ca and (d) K+ for deep, intermediate and shallow groundwaters from the Spicers Creek catchment. General trend experienced in (1) shallow groundwaters (2) Intermediate groundwaters (3) Oakdale Formation (4) Gleneski Formation groundwaters and (5) Na-HCO3-rich groundwaters. 153

6.14 Vertical distribution of (a) Li+ (b) B (c) Sr2+ (d) As for deep, intermediate and shallow groundwaters from the Spicers Creek catchment. 154

6.15 The spatial distribution of groundwater EC in the Spicers Creek catchment. 159

6.16 The spatial distribution of Cl- in groundwaters in the Spicers Creek catchment. 160

6.17 The spatial distribution of Sr2+ in groundwaters in the Spicers Creek catchment. 161

6.18 Spatial distribution of 87Sr/86Sr isotopes for groundwaters in the Spicers Creek catchment. 162

6.19 The spatial distribution of Na+ in groundwaters in the Spicers Creek catchment. 163

- 6.20 The spatial distribution of HCO3 in groundwaters in the Spicers Creek catchment. 164

6.21 The spatial distribution of K+ in groundwaters in the Spicers Creek catchment. 165

6.22 The spatial distribution of Li+ in groundwaters in the Spicers Creek catchment. 166

6.23 Spatial distribution of δ13C isotopes for groundwaters in the Spicers Creek catchment. 167

6.24 Piper diagram of groundwaters groups contained within the Spicers Creek catchment. 168

6.25 Total Magnetic Intensity (TMI) image with the location of the

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newly mapped structures in the Spicers Creek catchment. This image has an east to west sun angle illumination applied (data supplied by MIM, 2002). 171

6.26 North to South vertical profile of groundwater salinity for the Spicers Creek catchment. 174

6.27 Stream data for Spicers Creek and Talbragar River for study period Nov 2001 to Feb 2003 (a) river discharge (ML day-1) versus time (b) river EC (μS cm-1) versus time (b) average river level (m) versus time (c) (www.waterinfo.dlwc.nsw.gov.au). 177

7.1 Na+Cl% vs. EC for deep and intermediate groundwaters in Spicers Creek catchment. 182

7.2 Na+HCO3% vs. EC for deep and intermediate groundwaters in Spicers Creek catchment. 182

7.3 δ2H vs. δ18O for deep and intermediate groundwaters in Spicers Creek catchment. 184

7.4 δ18O vs. Cl for deep and intermediate groundwaters in Spicers Creek catchment. 184

7.5 Na+ vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 186

7.6 Na/Cl vs. EC for deep and intermediate groundwaters in Spicers Creek catchment. 186

7.7 Mg2+ vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 187

7.8 Ca2+ vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 187

7.9 Ca/Cl vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 188

7.10 Ca/Mg vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 188

- - 7.11 HCO3 vs. Cl for deep and intermediate groundwaters in Spicers Creek catchment. 189

2- - 7.12 SO4 vs. Cl for deep and intermediate groundwaters in Spicers Creek catchment. 189

7.13 K+ vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 189

- 7.14 SiO2 vs. Cl for deep and intermediate groundwaters in Spicers Creek catchment. 189

7.15 Calcite vs. dolomite for deep and intermediate groundwaters in

xiv

Spicers Creek catchment. 192

13 7.16 δ CDIC vs. DIC for deep and intermediate groundwaters in Spicers Creek catchment. 194

13 - 7.17 δ CDIC vs. Cl for deep and intermediate groundwaters in Spicers Creek catchment. 194

7.18 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Mg2+ deep and intermediate groundwaters in Spicers Creek catchment. 197

7.19 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Ca2+ deep and intermediate groundwaters in Spicers Creek catchment. 197

7.20 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Na+ deep and intermediate groundwaters in Spicers Creek catchment. 198

7.21 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for K+ deep and intermediate groundwaters in Spicers Creek catchment 198

2+ 2+ 2- - 7.22 Ca + Mg - SO4 - HCO3 for deep and intermediate groundwaters in Spicers Creek catchment. 199

7.23 B- vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 201

7.24 Li+- vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 201

7.25 V vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 202

7.26 As vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 202

7.27 Sr2+ vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 205

7.28 Sr/Cl vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 205

7.29 Sr/Ca vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 206

7.30 87Sr/86Sr vs. Cl- for deep and intermediate groundwaters in Spicers Creek catchment. 206

7.31 87Sr/86Sr vs. Sr2+ for deep and intermediate groundwaters in Spicers Creek catchment. 207

87 86 13 7.32 Sr/ Sr vs. δ CDIC for deep and intermediate groundwaters in Spicers Creek catchment. 207

87 86 18 7.33 Sr/ Sr vs. δ O for deep and intermediate groundwaters in Spicers Creek catchment. 208

7.34 87Sr/86Sr vs. 1/Sr for deep and intermediate groundwaters in Spicers Creek catchment. 208

8.1 Na/Cl molar ratio vs. EC1:5 for 1:5 soil water extracts for soils in Spicers Creek catchment. 219

8.2 Ca/Mg molar ratio vs. Cl1:5 for 1:5 soil water extracts for soils in Spicers Creek catchment. 219

8.3 δ2H vs. δ18O for shallow groundwaters in Spicers Creek catchment. 221

8.4 δ18O vs. Cl for shallow groundwaters in Spicers Creek catchment. 221

13 8.5 δ CDIC vs. DIC for shallow groundwaters in Spicers Creek catchment. 222

8.6 Cl/Br mass ratio vs. Cl for shallow groundwaters in Spicers Creek catchment. 223

8.7 Hydrochemical profile of Site 1. 231

8.8 Depth vs. δ18O for groundwaters from Site 1. 232

8.9 Depth vs. Cl- for groundwaters from Site 1. 232

8.10 Na+ vs. Cl- for groundwaters from Site 1. 234

8.11 Na/Cl vs. EC for groundwaters from Site 1. 234

8.12 Mg2+ vs. Cl- for groundwaters from Site 1. 235

8.13 Ca2+ vs. Cl- for groundwaters from Site 1. 235

8.14 K+ vs. Cl- for groundwaters from Site 1. 236

- - 8.15 HCO3 vs. Cl for groundwaters from Site 1. 236

2- - 8.16 SO4 vs. Cl for groundwaters from Site 1. 236

- - 8.17 SiO2 vs. Cl for groundwaters from Site 1. 236

8.18 Piper diagram for 1:5 soil water extracts for soils from Site 1. 237

8.19 Na/Cl vs. EC1:5 for soils from Site 1. 237

8.20 pH vs. Cl1:5 for soils from Site 1. 238

8.21 ESR1:5 vs. SAR1:5 for soils from Site 1. 238

8.22 B vs. Cl- for groundwaters from Site 1. 240

8.23 Li+- vs. Cl- for groundwaters from Site 1. 240

xvi

8.24 Sr2+ vs. Cl- for groundwaters from Site 1. 240

8.25 As- vs. Cl- for groundwaters from Site 1. 240

8.26 Se vs. Cl- for groundwaters from Site 1. 241

8.27 V vs. Cl- for groundwaters from Site 1. 241

8.28 Time series graph for calcite in groundwaters from Site 1. 243

8.29 Time series graph for strontianite in groundwaters from Site 1. 243

8.30 SIcalcite vs. SIstrontianite for groundwaters from Site 1. 244

8.31 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Mg2+ groundwaters from Site 1. 245

8.32 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Ca2+ groundwaters from Site 1. 245

8.33 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for Na+ groundwaters from Site 1. 245

8.34 Stability diagrams at 25°C and 1 bar pressure based on Drever (1988) for the silicates for K+ groundwaters from Site 1. 245

8.35 Cross-section depicting clay mineral assemblages through Site 1 in the Spicers Creek catchment. 247

8.36 Ca + Mg – SO4 – HCO3 vs. Na-Cl for groundwaters from Site 1. 248

8.37 Model of seepage zone formation at Site 1. 253

xvii

LIST OF TABLES

No. Title Page No

1.1 Rationale for the use of various geoscientific techniques within the Spicers Creek catchment. 5

3.1 Chemical characteristics of saline, non-saline sodic and saline sodic soils (Balba, 1995). 45

4.1 Simplified time-space plot of the Spicers Creek catchment geology (modified from Morgan and Meakin, 1999). 61

5.1 Aquifers and aquitards within the Spicers Creek catchment (modified from Schofield, 1998). 84

5.2 Descriptive statistics of the water levels within the shallow aquifers of the Spicers Creek catchment. 109

6.1 Descriptive statistics for 1:5 soil water extracts for soils in the Spicers Creek catchment. 124

6.2 Spearman’s nonparametric correlation coefficients for 1:5 soil water extracts for soils from Site 1 in the Spicers Creek catchment (n=45). 125

6.3 Spearman’s nonparametric correlation coefficients for 1:5 soil water extracts for soils from Site 2 in the Spicers Creek catchment (n=43). 128

6.4 Descriptive statistics of general parameters and major ions for the deep and intermediate groundwater systems of the Spicers Creek catchment. 138

6.5 Descriptive statistics of minor ions and trace elements for the deep and intermediate groundwater systems of the Spicers Creek catchment. 140

6.6 Descriptive statistics of general parameters and major ions for the shallow groundwaters in the Spicers Creek catchment. 143

6.7 Descriptive statistics of minor ions and trace elements for the shallow groundwaters in the Spicers Creek catchment. 146

6.8 Spearman’s nonparametric correlation coefficients for shallow groundwaters in Spicers Creek catchment (n=139). 147

6.9 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 1 in the Spicers Creek catchment (n=39). 148

6.10 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 2 in the Spicers Creek catchment (n=21). 149

6.11 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 3 in the Spicers Creek catchment (n=28). 150

xviii

6.12 General parameters, major ions, minor ions and trace elements for surface waters in Spicers Creek catchment. 176

6.13 Rainwater chemistry for Spicers Creek catchment. 179

7.1 Ion ratios for deep and intermediate groundwaters in Spicers Creek catchment. 188

7.2 Expected concentration of Sr2+ in groundwater from rainfall. 204

8.1 Chloride loads in the shallow aquifer in the Spicers Creek catchment. 218

8.2 Average linear velocities of Cl- and approximate travel times for shallow groundwaters at each site, in the Spicers Creek catchment. 226

xix Chapter 1: Introduction

CHAPTER 1: INTRODUCTION

1 Chapter 1: Introduction

1.1 BACKGROUND Spicers Creek catchment is located approximately 400 km west of Sydney, near Dubbo, in the Central West region of New South Wales (NSW), Australia. Within this catchment, dryland salinity has affected rural activities such as dryland agriculture and stock grazing. Dryland salinity has been recognised as a major environmental issue impacting soil and water resources in the Central West region of NSW for over 70 years (Humphries, 2000). Over 50, 000 hectares of land in the Central West Region of NSW was estimated to have the potential to develop dryland salinity problems (Humphries, 2000).

Large areas of the Spicers Creek catchment have been or are likely to be affected by dryland salinisation processes. Dryland salinity has been evident in the catchment since the 1950’s (A. Nicholson pers com, 2001). According to McElroy (2000), over fifty-two dryland salinity occurrences were identified in the catchment. He suggested that these dryland salinity outbreaks are controlled by the presence of geological structures, permeability contrasts in the aquifer lithologies and narrow constrictions within the topography. Due to the geological complexity of the catchment and the presence of high salt loads contained within the soils, groundwater and surface waters, the Spicers Creek catchment was identified as a large contributor of salinity to the Macquarie River and was classified as a very high salinity risk (Humphreys, 2000).

The Department of Land and Water Conservation (DLWC) (now known as the Department of Infrastructure, Planning and Natural Resources (DIPNR)) Wellington office, requested a hydrogeological evaluation of the area, including the townships of Ballimore, Saxa and Gollan and within the vicinity of the Spicers Creek, Snake Gully and Racecourse Gully. DIPNR began treating salt affected lands in the catchment in 2000 by implementing revegetation programs using funds made available under the Natural Heritage Trust (NHT) TARGET. The basic requirement of the hydrogeological component of this TARGET project was to quantify the local and regional groundwater system in the study area, so that effective management strategies could be implemented to help control dryland salinity. Pre-existing infrastructure installed by DIPNR included a shallow

2 Chapter 1: Introduction piezometer network and continuous stream data loggers on the Spicers Creek and Talbragar River.

Approximately twenty deep bores were drilled by DIPNR Dubbo drilling unit in 2001 which were installed to identify the groundwater flow and chemistry of various deep fractured aquifers in the catchment. Approximately forty shallow nested piezometers were drilled by the DIPNR Wellington office in 2001 under the supervision of the author. This shallow piezometer network was installed to identify the source of salt and identify transport mechanisms influencing salt movement in the shallow aquifer. The data obtained from these piezometers are also used to identify the extent of interaction between the deep and shallow groundwaters in groundwater seepage zones at the experimental sites.

1.1.1 Introduction to the problem Saline seepage zone development and hence the onset of dryland salinity is a major environmental problem affecting many semi-arid to arid landscapes in Australia and worldwide (Abrol, 1986; Ghassemi et al., 1995). Dryland salinity and saline seepage zone formation threatens approximately 5.7 million hectares of Australia’s agricultural and pastoral zones (ADSA, 2000). Predictions based on groundwater trends, field observations and landscape characteristics indicate this area could increase to over 17 million hectares by 2050 (ADSA, 2000). Dryland salinity may occur when there is an increase in groundwater recharge to a naturally saline environment. This increase in recharge occurs due to the replacement of deep-rooted native vegetation with shallow-rooted annual crops and pastures, resulting in a reduction in evapotranspiration rates which, in turn, results in increased in soil water moisture (Pavelic et al., 1997; Williams, et al., 2001). To initiate dryland salinity within a landscape there needs to be a source of salt within the landscape, a mechanism that concentrates the salt and a medium that transports the salts to an accumulation zone, which will be referred to herein as a seepage zone.

3 Chapter 1: Introduction

1.2 PROJECT AIMS The main aim of this thesis is to identify the source(s) of salts to the groundwater system and identify geochemical processes influencing seepage zone development. To achieve these aims a multidisciplinary approach was untaken to understand the soils, geology, hydrogeology and hydrogeochemistry of the catchment. Conceptualising and quantifying the hydrogeology and hydrogeochemistry of the deep and shallow groundwater systems and the source of salt to the groundwater system, will lead to a better understanding of dryland salinity processes can be gained.

1.3 PROJECT OBJECTIVES The following specific objectives to be fulfilled in this thesis include: ¾ Identify geological structures in the catchment; ¾ Identify the association between geological structures and seepage zone formation; ¾ Identify groundwater chemistry and isotopic characteristics of the deep fractured and shallow groundwater system; ¾ Quantify salt inputs to the catchment; and ¾ Identify geochemical processes occurring in the seepage zones.

1.4 SCOPE OF WORKS To identify the origin of salt to the Spicers Creek catchment, a hydrogeological and hydrogeochemical evaluation of the deep, intermediate and shallow groundwater systems was undertaken. Investigative techniques employed in this project include the use of high-resolution airborne magnetics and radiometrics, used in conjunction with ground-based electrical imaging and magnetic techniques. Soil science, soil spectroscopy, hydrogeochemistry and isotopic techniques were also used to further understand this problem.

A multidisciplinary approach was undertaken to achieve these aims and objectives and Table 1.1 shows the rationale for using various techniques in this project.

4 Chapter 1: Introduction

Table 1.1 Rationale for the use of various geoscientific techniques within the Spicers Creek catchment.

Component Technique Outcome Construction of cross-sections to Geology DLWC logs1, previous studies, MIM develop geological model of the study logs2 and drilling data4 area. Establish groundwater flow direction, Hydrogeology MIM data3, hydrograph data5, mixing between aquifers, the presences geophysical logs6 of fractures

MIM airborne Geophysics magnetics/radiometrics3, ground- Identify salt loads present in shallow based magnetics5, EM345, electrical aquifers and identify structural features resistivity4 within the fractured bedrock aquifers Salinisation processes, to identify soil Soils Field inspection4, 1:5 soil water4, soil degradation, erosion and types of salts spectroscopy6 present Categorise groundwaters from different aquifers, salinisation processes, Hydrogeochemistry delineate different aquifers in catchment, evaluation of Major ion, minors ions and trace hydrogeochemical processes during element chemistry4 water-rock interaction

Isotopes Identify origin of groundwaters, origin of 18O, 2H, 13C, 87Sr, 14C4 salts, indicate mixing, groundwater ages Identify salt transport, quantify salt Modelling loading in seepage zones, delineate hydrogeochemical processes within PHREEQC, NETPATH7 seepage zones 1DLWC (DPNIR) groundwater database. 2MIM 2002 drilling program 3MIM 2002 geophysical program 4Data collected by author and is presented in Appendix B 5Data collected by author and can be obtain from author through correspondence 6Data collected by author, Casey Edwards and Geoffrey Taylor, UNSW 7Modelling completed by author, output may be obtained from author through correspondence

1.5 HYPOTHESES The origin of salt to the catchment has been hypothesised to originate from several different sources including; aeolian sources (Smithson, 2002), the rising of saline shallow groundwaters (A. Nicholson, pers comm. 2001) or from deeper aquifers (Morgan and Jankowski, 2002a). A major geological, hydrogeological and hydrogeochemical study of the Ballimore region was completed by Schofield (1998) and showed the presence of fractured bedrock aquifers that contain varying groundwater chemistry. Due to the geological complexity and the presence of

5 Chapter 1: Introduction seepage zones at the mid slope and elevated areas the following set of hypotheses were developed. The hypotheses for this project include:

¾ Geological structures are influencing seepage zone formation and are the mechanisms controlling their development; ¾ Salts are derived from various sources including rainfall accession and bedrock sources; and ¾ Seepage zones are forming due to the mixing of rainfall recharge and deeper groundwaters within seepage zones.

1.6 OUTLINE OF THESIS The outline of this thesis is as follows; ¾ The environmental setting of the Spicers Creek catchment will be described in Chapter 2. The location, its climate with respect to temperatures and rainfall characteristics, the topography and surface water hydrology will be discussed with regards to stream Electrical Conductivity (EC) and observed trends in the Spicers Creek, Macquarie River and Talbragar River. Soils are discussed according to the soil landscape groups contained within the catchment (Murphy and Lawrie, 1998). Vegetation and fauna, and land use history, together with previous investigations conducted in the catchment, will be discussed; ¾ Chapter 3 will form a general review of dryland salinity in Australia and the salt sources to the catchment. It discusses allochthonous or autochthonous salt sources in a dryland salinity affected catchment. The focus of this review moves to groundwater seepage zone and differentiates the mechanisms that influence their formation, with the main focus on structurally controlled seepage zone formation and geochemical processes influencing their development; ¾ Chapter 4 will highlight the geological complexity of Spicers Creek catchment and show the presence of four previously unidentified structures in the catchment using airborne magnetics; ¾ Chapter 5 presents a hydrogeologic assessment of the Spicers Creek catchment groundwaters systems. Provides further information on the

6 Chapter 1: Introduction

Oakdale Formation and Gleneski Formation aquifer units and shows the association between increased hydraulic head in the fault zones; ¾ Chapter 6 presents hydrogeochemical data for the Oakdale Formation and Gleneski Formation aquifers, together with soil and groundwater data from the shallow aquifer system. It also presents maps showing the spatial distribution of groundwater chemistry and isotopes in relation to aquifer type and structural features in the catchment; ¾ Chapter 7 describes the processes by which deep and intermediate groundwaters in the Spicers Creek catchment have evolved and identifies the presence of two deep end-member groundwaters in the catchment. The geochemical processes influencing these deep groundwaters are evaluated using hydrogeochemistry, isotopes and inverse modelling techniques; ¾ Chapter 8 presents salt loads, accession rates and average groundwater residence times in the shallow aquifer of the Spicers Creek catchment. It also dates the shallow seepage zone groundwaters and shows the relationship between deep Na(Mg)-Cl-rich and shallow groundwaters. Geochemical processes influencing seepage zone development are identified and the mixing of Cl- in the shallow aquifer from various sources is evaluated; and ¾ Finally, Chapter 9 presents concluding remarks on the major findings and objectives fulfilled in this project. It also highlights areas of further research that will facilitate the understanding of dryland salinity processes in the Central West Region of New South Wales, Australia.

CHAPTER 2: SPICERS CREEK CATCHMENT

Chapter 2: Spicer Creek catchment

2.1 LOCATION The Spicers Creek catchment is located approximately 400 km west of Sydney and is contained within the larger Macquarie River Catchment that is located in the Central West Region of New South Wales, Australia. The study area is located on four 1:50,000 topographic map sheets, which include the Dunedoo (8733-I and IV), Geurie (8633-II and III), Goolma (8733-II and III) and the Mogriguy (8633-I and IV). It spans the Australian Map Grid (U.T.M) zone 55 within the coordinates of 64 48 000 mN to 64 22 000 mN and 678 000 mE to 704 000 mE. The catchment 2 covers an area of approximately 500 km , with the Spicers Creek forming the main surface water system. Spicers Creek flows in a north-westerly direction and is a tributary of the Talbragar River. The Talbragar River flows in a westerly direction and joins the Macquarie River at Dubbo. Dubbo is located approximately 65 km north-west of Spicers Creek catchment and is the largest town in the vicinity, with a population of approximately 38,000 people (Humphreys, 2000). Small townships within the catchment include Ballimore, Gollan and Saxa as seen in Figure 2.1.

The catchment has been divided into two smaller sub-catchments for the purpose of this study they include; the Snake Gully catchment located to the east and the Racecourse Gully catchment to the south (Figure 2.1). Three experimental sites were established in the Snake Gully catchment to further understand the relationship between various biophysical parameters and how they influence saline seepage zone formation within a dryland salinity affected catchment.

2.2 CLIMATE Climatic data was collected from two stations; one located within the catchment on Binginbar Farm and the other located approximately 30 km south of the catchment at Wellington Research Station. Rainfall data was collected over a 69-year period from 1934 to 2003 at Binginbar Farm and collected over a 57-year period from 1946 to 2003 at Wellington Research Station. Detailed climatic data such as temperature, pan evaporation, humidity and dew point values were collected from 1997 to 2004 for the Wellington Research Station.

Chapter 2: Spicer Creek catchment

Figure 2.1 Location of the Spicers Creek Catchment and sub-catchments; Snake Gully catchment and Racecourse Gully catchment (modified from DMR, 2000). 10 Chapter 2: Spicer Creek catchment

Spicers Creek catchment experiences semi-arid climatic conditions where hot summers (December to February) and cold winters (June to August) prevail, with average rainfall generally less than 600 mm-1 year. Highest temperatures are experienced in summer with a mean maximum temperature of 32 °C in January and lowest temperature in July with a minimum mean of 3.5°C as seen in Figure 2.2(a).

Figure 2.2(b) is a graph of the monthly mean pan evaporation compared to monthly mean rainfall. Evaporation is closely related to the season with the highest average evaporation experienced in January (280 mm) and the lowest in the month of June (48 mm). Average annual evaporation was calculated at 1830 mm-1 year which, compared with precipitation data, indicates that average evaporation rates exceed average rainfall for all months of the year. Monthly evaporation to precipitation (E/P) ratios were calculated for the area and monthly averages range from 7.3 in January to 1.1 in June and July with an average E/P ratio of 3 throughout the year. Therefore, 3 times more potential evaporation is likely to occur in the catchment than precipitation.

Figure 2.2 (a) Average monthly minimum and maximum temperatures for Wellington Research Station from 1997 to 2004. (b) Average rainfall and average pan evaporation data for Wellington Research Station from 1997 to 2004 (data obtained from Wellington Research Station).

Mean average rainfall at Binginbar Farm over a 69 year period was recorded as 522.92 mm-1 year and at Wellington Research Station over a 59 year period was recorded as 620.6 mm-1 year. Highest rainfall events appear to occur in summer and spring months (Figure 2.3). At Binginbar, 27% of rainfall is experienced during 11

Chapter 2: Spicer Creek catchment the summer months and 23% during winter. During the study period (2001 to 2003), the average annual rainfall was 440 mm-1 year, which is approximately 80 mm-1 year below average. Drought conditions prevailed in the area during the study period. The overall average yearly rainfall varies between a minimum of 255 mm (1946) to a maximum of 1150 mm (1950) indicating a large variation in rainfall events. Storm events are common in the area, an example of this occurred in February 2002, where 196 mm of rainfall occurred for the month. The author notes that storm events appear to be a major contributor of recharge to the groundwater system in the catchment, where piston flow recharge mechanisms are likely to dominate. Diffuse rainfall does not have a major influence on groundwater recharge due to high evaporation rates in summer months when most of the rainfall occurs.

Figure 2.3 Average monthly rainfall (a) Binginbar Farm from 1934 to 2003 (data obtained from M.Simpson) (b) Wellington Research Station from 1946 to 2003 (data obtained from Wellington Research Station).

2.3 TOPOGRAPHY Elevation throughout the catchment ranges from 280 to 500 metres above sea level (m asl). The landscape consists of low undulating hills with slopes that range from 3-10% gradient depending on the underlying geology (Murphy and Lawrie, 1998). The north-western section of the catchment contains geological units of the Gunnedah and Surat Basins, which form undulating rises, and low hills that are associated with isolated sandstone outcrops and have gradients less than 6% (Murphy and Lawrie, 1998). Areas to the south-east of the catchment contain volcanic rocks of the Lachlan Fold Belt (LFB) where low undulating hills

Chapter 2: Spicer Creek catchment comprising gently inclined slopes with gradients less than 10% dominate the topography. Occasional Tertiary basalt intrusions occur throughout the catchment, such as the Bald Hill basaltic intrusion, which produces topographic highs that can reach up to 540 m asl and contain slopes with gradients of 35% (Murphy and Lawrie, 1998).

2.4 SURFACE WATER HYDROLOGY The Spicers Creek is a minor tributary of the Talbragar River, which in turn joins with the larger Macquarie River. The Macquarie River originates near Oberon, in south-eastern NSW, and flows 940 km (Salas and Smithson, 2002) to join the Barwon River near Brewarrana in the far north-west, forming part of the Murray Darling Basin system (White, 2000). The Macquarie River flows in a north-westerly direction and is highly regulated with the Burrendong dam located 32 km upstream of Wellington. The regulated nature of the Macquarie River is now threatening fragile ecosystems such as the Macquarie Marshes and floodplain ecosystems. The lack of surface water flow, presence of turbid waters together with escalating salinity problems, are factors that threaten the health of the Macquarie River (White, 2000).

The Talbragar River lies to the north of the Spicers Creek catchment and flows in a westerly direction towards Dubbo where it joins the Macquarie River. The Talbragar River has an average daily discharge rate that generally ranges from zero to ~100 ML day-1 at Muronbung and has maximum peak flows of over ~35,000 ML day-1 (in November 2000) to ~1,000 ML day-1 (in December 1999 and June 2000). The Talbragar River has low water quality and tertiary drainage systems such as the Spicers Creek contribute large salt loads to the system.

The main surface water system in the catchment is the Spicers Creek, which flows in north-westerly direction and joins the Talbragar River at Muronbung in the north- western section of the study area (Figure 2.1). Other tributaries of the Talbragar River contained in the study area include: the Back, Goan, Ballimore and Baragonumbel Creeks. Smaller ephemeral creeks such as Snake Gully and Racecourse Gully also drain into the Spicers Creek. These tributaries contain

Chapter 2: Spicer Creek catchment extremely saline surface waters, ranging from approximately 5,000 μS cm-1 to 13, 000 μS cm-1, which were recorded over the study period.

Surface water Electrical Conductivity (EC) data for the Macquarie River, Talbragar and Spicers Creek were plotted from 1999 to 2004 (Figure 2.4). This data was obtained from three stream data loggers located on the Macquarie River (at Dubbo), on Spicers Creek (at Saxa Bridge) and on the Talbragar River (at Ballimore). The average surface water EC of the Macquarie River was measured at ~420 μS cm-1. This system is fresh and contains good quality drinking and irrigation waters, with the threat of increasing salt loads from tertiary water systems such as the Spicers Creek, the salinity of the Macquarie River may be impacted upon.

Figure 2.4 Stream EC data for Spicers Creek, Talbragar and Macquarie River for period July 1999 to July 2004 (www.waterinfo.dlwc.nsw.gov.au).

The surface water EC for the Talbragar River is slightly more brackish with an average of ~1,500 μS cm-1. The Spicers Creek is far more saline with an average EC value of ~4,900 μS cm-1 and reaching ~10,000 μS cm-1 in June 2003. The Talbragar River became more saline than the Spicers Creek towards the end of the study period. It appears that the EC of the Spicers Creek is influencing the Talbragar River with similar curves experienced from October 2001 to August 2002 and again from July 2003 to January 2004. It also appears that the Talbragar 14

Chapter 2: Spicer Creek catchment

River has experienced an increase in salinity when surface water EC rose to over 6,000 μS cm-1 on two occasions in January 2004 and June 2004.

The Spicers Creek and Talbragar River have the potential to become stagnant and saline surface water systems. In some stretches of these systems, algal blooms have developed due to decreasing oxygen concentrations. This has lead to a loss of biodiversity in the ecosystems of these tributaries. They have become devoid of fish and riparian vegetation due to the high salt loads and low flow conditions.

2.5 SOILS Soils within the Spicers Creek catchment are varied and heavily reliant on the underlying geology of the region. Murphy and Lawrie (1998) have categorised soils groups in the Dubbo area and placed them into soil landscape groups. These classifications, together with fieldwork observations completed by the author, were used to categorise the soils of the Spicers Creek catchment. Seven main soil landscape groups were identified in the catchment, including; ¾ Red-Brown Earths of Ballimore (bm); ¾ Euchrozems of Bodangora (bz); ¾ Earthy Sands of Goonoo (gn); ¾ Red-Brown Earths of Arthurville (ar) ¾ Alluvial Soils of Mitchell Creek (mi); ¾ Yellow Solodic Soils of Lahey’s Creek (lc); and ¾ Soloths of Dapperhill (dh).

The Red-Brown Earths of Ballimore (bm) were formed on quartzose, lithic sandstone, conglomerate, ferruginous sandstone and shales (Murphy and Lawrie, 1998) (Figure 2.5). These soils have formed insitu and comprise the most abundant soil landscape in the catchment. These soil units are prone to salinity development in topographic low areas where yellow and red solodic soil profiles may form (McElroy, 2000). In the southern section of the catchment, Earthy Sands of Goonoo (gn) soil landscape are derived from sandstone-rich lithologies such as the Pilliga Sandstone. These soils are permeable and have a low fertility due to the presence of siliceous parent material.

Chapter 2: Spicer Creek catchment

Figure 2.5 Soil landscapes of the Spicers Creek catchment (modified from Murphy and Lawrie, 1998).

Drainage lines such as Spicers Creek contain alluvial soils known as the Mitchell Creek (mi) soils which have formed on Quaternary aged transported material. These soils have a moderate fertility and have a high water holding capacity. Euchrozems of Bodangora (bz) have formed on the south-eastern side of the catchment. They have formed insitu on Lachlan Fold Belt (LFB) volcanic units. These units have a high erosion hazard under cultivation and have friable surface soils with moderate to high shrink swell potential (Murphy and Lawrie, 1998).

Yellow solodic Lahey’s Creek soils are scattered throughout the eastern side of the catchment. These soils have a low fertility and are susceptible to waterlogging and the formation of sodic and saline subsoils. The Dapper Hill soloths (dh) are interdispersed throughout the yellow solodic soils on the eastern side of the catchment. They have a low fertility and a high erosion hazard. In the southwestern part of the catchment the Red Brown Earths of the Arthurville (ar) soils landscape occur. They contain localised areas of salinisation, where surface soils have the potential to become structurally degraded and have a high erosion hazard.

Chapter 2: Spicer Creek catchment

The soil landscapes in relation to the experimental sites in the catchment will be discussed in detail in Chapter 6, with respect to soil type, clay mineralogy and solute composition.

2.6 NATIVE VEGETATION AND FAUNA Prior to European settlement, communities of open-forest, low native open forest and low woodlands dominated the area (Murphy and Lawrie, 1998). Flat to gently sloping lands have been cleared for cropping and grazing, and the clearing of tall woodlands has given rise to open grasslands and savannah woodland configurations (Anderson, 1992). The distribution of deep-rooted native vegetation in the catchment was identified from aerial photographs taken 13th February 2001 and transposed onto a Landsat image presented in Figure 2.6. Approximately 50 km2 area of the catchment was covered with deep-rooted native vegetation in 2001.

Yarindury State forest located in the western section of the catchment contains the highest density of native vegetation in the catchment. Remnant stretches of vegetation rim the eastern half of the catchment. Scattered kurrajongs provide shade, shelter and fodder and are located on the fertile volcanic soils in the east of the catchment (Grant, 1984). Grey box, white cypress, white box and iron bark trees are scattered throughout the catchment and river gums dominate stream banks of the Spicers Creek. As identified in Figure 2.6 approximately 90% of the catchment has been cleared of native vegetation.

Native grasses for the area include; kangaroo grass and tall oat grass. Many of these native grass species have been replaced by shorter perennials grasses such as weeping grass. This has occurring due to heavy grazing conditions and reduced bush fire frequencies in the area, leaving hardy drought tolerant species to dominate (Murphy & Lawrie, 1998).

The distribution of native grasses has also been altered due to increased areas of salt-affected land where couch grass, windmill grasses and strawberry clover become common, on compacted, waterlogged and salinised soils. Changes in

Chapter 2: Spicer Creek catchment land use practises, resulting in the replacement of native vegetation, has led to increased soil sodicity and salinity in the area. Due to these prevailing salinity problems, various revegetation programs initiated by DIPNR have occurred in the catchment. One such program began in June 2001 where an area of approximately 2 km2 was revegetated with a combination of native vegetation such as acacias, wattles and eucalypts.

Native fauna populations in the area have been reduced due to the influence of European land use practises in the area over the last 150 years. This has resulted in the reduction of native vegetation and habitat. The introduction of pests, such as rabbits and foxes, has also lead to soil degradation and destruction of native vegetation. Common reptiles, such as snakes and marsupials, inhabit the remnant woodlands. Revegetation areas located throughout the catchment have attracted native animals, such as echidnas and kangaroos back to their native habitats, as observed by the author over the study period.

Fig 2.6 Native vegetation distribution in the Spicers Creek catchment overlayed onto a Landsat image of the Spicers Creek catchment (modified from DMR, 2000). 18

Chapter 2: Spicer Creek catchment

2.7 LANDUSE HISTORY Grounds (1984) gives a brief history of the settlement of Europeans and impacts of their land use practises on the area between Dubbo and Wellington (where the Spicers Creek catchment is located). In the 1840’s, squatters occupied the land where they performed low-density sheep grazing. During this period, minimal tree clearing occurred and sheep grazed on natural grasses with minimal impact on the native landscape. In 1881, the extension of the railway to Dubbo occurred and the development of agricultural machinery saw wheat production in the Central West slopes grow from 62,000 ha to 138,000 ha by 1906. Large-scale ringbarking and tree clearing made way for monoculture planting crops such as wheat. Native flora and fauna in the area became under threat. Fox invasions and weed infestation threatened the area and by the late 1930’s, properties became infested with rabbits, and soils were suffering from soil erosion. By the late 1960’s, the current rural environment of the Spicers Creek catchment was established.

The main land use practises in the Spicers Creek catchment include cropping (wheat, lucerne and canola) and sheep grazing. The majority of the catchment has been cleared for cropping and grazing which amounts to approximately 90% of the catchment area (Figure 2.6). Mixed pastures are the dominant land use practises, which cover over 70% of the catchment. Timber production also occurs in Yarindury state forest in the eastern section of the catchment. The fertile soils of the Ballimore (bm) and Arthurville (ar) soil landscape groups support good dryland agricultural cropping but are now under threat of waterlogging, salinity and sodicity. Environmental problems that the area now faces are salinity, dieback of eucalypts, soil erosion and the degradation of water resources, which will be discussed in detail in the following chapters.

2.8 PREVIOUS INVESTIGATIONS A number of hydrogeological and hydrological investigations have been initiated in the Spicers Creek catchment and a summary of these studies is given below.

Schofield (1998), studied the geology, hydrogeology and hydrogeochemistry of the

Ballimore Region. He identified the origin and evolution of effervescent Na-HCO3- rich groundwaters in artesian bores located throughout the Ballimore area. He

Chapter 2: Spicer Creek catchment presented a regional geological history of Eastern Australia and drew focus to the geological history of the Ballimore Region. Using available geophysical data, outcrop data, borehole, rock, and hydrogeochemical data, he identified regional and local groundwater systems and delineated a groundwater divide that separates the Ballimore region from the Great Artesian Basin (GAB).

Mahamed (1999a) discussed the hydrogeology and hydrology of the Spicers Creek catchment and the occurrence of dryland salinity. He identified recharge and discharge areas for the shallow groundwater system. He established the major ions and EC of shallow groundwaters in the catchment, together with the general groundwater flow direction for the shallow aquifer in the Snake Gully catchment. Mahamed (1999b) measured the average hydraulic conductivity (<0.01 to 0.4 m-1 day) of the shallow aquifer in the Snake Gully Creek catchment and calculated the velocity of groundwater to be 0.05 m-1 day to 0.4 m-1 day in Snake Gully catchment. He estimated groundwater travel times across the length (10 km) of Snake Gully catchment, to be approximately 60 to 500 years. He also used chlorofluorocarbons (CFC) dating on shallow groundwaters and found that they were approximately 36 years old.

McElroy (2000), undertook a hydrogeological study for the Spicers Creek catchment. He developed an understanding of the geology and topography of the area and classified how these factors influenced groundwater flow in the catchment. This desktop study of the area, identified 52 groundwater discharge sites that appear to be forming from both the shallow and deep groundwater systems.

Edwards (2002) undertook a study to determine the type, distribution and crystallinity of clay minerals in the Spicers Creek catchment using spectrometry methods. Samples were gathered from experimental Sites 1 and 2 that were established by the author. It was found that soils at depth consisted of primarily halloysite, montmorillonite and kaolinite, with varying degrees of crystallinity. She incorporated Hymap data to produce a kaolinite crystallinity index map and trona abundance map. She found that these maps corresponded well with field spectra results and was able to map salt affected areas using hyperspectral imagery.

Chapter 2: Spicer Creek catchment

Smithson (2002), used a combination of geoscientific techniques to investigate the unconsolidated sedimentary units of the Snake Gully catchment. A conceptual model was developed for this 23.6 km2 catchment, which included a shallow exotic source of salt that was mobilised by a shallow pressurised water table in the area. This study did not consider the deeper groundwater system in various lithologies throughout Spicers Creek catchment. The source of salt was hypothesised as an aeolian source.

Schofield and Jankowski (2003) developed a groundwater flow model for the Ballimore region by using an integrated study, which employed hydrogeochemical and hydrogeological data. They identified two groundwater flow systems; a fractured bedrock regional system and a local groundwater system isolated by a regionally extensive aquiclude. The local system was further divided into three cells; deep, intermediate and shallow cells. Groundwater flow in the deep cell is proposed to be fracture controlled and under artesian pressure. The intermediate cell is a leaky aquitard, which acts as a mixing zone between the deep and shallow cells.

2.9 SUMMARY

¾ Evaporation exceeds rainfall for all months of the year, rainfall is variable and semi-arid climatic conditions prevail within the Spicers Creek catchment; ¾ The loss of native vegetation over the past 100 years due to agricultural activities has left approximately 90% of the catchment devoid of native vegetation; ¾ High concentrations of soluble salts are present within groundwaters, surface waters and soils; ¾ Soils have the tendency to form sodic and saline soil profiles due to underlying bedrock and presence of high concentrations of Na+ and Cl- concentrations; ¾ Surface waters are saline and are discharging large amounts of soluble salts in to the Talbragar River and later the Macquarie River catchment.

Chapter 3: Literature Review

CHAPTER 3: LITERATURE REVIEW

Chapter 3: Literature Review

3.1 SALINITY WITHIN THE ENVIRONMENT

3.1.1 Introduction

In order for salt to become an environmental problem, there needs to be a source of salt, a source of water to mobilise the salt and mechanism(s) that redistribute the salt to locations in the landscape where it can accumulate (Tickell, 1997; Willamson 1990; Walker, 1995). Salt is not created or destroyed but a regional salt input may exceed outputs or vice versa (Walker, 1995). The process of salt accumulation in a catchment can be explained by combined hydrological, hydrogeological, biological and chemical processes (Salama et al., 1993).

Salinisation of land and water is brought about by physical and chemical processes that increase the concentrations of salt in the soil and water (Salama et al, 1999b). Salt within a natural system may be sourced from the regolith, bedrock and/or from aerosols. Agricultural activities in a catchment may alter the salt balance, creating new conduits, enhancing existing pathways and facilitating salt discharge (Walker, 1995). Typically, in a natural groundwater environment, groundwater salinity increases with depth below the ground surface, groundwater residence time and groundwater flow through a groundwater system (Chebotariev, 1955; Richter et al., 1993). Nevertheless, in dryland salinity affected catchments this may not always be the case.

3.1.2 Dryland salinity in Australia

Dryland salinity is seen as one of Australia’s most serious environmental and resource management problems (Pannel, 2001). The political profile of salinity has increased dramatically over recent years, with extensive media coverage and the release of numerous reports, including the Prime Minister’s Science, Engineering and Innovation Council (PMSEIC, 1999), the Salinity Audit of Murray-Darling Basin (Murray-Darling Basin Ministerial Council, 1999); National Dryland Salinity Assessment, (2000) and the National Land and Water Resources Audit (2001). Dryland salinity is a phenomenon that results due to the complex and subtle interactions among the atmosphere, the soil, vegetation, water and people (Salama et al., 1999a).

Chapter 3: Literature Review

The National Dryland Salinity Assessment (2000) estimates that approximately 5.7 million ha of land within Australia has been identified to be at risk or currently affected by dryland salinity, and an estimated 17 million ha will be affected by the year 2050. Hence, the need to further understand the Australian environment is great.

Wood (1923) was first to identify dryland salinity outbreaks and suggested bare cleared ground on the hillsides was susceptible to greater rainfall infiltration. He noted the potential risk of groundwater rise and hence salt mobilisation in this scenario. Secondary salinity of non-irrigated farmland in Australia appears to be a consequence of the change in vegetation or land management practises that leads to increased groundwater recharge, causing the re-distribution of soluble salts in groundwaters and soils (Peck and Hatton, 2003). Dryland salinity is primarily caused by widespread clearing of high water-use native vegetation for the establishment of relatively low water-use annual crops and pastures (Richardson and Narayan, 1995; Pavelic et al., 1997). The correlation between dryland salinity and rainfall has been observed in areas that receive between 300 to 900 mm yr-1 of rainfall. This rainfall has high salt loads, which can accumulate in catchments that have been cleared of native vegetation (Sadler and Williams, 1981; Tickell, 1997). The removal of native forested areas in Australia has lead to increased groundwater recharge, and furthermore, the mobilisation of solutes stored in the landscape (Gunn, 1985).

This shift in hydrologic balance has lead to increased recharge, a rise in hydraulic head and increased discharge, and subsequently the mobilisation of accumulated solutes has led to serious secondary salinisation of agricultural land throughout Australia (Turner, et al., 1987 Salama et al., 1993; Richardson and Narayan, 1995; Pavelic et al., 1997; Salama et al, 1999b).

Extensive research in dryland salinity affected catchments over the past ~30 years has lead to a greater understanding of the Australian environment including identification of salt loads and predicting how the hydrologic cycle influences salt movement in low permeability aquifer systems. Holmes and Wronski (1981) found that afforested catchments yielded less runoff because evapotranspiration rates

Chapter 3: Literature Review are much greater than those of cleared catchments. It has also been identified that evapotranspiration in forests is also greater than in grasslands under the same conditions (Peck, 1978; Greenwood et al., 1985; Ruprecht and Schofield, 1991).

Ruprecht and Schofield (1991) studied the behaviour of water levels over a 13- year period in a catchment that was cleared of native vegetation located in the Wheatbelt of Western Australia. In the first four years, water levels rose 0.11 m year-1, the next five years water levels rose by 1.45 m year-1 and for the last 4 years 2.3 m year-1. These results indicate how reliant the hydrogeology of a catchment is on rainfall recharge and how cumulative increases in water levels can also be observed.

Salama et al. (1999a) evaluated methods used to estimate recharge and discharge in a salinised catchment, together with those used for quantifying surface water flows and salt fluxes in rivers. These methods provide an inferential framework for predicting dryland salinity and allow for the selection of appropriate management scenarios for individual catchment.

The effect of increased recharge since agricultural development and the inability of aquifers to cope with the increases in recharge, are reflected in the rising water levels, not only in shallow aquifers but also in deeper aquifers. George (1992) found due to the lack of groundwater discharge from the catchment, coupled with increased recharge rates after clearing, these elements impacted the deep groundwater system. He found the groundwater system responded as a one- dimensional unit, with recharge occurring until the water table is close enough to the surface for evaporation to begin (George 1992). Therefore, the vertical flux of water into the catchment is greater than the horizontal flux and water levels rise.

Rainfall recharge to a catchment is variable, therefore, episodic recharge contribution to semi-arid environments and how it influences long term recharge rates was assessed by Lewis and Walker (2002). They found that by increasing the yearly water usage of annual crops and pastures by millimetres, large pulses of episodic recharge would not be stopped from reaching the groundwater system and would only slightly limit the impact on the spread of salinity (Lewis and Walker,

Chapter 3: Literature Review

2002). This work implies greater measures for limiting groundwater recharge must be addressed.

Due to the presence of excess groundwater, waterlogging processes influence salt movement and geochemical processes in a salinised catchment. An experimental catchment ‘Ucarro’ was developed within the Wheatbelt in Western Australia and waterlogging was examined extensively by Hatton et al. (2002); McFarlane and Williams (2002); Silberstein et al. (2002); Rundle and Rundle (2002). Waterlogging was found to be the major degradation issue in the catchment due to excess groundwater recharge to the aquifers resulting from catchment clearing. Silberstein et al. (2002) found that in the catchment water levels respond to atmospheric pressures and they found that the deeper aquifer in the catchment is confined during summer when rainfall recharge is less, becoming semi-confined during winter where hydraulic connection with the overlying shallow aquifer is established due to increased rainfall recharge. They also found that between 50 to 70% of rainfall recharged the shallow perched aquifer. The excess groundwater moves laterally in the subsurface ‘C’ soil horizon and accumulates in concave higher permeability areas of the landscape, such as at the break of slope, in cracks that have formed in the soil and in agricultural drains (Silberstein et al., 2002; Hatton et al., 2002; McFarlane and Williams, 2002).

Peck and Hatton (2003) considered a broad-acre estimation of the average recharge rate to one hectare of land. They found vertical water movement occurs through remnant root paths and soil structures the aquifer and the quantity of soluble salts accumulated in the vadose zone is sufficient to result in soil salinity (Peck and Hatton, 2003). These salts are redistributed by diffusion to more permeable areas in the shallow aquifer and upward movement of soil water occurs in the discharge areas of the catchment (Peck and Hatton, 2003).

Dryland salinity research in Eastern Australia has focussed on catchments where salinisation occurs in regolith formed on or from weathered Lachlan Fold Belt (LFB) sediments (Van Dijk, 1969; Jenkins and Dyson, 1983; Jankowski and Acworth, 1993; 1997; Jankowski et al., 1994; Acworth et al., 1997; Acworth and Jankowski, 2001; Cartwright, 2004). Extensive research has been carried out in

Chapter 3: Literature Review the Yass River catchment of NSW to delineate the source of salt and groundwater types present in the catchment. Jankowski and Acworth (1993) described the hydrogeochemistry of groundwaters within the fractured bedrock aquifers and Acworth et al. (1997) described the hydrogeology using various geoscientific techniques used to create a model for dryland salinity development, where Pleistocene debris-flow deposits play a role in the distribution of salinity. They found that these debris-flow deposits contain salt-rich aeolian dust (parna), which accumulated on valley sides and were subsequently transferred to the valley floors by mudflows. Due to the change in hydrological balance, deeper groundwaters now discharge through these salt-rich clay deposits forming saline seepage zones (Jankowski and Acworth, 1993, 1997, 1998; Acworth et al., 1997). Two components are postulated to be essential for the development of dryland salinity in the Dicks Creek area: 1) the presence of a clay-rich and salt-rich debris flow; and 2) the presence of a deep groundwater system discharging through the debris-flow deposits (Acworth et al., 1997).

3.2 SOURCE OF SALT

3.2.1 Introduction

While the link between land clearing and dryland salinity is well established, many questions regarding the origin(s) of salts remain (Cartwright et al., 2004). One of the major challenges facing hydrogeochemical investigations of saline groundwaters is to determine the source of salt (Nordstrom et al, 1989). An understanding of the origin of salts and their distribution in specific landscapes is considered essential for controlling secondary salinisation of soils and natural waters in Australia (Gunn and Richardson, 1979).

Richter et al., (1993) suggests major sources of salt that may contribute to groundwater and soil salinisation. They include; natural saline groundwater, the presence of halite deposits, seawater intrusion, brines associated with oil and gas- fields or saline groundwaters from agricultural effluent. Nordstrom et al., (1989) suggested two general categories for the source of salt based on whether the salinity of the groundwater is allochthonous (salt derived from outside the rock mass) or autochthonous (salt derived from inside the rock mass). Therefore, an

Chapter 3: Literature Review allochthonous source indicates the groundwater salinity has resulted due to sources that are independent of the aquifer system and autochthonous salt is derived from within the aquifer. Source of salts will be discussed in the following section with regards to possible sources of salt in an uncontaminated groundwater system such as the Spicers Creek catchment.

3.2.2 Allochthonous salt sources

3.2.2.1 Meteoric salts

Atmospheric accession from rainfall or dry-fallout may originate from several sources such as; the ocean, volcanic emanations, dust from playa lakes in the arid zone, or salt from industrial urban areas (Gunn and Richardson, 1979). In eastern Australia volcanic sources and anthropogenic origins can be discounted, therefore, the sources of salts may be from aerosols of marine and terrestrial origin (Gunn and Richardson, 1979). Salt in rainfall from most coastal lands is derived from sea- salt aerosols and further inland salts may be derived from a combination of marine and terrestrial dust deflated from salt lakes (Hingston and Gailitis, 1976).

Marine salts may be transported by the wind as aerosols and deposited by rainfall or dry fall out (Bettenay et al., 1964; Sami, 1992; Salama et al, 1999b). Hingston and Gailitis (1976) shows that the accretion of salts from oceanic aerosols, in the Wheatbelt of WA is between 100-250 kg ha-1 yr-1 in high rainfall coastal areas, falling to 10-20 kg ha-1 yr-1 300 km inland (Hatton et al., 2002). Rainfall accession rates have been calculated at ~30 kg ha-1 yr-1 in the Central West Region of NSW (Evans, 1994). The dominance of Na+ and Cl- ions in Australian rainfall indicates that meteoric rainfall waters have a similar ion composition to the ocean (Mazor and George, 1992).

Hingston and Gailitis (1976); Peck (1978); Salama et al (1993b) and George (1992) suggest that the most important source of salt to Australian groundwaters is meteoric salt. Johnson (1987) concluded that salt accretion would take approximately 7,000 to 13,000 years to account for present day observed salt concentrations within the regolith in WA (Hatton et al., 2002). It has been established that large quantities of salts are contributed to the landscape from

Chapter 3: Literature Review airborne aerosols. Chloride is highly mobile in the environment and salts can accumulate in the landscape only when soils, relief, climate and drainage favour their retention (Hingston and Gailitis, 1976). Regolith development provides opportunities for salt accumulation in deeply weathered profiles (Dahlhaus et al., 2000). Hatton and Nulsen (1999) and Hatton et al. (2002) found that a combination of low hydraulic gradients, low aquifer hydraulic conductivity and low pre-clearing rates of recharge in Wheatbelt catchments in WA facilitates the accumulation of meteoric salt in the regolith.

3.2.2.2 Terrestrial aerosols

Windblown salts maybe transported from salt lakes in the form of parna (Butler, 1955). This is deflated from salt lakes located in central Australia and then accumulates within clay-rich sedimentary units (Acworth et al., 1997; Evans, 1998). Considerable volumes of salt are proposed to have been added to catchments from saline dust derived by deflation from saltpans in the adjacent Murray Basin (Evans, 1998; Dahlhaus et al., 2000). Aeolian processes associated with saline lakes are shown to be important in determining solute concentration in groundwater in arid and semiarid environments (Wood and Sanford, 1995). They used a steady state mass balance analysis of Cl- in groundwaters at Doulbe Lakes, a saline lake basin in southern High Plains of Texas, USA. Their work suggests that approximately 4.5 × 105 kg yr-1 of Cl- is removed from a relatively small basin floor (4.76 km2) each year by deflation and that the salt enters the groundwater system down-wind from the lake (Wood and Sanford, 1995).

Acworth and Jankowski (2001) performed a detailed geophysical and hydrogeochemical study over a 10-year period on a small catchment southeast of Yass on the Southern Tablelands of NSW, to investigate the source of salinity. Hydrogeochemical and isotopic evidence suggested groundwaters have not undergone evaporative or transpirative concentration of salt in the groundwater (Acworth and Jankowski, 2001). They found the salt to be of aeolian origin and that it was imported into the catchment with silt during dust storms in the last glacial (Acworth and Jankowski, 2001).

Chapter 3: Literature Review

3.2.3 Autochthonous salt sources

Many authors have used various hydrogeochemical and isotopic techniques to delineate the origin of salts within deep fractured bedrock aquifer systems throughout the world (Bottomly et al., 1984; 1999; Kelly et al., 1986; Gascoyne, 1989; Nordstrom et al., 1989; Gascoyne, 2004). The occurrence of autochthonous salts in deep groundwater systems may have multiple origins including: ¾ Connate marine salts (Frape and Fritz, 1982; Bottomly et al., 1994; Bottomly et al., 1999; Hudak, 2000); ¾ Sedimentary brines (Frape and Fritz, 1982; Land, 1987; Banner et al., 1989;); ¾ Dissolution of evaporite deposits (Johnson, 1981; Manheim and Paull, 1981; Graf, 1982) ¾ Dissolution of grain-boundary salts associated with igneous rocks (Gascoyne and Kamineni, 1993); ¾ Silicate mineral hydrolysis (Gascoyne, 2004); ¾ Water-rock interactions (Edmunds et al., 1984, 1985; Frape et al., 1984; Gascoyne and Kamineni, 1993; Gascoyne, 2004; Nordstrom et al, 1989; Edmunds et al., 1984; Gunn and Richardson, 1979); and/or ¾ Breakdown of fluid inclusions in quartz and other minerals (Nordstrom, 1989; Gunn, 1985).

Contribution of salts from these various autochthonous sources depends on the prior presence of these geological environments leading to salt accumulation, the degree of subsequent weathering, and the amount of flushing the aquifer has subsequently experienced.

3.3 GROUNDWATER SEEPAGES

Once the source of salt to the system has been identified, the mechanisms controlling dryland salinity or groundwater seepage zone development must be addressed. Groundwater seepages form where the watertable is close to the ground surface or actually discharging at the land surface (Peck, 1978; Walker, 1995). Saline seep formation is a salinisation process that is accelerated by dryland farming practises (Johnson, 1994). For a saline seepage to form there

Chapter 3: Literature Review must be a source of salt which is dissolved and transported by groundwater, the water must be undersaturated with respect to the salt during transport, there must be a discharge point for this salt and most importantly there must be the energy (hydrostatic head or density gradient) for the water to flow to the land surface (Johnson, 1981).

3.3.1 Terminology

Classification systems for salt-affected land in Australia was proposed by Peck (1980) and Scav (1980) and further modified by Williams and Bullock (1989) and will be used herein to classify salinisation. The primary focus of this review is dryland salinity development with particular focus on the formation of salt seepages (Figure 3.1). According to Williams and Bullock (1989) land that is experiencing secondary salinity has been salinised after European settlement, which contrasts with primary salinity where lands have become salinised due to natural processes.

3.3.2 Formation of seepage zones

A saline seep is defined as an intermittent or continuous discharge of saline groundwater, at or near the soil surface, which reduces or eliminates crop growth in the affected area because of increased soluble salt concentration in the root zone (Johnson, 1994). The main feature of the problem is the accumulation of soluble salts in the soil profile and a hydrologic disturbance, which redistributes these salts in the landscape (Peck, 1978). The development of a saline seepage occurs due to additional moisture input associated with the change in water balance, which is generally due to the clearing of native vegetation (Peck, 1978; Jankowski and Acworth, 1993; Salama et al., 1999b).

Saline seepages are dynamic in nature and may or may not result in bare and eroded land surfaces together with changes in native vegetation communities (Williams and Bullock, 1989). Groundwater discharge zones are commonly sites of active soil salinisation because salt fluxes are greatest at this point (Salama et al, 1999). Saline seeps develop in a variety of soil types. Seepages vary throughout time, season and from year to year and are reliant on climatic and hydrologic

Chapter 3: Literature Review factors where the developments of ephemeral perched water tables in winter are common (Peck, 1978).

Figure 3.1 Classification of salt affected land in Australia (Williams and Bullock, 1989)

Seeps are a combination of geological, climatic and cultural conditions (Doering and Sandoval, 1976, 1981; Miller et al., 1981). Variations of seep areas are commonly observed over periods of a few years (Halvorson, 1973; Peck, 1978). These fluctuations are mostly attributed to yearly precipitation (Peck, 1978). Doering and Sandoval (1976) and Miller et al. (1981) show that generally annual precipitation must be greater than 350 mm yr-1 for seepage formation to occur.

Chapter 3: Literature Review

Groundwater contained in the seepage zone water does not have to be very saline because evaporation or salt accumulation processes increase groundwater salinity in the landscape (Williams and Bullock, 1989).

3.3.3 Mechanisms controlling salinity seeps

Mechanisms that control the development of saline seepage zones have been summarised in the following section from George et al. (1997); Conram et al. (2000) and Clarke et al. (2002). The main geological and geomorphological mechanisms influencing seepage zone development are; distinctive changes in slope, the presence of permeability contrasts in the aquifer and the presence of geological structures such as dykes and faults that may act as barriers or conduits to groundwater flow.

3.3.3.1 Break of slope

Seepage zones may form at distinct changes in slope or at the break of slope in shallow groundwater systems. Groundwater is forced to discharge due to the fall in hydraulic gradient at the break of slope. The mechanism responsible for groundwater discharge is the permeability contrast between the unweathered and weathered aquifer at the break of slope (Figure 3.2a).

Some examples of seepage zones forming due to this mechanism include; saline seepages of the Great Plains in USA where they usually occur at a change of slope but not necessarily at the low point in the topography (Halvorson and Black, 1974). Van Dijk (1978) identified dryland salting in Eastern Highlands of Australia and found seepages were forming at the change of slope. Jankowski and Acworth (1993) also identified groundwater seepages located close to the change of slope but not always in the lowest point in the landscape in Yass River valley, NSW. Miller et al. (1981) suggests the occurrence of saline seeps at the break of slope is caused primarily by the decline in hydraulic gradient, causing an immediate velocity reduction and resultant groundwater build-up forming a groundwater barrier.

Chapter 3: Literature Review

Figure 3.2 Mechanisms associated with seepage zone development with respect to (a) break of slope (b) permeability contrast in shallow aquifer (NSCP, 2000).

3.3.3.2 Permeability contrasts

Seepage zones may form where a permeability contrast within the aquifer exists. This may be in the form of a bedrock high or change in aquifer lithology. The presence of a bedrock high may force shallow groundwaters to discharge at the land surface where groundwater encounters a lower permeability unit and is forced upwards (Figure 3.2b, 3.3a and 3.3b) The main mechanism responsible for groundwater discharge is the high permeability overlying sediments becoming thinner forcing groundwaters to the surface. Seepage zones also form where permeability contrasts occur in a shallow aquifer due to contrasting hydraulic conductivities.

Johnson (1994) found that seepage zones formed at textural changes in the soil permeability and where low hydraulic conductivity material outcrops. Dryland salinity seeps in a closed drainage basin at Nobleford Alberta form due to discharge of groundwaters where changes in soil texture and slope restrict drainage (Sommerfeldt and MacKay, 1982). Doering and Sandoval (1976) also found seeps often migrate through permeable contact layers between glacial tills and more dense substrata. Seepage zones also form in texture-contrast soils where the upslope soils are permeable and groundwater encounters lower permeability material and groundwater is forced to discharge (Walker, 1995),

Chapter 3: Literature Review

Figure 3.3 Mechanisms associated with seepage zone development with respect to (a) bedrock high (b) change in hydraulic conductivity (NSCP, 2000).

3.3.3.3 Dykes and minor faults

Groundwater seepage zones may form due to the presence of minor geological features such as dykes and minor faults. The mechanism leading to groundwater discharge is controlled by linear features of contrasting hydraulic conductivity to the surrounding units (Figure 3.4a). Engel et al. (1987) showed the association between dolerite dykes and the occurrence of saline seeps in two catchments in southwestern Australia. The linear hydraulic barrier caused by the clay-rich doleritic saprolite results in the impeded flow of groundwater, forcing saline groundwater to the surface. McFarlane and George (1992) identified groundwater forming ponds behind bedrock irregularities in the fractured bedrock.

3.3.3.4 Major Faults

The presence of major fault zones may act as a mechanism for groundwater discharge. The permeability of faults depends on the style of faulting that has occurred. Normal faults occur in tensional environments and form open voids, which enhance permeability. Reverse or thrust faults are caused by compression and the crust is shortened (Foster, 1971). They form closed and impermeable structures where groundwater is unlikely to flow. The discharge of groundwater may occur across topographic divides and is likely to be controlled by large transmissive linear structures. Generally, a higher hydraulic conductivity is experienced within these geological structures. Clarke et al. (2000) found that

Chapter 3: Literature Review large faults were up to 5 times more permeable than the surrounding bedrock and may act as conduits for groundwater flow. The higher hydraulic conductivity found in the faults allows water to flow between topographic catchments. Fractured permeable rock may form the recharge zone of a catchment and relatively impermeable rock may be found in the lower landscape. At the junction of two rock types, groundwaters may be forced to the surface (Thornburn, 1991; Clarke, et al., 1998, 1999, 2000).

Figure 3.4 Mechanisms associated with seepage zone development with respect to (a) dyke (b) fault (NSCP, 2000).

One objective of this review is to address structurally controlled seepage zone development within fractured rock aquifers, therefore, an extensive review of dryland salinity development in relation to structural features is presented in the following section.

3.4 STRUCTURALLY CONTROLLED SEEPAGE ZONES

3.4.1 Structural influences on groundwater flow

Geological structures such as faults, folds and fractures provide both vertical and horizontal pathways for the migration of groundwaters within an aquifer system. Mixing between different aquifers may also occur where geological units are disrupted and provide pathways for groundwater migration throughout fractured aquifer systems (Johnson, 1981; Land and Prezbindowski, 1981; Evans, 1982; Fritz and Frape, 1982; Maclay and Small, 1983; Banner et al, 1989, Gascoyne, 1989; Nordstrom et al., 1989, Gascoyne and Kaminemi, 1993; Gascoyne et al,

Chapter 3: Literature Review

1993; Oetting et al, 1996; Ceron et al, 1998; Edmunds and Smedley, 2000; Cartwright et al., 2002; Avisar et al., 2004; Gascoyne, 2004).

Land and Prezbindowski (1981) were the first to identify that major fault systems serve as pathways for vertical movement of basinal brines into the Lower Cretaceous section of the Edwards Aquifer in Texas USA. Groundwater movement in this system was observed to have strong up-fault and up-dip components.

Maclay and Small (1983) extended this research and found that within the Edwards Aquifer, faulting of these units controls the groundwater flow direction and mixing between deeper groundwaters along these fault zones into shallow aquifer systems occurs. The restriction of lateral groundwater flow occurs where fault displacements have juxtaposed permeable strata opposite impermeable strata (Maclay and Small, 1983). Such displacements lead to permeable stratigraphic units forming adjacent to relatively impermeable units, thus reducing the capacity for groundwater flow across the fault, causing it to be diverted along 2- the fault. Within the Edwards Aquifer a higher than normal SO4 concentration occurs within the overlying aquifer further suggesting that deeper groundwaters are migrating up-dip into the overlying aquifer system (Maclay and Small, 1983).

Oetting et al. (1996) undertook further investigations of the Edwards Aquifer using a geochemical and isotopic approach, which indicated high-angle normal faults crosscut and offset the Edwards aquifer, and these fractures provide both vertical horizontal pathways for the migration of extraformational fluid into the Edwards aquifer. They estimated groundwater flow up-dip and down-dip in the faults range from 90 to 900 cm day-1 and from 1 to 2 cm day-1, respectively. Brines mix with evolved meteoric waters and reflect a history of interaction with evaporites and siliclastics and may have migrated up-dip or along faults from a depth greater than 5 km. The fraction of saline groundwaters from the underlying units in mixtures with fresh groundwaters in the Edwards aquifer can exceed 80% (Oetting et al., 1996).

Chapter 3: Literature Review

Gascoyne and Kamineni (1993), Gascoyne et al. (1993) and Gascoyne (1993, 2004) found that deep groundwaters within a fractured granitic aquifer, flow up-dip of fracture zones towards the land surface in the Canadian Shield. Along this pathway dissolved salt concentrations of groundwaters increase due to the dissolution of saline pore fluids and due to mixing with groundwater from deeper fracture zones (Gascoyne, 2004). The presence of deep groundwaters within fault and shear zone systems in the Canadian Shield aquifer was also assessed by Bottomley et al. (1994, 1999).

3.4.2 Structurally controlled dryland salinity

Structurally controlled dryland salinity development has been recognised as an important mechanism influencing seepage zone formation. The association between the presence of geological structures such as lineaments, dykes, bedrock highs, faults and fractures or shear zones, and dryland salinity development has been identified by various authors such as Ventriss et al. (1982); Jenkins and Dyson, (1983); Engel et al. (1987); Lewis, (1991); Ferdowsian and Greenham, (1992); McFarlane et al. (1992); Salama et al. (1993b); Tuckson, (1995); Clarke et al., (1998, 1999, 2000, 2002) in Australia.

Engel et al. (1987) identified doleritic dykes that act as a barrier to groundwater flow leading to groundwater discharge and hence salinisation in WA (Clarke et al., 1998). Knight et al. (1989) illustrated the connection between dryland salinisation in northern NSW, where saline groundwaters are discharging through a permeable fault zone, forming saline-sodic soils. The fault provides a hydrostatic link between the shallow groundwater and high-pressured artesian water of the sandstone basement aquifer (Knight et al., 1989).

Lewis (1991) showed the spatial association between linear geological features and salt-affected land in the central region of the Wheatbelt in WA. He suggested these lineaments could act as carriers or barriers to groundwater flow, initiating the development of dryland salinity. Ferdowsian and Greenham (1992) showed how saline seeps are associated with fractured rock aquifers, where an increase in

Chapter 3: Literature Review hydraulic conductivity was experienced on one side of the fracture zone and a decrease on the other side (Clarke et al., 1998a). Salama et al. (1993) demonstrated how salt accumulation at Cuballing Catchment WA, occurs upstream of geological structures. When the water table reaches the surface, groundwater discharge associated with these structures is lost by evaporation and the salt is concentrated at the land surface increasing groundwater salinisation (Salama et al., 1993). Jankowski et al. 1998(b) also showed that an increase in salinity in a shallow system is associated with the discharge of saline groundwaters from Ordovician metasediments of marine origin. They also found that groundwater discharge is closely related to the underlying fracture geometry of the bedrock unit.

Jankowski and Acworth (1993, 1997, 1998) described the origin of dryland salinity, which is associated with fractured bedrock aquifers in the Southern Tablelands, NSW. The development of saline seepages is closely related to the fracture geometry of the bedrock. These seepages originate from the fractured bedrock aquifer on the lower slopes and valley floors, where the bedrock is close to the ground surface and groundwater in the fractured bedrock aquifer is discharging under artesian pressure into the salt-rich shallow aquifer system. Bradd (1993) noted parallel valleys and calculated very fast groundwater flow rates in the Williams Creek catchment, Yass, which is presumably due to the presence of large fracture openings (Tuckson, 1995).

Clarke et al., (1999) studied three groups of third order catchments in the Wheatbelt of WA and found the most salinised catchment was underlain by a major fault that is hundreds of kilometres long and hundreds of metres wide. They found that the hydraulic conductivity was as much as five times greater than the surrounding bedrock allowing for enhanced groundwater flow (Clarke et al., 1999; Clarke et al., 2000). These large geologically-controlled differences in hydraulic conductivity around the fault have influenced dryland salinity development (Clarke et al., 2000).

Tuckson (1995) identified discontinuously permeable fracture zones in the bedrock that are probably giving rise to the ‘patchy’ distribution of salinity. He found that a

Chapter 3: Literature Review fracture seemed to coincide with a largely saline area in the Cujegong Valley in the Riverina area of NSW. Beavis (2000) found that structural discontinuities occurred in the soils above an underlying fractured rock mass and that along these structural discontinuities groundwater flow occurs. She was also able to demonstrate a significant correlation between the alignment of gully systems and faults in mid-western NSW.

Clarke et al. (2002) overviewed the impacts of geological structures on the development of dryland salinity and emphased that further research is required to identify the ability of major faults to conduct groundwater from one catchment to another and the effect that they have on seepage zone development. He noted that major faults have the potential to substantially increase the salinisation of water and, to a lesser extent, increase the area of salinised land (Clarke et al., 1998b).

3.5 GEOCHMEMICAL PROCESSES IN SEEPAGES ZONES

3.5.1 Introduction Within an aquifer system, generally the observed groundwater salinity is a function of; groundwater residence time, the availability of soluble salts in the aquifer and the chemical balance of the water. However, within a groundwater seepage zone hydrogeochemical processes are governed by the presence of salt. The mechanisms leading to the evolution of the chemical composition of groundwater and the accumulation of salt within a catchment occur over a long period (Salama et al., 1993a). In seepage zones, the main geochemical processes influencing soil and groundwater chemistry are the presence of soluble salts and the increase in water-sediment ratio due to waterlogging.

Peck (1978); Doering and Sandoval (1991); Salama et al. (1999b); Jankowski and Acworth (1998); and Fitzpatrick et al. (1996) have reviewed and identified various waterlogging, salinisation and sodification processes that occur within seepage zones. These processes mostly rely on the fluctuating water table, which enhances oxidation and reduction, eluviation and illuviation of sediments and ions, and salinisation and solonisation of the soil profile. The driving force behind these

Chapter 3: Literature Review processes is the cyclic nature of these seepage zone profiles due to seasonal fluctuations in rainfall recharge (Halvorson, 1973; Peck, 1978). Therefore, the resultant hydrogeochemical reactions occurring within the seepage zone are reliant on the fluctuating water table.

3.5.1.1 Waterlogging and redox effects Prolonged saturation of soil pores leads to the depletion of oxygen and build-up of

CO2 from biological sources (Naidu and Rengasamy, 1995). When the profile is waterlogged, anoxic or sub-oxic conditions develop which lead to the chemical transformation of nutrients in the soil, and later results in either nutrient deficiency or toxicity (Naidu and Rengasamy, 1995). The effect of waterlogging on plant growth depends on the duration of saturation, the proportion of the root zone affected, the rate at which oxygen is depleted, the effect on availability and uptake of nutrients and the accumulation of toxins (McFarlane and Williamson, 2002). The rate of oxygen depletion and the degree of harm caused by waterlogging, depends upon temperature, organic matter content, salinity, acidity and the stage of plant growth (McFarlane and Williamson, 2002).

Waterlogged conditions experienced within the saturated zone favours the formation of a thick black sulfidic material via sulfidisation processes as described by Fitzpatrick et al. (1996) in non-tidal seepage and marsh areas strongly affected by waterlogging, dryland salinity and erosion. Black sulphide-rich material forms due to crystallisation of secondary fine-grained pyrite framboids by the action of sulphur-reducing bacteria in the presence of organic matter (Salama et al, 1999b). When the water table rises to the surface, the seepage zones are flushed with fresh water and solonisation and sulphurisation takes place (Salama et al, 1999b). The sulphides are then transformed to sulphates, in the presence of dissolved oxygen when the profile becomes drained (Salama et al, 1999b). Fitzpatrick et al. (1996) also showed that in saline soils during dry periods, distinctive black (FeS- rich) blotches form together with a large number of other minerals such as gypsum

(CaSO4.2H2O), halite (NaCl), thenardite (Na2SO4), mirabilite (Na2SO4.10H2O) and iron oxides (ferrihydrite).

Chapter 3: Literature Review

3.5.1.2 Weathering reactions The chemical weathering of minerals contained within in the soil zone leads to an increase in soil salinity, where soil solutions become depleted in Ca2+ and Mg2+ (Sposito, 1989). Chemical weathering produces soluble ions, colloidal gels and microcrystalline substances or clay minerals. These soluble ions may then be leached from the profile or become bonded to clay minerals (Duchaufour, 1982). The presence of Cl- can be used as an indication of the importance of weathering as it rarely originates from weathering processes in the soil zone (Sami, 1992; Herczeg et al., 1993).

Smith and Drever (1976) found in springs within arid environments Na+ contribution from weathering is minor compared to its contribution from the atmosphere. Presumably, this is because the accumulation of the salts in the soil zone inhibits chemical weathering (Drever and Smith, 1978). In saline environments, Szabolcs (1989) noted that the chemical compositions of most soils are not the same as the parent rocks due to various salinisation and sodification processes. If the water has been subjected to an evaporation-solution cycle, silica + - will tend to be retained in the soil, while Na and HCO3 are liberated into the water (Drever and Smith, 1978).

Salama et al. (1993a) discuss weathering reactions in a dryland salinity-affected catchment, before and after clearing. They suggested prior to clearing the groundwater chemistry was controlled by high CO2 concentration, which was generated in the soil zone by native vegetation. The abundance of CO2 in groundwaters created mildly acidic conditions leading to the weathering of silicates + - in the soil zone producing a groundwater rich in Na , HCO3 and H4SiO4. Post- clearing, the system becomes partially closed to CO2 because the generation of

CO2 has decreased due to the removal of deep-rooted native vegetation (Salama et al., 1993). Therefore, in the seepage zones weathering reactions become less dominant in the saline affected soils due to the decrease in CO2 concentration, which leads to an increase in groundwater pH.

Chapter 3: Literature Review

3.5.1.3 Salt accumulation processes Most saline seepage zones occur in arid to semi-arid environments. Therefore, evaporation processes play a major role in influencing seepage zone chemistry, particularly at the land surface. Smith and Drever (1976) and Drever and Smith (1978) indicated that the cyclic wetting and drying of the soil zone has a major influence on the chemistry of groundwater in arid terrains. Hellwig (1974) found a very close relationship between evaporation and the removal of salts from solution in a sand-filled experimental tank.

In summer, an upward hydraulic gradient may dominate due to evaporation from the capillary fringe and in winter due to increased recharge and lower evapotranspiration rates, the hydraulic gradients may reverse leading to the flushing of salts to the groundwater system after rainfall and increased salinity (Richter and Kreitler, 1987; Salama et al., 1993b; Cartwright et al., 2004). Evaporation is minimal when the water table is located between 1.5 to 3 m below the ground surface (bgs) (Salama et al, 1999a) and in salinised areas the watertable is generally located less than 1.5 m bgs from the land surface (Jenkins and Dyson, 1983), indicating evaporation influences salt accumulation at the land surface.

The best indicators of the extent of concentration of water by evapotranspiration is the Cl- concentration (Smith and Drever, 1976). It can serve as a monitor for evaporative concentration because it is removed only during the last stages of evaporation by precipitation of minerals such as halite and sylvite (Eugster and Maglione, 1979). However, Turner et al., (1987) used isotopes to study the vadose zone and they concluded evaporation from the soil surface plays only a minor role in solute concentration in the soil profile in a dryland salinity affected catchment (Peck and Hatton, 2003). They found that the dominant process leading to solute accumulation within the vadose zone was ion exclusion during water uptake by plant roots (Peck and Hatton, 2003). Jankowski and Shekarforoush (2000) also found by using stable isotopes that evaporative concentration is not the primary salt accumulation process in dryland salinity affected catchments. The variability in salt distribution in Liverpool Plains north-eastern NSW, was noted by Timms et al., (2001). They implied that evaporative or evaporative transpirative concentration is 43

Chapter 3: Literature Review not the prime cause of the salinity, otherwise the distribution of salinity would be even across the Plains.

Numerous studies have identified that evaporation is not the primary mechanism controlling salt accumulation within saline seepage zones, therefore two conflicting models of salt accumulation were devised in WA. The first model has salt entering the soil profile with rainwater, meeting a low permeability subsoil and becoming concentrated in the unsaturated zone as water is removed by evapotranspiration (Marshall and Holmes, 1988; Salama et al., 1993a). The second model has recharge water transporting salt to discharge zones through confined and unconfined aquifers and ion exclusion then concentrates the salt in the discharge area (Peck, 1978; Dyson, 1983). Both models indicate evaporative transpiration is the main control on concentration Cl- in the shallow aquifer.

3.5.1.4 Soil sodicity and salinity within seepage zones Soil salinity and sodicity is a major problem associated with groundwater seepage zone formation. The dominant soil salinisation processes are; cation exchange, aggregate dispersion, surface sealing, loss of soil structure and shrinkage and swelling (Duchaufour, 1982; Szabolcs, 1989; Walker, 1995). Ions are released into soil solution from weathering or from saline groundwater and tend to accumulate as secondary minerals within dry soils such as clay minerals, carbonates and sulphates (Sposito, 1989).

A soil is classified as saline when the soil solution EC is greater than 4 dS m-1 and soil pH less than 8.5 (Table 3.1). The dominant ions in saline seeps and associated soils in Australia are Na+ and Cl- (Peck, 1978). The amount of salt stored in the soil profile depends mainly on the soil type, rainfall and geochemical reactions (Salama et al, 1999). Saline soils are usually flocculated and water permeability is good (Sparks, 2003). But the major problem is the presence of soluble salts (Sparks, 2003). Salt-affected soils have a characteristic fluffy appearance when dry and other common features include mottling or gleyed colour, indicating the reduction of iron in the soil due to the persistence of a high water table (Thornburn, 1991).

Chapter 3: Literature Review

Table 3.1 Chemical characteristics of saline, non-saline sodic and saline sodic soils (Balba, 1995).

Exchangeable Sodium % Soil EC dS m-1 (ESP) pH saline >4 <15 <8.5 sodic <4 >15 >8.5 saline sodic >4 >15 <8.5

Deep weathering increases the ability of the profile to store salts, because the clayey material usually has a higher porosity than original rock, increasing its volume for storage (Tickell, 1997). The distribution of extensive salt-affected soils in eastern Australia is closely correlated with occurrences of the old residual landscapes of the weathered mantle that covered most of the continent during the Tertiary (Gunn and Richardson, 1979).

Sodicity occurs when there is an abundance of Na+, which leads to the degradation of soils making them more dispersible and hence more erodible (Sumner, 1995). Sodic soils exhibit poor soil-water and soil-air relationships, these properties adversely affect root growth, restricting plant production (Rengasamy and Olsson, 1991). Northcote and Skene (1972) reported that sodic soils occupy approximately ~27% of the total land surface in Australia where as saline soils only occupy ~5%. Sodic soils generally occur where annual rainfall is between 250-600 mm yr-1 (Naidu and Rengasamy, 1995). Soils are classified as sodic when the soil solution Exchangeable Sodium Percentage (ESP) is greater than 15 and pH is greater than 8.5 (Balba, 1995) (Table 3.1). However, for Australian soils Northcote and Skene (1972) established a value of ESP >6 in the top metre of the soil profile as the Australian definition of a sodic soil. Sodic soils have a pH between 8.5 and

10, where the high pH occurs due to hydrolysis of Na2CO3. Since the pH is high, 2- 2+ 2+ CO3 is present and Ca and Mg may be precipitated as carbonate. Therefore, soil solution concentration of Ca2+ and Mg2+ remain low in sodic soils (Sparks, 2003).

Sodic soils may be coarser-textured on the surface and have higher clay contents in the subsurface horizon due to leaching of clay material that is Na-saturated. Consequently, the subsoil is dispersed, permeability is low and prismatic in

Chapter 3: Literature Review structure (Balba, 1995; Sparks, 2003). A high concentration of Na+ usually leads to the formation of dense structured soils (Naidu et al., 1995). If a soil has high quantities of Na+ and low EC, soil permeability, hydraulic conductivity and the infiltration rate are decreased due to swelling and dispersion of clays and slaking of aggregates (Sparks, 2003).

In an environment where alternating wetting and drying regimes occur, a soil or clay is likely to swell and crack leading to torn plant roots (Magaritz and Nadler, 1993). A drop in infiltration rate of water due to sodicity leads to a decrease in the efficiency of salt leaching due to the movement through only part of the soil pores, which then leads to a further increase in salinity (Magaritz and Nadler, 1993). Swelling causes the soil pores to become narrower and slaking reduces the number of macropores through which water and solutes can flow, resulting in the plugging of pores by the dispersed clay (Sparks, 2003). High levels of Na+ combined with low salinity rainfall recharge cause the dispersion of clay particles that lead to the sealing and decrease in hydraulic conductivity and aeration, which results in increased runoff and erosion (Magaritz and Nadler, 1993).

3.5.1.5 Surficial precipitates In salt affected soils, mineral precipitation is a dominant process, and the most important means of salt accumulation (Szabolcs, 1989). Garrels and MacKenzie (1967) estimated that modern evaporite deposits have been dissolved and re- precipitated 15 times in the last 3 billion years, resulting in an average cycle of 200 million years (Richter et al., 1993). The accumulation of halite crystals is generally a surficial phenomenon and is not the main mechanism of solute concentration in groundwater (Turner et al., 1987).

The composition of a precipitated crust depends on the cations present in the soil profile, mineral solubility and leaching (Walker, 1995). The most soluble salts will dissolve and mobilise first such as halite and they are the last to precipitate at the surface (Eugster and Hardie, 1978). NaCl will tend to move up and down the profile where as carbonates tend to accumulate in the one soil horizon (Walker, 1995).

Chapter 3: Literature Review

During summer, seepage zones soil profiles are generally drained, surficial precipitates form such as reddish-yellow impermeable iron-rich crusts (Fitzpatrick et al. 1996) and evaporative minerals precipitated depending on the concentration of elements in solution and the thermodynamic properties of the discharged water and precipitated minerals. Evaporative mineral crusts formed on seeps in North Dakota are dominated by Na, Mg and Ca-sulphates, such as konaite, thenardite, hexahydrite, and bloedite (Timpson et al,. 1986; Johnson, 1994). Two examples of precipitates that have formed in groundwater seepage zones in the Spicers Creek catchment are represented in Figures 3.5 and 3.6.

Johnson (1994) found that the principle evaporative minerals in saline crusts were; thenardite, gypsum and hexahydrite which are sulphate minerals of Ca2+, Na+ and Mg2+ (Johnson, 1994). He also identified quartz that was incorporated into the precipitate from the local soils.

Jankowski and Acworth (1997) also analysed the white surficial precipitates formed at surface of seepage zones and found they contained halite, a magnesium-chloride-carbonate-hydrate, aragonite, anhydrite and hexahydrite minerals.

Figure 3.5 Examples of surficial precipitates in that have formed on the land surface in seepage zones, Spicers Creek catchment.

Chapter 3: Literature Review

Figure 3.6 Examples of surficial precipitates in that have formed on the land surface in seepage zones, Spicers Creek catchment.

Valenza et al., (2000) found that black crusts were composed of halite and trona, and white crusts were composed of thenardite (Na2SO4), bloedite (Na2Mg(SO4)2,

4H2O), glauberite (Na2Ca(SO4)2), gypsum and halite. These crusts formed because of long term irrigation, soil degradation of inner delta of the Niger River, Mali. The chemistry and mineralogy of salt crusts can be concluded to be highly variable and a fraction of local groundwater chemistry.

Thornburn et al. (1992) suggests that salt crusting may act as a surface-mulching layer in the seepage zone, preventing diffuse discharge (Walker, 1995). Smith and Drever (1976) found that when larger recharge events occur the percolating waters redissolve accumulated salts in the soils and transported them to the groundwater system. The same is true for the behaviour of surficial crusts or precipitates in seepage zones where they form in summer when evapotranspiration rates are high. They redissolve in winter when recharge increases. The distribution of salts is dependent on recharge intensity, whether the salts infiltrate to the groundwater system with diffuse rainfall or if they are transported with runoff during episodic recharge events.

3.6 SUMMARY

¾ Salt is neither created nor destroyed during salinisation, but regional salt balances may be altered due to agricultural practises in a catchment;

Chapter 3: Literature Review

¾ Over 30 years of dryland salinity research shows a correlation between salinity and increased recharge, due to the removal of native vegetation and dryland salinity; ¾ It is important to identify if the salt is allochthonous (derived from outside the rock mass) or autochthonous (derived from the rock mass) to estimate catchment salt balances; ¾ Groundwater seepages zones associated with dryland salinity vary seasonally, from year to year and throughout time; ¾ Various mechanisms control groundwater discharge and hence the development of a groundwater seepage zone; ¾ Geological structures within the basement rocks may provide horizontal and vertical pathways for groundwater flow; ¾ Structurally controlled dryland salinity development has been recognised in WA and to a lesser degree in NSW; ¾ Further research is required to identify the ability of major faults to conduct groundwater within dryland salinity affected catchments; and ¾ The dominant geochemical controls influencing seepage zone formation are waterlogging and subsequent redox processes, and the formation of surficial precipitates that accumulate at the surface of the seepage zone due to evaporation.

Chapter 4: Geological Complexity of Spicers creek catchment

CHAPTER 4: GEOLOGICAL COMPLEXITY OF THE SPICERS CREEK CATCHMENT

50 Chapter 4: Geological Complexity of Spicers creek catchment

4.1 INTRODUCTION The Spicers Creek catchment is geologically complex and landscape evolution is closely related to the underlying geology (Morgan and Jankowski, 2004). The study area is situated on the southern margin of the Gunnedah and Surat Basins which both overly the western margin of the Lachlan Fold Belt (LFB). The Palaeozoic basement rocks of the LFB have been regionally metamorphosed and contain north-south trending faults, folds, and fractures (Schofield, 1998).

The Gunnedah Basin unconformably overlies the LFB basement rocks and contains Permian to Triassic, marine to terrestrial fluvial sediments with some volcanics (Meakin and Morgan, 1999). The sediments of the Surat Basin were deposited over the Gunnedah Basin sediments during the Jurassic-Cretaceous period. These units represent successive deposition in braided streams, meandering streams, and finally swamps, lakes and deltas (Othman and Ward, 2002). These sedimentary cover rocks dip in a north-westerly direction (Schofield, 1998), cover the majority of the western half of the catchment, and are absent in the eastern part of the catchment (Meakin and Morgan, 1999). Quaternary alluvial and colluvial sediments were deposited in drainage systems and areas with low topographic relief.

4.2 REGIONAL GEOLOGY The geology of the Dubbo region has been extensively investigated by Schofield (1998) and more recently Meakin and Morgan (1999). This area contains a wide variety of lithologies that range in age from Ordovician to recent and have undergone several stages of structural deformation. The Palaeozoic basement rocks of the LFB in the Spicers Creek catchment are located between the Molong and Hill End structural zones within the Macquarie Thrust Sheet (Glenn, 1999) (Figure 4.1). A major thrust fault known as the Nindethana Fault runs through the centre of the catchment, in a north-south direction and dips towards the east. Palaeozoic basement rocks outcrop on the eastern half of the catchment with Surat and Gunnedah Basin sediments to the west (Figure 4.1).

51 Chapter 4: Geological Complexity of Spicers creek catchment

Figure 4.1 Simplified geological framework of the Dubbo 1:250 000 map sheet area (modified from Meakin and Morgan, 1999).

52 Chapter 4: Geological Complexity of Spicers creek catchment

4.2.1 Lachlan Fold Belt in the Dubbo Region The Dubbo region is located within the eastern belt of the Hill End-Cooma Zone of the LFB. The Lachlan Orogen basement rocks in the Dubbo region have been divided into several lithotectonic events based on their age, lithology and depositional environments (Meakin and Morgan, 1999). The following is a summary of the different geological events that occurred in the LFB within the Spicers Creek catchment area.

Prior to 450 Ma, the present day Dubbo region was part of the ancient Pacific Ocean. A westward movement of the Pacific Oceanic Plate against the Australian Continental Plate resulted in a converging plate boundary, leading to the development of the LFB (Holmes, 1984). In the early Ordovician, the basement geology of the Dubbo region was deposited in a deep marine setting. This unit is known as the Adaminaby Group and consists of thick quartz-rich turbidite and pelagic sediments (Morgan et al, 1999a).

An extensive hiatus occurred throughout the area before the deposition of the overlying mafic volcanic units that were derived from the Molong Volcanic Belt. During the Early to Late Ordovician period, the Molong Volcanic Belt began to develop as part of a single north-south volcanic arc known as the Macquarie Volcanic Arc (Morgan et al, 1999a). Mafic volcanic rocks were derived from this volcanic activity and this arc was the centre of volcanic activity for the area. To the west of the Macquarie Arc, the deep sea Cowra Trough environment was forming and to the east, the Monaro Slope was descending to the Pacific Ocean (Holmes, 1984). Volcanic sediments were deposited in a sub-marine to sub-aerial volcanic environment and during the Late Darwillian or Early Gisbornian, units such as the Cabbone Group formed (Meakin and Morgan, 1999). Shallow to emergent volcanic islands formed throughout the area and limestone reefs fringed these volcanic highs as seen in Figure 4.2. Volcaniclastic aprons of silt and boulder sized material were transported as turbidite and debris flows down the side of the volcanic highs.

53 Chapter 4: Geological Complexity of Spicers creek catchment

Figure 4.2 Geological environment of the Ordovician period for the Dubbo region (modified from Schofield, 1998).

A major hiatus in volcanism occurred during the Middle to Late Ordovician. After widespread Ordovician sedimentation, deformation occurred during the Late Ordovician to Early Silurian (Schofield, 1998). This was known as the Benambran Orogeny. This event caused minor deformation of the Macquarie Volcanic Arc and the geological units contained within this area.

During the Late Early Silurian to Early Devonian, a broad shelf known as the Mumbil Shelf developed on the Ordovician basement rocks. Trans-extensional forces in the Early or Late Ludlow caused the Ordovician Macquarie Volcanic Arc to split (Morgan et al, 1999a) and the crust between the Mumbil Shelf and Capertee Rise became thinner resulting in deep marine waters entering the area, forming the Hill End Trough (HET) (Packham, 1969).

During the Late Early Silurian to Earliest Devonian, felsic volcanism developed on the eastern margin of the Mumbil Shelf forming units such as the Mumbil Group (Morgan, et al, 1999a). This unit was deposited in an initially shallow marine environment on the Mumbil Shelf, which consisted of volcanic islands with

54 Chapter 4: Geological Complexity of Spicers creek catchment surrounding reefs and as the shelf began to subside, turbidite flow deposits formed. This environment of deposition continued until the end of the Silurian period. During the Early Devonian, submarine to sub-aerial mafic to intermediate volcanism occurred along the Mumbil Shelf depositing volcanic and volcaniclastic rocks, together with the formation of carbonates of the Grega group over the Mumbil Shelf. A syndepositional listric fault produced a fault scarp (possibly a precursor to the Nindethana Fault) on the eastern margin of the Mumbil Shelf and caused local uplift (Meakin and Morgan, 1999).

In the deep marine setting of the HET, turbidites and volcaniclastic units of the Cunningham Formation were deposited during the Early Devonian period (Morgan et al, 1999a). Figure 4.3 depicts mud and sand deposition on the progressively subsiding Cowra Trough and Mumbil Shelf with submarine to locally sub-aerial silicic volcanism occurring forming the Gleneski Formation (Morgan et al., 1999a).

Figure 4.4 shows the geological environment of the Early Devonian were submarine to locally sub-aerial, mafic to intermediate volcanism occurred along the Mumbil Shelf and on the western side of the Cowra Trough. The Cuga Burga Volcanics were deposited during this time.

During the Middle Devonian, regional uplifting, folding and contractional fault movement occurred, which lead to the termination of sediment deposition throughout the Dubbo area (Meakin and Morgan, 1999). This was known as the Tabberabberan Orogeny. Folding and thrusting occurred causing north-south compression of the existing units (Schofield, 1998). This intense movement led to crustal shortening where sediments were raised, folded, faulted and eroded during this intense deformation event. Scattered intrusions formed throughout the Dubbo region during this time.

During the Early to Late Carboniferous another deformation event occurred which produced folding, thrusting and east-west compressions in the Dubbo area. This was due to the development of a large subduction complex in the New England Orogen (Fergusson and Coney, 1992). The already folded Ordovician and Silurian

55 Chapter 4: Geological Complexity of Spicers creek catchment units were deformed further producing open to tight north-south folds with axial planar cleavage (Morgan et al, 1999a).

Figure 4.3 Schematic block diagram of the palaeogeography of the central and western parts of the Dubbo 1: 250,000 during the Late Silurian (modified from Meakin and Morgan, 1999).

Regional metamorphism occurred during this time with sub-greenschist and greenschist facies developing (Pemberton, 1990). Another deformation event occurred during the Early to Late Carboniferous period, in which the emplacement of plutons such as the Gulgong, Wuulman and Yeoval granites occurred (Morgan et al, 1999a). These units intruded the Ordovician-Silurian basement rocks of the Dubbo area and caused further north-south compression. Smaller satellite intrusions developed around the larger intrusions and these granites are generally concentrated along major structures in the Dubbo area (Morgan et al, 1999a).

56 Chapter 4: Geological Complexity of Spicers creek catchment

Figure 4.4 Schematic block diagram of the palaeogeography of the central and western parts of the Dubbo 1: 250,000 during the Early Devonian (modified Meakin and Morgan, 1999).

4.2.2 Sydney –Gunnedah Basin During the Early to Late Carboniferous to Early Permian, the Sydney-Gunnedah Basin began to form as a rift and succeeding foreland basin system adjacent to Permo-Triassic orogen of New England Fold Belt (Othman and Ward, 2002). The Sydney-Gunnedah Basin formed as an elongate basin that lies between the Lachlan Orogen to the west and New England Orogen to the east. During the Early Permian, fluvio-lacustrine and minor glacial sediments were deposited and basin subsidence associated with tectonism resulted in a marine transgression. A layer of shallow marine sediments was deposited in the area followed by the development of swamp environments (Morgan et al, 1999a). Depositional cycles in the Sydney-Gunnedah Basin in the Permian consisted of three constructive depositional episodes where fluvial and deltaic successions were deposited and separated by two significant marine transgressions (Othman and Ward, 2002). The New England Orogen was thrust further over the Sydney-Gunnedah Basin

57 Chapter 4: Geological Complexity of Spicers creek catchment during the Middle Triassic, which led to a hiatus in sedimentation (Glen and Brown, 1993).

4.2.3 Surat Basin The Surat Basin is a structural infrabasin of the Great Australian Basin (GAB) and occupies the northern edge of the Dubbo 1:250, 000 map sheet area (Pogson et al., 1999). The Surat Basin underwent five major depositional cycles representing different river environments, ranging from braided streams, meandering streams to swamps, lakes and deltaic environments (Exon, 1974; Othman and Ward, 2002). These sediments were deposited during the Middle Jurassic to Cretaceous and unconformably overlie the Sydney-Gunnedah Basin sediments.

4.2.4 Cainozoic sediments At the beginning of the Cainozoic, terrestrial sediments were subject to extreme weathering and erosion when high energy braided river systems reduced the elevation of the landscape (Morgan et al, 1999a). These sediments were deposited as alluvial sediments within the existing drainage systems forming alluvial deposits. During the Mid to Late Eocene and Miocene, intraplate basaltic lava eruptions occurred along the east coast of Australia (Morgan et al, 1999a). This volcanism occurred within the Ballimore Region approximately 17 Ma in the Middle Miocene and lasted approximately 7 Ma until the Late Miocene (~10 Ma) (Wellman and McDougall, 1974; Schofield, 1998). These basalts formed volcanoes, lava sheets, sills and valley fills (Morgan et al, 1999a). The area is now subject to erosional events and recent sediments are transported as alluvium or colluvium to lower elevations in the landscape.

4.3 LOCAL GEOLOGY The local geology of the Spicers Creek catchment was compiled using various literature sources including: Schofield (1998) Meakin and Morgan (1999) together with new lithological data provided by borehole investigations performed by DIPNR in 2001 and geological and geophysical information provided by MIM Exploration Pty Ltd (now known as XStrata Copper) in June 2002 (MIM, 2002). Figure 4.5 is a geological map of the Spicers Creek catchment that was complied by Meakin and

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Figure 4.5 The geology and location of cross-sections within the Spicers Creek catchment (modified from DMR, 2000).

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Morgan (1999) it shows the distribution of various geological units with respect to geological structures throughout the Spicers Creek catchment.

4.3.1 Palaeozoic basement rocks The Spicers Creek catchment is located in the eastern section of the Lachlan Orogen and contains Palaeozoic basement rocks that range in age from Ordovician to Permian. The study area lies on the edge of two structural boundaries known as the Molong High and Hill End Trough. The Molong High contains brittle volcanic sequences and the Hill End Trough contains ductile clastic detritus and both sequences have experienced north-south deformation (Schofield, 1998). The two main Palaeozoic units contained within the Spicers Creek catchment include the Oakdale Formation and the Gleneski Formation with the Cunningham Formation and Cuga Burga Volcanics present to a lesser degree. These units have been contact faulted against each other with the Gleneski Formation absent in the western half of the catchment.

4.3.1.1 Oakdale Formation (Oco) The Oakdale Formation (Oco) is a member of the Cabbone Group, which was deposited during the Late Ordovician period (Table 4.1). This unit is the oldest unit in the study area and outcrops in the western half of the catchment. The term Oakdale Formation was first introduced by Strusz (1960) and was used to describe volcaniclastic breccias and conglomerates, cherty to volcaniclastic, turbiditic sandstone and siltstone with minor clastic limestone beds. The lavas were mafic to intermediate in composition. Throughout the Dubbo area, the proportion of primary volcanic rocks and clastic rocks depends on the proximity from the eruptive centres (Morgan et al, 1999b).

The primary rocks of the Oakdale Formation basement rocks consist of dark latite crystal tuff or lava with quartz, haematic and carbonate veining with pervasive greenish alteration (Ashley, 2001). The clastic sediments of the unit are composed of volcaniclastic breccias and conglomerates that are interbedded with sandstone turbidite packages. These units range from grey to greenish grey to bluey grey and have a basaltic andesitic to latitic source. Volcaniclastic units occur within the

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Spicers Creek catchment and are commonly metamorphosed to greenschist facies with chlorite, sericite and carbonate present (Meakin and Morgan, 1999). This alteration contains epidote, chlorite and sericite assemblages and the unit is highly magnetic (Morgan et al, 1999b)

Table 4.1 Simplified time-space plot of the Spicers Creek catchment geology (modified from Meakin and Morgan, 1999).

Volcanism occurred in a submarine environment where the material was reworked and accumulated on beach or continental slope environments prior to re- deposition in deeper marine environments. The volcanicastic sediments of the Oakdale Formation were deposited in a relatively deep basin environment where the volcanic material was derived from the erosion of distant volcanic centres and

61 Chapter 4: Geological Complexity of Spicers creek catchment formed widespread coalescing submarine fans (Morgan et al, 1999b). De la Cruz (1988) carried out fluid inclusion studies of primary Oakdale Formation units from Bodangora, which is located approximately 20 km south of Spicers Creek catchment near Comobella. Apparent salinities of these units ranged from 4 to 8 wt % NaCl (Downes, 1999). The Oakdale Formation is unconformably overlain in the east by the Silurian Mumbil Shelf strata.

4.3.1.2 Gleneski Formation (Sms) The Gleneski Formation (SmS) forms part of the Mumbil Shelf sediments and was deposited during the Late to Early Silurian period in the Pridoli to Mid Lochkovian epoch (Table 4.1). The Gleneski Formation forms the basement rock geology of the eastern half of the Spicers Creek catchment and is contact faulted against the older Oakdale Formation with the Cuga Burga Volcanics unconformably overlying the Gleneski Formation to the south-east of the catchment. The term Gleneski Formation was first published by Brunker and Rose (1969). The Silurian aged Gleneski Formation is a fine to medium grained felsic volcanic sandstone that is pale green to buff grey in colour with sericite, clay and minor epidote alteration (Morgan et al., 1999c). This unit is generally massive to laminated, containing volcaniclastic to volcanic units that are less magnetic than the Oakdale Formation (Leys and Robson, 1999). The volcanicastic sediments of the Gleneski Formation where deposited by turbidity currents in submarine environments where the material was erupted from subaqueous volcanic vents and formed pyroclastic flows (McPhie et al, 1993; Meakin and Morgan, 1999).

4.3.1.3 Cuga Burga Vocanics (Dgc) The term Cuga Burga Volcanics (Dgc) was first introduced by Strusz (1960). The unit forms a 5 km belt that trends north-west to south-east in the Dubbo region. This unit is a member of Grega Group and forms a minor geological unit within the catchment. It is fault bounded by the Oakdale Formation on the west and Gleneski Formation on the east. A meridional fault slices the unit near Wellington to Gollan in the north within the Spicers Creek catchment (Morgan et al, 1999d). This unit unconformably overlies the Gleneski Formation and is unconformably overlain by Mesozoic strata in the north. The unit reaches a maximum thickness of 1000 m

62 Chapter 4: Geological Complexity of Spicers creek catchment near Wellington and is approximately 400 m thick in the Spicers Creek catchment (Meakin and Morgan, 1999). It is composed of volcanic breccias, feldspathic sandstone, siltstone and tuffs and ranges from basaltic to latitic composition and is grey to greenish grey in colour. The volcanism that produced this unit occurred in sub-aerial to sub-marine environments. The Cuga Burga Volcanics are structurally complex containing fault and shear zones. Shoshonitic in character, these units form rounded tors and weather to form dark reddish brown soils (Morgan et al, 1999d).

4.3.1.4 Cunningham Formation (Dn) The undifferentiated Cunningham Formation (Dn) outcrops in the southern section of the Spicers Creek catchment. It is faulted against the Cuga Burga Volcanics and Gleneski Formation and forms the youngest unit of Hill End Trough sequence (Meakin and Morgan, 1999). The Cunningham Formation was first named by Packham (1968a,b). This unit consists of shale, siltstone and fine-grained sandstone interbedded with calcarenite (Meakin and Morgan, 1999). It was deposited as turbidity flows in the quiet, deep basinal environment of the HET and ranges from massive to well bedded, chocolate brown to greenish grey units that have been folded and faulted.

4.3.2 Mesozoic cover rocks Mesozoic sedimentary cover rocks in the Spicers Creek catchment range in age from Early Permian to Late Jurassic and are a distinct geological sequence of sedimentary units, which consist of interbedded arkosic sandstone, mudstone, siltstones, and shale, with occasional gravel layers and black carbonaceous coaly material dispersed throughout (MIM, 2002). These units range from marine to terrestrial with a thin veneer of marine siltstone to shale units deposited over the Palaeozoic basement rock. These units are apparent in several boreholes located throughout the catchment. This marine sourced unit contains angular clasts, traces of pyrite and carbonate cement. Sediments are also elevated in trace element concentrations such as arsenic and iron (MIM, 2002). This peak in trace element concentrations is experienced in all the drill hole assays performed by MIM, (2002) indicating a source or sink of trace elements is occurring at the bedrock contact.

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The marine unit appears to be allochthonous and may represent a marine incursion that reached further east than previously identified.

Units overlying this marine unit are alluvial through to fluvial with some lacustrine sedimentary deposits. These units range in thickness from 50 m to 190 m. Sedimentary cover rocks are absent or sparse in the eastern portion of the catchment where they have most likely been eroded away exposing the Palaeozoic basement rocks. In the western section of the catchment over 190 m of Mesozoic sedimentary material overlies the Palaeozoic basement rocks. These sediments were deposited in various environments during different geological times and represent the Sydney-Gunnedah Basin and Surat Basin sedimentary sequences.

4.3.2.1 Early Permian undifferentiated (Pe) An Early Permian undifferentiated unit (Pe) directly overlies the basement rocks in Spicers Creek catchment and forms the basal unit of the sedimentary material in the area. It outcrops throughout the centre of the catchment in north-north-westerly trending lobes (Meakin and Morgan, 1999). The lobes are fault controlled and contain westward plunges that result in limited outcrop. The unit has been identified to reach a thickness of over 230 m near Ballimore and contains unsorted, rounded to sub-angular, lithic pebble to boulder conglomerates with clasts set in a poorly-sorted, purplish, clayey lithic-quartz sandstone matrix (Meakin et al., 1999). It was deposited in a high-energy environment such as an alluvial valley environment. The unit was quite abundant but has been eroded in many places leaving palaeosurfaces that have been regenerated (Meakin and Morgan, 1999).

4.3.2.2 Dunedoo Formation (Pd) The Dunedoo Formation (Pd) outcrops on the eastern boundary of Spicers Creek catchment. It unconformably overlies the Early Permian sedimentary rocks and where these rocks are absent, it overlies the Gleneski Formation. This unit represents a sedimentary terrestrial to marine formation that was deposited in the Late Permian and comprises conglomerates, breccia, fine to course sandstone. It

64 Chapter 4: Geological Complexity of Spicers creek catchment is quartzo-feldspathic in composition with a dominantly kaolinite-rich matrix with porcellanite, kaolinite, claystone and thin coal seams (Meakin and Morgan, 1999). It was deposited in varying environments ranging from braided fluvial to meandering streams with lacustrine and isolated swampy conditions (Meakin and Yo, 1999). Source material was derived from the LFB and the porosity and permeability of this unit is limited due to the presence of white kaolinitic clay horizons.

4.3.2.3 Boulderwood Formation (Rb) The Boulderwood Formation (Rb) was deposited in the Early Triassic and overlies the Dunedoo Formation forming a slight angular conformity (Meakin and Morgan, 1999). This unit is present on the western side of the catchment and forms low tree lined escarpments in the study area. It consists of a very course pebbly to conglomeritic, lithic-quartz sandstone with laminated medium quartz sandstone, claystone and siltstone with minor fine silicic volcanic fragments and other metasediments from the basement lithologies (Pogson et al, 1999a). This unit was deposited in a fluvial environment with different lithologies occurring depending on their distance from the river channel.

4.3.2.4 Napperby Formation (Rp) The Napperby Formation (Rp) conformably overlies the Boulderwood Formation and was deposited in the Middle Triassic period. This unit is distributed in the same manner as the Boulderwood Formation throughout the catchment and represents the last unit deposited in the Sydney-Gunnedah Basin sequence (Table 4.1). It forms broad plains and gently undulating hills and reaches a thickness of 150 m to the north-north-east of Ballimore (Pogson, et al, 1999b). The unit contains white, fine to medium grained, moderate to poorly sorted lithic quartz and ferruginous sandstone with a white clayey matrix containing thin interbeds of grey siltstone and minor conglomerate lenses (Meakin and Morgan, 1999). The unit was deposited in a lower energy environment than the Boulderwood Formation and was deposited in a lacustrine deltaic environment (Tadros, 1993). With the deposition of this unit the opening of a second set of north-west trending faults occurred, which created local highs and adjacent depocentres in the landscape

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(Schofield, 1998). Sediments were rhythmically deposited in the area with grainsize variation in this unit due to flooding of the lacustrine environments.

4.3.2.5 Purlawaugh Formation (Ju) The Purlawaugh Formation (Ju) unconformably overlies the Napperby Formation and was deposited in the Mid to Late Jurassic period. It comprises thinly bedded blue-grey to red siltstones and peletal kaolinitic claystone which contains sideritic cherty bands (Meakin and Morgan, 1999). This unit represents the first lithologic unit of the Surat Basin deposited in the area. It was deposited in a floodplain, overbank, backswamp to meandering stream environment (Pogson and Cameron, 1999).

4.3.2.6 Pilliga Sandstone (Jp) The Pilliga Sandstone appears to conformably overlie (McMinn, 1993) the Purlawaugh Formation and was deposited during the Late Jurassic period. Over 195 m of Pilliga Sandstone is preserved at Ballimore with a decrease in sediment thickness eastward across the Spicers Creek catchment. The Pilliga Sandstone generally forms broad flat to gently undulating plateaus characterised by sandy to ferruginous soils (Pogson et al, 1999c). The formation consists of massive, medium to very coarse grained, moderately well sorted quartzose sandstone with generally 80 to 90% quartz content. This unit was deposited by a high-energy braided stream system (Radke et al, 2000).

4.3.2.7 Alluvial (Qa) and Colluvial (Qc) unconsolidated sediments During the Cainozoic, the area experienced erosional events when mainly unconsolidated alluvial and colluvial deposits formed in modern drainage lines and in topographic depressions throughout the catchment. Alluvial deposits have formed along the Spicers Creek and Talbragar River drainage systems. The alluvium follows the north-south trend of the Spicers Creek tributary through the centre of the catchment. This unit generally lack continuity and ranges in thickness from 0 to 15 m. Its composition is dependent on source rocks located within the catchment. Colluvial deposits have formed in topographic depressions and unconformably overly various geological units throughout the catchment. An

66 Chapter 4: Geological Complexity of Spicers creek catchment aeolian component exists within these units, which have had several cycles of reworking due to climatic events over the last 40,000 years (Dawson and Augee, 1997).

Colluvial and alluvial deposits in the Spicers Creek catchment generally range in thickness from 2 to 20 m with an average thickness of 10 m. The material increases in thickness within drainage lines and landscape depressions. The colluvium contains clay to sand to gravel-rich unconsolidated sediments with angular lithic fragments of limestone, sandstone, shale and volcanics (K. Morgan et al., in press). These alluvial and colluvial units are still accumulating and eroding in the catchment.

4.4 STRUCTURAL COMPLEXITY Structural features and lithological boundaries in the Spicers Creek catchment were determined using high resolution geophysical data obtained from MIM Exploration Pty Ltd in July 2002 (MIM, 2002) together with low resolution imagery obtained from Department of Mineral Resources “Exploration NSW” 2000 (DMR, 2002) program. High-resolution data was obtained over exploration areas, EL5623 Yarindury and EL5758 North Comobella. Total Magnetic Image (TMI) data was processed from raw geophysical data and was used to ascertain major lineaments previously unidentified from other geological / geophysical investigations in the catchment (Meakin and Morgan, 1999; Schofield, 1998). Interpretation of this data has lead to the identification of four significant and several minor previously unmapped structures. This high-resolution imagery was used to delineate subtle differences in the magnetic signatures of the bedrock. Combining the geophysical information together with borehole information, the geological complexity has been identified and differentiation of lithologies within the catchment has been achieved.

Four major structural zones exist in the Dubbo region including the Hill End Zone, Cowra Zone, Molong Zone and Capertee Zone. Spicers Creek catchment is located in between the Molong and Hill End Zone (Glenn, 1999) and contains various north-east to south trending lineaments (Figure 4.6). It is located in the Macquarie thrust sheet that is bounded to the east by the easterly dipping

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Nindethana fault and to the west by the easterly-dipping Macquarie fault (Meakin and Morgan, 1999). It comprises easterly dipping thrusts and along these thrusts, the Oakdale Formation is displaced over the younger Silurian and Devonian aged formations. The area has undergone several deformation events, which have influenced the structural nature of the basement rocks by producing north-west and north-east trending deformation fabrics.

Figure 4.6 A subsection of the structural map of the Dubbo 1:250,000 showing structural zones (modified from Glenn (1999) in Meakin and Morgan (1999)).

4.4.1 Structural Interpretation High-resolution magnetics imagery was processed to illustrate the magnetics properties of the underlying bedrock. Anomalies in these properties allowed the subsurface structures to be delineated. Rock forming minerals generally exhibit a low magnetic susceptibility. If a rock contains a small proportion of magnetic minerals then an increase in induced magnetism occurs. Magnetic highs are

68 Chapter 4: Geological Complexity of Spicers creek catchment associated with rocks that contain magnetic minerals such as magnetite and lows are associated with a decrease in magnetic minerals. Groundwater flow through fractures destroys magnetite and therefore produces discontinuities in the magnetic pattern. The use of magnetics aids in the identification of intrusives, dykes, lithological boundaries and delineates zones of faulting within bedrock (Kearey and Brooks, 1991).

4.4.1.1 Identification of previously unmapped structures Previously, several faults had been identified from ground-based magnetic surveys conducted at research Sites 1, 2 and 3 during April 2002. This data contained many artefacts and covered only a small area of the catchment. The use of high resolution airborne geophysical information has further emphasised the magnetic anomalies present throughout the catchment that were previously unidentified. The most significant magnetic anomaly low identified in the catchment is represented as fault 1 on Figure 4.7.

Figure 4.7 First derivative Total Magnetic Intensity (TMI) image that illustrates the different basement lithologies in the Spicers Creek catchment.

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This north-easterly to south-westerly trending structure represents a higher permeability shear zone that is approximately 0.5 to 1 km thick and appears to be regionally extensive. This structural corridor most likely has open oblique structures, which have formed providing access for groundwater to flow through voids contained within the crystalline rocks. The shear zone is further evident from the lateral displacement of the highly magnetic Oakdale Formation unit in Figure 4.8. The Oakdale Formations is prominent in Figure 4.7 due to its high magnetic susceptibility, which is represented by the red colour.

Figure 4.8 Total Magnetic Intensity (TMI) image with an east to west sun angle illumination applied to further emphasise structural features in the Spicers Creek catchment.

Other magnetic lows can be identified from Figure 4.7. Fault 2 is a north-westerly to south-easterly trending fault that forms the extension of a fault that was previously mapped by Meakin and Morgan (1999). The third structural feature identified in Figure 4.7 has a north-westerly to south-easterly trending direction

70 Chapter 4: Geological Complexity of Spicers creek catchment and is represented as fault 3. Finally, the last notable magnetic low is the north- easterly to south-westerly trending fault represented as fault 4.

Figure 4.8 is a Total Magnetic Intensity (TMI) image with an east to west sun angle illumination applied to emphasise small-scale structural features in the catchment. These lineaments in the bedrock appear to be associated with other major structural features such as fault 1. This suggests that in addition to the major faults in the rock mass, the bedrock units are also fractured throughout. Intrusions into the Oakdale Formation bedrock can also be identified in the south-western quadrant of Figure 4.8.

The use of high resolution airborne magnetics data has allowed for the determination of four major structural features that were previously unidentified (Figure 4.7). It has also aided in defining smaller lineaments present, which may influence groundwater flow regimes within the basement rocks of the Spicers Creek catchment (Figure 4.8).

4.4.1.2 Identification of lithological boundaries Airborne radiometric geophysical data was used to determine the distribution of sedimentary cover material and hence the distribution of the intermediate aquifer in the Spicers Creek catchment. Figure 4.9 is a Red-Green-Blue (RGB) colour composite of potassium (red), thorium (green) and uranium (blue) counts for the Spicers Creek catchment.

The radiogenic bright green colour of the Napperby Formation has been highlighted together with the red K-rich alluvial sediments of the Spicers Creek. The K-rich alluvial sediments appear to be derived from granitic intrusions located to the south of the catchment such as the Wuulman granite. The Gleneski Formation appears to be Th-rich and the Oakdale Formation and Cuga Burga Volcanics appear to have a dull red signature. The colluvium is Th-rich, which indicates that the material is derived from the Th-rich sedimentary rocks throughout the catchment. The use of radiometrics has been a valuable tool for delineating the extent of sedimentary cover rocks in the catchment.

71 Chapter 4: Geological Complexity of Spicers creek catchment

Fig 4.9 Red Blue Green (RGB) radiometric colour composite with a high, pass filter applied to delineate of sedimentary cover units in the Spicers Creek catchment.

4.5 GEOLOGICAL MODEL OF SPICERS CREEK CATCHMENT Geological cross sections of the Spicers Creek catchment have been constructed to identify geological, hydrogeological and hydrochemical variations in the catchment using borehole information that reaches depths >310 m bgs. The Ordovician Oakdale Formation forms the basement rock of the western half of the catchment and is contact faulted against the Silurian Gleneski Formation in the east. A thick sedimentary package of marine to terrestrial sedimentary rocks overlies these basement rocks to the west of the catchment. These sequences can be clearly identified in Figure 4.12 to Figure 4.16.

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4.5.1 North to South A north-south transect through the Spicers Creek catchment reveals a distinct geological sequence of shales in the north grading into siltstones towards the south, with minor sandstone and shale lenses throughout (Figure 4.12). These units represent alluvial through to fluvial and lacustrine sedimentary deposits with grain size distribution dependent on the environment of deposition. Sedimentary rocks range from 50 m to 120 m in thickness and are mostly Napperby and Purlawaugh Formation sediments. A thin veneer of marine siltstone and shale units appear to blanket the Palaeozoic basement rocks of the Oakdale Formation. This siltstone to shale unit contains traces of pyrite, angular clasts with carbonate cement and contains high concentrations of trace elements such as arsenic and iron. It appears to be an allochthonous unit.

Figure 4.10 is a downhole assay of drill core COM2, which is located to the south of the Spicer Creek catchment (Figure 4.5). At approximately 70 m a marked increase in iron (>60,000 ppm), arsenic (140 ppm) and copper (100 ppm) concentrations occur. This corresponds with the bedrock contact encountered at 79 m bgs in this drillhole. Figure 4.12 highlights the irregular shape of the Oakdale Formation bedrock contact surface.

Figure 4.10 Drill core assay results for COM2 south of Spicers Creek catchment (MIM, 2002).

The Oakdale Formation has been folded, faulted metamorphosed and intruded by mafic and monzonitic dykes and intrusions. Towards the most southern part of the catchment, the Oakdale Formation has been intruded by an orange-coloured

73 Chapter 4: Geological Complexity of Spicers creek catchment potassium-rich monzonitic unit (MIM, 2002), which forms the Comobella ore deposit. The Oakdale Formation volcanic basement rocks are composed of a mafic to intermediate greenish grey lithology with haematic and chloritic alteration with minor quartz veining (Ashley, 2001). This unit grades into an andesite plagioclase-rich lithology. The unit becomes more mafic and magnetic with depth, with a latite unit forming the basement rock. The presence of chlorite, epidote and sericite alteration appears together with haematic and chloritic-filled fractures. The monzonitic rocks contain fresh or altered ferromagnesian phases, which include clinopyroxenes, hornblende and completely altered biotite. Accessory phases are titanomagnetite, apatite, titanite, and zircon (Ashley, 2001). The shallower monzonitic rocks have intruded and metamorphosed the latitic Oakdale Formation in the Comobella area. Within the Oakdale Formation unit a major fault zone was encountered at approximately 150 m bgs. The presence of this fault gives further evidence to the extension of the fault zone identification from the geophysics, which is approximately 1 km from the proposed extension zone.

4.5.2 West to East A transect running west to east through the centre of Spicers Creek catchment reveals its true geology and gives an overview of the main geologic units present in the study area (Figure 4.13 and Figure 4.14). The complex geology of this catchment is apparent, with a deep basin formed on the Oakdale Formation to the west, with the Oakdale Formation contact faulted against the Gleneski Formation in the east. The Oakdale Formation has been lifted upwards in the west. The Gleneski Formation is absent in the west and has probably been removed by erosion prior to the deposition of the sedimentary Gunnedah and Surat Basin sediments. In the eastern section of the catchment, the marine undifferentiated unit (Pd) or the Dunedoo Formation has been exposed closer to the land surface due to the lack of sedimentary cover (Figure 4.14). The thickness of the sedimentary cover rocks is captured at YAR1 where it reaches over 190 m of sediments. Sedimentary units consist of interbedded arkosic sandstone, mudstone, siltstones, and shale with occasional gravel layers with black carbonaceous coaly material dispersed throughout (MIM, 2002). These sediments contain water-bearing zones due to the presence of porous sandstone layers. At the contact between the Oakdale Formation and the sedimentary units, all trace

74 Chapter 4: Geological Complexity of Spicers creek catchment elements rise in concentration as seen in YAR 1 drill core assay in Figure 4.11, providing further evidence of the marine origin of this siltstone unit that overlies the bedrock. A peak in trace element concentration can be seen at 190 m bgs with a peak in arsenic (40 ppm) and zinc (~80 ppm) concentrations.

Figure 4.11 Drill core assay results for YAR1 within the Spicers Creek catchment (MIM, 2002).

A transect running north-west to south-east (Figure 4.15) and north to south (Figure 4.16) in the southern part of the catchment reveals the geological complexity of the catchment, with the Cuga Burga Volcanics and Cunningham Formation present.

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Figure 4.12 Geological cross-section A to A’ through the Spicers Creek catchment (see Figure 4.17 for location).

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Figure 4.13 Geological cross-section B’ to B through the Spicers Creek catchment (see Figure 4.17 for location).

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Figure 4.14 Geological cross-section C to C’ through the Spicers Creek catchment (see Figure 4.17 for location).

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Figure 4.15 Geological cross-section D to D’ through the Spicers Creek catchment (see Figure 4.17 for location).

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Figure 4.16 Geological cross-section E to E’ through the Spicers Creek catchment (see Figure 4.17 for location).

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Figure 4.17 Location of cross-section in the Spicers Creek catchment (refer to Figure 4.5 for map legend)

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82 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

CHAPTER 5: HYDROGEOLOGICAL ASSESSMENT OF THE SPICERS CREEK CATCHMENT

82 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

5.1 INTRODUCTION Spicers Creek catchment is located within the Ballimore Region and has been previously divided into two main groundwater systems; the deep regional system that is contained within the basement rocks of the Lachlan Fold Belt and the local groundwater system (Schofield, 1998). The local system has been divided into three cells; the deep, intermediate and shallow flow cells (Schofield, 1998). For the purpose of this study, the groundwater system has been divided into three main hydrostratigraphic units, which include:

¾ The deep groundwater system, which is contained within the fractured crystalline basement rocks of Oakdale Formation, Gleneski Formation and Cunningham Formation; ¾ The intermediate groundwater system, which is contained within the fractured sandstone and shales units; ¾ The shallow groundwater system, which is contained within the unconsolidated sediments overlying the fractured bedrock system.

Figure 5.1 shows the schematic model of groundwater circulation systems contained within the Ballimore region. The Spicers Creek catchment is located toward the south-eastern of the Ballimore Region.

The Ballimore region is separated from the Great Artesian Basin (GAB) by a regionally extensive south-east dipping fault, with 100 to 300 m of throw (Schofield and Jankowski, 2003). This structure forms a groundwater divide isolating the GAB aquifers of the Coonamble Basin from the Ballimore region groundwater system. The regional hydrogeology of Ballimore region is discussed extensively by Schofield (1998) and Schofield and Jankowski (2003).

Spicers Creek catchment contains several fractured bedrock aquifers and groundwater flow within these aquifers is mainly governed by the secondary porosity and permeability of these units. Table 5.1 shows the aquifers and aquitards present in the Spicers Creek catchment and how groundwater flows within these hydrogeologic units. Figure 5.2 presents the location of groundwater

83 Chapter 5: Hydrogeological assessment of Spicers Creek catchment piezometer throughout the Spicers Creek catchment that were utilised for this study.

Figure 5.1 Schematic models of the groundwater circulation systems of the Ballimore region (modified from Schofield, 1998).

Table 5.1 Aquifers and aquitards within the Spicers Creek catchment (modified from Schofield, 1998).

Age Geological Formation Lithology Aquifer Aquifer type Porous aquifers to Tertiary to recent alluvium / colluvium clay, sand, gravel Shallow aquitards conglomerate, Late Jurassic Pilliga Sandstone sandstone Shallow Porous aquifer Middle Jurassic Purlawaugh Formation Shale, siltstone Intermediate Fractured aquitard Sandstone, siltstone, Middle Jurassic Napperby Formation shale Intermediate Fractured aquifer Boulderwood Conglomerates, Early Triassic Formation sandstone, claystone Intermediate Fractured aquifer Conglomerates, Early Permian Dunedoo Formation claystone Intermediate Fractured aquifer Early Permian Dubbo Formation sandstone, shale Leaky Aquitard Conglomerates, Early Permian Undifferentiated Unit breccia Intermediate Fractured aquifer Shale, siltstone, Devonian Cunningham Formation sandstone Deep Fractured aquifer Silurian Gleneski Formation Volcanic Deep Fractured aquifer Ordovician Oakdale Formation Volcanic Deep Fractured aquifer

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Figure 5.2 Location of groundwater piezometers within the Spicers Creek catchment.

5.2 FRACTURED AQUIFERS OF THE DEEP SYSTEM The deep groundwater system in the Spicers Creek catchment is contained within the Ordovician to Devonian aged volcanic crystalline fractured rocks of the LFB. These fractured rocks include: the Oakdale Formation in the west of the catchment, the Gleneski Formation in the east and the Cunningham Formation in the far south-eastern part of the Spicers Creek catchment (Chapter 4, Figure 4.4). The general character of these fractured aquifers where identified using down-hole geophysical methods such as gamma and bulk EC, together with several sources of hydrogeological information such as water level data, pump test data and rock samples. These were used to obtain a greater understanding of the little known

85 Chapter 5: Hydrogeological assessment of Spicers Creek catchment hydraulic behaviour of the deep fractured aquifers contained within the Spicers Creek catchment.

5.2.1 The Oakdale Formation Aquifer The Ordovician aged Oakdale Formation aquifer is a confined fractured aquifer and is present in the western half of the catchment. The Oakdale Formation has experienced a large amount of fracturing due to the tectonic activity in the region. Hence, fracture size, connectivity and extent are important factors governing groundwater flow within these units. Potentiometric surfaces in the Oakdale Formation range from 2.2 m bgs (96121/3) to ~10 m bgs (96127/2), over the study period where over 80 m of upward hydraulic pressure is experienced in the aquifer. The deepest piezometer in the Oakdale Formation was drilled to 110 m bgs.

A geological exploration bore was drilled to over 300 m bgs within the Oakdale Formation in the Spicers Creek catchment, where a combination of diamond drill- core and rock chip samples were obtained during drilling. The presence of fracturing and veining found at depth in the Oakdale Formation has been identified in Figure 5.3 to 5.5. Rock chip samples obtained from 190 m to 195 m bgs, appear to have minor fracturing and veining throughout, the unit appears to be consolidated except where faulting occurs (Figure 5.3). Diamond drill core from 235 m bgs shows the presence of faults and veining (Figure 5.4). A sample obtained from 239 m bgs indicates the presence of a fracture zone where groundwater flow is likely to occur in the Oakdale Formation (Figure 5.5).

Figure 5.3 Rock chip samples of the Oakdale Formation aquifer from (a) 190 to 192 m bgs, (b) 192 to 194 m and (c) 194 to 196 m bgs (MIM, 2002).

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Figure 5.4 Core sample of the Oakdale Formation obtained from 235 to 236 m bgs (MIM, 2002).

The presence of large scale faulting as identified in Figure 5.5 is an example of a geological structure that will increase the aquifer yield and transmissivity on a regional scale. Faulting of this unit has led to the variation in thickness and continuity of the Oakdale Formation within the catchment.

Figure 5.5 Core sample of the Oakdale Formation obtained from 239 to 241 m bgs (MIM, 2002).

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Major fracture zones in the Oakdale Formation have hydraulic conductivities several orders of magnitude greater than the un-fractured sections of the aquifer. Fracturing generally decreases with depth within fractured rock aquifers as identified by Davis and Turk (1964) and aquifer porosities were found to range from 1.42 to 2.15%. According to Domenico and Schwartz (1998) a fractured crystalline rock has porosities that range from 0-10% and effective porosities of between 0.0001 to 0.01. These theoretical values are assumed to be representative of the Oakdale Formation aquifer.

A down-hole geophysical investigation of piezometer 96133/2 contained within the Oakdale Formation was completed by the Water Resource Laboratory, UNSW, in May 2002 (Acworth, 2002, pers com). This geophysical log consisted of gamma ray activities and bulk EC (EM39). The gamma ray activity log, is measured in counts per second (cps), where measurement permits the differentiation of grainsize variations such as the presence of clay and sand layers within an aquifer, which correspond to low and higher permeability units in the aquifer system (Repsold, 1989). Gamma ray activity logs can also be used to identify radioactive precipitation in the joints of consolidated rocks, which may indicate the presence of faulting and veining within a crystalline basement rock (Repsold, 1989).

A simplified geological log plotted against the gamma ray activity in cps and bulk EC in mS/m of the aquifer unit indicates that within the top 5 m of the formation, the average gamma activity of 160 cps represents a clay-rich unit. A gamma ray activity peak at 7.5 m is identified as the contact between the overlying weathered siltstone and the fresh siltstone unit. This was confirmed with geological drill-hole data. Other notable changes in the gamma ray activity occur at approximately 13 m where an increase in cps corresponds with the boundary between the volcanic units of the Oakdale Formation and the overlying sedimentary units of the intermediate aquifer system.

Decreases in gamma ray activities are experienced at 24 m, 27 m and 34 m bgs indicating the presence of higher permeability fractures within the Oakdale Formation. These decreases in cps correspond with increases in bulk EC, imply

88 Chapter 5: Hydrogeological assessment of Spicers Creek catchment that the higher permeability fault zones contain slightly higher groundwater salinities.

Figure 5.6 Down-hole geophysical logs of gamma ray (cps) and EM39 (m/Sm) for the Oakdale Formation in piezometer 96133 (adapted Acworth, 2002, pers com).

Bulk EC data indicates a salinity bulge (>200 mS/m) occurs within the top ~10 m of the profile, which corresponds with the weathered clay-rich sediments. Another peak in salinity is experienced at ~16 m bgs at the boundary of the siltstone and the top of the weathered Oakdale Formation.

5.2.2 The Gleneski Formation Aquifer The Silurian aged Gleneski Formation forms the fractured volcanic bedrock aquifer contained within eastern half of the catchment. On a regional scale, this unit is

89 Chapter 5: Hydrogeological assessment of Spicers Creek catchment confined, however in some parts of the catchment the aquifer becomes semi- confined, where the aquifer is located approximately 6 m bgs.

A geophysical log of the Gleneski Formation completed by the Water Resource Laboratory, UNSW, (Acworth, 2002, pers com) illustrates the presence of permeability contrasts within the Gleneski Formation aquifer. The permeability contrasts are interpreted as fracture zones contained within the intact volcanic rock. The contact between the Gleneski Formation aquifer and overlying sandstone units is identified at 15 m, which corresponds with a peak in gamma ray activity of the formation and bulk EC (>350 mS/m), indicating the presence of a saline clay unit in the shallow aquifer, which overlies the Gleneski Formation.

The bulk EC indicates the groundwater and aquifer material of the Gleneski Formation is non-saline from approximately 20 m down to 100 m bgs. The presence of open fractures in the Gleneski Formation can be identified from gamma activity log. These features appear to be located at approximately 28 m, 36 m and 85 m bgs.

A comparison of geophysical logs from the Oakdale Formation (Figure 5.6) and from the Gleneski Formation (Figure 5.7) shows that the Gleneski Formation has the higher salinity groundwaters in the top 20 m of the profile with a decrease in salinity with depth. The Oakdale Formation follows a similar trend where salinity is associated with the top ~20 m of the profile. Both units appear to have open fractures at depth that may be conductive to groundwater flow.

Yields in the Gleneski Formation aquifer are low ranging from 0.05 to 2 L s-1 with higher yields experienced in the top 30 m of the aquifer. This corresponds to the weathered upper section of the volcanic unit. A decrease in yield is experienced with depth where groundwater flow becomes reliant on fracture connectivity and extent (Figure 5.8).

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Figure 5.7 Down-hole geophysical logs of gamma ray (cps) and EM39 (m/Sm) for the Gleneski Formation in piezometer 96121 (adapted from Acworth, 2002, pers com).

Figure 5.8 Yield versus depth in the Gleneski Formation.

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5.2.3 The Cunningham Formation Aquifer The Cunningham Formation is a fractured siltstone aquifer that is part of the deep groundwater system in the south of the catchment. This aquifer has a moderate yield (5 L sec-1) and is under artesian pressure with potentiometric heads approximately 3 m above the ground surface at the time of drilling in April 2001. This unit will be discussed further with regards to water level dynamics and its interaction with the shallow aquifer.

5.3 GROUNDWATER FLOW WITHIN THE DEEP AQUIFERS 5.3.1 Regional groundwater flow Groundwater flow is assumed to follow the continuum approach for fracture flow, which assumes that the fractured mass is hydraulically equivalent to a porous media (Domenico and Schwartz, 1998). Groundwater flow in the Oakdale Formation aquifer is generally governed by the presence of secondary porosity in the form of fractures and lineaments in the bedrock that were induced by tectonic activity in the region. Fracture density, aperture and connectivity of the unit will determine the amount of groundwater flow within the aquifer system (Schofield and Jankowski, 2000). The fractured basement rocks of Spicers Creek catchment are regarded as intact rock that is separated by discontinuities, similar to the unit described by Van Golf-Racht (1982). Groundwater flow in these aquifers is mostly governed by secondary porosity in the form of fracture networks and shear zones. Major fracture zones in the Oakdale Formation and the Gleneski Formation may have hydraulic conductivities that are several orders of magnitude greater than the un-fractured sections of the aquifer.

Standing water levels were converted to reduced levels, according to the Australian Height Datum (AHD), which is elevation above sea level and potentiometric maps of the Oakdale Formation and Gleneski Formation were constructed as seen in Figure 5.9. Groundwater flow within the deep groundwater system follows a general westerly direction, where the contact fault separating the Oakdale Formation and Gleneski Formation disrupt groundwater flow in the catchment. Potentiometric pressure on the Oakdale Formation side of the fault

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(west) has ~10 m head difference to the Gleneski Formation aquifer on the eastern side of the fault.

Figure 5.9 Groundwater flow direction in the deep aquifers in the Spicers Creek catchment.

Recharge to the Oakdale Formation aquifer is thought to occur where the fractured rock units outcrop to the south of the catchment between Wellington and Comobella. Recharge to the Gleneski Formation aquifer occurs within exposed fractured rock outcrops to the east of the catchment. A two day lag period between groundwater level responses to rainfall was estimated by Smithson (2002) from piezometer 96128/3, located within the Gleneski Formation in the north-east of the catchment. The Gleneski Formation is located close to the ground surface in this part of the catchment, where geological structures may provide fast infiltration pathways for recharge to the Gleneski Formation. Figure 5.10 indicates potentiometric surfaces within the deeper section of the Gleneski Formation

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(96128/3) and shallow aquifer (96128/2) are hydraulically connected, responding in a similar manner to recharge events. This data also indicates that water level changes within the Gleneski Formation aquifer are not associated with changes in barometric pressure.

Figure 5.10 Hydrographs for the shallow (96128/2) and Gleneski Formation (96128/3) from January 2002 to May 2002 in the Spicers Creek catchment (Smithson, 2002).

Recharge to the deep groundwater system occurs when confining layers are absent and diffuse rainfall input can percolate into outcropping basement rocks. Faults extend south and east into the topographically high areas around Wellington and Lake Burrendong and are areas of recharge for the deeper groundwater system (McElroy, 2000). Groundwater replenishment from recharge usually varies seasonally and from year to year in the Spicers Creek catchment, depending on rainfall patterns. Recharge from overlying aquifers in areas where geological structures increase the communication between aquifers also appear to be a source of recharge for the deep groundwaters.

The deep groundwater system in the Spicers Creek catchment is generally confined but where the confining layers are absent or where the unit has been faulted, discharge may occur. Discharge of deeper groundwaters in the Spicers

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Creek catchment appears to occur through geological lineaments and permeable fault zones. Groundwater discharge is also occurring towards surface water systems such as Spicers Creek. Surface water systems in the Spicers Creek catchment are groundwater fed and possess a hydrochemistry reminiscent of the deeper groundwaters with elevated concentrations of trace elements found in the deep system.

In 1998, DLWC completed a regional static water level study of 255 private water bores that are screened within fractured rock aquifers located in the Central West region of NSW. These water level results were compared with water levels measured in 1988 and it was found that most water levels had risen since the time of bore construction (Salas and Smithson, 2002). A relationship was observed between the rainfall residual mass curve for climatic data in the area and the difference between the mean water level for 1988 and the mean measured water level for 1998. The results of this study showed that there has been a general trend in rising water levels over the past 11 years in the deep fractured system, even though the annual rainfall patterns have not changed from the long term average (Salas and Smithson, 2002). It appears that the deeper aquifer system is in a state of dynamic disequilibrium as described by Theis, (1938) and Fetter, (1994). It appear from current hydrograph data that water levels

5.3.2 Structural controls on groundwater flow Static standing water level data of groundwaters in the deeper fractured bedrock aquifers indicate that groundwaters are experiencing an upward hydraulic pressure where piezometers intersect geological structures or fault zones. Hydrographs were constructed from standing water level data obtained from June 2001 to February 2003 for nested piezometers. Hydrographs of nested piezometers located at different sites in the Oakdale Formation aquifer, Gleneski Formation and Cunningham Formation, indicate the hydrodynamic variability experienced within the fractured bedrock aquifers of Spicers Creek catchment.

Water level dynamics in the Oakdale Formation aquifer are represented by three nested piezometer locations (bore 96121/1-2-3, 96133/1-2 and 96127/1-2) (see Figure 5.2 for location). Nested piezometers 96121/1-2-3 were drilled to various

95 Chapter 5: Hydrogeological assessment of Spicers Creek catchment depths penetrating all three aquifers present at the site. The deep piezometer was drilled to a depth of 110 m bgs and screened within the Oakdale Formation aquifer. Piezometer 96121/2 was drilled to 50 m bgs, penetrating the intermediate aquifer and 96121/1 was drilled to 20 m bgs and screened within the shallow aquifer. This bore is located at the fault intersection of fault 1 and a previously identified fault represented in Figure 4.7. This hydrograph provides a good indication of how the groundwater flow within the deep aquifer is influenced by the presence of geological structures. Figure 5.11(a) indicates that the potentiometric surface of the Oakdale Formation aquifer has a higher hydraulic head than the intermediate aquifer groundwaters. The hydraulic head difference between the two aquifers is approximately 6 m, indicating the potential pressure for the upward migration of deeper groundwaters where the aquifer permeability is compromised such as at a fault location. Due to the potential upward gradient, mixing between groundwaters can occur within higher permeability fault zones. This hydrograph also illustrates the dynamic nature of the fractured system with over 10 m of head fluctuation occurring over the study period. A general increase in water level is experienced in the Oakdale Formation with over 2 m of potentiometric surface increase experienced in the deeper fractured aquifer (96121/3) over the study period.

Figure 5.11 Hydrographs of the Oakdale Formation aquifer (a) nested piezometers 96121/1-2-3 and (b) nested piezometers 96133/1-2 and nested piezometers 96127/1- 2, in the Spicers Creek catchment.

Figure 5.11(b) represents the potentiometric surfaces of the Oakdale Formation in a shallower section of the aquifer. Piezometer 96133/2 is screened within the Oakdale Formation from 30 to 34 m bgs. This hydrograph indicates that the deep

96 Chapter 5: Hydrogeological assessment of Spicers Creek catchment and shallow groundwater systems are hydraulically connected at this point with a slight upward hydraulic gradient. A decrease of 2.5 m in the potentiometric surfaces in the Oakdale Formation has occurred at the site over the study period. Figure 5.11(b) also shows the potentiometric surfaces of bore 96127/2, which is located in the Oakdale Formation at a depth of 51 m bgs. This piezometer is not located near a geological structure in the catchment. It took approximately 8 months for the potentiometric surface to recover after drilling indicating the low permeability nature of the Oakdale Formation aquifer, where geological faulting does not influence groundwater flow.

Figure 5.12 represents the hydrographs of piezometers 96128/1-2-3 and 96121/1- 2-3-4, where the deepest piezometers are screened within the Gleneski Formation aquifer. Piezometer 96128/1 was drilled to a depth of 3 m bgs and is screened within the shallow aquifer. Piezometer 96128/2 penetrates the shallow aquifer also to a depth of 15 m bgs and piezometer 96128/3 is screened within the weathered upper section of the Gleneski Formation at a depth of 31 m bgs. This hydrograph indicates that an upward hydraulic gradient is experienced in the lower part of the shallow aquifer at 15 m bgs (Figure 5.12(a)). The shallow aquifer and the Gleneski Formation aquifer appear to be hydraulically connected, and a general decrease in water levels in all aquifers was experienced over the study period.

Figure 5.12 Hydrographs of the Gleneski Formation (a) nested piezometers 96128/1- 2-3 and (b) nested piezometers 96122/1-2-3-4, in the Spicers Creek catchment.

Figure 5.12(b) represents the potentiometric surfaces of piezometers 96122 located within a fault zone. Piezometer 96122/1 is screened within the shallow

97 Chapter 5: Hydrogeological assessment of Spicers Creek catchment aquifer at 4 m bgs, piezometer 96122/2 is screened within the top of the intermediate aquifer at 11 m bgs, piezometer 96122/3 is screened within the weathered section of the Gleneski Formation at 49 m bgs and piezometer 96122/4 is screened within the unweathered Gleneski Formation aquifer at 100 m bgs. Water levels are close to the ground surface within this structural zone where the shallow, intermediate and weathered Gleneski Formation units are hydraulically connected and at the land surface. The hydraulic head in piezometer 96122/4 took over 5 months to recover after piezometer installation, indicating the low permeability nature of the Gleneski Formation at depth. A drop in potentiometric surface occurred in June 2002, due to purging during hydrochemical sampling in May 2002, with water levels recovering by October 2002. It appears that the top 50 m of the Gleneski Formation is hydraulically connected with the overlying units implying that deeper groundwaters maybe discharging at the land surface due to the presence of a fault zone.

Figure 5.13 represents the potentiometric surfaces of the Cunningham Formation, which is part of the deep groundwater system located in the southern part of the catchment. These nested piezometers are located within a geological structural zone. The deepest piezometer 96129/3 is screened within the Cunningham Formation at 31 m bgs. Piezometers 96129/1 and 96129/2 are screened within the shallow aquifer at 5 m, and 13 m bgs, respectively. A positive upward hydraulic gradient of over 2.5 m exists at the site where deep groundwaters may be mixing with overlying shallow aquifers within the fault zone. This bore is under artesian pressure where the potentiometric surface was approximately 3 m above the ground surface when the bore was drilled in April 2001 and is now ~0.5 m above the ground surface.

Hydrographs of the various fractured rock aquifers present in the Spicers Creek catchment indicate the potential for mixing between groundwaters from the different hydrogeological units. They also show the upwards gradient of deeper potentiometric surfaces and potential mixing paths of groundwaters from different aquifers where geological structures disrupt the crystalline aquifers.

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Figure 5.13 Hydrographs of the Cunningham Formation aquifer in nested piezometers 96129/1-2-3 in the Spicers Creek catchment.

5.4 INTERMEDIATE GROUNDWATER SYSTEM The intermediate groundwater system contained within the Spicers Creek catchment is separated from the underlying deeper aquifers by a regionally extensive aquiclude unit and the system has been divided into the deep, intermediate and shallow flow cells (Schofield, 1998). These flow cell are separated by regionally extensive aquitards and aquicludes. Mixing between the cells occurs where aquiclude units thin or are disrupted due to the presence of geological faulting or the movement of geological units.

5.4.1 The Deep cell The regional groundwater system is isolated from the deep cell of the local system by a regionally extensive aquiclude (Schofield and Jankowski, 2000). This unit is an argillaceous aquiclude, which has been smeared along fault planes and behaves as a self-sealing aquiclude (Schofield and Jankowski, 2003). In the Spicers Creek catchment, the deep cell is contained within the Dunedoo Formation.

The Dunedoo Formation is a fractured aquifer that consists of kaolinite bounded quartz lithic sandstone with inter-bedded clay and coal units. Discontinuous coal beds have well-developed porosity and form isolated reservoirs for upward migrating Na-HCO3-rich groundwaters. Schofield (1998) estimated that Dunedoo

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Formation has an approximate porosity of 20% in the form of secondary fracture porosity.

5.4.2 The Intermediate cell The intermediate cell is contained within the fractured aquitard units of the Napperby Formation and Purlawaugh Formation in the Spicers Creek catchment. The Napperby Formation is an argillaceous aquitard and contains mostly fracture porosity with an increase in primary porosity at the top of the unit, and a total estimated porosity of approximately 20% (Schofield, 1998). The lower section of the Purlawaugh Formation forms a fractured aquitard and the top of this unit forms an aquiclude separating the intermediate from the shallow cell. The Purlawaugh Formation has a sandy lower section and a shaly upper section, where a reduction in permeability in the sandy section occurs due to weathering and its lithic nature (Schofield and Jankowski, 2003). The Purlawaugh Formation contains mostly solution porosity and forms a self sealing unit, which ensures that CO2(g) is trapped within the intermediate cell and does not escape (Schofield, 1998). The intermediate cell forms a mixing zone where the Napperby Formation thins and the pressurised groundwaters from the deep cell are forced into the intermediate cell and the downward percolation of groundwaters from the shallow cell occurs (Schofield, 1998). Leakage from the deep and shallow cell into the intermediate cell produces mixed groundwater chemistries.

5.4.3 The Shallow cell (Pilliga Sandstone) The shallow cell consists of the Pilliga Sandstone, pre-Miocene and post-Miocene alluvium, Miocene volcanics and colluvial deposits throughout the Ballimore region. The alluvial / colluvial deposits will be discussed in section 5.5 in further detail. The Pilliga Sandstone is mostly absent in the Spicers Creek catchment except for a thin veneer in the north-western corner of the catchment.

The Pilliga Sandstone aquifer is a very good yielding and good quality confined aquifer that is permeable throughout, with an intrinsic permeability that ranges from 100 to 1000 m day-1 (Radke et al, 2000). The unit has a good porosity with an

100 Chapter 5: Hydrogeological assessment of Spicers Creek catchment average of 25% and a transmissivity that ranges from ten to several thousand m2 day-1. The hydraulic conductivity ranges from 0.1 to 20 m day-1.

5.4.4 Aquifer properties of the intermediate system This system has a combination of structurally and stratigraphic through-flow aquifers (Schofield, 1998). Sedimentary aquifers and aquitards of the intermediate system have been deformed due to structural events in the region. Groundwater bearing zones are contained within the argillaceous sandstone and siltstone units and are separated by arenaceous aquitard units (Schofield and Jankowski, 2003).

Insitu fracturing of the units and the presence of secondary precipitates, such as carbonate cements and iron oxides forming in fractures and pore spaces, reduces the secondary fracture porosity of the units. Schofield (1998) noted from visual porosity estimations that a rapid loss in primary porosity occurs with depth and an increase in secondary fracture porosity is experienced.

Groundwater head recovery tests where performed on three bores in the Ballimore region by Schofield (1998). He derived an average hydraulic conductivity (K) of the various fracture networks in the intermediate groundwater system that range from 1.1 to 1.8 m day-1. The aquifers contain a low storativity due to the fractured nature of the aquifers (Schofield, 1998). A plot of yield versus depth is shown in Figure 5.14, where yields range from 0.07 to 0.909 L s-1 with increases experienced with depth.

Figure 5.14 The relationship between yield versus depth for the intermediate aquifers contained within the Spicers Creek catchment (DLWC, 2003).

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5.4.5 Groundwater flow direction in the intermediate system Groundwater flow direction in the intermediate aquifers follows a general north- westerly direction as seen in Figure 5.15. Groundwater follows the direction of the topography on the eastern side of the catchment because it is spars in this part of the catchment. A recharge mound is evident in the south-western corner of the catchment due to the presence of a topographic high. An average horizontal hydraulic gradient of 0.006 m was calculated for the intermediate aquifer across the catchment.

Recharge to the intermediate system in the catchment occurs where the Mesozoic aged sediments of the intermediate aquifer outcrop. These units outcrop in the south-western part of the catchment. Recharge also occurs where native vegetation has been removed leaving bare ground for increased infiltration into the intermediate groundwater system.

Discharge from the intermediate groundwater system occurs within geological structures and towards the Talbragar River in the north of the catchment. The presence of a trough in the north-western corner of the catchment presents the possibility that intermediate groundwaters may be under increased pressure near Saxa, which is where research sites (Sites 1 and 2) are located. This intermediate groundwater system is confined to semi-confined, leakage between aquifers and aquitards occurring where faulting disrupts the aquitards, and communication between the units is enhanced. The groundwaters contained in the deep cell of the intermediate aquifer system have a low modern carbon activity (<2% pmC) indicating that these waters are older than 35,000 years (Schofield, 1998).

Figure 5.16 represents a hydrograph of nested piezometers located in the intermediate aquifers. Nested piezometer 96132/1-2 is located at the top of the catchment and nested piezometer 96130/1-2 is located at the centre of the catchment. Piezometer 96132/1 is located in the Napperby Formation at 61 m bgs and 96132/2 is screened within the shallow aquifer at 11 m bgs.

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Figure 5.15 Groundwater flow direction for the intermediate aquifers of the Spicers Creek catchment.

Figure 5.16 Hydrographs of the intermediate groundwater system in nested piezometers 96130/1-2 and 96132/1-2 in the Spicers Creek catchment.

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Piezometer 96130/2 is screened within the Napperby Formation at 40.5 m bgs and 96130/1 is screened within the shallow aquifer at 14.5 m bgs. This hydrograph shows the low permeability nature of the intermediate system where potentiometric surfaces took 6 months to recover after drilling. Once the potentiometric surfaces stabilised, depths ranged from 5 to 8 m bgs for the intermediate groundwater system. Recharge to the intermediate system appears to be occurring from downward infiltration of waters.

5.5 SHALLOW GROUNDWATER SYSTEM The shallow groundwater system in the Spicers Creek catchment consists of Tertiary to recent aged, clay-sand-gravel-rich lithologies. These clay-rich units contain perched water tables that transmit groundwater through permeable sand to gravel-rich lenses that are inter-dispersed throughout. These units are unconfined and act as semi-confined aquifers where an increase in clay composition occurs. The shallow aquifer forms discontinuous groundwater systems throughout the catchment and water table depth is governed by the amplitude of topographic undulations. Recharge and discharge to this shallow system appears to be disrupted in regards to normal groundwater flow within local groundwater system as described by Toth (1963, 1999), primarily due to the presence of geological structures in the catchment. These structures are acting as conduits for deeper groundwater flow to discharge into the shallow groundwater system forming groundwater seepage zones.

5.5.1 Shallow aquifer properties Due to the heterogenous nature of these shallow units, various lithologies possess different hydraulic properties. Yields are low from ranging from 0.15 to 1.2 L s-1 with an average of 0.28 L s-1. Theoretical values for hydraulic conductivity (K) within clay sediments range from 8.6 × 10-7 m day-1 to 8.6 × 10-4 m day-1 (Fetter, 1994). The overall K value for the shallow groundwater system would be low but due to the presence of high conductivity lenses of well sorted sands that have theoretical K values of between 0.86 m day-1 to 8.64 m day-1. The overall K of the shallow aquifers in the Spicers Creek catchment is much greater than expected. Mahamed (1999b) performed slug tests on the shallow aquifer near Binginbar in

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Snake Gully catchment and calculated the hydraulic conductivity of the shallow aquifer to range from 0.002 to 0.3 m day-1. When considering an average aquifer thickness of approximately 16 m throughout the catchment, transmissivities range from 0.03 to 5 m2 day-1. These transmissivity results are consistent with those calculated by Anderson (1992), which ranged from 0.1 to 0.2 m2 day-1 for the area.

5.5.2 Groundwater flow in the shallow aquifer Groundwater flow direction in the shallow groundwater system is influenced by the local topography, the thickness of the sandy-gravel-rich units and aquifer continuity. A general westerly to north-westerly groundwater flow direction can be identified from a piezometric map of the shallow groundwaters presented in Figure 5.17. Flow paths generally flow from topographic highs to lows within the catchment, except where the formation of seepage zones may be influencing the natural flow path.

Recharge is occurring at topographic highs to the south and the east of the catchment. Diffuse recharge is also occurring where bare tilled soils are exposed across the catchment. These disturbed soils have high infiltration capacities and readily accept rainfall recharge. Recharge to the shallow system occurs mostly in the winter months when precipitation exceeds evapotranspiration. An above average recharge pulse was experienced during February 2002 where ~200 mm of rainfall was experienced for the month. Piston-flow recharge mechanisms would mostly likely dominate recharge processes during storm events in the area. Once the infiltration capacity of the soil was exceeded, overland flow across the landscape would be initiated and the excess flow across the landscape or groundwater through flow would discharge in the surface water systems.

Discharge occurs at breaks in slope, where bedrock highs occur, where sediment permeability contrasts occur and where regional geological structures exist. Discharge zones or seepage zones appear to be forming within geological structures throughout the catchment as observed within research Sites 1, 2 and 3. The streams and creeks in Spicers Creek catchment are effluent or gaining

105 Chapter 5: Hydrogeological assessment of Spicers Creek catchment streams that receive groundwater from base flow, which is influencing stream water chemistry.

Figure 5.17 Groundwater flow direction for the shallow aquifers in the Spicers Creek catchment.

Groundwater flow in the Snake Gully catchment follows a westerly direction driven by topography, possessing an average hydraulic gradient of 0.016 m. Groundwater flow direction in the Racecourse Gully catchment follows a northerly direction along the Spicers Creek drainage line and has a hydraulic gradient of approximately 0.004 m.

Experimental Site 1 is located at the end of Snake Gully catchment (Figure 2.1) and a transect of nested piezometers dissects a seepage zone. Piezometers located at S3 are at the crest of the slope, S2 at mid slope and S1 are located at the lower slope past the seepage zone. Groundwater flow movement at Site 1 is

106 Chapter 5: Hydrogeological assessment of Spicers Creek catchment illustrated in Figure 5.18 where groundwater flow direction follows the general topography from nested piezometers S3 to S2 where water levels intersect the land surface forming a groundwater seepage zone. A positive vertical hydraulic gradient is experienced at nested piezometers S2 and S1 and a hydraulic gradient of 0.019 m was calculated across the transect.

Figure 5.18 Groundwater flow movement at Site 1 in the Spicers Creek catchment.

Experimental Site 2 is located within the Snake Gully catchment (Figure 2.1) and contains discontinuous seepage zones where the water table intersects the land surface. Groundwater flow movement at Site 2 follows the topography from piezometer S8 to S7, at piezometers S7, S6 and S5 groundwater seepage zones are forming (Figure 5.19). The site has a hydraulic gradient of 0.027 and groundwater flow direction is governed by the presence of permeability contrasts and geological structures at the site.

Experimental Site 3 is located at the top of Snake Gully (Figure 2.1) and groundwater flow direction follows a westerly direction. Site 3 has a lower hydraulic gradient than the other two sites of 0.006 m. These experimental sites will be discussed with regards to soil properties and hydrochemistry in Chapter 6.

107 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

Figure 5.19 Groundwater flow movement at Site 2 in the Spicers Creek catchment.

5.5.3 Water level dynamics in the shallow aquifer Standing water levels were obtained from the piezometers located within the shallow groundwater system. At each piezometer location, there are three nested piezometers located at between 4 to 6 m, which is screened within the upper section of the aquifer, then at 8 to 10m in depth, which is the middle section of the aquifer, and then at 10 to 12 m, which is the lower section of the aquifer. The rate of water level change and the aquifer response to changes with respect to rainfall was assessed.

Descriptive statistics of water levels within the shallow aquifers shows the amount of variation in water levels in the shallow aquifer over the study period (Table 5.2). The average water level depths in the shallow aquifers range from 0.82 to 1.89 m bgs. The minimum depth to the water table was experienced in June 2001 where water levels were greater than 1 m above the ground surface. The water table decreased throughout the study period indicating that the shallow groundwater system is responding to drought conditions experienced. Water levels dropped throughout the study period in response to the lack of recharge to the shallow groundwater system. Even though the area has been subjected to drought conditions, mean water levels are still at 1.89 m bgs. This may imply that areas in

108 Chapter 5: Hydrogeological assessment of Spicers Creek catchment the shallow aquifer in Spicers Creek catchment may be influenced by other hydrogeologic parameters and not just climatic conditions.

Table 5.2 Descriptive statistics of the water levels within the shallow aquifers of the Spicers Creek catchment.

N Minimum Maximum Mean range (m) Std. Deviation Jun-01 13 -1.05 2.19 0.82 3.24 0.91 Nov-01 21 0.01 5.61 1.54 5.6 1.54 Apr-02 26 -0.82 5.12 1.06 5.94 1.40 Jun-02 40 -0.76 5.26 1.16 6.02 1.26 Aug-02 31 -0.31 5.37 1.06 5.68 1.35 Sep-02 31 -0.29 5.4 1.11 5.69 1.36 Feb-03 36 -0.08 6.01 1.89 6.09 1.29

5.5.4 Water level response in the seepage zones Water levels from all three research sites were compared to rainfall conditions in the catchment as identification in Figure 5.20a. The residual mass curve was calculated by Smithson, (2002) and indicated that for periods from 1934 to 1948, 1965 to 1967 and 1974 to 1986 annual rainfall tended to be less than the long term average. From 1949 to 1964, 1968 to 1973 and 1987 to 2000, annual rainfall was greater than the long term average for the catchment at Binginbar Farm.

Site 1 has a transect of nested piezometers that dissects a seepage zone. Piezometers S3a, S3b and S4 are located at the top of the transect where water levels are deeper and the range in water levels is small, indicating a static system. Water levels have a subtle response to rainfall recharge. Water levels in piezometers S3a and S3b mimic each other, indicating they are hydraulically connected (Figure 5.20b). At the top of the transect at Site 1, piezometers seem to have subtle responses to rainfall patterns with a net decrease in water levels experienced over the study period due to the decrease in rainfall for the area.

Figure 5.20(c) the hydrograph of nested piezometers S2a-b-c which are located mid way through the transect at the top of the seepage zone at Site 1. A positive hydraulic gradient exists in the aquifer at this point, where the deeper sections of the aquifer contain a higher hydraulic pressure. Than the shallower sections, ~1 m of upwards hydraulic gradient exists. Water levels at S2 are influenced by rainfall

109 Chapter 5: Hydrogeological assessment of Spicers Creek catchment recharge where a rise in water levels was experienced in February 2002 and all parts of the aquifer responded to this recharge event, where water levels declined over the study period.

Figure 5.20 (a) Rainfall data for Binginbar Farm from June 2001 to February 2003 (b) hydrographs of nested piezometers S4 and S3 located at the top of the transect (c) nested piezometers S2 located at the top of the seepage zone and (d) nested piezometers S1 located within the seepage zone in the shallow groundwater system, Spicers Creek catchment.

Figure 5.20d is a hydrograph depicting water level changes for nested piezometer S1, which is located at the bottom of the seepage zone at Site 1. This hydrograph demonstrates the dynamic nature of water levels within the seepage zone. Water levels in piezometer S1a are influenced by rainfall recharge. Piezometers S1b and S1c have a similar response with slight increase in May 2002 due to recharge, followed by a subsequent decrease in water levels due to prevailing drought conditions. These water levels are relatively constant throughout the study period indicating the presence of a positive vertical hydraulic gradient, elevating water levels, even during drought conditions.

110 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

The shallow aquifer at Site 1 shows a response to rainfall events but also contains a component of upward vertical leakage of deeper groundwaters influencing water levels. These results indicate that the seepage zone at Site 1 is dependent on rainfall recharge and the upward flux of bedrock groundwaters leading to elevated water tables and hence waterlogging within the seepage zone.

Figure 5.21(a) presents the hydrograph of piezometers S8 and S7 that are located at Site 2. Piezometer S8 is located at the top of the transect and S7 within a seepage zone midway down the transect. This system is very dynamic and responds according to rainfall events. The most notable event is after the rainfall event in February 2002, where water levels rose nearly 2 metres in piezometer S8 and 1 metre in piezometers S7a and S7b. Water levels in the seepage zones are at or above the ground surface causing waterlogging problems. Piezometers S8 and S7b are screened within the weathered permeable sandstone unit and responds well to recharge. This site took approximately 10 months for water levels to equilibrate to the recharge pulse experienced in February 2002.

Figure 5.21 Hydrographs of the shallow aquifer at Site 2 (a) piezometers S8 and S7 located at the top of the transect (b) piezometers S5 and S6 located within seepage zones and p56 located at the bottom of the seepage zone, Spicers Creek catchment.

Figure 5.21(b) shows the hydrographs of p56, S5 and S6 that are located further down the transect, at the bottom of the seepage zone at Site 2. Piezometers S6 and S5 are located within the seepage zones but are screened within a very heavy clay unit. Piezometer S6 is less dynamic than other piezometers located at Site 2

111 Chapter 5: Hydrogeological assessment of Spicers Creek catchment implying it is not as dependent on rainfall events. All water levels at Site 2 responded to the rainfall event experienced in February 2002. Piezometer S5 was the most responsive to this event. Water levels are below the ground surface for all bores except S5 and p56, which are located at the bottom of the transect. A decrease of 2 m of head has been observed in piezometers S6a and S6b due to drought conditions.

Water levels have not dropped substantially at this site during drought conditions. Management practises to combat waterlogging and seepage zone formation have been implemented at this site, with the plantation of an agroforestry plot in June 2002. Water levels have remained constant even though evapotranspiration rates have increased in the area. Water levels are at the land surface at this site, where the planting of native vegetation has had little affect on water levels. The shallow aquifer at this site contains a positive pressure, with a higher hydraulic head experienced in the deeper bores, indicating the upward vertical flux of deeper groundwaters could be leading to waterlogging problems (Morgan and Jankowski, 2003).

At the top of the Snake Creek catchment at Site 3, hydrographs of piezometers S12 and nested piezometers S13 are shown in Figure 5.22(a). Piezometer S12 is located at the top of the transect and has the deepest water levels throughout the site with a decrease of 0.9 m over the study period. Piezometer S13(a) has a lower hydraulic pressure than experienced in piezometers S13(b), S13(c) and S13(d), indicating that a positive hydraulic gradient exists at this point in the aquifer. A loss of 0.5 m in water level in all bores was experienced, indicating water level response is dependent on climatic conditions. At the top of Site 3, all water levels respond the same way due to rainfall recharge.

Figure 5.22(b) is a hydrograph of nested piezometers S14 and piezometer p63, which are located at the bottom of Site 3. This hydrograph indicates that the shallow aquifer responds to climatic conditions with a decrease of approximately 1 m of head experienced due to drought conditions. Figure 5.22(c) is hydrograph of piezometers S15(a), S15(b), p62 and p65, which are located at the bottom of Site

112 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

3 and are drilled close to the Snake Creek. A general decrease of approximately 1 m of head is experienced over the study period.

Figure 5.22 Hydrographs of the shallow aquifer at Site 3 (a) piezometers S12 and S13 located at the top of the transect (b) piezometers S14 located at the bottom of the seepage zone and (c) piezometers S15, p62 and p65 located near the creek within the seepage zone, Spicers Creek catchment.

5.5.5 Water budget A water budget has been compiled for the shallow groundwater system in the Spicers Creek catchment. Hydrologic inputs to this system include: precipitation, surface water inflows and groundwater input from the deep groundwater system. The hydrologic outputs from this system include: evaporation, transpiration, surface water outflows and groundwater discharge. It is important to estimate the amount of water that is involved in this cycle to understand the system more effectively.

113 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

Estimated inputs include approximately 500 mm yr-1 of rainfall and rainfall recharge estimates were based on 10% of rainfall infiltration to the groundwater system. Most rainfall recharge occurs during the winter months where lower evapotranspiration rates prevail. Surplus water is supplied to the surface water system during storm events where above average rainfall events such as experienced in February 2002 occur. This is because when the soil zone has reached field capacity, interflow and groundwater recharge can commence (Domenico and Schwartz, 1998). Approximately 50 mm yr-1 rainfall recharge to the shallow groundwater system may occur.

Total recharge to the catchment considering 50 mm yr-1 of rainfall recharge to the 500 km2 catchment, produces 2.5 × 1010 L of water yr-1, which is equal to 25,000 ML yr-1 to the catchment from rainfall recharge.

To estimate the groundwater storage within the catchment an average saturated thickness of the aquifers in the catchment was estimated at 95 m with 5% porosity. The total volume of material is equal to 4.75 × 1010 m3 with a saturated volume of 2.3 × 109 m3. Hence, 2.375 × 1012 L of groundwater is in storage, which is equal to 2, 375, 000 ML. When considering that the average surface water discharge from Spicers Creek at Saxa bridge is equal to ~13,00 ML yr-1, then the groundwater system may increase by 12,000,000 ML yr-1 (this result does not take evapotranspiration of discharge groundwaters into consideration).

It appears from this simple water balance of the shallow groundwater system that there is a surplus of groundwater. The following chapters will show evidence to further indicate that the shallow system is receiving flux from the deeper aquifer systems in the catchment.

5.6 CONCEPTUAL HYDROGEOLOGICAL MODEL A conceptual hydrogeological model was developed for the Spicers Creek catchment, based on geological and hydrogeological data presented (Figure 5.23). Deep groundwater in the Oakdale Formation and Gleneski Formation aquifers follow a westerly direction where the permeable geological structures influence

114 Chapter 5: Hydrogeological assessment of Spicers Creek catchment groundwater flow. Fault intersection planes provide permeable pathways for deeper groundwaters that are under pressure to discharge up-dip of the fault zones towards the land surface. Groundwater flow within the intermediate system follows a westerly direction also. Groundwaters in the shallow system are influenced by the topography and the presence of geological structures in the catchment.

115 Chapter 5: Hydrogeological assessment of Spicers Creek catchment

Figure 5.23 Conceptual hydrogeological model for the Spicers Creek catchment groundwater system (see Figure 4.4 for location of cross section).

116 Chapter 6: Soil and water categorisation

CHAPTER 6: SOIL AND WATER CATEGORISATION

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6.1 INTRODUCTION In dryland salinity research, it is important to quantify the soil, groundwater, surface water and rainwater chemistry, to assess the extent and source of salinity within a catchment. This chapter aims to categorise the physical and chemical properties of soils and the hydrochemistry of the deep, intermediate and shallow groundwater systems present in the Spicers Creek catchment. It also aims to assess the vertical distribution of ions within the different aquifers, together with the spatial distribution of ions throughout the catchment. The hydrochemical categorisation of the soils, groundwaters, surface waters and rainwaters, has aided in evaluating the extent and type of ions that are contributing to salinisation processes within seepage zones located in the Spicers Creek catchment.

6.2 SOIL CATEGORISATION Soil landscapes of the Spicers Creek catchment have been briefly discussed in Chapter 2. The physical and chemical properties of soils contained within the three seepage zone sites (Site 1, Site 2 and Site 3) will be described with respect to physical properties, chemical properties, clay mineralogy and electrical resistivity properties. Soils from the three seepage zone sites possess different physical and chemical characteristics because each site has a different bedrock lithology, and are at different stages of salinisation. The soil characteristics are mostly dependent on the proximity to structural features in the catchment and hence the development of saline seepage zones.

The location of soil sampling points and geophysical investigations at the three experimental sites is shown in Figure 6.1. Soils from these experimental sites were analysed using various geoscientific techniques, which included; field assessment during piezometer installation and the use of 1:5 soil water extracts. The clay mineralogy of the soils was assessed by using a portable spectrophotometer device (PIMA) and XRD analysis was performed on selected samples to verify the PIMA results. The 1:5 soil water extracts were analysed for major and minor ions, EC and pH. Electrical resistivity image profiling was used to identify the clay distribution at the sites and confirm the location of the bedrock contact at these sites.

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Figure 6.1 Location of soil sampling points and geophysical investigations in Spicers Creek catchment.

6.2.1 Physical properties of soils The physical attributes of soil within the three experimental sites were determined on samples obtained during piezometer installation. Samples were collected at textural changes and were analysed in the field for texture, colour, the presence of mottling, soil structure, coherence, soil pH and the presence of pans (Charman and Murphy, 1998). Soil texture was determined using the approach adapted from Charman and Murphy (1998) and soil colours were determined using a Munsell Colour Company soil chart (1975). A full description of the field and laboratory methodology employed involving soil sampling is presented in Appendix A1.

6.2.1.1 Site 1 Experimental Site 1 is located on the Euchrozems of the Bodangora soil landscape groups (Murphy and Lawrie, 1998), which have formed on the Oakdale Formation. The soil profile thickness ranges from 5.7 m to over 12.3 m. At the time of drilling (Jun 2001), the unsaturated zone was 10 m thick at S3, thinning towards the seepage zone, reaching approximately 1.5 m bgs. The soil profile ranges from clay-rich to sand-clay-gravel to gravel-rich lithologies, with a decrease in grain-size distribution occurring towards the lower part of the cross-section at S1 (Figure

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Figure 6.2 Cross section of soil profiles within Site 1 with soil textures, colours, clay mineral percentage, soil water EC1:5 and soil moisture percentage depicted.

120 Chapter 6: Soil and water categorisation

6.2). Carbonate minerals are present throughout, with iron and manganese nodules present in the top 1 to 2 m of the profile. A thick (dark) yellowish brown saturated clay layer overlies the bedrock with alternating layers of sediments of varying permeability. Groundwater is contained within the clay/gravel to gravel-rich units, which form disconnected lenses of high permeability sediments.

Soils that are not affected by salinisation, generally range from dark red-yellowish- brown clays to yellowish brown sandy clay gravels, evolving to dark yellowish brown clay with clay sand, where the sediments meet the water table. Within the seepage zone (S1) soils become yellowish brown clay-rich with minor clay sand lenses throughout.

6.2.1.2 Site 2 Site 2 is located on the Ballimore Red-Brown Earths soil landscape group (Murphy and Lawrie, 1998) and the bedrock is composed of Mesozoic sedimentary units. A thin silica-rich soil profile overlies the bedrock at this site and ranges from 3.1 m to 9.3 m in thickness. The soil profile at Site 2 appears to have formed insitu on the sandstone to shale bedrock. The soil profile at Site 2 consists of clay-sand to clay- rich lithologies, where soils are not affected by seepage zone (S8) formation, the profile is well drained with oxidised iron-rich sediments above the water table. According to Charman and Murphy (1998), red to reddish brown colours are common in well-drained soil profiles, such as these seen in soil profile S8 at the top of the transect in Figure 6.3. Towards the bottom of the cross section within soil profiles S6 and S5, waterlogged conditions dominate (Figure 6.3) and a colour change from yellow brown to pale grey within the seepage zone profile is observed. This is attributed to the formation of a reduced environment, where dull yellow and grey colours form due to varying degrees of hydration of Fe and Al oxides in a more reduced environment (Charman and Murphy, 1998).

The unsaturated zone at Site 2 is generally approximately 4 m thick but towards the seepage zones within soil profiles S5 and S6, the water table intersects the land surface forming groundwater discharge zones.

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Figure 6.3 Cross section of soil profiles within Site 2 with soil textures, colours, clay mineral composition, soil water EC1:5 and soil moisture percentage depicted.

122 Chapter 6: Soil and water categorisation

Within the seepage zone profiles at S7, S6 and S5, clay translocation has occurred at the water table, where clay particles in the top of the soil profile have moved downwards due to eluviation and illuviation processes, which have been initiated by the rising and lowering of the water table (Charman and Murphy, 1998). This has lead to the formation of heavy clay layers below the water table. At Site 2, soils not affected by salinisation are yellow brown sandy clays. Towards the seepage zones soils become reddish brown clay sands (S7). Grainsize decreases further towards the seepage zone soil profiles (S6 and S5) where soils become yellowish brown clays with some clay gravels.

6.2.1.3 Site 3 Site 3 is located on the Bodangora Euchrozems soil landscape (Murphy and Lawrie, 1998), which overlie the Gleneski Formation volcanic units. These soils have formed from the volcanic units of the Gleneski Formation. Soils are composed of colluvial and alluvial material derived from the parent rock located throughout the catchment (Murphy and Lawrie, 1998). A hypothetical model of this site was developed primarily from data obtained during drilling, site inspection and geophysical investigations of this site. Soil profiles at Site 3 range from 1.4 m to 8.7 m thick, and consist of dark reddish brown loams grading into red heavy clays, to brown clay-gravel-rich lithologies, to greenish grey clay that overlies the volcanic bedrock. The unsaturated zone ranges from non-existent in the seepage zones to approximately 3 m bgs. Iron and manganese-rich nodules and carbonate minerals are found in the unsaturated zone, they have formed due to the rising and lowering of the water table throughout the site.

6.2.2 Chemical attributes of soils The soil chemistry of the Spicers Creek catchment was assessed by using 1:5 soil water extract technique, where 5 g of dried soil was mixed with 25 ml deionised water (Rayment and Higginson, 1992). The 1:5 soil water extract methodology is presented in Appendix A1. General parameters of soil water extracts together with ion chemistry were assessed with respect to the vertical and horizontal distribution of these parameters and ions at each experimental site. Descriptive statistics for soil water extracts for soils in the Spicers Creek catchment are presented in Table 6.1.

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Table 6.1 Descriptive statistics for 1:5 soil water extracts for soils in the Spicers Creek catchment.

Site 1 Site 2 Site 3 N Min Max Mean S.D N Min Max Mean S.D N Min Max Mean S.D EC 45 25 1287 329.2556 247.3202 43 38.4 415 219.1302 90.9398 7 477 792 605.5714 128.061 Depth (m) 45 -12.3 0 -4.92444 3.5966 43 -10.7 0 -2.62558 2.33881 7 -8.7 -0.6 -3.24286 2.74521 PH 45 5.99 9.658 8.31658 0.87232 43 6.41 9.025 8.09286 0.52017 7 7.68 8.741 8.42514 0.40597 moisture % 45 8 78 23.61111 14.16818 43 8.2 40.2 17.23023 6.67816 7 21.4 48.2 31.98571 10.5018 Al 45 0 1.831 0.18511 0.31784 43 0.03 42.624 3.2206 8.04017 7 0 0.013 2.77E-03 4.99E-03 As 45 0 0 8.01E-05 0 43 0 0 8.13E-05 8.07E-067 0 0 8.01E-05 0 B 45 0 0.019 1.98E-03 3.49E-03 43 0 0.064 9.81E-03 1.54E-027 0.001 0.004 1.80E-03 1.24E-03 Ca 45 0 0.514 0.18056 0.12674 43 0 0.327 8.70E-02 8.04E-027 0.076 0.601 0.23956 0.17389 Cu 45 0 0.001 4.62E-05 1.43E-04 43 0 0.002 3.25E-04 6.33E-047 0 0 4.72E-06 0 Fe 45 0 0.994 0.12466 0.22278 43 0 3.044 0.58707 0.84941 7 0 0 3.58E-05 0 K 45 0.04 0.252 0.10963 5.02E-02 43 0.02 1.049 0.21257 0.27315 7 0.176 0.343 0.27081 6.59E-02 Li 45 0 0.04 3.23E-03 8.58E-03 43 0 0.42 7.42E-02 0.10019 7 0 0 4.00E-04 0 Mg 45 0.06 0.691 0.22398 0.16393 43 0.01 1.325 0.23702 0.28267 7 0.376 0.819 0.59975 0.18439 Mn 45 0 0.01 1.07E-03 2.37E-03 43 0 0.021 2.94E-03 5.03E-037 0 0 3.64E-06 0 Na 45 0.13 11.092 2.41897 2.20729 43 0.15 3.893 2.06944 0.92012 7 2.623 5.263 4.20866 0.96452 Ni 45 0 0 3.41E-04 0 43 0 0.004 8.04E-04 9.33E-047 0 0 3.41E-04 0 Pb 45 0 0 4.83E-05 0 43 0 0 4.83E-05 0 7 0 0 4.83E-05 0

SO4 45 0 0.171 4.21E-02 4.01E-02 43 0.03 0.225 0.10098 4.51E-027 0.07 0.126 9.76E-02 1.84E-02 Sr 45 0 0.005 1.20E-03 1.46E-03 43 0 0.009 1.87E-03 2.04E-037 0.001 0.003 1.79E-03 8.29E-04 Zn 45 0 0 4.59E-05 0 43 0 0.005 4.11E-04 9.87E-047 0 0 4.59E-05 0 Cd 45 0 0 2.67E-05 0 43 0 0 2.67E-05 0 7 0 0 2.67E-05 0 Cl 45 0.17 12.52 2.33848 2.26265 43 0.4 2.82 1.37574 0.56085 7 3.665 7.219 5.05132 1.40655

HCO3 45 0 2.8 0.97644 0.61167 43 0 5.32 1.36558 1.1399 7 0.4 1.14 0.91571 0.24979

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6.2.2.1 Site 1

-1 Soil EC1:5 for Site 1 range from 25 to 1,300 μS cm , with an average of 330 μS cm-1 and a standard deviation of 250 μS cm-1. The large variation between the

EC1:5 is due to the progressive increase in salinity along the transect (from S3 to

S1) towards the seepage zone (Figure 6.2). The soil EC1:5 appears to be well + - correlated with soil moisture percentage, Na 1:5, Cl 1:5, and TDS1:5 as indicated in

Table 6.2. Soil pH1:5 ranges from pH 6 to pH 9.66 with an average of pH 8.32. Soil pH1:5 are mildly acidic in the topsoil (0 to 0.4 m) and then increases at depth forming alkaline soils. Within the seepage zone soil profile S1, soil pH1:5 remain + high throughout. Soil pH1:5 correlates well with Na 1:5 (Table 6.2). The moisture + - content of the soils is well correlated with soil EC1:5, Na 1:5 and Cl 1:5. This is indicated in Figure 6.2, where salinity peaks correlate with distinct increases in soil moisture throughout the soil profile. This factor may indicate that salinity is associated with saline groundwaters rather than salts contained within the soils.

Soil pH1:5 at Site 1 range from 5.994 to 9.658 with an average of 8.32. Elevated pH1:5 values occur within seepage zone groundwaters. Figure 6.2 shows throughout the soil cross-section for Site 1, soil moisture percentage, soil EC1:5 and pH1:5 increase in the seepage zone, where saline, sodic and alkaline soils are formed.

Table 6.2 Spearman’s nonparametric correlation coefficients for 1:5 soil water extracts for soils from Site 1 in the Spicers Creek catchment (n=45)

EC pH moisture B Ca K Mg Na Sr Cl

EC 1 .510 ** .700 ** -0.203 -0.114 -.486 ** 0.211 .950 ** 0.14 .915 ** pH .510 ** 1 .358 * -.349 * -.557 ** -.590 ** -0.266 .602 ** -.388 ** .342 * moisture .700 ** .358 * 1 -0.145 0.066 -0.223 .500 ** .725 ** .422 ** .747 ** B -0.203 -.349 * -0.145 1 -.354 * .374 * -0.119 -0.172 -0.28 -0.032 Ca -0.114 -.557 ** 0.066 -.354 * 1 0.258 .594 ** -0.273 .841 ** -0.019 K -.486 ** -.590 ** -0.223 .374 * 0.258 1 0.231 -.550 ** 0.291 -0.292 Mg 0.211 -0.266 .500 ** -0.119 .594 ** 0.231 1 0.165 .871 ** .426 ** Na .950 ** .602 ** .725 ** -0.172 -0.273 -.550 ** 0.165 1 0.044 .869 ** Sr 0.14 -.388 ** .422 ** -0.28 .841 ** 0.291 .871 ** 0.044 1 .301 * Cl .915 ** .342 * .747 ** -0.032 -0.019 -0.292 .426 ** .869 ** .301 * 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

Sodium1:5 is the major cation in soil solution for soils from Site 1 with concentrations ranging from 0.128 mmol L-1 to 11.1 mmol L-1. The vertical

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+ distribution of Na 1:5 at Site 1 indicate that in soils not affected by salinity (S3 and + S4) soil Na 1:5 concentrations generally increase with depth (Figure 6.4a and + Figure 6.4b). In soil profiles slightly affected by salinity (S2), Na 1:5 increases until + 5 m bgs then decreases in concentration (Figure 6.4c). Soil Na 1:5 in the salt + affected soil profile S1 show that Na 1:5 is higher in this profile compared with the other profiles and a peak at ~9 m bgs is experienced (Figure 6.4d). Chloride1:5 + -1 follow a similar trend to Na 1:5 although concentrations range from 0.169 mmol L in soils not affected by salinisation, to 12.52 mmol L-1 in the seepage zone soils (Table 6.1; Figure 6.4).

- + 2+ 2+ Figure 6.4 Vertical distribution of Cl 1:5, Na 1:5, Mg 1:5, Ca 1:5 and pH1:5 for soils water extracts from site 1. Soil profile (a) S3 not affected by salinity (b) S4 not affected by salinity (c) S2 slightly saline (d) S1 salt affected soils in the Spicers Creek catchment (soil texture legend refer to Figure 6.2).

-1 Magnesium1:5 concentrations range from 0.056 to 0.691 mmol L with an average -1 of 0.224 mmol L . Calcium1:5 concentrations ranges from zero in the seepage zone soils to 0.514 mmol L-1 in soils not affected by salinisation, with an average

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-1 2+ 2+ 2+ of 0.18 mmol L . A good correlation exists between Ca 1:5, Mg 1:5 and Sr 1:5 for soils located at Site 1 (Table 6.2).

- + 2+ 2+ The vertical distribution of Cl 1:5, Na 1:5, Mg 1:5, Ca 1:5 and pH1:5 are shown in Figure 6.4. Figure 6.4a and Figure 6.4b represent the vertical distribution of ions in soil profiles S3 and S4, which have not been affected by salinisation processes. + - These soil profiles show that Na 1:5 and Cl 1:5 are dominant ions in the soil water and concentrations increase due to the presence of clay-rich units within the soil 2+ profile. Calcium1:5 and Mg 1:5 have a relatively constant concentration throughout + - the soil profile. In Figure 6.4c, Na 1:5 and Cl 1:5 concentrations increase and a 2+ salinity bulge occurs in the top 5 m of the profile. Calcium1:5 and Mg 1:5 concentrations are relatively constant throughout the profile. Figure 6.4d shows a + - dramatic increase in Na 1:5 and Cl 1:5 concentrations in this profile and salinisation appears to be highest at ~9 m bgs. Soil profile S1 is saline, sodic and alkaline, + - 2+ containing elevated concentrations of Na 1:5, Cl 1:5 and a lack of Mg 1:5 and 2+ Ca 1:5.

6.2.2.2 Site 2

Soil EC1:5 for soils from Site 2 are less saline than Site 1 soils and range from 39 -1 -1 to 420 μS cm , with an average of 220 μS cm . Soil pH1:5 appears to be high, with an increase with depth. The highest soil pH1:5 results were encountered in soil profile S5 where soils are influenced by waterlogging. These soils are indicative of non-saline alkaline soils. Soil moisture composition is not related to EC1:5 as seen in Figure 6.3, except for soils contained within soil profile S7, where a bulge in soil moisture and soil EC1:5 occurs at 4.5 m. Soil moisture percentage increases in soil profiles S6 and S5, which corresponds with saturated and waterlogged soil profiles.

+ Sodium1:5 is the dominant cation for soils from Site 2, where Na 1:5 ranges from -1 -1 0.15 to 3.9 mmol L with an average of 2.1 mmol L (Table 6.1). Magnesium1:5 + 2+ increases with a decrease in Na 1:5, in soil profiles S8 and S7 and Mg 1:5 is dominant in soil profiles S6 and S5 within the seepage zones.

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- Soil Cl 1:5 concentrations are lower than in Site 1 soils ranging from 0.39 to 2.82 -1 + + mmol L . Soils from Site 2 contain elevated concentrations of Fe1:5, K 1:5, Li 1:5, 2+ - Sr 1:5 and HCO3 1:5 with respect to other soils from Site 1 and Site 3 (Table 6.1).

Soils from Site 2 have a distinctly different chemistry to those of Site 1. Table 6.3 + indicates that soils from Site 2 show a strong correlation between Fe1:5, B1:5, K 1:5 + and Li 1:5, indicating that soil forming processes differ from those at Site 1, where a + - strong Na 1:5 to Cl 1:5 correlation exists.

Table 6.3 Spearman’s nonparametric correlation coefficients for 1:5 soil water extracts for soils from Site 2 in the Spicers Creek catchment (n=43).

EC pH moisture B Ca Fe K Li Mg Na Sr Cl

EC 1 .317 * 0.135 -0.244 .376 * -0.02 0.01 -0.141 0.162 .748 ** 0.025 .708 ** PH .317 * 1 0.087 -.388 * 0.012 -0.207 -0.201 -0.259 -0.055 .423 ** -0.006 0.132 moisture 0.135 0.087 1 0.177 0.093 .328 * .369 * 0.297 0.089 0.003 0.145 0.067 B -0.244 -.388 * 0.177 1 .499 ** .838 ** .804 ** .757 ** .694 ** -.321 * .507 ** -.326 * Ca .376 * 0.012 0.093 .499 ** 1 .513 ** .547 ** 0.275 .725 ** 0.186 .449 ** 0.083 Fe -0.02 -0.207 .328 * .838 ** .513 ** 1 .915 ** .871 ** .775 ** -0.22 .695 ** -0.215 K 0.01 -0.201 .369 * .804 ** .547 ** .915 ** 1 .890 ** .728 ** -0.207 .740 ** -0.159 Li -0.141 -0.259 0.297 .757 ** 0.275 .871 ** .890 ** 1 .682 ** -0.222 .787 ** -0.166 Mg 0.162 -0.055 0.089 .694 ** .725 ** .775 ** .728 ** .682 ** 1 0.064 .778 ** -0.104 Na .748 ** .423 ** 0.003 -.321 * 0.186 -0.22 -0.207 -0.222 0.064 1 -0.04 .735 ** Sr 0.025 -0.006 0.145 .507 ** .449 ** .695 ** .740 ** .787 ** .778 ** -0.04 1 -0.062 Cl .708 ** 0.132 0.067 -.326 * 0.083 -0.215 -0.159 -0.166 -0.104 .735 ** -0.062 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

6.2.2.3 Site 3

Soil EC1:5 of soils located within Site 3 are highest at the land surface with a soil -1 EC1:5 value of 800 μS cm and decrease to 500 μS/cm at depth (~9 m bgs) (Figure 6.5). Salinity decreases with depth and is related to the soil moisture 2+ 2+ content as seen in Figure 6.5a. Soils from Site 3 have high Ca 1:5 and Mg 1:5 concentrations relative to other soils contained within Site 1 and Site 2. Calcium1:5 concentrations range from 0.076 to 0.601 mmol L-1 with average concentrations of -1 -1 0.239 mmol L . Magnesium1:5 concentrations range from 0.376 to 0.819 mmol L -1 with an average of 0.599 mmol L . The vertical distribution of soil EC1:5, soil - + moisture percentage, Cl 1:5 and Na 1:5 are related as seen in Figure 6.5. Where a peak is experienced between 2.5 to 4.5 m bgs and then decreases with depth.

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- + Boron1:5 appears to increase in the top 2 m of the soil profile, as Cl 1:5, Na 1:5, and 2+ Sr 1:5 decrease. Ions within soil waters at Site 3 appear to decrease with depth.

+ - 2+ Figure 6.5 Vertical distribution of (a) moisture and EC1:5 (b) Na 1:5, Cl 1:5, Sr 1:5 and B1:5 for soils from site 3, in the Spicers Creek catchment.

6.2.3 Clay mineralogy of soils 6.2.3.1 Site 1 The clay mineralogy of soils from Site 1, reflect soil-water processes. The clay mineralogy was determined using a portable spectrophotometer, the methodology for this technique is discussed in detail in Appendix A1. Soil profile S3, contains 100% halloysite at the top of the soil profile with an increase in montmorillonite to 40% of the clay mineral composition with depth. At 2 m bgs, a steady decrease in montmorillonite content occurs with depth, where the clay mineral composition is composed of 90% halloysite and 10% montmorillonite at 6 m bgs (Figure 6.2). At the bottom of the drill hole (12 m bgs) at soil profile S3, the clay mineralogy content is composed of 65% halloysite and 35% montmorillonite.

Soil profile S2, has a large amount of clay mineralogical variation with 100% halloysite in the top 1 m, increasing in montmorillonite content to approximately 20% of the total clay mineralogy. From 2 to 6 m bgs, the clay composition is composed of 60% nontronite and 40% illite. From 6 m to 12 m bgs, the clay mineralogy is composed of 15% illite, 40% nontronite and 45% montmorillonite.

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Soil profile S1, has a clay composition that consists of 60% halloysite and 40% montmorillonite at the surface, with an increase in halloysite with depth. Halloysite becomes the dominant clay mineral at depth due to the hydrated nature of the profile.

6.2.3.2 Site 2 The clay mineral composition present at Site 2 consist of halloysite and kaolinite in varying quantities down the soil profile, depending on the soil profile position in the transect and the depth of the soil profile (Figure 6.3). Soil profile S8, contains 100% halloysite at the surface with an increase in kaolinite percentage at depth. At 2 m bgs, the clay mineral composition consists of 55% halloysite and 45% kaolinite, with an increase in kaolinite to 60% at depth. Soil profile S7, follows a similar trend where 100% halloysite occurs within the first metre with a gradual increase in kaolinite (55%) relative to halloysite (45%). At the bedrock contact (9 to 10 m bgs), kaolinite is equal to halloysite. Soil profiles located at S6 and S5 contain mostly halloysite due to the hydrated nature of the system, where soil profile S6 contains 100% halloysite until 3 m bgs and an increase in kaolinite to 30% of the clay mineral composition occurs. At the bottom of the cross-section at soil profile S5, halloysite dominates with an increase in kaolinite percentage (25%) experienced at 3 m bgs (Figure 6.3).

6.2.4.3 Site 3 The clay mineral composition of Site 3 soils, consist of predominantly halloysite in the upper profile with minor montmorillonite throughout. Vermiculite becomes dominant at the bedrock contact located at 9 m bgs. The presence of the clay mineral vermiculite in Site 3 soils is indicative of the underlying volcanic parent material.

6.2.4 Electrical resistivity results Electrical geophysical methods were used at Sites 1, 2 and 3 to evaluate the variation in resistivity of a shallow aquifer insitu. The methodology for using electrical resistivity image profiling in the Spicers Creek catchment is described in Appendix A1. Electrical resistivity image profiling was used by Acworth and

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Jankowski (1997); Acworth (1999); Acworth and Jankowski (2001) to identify the salt load contained within clay-rich units contained within dryland salinity affected sites in New South Wales. It is a useful tool that is used to delineate the shallow subsurface geology and hence the extent of clay-rich units within a site.

Electrical resistivity measurements are recorded in milliohms m-1 and represent the bulk resistivity of the subsurface. When the subsurface material is homogenous, the EC value is the reciprocal of resistivity (MacDonald et al., 2001). In most aquifer systems, this is not representative because the subsurface is heterogenous and the EC value must be calibrated against the porosity, pore water EC and clay content of the unit (Acworth. 1999). High resistivity readings may indicate the presence of higher porosity aquifers with low EC groundwaters. Low resistivity readings may indicate the presence of clay-rich material and/or the presence of saline groundwaters. Figure 6.1 shows the location of geophysical profiles completed at Site 1, Site 2 and Site 3 in the Spicers Creek catchment.

6.2.4.1 Site 1 The electrical resistivity of soils from Site 1 was investigated in detail, where three electrical resistivity image lines where run in transects across and parallel to the seepage zone present at Site 1. Line 1 is 230 m in length and follows an east-west direction and dissects the seepage zone present at Site 1 (Figure 6.6). A resistive boundary located at approximately ~12 m bgs can be clearly identified in Figure 6.6, which represents the bedrock contact. Overlying the resistive bedrock is a lower resistivity unit that forms the clay-rich shallow aquifer system.

The fault zone between piezometers S1 and S2 can be delineated from this figure. This area contains slightly less resistive material than the surrounding material. Low resistivity clay-rich saline lenses are forming within the seepage zones and are represented in blue, they are forming down slope of the piezometer locations. The presence of this slightly higher resistivity material within the fault zone can be also identified in Figure 6.7 and Figure 6.8.

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Figure 6.6 Electrical resistivity image profile of line 1, at Site 1 with generalised groundwater flow direction and bedrock contact (data collected by author and Ramin Nikov).

Figure 6.7 represents a resistivity line that follows a north-east to south-westerly direction. At the beginning of this transect between 0 to 40 m, a higher resistivity area is encountered and represents the fault zone at Site 1. This figure also indicates that the soil profile is thicker (~20 m) towards the centre of Site 1.

Figure 6.7 Electrical resistivity image profile of line 2, at Site 1 with generalised groundwater flow direction and bedrock contact (data collected by author and Ramin Nikov).

Line 3 is 190 m in length and follows a north to south direction and is located across the seepage zone in Figure 6.8. This cross-section also shows the presence of a slightly higher resistive material relative to the surrounding unit.

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The presence of a higher resistivity material in the seepage zone implies that sediments in the fault zone have a higher permeability and/or groundwater salinity than the surrounding material. The depth to bedrock and the presence of a permeable fault zone has been delineated using electrical resistivity methods at Site 1.

Figure 6.8 Electrical resistivity image profile of line 3, at Site 1 with generalised groundwater flow direction and bedrock contact (data collected by author and Ramin Nikov).

6.2.4.2 Site 2 The electrical resistivity profile of Site 2, and is over 400 m in length and clearly identifies the undulating nature of the higher resistivity underlying bedrock (Figure 6.9). A bedrock high is encountered at 80 m along the transect as indicated by the presence of high resistivity material. The presence of this structural feature appears to be forcing groundwater to discharge at this point in the landscape. Soils are more resistive in Site 2, indicating these are soils are more permeable in nature. The physical properties of soil contained within Site 2 indicate that they are silica-rich sediments and generally have larger grain sizes present throughout the profile.

6.2.4.3 Site 3 The electrical image profile of Site 3, is represented in Figure 6.10, which is approximately 400 m in length. Soils from Site 3 contain the least resistive signatures and the bedrock has the highest resistivity readings of the three experimental sites. These results indicate that soils are clay-rich and/or saline and

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1:5 soil water extracts confirm that soils are more saline at Site 3. The high resistivity readings of the bedrock represent the relatively permeable weathered section of the fractured bedrock Gleneski Formation aquifer at Site 3. The uniform nature of the low resistivity material indicates that this material is transported and well sorted.

Figure 6.9 Electrical resistivity image profile of line 1, at Site 2 with generalised groundwater flow direction and bedrock contact (data collected by author and Ramin Nikov).

Figure 6.10 Electrical conductivity image profile of line 1, at Site 3 with generalised groundwater flow direction and bedrock contact (data collected by author and Ramin Nikov).

6.2.5 Summary of soil characteristics in the seepage zones The physical properties of soils from the three experimental sites indicate that they are dependent on; the underlying parent material and the extent of seepage zone formation at each site.

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Generally soils that are not affected by salinisation are composed of mostly yellowish brown clay sand gravel textures, moving towards the seepage zone where the soil texture changes to clay-rich sediments. Soil moisture increases, soil pH!:5 increases, leaving a saline, sodic and alkaline soil forming within the seepage zones. Soil chemistry in soils not affected by salinisation have low concentrations + - 2+ 2+ of Na 1:5, Cl 1:5, Mg 1:5 and Ca 1:5. As soil become more salinised they increase in + - 2+ 2+ Na 1:5, and Cl 1:5 concentrations and decrease in Mg 1:5 and Ca 1:5 concentrations.

Generally, the clay mineral composition of the soils is not affected greatly by salinisation processes in the Spicers Creek catchment where soil profiles consist of montmorillonite and kaolinite with varying amounts of halloysite. Within the salinised seepage zones, halloysite becomes the dominant clay mineral.

The use of electrical resistivity imaging at each site highlighted the boundary between the low resistivity shallow aquifer unit and higher resistivity bedrock units. The presence of higher resistivity material representing geological structural features was also identified.

6.3 HYDROCHEMICAL CATEGORISATION OF GROUNDWATERS Groundwaters within the Spicers Creek catchment have been divided into five groups according to the aquifer from which they were abstracted. These groups include: ¾ The Oakdale Formation groundwaters that were abstracted from a fractured mafic volcanic bedrock unit that forms part of the deep aquifer system. This unit is present in the western half of the catchment; ¾ The Gleneski Formation groundwaters that were abstracted from a fractured felsic volcanic bedrock unit that forms part of the deep aquifer system. This unit is present in the eastern half of the catchment; ¾ The intermediate aquifer system groundwaters which were abstracted from fractured sandstones and siltstone units;

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¾ Na-HCO3-rich groundwaters that also originate from the intermediate aquifer system and are found in the north-western section of the catchment. These groundwaters have been described extensively by Schofield (1998); Schofield and Jankowski (2003, 2004); and ¾ The shallow aquifer groundwaters, which were abstracted from unconsolidated sediments, composed of colluvium and alluvium. The shallow aquifer groundwaters are further divided into the experimental site that they were abstracted, Site 1, Site 2 and Site 3.

A total of one hundred and seventy four groundwater samples were collected from these aquifer systems. Groundwaters were sampled for major ions, minor ions, nutrients, trace elements and isotopes. Groundwaters have been categorised according to the aquifer they were abstracted from to highlight the hydrochemical characteristics of each groundwater type. Groundwaters are discussed with regards to major ion chemistry, water types, and trace element concentrations. The chemical type of the groundwaters in Spicer Creek catchment were calculated in the computer program AQUACHEM (Calmback, 1997), using the concentrations + + 2+ 2+ - 2- 2- - of major cations (Na +K , Ca , Mg ) and major anions (HCO3 +CO3 , SO4 , Cl ). When an ion is calculated to be over 10% (in meq L-1) of the total anions or total cations in the water, then it is classified as a chemical type of water. The methodology employed for obtaining these samples is described in Appendix A1.

A Piper diagram of the five groundwater groups contained in the Spicers Creek catchment is represented in Figure 6.11. The Piper diagram is based on a multi- triangular diagram (Piper, 1944) and aims to graphically display major cations and anions to aid in classifying groundwaters and further highlight geochemical processes that may be influencing the groundwater composition. Figure 6.11 shows the vastly different groundwater chemistries of the shallow, intermediate and deep groundwater systems in the Spicers Creek catchment.

Three main end-member groundwater types can be identified, they include the (1)

Na-HCO3-rich groundwaters of the intermediate aquifer system that plot in the lower quadrant of the diamond shaped diagram, the (2) Na-Cl-rich groundwaters of the shallow, intermediate and Oakdale Formation groundwaters that plot in the

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Chapter 6: Soil and water categorisation right hand corner of the diamond shaped Piper diagram and the fresh groundwaters of the shallow and Gleneski Formation aquifer systems that plot roughly in the centre of the Piper diagram.

Figure 6.11 Piper diagram of groundwaters from the Spicers Creek catchment.

6.3.1 Hydrochemical categorisation of deep groundwaters Two main fractured volcanic bedrock aquifers are present in the Spicer Creek catchment. They include the Oakdale Formation and Gleneski Formation. Six groundwater samples were obtained from the Oakdale Formation aquifer and eight groundwater samples from the Gleneski Formation aquifer. A total of twenty-one groundwater samples were obtained from the intermediate groundwater systems, which include six Na-HCO3-rich groundwaters. Due to the distinctive groundwater chemistry of the Na-HCO3-rich groundwaters, they will be discussed separately from the other intermediate groundwaters.

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The descriptive statistics for general parameters and major ions of these deep and intermediate groundwaters are presented in Table 6.4 and the descriptive statistics for minor ions and trace elements are presented in Table 6.5.

6.3.1.1 Oakdale Formation groundwaters The Oakdale Formation is predominantly a mafic volcanic unit that was deposited in a submarine environment. Salinities of the Oakdale Formation range from 4,460 μS cm-1 to 14,510 μS cm-1, with Na+ dominating the cation composition with an average of 6,850 mg L-1 and Cl- dominating the anion composition with an average -1 2- of 4,720 mg L . Oakdale Formation groundwaters contain very high SO4 concentrations reaching 1,245 mg L-1, in the most saline groundwater (Table 6.4).

Water types range from Na-Cl-rich groundwaters to Mg-Na-Cl-rich and to mixed

Na-Mg-Cl-HCO3-rich waters. Groundwaters are neutral with an average pH of 7.1, reducing with an average Eh of –197 mV and tepid with an average temperature of 21°C.

Table 6.4 Descriptive statistics of general parameters and major ions for the deep and intermediate groundwater systems of the Spicers Creek catchment.

General parameters Major ions

°C μS cm-1 mV mg L-1 mg L-1 Oakdale Formation T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 Minimum 18.7 4460 6.9 -22.3 0 16 537 120 76.9 1.5 1060 605.2 23.4 Maximum 23 14510 7.55 -300 4.6 153 2650 364 308 42.7 4719 1293 1243 Mean 20.89 6856.4 7.099 -197 1.386 94.6 1041 229.3145.7 13.21 1958 895.1262.4 S.D 1.648 3481.8 0.225 93.81 1.699 49.5 731.5 88.15 96.17 13.74 1285 240 439.3 N 6 6 6 6 6 6 6 6 6 6 6 6 6 Gleneski Formation T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 Minimum 19.3 954.5 6.84 -263 0 63.4 92.32 16.7 11.9 2.59 160 289.8 8.97 Maximum 22 6645 8.26 -67.2 3.5 222 741 404 188.5 21.1 1979 1156 178.6 Mean 20.6 3637.8 7.236-149 1.029 131 325.9 226.2103.5 9.886 920.5 780.666.16 S.D 1.037 1900.9 0.47766.69 1.374 57.9 240.5 134.661.02 8.8 618.9 286.461.12 N 8 8 8 8 8 8 8 8 8 8 8 8 8 Inter- mediate T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 Minimum 19.3 3065 5.28 -364 0 16 376 38.9 29.9 1.4 479.9 85.7 0 Maximum 22.3 21250 8.5 55.1 42.1 1283 4530 655.2 488 93.1 6978 4040 898.8 Mean 20.59 8390.3 6.805 -130 6.729 258 1419 228.5153.7 25.76 2303 1294 200.9 S.D 0.956 4818.1 0.659116.6 11.77 333 1049 161.7112.1 27.06 1762 1081 247.6

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General parameters Major ions N 15 15 15 15 15 15 15 15 15 15 15 15 15

Na-HCO3- rich T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 Minimum 21 3600 6.27 -312 0 616 819.7 32.6 61.5 77.89 49.2 2758 0 Maximum 24 4990 6.71 32.2 42.1 2253 1220 64 133.4 104.8 479.9 3889 60 Mean 22.03 4593.3 6.432 -163 7.068 1190 1077 47.3991.43 91.78 135.5 3461 11 S.D 1.08 502.58 0.198130.6 17.16 557 138.8 13.8531.14 9.607 170.8 394.724.04 N 6 6 6 6 6 6 6 6 6 6 6 6 6

+ Oakdale Formation groundwaters contain elevated concentrations of NH4 with a maximum concentration of 6.71 mg L-1. Notable elevated trace element concentrations include Sr2+, As and U. Oakdale Formation groundwaters contain very high Sr2+ concentrations ranging from 1,860 to 20,100 μg L-1. Arsenic ranges from 5.1 to 19.4 μg L-1 with an average concentration of 11.7 μg L-1. Uranium is also elevated in the Oakdale Formation groundwaters ranging from 2 to 11.8 μg L- 1 with an average of 5.5 μg L-1. Most Oakdale Formation groundwaters plot in the far right hand corner of the Piper diagram in Figure 6.11, indicating that these groundwaters have a strong Cl- dominance with varying concentrations of Mg2+ and Na+.

6.3.1.2 Gleneski Formation groundwaters The Gleneski Formation was deposited in a submarine environment and is predominantly a felsic volcanic unit. The Gleneski Formation groundwaters are generally less saline than the Oakdale Formation groundwaters, with salinities ranging from 955 μS cm-1 to 6,650 μS cm-1, with an average of 3,640 μS cm-1. They possess a different chemical composition to those of the Oakdale Formation and are varied in cation and anion chemical composition, where groundwater types range from Mg-Na-(Ca)-Cl-HCO3 to Na-(Ca-Mg)-Cl-HCO3 to Na-HCO3-Cl- rich. They contain less Na+ (average 330 mg L-1), Cl- (average 1980 mg L-1), Sr2+ -1 2- -1 (average 1,800 μg L ) and SO4 (average 67 mg L ). Gleneski Formation groundwaters have high Mg2+ concentrations with an average concentration of 227 mg L-1. These groundwaters have a slightly higher pH values ranging from 6.84 to 8.26, they are reducing, ranging from extremely reducing (-263 mV) to mildly reducing (-67 mV) with and average of –149 mV and contain low DO, with an average of 1.44 mg L-.

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Table 6.5 Descriptive statistics of minor ions and trace elements for the deep and intermediate groundwater systems of the Spicers Creek catchment. Minor elements Nutrients Trace elements mg L-1 mg L-1 μg L-1 Oakdale 2+ 3+ 2- Formation Fe Fe Fetot S SIO2 NO3 PO4 NH4 Ag As B Ba Cd Co Cr Cu Ga Li Mn Ni Pb Rb Sr U Zn Minimum 0.02 0.06 0.07 0.01 3.5 2.46 0.58 0.4 1.5 5.11 175 56.1 5.3 5.3 2.74 10 10 8.7 1.7 2.89 1860 2.02 8.7 Maximum 3.74 0.05 3.74 2.61 34.4 16.28 5.7 6.71 1.5 19.4 387 532 5.55 9.4 23.2 89 1590 15.4 4.6 34.5 20100 11.8 258 Mean 0.897 0.004 0.901 0.57 15.94 8.888 3.345 2.403 1.5 11.88 257.9 207 5.387 7.85 9.048 33.77 507.7 12.43 3.15 13.41 6151 5.528 123 Std. Deviation 1.344 0.038 1.339 0.935 11.05 6.959 2.663 2.9 5.946 72.1 220.4 0.142 1.794 9.557 28.47 588.8 2.911 2.051 14.28 6421 4.419 116.9 Gleneski 2+ 3+ 2- Formation Fe Fe Fetot S SIO2 NO3 PO4 NH4 Ag As B Ba Cd Co Cr Cu Ga Li Mn Ni Pb Rb Sr U Zn Minimum 0 -0.34 0 0 3 7.04 0.45 0.03 0.29 1.08 62.11 121 0.22 0.39 5.462.45 5.24 4.19 8.72 5.86 1.81 1.22 344 0.69 9.57 Maximum 0.34 0.66 0.77 1.25 38.2 28.16 0.67 1.11 2.71 12.5 362 690.6 2.2 3.09 10.1 3.59 18.37 62.3 821 10.5 5.07 32.6 3250 14.5 403 Mean 0.14 0.027 0.167 0.267 16.514.3 0.563 0.538 1.12 5.535 195.9 321.5 0.977 1.413 7.8483.02 11.93 17.71 268.8 7.11 3.693 12.87 1817 4.726 125.7 Std. Deviation 0.147 0.338 0.301 0.483 14.87 9.488 0.09 0.486 1.083 5.036 106.7 224.6 1.069 1.464 1.683 0.806 5.335 19.96 336 1.926 1.688 12.15 1012 5.617 150.8 Inter- 2+ 3+ 2- mediate Fe Fe Fetot S SIO2 NO3 PO4 NH4 Ag As B Ba Cd Co Cr Cu Ga Li Mn Ni Pb Rb Sr U Zn Minimum 0.08 -0.37 0.05 0 2.7 4.84 0.01 0.04 0.58 4.96 20 0.99 10 4.02 3.5 9 1.65 6.97 20 2.5 1.6 2.89 1300 1.87 8.7 Maximum 12.39 16.08 27.74 7.27 61.9 14.52 5.7 4.52 4.67 26.5 2120 1800 29 11.1 11 77 81.3 339 2070 202 4.5 150 14200 5.75 1505 Mean 3.095 1.498 4.329 0.849 11.99.191 1.059 1.683 1.769 14.91 583.8 232.6 19.75 7.618 7.4 27.75 15.1 83.59 712.3 31.76 3.133 36.81 4730 3.668 320.1 Std. Deviation 3.834 4.381 6.995 1.824 14.09 3.404 1.9 1.652 1.35 8.584 602.4 485.8 8.77 3.372 2.681 32.9 25.39 82.81 765 53.72 1.457 46.37 3652 1.861 423.5

Na-HCO3- 2+ 3+ 2- rich Fe Fe Fetot S SIO2 NO3 PO4 NH4 Ag As B Ba Cd Co Cr Cu Ga Li Mn Ni Pb Rb Sr U Zn

Minimum 0.71 0.66 0 5.6 11 0.01 4.52 0.42 2.78 495 1.43 0.42 0.26 5.5 1.16 40.66 189 12.76 2.5 29.83 137 210 0.07 10.44 Maximum 3.08 3.08 1.02 8.7 11 0.01 4.52 0.58 2.78 1610 1800 14 0.26 36.06 10 81.3 366.8 12.76 32 29.83 150 1800 0.07 550 Mean 1.402 1.303 0.37 7.34 11 4.52 0.5 2.78 971 523 8.484 0.26 20.78 4.54 60.98 273.1 12.76 14.87 29.83 143.5 762.7 0.07 288.2 Std. Deviation 0.973 0.905 0.384 1.142 0.113 412.8816.7 5.964 21.613.825 28.74 66.66 12.27 9.214627.6 220.9

140 Chapter 6: Soil and water categorisation

Gleneski Formation groundwaters contain lower Cl- concentrations ranging from -1 - 160 to 1,979 mg L and have a low average concentration of HCO3 (average of -1 - 781 mg L ) and contain elevated NO3 levels with a maximum concentration of 28.2 mg L-1 (Table 6.5).

Gleneski Formation groundwaters plot from the top of the diamond shaped Piper diagram towards the left hand corner, indicating Gleneski Formation groundwaters have varied Mg2+ and Na+ concentrations. These groundwaters generally have - between 40 to 60% HCO3 within these groundwaters.

Gleneski Formation groundwaters contain the lowest concentration of trace elements, where Sr2+, B and Li+ are well below the concentrations of other aquifers in Spicers Creek catchment (Table 6.5).

6.3.1.3 Intermediate groundwaters Intermediate groundwaters are varied in groundwater chemistry in the Spicers Creek catchment because they have been sampled from various lithological units, which consist of sediments deposited in marine through to terrestrial geological environments. Hence, the salinities and ionic composition of these waters are variable. Groundwater salinities range from 3,070 μS cm-1 to 21,250 μS cm-1 with and average value of 8,400 μS cm-1. They have a large standard deviation for EC with a value of 4,800 μS cm-1, indicating their variability. Intermediate groundwaters range from highly reducing (-364 mV) to oxidised (55 mV) with an average Eh value of –130 mV. Intermediate groundwaters are slightly acidic (pH 5.28) to slightly alkaline (pH 8.5), with an average pH of 6.8 and average temperature of 21°C.

Intermediate groundwaters contain the highest ionic variation in the catchment ranging from saline Na-Cl-rich groundwaters to mixed Na-(Mg-Ca)-Cl-HCO3-rich, + to relatively fresh Na-HCO3-Cl-rich groundwaters. They contain high Na concentrations (>4,500 mg L-1) and high Cl- concentrations (>6,900 mg L-1). - Intermediate groundwaters have elevated HCO3 concentrations ranging from 86 to 4,040 mg L-1, with an average of 1,295 mg L-1. They also have high

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2- -1 2+ concentrations of SO4 with an average 200 mg L . They have the highest Mg (655 mg L-1) and Ca2+ (488 mg L-1) concentrations. These groundwaters also -1 2- -1 -1 contain elevated Fe (27.8 mg L ), S (7.27 mg L ) and SiO2 (61.9 mg L ) concentrations.

These mixed groundwaters plot from the top of the diamond shaped diagram in Figure 6.11 and evolve to the Na-Cl-rich groundwaters located in the right hand side corner. They also evolve towards the bottom of the diamond shaped diagram where the Na-HCO3-rich groundwaters are located.

Trace elements are also elevated in the intermediate groundwaters with high B, Sr2+, Li+, As, Mn, Ni, Zn and Ag concentrations experienced. Arsenic is highest in these deep groundwaters ranging from 5 to 26.5 μg L-1 with an average of 14.9 μg L-1. Manganese reaches a maximum of 2,070 μg L-1, Ni a maximum of 202 μg L-1 and Zn a maximum of 1,505 μg L-1 (Table 6.5).

6.3.1.4 Na-HCO3-rich groundwaters (intermediate aquifer system)

Na-HCO3-rich groundwaters are part of the intermediate aquifer systems and the least saline bedrock groundwaters within the catchment, with EC values ranging from 3,600 μS cm-1 to 4,990 μS cm-1 with an average value of 4,590 μS cm-1

(Table 6.4). Na-HCO3-rich groundwaters have slightly higher average temperatures of 22°C and are reducing with an average Eh of –162mV and DO of -1 0.2 mg L . Na-HCO3-rich groundwaters have the lowest pH, with an average of 6.43 and are the most homogenous in hydrochemical character, ranging from Na-

HCO3-rich to Na-HCO3-Cl-rich groundwaters. They plot in the bottom centre of the diamond shaped Piper diagram in Figure 6.11.

These groundwaters are composed of mainly Na+, which ranges from 820 to 1,220 -1 -1 - mg L , with an average 1,077 mg L , and HCO3 which ranges from 2,760 to 3,900 mg L-1, with an average of 3,460 mg L-1. These groundwaters also contain -1 elevated CO2 concentrations, with an average concentration of 1,190 mg L and elevated K+ concentrations ranging from 78 to 105 mg L-1. These groundwaters - 2- 2+ 2+ have low Cl , SO4 , Mg and Ca concentrations.

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Na-HCO3-rich groundwaters contain elevated trace element concentrations such as B, Ba, Cr, Ga, Li+ and Rb. The groundwaters have an average B concentration of 970 μg L-1, average Ba concentration of 523 μg L-1, an average Ga concentration of 61 μg L-1, an average Li+ concentration of 273 μg L-1, and an average Rb concentration of 143 μg L-1. Chromium is also elevated in these groundwaters and ranges from 5.5 to 36.1 μg L-1, with an average of 21 μg L-1.

6.3.2 Hydrochemical categorisation of shallow groundwaters Shallow groundwaters will be discussed according to four groups. Firstly, all the shallow groundwaters from the Spicers Creek catchment will be discussed and then groundwaters from the experimental sites will be discussed, to highlight various groundwater chemical characteristics that change within seepage zones. A total of one hundred and thirty nine shallow groundwaters were sampled over the study period from various piezometers located within the Spicers Creek catchment and from sub-catchments including Snake Gully and Racecourse Gully, which are located within the Spicers Creek catchment. Groundwaters from the experimental sites will be discussed according to those not affected by salinity (fresh groundwaters) and those that are salinised (seepage zone groundwaters). Table 6.6 presents the descriptive statistics for general parameters and major ions, for the shallow groundwaters from the study area. The location of these sample points is shown in Figure 5.2.

Table 6.6 Descriptive statistics of general parameters and major ions for the shallow groundwaters in the Spicers Creek catchment.

General parameters Major ions

μS °C cm-1 mV mg L-1 mg L-1

Shallow T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 N 128 129 129 129 122 124 139 139 139 139 139 139 139 Minimum 13.05 443.5 6.44 -297.4 0.06 0 88 4.41 2.16 0.43 59.98 124.5 0 Maximum 32 23250 8.66 332 8.03 1166 4670 984 561 41.95 8877 2870 847.9 Mean 19.9 6889 7.18 -29.45 2 232.5 936.1 343 116.4 7.6 2166 913.7101.6 Std. Deviation 2.742 4284 0.4 80.66 1.52 169.4 804 225.4 102.6 9.674 1554 361.1 139.4

Site 1 T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 N 36 36 36 36 34 34 36 36 36 36 36 36 36

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General parameters Major ions Minimum 14.65 1250 6.53 -201.8 0.35 0 105 41.5 18.5 2.17 96.47 350.2 5.17 Maximum 32 11285 8.66 78 5.4 466.5 1900 854.6 561 40.7 4040 1850 277.7 Mean 20 5756 7.19 -28.692.17 175.1 686.2 305.3 165.9 8.127 1878 756.555.77 Std. Deviation 3.091 2902 0.439 58.87 1.32 109.4 560.5 204.7 141 9.61 1092 349.8 64.33

Site 2 T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 N 17 17 17 17 17 17 18 18 18 18 18 18 18 Minimum 13.05 1287 6.58 -297.4 0.08 14.08 250.1 17.15 16.02 0.61 199.9 451.5 15.82 Maximum 25.1 12435 8.3 76 5.59 674.2 2234 305 247 7.76 4119 1290 670 Mean 19.54 4340 7.339 -41.9 2.59 147 848.6 115.8 72.32 3.395 1259 810.6 146.2 Std. Deviation 3.338 3292 0.436 81.7 1.42 148.5 694.5 83.88 51.26 2.193 1218 251.8 177.3

Site 3 T EC pH Eh O2 CO2 Na Mg Ca K Cl HCO3 SO4 N 23 23 23 23 23 23 25 25 25 25 25 25 25 Minimum 13.15 4140 6.65 -78.3 0.15 73.94 337.2 115 20.22 0.52 1200 469.8 19.08 Maximum 23 20040 7.9 211 5.88 360.9 2650 966 402 30.1 7738 1860 183.4 Mean 19.83 6320 7.205 -21.43 1.58 196.5 883.8 332.4 81.89 4.87 2019 833.6 66.67 Std. Deviation 2.185 3189 0.359 54.72 1.2 80.49 472.4 173.7 76.46 7.221 1286 260 45.99

The shallow groundwaters in the Spicers Creek catchment have varying water chemistries, where groundwaters that are not salinised range from fresh to brackish, and an increase in salinity is experienced within the seepage zones groundwaters. These seepage zone groundwaters have high groundwater salinities, with elevated concentrations of major ions and trace elements. The groundwater chemical composition at these sites changes from low salinity “background” groundwaters to saline within the seepage zones.

6.3.2.1 Shallow groundwaters Shallow groundwaters in the Spicers Creek catchment are varied ranging, from ~450 μS/cm) to 23,250 μS cm-1 with an average EC of 6,900 μS cm-1. Temperatures range from 13 to 32°C, and pH ranges from slightly acidic (pH 6.44) to alkaline (pH 8.66). Shallow groundwaters range from oxidising (Eh~330 mV, 8.03 mg/L DO) to reducing (-300 mV, 0.06 mg/L). Dominant cations include Na+, with concentrations ranging from 88 to 4,970 mg L-1 and Mg2+, with concentrations ranging from ~4 to 990 mg L-1. Dominant anions include Cl- which ranges from 60 -1 -1 to ~8,900 mg L , with an average of 2,170 mg L , and HCO3 ranging from 125 to 2,870 mg L-1, with an average of 914 mg L-1 (Table 6.6).

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Shallow groundwaters in the Spicers Creek catchment have elevated concentrations of trace elements such as As, Ba, Ga, Se, Sr2+ and V (Table 6.7). Arsenic concentrations are elevated ranging from 1.2 to 46 μg L-1 with an average of 8.4 μg L-1, which is above the drinking water guidelines of 7 μg L-1. These groundwaters also have elevated Se concentrations, which range from 3.7 to 77.9 μg L-1 with an average 25.7 μg L-1. Vanadium is elevated ranging from 2 to 44.9 μg L-1, with an average of 16.5 μg L-1. Chromium ranges from 3.4 to 26.15 μg L-1, with an average of 9.8 μg L-1. The lowest concentrations are experienced in groundwaters not affected by salinity and as salinity increases, trace element composition increases, with trace element concentrations above the drinking water guidelines.

The majority of shallow groundwaters range from fresh Na-Mg-Cl-HCO3 to Mg-Na-

Cl-HCO3 to saline Mg-Na-Cl and Na-Cl-rich groundwaters. Na-Mg-Cl-HCO3 are the most common water type present in the catchment and these groundwaters are located at the top of the Snake Gully catchment, the Spicers Creek catchment, the Racecourse Gully and the top of the cross-section at Site 2. These groundwater types are indicative of groundwaters that are not affected by salinisation processes. Mg-Na-Cl-HCO3 type groundwaters are the next most common water type, are present at the top of the Snake Gully catchment, and represent salinised groundwaters of Site 2 and Site 3. These water types represent groundwaters that are mixed with recharge groundwaters and salt affected groundwaters. Mg-Na-Cl and Na-Mg-Cl groundwater types represent seepage zone groundwaters. Na-Cl-rich groundwaters are the most saline groundwaters in the Spicers Creek catchment and represent end-member groundwaters that are not mixed with fresh recharge groundwaters. Other water types present in the shallow groundwaters represent the mixing of Na-Cl-rich groundwaters with fresher Na-HCO3 groundwaters.

Table 6.8 represents a Spearman’s correlation matrix for shallow groundwaters in Spicers Creek catchment. This table reveals that salinity (EC) is closely correlated with major ions such as Cl-, Mg2+, Na+ and with trace elements such as Br, As, Se, Sr2+ and V in shallow groundwaters.

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Table 6.7 Descriptive statistics of minor ions and trace elements for the shallow groundwaters in the Spicers Creek catchment. Minor elements Nutrients Trace elements mg L-1 mg L-1 μg L-1 tot 2- shallow Fe S Br SIO2 NO3 PO4 NH4 Ag As B Ba Co Cr Cu Ga Li Mn Mo Ni Rb Se Sr U V Zn Zr N 120 73 43 81 74 70 73 48 48 130 48 48 48 101 48 99 123 48 81 48 48 131 48 48 81 48 Minimum 0 0 1.3 2.8 0 0.08 0.01 0.09 1.18 34 29.4 0.32 3.4 0.68 0.73 0.99 7 0.31 2.33 0.22 3.69 2 0.58 1.96 2 0.15 Maximum 4.8 2.04 30.7 35.2 44 2.8 6.32 11.2 45.7 3520 1216 19.1 26.2 32 32.3 107 4840 120 64 16.9 77.9 12469 62.3 44.9 202 1.96 Mean 0.34 5E-02 8.38 12.9 9.04 0.53 0.87 1.72 8.65 375 370 3.65 9.84 3.37 9.93 14 859 6.53 11.3 2.8 25.7 4156 13.9 16.5 35.4 0.61 Std. Deviation 0.71 0.25 6.24 7.07 8.53 0.41 1.2 2.79 8.09 405 304 4.16 4.55 3.52 8.3 18.9 983 19.9 9.53 3.58 17.1 2883 12.4 10.6 32.8 0.41 tot 2- Site 1 Fe S Br SIO2 NO3 PO4 NH4 Ag As B Ba Co Cr Cu Ga Li Mn Mo Ni Rb Se Sr U V Zn Zr N 32 21 12 22 22 21 22 12 12 34 12 12 12 24 12 28 35 12 20 12 12 36 12 12 20 12 Minimum 0.01 0 1.67 6.6 1.32 0.08 0.17 0.09 1.18 34 112 0.39 4.19 0.68 2.94 1.02 46.7 0.45 2.66 0.22 4.81 1030 3.84 2.88 2 0.23 Maximum 3.41 0.34 15.5 29.2 27.7 1.01 3.46 11.2 14.1 1090 1216 11.8 26.2 13.7 32.3 33 4840 14.5 64 10 54.7 11709 25.5 19.3 114 1.61 Mean 0.46 0.02 7.14 15.6 8.62 0.4 0.72 1.61 6.43 351 605 3.42 10.1 3.4 16.2 11.1 1351 3.03 16.4 1.9 24 5953 13.3 10.6 35.5 0.67 Std. Deviation 0.85 0.07 4 7.06 6.82 0.23 0.87 3.15 4.22 275 321 3.1 6.74 2.84 8.84 7.97 1156 3.94 14 2.63 14.9 3149 7.06 5.1 29.9 0.4 tot 2- Site 2 Fe S Br SIO2 NO3 PO4 NH4 Ag As B Ba Co Cr Cu Ga Li Mn Mo Ni Rb Se Sr U V Zn Zr N 15 11 5 12 11 9 11 6 6 18 6 6 6 13 6 13 16 6 9 6 6 17 6 6 13 6 Minimum 0.01 0 2.14 4.6 4.44 0.21 0.05 0.16 1.3 175 57.6 0.32 3.4 1.74 1.72 0.99 7 1.2 2.33 0.84 3.69 379.5 5.01 1.96 2 0.16 Maximum 1.94 0.4 13.1 17.2 29 0.88 2.45 1.64 10.5 830 221 3.33 14.8 32 5.73 46 4010 120 28 4.92 47.7 6530 37 14.4 202 1.67 Mean 0.4 0.05 5.77 9.64 10.8 0.54 0.68 0.85 4.66 395 129 1.33 7.58 5.76 3.48 18 746 34.4 9.64 2.89 18.1 1994 19.1 8.46 51.8 0.88 Std. Deviation 0.52 0.12 4.4 3.27 7.39 0.25 0.86 0.6 3.36 158 61.4 1.25 4.42 8 1.64 16.4 1126 50.4 7.85 1.59 15.6 1493 11.6 4.08 58.4 0.51 tot 2- Site 3 Fe S Br SIO2 NO3 PO4 NH4 Ag As B Ba Co Cr Cu Ga Li Mn Mo Ni Rb Se Sr U V Zn Zr N 20 12 10 14 12 12 12 11 11 25 11 11 11 22 11 17 21 11 17 11 11 23 11 11 19 11 Minimum 0.01 0 4.19 7 3.52 0.13 0.01 0.25 3.65 110 80.7 0.58 7.8 0.98 2.29 2.19 31 0.32 4 0.65 14.5 1110 3.9 7.56 2 0.22 Maximum 1.41 0.01 6.99 24.2 44 1.54 6.32 11 9.23 3520 507 6.58 13.9 7 13.9 9 1310 2.05 25.2 2.76 34.9 8250 11 40.2 70.9 0.88 Mean 0.19 0 5.77 14.8 9.46 0.43 0.82 2.78 5.77 462 290 3.03 10 2.71 7.88 5.24 433 1.09 8.42 1.07 20.3 3071 6.79 18.4 30.2 0.41 Std. Deviation 0.31 0 1.03 6.23 11.2 0.37 1.75 3.54 1.64 710 172 2.31 2 1.63 4.63 2.1 430 0.47 5.07 0.63 5.87 1780 1.97 11.3 21.4 0.23

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Table 6.8 Spearman’s nonparametric correlation coefficients for shallow groundwaters in Spicers Creek catchment (n=139).

EC Na Ca Mg HCO3 SO4 Cl Br As Ba Cr Se Sr V

EC 1 .779** .188* .726** .518** .613** .951** .893** .885** -0.07 0.2 .921** .529** .627** Na .779** 1 -0.15 .331**.606** .621** .756** .730** .752** -.304* .308* .757** .229**.558** Ca .188* -0.15 1 .416** -.310** 0.09 .242** -0 -0.01 0.25 -0.21 0.01 .730** -0.14 Mg .726** .331** .416** 1 0.15 .434** .786** .580** .606** 0.21 -0.01 .643** .655** .499**

HCO3 .518** .606** -.310** 0.15 1 .342** .398** .415** .566** -0.2 .563** .444** -0.08 .392**

SO4 .613** .621** 0.09 .434** .342** 1 .633** .407** .630** -.519** -0.02 .520** .268** .483** Cl .951** .756** .242** .786** .398** .633** 1 .887** .870** -0.01 0.14 .917** .613** .628** Br .893** .730** -0 .580** .415** .407** .887** 1 .742** 0.1 0.09 .980** .446** .623** As .885** .752** -0.01 .606** .566** .630** .870** .742** 1 -0.13 0.22 .789** .446** .679** Ba -0.07 -.304* 0.25 0.21 -0.2 -.519** -0.01 0.1 -0.13 1 0.02 0.06 .322* -0.18 Cr 0.2 .308* -0.21 -0.01 .563** -0.02 0.14 0.09 0.22 0.02 1 0.21 -0.1 0.15 Se .921** .757** 0.01 .643** .444** .520** .917** .980** .789** 0.06 0.21 1 .512** .570** Sr .529** .229** .730** .655** -0.08 .268** .613** .446** .446** .322* -0.1 .512** 1 0.13 V .627** .558** -0.14 .499** .392** .483** .628** .623** .679** -0.18 0.15 .570** 0.13 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

6.3.2.2 Site 1 shallow groundwaters Salinities of the shallow groundwaters from Site 1 range from 1,250 μS cm-1 to 11,290 μS cm-1, with an average groundwater EC of 5,760 μS cm-1 (Table 6.6). Salinity varies at this site due to the presence of a saline seepage zone that forms towards the bottom of the transect (Figure 6.2). Groundwaters that are not salinised (“fresh” groundwaters) are Mg-Na-Cl-HCO3-rich and evolve to salinised Na-Mg-Cl to Mg-Na-Cl-rich groundwaters within the seepage zone. Sodium ranges from 105 mg L-1 in the “fresh” groundwaters to 1,900 mg L-1 in the seepage zones. Chloride follows this same trend with ~100 mg L-1 in the “fresh” groundwaters, to 4,040 mg L-1 in the seepage zone groundwaters (Table 6.7). Shallow groundwaters at Site 1 are neutral with an average pH of 7.19, reducing (Eh –202 mV) to oxidising (Eh 78 mV) and have an average temperature of 20°C. “Fresh” -1 - -1 groundwaters contain higher SiO2 concentration (28 mg L ) and NO3 (28 mg L ), and seepage zone groundwaters contain higher B (1,100 μg L-1) and Sr2+ -1 concentrations (11,300 μg L ). Bicarbonate is also elevated in the seepage zone groundwaters with an average concentration of 1,850 mg L-1, compared with 350 mg L-1 for “fresh” groundwaters.

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Trace elements that are elevated in Site 1 groundwaters include As, which ranges from 1.2 to 14 μg L-1, with an average of 6.4 μg L-1. Arsenic correlates well with Cl-, Br, Se, V and U (Table 6.9). Boron ranges from 34 to 1,090 μg L-1 with an average -1 + - of 350 μg L and correlates well with Na , HCO3 and U. Barium ranges from 112 to 1,215 μg L-1 with an average of 605 μg L-1. Chromium is highest in Site 1 groundwaters and ranges from 4.2 μg L-1 to 26.2 μg L-1 with an average of 10 μg L- 1 - + and it correlates well with HCO3 and Li . Selenium is highest in Site 1 groundwaters ranging from 4.8 μg L-1 to 54.7 μg L-1 with an average of 24 μg L-1. + 2+ 2- - Selenium correlates well with EC, Na , Mg , SO4 , Cl , Br, As, U and V. Strontium ranges from 1,030 to 11,710 μg L-1 with an average of 5,950 μg L-1 and correlates well with Mg2+, Cl-, Br and Se. Vanadium ranges from 3 μg L-1 to 19.2 μg L-1 with -1 2- an average of 8.5 μg L and correlates well with SO4 , Br, Se and As.

Table 6.9 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 1 in the Spicers Creek catchment (n=39).

EC Na Mg HCO3 Cl Br As B Cr Se Sr U V

EC 1 .569** .624** .395* .827** .965** .993** .596** 0.25 .958** .512** .783** .881** Na .569** 1 0.3 .793** .665** .727** .706* .831** 0.52 .720** 0.23 .839** .755** Mg .624** 0.3 1 -0.02 .828** .783** .762** 0.27 0.13 .797** .891** 0.46 .790**

HCO3 .395* .793** -0.02 1 0.3 .622* .643* .730** .657* .601* -0.13 .832** 0.57 Cl .827** .665** .828** 0.3 1 .993** .972** .590** 0.2 .986** .705** .741** .930** Br .965** .727** .783** .622* .993** 1 .951** .671* 0.21 .993** .741** .776** .944** As .993** .706* .762** .643* .972** .951** 1 .608* 0.27 .944** .643* .755** .888** B .596** .831** 0.27 .730** .590** .671* .608* 1 0.57 .685* 0.31 .825** .671* Cr 0.25 0.52 0.13 .657* 0.2 0.21 0.27 0.57 1 0.22 0.07 0.55 0.2 Se .958** .720** .797** .601* .986** .993** .944** .685* 0.22 1 .720** .804** .930** Sr .512** 0.23 .891** -0.13 .705** .741** .643* 0.31 0.07 .720** 1 0.36 .706* U .783** .839** 0.46 .832** .741** .776** .755** .825** 0.55 .804** 0.36 1 .692* V .881** .755** .790** 0.57 .930** .944** .888** .671* 0.2 .930** .706* .692* 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

6.3.2.3 Site 2 shallow groundwaters Groundwaters from Site 2 follow a similar trend to Site 1, where “fresh” groundwaters have different hydrochemical signatures to the seepage zone groundwaters. Groundwater salinities range from 1,300 μS cm-1 in the “fresh” groundwaters to 12,430 μS cm-1 in the seepage zones (Table 6.7). “Fresh”

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groundwaters range from Na-Cl-HCO3 to Na-Mg-HCO3-rich and change to Na-Cl- rich groundwaters within the salinised seepage zone groundwaters. Sodium ranges from 310 to 2,080 μS cm-1, Cl- follows a similar pattern ranging from 200 to 4,110 mg L-1 with the highest concentrations found in the salinised seepage zones. Groundwaters are neutral with an average pH of 7.34 and range from extremely reducing (Eh -297 mV) to oxidising (Eh 76 mV) with an average - temperature of 19.5°C. “Fresh” groundwaters contain higher NO3 concentrations, reaching 29 mg L-1.

Table 6.10 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 2 in the Spicers Creek catchment (n=21).

EC CO2 Na Mg HCO3 SO4 Cl As B Li Mo Se Sr EC 1 0.36 .978** .937** .690** .673** .982** .943** .483* 0.33 0.09 1** .832**

CO2 0.36 1 0.34 0.290.23 .716** 0.32 0.75 -0.16 0.38 0.06 .812* 0.3 Na .978** 0.34 1 .897**.715** .770** .959** .943** .544* 0.23 0.09 1** .849** Mg .937** 0.29 .897** 1 .651** .581* .966** 1** .478* 0.37 0.26 .943** .867**

HCO3 .690** 0.23 .715** .651** 1 .523* .672** .943** .527* 0.12 0.49 .829* 0.45

SO4 .673** .716** .770** .581* .523* 1 .687** .829* 0.28 0.19 0.03 .943** .494* Cl .982** 0.32 .959** .966** .672** .687** 1 .943** .500* 0.36 0.09 1** .858** As .943** 0.75 .943** 1** .943** .829* .943** 1 0.14 0.6 0.26 .943** .829* B .483* -0.16 .544* .478* .527* 0.28 .500* 0.14 1 -0.45 0.09 0.2 0.21 Li 0.33 0.38 0.23 0.37 0.12 0.19 0.36 0.6 -0.45 1 -0.03 0.66 0.44 Mo 0.09 0.06 0.09 0.26 0.49 0.03 0.09 0.26 0.09 -0.03 1 0.09 0.03 Se 1** .812* 1** .943** .829* .943** 1** .943** 0.2 0.66 0.09 1 .943** Sr .832** 0.3 .849** .867** 0.45 .494* .858** .829* 0.21 0.44 0.03 .943** 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

Trace element concentrations of groundwaters within Site 2 become elevated in the seepage zone groundwaters, with the highest concentrations of Cu, Mo, Nd and Zn occurring in Site 2 groundwaters. Other notable trace elements include Se and Cr, which are both elevated in these groundwaters. Arsenic is low within Site 2 groundwaters, ranging from 1.3 to 10.5 μg L-1 with an average of 4.7 μg L-1. Boron ranges from 175 to 830 μg L-1 with an average of 395 μg L-1 and correlates well with U (Table 6.10). Zinc is also highest at Site 2, with a maximum of 202 μg L-1 and it correlates well with Se.

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6.3.2.4 Site 3 shallow groundwaters Groundwater salinity for Site 3 ranges from 4,140 μS cm-1 to 20,040 μS cm-1. These groundwaters have an average pH of 7.2 and range from oxidised (Eh 211 mV, DO 5.99 mg L-1) to reduced (Eh –78, DO 0.15 mg L-1). Site 3 groundwaters have the highest Mg2+ concentrations of the shallow groundwaters, ranging from 115 to 966 mg L-1 with an average of 332 mg L-1. Sodium ranges from 340 to 2,650 with a lower than average concentration of 333 mg L-1. Chloride ranges from -1 -1 - -1 1,200 mg L to 2,000 mg L and HCO3 ranges from 470 to 1,860 mg L .

Groundwaters range from Na-Mg-Cl to Na-Cl-HCO3 to Mg-Na-Cl-HCO3-rich.

Table 6.11 Spearman’s nonparametric correlation coefficients for shallow groundwaters from Site 3 in the Spicers Creek catchment (n=28).

EC Na K Ca Mg Fe HCO3 SO4 Cl Br As B Se Sr V

EC 1 .690** -0.02 -0.28 0.41 -0.21 0.07 .534** .919** .988** .873** 0.1 .936** -0.03 0.53 Na .690** 1 -0.09 -0.35 -0.1 -0.14 .539** .615** .610** .685* 0.58 .544** .664* -0.23 .618* K -0.02 -0.09 1 0.17 0.37 0.1 -.496* 0.03 0.2 -0.1 -0.03 0.36 -0.01 .532** 0.03 Ca -0.28 -0.35 0.17 1 .399* 0.13 -.459* 0.05 -0.16 -0.44 -0.5 -.482* -0.5 .606** -0.56 Mg 0.41 -0.1 0.37 .399* 1 .480* -.660** 0.03 .584** 0.24 0.5 -0.29 0.46 .742**-0.07 Fe -0.21 -0.14 0.1 0.13 .480* 1 -0.27 -0.38 0.2 0.26 0.13 -0.26 0.12 0.29 0.57

HCO3 0.07 .539** -.496* -.459* -.660** -0.27 1 0.25 -0.12 0.02 -0.02 0.37 0.14 -.498* 0.2

SO4 .534** .615** 0.03 0.05 0.03 -0.38 0.25 1 .406* 0.47 0.37 0.36 0.52 -0.05 0.12 Cl .919** .610** 0.2 -0.16 .584** 0.2 -0.12 .406* 1 .827** .866** 0.19 .834** 0.13 0.53 Br .988** .685* -0.1 -0.44 0.24 0.26 0.02 0.47 .827** 1 .879** -0.02 .952** -0.22 .673* As .873** 0.58 -0.03 -0.5 0.5 0.13 -0.02 0.37 .866** .879** 1 0.15 .927** 0.14 0.59 B 0.1 .544** 0.36 -.482* -0.29-0.26 0.37 0.36 0.19 -0.02 0.15 1 0.12 -0.15 0.41 Se .936** .664* -0.01 -0.5 0.46 0.12 0.14 0.52 .834** .952** .927** 0.12 1 0.21 0.54 Sr -0.03 -0.23 .532** .606** .742** 0.29 -.498* -0.05 0.13 -0.22 0.14 -0.15 0.21 1 -0.46 V 0.53 .618* 0.03 -0.56 -0.07 0.57 0.2 0.12 0.53 .673* 0.59 0.41 0.54 -0.46 1 **Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).

- + Site 3 groundwaters have the highest NO3 and NH4 concentrations, with a maximum of 44 mg L-1 and a maximum of 6.32 mg L-1 experienced, respectively.

These two nutrients correlate well with SiO2 (Table 6.11). Silver is also highest in Site 3 groundwaters with an average of 2.8 μg L-1. Arsenic ranges from 3.7 to 9.2 μg L-1 with an average of 5.8 μg L-1 and correlates well with Cl-, Br and Se. Boron is highest in Site 3 groundwaters with a maximum concentration of 3,520 μg L-1 and high average concentration of 462 μg L-1. Lead has a maximum concentration

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-1 -1 2- of 380 μg L with an average of 41 μg L and correlates well with SO4 . Selenium ranges from 14.5 to 35 μg L-1 with an average of 20.3 μg L-1 and correlates well with Br and As. Strontium ranges from 1,110 to 8,250 μg L-1 with an average of 3,070 μg L-1 and is well correlated with Mg2+. Vanadium has a higher than average concentration of 18.4 μg L-1 for shallow groundwaters and correlates well with U.

6.3.4 Vertical distribution of ions with depth The vertical distributions of ions in groundwaters within the deep, intermediate and shallow aquifers were assessed using bivariate plots of, depth versus various general parameters, major ions and trace elements. The vertical distribution of these parameters and ions indicate trends that are occurring with depth within these different aquifers present in the Spicers Creek catchment.

A scatter plot of groundwater depth versus groundwater EC indicates that groundwaters from the shallow, intermediate and the Oakdale Formation aquifers show an increase in EC with depth (Figure 6.12a). A lack of correlation exists between EC and depth for the Gleneski Formation groundwaters and Na-HCO3- rich groundwaters in the Spicers Creek catchment.

The relationship between depth versus Cl- and Na+ concentration (Figure 6.12b and Figure 6.15c) indicate that these ions follow a similar trend to EC, where Cl- and Na+ appear to increase in the shallow, intermediate and the Oakdale Formation groundwaters with depth. Gleneski Formation groundwaters are - + experiencing a decrease in Cl and Na with depth and Na-HCO3-rich groundwaters are constant. Figure 6.12d indicates that Mg2+ concentrations increase with depth in the shallow groundwaters and appears to decrease with depth in the intermediate and deep groundwaters.

2- The relationship between depth versus SO4 in Figure 6.13a shows that a large 2- increase in SO4 is experienced in the Oakdale Formation groundwaters, 2- intermediate groundwaters and shallow groundwaters with depth and SO4 decreases in the Gleneski Formation and Na-HCO3-rich groundwaters. The relationship between depth versus Ca2+ in Figure 6.13c shows that Ca2+ increases with depth in salinised groundwaters but decreases in the Gleneski Formation and 151

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Na-HCO3-rich groundwater with depth. The relationship between depth versus - - HCO3 in Figure 6.13b indicates that HCO3 increases with depth in Na-HCO3-rich groundwaters and this same phenomenon is identified in Figure 6.13d where K+ also increases with depth in Na-HCO3-rich groundwaters.

Figure 6.12 Vertical distribution of (a) EC (b) Cl- (c) Na+ and (d) Mg2+ for deep, intermediate and shallow groundwaters from the Spicers Creek catchment.

The relationship between depth versus Li+ in Figure 6.14a shows Li+ increases with depth in Na-HCO3-rich groundwaters. This figure highlights shallow groundwaters that are mixing with Na-HCO3-rich groundwaters and shows an increase with depth most likely due to mixing processes. Gleneski Formation, Oakdale Formation and most intermediate groundwaters have a constant concentration of Li+ with depth.

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2- - 2+ + Figure 6.13 Vertical distribution of (a) SO4 (b) HCO3 (c) Ca and (d) K for deep, intermediate and shallow groundwaters from the Spicers Creek catchment. General trend experienced in (1) shallow groundwaters (2) Intermediate groundwaters (3) Oakdale Formation (4) Gleneski Formation groundwaters and (5) Na-HCO3-rich groundwaters.

The relationship between depth versus B in Figure 6.14b indicates that Na-HCO3- rich groundwaters are high in B concentration and shows a similar trend to Li+ where groundwaters elevated in B appear to be related to the Na-HCO3-rich groundwaters. The relationship between depth versus Sr2+ in Figure 6.14c shows that Sr2+ is elevated in saline groundwaters from the shallow, intermediate and Oakdale Formation groundwater systems. Groundwaters that are not salinised have a lack of correlation between Sr2+ and depth. The relationship between depth versus As in Figure 6.14d also shows that salinised groundwaters contain elevated concentrations of As. A lack of correlation between As concentrations in

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Chapter 6: Soil and water categorisation groundwaters exists because As mobilisation is reliant on pH and redox conditions (Smedley and Kinniburgh, 2002).

Figure 6.14 Vertical distribution of (a) Li+ (b) B (c) Sr2+ (d) Astot for deep, intermediate and shallow groundwaters from the Spicers Creek catchment.

The vertical distribution of various elements with depth in the Spicers Creek + 2+ 2- catchment groundwaters indicates that EC, Na , Sr , As and SO4 all increase - + with depth in salt affected groundwaters. Lithium, B, HCO3 and K are elevated in

Na-HCO3-rich groundwaters and increases in concentration with depth.

6.3.5 Spatial distribution of ions The spatial distribution of general parameters, major ions and trace elements, allowed for the visualisation of areas in the catchment where elevated concentrations of elements are occurring in relation to aquifer lithology, position in

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Chapter 6: Soil and water categorisation groundwater flow system and location with respect to structural features in the catchment. The grouping divisions for each parameter or element were developed in ARCVIEW using the “natural breaks” in the raw data set. These groupings are based on five divisions for each parameter or element that is mapped.

The spatial distribution of groundwater EC in the Spicers Creek catchment is presented in Figure 6.15. The divisions between each grouping was based on “natural breaks” identified within the data set, the author then grouped the salinities according to; low salinity groundwaters (0 to 5,000 μS cm-1), medium salinity groundwaters (5,001 to 7,500 μS cm-1), high salinity (7,501 to 10,000 μS cm-1), and very high salinity groundwaters (10,001 to 24,000 μS cm-1). This map indicates that the lower salinity groundwaters are located to the north of the

Spicers Creek catchment. Groundwaters in the north-east are Na-HCO3-rich groundwaters, which have lower salinities (<5,000 μS cm-1). The presence of saline groundwater (>10,000 μS cm-1) appears to be associated with the presence of structural features throughout the catchment. The most salinised groundwaters plot within close proximity of geological structures in the catchment.

The spatial distribution of Cl- in Figure 6.16 further indicates that groundwaters associated with geological structures in the catchment have elevated Cl- -1 -1 concentrations ranging from 4,000 mg L to 9,000 mg L . Na-HCO3-rich groundwaters in the north-western corner are characterised by low Cl- concentrations.

The spatial distribution of Sr2+ in Figure 6.17 shows that elevated Sr2+ concentrations are associated with groundwaters associated with the geological structures in the catchment. Strontium concentrations are particularly high (>10,000 μg L-1) in the fault zone that runs north-east throughout the catchment.

Na-HCO3-rich groundwaters and groundwaters in the north-western corner of the catchment have low Sr2+ concentrations. Strontium is a good indicator of the presence of saline groundwaters within the geological structural zones in the Spicers Creek catchment.

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Due to the elevated concentrations of Sr2+ associated with the fault zones, the spatial distribution of 87Sr/86Sr isotopic ratios for deep groundwaters were plotted in Figure 6.18. This figure was produced to identify the association of 87Sr/86Sr isotopic ratios with respect to the geological structures in the catchment. This figure indicates that less radiogenic values (0.705 – 0.706) are associated with higher concentrations Sr2+, which are also associated with the saline groundwaters contained within the fault zone.

The spatial distribution of Na+ is presented in Figure 6.19 and it shows two major trends for Na+. It appears that elevated Na+ concentrations (2,000 to 5,000 mg L-1) are associated with geological structures in the catchment. Lower Na+ -1 concentrations (1,000 to 2,000 mg L ) are associated with Na-HCO3-rich groundwaters in the north-western corner of the catchment. Therefore, Na+ concentrations are not as useful for discerning groundwater types in the catchment + because Na-HCO3-rich and saline groundwaters are both elevated in Na concentrations.

The spatial distribution of EC, Cl-, Sr2+ and 87Sr/86Sr isotopic ratios show that these parameters can be used to identify the presence of saline groundwaters associated with geological structures.

- The spatial distribution of HCO3 in Figure 6.20 clearly delineates the presence of - -1 elevated concentrations of HCO3 (3,000 to 6,000 mg L ) within the north-western corner of the catchment, representing Na-HCO3-rich groundwaters. This figure also indicates that groundwaters associated with the geological structures are - - lower in HCO3 concentrations. Hence, the presence of high HCO3 concentrations near the town of Saxa (Figure 6.20) may indicate Na-HCO3-rich groundwaters are present further east than previously realised and the mixing of these Na-HCO3-rich groundwaters with groundwaters further east in the Spicers Creek catchment is + - likely. Therefore, elevated concentration of Na and HCO3 in Site 2 groundwaters may have resulted due to groundwater mixing processes.

- - The spatial distribution of Cl and HCO3 indicates that different groundwater types are present in the catchment. They include the Na-HCO3-rich groundwaters, which

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- - contain groundwaters with low Cl and high HCO3 concentrations and the Na-Cl- - - rich groundwaters that contain high Cl and low HCO3 concentrations. The spatial distribution of major ions has shown that elevated Cl- concentrations are associated with groundwaters contained within geological structural zones and - HCO3 concentrations are associated with Na-HCO3-rich groundwaters.

+ The spatial distribution of K in Figure 6.21 highlights the presence of Na-HCO3- rich groundwaters in the north-west of the catchment. Elevated K+ concentrations appear to be associated with the presence of Na-HCO3-rich groundwaters throughout the catchment. Once again, the presence of elevated K+ concentrations towards Saxa may indicate the mixing of Na-HCO3-rich with other groundwaters in the Spicer Creek catchment. Elevated concentrations of K+ are may also be used as a tracer of the extent of Na-HCO3-rich groundwaters in the Spicers Creek catchment.

The spatial distribution of Li+ in the Spicers Creek catchment is represented in Figure 6.22, indicating that elevated concentrations of Li+ are associated with Na-

HCO3-rich groundwaters in the north-western section of the catchment. Other groundwaters throughout the catchment have concentrations <100 mg L-1. Lithium can be used as a tracer for identifying the extent of Na-HCO3-rich groundwaters in the catchment.

13 Finally, the spatial distribution of δ CDIC within the Spicers Creek catchment is shown in Figure 6.23. This figure shows enriched δ13C values are experienced in the north-western section of the catchment and are represented by the enriched

Na-HCO3-rich groundwaters. These carbon-13 isotopic signatures are an excellent tracer that can be used to delineate the extent of Na-HCO3-rich groundwaters in the catchment and identify mixing between these waters.

The spatial distribution of general parameters and major and minor ions in the Spicers Creek catchment groundwaters highlights the presence of different groundwater types throughout the catchment. Na-HCO3-rich groundwaters can be identified in the north-western corner of the catchment, are categorised by low EC + - + + values, and elevated concentrations of Na , HCO3 , K and Li . These 157

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- 2+ groundwaters also have a lack of Cl and Sr . Na-HCO3-rich groundwaters have enriched carbon-13 values relative to other groundwaters in the catchment and are easily identified by this signature. The presence of Na-HCO3-rich groundwaters further east within the Spicers Creek catchment was delineated from the spatial distribution of these parameters and ions, and the mixing of these groundwaters within the groundwater seepage zones at the experimental sites is a strong possibility.

Saline groundwaters associated with geological structures throughout the catchment were also identified from the spatial distribution of various parameters and ions. Saline groundwaters are characterised by high EC groundwaters with elevated concentrations of Na+, Cl-, Sr2+ and non-radiogenic 87Sr/86Sr isotopic ratios. These unique signatures will be discussed in Chapter 7.

The spatial distribution of parameters and elements in these groundwaters show the location and extent of the different end-member groundwaters present in the catchment. They also show the relationship between saline groundwaters and geological structures in the catchment.

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Figure 6.15 The spatial distribution of groundwater EC in the Spicers Creek catchment.

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Figure 6.16 The spatial distribution of Cl- in groundwaters in the Spicers Creek catchment.

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Figure 6.17 The spatial distribution of Sr2+ in groundwaters in the Spicers Creek catchment.

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Figure 6.18 Spatial distribution of 87Sr/86Sr isotopes for groundwaters in the Spicers Creek catchment.

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Figure 6.19 The spatial distribution of Na+ in groundwaters in the Spicers Creek catchment.

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- Figure 6.20 The spatial distribution of HCO3 in groundwaters in the Spicers Creek catchment.

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Figure 6.21 The spatial distribution of K+ in groundwaters in the Spicers Creek catchment.

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Figure 6.22 The spatial distribution of Li+ in groundwaters in the Spicers Creek catchment.

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Figure 6.23 Spatial distribution of δ13C isotopes for groundwaters in the Spicers Creek catchment.

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6.3.6 General chemical characteristics of groundwaters The general chemical character of groundwaters in the Spicers Creek catchment indicate that groundwater chemistry is dependent on two main factors; the aquifer lithology and mixing between two end-member groundwaters present in the catchment. These end-members include the Na-HCO3-rich groundwaters from the intermediate groundwater system and the Na-Cl-rich groundwaters associated with geological structures in the catchment.

Figure 6.24 Piper diagram of groundwaters groups contained within the Spicers Creek catchment.

The Oakdale Formation groundwaters have a varied chemistry ranging from relatively fresh (~4,500 μS cm-1) to extremely saline (~14,000 μS cm-1). These groundwaters have a Cl- dominance and mixed Na+ and Mg2+ composition. The Oakdale Formation groundwaters plot in a “L” shape from Mg-Cl-rich to Na-Cl-rich in Figure 6.24. The main influence on the chemical composition of these

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Chapter 6: Soil and water categorisation groundwaters is the location of these groundwaters with respect to geological structures in the catchment. The Oakdale Formation groundwaters contained within the fractured structural zones have high salinities, high concentrations of + - 2- 2+ Na , Cl , SO4 , Sr , As and V.

The Gleneski Formation groundwaters are relatively fresh groundwaters with salinities ranging from ~950 μS cm-1 to ~6,500 μS cm-1. These groundwaters have 2+ - - high concentration of Mg and contain varied amounts of HCO3 and Cl . Gleneski Formation groundwaters plot in the centre of the Piper diagram in Figure 6.24.

The intermediate groundwater system has the most varied groundwater chemistry, where groundwaters range from relatively fresh (~3,000 μS cm-1) to extremely saline (~21,300 μS cm-1). These groundwaters have the highest ionic variation and their general groundwater chemistry is primarily influenced by where they are located with respect to geological structures and the presence of Na-HCO3-rich groundwaters in the catchment. Salinised groundwaters in the intermediate + - 2- 2+ groundwater system contain high concentrations of Na , Cl , SO4 , Sr , As, V and Se and plot near the Na-Cl-rich end-member groundwater in Figure 6.31.

Groundwaters that are mixing with Na-HCO3-rich groundwaters have elevated - + + concentrations of HCO3 , CO2, K , Li , B and Cr and these groundwaters plot towards the Na-HCO3-rich end-member groundwaters in Figure 6.24.

Na-HCO3-rich groundwaters have relatively fresh groundwaters with an average of ~4,500 μS cm-1, when compared with other groundwaters in the Spicers Creek + - + + catchment. They are elevated in Na , HCO3 , K , CO2, B, Cr, Ga, Li and Rb - 2- 2+ concentrations. These groundwaters have low concentrations of Cl , SO4 , Mg 2+ and Ca . Na-HCO3-rich groundwaters plot in the bottom quadrant of the diamond shaped Piper diagram in Figure 6.24.

Seepage zone affected groundwaters from Site 1 are salinised (>10,000 μS cm-1) + - 2- - 2+ and contain high concentrations of Na , Cl , SO4 , HCO3 , Sr , B, Ba, Cr, As, Se and V. It appears that these seepage zone groundwaters have elevated + - 2- 2+ concentrations of Na , Cl , SO4 , Sr , As, Se and V due to the presence of saline

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Chapter 6: Soil and water categorisation groundwaters associated with geological structures in the catchment. Elevated - concentrations of HCO3 , B, Ba and Cr may be contributed from Na-HCO3-rich groundwaters that may be mixing within the seepage zone also. Groundwaters from Site 1 plot from the Na-Cl-rich end-member groundwaters to the mixed Na-

HCO3-rich groundwaters in Figure 6.24. Groundwaters from Site 2 plot within the mixed Na-HCO3-rich groundwater types showing plausible flux of Na-HCO3-rich groundwaters of magmatic origin (Schofield and Jankowski, 2004) and Site 3 groundwaters plot close to the Na-Cl-rich groundwaters.

6.4 MECHANISMS CONTROLLING SALINITY DISTRIBUTION Salt distribution within the groundwaters and soils contained within the Spicers Creek catchment is variable. Salinity appears to be unrelated to depth, aquifer lithology or the position in the groundwater flow system. This section aims to recognise how geological structures located within the catchment have influenced groundwater flow regimes and salt accumulation. The presence of these structures may force a re-evaluation of previously accepted simple dryland salinity models in New South Wales, Australia.

6.4.1 Seepage zone formation in relation to structural features Using high-resolution magnetics data, the location of main structural features in the Spicers Creek catchment was identified. Figure 6.25 represents the Total Magnetic Image (TMI) that was processed from raw geophysical data and was used to ascertain major lineaments. These were previously unidentified from other geophysical investigations performed in the catchment by Meakin and Morgan, (1999) and Schofield, (1998). Interpretation of this data has lead to the identification of four previously unmapped structures. This high-resolution imagery was used to delineate subtle differences in the magnetic signatures of the bedrock. Previously, several faults had been identified from ground-based magnetic surveys conducted at research sites 1, 2 and 3 during April 2002. This data contained many artefacts and covered only a small area of the catchment.

The most significant magnetic anomaly low identified in the catchment is represented as fault 1 on Figure 6.25. This north-easterly to south-westerly

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Chapter 6: Soil and water categorisation trending structure represents a fault zone with higher permeability than the crystalline bedrock and appears to be an extensive regional structure. The next magnetic low identified is represented as fault 2 on Figure 6.25. This structure is a north-westerly to south-easterly trending fault that forms the extension of a fault that was previously mapped by Meakin and Morgan (1999). The third structural feature identified in Figure 6.25 has a north-westerly to south-easterly trending direction and is represented as fault 3. Finally, the last notable magnetic low is the north-easterly to south-westerly trending fault represented as fault 4.

Figure 6.25 Total Magnetic Intensity (TMI) image with the location of the newly mapped structures in the Spicers Creek catchment. This image has an east to west sun angle illumination applied (data supplied by MIM, 2002).

As indicated on Figure 6.25 there is a close association between structural features and the formation of saline seepage zones in the catchment. This correlation has previously not been recognised remained unidentified. Six seepage

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Chapter 6: Soil and water categorisation zones areas located in close proximity to the geological structure features contain saline groundwaters that have been identified in this study. These seepage zones are shown on Figure 6.25 and are labelled from seepage zone 1 (SZ1) to seepage zone 6 (SZ6). SZ1 is located at a fault intersection between the previously unmapped fault 1 and fault 2 that was identified by Meakin and Morgan (1999). Deep groundwaters contained within the Oakdale Formation at this seepage zone have an average salinity of 6,000 μS/cm at 35 m bgs and seepage zone groundwaters reach a salinity of over 10,000 μS/cm. Deep groundwaters possess a positive hydraulic gradient at this point in the landscape and are discharging through the low permeability fault zone located through this site (Morgan and Jankowski, 2002).

The seepage zone SZ2 is located on the contact fault that divides the Oakdale Formation and Gleneski Formation. This north-westerly trending fault extension has previously been unidentified in the catchment and was first identified from an EM34 survey completed by the author in June 2001. Seepage zone groundwaters reach a salinity of over 12,000 μS/cm and contain a chemical signature that is similar to SZ1 groundwaters. It appears that salt, which is mobilised by groundwater, is accumulating within this high permeability fault zone at SZ1 and SZ2 causing an increase in groundwater salinity.

The seepage zone SZ3 is located on a fault zone that was identified by Meakin and Morgan (1999) and forms the division between the Oakdale Formation to the west and the Gleneski Formation to the east of the catchment. Salinities reach over 20,000 μS/cm at this site in the shallow aquifer, deeper Gleneski Formation groundwaters are fresh in this part of the landscape.

The seepage zone SZ4 is located in the Racecourse Gully catchment and is located in a fault intersection between the previously identified north-westerly to south-easterly trending fault and the previously unidentified fault 1. At this location, groundwaters from the intermediate and deep groundwater system deep are saline with salinities over 14,000 μS/cm at 110 m bgs and a positive hydraulic gradient exists in the Oakdale Formation. Salinity is high throughout the whole

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Chapter 6: Soil and water categorisation profile and increases in the top 20 m. Deep saline groundwaters are discharging at this site through the permeable fault intersection zone that has formed.

The seepage zone SZ5 is also located in the Racecourse Gully catchment and has the highest groundwater salinity in the catchment. This salinity high is associated with deep groundwaters located in the intermediate groundwater system and is located at 65 m bgs with groundwater greater than 21,000 μS/cm. This seepage zone forms on the fault intersection of two previously unidentified faults that are represented as fault 1 and fault 3.

Finally, SZ6 is located on the previously unidentified fault 3, which has salinities that reach over 13,000 μS/cm at 29 m bgs. This bore is located within the intermediate aquifer system.

These six seepage zones indicate a close association between groundwater salinity and structural features in the catchment. They also indicate that groundwater salinity is not depth specific or associated with a particular aquifer lithology. The aquifers of the Spicers Creek catchment are generally low permeability fractured systems where groundwater flow is reliant on fracture connectivity and extent. The presence of fracture zones promotes groundwater flow. Groundwater and salts accumulates in these fracture zones and appear to be discharging at the land surface at these points due to aquifer over-pressurisation or the presence of intact crystalline bedrock where groundwater flow is non- existent. Seepage zone formation is related to permeability within the structural features where groundwater flow may occur. These seepage zone sites contribute large quantities of salt and eroded sediments into the surface water systems.

6.4.2 The location of salt in the groundwater system Due to the un-predictable nature of the salt distribution in the catchment a cross- section running north-south through the Spicers Creek catchment was constructed and is presented in Figure 6.29. It shows the location of saline groundwaters at different depths within the fractured aquifer units.

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Figure 6.26 North to South vertical profile of groundwater salinity for the Spicers Creek catchment.

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Groundwater chemistry together with piezometric data was used to identify flow and solute concentrations of these groundwaters. The most saline groundwaters (>21,000 μS cm-1) are located in bores 96132/1 and 96132/2 and these saline points coincide with fault intersections. Bore 96121 is also located on a fault intersection and groundwater salinity ranges from over 14,000 μS cm-1 at 110 m bgs to over 18,000 μS/cm at 20 m bgs. Deeper groundwaters are experiencing a positive hydraulic gradient at this site, which indicates that the deep groundwaters are under pressure and are discharging through the higher permeability fault zones that were identified from the high-resolution geophysical data (Morgan et al., 2005) and from hyperspectral data image processing of the catchment (Taylor pers com 2004).

It appears from the cross-section that salt is accumulating within these permeable areas purely because they are have increased groundwater flow. Saline groundwaters have concentrated in the permeable fault zone and are discharging through these higher hydraulic conductivity units. Changes in groundwater chemistry in the aquifers are mainly associated with the presence of these geological structural zones. Groundwaters appear to be migrating towards the most permeable areas in the low permeability fractured aquifer system and as the groundwater migrates towards higher permeability zones in the aquifer, Cl- appears to accumulate within these structural zones increasing the groundwater salinity.

6.5 HYDROCHEMISTRY OF SURFACE WATERS Surface water samples from various locations throughout the catchment were collected to assess the hydrogeochemistry of surface waters in the Spicers Creek catchment. Surface water sample SUR1 was collected from the top of the Snake Gully catchment, SUR2 from middle of the Snake Creek, SUR3 from the Spicers Creek near Saxa bridge and SUR4 from Spicers Creek near Gollan (Figure 5.2). Surface water EC sampled during the study period ranged from 3,670 μS cm-1 to 6,055 μS cm-1. Surface water pH is high reaching pH 8.4 and surface waters appear to be slightly reducing ranging from –73 to –54 mV. Water types range 2+ from Mg-Na-Cl to Na-Mg-Cl-HCO3 to Mg-Na-Cl-HCO3, where Mg is the dominant

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Chapter 6: Soil and water categorisation cation and Cl- the dominant anion. Surface waters contain elevated As, B, Ba, Cr and Se concentrations (Table 6.12) indicating the presence of groundwater baseflow components to these surface water systems in the Spicers Creek catchment. These surface water results indicate that Snake Creek surface waters are stagnant and saline. Surface waters in the Spicer Creek are fresh at the top of the catchment and become more saline at Saxa bridge.

Table 6.12 General parameters, major ions, minor ions and trace elements for surface waters in Spicers Creek catchment.

ID EC PH Eh Na K Ca Mg HCO3 SO4 Cl As B Se Sr V SUR1 N/A N/A N/A 982 20 137904 N/A 1213992.8 N/A 299 N/A 4570 N/A SUR2 N/A N/A N/A 699 9 70 443N/A 54.82003.4 N/A 347 N/A 3360 N/A SUR3 6055 8.1 -72.8 772 9 117 295 837 9.7 1959.4 8.2 133.8 24.9 2764 8.7 SUR4 3665 8.4 -54.2 376 9 80 233 879 3.6 999.7 6.8 153.6 12.8 1507 16.8 μS cm-1 mV mg L-1 μg L-1 N/A – not analysed

Data obtained from DLWC data loggers located on the Spicers Creek at Saxa Bridge in the Spicers Creek catchment, recorded the average surface water discharge (ML day-1), surface water EC (μS cm-1) and mean water level (metres) as indicated in Figure 6.32.

Surface water discharge for the Spicers Creek at Saxa Bridge location ranges from 0 to 0.3 ML day-1 with an average discharge rate of ~0.1 ML day-1 for the study period (Figure 6.27a). An increase in surface water discharge corresponds with a large rainfall event experienced in February 2002. A decrease in discharge from November 2002 has occurred due to drought conditions prevailing in the catchment.

The surface water EC ranges from ~3,000 μS cm-1 to ~6,500 μS cm-1 with a mode of ~4,500 μS cm-1 (Figure 6.27b). Surface water EC is related to discharge rate where a decrease in surface water EC is experienced when a peak in discharge occurs. This phenomenon is identified in February 2002, where an increase in discharge leads to a decrease in surface water EC from ~6,500 μS cm-1 to below 3,000 μS cm-1. A steady increase in surface water EC occurred after October 2002 due to the lack of rainfall recharge and hence surface water dilution. 176

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Figure 6.27 Stream data for Spicers Creek and Talbragar River for study period Nov 2001 to Feb 2003 (a) river discharge (ML day-1) versus time (b) river EC (μS cm-1) versus time (b) average river level (m) versus time (c) (www.waterinfo.dlwc.nsw.gov.au).

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The mean surface water level is represented in Figure 6.27c, which ranges from 0 to 27 m. Surface water level is related to discharge and EC where the discharge rate increases, the surface water salinity of the Spicers Creek, decreases. Due to drought conditions experienced in the area during the study period, water levels have decreased and the surface water loggers are not submerged in water, accounting for invalid data from December 2002 to February 2003.

The surface water data presented indicates that the Spicers Creek is reliant on rainfall recharge in the area for surface water flow to occur. The Spicers Creek at Saxa has a low discharge rate and water level and as waters become more stagnant, the surface water salinity increases due to evaporation and due to saline groundwater discharge into the surface water system. Once a rainfall event occurs the surface water is diluted and discharged at 0.3 ML day-1 with an average water salinity of ~3,000 μS cm-1 to the Talbragar River system. This large amount of salt exported from the Spicers Creek represents a huge salinity risk for the Talbragar River and the down stream Macquarie River system.

6.6 HYDROCHEMISTRY OF RAIN WATER Rainwater samples were collected from the Spicers Creek catchment over the study period and the hydrochemistry of the samples were determined. Two rainwater samples were analysed during this period, due to the lack of rainfall throughout the region. Rainfall sample event R1 was collected on 17th September 2002 with 14.8 mm of rainfall recorded. Rainfall sample R2 was collected on the 1st January 2003 with 18 mm of rainfall recorded. The hydrochemical data for rainfall events are summarised in Table 6.13 and the whole data set presented in Appendix A1.

Potassium and Na+ are the dominant cations and Cl- is the dominant anion in rainwater from Spicers Creek catchment. Rainfall event R1 has a much higher TDS (~46 mg L-1) than R2 (~3 mg L-1). The rainfall in the area contains elevated concentrations of Sr2+ and Cu and it contains minor amounts of As, B, Ba, Li+, Rb and Se. The presence of these elements within the rain water samples indicates

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Chapter 6: Soil and water categorisation that a continental aerosol input is most likely the source of these constituents. The basement rocks in the region are high in trace elements such as As and Cu. The presence of trace elements within the rainfall samples indicates that aerosols from the weathered land surface are a plausible source of solutes in rainfall.

Table 6.13 Rainwater chemistry for Spicers Creek catchment.

mg L-1 μg L-1

ID date Na K Ca MgSO4 Cl Br As B Ba Cu Li Rb Se Sr R1 17-Sep-02 9.65 16.51 3.95 1.284.40 10 1.89 14.3011.37 34.10 0.19 10.34 0.49 38.20 R2 1-Jan-03 0.27 0.12 0.19 0.05 0.27 2 0.028 <0.05 1.31 2.89 6.54 0.05 0.12 <0.29 2.28

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CHAPTER 7: HYDROGEOCHEMICAL PROCESSES INFLUENCING DEEP END-MEMBER GROUNDWATERS

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

7.1 INTRODUCTION The geological complexity of the deep fractured aquifer systems and the irregular distribution of salt indicate that groundwater chemistries are not distinctive to each aquifer in the Spicers Creek catchment. The presence of salt in the system appears to be the primary influence on hydrogeochemical processes. From initial hydrogeochemical and isotopic observation, the intermediate and deep groundwater systems, appear to have two distinctive groundwater types. They include the Na(Mg)-Cl-rich and Na-HCO3-rich groundwaters. Other groundwaters appear to represent mixing between these end-member groundwater groups and rainfall recharge to the system. Both groundwater types have a unique geochemical evolution and will be described separately throughout this chapter, using ion relationships, isotopes and inverse modelling. It is important to identify the geochemical processes influencing these end-member groundwaters because the chemical compositions of the deep groundwaters influence the shallow groundwater chemistry within seepage zones.

7.2 DEFINING DEEP END-MEMBER GROUNDWATERS Groundwater chemistry is described in Chapter 6 and two distinctive groundwater chemical types appear to occur in the catchment. They include the Na(Mg)-Cl-rich groundwaters associated with the fractured intermediate and deep aquifer systems, and the Na-HCO3-rich groundwaters located in the north-western section of the catchment. Plots of Na%, Cl%, and HCO3% versus EC are used to graphically display these two end-member groundwater groups.

The percentage of Na+Cl% with respect to total ions in solution increases as groundwater salinity increases and the Na(Mg)-Cl-rich groundwaters can be clearly identified in Figure 7.1. Na(Mg)-Cl-rich groundwaters contain between ~70% to 86% of Na+ and Cl- ions. A plot of Na+HCO3% versus EC indicates that + - Na-HCO3-rich groundwaters contain between 82 to 95% of Na and HCO3 as their total ionic composition (Figure 7.2). The processes influencing these distinctive groundwater groups will be discussed accordingly in the following sections.

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

Figure 7.1 Na+Cl% vs. EC for deep and Figure 7.2 Figure 7.1 Na+HCO3% vs. EC intermediate groundwaters in Spicers for deep and intermediate groundwaters Creek catchment. in Spicers Creek catchment.

7.3 Na(Mg)-Cl-RICH END-MEMBER GROUNDWATERS 7.3.1 Origin of Na(Mg)-Cl-rich groundwaters Isotopic data is useful in confirming the origin of salts, providing hydrogeologic interpretations of a system and assisting the further understanding of the evolution of the groundwater chemistry within a fractured crystalline bedrock aquifer system (Gascoyne and Kamineni, 1993). After rainfall infiltrates the bedrock as recharge, it inherits the geochemical properties of the aquifer but the water retains some of its original characteristics such as its isotopic signature (Nordstrom et al, 1989). These isotopic signatures will be used to assess the origin of Na(Mg)-Cl-rich groundwaters. Variations in δ18O and δ2H isotopic values in groundwaters from deep and intermediate aquifers reflect mixing between Na(Mg)-Cl-rich groundwaters and more depleted Na-HCO3-rich groundwaters.

The relationship between 18O and 2H was identified by plotting δ18O versus δ2H with the updated Global Meteoric Water Line (GMWL δ2H ‰ = 8.13δ18O + 10.8) (Rozanski et al., 1993), based on the isotopic values of precipitation and modified from Craig (1961). The Local Meteoric Water Line (LMWL δ2H ‰ = 9.74δ18O + 16.63) (Schofield, 1998) for Ballimore will also be used herein for comparing stable isotopes of δ18O and δ2H against rainfall. By convention, seawater has a

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters composition close to the 0‰ with respect to both 18O and 2H values and δ values are reported relative to the Vienna Standard Mean Ocean Water (VSMOW) or otherwise know as SMOW.

δ18O and δ2H isotopic values of Na(Mg)-Cl-rich groundwaters range from -5.28‰ to -4.45‰ with an average of -4.96‰. δ2H values range from -36.2‰ to -31.8‰ with an average of –33.06‰. Mixed groundwaters have δ18O values ranging from - 7.51‰ to -4.32‰ with an average of -5.29‰. δ2H values range from -45.3‰ to - 27‰ with an average of -34.26‰. Variations in these values occur due to mixing between depleted Na-HCO3-rich groundwaters and slightly enriched in Na(Mg)-Cl- rich.

δ18O and δ2H values were plotted against the GMWL and LMWL (Figure 7.3). Deviation from the meteoric line is most likely due to fractionation factors that the water has experienced during its passage through the hydrologic cycle (Dansgaard, 1953). Hartley (1981) shows there are two major influences on the isotopic composition of Australian rainfall, which are rainfall intensity and the dew point. During intense storms, the turbulence and cooling reduces fractionation and istopically light rain falls. He found the relationship between dew point to be complex but concluded at a low dew point isotopically light vapours occur and less rain is produced. The observed δ18O and δ2H values in groundwaters reflect precipitation events together with modification of isotopic value due to water-rock interaction where the oxygen isotope shift is considered a result of isotope exchange between oxygen in the water and in aquifer (Faure, 1989; Clark and Fritz, 1997). δ2H is not a major constituent of many rocks (except in the hydroxyl groups of clays and hydroxides) therefore less exchange is likely to occur between the groundwater and aquifer (Appelo and Postma, 1999).

δ18O and δ2H values indicate that groundwaters are depleted relative to SMOW, with most values extrapolating towards the meteoric water lines (Figure 7.3). This trend implies groundwaters are derived from local rainfall (Appelo and Postma, 1999). The isotopic signatures of δ18O and δ2H in Na(Mg)-Cl-rich groundwaters show that due to the relatively depleted nature their signatures the presence of

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters connate marine or hydrothermal fluids is not likely. Connate seawater would result in enriched δ18O and δ2H values close to SMOW and hydrothermal fluids evolved from rock-water interactions at elevated temperatures would have enriched oxygen-18 values in the resultant water (Richter et al., 1993).

Figure 7.3 δ2H vs. δ18O for deep and Figure 7.4 δ18O vs. Cl for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

7.3.2 Evaporation trend in Na(Mg)-Cl-rich groundwaters The importance of evaporation processes influencing the deep groundwaters can be identified from the isotopic compositions of the water (Gat, 1981). Evaporation processes affect the δ18O and δ2H ratios in a water sample. The residual water subjected to evaporation becomes progressively more enriched in the heavier isotopes 18O and 2H. Therefore, salinisation caused by evaporation typically concentrates the heavier isotopes 18O and 2H (Banner et al,. 1989; Richter et al., 1993).

Waters that have been subjected to evaporation prior to recharge may produce δ18O and δ2H values heavier than SMOW and tend to evolve along a line that is shallower than the meteoric waters when evaporation occurs (Gat, 1981). Allison (1982) showed in the laboratory using sand columns, how evaporation from unsaturated soils produces soil moisture compositions with shallow gradients ranging from 2.4 to 4.7 on a plot of δ18O versus δ2H. He also found that

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters evaporation from an open water body or saturated soil results in isotopic compositions with a slope of ~5. Therefore, δ18O and δ2H isotopic evidence can be used in dryland salinity affected environments to identify cyclic patterns of evaporation and determine when evaporation is leading to an increase in solutes in the groundwater system (Salama et al, 1999). Analysing the slope of the data for Na(Mg)-Cl-rich groundwaters will yield information on evaporation processes occurring prior to groundwater recharge (Gat, 1981; Clark and Fritz, 1997).

Regression analysis of δ18O and δ2H data for Na(Mg)-Cl-rich groundwaters indicates they have a slope of –1.85 (Figure 7.3), which implies that these groundwaters have not undergone evaporation prior to recharge. On the other hand, mixed groundwaters have a slope of 5.8. This trend is most likely due to minor evaporation prior to recharge or this signature may reflect palaeoclimatic conditions where groundwaters were recharged under different rainfall regimes (Dansgaard, 1964).

To identify the extent of evaporation the relationship between δ18O and Cl- is assessed, as Cl- concentrations increase in the groundwater sample, an increase in heavy 18O isotope would also be observed (Turner et., 1987). The correlation between δ18O and Cl- is weak (r2=0.410) in Na(Mg)-Cl-rich groundwaters and mixed groundwaters show no correlation (r2=0.001) (Figure 7.4).

Stable isotope data implies Na(Mg)-Cl-rich groundwaters are of meteoric origin and have not undergone evaporation prior to recharge. Therefore, evaporation or dissolution of connate seawater or hydrothermal fluid can be discounted as the primary mechanism leading to the increasing salinity in the Na(Mg)-Cl-rich groundwaters.

7.3.3 Geochemical evolution of Na(Mg)-Cl-rich groundwaters 7.3.3.1 Geochemical evolution of Na(Mg)-Cl-rich groundwaters The geochemical evolution of Na(Mg)-Cl-rich groundwaters were identified using simple bivariate plots and ionic ratio calculations based on methods employed by Sami (1992) and Richter et al. (1993). Ionic ratios of groundwaters were compared

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters to determine the evolution of groundwater chemistry. Chloride is used as a normalising factor because it generally does not enter into precipitation-dissolution processes except at brine concentrations. It also rarely enters into oxidation- reduction or adsorption reactions (Nordstrom et al, 1989).

The relationship between Na+ versus Cl- was examined and Na(Mg)-Cl-rich groundwaters plot on or close to the 1:1 halite dissolution line, with a slight excess of Cl- relative to Na+ (Figure 7.5). As groundwaters evolve or become more saline they move closer to unity, where Na/Cl ratios approach 1 (Figure 7.6). This is the opposite process to that observed by Salama et al. (1993) and Acworth and Jankowski (2001). These authors noted Na/Cl ratios decrease with increasing salinity and used hydrogeochemical evidence to indicate that reverse ion exchange reactions become more pronounced with increasing salinity. Banner et al. (1989) also noted in a deep fractured aquifer system, a Na-Cl brine derived from halite dissolution may become deficient in Na+ relative to Cl-.

Figure 7.5 Na+ vs. Cl- for deep and Figure 7.6 Na/Cl vs. EC for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

The relationship between Mg2+ and Cl- indicates that in mixed groundwaters the concentration of Mg2+ increases relative to Cl-, but in Na(Mg)-Cl-rich groundwaters, a decrease in Mg2+ relative to Cl- is observed indicating as salinity increases, Mg2+ is removed from the Na(Mg)-Cl-rich groundwaters (Figure 7.7). The opposite is true for Ca2+, where an increase in concentration is observed with Cl- increase in

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

Na(Mg)-Cl-rich groundwaters (Figure 7.8). Generally, Ca/Cl ratios move to ~0.5 as Cl- increases indicating the Ca2+ to Cl ratio remains stable as Cl- concentration increase in the Na(Mg)-Cl-rich groundwaters (Figure 7.9). Ca/Mg ratios increase as Cl- concentration increase in Na(Mg)-Cl-rich groundwaters, implying Ca2+ is supplies at a greater rate to Mg2+ or it is removed relative to Ca2+ in the groundwater as salinity increases.

Figure 7.7 Mg2+ vs. Cl- for deep and Figure 7.8 Ca2+ vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

- - - Observations of HCO3 concentrations versus Cl indicate HCO3 appears to slightly increase as Cl- increases (Figure 7.11). Major ions versus Cl- yielded information regarding the behaviour of ions with increasing salinisation. Ion ratios can be used to infer the source of Ca2+ and Mg2+ to the groundwaters.

Ca+Mg/HCO3 ratios increase as the groundwater salinity increases, which imply Mg2+ and Ca2+, are added to Na(Mg)-Cl-rich groundwaters at greater rate than - 2+ 2+ HCO3 . Most potential lithological sources of Ca and Mg have a (Ca+Mg)/HCO3 ratio of ~0.5 (Mahlknecht, et al., 2004). At low salinities the ratios are <0.5, - indicating HCO3 enrichment maybe due to weathering. The ratio increases with 2+ 2+ - salinity, implying Mg and Ca are contributed at a greater rate than HCO3 , as salinity increases (Mahlknecht, et al., 2004). If Mg2+ and Ca2+ concentrations are only from the weathering of carbonates, the Ca+Mg/HCO3 ratios would equal 0.5 (Mahlknecht, et al., 2004).

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

Table 7.1 Ion ratios for deep and intermediate groundwaters in Spicers Creek catchment.

Ion ratios Na(Mg)-Cl-rich Mixed Na-HCO3-rich

Ca+Mg/HCO3 ~1 0.3 to 11 ~0.1

Ca+Mg/SO4 1.6 to 4.5 2 to 500 ~600

Figure 7.9 Ca/Cl vs. Cl- for deep and Figure 7.10 Ca/Mg vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

2- - 2- The relationship between SO4 and Cl shows that SO4 increases with increasing - 2- Cl concentration (Figure 7.12). Consideration of SO4 ratios will identify if halite and gypsum dissolution are the main contributors of salts to the Na(Mg)-Cl-rich groundwaters. According to Richter and Kreiter (1987) molar ratios of

(Ca+Mg)/SO4 and of Na/Cl that are close to unity suggesting halite and gypsum are not the only sources of dissolved constituents to groundwater. Salt water derived from deep-basin brines are characterised by Na/Cl ratios of less that 1,

(Ca+Mg)/SO4 molar ratios greater than 1 and high Mg/Cl, K/Cl, Br/Cl and I/Cl ratios (Richter and Kreitler, 1987; Richter et al., 1993).

Molar ratios of Ca+Mg/SO4 in the Na(Mg)-Cl-rich groundwaters are greater than 1, ranging from 1.6 to 4.5, implying the salinity in these groundwaters is not contributed solely from halite and gypsum dissolution. Sulphate and Ca2+ therefore 2- appear to be contributed from other sources or SO4 maybe decreasing due to + + 2- - reduction processes. Calcium, Na , K and SO4 increase monotonically with Cl

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters concentration. Nordstrom et al, (1989) noted within a fractured rock aquifer, this trend might indicate a single source of salt mixing to various degrees with infiltrating freshwater.

- - 2- - Figure 7.11 HCO3 vs. Cl for deep and Figure 7.12 SO4 vs. Cl for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

+ - - Figure 7.13 K vs. Cl for deep and Figure 7.14 SiO2 vs. Cl for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

7.3.3.2 Chemical reactions influencing Na(Mg)-Cl-rich groundwaters The general behaviour of ions in deep and intermediate groundwaters have been identified for the mixed and Na(Mg)-Cl-rich groundwaters in the Spicers Creek catchment. Hence, for a greater understanding of the geochemical processes

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters occurring in the groundwater system, mineralogical data is presented for the Oakdale Formation aquifer. Na(Mg)-Cl-rich groundwaters evolve from the Oakdale Formation aquifer, which is composed of coarse epiclastic, rocks, lavas and shallow intrusives of felsic to intermediate origin (Ashley, 2001). Average mineral abundances were estimated from thin section and the rocks contain; approximately ~45% plagioclase, 15% K-feldspar, 10% quartz, 10% chlorite, 10% biotite, 5% sericite, 1% carbonate, 1% haematite, with minor epidote and trace minerals. Pyrite was also observed in the Oakdale Formation during drilling (MIM, 2002). The following are a set of chemical reactions representing the dissolution of various minerals, which are present in the Oakdale Formation aquifer;

The incongruent weathering of Na-plagioclase (albite) and/or Ca-plagioclase 2+ + - (anorthite) to kaolinite would produce Ca , Na , HCO3 and silica;

Albite

+ - NaAlSiO3O8(s) + H2CO3 + 9/2H2O → Na + HCO3 + 2H4SiO4 + 1/2Al2Si2O5(OH)4(s) eq 7.1

Anorthite

2+ - CaAl2Si2O8(s) + 2H2CO3 + H2O → Ca + 2HCO3 + Al2Si2O5(OH)4(s) eq 7.2

Plagioclase

4Na0.5Ca0.5Al1.5Si2.5O8(s) + 6H2CO3 + 11H2O → + 2+ - 2Na + 2Ca + 6HCO3 + 4H4SiO4 + 3Al2Si2O5(OH)4(s) eq 7.3

+ - The incongruent dissolution of K-feldspar to kaolinite would produce K , HCO3 and silica;

+ - KAlSi3O8(s) + H2CO3 + 9/2H2O → K + HCO3 + 2H4SiO4 + 1/2Al2Si2O5(OH)4(s) eq 7.4

2+ - The weathering of chlorite to kaolinite would produce Mg , Al, HCO3 , and silica, the precipitation of this mineral would conversely lead to the removal of these ions;

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

+ 2+ 3+ Chlorite Mg5Al2Si3O10(OH)8+16H →5Mg +2Al +3H4SiO4+6H2O eq 7.5

+ 2+ - The incongruent dissolution of biotite to kaolinite would produce K , Mg , HCO3 and silica;

+ + 2+ K[Mg2Fe] [AlSi3]O10(OH)2 + 10H + 0.5 O2 + 7H2O → Al2Si2O5(OH)4 + 2K + 4Mg +

2Fe(OH)3 + 4H4SiO4 eq 7.6

3+ 2- The oxidation of pyrite under various oxidation states may produce Fe , SO4 and H+;

2- + FeS2 + 15/4O2 + 7/2H2) → Fe(OH)3 + 2SO4 + 4H eq 7.7

3+ 3+ 2- + FeS2 + 14Fe + 8H2O → 14Fe + 2SO4 + 16H eq 7.8

The congruent dissolution or precipitations of calcite would produce Ca2+ and 2- CO3 or remove these ions during precipitation;

2+ - CaCO3 → Ca + HCO3 eq 7.9

2+ 2+ 2- The congruent dissolution of dolomite would add Ca , Mg and CO3 ;

2- CaMg(CO3)2 → Ca + Mg + 2CO3 eq 7.9

Carbonates present in silicate or alumino-silicate rocks or soils at levels >1% will tend to dominate the chemistry of the soil or groundwater (Langmuir, 1997). Due to the presence of carbonates in the Oakdale Formation mineralogy, the carbonate system will be explored in further detail.

7.3.4 Carbonate system with respect to Na(Mg)-Cl-rich groundwaters Dissolution and precipitation reactions influence the chemical composition of natural waters and consideration of solubility relations aids in the understanding of the variation in groundwater chemistry (Stumm and Morgan, 1970; Hem, 1989;

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

Plummer et al., 1994). Evans (1982) suggested important control on the hydrochemistry of fractured bedrock groundwaters is related to aquifer dynamics and flushing rates. If flushing rates are low, then dissolution reactions have the ability to approach equilibrium. When flow rates are low, the groundwaters contained within these fractures may become chemically mature due to extensive water-rock interaction processes. Carbonates are likely to become oversaturated in this type of environment.

In studies of the state of saturation of minerals in natural waters and in most geochemical codes, the saturation index (SI) is used. Saturation indices were calculated in PHREEQC 2.4.2 (Parkhurst and Appelo, 1999) and the index is defined as SI = log10 (Q/Keq). When SI is equal to zero, the mineral is considered at equilibrium and if the SI is negative, the mineral is considered undersaturated and will tend to dissolve. When it is positive, the mineral is supersaturated and will tend to precipitate out from solution (Stumm and Morgan, 1970).

Figure 7.15 Calcite vs. dolomite for deep and intermediate groundwaters in Spicers Creek catchment.

The relationship between saturation indices for calcite and dolomite shows most groundwaters are supersaturated with respect to these carbonate minerals and the degree of saturation increases as salinity increases for both calcite and dolomite (Figure 7.15). Dolomite is a very un-reactive mineral at low temperatures and is all most impossible to grow at 25 °C in the laboratory, and dissolves very slowly in

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters solutions that are strongly undersaturated with respect to it (Stumm and Morgan, 1970; Drever, 1988; Drever, 1997). Therefore, dolomite precipitation from these groundwaters is highly unlikely and the precipitation of calcite is more plausible. The presence of calcite in the aquifer has been identified and the likely precipitation of carbonates from Na(Mg)-Cl-rich groundwaters is established. A marine or terrestrial origin of this carbonate contained within the Oakdale Formation can be identified by considering carbon-13 data.

7.3.4.1 Carbon-13 in Na(Mg)-Cl-rich groundwaters The δ13C isotopic signature of a groundwater is governed by the inflow of carbon derived from outside sources and carbon contributed from the aquifer. Sources of carbon include; the dissolution of carbonate minerals such as calcite, aragonite and dolomite, which produce a heavy isotopic signature, the oxidation of organic matter which produces a light carbon isotopic signature together with CO2 gas from the soil zone which also produces a light isotopic signature (Wigley, et al., 1978). Dissolved Inorganic Carbon (DIC) is generally contributed to the 13 groundwater system by the dissolution of CO2 gas in the soil zone where δ CDIC begins with an atmospheric CO2 value of approximately –7‰ VPDB (Calf, 1978).

The evolution of DIC and Photosynthetic uptake of CO2(atm) accompanies the depletion in 13C. When in the aquifer, calcite dissolution and precipitation are 13 important controls on the evolution of DIC and δ CDIC in groundwaters (Salomons and Mook, 1980; Clark and Fritz, 1997).

13 δ CDIC values for Na(Mg)-Cl-rich groundwaters in the Spicers Creek catchment are relatively depleted ranging from –19.5‰ to –13.04‰ with an average of – 15.31‰. Mixed groundwaters range from –16.52‰ to –2.37‰ with an average of –12.56‰. The variance experienced in the mixed groundwaters reflects the mixing 13 of depleted Na(Mg)-Cl-rich groundwaters and more δ CDIC enriched Na-HCO3-rich 13 groundwaters. The δ CDIC values observed in Na(Mg)-Cl-rich groundwaters are indicative of groundwaters that have evolved from a non-marine aquifer system. In a marine carbonate system, heavier δ13C values would be expected with increasing groundwater residence time (Edmunds et al., 2003). The relationship 13 13 between δ CDIC and DIC in Na(Mg)-Cl-rich groundwaters shows δ CDIC values

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters are not related to the influx of DIC into the system (Figure 7.16). As Cl- 13 concentration increases the δ CDIC values become slightly more depleted, implying further depletion occurs as carbonate precipitation occurs from Na(Mg)- Cl-rich groundwaters (Figure 7.17). Therefore, terrestrial sourced carbonate 2+ - precipitates are likely to be influencing the Ca and HCO3 concentrations in Na(Mg)-Cl-rich groundwaters.

13 13 - Figure 7.16 δ CDIC vs. DIC for deep and Figure 7.17 δ CDIC vs. Cl for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

7.3.4 Weathering reactions in Na(Mg)-Cl-rich groundwaters 7.3.4.1 Aluminosilicate weathering As previously identified, the Oakdale Formation aquifer contains many aluminosilicate mineral phases, which are likely to weather and contribute ions. Nordstrom et al. (1989) suggested that within a fractured bedrock aquifer, carbonate and silicate hydrolysis reactions are the primary geochemical reactions that influence the observed groundwater chemistry. Identification of weathering processes contributing ions to the Na(Mg)-Cl-rich groundwaters and the weathering products that may form are assessed in this section.

The chemical weathering of silicate rocks plays a major role in influencing geochemical cycles and the production of CO2 within the environment (Drever 1994). Silicate weathering also plays a major control on continental aqueous

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters chemistry (Smith and Drever, 1976). Weathering of silicate minerals is estimated to contribute 45% of TDS to the worlds rivers (Stumm and Wollast, 1990). Carbonic acid is the most abundant acid in natural waters and is responsible for rock weathering (Stumm and Morgan, 1970). A high silica concentration in groundwaters indicates active degradation of silicate minerals (Stumm and Morgan, 1970; Hem, 1989), which generally occurs in recharge groundwaters that are slightly acidified due to the presence of carbonic acid contributed from atmospheric CO2. These slightly acidic waters have a higher potential to dissolve aluminosilicate minerals.

The weathering of aluminosilicate such as feldspars, biotite and chlorites are most likely contributing to SiO2 concentration observed in Na(Mg)-Cl-rich groundwaters. The total dissolved concentration of silica in groundwaters is normally low due to the slow dissolution kinetics of most silicate minerals (Appelo and Postma, 1999). - - The relationship between SiO2 and Cl shows SiO2 increases with Cl concentration until ~40 mmol L-1 of Cl- then decreases, as Cl- concentration increases, implying SiO2 is removed from the groundwater as salinity increases (Figure 7.18). This may indicate that as hydrogeochemical reactions such as clay mineral transformation occur, these processes may be reducing the silica activity of groundwaters, as their salinity increases. Cartwright et al., (2004) observed in a dryland salinity affected catchment groundwaters were at or near saturation with respect to aqueous silica. They implied the precipitation of amorphous silica might limit silica concentrations in saline groundwaters.

The weathering sequence of minerals in the Oakdale Formation aquifer was assessed according to the Goldrich weathering sequence (Goldrich, 1938). According to studies completed by Lasagna (1984) Ca-plagioclase is the most easily weathered mineral in the Oakdale Formation aquifer systems, the next to weather is Na-plagioclase then biotite and finally K-feldspar. Ca-plagioclase forms at relatively high temperatures and is one of the last minerals to form making it the most unstable and susceptible to weathering processes (Langmuir, 1997). Ca- plagioclase (anorthite) has the capacity to dissolve 700 times faster than Na- plagioclase (albite) and about 4500 times faster than K-feldspar (Lasaga, 1987; Appelo and Postma, 1999). A one mm crystal of anorthite at a pH 5 and

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters temperature of 25°C would last for 112 yrs, whereas albite would survive 80,000 yrs and quartz 34,000,000 yrs (Lasaga, 1984). However, the dissolution of silicates in an aquifer system is much slower than rates predicted from laboratory studies (Paces, 1983; White and Peterson, 1990). Nonetheless, these rates provide a guide for the behaviour of aluminosilicate minerals and how they influence Na(Mg)-Cl-rich groundwaters.

7.3.4.2 Halogen-bearing biotite weathering The presence of halogenated biotite is likely to occur in the Oakdale Formation because the lava that comprises the Oakdale Formation was extruded into a marine environment. Other authors such as Gunn and Richardson (1979) have identified the presence of Cl associated with biotites in Ordovician bedrock units in the Dubbo area. Therefore, the weatherability and stoichiometry of halogen- bearing biotite will be addressed. Gascoyne (2004) suggests that Mg2+, K+, Cl-,

SiO2 can be released to the groundwater from the congruent dissolution of halogenated biotites during low temperature silicate weathering in fractured bedrock environments according to the following formula;

+ 2KMg3AlSiO3O10(Cl)2+10H ⇒ + 2+ - 2K + 6Mg + 3H2O + 4Cl + 4SiO2 + Al2Si2O5(OH)4 eq 7.11

Nordstrom et al. (1989) and Edmunds et al. (1984) also found Cl- associated with micas and chlorite, where the leaching of lattice-bound Cl- increased groundwater salinity. Nordstrom et al. (1989) also found that halides are abundant in fluid inclusions in deep fractured rock aquifers (Nordstrom et al, 1989). Gunn and Richardson (1979) assessed the relative Cl- contents of various weathered and unweathered sedimentary, igneous and metamorphic rocks in the Dubbo area. Gunn (1985) used an electron microprobe to identify that biotite, hornblende, chlorite, feldspars and fluid inclusions in quartz contained chlorine. He found that the loss of chlorine is associated with biotite weathering. Whole rock analysis indicated samples consisted of 0.09% Cl- with the highest Cl- concentration found in andesitic basalts from a quarry near Dubbo (Gunn and Richardson, 1979). They further noted that extensive areas of Palaeozoic rocks, many of marine origin,

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters occur in the south-east of the continent and salt encrustation on Ordovician marine sediments was observed (Gunn and Richardson, 1979).

7.3.4.3 Clay mineral stability Possible weathering processes influencing the Oakdale Formation have been identified. The weathering products that the Na(Mg)-Cl-rich groundwaters are likely to produce from aluminosilicate mineral weathering are now assessed. Although many minerals never reach true thermodynamic equilibrium in a soil or an aquifer, their stability constants provide insights as to their general behaviour and occurrence. Such behaviour is conveniently examined using phase diagrams (Drever, 1988; Langmuir, 1997). Phase diagrams involving clay minerals and related phases provide useful insight to processes such as weathering and clay mineral transformation in the aquifer system.

Clay stability diagrams were constructed for Na+, K+, Mg2+ and Ca2+ systems in Figure 7.18 to Figure 7.21. The principle stable clay mineral phase in Na(Mg)-Cl- rich groundwaters is kaolinite.

Figure 7.18 Stability diagrams at 25°C Figure 7.19 Stability diagrams at 25°C and 1 bar pressure based on Drever and 1 bar pressure based on Drever (1988) for the silicates for Mg2+ deep and (1988) for the silicates for Ca2+ deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

Kaolinitic clay minerals are likely to form where a high water to sediment ratio exists (Velde, 1992). Fault zones within the fractured bedrock system have hydraulic conductivities several orders of magnitude greater than the surrounding parent rock. Hence, higher water to sediment ratios are likely to exist, favouring the formation of kaolinitic weathering products.

Figure 7.20 Stability diagrams at 25°C Figure 7.21 Stability diagrams at 25°C and 1 bar pressure based on Drever and 1 bar pressure based on Drever (1988) for the silicates for Na+ deep and (1988) for the silicates for K+ deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

7.3.5 Reverse Ion exchange in Na(Mg)-Cl-rich groundwaters Ion exchange is the interchange between an ion in solution and another ion in the boundary layer between the solution and a charged surface (Sparks, 2003). This reaction is common on clay minerals. As soil water solutions become more dilute, the equilibrium shifts to favour the adsorption of cations with a higher valence, thus Ca2+ and Mg2+ would tend to replace Na+, whereas Na+ would tend to replace Ca2+ and Mg2+ as soil solutions become more concentrated (Szabolcs, 1989). Ion exchange processes are known to happen in µ seconds and ion exchange is generally governed by the type of clay mineral present (Sparks, 2003).

An excess of Na+ compared to Cl- on a molar basis, indicates a significant source of Na+ (Cerling et al., 1989), which may indicate that ion exchange reactions are occurring. The reverse may also be true where a deficit of Na+ relative to Cl- may indicate reverse ion exchange. As previously, mentioned, Na/Cl ratios approach

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters unity in Na(Mg)-Cl-rich groundwaters but an excess of Cl- exists for mixed groundwaters. The relationship between Ca+ Mg - SO4 - HCO3 against Na-Cl ions can be used to evaluate ion exchange or reverse in exchange reactions (Fischer and Mullican, 1997; Jankowski et al, 1998 a & b, Jankowski and Sekarfaroush, 2000; Timms 2002; McLean 2003). Groundwaters that equal zero are assumed to experience the congruent dissolution of calcite, dolomite and gypsum. In these groundwaters, ion exchange reactions are assumed not to be dominant. Na(Mg)- Cl-rich groundwaters plot close to zero, indicting ion exchange reactions are not dominant in these groundwaters (Figure 7.23). Whereas mixed groundwaters plot in the reverse ion exchange field. A groundwater system dominated by ion exchange reactions will plot along a line that has a slope of approximately –1 (Jankowski and Beck, 2000). Linear regression analysis performed on this data reveals a slope of exactly –1 and a goodness of fit r2 = -0.992, indicating that reverse ion exchange reactions are likely to be influencing the geochemical evolution of mixed groundwaters.

2+ 2+ 2- - Figure 7.22 Ca + Mg - SO4 - HCO3 for deep and intermediate groundwaters in Spicers Creek catchment.

7.3.6 Trace elements in Na(Mg)-Cl-rich groundwaters The relationship between trace elements in the deeper groundwaters gives further insight to salinisation processes influencing the groundwater chemistry. Identification of the background trace element composition of deeper groundwaters helps identify the source of elevated trace elements found in

199

Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters seepage zones located throughout the catchment. Elevated trace elements in deep and intermediate groundwaters are Sr2+, B, Li+, V and As.

Boron is generally found in different geological environments associated with the presence of volcanic rocks, geothermal processes and with minerals associated with saline environments (Leeman and Sisson, 1996). Boron is highly soluble and tends to concentrate in environments that have limited water circulation such as in evaporites of brines (Sanchez-Martos et al. 2002). The source of B is generally associated with the dissolution of the mineral biotite (Edmunds et al., 1984). The weathering of biotite contained in the Oakdale Formation aquifer is the most likely source of B concentrations. Gunn and Richardson (1979) noted an increase in B concentration in weathered marine sediments of the Dubbo region, which corresponded with an increase in Cl- content of these rocks. This association is most likely due to biotite dissolution. Macpherson and Land (1989) and Sanchez- Martos et al. (2002) suggest elevated concentrations of B in connate water should be related to K+, Li+, Mg2+ and Sr2+ concentrations. Boron correlates well with K (r2 =0.64), and Li (r2=0.605) but shows a lack of correlation with Mg (r2=-0.13) and Sr (r2=0.19) in mixed and Na(Mg)-Cl-rich groundwaters. The lack of correlation with Mg2+ and Sr2+ is most likely because these ions are liberated from sources other than biotite dissolution.

The relationship between B against Cl- shows a general increase in B with increasing Cl- concentration (Figure 7.23). A decrease in B is observed in Na(Mg)- Cl-rich groundwaters. A similar decrease in B concentration was observed by Giblin and Dickson (1992). They found that as the groundwater salinity increased the B concentration decreased. This was most likely due to B sorption on clays or incorporation into authigenic clays. Therefore, B is most likely released during biotite weathering and as salinity increases in the fractured aquifer the B is removed by sorption onto the clays from the groundwater.

A similar trend can be observed for Li+, where Li+ increases in concentration with Cl- in mixed groundwaters then decreases in Na(Mg)-Cl-rich groundwaters (Figure 7.24). High Li+ concentrations can also be related to biotite weathering (Richter et al., 1993) and tends to absorb to clay minerals present in the aquifer (Hitchson et

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters al., 1999). Therefore, B and Li+ appear to be related to biotite weathering in mixed groundwaters and in Na(Mg)-Cl-rich groundwaters the concentration decreases due to sorption of these trace elements onto clay minerals present in the fractured aquifer system.

Figure 7.23 B- vs. Cl- for deep and Figure 7.24 Li+- vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

Vanadium is another important trace element in this study because groundwater and surface water concentrations of V around the world rarely exceed more than 10 μg L-1 (Hem, 1989). Therefore, elevated concentrations of V in Na(Mg)-Cl-rich groundwaters (>37 μg L-1) make V an important tracer of bedrock groundwaters in the Spicers Creek catchment. Vanadium is a transition metal that has three oxidation states V3+, V4+ and V5+ and is associated with U in ore deposits. The relationship between V and Cl- indicates that V increases as Cl- increases (Figure 7.25).

Elevated concentrations of As in the groundwaters also make it a useful trace element indicator in this study. Arsenic can be associated with anthropogenic contamination due to the use of pesticides and acid mine drainage or geogenic through mineral dissolution and geothermal discharge (Goldberg, 2002; Thornburg and Sahai, 2004). Reduced iron sulphur containing earth materials such as pyrite are significant sources of As and Se in the environment (Ganje and Rains, 1982; Presser and Swain, 1990; Strawn et al., 2002). Elevated concentrations of As

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters occur as Cl- concentration increases (Figure 7.26). Whole rock assay analysis of the Oakdale Formation unit indicates elevated concentrations of As (>100 mg kg-1) occur within this unit, and are most likely associated with pyrite contained within this unit (MIM, 2002).

Figure 7.25 V- vs. Cl- for deep and Figure 7.26 As- vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

During purging of piezometer 96121/3 located at 100 m bgs in the Oakdale Formation aquifer, black amorphous sulphide-rich precipitate formed instantly from the wellhead indicating the presence of iron and sulphide-rich groundwaters. It appears that Fe, S, As and Se may be mobile in the groundwater and when exposed to oxygen form amorphous FeS precipitates. To assess the hydrogeochemical association of As with other ions, correlation coefficients were - 2 2- 2 2 calculated. These are HCO3 (r =0.672), SO4 (r =0.592), Fe (r =0.622) and Mn (r2=0.611), and all are mildly correlated with As. The observed correlations indicate that As is associated with pyritic sediments within the Oakdale Formation.

7.3.7 The origin of strontium to the Na(Mg)-Cl-rich groundwaters Isotope techniques are particularly effective for identifying the sources of salinity and a combination of isotopic techniques maybe used to determine the age and origin of groundwaters (Banner et al,. 1989; Lyons et al., 1995; Armstrong et al., 1998; Bullen et al., 1996; Grobe et al., 2000; Friedman, 2001; Negrel et al., 2001 and Dogramaci and Herczeg, 2002). This section aims to use radiogenic isotopes

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters of strontium which are extremely useful for identifying the source(s) of strontium and hence the source of salt to the groundwater system.

87Sr/86Sr isotopic ratios of dissolved strontium are maintained in groundwater and are controlled by water-rock interaction and therefore represent the isotopic composition of the strontium bearing minerals contained in the host rock (Faure, 1986); Jorgensen and Banoeng-Yakubo, 2001). 87Sr/86Sr ratios are not significantly altered by the radiogenic decay of 87Rb to 87Sr after deposition (Faure, 1986). Rubidium is concentrated primarily in mica, K-feldspar and clay minerals whereas strontium occurs in plagioclase, feldspar, apatite and carbonate minerals (Faure, 1986). The 87Sr/86Sr isotopic ratios of any Rb-containing minerals will increase with time while that of Rb-free minerals will not (McNutt et al., 1990). 87Sr enrichment occurs from the dissolution of older Rb-bearing rock units (McNutt, 2000). These isotopic ratios are source-dependent and produce information on geochemical processes occurring in the groundwater system. Generally, hydrologically young waters exhibit un-radiogenic strontium ratios and older waters inherit a more radiogenic signature (Collerson et al., 1988).

87Sr/86Sr isotopic ratios range from un-radiogenic in young basaltic volcanic rocks with average ratio values of 0.7040, to radiogenic in older continental crust rocks with average values of 0.7200. Marine carbonates have an average of 0.708 and modern seawater has an average ratio of 0.7090 (Faure, 1986). 87Sr/86Sr isotopic ratios of seawater have varied throughout Phanerozoic time and were measured by Burke et al. (1982). They found that 87Sr/86Sr isotopic ratios of seawater during the Ordovician ranged from 0.7077 to 0.7080. The Silurian period experienced higher strontium ratios ranging from 0.7087 to 0.7088 and during the Permian period, more varied ratios developed ranging from 0.7068 to 0.7080. Hence the 87Sr/86Sr isotopic ratios of seawater are likely to differ because strontium ratios of seawater reflect the mixing of three isotopic sources derived from young un- radiogenic volcanic rocks; radiogenic old continental sialic rocks and marine carbonate rocks (Faure, 1986).

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7.3.7.1 Sources and sinks of strontium A large number of sources and sinks of strontium are present in the groundwaters and aquifer systems of the Spicers Creek catchment. Sources of strontium include aerosols, the dissolution of Sr-rich minerals within the unsaturated zone and saturated zone of the system. Strontium sinks may include the precipitation of strontium-rich minerals, reverse ion exchange reactions and the formation of clay minerals (Shand et al., 1999; Harrington, 1999). Therefore, 87Sr/86Sr isotopic ratio signatures will be used to identify the source of Sr to the system and hence the source of salt.

To help quantify the potential contribution of Sr2+ from an aerosol source, the molar ratio of rainwater for the catchment was examined in relation to Sr2+ concentration. The average Cl- concentration of rainfall for the Spicers Creek -1 2+ catchment during the study period was Clrain = 0.169 mmol L and average Sr -4 -1 concentration was Srrain 4 × 10 mmol L . Using a technique devised by 2+ Harrington (1999), the Sr concentration of rainfall can be calculated (Srcal) within a groundwater sample and compared with the actual Sr2+ concentration found in the groundwater sample (Srgw). Strontium contributed from rainfall can be determined assuming Sr2+ is not involved in any geochemical reactions. Therefore, the Sr2+ concentrations calculated in groundwater will be an overestimation of the actual groundwater result because Sr2+ is not a conservative ion and sources and sinks exist in the aquifer system.

Clgw/Clrain = Srcal/Srrain eq 7.10

Table 7.2 Expected concentration of Sr2+ in groundwater from rainfall.

2+ ID Clgw Srgw Srcal Sr deficit 96132/1 200 0.13 0.47 -0.34 96121/3 130 0.229 0.308 -0.079 96127/2 30 0.04 0.07 -0.03 96133/2 60 0.009 0.142 -0.133

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Figure 7.27 Sr2+ vs. Cl- for deep and Figure 7.28 Sr/Cl- vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

These results indicate that the Sr2+ concentrations observed in the groundwater samples have a deficit of Sr2+ compared with the likely contribution from rainfall. The relationship between Sr2+ versus Cl- and Sr/Cl show Sr2+ concentrations increase with an increase in Cl- concentration (Figure 7.27 and 7.28). The calculated Sr2+ concentrations in groundwaters from rainfall don’t account for the Sr2+ sinks and sources and prove to be oversimplified. 87Sr/86Sr isotopic ratio data provided further indication of water-rock interaction and how it plays a major role in influencing Sr2+ geochemistry in the Na(Mg)-Cl-rich groundwaters.

7.3.7.2 87Sr/86Sr isotopic evidence 87Sr/86Sr isotopic ratios for Na(Mg)-Cl-rich groundwaters range from 0.7054 (96121/3) to 0.7060 (96132/1) with an average of 0.7056. Mixed groundwaters range from 0.7057 (UR1) to 0.7093 (96131/1) with an average of 0.7070. 87Sr/86Sr isotopic ratios are relatively un-radiogenic, which is unusual, considering Gray, (1990) and Cartwright et al. (2002) determined the whole rock 87Sr/86Sr isotope ratios of Ordovician turbidites of the LFB, to have radiogenic signatures that range from 0.7626 to 0.7763. These results are compared with other studies of 87Sr/86Sr isotope ratios in deep fractured rock environments, which indicate radiogenic signatures greater than 0.715 are generally encountered (McNutt et al., 1990; Banner et al 1989).

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Figure 7.29 Sr/Ca vs. Cl- for deep and Figure 7.30 87Sr/86Sr vs. Cl- for deep and intermediate groundwaters in Spicers intermediate groundwaters in Spicers Creek catchment. Creek catchment.

The relationship between 87Sr/86Sr isotopic ratios versus Cl- and Sr2+ shows the evolution of groundwaters from two different lithologies (Figures 7.30 and 7.31). The first occurs due to water-rock interaction, which causes 87Sr/86Sr isotopic ratios to become more radiogenic with increasing Sr2+ and Cl- concentrations. These waters are recharged with a marine signature which is indicative of rainfall and with time, the 87Sr/86Sr isotope ratios increase as alkali feldspars and mica minerals contained with the aquifer became involved in geochemical reactions (McNutt et al. 1990). The second trend is the evolution of Na(Mg)-Cl-rich groundwaters in the Oakdale Formation aquifer. As Cl- and Sr2+ concentrations increase the 87Sr/86Sr isotopic ratios become less radiogenic. The most likely process leading to these values is the addition of non-radiogenic Sr2+ from a non- radiogenic plagioclase source. The relationship between Sr/Ca versus Cl- in Figure 7.29 shows that Sr/Ca ratios increase as Cl- concentration increases.

Whole rock analysis of Canadian Shield pluton units by Franklyn et al. (1991) showed 87Sr/86Sr isotopic ratios values of 0.706-0.717. They then analysed 87Sr/86Sr isotope ratios of individual minerals associated with these rocks and found biotite has radiogenic values ranging from 0.782 to 0.894, plagioclases were low ranging from 0.703 to 0.715 and secondary mineral phases such as epidote, which were present as alteration minerals coating fracture walls, had ratios ranging from 0.7039 to 0.7055 (Franklyn et al. 1991). These results indicate the

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters importance of evaluating the role different mineral phases might have on the observed 87Sr/86Sr isotope signature in groundwaters (McNutt et al., 1990).

87 86 2+ 87 86 13 Figure 7.31 Sr/ Sr vs. Sr for deep and Figure 7.32 Sr/ Sr vs. δ CDIC for deep intermediate groundwaters in Spicers and intermediate groundwaters in Creek catchment. Spicers Creek catchment.

Under low temperature conditions, plagioclase is the first major susceptible phase to react with water, readily losing Sr2+ to the water (Franklyn et al. 1991). The Oakdale Formation rocks hosting the groundwater system is composed of approximately 45% plagioclase. Therefore, the addition of un-radiogenic Sr2+ from the plagioclase phase is most likely leading to the observed un-radiogenic signature found in the Na(Mg)-Cl-rich groundwaters. It appears that 87Sr/86Sr isotope ratios observed in Na(Mg)-Cl-rich groundwaters are dominated by isotopic exchange with plagioclase. Franklyn et al. (1991) also observed this to be the case in the Canadian Shield rocks and McNutt et al. (1990) found plagioclase to be the main source of Sr2+ within groundwaters. They also note that with time the 87Sr/86Sr isotope ratios should increase as biotite weathering occurs because biotite has a high Rb/Sr ratio and dissolution of these minerals leads to a radiogenic input of Sr2+ (McNutt et al., 1990). The evolution of Na(Mg)-Cl-rich groundwaters indicates biotite weathering has a minor influence on the observed 87Sr/86Sr isotope ratio signatures within the present weathering regime.

The observed decreases in radiogenic Sr2+ and the addition of non-radiogenic Sr2+ to the more geochemically evolved Na(Mg)-Cl-rich groundwaters was also

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters observed by Armstrong et al. (1998) where they found the 87Sr/86Sr ratios of the Milk River Aquifer pore waters become less radiogenic with increasing distance from the recharge area. The 87Sr/86Sr ratios of the aquifer units such as the sandstone and shale whole rocks, leachates and feldspars were found to be too radiogenic to account for low 87Sr/86Sr ratios measured in the evolved pore waters (Armstrong et al., 1998).

87 86 13 18 Sr/ Sr isotopic ratios versus δ CDIC and δ O further indicate the evolution of Na(Mg)-Cl-rich groundwaters (Figure 7.32 and 7.33). As 87Sr/86Sr isotopic ratios 13 become less radiogenic δ CDIC values become more depleted and the slight 18 13 enrichment of δ O occurs. Carbon-13 becomes more depleted due to δ CDIC fractionation from calcite precipitation. As plagioclase weathers in the aquifer, Ca2+ - and HCO3 are released into the groundwaters increasing the carbonate saturation indices in the groundwater leading to carbonate precipitation.

87 86 18 87 86 Figure 7.33 Sr/ Sr vs. δ O for deep Figure 7.34 Sr/ Sr vs. 1/Sr for deep and and intermediate groundwaters in intermediate groundwaters in Spicers Spicers Creek catchment. Creek catchment.

A mixing hyperbola was transformed into a straight line by plotting 87Sr/86Sr isotopic ratios against the inverse of Sr2+ concentration to form a hypothetical mixing situation presented in Figure 7.34. Mixing relationship and the proportion of mixing between two end-members can be estimated by plotting strontium ratios versus 1/Sr (Faure, 1986; Armstrong et al., (1998); Dogramaci and Herczeg, 2002). For the purpose of this mixing calculation, the 87Sr/86Sr isotopic ratio for

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters seawater represents the initial ratio at the time of groundwater recharge and is considered the initial value with respect to plagioclase dissolution. The geochemical evolution of Na(Mg)-Cl-rich groundwaters in the Oakdale Formation can be calculated from 87Sr/86Sr isotopic ratios versus 1/Sr plot (Figure_). As groundwaters evolve through the Oakdale Formation aquifer, they inherit a non- radiogenic source of Sr2+ from plagioclase weathering. The 87Sr/86Sr isotopic ratio of groundwater sample 96127/2 appears to be ~25% evolved, 96133/2 is ~ 50%, and 96121/2 is ~95% evolved with respect to sample 96121/3 which is considered to be 100% evolved. 87Sr/86Sr isotopic ratios values reflect the evolution of Na(Mg)-Cl-rich groundwaters in this system.

7.3.8 Mass balance modelling for Na(Mg)-Cl-rich groundwaters Identification of the mineralogy and possible geochemical processes influencing Na(Mg)-Cl-rich groundwaters have been described. Mass balance modelling is now used to assess these processes by treating the evolution of Na(Mg)-Cl-rich groundwaters as an inverse modelling problem. This begins with the observed chemical data for the groundwater system and evaluates hypothetical reaction models within the constraints of the observed data (Plummer et al. 1982). Inverse modelling is useful to validate a hypothetical model developed by observing the groundwater chemistry using ion relationships but this method does not consider

CO2 inputs, ion exchange reactions and additional thermodynamic constraints such as silica, K, pH and mineral phases (Mahlknecht, et al., 2004). Therefore, mass balance calculations, can be used to provide information about the reactions occurring as the Na(Mg)-Cl-rich groundwaters evolve.

Modelling code, NETPATH (Plummer and others 1991, 1994) was used in place of PHREEQC 2.4.2 (Parkhurst and Appelo, 1999). Both codes are capable of performing inverse-modelling calculations (Parkhurst and Appelo, 1999), but for this scenario, NETPATH has two advantages over PHREEQC. The first is that NETPATH provides a thorough treatment of isotopes, including mole balance, isotope fractionation, and carbon-14 dating, whereas PHEERQC has only isotope mole-balance capabilities. NETPATH also provides a completely interactive environment for data entry and model development, whereas PHREEQC (version 2) is primarily a batch-orientated program (Parkhurst and Appelo, 1999). 209

Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters

The objective of this modelling exercise is to find sets of minerals and gases, when reacted in appropriate amounts, to quantitatively account for the differences in composition between solutions (Parkhurst and Appelo, 1999) and hence identification of geochemical processes leading to the evolution of Na(Mg)-Cl-rich groundwaters. The initial solution is taken to be equivalent to sample 96127/2, which was abstracted from the Oakdale Formation aquifer (51 m bgs). The final solution is taken to be equivalent to sample 96121/3 (100 m bgs), which represents the most geochemically evolved groundwater abstracted from the Oakdale Formation aquifer.

7.3.8.1 Model constraints Model constraints are used to indicate the mass of selected phases (minerals and gases) that can enter or leave the aqueous solution (Plummer et al.,1994). The selected constraints for this model scenario include; C, S, Ca, Al, Mg, Na, K, Cl, Si and Fe. Sodium, K, Mg, Ca and Cl were chosen because they are elevated in the Na(Mg)-Cl-rich groundwaters and increase in concentration as the salinity increases. Iron and S were chosen due to the presence of pyritic sediments and Al and Si were chosen to account for silicate weathering and clay mineral transformation.

7.3.8.2 Phases A phase selected in a model indicates any mineral or gas that can leave the aqueous solution along the evolutionary path and the selection of plausible phases is usually based on mineralogical data (Plummer et al. 1982). Phases were chosen based on detailed mineralogical information obtained for the Oakdale Formation and evaluation of hydrogeochemical processes using bivariate plots and isotopic evidence. Phases selected include calcite, dolomite, reverse ion exchange, K-feldspar, chlorite, NaCl, kaolinite, CO2(g), albite, anorthite, pyrite, sylvite, siderite, biotite, plagioclase and haematite. An extensive list of phases was selected due to the complex nature of the aquifer lithology. CO2(g) was included and the carbon-13 signature was set by NETPATH at –25 per mil to represent soil zone CO2(g).

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Rayleigh distillation calculations were calculated in NETPATH using the general case of N non-fractionating inputs and M fractionation outputs (Wigley et al., 1978 and 1979; Plummer et al. 1994). Modelled values are compared with observed values to examine the difference between the fractionating differential problem of isotopic evolution and mass balance results (Plummer et al., 1994). The Mook fractionation factors for the inorganic carbon-13 systems were used (Mook, 1980, 1986).

7.3.8.3 Evaluation of Na(Mg)-Cl-rich groundwater model 8008 models were produced by NETPATH according to the above stated constraints and phases. Of these models, 115 were found to be likely. One model was deemed plausible using Rayleigh distillation calculations (Plummer et al. 1994), together with calculated SI data and bivarite plots to identify the most suitable model showing the evolution of Na(Mg)-Cl-rich groundwaters.

Initial Well : 96127/2 Final Well : 96121/3

Final Initial C 16.0883 18.5476 S 13.1594 2.5325 CA 7.7642 2.7285 AL 0.0019 0.0022 MG 13.6725 8.5011 NA 116.4614 26.9701 K 1.1033 0.3284 CL 134.4702 29.9879 SI 0.0824 0.1803 FE 0.0013 0.0036

CALCITE CA 1.0000 C 1.0000 RS 4.0000 I1 0.0000 I2 0.0000 DOLOMITE CA 1.0000 MG 1.0000 C 2.0000 RS 8.0000 I1 0.0000 I2 0.0000 Mg/Na EX NA 2.0000 MG -1.0000 K-SPAR K 1.0000 AL 1.0000 SI 3.0000 CHLORITE MG 5.0000 AL 2.0000 SI 3.0000 NaCl NA 1.0000 CL 1.0000 KAOLINIT AL 2.0000 SI 2.0000 CO2 GAS C 1.0000 RS 4.0000 I1 -25.0000 I2 100.0000 ALBITE NA 1.0000 AL 1.0000 SI 3.0000 ANORTH CA 1.0000 AL 2.0000 SI 2.0000 PYRITE FE 1.0000 S 2.0000 RS 0.0000 I3 -60.0000 SYLVITE K 1.0000 CL 1.0000 SIDERITE FE 1.0000 C 1.0000 RS 6.0000 BIOTITE AL 1.0000 MG 1.5000 K 1.0000 SI 3.0000 FE 1.5000 RS 3.0000 PLAGAN38 CA 0.3800 NA 0.6200 AL 1.3800 SI 2.6200 HEMATITE FE 2.0000 RS 6.0000

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8008 models checked 115 models found

MODEL 44 CALCITE -2.45921 Mg/Na EX -7.19857 CHLORITE -0.45977 NaCl 103.88849 KAOLINIT -7.12581 ANORTH + 7.49485 PYRITE 5.31344 SYLVITE 0.59379 BIOTITE + 0.18110 HEMATITE -2.79370

Computed Observed Carbon-13 -15.6668 -14.8500 C-14 (% mod) Insufficient data Sulfur-34 -24.2266 Undefined Strontium-87 0.706560 0.705410 Nitrogen-15 0.0000 Undefined

103.9NaCl + 7.5Anorthite + 5.3Pyrite + 0.6Sylvite + 0.2Biotite → 7.2 Na/Mg exchange + 7.2Kaolinte + 2.8 haematite + 2.5Calcite + 0.5Chlorite

Dissolution of halite is the main process influencing the observed Na(Mg)-Cl-rich groundwaters. Anorthite weathering is the next major process to influence cations and anion concentrations in the Na(Mg)-Cl-rich groundwaters. The dissolution of anorthite is approximately 700 times faster than Na-plagioclase (Lasagna, 1984) and is the most likely plagioclase to weather in this system. Potassium is more likely to be contributed from sylvite dissolution than K-felspar because it is last to weather in the system according to the Goldrich (1938) weathering sequence. The dissolution of pyrite is likely due to the presence of pyritic veins throughout the Oakdale Formation (MIM, 2002). Reverse ion exchange reactions identified from Figure 7.23 indicate Na is removed from the groundwater and Mg2+ is liberated as groundwaters evolve to Na(Mg)-Cl-rich groundwaters. The weathering of aluminosilicate minerals to kaolinite was identified from clay stability diagrams where anorthite is releasing Ca2+ and weathering to kaolinite. Haematite is observed in the mineralogy and is the alteration product of pyrite and biotite.

Calcite is supersaturated in Na(Mg)-Cl-rich groundwaters and is likely to be forming as a secondary mineral in the fracture zones. Nordstrom et al. (1989) indicates calcite is a common mineral that coats or precipitates within fractures in

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Chapter 7: Hydrogeochemical processes influencing deep end-member groundwaters bedrock environments. The formation of chlorite is likely in the fault zone because a decline in Mg2+ occurs in the Na(Mg)-Cl-rich groundwaters and chlorite was identified in the Oakdale Formation. Gascoyne (2004) suggests in a deep fractured rock unit, Mg2+ concentration is dependent on the rock type, where Mg concentration is likely to be controlled by equilibrium with alteration products such as clays and chlorite. Chlorite is also a common fracture coating in crystalline basement rock aquifers (Nordstrom et al, 1989).

According to the model 0.2 mmol kg of biotite is weathered and contributed to Na(Mg)-Cl-rich groundwaters, referring to the halogen-bearing biotite equation (eq 7.10), 2K+, 6Mg2+ and 4Cl- ions would be released for every 2 moles of halogenated biotite dissolved. Due to the low weathering rate, only minor Cl would be contributed from this source. Non-radiogenic 87Sr/86Sr isotopic signatures in Na(Mg)-Cl-rich groundwaters also infer the weathering of radiogenic biotite and K- feldspar is minor in this system.

Therefore, the evolution of Na(Mg)-Cl-rich groundwaters in the Oakdale Formation aquifer occurs due to the dissolution of halite and sylvite salts contributing Na+, K+ and Cl-, the weathering of anorthite contributing Ca2+ and non-radiogenic Sr2+ and minor biotite. The weathering of anorthite and biotite produces kaolinitic clay minerals and the dissolution of pyrite produces secondary Fe-oxide minerals such as haematite. The precipitation of calcite and chlorite also occurs within fractures, due to the high water-rock ratios compared with the surrounding crystalline bedrock. These fractures or voids from an environment that is suitable for clay mineral formation, reverse ion exchange and carbonate precipitation.

7.4 Na-HCO3-RICH GROUNDWATERS

The geochemical evolution of Na-HCO3-rich groundwaters in the Ballimore region has been described extensively by Schofield, 1998 and later by Schofield and Jankowski (2003, 2004). Hydrogeochemical processes influencing these groundwaters will be discussed briefly in this section. Na-HCO3-rich groundwaters are located in the north-western section of the Spicers Creek catchment and the mixing of these end-member groundwaters with other groundwaters make them

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significant to this study. Na-HCO3-rich groundwaters are under artesian pressure and have flowed from boreholes for over 100 years in this area (Schofield and Jankowski, 2003).

18 Na-HCO3-rich groundwaters in the Spicers Creek catchment area have δ O isotopic values that are relatively depleted with respect to Na(Mg)-Cl-rich groundwaters and range from –7.59‰ to –7.39‰ with an average of –7.49‰. δ2H values are also depleted with values that range from –47.1‰ to –43.4‰, with an 18 2 average of –45.8‰. On a plot of δ O versus δ H, Na-HCO3-rich groundwaters plot to the left of the MWLs in Figure 7.3. Schofield and Jankowski (2004) suggest that these groundwaters are meteoric in origin and the shift to the left of the MWLs is most likely due to CO2 exsolution or gas exchange and fractionation resulting from incongruent silicate weathering reactions occurring in these groundwaters.

13 δ CDIC isotopic values of Na-HCO3-rich groundwaters range from –5.04‰ to 13 2.3‰, with an average –2.13‰. These groundwaters are more enriched in δ CDIC compared with other groundwaters in the catchment. Na-HCO3-rich groundwaters -1 have elevated concentrations of CO2 greater than 1,000 mg L and calculated

PCO2 concentrations 1000 times higher than atmospheric levels (Schofield and

Jankowski, 2003). Modelling of isotopic data showed that CO2 gas is of mixed 13 mantle origin with a primary δ CDIC of –5.9 ‰ (Schofield, 1998). Cartwright et al.

(2002) also found elevated concentrations of ~2,700 mg L of CO2 in groundwaters in Victoria; these elevated concentrations were also attributed to a recent mantle- derived source located at depth which is still out-gassing.

2+ 2+ 2- - Na-HCO3-rich groundwaters have very low Ca , Mg , SO4 and Cl concentrations and are slightly acidic. They have elevated concentrations of Na+, - + HCO3 and K . Na/Cl ratios range from 6 to 24 indicating that halite dissolution is not the major contributor of Na+ to these groundwaters. The source of elevated Na+ appears to be due to the dissolution of Na-rich silicate minerals associated with syenitic intrusive bodies. All groundwaters plot in the kaolinite fields as indicated in Figure 7.18 to 7.21. Therefore, weathering of these aluminosilicate minerals is likely to produce kaolinite clay minerals.

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- Elevated HCO3 concentrations appear to be due to the dissociation of CO2(g) where carbonic acid is partly consumed by weathering reactions involving silicate - minerals. Carbon is not consumed in this reaction therefore HCO3 results from the transformation of this excess carbon source. A constant supply of CO2(g) is buffering the Na-HCO3-rich groundwaters making them slightly acidic.

+ Trace elements such as B and Li are elevated in Na-HCO3-rich groundwaters and the source of these elements may be tourmaline dissolution (Schofield, 1998). Trace elements such as V, As and Se are all low or below detection limit in Na-

HCO3-rich groundwaters Strontium concentrations are low and non-radiogenic 87Sr/86Sr isotopic signatures are observed which plot within the seawater range (Figure 7.32).

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CHAPTER 8: GEOCHEMICAL PROCESSES INFLUENCING SEEPAGE ZONE DEVELOPMENT

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Chapter 8: Geochemical processes influencing seepage zone development

8.1 INTRODUCTION The deep groundwater chemistry was identified in Chapter 7 and the shallow groundwater chemistry will be discussed herein. This chapter aims to estimate the amount of Cl- contained within the shallow aquifer system and identify the types of solutes contained within this system. δ18O and δ2H isotopes were used to identify if evaporation is influencing solute accumulation in the shallow aquifer. An allochthonous versus autochthonous source of Cl- to the shallow aquifer was assessed and shallow groundwaters were dated and compared with groundwaters contained within the seepage zones.

Various studies in dryland salinity affected catchment throughout Australia have used hydrogeochemical techniques to identify water-sediment processes influencing groundwater chemistry (Salama et al., 1993; Jankowski and Acworth, 1998; Jankowski et al., 1994; Jankowski and Acworth, 1997; Jankowski et al., 1998; Salama et al., 1998; Cartwright et al., 2004). Various salinisation, sodification and waterlogging processes are influencing the overall geochemical and hydrogeochemical processes that are observed in the Spicers Creek catchment seepage zones and these processes influencing the development of a structurally controlled seepage zone are addressed in the final section.

8.2 CHLORIDE BEHAVIOR IN THE SHALLOW AQUIFER 8.2.1 Volume of Cl- in the shallow aquifer Each site contains different soil types, solutes and hence salt loads. The objective of this section is to quantify the amount of Cl- contained within the unconsolidated sediments of the shallow aquifer system. The amount of chloride contained within the shallow aquifer has been estimated using 1:5 soil water extract concentrations of Cl- and relating this average concentration to the volume of the aquifer. The shallow aquifer ranges in thickness throughout the Spicers Creek catchment from 2 to 20 m, with an average of 10 m and the catchment is approximately 500 km2 in - -1 area. Using an average Cl1:5 concentration of 100 mg L in soil solution, the - - amount of Cl stored in the aquifer was calculated. Converting the Cl1:5 concentration of 1:5 soil water extract and considering a dilution factor (× 5), the

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Chapter 8: Geochemical processes influencing seepage zone development amount of Cl- contained within the sediments was calculated at 0.5 kg m-3. The volume of the shallow aquifer in the Spicers Creek catchment is calculated at 5 × 109 m3. Multiplying the volume of the shallow aquifer by the average Cl- weight per volume contained in the shallow aquifer, the catchment contains approximately 2.5 million tonnes of Cl-.

Calculations of Cl- loads contained in the three experimental sites shows that Site 1 has approximately 1,435 tonnes of Cl- stored in the regolith, Site 2 has approximately 2,400 tonnes and Site 3 has over 4,320 tonnes of Cl- stored within the shallow aquifer (Table 8.1). These results show that Site 3 has over double the Cl- load of Site 1, which contains almost double the load of Site 2. Therefore, soils at the top of the Snake Gully catchment have a higher Cl- load, which pose a potential problem when considering salt mobilisation and release of Cl- to the lower parts of the catchment.

Table 8.1 Chloride loads in the shallow aquifer in the Spicers Creek catchment.

Cl- (mg L-1)Cl- (kg m3) Volume (m3)Cl- tonnes Site 1 82 0.41 3500000 1435 Site 2 48 0.24 10000000 2400 Site 3 176 0.88 9000000 7920

8.2.2 Solute composition of the soils Soils affected by salinity in the Spicers Creek catchment have a strong dominance of Cl-. Naidu et al. (1995) shows this is common in Australian soils where a strong linear relationship between Cl1:5 and EC1:5 occurs in soil solutions. This indicates that much of the salinity is due to the abundance of Cl- contributed from NaCl dissolution. Na1:5/Cl1:5 ratios of the water-soluble constituents of soils show that soils not affected by salinisation have a ratio of ~5 and as soil EC1:5 increase these ratios reach unity, implying NaCl dissolution becomes dominant in salinised soils (Figure 8.1). Soils in areas not badly affected by salinisation in Sites 1 and 2 have an excess of Na1:5 indicating aluminosilicate weathering or ion exchange reactions are influencing soil chemistry (Drever and Smith, 1978). Most soils from Site 3 plot

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Chapter 8: Geochemical processes influencing seepage zone development on the 1:1 line implying halite dissolution is contributing to elevated salt loads experienced in this part of the catchment.

Ca/Mg ratios also decrease from ~4 to 0.1 as Cl1:5 concentrations increase. As soils become more saline, Mg1:5 become more dominant in the soil solution (Figure 8.2). Downes (1954) shows that if a soil becomes saline due to the addition of sea salt it develops a dominantly Na-Mg-clay complex and soils in the B-horizon inherit a low ratio of exchangeable Ca1:5 to Mg1:5. The presence of Na-Mg systems in saline soils may lead to a lower hydraulic conductivity than experienced in a Na- Ca system, which may influence the waterlogging regimes of soils in the catchment (Sumner, 1995).

Figure 8.1 Na/Cl molar ratio vs. EC1:5 for Figure 8.2 Ca/Mg molar ratio vs. Cl1:5 for 1:5 soil water extracts for soils in 1:5 soil water extracts for soils in Spicers Creek catchment. Spicers Creek catchment

8.2.3 Elucidating the source of salinity 8.2.3.1 Oxygen-18 and deuterium Oxygen and deuterium stable isotopes are used in this section to identify the source of salinity and provide evidence that evaporation is not a major process influencing solute concentration in the shallow aquifer. δ18O values in the shallow aquifer range from –4.42‰ to –6.21‰ with an average of –4.90‰. δ2H values range from –26.2‰ to –39.2‰ with an average of –30.50‰. Most shallow groundwaters plot on or close to the MWLs indicating shallow groundwaters are

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Chapter 8: Geochemical processes influencing seepage zone development meteoric in origin (Figure 8.3). Groundwaters are depleted in δ18O and δ2H relative to SMOW indicating salinity is not from a connate marine origin (Payne, 1988;. Sami, 1992).

Groundwaters from Site 1 are varied in isotopic composition and site-specific processes are likely to influence these groundwaters. Groundwaters from Site 2 plot on the LMWL and are more enriched in δ18O and δ2H, possibly indicating groundwaters that have been recharged from summer rainfall events which are more enriched in δ18O and δ2H relative to winter rainfall (Hartley, 1981). These groundwaters appear to have been recharged at the same time due to due to their similar isotopic composition. Groundwaters from Site 3 are slightly less enriched in δ18O and δ2H, with a similar signature for all groundwaters, indicating comparable recharge events, whereas groundwaters from across Snake Gully plot on the LMWL and are varied in the degree of δ18O and δ2H depletion indicating different recharge events (Dansgaard, 1964).

Regression fit equations were calculated for the three research sites to determine whether evaporation is a major mechanism influencing solute concentration in the seepage zones (Payne, 1988). Data indicates that groundwaters from Site 1 have a slope of ~5.1, Site 2 groundwaters have a slope of 16.22 and Site 3 groundwaters have a slope of 40.4. Groundwaters from Snake Gully have a slope 3.4. Groundwaters experiencing evaporation are likely to plot on a line that has a gradient of between ~4 to 6 on a graph of δ18O versus δ2H (Alison, 1982). The Snake Gully catchment fall within these ranges indicating evaporation may be occurring prior to recharge. These results are consistent with those experienced in semi-arid environments where minor evaporation may occur as rainfall waters encounter a hot dry landscape and minor evaporation is likely (Clarke and Fritz, 1997). However, examination of the relationship between δ18O and δ2H may aid in determining the extent and intensity of evaporation that these groundwaters are experiencing.

A plot of δ18O versus Cl for shallow groundwaters indicates these variables are not well correlated (r2=0.063) implying evaporation is not leading to the enrichment of

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18O relative to Cl- concentration in the groundwater (Figure 8.4). Therefore, evaporation does not seem to play a major role in Cl- accumulation in the shallow groundwaters. These results are consistent with other studies in dryland salinity affected catchments where authors found salinity was not due to evaporation because δ18O and δ2H are not enriched and not positively correlated with Cl- (Turner et al., 1992; Jankowski et al, 1998a and Jankowski and Shekaroroush, 2000;). These results indicate that groundwaters from these sites are not primarily influenced by evaporation hence solute concentration is not due to evaporation.

Figure 8.3 δ2H vs. δ18O for shallow Figure 8.4 δ18O vs. Cl for shallow groundwaters in Spicers Creek groundwaters in Spicers Creek catchment. catchment.

8.2.3.2 Carbon-13 Carbon-13 values for shallow groundwaters in the Spicers Creek catchment range from –16.5‰ to –9.4‰, with an average of –13.2‰ (Figure 8.5). The δ13C of soil

CO2 in most C3 landscapes would evolve to –23‰ and in C4 environments – 13 12.5‰ (Clark and Fritz, 1997). δ CDIC signatures of the shallow groundwaters are consistent with soil zone values for terrestrial vegetation, which uses a Hatch-

Slack or C4 photosynthetic cycle (Deines, 1980 and Salomons and Mook, 1980). Photosynthesis enriches the 12C isotope, depending on the biochemical pathway used for depletion. Vegetation that uses the C4 photosynthesis pathway includes native vegetation such as eucalypts, wattles and low land grasses (Cartwright et al., 2004). Therefore, these values reflect carbon-13 values derived from original

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land use scenarios where soil CO2 is derived from C4 pathway plant respiration and carbon is not contributed from marine sources.

13 Figure 8.5 δ CDIC vs. DIC for shallow groundwaters in Spicers Creek catchment.

8.2.4 Allochthonous versus autochthonous source(s) of Cl Chloride and Br- concentrations in groundwaters are used as tracers for the origin of salts and likely evolution of shallow groundwaters (Murphy et al., 1996; Edmund and Smedley, 2000;). Bromide generally behaves conservatively and may be used to constrain the source of Cl- (Edmunds et al., 2003). A large portion of Cl- and Br- in potable groundwater originates from atmospherically transported material. Bromide has similar characteristics to Cl- but it is more soluble than Cl-, and the natural abundances of Cl- are generally 40 to 8000 times greater than Br- (Davis et al., 1998, 2001).

Cl/Br ratios of halite (NaCl) deposits are elevated (McCaffrey et al., 1987). During evaporation, Cl- and Br concentrations increase until halite saturation is reached. Once halite begins to precipitate, Br- is excluded from the crystalline lattice of NaCl (Braitsch, 1971 and Salama et al, 1999) Therefore, halite dissolution will lead to elevated ratios of Cl-, imparting Cl/Br mass ratios on the resultant groundwater ranging from 1,000 to 10,000 (Davis et al., 1998). Connate waters generally range from 10 to 100, oilfield waters 200 to 400 and seawater ranges from 300 to 600 with an average value of ~290.

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Figure 8.6 Cl/Br mass ratios vs. Cl- for shallow groundwaters in Spicers Creek catchment.

The relationship between Cl/Br mass ratios and Cl- for shallow groundwaters in the Spicers Creek catchment indicate that Cl/Br ratios range from ~65 in rainfall to ~330 with an average of ~297 (Figure 8.6). Ratios are elevated relative to rainfall indicating Cl- is contributed to the groundwater after recharge infiltration. Cartwright et al. (2004) indicates Cl/Br ratios of groundwaters in the Murray Darling Basin (MDB) are generally elevated due to a small degree of halite dissolution during recharge. The Cl/Br ratios indicate the dissolution of halite deposit in the shallow aquifer does not appear to be the main source of Cl- to the groundwater because ratios are not >1000, although a certain amount of Cl- is added once groundwaters have entered the shallow aquifer because Cl- is elevated relative to Br- concentrations to those found in rainfall.

Cl/Br ratios also show that it is unlikely that Cl- is contributed from the dissolution of aeolian derived salts to the Spicers Creek catchment area as suggested by Smithson (2002). The salt entrained in parna would have halite crystals associated with them that have been deflated from playa lake systems, which have undergone evaporative concentration. During halite crystallisation the Br- is excluded from the halite crystal lattice, therefore these entrained salts would have Cl/Br ratios >1000.

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8.2.5 Recharge rate estimation The chloride mass balance (CMB) is a technique that uses meteoric Cl- input as a conservative tracer for distinguishing downward soil-water flux in an aquifer system (Murphy et al., 1996). This method can be valuable for estimating long term averages of recharge in arid climates (Murphy et al., 1996; Wood, 1999). The CMB technique can only be used as an estimate because the conditions for successful application according to Mahlknecht, et al. (2004) is that Cl- is only contributed from the atmosphere, Cl- is conservative, unsaturated zone and saturated zone flow can be approximated by one dimensional piston flow and surface runoff is neglected. The CMB technique is used as a guide to rainfall recharge in this study because there appears to be a source of Cl- that is not attributed to accession. The CMB is calculated using the following formula;

R = P Ceff eq 8.1

Cgw

Where the average yearly precipitation for the area (P), the effective Cl- - concentration of rainfall (Ceff) and Cl concentration of groundwater (Cgw) must be known to estimate recharge flux (R) to the aquifer. Spicers Creek catchment has an average rainfall of 535 mm yr-1 and the average concentration of Cl- in rainfall is 6 mg L-. A groundwater sample was chosen that was obtained from the shallow aquifer that has a known downward hydraulic gradient, piston groundwater flow occurs and the profile is not influenced by seepage zone development. This sample has a Cl- concentration of ~680 mg L-1. Rainfall recharge using the CMB approach was calculated at 4.6 mm yr-1. This result seems likely when considering Harrington (1999) calculated between 0.1 to 2 mm yr-1, recharge to an arid groundwater system in Australia using this technique and was able to verify this result using isotopic evidence.

Cl/Br ratios can be used as a guide to identify whether Cl- is contributed solely from aerosol sources to the groundwater system (Murphy et al., 1996). Cl/Br ratios in shallow groundwaters show an excess of Cl- relative to Br- with regards to rainfall. Therefore, this CMB estimation can only be used as a guide to delineate

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Chapter 8: Geochemical processes influencing seepage zone development rainfall recharge because Cl- is contributed to the system from sources other than rainfall.

8.2.6 Chloride accession from rainfall Gunn and Flemming (1984) and Evans (1994) showed the importance of calculating regional salt balances and accession rates from rainfall to a catchment. Chloride accession from rainfall into the shallow aquifer was calculated considering the rainfall input to the catchment then relating this to the observed Cl- concentration in modern rainfall. The shallow aquifer is approximately 500 km2 with an average thickness of ~10 m. Recharge to the aquifer (R) was estimated using the CMB technique where a value of ~5 mm yr-1 is considered. Hence, rainfall recharge input to the catchment can be calculated using the following formula;

R (m yr-1) × A (m2) = I (m3 yr-1) eq 8.2

Considering the aquifer has an area of 500 km2, the volume of water to the catchment (I) was calculated at 2.5 × 106 m3 yr-1.

Chloride input to the catchment from rainfall was considered using the average Cl- concentration of rainfall (6 mg L-1) multiplied by the volume of water contained within the system (I). Considering this relationship approximately 0.006 kg m3 of Cl- is contributed from rainfall input per year. Hence, an estimated 15 tonnes of Cl- from rainfall would be contributed to the catchment per year. Dividing the volume of the shallow aquifer by the amount of Cl- stored in the catchment a rainfall accession rate of 30 kg ha-1 yr-1 was calculated for the Spicers Creek catchment. This result was compared with other Cl- accession calculations for western NSW (30 kg ha-1 yr-1) (Evans, 1994) and in Central Australia ~1 kg ha-1 yr- (Gunn and Flemming, 1984) and appear to agree with results calculated for the Spicers Creek catchment.

Assuming an estimated 2.5 million tonnes of Cl- is contained within the shallow aquifer, it would take well over 1,000,000 years of continuous accession of Cl- at a

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Chapter 8: Geochemical processes influencing seepage zone development constant rate for the observed Cl- load to accumulate in the Spicers Creek catchment.

8.2.7 Chloride transport in the shallow aquifer The amount of Cl- contained within the catchment and Cl- accession rates to the catchment have been calculated, now the transport of Cl- through and out of the system is addressed. Chloride transport throughout the catchment was determined assuming Cl- is a conservative parameter and calculated considering the linear velocity of groundwater in the aquifer, using the following equation (Fetter, 1994);

Vx = K(dh/dl) eq 8.3

- Where Vx is the average linear velocity that the conservative Cl will travel, K is the hydraulic conductivity, dh/dl is the hydraulic gradient across the area and ne is the effective porosity of the aquifer, which an estimate of is 10%. Hydraulic conductivity was calculated from previous studies in the catchment and was calculated at between 0.002 to 0.5 m day-1 (Mahamed, 1999b). An average value of 0.1 m day-1 will be used in this calculation and dh/dh estimates are provided in Table 8.2. Average linear velocities range from 0.02 to 0.09 m day-1 at the sites and therefore Cl- is likely to travel from ~2.2 to ~7 m yr-1 in the shallow aquifer at the three experimental sites.

Table 8.2 Average linear velocities of Cl- and approximate travel times for shallow groundwaters at each site, in the Spicers Creek catchment.

-1 -1 length (m) dh/dl Vx m day Vx m year travel time (yrs) Site 1 750 0.019 0.02 7.0 100 Site 2 1000 0.027 0.027 10.0 100 Site 3 1000 0.006 0.006 2.2 450

A Cl- is likely to travel 7 m yr-1 within the aquifer at Site 1, whereas a Cl- would travel 10 m in one year at Site 2 and 2.2 m in one year at Site 3. These values are indicative of the type of sediments present at each site. Site 2 has sandy sediments and Site 3 is clay-rich (Appendix A). Therefore, Cl- at Site 2 will flow

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Chapter 8: Geochemical processes influencing seepage zone development approximately 4.5 times faster than Cl- at Site 3, indicating Site 3 has a far greater capacity for Cl- accumulation than the other two sites, which is likely to explain the higher Cl- load contained at this site.

8.3 AGE OF SHALLOW GROUNDWATERS 8.3.1 Groundwater residence time

An estimation of the mean groundwater residence time for the shallow aquifer (tres) can be made assuming a steady state system, and can be calculated using the following formula (Harrington, 1999);

Tres = ne × V eq 8.4

Ravg

Where ne is the aquifer porosity, V is the total volume of water contained in the 3 aquifer (L ) and Ravg is the average groundwater recharge rate to the aquifer (L3/T). The average groundwater recharge is calculated by multiplying the amount recharge (5 mm yr-1) by the volume of the aquifer (5 × 109 m3), which yielded a value of 2.5 × 107 m3 yr-1. Using the above equation and assuming an aquifer porosity of 0.1, the average groundwater residence time calculated was ~20 years. This age is similar to CFC dating results which found shallow groundwaters in the catchment to be ~36 years old (Mahamed, 1999b). Hence, these simple calculations indicate the ages of groundwaters contained in the shallow aquifer are recent, generally less than 100 years old.

8.3.2 Age of groundwaters in the seepage zones 8.3.2.1 Carbon-14 dating Groundwaters in the shallow aquifer have been identified as recent <100 years. Three groundwater samples were collected from the shallow aquifer from seepage zones at Sites 1 and 2, to approximate the ages of these groundwaters. Carbon- 14 values are used as a comparative guide and are interpreted uncorrected. The Conventional Radiocarbon Age (CRA) of these samples were defined by Stuvier and Polach (1997) and are a measure of the amount of radiocarbon in the sample

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Chapter 8: Geochemical processes influencing seepage zone development and the approximate ‘true age’ of the sample (refer to Appendix A for methodology details).

A sample from piezometer S2c was obtained from approximately 12 m in depth. This sample was obtained from the top of the saline discharge zone and contained + + 57.25 /- 0.27 percent modern carbon (pMC) with an estimated age of 4,428 /- 40 years Bp Radiocarbon Age (RCA). Further down the transect a sample was obtained from piezometer S1c which is approximately 10.4 m bgs. This sample is + located within the seepage zone and contained 89.89 /- 0.2 pMC and has an + estimated age of 897 /- 40 Bp. Considering the average linear velocity calculation at this site, groundwaters should theoretically be between 35 to 70 years old. These results indicate that seepage zone groundwaters are older than previously envisaged and may indicate the mixing of older 14C sources within the seepage zones.

Seepage zone groundwaters obtained from Site 2, from piezometer S7b, located + at 10 m bgs show a similar trend. This sample contained 74.04 /- 0.35 pMC and was dated at approximately 2,363 years Bp. These results imply that groundwaters from the seepage zones are far older than previously expected where seepage zone affected groundwaters are dated at between 900 to 4,500 years old.

8.3.3 Summary of Cl- data Evaluating the presented data, the shallow aquifer contains approximately 2.5 million tonnes of Cl- within the top 10 m of the soil profile. The ionic composition of soils show they are mostly composed primarily of Na+ and Cl-. Groundwaters are meteoric in origin and various isotopic compositions reflect different rainfall recharge events in the catchment. Evaporation is not the major mechanism leading to the accumulation of solutes in the landscape. Carbon-13 data values are representative of soil CO2 that has evolved via C4 photosynthetic pathway and native vegetation such as eucalypts, wattles and low land grasses use this pathway (Cartwright et al., 2004). Chloride appears to be contributed from sources other than rainfall because Cl/Br ratios increase after rainfall recharge. Cl/Br ratios also indicate that aeolian salt are 228

Chapter 8: Geochemical processes influencing seepage zone development not responsible for the observed Cl- concentrations in the catchment. Using the CMB techniques a recharge rate of ~5 mm yr-1 and a rainfall accession rate of 30 kg ha-1 yr-1 was calculated for the Spicers Creek catchment. Chloride is likely to travel 2 to 10 m y-1 in the shallow aquifer system and average groundwater residence time in the shallow aquifer was calculated at 20 years, which is confirmed with CFC dating where groundwaters are dated at 36 years old (Mahamed, 1999b). Hence, carbon-14 dating found that groundwaters from the seepage zones at Sites 1 and 2 are much older than groundwaters not influenced by seepage zone formation. Seepage zone groundwaters range from 900 to 4,500 years old implying that in these seepage zones older groundwaters are mixing with rainfall recharge in the seepage zones. Therefore, the mixing of deeper Na(Mg)- Cl-rich groundwaters is assessed for Site 1 in the following section.

8.4 STRUCTURALLY CONTROLLED SEEPAGE ZONE 8.4.1 Seepage zone at Site 1 The formation of a seepage zone at Site 1 will be used as an example of possible hydrogeochemical processes that are likely to occur within a structurally controlled seepage zone in the Spicers Creek catchment (refer to Figure 5.2 for the site location). This site was chosen as a representative site due to presence of a regionally extensive geological structure that runs through the site and presence of salinisation features such as waterlogging, salt encrustation and gullying. High- resolution magnetics data, ground-based geophysical investigations and seismic investigations identified the presence of a cross-cutting fault zone where the Oakdale Formation and Gleneski Formation are contact faulted against each other (Morgan et al., in press). The correlation between this fault zone and the presence of groundwater seepage zones forming adjacent to this structure have been identified and the geochemical processes influencing this seepage zone are now explored.

Groundwaters range from Mg-Na-Cl-HCO3-rich at the crest of the slope

(piezometer S3) to Mg(Na)-Cl-HCO3-rich at mid slope (S2) to Na-Mg-Cl-rich at the bottom of the slope (S1) where a dryland salinity seepage zone has formed (Figure 8.7). The electrical conductivity values increase from 2,900 μS/cm to over

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10,500 μS/cm within a 500 m transect. Closer inspection of the mechanisms influencing this distinctive change in chemistry was undertaken. Nested piezometers were installed at various positions along the transect to analyse the soil and groundwater chemistry.

8.4.2 Chloride balance of Site 1 A Cl- balance was undertaken at Site 1 to quantify the amount of salt entering the catchment from rainfall accession and then compare this value with the observed Cl- load contained within the soils. Using equation 8.2, approximately 7,500 m3 of rainfall recharge is added to Site 1 per year. Considering rainfall input, it is calculated that ~45 kg of Cl- is likely to be contributed to Site 1 from rainfall per year.

Over 1,430 tonnes of Cl- is contained within the shallow aquifer at Site 1 (Table 8.1) therefore it would take ~32,000 years for the observed Cl- load to accumulate from rainfall at Site 1 (considering no Cl- output). Chloride is likely to move at ~7 m yr-1 across the site, hence another source of Cl- is obviously contributing to the observed Cl- load in the seepage zone. The age of seepage zone groundwaters were dated using carbon-14 dating techniques and groundwaters in the seepage zone range from 900 to 4,430 years old. Based on this simple Cl- balance, rainfall accession and accumulation of this Cl- in the lower slope, is not the major process leading to a saline groundwater seepage zone forming at Site 1.

8.4.3 A comparison of Na(Mg)-Cl-rich and seepage zone groundwaters 8.4.3.1 Vertical distribution of δ18O

The vertical distribution of δ18O in the seepage zone at Site 1 highlights the presence of groundwaters that have varied δ18O values with depth (Figure 8.8). δ18O and δ2H isotopic compositions are chemically conservative in an aquifer when temperatures are below 80 °C (Issar and Gat, 1981).

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Figure 8. 7 Hydrochemical profile of Site 1.

231 Chapter 8: Geochemical processes influencing seepage zone development

Therefore, concentrations of these isotopes are not likely to be affected by geochemical reactions within the aquifer (Hoefs, 1997) and the groundwater will preserve its isotopic signature reflecting its history prior to recharge (Mahlknecht, et al., 2004). Using this information, the δ18O isotopic composition of groundwaters in the seepage zone can be used to identify the occurrence of mixing between different groundwater types in the seepage zone.

Figure 8.8 Depth vs. δ18O for Figure 8.9 Depth vs. Cl- for groundwaters from Site 1. groundwaters from Site 1.

Groundwaters at the crest of the slope are more depleted than in the mid and lower slope. They are also more variable and show different recharge regimes, where recharge waters are more enriched at ~5.5 m bgs than isotopic signatures found at depth. δ18O and δ2H values of groundwaters at the crest, which are located between 10 m to 12 m bgs, most likely represent isotopic signatures of larger rainfall events that are more depleted than the rainfall events that recharge the groundwaters at 5 m bgs (Dansgaard, 1964). Lower slope groundwaters have a similar δ18O signature to the deeper Na(Mg)-Cl-rich groundwaters and have a relatively constant δ18O value throughout the whole profile. This result implies that deeper Na(Mg)-Cl-rich groundwaters are influencing the isotopic signature of the lower slope groundwaters. If these groundwaters at the lower slope were purely rainfall recharge groundwaters, they would have signatures that are similar to those of the crest of the slope. Instead, over 1 per mille difference in δ18O is experienced at depth.

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8.4.3.2 Vertical distribution of Cl- The vertical distribution of Cl- in groundwaters at Site 1 gives an indication of where the salt is located in the soil profile (Figure 8.9). Even though there is a lack of groundwater data in the vertical dimension, this data can be used as a comparative guide for identifying Cl- trends with depth. Groundwater data was compared with 1:5 soil water extract data collected at ~1 m interval of each profile (section 6.4) and a close correlation exists between Cl- loads in soils and groundwaters. Groundwaters located at the crest of the slope show a general Cl- bulge at ~10 m bgs and then decrease in Cl- at depth. This profile is a typical Cl- profile as described by Allison and Hughes (1983), where a Cl- peak corresponds with the maximum depth of abstraction by plant roots and Cl- input is mostly from Cl- accession and Cl- is mobilised downwards during rainfall recharge. Chloride distribution in groundwaters of the lower slope show elevated concentrations in the top 1 m, which are most likely due to evaporative concentration at the surface during drier periods. Chloride concentrations then decrease with depth and further increase at ~10 m bgs. Using this data together with δ18O signatures of the lower slope profile, it appears that an increase in Cl- may be associated with deeper Na(Mg)-Cl-rich groundwaters.

8.4.4 Hydrochemical evolution of seepage zone groundwater 8.4.4.1 Relationship between major ions in groundwater The trend of major ions versus Cl- at Site 1 show that generally ions increase in a linear manner compared with Cl- concentration in most groundwaters from the crest to the mid slope (Figure 8.10 to 8.17) However, groundwaters from the lower slope do not follow these same trends and will be discussed accordingly. Groundwaters have a slight excess of Cl- relative to Na+ (Figure 8.10). Salama et al. (1993) suggest that the chemical accumulation in a groundwater system by rainfall solutes generally produces an excess of Cl- relative to other ions in the groundwaters. This is because Cl- production does not occur during weathering processes and Na+ is removed from the system due to other processes such as ion exchange reactions as the groundwater flows through an aquifer system. Chloride is leached very rapidly into groundwaters in arid to semi-arid environments (Drever and Smith, 1978). Therefore, the observed general increase

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Chapter 8: Geochemical processes influencing seepage zone development in ions in groundwaters at the crest of the slope can be attributed to Cl- accumulation from rainfall accession where salts are recharged and concentrate in groundwaters as they move through the aquifer. This trend is not apparent in the lower slope groundwaters where mixing between deep Na(Mg)-Cl-rich and rainfall groundwater is hypothesised. Hence, a Na(Mg)-Cl-rich representative end- member groundwater is compared with the observed groundwater chemistry of Site 1 to identify chemical trends apparent during their hydrochemical evolution.

Figure 8.10 Na+ vs. Cl- for groundwaters Figure 8.11 Na/Cl vs. EC for from Site 1. groundwaters from Site 1.

Na/Cl ratios in groundwaters are mostly less than 1. This is consistent with studies performed by Acworth and Jankowski (2001) where they found as salinity increased in groundwaters the Na/Cl ratio decreased, indicating reverse ion exchange processes become dominant as salinity increases in groundwaters. However, lower slope groundwaters have Na/Cl ratios that range from 0.3 to 1.7. Groundwater at depth (>10 m bgs) in the lower slope has Na/Cl ratios that reach unity as identified in Figure 8.11. Edmunds et al. (2003) suggests that a ratio close to unity would indicate halite to be the main source of salinity, however halite does not appear to be present in the sediments in Site 1 (or the catchment). Deeper Na(Mg)-Cl-rich groundwaters have Na/Cl ratios that are close to unity, therefore ratios close to unity could indicate mixing with deeper Na(Mg)-Cl-rich groundwaters.

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2+ 2+ + - - - Trends of Mg , Ca , K , HCO3 and SO4 verus Cl show that various hydrogeochemical processes are influencing the variability of ions in the shallow aquifer at Site 1. Magnesium and Ca2+ concentrations increase as Cl- increases in groundwaters located at the crest and mid slope (Figure 8.12 and 8.13). Magnesium concentrations in the lower slope groundwaters, particularly at depth (> 10 m bgs), have Mg2+ concentrations similar to the Na(Mg)-Cl-rich groundwaters, whereas Ca2+ concentrations decrease in lower slope groundwaters compared with Na(Mg)-Cl-rich groundwaters. Bicarbonate concentrations in the lower slope groundwaters at depth are also similar to deep 2+ + - Na(Mg)-Cl-rich groundwaters (Figure 8.15). Magnesium, Ca , K and HCO3 concentrations in groundwaters are not used as indicators of mixing between groundwaters because these ion are involved in numerous different geochemical reactions particularly in the seepage zone where fluctuating water tables lead to the change in redox conditions and influence the thermodynamic properties of the groundwater, which would influence the groundwater chemistry. Sulphate concentrations are slightly elevated in the lower slope relative to other 2- groundwaters from Site 1 (Figure 8.16). Once again, SO4 is also likely to be influenced by redox conditions in the aquifer.

Figure 8.12 Mg2+ vs. Cl- for groundwaters Figure 8.13 Ca2+ vs. Cl- for groundwaters from Site 1. from Site 1.

Dissolved silica concentrations decrease as Cl- concentration increases. Seepage zone affected groundwaters have a lack of silica. Drever and Smith (1978) noted that the contribution of silicate weathering to the Na+ concentration of springs is 235

Chapter 8: Geochemical processes influencing seepage zone development minor compared to contributions from the atmosphere (Drever and Smith, 1978). This was presumed because the accumulation of salts in the soil zone inhibits chemical weathering (Drever and Smith, 1978). Hence, the SiO2 concentration in groundwaters decreases from the crest to the mid slope..

+ - - - Figure 8.14 K vs. Cl for groundwaters Figure 8.15 HCO3 vs. Cl for from Site 1. groundwaters from Site 1.

2- - - - Figure 8.16 SO4 vs. Cl for Figure 8.17 SiO2 vs. Cl for groundwaters from Site 1. groundwaters from Site 1.

8.4.5.2 Soil chemistry trends in the seepage zone Identifying the hydrogeochemistry of Site 1 shows that groundwaters in the lower slope are impacted on by Na(Mg)-Cl-rich groundwaters, and therefore the influence of these groundwaters on soils will be discussed in this section. A Piper

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Chapter 8: Geochemical processes influencing seepage zone development plot of soil water extracts in Figure 8.18 shows soils at the crest and mid slope have mixed Ca-Mg-Na and HCO3-Cl ions and at the lower slope position soils are Na-Cl. Water-soluble constituents of soils at Site 1 show a change, where soils located at the crest have high Na/Cl ratios (4.5) and at the lower slope move to unity as soil EC1:5 increases (Figure 8.19). Rengasamy and Olsson (1991) showed Australian soils, especially those influenced by dryland salinity contain very low contents of soluble minerals, in particular Ca-rich minerals. These soluble minerals are necessary to maintain the electrolyte concentration during leaching, hence, these soils may become increasingly monotonic with increased leaching if a source of divalent cations is not present in the profile. Although soils in the lower profile have predominantly Na and Cl ions associated with them, these profiles have not been excessively leached and it appears soil salinisation and sodicity are related to saline groundwaters interacting with the soil profile.

Soil pH1:5 vary from acidic in the topsoils to alkaline (pH 9 to 9.5) in the lower slope soils (Figure 8.20). Sodic soils generally have a pH between 8.5 to 10, where the elevated pH may be a result of hydrolysis of Na2CO3 (Sparks, 2003). Once the soil 2- 2+ pH becomes elevated, the CO3 dominates the soil composition and if Ca and Mg2+ are present, carbonates are likely to precipitate leaving the soil solution low in Ca2+ and Mg2+ concentrations.

Figure 8.18 Piper diagram for 1:5 soil Figure 8.19 Na/Cl vs. EC1:5 for soils from water extracts for soils from Site 1. Site 1.

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Figure 8.20 pH vs. Cl1:5 for soils from Figure 8.21 ESR1:5 vs. SAR1:5 for soils Site 1. from Site 1.

8.4.4.3 Sodicity in the seepage zone From initial evaluation of soil data, it appears that soils in the lower slope have high Na+ concentrations and possess a potential sodicity risk. The characteristics of sodic soils have been described extensively by Rengasamy et al. (1984); Rengasamy and Olsson, (1991); Fitzpatrick et al. (1995); So and Allymore, (1995) and Sumner (1995). Sodic soils exhibit poor soil-water and soil-air relations, these properties adversely affect plant growth (Rengasamy and Olsson, 1991). Sodium Absorption Ratio (SAR) and Exchangeable Sodium Percentage (ESP) values of soils are used to determine the extent of sodicity (Emerson, 1967; Lima et al., 1990). The value of SAR in a soil is thermodynamically related to ESP when defining sodic soils (Duchaufour, 1982; Rengasamy and Olsson, 1991)

In Australian soils, when the ESP value is greater than 6 the soils is defined as sodic and maybe subject to serious structural degradation. The relationship between ESR and SAR are shown in Figure 8.21 where soils in the lower slope -1 are classified as sodic because soil EC1:5 is lower than 4 dS m , soil pH1:5 is greater than 8.5 and soil ESRs are above 6 . Hence, soil sodicity increases from the crest of the slope to the lower slope where soils become alkaline and sodic.

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8.4.4.4 Trace elements Trace elements are also useful indicators of geochemical processes occurring within an aquifer system (Durand et al, 1994). Most trace elements are likely to be removed by processes such as adsorption, mineral formation and organic complexation as groundwater flows through different lithologies (Giblin and Dickson, 1992). Therefore, the presence of trace elements in groundwaters can be used as an indicator of mixing. Elevated trace element compositions occur in shallow and deep groundwaters in the Spicers Creek catchment. Particularly high concentrations are encountered in the bedrock groundwaters. Mixing between deeper groundwaters and other groundwaters may therefore result in elevated trace element concentrations in the mixed groundwater bodies. Hence, trace element concentrations in groundwaters can be used as a tracer to determine the extent of mixing between groundwaters in the seepage zones.

A bivariate plot of B against Cl- shows a general increase of B in groundwaters from the crest to mid slope, with concentrations decreasing in the deeper sections (>10 m bgs) in the lower slope groundwaters (Figure 8.22). Boron concentrations are relatively also low in Na(Mg)-Cl-rich groundwaters. To determine whether B is sorbed from the groundwater in the lower slope, soil water extract results were examined. Soil water extract analysis indicates B is non-detectable in soils of the lower slope, indicating that B is not sorbed from the groundwaters onto the sediments and lower concentrations experienced in these groundwaters is most likely due to the mixing and dilution with deeper groundwaters. The relationship between Li+ and Cl- further shows that groundwaters in the lower slope have concentration of Li+ similar to deeper Na(Mg)-Cl-rich groundwaters (Figure 8.23).

The relationship between Sr2+ and Cl- shows Sr2+ concentrations of groundwaters located at the crest and mid slope increase as Cl- increases (Figure 8.24). Groundwaters in the lower slope experience a decrease in Sr2+ concentrations relative to Na(Mg)-Cl-rich groundwaters. Hitchson et al. (1999) suggest that the 2+ thermodynamics of strontianite (SrCO3) can govern the concentration of Sr in natural groundwaters. The likelihood of strontianite precipitation is explored further in section 8.4.5.

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Figure 8.22 B vs. Cl- for groundwaters Figure 8.23 Li+- vs. Cl- for groundwaters from Site 1. from Site 1.

Figure 8.24 Sr2+ vs. Cl- for groundwaters Figure 8.25 As- vs. Cl- for groundwaters from Site 1. from Site 1.

Other trace elements such as As and Se are elevated in shallow groundwaters at Site 1. Arsenic increases with an increase in Cl- concentration (Figure 8.25). Arsenic is elevated in the Oakdale Formation aquifer and is associated with pyritic sediments contained within this unit (refer to section 7.3.6). Arsenic concentrations are elevated in Na(Mg)-Cl-rich groundwaters. The trace element solubility is most likely controlled by metal-chloride complexes that form in groundwaters with high Cl- concentrations (Long and Angino, 1977; Lyons et al. 1987). Arsenic is released from this unit into the groundwaters and appears to accumulate within the seepage

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Chapter 8: Geochemical processes influencing seepage zone development zone and is well correlated with Cl- (r2=0.971). It is also well correlated Se (r2=0.973) and V (r2 = 0.878).

Selenium is also strongly positively correlated with Cl- (r2 = 0.988). The relationship between Se and Cl- in shallow groundwaters is represented in Figure 8.26. Selenium was not analysed in deeper Na(Mg)-Cl-rich groundwaters but due to the high correlation between Se and As (r2=0.973) it suggests these ions are released from a similar source, which is most likely in the Oakdale Formation aquifer. Selenium concentrations in uncontaminated groundwaters generally range from 0.0001 to 0.01 mg L-1 (Hitchson et al. 1999). Groundwaters at Site 1 are elevated in Se concentrations relative to these values. Miller et al. (1981) found elevated concentrations of Se within dryland salinity-affected seepage zones in the North American Great Plains of USA. They found concentrations from 0.06 to 2 mg L-1 (Miller et al., 1981) and expressed concerns about the impact of Se on surface water systems.

Figure 8.26 Se vs. Cl- for groundwaters Figure 8.27 V vs. Cl- for groundwaters from Site 1. from Site 1.

Arsenic and Se concentrations are not as elevated in the lower slope groundwaters as the in the Na(Mg)-Cl-rich bedrock groundwaters. However, As and Se mobilisation is highly dependent on pH and Eh conditions in the aquifer system (Smedley and Kinniburgh, 2002). As deeper groundwaters meet sediments of the shallow aquifer, a change in geochemical condition may lead to coprecipitation reactions where Se and As may be preferentially associated with iron 241

Chapter 8: Geochemical processes influencing seepage zone development oxide aggregates in the soil (Strawn et al., 2002). Therefore, As and Se concentrations may decrease due to mixing in the shallow groundwater system.

Vanadium is also well correlated with As (r2=0.878) and Se (r2=0.897) and increases as Cl- concentration increases (Figure 8.27). Vanadium is associated with the Oakdale Formation and Gleneski Formation aquifers in the catchment and elevated concentrations in groundwaters appear to be related to a bedrock source. The sediments that make up the shallow aquifer in this part of the catchment are derived from weathered bedrock material. As groundwater migrates through these sediments, Cl- concentration increase and trace element mobilisation occurs.

8.4.4.5 Behaviour of carbonates in the seepage zone Miller et al. (1981) identified that the chemistry of seeps is primarily controlled by carbonate and sulphate minerals contained within the shallow aquifer system. The groundwater seepage zone is an extremely dynamic region where changes in recharge, groundwater flow rates and surficial flow can have an affect on the geochemical dynamics of the system (Lyons et al. 1992). Carbonates are particularly dependent on different thermodynamic conditions, therefore saturation indices for carbonates were assessed to identify how carbonate minerals maybe influencing groundwaters at Site 1.

Saturation indices of various carbonate minerals were assessed to identify how these parameters change in groundwaters in relation to seasonal change. Groundwater chemistry was determined in spring November 2001, winter June 2002 and summer February 2003. Time series graphs of calcite (Figure 8.28) and strontianite (Figure 8.29) saturation indices show that groundwaters in the lower slope are oversaturated with respect to these carbonate minerals in summer when evapotranspiration rates are higher and decrease in saturation in winter. These results are similar to Smith and Drever’s (1976) findings where they found that Ca2+ and Mg2+ are removed from solution in arid periods due to calcite and dolomite precipitation.

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Figure 8.28 Time series graph for calcite Figure 8.29 Time series graph for in groundwaters from Site 1. strontianite in groundwaters from Site 1.

These results indicate that the precipitation of carbonates in the seepage zones appears to be cyclic and is related to the amount of evapotranspiration and recharge to the groundwater system. The seepage zone is a dynamic area of interaction between groundwaters of various redox potential and chemistry (Hines et al, 1992). During winter when evapotranspiration rates are lower in the Spicers Creek catchment carbonates are more likely to precipitate. Seasonal hydrologic change appears to influence the precipitation/dissolution of carbonate minerals in the seepage zone. Seepage zone formation is not solely reliant on deep groundwater discharge but is also affected by seasonal hydrologic change. During drilling and soil sampling abundant calcareous material was identified within the sediments of the lower slope, particularly at around ~10 m bgs, supporting that 2+ - 2+ Ca , HCO3 and Sr maybe removed from solution due to carbonate precipitation.

Saturation with respect to calcite increases when a system is open to CO2 influx because the amount of calcite that can be dissolved in water is limited by the availability of CO2 (Drever 1994; Salama et al, 1999). Most groundwaters at Site 1 are oversaturated with respect to calcite because they are an open system with respect to CO2. A plot of calcite and strontianite shows groundwaters in the lower slope (S1c) and deep Na(Mg)-Cl-rich groundwaters are both supersaturated with respect to both calcite and strontianite (Figure 8.30).

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Figure 8.30 SIcalcite vs. SIstrontianite for groundwaters from Site 1.

8.4.4.6 Clay mineral transformation in the seepage zone Clay mineralogical composition in the shallow aquifer at Site 1 was determined using soil spectroscopy results and inspecting clay stability diagrams. Saturation indices of gibbsite, kaolinite, illite and montmorillonite shows that groundwaters are all supersaturated with respect to these minerals in Site 1 and thermodynamic conditions are suitable for these clay minerals to form.

Na+, Mg2+, Ca2+ and K+ stability diagrams are presented in Figures 8.31 to 8.34 (refer to 7.3.4.3 for details on clay stability diagrams). Groundwaters at the crest and mid positions of the slope plot in the kaolinite field and evolve to the montmorillonite field at depth. Groundwaters at the bottom of the slope all plot in the kaolinite stability field. As the groundwater salinity increases groundwaters move from equilibrium with montmorillonite to kaolinite. Haines and Lloyd (1985) suggest that groundwaters that plot in the kaolinite stability field are more chemically mature than those that plot in the montmorillonite field.

Soil spectroscopy results presented in Figure 8.35 show a variation in clay mineralogy along the profile. The clay mineral assemblage present at Site 1 has formed due to various geochemical processes, which are reliant on the parent material, permeability of sediments, water-sediment ratios and the chemical composition of the groundwater. According to Velde (1992), kaolinites or 1:1 clays

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Chapter 8: Geochemical processes influencing seepage zone development will form in well drained soil profiles, generally at the top of the soil profile and at the top of a transect. As sediments become less permeable and where drainage is impeded, 2:1 clay minerals, such as smectites, are likely to occur. Therefore, the clay mineralogy present can be a guide to groundwater flow characteristics of a site.

Figure 8.31 Stability diagrams at 25°C Figure 8.32 Stability diagrams at 25°C and 1 bar pressure based on Drever and 1 bar pressure based on Drever (1988) for the silicates for Mg2+ (1988) for the silicates for Ca2+ groundwaters from Site 1. groundwaters from Site 1.

Figure 8.33 Stability diagrams at 25°C Figure 8.34 Stability diagrams at 25°C and 1 bar pressure based on Drever and 1 bar pressure based on Drever (1988) for the silicates for Na+ (1988) for the silicates for K+ groundwaters from Site 1. groundwaters from Site 1.

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At the crest of the slope, variations between montmorillonite and halloysite clay mineralogy occurs, which is likely to represent different drainage patterns throughout the soils profile. Halloysite clay minerals are forming in the soil profile where the water to sediment ratio is greatest due to solution renewal and dilution by rainfall and therefore 1:1 types clays are likely to form (Velde, 1992). At the mid slope position, clay minerals move from dominantly 1:1 to 2:1 clay types. Montmorillonite and illitic clays are forming at S2 and the soil profile becomes montmorillonite-rich with nontronite, a Fe-rich variety of montmorillonite, dominating the soil profile. The presence of these clay minerals indicates prolonged water-sediment interaction or low flushing rates (Lawrence and Taylor, 1971).

At the lower slope in the seepage zone, halloysite and kaolinites dominate the clay mineralogy. This is unusual because this seepage zone experienced continuous waterlogging with saline groundwaters and limited groundwater flow therefore the formation of smectites clays is favoured (Haines and Lloyd, 1985). The formation of 1:1 type clays, as suggested by Gerla (1992), may be occurring due to rapid recharge of rainfall high in H+ or in areas where the pH is not buffered by carbonate dissolution. The later is the most likely scenario, where groundwaters in the lower profile are oversaturated with respect to carbonate minerals and precipitation rather than dissolution of carbonates is occurring.

8.4.4.7 Ion exchange processes Ion exchange reactions in groundwaters were assessed using the relationship 2+ 2+ 2- - + - between Ca + Mg - SO4 - HCO3 against Na -Cl (refer to 7.3.5 for ion exchange details). Groundwaters mostly plot in the reverse ion exchange quadrant of the graph and it is particularly important to note groundwaters from the lower slope (>10 m bgs) plot in the reverse ion exchange field, where Ca2+ and/or Mg2+ are likely to be exchanged for Na+ on the clay surface, because soil solution more concentrated

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Figure 8.35 Cross-section depicting clay mineral assemblages through Site 1 in the Spicers Creek catchment.

247 Chapter 8: Geochemical processes influencing seepage zone development

Figure 8.36 Ca + Mg – SO4 – HCO3 vs. Na-Cl for groundwaters from Site 1.

Ion exchange and reverse ion exchange processes appear to influence the chemistry of Site 1 groundwaters. When considering impact of the clay mineralogy on ion exchange processes at Site 1, kaolinites have between 2 to 15 cmol kg-1 exchange capacities and halloysite has a slightly greater capacity of between 10 to 40 cmol kg-1 (Sparks, 2003). The exchange potential of montmorillonite is high with between 80 to 150 cmol kg-1 due to substantial isomorphic substitution and presence of fully expanded interlayers that promote exchange of ions (Sparks, 2003). Clay minerals in the lower slope are composed of predominately halloysite clay mineral and most likely have between 10 to 40 cmol kg-1 exchange capacities.

8.4.5 Modelling mixing in the seepage zone at Site 1 Many geochemical processes are likely to influence the groundwater chemistry of seepage zone waters. These processes included; redox reaction, evapotranspiration, salinisation and the formation of surficial crusts (Salama et al., 1998; Fitzpatrick et al., 1996). Therefore, a simple mixing model between a fresh water and saline end-member groundwater to produce the observed seepage zone groundwater was performed using inverse modelling techniques.

The initial groundwater (1) selected was S3b, which represents a groundwater that has not been influenced by salinity. Initial groundwater (2) is 96121/3, which represents a deep Na(Mg)-Cl-rich groundwater and the final solution, which is the

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Chapter 8: Geochemical processes influencing seepage zone development resultant groundwater chemical composition from the mixing of these two groundwaters, is S1c. This sample is located in the lower slope at Site 1 (~10.8 m bgs) and represents a groundwater that is influenced by mixing with deeper groundwaters.

Mass balance modelling was used to assess the main geochemical processes influencing the observed groundwater chemistry and primarily to quantify the amount of groundwater mixing occurring in the seepage zone. This information can then be used as a guide to determine the potential contribution of salt from accession and from deep discharge to the seepage zone. The modelling code, NETPATH (Plummer et al., 1994) was used to model these groundwaters (refer to 7.3.8 for modelling details).

8.4.5.1 Constraints The selected constraints for this model scenario include; C, Ca, Mg, Na, Cl, Na and Sr. These major cations and anions were chosen because they are involved in the major processes influencing salinisation. Strontium was chosen because it is elevated in Na(Mg)-Cl-rich groundwaters.

8.4.5.2 Phases Phases where chosen based on saturation indices for groundwaters in the seepage zone, soil analysis and evaluation of hydrogeochemical process using bivariate plots and isotopic evidence discussed earlier. Phases selected include calcite, dolomite, strontianite, CO2(g) and reverse ion exchange. CO2(g) was included and the carbon-13 signature was set by NETPATH at –25 per mil to represent soil zone CO2(g). There is no evidence that NaCl is present within the shallow aquifer because sediments are relatively non-saline away from the seepage zone. Therefore, NaCl was removed from the set of phases so that NETPATH would set the mixing ratio for Cl-. Chloride is assumed to be contributed from atmospheric accession and deeper groundwaters, not from halite dissolution.

Rayleigh distillation calculations are compared with observed values to examine the difference between the fractionating differential problem of isotopic evolution

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Chapter 8: Geochemical processes influencing seepage zone development and mass balance results (Plummer et al., 1994). The Mook fractionation factors for the inorganic carbon-13 systems were used (Mook, 1980, 1986).

8.4.5.3 Model interpretation One model was checked and this model was found to be plausible by assessing it against the Rayleigh distillation calculation, saturation indices and bivarite plots for this groundwater. The model is presented below;

Initial Well 1 : 96121/3 Initial Well 2 : S3b Final well : S1c

Final Initial 1 Initial 2 C 18.6887 16.0883 8.9775 CA 2.5286 7.7642 2.2324 MG 13.3491 13.6725 5.6370 CL 97.6810 134.4702 19.2076 SR 0.0669 0.2318 0.0360 NA 82.2805 116.4614 10.4780

CO2 GAS C 1.0000 RS 4.0000 I1 -25.0000 I2 100.0000 CALCITE CA 1.0000 C 1.0000 RS 4.0000 I1 0.0000 I2 0.0000 STRONITE SR 1.0000 C 1.0000 RS 4.0000 Mg/Na EX NA 2.0000 MG -1.0000 DOLOMITE CA 1.0000 MG 1.0000 C 2.0000 RS 8.0000 I1 0.0000 I2 0.0000

1 model checked 1 model found

MODEL 1 Init 1 + F 0.68082 Init 2 + F 0.31918 CO2 GAS 6.37758 CALCITE -5.53466 STRONITE -0.10240 Mg/Na EX -0.17667 DOLOMITE 2.06472 Computed Observed Carbon-13 -15.0855 -13.3000

68% Na(Mg)-Cl-rich groundwater + 32% fresh (S3b) + 0.31CO2 + 2dolomite → 5.5calcite + 0.1strontinainte + 0.17Na/Mg exchange

The model is compatible with the observed chemistry and it appears that mixing between deep Na(Mg)-Cl-rich end-member groundwaters with rainfall recharged groundwater is influencing the observed chemistry. Approximately 68% of Na(Mg)-

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Cl-rich groundwaters appear to be mixing with 32% of fresh groundwaters to produce the observed groundwater chemistry in the seepage zone at the lower slope.

The model suggests that as groundwater migrates through the clay-rich aquifer, calcite and strontianite may be precipitated out of the water. Carbonate precipitates were identified in the sediments of the lower slope and, calcite and strontianite are oversaturated in S1c groundwaters. Using these mixing calculations, assumptions on the amount of Cl- from each source can be made. Therefore, approximately 30% of the salt is from a recent aerosol source and a further 70% from deep groundwaters. It is most likely that these have reached the surface through a permeable fault zone located at Site 1.

8.5.6 Hydrogeological and hydrogeochemical model of Site 1 Evaluating the presented data, a hydrogeological and hydrogeochemical model for the seepage zone at Site 1 was developed (Figure 8.37). It has previously been established that a regional fault zone runs through Site 1, where crosscutting faults intersect. Modelling the groundwater chemistry suggests that this fault is a conduit for groundwater flow. This site forms the contact between the Gleneski Formation on the east and the Oakdale Formation on the west. The clay mineralogy of this site indicates that montmorillonite-rich clays are forming at the approximate boundary of these two units and indicates a permeability contrast at this point.

Groundwaters in the seepage zone have a similar geochemical signature to the deeper Oakdale Formation groundwaters where δ18O, Cl- and Na+ concentrations are similar to the bedrock. The deeper bedrock groundwaters are elevated in As, Sr2+ and V concentrations, and these trace elements are identified in the shallow groundwaters. Modelling showed that the observed groundwater sample at S1c is likely to be composed of approximately 68% deep and 32% fresh groundwater. As deeper groundwaters migrate through the permeable fracture zone, they encounter the clay-rich sediments of the shallow aquifer and precipitation reactions involving carbonates occur. Due to the precipitation of carbonate in the shallow system, the groundwaters are not buffered by the carbonate system

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Chapter 8: Geochemical processes influencing seepage zone development hence, groundwaters become more susceptible to forming kaolinite-rich clays instead of montmorillonites in the seepage zone. Minor reverse ion exchange processes are also influencing groundwater chemistry. At the surface during summer, when evapotranspiration rates are high, carbonate-rich precipitate forms. Surficial processes such as observed at Site 1 are likely to form due surface evaporation processes (Turner et al., 1987).

Figure 8.37 Model of seepage zone formation at Site 1.

Water levels are at or near the ground surface in the seepage zone. Cartwright et al. (2004) proposes that in summer an upward head is promoted by evaporation in dryland salinity affected areas. They also suggest that in winter a head reversal occurs and saline groundwaters are able to re-enter the groundwater system. Evaporation is not a major process in the seepage zone but may explain the slightly more elevated EC values in groundwaters in the top 5 m compared with groundwater located between 6 to 8 m bgs.

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These seepage zones are dependent on rainfall and deep discharge; their cyclic nature is not only due to the local groundwater system but also a function of the regional groundwater system. A mixing model suggests that approximately 70% of Cl- is contributed from the deep Na(Mg)-Cl-rich groundwaters and 30% from fresh groundwaters. Mixing percentages will vary due to water level fluctuations, which will change the thermodynamic property of the groundwaters. Hence, the development of a seepage zone at Site 1 appears to be associated the geology, the presence of geological structures, the extent of groundwater mixing and the extent of mixing in the seepage zone.

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CHAPTER 9: CONCLUSIONS

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9.1 REVIEW OF THE PROBLEM Dryland salinity is recognised as a major environmental problem impacting on land and water resources in Central West Region of NSW. The Spicers Creek catchment is located within this region and due to the geological complexity and high salt loads contained within the catchment it was allocated an extremely high salinity risk (Humphreys, 2000).

Spicers Creek catchment experiences semi-arid climatic conditions with episodic rainfall regimes. During the study period, 2001 to 2003, drought conditions prevailed. Combinations of climatic, geological and agricultural factors appear to be influencing the observed salinity problems. The surface waters of the Spicers Creek are brackish with an average EC ~5 dS m-1, reaching peaks of over 10 dS m-1 during drought periods. Over the past 5 years, it appears that the average surface water salinity of the Spicers Creek has steadily increased. Approximately 90% of the catchment has been cleared of its native vegetation due to agricultural activities such as cropping or grazing which began in the area over 100 years ago.

Soils in the Spicers Creek catchment are prone to dryland salinity development due to their predominantly low hydraulic conductivity, the low drainage characteristics of the area and clearing regimes within the catchment. Therefore, soils have the potential to become waterlogged and Cl- accumulation is likely to occur. Fertile red-brown earths of the Ballimore and Arthurville soil landscapes are therefore now threatened by salinity and soil erosion. The geological complexity of the catchment, together with the presence of sodic Na-HCO3-rich and saline Na(Mg)-Cl-rich groundwaters within the fractured bedrock aquifers present in the catchment have also present risks for this area. Therefore, an understanding of where the salt is located, how it accumulates and how it is mobilised in the catchment will help alleviate salinity problems in the catchment.

The main aim of this thesis was to identify the factors affecting dryland salinity processes in the Spicers Creek catchment. These include the role of geological structures, the source(s) of salts to the groundwater system and the geochemical processes influencing seepage zone development. To achieve these aims a

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Chapter 9: Conclusions multidisciplinary approach was untaken to understand the soils, geology, hydrogeology and hydrogeochemistry of the catchment. Investigative techniques employed in this project include the use of high-resolution airborne magnetics and radiometrics used in conjunction with ground-based electrical imaging and magnetic techniques. Soil science, soil spectroscopy, hydrogeochemistry and isotopic techniques were also used to further understand this problem.

9.2 SUMMARY OF MAJOR FINDINGS The major findings of this research are summarised below according to the technique that was used to investigate the problem.

9.2.1 Geology The structural complexity of the catchment was evaluated using high-resolution airborne magnetics imagery, which identified four significant and several minor previously unmapped structures. This method was particularly useful in identifying large open structural features in the area. The Oakdale Formation is particularly amenable to the use of magnetics techniques because it generally exhibits a high magnetic intensity. Groundwater flow in the Oakdale Formation is structurally controlled and as groundwater migrates through these structures it alters minerals such as magnetite. This process produces discontinuities or lows in the observed magnetic pattern. Recognising these patterns led to the observation of a regionally extensive north-east to south-west regionally shear zone. The structure appears to be 0.5 to 1 km wide and conducive to groundwater flow. This structure dissects the Spicers Creek catchment and several other minor faults were observed to be splays off this major structure.

9.2.2 Hydrogeology Evaluations of the behaviour of the previously poorly understood Oakdale Formation and Gleneski Formation aquifers were undertaken. Water levels in the Oakdale Formation are within 2 to 10 m bgs and in the south of the catchment were found to have over 80 m of upward hydraulic head. Groundwater flow in the deep fractured aquifers is governed by fracture density, aperture and connectivity. It was found that the Oakdale Formation has a higher hydraulic head than the

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Gleneski Formation aquifer where the two aquifers are contact faulted against each other and an upward hydraulic gradient was identified in bores that are located within a geological structure at this zone.

During the period of the study water levels in the shallow aquifer were found to have decreased due to drought conditions experienced in the catchment. Average water levels of the shallow aquifer throughout the catchment were recorded at 0.82 m bgs (n=50) in June 2001 and decreased in February 2003 to an average water level of 1.89 m bgs (n=50). However, water levels of shallow piezometers associated with the fault zones remained elevated (<2m bgs). A connection between climatic conditions and deep hydraulic pressure was identified in the seepage zones.

9.2.3 Hydrogeochemistry and isotopes Oakdale Formation groundwaters were found to quite saline (>14,500 µS cm-1) at 110 m bgs and were found to contain elevated concentration of As, Sr2+ and V. The Gleneski Formation groundwaters were found to be relatively fresh (~3,700 µS cm-1) at 100 m bgs. Deep groundwaters were found to be variable in EC and groundwater chemistry, and trends in aquifer types were not evident. Shallow groundwaters in the Spicers Creek catchment were of varied composition ranging from ~450 to 23,250 µS cm-1 and were also found to be elevated in As, Ba, Ga, Se, Sr2+ and V.

Vertical distribution plots of ions versus depth proved less informative than the spatial distribution of ions in the catchment. The spatial distribution of EC, Cl-, Sr2+ and 87Sr/86Sr isotopic ratios showed the correlation between the presence of saline groundwaters and the location of structural features throughout the catchment. - + + 13 The spatial distribution of HCO3 , K , Li and δ CDIC highlighted the spatial extent of Na-HCO3-rich groundwaters in the Spicers Creek catchment and presented the possibility of these groundwaters participating in mixing as far as experimental Site 2. The association of groundwater seepage zones with structural features was identified. Of particular interest was the association of the highest salinity groundwaters with an area where two faults intersect. The location of all three

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Chapter 9: Conclusions experimental sites corresponded with geological structures. Another two of the most saline groundwater samples in the catchment were abstracted from bores situated in this fault zone where crosscutting faults occur.

Once the association of groundwaters with structural features was realised the hydrogeochemistry of the deep and shallow groundwaters was recognised to be of great significance. Two distinctive groundwater chemical types were observed in the catchment. They include the Na(Mg)-Cl-rich groundwaters associated with the fractured Oakdale Formation and the Na-HCO3-rich groundwater associated with the intermediate groundwater system. The geochemical evolution of Na-HCO3-rich groundwaters has been described by Schofield (1998) and Schofield and Jankowski (2003, 2004).

This research discovered the origin and geochemical evolutionary pathways of the Na(Mg)-Cl-rich groundwaters. The Na(Mg)-Cl-rich groundwaters were found to be meteoric in origin and have not undergone significant amounts of evaporation prior to recharge. They have Na/Cl ratios of ~1 and elevated concentrations of Na+, Cl-, 2- 2+ SO4 , As, Sr and V. Inverse modelling of these groundwaters together with use of saturation indices (SI), bivariate plots and detailed mineralogical evaluation shows that the dissolution of NaCl and KCl, the oxidation of pyrite and weathering of Ca-plagioclase and biotites are contributing to their observed chemical composition. During their evolutionary pathway throughout the fracture zones in the Oakdale Formation aquifer, reverse ion exchange (Na/Mg), calcite precipitation and, the formation of weathering products such as kaolinite, haematite and chlorite are also occurring.

87Sr/86Sr isotopic ratios were used to identify that elevated concentrations of Sr2+ in the Na(Mg)-Cl-rich groundwaters are from the weathering of plagioclase phases contained within the Oakdale Formation aquifer. These results also showed that Na(Mg)-Cl-rich groundwaters inherited less radiogenic signatures as Cl- and Sr2+ concentrations increase. This study shows the possibility of rock derived Cl- from halogenated biotites should not be dismissed because the evolution of these Na(Mg)-Cl-rich groundwaters from the Oakdale Formation at 110 m bgs have occurred due to prolonged and extensive geochemical reactions. However, rock-

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Chapter 9: Conclusions leaching tests must be performed on crushed rock samples of the Oakdale Formation to confirm the presence of these halogenated biotite phases. 87Sr/86Sr isotopic ratios also showed that the source of Sr2+ is not purely from marine or aerosol input. The source of salt to these groundwaters is most likely from various allochthonous and autochthonous sources.

The significance of these findings shows Na(Mg)-Cl-rich groundwaters are geochemically distinctive and have evolved due to extensive water-rock interaction processes within the fracture zones of the Oakdale Formation.

High salt loads (~2.5 million tonnes of Cl-) were found to exist in the shallow groundwater system and δ18O, δ2H and Cl- data indicates evaporation is not the major process responsible for the accumulation of solutes in the landscape and that shallow groundwaters are meteoric in origin. It was found that salt is not associated with the dissolution of evaporitic deposits because Cl/Br ratios have an average value of ~297 similar to seawater (Davis et al., 1998). These ratios are higher than rainfall ~65 indicating Cl- is added to the soil profile during infiltration. It was also found that Cl- is not likely to be solely from aeolian sources because the salt entrained in a parna deposit would have undergone evaporative concentration and higher Br/Cl ratios would be expected.

Using the Chloride Mass Balance (CMB) techniques a recharge rate of ~5 mm yr-1 and a rainfall accession rate of 30 kg ha-1 yr-1 were calculated for the Spicers Creek catchment. Chloride is likely to travel 6 to 30 m y-1 in the shallow aquifer system and average groundwater residence time in the shallow aquifer was calculated at 20 years, which is confirmed with CFC dating of results indicating groundwaters are approximately 36 years old (Mohammed, 1999b). Carbon-14 dating of seepage zones groundwaters found that these groundwaters are much older than groundwaters not influenced by seepage zone formation. Seepage zone groundwaters range from 900 to 4,500 years old.

It was found that seepage zones are acting as mixing zones for rainfall recharge and deeper groundwaters. The geologic conditions required for seepage zone formation are the presence of geological faults and a high hydraulic pressure in

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Chapter 9: Conclusions the fractured aquifer. δ18O and Cl- profiles provided further evidence for mixing between deep and rainfall recharged groundwaters in the seepage zones. The amount of mixing was quantified using inverse modelling techniques and it was found that 68% of Na(Mg)-Cl-rich groundwater was mixed with 32% fresh groundwaters to obtain the observed groundwater chemistry in the seepage zone. Therefore it was concluded that approximately 30% of Cl- can be attributed to rainfall accession and 70% Cl- from deeper groundwaters.

The major importance of this research highlights the need for the combined use of geophysical, hydrogeology, soil science and hydrogeochemistry in dryland salinity research. These integrated techniques made it possible for recognition of structurally controlled dryland salinity and aided in the understanding of the various sources of salt.

9.3 RECOMMENDATIONS Dryland salinity seepage zones in the Spicers Creek catchment are cyclic in nature and reliant on rainfall recharge patterns in the local and regional scale. Therefore, during dry periods, these surface expressions may become minimal but when climatic conditions are altered, these systems may become reactivated. Recognition of the structural controls on seepage zones must be the first step in management.

It is recommended that high-resolution geophysical imagery be obtained for areas where the Oakdale Formation occurs to identify structural trends in the basement rock and identify possible groundwater flow paths in the fractured aquifers. Studies are underway into identifying the spectral properties soils contained with in geological structure zones at UNSW by Geoffrey Taylor and the reader is encouraged to consult this research for further details.

Major recommendations for future research include; ¾ Identifying the hydraulic conductivity of geological structural zones; ¾ Assessing the extent of geological structures;

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Chapter 9: Conclusions

¾ Obtaining rock samples from the Oakdale Formation and conducting the following tests; o Rock leaching tests; o Electron-microprobe analysis on biotite phase; o 87Sr/86Sr isotopic of all the individual phases; ¾ 36Cl and 14C isotope analysis of the groundwaters to determine ages; and ¾ Lithium isotope analysis to delineate whether marine or terrestrial origin.

9.4 FINAL COMMENTS Dryland salinity research in structurally complex catchments needs to assess the entire soil-air-plant-water system to fully understand how these variables influence seepage zone development. As mentioned by Clarke et al. (2002) and confirmed by this research, further consideration to the effect of regional structures on groundwater fluid migration is needed to identify possible exchange of saline fluids from one catchment to the next. The Spicers Creek catchment is located in a low permeability fractured bedrock system and groundwater movement is minimal, however fluid migration still exists. Saline groundwaters are located at 110 m bgs and the effect of these groundwaters must be considered. These saline groundwaters contain elevated concentrations of trace elements such as As, V and possibly Se, which pose a potential risk for water resources in the area. It is not imperative to identify whether the source of salt is allochthonous or autochthonous to the Na(Mg)-Cl-rich groundwaters; the fact remains that these deep saline groundwaters do exist in the Spicers Creek catchment and these groundwaters will migrate to discharge point(s) in the landscape, whether it is in the Spicers Creek catchment or a catchment further down the groundwater flow path.

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Appendix A: Methodology

APPENDIX A

Appendix A: Methodology

A.1 INTRODUCTION This project incorporates a variety of environmental, geological and geochemical investigation techniques, to obtain detailed information with regards to dryland salinisation processes occurring within the Spicers Creek catchment. The main techniques employed include hydrogeochemical interpretation of soil analyses, soil spectroscopy, and airborne and ground-based geophysics. This multidisciplinary approach has allowed for hydrochemical categorisation of soils and groundwaters on a regional and site-specific scale. This project consisted of a two year fieldwork program where data was collected between 2001 to 2004. Field visits are summarised as follows:

¾ April 2001 – drilling of deep nested piezometers into fractured aquifers in the Spicers Creek catchment using 6.5 inch percussion hammer rig (by DLWC Dubbo Drilling Unit); ¾ 20-26th June 2001 – reconnaissance survey of the catchment to identify locations for drilling of shallow piezometers and initial groundwater EC and water level readings of pre-existing piezometers in the catchment (by author and Jerzy Jankowski, UNSW); ¾ 14-20th August 2001 – drilling and installation of shallow piezometers at Sites 1 and 2, using a Proline auger drill rig (by Russel Millard and Mathew Delaney DLWC). Soil samples were collected during drilling (by author, UNSW). EM34-3 survey of Site 2 completed (by Russel Millard, Mathew Delaney DLWC and author, UNSW); ¾ November 2001 – groundwater sampling and water level measurement of shallow and deep piezometers (by author and Jerzy Jankowski, UNSW). ¾ December 2001 – drilling and installation of shallow piezometers at Site 3 (by Russel Millard, DLWC); ¾ 14th March 2002 – acquisition of single swath airborne hyperspectral imagery in the north-south direction; ¾ 2-8th April 2002 – electrical imaging profiles and ground-based magnetics completed at Sites 1, 2 and 3 (by author, Jerzy Jankowski, Ramin Nikorz and Derek Palmer, UNSW). Water level measurements were also taken (by author);

Appendix A: Methodology

¾ 3-16th June 2002 – groundwater sampling and water level measurement of shallow piezometers (by author, Jessica Northey and Jerzy Jankowski, UNSW); ¾ July 2002 – the acquisition of high-resolution airborne radiometrics and magnetics imagery from MIM; ¾ 12-16th August 2002 – field calibration of soils for hyperspectral imagery using PIMA and FIELDSPEC portable spectrometers at Sites 1 and 2 (by author, Casey Edwards and Geoffrey Taylor, UNSW). Water level measurements were also taken at Sites 1, 2 and 3 (by author); ¾ 3-8th September 2002 – groundwater sampling, and isotope collection for deep and intermediate aquifer systems. Water levels were also measured (by author and Sarah Groves, UNSW); and ¾ 1-7th February 2003 – groundwater sampling and isotope collection for shallow aquifer system. Water levels were also measured (by author, UNSW, and Gavin Meredith). During these field trips, over 200 hundred water chemistry samples were taken and over one hundred soil samples were collected from throughout the catchment.

A.2 GEOPHYSICS Various airborne and ground-based geophysical techniques were employed in this project, including airborne magnetics and radiometrics, together with ground- based techniques (electrical imaging, magnetics and electromagnetic techniques). The locations of these surveys are identified in Figure A1.

A.2.1 Airborne geophysics Structural features in Spicers Creek catchment were determined using high resolution geophysical data obtained from MIM Exploration Pty Ltd (now known as XStrata Copper Exploration) in July 2002 (MIM, 2002) together with low resolution imagery obtained from Department of Mineral Resources “Exploration NSW” 2000 (DMR, 2002) program. High-resolution data was obtained over exploration areas, EL5623 Yarindury and EL5758 North Comobella. High-resolution magnetics imagery was processed to allow for the investigation of the subsurface geology based on anomalies in the earth’s magnetic field resulting from magnetic properties of the underlying bedrock. 3

Appendix A: Methodology

The use of magnetics aids in the identification of intrusives, dykes, lithological boundaries and delineates zones of faulting within bedrock (Kearey and Brooks, 1991). The high-resolution magnetics were analysed and processed in ERMapper and total magnetic intensity (TMI) images were manipulated using various algorithms and applying various filters. TMI images were reduced to the poles and the first and second derivatives of this data were produced. The first derivative image emphasised short wavelength anomalies from the near surface anomaly source that highlights lithological boundaries and structural features. Discontinuities in pattern elements contained within the geophysical data were interpreted as faults. An east to west sun angle illumination filter was applied to the TMI to further clarify the image for the identification of subtle magnetic lows.

A.2.2 Ground-based geophysics A.2.2.1 Ground-based magnetics Ground-based magnetics surveys were completed at Sites 1, 2 and 3 and based on a grid system with 10 m intervals. A GEOMETRICS MAGMAPPER G858 magnetometer was used to delineate the magnetic signature of the sites. Site 1 covered an area 170 m by 150 m and Sites 2 and 3 were 400 m by 100 m areas. Survey locations are presented in Figure A1.1.

A.2.2.2 Electromagnetic survey An electromagnetic survey (EM) survey was completed at Site 2, using a GEONICS EM34-3 device. This is a fixed frequency electromagnetic instrument, which is used to determine the electrical conductivity, and hence the salinity at different depths. These devices measure the depth-weighted mean bulk EC that is mainly dependent on salt storage, soil texture and water content of the site (Williams, 1995).

This device consisted of a transmitter coil and receiver coils with 10 m coil separation. The transmitter coil induces a small eddy current in the earth to a certain depth and measurements are made at the receiver in the horizontal and vertical dipole positions (McNeill, 1980). The receiver coil measures both the

Appendix A: Methodology primary and secondary EM fields. The ratio of the two fields provides a measure of the apparent depth-weighted EC of the soil in dS m-1 (Williams, 1995).

Figure A.1 Location of ground-based geophysical surveys in the Spicers Creek catchment.

Appendix A: Methodology

Exploration depths for 10 m inter-coil spacing were 7.5 m in horizontal dipoles and 15 m in the vertical dipoles. Resistivity readings were recorded in milliohms/m. Measurements were recorded every 10 m. Results were then contoured in SURFER using the recorded resistivity measurements.

A.2.2.3 Electrical imaging Five electrical image profiles where completed using an ABEM TETRAMETER SAS 300B electrical imaging device. Electrodes were spaced using a 4-electrode system known as the Wenner Array. Rhoades and Ingvalson (1971) developed this technique for determining soil salinity using 4 electrodes in a straight line to measure the soil resistance. Resistivity methods require an artificially generated electric current that is transmitted via two metal electrodes. Four electrodes were placed in line with a constant separation between the electrodes. Readings were taken at 5 m, 10 m, 20 m and 40 m to obtain a good depth variation. The current was passed between the outer two electrodes and the resistance was measured between the inner two electrodes. Once the readings were taken the electrodes were moved along the survey transect and readings were taken at constant intervals.

An inverse model of the true resistivity measurements was run for each image line using Res2DINV 3.4 program. Pseudo cross-section was produced and apparent electrical resistivity data was inverted using RES2DINV automated inversion software (Loke and Barker, 1995, 1996).

Three electrical resistivity lines were recorded at Site 1, where line 1 ran in a west to east direction for 230 m through the seepage zone, line 2 (north-west to south- east) was 280 m in length and line 3 measuring 190 m in length, ran perpendicular to the seepage zone (north to south). One line at Site 2 was measured running north-west to south-east, measuring 400 m in length. One line was also measured at Site 3 running in a south-west to north-east direction and measuring 445 m in length (Figure A1.1).

Appendix A: Methodology

A.3 INSTALLATION OF PIEZOMETERS A.3.1 Deep piezometers A series of drilling programs were conducted in the catchment. Deep bores were drilled by the Department of Land and Water Conservation (DLWC) (now known as the Department of Infrastructure, Planning and Natural Resources (DIPNIR)) Dubbo drilling unit. They were installed to identify the groundwater flow direction and the hydrochemistry of various deep fractured aquifers in the catchment. Bores were drilled using a compressed air 6.5-inch percussion hammer rig. No drilling fluids were used during this process and bores are located between 2 to 110 m bgs. Nested PVC pipes with various screened intervals were installed within the boreholes at each site according to the location of water bearing zones. These piezometers were developed by removing 5 well volumes of water and left to settle for ~6 months before hydrochemical analysis.

A.3.2 Shallow piezometers Shallow piezometers were drilled by the DLWC Wellington using a Proline rotary auger drill rig. Sites were nested according to the depth to bedrock and location of perched aquifers in the groundwater system. Shallow piezometers were screened at 5 m bgs, intermediate piezometers between 7 m to 10 m and deeper piezometers between 12 m to 15 m. PVC pipes (65 mm diameter) were installed in the 100 mm borehole after drilling, with 1 m slotted intervals placed at the bottom of the pipe. The hole was gravel packed to approximately 1 m above the screen and sealed with a swelling basalt powder medium to ensure that a representative sample was obtained from the required depth and no mixing occurred. The nested piezometers were drilled in transects with a reference bore located away from the transect to determine groundwater flow direction and relate the background groundwater chemistry in seepage zones. Piezometers were developed by removing 5 well volumes of water and before hydrochemical sampling, piezometers were purged dry and left 24 hours to recharge.

A.4 SOIL SAMPLING Soil samples were collected at textural changes during piezometer installation and were analysed in the field for texture, colour, the presence of mottling, soil

Appendix A: Methodology structure, coherence, soil pH and the presence of pans according to the methodology outlined in Charman and Murphy (1998). These results are presented in Appendix B Table B1, Appendix B. Soil texture was determined using the bolous technique (Charman and Murphy, 1998) and soil colours were determined using a Munsell Colour Company soil chart (1975). Soil pH was determined insitu with a field-probe and diluted hydrochloric acid was used to identify the presence of carbonates. Samples were collected for further laboratory analysis, which included 1:5 soil water analysis, and spectroscopy analysis. Soil water extracts were used to understand water-soluble constituents in the soil sample and thus identify constituents that are likely to become mobilised in the groundwaters as it migrates through the clay-rich sediments.

A.4.1 Soil water extracts Soil water extracts were performed at 1:5 dilutions on soil samples and these methods are outlined by the USA Salinity Laboratory staff (1954) and Rayment and Higgson (1992). The supernatant was extracted from the sample and analysed for Electrical Conductivity (EC), pH and Cl- and major ions. Duplicate analyses were performed on each sample.

The water content of soils was determined gravimetrically, using ~70 g aliquots of soil sample, which were dried at 105°C for 24 hours on a watch glass. Samples are weighed before and after drying to find the percentage of moisture contained within the sample. Once dry, samples were crushed with a mortal and pestle and sieved through 250 μm mesh, and 5 g aliquots of sample were placed into sample containers with 25ml of deionised water, stoppered and placed on the on the shaker for ½ hour. Samples were centrifuged until the supernatant was clear. A second sample was prepared where the supernatant was extracted, filtered and acidified for analysis of major ions using ICP-AES (refer to section A5.2.3). EC1:5 and pH1:5 were measured using an ORION model 290A electrode (calibration details are presented in A5.1.2). Ten ml aliquots of the supernatant solution were diluted up to 25 ml volume with DI water and Cl- was determined using argentiometric methods (details are presented in A5.2.2).

Appendix A: Methodology

A.4.2 Soil spectrometry Spectrometry is the study of light as a function of wavelength that has been emitted, reflected or scattered from a solid, liquid or gas (Clarke, 1999) and gives the user the ability to measure and process the wavelengths of light that is reflected back from the mineral. Portable Infrared Mineral Analyser (PIMA). detects reflected light in the wavelength range from 1300 nm to 2500 nm and identifies hydroxyls, carbonates, sulphates, micas and amphiboles. In this study, the PIMA was used to identify clay minerals present in the shallow aquifer.

Soil samples were air dried for 7 days, then oven dried at 30°C for a further 6 days. This was to ensure the removal of soil water without affecting the clay structure. Soil water exhibits a very broad adsorption feature that tends to mask the absorption features of other minerals in the samples. Drying at low temperatures ensured the removal of adsorbed water and allowed the retention of the interlayer water (Edwards, 2002). After drying, the samples were lightly crushed with a mortal and pestle and placed on glass petri dish. The soils were identified using a PIMA.

This data was analysed in PIMA-View Integrated Spectronics PTY LTD, program (Integrated Spectronics, 1999) that calculates the mineral abundances percentages using curve-matching algorithms. Samples were placed on pre- calibrated Petri dishes and mineral abundances recorded by Edwards (2002).

A.5 SAMPLING GROUNDWATER CHEMISTRY Major ions, minor and trace element chemistry was analysed for groundwater samples from shallow, intermediate and deep fractured aquifers. The shallow groundwater chemistry was characterised from samples taken from over 100 piezometers located in the shallow aquifer and a further 15 water samples from the deeper fractured aquifer systems.

Appendix A: Methodology

A.5.1 Field methods A.5.1.1 Water level measurement and well purging Standing water levels (SWLs) were measured prior to groundwater sampling in the deep and shallow piezometers. Water levels were measured using an electronic sounding device known as a dip meter, which was lowered into the bore to determine accurate water level measurements within each aquifer system.

A submersible pump (GRUNDFOS MP1) was used for sampling deep groundwaters where the pump was lowered into the bore and placed below the air-water interface and above the screen of the bore. The pump was attached to a Honda EM 3000, 240V generator with an output of 3 KV. Three well volumes were purged from the piezometers or until water quality parameters stabilised, prior to hydrochemical sampling to obtain a representative groundwater sample from the aquifer.

Shallow piezometers (<20 m bgs) were purged dry using a submersible bilge pump (WHALE) and left for 24 hours to recover prior to sampling. This procedure ensured that representative groundwater samples were obtained. Groundwater was circulated through a closed cell and monitored for temperature, electrical conductivity (EC), pH, redox potential (Eh) and dissolved oxygen (DO) prior to sample collection. In both pumping techniques water was purged into a flow cell where electrodes where submerged in sample.

A.5.1.2 General parameters Field measurements consisted of all unstable parameters and included temperature, EC, pH, Eh, DO and alkalinity. Temperature and EC were measured using an ORION model 135A conductivity meter. The conductivity readings were checked in the field against freshly prepared KCl standards ranging from 0.0005 M to 0.05 M. Dissolved oxygen was measured using an ORION model 810 oxygen meter. The pH and Eh measurements were made using an ORION model 290A portable pH/concentration meter. A glass electrode with a silver/silver chloride reference was used for the pH measurements, and calibrated against standard buffer solutions of 4.01, 7.00 and 10.01. The Eh measurements were made using

Appendix A: Methodology a platinum redox electrode calibrated in the field against Zobell’s solutions (Nordstrom, 1977; Zobell, 1946). Two sets of EC, pH and Eh meters were used throughout the fieldwork (to eliminate possible error for quality assurance).

A.5.1.3 Spectrophotometers groundwater

2- 2+ - + 3- Chemical analysis of S , Fe , NO3 , NH4 and PO4 where performed in the field, due to the unstable nature of these redox elements, using portable HACH DR/200 spectrophotometer (Hach, 1989). Table A1.1 provides a summary of the methods employed from spectrophotometer analysis. Two cells were used for each sample, (a blank and the sample). Filtered sample was used for chemical analysis and readings are given in mg L-1.

Table A.1 Summary of water analysis methods performed in the field.

Parameter Method Volume mL Titration 0.02M NaOH CO2 50 HCO3 Titration 0.01M HCl 25 Titration 0.02M NaOH CO3 25 2+ Fe HACH Phenanthroline method 50 NO3 HACH Cadmium reduction NO3-N 50 PO4 HACH Ascorbic acid method 50 S2- HACH Methyl blue method 25 NH4 HACH Nestler method NH3-N 25

A.5.1.4 Alkalinity and dissolved CO2

- Titrometric methods were used in the field to determine HCO3 and dissolved CO2 - concentrations of groundwaters (APHA, 1998). Total alkalinity as HCO3 was determined by titrating 0.01 M HCl against 25 mL of sample with bromcresol green indicator and the endpoint was indicated by a change in colour from blue to yellow. Duplicate titrations were performed on the sample.

- The following formula was used to calculate the concentration of HCO3 from the titration performed:

- -1 HCO3 (mg L ) = molarity of HCl × 61.012 × volume of HCl × 1000 eq A.1 Sample volume

Appendix A: Methodology

The amount of acidity due to CO2, CO2(aq) and H2CO3 in groundwater was determined by titrating 0.02M NaOH against 50 mL of sample using phenolphthalein indicator until the first permanent pink colour was observed. At this point, the pH is raised to 8.4 and all the carbon dioxide is converted to bicarbonate. The following formula was used to calculate the concentration of CO2 in groundwater from the titration performed:

-1 CO2(mg L ) = molarity of NaOH ×44.009 ×volume of NaOH ×1000 eq A.2 Sample volume

A.5.2 Laboratory methods A.5.2.1 Silica The concentration of dissolved silica in groundwater samples was determined using a HACH spectrophotometer (HACH, 1989). The molybdate reagent method was used and the reading was given in mg L-1 (Table A.2).

A.5.2.2 Chloride Chloride was determined by an argentometric method outlined in (APHA, 1998).

Standardised AgNO3 was placed into a burette and titrated against 25 mL of the sample with 10 drops of potassium chromate (K2CrO4) indicator and the endpoint was indicated by a colour change from yellow to orange. Duplicate titrations were performed on the sample. Most groundwaters contain high concentrations of Cl- therefore 25 mL aliquots of sample to alkalinity were titrated against 0.141 M

AgNO3 solution. Calculation of the concentration of chloride was determined using the following formula:

-1 3 Cl(mg L ) = molarity of AgNO3 × Volume of AgNO3 × 35.45 × 10 eq A.3 Sample volume

A.5.2.3 Hydrochemical analysis Waters samples were collected for ICP-AES and ICP-MS analysis in 60 ml polyethylene containers, and filtered in the field using 0.45 μm MilliporeTM cellulose acetate membrane filters. Samples were acidified using 0.4 mL of concentrated analytical grade nitric acid to reduce the pH below 2. Acidification was done to

Appendix A: Methodology prevent oxidation reactions and bacterial growth (Appelo and Postma, 1996). Summaries of methods performed in the laboratory are presented in Table A2.

Cations and anions were determined using an Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP–AES) in mg L-1 and trace elements and minors were determined using Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) in μg L-1 in the School of Biological Earth and Environmental Sciences (BEES) at UNSW according to methods outlined in APHA (1998). High salinity samples were diluted (×10) and total S concentrations were converted to sulphate using 2.996 conversion factor.

Table A.2 Summary of water analysis methods performed in the laboratory.

Parameter Method Volume mL SiO2 HACH Molybdate reagent method 50 Cl Argentometric titration AgNO3 0.41M 50 Major and minor ions ICP-AES 60 Trace elements ICP-MS 60 Oxygen-18 isotope mass spectrometry 28 Deuterium isotope mass spectrometry 28 Carbon-13 isotope mass spectrometry 1000 87Sr/86Sr isotope mass spectrometry 28

A.5.2.4 Collection of rainfall samples Rainfall samples were collected during the only two significant rainfall events during 2002, using a modified 50 L plastic drum with a 0.5 m diameter funnel fed to a 1 L schott bottle contained within the drum (Timms, 2002). The plastic drum was located at Binginbar Farm within the catchment and rainfall samples were collected, preserved and refrigerated. Samples were then analysed for majors, minors and trace elements using ICP-AES and ICP-MS. Chloride concentrations were determined by argentiometric titration methods.

A.5.3 Stable isotopes A.5.3.1 Terminology stable isotopes Stable isotope ratios are expressed as standard notation in ‰ relative to SMOW reported in δ notation:

Appendix A: Methodology

δ(‰) = (Rsample - Rstandard)/ Rstandard x 1000‰ VSMOW where R is the isotope ratios 18O/16O or 13C/12C. The δ values are reported relative to the Vienna Standard Mean Ocean Water (VSMOW) for oxygen and relative to VPDB for carbon (Clark and Fritz, 1997). Precision for most waters was within +/- 0.2 ‰ for δ18O, +/-1 ‰ for δ2H and for δ13C +/-2 ‰.

A.5.3.2 Oxygen-18 and deuterium Duplicate isotope samples for 18O and 2H analysis were collected from the flow cell during water sample collection. These waters were collected in 28 ml glass vials that contain rubber sealed caps, which ensured that there was no atmospheric exchange with the water sample. Stable isotopes 18O and 2H were analysed using a dual inlet stable isotope gas ratio mass spectrometer at CSIRO Land and Water Isotope Laboratory in Adelaide. The methodology behind the analysis of δ18O is described by Taylor (1973) and δ2H according to Coleman et al. (1982).

A.5.2.3 Carbon-13 Carbon-13 isotopes of groundwater Dissolved Inorganic Carbon (DIC) was analysed relative to VPDB standard. Carbon-13 was analysed by precipitating all available DIC in the groundwater sample in the field using 25 ml aliquot of saturated SrCl2 under elevated pH conditions of >10, which was achieved by the addition of 10 ml of 11 M NaOH. Once the SrCO3 precipitate was collected and oven-dried for 48 hours, the precipitate was sent to CSIRO Land and Water Isotope Laboratory in Adelaide and analysed using an isotope mass spectrometer.

A.5.4 Radiocarbon isotopes A.5.4.1 Carbon-14 Carbon-14 samples were collected in 1 L plastic bottles. Samples were analysed using an Atomic Mass Spectrometer (AMS), which only requires 5 g of carbon for high accuracy analysis. Groundwater samples were collected and sent to the Rafter Laboratory, Institute of Geological and Nuclear Sciences, New Zealand. The conventional radiocarbon age (CRA) of samples were defined by Stuiver and Polach (1977), which is a measure of the amount of radiocarbon in the sample and

Appendix A: Methodology the approximate ‘true age’ of the sample. Before present (Bp) is referenced to the year 1950 and the percent modern carbon (pMC) radiocarbon content is a percentage of the radiocarbon in a modern standard, corrected to the value it had in 1950. The CRA and pMC in the samples are considered equivalent. 14C activities are referenced to an international standard known as “modern carbon” (mC). The activity of 14C concentration is expressed as a percentage of modern carbon (pMC), where 100 pMC corresponds to 95% of the 14C concentration of NBS oxalic acid standard, which is close to the activity of wood grown in 1890 (Clarke and Fritz, 1997). Standard pMC results are normalised to a δ13C = -25 per mil (Stuiver and Polach, 1977).

A.5.5 Radiogenic isotopes A.5.5.1 87Sr/86Sr isotopic ratios Duplicate samples were collected for 87Sr/86Sr analysis from the flow cell during water sample collection. These waters were collected in 28 ml glass vials that contain rubber sealed caps, which ensured that there was no atmospheric exchange with the water sample. Samples were sent to CSIRO Centre for Isotopes Studies (CIS) at North Ryde, NSW, where the 87Sr/86Sr isotopic ratios were determined using a thermal ionisation mass spectrometer, and using the methodology described by Blacklock (2002). Precision of individual analysis was reported at 0.0010 - 0.0020%.

A.5.3 Quality Control (QC) and Quality Assurance (QA) The development of QA (Quality Assurance) and QC (Quality Control) is to ensure that analytical results reported in the laboratory express the actual concentration of the groundwater insitu (Fetter, 1994). Methods such as looking at the Charge Balance Error (CBE), rinsing equipment, purging piezometers, calibration of equipment and repetition of procedure, all help eliminate possible errors in sampling (Hem, 1984).

In the field, sample containers were cleaned with deionised water, and then rinsed with sample. Equipment used for titration and spectrophotometer analysis was rinsed with DI. Samples for ICP analysis were acidified and unstable elements

Appendix A: Methodology were analysed in the field. Electrodes were cleaned and calibrated every 5 days while in the field, to prevent equipment drift. Titrations were performed twice and immediate titration of bicarbonate and carbon dioxide allowed for accurate results. Water was collected from the piezometer-head, so limited reactions could occur, and samples were refrigerated to prevent changes due to extremes in temperatures. Charge Balance Error percentages (CBE%) for groundwaters collected for this study are presented in Figure A2. Most groundwaters plot within the -/+ 5% field and are considered acceptable for use in this project (Hem, 1989).

EC uS/cm 24000

19200

14400

9600

4800

0 -22.0 -13.6 -5 .2 3.2 11.6 20.0 CBE%

Figure A2 Electrical conductivity (EC) versus CBE% for Spicers Creek catchment groundwaters.

A.5.7 Groundwater and soil data compilation Soil and groundwater data was complied in AQUACHEM (Calmbach, 1997). Statistics were calculated in SPSS version 10.0 (Coakes and Steed, 2001) and correlation coefficients between variables were calculated using the Spearman’s R coefficient for a non-parametric data set. Hydrogeochemical mapping was performed in ARCVIEW 3.3 using the natural breaks in the data set. Saturation indices, ion activities, DIC, total alkalinity and log PCO2 were calculated using the WATEQ4F thermodynamic database in the PHREEQC 2.4.2 (Parkhurst and Appelo, 1999) and inverse modelling was performed in NETPATH (Plummer, et al. 1994).

Appendix B: Soil and groundwater data

APPENDIX B

Appendix B: Soil and groundwater data

B.1 SOIL CHEMISTRY DATA

Sample ID EC1:5 Us/cm pH1:5 Al As B Ca Cd Cl Cu Fe HCO3 K Li Mg Mn Na Ni Pb SO4 Sr Zn s0/0 377 NA <0.01 <0.030.52 34.45 <0.02NA 0.04 <0.010.00 49.65 <0.002880.00 <0.001 825.00 <0.1 <0.05 190.45 0.92 <0.02 s0/0.15 501 7.747 5.50 <0.03 <0.045 70.50 <0.02 699.90 0.00 11.10 305.04 30.35 <0.002115.00 <0.001 281.50 <0.1 <0.05 59.55 1.46 <0.02 s0/0.30 50.6 7.677 <0.01 <0.03 0.30 71.50 <0.02 799.75 0.02 <0.01 338.59 50.00 0.01 151.00 <0.001 455.50 <0.1 <0.05 430.45 1.60 <0.02 s0/0.45 975 7.799 <0.01 <0.03 <0.045 184.00 <0.02 1219.60 0.02 <0.01 448.41 63.50 0.03 240.50 <0.001 535.00 <0.1 <0.05 580.40 3.03 <0.02 s0/0.55 635 8.083 <0.01 <0.03 <0.045 97.50 <0.02 919.70 <0.002 <0.01 375.20 32.40 <0.002 140.00 <0.001 397.00 <0.1 <0.05 114.30 1.51 <0.02 s0/0.65 677 8.075 <0.01 <0.03 <0.045 131.00 <0.02 999.70 <0.002 <0.01 320.29 30.30 <0.002 153.50 <0.001 352.50 <0.1 <0.05 85.95 2.08 <0.02 s0/0.75 637 8.206 <0.01 <0.03 <0.045 110.50 <0.02 949.70 <0.002 <0.01 244.03 25.15 <0.002 150.50 <0.001 319.00 <0.1 <0.05 78.00 2.08 <0.02 S1/0.5 590 7.932 143.50 <0.03 0.98 9.65 <0.02 799.75 0.05 92.00 433.16 30.25 0.07 23.30 <0.001 630.00 <0.1 <0.05 42.15 0.36 <0.02 S1/1.1 555 9.261 27.80 <0.03 <0.045 1.30 <0.02 579.80 <0.002 10.40 549.07 16.90 <0.002 10.70 <0.001 556.00 <0.1 <0.05 3.55 <0.002 <0.02 S1/2.5 527 9.428 15.90 <0.03 <0.045 <0.1 <0.02 459.85 <0.002 0.98 680.24 8.60 <0.002 7.38 <0.001 536.00 <0.1 <0.05 1.34 <0.002 <0.02 S1/3.5 565 9.47 79.00 <0.03 <0.045 <0.1 <0.02 559.85 <0.002 71.50 719.89 11.50 <0.002 17.70 <0.001 595.00 <0.1 <0.05 1.34 <0.002 <0.02 S1/4.8 656 9.528 37.40 <0.03 <0.045 <0.1 <0.02 619.80 <0.002 26.60 753.45 6.99 <0.002 8.43 <0.001 669.00 <0.1 <0.05 5.95 <0.002 <0.02 S1/5.4 537 9.658 54.20 <0.03 <0.045 <0.1 <0.02 399.85 <0.002 47.90 854.11 6.96 <0.002 10.90 <0.001 559.00 <0.1 <0.05 6.05 <0.002 <0.02 S1/7.8 1287 9.495 0.49 <0.03 0.14 1.94 <0.02 2219.30 <0.002 0.37 0.00 8.60 <0.002 10.20 <0.001 1275.00 <0.1 <0.05 81.45 <0.002 <0.02 S1/8.2 814 9.038 25.15 <0.03 <0.045 12.60 <0.021339.80 <0.002 16.85 0.00 17.95 <0.002 13.00 0.07 730.00 <0.1 <0.05 82.35 0.09 <0.02 S1/10.3 584 9.37 26.30 <0.03 <0.045 5.05 <0.02 759.75 <0.002 22.80 332.49 9.80 <0.002 6.75 <0.001 615.00 <0.1 <0.05 43.50 <0.002 <0.02 S2/0 379 6.09 <0.01 <0.03 <0.045 97.50 <0.02 549.85 <0.002 <0.01 36.60 39.75 0.07 58.50 2.76 143.00 <0.1 <0.05 36.60 1.65 <0.02 S2/0.4 370 6.544 <0.01 <0.03 <0.045 88.00 <0.02 599.80 <0.002 <0.01 0.00 19.90 0.04 56.50 0.29 167.50 <0.1 <0.05 34.80 1.59 <0.02 S2/0.8 381 7.194 <0.01 <0.03 <0.045 103.00 <0.02 479.85 <0.002 <0.01 338.59 18.65 <0.002 47.70 <0.001 237.50 <0.1 <0.05 37.65 1.55 <0.02 S2/1.5 381 8.017 <0.01 <0.03 <0.045 68.00 <0.02 519.85 <0.002 <0.01 305.04 17.70 <0.002 43.50 <0.001 298.50 <0.1 <0.05 35.85 1.49 <0.02 S2/1.8 478 8.47 <0.01 <0.03 <0.045 64.00 <0.02 759.75 <0.002 <0.01 198.28 16.85 <0.002 61.50 <0.001 386.00 <0.1 <0.05 37.95 1.94 <0.02 S2/2.1 523 8.421 <0.01 <0.03 <0.045 59.00 <0.02 799.75 <0.002 <0.01 292.84 17.80 <0.002 70.00 <0.001 438.00 <0.1 <0.05 40.85 2.06 <0.02 S2/3 421 8.588 <0.01 <0.03 <0.045 47.40 <0.02 579.80 <0.002 <0.01 286.74 14.50 <0.002 63.50 <0.001 316.00 <0.1 <0.05 31.20 1.43 <0.02 S2/5.8 610 8.388 <0.01 <0.03 <0.045 67.50 <0.02 749.75 <0.002 <0.01 527.72 16.70 <0.002 84.00 <0.001 462.50 <0.1 <0.05 47.25 2.05 <0.02 S2/6 371 8.398 <0.01 <0.03 <0.045 54.50 <0.02 479.85 <0.002 <0.01 277.59 17.65 <0.002 50.40 <0.001 261.00 <0.1 <0.05 27.75 1.11 <0.02 S2/6.8 310 8.387 <0.01 <0.03 <0.045 40.05 <0.02 399.90 <0.002 <0.01 289.79 18.45 <0.002 41.20 <0.001 244.50 <0.1 <0.05 21.60 0.85 <0.02 S2/7.5 373 8.407 2.06 <0.03 <0.045 57.50 <0.02 499.85 <0.002 <0.01 274.54 18.75 <0.002 51.00 <0.001 267.50 <0.1 <0.05 28.65 1.16 <0.02 2 Appendix B: Soil and groundwater data

Sample ID EC1:5 Us/cm pH1:5 Al As B Ca Cd Cl Cu Fe HCO3 K Li Mg Mn Na Ni Pb SO4 Sr Zn S2/8.3 290 8.452 5.35 <0.03 <0.045 28.40 <0.02 399.90 <0.002 5.70 366.05 24.05 <0.002 28.00 <0.001 306.50 <0.1 <0.05 18.30 0.39 <0.02 S2/9.3 336 8.407 7.80 <0.03 <0.045 30.40 <0.02 459.85 <0.002 8.20 274.54 25.80 <0.002 30.25 <0.001 302.50 <0.1 <0.05 20.15 0.42 <0.02 S2/10.5 314 8.766 6.85 <0.03 <0.045 25.10 <0.02 419.85 <0.002 7.55 234.88 22.85 <0.002 25.95 <0.001 276.50 <0.1 <0.05 16.50 0.31 <0.02 S2/12.3 444 8.417 <0.01 <0.03 <0.045 47.00 <0.02 659.80 <0.002 <0.01 137.27 23.50 <0.002 46.10 <0.001 340.00 <0.1 <0.05 31.50 0.91 <0.02 S3/0.3 84.1 6.484 28.25 <0.03 0.46 28.45 <0.02 99.95 0.26 277.50 207.43 48.40 0.19 18.75 1.62 55.00 <0.1 <0.05 18.30 0.17 <0.02 S3/1.3 86.1 5.994 20.15 <0.03 0.38 21.95 <0.02 99.95 0.17 250.50 228.78 47.15 0.19 21.60 1.40 62.50 <0.1 <0.05 10.00 0.10 <0.02 S3/1.8 34.1 7.61 247.00 <0.03 0.37 15.60 <0.02 79.95 0.03 171.00 115.92 28.35 0.07 19.35 1.14 26.60 <0.1 <0.05 4.05 <0.002 <0.02 S3/2.6 136.2 8.163 19.30 <0.03 <0.045 56.00 <0.02 59.95 <0.002 7.65 323.34 27.20 0.00 8.85 <0.001 68.00 <0.1 <0.05 8.20 0.16 <0.02 S3/3.8 118.2 8.812 65.00 <0.03 <0.045 32.25 <0.02 99.95 0.01 75.50 234.88 25.65 0.01 14.55 0.88 76.00 <0.1 <0.05 4.35 0.14 <0.02 S3/6.2 106.1 8.665 19.50 <0.03 <0.045 28.90 <0.02 79.95 <0.002 14.85 195.23 18.20 <0.002 11.40 <0.001 62.00 <0.1 <0.05 4.20 0.11 <0.02 S3/8 218 9.065 27.90 <0.03 <0.045 24.45 <0.02 239.95 0.12 126.00 369.10 21.40 0.02 25.50 2.57 209.00 <0.1 <0.05 7.50 0.17 <0.02 S3/9 132.7 8.979 35.55 <0.03 <0.045 27.35 <0.02 139.95 0.01 43.00 210.48 21.90 <0.002 20.70 1.17 88.50 <0.1 <0.05 4.60 0.26 <0.02 S3/10.5 305 8.777 6.60 <0.03 <0.045 34.15 <0.02 399.85 <0.002 15.60 225.73 25.40 <0.002 36.95 0.03 226.50 <0.1 <0.05 10.90 0.69 <0.02 S3/11 275 8.696 4.07 <0.03 <0.045 27.05 <0.02 399.85 <0.002 18.25 161.67 21.55 <0.002 32.60 0.02 219.50 <0.1 <0.05 9.35 0.57 <0.02 S3/12.3 213 8.422 29.30 <0.03 <0.045 47.45 <0.02 299.90 <0.002 36.25 128.12 28.50 <0.002 23.80 0.34 131.00 <0.1 <0.05 8.95 0.45 <0.02 S4/0.3 101.6 6.891 46.45 <0.03 <0.045 47.95 <0.02 59.95 <0.002 30.15 195.23 49.25 <0.002 13.30 0.43 14.70 <0.1 <0.05 24.30 0.24 <0.02 S4/1 25 7.834 38.55 <0.03 0.69 17.50 <0.02 39.95 0.02 102.00 155.57 27.90 0.06 10.95 0.06 31.45 <0.1 <0.05 9.65 0.05 <0.02 S4/2.1 108.3 8.036 16.75 <0.03 <0.045 38.85 <0.02 59.95 <0.002 6.90 231.83 21.85 <0.002 9.40 <0.001 54.00 <0.1 <0.05 6.25 0.13 <0.02 S4/3 115.8 7.953 9.55 <0.03 <0.045 55.00 <0.02 69.95 <0.002 3.54 335.54 25.90 <0.002 13.20 <0.001 71.50 <0.1 <0.05 8.45 0.27 <0.02 S4/3.2 115.1 8.26 12.05 <0.03 <0.045 41.60 <0.02 69.95 <0.002 8.40 265.38 16.40 <0.002 10.30 <0.001 71.00 <0.1 <0.05 5.35 0.16 <0.02 S4/3.9 108 8.397 20.25 <0.03 <0.045 33.40 <0.02 39.95 <0.002 16.80 289.79 15.40 <0.002 8.55 0.34 73.50 <0.1 <0.05 4.70 0.07 <0.02 S4/4.1 95.5 8.437 12.40 <0.03 <0.045 33.85 <0.02 29.95 <0.002 10.70 332.49 17.35 <0.002 9.20 <0.001 80.50 <0.1 <0.05 4.70 0.09 <0.02 S4/5.5 75 7.927 16.60 <0.03 <0.045 27.25 <0.02 29.95 <0.002 15.40 338.59 12.95 <0.002 12.05 0.05 89.50 <0.1 <0.05 7.60 0.11 <0.02 S4/5.7 133.3 8.588 7.65 <0.03 <0.045 24.50 <0.02 79.95 <0.002 19.55 326.39 12.80 <0.002 22.70 0.04 99.50 <0.1 <0.05 6.40 0.05 <0.02 S4/5.8 134.4 8.13 9.00 <0.03 <0.045 56.50 <0.02 79.95 <0.002 5.65 369.10 20.55 <0.002 14.85 <0.001 90.00 <0.1 <0.05 8.55 0.38 <0.02 S5/0.2 257 7.733 4330.00 <0.03 2.21 32.90 <0.02 379.90 0.60 710.00 698.54 147.00 1.56 107.00 5.85 206.50 0.82 <0.05 48.90 2.09 0.93 S5/0.7 165 7.926 85.00 <0.03 1.65 24.60 <0.02 199.95 0.48 540.00 948.67 117.00 1.28 71.00 2.48 302.50 0.77 <0.05 97.20 1.35 0.39 S5/1.3 343 8.703 41.20 <0.03 <0.045 25.00 <0.02 279.90 <0.002 19.45 542.97 9.95 0.03 11.55 <0.001 361.50 <0.1 <0.05 66.30 0.23 <0.02 S5/2.2 310 8.94 20.40 <0.03 <0.045 6.02 <0.02 209.95 <0.002 0.57 579.58 6.98 <0.002 7.60 <0.001 344.00 <0.1 <0.05 30.30 <0.002<0.02 S5/3.1 322 9.025 45.55 <0.03 <0.045 13.15 <0.02 219.95 <0.002 23.05 622.28 9.00 0.03 10.55 <0.001 361.50 <0.1 <0.05 52.20 0.23 <0.02 3 Appendix B: Soil and groundwater data

Sample ID EC1:5 Us/cm pH1:5 Al As B Ca Cd Cl Cu Fe HCO3 K Li Mg Mn Na Ni Pb SO4 Sr Zn S5/3.5 325 9.012 46.55 <0.03 <0.045 8.90 <0.02 299.50 <0.002 19.90 536.87 8.40 0.05 11.10 <0.001 380.00 <0.1 <0.05 40.80 0.25 <0.02 S5/4 327 8.567 24.20 <0.03<0.045 13.10 <0.02259.90 <0.002 2.70 469.76 9.90 0.01 8.95 <0.001 330.50 <0.1 <0.05 46.80 0.18 <0.02 S6/0 220 7.733 190.00 <0.03 0.45 16.20 <0.02 199.95 0.12 113.00 305.04 29.90 0.14 15.55 0.99 230.00 <0.1 <0.05 105.00 0.17 <0.02 S6/0.1 206 7.714 915.00 <0.03 1.34 28.90 <0.02 199.95 0.36 505.00 677.19 88.50 0.96 49.15 1.78 237.00 0.66 <0.05 62.55 0.97 0.18 S6/0.6 213 7.883 36.70 <0.03 2.15 30.15 <0.02 239.95 0.60 675.00 884.62 139.00 1.41 83.00 2.61 246.50 0.87 <0.05 85.50 1.22 0.76 S6/1.2 233 8.135 1335.00 <0.03 2.63 38.75 <0.02 239.95 0.65 730.00 1220.16 159.50 1.52 113.00 1.96 287.00 0.83 <0.05 61.05 1.65 1.06 S6/2.1 199.3 8.534 5750.00 <0.03 3.53 54.00 <0.02 199.95 0.70 850.00 1622.81 205.00 2.09 161.00 2.70 274.50 1.18 <0.05 40.05 2.47 1.51 S6/2.3 233 8.248 1230.00 <0.03 1.55 35.20 <0.02 209.95 0.28 510.00 1024.93 79.50 0.89 90.00 1.58 284.50 0.43 <0.05 40.20 1.44 0.33 S6/3.1 199.3 8.688 132.00 <0.03<0.045 11.85 <0.02 199.95 <0.002 94.00 305.04 21.65 0.12 17.00 0.90 203.00 <0.1 <0.05 33.75 0.23 <0.02 S7/0.2 346 6.952 456.50 <0.03 0.12 65.50 <0.02 409.85 0.11 204.00 323.34 49.65 0.31 21.70 0.27 283.50 <0.1 <0.05 86.10 0.59 <0.02 S7/0.8 244 8.275 80.50 <0.03 0.21 36.20 <0.02 259.90 <0.002 34.95 195.23 22.15 0.05 9.80 <0.001 208.00 <0.1 <0.05 81.60 0.27 <0.02 S7/1.7 208 8.438 336.00 <0.03 0.33 24.20 <0.02 239.95 <0.002163.00 289.79 34.35 0.23 23.50 0.20 200.50 <0.1 <0.05 58.35 0.56 <0.02 S7/2.5 175.4 8.224 493.00 <0.03 0.59 17.60 <0.02 159.95 0.02 228.00 433.16 35.30 0.31 31.50 1.19 183.50 <0.1 <0.05 34.35 1.21 <0.02 S7/3.1 189.3 8.137 510.00 <0.03 0.54 14.30 <0.02 159.95 0.02 243.50 509.42 35.70 0.39 34.90 1.35 209.50 <0.1 <0.05 36.60 1.51 <0.02 S7/3.4 187.4 8.653 478.50 <0.03 0.44 9.80 <0.02 219.95 0.08 184.00 402.65 40.20 0.55 34.05 0.78 212.00 0.23 <0.05 34.35 4.04 <0.02 S7/4.1 260 7.917 188.50 <0.03<0.045 2.28 <0.02 259.90 0.04 55.50 274.54 22.30 0.26 15.70 0.12 252.00 <0.1 <0.05 53.70 1.63 <0.02 S7/5 278 8.269 157.00 <0.03 <0.045 3.43 <0.02 299.90 <0.002 28.10 228.78 19.80 0.13 10.30 <0.001 268.50 <0.1 <0.05 47.25 0.46 <0.02 S7/6.8 137.8 8.214 42.10 <0.03 <0.045 <0.1 <0.02 99.95 <0.002 18.15 231.83 23.35 0.28 7.95 <0.001 134.00 <0.1 <0.05 22.05 0.51 <0.02 S7/7.5 136.5 7.927 211.50 <0.03 <0.045 <0.1 <0.02 219.95 <0.002 39.70 9.15 19.30 0.28 7.10 <0.001 138.50 <0.1 <0.05 35.70 1.51 <0.02 S7/9 154.2 8.293 60.50 <0.03<0.045 <0.1 <0.02 239.95 <0.002<0.01 0.00 7.45 0.09 1.17 <0.001 140.50 <0.1 <0.05 37.35 <0.002<0.02 S7/10.7 150.7 7.947 15.60 <0.03<0.045 <0.1 <0.02 219.95 <0.002<0.01 0.00 7.80 0.06 0.80 <0.001 150.00 <0.1 <0.05 44.10 <0.002<0.02 S8/0.2 342 7.902 14.65 <0.03 <0.045 34.80 <0.02 499.85 <0.002 30.80 73.21 13.25 0.05 12.90 <0.001 303.50 <0.1 <0.05 48.90 0.32 <0.02 S8/0.6 126.9 7.4 118.00 <0.03 0.72 14.15 <0.02 199.95 0.08 282.50 244.03 42.20 0.53 33.90 0.75 131.50 0.41 <0.05 34.50 0.91 <0.02 S8/1.2 192.7 7.923 33.80 <0.03 0.27 3.95 <0.02 119.95 <0.002 130.50 131.17 24.45 0.42 18.30 0.49 83.00 0.31 <0.05 18.00 0.44 <0.02 S8/2.1 108.7 7.855 462.50 <0.03 0.97 17.45 <0.02 119.95 0.07 366.00 390.45 38.50 0.62 45.40 4.14 118.50 0.45 <0.05 45.30 3.36 0.06 S8/2.4 74.2 8.491 13.00 <0.03 <0.045 38.70 <0.02 99.95 <0.002 <0.01 359.95 7.60 0.01 16.80 <0.001 138.00 <0.1 <0.05 36.30 0.57 <0.02 S8/2.9 143.4 8.314 20.95 <0.03 <0.045 5.15 <0.02 119.95 <0.002 31.50 213.53 11.90 0.13 12.60 <0.001 127.50 <0.1 <0.05 15.45 0.75 <0.02 S12/0.6 792 7.68 0.91 <0.03 0.16 120.50 <0.02 1279.60 0.01 <0.01 122.02 67.00 <0.002 85.50 <0.001 565.00 <0.1 <0.05 60.30 1.49 <0.02 S12/1.2 507 8.69 <0.01 <0.03 0.19 51.50 <0.02 699.75 <0.002 <0.01 347.75 61.00 <0.002 45.70 <0.001 427.00 <0.1 <0.05 47.40 0.70 <0.02 S12/2 492 8.741 1.68 <0.03 0.16 34.70 <0.02 679.75 <0.002 <0.01 305.04 52.50 <0.002 46.10 <0.001 415.00 <0.1 <0.05 41.50 0.52 <0.02 4 Appendix B: Soil and groundwater data

Sample ID EC1:5 Us/cm pH1:5 Al As B Ca Cd Cl Cu Fe HCO3 K Li Mg Mn Na Ni Pb SO4 Sr Zn S12/2.5 561 8.401 <0.01 <0.03 <0.045 31.80 <0.02 799.75 <0.002 <0.01 329.44 51.50 <0.002 59.50 <0.001 483.00 <0.1 <0.05 41.85 0.58 <0.02 S12/3 742 8.081 <0.01 <0.03 <0.045 55.50 <0.02 1119.65 0.01 <0.01 320.29 66.00 <0.002 94.50 <0.001 590.00 <0.1 <0.05 51.15 1.05 <0.02 S12/4.7 668 8.729 <0.01 <0.03 <0.045 15.25 <0.02 1039.70 <0.002 <0.01 256.23 38.25 <0.002 79.50 <0.001 605.00 <0.1 <0.05 52.50 0.53 <0.02 S12/8.7 477 8.654 <0.01 <0.03 <0.045 26.80 <0.02 649.75 <0.002 <0.01 274.54 34.35 <0.002 99.50 <0.001 301.50 <0.1 <0.05 33.45 0.60 <0.02 S16/0.4 180.4 7.525 229.50 <0.03 1.68 44.20 <0.02 159.95 0.08 135.00 158.62 201.00 0.20 15.90 <0.001 16.65 <0.1 <0.05 108.00 0.51 <0.02 S16/0.8 70.6 7.31 3.64 <0.03 0.08 4.35 <0.02 69.95 <0.002 <0.01 0.00 7.80 <0.002 7.90 <0.001 40.30 <0.1 <0.05 48.30 <0.002 <0.02 S16/1 110.3 6.406 5.60 <0.03 0.12 1.03 <0.02 189.95 <0.00213.90 0.00 5.85 0.03 10.00 <0.001 91.50 <0.1<0.05 29.70 <0.002<0.02 S16/1.3 146 7.752 13.90 <0.03 0.20 <0.1 <0.02 199.95 <0.00238.85 9.15 8.50 0.15 8.35 <0.001 132.50 <0.1 <0.05 41.85 0.04 <0.02 S16/1.8 342 7.861 22.95 <0.03 <0.045 18.20 <0.02 339.90 <0.002 <0.01 536.87 4.54 0.02 21.15 <0.001 377.50 <0.1 <0.05 36.60 0.28 <0.02 S16/2.4 212 8.286 43.90 <0.03 <0.045 15.75 <0.02 249.90 <0.002 <0.01 747.35 6.15 0.06 18.85 <0.001 404.00 <0.1 <0.05 37.50 0.46 <0.02 S16/2.6 409 8.47 150.00 <0.03<0.045 21.15 <0.02 419.85 0.04 8.55 619.23 13.55 0.15 25.50 <0.001 447.50 <0.1 <0.05 46.95 1.47 <0.02 S16/3 415 8.511 102.50 0.04 <0.045 18.35 <0.02 459.85 0.04 8.70 427.06 17.90 0.09 23.15 <0.001 401.00 <0.1 <0.05 48.15 0.67 <0.02 S16/3.2 38.4 8.174 121.50 <0.03 0.14 <0.1 <0.02 369.90 <0.002 11.25 167.77 13.50 0.13 6.85 <0.001 297.50 <0.1 <0.05 31.95 0.25 <0.02 S16/3.8 179.1 7.631 22.50 <0.03<0.045 <0.1 <0.02 349.90 <0.002<0.01 311.14 5.80 0.03 2.47 <0.001 352.50 <0.1 <0.05 33.90 <0.002<0.02 S16/4 312 8.095 92.50 <0.03 <0.045 <0.1 <0.02 389.90 <0.002 7.90 189.07 15.75 0.19 3.97 <0.001 326.50 <0.1 <0.05 42.00 0.49 <0.02 Ions in mg kg-1

5 Appendix B: Soil and groundwater data

B.2 PHYSICAL SOIL DATA

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description Light yellowish S0/0 0 11.1 Light clay brown 10YR 6/4 NA abundant crust Carbonate-rich crust, groundwater discharge zone. S0/0.15 0.15 19.5 clayey sand Yellowish brown 10YR 5/6 NA NA clay gravel Calcareous clay with silt, lithic fragments and quartz grains. S0/0.3 0.3 33.6 clayey sand Reddish brown 10YR 5/6 NA NA clay gravel Angular quartz grains present. Dark yellowish S0/0.45 0.45 38 clayey sand brown 10YR 4/4 NA NA clay gravel Contains lithic fragments and larger angular quartz grains. S0/0.55 0.55 29.1 sandy clay Very pale brown 10YR 6/4 NA NA clay sand With sand sized quartz and lithic fragments. S0/0.65 0.65 32.5 clayey sand Very pale brown 10YR 7/4 NA NA sand clay Weathered sandstone bedrock contact, encountered groundwater. weathered S0/0.75 0.75 31.4 clayey sand Very pale brown 10YR 7/3 NA NA sandstone As above. light sandy clay S1/0 0 NA loam dusky red 10YR 3/3 4.75 absent loam clay Contains plant roots, high organic matter, Fe nodules. S1/0.5 0.5 22.7 light clay red 2.5YR 4/6 7.5 absent clay Oxidised well-drained sediments. S1/0.7 0.7 22 light clay yellowish red 5YR 5/6 8.25 present clay Black nodules Fe/Mn concretions. S1/1.1 1.1 21.4 sandy clay strong brown 7.5YR 5/6 7.73 abundant clay gravel Contains carbonate lithic fragments. S1/1.5 1.5 20.3 light clay strong brown 7.5YR 5/6 7.7 abundant clay Angular carbonate lithic fragments. very S1/2.5 2.5 19.6 sandy clay brown 7.5YR 5/4 8.12 abundant clay gravel Contains colluvium with large white lithic fragments, gravel layer. very S1/2.7 2.7 19.3 sandy clay brownish yellow 10YR 6/6 7.93 abundant clay gravel Large limestone lithic fragments with gravel sized grains. S1/3.5 3.5 23 clay sand strong brown 7.5YR 5/6 7.5 high clay sand Decrease in lithic fragments, increase in clay content S1/4.8 4.8 30.4 sandy clay brownish yellow 10YR 6/8 7.5 high clay gravel Saturated clay with fine-grained lithic fragments, encountered groundwater. medium heavy S1/5.4 5.4 22.2 clay yellowish brown 10YR 5/4 NA high clay With silica-rich sand grains. S1/7.8 7.8 31.64 medium clay Yellow brown 10YR 5/4 NA high clay Groundwater strike. S1/8.2 8.2 26.3 medium clay brown 7.5YR 5/6 NA high clay sand contains sand and gravel sized grains medium heavy light yellowish S1/10.2 10.2 25.7 clay brown 10YR 6/4 NA low clay Saturated with lithic fragments throughout. S1/10.3 10.3 22.4 weathered shale brown 10YR5/3 NA medium clay High water flow, encountered bedrock. S2/0 0 13.4 clay loam dusky red 10R 3/3 5.52 absent clay loam Contains high organic matter.

6 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description S2/0.4 0.4 17.9 light clay Dark red 10R 3/6 6 absent clay With angular ironstone and quartz grains. S2/0.8 0.8 22.9 sandy clay Strong brown 7.5YR 4/6 6.25 present clay gravel With angular carbonate fragments and colluvium. S2/1.5 1.5 24.1 sandy clay Strong brown 7.5YR 5/6 7.61 present clay gravel Large carbonate-rich fragments and colluvium. S2/1.8 1.8 39.2 sandy clay Strong brown 7.5YR 5/6 7.17 present clay gravel Saturated, encountered groundwater. S2/2.1 2.1 45.6 sandy clay Strong brown 7.5YR 5/6 7.14 present clay gravel Colluvium with large angular rock fragments present. dark yellowish S2/3 3 29.3 sandy clay brown 10YR 4/4 NA present gravel clay High lithic content with some pebbles sized fragments. dark yellowish S2/5.8 5.8 55.9 clayey sand brown 10YR 4/6 7.07 present sand clay gravel Saturated clay with small angular lithic fragments. medium heavy dark yellowish S2/6 6 31.1 clay brown 10YR 4/4 NA abundant clay Very stiff clay layer. medium heavy S2/6.8 6.8 24.6 clay dark brown 10YR 3/4 NA abundant clay High water flow 3.3 dS/cm with angular carbonate fragments throughout. dark reddish S2/7.5 7-Jan 26.3 medium clay brown 2.5YR 3/4 7.25 abundant gravel clay Colluvium with lithic fragments of carbonate and quartz gravel. medium heavy dark yellowish S2/8.3 8.3 30.9 clay brown 10YR 4/4 NA present clay Angular sand sized rock fragments present. medium heavy S2/9.3 9.3 30 clay brown 10YR 3/4 NA minor clay With minor sand sized particles and rock fragments. dark yellowish S2/10.5 10.5 29.1 medium clay brown 10YR 4/4 NA present clay Angular gravel fragments, groundwater pH of 7.23. light yellowish S2/10.8 10.8 29.5 medium clay brown 10YR 4/6 NA present clay Heavy clay seal dark yellowish S2/12.3 12.3 57.9 medium clay brown 10YR 4/4 6.92 present clay Confining clay layer. light sand clay S3/0 0 7.3 loam Dark red 2.5YR 3/6 NA absent loam Organic matter and plant roots present. light sand clay S3/0.3 0.3 8 loam red 2.5YR 4/6 NA absent loam Organic matter with decrease in plant root content. S3/0.6 0.6 8.2 clay loam red 2.5YR 4/6 NA low loam clay Contains lithic fragments. dark reddish S3/1.3 1.3 13.4 clay loam brown 2.5YR 3/4 NA absent clay loam White mottling apparent with shale lithic fragments. S3/1.8 1.8 sandy clay yellowish brown 10YR 5/4 NA absent sand clay Sand sized particles with shale fragments present. S3/2.1 2.1 12.5 sandy clay yellowish brown 10YR 5/4 NA absent sand clay White clay lenses with large shale fragments. S3/2.6 2.6 8 sandy clay Strong brown 7.5YR 5/6 NA present clay sand gravel Large angular shale fragments present. dark yellowish S3/3.2 3.2 10.6 sandy clay brown 10YR 4/6 NA abundant sand clay gravel Contains Fe/Mn nodules with angular shale fragments.

7 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description S3/3.8 3.8 10.3 sandy clay yellowish brown 10YR 5/8 NA abundant sand clay White clay lenses present. S3/4.2 4.2 12.5 sandy clay yellowish brown 10YR 5/6 NA abundant sand clay gravel Rounded pebble sized grains. dark yellowish very S3/6.2 6.2 12.5 sandy clay brown 10YR 4/4 NA abundant sand gravel Sandy sediments with rounded pebbles. dark yellowish very S3/7.5 7.5 13.4 sandy clay brown 10YR 4/6 NA abundant gravel clay sand Rounded gravel with increase in moisture. dark yellowish extremely Increase in clay content & moisture, white clay lenses present with angular S3/8 8 16.8 sandy clay brown 10YR 4/4 NA high clay sand gravel. dark yellowish extremely S3/9 9 13.7 sandy clay brown 10YR 4/4 NA high sand clay Unconsolidated sand and decrease in moisture. dark yellowish extremely S3/9.5 9.5 15 sandy clay brown 10YR 4/4 NA high clay sand White lithic fragments present. S3/10.3 10.3 22.3 light clay dark brown 10YR 4/3 NA present clay Moisture increase. dark yellowish S3/10.5 10.5 35 medium clay brown 10YR 4/4 NA absent clay gravel Encountered groundwater. S3/11 11 31.3 medium clay yellowish brown 10YR 5/4 NA absent clay Gravel and sand with angular shale fragments present. dark yellowish S3/12.1 12.1 29.2 medium clay brown 10YR 4/4 NA absent clay With angular gravel fragments, saturated. S3/12.3 12.3 23.4 light clay yellowish brown 10YR 5/6 NA present weathered shale Large angular shale and sandstone fragments. S4/0 0 8.1 clay loam strong brown 7.5YR 4/6 NA absent loam With plant roots present. S4/0.3 0.3 13.4 light clay Dark red 2.5YR 4/6 NA absent clay Contains white lithic fragments and Fe/Mn nodules. S4/0.6 0.6 13.4 Silty clay loam Dark red 2.5YR 4/6 NA absent clay loam Increase in moisture content. dark reddish S4/1 1 15.6 light clay brown 2.5YR 3/4 NA absent clay Contains white angular rock fragments. S4/2.1 2.1 17.2 light clay strong brown 7.5YR 4/6 NA absent clay Contains Fe/Mn nodules with angular lithic fragments present, moist. S4/2.7 2.7 15.5 sandy clay dark brown 7.5YR 4/4 NA abundant clay sand gravel Large angular pebbles present with Fe/Mn nodules. S4/3 3 16.6 sandy clay strong brown 7.5YR 4/6 NA present clay gravel Angular white shale lithic fragments present. dark yellowish S4/3.2 3.2 12 sandy clay brown 10YR 4/4 NA abundant clay gravel Large angular black and white pebbles with colluvium present. dark yellowish very S4/3.9 3.9 10.3 sandy clay brown 10YR 4/4 NA abundant clay gravel Carbonaceous angular lithic fragments. dark yellowish very S4/4.1 4.1 11.3 sandy clay brown 10YR 4/6 NA abundant clay gravel With occasional lithic fragment. dark yellowish very Contains white clay lenses with weathered shale and angular ironstone S4/4.3 4.3 9.3 sandy clay brown 10YR 4/4 NA abundant clay gravel pebbles throughout.

8 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description dark yellowish very S4/5.2 5.2 10.9 light clay brown 10YR 4/4 NA abundant clay Sulphide odour present. S4/5.5 5.5 10.7 sandy clay yellowish brown 10YR 5/4 NA abundant clay gravel Fe oxides present. S4/5.7 5.7 8.3 light clay yellowish brown 10YR 5/6 NA abundant weathered shale Angular shale lithic fragments, weathered bedrock. Light medium dark yellowish S4/5.8 5.8 16.5 clay brown 10YR 4/4 NA present shale/sandstone Increase in moisture. S5/0 0 13.6 medium clay yellowish red 5YR 4/6 8.07 absent clay Contains Fe nodules. S5/0.2 0.2 18.8 heavy clay Strong brown 7.5YR 5/8 7.3 absent clay Impermeable and saturated. S5/0.4 0.4 18 heavy clay Strong brown 7.5YR 4/6 7.27 absent clay With angular lithic fragments. S5/0.7 0.7 17.3 heavy clay Strong brown 7.5YR 4/6 6.91 absent clay Fe/Mn nodules present. S5/1.3 1.3 17 medium clay yellowish brown 10YR 5/6 7.35 abundant clay gravel Large carbonaceous rich and ironstone fragments. very S5/1.8 1.8 17.8 medium clay yellowish brown 10YR 5/6 7.77 abundant clay gravel As above. S5/2.2 2.2 16.9 medium clay yellowish brown 10YR 5/6 8.12 abundant clay gravel Colluvium. very S5/2.3 2.3 17.1 sand clay yellowish brown 10YR 5/6 8.07 abundant sand clay Increase in carbonaceous fragments. S5/3.1 3.1 17.8 sand clay Reddish brown 5YR 4/4 7.95 abundant clay gravel Contains gravel throughout. dark yellowish S5/3.5 3.5 15.8 sand clay brown 10YR 4/4 7.7 abundant sand clay gravel White clay lenses present. dark yellowish S5/3.8 3.8 26.6 medium clay brown 10YR 5/6 NA absent clay As above but increase in moisture. Light medium S5/4 4 24.1 clay light grey 10YR 6/1 NA minor shale Bedrock sandstone and shale. dark yellowish S6/0 0 17.8 light clay brown 10YR 3/4 7.32 absent clay Saturated, FeS precipitate on surface, groundwater discharge. medium heavy S6/0.1 0.1 19.3 clay Reddish brown 5YR 4/4 7.23 absent clay Saturated, contains lithic fragments of ironstone. medium heavy S6/0.6 0.6 27.2 clay yellowish red 5YR 5/6 7.57 absent clay Decrease in lithic fragments. S6/1.2 1.2 24.6 heavy clay brownish yellow 10YR 6/8 7.66 absent clay Contains quartz fragments and gravel. S6/2.1 2.1 23.7 heavy clay brownish yellow 10YR 6/8 7.52 absent clay Contains Fe/Mn nodules. S6/2.3 2.3 23 heavy clay brownish yellow 10YR 6/6 7.3 absent clay Anoxic environment with grey mottling throughout clay. Light medium weathered S6/2.9 2.9 25 clay yellowish brown 10YR 5/6 7.31 absent sandstone Weathered bedrock, large well-rounded quartz grains within a clay matrix. S6/3.1 3.1 19.8 light medium brown 10YR 5/3 7.41 absent sandstone Anoxic environment. 9 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description clay dark yellowish S7/0 0 25.6 clay loam brown 10YR 3/6 5.54 absent clay loam High moisture content, plant roots are evident. light medium S7/0.2 0.2 21.2 clay dark brown 7.5YR 4/4 7.06 absent clay High moisture content, groundwater discharge zone. light medium S7/0.5 0.5 23.3 clay yellowish red 5YR 4/6 6.93 absent clay Increase in moisture S7/0.8 0.8 23 medium clay strong brown 7.5YR 5/8 7.03 absent clay S7/1.7 1.7 16.4 sandy clay yellowish brown 10YR 5/6 6.97 absent clay sand Contains lithic fragments and Fe/Mn nodules. Contains quartz grains and lithic fragments of mixed origin, sulphides odour S7/2.5 2.5 12.7 sandy clay yellowish brown 10YR 5/4 7.02 absent sand clay present. S7/2.9 2.9 14.5 sandy clay yellowish brown 10YR 5/6 7.06 absent sand clay Contains angular quartz grains. S7/3.1 3.1 16.3 sandy clay yellowish red 5YR 4/6 7.27 absent clay gravel Increase in clay content with ironstone and Fe/Mn nodules present. S7/3.3 3.3 22.1 sandy clay strong brown 7.5YR 5/6 7.31 absent clay gravel Increase in moisture S7/3.4 3.4 22.1 light clay brown 10YR 5/3 7.37 absent clay Saturated containing shale lithic fragments. S7/4 4 28.2 sandy clay brown 7.5YR 5/4 7.5 absent clay gravel Saturated with large angular pebbles present throughout. S7/4.1 4.1 40.2 light clay brown 7.5YR 5/4 7.46 absent clay Weathered shale material. S7/5 5 23.3 sandy clay Weak red 2.5YR 5/2 7.37 absent clay sand Saturated with gravel-sized grains. S7/6.8 6.8 24.1 sandy clay Weak red 2.5YR 5/2 7.19 absent clay sand Decrease in gravel content, saturated. S7/7.5 7.5 22.5 sandy clay Reddish brown 5YR 5/4 7.08 absent clay sand Ironstone fragments present, saturated. S7/9 9 23.1 sandy clay Reddish brown 2.5YR 5/4 6.73 absent clay sand Mottling with ironstone band within sandstone. S7/10.2 10.2 20.6 sand clay Weak red 7.5YR 4/2 6.77 absent sand clay Ironstone with weathered sandstone. S7/10.7 10.7 25 sand clay red 7.5YR 4/4 6.7 absent sandstone Saturated with larger lithic fragments, bedrock contact. S8/0.2 0.2 15.8 sandy clay Red 2.5YR 4/6 6.31 absent sand clay Moist with angular sand grains. S8/0.6 0.6 16.7 sandy clay yellowish brown 10YR 5/6 6.47 absent sand clay Very sandy, mottled yellow & brown. light yellowish S8/0.9 0.9 13.3 clayey sand brown 10YR 6/4 7.02 absent sand Sandy with white clay lenses, unconsolidated. S8/1.2 1.2 8.5 clayey sand light grey 10YR 7/2 7.31 absent sand Unconsolidated sand with small white clay lenses, uniform grain size. Increase in clay content with angular quartz grains, lithic fragments and Fe/Mn S8/1.5 1.5 13.5 sandy clay yellowish brown 10YR 5/6 7.23 absent sand clay nodules. S8/2.1 2.1 10.7 sandy clay dark yellowish 10YR 4/4 7.32 absent clay gravel sand White clay lenses present with large angular rock fragments. 10 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description brown

S8/2.4 2.4 8.2 sandy clay Dark red 2.5YR 3/6 7.46 present silt clay gravel Ironstone lithic fragments present. S8/2.9 2.9 8.7 sandy clay brown 10YR 5/3 7.68 present clay sand With white clay lenses (kaolinite), angular shale fragments. S8/3.2 3.2 8.6 sandy clay dark brown 7.5YR 4/4 7.36 minor clay sand Shale fragments throughout. light yellowish S8/3.4 3.4 6.9 sandy clay brown 10YR 6/4 7.25 present sand clay Angular shale fragments. S8/3.6 3.6 5.7 sandy clay pale brown 10YR 6/3 7.1 present silt clay sand Weathered sandstone. S8/4 4 7 sandy clay pale brown 10YR 6/3 7.3 absent weathered shale As above. S8/4.4 4.4 6.8 sandy clay light brown 7.5YR 6/4 7.29 minor shale Bedrock contact. dark reddish S12/0 0-0.6 26.4 loamy clay brown 5YR 3/4 7.85 absent topsoil plant roots & organic matter abundant S12/0.6 0.6-0.8 21.4 heavy clay red 2.5YR 4/6 7.53 absent clay contains moisture, uniform grain size S12/0.8 0.8-1.2 21.8 very heavy clay red 2.5YR 4/6 7.38 present clay contains lithic fragments

S12/1.2 1.2-2 25.5 med clay red 2.5YR 4/6 7.54 abundant clay Fe/Mn nodules, rock fragments of limestone, abundant CO3 large angular pebbles of assorted rock types, clay rich, water table, abundant S12/2 2-2.5 24.1 clay/gravel strong brown 7.5YR 5/6 7.68 abundant clay/gravel CO3

heavy increase in moisture, angular limestone rock fragments & Fe/Mn nodules, CO3 S12/2.5 2.5-3 33.7 clay/gravel dark brown 7.5YR 4/4 7.46 present clay/gravel present S12/3 3-3.5 44.3 clay/gravel strong brown 7.5YR 5/6 7.41 minor clay/gravel saturated, large angular rock fragments, colluvium, quartz grains S12/4.7 4.7-5.5 30.7 clay/gravel brown 7.5YR 5/4 7.51 absent clay/gravel same material as above weathered S12/8.7 7.9-8.7 NA volcanic greenish grey 5GY 5/1 8.07 absent gravel/clay decrease in moisture, Palaeozoic basement, weathered powdery weathered weathered firm weathered volcanic Palaeozoic basement rock, green matrix with black S12/8.8 8.7-9.1 NA volcanic greenish grey 5GY 5/1 7.95 absent volcanic rock fragments, inc in moisture weathered S12/9.1 9.1-9.2 NA volcanic greenish grey 5G 6/1 8.02 absent volcanic green clayey flowing water from the basement rock, 4.8 µS/cm. Mafic rock S16/0.4 0.4 11.7 loamy sand Dark red 2.5YR 3/6 5.87 absent loam Organic matter present. S16/0.8 0.8 13.8 light clay strong brown 7.5YR 5/6 6.42 absent clay Contains lithic fragments. S16/1 1 13.5 light clay strong brown 7.5YR 5/6 6.2 absent clay Lithic fragments present, dry. S16/1.3 1.3 10.9 light clay Reddish brown 2.5YR 5/4 6.38 absent clay Large pebble sized lithic fragments. S16/1.8 1.8 10.4 light clay Pale red 2.5YR 6/2 6.77 present clay Large angular lithic fragment.

11 Appendix B: Soil and groundwater data

Sample Depth Moisture Munsel Field Generalised ID (m) % Texture class Colour colour pH Carbonate lithology Field description S16/2.4 2.4 11.5 sandy clay Pale red 2.5YR 6/2 7.57 present sand clay White shale and sandstone fragments. S16/2.6 2.6 9.1 sandy clay Pinkish grey 5YR 6/2 7.22 present sand clay Increase in sand content with sandstone fragments present. S16/3 3 9.6 clayey sand Pinkish grey 5YR 7/2 6.12 present sand With white sandstone fragments. S16/3.2 3.2 10.5 sandy clay pink 7.5YR 7/4 6.58 absent sand clay Contains red angular shale fragments. S16/3.8 3.8 9.5 sandy clay Reddish yellow 7.5YR 6/4 6.11 absent clay sand Contains shale fragments, dry. S16/4 4 8.8 light clay Reddish brown 5YR 5/4 NA absent weathered shale Pebble sized angular shale fragments, weathered bedrock. dark reddish S17/0 0 12.5 clay loam brown 5YR 3/3 NA absent loam Moist with plant roots. S17/0.5 0.5 11.8 clay loam Dark red 2.5YR 3/6 NA absent clay loam Fe/Mn nodules present, with white rock fragments. S17/0.8 0.8 14 light clay red 2.5YR 4/6 NA absent clay moist, with Fe/Mn nodules. S17/1.4 1.4 20 medium clay yellowish red 5YR 4/6 NA absent clay White lithic fragments present. White lithic fragments and Fe/Mn nodules, fine colluvium, lenses of white clay S17/2.6 2.6 15.9 medium clay red 2.5YR 4/6 NA absent clay present. S17/3 3 16.2 medium clay yellowish red 5YR 4/6 NA absent clay Very soft, red clay with nodules. S17/4.2 4.2 17.6 medium clay red 2.5YR 4/6 NA absent clay Oxidised S17/5 5 16.8 medium clay strong brown 7.5YR 4/6 NA absent clay gravel Large ironstone pebbles present. S17/5.4 5.4 15.3 medium clay dark brown 7.5YR 4/4 NA absent gravel clay Large angular pebbles, narrow band of gravel. light medium S17/5.5 5.5 15.6 clay dark brown 7.5YR 4/4 NA absent clay gravel Increase in gravel content, with nodules. light medium S17/6.5 6.5 15.6 clay dark brown 7.5YR 4/4 NA absent clay Increase in clay content. S17/6.8 6.8 18.4 medium clay brown 7.5YR 5/4 NA absent clay Unconsolidated. S17/7.2 7.2 17.2 medium clay strong brown 7.5YR 4/6 NA absent clay Fe/Mn nodules present. dark yellowish S17/7.7 7.7 17.1 light clay brown 10YR 4/6 NA absent clay Very soft, light coloured yellow clay. S17/8.5 8.5 13.6 sandy clay yellowish brown 10YR 5/4 NA present sand clay Unconsolidated with clay lenses and sulphide odour apparent.

S17/9 9 12.8 sandy clay yellowish brown 10YR 5/6 NA abundant sand clay With white nodules throughout. medium heavy dark reddish S17/10.4 10.4 15.1 clay brown 5YR ¾ NA present clay Ironstone fragments with angular pebbles present throughout. NA = Not analysed

12 Appendix B: Soil and groundwater data

B.3 BORE CONSTRUCTION DETAILS AND WATER LEVEL DATA (m) Slotted Casing Easting Northing Apr 2002 Jun 2001 Jun 2002 Feb 2003 Nov 2001 Aug 2002 Sep 2002 height (m) Sample ID interval (m) Total depth Aquifer unit Elevation (m) 96121/3 Oakdale 688134 6428636370 103-108 110 1.04 5.94 5.25 NR 3.24 NR 3.39 3.4 96127/2 Oakdale 692277 6429326370 43-49 51 0.94 NR 24.75 NR 9.91 NR 9.65 10.44 96133/2 Oakdale 691000 6433700345 30-34 36 1.16 NR 4.72 5.05 5.6 5.88 5.9 6.75 96122/3 Gleneski 694561 6434680 390 41-47 49 0.72 1.53 1.04 1.33 1.37 1.24 1.23 1.98 96122/4 Gleneski 694561 6434680390 94-98 100 0.78 23.25 2.86 4.04 30.19 11.8 9.26 6.53 96128/3 Gleneski 696661 6432806420 27-29 31 1.4 NR NR NR 3.27 NR 3.47 3.99 BH1 Gleneski 697488 6432320440 25-35 38 NR NR NR NR NR NR 5.5 UR3 Gleneski 695800 6436300375 - 117 0.7 18.68 NR NR NR NR 20.62 NR UR14 Gleneski 694400 6431600410 - 15 0 1.25 NR NR NR NR NR NR 96129/3 Cunningham 694304 6425819 375 23-29 31 0 NR -0.6 NR -0.4 NR NR 0.68 238 Intermediate 684855 6427420378 - 20 0.47 2.75 NR NR NR NR NR NR 268 Intermediate 690232 6426877396 - 34.7 0.48 6.82 NR NR NR NR 13.11 NR 287 Intermediate 684616 6437923327 128.4-146.3 147 0 NR NR NR NR NR Flowing NR 1173 Intermediate 696044 6428513440 - 20.4 0.5 6.18 NR NR NR NR NR NR 24363 Intermediate 684551 6428904415 - 44.2 0 1.39 NR NR NR NR NR NR 33343 Intermediate 692396 6432951380 - 41.8 0.44 2.71 NR NR NR NR NR NR 44700 Intermediate 691067 6434092381 15.2-30.4 30.5 0.22 2.63 NR NR NR NR NR NR 44924 Intermediate 690669 6435774347 36.6-44.2 44.2 0.17 0.7 NR NR NR NR 19.6 NR 96121/2 Intermediate 688134 6428636 370 44-49 51 1.12 11.39 1.85 NR 9.23 NR 9.2 8.62 96130/2 Intermediate688879 6433108355 34.5-40.5 40.5 0.96 NR 33.32 NR 6.57 NR 6.06 6.24 96131/2 Intermediate 685726 6439054 310 32-35 37 1.03 NR NR NR 8.79 NR 8.76 9.17 96132/1 Intermediate 686851 6425936 390 49-55 61 0.9 NR 40.03 NR 8.11 NR 8.3 8.59 Soda Intermediate 678574 6436705310 - - 0 NR NR NR NR NR NR Flowing UR1 Intermediate 687800 6424200390 - 30 0.7 2.89 NR NR NR NR 11.52 NR UR2 Intermediate 687700 6430200350 - - 0.36 3.62 NR NR NR NR 3.02 NR UR4 Intermediate 687800 6423800390 - 26 0.94 23.7 NR NR NR NR NR NR UR5 Intermediate 686100 6430500380 - - 0.44 1.42 NR NR NR NR NR NR UR6 Intermediate 687400 6429600365 - 30 0.44 7.59 NR NR NR NR NR NR UR7 Intermediate 690400 6426400410 - 24.3 0.36 9.02 NR NR NR NR NR NR UR8 Intermediate 697700 6438600390 - 18 0.21 2.74 NR NR NR NR NR NR UR9 Intermediate 696300 6432900420 - - 0.49 1.54 NR NR NR NR NR NR UR10 Intermediate 690500 6427600400 - - 0 9.21 NR NR NR NR NR NR UR11 Intermediate 695900 6431700420 - - 0.33 6.03 NR NR NR NR NR NR UR12 Intermediate 693600 6431900395 - 6 0.55 1.54 NR NR NR NR NR NR UR13 Intermediate 693300 6431900395 - 20 0 5.08 NR NR NR NR NR NR UR15 Intermediate 686085 6429550368 - 100 0.22 2.43 NR NR NR NR NR NR UR16 Intermediate 683400 6428200415 - - 0 Flowing NR NR NR NR NR NR 96035/1 Shallow 697107 6432803440 4.4-5.4 5.4 0.9 NR NR NR 0.83 NR NR 1.72 96035/2 Shallow 697107 6432803440 7.6-8.6 8.6 0.87 NR NR NR 3.48 NR NR 1.7 96034 Shallow 697120 6432664440 2.7-3.7 3.79 1 NR NR NR 2.03 NR NR 3.43 96121/1 Shallow 688134 6428636370 8-13 20 1.08 1.37 1.51 NR 1.85 NR 2.1 2.47 96122/1 Shallow 694561 6434680 390 2-3 4 1.03 1.19 1.63 1.58 1.33 1.33 1.38 2.37 96122/2 Shallow 694561 6434680390 6-8 11 1.2 1.19 1.6 1.53 1.34 1.33 1.38 2.38 96127/1 Shallow 692277 6429326370 10-12 14 0.95 NR 9.74 NR 9.1 NR 9.09 9.42

Appendix B: Soil and groundwater data (m) Slotted Casing Easting Northing Apr 2002 Jun 2001 Jun 2002 Feb 2003 Nov 2001 Aug 2002 Sep 2002 height (m) Sample ID interval (m) Total depth Aquifer unit Elevation (m) 96128/1 Shallow 696661 6432806420 1.5-3 3 0.99 NR NR NR 2.94 NR 2.99 3.47 96128/2 Shallow 696661 6432806420 10.8-12.8 15 0.98 NR NR NR 2.65 NR 2.83 3.3 96129/1 Shallow 694304 6425819375 3-4 5 0.97 NR 2.44 NR 2.98 NR NR 3.21 96129/2 Shallow 694304 6425819375 9.5-11 12 0.97 NR 2.5 NR 2.94 NR NR 3.23 96130/1 Shallow 688879 6433108355 10.5-12.5 14.50.96 NR 3.23 NR 2.58 NR 3.32 3.6 96131/1 Shallow 685726 6439054310 8.1-10.1 10.3 0.97 NR NR NR 8.52 NR 9.51 9.5 96132/2 Shallow 686851 6425936390 3-5 11 0.96 NR 4.47 NR 4.84 NR 5.22 5.48 96133/1 Shallow 691000 6433700 345 4-6 8 1.27 NR 4.22 5.36 5.72 5.94 5.99 6.76 98037 Shallow 690934 6433793 345 5.7-6.7 6.7 0.84 NR NR NR 3.21 3.38 NR 4.2 98038 Shallow 696587 6432905420 3.3-4.3 4.3 1 NR NR NR NR NR NR 3.22 98036 Shallow 697120 6432867440 3-4 4 0.95 NR NR NR 1.22 NR NR 2.28 p9 Shallow 688700 6429100370 8.6-9.6 9.64 0.97 1.1 NR NR NR NR NR NR p9a Shallow 688600 6429200370 3-4 4.03 0.95 2.76 NR NR NR NR NR NR p10 Shallow 688900 6428800370 3-4 4 1 1.62 NR NR NR NR NR NR p10a Shallow 689100 6428800370 3.4-4.4 4.4 1 2.39 NR NR NR NR NR NR p11 Shallow 688900 6428600370 6.3-7.3 7.32 0.97 4.15 NR NR NR NR NR NR p56 Shallow 689716 6435740330 4.3-5.3 5.3 0.92 1.46 NR NR NR NR NR 3.19 p57 Shallow 694730 6434834390 5.8-4.8 5.8 0.99 1.66 1.17 NR 2.05 NR NR 2.88 p58 Shallow 697326 6432943450 7-6 7 1.05 NR 2.02 NR 1.17 NR NR 3.02 p59 Shallow 697244 6432663430 11.2-10.2 11.20.99 3.05 4.32 NR 4.29 NR NR 4.39 p60 Shallow 697107 6432421430 6.8-5.8 6.8 0.93 1.58 1.98 NR 2.01 NR NR 2.89 p61 Shallow 696731 6432931430 5.7-4.7 5.7 1 2.91 3.13 NR 2.92 NR NR 3.26 p62 Shallow 694748 6433220 390 7.2-8.2 8.2 0.91 1.49 NR 1.69 1.55 1.52 1.49 2.58 p63 Shallow 694851 6433061 390 3.4-4.4 4.4 0.96 1.44 NR 1.88 1.76 1.73 1.59 2.85 p64 Shallow 694550 6432847390 2.7-3.7 3.7 0.87 3.06 NR NR 3.48 NR NR NR p65 Shallow 693741 6434167370 3.7-4.7 4.65 0.94 1.92 NR NR 2.21 NR NR 3.34 p66 Shallow 695777 6433541410 4.9-5.9 5.9 0.87 2.33 NR NR 2.73 NR NR NR S1a Shallow 691401 6433573 348 6.7-5.7 6.7 1.02 NR 2.26 1.75 1.56 1.69 2.75 1.95 S1b Shallow 691401 6433573348 7-8 8 1.03NR 1.8 1.37 1.52 1.56 1.62 1.92 S1c Shallow 691401 6433573 348 10.4-9.4 10.4 0.97 NR 1.74 1.52 1.55 1.5 1.58 1.93 S2a Shallow 691533 6433517 354 3.7-4.7 4.7 0.97 NR 2.39 1.92 1.98 2.05 2.1 2.4 S2b Shallow 691533 6433517354 7.1-8.1 8.1 0.98NR 1.96 1.62 1.7 1.81 1.86 2.18 S2c Shallow 691533 6433517354 11-12 12 1 NR 1.54 1.53 1.48 1.55 1.55 1.85 S3a Shallow 691786 6433328 362 10.2-9.2 10.2 0.97 NR 5.69 6.09 6.17 6.32 6.34 6.92 S3b Shallow 691786 6433328 362 12.4-11.4 12.4 1.01 NR 6.62 6.11 6.27 6.38 6.41 7.02 S4 Shallow 691705 6433248372 5.1-6.1 6.1 0.9 NR 4.19 4.13 4.3 4.37 4.38 4.9 S5 Shallow 690300 6435449 360 5.4-4.4 5.4 0.93 NR 1.52 0.21 1.35 1.39 1.38 2.06 S6a Shallow 690624 6435304 363 1.45-1.6 1.6 0.54 NR NR NR 0.62 0.65 0.7 1.62 S6b Shallow 690624 6435304 363 4.1-5.1 5.1 0.97 NR 1.35 1.38 1.15 1.2 1.16 2.3 S7a Shallow 690666 6435113370 0.8-0.95 0.950.63 NR NR NR 0.86 0.91 1.13 dry S7b Shallow 690666 6435113 370 10.7-9.7 10.7 1 NR 1.01 -0.82 0.24 0.69 0.71 0.92 S8 Shallow 690913 6434936 378 4.1-5.1 5.1 0.98 NR 3.68 2.05 2.52 3.12 3.26 4.19 S10 Shallow 691488 6433643348 1.35-1.5 1.5 0.9 NR NR NR 1.93 1.35 1.44 1.8 S11 Shallow 691453 6433538 352 1.35-1.5 1.5 0.51 NR NR NR 1.08 1.03 1.03 1.21 S12 Shallow 695044 6433574400 5-6 6 0.95NR NR 2.72 2.86 2.9 2.95 3.7 S13a Shallow 694778 6433451395 4.3-5.3 5.250.75 NR NR 2.3 2.22 2.22 2.23 2.88 S13d Shallow 694778 6433451395 9.5-10.5 10.50.95 NR NR 1.9 1.9 1.89 1.87 2.58

Appendix B: Soil and groundwater data (m) Slotted Casing Easting Northing Apr 2002 Jun 2001 Jun 2002 Feb 2003 Nov 2001 Aug 2002 Sep 2002 height (m) Sample ID interval (m) Total depth Aquifer unit Elevation (m) S13c Shallow 694866 6433363395 8-9 9 0.95NR NR 1.9 1.92 1.92 1.92 2.62 S13b Shallow 694866 6433363395 6.1-7.1 7.1 1 NR NR 1.97 1.96 1.97 1.97 2.68 S14a Shallow 694901 6433136393 0.8-1.8 1.8 1 NR NR 1.43 1.43 1.51 1.37 dry S14b Shallow 694901 6433136393 3-4 4 0.98NR NR 1.46 1.45 1.52 1.39 2.26 S14c Shallow 694901 6433136393 9-10 10 0.99NR NR 1.43 1.54 1.52 1.51 2.25 S15a shallow 694656 6433136392 5-6 6.05 0.95 NR NR 6.05 1.72 1.74 1.72 2.59 S15b shallow 694726 6433101 392 7.4-8.4 8.4 0.97 NR NR 1.28 1.17 1.21 1.08 2.21 U1 shallow 694561 6434680390 0.82-0.32 0.820.15 NR -0.02NR -0.05 NR NR NR NR= not recorded Water level measurements = m below ground surface (bgs)

Appendix B: Soil and groundwater data

B.4 ISOTOPES

18 δO 2 δH ‰ ‰ 87 86 13 1 1 SampleID date Sr/ Sr δC ‰ DIC mmol/L PCO2 deep 19822 -4.88 -32.6NA -13.34 - -1.85 44700 -5.14 -32.8NA -16.52 3.84 -1.67 51655 -4.32 -27.5NA -12.40 - -1.2 9121 -5.21 -34.7NA -13.00 - -1 96121/3 4-Sep-02 -4.45 -32.50.705407 -14.85 16.18 -1.39 96127/2 4-Sep-02 -5.43 -38.90.706555 -15.44 18.71 -1.22 96133/2 3-Sep-02 -5.34 -38.10.706375 -13.668 11.93 -1.3 1626 -5.08 -33.6NA -14.59 - -1.34 1636 -5.16 -33.9NA -13.00 - -1.2 96122/4 6-Sep-02 -5.75 -37.60.707081 -14.158 17.07 -1.32 96122/3 6-Sep-02 -5.49 -35.30.706546 -12.31 23.77 -0.9 96128/3 6-Sep-02 -4.84 -34.80.708938 -14.752 19.04 -1.11 BH1 5-Feb-03 -5.15 -31.6 NA -13.4 10.13 -1.63 UR3 8-Sep-02 -5.31 -30.80.707292 -12.436 4.97 -2.83 96129/3 6-Feb-03 -5.13 -32.4 NA -13.9 11.25 -1.56 intermediate 287 8-Sep-02 -7.47 -47.10.706564 -5.047 74.58 -0.27 7711 -7.49 -44.7NA -3.51 115.74 0.19 23737 -7.55 -47.3NA 2.30 106.49 0.12 50926 -7.39 -47.5NA -3.11 109.75 0.15 65909 -7.59 -47.3NA -1.28 126.99 0.23 268 7-Sep-02 -4.62 -32.80.706998 -12.494 18.7 -0.95 23336 -7.51 -47.1NA -2.37 - -0.09 24363 -4.23 -32.7NA -19.50 13.45 -0.51 26988 -5.08 -32.5NA -13.04 13.66 -1.44 44924 8-Sep-02 -4.92 -34.70.708060 -12.195 15.84 -0.99 52522 -7.49 -46.9NA -3.05 - 0.28 9119 -5.98 -39.6NA -9.35 26.5 -0.56 96121/2 4-Sep-02 -5.28 -32.90.705530 -14.219 22.14 -0.98 96130/2 4-Sep-02 -5.98 -41.30.706629 -12.552 24.87 -1 96131/2 7-Sep-02 -5.4 -37.2 0.709346 -14.041 20.68 -0.83 96132/1 4-Sep-02 -4.74 -36.20.706003 -14.949 28.57 -1.04 UR1 7-Sep-02 -4.67 -27.20.705692 -12.285 20.72 -1 UR2 7-Sep-02 -4.87 -30.70.706739 -12.76 7.99 -2.92 shallow 96121/1 3-Feb-03 -4.75 -29.2 NA -12.7 23.25 -1.08 96122/1 4-Feb-03 -5.04 -32.3 NA -14.4 17.31 -1.61 96122/2 4-Feb-03 -4.81 -31.8 NA -14.3 26.53 -1.65 96127/1 6-Feb-03 -5.59 -34.7 NA -12.5 15.79 -1.82 96128/1 5-Feb-03 -5.34 -32.9 NA -12.4 17.32 -1.65 96128/2 5-Feb-03 -4.96 -32 NA -13.3 15.6 -1.44 96129/1 6-Feb-03 -4.93 -30.8 NA -13.6 9.23 -2.04 96129/2 6-Feb-03 -5.2 -32.2 NA -12.4 12.74 -1.8 96130/1 3-Feb-03 -4.67 -29.9 NA -12.7 22.17 -1.13 96132/2 6-Feb-03 -4.69 -31.1 NA -12.8 16.99 -1.62 96133/1 2-Feb-03 -6.21 -39.2 NA -14.7 8.8 -1.66

Appendix B: Soil and groundwater data

18 δO 2 δH ‰ ‰ 87 86 13 1 1 SampleID date Sr/ Sr δC ‰ DIC mmol/L PCO2 98037 2-Feb-03 -5.08 -31.7 NA -15.5 14.12 -1.69 p56 3-Feb-03 -4.59 -28.3 NA -13.2 21.2 -1.34 p58 5-Feb-03 -4.99 -31.8 NA -12.5 16.2 -1.36 p60 5-Feb-03 -4.84 -32.4 NA -14.5 29.11 -1.62 p61 5-Feb-03 -5.2 -28.9 NA NA 14.95 -1.56 S1a 2-Feb-03 -4.57 -31.2 NA -13.8 11.94 -1.76 S1b 2-Feb-03 -4.46 -28.8 NA -12.5 27.74 -2.55 S1c 2-Feb-03 -4.49 -27.3 NA -13.3 19.05 -1.78 S2a 2-Feb-03 -4.46 -29 NA -12.8 11.96 -1.66 S2b 2-Feb-03 -4.77 -30.6 NA -14.1 11.27 -1.99 S2c 2-Feb-03 -4.51 -28 NA -9.4 12.07 -1.88 S3a 2-Feb-03 -5.44 -32.2 NA -11.9 7.18 -2.1 S3b 2-Feb-03 -5.43 -29.6 NA -13.2 9 -2.16 S4 2-Feb-03 -4.91 -28.2 NA -12 8.08 -1.7 S5 3-Feb-03 -4.49 -26.2 NA -13.9 14.93 -1.79 S6b 3-Feb-03 -4.47 -28 NA NA 12.67 -1.62 S7b 3-Feb-03 -4.42 -26.5 NA -14.8 8.92 -2.64 S8 3-Feb-03 -4.68 -29.1 NA -14.1 20.23 -1.66 S11 2-Feb-03 -4.44 -27.1 NA -11.6 11.07 -1.93 S12 4-Feb-03 -5.28 -30 NA -13.3 10.04 -2.24 S13a 4-Feb-03 -4.98 -31.4 NA -11.9 14.32 -1.57 S13b 4-Feb-03 NA NA NA -12.2 17.4 -1.55 S13c 4-Feb-03 -4.81 -31.7 NA NA 13.69 -1.63 S13d 4-Feb-03 -5.09 -31.1 NA -16.5 12.73 -1.76 S14b 4-Feb-03 -4.81 -30.5 NA -12.7 11.68 -1.7 S14c 4-Feb-03 -4.98 -30.9 NA -14.3 13.16 -1.92 S15a 4-Feb-03 -4.86 -31.9 NA -12.6 13.17 -1.62 S15b 4-Feb-03 -4.86 -30.3 NA -12.3 11.3 -1.68 Rain 1 -1.3 5.9 NA NA - - Rain 2 -1.645 0.8 NA NA - - 1calculated in PHREEQC

Appendix B: Soil and groundwater data

B.5 HYDROCHEMICAL DATA I Geology/ EC µS TDS -1 2+ 3+ SampleID Date Site pH Eh (mV) T ºC cm O2 Na K Mg Ca Fe Fe Cl SO4 HCO3 F Br CO2 CO3 H2S SIO2 Sr Li B Mn NH4 NO3 PO4 pe CBE (mg/l) SAR MH Wtype Deep (n=14)

19822 1/01/1998 OF 7.55 -300 21.2 6815 0 1061.9 1.5 236.6 76.9 3.74 0 1964.29 28.4 671.2 0.96 NA 16 NA 0.78 16.8 3.89 0.01 0.08 0.18 NA NA NA -5.14 1.99 4083.64 13.53 83.53 Na-Mg-Cl

51655 1/01/1998 OF 6.97 -188.8 20.2 6025 0.7 843.2 4.3 168.8 99.3 1.18 NA 1549.99 153.3 753 1.83 NA 126.5 NA 0.2 25.3 3.48 0.089 0.26 0.09 NA NA NA -3.24 -3.04 3731.87 11.95 73.70 Na-Mg-Cl-HCO3

9121 1/01/1998 OF 6.9 -252.3 18.7 5065 0 682.5 8.1 181 77.5 0.07 NA 1171.43 78.6 1034.9 1.17 NA 146.3 NA 0.09 34.4 1.86 0.01 0.1 0.01 NA NA NA -4.36 -2.98 3418.29 9.69 79.38 Na-Mg-Cl-HCO3

96121/2 4/09/2002 OF 6.876 -150.7 20.75 14025 0.7 2730 32.3 303 252 0.83 0.15 4698.54 392.48 1110.42 NA NA 96.82 NA 0.62 5.8 14.2 0.09 0.375 0.66 2.93 14.52 0.73 -2.58 -0.45 9657.52 27.42 66.47 Na-Cl

96121/3 4/09/2002 OF 7.193 -278.3 23 14510 0.3 2650 42.7 329 308 0.02 0.05 4718.54 1243.34 898.1 NA NA 66.89 NA 2.61 4.9 20.1 0.05 0.26 0.4 6.71 16.28 1.55 -4.74 -4.29 10310.01 25.02 63.78 Na-Cl

96127/2 4/09/2002 OF 7.129 -158.4 22.3 4460 2.6 618 12.8 206 109 0.2 NA 1059.67 242.08 1009.75 NA NA 79.22 NA 0.132 10.8 3.22 0.04 0.291 0.24 1.29 2.464 5.55 -2.7 -1.87 3363.44 8.03 75.70 Na-Mg-Cl-HCO3

96133/2 3/09/2002 OF 6.932 -22.3 19 6320 4.6 537 14.2 364 260 0.05 0.05 2099.35 68.01 605.24 NA NA 73.94 NA 0.006 3.5 7.7 0.02 0.229 1.05 0.4 NA 0.58 -0.38 -2.66 4040.54 5.04 69.77 Mg-Na-Cl

1626 1/01/1998 GF 7.14 -81.5 19.5 2070 0 191 2.7 102 95.7 0 0 282.07 18.3 773.7 0.5 NA 118.8 NA 0.13 31.2 0.8 0.01 0 0 NA NA NA -1.4 1.25 1617.16 3.24 63.73 Mg-Na-Ca-HCO3-Cl

1636 1/01/1998 GF 6.96 -143.2 19.3 4145 0 151.3 3.7 290 188.5 0 0.01 1042.86 20.9 762.7 0 NA 154 NA 0.12 38.2 2.38 0.01 0.02 0 NA NA NA -2.47 -2.83 2655.36 1.61 71.72 Mg-Ca-Cl-HCO3

96122/3 6/09/2002 GF 6.844 -67.2 20.5 5085 0.6 520 21.1 341 65.1 0.3 NA 1319.59 97.37 1156.18 NA NA 151.39 NA 0.001 4.5 2.38 0.06 0.216 0.35 0.26 9.68 0.56 -1.15 -3.32 3690.78 5.72 89.62 Mg-Na-Cl-HCO3

96122/4 6/09/2002 GF 7.201 -175 22 3715 2.4 419 15.3 204 77.7 0.09 NA 819.75 178.56 936.53 NA NA 63.37 NA 1.245 7 2.13 0.02 0.271 0.82 0.75 12.32 0.57 -2.99 -3.64 2742.08 5.67 81.23 Na-Mg-Cl-HCO3

96128/3 6/09/2002 GF 6.963 -127.6 20.45 6645 0.6 741 3.01 404 116 0.34 NA 1979.39 93.77 979.24 NA NA 77.46 NA 0 15.1 3.25 0.01 0.24 0.05 0.03 28.16 0.45 -2.19 -1.96 4442.48 7.30 85.17 Mg-Na-Cl-HCO3

BH1 5/02/2003 GF 7.28 -186 20.6 2850 3.5 92.32 2.59 225.43 169.61 0 0 839.74 8.97 566.19 NA 2.591 221.81 NA NA NA 1.43 0 0.062 0.01 NA NA NA -3.19 -3.18 2135.02 1.09 68.66 Mg-Ca-Cl-HCO3

UR3 8/09/2002 GF 8.261 -262.6 21.85 954.5 0.1 167 20.8 16.7 11.9 0.11 0.66 159.95 45.24 289.81 NA NA 28.8 14.4 0.106 3 0.34 0.01 0.118 0.12 1.11 7.04 0.67 -4.49 -4.46 495.47 7.32 69.82 Na-HCO3-Cl

96129/3+ 6/02/2003 CF 7.248 -1.6 19.7 2920 1.93 164.57 1.95 222 124.61 0.01 NA 759.76 46.34 622.32 NA 2.643 193.64 NA NA 23.3 1.67 0.01 0.104 0 NA NA NA -0.03 -1.38 2141.73 2.05 74.60 Mg-Na-Cl-HCO3 Int (n=19)

23737* 1/01/1998 Int 6.33 -312 21.5 4650 0 1059.4 91 64 133.4 1.36 0 58.4 60 3498 NA NA 1041 NA 0.3 7.9 0.24 0.25 0.69 <0.002 NA NA NA -5.34 0.35 2840.34 18.87 44.16 Na-HCO3 Int 287* 8/09/2002 6.714 -59.7 22.3 4790 42.1 1220 93.1 38.9 61.9 0.71 0.05 479.85 0 3355.66 NA NA 616.13 NA 0.001 5.6 1.8 0.34 0.495 0 4.52 11 0.01 -1.02 -4.80 2767.30 29.93 50.89 Na-HCO3-Cl Int 50926* 1/01/1998 6.31 -149 21.3 4670 0.1 1071.5 85 52.5 106.2 1.08 NA 53.1 0.7 3509.6 NA NA 1118 NA 0.31 7.2 0.21 0.255 0.64 <0.002 NA NA NA -2.55 -0.28 2786.58 21.25 44.90 Na-HCO3 Int 65909* 1/01/1998 6.27 -224 21 4990 0 1132.5 104.8 61.7 116.2 3.08 NA 53.1 3.7 3889 NA NA 1178 NA 1.02 7.3 0.5 0.189 0.38 <0.002 NA NA NA -3.84 -1.70 2987.94 21.13 46.68 Na-HCO3 Int 7711* 1/01/1998 6.31 -265 24 4860 0 1156 98.9 32.6 61.5 0.78 NA 49.2 1.1 3755.1 NA NA 935 NA 0.22 8.7 1.23 0.239 0.6 <0.002 NA NA NA -4.49 -3.36 2519.01 29.65 46.64 Na-HCO3 Int Soda1* 6/02/2003 6.655 32.2 22.1 3600 0.21 819.73 77.89 34.66 69.38 0.87 NA 119.56 0.5 2757.74 NA 0.427 2253.26 NA NA NA 0.6 0.37 0.621 0.01 NA NA NA 0.55 -4.51 3568.83 20.07 45.16 Na-HCO3 Int 23336 1/01/1998 6.42 -233.1 21.1 9255 0 2027 47.8 54.7 91.5 5.3 0.01 1859.98 4.2 2745.8 1.82 NA 692.2 NA 0.77 13.9 4 0.149 0.39 0.02 NA NA NA -3.99 0.63 5073.39 41.41 49.64 Na-Cl-HCO3 Int 24363 1/01/1998 5.28 -115 19.3 13800 0.7 2224.3 1.5 350.1 68.6 5.11 NA 4343.9 391.6 85.7 NA NA 230 NA 0.83 61.9 3.25 0.088 <0.008 0.97 NA NA NA -1.98 -1.02 7770.80 24.10 89.38 Na-Mg-Cl Int 268 7/09/2002 6.775 55.1 19.4 4070 12.5 376 2.38 195 192 0.03 0 1019.68 36.25 869.42 NA NA 105.62 NA 0.001 5.5 3.52 0.02 0.274 0 0.04 14.08 0.35 0.95 -2.10 2834.21 4.57 62.61 Na-Mg-Ca-Cl-HCO3 Int 26988 1/01/1998 7.34 -77.8 21.2 13215 0 2009.8 8.1 370.3 142.6 1.08 0 3443.96 530 1104.4 0 NA 72.6 NA 0.41 15.1 4.5 0.128 0.11 0.15 NA NA NA -1.33 -0.31 7703.81 20.17 81.07 Na-Mg-Cl Int 44700 1/01/1998 6.76 -126 19.9 10210 0.4 674.9 37.6 655.2 264.1 11.66 16.08 3229.2 6.3 219 NA NA 77 NA 7.27 5.8 8.78 <0.004 0.32 1.92 NA NA NA -2.17 2.16 5218.65 5.07 80.35 Mg-Na-Cl Int 44924 8/09/2002 6.781 -83.25 22 3415 25.6 491 12.1 91.1 128 5.45 4.54 799.75 144.11 738.25 NA NA 144.35 NA 0 5 1.88 0.05 0.245 0.14 0.9 8.36 0.08 -1.42 -2.24 2189.28 8.11 53.99 Na-Mg-Cl-HCO3 Int 52522 1/01/1998 6.22 -273 20.5 6630 0 1604.8 60.5 84 90.5 0.85 NA 518 4040.3 NA NA 1283 NA 0.35 3.6 2.27 0.091 0.43 <0.002 NA NA NA -4.68 1.30 3992.99 29.20 60.48 Na-HCO3 Int 61078 1/01/1998 6.44 47 20.1 6390 3.7 846 1.4 221 138 0.15 0.01 1710 173 846 NA NA 97 NA 0.02 NA 0 <0.004 <0.008 <0.002 NA NA NA 0.81 -2.97 4036.17 10.39 72.53 Na-Mg-Cl-HCO3 Int 9119 1/01/1998 6.44 -174 19.3 5350 0.1 952.3 14.8 95.2 71.1 12.39 NA 1205.1 142.3 965.6 NA NA 189 NA 3.17 10.3 2.61 0.04 0.19 <0.002 NA NA NA -3 0.90 2952.46 17.37 68.82 Na-Cl-HCO3 Int 96130/2 4/09/2002 7.022 -175.8 21.85 4800 1.5 897 8.85 120 89.1 1.02 NA 1139.65 23.4 1293.45 NA NA 153.15 NA 0.173 15.9 2.81 0.02 0.387 1.59 1.21 7.92 5.7 -3 -0.31 2884.52 14.58 68.95 Na-Cl-HCO3 Int 96131/2 7/09/2002 6.665 -120.9 21.2 8275 0.4 1200 28.7 279 246 1.68 NA 2499.23 259.75 924.33 NA NA 151.39 NA 0.027 9.3 4.22 0.05 0.293 0.76 0.63 6.6 NA -2.07 -1.52 5612.74 12.44 65.16 Na-Mg-Cl Int 96132/1 4/09/2002 7.046 -59.2 20.3 21250 8.9 4530 65.8 255 488 1.8 NA 6977.84 898.8 1525.3 NA NA 88.02 NA 0.001 5.8 11.5 0.06 0.172 2.07 3.87 9.24 0.76 -1.02 0.83 14873.21 41.39 46.28 Na-Cl Int UR1 7/09/2002 6.863 3.05 19.75 7280 17.5 804 14.1 430 183 0.69 NA 2399.26 166.58 1025 NA NA 109.14 NA 0.001 7.4 5.15 0.11 0.248 0.06 0.28 6.16 0.7 0.05 -4.73 5169.45 7.41 79.48 Mg-Na-Cl Int UR2 7/09/2002 8.5 -363.5 19.9 3065 0.3 475 7.46 105 29.9 0.08 1.25 859.73 17.95 485.05 NA NA 43.2 21.3 0.002 2.7 1.3 0.01 0.161 0.04 0.77 4.84 0.14 -6.25 -3.45 2056.32 9.18 85.27 Na-Mg-Cl-HCO3 Shallow (n=138)

96034 10-Jun-02 Top SG 7.163 -16 17.75 6520 1.14 839 2.89 375 62.6 0.01 0 2099.35 52.43 1067.8 NA NA 281.66 NA 0 7.5 4.12 <0.004 0.55 0.127 0.14 4.84 0.3 -0.28 -4.88 4799.32 8.85 90.8 Na-Mg-Cl-HCO3

96034 5-May-02 Top SG 7.36 288 20.4 6660 833 3.6 359.9 68.3 NA 1821 57.1 1031 NA NA NA NA NA NA 4.1 <0.004 <0.008 0.9 NA NA NA 4.94 0.01 4178.76 8.91 89.67 Na-Mg-Cl-HCO3

96035/1 10-Jun-02 Top SG 6.58 6.6 15.65 3600 0.8 162 0.76 269 179 0.01 0 909.72 20.37 766.37 NA NA 453.3 NA 0.002 30.4 2.46 0.01 0.083 0.122 0.22 33 0.35 0.12 -1.26 2827.88 1.78 71.24 Mg-Ca-Cl-HCO3

96035/1 4-May-02 Top SG 6.84 332 18.8 3700 163.4 1.1 272.7 185.3 NA NA 908 26.6 785 NA NA NA NA NA NA 2.5 <0.004 <0.008 0.2 NA NA NA 5.73 -0.19 2344 1.78 70.81 Mg-Ca-Cl-HCO3

96035/1 5-Feb-03 Top SG 7.027 7.2 21 3450 0.71 161.07 0.67 263.36 174.12 NA NA 879.73 8.25 729.7 NA NA 292.22 NA NA NA 2.538 0.012 ####### 0.1968 NA NA NA 0.12 0.7 2513.09 1.79 71.37 Mg-Ca-Cl-HCO3

96035/2 10-Jun-02 Top SG 6.688 12.75 18.05 3655 1.03 166 1.08 302 137 0.01 0 939.71 22.77 833.49 NA NA 376.28 NA 0 12.4 2.67 ##### 0.096 0.568 0.25 20.68 0.21 0.22 -2.43 2816.15 1.81 78.42 Mg-Cl-HCO3

96035/2 5-Feb-03 Top SG 7.411 15.3 22.1 3465 1.29 160.92 1.12 293.06 126.25 NA NA 919.71 8.26 785.83 NA NA 130.27 NA NA NA 2.5715 0.013 0.08937 0.2079 NA NA NA 0.26 -1.91 2430.94 1.79 79.28 Mg-Cl-HCO3

96121/1 1-Nov-01 RC 6.7 -145.3 17.2 19270 2.6 3080 14.1 474 243 0.28 < .08 6352.03 551.26 1260.61 NA NA 682.15 NA 0.002 11.7 9.61 0.1 0.242 2.63 0.72 11 0.79 -2.52 -6.44 12696 26.49 76.28 Na-Cl

96121/1 3-Feb-03 RC 6.988 13.2 19.5 18110 0.18 3592.01 13.26 456.81 237.56 NA NA 6597.95 240.72 1217.8 NA 25.566 475.3 NA NA NA 12.469 0.092 0.15115 2.3588 NA NA NA 0.23 -1.18 12872.53 31.42 76.02 Na-Cl

96121/1 9-Jun-02 RC 6.512 -169.2 17.95 19530 2.59 3760 13.7 461 228 0.15 0 6358.03 683.09 1205.7 NA NA 642.54 NA 0.001 5.3 9.37 0.107 0.328 2.19 0.52 6.16 0.54 -2.93 0.05 13379.18 32.93 76.92 Na-Cl

96122/1 1-Nov-01 mid SG 7.058 26.3 19.55 9140 6.57 632 36.2 798 114 0.1 < .09 2883.11 132.12 1020.21 NA NA 314.67 NA 0.004 6.3 5.14 0.007 0.465 0.127 1.44 4.4 0.43 0.45 -0.45 5955.15 4.60 92.02 Mg-Na-Cl 1 Appendix B: Soil and groundwater data

Geology/ EC µS TDS -1 2+ 3+ SampleID Date Site pH Eh (mV) T ºC cm O2 Na K Mg Ca Fe Fe Cl SO4 HCO3 F Br CO2 CO3 H2S SIO2 Sr Li B Mn NH4 NO3 PO4 pe CBE (mg/l) SAR MH Wtype

96122/1 3-May-02 mid SG 7.06 -9 9720 794.6 39.7 788.6 101.3 NA NA 3094 149.3 983 NA NA 102.63 NA NA NA 4.9 <0.004 <0.008 0.1 NA NA NA -0.17 -0.41 6058 5.84 92.77 Mg-Na-Cl

96122/1 4-Feb-03 mid SG 7.467 -18 24.1 8735 1.06 766.45 41.95 781.61 20.59 NA NA 3039.06 40.85 1012.8 NA 11.129 207.72 NA NA NA 3.3127 0.011 0.68291 0.0806 NA NA NA -0.31 -1.71 5927.72 5.83 98.42 Mg-Na-Cl

96122/1 9-Jun-02 mid SG 6.905 -163.7 16.85 9785 0.7 793 36.2 790 114 0 0 3139.03 136.92 987.26 NA NA 334.47 NA 0.001 4.4 5.27 0.003 0.448 <0.002 3.19 4.84 0.32 -2.84 -0.59 6349.92 5.802 91.95 Mg-Na-Cl

96122/2 1-Nov-01 mid SG 7.383 15.9 19.55 13810 5.86 1350 37.2 977 26.9 0.04 < .02 3892.79 221.4 1452.21 NA NA 184.84 NA 0.002 9.7 2.179 0.02 0.807 0.45 2.31 7.92 0.51 0.27 1.16 8172.1 9.18 98.35 Mg-Na-Cl

96122/2 3-May-02 mid SG 7.06 -20 19.9 13600 1600.4 31.2 899.4 22.5 NA NA 4151 258.5 1562 NA NA 109.75 NA NA NA 1.9 <0.004 <0.008 0.5 NA NA NA -0.34 -0.84 8636.94 11.35 98.50 Mg-Na-Cl

96122/2 4-Feb-03 mid SG 7.646 -28.6 20.2 13770 2.43 1776.48 26.3 984 12.06 NA NA 4718.54 91.01 1581.43 NA 19.459 316.86 NA NA NA 2.3677 0.02 0.46019 0.4726 NA NA NA -0.49 -0.48 9532.33 12.10 99.26 Mg-Na-Cl

96122/2 6-Jun-02 mid SG 7.253 11.45 18.65 10550 1.01 1160 36.5 769 13.1 0.01 0 3239 157.89 1304.55 NA NA 220.05 NA 0 3.4 1.68 0.01 0.817 0.071 0.41 3.52 0.63 0.2 -0.31 6911.4 8.92 98.97 Mg-Na-Cl

96127/1 6-Feb-03 SC 7.685 -220.1 21.5 3720 3.09 494.73 3.64 214.51 63.85 NA NA 959.7 45.26 937.14 NA 3.66 105.62 NA NA NA 2.0915 0.007 0.09781 0.2982 NA NA NA -3.76 -1.05 2833.83 6.6 84.70 Na-Mg-Cl-HCO3

96127/1 9-Jun-02 SC 7.366 -166.7 19.15 4100 0.3 743 5.74 137 44 0.13 0.47 959.7 122.54 915.26 NA NA 151.83 NA 0.01 4.7 0.946 0.003 0.136 0.184 0.58 0 2.8 -2.87 1.45 2502.61 12.45 83.69 Na-Mg-Cl-HCO3

96128/1 10-Jun-02 top SG 7.091 47.5 18.5 8940 1.31 1690 14.1 185 54.9 0.07 0 2699.16 100.37 994.58 NA NA 422.49 NA 0.001 12.7 2.68 <0.004 0.742 0.42 0.13 4.4 1.08 0.82 -1.45 5665.64 24.53 84.74 Na-Cl

96128/1 4-May-02 top SG NA NA NA NA NA 1726.5 15.3 193.1 61.2 NA NA 2674 109.7 1026 NA NA NA NA NA NA 2.9 <0.004 <0.008 0.6 NA NA NA NA 0 5282.98 24.40 83.87 Na-Cl

96128/1 5-Feb-03 top SG 7.56 -21.5 25.4 8520 0.61 1622.1 12.17 185.23 44.1 NA NA 2759.14 24.28 1015.24 NA 10.892 147.87 NA NA NA 3.1375 0.003 0.48469 0.3991 NA NA NA -0.36 -3.65 5825.93 23.8 87.3816 Na-Cl

96128/2 4-May-02 top SG NA NA NA NA NA 748.1 3.6 338.5 106 NA NA 1732 96 893 NA NA NA NA NA NA 2.5 <0.004 <0.008 <0.002 NA NA NA NA 0.26 3919.58 7.99 84.03 Na-Mg-Cl-HCO3

96128/2 5-Feb-03 top SG 7.251 -5 20.2 6160 0.08 718.64 2.89 351.78 103.78 NA NA 1959.39 28.16 868.81 NA 7.177 278.14 NA NA NA 2.948 0.01 0.16017 0.0178 NA NA NA -0.09 -3.43 4322.1 7.56 84.82 Na-Mg-Cl-HCO3

96128/2 9-Jun-02 top SG 6.703 9.7 19.3 6210 0.06 747 3.01 339 103 0.02 0 1799.44 84.79 898.17 NA NA 448.9 NA 0.003 9.1 2.48 0.008 0.206 <0.002 0.05 41.36 0.45 0.17 -1.69 4476.93 7.9 84.43 Na-Mg-Cl-HCO3

96129/1 6-Feb-03 SC 7.594 -29.8 23.2 15000 1.17 2258.05 13.73 767.36 198.3 NA NA 5438.31 284.87 549.11 NA 22.888 98.58 NA NA NA 7.6972 ##### 0.32561 0.2213 NA NA NA -0.51 0.93 9640.98 16.25 86.44 Na-Mg-Cl

96129/1 9-Jun-02 SC 7.434 -49.1 19.8 15015 3.01 2150 16 696 200 0.02 0 5078.43 722.04 517.43 NA NA 105.62 NA 0.001 8.8 6.42 0.005 0.581 0.094 2.45 4.84 0.32 -0.84 -1.64 9512.08 16.12 85.15 Na-Mg-Cl

96129/2 6-Feb-03 SC 7.556 -21.4 21.2 4810 1.01 532.42 1.37 317.99 67.9 NA NA 1399.53 62.21 746.79 NA 5.483 130.27 NA NA NA 2.4297 0.01 0.15844 0.1786 NA NA NA -0.37 -0.25 3267.95 6.02 88.53 Mg-Na-Cl-HCO3

96129/2 9-Jun-02 SC 7.059 -57.2 19.25 5070 1.65 544 1.57 328 70.7 0.06 0 1379.57 181.86 800.54 NA NA 215.65 NA 0.004 14.4 2.27 0.007 0.195 0.163 1.02 10.12 0.55 -0.99 -1.51 3552.28 6.05 88.43 Mg-Na-Cl-HCO3

96130/1 3-Feb-03 RC 7.034 7.5 19.3 9590 1.83 1259.21 13.68 465.12 328.62 NA NA 3039.06 134.6 1173.87 NA 1.302 485.86 NA NA NA 10.496 0.062 0.14245 1.2541 NA NA NA 0.13 1.08 6915.10 10.47 70 Na-Mg-Cl

96130/1 9-Jun-02 RC 6.475 -173.4 18.8 9810 0.22 1540 12.4 381 218 2.74 0.03 2879.11 64.71 1470.51 NA NA 1166.26 NA 0.171 35.2 4.45 0.047 0.243 0.813 1.94 6.16 0.91 -2.99 1.44 7784.7 14.57 74.2 Na-Mg-Cl-HCO3

96131/1 10-Jun-02 Talbragar 6.916 22.4 18.9 443.5 2.3 88 2.26 4.41 4.84 0 1.85 59.98 39.85 124.47 NA NA 46.21 NA 0 NA 0.002 <0.004 0.05 0.062 NA 0 NA 0.39 0.33 246.5 6.96 60.03 Na-HCO3-Cl

96132/2 6-Feb-03 RC 7.439 -110 23.9 23050 3.5 4669.19 2.43 675.38 64.14 NA NA 8557.35 317.93 985.95 NA 30.646 144.35 NA NA NA 10.299 0.033 ####### 0.0367 NA NA NA -1.87 -0.44 15461.6 37.46 94.5 Na-Mg-Cl

96132/2 9-Jun-02 RC 6.591 -126.4 18.85 23250 1.02 4670 2.67 608 65.6 0.03 0 8877.25 847.87 859.12 NA NA 391.69 NA 0.003 2.8 7.98 0.036 0.235 0.152 2.23 8.8 0.93 -2.18 -4.72 16346.33 39.3 93.8 Na-Cl

96133/1 1-Nov-01 Site 1 6.779 34.8 17.5 7750 0.78 181 40.7 478 561 0.19 < .18 2673.17 60.82 350.24 NA NA 167.24 NA 0.005 19.3 9.6 0.006 0.144 1.05 0.28 3.52 1.01 0.6 -3.76 4548 1.35 58.41 Mg-Ca-Cl

96133/1 2-Feb-03 Site 1 7.184 0.1 20.4 7105 2.21 209.69 17.85 549.79 460.41 NA NA 2599.19 10.28 488.1 NA 8.02 144.35 NA NA NA 11.709 0.001 0.17001 1.6013 NA NA NA 0 -2.19 4504 1.56 66.31 Mg-Ca-Cl

96133/1 4-May-02 Site 1 6.88 -8 18.1 8020 203.9 28.7 521.1 550.3 NA NA 2653 34.5 411 NA NA NA NA NA NA 10.4 <0.004 <0.008 2.3 NA NA NA -0.14 -1.25 4415.14 1.49 60.95 Mg-Ca-Cl

96133/1 6-Jun-02 Site 1 6.53 15.75 20 7545 1.68 242 20.3 529 470 0.06 0 2539.21 40.45 460.07 NA NA 270.66 NA 0.003 9.9 9.82 <0.004 0.232 0.79 3.46 3.52 0.26 0.27 -1.01 4601.49 1.81 64.98 Mg-Ca-Cl

98036 10-Jun-02 top SG 6.882 22.65 17.65 9890 2.44 1370 5.99 495 125 0 0 3139.03 121.64 1184.95 NA NA 532.52 NA 0.001 6.1 4.99 ##### 0.306 2.57 1.15 3.96 0.65 0.39 -1.65 6996.17 12.29 86.7 Na-Mg-Cl

98036 4-May-02 top SG 7.15 105 21.2 9890 1338 7.2 480.7 113.2 NA NA 2943 103.4 1135 NA NA NA NA NA NA 4.8 <0.004 <0.008 3.3 NA NA NA 1.8 0.02 6128.45 12.24 87.50 Na-Mg-Cl

98036 5-Feb-03 top SG 7.427 -16.3 24.3 9680 2.5 1342.3 5.01 514.31 121.58 NA NA 3239 44.17 1098.22 NA 12.238 193.64 NA NA NA 5.5624 0.012 0.20219 1.8526 NA NA NA -0.28 -1.53 6581.41 11.8 87.4 Na-Mg-Cl

98037 2-Feb-03 Site 1 7.425 -16.3 21.3 11085 2.47 1243.53 3.17 813.96 99.97 NA NA 3958.77 88.61 820 NA 15.512 105.62 NA NA NA 11.09 0.004 0.39234 0.8373 NA NA NA -0.28 -0.28 7164.4 9 93.06 Mg-Na-Cl

98037 4-May-02 Site 1 7.13 -22 19 1250 1287.9 4.7 854.6 142.2 NA NA 4040 277.7 589 NA NA NA NA NA NA 10.8 <0.004 <0.008 2.1 NA NA NA -0.38 1.7 7208.9 9 90.8 Mg-Na-Cl

98037 6-Jun-02 Site 1 6.864 -17.05 20.35 11285 3.63 1230 4.24 748 117 0.01 0 3758.83 252.56 887.19 NA NA 286.06 NA 0.001 19.4 9.63 <0.004 0.641 0.977 2.71 5.72 0.46 -0.29 -1.83 7327 9.21 91.3 Mg-Na-Cl

98038 10-Jun-02 top SG 6.63 10.3 18 7565 0.89 659 9.58 418 372 0.15 0 2579.2 87.78 939.66 NA NA 585.33 NA 0.005 5.9 6.49 <0.004 0.207 0.776 0.75 6.16 0.31 0.18 -4.65 5672.0 5.57 64.94 Mg-Na-Ca-Cl p56 24-Nov-97 Site 2 NA NA NA NA NA 2234.36 2.96 287.36 124.36 NA NA 3400 670 1290 NA NA NA NA NA 17.18 <0.0001 <0.004 0.83 <0.002 NA NA NA NA -1.51 7214.0 25.15 79.26 Na-Cl p56 3-Feb-03 Site 2 7.298 -7.5 22.4 9925 3.15 1951.93 0.79 216.43 103.74 NA NA 2999.07 178.54 1193.39 NA 13.119 267.57 NA NA NA 3.8979 0.043 0.27089 0.098 NA NA NA -0.13 0.01 6317.03 25 77.4 Na-Cl p56 8-Jun-02 Site 2 6.579 -103.2 18.9 10275 1.17 2000 0.61 217 104 0.05 0 2979.08 500.33 1150.78 NA NA 674.23 NA 0.007 9.6 3.49 0.039 0.43 1.06 0.23 5.72 0.24 -1.78 -1.42 6876.07 25.62 77.47 Na-Cl p57 1-Nov-01 mid SG 6.695 -16.4 18.8 8050 1.62 588.54 6.78 569 210 0.01 0.02 2503.22 135.1 901.83 NA NA 503.91 NA 0.001 20.9 4.95 0.011 0.135 0.107 0.25 12.32 0.88 -0.28 -3.04 5459.47 4.783 81.7 Mg-Na-Cl p57 24-Nov-97 mid SG NA NA NA NA NA 700.79 8.75 666.86 220.51 NA NA 2730 150 1100 NA NA NA NA NA 17.26 <0.0001 <0.004 0.22 <0.002 NA NA NA NA -0.81 5594.36 5.31 83.29 Mg-Na-Cl p57 6-Feb-03 mid SG 6.961 12.8 23.4 7590 0.49 619.04 7.52 580.64 216.13 NA NA 2559.21 45.44 832.2 NA 9.771 383.76 NA NA NA 6.0379 ##### 0.12743 0.1398 NA NA NA 0.22 -0.62 5260.9 4.97 81.58 Mg-Na-Cl p57 9-Jun-02 mid SG 6.444 -66.85 17.5 7875 1.28 627 7.65 559 220 0.02 0 2719.16 127.33 888.41 NA NA 620.54 NA 0.001 7.9 5.16 0.006 0.165 <0.002 0.21 10.12 0.48 -1.16 -5.33 5794.3 5.11 80.72 Mg-Na-Cl p58 1-Nov-01 top SG 6.901 -145 19.1 4650 0.81 456 0.43 268 77.2 0.01 0 1233.62 27.29 888.41 NA NA 349.88 NA 0.007 14.7 1.81 0.01 0.098 0.8 0.21 3.96 1.23 -2.5 -4.37 3324.3 5.51 85.12 Mg-Na-Cl-HCO3 p58 10-Jun-02 top SG 6.826 -11.1 18.25 5535 2.3 685 1.49 295 87.4 0.25 0.07 1559.52 42.84 960.41 NA NA 356.48 NA 0.002 14.8 2.38 0.004 0.143 0.934 0.41 5.28 0.67 -0.19 -1.79 4015.4 7.8 84.76 Na-Mg-Cl-HCO3 p58 24-Nov-97 top SG NA NA NA NA NA 598.86 1.55 303.59 86.57 NA NA 1380 30 1320 NA NA NA NA NA 27.81 <0.0001 <0.004 2.09 <0.002 NA NA NA NA -4.98 3750.43 6.8 85.25 Na-Mg-Cl-HCO3 p58 5-Feb-03 top SG 7.202 -3.4 21.7 4535 0.43 525.64 0.46 262.97 82.26 NA NA 1359.58 8.27 890.78 NA 4.806 225.33 NA NA NA 2.1126 ##### ####### 1.5007 NA NA NA -0.06 -4.37 3364.67 6.37 84.05 Na-Mg-Cl-HCO3 p59 10-Jun-02 top SG 7.181 -35.35 18.2 4515 1.4 881 7.9 81.3 47.5 0.28 0 1049.67 22.35 1132.48 NA NA 303.67 NA 0.028 6.9 0.703 <0.004 0.125 1.68 0.39 1.32 0.57 -0.61 -1.02 2664.6 18 73.83 Na-Cl-HCO3 p59 5-Feb-03 top SG 8.182 -60.3 26.8 4200 4.23 813.4 6.71 77.29 42.22 NA NA 1039.68 9.21 1025 NA NA 38.73 NA NA NA 0.7293 0.001 ####### 0.2508 NA NA NA -1.01 -2.51 2281.47 17.19 75.1 Na-Cl-HCO3 p60 10-Jun-02 top SG 7.279 -27.85 18.6 7345 1.21 1470 0.56 237 2.16 0.03 0 1839.43 37.75 1784.14 NA NA 378.48 NA 0.006 5.8 0.527 0.005 0.33 0.026 0.13 4.4 0.42 -0.48 0.96 4542.86 20.4 99.45 Na-Mg-Cl-HCO3 p60 24-Nov-97 top SG NA NA NA NA NA 155.54 1.91 317.54 4.73 NA NA 2130 70 2870 NA NA NA NA NA 15.72 <0.0001 <0.004 0.58 <0.002 NA NA NA NA -53.19 3443.25 1.86 99.10 Mg-Cl-HCO3 p60 5-Feb-03 top SG 7.735 -27.8 21.4 7350 0.82 1382.28 0.62 249.38 2.38 NA NA 2039.37 13.19 1732.74 NA 8.296 133.79 NA NA NA 0.7188 ##### 0.2343 0.1137 NA NA NA -0.48 -3.29 4442.43 18.71 99.42 Na-Mg-Cl-HCO3 p61 10-Jun-02 top SG 6.913 -1.35 18.2 5850 5.93 535 2.64 395 123 0.05 0 1699.47 21.33 940.88 NA NA 321.27 NA 0.009 10.3 4.26 <0.004 0.357 1.1 0.45 0.44 0.29 -0.02 -1.33 4061.66 5.2 84.1 Mg-Na-Cl-HCO3 2 Appendix B: Soil and groundwater data

Geology/ EC µS TDS -1 2+ 3+ SampleID Date Site pH Eh (mV) T ºC cm O2 Na K Mg Ca Fe Fe Cl SO4 HCO3 F Br CO2 CO3 H2S SIO2 Sr Li B Mn NH4 NO3 PO4 pe CBE (mg/l) SAR MH Wtype p61 24-Nov-97 top SG NA NA NA NA NA 438.41 3.96 388.5 116.32 NA NA 1450 0 1000 NA NA NA NA NA 13.41 <0.0001 <0.004 0.93 <0.002 NA NA NA NA -0.31 3411.55 4.38 84.63 Mg-Na-Cl-HCO3 p61 5-Feb-03 top SG 7.371 -11.9 23.1 5535 1.27 499.25 2.42 397.46 115.81 NA NA 1759.45 6.87 856.61 NA 7.13 179.56 NA NA NA 4.5515 0.002 0.27943 1.2871 NA NA NA -0.2 -2.8 3833.11 4.95 84.98 Mg-Na-Cl-HCO3 p62 24-Nov-97 Site 3 NA NA NA NA NA 1099.32 2.72 608.35 72.52 NA NA 3210 130 700 NA NA NA NA NA 17.5 <0.0001 <0.004 1.55 <0.002 NA NA NA NA -1.54 5842.02 9.23 93.25 Mg-Na-Cl p62 4-Feb-03 Site 3 7.281 -6.7 21 8320 0.61 1107.85 1.15 483.69 42.48 NA NA 2799.13 36.87 868.81 NA NA 299.26 NA NA NA 3.774 0.006 0.23352 1.1416 NA NA NA -0.11 -2 5645.5 10.52 94.94 Na-Mg-Cl p62 5-Jun-02 Site 3 6.647 -44.6 18.75 8630 1.04 1180 1.21 475 45.2 0.03 0 2699.16 107.26 922.58 NA NA 314.67 NA 0.001 8.8 3.25 <0.004 0.332 1.31 0.34 3.96 0.22 -0.77 -0.39 5764.2 11.29 94.54 Na-Mg-Cl p63 24-Nov-97 Site 3 NA NA NA NA NA 1259.76 2.79 176.29 46.15 NA NA 1800 160 1860 NA NA NA NA NA 24.15 <0.0001 <0.004 3.52 <0.002 NA NA NA NA -8.27 3877.08 18.90 86.29 Na-Cl-HCO3 p63 4-Feb-03 Site 3 7.766 -35.5 22.1 5240 1.61 1016.03 1.02 117.39 30.66 NA NA 1439.55 27.2 1107.98 NA 5.115 73.94 NA NA NA 1.2756 0.005 0.39256 0.1287 NA NA NA -0.61 -3.44 3033.2 18.68 86.32 Na-Cl-HCO3 p63 5-Jun-02 Site 3 7.184 -34.95 18.95 5505 2.05 1060 0.71 115 30.9 0.01 0 1429.56 75.2 1055.6 NA NA 184.84 NA 0.001 22.4 1.11 0.003 0.483 <0.002 0.08 4.84 0.49 -0.6 -1.82 3210.80 19.6 85.98 Na-Cl-HCO3 p65 24-Nov-97 mid SG NA NA NA NA NA 958.11 4.27 284.72 55.27 NA NA 1590 90 1620 NA NA NA NA NA 14.09 <0.0001 <0.004 0.82 <0.002 NA NA NA NA -3.76 3726.70 11.5 89.4 Na-Mg-Cl-HCO3 p65 6-Feb-03 mid SG 7.578 -272.1 23.2 6485 0.06 1034.33 1.58 270.44 48.55 NA NA 1759.45 21.73 1327.62 NA 7.503 239.41 NA NA NA 3.8176 0.002 0.48157 1.8808 NA NA NA -4.63 -1.46 4717.21 12.8 90.18 Na-Mg-Cl-HCO3 p65 7-Jun-02 mid SG 7.031 -201.8 18.5 6495 0.98 1040 2.15 263 49.4 0.1 0.03 1899.41 120.74 1358.24 NA NA 327.87 NA 2.04 3.9 3.15 <0.004 0.642 2.58 6.06 14.96 1.55 -3.49 -5.88 4386.21 13.03 89.7 Na-Mg-Cl-HCO3

R1 17-Sep-02 Rain NA NA NA NA NA 9.65 16.51 1.28 3.95 NA NA 10 4.4 NA NA NA NA NA NA NA 0.0382 2E-04 0.0143 0.0434 NA NA NA NA 51 46.07 1.07 34.8 K-Na-Ca-Cl

R2 1-Jan-03 Rain NA NA NA NA NA 0.27 0.12 0.05 0.19 NA NA 2 0.27 NA NA 0.028 NA NA NA NA 0.0023 5E-05 0.00131 ###### NA NA NA NA -29.54 3.11 0.14 30.25 Na-Cl

S10 12-Jun-02 Site 1 6.858 11.1 15 8335 2.88 929 32 376 435 0.01 0 3139.03 79.39 483.26 NA NA 173.84 NA NA 10.3 9.31 <0.004 0.35 0.292 2.09 13.2 NA 0.19 -2.14 5686.04 7.87 58.76 Na-Mg-Ca-Cl

S11 12-Jun-02 Site 1 7.29 5.15 14.65 8340 3.19 858 21 513 217 0 0.04 2879.11 96.77 624.82 NA NA 202.45 NA 0.006 6.6 11.3 <0.004 0.46 <0.002 0.67 13.2 0.27 0.09 -1.35 5447.99 7.2 79.58 Mg-Na-Cl

S11 2-Feb-03 Site 1 7.69 -30.7 32 5560 3.53 713.14 20.14 310.06 97.59 NA NA 1799.44 21.44 666.25 NA 7.975 105.62 NA NA 7.9486 0.003 0.73743 1.5241 NA NA NA -0.51 -0.04 3756.78 7.9 83.9 Na-Mg-Cl

S12 4-Feb-03 Site 3 7.899 -42.9 21.5 5730 2.95 725.31 16.27 334.86 20.22 NA NA 1919.4 20.05 610.12 NA 6.653 84.5 NA NA 2.3702 0.004 0.33617 0.1119 NA NA NA -0.73 -3.23 3743.98 8.34 96.4 Na-Mg-Cl

S12 5-Jun-02 Site 3 7.149 -30.25 18.3 6160 1.17 763 20.5 336 34 0.01 0 1919.4 56.32 604.07 NA NA 127.63 NA 0.005 17.8 2.48 <0.004 0.459 0.191 0.19 8.8 0.52 -0.52 -1.75 3892.49 8.6 94.2 Na-Mg-Cl

S13a 4-Feb-03 Site 3 7.361 -11.6 20.3 5445 1.91 894.49 1.08 263.16 51.78 NA NA 1679.48 29.22 812.68 NA 5.875 158.43 NA NA 1.7434 0.002 0.17644 0.0447 NA NA NA -0.2 1.48 3900.39 11.17 89.33 Na-Mg-Cl-HCO3

S13a 5-Jun-02 Site 3 6.803 -48.85 18.9 5710 0.99 861 1.44 232 49.3 0.01 0 1619.5 82.39 872.54 NA NA 261.86 NA 0.001 9.4 1.99 <0.004 0.29 0.031 0.17 3.52 0.4 -0.84 -2.21 3996.72 11.41 88.58 Na-Mg-Cl-HCO3

S13b 4-Feb-03 Site 3 7.442 -15.3 21.2 6155 1.3 1153.5 0.64 148.4 24.9 NA NA 1719.47 37.24 998.16 NA 6.988 200.68 NA NA 1.3349 0.003 0.24186 0.8169 NA NA NA -0.26 -1.56 3676.17 19.34 90.76 Na-Cl-HCO3

S13b 5-Jun-02 Site 3 6.992 -57.45 19.45 6865 1.4 1380 1.05 170 34.7 0.01 0 1939.4 128.83 959.19 NA NA 202.45 NA 0.004 7.6 1.39 <0.004 0.367 0.29 0.63 4.4 0.39 -0.99 1.78 4263.9 21.41 88.98 Na-Cl-HCO3

S13c 4-Feb-03 Site 3 7.386 -12.5 19.5 5860 0.75 725.54 0.7 338.87 75.32 NA NA 1759.45 31.92 780.95 NA 6.947 176.04 NA NA 2.9528 0.007 0.11828 1.211 NA NA NA -0.22 0.12 3901.3 7.9 88.12 Na-Mg-Cl-HCO3

S13c 5-Jun-02 Site 3 6.867 -69.45 19.05 6020 1.09 807 0.67 298 68.2 0.03 0 1759.45 96.77 823.73 NA NA 294.87 NA 0.001 22.9 2.32 0.003 0.157 0.29 0.01 6.16 0.22 -1.2 -1.67 4181.8 9.39 87.81 Na-Mg-Cl-HCO3

S13d 4-Feb-03 Site 3 7.491 -19.8 19.3 5580 2.06 578.89 1.43 376.36 99.28 NA NA 1839.43 28.18 739.47 NA 6.424 133.79 NA NA 3.2318 0.006 0.11025 0.3377 NA NA NA -0.34 -2.73 3809.6 5.94 86.2 Mg-Na-Cl

S13d 5-Jun-02 Site 3 6.837 -78.3 18.85 5685 0.77 624 0.95 333 88.6 0.18 0 1679.48 78.5 796.88 NA NA 277.26 NA 0.008 18.3 2.66 0.005 0.133 1.02 0.25 5.28 1.54 -1.35 -2.55 3908.7 6.8 86.10 Mg-Na-Cl-HCO3

S14a 10-Jun-02 Site 3 7.424 211 13.15 20040 5.88 2650 30.1 966 402 0 0 7737.6 183.36 469.83 NA NA 158.44 NA 0.004 7 7.93 <0.004 0.182 <0.002 6.32 44 0.31 3.71 -3.22 12668.9 16.3 79.8 Na-Mg-Cl

S14b 4-Feb-03 Site 3 7.415 -15.3 22.9 5330 2.03 508.7 5.62 348.24 123.74 NA NA 1759.45 19.08 673.57 NA 6.137 147.87 NA NA 3.5548 0.005 0.16808 0.0414 NA NA NA -0.26 -3.34 3598.76 5.3 82.26 Mg-Na-Cl

S14b 5-Jun-02 Site 3 6.933 -36.05 18.8 6060 2.37 596 5.86 360 136 0.03 0 1879.42 54.23 694.37 NA NA 160.64 NA 0.004 14.8 3.38 0.003 0.195 0.192 0.21 8.36 0.23 -0.62 -2.41 3916.26 6 81.3 Mg-Na-Cl

S14c 10-Jun-02 Site 3 6.672 3.35 18 4295 0.73 976 5.89 292 141 0 0 1329.59 53.93 866.44 NA NA 360.88 NA 0.001 8.8 8.25 ##### 1 0.148 1.02 13.2 0.24 0.06 16.44 4059.01 10.7 77.3 Na-Mg-Cl-HCO3

S14c 4-Feb-03 Site 3 7.705 -31.6 22.5 4140 2.93 399.26 2.18 271.7 103.51 NA NA 1199.63 24.71 785.83 NA 4.194 119.7 NA NA 2.3981 0.008 0.14628 0.1965 NA NA NA -0.54 -2.45 2917.03 4.6 81.2 Mg-Na-Cl-HCO3

S15a 4-Feb-03 Site 3 7.388 -12 22.8 4745 0.78 502.48 7.21 317.08 43.06 NA NA 1359.58 25.67 754.11 NA 4.854 123.23 NA NA 3.7275 0.004 0.28635 0.0965 NA NA NA -0.2 -0.92 3142.48 5.8 92.38 Mg-Na-Cl-HCO3

S15a 5-Jun-02 Site 3 6.702 -52.75 18.5 4900 0.42 533 7.94 311 46.1 0 0 1379.57 78.2 781.02 NA NA 316.87 NA 0.004 8.8 3.33 <0.004 0.366 0.16 0.4 4.4 0.13 -0.91 -1.95 3471.61 6.2 91.75 Mg-Na-Cl-HCO3

S15b 4-Feb-03 Site 3 7.378 -13.7 23 4360 0.15 337.23 0.52 327.47 112.72 NA NA 1319.59 26.31 646.73 NA 4.54 168.99 NA NA 3.155 0.006 0.14433 0.4807 NA NA NA -0.23 -1.13 2948.21 3.6 82.72 Mg-Na-Cl-HCO3

S15b 5-Jun-02 Site 3 6.994 -37.6 19.4 4575 1.46 357 2.09 311 125 0.01 0 1299.6 75.2 654.1 NA NA 171.64 NA 0.004 18.7 3.03 ##### 0.166 0.845 0.19 6.6 0.41 -0.65 -1.59 3027.36 3.8 80.39 Mg-Na-Cl-HCO3

S1a 1-Nov-01 Site 1 7.222 39.1 17.45 6560 0.38 939.93 2.65 245 88.3 0.01 0.06 1963.39 47.3 807.87 NA NA 121.03 NA 0.003 9.6 6.38 0.014 0.725 0.816 0.17 3.52 0.58 0.68 -2.93 4237.7 11.6 82.06 Na-Mg-Cl

S1a 2-Feb-03 Site 1 7.493 -20.2 23.4 6070 2.85 866.98 6.58 260.7 115.92 NA NA 1959.39 17.23 695.54 NA 8.251 52.81 NA NA 8.1512 0.011 0.80483 0.1145 NA NA NA -0.34 -1.37 3995.79 10.2 78.75 Na-Mg-Cl

S1a 6-Jun-02 Site 1 6.925 -48 19.45 7130 1.32 416 2.4 270 105 0.01 0 1999.38 69.51 721.22 NA NA 151.83 NA 0.002 9.5 2.32 0.005 0.156 1.28 0.19 5.28 0.18 -0.83 -20.81 3755.5 4.8 80.91 Mg-Na-Cl-HCO3

S1b 1-Nov-01 Site 1 7.649 28 18.45 6400 2.42 1258.4 2.53 125 22.7 0.01 0.05 1683.48 53.9 1339.94 NA NA 110.02 NA 0.002 10.5 3 0.015 0.835 1.09 0.26 3.52 0.5 0.48 -3.13 3587.1 22.9 90.07 Na-Cl-HCO3

S1b 2-Feb-03 Site 1 8.659 -89.2 24.2 6715 2.22 1513.94 2.63 95.7 19.12 NA NA 1759.45 15.66 1683.93 NA 7.523 0 120 NA 2.2934 0.012 0.79568 0.6946 NA NA NA -1.51 -4.35 3675.9 31.34 89.19 Na-Cl-HCO3

S1b 6-Jun-02 Site 1 7.25 -142.4 19.85 6795 0.82 1770 2.17 90 18.5 2.84 0.57 1699.47 50.63 1850.04 NA NA 310.27 NA 0.003 12.1 1.85 0.008 1.09 1.25 0.63 1.32 0.73 -2.45 3.8 4182.4 37.73 88.91 Na-Cl-HCO3

S1c 1-Nov-01 Site 1 6.72 -192 18.5 10680 0.35 1740 3.18 323 113 0.19 < .04 3482.92 173.77 1255.73 NA NA 407.09 NA 0.089 10.7 5.41 0.033 0.399 2.43 0.43 7.04 0.51 -3.32 -6.2 7526.1 18.85 82.49 Na-Mg-Cl

S1c 2-Feb-03 Site 1 7.687 -30.9 21 10330 3.21 1878.42 2.43 322.28 100.64 NA NA 3438.93 56.99 1132.38 NA 13.318 42.25 NA NA 5.8248 0.026 0.26586 0.3015 NA NA NA -0.53 -1.49 6998.3 20.5 84.07 Na-Mg-Cl

S1c 6-Jun-02 Site 1 6.638 -51.2 19.65 10760 1.14 1900 2.5 311 115 0.26 0 3219 160.89 1258.17 NA NA 431.3 NA 0.003 10.2 5.2 0.028 0.432 1.89 0.28 7.04 0.58 -0.88 -0.27 7424.75 20.8 81.6 Na-Mg-Cl

S2a 1-Nov-01 Site 1 7.156 -2 17.6 4910 1.08 449.15 2.72 255 99.5 0.03 < .02 1393.57 38.3 745.63 NA NA 213.45 NA 0.003 13.3 5.25 0.008 0.39 1.92 0.21 4.4 0.62 -0.03 -6.78 3224.4 5.42 80.8 Mg-Na-Cl-HCO3

S2a 2-Feb-03 Site 1 7.412 -21.8 26.5 4580 3.82 497.71 3.21 285.56 127.13 NA NA 1479.54 15.64 690.66 NA 5.966 123.23 NA NA 6.5429 0.009 0.42571 0.4996 NA NA NA -0.37 -1.61 3241.0 5.6 78.7 Mg-Na-Cl-HCO3

S2a 6-Jun-02 Site 1 6.832 -21.8 19 4965 1.94 523 2.92 281 115 0 0 1499.54 42.54 796.88 NA NA 277.26 NA 0.002 28 5.93 0.003 0.528 0.055 0.18 7.48 0.23 -0.38 -4.2 3582.3 5.9 80.11 Mg-Na-Cl-HCO3

S2b 1-Nov-01 Site 1 7.256 58.6 21.3 4280 2.45 338 3.62 295 97.3 0.02 0 1273.61 46.44 790.78 NA NA 162.84 NA 0.003 16.2 5.6 0.016 0.314 3.14 0.59 5.72 0.42 1 -6.1 3041.9 3.85 83.3 Mg-Na-Cl-HCO3

S2b 2-Feb-03 Site 1 7.691 -5.15 20.5 3975 5.4 342.69 2.65 263.69 124.55 NA NA 1199.63 14.56 671.13 NA 4.879 172.52 NA NA 5.7301 0.018 0.23082 0.0467 NA NA NA -0.09 -2.45 2808.13 3.9 77.73 Mg-Na-Cl-HCO3

S2b 6-Jun-02 Site 1 6.736 -5.15 18.45 4185 2.87 351 2.74 260 136 0.08 0 1119.65 41.94 833.49 NA NA 266.26 NA 0.001 14.1 5.17 0.015 0.274 0.855 0.28 10.56 0.24 -0.09 -2.89 3045.4 4.06 75.9 Mg-Na-Cl-HCO3

S2c 1-Nov-01 Site 1 7.097 -201.8 20.1 4750 0.5 417.21 8.46 258 160 0.26 < .03 1333.59 43.7 782.24 NA NA 173.84 NA 0.335 11.6 4.91 0.016 0.241 2.67 0.62 9.24 0.41 -3.47 -3.69 3207.7 4.74 72.66 Mg-Na-Cl-HCO3

S2c 2-Feb-03 Site 1 7.605 -46.3 19.6 4525 4.74 419.43 7.9 225.25 156.13 NA NA 1239.62 15.73 710.18 NA 5.317 91.54 NA NA 6.5531 0.013 0.15772 1.0194 NA NA NA -0.8 -2.2 2886.14 5.02 70.40 Mg-Na-Cl-HCO3 3 Appendix B: Soil and groundwater data

Geology/ EC µS TDS -1 2+ 3+ SampleID Date Site pH Eh (mV) T ºC cm O2 Na K Mg Ca Fe Fe Cl SO4 HCO3 F Br CO2 CO3 H2S SIO2 Sr Li B Mn NH4 NO3 PO4 pe CBE (mg/l) SAR MH Wtype

S2c 6-Jun-02 Site 1 6.542 -46.25 19.45 4830 0.69 477 8.79 252 177 0.01 0 1359.58 39.85 807.87 NA NA 466.5 NA 0.003 24.2 5.17 0.012 0.246 4.14 0.45 9.24 0.1 -0.8 -1.67 3632.7 5.39 70.12 Na-Mg-Cl-HCO3

S3a 1-Nov-01 Site 1 7.255 11.5 20.2 2750 2.28 170 5.09 138 138 0.02 < .02 723.78 21.21 439.32 NA NA 90.22 NA 0 24.2 3.23 0.008 0.038 4.84 0.53 7.92 0.33 0.2 -3.95 1768.95 2.44 62.24 Mg-Na-Ca-Cl-HCO3

S3a 2-Feb-03 Site 1 7.615 -62 19.5 3000 1.2 223.69 4.44 164.38 145.35 NA NA 879.73 7.51 422.2 NA 4.111 95.06 NA NA 4.3001 0.006 0.03872 1.2486 NA NA NA -1.07 -1.84 1956.42 3.01 65.09 Mg-Na-Ca-Cl-HCO3

S3a 6-Jun-02 Site 1 6.967 -62.05 18.1 2940 1.23 210 4.71 150 146 0.01 0 819.75 17.68 427.12 NA NA 116.63 NA 0.001 8.8 3.62 <0.004 0.034 2.51 0.58 6.6 0.08 -1.07 -2.53 1915.31 2.91 62.87 Mg-Na-Ca-Cl-HCO3

S3b 2-Feb-03 Site 1 7.797 -68 20.4 2575 0.5 240.47 3.48 136.81 89.32 NA NA 679.79 5.34 539.35 NA 3.12 66.89 NA NA 3.1582 0.009 0.07471 0.36 NA NA NA -1.17 -3.29 1769.78 3.73 71.63 Mg-Na-Cl-HCO3

S3b 6-Jun-02 Site 1 6.755 -68.15 17.6 2930 0.55 270 3.41 153 99.8 0.86 0 729.77 15.25 605.29 NA NA 173.84 NA 0.001 18.7 3.42 0.006 0.074 2.19 0.7 6.6 0.12 -1.18 -2.15 2083.5 3.96 71.65 Mg-Na-Cl-HCO3

S4 1-Nov-01 Site 1 7.135 78 18.9 1303 2.76 105 3.59 41.5 93.6 0.04 0 96.47 15.19 491.8 NA NA 132.03 NA 0.002 29.2 1.03 0.004 ####### 0.203 0.18 27.72 0.51 1.35 5.05 782.2 2.27 42.2 Ca-Na-Mg-HCO3-Cl

S4 2-Feb-03 Site 1 7.303 -6.7 23.9 1464 4.15 142.12 2.34 49.17 107.64 NA NA 279.91 5.17 451.49 NA 1.674 88.02 NA NA 1.3957 0.001 0.07572 0.1431 NA NA NA -0.11 0.89 1133.59 2.84 42.93 Na-Ca-Mg-Cl-HCO3

S4 6-Jun-02 Site 1 6.805 -29.85 18.6 1531.5 2.63 145 2.63 45.7 110 0.01 0 259.92 13.36 505.22 NA NA 160.64 NA 0.001 27.7 1.25 <0.004 0.081 ###### 0.44 27.28 0.27 -0.52 -2.06 1302.16 2.93 40.6 Na-Ca-Mg-HCO3-Cl

S5 1-Nov-01 Site 2 7.401 -77 20.05 4050 1.55 755 2.4 89.8 64.2 0.01 0 973.7 180.66 721.22 NA NA 85.82 NA 0.001 9.8 1.67 0.007 0.383 0.756 0.26 7.92 0.72 -1.32 0.44 2379.57 14.27 69.75 Na-Cl-HCO3

S5 3-Feb-03 Site 2 7.656 -27.9 25.1 5200 2.26 958.24 1.61 118.26 73.69 NA NA 1519.53 70.38 883.45 NA 6.165 84.5 NA NA 2.6688 0.011 0.65947 0.0418 NA NA NA -0.47 -3.22 3196.64 16.09 72.5 Na-Cl-HCO3

S5 6-Jun-02 Site 2 6.906 -14.6 17.55 12435 1.31 2080 4.95 305 247 0 0 4118.72 308.59 584.54 NA NA 149.63 NA 0.001 13.5 6.53 0.008 0.417 0.302 0.25 8.8 0.38 -0.25 -1.59 7829.86 20.91 67.0 Na-Cl

S6a 12-Jun-02 Site 2 7.065 -20.5 13.05 3085 2.1 566 5.92 63.8 60.6 0.19 0 619.81 113.55 888.41 NA NA 143.03 NA 0.013 6.7 1.19 <0.004 0.387 0.055 0.66 6.6 NA -0.36 -2.07 1768.36 12.1 63.44 Na-Cl-HCO3

S6a 3-Feb-03 Site 2 8.17 -57.1 21.6 1286.5 2.28 250.12 2.7 17.15 16.02 NA NA 199.94 15.82 451.49 NA NA 14.08 NA NA 0.3795 ##### 0.44183 0.3867 NA NA NA -0.98 -0.69 578.2 10.34 63.83 Na-HCO3-Cl

S6b 1-Nov-01 Site 2 7.243 76 19.95 2370 2 384 3.75 49.9 47.2 0.02 0.19 443.86 85.39 728.54 NA NA 116.63 NA 0.01 10.1 0.947 0.004 0.384 0.254 0.37 18.92 0.83 1.31 -6.5 1305.6 9.29 63.54 Na-Cl-HCO3

S6b 3-Feb-03 Site 2 7.397 -13.1 21.4 2850 3.97 511.93 1.69 78.84 71.22 NA NA 679.79 40.65 719.94 NA 2.827 91.54 NA NA 1.8604 0.006 0.32336 0.6784 NA NA NA -0.22 0.89 1765.17 9.93 64.60 Na-Mg-Cl-HCO3

S6b 6-Jun-02 Site 2 6.956 -11.55 17.35 2480 2.73 405 0.77 64.6 64.3 0 0.26 499.85 82.99 711.46 NA NA 147.43 NA 0.032 10.7 1.45 <0.004 0.349 0.157 0.28 12.76 0.21 -0.2 -2.73 1498.43 8.53 62.35 Na-Cl-HCO3

S7a 12-Jun-02 Site 2 6.89 22.6 13.1 1964.5 5.59 314 6.48 46.5 59.7 0.07 0.19 399.88 74.3 527.19 NA NA 189.24 NA 0.035 4.6 0.868 <0.004 0.175 <0.002 2.32 4.444 NA 0.4 -1.77 1267.07 7.4 56.22 Na-Cl-HCO3

S7b 1-Nov-01 Site 2 7.339 -297.4 18.4 2440 0.08 337 7.76 71.4 57.2 0.17 0.16 503.84 22.71 709.02 NA NA 107.82 NA 0.4 9.2 1.17 0.046 0.245 4.01 2.45 5.72 0.88 -5.14 -4.91 1379.92 7.01 67.29 Na-Mg-Cl-HCO3

S7b 3-Feb-03 Site 2 8.296 -64.6 22.2 2205 3.23 359.71 5.54 62.98 40.37 NA NA 439.86 30.46 529.58 NA 2.139 14.08 24 NA 1.0766 0.029 0.23891 0.0255 NA NA NA -1.1 1.09 1156.91 8.24 72.00 Na-Mg-Cl-HCO3

S7b 6-Jun-02 Site 2 7.237 -40.2 20.95 2370 0.88 384 5.98 67.4 53.9 0.12 0.34 499.85 50.03 633.36 NA NA 94.62 NA 0.001 6.7 2.38 0.028 0.238 2.84 0.23 6.6 0.34 -0.69 -0.64 1392.47 8.23 67.33 Na-Mg-Cl-HCO3

S8 1-Nov-01 Site 2 7.393 54.5 17.7 3650 3.76 552 3.12 104 45.1 0.03 0.02 783.76 99.77 909.15 NA NA 110.02 NA 0.004 8.7 1.28 0.007 0.371 1.13 0.35 12.76 0.65 0.94 -5.81 1988.8 10.32 79.17 Na-Mg-Cl-HCO3

S8 3-Feb-03 Site 2 7.664 -26.8 24.3 4255 3.45 748.58 2.18 127.28 29.89 NA NA 879.73 31.4 1195.84 NA 4.59 70.41 NA NA NA 1.7605 0.006 0.51607 0.1412 NA NA NA -0.45 -0.55 2240.26 13.31 87.53 Na-Mg-Cl-HCO3

S8 9-Jun-02 Site 2 7.275 -104 18.15 2940 4.52 483 1.9 96.4 39.2 0.02 0 719.78 76.1 762.71 NA NA 138.63 NA 0.001 8.9 1.28 <0.004 0.444 0.007 0.05 29.04 0.63 -1.8 -5.92 1849.15 9.44 80.21 Na-Mg-Cl-HCO3

SUR1 1-Nov-01 Surface NA NA NA NA NA 982 19.5 904 137 NA 0.01 3992.76 121.34 NA NA NA NA NA NA NA 4.57 0.005 0.299 0.03 NA NA NA NA 3.92 6161.51 6.70 91.58 Mg-Na-Cl

SUR2 1-Nov-01 Surface NA NA NA NA NA 699 9.18 443 69.6 NA 0.02 2003.38 54.83 NA NA NA NA NA NA NA 3.36 0.007 0.347 <0.002 NA NA NA NA 10.13 3282.72 6.80 91.29 Mg-Na-Cl

SUR3 6-Feb-03 Surface 8.076 -72.8 24.8 6055 3.02 771.55 8.95 294.65 116.87 NA NA 1959.39 9.71 837.08 NA NA 45.77 24 NA NA 2.764 0.002 0.13385 0.344 NA NA NA -1.23 -4.51 4075.07 8.65 80.60 Na-Mg-Cl-HCO3

SUR4 6-Feb-03 Surface 8.389 -54.2 28.9 3665 2.23 375.59 8.6 233.22 79.84 NA NA 999.69 3.61 878.57 NA NA 35.21 57.6 NA NA 1.5071 0.002 0.15359 0.0496 NA NA NA -0.9 -5.71 2676.20 4.79 82.80 Mg-Na-Cl-HCO3

U1 1-Nov-01 mid SG 6.93 -47.5 23.55 8880 8.03 600 10.2 681 206 0.16 < .02 2783.14 185.45 1082.44 NA NA 275.06 NA 0.006 8.3 5.39 ##### 0.184 0.183 0.81 7.04 0.3 -0.81 -3.82 5853.56 4.53 84.49 Mg-Na-Cl

U1 9-Jun-02 mid SG 6.716 -32.25 13.35 9620 3.51 735 9.55 737 256 0.02 0 3099.04 173.47 1109.29 NA NA 448.9 NA 0.002 6.9 6.55 0.003 0.174 0.018 1.55 4.356 0.18 -0.57 -1.59 6591.37 5.27 82.59 Mg-Na-Cl All readings in mg L-1 unless otherwise stated.

OF = Oakdale Formation, GF = Gleneski Formation, Int = intermediate groundwater system. SG = Snake Gully, SC = Spicers Creek, rain = rainfall, surface = surface water.

4 Appendix B: Soil and groundwater data

B.6 HYDROCHEMICAL DATA II

Sample ID Al Ag As B Ba Be Bi Cd Ce Co Cr Cs Cu Dy Er Eu Ga Gd Ge Ho La Li Lu Mn Mo Nb Nd Ni Pb Pr Rb Sb Sc Se Sm Sn Sr Ta Tb Th U V W Y Yb Zn Zr Deep 96121/3 0.05 <0.02 12.80 260.00 153.00 <0.20 <0.20 <0.20 <0.01 <0.20 8.70 0.35 <0.20 <0.02 <0.02 <0.01 6.38 <0.02 <0.07 <0.01 <0.01 51.00 <0.02 395.00 <0.30 <0.13 <0.02 11.70 4.60 <0.01 34.50 <0.07 <0.20 NA <0.04 <3.7 20100.00 <0.03 <0.02 <0.10 11.80 21.40 <0.13 <0.02 <0.01 10.44 2.61 96127/2 0.06 <0.02 19.40 291.00 87.00 <0.20 <0.20 <0.20 <0.01 5.31 8.00 <0.01 <0.20 <0.02 <0.02 <0.01 3.87 <0.02 <0.07 <0.01 <0.01 35.60 <0.02 240.00 <0.30 <0.13 <0.02 13.90<0.10<0.01 8.53 <0.07 2.62 NA <0.04 <3.7 3220.00 <0.03 <0.02 <0.10 2.90 10.60 <0.13 <0.02 <0.01 <0.86 <0.03 96133/2 0.04 1.50 5.11 229.00 532.00 <0.20 <0.20 <0.20 <0.01 5.30 5.30 <0.01 <0.20 <0.02 <0.02 <0.01 23.20 <0.02 <0.07 <0.01 <0.01 16.90 <0.02 1050.00 <0.30 <0.13 <0.02 15.40 1.70 <0.01 7.73 <0.07 <0.20 NA <0.04 <3.7 7700.00 <0.03 <0.02 <0.10 5.39 11.80 <0.13 <0.02 <0.01 33.93 <0.03 BH1 0.00 0.29 2.77 62.11 690.55 <0.02 <0.006 0.22 0.08 0.39 7.58 1.07 2.45 0.01 0.01 0.20 18.37 0.02 0.02 0.00 0.05 4.19 0.00 8.72 0.58 <0.08 0.06 5.86 1.81 0.01 7.56 <0.01 6.07 8.52 0.01 <0.05 1431.25 <0.02 <0.003 0.02 2.44 17.77 <0.08 <0.02 0.01 66.09 0.18 UR3 0.55 0.66 1.08 118.00 184.00 <0.20 <0.20 0.51 0.52 0.76 5.46 0.13 3.59 0.06 0.04 0.05 8.65 0.07 0.08 0.01 0.26 11.50 <0.02 120.00 <0.30 0.15 0.31 6.49 5.07 0.08 15.60 0.26 1.63 NA 0.08 0.07 344.00 0.05 0.01 0.15 0.69 1.54 0.11 0.27 0.03 123.54 1.11 96122/4 0.06 <0.02 <0.3 271.00 251.00 <0.20 <0.20 2.20 <0.01 <0.20 8.50 <0.01 <0.20 <0.02 <0.02 <0.01 11.40 <0.02<0.07 <0.01 <0.01 15.90 <0.02 821.00 <0.30 <0.13 <0.02 6.00 4.20 <0.01 7.39 <0.07 <0.20 NA <0.04 <3.7 2130.00 <0.03 <0.02 <0.10 4.26 4.13 <0.13 <0.02 <0.01 9.57 0.55 96122/3 0.07 0.82 12.50 216.00 121.00 <0.22 4.19 <0.20 <0.01 3.09 10.10 0.18 <0.20 <0.02 <0.02 <0.01 5.24 <0.02 <0.07 <0.01 <0.01 62.30 <0.02 350.00 <0.30 <0.13 <0.02 10.50<0.10<0.01 32.60 8.58 <0.20 NA <0.04 <3.7 2380.00 <0.03 <0.02 <0.10 1.74 7.54 <0.13 <0.02 <0.01 11.31 <0.03 96128/3 0.05 2.71 5.79 240.00 361.00 <0.20 <0.20 <0.20 <0.01 <0.20 7.60 <0.01 <0.20 <0.02 <0.02 <0.01 16.00 <0.02<0.07 <0.01 <0.01 10.10 <0.02 44.40 <0.30 <0.13 <0.02 6.70 <0.10<0.01 1.22 <0.07 3.33 NA <0.04 <3.7 3250.00 <0.03 <0.02 <0.10 14.50 17.70 <0.13 <0.02 <0.01 12.18 0.48 96129/3+ 0.00 0.22 2.51 104.37 136.94 <0.02 0.01 0.22 0.06 0.25 8.14 0.58 1.35 0.01 0.00 0.04 3.50 0.01 0.04 <0.003 0.04 5.40 <0.003 3.13 0.29 <0.08 0.05 6.26 7.06 0.01 1.98 <0.01 6.49 9.14 0.01 <0.05 1674.47 <0.02 <0.003 0.04 4.22 37.22 <0.08 <0.02 0.00 20.03 0.17 Int Soda1* 0.01 0.42 2.78 621.24 1317.59 0.36 0.01 0.42 0.23 0.26 36.06 3.71 1.16 0.06 0.05 0.41 40.66 0.03 0.67 0.02 0.10 366.78 0.01 12.76 0.16 <0.080.10 3.71 29.83 0.03 136.97 <0.01 2.33 1.00 0.02 0.18 596.43 0.02 0.01 0.04 0.07 1.52 <0.08 0.53 0.04 59.05 5.16 287* 0.06 0.58 <0.3 495.00 1800.00 <0.20 <0.20 <0.20 <0.01 <0.20 5.50 1.23 <0.20 <0.02 <0.02 0.35 81.30 0.22 <0.07 <0.01 <0.01 339.00 <0.02 <0.10 <0.30 <0.13 <0.02 2.50 <0.10<0.01 150.00 <0.07 <0.20 NA <0.04 <3.7 1800.00 <0.03 <0.02 <0.10 <0.01 <0.25 <0.13 0.63 0.12 10.44 5.06 UR1 0.04 1.25 4.96 248.00 56.00 <0.20 <0.20 <0.20 <0.01 <0.20 9.20 0.18 <0.20 <0.02 <0.02 <0.01 2.35 <0.02 <0.07 <0.01 <0.01 111.00 <0.02 54.90 <0.30 <0.13 <0.02 6.70 <0.10<0.01 16.20 <0.07 3.67 NA <0.04 <3.7 5150.00 <0.03 <0.02 <0.10 5.75 12.10 <0.13 <0.02 <0.01 33.93 <0.03 UR2 0.07 2.04 <0.3 161.00 103.00 <0.20 <0.20 <0.20 <0.01 <0.20 4.90 0.16 <0.20 <0.02 <0.02 <0.01 4.82 <0.02 <0.07 <0.01 <0.01 6.97 <0.02 37.10 <0.30 <0.13 <0.02 2.70 <0.10<0.01 4.75 <0.07 <0.20 NA <0.04 <3.7 1300.00 <0.03 <0.02 <0.10 <0.01 3.77 <0.13 <0.02 <0.01 <0.86 <0.03 268 0.04 1.19 <0.3 274.00 60.40 <0.20 <0.20 <0.20 <0.01 <0.20 6.00 <0.01 <0.20 <0.02 <0.02 <0.01 2.84 <0.02 <0.07 <0.01 <0.01 21.20 <0.02 <0.10 <0.30 <0.13 <0.02 8.30 3.30 <0.01 3.44 <0.07 2.73 NA <0.04 <3.7 3520.00 <0.03 <0.02 <0.10 5.05 5.62 <0.13 0.21 <0.01 1505.10 <0.03 44924 0.05 4.67 <0.3 245.00 33.90 <0.20 <0.20 <0.20 <0.01 <0.20 6.60 0.23 <0.20 <0.02 <0.02 <0.01 1.65 <0.02 <0.07 <0.01 <0.01 47.80 <0.02 143.00 <0.30 <0.13 <0.02 4.60 1.60 <0.01 27.40 <0.07 <0.20 NA <0.04 <3.7 1880.00 <0.03 <0.02 <0.10 <0.01 2.92 <0.13 <0.02 <0.01 38.28 <0.03 96121/2 0.04 <0.02 12.30 375.00 341.00 <0.20 <0.20 <0.20 <0.01 4.02 11.00 0.31 <0.20 <0.02 <0.02 <0.01 16.00 <0.02 <0.07 <0.01 <0.01 89.50 <0.02 658.00 <0.30 <0.13 <0.02 11.50<0.10<0.01 35.60 <0.07 <0.20 NA <0.04 <3.7 14200.00 <0.03 <0.02 <0.10 1.87 20.50 <0.13 <0.02 <0.01 <0.86 0.82 96130/2 0.06 <0.02 10.20 387.00 56.10 <0.20 <0.20 <0.20 <0.01 5.55 9.40 0.10 <0.20 <0.02 <0.02 <0.01 2.74 <0.02 <0.07 <0.01 <0.01 23.90 <0.02 1590.00 <0.30 <0.13 <0.02 8.70 <0.10<0.01 2.89 <0.07 6.59 NA <0.04 <3.7 2810.00 <0.03 <0.02 <0.10 2.02 8.69 <0.13 <0.02 <0.01 8.70 <0.03 96131/2 0.05 1.21 20.60 293.00 296.00 <0.20 <0.20 <0.20 0.13 11.10 10.50 0.30 <0.20 <0.02 <0.02 <0.01 13.60 <0.02 <0.07 <0.01 <0.01 51.80 <0.02 757.00 <0.30 <0.13 <0.02 24.07<0.10<0.01 30.80 <0.07 2.92 NA <0.04 <3.7 4220.00 <0.03 <0.02 <0.10 5.26 12.10 <0.13 <0.02 <0.01 21.75 <0.03 96132/1 0.01 1.44 26.50 172.00 264.00 <0.20 <0.20 <0.20 0.32 9.80 3.50 0.35 <0.20 <0.02 <0.02 <0.01 10.60 <0.02 <0.07 <0.01 0.19 56.70 <0.02 2070.00 16.10 <0.13 <0.02 25.87 4.50 <0.01 60.20 <0.07 <0.20 NA <0.04 <3.7 11500.00 <0.03 <0.02 <0.10 2.06 27.30 <0.13 <0.02 <0.01 22.62 <0.03 Shallow 96035/1 0.00 0.21 3.26 79.43 403.06 <0.02 <0.006 0.20 0.21 0.78 6.29 0.01 1.00 0.01 0.01 0.12 10.02 0.01 <0.02 0.00 0.10 12.34 <0.003 196.79 0.33 <0.08 0.09 10.9910.74 0.02 0.78 <0.01 7.02 10.82 0.02 <0.05 2538.00 <0.02 0.00 0.02 13.29 15.85 <0.08 <0.02 0.01 43.05 0.15 96035/2 0.12 9.00 3.65 89.37 1160.46 <0.02 <0.006 0.22 0.45 2.94 5.48 0.01 2.61 0.02 0.01 0.36 31.07 0.04 <0.02 0.00 0.17 13.06 <0.003 207.90 1.51 <0.08 0.18 10.49 6.41 0.05 0.51 <0.01 7.03 10.76 0.04 <0.05 2571.53 <0.02 0.01 0.04 13.51 17.64 <0.08 <0.02 0.01 47.96 0.20 96121/1 0.00 3.00 25.88 151.15 194.94 <0.02 <0.006 0.19 0.33 19.11 9.63 0.07 3.32 0.03 0.02 0.06 4.12 0.04 <0.02 0.02 0.21 91.86 0.00 2358.83 2.66 <0.08 0.19 22.82 2.30 0.04 16.87 <0.01 3.29 73.93 0.03 <0.05 12469.48 <0.02 0.01 0.03 4.50 26.20 <0.08 0.21 0.02 52.67 0.65 96122/1 0.03 0.25 9.06 682.91 332.96 <0.02 0.03 0.28 0.33 1.35 7.05 0.01 2.24 0.03 0.02 0.11 8.90 0.04 <0.02 0.01 0.15 11.49 0.00 80.57 1.09 0.14 0.17 5.56 4.51 0.04 11.97 <0.01 3.66 40.38 0.04 <0.05 3312.73 0.07 0.01 0.06 10.64 19.84 3.72 0.11 0.01 52.37 0.71 96122/2 0.05 4.72 16.07 460.19 357.74 <0.02 <0.006 0.34 0.52 5.85 10.61 0.02 4.06 0.05 0.02 0.12 9.26 0.06 <0.02 0.01 0.21 20.30 0.01 472.58 2.05 <0.08 0.25 7.98 3.05 0.07 5.73 0.01 3.20 70.69 0.06 <0.05 2367.74 0.03 0.01 0.05 29.60 32.06 1.46 0.23 0.02 40.37 1.96 96127/1 0.03 0.20 45.71 97.81 64.19 <0.02 0.02 0.31 0.11 0.69 10.88 0.02 1.26 0.01 0.00 0.02 1.75 0.01 0.03 <0.003 0.04 7.06 <0.003 298.17 20.33 0.11 0.05 5.47 6.78 0.01 1.31 0.24 5.29 11.35 0.01 <0.05 2091.53 0.06 <0.003 0.18 9.20 27.80 0.66 <0.02 0.00 19.35 0.81 96128/1 0.00 0.38 12.86 484.69 213.16 <0.02 <0.006 0.19 0.15 5.34 10.51 0.01 0.82 0.02 0.01 0.07 5.62 0.02 <0.02 0.00 0.07 3.03 0.00 399.14 2.24 <0.08 0.08 9.47 4.71 0.02 3.05 0.71 4.34 35.96 0.02 <0.05 3137.54 <0.02 0.00 0.02 55.85 20.79 <0.08 <0.02 0.01 22.37 0.75 96128/2 0.00 0.45 6.50 160.17 202.77 <0.02 <0.006 0.24 0.21 0.37 8.58 0.03 1.14 0.02 0.02 0.07 5.46 0.03 <0.02 0.01 0.12 10.00 0.00 17.80 0.40 <0.080.12 4.39 4.66 0.03 2.65 <0.01 6.33 29.30 0.03 <0.05 2947.98 <0.02 0.01 0.01 13.79 15.85 0.11 0.09 0.01 23.06 0.61 96129/1 0.13 0.21 20.24 325.61 72.78 <0.02 <0.006 0.21 0.68 1.14 4.78 0.08 4.60 0.05 0.03 0.03 1.69 0.06 <0.02 0.02 0.21 6.57 0.00 221.27 1.37 <0.08 0.24 10.16 0.91 0.06 6.41 <0.01 4.71 77.87 0.05 <0.05 7697.24 <0.02 0.01 0.04 22.51 37.16 <0.08 0.29 0.02 36.10 0.31 96129/2 0.03 0.30 5.38 158.44 126.91 <0.02 <0.006 0.31 0.46 3.03 9.26 0.16 2.07 0.03 0.02 0.04 3.37 0.04 <0.02 0.01 0.18 9.90 0.00 178.58 2.46 <0.08 0.19 8.03 6.93 0.05 1.21 <0.01 7.49 18.63 0.04 <0.05 2429.74 <0.02 0.01 0.04 10.00 44.87 0.09 0.05 0.01 23.58 0.38 96129/3 0.00 0.22 2.51 104.37 136.94 <0.02 0.01 0.22 0.06 0.25 8.14 0.58 1.35 0.01 0.00 0.04 3.50 0.01 0.04 <0.003 0.04 5.40 <0.003 3.13 0.29 <0.08 0.05 6.26 7.06 0.01 1.98 <0.01 6.49 9.14 0.01 <0.05 1674.47 <0.02 <0.003 0.04 4.22 37.22 <0.08 <0.02 0.00 20.03 0.17 96130/1 0.00 0.22 15.92 142.45 29.43 <0.02 0.01 0.24 0.61 5.17 8.59 0.10 2.46 0.03 0.01 0.02 0.73 0.05 0.24 0.01 0.27 62.16 <0.003 1254.11 1.19 <0.08 0.28 13.89 1.94 0.07 14.59 0.11 6.62 13.12 0.05 <0.05 10496.14 <0.02 0.01 0.17 0.58 13.00 0.18 <0.02 0.01 24.10 0.24 96132/2 0.00 0.69 31.06 86.71 147.03 <0.02 <0.006 0.40 0.23 2.70 7.76 0.12 6.41 0.02 0.02 0.05 3.26 0.03 <0.02 0.04 0.12 32.51 0.00 36.66 6.01 <0.080.10 28.48 6.61 0.03 2.88 0.10 3.01 37.68 0.02 <0.05 10298.84 <0.02 0.01 0.05 62.25 42.09 0.62 0.12 0.01 79.38 1.10 96133/1 0.00 0.09 11.73 170.01 872.03 <0.02 <0.006 0.16 0.56 3.06 6.78 0.01 1.43 0.04 0.02 0.27 21.83 0.05 <0.02 0.01 0.24 1.31 0.01 1601.34 0.57 <0.08 0.26 17.14 6.46 0.06 1.91 <0.01 4.97 27.07 0.05 <0.05 11708.89 <0.02 0.01 0.02 10.05 10.96 <0.08 0.26 0.02 44.56 0.39 98036 0.00 0.63 11.49 202.19 719.47 <0.02 <0.006 0.27 0.12 16.67 8.95 0.01 2.43 0.01 0.01 0.21 18.43 0.01 <0.02 0.00 0.05 11.76 0.00 1852.63 1.77 <0.08 0.06 37.78 6.57 0.01 1.66 <0.01 7.36 42.23 0.01 <0.05 5562.37 <0.02 <0.003 0.02 6.99 15.57 <0.08 <0.02 0.01 59.17 0.43 98037 0.02 0.33 14.07 392.34 344.69 <0.02 0.01 0.42 0.35 4.44 6.88 0.01 3.02 0.04 0.02 0.11 8.59 0.04 <0.02 0.01 0.15 4.19 0.00 837.30 6.08 <0.08 0.18 14.31 7.60 0.04 1.71 0.03 5.08 54.65 0.03 0.05 11090.28 <0.02 0.01 0.05 25.53 19.27 <0.08 0.23 0.02 113.87 0.35 P56 0.01 0.92 10.46 270.89 73.39 <0.02 0.01 0.44 0.33 0.61 10.93 0.05 5.74 0.04 0.02 0.03 1.84 0.04 <0.02 0.02 0.13 42.81 0.00 98.01 1.86 <0.080.17 12.1316.96 0.04 2.95 <0.01 6.36 47.69 0.04 8.28 3897.93 0.03 0.01 0.04 5.01 14.38 0.77 0.21 0.02 202.04 0.76 P57 0.01 0.23 9.24 127.43 295.15 <0.02 <0.006 0.25 0.29 1.23 11.18 0.04 3.19 0.01 0.01 0.09 7.58 0.02 <0.02 0.00 0.10 8.10 <0.003 139.82 0.31 <0.08 0.13 14.19 2.05 0.03 3.66 <0.01 6.16 34.07 0.02 <0.05 6037.85 <0.02 0.00 0.05 8.86 12.79 0.21 <0.02 0.01 76.19 0.30 P58 0.05 6.19 4.28 94.87 390.08 <0.02 0.01 0.32 0.46 14.46 14.61 0.01 0.94 0.03 0.01 0.12 10.92 0.04<0.02 0.01 0.22 7.01 0.00 1500.72 0.61 <0.08 0.21 6.51 6.78 0.06 0.72 <0.01 7.64 16.80 0.04 <0.05 2112.56 <0.02 0.01 0.04 1.80 7.26 0.15 0.03 0.01 11.76 0.31 P59 0.37 0.15 4.80 99.55 242.52 <0.02 0.01 0.20 2.40 1.08 10.53 0.09 1.31 0.13 0.07 0.10 6.56 0.17 0.03 0.03 0.97 1.48 0.01 250.77 1.32 <0.08 0.88 3.77 6.88 0.24 3.19 <0.01 5.17 13.53 0.17 0.17 729.34 <0.02 0.03 0.18 3.63 9.04 2.15 0.58 0.04 23.26 0.64 P60 0.09 0.38 7.46 234.30 132.82 <0.02 <0.006 0.34 0.85 1.28 21.89 0.06 1.64 0.06 0.03 0.05 3.81 0.07 0.02 0.02 0.34 8.04 0.00 113.65 1.34 <0.08 0.33 3.76 3.54 0.09 1.33 <0.01 5.17 27.57 0.07 <0.05 718.82 <0.02 0.01 0.07 17.35 31.11 1.03 0.31 0.03 60.15 0.59 P61 0.02 0.33 6.28 279.43 1067.69 <0.02 <0.006 0.34 1.02 7.29 12.01 0.02 1.50 0.08 0.05 0.34 30.53 0.10<0.02 0.02 0.39 1.54 0.01 1287.08 9.35 <0.08 0.44 11.67 3.98 0.11 2.01 0.03 3.91 23.19 0.09 <0.05 4551.47 <0.02 0.02 0.03 6.19 11.92 24.31 0.61 0.04 34.63 0.46 P62 0.00 10.98 9.23 233.52 448.15 <0.02 <0.006 0.29 0.08 5.89 9.24 0.05 1.96 0.01 0.01 0.14 11.85 0.01<0.02 <0.003 0.04 5.96 0.00 1141.55 1.03 <0.08 0.04 8.56 2.42 0.01 1.25 <0.01 4.35 34.94 0.01 <0.05 3773.99 <0.02 <0.003 0.02 4.37 12.98 0.11 <0.02 0.01 70.89 0.31 P63 0.01 2.03 5.21 392.56 103.35 <0.02 <0.006 0.25 0.17 0.77 13.85 0.01 1.97 0.02 0.02 0.03 2.82 0.02 0.04 0.01 0.07 5.45 <0.003 128.72 0.94 <0.08 0.09 4.92 5.81 0.02 0.71 0.02 5.89 16.26 0.02 <0.05 1275.57 <0.02 0.00 0.01 11.00 40.17 0.47 0.03 0.01 30.48 0.25 P65 0.00 0.25 7.55 481.57 402.64 <0.02 <0.006 0.26 0.34 2.17 17.02 0.01 0.69 0.05 0.04 0.13 11.26 0.05<0.02 0.01 0.13 1.81 0.01 1880.76 2.70 <0.08 0.17 5.85 6.61 0.04 1.71 <0.01 4.39 24.09 0.04 <0.05 3817.57 <0.02 0.01 0.03 26.58 11.60 2.18 0.42 0.04 9.98 1.02 S1a 0.09 0.81 6.55 804.83 308.92 <0.02 <0.006 0.25 0.43 0.66 8.10 0.01 1.28 0.03 0.01 0.10 8.08 0.04 <0.02 0.01 0.15 10.64 0.00 114.47 0.85 <0.08 0.19 6.69 10.57 0.05 0.22 <0.01 6.30 27.86 0.04 <0.05 8151.20 0.04 0.01 0.05 21.00 13.60 <0.08 0.03 0.01 43.31 0.70 S1b 0.03 11.23 8.14 795.68 689.84 <0.02 <0.006 0.24 0.20 1.64 20.62 0.01 0.68 0.03 0.03 0.21 19.74 0.03 0.07 0.01 0.07 11.84 0.01 694.60 14.52 <0.08 0.10 2.66 6.86 0.02 0.87 0.07 4.90 24.72 0.03 0.09 2293.40 0.05 0.01 0.03 21.45 10.72 0.09 0.19 0.02 17.36 1.61 S1c 0.64 0.72 11.84 265.86 383.99 <0.02 0.01 0.21 1.49 2.61 8.87 0.03 2.54 0.11 0.05 0.16 9.39 0.17 <0.02 0.02 0.58 26.44 0.01 301.54 2.44 <0.08 0.81 5.90 11.63 0.19 0.90 0.10 7.86 48.89 0.17 0.96 5824.75 <0.02 0.02 0.10 18.51 16.85 0.12 0.45 0.03 28.25 0.75 5 Appendix B: Soil and groundwater data

Sample ID Al Ag As B Ba Be Bi Cd Ce Co Cr Cs Cu Dy Er Eu Ga Gd Ge Ho La Li Lu Mn Mo Nb Nd Ni Pb Pr Rb Sb Sc Se Sm Sn Sr Ta Tb Th U V W Y Yb Zn Zr S2a 0.39 1.02 4.75 425.71 676.93 <0.02 <0.006 0.18 0.84 4.04 10.54 0.03 1.95 0.05 0.02 0.21 18.22 0.08<0.02 0.01 0.29 9.10 0.00 499.61 0.96 <0.08 0.37 14.5026.77 0.09 0.76 <0.01 7.18 20.84 0.09 <0.05 6542.85 <0.02 0.01 0.07 12.96 11.94 <0.08 0.12 0.02 22.56 0.55 S2b 0.00 0.28 3.62 230.82 361.59 <0.02 0.01 0.22 0.20 0.39 26.15 0.01 1.56 0.02 0.01 0.10 9.51 0.02 <0.02 0.00 0.09 17.83 <0.003 46.74 1.84 <0.080.10 6.30 13.52 0.03 0.42 <0.01 5.50 16.55 0.03 <0.05 5730.09 0.02 0.00 0.01 14.31 6.02 <0.08 <0.02 0.01 32.39 0.23 S2c 1.99 0.37 3.64 157.72 515.89 0.07 0.01 0.19 3.98 5.20 10.92 0.13 5.75 0.27 0.13 0.28 13.99 0.43 <0.02 0.05 1.60 12.70 0.02 1019.43 0.45 <0.08 1.96 14.9818.24 0.45 2.00 <0.01 5.58 15.11 0.43 2.72 6553.10 <0.02 0.06 0.22 8.56 9.53 <0.08 1.27 0.10 29.64 1.01 S3a 1.82 0.52 2.86 38.72 1215.66 0.03 0.02 0.56 4.20 4.37 4.19 0.05 6.01 0.20 0.10 0.48 32.33 0.31 0.04 0.04 1.29 6.06 0.01 1248.55 1.92 <0.08 1.61 14.89 8.97 0.38 2.07 0.02 7.42 12.75 0.32 21.54 4300.11 0.02 0.05 0.16 3.84 7.13 <0.08 0.68 0.07 41.00 0.38 S3b 0.08 3.36 2.18 74.71 874.89 <0.02 0.02 1.17 0.32 2.00 4.28 0.01 13.68 0.02 0.01 0.26 24.41 0.04 0.04 0.00 0.13 8.86 <0.003 360.03 3.13 <0.08 0.20 17.17 8.99 0.04 1.09 0.18 4.76 9.41 0.04 43.23 3158.16 0.03 0.01 0.04 5.93 3.37 <0.08 <0.02 0.01 76.78 0.90 S4 0.13 0.29 1.18 75.72 111.61 <0.02 0.02 0.36 0.76 0.81 4.24 0.02 1.15 0.05 0.03 0.05 2.94 0.08 0.03 0.01 0.30 1.02 0.00 143.09 0.90 <0.08 0.35 4.33 11.81 0.08 0.84 0.03 5.87 4.81 0.08 0.66 1395.71 0.03 0.01 0.08 5.25 2.88 0.09 0.13 0.02 66.57 0.23 S5 0.04 1.46 4.80 659.47 116.13 <0.02 0.04 0.28 0.28 0.34 5.36 0.05 3.18 0.03 0.02 0.04 2.91 0.03 0.05 0.01 0.11 10.93 <0.003 41.83 4.63 <0.08 0.14 6.08 14.76 0.03 0.84 <0.01 6.04 19.65 0.03 <0.05 2668.84 0.09 0.01 0.04 25.43 7.42 0.12 0.07 0.01 140.90 0.66 S6a 2.33 1.64 1.30 441.83 57.56 0.11 0.01 0.23 4.52 2.43 3.40 0.08 4.17 0.42 0.22 0.14 1.72 0.56 0.05 0.08 1.44 0.99 0.03 386.72 1.20 <0.08 2.22 3.81 7.93 0.51 4.17 <0.01 2.92 3.69 0.49 8.66 379.49 0.03 0.09 0.41 22.92 8.95 <0.08 2.05 0.17 56.65 0.90 S6b 3.66 0.36 2.74 323.36 134.26 0.13 0.03 0.51 4.39 3.33 6.97 0.13 2.88 0.36 0.19 0.15 3.69 0.48 0.05 0.08 1.28 5.70 0.03 678.42 72.40 <0.08 1.85 8.54 10.60 0.44 3.19 <0.01 7.33 14.48 0.40 23.22 1860.36 0.03 0.07 0.70 13.03 7.62 0.74 1.70 0.14 52.44 1.67 S7b 0.00 0.16 2.38 238.91 220.92 <0.02 <0.006 0.15 0.12 0.32 4.08 0.15 1.74 0.01 0.01 0.06 5.73 0.02 0.10 0.00 0.04 28.77 <0.003 25.47 5.62 <0.080.06 2.33 4.92 0.01 4.92 <0.01 2.91 7.52 0.01 1.76 1076.55 0.04 0.00 0.04 11.45 1.96 0.17 <0.02 0.01 46.73 0.16 S8 0.58 0.57 6.27 516.07 173.99 0.04 0.01 0.74 1.13 0.97 14.75 0.05 3.20 0.09 0.05 0.08 4.96 0.13 0.12 0.02 0.44 5.84 0.01 141.20 120.43 <0.08 0.57 4.90 15.66 0.14 1.26 0.15 4.26 15.46 0.12 0.17 1760.47 0.05 0.02 0.24 36.98 10.42 <0.08 0.42 0.03 57.70 1.15 S11 0.35 0.25 6.57 737.43 908.85 <0.02 0.03 0.37 0.81 11.84 9.21 0.04 3.61 0.07 0.04 0.30 25.54 0.09<0.02 0.02 0.33 2.96 0.01 1524.09 2.64 0.12 0.43 10.2512.86 0.10 10.02 <0.01 4.47 25.33 0.09 0.45 7948.58 0.06 0.01 0.10 11.66 14.46 0.17 0.40 0.03 66.99 0.91 S12 0.30 0.25 7.85 336.17 454.54 <0.02 0.01 0.27 0.42 1.63 9.25 0.01 2.04 0.03 0.02 0.14 12.67 0.04<0.02 0.01 0.17 4.08 0.00 111.90 1.46 <0.08 0.19 7.14 4.70 0.05 1.64 <0.01 5.37 22.19 0.05 <0.05 2370.20 <0.02 0.01 0.05 6.72 38.22 <0.08 0.06 0.01 27.55 0.34 S13a 0.22 4.20 4.35 176.44 80.68 <0.02 <0.006 0.20 0.26 0.70 13.09 0.01 2.37 0.02 0.02 0.03 2.29 0.03 <0.02 0.01 0.11 2.19 <0.003 44.74 0.61 <0.080.13 4.51 15.69 0.03 0.96 <0.01 4.59 16.13 0.03 <0.05 1743.39 <0.02 0.01 0.04 5.89 11.92 <0.08 0.05 0.01 40.68 0.40 S13b 0.10 4.96 6.67 241.86 131.38 <0.02 <0.006 0.27 0.18 5.51 8.66 0.02 1.48 0.02 0.01 0.04 3.65 0.02 0.02 0.01 0.08 3.36 0.00 816.91 2.05 <0.08 0.08 4.21 19.27 0.02 0.80 0.05 5.40 22.86 0.02 <0.05 1334.85 <0.02 0.00 0.02 7.03 18.03 <0.08 <0.02 0.01 35.37 0.84 S13c 0.22 0.35 6.07 118.28 241.72 <0.02 0.02 0.44 0.22 6.58 11.57 0.02 1.63 0.03 0.01 0.08 6.59 0.03 <0.02 0.00 0.09 6.56 <0.0031211.01 0.93 <0.08 0.11 6.82 20.04 0.02 0.90 <0.01 7.47 22.82 0.02 <0.05 2952.80 0.02 0.00 0.04 9.04 24.42 <0.08 <0.02 0.01 51.37 0.31 S13d 0.13 0.26 5.73 110.25 416.64 <0.02 0.01 0.30 0.30 2.64 7.80 0.01 2.06 0.02 0.01 0.13 11.16 0.03<0.02 0.01 0.11 6.43 0.00 337.71 1.45 <0.08 0.11 7.05 16.41 0.03 0.65 <0.01 4.44 21.51 0.03 <0.05 3231.82 0.02 0.00 0.04 7.44 14.01 <0.08 <0.02 0.01 63.69 0.27 S14b 0.00 6.55 5.65 168.08 483.38 <0.02 0.01 0.33 0.12 0.58 10.43 0.01 2.32 0.01 0.00 0.14 13.00 0.01<0.02 <0.003 0.05 4.76 <0.003 41.42 0.32 <0.080.05 10.6812.05 0.01 2.76 <0.01 6.69 20.58 0.01 <0.05 3554.76 <0.02 <0.003 0.01 6.29 15.52 <0.08 <0.02 0.00 44.89 0.88 S14c 0.08 0.32 3.65 146.28 506.58 <0.02 0.02 0.40 0.47 3.39 9.63 0.02 2.10 0.03 0.02 0.16 13.90 0.05<0.02 0.01 0.18 8.00 <0.003 196.49 1.33 <0.08 0.20 25.2215.68 0.05 0.73 <0.01 6.00 14.48 0.04 <0.05 2398.14 0.02 0.01 0.06 6.61 8.99 <0.08 0.02 0.01 45.35 0.22 S15a 0.11 0.40 4.39 286.35 187.67 <0.02 0.01 0.50 0.51 0.85 8.76 0.01 1.68 0.03 0.02 0.06 5.23 0.05 <0.02 0.01 0.21 4.23 0.00 96.49 0.74 <0.08 0.22 5.41 5.69 0.06 0.70 <0.01 5.27 17.02 0.04 <0.05 3727.51 0.02 0.01 0.11 6.42 10.42 <0.08 0.09 0.01 43.39 0.45 S15b 0.00 0.31 4.72 144.33 130.85 <0.02 0.01 0.36 0.27 4.79 8.15 0.01 0.98 0.02 0.01 0.05 3.55 0.03 <0.02 0.01 0.11 6.03 <0.003 480.74 1.18 <0.08 0.12 7.59 12.74 0.03 0.69 <0.01 5.62 14.53 0.02 <0.05 3155.02 <0.02 0.00 0.03 3.90 7.56 <0.08 <0.02 0.01 50.93 0.24 R1 0.03 0.52 1.89 14.30 11.37 <0.02 0.04 0.25 0.17 1.26 0.87 0.02 34.10 0.02 0.01 0.01 0.31 0.02 <0.02 0.01 0.07 0.19 <0.003 43.39 0.69 0.09 0.09 1.60 1.34 0.02 10.34 2.45 <0.09 0.49 0.02 <0.05 38.20 0.08 0.00 0.05 0.02 0.93 0.27 <0.02 0.01 92.40 0.30 R2 0.00 0.70 <0.05 1.31 2.89 <0.02 0.01 0.19 0.05 0.13 <0.13 0.00 6.54 0.01 <0.003 <0.003 0.07 0.01 <0.02 <0.003 0.02 0.05 <0.003 8.92 0.11 <0.08 0.03 0.46 1.00 0.01 0.12 1.23 <0.09 <0.29 0.01 <0.05 2.28 0.04 <0.0030.00 0.00 <0.27 0.13 <0.02 <0.003 157.99 0.04 SUR3 0.00 0.11 8.22 133.85 842.74 <0.02 <0.006 0.10 0.06 0.55 8.54 0.00 1.32 0.01 0.00 0.25 23.51 0.01<0.02 <0.003 0.03 1.87 0.00 344.03 1.54 <0.08 0.03 4.95 2.83 0.01 1.72 <0.01 2.67 24.85 0.01 <0.05 2763.99 <0.02 <0.003 0.01 2.88 8.70 <0.08 <0.02 0.01 20.10 0.67 SUR4 0.00 0.20 6.80 153.59 332.32 <0.02 0.01 0.22 0.23 0.71 12.49 0.02 2.66 0.03 0.02 0.10 9.40 0.03 <0.02 0.01 0.08 2.34 0.00 49.56 1.31 <0.080.10 5.50 11.55 0.03 2.76 0.05 3.89 12.83 0.03 <0.05 1507.10 <0.02 0.01 0.03 2.81 16.76 <0.08 0.08 0.02 33.41 0.62 All readings in µg L-1 (except Al which is reported in mg L-1).