Surface impacts of gold mining activities on the Kromdraai/Koekemoerspruit : a situation analysis

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Surface impacts of gold mining activities

on the Kromdraai/Koekemoerspruit: a

situation analysis

AJ Botha

23658312

Dissertation submitted in fulfilment of the requirements for the

degree Magister Scientiae in

Environmental Sciences

at the

Potchefstroom Campus of the North-West University

Supervisor:

Mr PW van Deventer

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“The most beautiful thing we can experience is the mysterious. It is the source of all true art and science.”

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ABSTRACT

Six point sources of potential contamination from gold mine tailings were identified along the Kromdraai/Koekemoerspruit drainage basin. The degree of contamination of the tailings, soils, surface water, stream sediments and plants at each point source, as well as the individual contribution of these point sources to the contamination of downstream localities was determined by means of quantitative indices. These indices include availability percentage, threshold exceedance ratio, geoaccumulation index, bioaccumulation index and hyperaccumation threshold exceedance ratio. Both the total concentration pool as well as the available (soluble) fraction thereof were evaluated relative to pH and plant uptake, and as applicable to the sample type, by using the USEPA 3050b and DIN 19730 (NH4NO3) extraction methods, respectively. The results for the eight selected potentially toxic trace elements (Cr, Co, Ni, Cu, Pb, Zn, As and U) were further categorised under current and potential future contamination statuses and discussed according to a source-pathway-receptor model relative to individual localities. Composite sampling was employed to provide a representative average of each locality for an overall contamination profile of the study area. Plant species were classified according to accumulation degree and hyperaccumulation status in order to derive an indication of accumulation efficiency relative to the geochemical status of soils or tailings. A document was compiled in order to be used as a guideline for rehabilitation purposes specific to a geochemically-contaminated drainage system.

Keywords: available (soluble) fraction, composite sampling, tailings contamination, plant

bioaccumulation, potentially toxic trace elements, quantitative indices, rehabilitation, source-pathway-receptor, total concentration pool

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PREFACE AND ACKNOWLEDGEMENTS

Mine Waste Solutions [Pty] Ltd, in conjunction with the National Research Foundation / Technology and Human Resources for Industry Program [NRF/THRIP], authorised and funded the research for this study in order to determine potential contamination and impacts caused by gold mining activities along the Kromdraai/Koekemoerspruit drainage system (NRF/THRIP proposal submitted in 2011 by the North-West University [NWU], Potchefstroom. Ref: TP2011071700002).

Many thanks go to the following persons and/or organisations:

 National Research Foundation / Technology and Human Resources for Industry Programme (NRF/THRIP): Doret Potgieter

 Mine Waste Solutions / AngloGold Ashanti: Melt Marais, John van Wyk, Etienne Grond, Charl Human and Gunter Wiegenhagen

 Tlokwe City Council

 North-West University, Potchefstroom

 Study supervisor: Piet van Deventer (for all-round awesomeness)

 Bryan Botha (you are the best part of my day)

 Koos and Joy Haasbroek (for unwavering love, support and encouragement; for making the first two degrees possible – this one’s on me)

 Landowners: Tlokwe City Council, Tom van Rooyen, Mike van Rooyen, Chris de Wet, Danie Barnard, Donovan Webster, Kobus Steenkamp, Fanie Nel and Hein (farm manager), Hannes Dreyer, Frik Scheepers and Johan Condos

 EcoAnalytica Laboratories: Terina Vermeulen, Yvonne Visagie and Mariiza Neethling

 Geolab: Dries Bloem (data sources and discussion of geochemical concepts)

 Technical advice, review and GIS map compilation: Jaco Koch (and for great coffee breaks)

 Fieldwork and laboratory assistance: in particular, Divan Kok, Douw Bodenstein, Marcélle Ferreira, Jaco Koch and AJ Erasmus (and for super amounts of patience, hard work, integrity and friendship)

 Specialist inputs on South African soil background concentrations: Elize Herselman

 Suzette Smalberger (for advice, friendship and lots of laughs)

 South African Weather Service for weather/climatic datasets of the study area

 DWA Pretoria: Ernst Bertram

 DWA, Bloemfontein: Willem Grobler and George Nel

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School for Geo- and Spatial Sciences

Geology Subgroup: Soil Science Division

Cell: 082 855 4533 Tel: 018 285 2267

E-mail: 10058591@nwu.ac.za

19 March 2013

To Whom It May Concern

DECLARATION: NEW MACHAVIE GOLD MINE RESEARCH

The Soil Science Division of the Geology Subgroup of the North-West University (NWU) is doing research on and downstream of the New Machavie gold mine west of Potchefstroom. The mine is currently the property of Tlokwe Town Council and the projects were approved by the Council. Various parameters are measured for the different projects; however, the results are shown differentially based on the context of the individual project objectives.

This can be illustrated by the following examples:

i) Geophysical radiometric downhole probing and geochemical analyses to determine the uranium concentrations and mobility in the tailings; and

ii) Soil, sediment and vegetation surveys and analyses to investigate the influence of the tailings dams on the nearby Koekemoer and Kromdraai drainage systems.

Should you require additional information please do not hesitate to contact the undersigned.

Piet van Deventer (PrSc Nat)2

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DISCLAIMER

Although all reasonable care was taken in preparing the dissertation, tables, figures, maps and photos, the North-West University (NWU), NRF/THRIP and/or the author are not responsible for any changes with respect to any biophysical variations that might have an influence on the tailings, soil, water, stream sediment and vegetation quality. The integrity of this report and the NWU, NRF/THRIP and/or author nevertheless do not provide any warranty whatsoever that the report is free of any misinterpretations of National or Provincial Acts or Regulations with respect to environmental and/or social issues. The integrity of this communication and the NWU, NRF/THRIP and/or author do not give any warranty whatsoever that the report is free of damaging code, viruses, errors, interference or interpretations of any nature. The NWU, NRF/THRIP and/or author do not make any warranties in this regard whatsoever and cannot be held liable for any loss or damages incurred by the recipient or any person who will use it in any respect. Although all possible care has been taken in the production of the maps, tables, figures and photos, the NWU, NRF/THRIP and/or author cannot take any liability for perceived inaccuracy or misinterpretation of the information shown in these maps, tables, figures and photos.

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LIST OF ACRONYMS AND ABBREVIATIONS

A Available concentration / availability A% Availability percentage

AD Accumulation degree

Ag Silver

Al Aluminium

AMD Acid mine drainage / acid and metalliferous drainage ARD Acid rock drainage

As Arsenic

ASL Above sea level

Au Gold

Ba Barium

BAI Bioaccumulation index

B Boron

Br Bromine

BuDo Buffelsdoorn BuFo Buffelsfontein

Bu10 Buffelsfontein #10 Shaft

Ca Calcium

CC Contamination category/class

Cd Cadmium

CF Contamination factor Cl Chlorine

CoDo Control on dolomite CoLa Control on lavas

CLI Contamination load index

Co Cobalt CO3 Carbonate Cr Chromium Cu Copper CZ Critical Zone DC Drainage canal DrSy Drainage system EC Electrical conductivity ED Evaporation dam

EDTA Ethylenediaminetetraacetic acid Eh Oxidation-reduction potential ESP Eastern spillage

F Flourine

Fe Iron

FeS2 Pyrite FP Footprint

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I Iodine

Igeo Geoaccumulation index HaFo Hartebeestfontein

Hg Mercury

HTER Hyperaccumulation threshold exceedance ratio ICP-MS Inductively coupled plasma-mass spectrometer

K Potassium

KDS Kromdraai/Koekemoerspruit drainage system

Li Lithium

MAT Maximum available threshold MC Mine/mining complex

Mg Magnesium

MIW Mining influenced water

MiWa Mine Waste Solutions [First Uranium / Chem-Wes]

Mn Manganese

Mo Molybdenum

MPRDA Mineral and Petroleum Resources Development Act

N Nitrogen

nc Composite sample NeMa New Machavie

NEMWA National Environmental Management Waste Act NH4EDTA Ammonium ethylenediaminetetraacetic acid NH4NO3 Ammonium nitrate

Ni Nickel

NMD Neutral mine drainage NNR National Nuclear Regulator

Pb Lead

OXT Oxidised tailings

P Phosphorous

PTE Potentially toxic trace element PTotE Periodic table of the elements

Rb Rubidium

RD Rock dump

RWD Return water dam

S Sulphur

SD Saline drainage

Se Selenium

Sed Stream sediment

Si Silica

SO4 Sulphate

SOM Soil organic matter SP Spillage

Sr Strontium

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SSV Soil screening value SubS Subsoil

SurfS Surface soil

SVC Soil visibly contaminated T Total concentration

Te Tellurium

TER Threshold exceedance ratio TIL Total investigative level

Ti Titanium

Tl Thallium

TMT Total maximum threshold TSF Tailings storage facility UNT Unoxidised tailings

USEPA United States Environmental Protection Agency

V Vanadium

VC Visibly contaminated

WT Wetland

Zn Zinc

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TABLE OF CONTENTS

Abstract ... ii

Preface and acknowledgements ... iii

Disclaimer ... v

List of acronyms and abbreviations ... vi

1 Introduction ... 1

1.1 Overview ... 1

1.2 Aims and objectives ... 3

1.3 Provisos ... 4 2 Study area... 6 2.1 Geological setting ... 7 2.1.1 Ventersdorp Supergroup ...9 2.1.2 Transvaal Supergroup ... 10 2.2 Pedology ... 11

2.3 Climate and topography ... 14

2.3.1 Regional climate ... 14

2.3.2 Topography and drainage ... 20

2.4 Vegetation ... 22

2.5 Locality identification ... 24

2.5.1 Locality nomenclature and descriptions ... 24

2.5.2 Locality maps and photos ... 25

2.5.3 Locality and sampling matrix ... 32

3 Literature study ... 37 3.1 Trace elements ... 37 3.1.1 Chromium ... 42 3.1.2 Cobalt ... 44 3.1.3 Nickel ... 47 3.1.4 Copper ... 49 3.1.5 Lead ... 51 3.1.6 Zinc ... 54 3.1.7 Arsenic ... 56 3.1.8 Uranium ... 59

3.2 Trace elements and plants ... 61

3.3 Acid mine drainage and source-pathway-receptor principles ... 69

3.4 Phytoremediation ... 77

3.4.1 Phytoextraction ... 77

3.4.2 Phytostabilisation (-restoration) ... 78

3.4.3 Phyto-/Rhizofiltration ... 79

3.4.4 Phytotransformation (-volatilisation) ... 79

3.4.5 Benefits and drawbacks of phytoremediation ... 79

4 Methodology ... 81

4.1 Project Management ... 81

4.2 Sampling protocol ... 81

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4.2.2 Soil sampling protocol ... 89

4.2.3 Surface water sampling protocol ... 89

4.2.4 Stream sediment sampling protocol ... 90

4.2.5 Plant tissue sampling protocol ... 90

4.3 Laboratory analysis ... 93

4.4 Data processing and analysis ... 94

4.4.1 Baseline and threshold/guideline values ... 94

4.4.2 Current contamination status ... 97

4.4.3 Potential future contamination impact ... 99

4.4.4 Plant accumulation status (efficiency) ... 100

5 Results ... 102

5.1 Point source impacts of gold mine tailings along the Kromdraai/Koekemoerspruit ... 104

5.1.1 New Machavie Mine Complex ... 109

5.1.2 Buffelsdoorn Mine complex ... 111

5.1.3 Mine Waste Solutions mining complex ... 111

5.1.4 Hartebeestfontein Mine complex ... 112

5.1.5 Buffelsfontein #10 Shaft mining complex ... 113

5.1.6 Buffelsfontein Mine complex ... 114

5.2 Impacts of gold mine activities on soils along the Kromdraai/Koekemoerspruit ... 115

5.2.1 Control localities on lavas ... 124

5.2.2 Control localities on dolomite ... 124

5.2.3 New Machavie Mine Complex ... 125

5.2.4 Drainage system localities 1 and 2 ... 126

5.2.7 Drainage system locality 8 ... 128

5.2.8 Drainage system localities 10, 11, 12 and 13 ... 129

5.2.10 Drainage system localities 14, 15 and 16 ... 130

5.2.11 Hartebeestfontein Mine complex ... 131

5.2.12 Drainage system locality 17 ... 132

5.2.13 Control locality 4 on dolomite ... 132

5.3 Impacts of gold mine activities on the surface water and stream sediments along the Kromdraai/Koekemoerspruit ... 135

5.3.1 Control locality on lavas ... 138

5.3.2 Control locality on dolomite ... 138

5.3.4 Drainage system localities 5, 6 and 9 ... 139

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5.4 Impacts of gold mine activities on vegetation along the Kromdraai/Koekemoerspruit ... 142

5.4.1 Cenchrus ciliaris ... 164 5.4.2 Cymbopogon caesius ... 164 5.4.3 Cymbopogon pospischilii ... 165 5.4.4 Cynodon dactylon ... 166 5.4.5 Cyperus rotundus ... 168 5.4.6 Digitaria eriantha ... 169 5.4.7 Eragrostis chloromelas ... 169 5.4.8 Eragrostis curvula ... 169 5.4.9 Eragrostis gummiflua ... 170 5.4.10 Eragrostis lehmanniana ... 170 5.4.11 Eragrostis plana ... 171 5.4.12 Eragrostis superba ... 172 5.4.13 Eustachys paspaloides ... 172 5.4.14 Hyparrhenia hirta ... 173 5.4.15 Juncus rigidus... 174 5.4.16 Panicum coloratum... 175 5.4.17 Paspalum dilatatum ... 175 5.4.18 Paspalum notatum ... 175 5.4.19 Pennisetum clandestinum ... 175 5.4.20 Phragmites australis ... 176 5.4.21 Setaria pumila... 177 5.4.22 Setaria sphacelata ... 177 5.4.23 Themeda triandra ... 178 5.4.24 Triraphis andropogonoides ... 180 5.4.25 Typha capensis ... 180

6 Discussion and conclusions ... 182

6.1 Tailings, soil and sediment summary: current and potential future contamination impacts 183 6.1.1 Chromium contamination impacts ... 187

6.1.2 Cobalt contamination impacts ... 188

6.1.3 Nickel contamination impacts ... 191

6.1.4 Copper contamination impacts ... 193

6.1.5 Lead contamination impacts ... 196

6.1.6 Zinc contamination impacts ... 197

6.1.7 Arsenic contamination impacts ... 199

6.1.8 Uranium contamination impacts ... 209

6.1.9 Final conclusions ... 213

6.2 Plant tissue summary: accumulation status (efficiency) ... 217

6.2.1 Cymbopogon caesius accumulation efficiency ... 220

6.2.2 Cymbopogon pospischilii accumulation efficiency ... 220

6.2.3 Cynodon dactylon accumulation efficiency ... 221

6.2.4 Eragrostis chloromelas accumulation efficiency ... 222

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6.2.6 Eragrostis lehmanniana accumulation efficiency ... 223

6.2.7 Eragrostis plana accumulation efficiency ... 224

6.2.8 Hyparrhenia hirta accumulation efficiency ... 225

6.2.9 Pennisetum clandestinum accumulation efficiency ... 226

6.2.10 Setaria pumila accumulation efficiency ... 226

6.2.11 Setaria sphacelata accumulation efficiency ... 227

6.2.12 Themeda triandra accumulation efficiency ... 228

6.2.13 Triraphis andropogonoides accumulation efficiency ... 228

6.2.14 Juncus rigidus accumulation efficiency ... 229

6.2.15 Phragmites australis accumulation efficiency ... 230

6.2.16 Typha capensis accumulation efficiency ... 231

6.2.17 Final conclusions ... 232

7 Prevention, mitigation and rehabilitation recommendations ... 234

References ... 242

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LIST OF FIGURES

Figure 2-1: Geology of drainage basin C24A, with reference to the Kromdraai/Koekemoerspruit ...8

Figure 2-2: Total monthly rainfall for Klerskdorp and Potchefstroom for the years 2006 to 2012 ... 16

Figure 2-3: Average maximum and minimum monthly temperatures for Klerskdorp for the years 2006 to 2012 ... 17

Figure 2-4: Average maximum and minimum monthly temperatures for Potchefstroom for the years 2006 to 2012 ... 18

Figure 2-5: Topography of the study area with 20 m contour lines ... 21

Figure 2-6: Regional setting of the study area ... 26

Figure 2-7: Sampling localities of the study area ... 27

Figure 2-8: New Machavie Mine complex and downstream localities ... 28

Figure 2-9: Buffelsdoorn Mine complex and related sampling localities ... 29

Figure 2-10: Mine Waste Solutions mining complex and related sampling localities ... 30

Figure 2-11: Hartebeestfontein and Buffelsfontein mining complexes with related sampling localities . 31 Figure 3-1: Sorption phases of selected potentially toxic trace elements in soils ... 38

Figure 3-2: Mobility trends of potentially toxic trace elements versus soil pH ... 63

Figure 3-3: Conceptual response diagram for potentially toxic trace element uptake by foliage ... 64

Figure 3-4: Bioaccumulation of potentially toxic trace elements by green plants from soils ... 65

Figure 3-5: Interactions of potentially toxic trace elements in plants and in soil solution ... 68

Figure 3-6: Critical Zone materials and energy processes ... 69

Figure 3-7: Source-pathway-receptor model for potential contamination from mines ... 71

Figure 3-8: Types of drainage produced by the oxidation of sulphide minerals ... 74

Figure 3-9: Phytoextraction process ... 78

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LIST OF TABLES

Table 2-1: Geology of the Loraine Formation ...9

Table 2-2: Geology of the Black Reef Formation ... 10

Table 2-3: Geology of the Malmani Subgroup ... 11

Table 2-4: Identified soil forms ... 12

Table 2-5: Vegetation classification of the study area ... 22

Table 2-6: Grass species and vegetation units ... 23

Table 2-7: Locality code backbone ... 25

Table 2-8: Locality and sampling matrix ... 33

Table 3-1: World mine production of potentially toxic trace elements ... 40

Table 3-2: Natural chromium concentrations ... 42

Table 3-3: Chemical speciation of chromium3+_{relative to soil conditions ... 43}

Table 3-4: Natural cobalt concentrations ... 44

Table 3-5: Natural nickel concentrations ... 47

Table 3-6: Chemical speciation of nickel relative to soil conditions ... 48

Table 3-7: Natural copper concentrations ... 49

Table 3-8: Chemical speciation of copper relative to soil conditions... 50

Table 3-9: Natural lead concentrations ... 52

Table 3-10: Natural zinc concentrations ... 54

Table 3-11: Chemical speciation of zinc relative to soil conditions ... 55

Table 3-12: Natural arsenic concentrations ... 57

Table 3-13: Natural uranium concentrations ... 59

Table 3-14: Sulphide minerals ... 72

Table 3-15: Acidophilic bacteria with growth parameters ... 73

Table 3-16: Chemical equations representing acid mine generation ... 75

Table 3-17: Advantages and disadvantages of phytoremediation ... 80

Table 4-1: Composite vs individual samples ... 82

Table 4-2: Sample type and potentially toxic trace element codes ... 84

Table 4-3: Sampling locality list with locality descriptions, sample types and data sources ... 85

Table 4-4: Analysed plant species vs sample localities showing grazing value status ... 91

Table 4-5: Analyses conducted per sample type ... 93

Table 4-6: Baseline and threshold/guideline values for specific potentially toxic trace elements ... 96

Table 4-7: Soil screening values for specific potentially toxic trace elements ... 97

Table 4-8: Geoaccumulation index scale ... 100

Table 4-9: Bioaccumulation index scale ... 101

Table 5-1: Analysis of oxidised and unoxidised tailings results ... 105

Table 5-2: Analysis of surface soil and subsoil results ... 116

Table 5-3: Analysis of stream sediment results ... 136

Table 5-4: Analysis of plant tissue results ... 143

Table 6-1: Summary of current contamination by tailings, soil and sediment ... 184

Table 6-2: Summary of potential future contamination by tailings, soil and sediment... 186

Table 6-3: Summary of plant tissue accumulation status ... 218

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LIST OF EQUATIONS Eq. 1 ... 72 Eq. 2 ... 74 Eq. 3 ... 75 Eq. 4 ... 75 Eq. 5 ... 75 Eq. 6 ... 75 Eq. 7 ... 75 Eq. 8 ... 75 Eq. 9 ... 75 Eq. 10 ... 75 Eq. 11 ... 75 Eq. 12 ... 76 Eq. 13 ... 76 Eq. 14 ... 98 Eq. 15 ... 98 Eq. 16 ... 98 Eq. 17 ... 99 Eq. 18 ... 100 Eq. 19 ... 100 Eq. 20 ... 101

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LIST OF APPENDICES

Appendix A: Tailings results ... 264

Appendix B: Soil results ... 266

Appendix C: Surface water results ... 270

Appendix D: Stream sediment results ... 271

Appendix E: Plant tissue results ... 272

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1 INTRODUCTION 1.1 Overview

Gold mining, both in the past as well as currently, fulfils a critical function in socio-economic development and upliftment in South Africa. However, the environmental impacts resulting from mining are often numerous and varied in degree of severity. One such potential impact is the contamination of freshwater systems in terms of surface water and stream sediments, as well as of the soils and plants in the surrounding environs (Critical Zone impacts). This issue is critical in South Africa, especially in terms of the increasing demand for land in a climate of dwindling land quality. Due to the potential costs involved, the rehabilitation of drainage systems and surrounding ecosystems can be problematic for mines, particularly those nearing closure, and also due to the environmental and possible legal implications. It is therefore essential that guidelines are established for prevention of contamination, and that rehabilitation or mitigation specification criteria are established for drainage systems currently contaminated by tailings dam facility seepages. (Van Deventer & Slabbert, 2011)

In terms of Section 24 of the Bill of Rights of the Constitution (1996), the following environmental rights are stipulated:

“Everyone has the right 

a. to an environment that is not harmful to their health or well-being; and

b. to have the environment protected, for the benefit of present and future generations, through reasonable legislative and other measures that -

i. prevent pollution and ecological degradation; ii. promote conservation; and

iii. secure ecologically sustainable development and use of natural resources while promoting justifiable economic and social development.”

Six point sources of potential gold mine contamination are situated along the Kromdraai/ Koekemoerspruit drainage system (KDS) in the Eleazar/Stilfontein area, namely the abandoned New Machavie Mine complex (NeMa-MC), the Buffelsdoorn Mine complex (BuDo-MC), the Mine Waste

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Solutions (also known as First Uranium or Chem-Wes) mining complex (MiWa-MC), the Hartebeestfontein Mine complex (HaFo-MC), the Buffelsfontein #10 Shaft mining complex (Bu10-MC), and the Buffelsfontein Mine complex (BuFo-MC). The MiWa and BuFo complexes have largely been regarded as the primary sources of gold mining contamination to the KDS; however, the relative contribution of each point source has yet to be ascertained. The purpose of this study was to identify and differentiate between these point sources and to evaluate the environmental surface impacts of each individual entity upon the KDS in order to provide a more accurate representation of both the potential and current contamination status. As such, geochemical characterisation of the surface impacts of gold mining activities along a drainage basin on the surrounding environment by means of the inorganic quality assessment of the tailings, soils, surface water, stream sediments and vegetation was conducted (Van Deventer & Slabbert, 2011), and was displayed as both current and potential contamination status using geochemical and biological indices via a source-pathway-receptor flow model.

A distinction must be made between total and available potentially toxic trace element [PTE] concentrations with regard to the associated ecological footprint by referring specifically to the individual and combined effect thereof on soils, water, stream sediment and vegetation (Gryschko et al., 2004:105-106; Güven & Akinci, 2011:369). Only the mobile and available PTE component is taken up by plants, resulting in toxicity of plants (of which lower yield is a function) and in animals (where ingestion occurs). Toxicity occurs once critical tissue concentration is reached in the plant (Macnicol & Beckett, 1985:107-108). The accumulation of PTEs in stream sediments and their presence in water closely relates to the solubility status which is determined by a number of biogeochemical factors (Roychoudhury & Starke, 2006:1045). Thus the potential contaminating substrate, soils and underlying geology of drainage systems must be critically evaluated when assessing environmental impacts and making recommendations for the prevention of contamination as well as the mitigation and rehabilitation of affected areas.

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1.2 Aims and objectives

The aims of this study are:

1. To conduct an in-depth assessment/quantification of geochemical, biophysical and hydrological characteristics of the KDS in order to determine quality status. This will provide a sound basis for a holistic methodology aimed at preventing and mitigating contamination problems, was well as rehabilitating mining land and the adjoining environs for sustainable and socio-economic post-closure land use.

2. To construct a geoecological guideline document on the influence of gold mines on drainage systems, with special reference to the effect of PTEs on the soils, sediments, plant species and surface water of a drainage system which is fed by seepage from gold tailings storage facilities.

The objectives of this study are:

1.1 To identify the six gold mining point sources along the KDS. 1.2 To determine the degree of contamination at each point source.

1.3 To determine the individual contribution of these point sources to the contamination of downstream localities.

1.4 To distinguish between and evaluate the total PTE concentration pool as well as the available (soluble) fraction relative to pH and plant uptake for the different sample types.

1.5 To provide a more accurate representation of both the current contamination status and potential future contamination impacts at localities within the study area.

1.6 To indicate the bioaccumulation and hyperaccumulation status of plant species relative to rehabilitation recommendations.

2.1 To use the guideline document as a preventive tool for future contamination and also to use it as criteria for rehabilitation specifications for contaminated drainage systems.

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1.3 Provisos

The following terms of reference are pertinent to the focus and layout of this dissertation:

1. Sampling of the different sample types took place based on locality-specific attributes and relevance, environmental conditions (drought, fire, etc.), access to a given locality, availability of a sample material, and the data provided by other sources. This, together with analysed data occurring below detectable limits, is represented by blank spaces in the results tables under the designations ‘Below detectable limits’, ‘Not available’ and ‘Not sampled’. Because of this, certain indices could not be calculated at specific localities for given sample types.

2. Although the sample type of surface water was stipulated as a pathway and/or receptor potentially impacted by gold mine tailings, it was not discussed due to both environmental and analytical constraints experienced during the course of the study (see Section 5.3 for a more detailed explanation). As such, the focus of this study lay on the interaction of tailings with the soil, stream sediments and various plant species sampled along the KDS as a representation of the potential contamination by gold mine activities.

3. A photo record depicting individual localities with relevant descriptions is included in Appendix F (enclosed CD).

4. Plant tissue was analysed and discussed with direct relevance to the species growing at a specific locality and for contamination status/rehabilitation purposes.

5. The analytical parameters of this study comprised eight PTEs (Cr, Co, Ni, Cu, Pb, Zn, As and U) as well as pH with regard to contamination of a locality. All other analyses fell outside the scope of this study, unless noted with due relevance.

6. Various geochemical and biological indices were used for statistical analysis of the data, factoring in the use of composite sampling in this study (see Section 4.2 for justification of the use of this method pertinent to this study).

7. All mining complex localities (prefixed by e.g. NeMa, and suffixed by e.g. TSF) may be discussed or grouped under their applicable sites (e.g. NeMa-MC), where relevant.

8. The locality codes are, as far as possible, listed sequentially according to the drainage direction of the KDS along the north-south axis, starting in the north of catchment basin C24A.

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9. Justification for the relevance and use of composite sampling in this study is discussed in Section 4.2.

10. Statistical analyses of the data were conducted via the use of geochemical and biological indices based on the use of composite sampling as well as the approach of contamination models and plant accumulation efficiency/status.

11. In the majority of cases, data from the year 2012 originated from sampling by the author. However, additional data from other sources were also used in this study and were collected in the years 2000, 2008, 2009, 2011, 2012 and 2013. As such, data interpretations should be made accordingly.

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2 STUDY AREA

This study was conducted in the KDS and environs of the quarternary drainage basin C24A (De Villiers & Mangold, 2002:sec. 2.3) and the 1:250 000 2626 Geological Sheet of the West Rand published by the Council for Geoscience was used for the purposes of this study. The catchment area covers an area given to agricultural activities, such as dry-land, irrigation and livestock farming, as well as gold mining activities. Several tributaries originating in the north of the catchment area converge to form the Kromdraaispruit. The Kromdraaispruit becomes the Koekemoerspruit at the confluence of the two streams nearly halfway down the catchment area. The study area commences in the upper reaches of the Kromdraaispruit and concludes where the Koekemoerspruit runs dry just prior to joining the Vaal River.

Six point sources of potential contamination related to gold mining activities are located along the KDS as follows:

 The NeMa-MC (tailings from Black Reef mining) next to the Kromdraaispruit on the dolomitic Oaktree Formation;

 The BuDo-MC beside the Koekemoerspruit prior to the confluence on the quartzitic Black Reef Formation;

 The MiWa-MC along the KDS (after the confluence) on the dolomitic Oaktree Formation; and

 The HaFo-, Bu10- and BuFo-MCs along the KDS (after the confluence) on the dolomitic Monte Christo Formation.

Six control points for the study area were identified as follows:

 Three control points upstream from all gold mining activities at the top end of the drainage system (DrSy); the first two (CoLa-1 and CoLa-2) on the andesitic Loraine Formation, with the third (CoDo-1) on the dolomitic Oaktree Formation.

 A fourth control point (CoDo-2) just above and northwest of the NeMa-MC on the dolomitic Oaktree Formation;

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 The sixth control point (CoDo-4) to the east of the HaFo-MC, and northwest of the Bu10-MC and BuFo-MC on the dolomitic Monte Christo Formation.

Various drainage system (DrSy) localities downstream from point sources were sampled along the KDS.

Consult the List of acronyms, Table 2-7 and Table 4-2 for explanation of the locality and sample type codes. A photo record including locality descriptions is provided in the attached CD.

2.1 Geological setting

The area through which the KDS flows lies on the northwestern edge of the Witwatersrand Basin (Antrobus et al., 1986:553). The geology of this region comprises conglomerate, quartzite and shale outcrops of the Black Reef of the Transvaal Supergroup, as well as lavas and sediments of the Ventersdorp Supergroup to the north of Stilfontein; however, dolomites of the Transvaal Supergroup cover most of the study area (Antrobus et al., 1986:553). The only visible outcrops in the study area are the andesitic lavas of the Loraine Formation of the Ventersdorp Supergroup, as well as the Black Reef quartzite and Oaktree dolomitic Formations of the Transvaal Supergroup. Black Reef quartzites were mined at NeMa-MC and BuDo-MC, whilst the Vaal Reef conglomerate has been mined at MiWa-MC, HaFo-MC, Bu10-MC and BuFo-MC. The geology of the study area is illustrated in Figure 2-1.

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(Arc Map 10; Google Earth, 2013; Eriksson et al., 2006:237-260; NWU geodatabase, 2013; Van der Westhuizen & De Bruiyn, 2006:187-208)

[Compiled by Jaco Koch, 2013]

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2.1.1 Ventersdorp Supergroup

The Ventersdorp Supergroup primarily consists out of andesitic, rhyolitic, basaltic and dacitic lavas, quartz-feldspar porphyries, greywackes, tuff, agglomerates, conglomerates, shale and limestone (King,

et al., 2007:9; Visser, 1989:33).

2.1.1.1 Loraine Formation

Table 2-1: Geology of the Loraine Formation

Ventersdorp Supergroup (± 2700 Ma) Klipriviersberg Group (2699 ± 50 Ma) Edenville Formation Loraine Formation Jeannette Formation Orkney Formation Alberton Formation East Driefontein Subgroup Westonaria Formation

Venterspost Formation

(McCarthy & Rubidge, 2005:17, 105-108; Van der Westhuizen & De Bruiyn, 2006:190-191)

The Loraine Formation belongs to the Klipriviersberg Group of the Ventersdorp Supergroup (Table 2-1). It has a stratigraphic thickness of ± 217 m, and comprises micro-crystalline to medium-grained andesitic lavas that are both aphyric and porphyritic, the bulk of which is aphyric (Antrobus et al., 1986:573, King,

et al., 2007:11; Marsh et al., 1992:817; Van der Westhuizen & De Bruiyn, 2006:193-194). The defining

features of this Formation are olive-green amygdales [set in a detrital, tuffaceous matrix that is quartzitic to cherty in nature] together with marker horizons such as alteration zones (Antrobus et al., 1986:549, 575; Winter, 1976 [cited by Van der Westhuizen & De Bruiyn, 2006:194]). These alteration zones are green aphanitic lavas displaying a high concentration of variolitic or globular structures (Antrobus et al., 1986:575; Van der Westhuizen & De Bruiyn, 2006:193-194) within well-preserved igneous textures (Marsh et al., 1992:817). Due to their calcitised and chloritised properties, these lavas are markedly lighter in colour [light-grey] (Antrobus et al., 1986:575; Van der Westhuizen & De Bruiyn, 2006:193-194). Geochemically, the lavas are relatively variable due to the presence of orthopyroxene in the fractional crystallization (Marsh et al., 1992:817). Small chlorite amygdales [± 0.5 mm in diameter], glassy mesostasis [to a lesser degree] and augite in the form of non-ophitic, lath-shaped microphenocrysts [to a greater degree] are present in these lavas (Antrobus et al., 1986:575; Van der Westhuizen & De Bruiyn, 2006:193-194). Plagioclase phenocrysts together with chlorite pseudomorphs,

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formed as a result of primary mafic phenocryst phases, are found in the porphyritic lavas and comprise approximately 5% of the rock (Van der Westhuizen & De Bruiyn, 2006:193-194).

2.1.2 Transvaal Supergroup

The Transvaal Supergroup primarily consists out of gritstone and small-pebbled conglomerates underlying siliceous orthoquartzites that are interbedded with overlying carbonaceous shales (King, et

al., 2007:12, 47; Obbes, 2000:18; Visser, 1989:43).

2.1.2.1 Black Reef Formation

Table 2-2: Geology of the Black Reef Formation

Transvaal Supergroup (± 2650 Ma)

Black Reef Formation (± 2642 Ma)

(Eriksson et al., 2006:245; King, et al., 2007:12-13, 47; McCarthy & Rubidge, 2005:17, 111-112)

The Black Reef Formation forms the basal unit of the Transvaal Supergroup (Table 2-2). It can be defined as an alluvial gravel or scree above an erosional, arenaceous unconformity that overlies older successions (Eriksson et al., 2006:242; King, et al., 2007:47). Quartz arenites prevail, with conglomerates and mudrocks to a lesser extent (Eriksson et al., 2006:242). This Formation forms a thin yet extensive sheet of quartzite that displays a variable thickness of ± 25 m, with a maximum thickness of 60 m (Eriksson et al., 2006:243; Visser, 1989:43). The basal conglomeratic facies, derived from the underlying Witwatersrand beds, contains detrital or placer gold, uranium and pyrite mineralisation (King, et al., 2007:47, 50). The pyritic, chloritic and carbonaceous composition is responsible for the characteristic dark- to bluish-grey colour of the Black Reef quartzites (Antrobus et al., 1986:575). This clastic Formation is mostly impersistent in terms of development and mineralisation; pebbles are generally poorly-sorted and vary widely in size, mineralogical composition and shape (Antrobus et al., 1986:549, 575; King, et al., 2007:12, 49-50). The basal conglomerate is not uniformly continuous and is succeeded by thicker quartzites and thin mudrocks; resulting in an ascending trend of successively finer grain-size distribution (Henry et al., 1990 [cited by Eriksson et al., 2006:242]). In contrast to this, the mudrocks and quartzites overlying this basal sequence present an ascending trend of coarsening grain-size distribution (Key, 1983 and Henry, et al., 1990 [cited by Eriksson et al., 2006:243]).

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2.1.2.2 Monte Christo and Oaktree Formations Table 2-3: Geology of the Malmani Subgroup

Transvaal Supergroup (± 2650 Ma)

Chuniespoort Group

(± 2642 Ma) Malmani Subgroup

Frisco Formation Eccles Formation Lyttelton Formation Monte Christo Formation Oaktree Formation

(Eriksson et al., 2006:245; McCarthy & Rubidge, 2005:17)

The Monte Christo and Oaktree Formations belong to the Malmani Subgroup within the Chuniespoort Group of the Transvaal Supergroup (Table 2-3). Dolomite outcrops cover most of the area, whilst massive weathered chert bands dominate the Monte Christo Formation and only small, thin bands are found in the Oaktree Formation (King, et al., 2007:12; Pretorius & Dennis, 2007:3; Van Deventer, 2011:23; Visser, 1989:44). The iron- and manganese-rich dolomitic Oaktree Formation encompasses between 10 and 200 m of carbonaceous shales, quartzites, stromatolitic dolomites and dolomites developed in situ, and is a transitional zone between siliclastic sedimentation and platformal carbonates (Eriksson et al., 2006:244; King, et al., 2007:12; Obbes, 2000:26-30). The overlying Monte Christo Formation varies in thickness between 300 and 500 m, and comprises erosion breccia, stromatolitic and oolitic platformal dolomites, oolitic carbonates and mudstones (Eriksson et al., 2006:244; King, et al., 2007:12; Obbes, 2000:30-36); iron- and manganese oxides are not a prominent feature (Van Deventer, 2011:23). Dolines and palaeo sinkholes commonly associated with the surface instability of dolomites have not been found in the Oaktree Formation, but erosion-slump structures dominate in the Monte Christo Formation and also occur in the Oaktree Formation (Pretorius & Dennis, 2007:3; Van Deventer, 2011:23).

2.2 Pedology

The soil forms identified at the different sampling localities in the study area are shown in alphabetical order in Table 2-4, together with the World Reference Base (WRB) reference group and United States Department of Agriculture (USDA) soil taxonomy classifications. Please take note that uniformity of the soil form within each sample locality radius was ensured during sampling; however, due to the inherent difficulty in identifying soil forms below certain tailings structures such as tailings storage facilities (TSFs) and spillages (SPs) based on the extent (size and depth), as well as the varied occurrence of soil forms at

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certain localities (as at NeMa-MC), specific localities may be listed as occurring on more than one soil form.

In Table 2-4, the localities are listed sequentially according to the drainage direction of the KDS along the north-south axis next to their associated soil forms. Consult the List of acronyms and Table 2-7 for explanation of the locality and sample type codes.

Table 2-4: Identified soil forms

Locality Soil family Soil form

Diagnostic horizons (profile) WRB reference group USDA soil taxonomy DrSy-3 DrSy-5

Lonehill 1100 Dominant: Arcadia

(Aeromorphic) Vertic A Phaeozemic

Vertisol Vertisol Greendale 1000 Subdominant: Rensburg

(Hydromorphic) Unspecified CoDo-2 NeMa-TSF1-1 NeMa-TSF1-2 NeMa-SP-1 NeMa-TSF2 NeMa-TSF3 NeMa-TSF4-1 NeMa-TSF4-2 NeMa-SP-2 NeMa-SP-3 DrSy-1 CoDo-4 Hayfield 2100 or Suurbekom 2200 Hutton (Rhodic) Orthic A Acrisolic / Lixisolic / Arenosolic / Cambisolic Ferralsol Oxisol Red apedal B Unspecified DrSy-2 DrSy-7 DrSy-8 DrSy-9 DrSy-10 DrSy-12 DrSy-16 DrSy-21 DrSy-23 Lammermoor 1000 Katspruit (Orthic)

Orthic A _Gleysol _Ultisol G horizon NeMa-TSF1-1 NeMa-TSF1-2 NeMa-SP-1 NeMa-TSF2 NeMa-TSF3 NeMa-TSF4-1 NeMa-TSF4-2 NeMa-SP-2 NeMa-SP-3 BuDo-RD HaFo-SP DrSy-22 Dumisa 1111 Lithosol (Skeletal soil) Orthic A Acrisolic / Lixisolic / Cambisolic Leptosol Inceptisol Glenrosa (Glossic) Lithocutanic B

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Table 2-4: Identified soil forms (cont.)

Locality Soil family Soil form

Diagnostic horizons (profile) WRB reference group USDA soil taxonomy NeMa-TSF1-1 NeMa-TSF1-2 NeMa-SP-1 NeMa-TSF2 NeMa-TSF3 NeMa-TSF4-1 NeMa-TSF4-2 NeMa-SP-2 NeMa-SP-3 BuDo-RD CoDo-3 MiWa-TSF4/ESP DrSy-14 DrSy-15 DrSy-17 DrSy-19 DrSy-20 DrSy-22 Myhill 1100 Lithosol (Skeletal

soil) Orthic A _Leptosol _Entisol

Mispah (Orthic) Hard rock CoLa-1 CoLa-2 CoDo-1 DrSy-8 DrSy-9 DrSy-11 DrSy-13 Greendale 1000 Rensburg (Hydromorphic) Vertic A Gleyic Vertisol Vertisol G horizon DrSy-6 DrSy-8 DrSy-9 DrSy-18 Rapoeli 1110 or Katdoorn 1210 Sepane (Pedocutanic-cumulic- hydromorphic) Orthic A Lixisolic Luvisol Alfisol Pedocutanic B Unconsolidated material with signs of wetness DrSy-6 DrSy-18 Slykspruit 1111 or Goedemoed 1121 Valsrivier (Pedocutanic-cumulic- aeromorphic) Orthic A Lixisolic Luvisol Alfisol Pedocutanic B Unconsolidated material without signs of wetness DrSy-4 MiWa-TSF5 MiWa-TSF4 MiWa-WT-1 MiWa-WT-2 MiWa-FP3 MiWa-TSF2 MiWa-FP2 MiWa-ESP MiWa-FP1 HaFo-TSF Bu10-ED BuFo-DC BuFo-TSF

Thornlea 1000 Witbank/Anthrosol Man-made soil

deposit Anthrosol Anthrosol

(IUSS Working Group WRB, 2007:70-71; Martin Fey, 2010: 41, 77, 110-111, 139; SCWG, 1991:44-47, 230; Soil Survey Staff, 2003:13; Van Deventer, 2014b)

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Calcareous soils possess high levels of calcium carbonate with a strong buffering capacity (USDA NRCS (1998:2). According to Van Deventer (2011:23), dolomite outcropping of the Monte Christo and Oaktree Formations is extensive, with soil layers rarely exceeding a thickness of 20 cm. Oxisols [Hutton soil form] often occur and manganese [Mn] cations dominate in these soils, whilst high concentrations of nickel [Ni] and zinc [Zn] may occur due to natural anomalies in the dolomite (Van Deventer, 2011:23). Over a period of about 15 years, the high infiltration and buffer capacities of dolomitic soils may play a role in reducing PTE concentrations in these soils as well as in the associated vegetation (Van Deventer, 2011:26). Based on this, regular monitoring and risk assessment via the appropriate geochemical and biological indices could reflect the current contamination status of a locality as well predict potential future contamination, thereby providing a focus for rehabilitation management protocols.

2.3 Climate and topography 2.3.1 Regional climate

Site-specific climate data were unavailable for the study area, and as a result, data from the Potchefstroom and Klerksdorp weather stations [GPS coordinates: -26.74/27.08 and -26.90/26.62, respectively] (courtesy of the South African Weather Service [SAWS], 2013) were used to describe rainfall and temperature. The total monthly rainfall, as well as the average maximum and minimum monthly temperatures (for both Klerskdorp and Potchefstroom for the years 2008 to 2012), are shown in Figure 2-2, Figure 2-3 and Figure 2-4.

The regional climate is distinctively South African ‘Highveld’ which entails cold, dry winters and hot, rainy summers; the annual rainfall averages 580 – 625 mm (Antrobus, 1986:551; Aucamp, 2000:3.3; Mucina & Rutherford, 2006:355, 442; Van Deventer, 2011:22-23), with 80% occurring between October and March (Pretorius & Dennis, 2007:4). Summer temperatures average 30°C, whilst winter temperatures average 18°C; frost is characteristically occurs during April to September (Van Deventer, 2011:22-23), with an average of 34 days of frost yearly (Van Wyk & Seiderer, 2012:6).

The region experiences high annual evaporation rates averaging 2 141 - 2 407 mm (Mucina & Rutherford, 2006:354, 442; Pretorius & Dennis, 2007:5; SAWS, 2013), and this, together with the low

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rainfall rates of 2012 compared to previous years [Figure 2-2], contributed towards a particularly dry year in which sampling was conducted. According to Van Wyk & Seiderer (2012:6), the soil moisture stress per annum averages 78%; meaning that for this percentage of days, the evaporative demand is at least twice that of the soil moisture resource.

Northwesterly winds prevail in the area (Van Deventer, 2011:22-23); northerly, northeasterly and southwesterly winds occur to a lesser degree, particularly during the period August to January (Aucamp, 2000:3.4; SAWS, 2013).

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(SAWS, 2013*)

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(SAWS, 2013*)

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(SAWS, 2013*)

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*In Figure 2-2, Figure 2-3 and Figure 2-4, the data averages for the following months and years are unreliable due to missing daily values (SAWS, 2013): Klerksdorp: Maximum temperatures  2011 - Dec  2012 - Oct Potchefstroom: Maximum temperatures  2008 - Jun, Jul, Aug, Sep, Dec

 2009 - Jun, Aug, Sep, Oct, Nov

 2010 - Jan, Sep, Nov, Dec

 2011 - Jan, Feb, Mar, Dec

Minimum temperatures  2008 - Jun

 2010 - Jan, Mar, Aug

 2011 - Dec

 2012 - Oct

Minimum temperatures  2008 - Jun, Jul, Aug, Sep, Dec

 2009 - Jun, Aug, Sep, Oct, Nov, Dec

 2010 - Jan, Sep, Nov, Dec

 2011 - Jan, Feb, Mar, Dec

Total rainfall

 2008 - Jun, Aug, Sep, Oct, Nov, Dec

 2009 - Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec

 2010 - Jan, Feb,Mar, Apr, May, Jun, Jul, Aug, Dec

 2011 - Feb, Mar, Apr, Jul, Aug, Nov

 2012 - Jan, May, Jun, Aug, Oct, Nov, Dec

Total rainfall

 2008 - Apr, Jun, Jul, Aug, Sep, Oct, Nov, Dec

 2009 - Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec

 2010 - Jan, Feb, Mar, Jun, Aug, Sep, Nov, Dec

 2011 - Jan, Feb, Mar, Jun

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2.3.2 Topography and drainage

The study area lies about 1 300 - 1 500 m above sea level [ASL] (Antrobus, 1986:551) and the topography slopes gradually towards the south of the catchment (Aucamp, 2000:3.4). Hills and rocky ridges are scattered throughout the area up to 100 m above the surrounding planes; broad, flat valleys cut through the area, draining surface water into the KDS and associated tributaries (Antrobus, 1986:551; Pretorius & Dennis, 2007:5). The topography and drainage patterns of the study area are shown in Figure 2-5.

In the north of the catchment, the Kromdraaispruit originates at an elevation of 1 500 m ASL. Along the Kromdraaispruit, four control localites (CoLa-1, CoLa-2, CoDo-1 and CoDo-2), the NeMa-MC localities and the related downstream localities (DrSy-1, DrSy-2, DrSy-3, DrSy-4 and DrSy-5) are situated 1 420 m ASL, whilst the elevation decreases 40 m south towards the localities further downstream (DrSy-6, DrSy-7, DrSy-8 and DrSy-9) at 1 380 m ASL. The Koekemoerspruit originates in the northwest of the catchment at 1 440 m ASL; from this, the BuDo-MC locality and the related localities (DrSy-10, DrSy-11, DrSy-12 and DrSy-13) are found 1 380 m ASL, showing a 60 m reduction in elevation. The confluence of the KDS occurs at 1 360 m ASL, thus decreasing 20 m in elevation to the south. With a further 20 m drop in elevation, one control locality (CoDo-3), the MiWa-MC localities and the associated localities (DrSy-14, DrSy-15 and DrSy-16) are situated at 1 340 m ASL. This elevation is maintained southwards at the HaFo-MC localities and one control locality (CoDo-4). The Bu10-MC and related localities occur at 1 320 m ASL, showing a 20 m decrease in elevation; and further south, with a 20 m drop in elevation, the BuFo-MC is situated at 1 300 m. Therefore, the KDS sample localities in the study area are found along a generalised north-south slope with a 120 m decline in elevation.

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(Arc Map 10; Google Earth, 2013; NWU geodatabase, 2013) [Compiled by Jaco Koch, 2013]

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2.4 Vegetation

The KDS flows through the grassland and savanna biomes, which are typical of the North West Province (De Villiers & Mangold, 2002:sec. 2.7). Vegetation classifications by Acocks (1988:100, 103, 112), Bredenkamp & Van Rooyen (1996:39, 41, 43) and Mucina & Rutherford (2006:384, 386, 388, 467; 784) are shown in Table 2-5.

Table 2-5: Vegetation classification of the study area

Biome 1Vegetation unit 2Vegetation type 3Veld type

Grassland

Vaal-Vet Sandy Grassland

[Gh 10] Dry Sandy Highveld Grassland [LR 37]

Dry Cymbopogon-Themeda veld [VT 50] Cymbopogon-Themeda veld [VT 48] Vaal Reefs Dolomite

Sinkhole Woodland [Gh 12]

Rocky Highveld Grassland [LR 34]

Western Variation of the Bankenveld [VT 61a] Carletonville Dolomite

Grassland [Gh 15]

Bankenveld [VT 61]

Savanna Andesite Mountain

Bushveld [SVcb 11] Moist Cool Highveld Grassland [LR 39]

(1Mucina & Rutherford, 2006:384, 386, 388, 467, 784; 2Bredenkamp & Van Rooyen, 1996:39, 41, 43);

3

Acocks, 1988:100, 103, 112)

With regard to the Vaal Reefs Dolomite Sinkhole Woodland, it must be noted that sinkholes in the study area predominantly occur to the south of the N12 National Route (Van Deventer, 2013). The vegetation units will not be discussed in detail as the varying geology of the study area influences the topography, geomorphology and soils, which in turn determines the vegetation of the area on a more localised level, and is beyond the scope of this study.

Mucina & Rutherford (2006:385,386,388,468) list important grass species for each of the four vegetation units relevant to this study. Those grass species which correspond with species identified and/or collected at the sampling localities, together with grass species found additionally at the sampling localities, are shown in Table 2-6 (listed in alphabetical order).

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Table 2-6: Grass species and vegetation units

Grass species Vegetation unit

Grass species listed for vegetation units that correspond with identified and/or collected grass species at sampling localities:

Aristida canescens Vaal-Reefs Dolomite Sinkhole Woodland

Carletonville Dolomite Grassland

Aristida diffusa Carletonville Dolomite Grassland

Cymbopogon caesius Vaal-Vet Sandy Grassland

Vaal-Reefs Dolomite Sinkhole Woodland Carletonville Dolomite Grassland

Cymbopogon pospischilii Vaal-Vet Sandy Grassland

Vaal-Reefs Dolomite Sinkhole Woodland Carletonville Dolomite Grassland Andesite Mountain Bushveld

Cynodon dactylon Vaal-Vet Sandy Grassland

Digitaria eriantha Vaal-Vet Sandy Grassland

Vaal-Reefs Dolomite Sinkhole Woodland Andesite Mountain Bushveld

Eragrostis biflora Vaal-Reefs Dolomite Sinkhole Woodland

Eragrostis chloromellas Vaal-Vet Sandy Grassland

Eragrostis curvula Vaal-Vet Sandy Grassland

Eragrostis gummiflua Carletonville Dolomite Grassland

Eragrostis lehmanniana Vaal-Vet Sandy Grassland

Vaal-Reefs Dolomite Sinkhole Woodland

Eragrostis plana Vaal-Vet Sandy Grassland

Eragrostis superba Vaal-Vet Sandy Grassland

Vaal-Reefs Dolomite Sinkhole Woodland Andesite Mountain Bushveld

Eragrostis trichophora Vaal-Vet Sandy Grassland

Heteropogon contortus Vaal-Vet Sandy Grassland

Hyparrhenia hirta Carletonville Dolomite Grassland

Andesite Mountain Bushveld

Melinis repens Vaal-Reefs Dolomite Sinkhole Woodland

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Table 2-6: Grass species and vegetation units (cont.)

Grass species Vegetation unit

Grass species listed for vegetation units that correspond with identified and/or collected grass species at sampling localities:

Panicum coloratum Vaal-Vet Sandy Grassland

Pogonarthria squarrosa Vaal-Vet Sandy Grassland

Schizachyrium sanguineum Carletonville Dolomite Grassland

Setaria sphacelata Vaal-Vet Sandy Grassland

Themeda triandra Vaal-Vet Sandy Grassland

Triraphis andropogonoides Vaal-Vet Sandy Grassland

Additional grass species identified and/or collected at the sampling localities in this study:

Andropogon eucomis Aristida stipitata Eragrostis bicolor Eragrostis heteroma Eragrostis pallens Eragrostis superba Panicum natalense Paspalum dilatatum Sporobolus fimbriatus Triraphis andropogonoides Setaria pumila 2.5 Locality identification

2.5.1 Locality nomenclature and descriptions

The term ‘locality’ may refer to a mining complex, a site within a mining complex or an individual sampling site along the KDS.

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Table 2-7: Locality code backbone

Co Control locality (natural veld)

Underlying geology:

La Lavas

Do Dolomite

DrSy Drainage system localities running alongside the KDS. These localities may be directly

adjacent to, or up to 3 km away, and running parallel with the KDS.

MC Mine/mining complex

Main sources of potential contamination:

NeMa New Machavie Mine complex BuDo Buffelsdoorn Mine complex

MiWa Mine Waste Solutions mining complex HaFo Hartebeestfontein Mine complex Bu10 Buffelsfontein #10 Shaft mining complex BuFo Buffelsfontein Mine complex

Areas or structures within MC sites (these designations are used to supersede the ‘MC’ in a code when a specific area or facility is being referred to within an MC):

DC Drainage canal ED Evaporation dam FP Footprint

RD Rock dump

RWD Return water dam SP Spillage area

TSF Tailings storage facility WT Wetland

2.5.2 Locality maps and photos

Maps of the regional setting and the sampling localities of the overall study area are shown in Figure 2-6 and Figure 2-7, respectively. Maps of the different point source localities are displayed in Figure 2-8, Figure 2-9, Figure 2-10 and Figure 2-11. In the compilation of these maps, the resolution was adjusted to ensure minimal pixelation per Google Earth satellite image based on individual map requirements and ArcMap 10 capabilities.

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2.5.3 Locality and sampling matrix

A comprehensive matrix detailing sampling localities, sample types, sample sizes (n/nc), sample depths and statuses, total and soluble PTEs, number of species, GPS coordinates and soil forms (for all data collected by the author and obtained from additional data sources) is presented in Table 2-8.

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Table 2-8: Locality and sampling matrix 2012 2012 2012 2013 2013 2013 2013 2013 2013 2000 2012 2000 2012 C o La -1 C o La -2 C o D o -1 C o D o -2 N eM a -M C N eM a -T SF 1 -1 N eM a -T SF 1 -2 N eM a -SP -1 N eM a -T SF 2 N eM a -T SF 3 N eM a -T SF 4 -1 N eM a -T SF 4 -2 N eM a -SP -2 N eM a -SP -3 -26.63069 -26.63067 -26.64964 -26.66643 -26.66644 -26.66792 -26.66792 -26.67039 -26.67197 -26.67294 -26.67366 -26.67511 -26.67531 -26.67647 26.88855 26.88974 26.89308 26.86931 26.87203 26.87283 26.87283 26.87398 26.87256 26.87567 26.87250 26.86964 26.87496 26.87139 >3 27 >9 >3 >3 3 6 24 0 - 0.3 0 - 0.2 0 - 0.3 0 - 0.3 0 - 0.3 0 - 0.3 0 - 0.3 0 - 0.3               >3 27 6 5 6 - 6.1 3.1        11 + n=11 3 11 >3 11 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.3 0 - 0.3           27 12 4 26 6 7.6 - 10 1.2 0 - 0.3 0 - 0.3 0.4 - 0.7         3 3 FL FL 3 3 0 - 0.15 0 - 0.15 10 - 50 10 - 50 10 - 50 4 5 5 10 - 50 2 Hutton M C

* Taken along a vertical profile at given depths Bu10 Buffelsfontein #10 Shaft CoDo Control on Dolomites M iWa M ine Waste Solutions ESP Eastern spillage RWD Return water dam nc composite sample BuDo Buffelsdoorn CoLa Control on Lavas NeM a New M achavie FP Footprint SP Spillage

BuFo Buffelsfontein DrSy Drainage system DC Drainage canal M C M ining complex TSF Tailings storage facility HaFo Hartebeestfontein ED Evaporation dam RD Rock dump WT Wetland

Loraine M onte Christo Black Reef

# spp Sedge nc Rensburg depth (m) Total concentration Available concentration Subsoil nc depth (m) Total concentration Available concentration

Hutton, Glenrosa / M ispah P lant

tissue Surface

water

nc F l owing / P u ddle / St anding Stream sediment nc depth (m) Grass nc # spp Bulrushes nc # spp Year Sampling sites GP S SA M P LIN G T YP ES T ailings Oxidised nc depth (m) Total concentration Available concentration Unoxidised nc depth (m) Total concentration Available concentration So il Surface Visibly contaminated nc SOIL F OR M GEOLOGY

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Table 2-8: Locality and sampling matrix (cont. 1) 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 2012 D rSy -1 D rSy -2 D rSy -3 D rSy -4 D rSy -5 D rSy -6 D rSy -7 D rSy -8 D rSy -9 B uD o -M C B uD o -R D D rSy -10 D rSy -11 D rSy -12 D rSy -13 -26.67772 -26.67922 -26.68594 -26.68647 -26.69032 -26.71615 -26.73294 -26.74066 -26.74072 -26.74556 -26.74379 -26.74430 -26.74450 -26.74507 -26.74534 26.86768 26.87651 26.86728 26.87173 26.86636 26.84889 26.84342 26.84107 26.84190 26.78141 26.78239 26.78392 26.78496 26.78425 26.78532 3 0 - 0.3*      11 11 11 11 11 11 11 11 11 11 11 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15                       3 3 3 3 3 3 3 PU PU PU FL FL FL FL 4 3 3 4 3 4 3 3 3 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15 10 - 50 10 - 50 10 - 50 10 - 50 10 - 50 10 - 50 10 - 50 10 - 50 3 3 3 2 2 4 2 2

Hutton Katspruit Arcadia Witbank / Anthrosol Arcadia

Valsrivier /

Sepane Katspruit M C RD Katspruit Rensburg Katspruit Rensburg

Bulrushes nc # spp

SOIL F OR M

GEOLOGY M onte Christo Black Reef

Stream sediment nc depth (m) Grass nc # spp Available concentration Subsoil nc depth (m) Total concentration Available concentration Surface water nc F l owing / P u ddle / St anding So il Surface Visibly contaminated nc depth (m) Total concentration Year Sampling sites GP S SA M P LIN G T YP ES T ailings Oxidised nc depth (m) Total concentration Available concentration Unoxidised nc depth (m) Total concentration Available concentration P lant tissue Katspruit / Sepane / Rensburg Sedge nc # spp

(52)

Table 2-8: Locality and sampling matrix (cont. 2) 2008 2008 2008 2008 2012 2008 2008 2008 2011 2012 2008 2008 2012 2012 2012 C o D o -3 M iWa -M C M iWa -T SF 5 M iWa -T SF 4 M iWa -WT -1 M iWa -WT -2 M iWa -F P 3 M iWa -T SF 4 / ESP M iWa -R WD M iWa -T SF 2 M iWa -F P 2 M iWa -ESP M iWa -F P 1 D rSy -14 D rSy -15 D rSy -16 -26.80643 -26.82819 -26.81825 -26.81106 -26.82084 -26.82084 -26.81952 -26.81662 -26.82708 -26.82711 -26.82301 -26.82127 -26.82528 -26.81317 -26.81397 -26.81479 26.79686 26.80220 26.77376 26.80073 26.78518 26.78518 26.79425 26.80296 26.78132 26.79200 26.79219 26.80566 26.80591 26.80812 26.81504 26.82434 >18 5 - 26 30 - 114 0 - 1 0 - 0.3* 0 - 0.4       3 12 11 11 11 11 0 - 0.15 0 - 0.2 0 - 0.15 0 - 0.15 0 - 0.15 0 - 0.15           3 3 ST FL 3 3 0 - 0.15 0 - 0.15 10 >10 >20 >10 >10 >10 >10 >10 >10 10 - 50 10 - 50 10 - 50 4 3 3 4 3 4 2 3 5 3 5 3 10-50 10-50 3 2 >10 >10 1 1

M ispah M ispah RWD Katspruit

Oaktree

M ispah Bulrushes nc

# spp

Sedge nc

# spp

Oaktree M onte Christo

Witbank / Anthrosol Witbank / Anthrosol Witbank / Anthrosol

SOIL F OR M GEOLOGY So il Surface Visibly contaminated nc depth (m) Total concentration Available concentration Subsoil nc depth (m) Total concentration Available concentration Surface water nc F l owing / P u ddle / St anding Stream sediment nc depth (m) Grass nc # spp Year Sampling sites GP S SA M P LIN G T YP ES T ailings Oxidised nc depth (m) Total concentration Available concentration Unoxidised nc depth (m) Total concentration Available concentration M C P lant tissue