The Environmental Impact of the Abandoned Edendale Lead Mine Near Tshwane, South Africa

THE ENVIRONMENTAL IMPACT OF THE ABANDONED EDENDALE LEAD MINE NEAR TSHWANE, SOUTH AFRICA

Jenny Glass

MINOR DISSERTATION

Submitted in partial fulfilment of the requirements for the degree

MASTER OF SCIENCE

ENVIRONMENTAL MANAGEMENT

in the

FACULTY OF SCIENCE

at the

UNIVERSITY OF JOHANNESBURG

Supervisor: Prof. J-M. Huizenga Co-supervisor: Prof. J. Gutzmer Co-supervisor: H. Coetzee

December 2006

ABSTRACT

The mining industry has been associated with environmental pollution throughout the ages. Old abandoned mines are of particular concern due to the lack of remediation and monitoring of the pollution. The abandoned Edendale Lead Mine in Tshwane, South Africa, was in operation from the 1980’s until 1938 and mined primarily galena for the lead content, although some silver was also recovered in the early years. The mine was decommissioned before environmental legislation in South Africa, namely the National Environmental Management Act 107 of 1998 and the Minerals and Petroleum Resources Development Act 28 of 2002, required the mitigation of environmental impacts associated with mining. Consequently, the environmental effects of Edendale Lead Mine have not been determined. This study is aimed at establishing the source, extent and magnitude of environmental pollution associated with metal contamination from mining operations in the area. Such investigation is of particular interest as there are two schools in the area, namely the Edendale Primary and High School, and the mine site is located immediately adjacent to the Edendalespruit. Furthermore, there are numerous farms and some private residences in the area that rely on borehole water that may potentially be polluted.

The ore at Edendale Lead Mine was mined from a hydrothermal deposit, with irregularly disseminated argentiferous galena being the only ore mineral of importance. Two mineralisation stages can be recognised from material available on waste rock dumps, i.e. an intensely fragmented and strongly silicified breccia and a carbonate-dominated breccia with minor pyrite. The galena is restricted to the first mineralisation stage.

Water and solid samples were collected from the mine site and from the surrounding area. Through ion chromatography, Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) analysis, the water of the area is found to be of good quality according to the South African Department of Water Affairs and Forestry Domestic Water Guidelines. The main concern is the presence of hazardous concentrations of lead in the Edendalespruit below the old plant site and in a pit near shaft one; determined to be from the abundance of relatively soluble anglesite (PbSO4) and susannite/leadhillite (Pb4(SO4)(CO3)2(OH)2) in the slag heap and the waste rock dump.

Solid samples were mineralogically and chemically analysed using X-Ray Powder Diffraction (XRD) and X-Ray Fluorescence Spectrometry (XRF), which determined the soil to be enriched in lead, zinc, and copper. The lead, zinc and copper are from secondary minerals of galena, sphalerite and chalcopyrite, respectively.

Metal mobility and availability was found to be limited through high soil pH conditions, which encourage metal-carbonate precipitation reactions and absorption by iron oxides and hydroxides. However, the high concentrations of lead in the soil are of considerable concern due to its toxicity and the number of people at risk, namely at the Edendale Primary and High Schools as well as users of the Edendalespruit and local ground water sources. The soil lead levels exceed the European Union target and intervention standards, therefore, requiring immediate mitigation and remediation measures. Recommendations for remediation and prevention measures may include the removal of the slag heap at the old mine site and the use of phytoremediation.

LIST OF ABBREVIATIONS

BLL: Blood Lead Levels BSE: Backscattered Electron Image DWAF: Department of Water Affairs ECA: Environmental Conservation Act 73 of 1989 EIA: Environmental Impact Assessment ELM: Edendale Lead Mine EPA: Environmental Protection Agency ESP: Electrostatic Precipitator EU: European Union FAO: Food and Agricultural Organisation of the United Nations GDP: Gross Domestic Product GPS: Global Positioning System HA Hydroxyapatite ICP-MS: Inductively Coupled Plasma - Mass Spectrometry ICP-OES: Inductively Coupled Plasma – Optical Emission Spectrometry NEMA: National Environmental Management Act 107 of 1998 PAAS: Post Achaean average Australian Shale PICs: Products of Incomplete Combustion SEM: Scanning Electron Microscope TDI: Tolerable Daily Intake TWQR: Target Water Quality Range WBG: World Bank Group WHO: World Health Organisation XRD: X-Ray Diffraction XRF: X-Ray Fluorescence Spectrometry

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ACKNOWLEDGEMENTS

I would like to thank the following people and organisations: • Prof. J.M. Huizenga to whom I am immensely grateful for his endless patience, guidance and help with this thesis. • H. Coetzee from the Council for Geoscience for providing the topic, background to this study and for his invaluable observations. • Prof. J. Gutzmer for his valuable suggestions and comments, particularly pertaining to the mineralogy. • Spectrau, specifically Dr. H. Van Niekerk and Dr. C. Reinke, for their patient explanations and suggestions. • Council for Geoscience for permitting me to undertake this thesis and access to their analytical equipment. • Department of Chemistry at the University of Johannesburg, namely S.B. Mubenga, for the water analyses. • Department of Geology at University of Johannesburg for allowing me to carry out this study. • The University of Johannesburg for financing this thesis. • Finally Kelly Bucas for all the support and motivation, without her this would not have been possible; Tamara King for her endless encouragement, understanding and inspiration; Lauren Nirta for everything; and lastly my parents for giving me this opportunity.

TABLE OF CONTENTS

ABSTRACT i LIST OF ABBREVIATIONS iii ACKNOWLEDGEMENTS iv LIST OF FIGURES vii LIST OF TABLES ix

1. Introduction 1

2. Statement of the problem 3

3. Description of the study area 5 3.1 Geological background and study area 5 3.2 Edendale lead mine 8

3.2.1 Location and history 8

3.2.2 Climate, vegetation and hydrology 11

3.2.3 Geological features and history 11

3.2.4 Ore mineralogy and petrology of the ELM 12

3.2.5 Lead smelting process 17

4. Data collection and methodology 25 4.1 Data collection 25

4.1.1 Data required 25

4.1.2 Sample collection procedures 29

4.2 Analytical methodology 29

4.2.1 Water samples 29

4.2.2 Solid samples 30

4.3 Results 31

4.3.1 Water samples 31

4.3.2 Solid samples 38

5. Discussion and conclusions 45

6. Recommendations 53

7. References 56

APPENDIX I: Microprobe report compiled by Dr. C. Reinke from SPECTRAU, University of Johannesburg. 60 APPENDIX II: The occurrence and health effects of lead. 63

APPENDIX III: Map coordinates of solid and water samples collected from the Edendale Lead Mine and surrounding areas. 68 APPENDIX IV: Element concentration ranges and their effects on human health, indicating the Target Water Quality Range. 69 APPENDIX V: XRF data using Shale PPow program 72

LIST OF FIGURES

Figure 1: Distribution of the Transvaal Supergroup in South Africa. 5 Figure 2: Outcrop of the Transvaal Supergroup in the Transvaal area. 6 Figure 3: Lithostratigraphy of the upper part of the Silverton Formation. 8 Figure 4: Geological map of the study area; indicating the old Edendale and Union Mines, Edendale mine shafts, and the approximate location of the mineralised vein at the Edendale Lead Mine. 9 Figure 5: Annual output of lead and silver from the ELM, 1904-1938. 10 Figure 6: A-C: Silicified tectonic breccia, stage one vein infill; A: Hand specimen; B: Galena intergrown with sphalerite (reflected light); C: Exsolutions of chalcopyrite in sphalerite (reflected light); D-F: Carbonate-cemented breccia (stage two) D: Hand specimen; E: Quartzite fragment surrounded by carbonate, rimmed with pyrite (transmitted light); F: Chlorite associated with pyrite (transmitted light). 15 Figure 7: Original SEM image of an aggregate of galena, sphalerite and quartz; and elemental X-ray maps for As, S, Cu, Pb, Si and Zn. Higher concentrations of the element mapped shows up as brighter in colour. Note minute grain of chalcopyrite (Cu map). 16 Figure 8: Backscattered-electron image of cobalite (further data in Appendix I). 17 Figure 9: A typical primary lead smelting and refining process. 18 Figure 10: Schematic cross section through a reverberatory furnace. 22 Figure 11: Process of lead smelting at the ELM. 23 Figure 12: A: Image of study area, indicating main features; B: Sample points near shaft one (red block on A); C: Sample points near shaft two (blue block on A). 26 Figure 13: Photographs of Edendale Lead Mine, A. Waste rock dump; B: Plant site; C: Plant site; D: White precipitate on rocks at plant site; E: Encrustations in and on slag heap; F: Encrustations and malleable metallic material of slag heap. 28 Figure 14: Element concentrations within water samples RW1, NW1, RW2, RW3, NW5, RW4, NW4, RW6 and NW6. Anion concentrations measured by ion chromatography, cation concentrations measured by ICP-OES, and lead and arsenic concentrations measured by ICP-MS. Note TWQR is plotted for reference (for GPS coordinates see Appendix III and for TWQR see Appendix IV). 35

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Figure 15: Element concentrations within water samples RW7, NW2, RW8, NW8, RW10, NW3 and NW7. Anion concentrations measured by ion chromatography, cation concentrations measured by ICP-OES, and lead and arsenic concentrations measured by ICP-MS. Note TWQR is plotted for reference (for GPS coordinates see Appendix III and for TWQR see Appendix IV). 37 Figure 16: Normalised trace element concentrations for soil samples (for XRF data see Appendix V). 40 Figure 17: Normalised trace element concentrations for waste rock dump material (for XRF data see Appendix V). 40 Figure 18: Normalised trace element concentrations for slag material (for XRF data see Appendix V). 40 Figure 19: Lead concentrations normalised to target values of the EU standard (see Appendix V for XRF data). 42 Figure 20: Lead concentrations normalised to intervention values of the EU standard (see Appendix V for XRF data). 42 Figure 21: Image illustrating the spatial distribution of lead concentrations around the ELM (concentrations normalised to EU target values). 44

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LIST OF TABLES

Table 1: The total marketable output of shaft one. 10 Table 2: Process materials inputs and pollution outputs for lead smelting and refining. 21 Table 3: Sample names and locality descriptions (for GPS coordinates see Appendix III). 28 Table 4: pH values for water samples (for GPS coordinates see Appendix III). 31 Table 5: Results of ion chromatography analysis of water samples (all results in mg/L). 33 Table 6: Results of ICP-OES analysis of water samples (all results in mg/L). 33 Table 7: Results of ICP-MS analysis of water samples (all results in mg/L). 33 Table 8: Main minerals identified by XRD for each sample, with sample location description. 38 Table 9: Soil quality standards of the EU. 41 Table 10: Samples with element concentrations above the TWQR, indicating driving force and health impacts. 46 Table 11: PHREEQU equilibrium calculations assuming a calcite-dolomite carbonate rock

for different values of P reflecting the common range in natural surface water. 46 CO2

Table 12: Primary and secondary minerals found at the ELM with associated source and solubility products. 49 Table 13: Plants recommended for remediation of metal-contaminated soil, namely zinc, copper and lead, indigenous status for South Africa and climate suitability of indigenous species for study area. 55 Table 14: Lead concentrations in water and associated human health effects. 65 Table 15: Average BLL in various countries/cities. 66

Chapter 1

Introduction

Mining is an essential contributor to the South African economy along with manufacturing and agriculture. South Africa is a world leader in mining and is internationally renowned for an abundance of mineral resources, accounting for a significant proportion of both world production and reserves. South Africa is the world’s biggest producer of gold, platinum, manganese, vanadium and chromium (Department of Trade and Industry, 2006). Although South Africa’s mining industry is well over a century old, the country still holds many diverse mineral resources that will be available for decades to come. Due to the growth of South Africa’s secondary and tertiary industries as well as a decline in gold production, mining’s contribution to South Africa’s gross domestic product (GDP) has declined over the past decade (Department of Trade and Industry, 2006). However, this may be compensated for by an increase in the beneficiated minerals industry, which provides lucrative opportunities, such as adding value locally to iron, carbon steel, stainless steel, aluminium, platinum group metals and gold. South Africa’s mining industry is continually expanding and adapting to changing local and international conditions; it remains a cornerstone of the economy, making a significant contribution to economic activity, job creation and foreign exchange earnings (Department of Trade and Industry, 2006).

Mining and mineral processing have a severe impact on the environment. South Africa’s environmental legislation has only been in place since 1989 with the promulgation of the Environmental Conservation Act No. 73 (ECA). This legislation was the first to require an Environmental Impact Assessment (EIA) for certain activities that were considered detrimental to the environment, including mining. The ECA has since been repealed and replaced by the National Environmental Management Act 107 of 1998 (NEMA), which forms the overarching legislation for environmental issues in South Africa. The EIA legislation in the ECA was repealed and replaced by regulations 385, 386 and 387 of NEMA on the 1st of July 2006. These new regulations specify the EIA procedures (reg. 385) as well as the listed activities requiring a basic (reg. 386) and a full EIA (reg. 387). The EIA legislation pertaining specifically to mining is due to be promulgated in 2007. Current environmental control falls largely under the Minerals and Petroleum Resources Development Act 28 of 2002 and the National Water Act 36 of 1998.

Due to South Africa’s prolific mining industry there are numerous old mines that have been decommissioned. Many of these mines were closed or simply abandoned before the introduction of environmental legislation, in the National Environmental Management Act, that requires mitigation of the affected area once a mine has been decommissioned. Consequently, many old mining and processing sites have not undergone any form of remediation and the environment continues to be polluted. The fact that studies of lead concentrations in airborne dust by the Council of Geoscience found hotspots of high lead levels around abandoned lead mines proves to illustrate this danger (Cloete, 2006).

This study focuses on such a lead mine, namely the Edendale Lead Mine in Tshwane, Gauteng Province, South Africa. Due to the hazardous nature of lead, the abandonment of similar mines without any form of mitigation is of particular concern. In this case the primary fear is the influence of the old mine on the environment and on the local population. The mine site boarders on a small stream, namely the Edendalespruit, and there are two schools in the area, the Edendale Primary and High Schools, as well as numerous local farmers and some private residences that utilise the local groundwater resources from boreholes. The objective of this study is an assessment of the level of threat that the Edendale Lead Mine poses to the local people and to the environment.

Chapter 2

Statement of the problem

The aim of this study is to determine the source as well as the extent and magnitude of metal contamination at the Edendale Lead Mine (ELM) site, with regards to water quality and soil contamination levels. Results are benchmarked against national and international regulatory frameworks to access the severity associated with the observed levels of pollution.

Metal pollution is one of the most serious environmental problems resulting from human activities, such as mining and smelting of metalliferous ores, electroplating, gas exhaust, fertiliser and pesticide application (Alkorta et al., 2004). Metals are pollutants of great concern due to their immutable nature. Within a certain range of concentrations metals are essential for the functioning of biological systems but at higher concentrations they can be detrimental by blocking essential functioning groups, displacing other ions or modifying the active conformation of biological molecules. Metal-related pollution has recently attracted considerable public attention since the magnitude of the problem calls for immediate action (Alkorta et al., 2004).

This study is significant due to the harmful effects of lead and other heavy metals to human health and the environment. According to the Target Water Quality Range (TWQR) lead concentrations in water should be less than 10 µg/L (DWAF, 1996) and Blood Lead Levels (BLL) according to Centre for Disease Control and Prevention should be less than 10 µg/dl. Exposure levels greater than these can lead to behavioural problems as well as neurological impairment in humans. Sensitive groups, such as young children and fetuses, are able to absorb more lead from the environment and are, therefore, at a higher risk (DWAF, 1996).

In the area of the ELM there are various farms with boreholes, as well as the Edendale Primary and Edendale High Schools neighbouring the former mine site. These people are at risk should the lead concentrations be higher than recommended levels. The Edendalespruit flows directly below the mine site and any contamination as a result of the mine waste will be transferred to downstream users, such as the two schools and local livestock. The ELM is not cordoned off, therefore, any humans and animals in the area may be directly exposed to lead and other heavy metals in the soil and natural water sources.

In order to address the problem of this study, the following approach has been taken: • Describe the study area: using previous literature, including a basic overview of the geology of the area around the ELM, its history, location and physical environment of the mine site as well as the lead smelting process used to extract the lead and any resultant contaminants. • Characterise the ore body: in terms of its geological setting and style of mineralisation, specifically the hosts of lead and other heavy metals, using field observations, light microscopy, scanning electron microscope (SEM) and microprobe analysis. • Determine data required and collection of data: data required includes water and solid samples from the mine site and surrounding areas as well as water samples from two different seasons, namely the rainy and dry season, to establish seasonal changes. • Analyse water samples: using Ion Chromatography analysis, Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). • Analyse solid samples: using X-Ray Diffraction (XRD) and X-Ray Fluorescence Spectrometry (XRF) for mineralogy and trace elements. • Evaluate data: in order to determine the magnitude and extent of lead contamination in the area. • Recommendations: including any possible mitigation measures.

Chapter 3

Description of study area

3.1 Geological background and study area

The study area is located in the Silverton Formation of the Pretoria Group that forms part of the Transvaal Supergroup of South Africa (Figure 1). The Transvaal Supergroup formed between 2.67 and 2.07 billion years ago. It is an extraordinary well preserved cratonic cover succession and is found over an area of at least 500 000 km2 (Coetzee, 2001). The Transvaal Supergroup is predominantly composed of siliciclastic and chemical sedimentary rocks with subordinate volcanic rocks. There are three main outcrop regions, namely the Transvaal and Griqualand West regions in South Africa (Figure 1) and the Kanye area in Botswana (Coetzee, 2001).

Figure 1: Distribution of the Transvaal Supergroup in South Africa (Coetzee, 2001).

The study area falls within the Transvaal outcrop region. It is located to the northeast of the city of Tshwane, within the Silverton Formation of the Pretoria Group (indicated by the red dot on Figure 2). The Pretoria Group is predominantly composed of quartzite and shale together with a prominent volcanic unit, the Hekpoort Formation. Numerous diabase and other basic sills intrude at various levels in the Pretoria Group (SACS, 1980).

Tshwane

Figure 2: Outcrop of the Transvaal Supergroup in the Transvaal area (adapted from Coetzee, 2001).

The Silverton Formation is a thick succession of shales of the Pretoria Group in the Transvaal region. It is conformably under- and overlain by shallow marine quartzites of the Daspoort Formation and Magaliesberg Formation, respectively (Button, 1973). The Silverton Formation rests with sharp conformable contact on the Daspoort Formation. It consists of carbonaceous black shale or siltstone, a basaltic lava unit (Machadodorp Lava) and minor carbonate beds towards the top of the Formation (Figure 3). The Silverton Formation grades upward into the Magaliesberg Formation, which is composed of fine- to medium-grained quartzite and orthoquartzite, and is the youngest preserved stratigraphic unit of the Pretoria Group in the western Transvaal area (Coetzee, 2001). The age of the Pretoria Group is 2100Ma to 2400Ma and the Silverton Formation is older than 2100Ma, but younger than 2160Ma (Coetzee, 2001).

Two thick units of carbonaceous shale and siltstone make up the Silverton Formation. These units are locally separated by a basaltic lava unit that is called the Machadodorp Lava in the eastern Transvaal. The Silverton Formation contains upwards coarsening and upwards fining lithofacies successions below the Machadodorp Lava (Coetzee, 2001). These upward coarsening lithofacies successions consist of black shale at the base and grade upwards into grey siltstone. The fining upwards successions have fine-grained quartzite with contorted bedding at the base grading upwards into black shale. The upper two fining upward units contain carbonate concretions and have clay-pellet conglomerates at the base of the quartzites (Coetzee, 2001). The Silverton Formation above the Machadodorp Lava is composed of a stack of upwards coarsening lithofacies successions (20-60 meters thick) of carbonaceous shale and siltstone with numerous calcite concretions that show a typical brown colour due to weathering (Coetzee, 2001) (Figure 3). The carbonate unit near the top of the Silverton Formation is situated immediately below the Magaliesberg quartzite and consists mainly of limestone with minor dolomite. The carbonate beds are found to be partly silicified (Swart, 1999). The Silverton Formation is overlain by the white, mature orthoquartzite of the Magaliesberg Formation with sharp gradational contact (Coetzee, 2001).

Figure 3: Lithostratigraphy of the upper part of the Silverton Formation (adapted from Coetzee, 2001).

Within the study area the sedimentary rocks of the Silverton Formation are intruded by dolerite sills of unknown age but possibly related to the Bushveld Igneous Complex. Deformation and contact metamorphism in the area could, therefore, be due to the intrusion of the Bushveld Complex of 2061 ± 27Ma (Coetzee, 2001). Lead mineralisation is controlled by east-west striking normal faults of unknown age. A model age obtained for galena from the vein at the Edendale Lead Mine suggests a Bushveld age to the mineralisation (Coetzee, 2006).

3.2 Edendale lead mine 3.2.1 Location and history

The Edendale Lead Mine (ELM) is located on the farm Nooitgedagt 333 JR. in Silverton, Tshwane East. Figure 4 indicates the locality of the mine and the geology of the immediate region, where the ELM occurs within part of the Silverton Formation. The two shafts mined are shown on the geological map, separated by the main road (R513), the approximate location of the hydrothermal deposit exploited is also indicated on the map. The ELM was one of the earliest mines in the Transvaal region and produced fair quantities of lead and some silver in the 1890’s from a vein containing argentiferous (containing silver) galena and some sphalerite (Russell, 1940).

Figure 4: Geological map of the study area; indicating the old Edendale and Union Mines, Edendale mine shafts, and the approximate location of the mineralised vein at the Edendale Lead Mine (modified after Geological Map of South Africa, Council for Geoscience, 1973).

The Edendale lead deposit was known and exploited prior to 1900, but its presence was for the first time indicated on a map in the Annual Report of the Geological Survey of 1903. The deposit was exploited from two vertical shafts of unknown final depth (Russell, 1940). The style and nature of mineralisation encountered has never been documented in any significant detail. The vein exploited at the first shaft yielded the ore minerals galena and sphalerite, with chalcopyrite appearing at depth. The second shaft, less than a kilometre southwest of the first, exploited the same vein with galena, small amounts of sphalerite and also pyrite (Jansen, 1977). There is limited information concerning the actual output from the deposit in relation to the production of lead, silver and sphalerite (Table 1) (Russell, 1940).

Table 1: The total marketable output of shaft one (Russell, 1940). Mineral/element Output (metric tons) Lead 5 560.7 Sphalerite 207.1 Silver 0.553

ELM production was quite prolific from 1904 to 1909 and then decreased until mining ceased in 1938 (Figure 5). The mine predominantly produced lead while it was in operation but fair quantities of silver were also mined from 1907 till 1912; the greatest production being in 1908 with 0.23 tons of silver being produced (Russell, 1940).

Lead and Silver Production at Edendale Lead Mine (1904-1938)

1080

900

720

540 Lead 360 Silver

180 Lead (tons) and (10 ozs) Silver 0 1904 1909 1914 1919 1924 1929 1934 Year

Figure 5: Annual output of lead and silver from the ELM, 1904-1938 (adapted from Russell, 1940).

3.2.2 Climate, vegetation and hydrology

The rainfall of the study area varies between 625 and 750 mm per annum (Kgwakgwe, 2001). Vegetation along the quartz ridges of the Pretoria Group includes the sugarbush (Protea caffra), withering, bergpruim and moepel. On the soils derived from basic rocks, lava and argillaceous sediments, the vegetation consists of kareeboom, soetdoring and Acacia arabica. The vegetation along the foot of the Magliesberg includes wild-fig, wild olive, kiepersol, marula and moepel (Kgwakgwe, 2001).

The Edendalespruit that runs through the area rises south of the farm Franspoert and passes through a gap in the Magaliesberg quartzites, then through a narrow gap in the Leeuwfontein quartzites (Kgwakgwe, 2001). The Edendalespruit drains into the south eastern part of the Roodeplaat dam. The Roodeplaat Dam is situated north-east of Tshwane at the confluence of the Pienaars River, the Moreleta/Hartbees River and the Edendalespruit. The Roodeplaat Dam is considered hyper-eutrophic due to various nutrient inputs from the catchment, especially two Water Care Works that service the formal residential areas and industries in the area; diffuse sources include extensive agricultural feedlots and informal settlements (DWAF, 2000).

3.2.3 Geological features and history

The deposit exploited at the ELM occurs in the Silverton Formation of the Pretoria Group that was intruded by dolerite sills, probably related to the Bushveld Complex (Coetzee, 2006). The intrusion of the Bushveld Igneous Complex most likely resulted in the deformation that created the faults in the area, which host the lead mineralisation at the ELM. Later syenite intrusions from the Leeuwfontein complex occurred at about 1.4 – 1.3Ga. (Hanson et al., 2004). The study area is now covered by recent deposits of Cenozoic age that obscure any outcrops (Figure 4).

The main geological features of the study area are two quartzite ridges that demarcate the southwest and northeast boundaries (Figure 4 and Figure 12). These and other less prominent ridges of the Magaliesberg formation are composed almost entirely of quartzite with minor intercalations of limestone and shale (Russell, 1940).

Generally, these rocks strike southeast-northwest and dip approximately 20° northeast; but there are some variations in the amount and direction of dip further north of shaft one due to diabase intrusions (Russell, 1940). As previously mentioned, the Silverton Formation contains minor carbonate beds towards the top of the formation (Figure 3) (Coetzee, 2001). These are seen in the ELM area as a limestone band that is approximately three metres thick (Kgwakgwe, 2001). No appreciable enrichment of galena was found at the junction of the limestone and the mineralised zone (Russell, 1940).

The ore itself occurs within a quartz-vein that crosscuts the Silverton Formation, which developed along a set of east-west trending faults (Jansen, 1977). The vein measures up to two metres wide and dips 60° to 85° south. It trends true east along a fault and can be traced for almost 1170 meters (Kgwakgwe, 2001). At the surface the vein varies in thickness from 1 – 1.5 metres, but considerable variations in vein thickness were observed at depth (Russell, 1940). Slickensides found indicate a westward movement on the north side of the fault (Jansen, 1977).

Galena was exploited from two main shafts. Galena mineralisation was concentrated in small randomly distributed pockets that appeared to dip towards the east. The origin of the mineralisation is uncertain, but it crosscuts, i.e. postdates, the diabase sills (Russell, 1940). Lead isotopes ratios of galena from the ELM suggest a connection with the intrusion of the Bushveld Complex (Coetzee, 2006).

3.2.4 Ore mineralogy and petrology of the ELM

Lead mineralisation that was exploited at the ELM is discussed in terms of field observations, light microscopy, SEM and microprobe work. This has been done in order to provide a suitable framework for the arrangement of the potential environmental impacts of this historical mining operation. In particular, a detailed understanding of the nature, distribution, abundance and association of ore and gangue minerals is required as this will determine the availability and concentrations of potentially toxic elements to the environment, such as lead and other heavy metals. Mining of the ELM focused on lead, but reasonable amounts of silver were also exploited (Figure 5) (Kgwakgwe, 2001).

The silver content of the ore was concentrated in thin films, probably consisting of secondary argentite with surrounding galena grains (Jansen, 1977). It was found during this study that lead concentrations are of greatest environmental concern due to the toxic nature of lead and the high concentrations in the area.

• Methodology In order to characterise the lead mineralisation, hand samples were collected from dumps and remnant ore stock piles during numerous site visits. Some of these samples were cut and polished for mesoscopic textural descriptions; others were used for the preparation of polished sections and polished thin sections for light microscopy, SEM and microprobe analysis. Thin sections were studied under reflected and transmitted light to identify and describe the various minerals present. A small part of a thin section was X-ray mapped using the Jeol 5600 SEM for the following elements (Figure 7): arsenic (As), sulphur (S), copper (Cu), lead (Pb), silica (Si) and zinc (Zn). SEM analyses were performed with a load current of 25kV. Before the thin section was studied it was carbon-coated with an Emiscope SC500 carbon coater.

In addition, galena, sphalerite and chalcopyrite were analysed by electron microprobe. Before the thin section was studied it was carbon-coated with an Emiscope SC500 carbon coater. The microprobe was set with the appropriate settings for each mineral (see Appendix I). Six elemental maps were created of a small cluster of sulphides grains and their surrounding area. These maps were created in order to identify any trace mineral phases that had not been identified with the SEM or in hand sample descriptions (for microprobe report see Appendix I)

• Results There are two stages of mineralisation that were identified from material collected from rock dumps at the ELM. Both stages represent the hydrothermal infill of the vein once mined for its lead content. The first stage of mineralisation is best described as an intensively fragmented and strongly silicified tectonic breccia (Figure 6A), referred to as stage one. This silicified breccia contains erratically distributed fragments of strongly silicified host rock next to millimetre- to centimetre-sized angular aggregates of galena. This siliceous stage of mineralisation predates the second stage of mineralisation that is marked by an abundance of carbonate with minor pyrite (Figure 6D).

This carbonate dominated stage is represented in shaft two by a 25 centimetre thick calcite vein that occurs between the galena lobe and the hanging wall. This calcite vein served as a convenient marker for the mineralised zone and the material was collected for the sintering process (Russell, 1940). Clasts of silicified host (stage one mineralisation) occur coated by several generations of iron-rich sparry dolomite and at least one generation of fine-grained pyrite. Renewed brecciation between events of carbonate and pyrite formation is evident. Sparry calcite and some megaquartz fill remaining vugs are lined by sparry dolomite.

Thin sections of stage one siliceous breccia reveal the presence of host rock clasts that are extensively infiltrated and replaced by fine-crystalline quartz. The main mineral phase in the breccia cement is quartz, with minor galena, sphalerite and chalcopyrite; these are clearly associated and co-genetic with the galena (Figure 6B), and trace amounts of chlorite.

Chalcopyrite (CuFeS2) occurs only as microscopic exsolutions within sphalerite (Figure 6C).

B Gangue

A Sphalerite

Galena

Galena 0.24 mm

Quartz C Galena clast Very fine grained chalcedony matrix Chalcopyrite Sphalerite

Gangue 1 cm 0.120.005 mm mm

Carbonate E Pyrite

Quartz D clast Carbonate Quartz

Pyrite 0.48 mm

F Carbonate

Chlorite Pyrite

1 cm Carbonate 0.48 mm Figure 6: A-C: Silicified tectonic breccia, stage one vein infill; A: Hand specimen; B: Galena intergrown with sphalerite (reflected light); C: Exsolutions of chalcopyrite in sphalerite (reflected light); D-F: Carbonate cemented breccia (stage two) D: Hand specimen; E: Quartzite fragment surrounded by carbonate, rimmed with pyrite (transmitted light); F: Chlorite associated with pyrite (transmitted light).

The sparry dolomite of the second stage of mineralisation (Figure 6D) is iron-rich as indicated by its red/brown weathering colour. Silicified host rock clasts are surrounded by several generations of hydrothermal sparry dolomite and single intermittent generations of pyrite forming thin rims (Figure 6E). Bright green chlorite is locally associated with the pyrite rims (Figure 6F).

The Jeol 5600 SEM was used to create elemental X-ray maps from a large aggregate of galena, sphalerite and quartz (Figure 7). The primary aim was to identify any trace mineral phases that had not been identified in hand sample description or by light microscopy.

As BSE image S

Galena Sphalerite

Quartz

Cu Pb Si Zn

Figure 7: Original SEM image of an aggregate of galena, sphalerite and quartz; and elemental X-ray maps for As, S, Cu, Pb, Si and Zn. Higher concentrations of the element mapped shows up as brighter in colour. Note minute grain of chalcopyrite (Cu map).

The elemental X-ray maps indicate expected appearances of S, Pb, Si and Zn (Figure 7). Cu is shown to occur in a small grain of chalcopyrite. The arsenic map shows a reasonably uniform colour over the entire galena grain. Although there are certain areas of a slightly brighter colour, these are likely due to statistical variations in the background concentrations or the influence of pits or holes in the sample. The X-ray maps, therefore, do not conclusively indicate any arsenic-bearing phase. Subsequent electron microprobe analysis identified galena as a host of minor concentrations of arsenic (less than 0.07 weight percent arsenic), see Appendix I.

In a further mapping exercise (Figure 8) the presence of an arsenic-bearing phase was established by microprobe analysis. Additional analysis indicated this phase contained on average 45 weight percent arsenic, 20 weight percent cobalt, 15 weight percent nickel, 19 weight percent sulphur, one weight percent iron and one weight percent antimony (see

Appendix I). The arsenic-bearing mineral, (Co0.55Ni0.42Fe0.03)(As0.99Sb0.01)S, has been identified as an intermediate mineral in a solid substitution series with end members cobaltite (CoAsS) and gersdorffite (NiAsS).

Chlorite

Cobaltite

Quartz

Figure 8: Backscattered-electron image of cobaltite (further data in Appendix I).

• Interpretation Quartzites of the Magaliesberg Formation of the Pretoria Group, intruded by abundant (syn- Bushveld) dolerite sills were affected by east-west directed normal faulting. Tectonic breccias related to such faulting are host to lead-dominated hydrothermal mineralisation of the ELM. Two distinct stages of hydrothermal mineralisation are evident, with the older being the one associated with lead mineralisation in the form of galena. This first stage is marked by strong brecciation and silification and finely disseminated Pb-Zn-Cu-Co sulphides; galena being the only sulphide mineral of significant abundance. Arsenic occurs in minor concentrations in galena (less than 0.07 weight percent) but also forms a separate trace mineral phase, namely cobaltite. The second stage of hydrothermal mineralisation is marked by an abundance of iron-rich dolomite with minor calcite, quartz and chlorite. Usually associated with the latter is pyrite, the only sulphide mineral in this stage of mineralisation.

3.2.5 Lead Smelting Process

• General lead smelting process Lead and zinc can be produced pyrometallurgically or hydrometallurgically, depending on the type of ore. The pyrometallurgical production of lead (Figure 9) is more common and can be subdivided into four processes, namely sintering, smelting or reducing, drossing and refining (WBG, 1998). The process utilised at the ELM was similar, but with some differences that will be discussed later.

Figure 9: A typical primary lead smelting and refining process (Den Hoed, 2006).

1. Sintering The primary purpose of sintering is sulphur reduction of the feed material (Den Hoed, 2006). The feedstock is composed of lead concentrates (pyrite with a high sulphur content and other impurities such as arsenic, antimony and bismuth); limestone and silica (to maintain the desired sulphur content); and high-lead-content sludge by-products from other facilities (Den Hoed, 2006). It may also contain iron, coke, soda ash, zinc and caustic particulates (WBG, 1998). This feedstock is known as green feed, and to this, is added undersized sinter returns recycled from the sinter roast. The green feed and sinter returns are placed in a rotary pelletising drum where a water spray is added to enhance nodule formation. Sinter return nodules have a lead oxide rich core and green feed nodules are coated in lead sulphide. Smaller nodules are separated and conveyed through an ignition furnace. They are then covered with the remaining nodules and are conveyed to the sinter machine, which is essentially a large oven (Den Hoed, 2006).

Air is forced up through a grate, facilitating combustion, releasing sulphur dioxide and oxidising lead sulphide into lead oxide. ‘Strong gas’ from the front of the sinter (containing 2.5-4 percent sulphur dioxide) is vented to gas cleaning equipment and then can be piped to a sulphuric acid plant. Gasses from the rear of the sinter are re-circulated through a moving grate and vented into a bag-house, which is a fabric filter used to remove undesirable constituents from gas emissions (Den Hoed, 2006).

Any undersized produce, generally due to insufficient desulphurisation, is filtered out and recycled through the sinter. The remaining sinter roast is crushed, coke is added and it is transported to the blast furnace, which is primarily used for reduction and smelting (Den Hoed, 2006).

2. Smelting or reduction Sinter roast is combined with coke, ores containing high amounts of precious metals, slags, by-products dusts from other smelters and by-products from bag-houses, as well as various other sources in the facility. Iron scrap is added to assist with heat distribution and to combine with the arsenic in the feed (Den Hoed, 2006). The process rate of the blast furnace is controlled by the proportion of coke in the feed and by the air flow through the tuyeres, i.e. openings, in the floor of the furnace. The feed descends through the furnace shaft into the smelting zone where it becomes molten and is tapped off into a series of settlers that allow the separation of lead from slag. The slag cools and is stored. The molten lead, approximately 85 percent purity, is transported to the dross building (Den Hoed, 2006).

In the blast furnace carbon acts as a fuel and smelts the material. Four layers form in the blast furnace, namely (WBG, 1998): a. Speiss, this is the lightest material, consisting of arsenic and antimony. This is usually sold to copper smelters. b. Matte, mainly copper sulphides and metal sulphides, which is also sold to copper smelters with the speiss. c. Blast furnace slag, primarily silicates, such as zinc, iron, silica and calcium. This is stored in piles and can be partially recycled. d. Lead bullion, with approximately 98 weight percent lead content.

3. Drossing Here the lead bullion is agitated in a drossing kettle and is cooled to just above melting point (370˚-425˚C). A dross is added, which consists of lead oxide, copper, antimony and other materials. This floats to the top and is removed and sent to the dross furnace where non-lead valuable minerals are recovered (WBG, 1998).

The drossing area is made up of a variety of interconnected kettles, which are heated from below using natural gas combustion. The charge from the blast furnace is poured into receiving kettles and allowed to cool until the copper dross rises to the top and can be skimmed off and transferred to a reverbatory furnace (Den Hoed, 2006). The remaining lead dross is sent to a finishing kettle where materials like wood chips, coke fines and sulphur are added to further facilitate separation. This sulphur dross is skimmed off and transferred to the reverbatory furnace. Tetrahedrite ore (which has a high silver content but a low lead content), coke fines and soda ash are added to the drosses in the reverbatory furnace. The dross in the reverbatory furnace is heated and it separates into three layers, namely the lead bullion at the bottom, which is tapped back into the kettles, then the matte and the speiss at the top (Den Hoed, 2006).

4. Refining Refining is conducted in cast iron kettles and occurs in five stages (EPA, 1995; WBG, 1998; Den Hoed, 2006): a. Antimony, tin and arsenic are removed. b. Gold and silver are removed by adding zinc (Parke’s Process, where zinc combines with gold and silver to form an insoluble intermetallic compound at opening temperatures) c. Vacuum removal (distillation) of zinc. d. Calcium and magnesium are added to form an insoluble compound with bismuth, which is removed (Betterson Process).

e. Caustic soda and/or nitrates (NaOH and NaNO3) are added to remove any trace metal impurities.

The lead bullion that is left has a purity of approximately 99.90 – 99.99 percent (EPA, 1995; WBG, 1998). The lead smelting process produces various pollutants in the form of wastes and air emissions (Table 2) (EPA, 1995).

Table 2: Process materials inputs and pollution outputs for lead smelting and refining (adapted from EPA, 1995). Process Material input Air emissions Process wastes Other wastes Lead ore, iron, silica, Sulphur dioxide limestone flux, coke, particulate matter Lead sintering soda ash, pyrite, zinc, containing cadmium caustic, baghouse dust and lead Sulphur dioxide Slag containing such Plant washdown particulate matter as zinc, iron, silica Lead smelting Lead sinter, coke wastewater, slag containing cadmium and lime surface granulation water and lead impoundment solids Slag containing Lead bullion, soda ash, impurities such as Lead drossing sulphur, baghouse dust, zinc, iron, silica and coke lime. Surface impoundment solids Lead refining Lead drossing bullion

• Lead smelting process at Edendale Lead Mine The lead smelting process at ELM (Figure 11) ran a sintering plant consisting of six small pots, which were originally cocopans, and a reverberatory furnace; together they had a capacity of 2.5 tons per day (Russell, 1940). Primary lead production usually begins with sintering, which is a process where solid wastes are combined into a porous mass that can then be added to the blast furnace. The general process includes concentrated lead ore fed into a sintering machine with iron, silica, limestone fluxes, coke, soda ash, pyrite, zinc, caustics or pollution control particulates. This mixture is then roasted with hot air to burn off the sulphur

(SOx) and is then finally sent to the smelter. Air emissions from a sintering plant include sulphur (SOx) and particulates (North Carolina Department of Environment and Natural Resources, 2006). Presumably these air emissions would have been similarly eliminated at the ELM, since the process included a blast furnace.

A reverberatory furnace (Figure 10) is a metallurgical or process furnace, which characteristically isolates the material being processed from contact with the fuel but not from contact with the combustion gases (North Carolina Department of Environment and Natural Resources, 2006). Reverberatory furnaces are designed and operated to produce a soft, nearly pure lead product. Reverberatory furnaces emit high levels of lead fumes during the processes of charging and tapping the lead and slag (USDL, 2006).

Figure 10: Schematic cross section through a reverberatory furnace (USDL, 2006).

For the lead smelting process at ELM (Figure 11) the reverberatory, or open-hearth furnace, was initially constructed for smelting but proved a failure and was from then on used for sintering. The blast furnace used was of the type usually employed in the smelting of galena concentrates. The silver was recovered from the slags using amalgamation. The original cocopans were fitted with a lid, chimney, grid to cover the coal, coke for desulphurising and an aperture at the bottom for the blast, in order to use them for sintering (Russell, 1940). The feedstock for the sintering machine (Figure 11) consisted of limestone, to increase the pH and for the calcium to bind with unwanted metals that would float to the surface and be removed as slag. Iron ore was also added as well as fluorite, as a flux to reduce the melting temperature (Russell, 1940). There was no mention of a pelletising drum being used at Edendale and gases were most properly simply released through stacks as no gas cleaning equipment is referred to by Russell (1940).

The sintered material was then run up a steep incline to the top of the blast furnace and tipped in. The addition of coke to the sintering roast is not mentioned during the Edendale process but iron ore was added in the initial feedstock for the sintering process. This iron could have aided heat distribution and combined with the arsenic. Smelting at Edendale was done using a reverberatory furnace where the slag rose to the top and was tapped off and the lead concentrate was tapped off the bottom of the furnace (Figure 10). This slag would have contained high concentrations of arsenic, antimony, copper sulphides, metal sulphides and silicates (Russell, 1940).

Ore (hand sorted)

Crusher

Dump Concentrator (>2 cm) (<2 cm)

Dump Sinter Pots (light material) (heavy material)

Add limestone, iron ore and fluorite

Slag Blast Furnace

Lead/Silver

Figure 11: Process of lead smelting at ELM (adapted from Russell, 1940).

• Sources of pollution or contamination during lead smelting The major hazards of lead smelting are exposure to the ore dusts during ore processing and smelting, metal fumes (including lead, arsenic and antimony) during smelting; sulphur dioxide and carbon monoxide during most smelting operations; noise from grinding and crushing operations and from furnaces; as well as heat stress from the furnaces (EPA, 1995). Nearly every process and process component within primary lead smelting can result in emission of lead and particulate in varying amounts. Sulphur dioxide is also emitted from numerous sources (Den Hoed, 2006).

Air pollutants from the lead smelting process primarily consist of particulate matter and sulphur dioxide. Fugitive emissions are released from furnace openings, lauders, casting moulds, ladles carrying molten material, materials handling, and transport of ores and concentrates. Particulate matter is principally lead or zinc and iron oxides but can include oxides of arsenic, antimony, cadmium, copper, mercury and metallic sulphides (WBG, 1998).

The dust from handling raw materials is composed of metals, mainly sulphides but chlorides and fluorides may be present. Off-gases contain fine dust particles and volatile impurities like arsenic, fluorine and mercury. The presence of metals in vapour form is temperature dependent. Leaching processes will generate acid vapours, whereas refining processes result in products of incomplete combustion (PICs). Emissions of arsenic, chlorine and hydrogen chloride vapours and acid mists are associated with electrorefining (WBG, 1998). The air emissions expected for a process with few controls, as would have been the case for Edendale Lead Mine, would be 30 kilograms lead or zinc per metric ton of lead or zinc produced (WBG, 1998). Based on known production figures (Table 1), shaft one from the ELM would have produced 167 metric tons of air emissions over its lifespan.

Water pollution associated with lead smelting is generated in the form of waste-water from wet air scrubbers and cooling waters. Scrubber effluent contains lead, zinc, arsenic and other metals. Waste-water sources include spent electrolytic baths, slimes recovery, spent acid from hydrometallurgy processes, cooling water, air scrubbers, wash downs and storm-water. Pollutants or contaminants in these waste-waters include dissolved and suspended solids, metals, oil and grease (WBG, 1998). At the ELM effluent is likely to have been released directly into the natural water sources in the area, namely the Edendalespruit and groundwater sources.

Solid waste is mainly the slag from the smelter. This slag may contain 0.5 – 0.7 percent lead or zinc, which could be used as fill or for sandblasting, where the slag contains up to 15 percent lead or zinc it can be sent for metal recovery. Leaching processes result in residues, while effluent treatment results in sludges that require appropriate disposal. The smelting process typically produces less than three tons of solid waste per ton of lead or zinc produced (WBG, 1998). Thus, ELM would have produced at least 16 681 metric tons of solid waste from shaft one throughout its lifespan (Table 1).

Lead is the most toxic or problematic contaminant resulting from the lead smelting process, therefore, lead is further studied according to its occurrence and health effects, as can be seen in Appendix II.

Chapter 4

Data collection and methodology

4.1 Data collection 4.1.1 Data required

In order to determine the metal contamination at ELM and the surrounding area, 16 water and 16 solid samples were taken from various sample localities (Figure 12). For this study a typical judgemental sampling procedure was utilised. Samples were taken of different macro- environments that were recognisable in the field, namely the waste rock dump and the old plant site. Focus was placed on the immediate area around the ELM to identify potential contamination of the natural environment.

Solid samples were taken from around the mine site, specifically from around the waste rock heap and from the area of the old plant site as these were felt to be the most contaminated. Some solid samples were taken of the soils around ELM to determine the extent of lead contamination. Water samples were collected form the Edendalespruit below the mine site and from the surrounding area to provide a broader overview of contamination. The solid samples can be divided into three groups according to type of material sampled; group one: soil samples, group two: waste rock dump material and group three: slag heap material. According to the geological map of the region (Figure 4) the soil samples were taken from areas with soil, sand, gravel, scree, ferricrete and silicrete and all samples were collected from areas underlain by the Silverton Formation (Figure 2). These samples are of medium-grained sandy topsoil. Group two samples from the waste rock dump and the area around the waste rock dump consisted of some material from the waste rock dump itself and soil directly around the waste rock dump. The third group is material from the old plant site, namely the slag material from the lead smelting process.

Water samples were taken at two different times of the year, specifically at the end of the rainy season (22 May 2006) and in the dry season (29 August 2006). Sample names starting with R represent rainy season and N refers to samples taken in the dry season. W represents water samples and S solid samples, where solid samples were only collected in the rainy season.

Map coordinates were taken for each of the samples using a hand held Global Positioning System (GPS). These coordinates are listed in Appendix III.

At ELM, shaft one and two are separated by the main road, the R513, where shaft one is located to the east of the waste rock dump and shaft two is west of the old plant site (Figure 12A). There are two main quartzite ridges on either side of the mine, of the Magaliesberg Formation, and the Edendalespruit runs directly south of the mine site, flowing in a south- easterly direction. Downstream of the ELM are two schools located alongside the Edendalespruit, namely the Edendale Primary and High Schools. There are no building structures left on the old plant site; only some ruins of what used to be the plant and the slag heap with mine tailings (Figure 13B and 13C).

B C

Figure 12: A: Image of study area, indicating main features; B: Sample points near shaft one (red block on A); C: Sample points near shaft two (blue block on A) (Google Earth, 2006 http://earth.google.com).

Samples collected from shaft one and the surrounding area are indicated by the red block on Figure 12A, enlarged to Figure 12B. Sample NW1 was collected from shaft one and samples RS3, RS4, RS5, RS6 and RS7 were collected from the waste rock dump. The vegetation in the area around the ELM is overgrown, although there are some areas with no vegetation, these can be seen as the white and grey regions on the figure; note the old plant site (note Figure 12C). The waste rock dump (note Figure 12B) is predominantly gravel and fragmented rock, with no soil cover. Sample RW1 was taken from a pit near to shaft one and sample RS8 was of soil further away from the shaft where the vegetation was overgrown. The later sample is a sample of soil, comparable to samples RS1, RS2 and RS9.

Samples taken from the area surrounding shaft two are indicated by the blue block on Figure 12A, enlarged to Figure 12C. The old mine site is characterised by the absence of vegetation and an abundance of white precipitate covering the slag material (Figure 13D). Samples RW7 and NW2 were collected from shaft two and samples RS10-RS16 from the old plant site (slag material). As can be seen from Figure 12C the Edendalespruit flows directly below the mine site, and samples RW10 and RW3 were taken from the Edendalespruit.

For each sample, brief locality descriptions are provided in Table 3. Photographs were also taken during site visits (Figure 13). Figure 13A is a photograph of the waste rock dump near shaft one (samples RS1, RS2, RS8 and RS9). Figure 13B and 13C illustrate what is left of the old plant site, i.e. some foundations as well as the slag heap (samples RS10-RS16). There are no structures left documenting the processes used for lead smelting. A white precipitate covers some of the slag material, seen in Figure 13D (samples RS12 and RS16). The slag heap (Figure 13E and 13F) at the old plant site shows evidence for the formation of encrustations, seen in Figure 13E (sample RS15). Figure 13F shows malleable metallic material, probably lead metal, found on the slag heap, which formed as a by-product of the smelting process (sample RS14).

Table 3: Sample names and locality descriptions (for GPS coordinates see Appendix III). Sample Sample Description Sample Sample Description Northern side of the R513 (area near shaft one) RS1 Soil (medium-grained sandy topsoil) RW1 Pit near shaft one RS2 Soil (medium-grained sandy topsoil) NW1 Shaft one RS8 Soil (medium-grained sandy topsoil) RS9 Soil (medium-grained sandy topsoil) RS3 Waste dump material (waste rock) RS4 Waste dump material (waste rock) RS5 Waste dump material (waste rock) RS6 Waste dump material (white soil around waste dump) RS7 Waste dump material (white soil around waste dump) Southern side of the R513 (area near shaft two) RS10 Slag material (white Pb precipitate) RW2 Edendale High School borehole RS11 Slag material (grey soil) RW3 Edendale High School borehole RS12 Slag material (white precipitate on grey soil) NW5 Edendale High School borehole RS13 Slag material (grey soil) RW4 Edendale High School fountain RS14 Slag material (malleable metal pieces) NW4 Edendale High School fountain RS15 Slag material (encrustations) RW6 Edendale Primary School borehole RS16 Slag material (white precipitate on grey soil) NW6 Edendale Primary School borehole RW7 Shaft two NW2 Shaft two Edendalespruit down slope from mine RW10 plant site Edendalespruit down slope from mine NW3 plant site Edendalespruit before mine (upstream, RW8 bridge over R513) Edendalespruit before mine (upstream, NW8 bridge over R513) Residential home borehole 700 m from NW7 mine

A B C

D E F

Figure 13: Photographs of Edendale Lead Mine, A. Waste rock dump; B: Plant site; C: Plant site; D: White precipitate on rocks at plant site; E: Encrustations in and on slag heap; F: Encrustations and malleable metallic material of slag heap.

4.1.2 Sample collection procedures

Solid samples were collected by scooping sample material from different areas into plastic sample bags, which were clearly labelled and a brief description of the sample locality noted (Table 3). For water sampling plastic bottles were used that were first thoroughly cleaned out with deionised water. Where a stream was being sampled the bottle was placed in running water, the bottle washed out and a final sample collected. Borehole water samples from the two schools in the area were collected from taps, again the bottles were rinsed with the tap water before the final sample was taken. When collecting water from pits or shafts, the bottles were weighted, attached to a rope and lowered into the pit, the water collected, washed out and a final sample taken. All sample bottles were labelled and a site description taken (Table 3). The water sample bottles were refrigerated to prevent biological processes from changing the water chemistry. A hand held GPS was used to obtain coordinates for each sample locality so they could be accurately plotted on a map and further samples could be taken from the same site if required (Appendix III).

4.2 Analytical methodology 4.2.1 Water samples

Once the water samples were collected they were filtered at Chemistry Department at the University of Johannesburg on the same day that they were collected. Filtering occurred by forcing the sample water through 0.45 μm cellulose-acetate paper using a syringe, thus removing solid particles from the water. The samples were then divided in half; one half was acidified with nitric acid to ensure all components remain in solution. This was done by adding 1 – 1.5 millilitre of supra-pure nitric acid to each sample depending on the amount of sample. The other half of the sample was not acidified to allow for the pH to be determined and the anions concentrations to be measured. Cation concentrations were measured using the acidified water samples.

The acidified and non-acidified water samples were analysed by the Chemistry Department. Ion chromatography and Inductively Coupled Plasma- Optical Emissions Spectrometry (ICP- OES) analysis was used to determine element concentrations.

The pH of the non-acidified samples was also measured at the Chemistry Department. Before measuring the pH of the water samples the pH meter was calibrated using two separate buffers (the first at a pH of 6.88 and the second 9.18) and the samples were allowed to equilibrate at room temperature. The acidified water samples were sent to the Council for Geoscience for Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) analysis to measure the concentrations of lead and arsenic.

4.2.2 Solid samples

All solid samples were milled into a powder of analytical fineness using a chrome-steel vibrating disc mill, except sample RS14, representing malleable metal pieces from the plant site (Figure 13F). There was no standard against which to analyse sample RS14, therefore, this sample was not processed. To avoid contamination between samples the mill components were washed and dried with acetone and cleaned with quartz sand after every sample. The powder was then used in preparing powder pellets and pressed powder pellets to be analysed by XRD and XRF, respectively.

X-ray Powder Diffraction is an analytical technique used to semi-quantitatively identify unknown crystalline phases within a powder sample (Perks, 2004). Powder pellets were prepared with the back loading technique. XRD analysis was carried out using a Panalytical X’Pert Pro automated diffractometer, at the following settings. The Panalytical software package HighScore Plus was used to identify mineral phases present.

Tube anode material Cu Generation settings 45kV, 45mA Wavelength Kα1 1.54060Å Wavelength Kα2 1.54443Å Intensity ratio I Kα1/I Kα2 2 Divergence slit size 0.5° Detector diaphragm 0.1mm Angle range 4° – 80° 2Ө Scan type continuous Step size 0.02 2Ө Scan rate 51s per step Spinning yes

X-ray Fluorescence Spectrometry is a non-destructive technique used to identify and quantify the concentrations of chemical elements within solid and liquid samples. The sample is bombarded with X-rays of high energy, which causes the emission of fluorescent X-rays from elements present in the sample.

The elements within the sample are identified by characteristic wavelengths of the emitted X- rays, which are compared to the wavelength peaks of standards with known composition (Perks, 2004).

The pressed powder pellets for this study were prepared by mixing the sample powder with an adhesive component (Herzog Binder was used during this study, 90 percent cellulose and 10 percent wax) and pressed within an aluminium tin with a hydraulic press. Eight grams of sample were mixed with four grams of binder. The advantage of using pressed powder pellets in the analysis is that there is little dilution of the sample; it has good detection limits and is a simple and fast method of sample preparation. During this study the MagiX Pro XRF was used. The software used to identify the different elements was Panalytical Super Q.

4.3 Results 4.3.1. Water samples

The pH determined for each of the water samples is listed in Table 4. Most of the samples have near neutral pH (Table 4), except sample RW4 collected at a natural fountain upstream of the Edendale High School, which is more acidic than the other samples. The pH according to the Target Water Quality Range (TWQR) for domestic water is between 6 and 9, see Appendix IV (DWAF, 1996), therefore, none of the samples indicate a serious problem with regards to water pH in the area, with the exception of sample RW4, which is more acidic than the recommended limits.

Table 4: pH readings from water samples (for GPS coordinates see Appendix III). Sample (rainy season) pH Sample (dry season) pH RW1 (pit near S1) 6.56 NW1 (S1) 8.03 RW2_3 (EHS BH) 7.20 NW5 (EHS BH) 6.95 RW4 (EHS fountain) 5.28 NW4 (EHS fountain) 6.89 RW6 (EPS BH) 7.43 NW6 (EPS BH) 7.07 RW7 (S2) 6.77 NW2 (S2) 7.34 RW8 (ES under bridge) 7.49 NW8 (ES under bridge) 7.41 RW10 (ES near mine) 7.36 NW3 (ES near mine) 7.33 NW7 (BH 700 m from mine) 6.67 S1: Shaft one; EHS: Edendale High School; BH: Borehole; EPS: Edendale Primary School; S2: Shaft two; ES: Edendalespruit

The samples that were slightly acidic include RW1, RW7, NW4, NW5 and NW7. Sample RW1 was collected from near shaft one and RW7 from shaft two, indicating that the water from the mineshafts is somewhat acidic in the rainy season.

Samples RW2_3, RW6, RW8 RW10, NW1, NW2, NW3, NW6 and NW8 were slightly basic. Samples RW2_3 and NW5 were collected from the borehole of Edendale High School and samples RW6 and NW6 from Edendale Primary School. These samples show that the borehole water from both schools in both seasons is close to neutral and within the accepted range for domestic use according to DWAF (1996).

Samples RW10 and NW3 were collected from the Edendalespruit down slope from the mine site, both these samples are slightly acidic as are the samples collected from the Edendalespruit at the bridge of the R513 before entering the area of the mine. In both seasons the water of the Edendalespruit becomes only slightly more acidic flowing through the mine site. Sample NW7 was collected from a residential borehole only 700 metes from the mine site and is only slightly acidic, but still within accepted range of natural and domestic water.

Anion concentrations in the water samples (Table 5) were mostly below the detection limits of the method used as well as below the TWQR for domestic water set by the South African Water Quality Guidelines (DWAF, 1996). Cation concentrations (Table 6) fall within the range set by the TWQR, except for cadmium. In the latter case the detection limits were too high to determine whether or not the values are acceptable according to the Water Quality Guidelines. ICP-MS was used to measure arsenic and lead concentrations (Table 7) at the Council of Geoscience. Most of the samples are below the detection limit and, therefore, fall within the TWQR for arsenic and lead, except samples RW1 (near shaft one) and RW10 (Edendalespruit below the mine site).

Table 5: Results of ion chromatography analysis of water samples. All results in mg/L. (Data Source: Chemistry Department).

Detection Element limit (dl) RW1 RW2 RW3 RW4 RW6 RW7 RW8 RW10 NW1 NW2 NW3 NW4 NW5 NW6 NW7 NW8 TWQR F- 0.1 mg/L

Table 6: Results of ICP-OES analysis of water samples. All results in mg/L. (Data Source: Chemistry Department).

Detection Element limits (dl) RW1 RW2 RW3 RW4 RW6 RW7 RW8 RW10 NW1 NW2 NW3 NW4 NW5 NW6 NW7 NW8 Check Std. 10 TWQR Ca 0.05 mg/L 3.48 29.4 29.5 1.92 31.3 56.2 20.3 29.27 36.5 53.7 23.7 1.95 27.1 30.8 8.84 24.5 9.93 0-32 Ba 0.05 mg/L 0.07

Table 7: Results of ICP-MS analysis of water samples. All results in mg/L. (Data Source: Council for Geoscience). Detection Check Std. Element limits (dl) RW1 RW2 RW3 RW4 RW6 RW7 RW8 RW10 NW1 NW2 NW3 NW4 NW5 NW6 NW7 NW8 0.2/0.002 TWQR As 0.002 mg/L

Data generated from the three analytical methods used to test the water samples was compared against the TWQR set by the Water Quality Guidelines. Graphs were compiled indicating the element concentrations versus the accepted values according to the South African Water Quality Guidelines to assess the quality of the water in the study area (Figures 14 and 15). Where element concentrations were below detection limits, the detection limit itself was graphed as the highest possible value.

Sample RW1 was collected from a pit near shaft one and sample NW1 from shaft one (Figure 14). Sample RW1 has high a sulphate concentration at 18.6 mg/L in comparison to the other samples in the same season but the TWQR is set at 0-200 mg/L, therefore, the water is of acceptable quality. The lead concentrations at 0.07 mg/L are above the TWQR (0-0.01 mg/L). Sample NW1 has a high calcium concentration (36.5 mg/L), which is above the TWQR. The magnesium concentration is also relatively high in comparison with other samples taken in the same season, but is still below the TWQR. The nitrate concentration (12.6 mg/L) is well above the TWQR (0-6 mg/L). And the phosphate concentration is relatively high in comparison with other samples; however it is below the TWQR.

Samples RW2, RW3 and NW5 were collected from the borehole at Edendale High School (Figure 14). Samples RW2 and RW3 show high calcium, magnesium and sodium concentrations. The TWQR for calcium is 0-32 mg/L and calcium in these samples measured at 29.41 and 29.48 mg/L (RW2 and RW3, respectively). The values are close but not exceeding the TWQR, unlike the magnesium concentrations, which are 49.7 and 50 mg/L (RW2 and RW3, respectively), where the TWQR is 0-30 mg/L. The sodium concentrations are high in comparison to the other samples but still well within the accepted TWQR. Sample NW5 shows relatively high calcium values, but not exceeding the TWQR. The magnesium concentration (47.6 mg/L) is above the TWQR. The sodium, nitrate and sulphate levels are also relatively high in comparison with the other samples taken in this season, but they do not exceed the TWQR.

Samples RW4 and NW4 were collected from the fountain below Edendale High School. These samples show comparatively low concentrations of all elements analysed (Figure 14).

Sample RW1 (Shaft one) Sample NW1 (Shaft one) 1000 1000

100 100 10 10 TWQR 1 1 Sample (mg/l) (mg/l) (mg/l) (mg/l) 0.1 0.1 0.01 0.01 Element Concentration 0.001 Element Concentration 0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4

Elements Elements

Sample RW2_RW3 (Edendale High School) Sample NW5 (Edendale High School)

1000 1000

100 100 10 10 TWQR 1 1 Sample (mg/l) (mg/l) (mg/l) 0.1 0.1 0.01 0.01 Element Concentration Element Concentration 0.001

0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4

Elements Elements

Sample RW4 (Fountain below Edendale High School) Sample NW4 (Fountain below Edendale High School)

1000 1000

100 100

10 10 TWQR 1 1 Sample (mg/l) (mg/l) 0.1 0.1 0.01 0.01 Element Concentration Element Concentration 0.001 0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4

Elements Ele m e n t s

Sample RW6 (Edendale Primary School) Sample RW6 (Edendale Primary School) 1000 1000

100 100 10 10 TWQR 1 1 Sample (mg/l) (mg/l) 0.1 0.1

0.01 0.01 Element Concentration Element Concentration 0.001 0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4

Ele m e n t s Elements

Figure 14: Element concentrations within water samples RW1, NW1, RW2, RW3, NW5, RW4, NW4, RW6 and NW6. Anion concentrations measured by ion chromatography, cation concentrations measured by ICP-OES, and lead and arsenic concentrations measured by ICP-MS. Note TWQR is plotted for reference (for GPS coordinates see Appendix III and for TWQR see Appendix IV).

Samples RW6 and NW6 were collected from the borehole at Edendale Primary School (Figure 14). The calcium concentrations of sample RW6 are slightly below the TWQR (0-32 mg/L) at 31.3 mg/L and, therefore, even though the value is high in comparison with the other samples, it is still within the accepted range. Sample NW6 has high calcium concentrations, although they are still slightly below the TWQR. Nitrate concentrations are relatively high in comparison with other samples taken in the same season but are below the TWQR.

Samples RW7 and NW2 were collected from shaft two (Figure 15). Sample RW7 contains high concentrations of calcium and magnesium. The TWQR for calcium is 0-32 mg/L where RW7 contains 56.2 mg/L of calcium and NW2 53.7 mg/L. The magnesium concentration should be between 0-30 mg/L according to the TWQR but RW7 contains 38.4 mg/L of magnesium and NW2 35.8 mg/L. Lead concentrations at 0.009 mg/L just fall within the TWQR of 0-0.01 mg/L. Sample NW2 has high calcium and magnesium concentrations, both above the TWQR.

Water samples RW8 and NW8 were collected from the Edendalespruit under the bridge crossing the R513 before the Edendalespruit enters the mine property (Figure 15). Sample RW8 has a relatively high calcium concentration at 20.31 mg/L, but it is still within the TWQR. The sodium values are also high at 13.56 mg/L in comparison to the other samples of the area but the TWQR for sodium is 0-100 mg/L, therefore, the concentration is well within the accepted limits. Lead concentrations are again just below the TWQR at 0.007 mg/L. Sample NW8 has relatively high calcium, magnesium, sodium, chloride and sulphate concentrations in comparison with the other samples taken in the same season, but all values are still below the TWQR and, therefore, within the accepted levels.

The water samples RW10 and NW2 were collected from the Edendalespruit at the mine site (Figure 15). Sample RW10 shows relatively high calcium and magnesium concentrations, however, values are within the TWQR. Lead concentrations at 0.77 mg/L are, however, well above TWQR. Sample NW2 has relatively high concentrations of calcium, magnesium and sulphate, although none exceed the TWQR. Sample NW7 was only collected during the dry season from a borehole approximately 700 meters from the mine site. The water quality indicates all concentrations below the TWQR (Figure 15).

Sample RW7 (Shaft two) Sample NW2 (Shaft two)

1000 1000 100 100 10 10 TWQR 1 1 Sample 0.1 0.1

0.01 0.01 0.001 0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration (mg/l) (mg/l) Concentration Element Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration (mg/l) (mg/l) Concentration Element

Elements Elements

Sample RW8 (Edendalespruit at bridge over R513) Sample NW8 (Edendalespruit at bridge over R513)

1000 1000

100 100

10 10 TWQR 1 1 Sample 0.1 0.1

0.01 0.01 0.001

Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 0.001 Element Concentration (mg/l) Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration (mg/l)

Ele m e n t s Elements

Sample RW10 (Edendalespruit below plant site) Sample NW3 (Edendalespruit below plant site)

1000 1000

100 100

10 10 TWQR 1 1 Sample 0.1 0.1

0.01 0.01 0.001

0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration (mg/l) Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration(mg/l)

Elements Elements

Sample NW7 (Residential borehole 700 metres from mine site)

1000

100

10 TWQR 1 Sample 0.1

0.01

0.001 Ca Ba Mg Cu Na Zn K Pb As F Cl NO2 NO3 Br PO4 SO4 Element Concentration (mg/l)

Elements

4.3.2 Solid samples

Using the XRD various minerals were identified in the solid samples, the more common ones include quartz (SiO2), cerussite (PbCO3), sphalerite (ZnS), galena (PbS) and anglesite

(PbSO4) (Table 8). In addition to the minerals identified in this study, barite and chrysotile were identified by the South African Micromount Society (Buchauer, 1999). Various oxides were also identified by the Micromount Society, such as descloizite, hematite, hemimorphite, linarite, mimetite, minium and siderite (Buchauer, 1999).

Table 8: Main minerals identified by XRD for each sample, with sample location description. Sample Sample description Minerals identified by XRD Quartz (SiO2) RS1 Soil, medium-grained sandy topsoil (S1) Cerussite (PbCO3) Magnetite (Fe3O4) Quartz (SiO2) Cerussite (PbCO3) RS2 Soil, medium-grained sandy topsoil (S1) Sphalerite (ZnS) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Muscovite (KAl3Si3O10(OH)2) Quartz (SiO2) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) RS3 Waste dump material, waste rock (S1) Muscovite (KAl3Si3O10(OH)2) Calcite (CaCO3) Dolomite (CaMg(CO3)2) Quartz (SiO2) Muscovite (KAl3Si3O10(OH)2) RS4 Waste dump material, waste rock (S1) Calcite (CaCO3) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Orthoclase (KAlSi3O8) Quartz (SiO2) Cerussite (PbCO ) RS5 Waste dump material, waste rock (S1) 3 Muscovite (KAl3Si3O10(OH)2) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Quartz (SiO2) Muscovite (KAl3Si3O10(OH)2) Chlorite ((Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Waste dump material, white soil around Anglesite (Pb(SO )) RS6 4 waste dump (S1) Cerussite (PbCO3) 3+ Franklinite (ZnFe 2O4) Susannite/leadhillite (Pb4(SO4)(CO3)2(OH)2) Gypsum (CaSO4·2H2O) Quartz (SiO2) Waste dump material, white soil around Cerussite (PbCO ) RS7 3 waste dump (S1) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Muscovite (KAl3Si3O10(OH)2) Quartz (SiO2) RS8 Soil, medium-grained sandy topsoil (S1) Muscovite (KAl3Si3O10(OH)2) Orthoclase (KAlSi3O8) Quartz (SiO2) Albite (NaAlSi O ) RS9 Soil, medium-grained sandy topsoil (S2) 3 8 Montmorillonite ((Al,Mg)8(Si4O10)4(OH)8·12H2O) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6)

Sample Sample description Minerals identified by XRD Quartz (SiO2) Sphalerite (ZnS) Galena (PbS) RS10 Slag material, white precipitate (S2) Anglesite (Pb(SO4)) Cerussite (PbCO3) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Calcite (CaCO3) Quartz (SiO2) Galena (PbS) Cerussite (PbCO3) Slag material, grey fine-grained slag Anglesite (PbSO ) RS11 4 (S2) Sphalerite (ZnS) Hemimorphite (Zn4Si2O7(OH)2(H2O) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Muscovite (KAl3Si3O10(OH)2) Quartz (SiO2) Sphalerite (ZnS) Galena (PbS) Slag material, white precipitate on grey RS12 Anglesite (PbSO ) soil (S2) 4 Gypsum (CaSO4·2H2O) Muscovite (KAl3Si3O10(OH)2) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Quartz (SiO2) Anglesite (Pb(SO )) Slag material, grey fine-grained slag 4 RS13 Chlorite (Mg,Fe) (Si,Al) O (OH) ·(Mg,Fe) (OH) ) (S2) 3 4 10 2 3 6 Gypsum (CaSO4·2H2O) Muscovite (KAl3Si3O10(OH)2) Quartz (SiO2) Anglesite (Pb(SO4)) Hemimorphite (Zn4Si2O7(OH)2(H2O) Susannite/leadhillite (Pb4(SO4)(CO3)2(OH)2) Muscovite (KAl3Si3O10(OH)2) RS15 Slag material, encrustations (S2) 3+ 4 Paracoquimbite (Fe 2(SO )3•9H2O) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Nontronite (Fe2(Al,Si)4O10(OH)2Na0.3·nH2O) Brianyoungite (Zn3(OH)4(CO3SO4)) Cerussite (PbCO3) Quartz (SiO2) Anglesite (Pb(SO4)) Slag material, white precipitate on grey Gypsum (CaSO 2H O) RS16 4 2 fine-grained slag (S2) Chlorite (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6) Montmorillonite ((Al,Mg)8(Si4O10)4(OH)8·12H2O) Muscovite (KAl3Si3O10(OH)2) S1: Shaft one (northern) side of road; S2: Shaft two (southern) side of road

Results of XRF analysis using pressed powder pellets are given in Appendix V. The concentrations were normalised to shale (PAAS) for a comparison to average continental crust concentrations (Taylor and McLennan, 1985). Analysis was carried out for trace elements for each of the solid samples collected, focusing on lead, copper and zinc (Figure 16, Figure 17 and Figure 18).

10000

1000

100 RS1 10 RS2 1 RS7

Sample/PAAS RS8 0.1

0.01

0.001 Ba Nb Pb Rb Th Zr Co Cr Cu Zn Ni V Sc Trace elements

Figure 16: Normalised trace element concentrations for soil samples (for XRF data see Appendix V).

10000

1000

100 RS3 10 RS4 1 RS5 RS6 Sample/PAAS 0.1

0.01

0.001 Ba Nb Pb Rb Th Zr Co Cr Cu Zn Ni V Sc Trace elements

Figure 17: Normalised trace element concentrations for waste rock dump material (for XRF data see Appendix V).

10000

1000 RS9 100 RS10 RS11 10 RS12 1 RS13

Sample/PAAS 0.1 RS15 0.01 RS16

0.001 Ba Nb Pb Rb Th Zr Co Cr Cu Zn Ni V Sc Trace elements

Figure 18: Normalised trace element concentrations for slag material (for XRF data see Appendix V).

XRF analysis indicates high concentrations of zinc, copper and lead. Of primary concern is the high concentration of lead due to its toxicity. As there are currently no soil quality standards available in South Africa, the soil quality standards of the Netherlands are used (Table 9). These standards are accepted by the European Union (EU) and indicate both target and intervention values for soils, where the target value is the maximum permissible concentration with no risk to humans, plants, animals or ecological systems, and the intervention value indicates values of significant risk, which if exceeded, would require mitigation measures (Rösner and Schalkwyk, 2000).

Table 9: Soil quality standards of the EU (Rösner and Schalkwyk, 2000). Element As Co Cr Cu Mo Ni Pb Zn Target value (ppm) 29 20 100 36 10 35 85 140 Intervention value (ppm) 55 240 380 380 200 210 530 720

Zinc concentrations for soil samples and waste rock dump material are below the EU target values (Figure 17 and Figure 18), however, zinc concentrations for slag material sampled exceed the target values but fall below the intervention values of the EU standards (Figure 19) and, therefore, are not considered hazardous. Copper concentrations (Figure 17, Figure 18 and Figure 19) do not exceed the EU target values, except sample RS10 from the slag material, which shows a concentration of 112 ppm, well above the EU target value of 36 ppm but still below the intervention value of 380 ppm.

The lead concentrations obtained with XRF were normalised to the target values (Figure 19) and intervention values (Figure 20) of the EU standards for each of the three groups of solid material sampled. Normalised concentrations that fall below one are less than the target or intervention values and normalised concentrations greater than one are higher than the target or intervention values, where the x-axis of the graphs crosses at one. In this way the extent of contamination can be ascertained for each group.

150

110 Highest value Average 70 Low est value Sample/target value Sample/target 30

-10 Soil Waste dump material Slag material

Figure 19: Lead concentrations normalised to target values of the EU standard (see Appendix V for XRF data).

e 21

15 Highest value Average Low est value 9

Sample/intervention valu 3

Soil Waste dump material Slag material -3

Figure 20: Lead concentrations normalised to intervention values of the EU standard (see Appendix V for XRF data).

The ranges of lead concentrations for waste dump material and slag material fall above one for both the target and intervention values (Figure 19 and Figure 20), indicating the seriousness of the contamination. Average lead concentrations for soil samples fall above target and intervention values, however sample RS8 plots at 0, being below the target and intervention values and sample RS9 plots at 0 for intervention values.

The lead concentrations are clearly lower in the soil samples, increasing in the waste rock dump material and becoming the highest in the slag material; therefore, the primary areas of concern are the waste rock dump and the slag heap. The lead concentrations in the soil surrounding the ELM are closer to the intervention level defined by the EU, where lead concentrations for both the waste rock dump and slag heap greatly exceed intervention values.

The lead concentrations can be mapped on the study area to indicate the areas of greatest concern (Figure 21). The soil samples RS1, RS2, RS8 and RS9 are relatively less contaminated. RS1 and RS2 were collected to the east of the waste rock dump, where material had been excavated from open pits. The samples collected from the waste rock dump (samples RS3, RS4, RS5, RS6 and RS7) indicate higher concentrations of lead, specifically sample RS6, which was collected from the white soil around the rock dump. Samples RS10-RS16 collected from the slag heap at the old mine site indicate the highest concentrations of lead. These results confirm the comparisons to the EU standards and indicate that the slag heap is of greatest concern.

Figure 21: Image illustrating the spatial distribution of lead concentrations around the ELM (concentrations normalised to EU target values) (Google Earth, 2006 http://earth.google.com).

Chapter 5

Discussion and conclusions

• Remnants and potential dangers of mining and processing at the ELM The ELM operated from the 1890’s through to 1938, when it was abandoned. Although fair amounts of silver were produced, the mine focused mainly on the exploitation of lead from galena, from a single fault-hosted vein from two different shafts. There are limited details on the exact mining and smelting process used at the mine and the only remnants of mining and processing at the ELM is the waste rock dump, the slag heap, a few open pits, the two main shafts and some ruins of the old processing plant itself just north of the Edendalespruit. It can be assumed that the ELM used a pyrometallurical production method for producing lead as it operated a sintering plant with a reverberatory furnace (Russell, 1940).

Since ELM operated in the 1890’s till 1938 there would have been limited if any emission or pollution control mechanisms in place, such as scrubbers and baghouses, therefore, air emission (such as sulphur dioxide and particulate matter) and effluent (such as plant washdown wastewater and slag granulation water) would have been released directly into the atmosphere and into natural water sources in the area, namely the Edendalespruit and groundwater sources. The ELM would have produced around 17 000 metric tons of solid waste and approximately 170 metric tons of lead in air emissions from shaft one throughout its lifespan. Slag from the smelting process was dumped onto the slag heap near the mine site. This contains high concentrations of zinc, iron, silica, lime (CaO) and lead, and is of primary concern as it has an impact on human health and the environment today.

• Water chemistry and seasonal variations In terms of water quality most of the water samples have near-neutral pH (Table 4), except sample RW4 collected at a natural fountain upstream of the Edendale High School, which is more acidic. The pH of most natural waters lies in the range of 6.5-8.5 and the TWQR of pH for domestic water usage is between 6 and 9, see Appendix IV (DWAF, 1996). Therefore, none of the samples indicate a serious problem with regards to water pH in the area, with the exception of sample RW4, which is below the recommended limits. Certain samples indicated element concentrations above the recommended TWQR (Table 10). High lead concentrations are of significance due to its severe health impacts.

Table 10: Samples with element concentrations above the TWQR, indicating driving force and health impacts. Element Health impact (DWAF, concentration Samples Locality Driving force 1996) above TWQR Edendale High RW2_3, RW5 Magnesium School Geology of area No health impact RW7, NW2 Shaft two NW1 Shaft one Calcium Geology of area No health impact RW7, NW2 Shaft two Fertiliser used in local Methaemoglobinaemia in Nitrate NW1 Shaft one agricultural activities infants Secondary minerals Possible neurological RW1 Pit near shaft one from waste rock damage in young children Lead dump and fetuses Edendalespruit Secondary minerals Neurological impairment RW10 below mine site from slag heap in children

The water quality for the area surrounding the ELM is generally good or ideal in terms of the DWAF Water Quality Guidelines (1996) for domestic use as most samples fall within the TWQR and none of the samples indicate a serious pH problem. There are a few exceptions where calcium and magnesium concentrations exceed the TWQR, but there are no associated health effects (Table 10), and these high calcium and magnesium concentrations are normal for a calcite-dolomite rich environment (Table 11); water samples occur where P = 10-2.5. CO2 Nitrates, from fertilisers used in the area, exceed the TWQR in sample NW1 collected from shaft one, which could endanger infants if ingested (Table 10). The most concerning result is the high concentration of lead in the Edendalespruit below the mines old plant site, where contamination is the most prominent (Figure 21), and in the pit near shaft one (Table 10). Lead concentrations exceed the TWQR becoming unsafe for children and pregnant woman to drink during the rainy season. The presence of lead in the water samples could be controlled by the solubility of anglesite and susannite/leadhillite, found at the slag heap and within the waste rock material.

Table 11: PHREEQC equilibrium calculations assuming a calcite- dolomite carbonate rock for different values of P reflecting the CO2 common range in natural surface water. Mg2+ (mg/L) Ca2+ (mg/L) pH

PHREEQC ( P = 10-1.5) CO2 32 71 7.1

PHREEQC ( P = 10-2.5) CO2 14 31 7.7

PHREEQC ( P = 10-3.5) CO2 6 14 8.4

Analysis of water samples collected during and after the rainy season, allow for a comparison of water quality through the year, whereas collection of samples from different sites permits comparison between different environments. The water collected at shaft one (samples RW1 and NW1, Figure 14) showed a significant increase in calcium and magnesium and only a slight increase in sodium from the rainy to dry season. The dry season also showed a slight decrease in chloride, a slight increase in phosphate, a significant increase in nitrate and a significant decrease in sulphate. The concentration of lead decreased in the dry season and the arsenic levels remained constant. The water quality for both samples was good, being within the TWQR, except lead in the rainy season and calcium and nitrates in the dry season. Shaft two water quality (samples RW7 and NW2, Figure 15) indicates a slight decrease in calcium, magnesium, sodium, chloride, nitrates and lead in the dry season, whereas there is a minor increase in zinc and phosphate concentrations. Although calcium and magnesium concentration are above the TWQR for both seasons, there are no associated health effects and all other values are within the TWQR.

Edendale High School borehole water quality (samples RW2_RW3 and NW5, Figure 14) showed little change between seasons, with calcium, magnesium and nitrate levels remaining high, but overall the water would not cause any health effects in humans; only slight scaling problems from the high magnesium concentrations. Water collected from the fountain below Edendale High School showed little change in the water quality between seasons for the cations, whereas there was a decrease of nitrate and sulphate concentrations in the dry season (samples RW4 and NW4, Figure 14). The water quality is acceptable as all concentrations are within the TWQR. The water quality of the Edendale Primary School borehole indicates a minor change through the year (samples RW6 and NW6, Figure 14). There is only a slight decrease in the concentrations of calcium, magnesium, sodium, zinc, chloride and nitrates. All values are within the TWQR indicating good water quality at this site.

The water collected from the Edendalespruit at the bridge crossing the R513 shows all concentrations within the TWQR (samples RW8 and NW8, Figure 15). The dry season indicates an increase in calcium, barium, magnesium, sodium and fluoride concentrations. There is also a considerable increase in chloride and sulphate concentrations in the dry season. The amount of lead decreases in the dry season. The Edendalespruit’s water quality at the mine site (samples RW10 and NW3, Figure 15) shows a considerable decrease in lead concentrations in the dry season.

The value drops from 0.77 mg/L, a concentration that renders the water unsafe for children and pregnant woman, to below 0.005 mg/L. There is a reasonable decrease in calcium, magnesium, sodium and chloride, with a significant decrease in sulphates and only a slight decrease in barium and zinc, whereas phosphates show a slight increase in the dry season. The only element that exceeds the TWQR is lead in the rainy season whereas all other concentrations are within the TWQR.

Sample NW7 collected from a borehole approximately 700 meters from the mine site was only tested during the dry season and shows all values within the TWQR indicating good or ideal water quality (Figure 15). The comparison between the seasons shows a general decrease in element concentrations in the dry season. This is expected as the increase in water during the rainy season would mean more elements being leached into nearby water sources, namely the Edendalespruit and ground water, through chemical weathering. However, during the rainy season the raised water-level could drain water from the mine and into the surrounding water sources resulting in the increased lead concentrations found.

• Mineralogy and chemistry From XRD analysis it can be concluded that the soil samples (samples RS1, RS2, RS8 and RS9) are predominately composed of quartz, muscovite, chlorite and montmorillonite, with minor sphalerite and cerussite in some samples (Table 8). The waste rock dump material sampled from the waste rock itself (samples RS3, RS4 and RS5) is very similar in mineralogical composition to the soil samples, containing quartz, muscovite, chlorite and some cerrusite and calcite (Table 8).

Soil samples from the immediate vicinity around the waste rock dump (samples RS6 and RS7) are composed of quartz, muscovite and chlorite, with some cerussite, anglesite and susannite/leadhillite (Table 8). The last group of samples, namely samples RS10-RS16, were collected from the slag heap at the old mine site. The grey fine-grained slag (RS11 and RS13) is predominately composed of quartz, chlorite and significant amounts of anglesite, sphalerite, galena and cerrusite (Table 8). Samples RS10, RS12 and RS16 were taken of the white precipitate that formed on the slag material; this was found to be composed of chlorite, muscovite, sphalerite, galena, anglesite, with some gypsum and montmorillonite (sample RS16) (Table 8). The encrustations (sample RS15) are composed of quartz, chlorite, muscovite, anglesite, susannite/leadhillite, hemimorphite and some nontronite (Table 8).

The XRF analysis showed for the most part trace elements at or below normal crustal values, determined by average shale (PAAS) (Figure 16, 17 and 18), except for high concentrations of lead, copper and zinc, which reflects the abundance of galena, chalcopyrite, sphalerite and the respective secondary minerals, including anglesite, cerrusite and susannite/leadhillite (Table 12).

Table 12: Primary and secondary minerals found at ELM with associated source and solubility products. Solubility Solubility Source of primary products of products of Primary Minerals Secondary minerals minerals primary secondary minerals minerals Geological background Quartz (SiO ) 2 (stage one) Hydrothermal Calcite (CaCO ) 3.36·10-9 3 mineralisation (stage two) Hydrothermal Iron-rich dolomite (FeCO ) 3.13·10-11 3 mineralisation (stage two) Hydrothermal Pyrite (FeS ) 8·10-19 2 mineralisation (stage two) Anglesite 2.53·10-8 Hydrothermal Galena (PbS) 3·10-28 -14 mineralisation (stage one) Cerussite 7.4·10 Susannite/leadhillite 1.08·10-5 Hydrothermal Sphalerite (ZnS) 3·10-23 mineralisation (stage one) Hydrothermal Chalcopyrite (CuFeS ) 2 mineralisation (stage one) Hydrothermal Chlorite mineralisation (stage one (Mg,Fe) (Si,Al) O (OH) ·(Mg,Fe) (OH) ) 3 4 10 2 3 6 and two)

• Pollution potential and future impact The mobility of metals depends strongly on their mineralogical and chemical form as well as the pH of the environment they occur in (Maskall and Thornton, 1998). Maskall et al. (1995) suggests that pH is the principle controlling mechanism of vertical migration of lead and zinc through soil horizons. Increasing pH allows for the precipitation of insoluble metal compounds, including carbonates, oxides and hydroxides, and enhances the potential for adsorption and exchange reactions (Maskall et al., 1995). In addition, the exchange of metals onto clays and organic matter may further control metal mobility (Maskall et al., 1995). Soil properties such as soil texture, surface area, free iron oxide concentration and pH will determine metal mobility (Maskall and Thornton, 1998). Maskall et al. (1995) concluded that maximum lead and zinc mobility occurs in soils with a relatively low pH, coarse texture and a low content of free iron oxides.

In the study area the relatively low availability of metals, as documented by the good quality of surface and groundwater, is due to the presence of carbonates in the natural geology, namely the Silverton Formation, and the additions of calcium in the smelting process, which creates high soil pH conditions enabling metals to be precipitated as carbonates and for absorption reaction with iron oxides and hydroxides immobilising metals in insoluble states. Manganese and iron oxides and hydroxides are known to bind with lead mainly by specific adsorption (Rieuwerts et al., 2000). The slag heap at the ELM would contain calcium oxides and calcium silicates, both of which are highly alkaline compounds. These compounds would ensure the high pH of the slag heap. The elements of high concentration in the water and, therefore, the more mobile elements, are mainly calcium, magnesium and lead. The presence of calcium and magnesium is due to the abundance of these elements in the natural rocks of the area, which slowly leaches into the water sources. However, since neither of these elements occur at concentrations that are hazardous to human health, they are not of major environmental concern.

Solid samples (soils, waste rock material and slag material) are all marked by high concentrations of lead that exceed internationally recognised intervention limits by several orders of magnitude (Figure 19 and Figure 20). This is of particular concern due to leads hazardous nature to human health and the environment (Appendix II) and clearly indicates the strong need for mitigation measures. Although all lead concentrations in the solid samples are high, there is a considerable variation in concentration (Figure 21). Lead concentrations decrease further away from the waste rock dump and the slag heap to the soils surrounding the mine site. The toxicity of the waste rock material and slag material can clearly be seen by the lack of vegetation found in these areas. Areas of minimal vegetation are due to the phytotoxicity of soils containing high concentrations of potentially available metals. These sites are a risk to surrounding areas since the absence of vegetation facilitates wind erosion of metal contaminated particles and may increase the amount of water percolating through the soil and reaching ground water sources (Vangronsveld et al., 1991).

The primary lead bearing mineral is galena, which, when oxidised, forms a rim or armour around it preventing the further oxidation (Joeng and Lee, 2003).

The rim or armour is formed by cerussite (PbCO3) (reaction 1) or anglesite (PbSO4) (reaction 2), both of which have been identified as major components in the altered slag of the ELM and some cerrusite that has been identified in the soil and the waste rock material, with anglesite found in the waste rock material (Table 8).

2+ + Pb + H CO + 2H O → PbCO + 2H O (1) 2 3 2 3 3

2 + 2 − Pb +SO4 → PbSO4 (2)

The high pH of the soils would favour the formation of cerussite, as the mineral is usually stable at a pH above 6.0 (Maskall and Thornton, 1998). The solubility products of cerussite and anglesite are 3·10−28 and 2.53·10−8, respectively (Table 12) (Eni Generalic, 2003). Cerussite is very poorly soluble indicated by the low solubility product, unlike anglesite, which has a relatively higher solubility product and is, therefore, more soluble. As the more soluble mineral, dissolution of anglesite could be responsible for some of lead in the Edendalespruit below the mine site and for some of the lead in the pit near shaft one as it is found in the slag material and in the waste rock material near the pit (Table 8). In the presence of an acid both cerussite (reaction 3) and anglesite (reaction 4) would release lead into the environment. The lead present in the slag would become mobile should conditions become more acidic and undergo reaction 5.

+ 2+ PbSO4 + 2H3O → Pb + H2SO4 (3) PbCO + 2H O+ → Pb2+ +3H O + CO (4) 3 3 2 2 + 2+ Pb + 2H3O → Pb + 2H2O + H2 (5)

The oxidation products anglesite and cerussite form from the primary lead mineral galena and from these oxidation products a variety of other minerals form such as the trimorphous group susannite, leadhillite and macphersonite (Steele et al., 1998). Susannite and leadhillite are polymorphs of lead sulphate carbonate hydroxide (Pb4(SO4)(CO3)2(OH)2) that were both identified by XRD analysis, however leadhillite is the more stable polymorph at room temperatures and pressures, therefore, susannite may convert to leadhillite over time (Bindi and Menchetti, 2005). Leadhillite is commonly associated with anglesite and forms in the oxidised zone of lead deposits (Pellant, 1992), such as at the ELM.

The solubility product of leadhillite is 1.08·10-5 (Table 12) (Abdul-Samad et al., 1982), indicating that it is much more soluble than anglesite, and is most probably responsible for the majority of lead present in the pit near shaft one and in the Edendalespruit below the old mine site, as it was found in both the waste rock material and the slag material.

During this study some arsenic has been identified within the galena (less than 0.07 weight percent) and the arsenic-bearing trace mineral cobaltite was recognised by microprobe analysis. This arsenic would have been concentrated by metallurgical processing in the slag heap. However, arsenic concentrations were not measured by XRF and the arsenic at the ELM site appears immobile as it is not found in any significant concentrations within the water sampled, therefore it is not considered an environmental threat.

The solid samples collected around the ELM yield lead concentrations that are hazardous. This is of particular concern as the site is accessible to the public and there are two schools in the area. Another concern is the Edendalespruit that runs directly below the old plant site, although the leaching of this toxic metal into the spruit appears to be minimal (except for during the rainy season), the plant site is still a potential source of pollution and as conditions change over time it may become a highly contaminated water source with public access.

Even though water quality in the area is currently acceptable, the high concentrations of lead in the waste rock material and slag material poses a potential future threat to human health and the environment as meteoric water will slowly release the lead into the nearby water sources. The mobility of lead is currently limited by the high pH conditions of the contaminated areas, should pH decrease the lead will become mobile and may form a serious environmental threat.

Chapter 6

Recommendations

Due to the nature and extent of lead contamination at the abandoned ELM mitigation measures should be developed and implemented. These measures should include systems to both prevent risk to the environment and to human health and welfare as well as programs that remediate existing problems associated with metal contamination from the mine. The following are immediate recommendations warranted by the results of this study, however, the long term effectiveness of some suggestions will require further study, particularly for the soil mitigation measures as not all chemical, physical and biological interactions have been assessed.

1. Removal of slag heap at old mine site The slag heap at the old mine plant is the most prominent source of contamination at the ELM. Its removal would eradicate the source of pollution and allow the natural environment to recover. The slag material will have to be disposed of as hazardous waste due to its toxicity.

2. Enclose area around ELM The area surrounding the ELM should be enclosed by a security fence to prevent people and large animals entering the site where there are numerous exposed shafts and pits. The plants in the area may be toxic due to the uptake of metals rendering them unsafe to animals and for human usage, such as wood for domestic fires, fodder for animals. The soil and slag material at the old plant site should not be handled by people due to the extremely high concentrations of lead. Once handled, the contaminants are easily ingested through hand to mouth contact. The fence or enclosure should contain signs indicating the dangers, with illustrations to ensure warnings are fully comprehended.

3. Monitoring system A monitoring system should be put in place to monitor the water and soil quality to ensure the contaminants, particularly lead, remain insoluble and immobile. A monitoring frequency of six months would be adequate depending on the remediation methods implemented.

4. Treatment of heavy metal contaminated soils Metal-contaminated soils are notoriously hard to remediate. Current technologies include excavation and either land-filling or soil washing followed by physical or chemical separation of the contaminants (Alkorta et al., 2004). A logical solution would be the excavation and removal of the contaminated soil, but this is often not a viable option due to the size of the contaminated area and the high costs involved. A more acceptable alternative for soil remediation is in the in situ stabilisation of metals, thereby rendering them immobile in order to reduce the risks of surface and ground water contamination, plant uptake and exposure of other living organisms. A lower plant uptake results in plant cover that fixes and stabilises the top layer of soil, prevents wind erosion and has a positive effect on metal percolation (Boisson et al., 1999). The application of

hydroxyapatite (HA, Ca10(PO4)6(OH)2) to a metal (Pb, Zn, Cu, Cd) contaminated soil results in a decrease of the exchangeable amount of these metals. HA addition shows a decrease in the uptake of metals by plants but at the highest application rate (5 percent) there is a decrease in the uptake of nutrients leading to deficiency problems, in particular a magnesium deficiency (Boisson et al., 1999).

5. Phytoremediation of metal contaminated soils Phytoremediation is the use of plants to extract, sequester and /or detoxify pollutants in soil. It can be used in mined soil restoration by means of phytostabilisation and phytoextraction to stabilise toxic mine spoils and remove toxic metals, respectively (Alkorta et al., 2004). Micro-organisms can be used for metal remediation; however, metal-accumulating plants offer numerous advantages over microbial processes since plants actually extract metals from the polluted soils, theoretically rendering them clean (metal-free) (Garbisu and Alkorta, 2001). Phytoremediation is an effective, non-intrusive, inexpensive, ecologically responsible, aesthetically pleasing and socially accepted technology to remediate soils. However, phytoremediation has certain limitations, including root depth, solubility and availability of the contaminant. It also requires long periods of time to be effective, usually several years (Alkorta et al., 2004).

Phytoremediation is a complex system where various factors have to be taken into account, including planting densities, interaction of remediation plants with the existing environment and disposal of the metal-rich plants.

Heavy metals cannot be destroyed biologically, they are merely transformed from one oxidation state or organic complex to another. Depending on the plant type metals are stored in the roots, shoots or leaves, rendering them unsafe for animal consumption. Therefore, plants used for remediation have to be disposed of responsibly; they can be seen as hazardous waste or used for metal recovery, if economically feasible (Alkorta et al., 2004).

Hyperaccumulators are plants that accumulate high concentrations of metals in their foliage, these plants are often endemic to naturally mineralised soils. There are various hyperaccumulators that can be used to remediate the highly concentrated metals in the area, namely zinc, copper and lead, however, not all of these species are indigenous and may not be suitable to the climate of the area (Table 13) (Alkorta et al., 2004).

Table 13: Plants recommended for remediation of metal contaminated soil, namely zinc, copper and lead, indigenous status for South Africa and climate suitability of species for study area (adapted from Pienaar, 1984; Alkorta et al., 2004).

Metal Plant species South Africa Climate suitability of indigenous species T. caerulescens Exotic Sedum alfredii Exotic Zinc Platanus acerifolia Exotic Holcus lanatus Indigenous Unsuitable Copper Haumaniastrum robertii Exotic Agrostemma githago Exotic B. juncea Indigenous Suitable Lead T. rotundifolium Exotic Sesbania drummondii Exotic

The B. juncea is an appropriate plant for the ELM area as it hyperaccumulates lead and it is suitable for the climate of the region. This plant stores lead in its shoots, which would render this plant unsafe for animal consumption and it would have to be disposed of as hazardous waste to ensure no further contamination (Alkorta et al., 2004).

References

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Department of Water Affairs and Forestry (DWAF). 1996: South African Water Quality Guidelines. Volume 1: Domestic Water Use (2nd Ed.) Department of Water Affairs and Forestry (DWAF). 2000: Pollution incident in the Roodeplaat Dam. http://www.dwaf.gov.za/iwqs/leports/carin/lpd2000%5F2/exec.htm Eni Generalic. 2003: Solubility product constants. http://www.ktf- split.hr/periodni/en/abc/kpt.html Environmental Protection Agency (EPA). 1995: Copper, lead and zince smelting and refining. http://www.ilo.org/encyclopedia Garbisu, C. and I. Alkorta. 2001: Phytoextraction: a cost-effective plant-based technology for the removal of metals from the environment. Bioresource Technology, 77, 229–236 Glorennec, P. 2005: Analysis and mine. Environmental Research, 100, 150-158 Hanson, R.E., W.A. Gose, J.L. Crowley, J. Ramezani, S.A. Bowring, D.S. Bullen, R.P. Hall, J.A. Pancake and J. Mukwakwami. 2004: Paleoproterozoic intraplate magmatism and basin development on the Kaapvaal Craton: Age, paleomagnetism and geochemistry of ~1.93 to ~1.87 Ga post-Waterberg dolerites. The South African Journal of Geology, 107, 233-254 Harper, C.C., A. Mathee, Y. von Schirnding, C.T. Ce Rosa and H. Falk. 2002: The health impact of environmental pollutants: a special focus on lead exposure in South Africa. International Journal of hygiene and Environmental Health, 206, 315-322 Jansen, H. 1977: The geology of the country around Pretoria. Pretoria: Dept. of Mines Geol. Survey. Jin, Y., Y. Liao, C. Lu, G. Li, F. Yu, X. Zhi, J. Xu, S. Liu, M. Liu and J. Yang. 2005: Health effects in children aged 3-6 years induced by environmental lead exposure. Ecotoxicology and Environmental Saftey, in press Joeng, G.Y. and B.Y. Lee. 2003: Secondary mineralogy and microtextures of weathered sulfides and manganoan carbonates in mine waste-rock dumps, with implications for heavy-metal fixation. American Mineralogist, 88, 11-12. Kgwakgwe, K.P. 2001: Geology of Baviaanspoort-Edendale Area. Tshwane: Council for Geoscience Internal Report Maskall, J.E. and I. Thornton. 1998: Chemical partitioning of heavy metals in soils, clays and rocks at historical lead smelting sites. Water, Air and Soil Pollution, 108, 391-409 Maskell, J., K. Whitehead and I. Thornton. 1995: Heavy metal migration in soils and rocks at historical smelting sites. Environmental Geochemistry and Health, 17, 127-138

Meyer, P.A., F. Staley, P. Staley, J. Curtis, C. Blanton and M.J. Brown. 2005: Improving strategies to prevent childhood lead poisoning using local data. International Journal of Hygiene and Environmental Health, 208, 15-20 Nriagu, J.O., M.L. Blankson and K. Ocran. 1996: Childhood lead poisoning in Africa: a growing public health problem. The Science of the Total Environment, 181, 93-100 North Carolina Department of Environment and Natural Resources: Division of Pollution Prevention and Environmental Assistance. 2006: Sintering and Reverberatory Furnaces. http://www.p2pays.org/lef/01/text/00778/chapter2.htm Pellant, C. 1992: Rocks and minerals. London: Dorling Kindersley. Perks, P. 2004: Scanning Electron Microscope (SEM), URL. Department of Physics and Astronomy, Arizona State University http://acept.asu.edu/PiN/rdg/elmicr/elmicr.shtml Pienaar, K. 1984: The South African: What flower is that? Cape Town: C. Struik. Rieuwerts, J.S., M.E. Farago, M. Cikrt and V. Bencko. 2000: Differences in lead bioavailability between a smelting and a mining area. Water, Air and Soil Pollution, 122, 203-229 Rösner, T. and A. van Schalkwyk. 2000: The environmental impact of gold mine tailings footprints in the Johannesburg region, South Africa. Bulletin of Engineering Geology and the Environment, 59, 137-148 Russell, H.D. 1940: Lead occurrence at Edendale Nooitgedatch No 173/458/333 Pretoria District. Tshwane: Council for Geoscience Internal Report South African Committee for Stratigraphy (SACS), 1980. Stratigraphy of South Africa. Part 1 (Comp. L.E. Kent). Lithostratigraphy of the Republic of South Africa, South West Africa/Namibia, and the Republics of Bophuthatswana, Transkei and Venda: Handb. Geol. Surv. S. Afr., 8. Steele, I.M., J.J. Pluth and A Livingstone. 1998: Crystal structure of macphersonite: comparison with leadhillite. Mineralogical Magazine, 62, 451-459 Swart, Q. D., (1999). Carbonate rocks of the Paleoproterozoic Pretoria and Postmasburg Groups, Transvaal Supergroup. Unpublished M.Sc. thesis, Rand Afrikaans University, Johannesburg. Taylor, R and S.M. McLennan.1985: The continental crust: its composition and evolution: an examination of the geochemical record preserved in sedimentary rocks. Oxford: Blackwell Scientific. United States Department of Labour (USDL). 2006: Sintering and Reverberatory furnaces. http://www.osha.gov/SLTC/etools/leadsmelter/smelting/leverbfurnace.html

Vangronsveld, J., F. Van Assche and H. Clijsters. 1991: Reclamation of a “desert like” site in the north east of Belgium: evolution of the metal pollution and experiments in situ. In: Farmer, J.G. (Ed.), Proc. Int. Conf. Heavy Metals in the Environment. CEP Consultants, Edinburgh, UK, pp. 58-61. Von Schirnding, Y., A. Mathee, M. Kibel, P. Robertson, N. Strauss and R. Blignaut. 2003: A study of paediatric blood lead levels in a lead mining area in South Africa. Environmental Research, 93, 259-263 World Bank Group (WBG). 1998: Lead and Zinc Smelting. Pollution Prevention and Abatement Handbook

APPENDIX I

SPECTRAU Faculty of Science Auckland Park Kingsway Campus PO Box 542, Auckland Park 2006, South Africa +27 (0)11 489-2322 | +27 (0)11 489-3361 (fax)

To : Prof. J. Gutzmer, University of Johannesburg, Department of Geology

From : Dr. Christian Reinke

Date : 20 Nov 2006

Subject : Occurrence of arsenic in the sample EV1-B

Our reference : CR142

Introduction Prof. J. Gutzmer submitted a polished section containing galena (PbS) and other sulfides to— • Search for arsenic-bearing phases by X-ray mapping in a scanning electron microscope (SEM). • Determine whether or not arsenic and silver can be detected in the PbS by wavelength- dispersive X-ray spectrometry (WDX), using the IbeX spectrometer at Spectrau. The sample was labelled EV1-B (Table 1). We examined an area that was a few mm2 large and contained large sulfide grains. Table 1. Sample traceability information. Sample number Description CR142_1 EV1-B

Experimental Procedures The sample had been carbon-coated before we received the section. We removed the coating with 0.25 μm diamond polish and applied a carbon-coating of about 20 nm thickness. X-ray maps of arsenic and other elements were acquired with an energy-dispersive spectrometer (EDS), largely on a Jeol Superprobe 733. We determined the chemical composition of typical phases in the polished section by energy- dispersive X-ray spectrometry (EDX). The EDS was calibrated— • For the analysis of the sulfides using pure elemental reference materials for As, Cu, Fe, and Ni; and FeS2 for S, Sb2S3 for Sb, CaSiO3 for Si, and ZnS for Zn.

• For the analysis of the oxides using CaSiO3 for Si and pure binary oxides for Al, Fe, and Mg. Other elements were quantified with supplied references from the manufacturer of the EDX system. The results of this report pertain to the samples submitted. The University of Johannesburg and SPECTRAU take responsibility only for the accuracy of the analysis itself and not for the advice taken based on these results. If you rely on the information and the data contained in this report you are responsible for ensuring by independent verification its accuracy or completeness. 60

Galena was not analysed by EDX because the S Kα and Pb Mα X-ray lines overlap severely. The detection limit of EDX is about 0.4 mass % if X-ray peaks do not overlap.

We conducted the WDX measurements with an IbeX spectrometer connected to the Jeol Superprobe 733. The IbeX is an application-specific wavelength-dispersive spectrometer that, at the time of this work, was configured for the determination of C, F, Na, Al, Cl, and Fe. The IbeX was equipped with specific analysing crystals for each of these elements. The sensitivity of the spectrometer decreases if an analysing crystal is used to diffract X-rays with a different wavelength, such as characteristic X-rays of another element. For instance, the IbeX needs two different TAP crystals (called TAP-Na and TAP-Al) for the measurement of Na Kα and Al Kα, respectively. We aligned the TAP-Al crystal in the IbeX for the measurement of As Lα. The arsenic analyses were carried out at an accelerating voltage of 15 kV, a beam current of 100 nA, and 80 s on-peak counting time. The detection limit for arsenic was about 0.07 mass % As. The silver content of the PbS was not measured because the detection limit for Ag was too high (after aligning the PET-Cl crystal for the measurement of Ag Lα). Results The arsenic content was below the detection limit of about 0.07 mass % As in the PbS, ZnS, and CuFeS2 particles that were analysed by WDX. X-ray mapping and EDX analyses show that the sample contains arsenic in (Co,Ni)AsS particles that seem to be less than 10 μm large. This is shown in Figure 1 (analyses 1–3, below). The small amount of silicon in the analyses of the (Co,Ni)AsS particles might come from the matrix, which largely consists of SiO2 (Figure 1).

ID As Co Cu Fe Ni S Sb SiO2 Zn Total Comment 1 46.9 18.4 – 1.1 15.9 18.9 1.2 1.0 – 103.4 2 46.1 17.7 – 1.0 17.9 19.5 1.2 0.4 – 103.8 3 44.7 21.5 – 1.1 14.3 20.5 0.5 – – 102.6 – – – 0.5 – 33.1 – – 66.6 100.2 ZnS – – 33.1 29.6 – 34.4 – – – 97.1 CuFeS2

ID Al2O3 FeO MgO MnO Na2O SiO2 Total Comment 4 – 0.8 – – – 99.0 99.8 5 0.8 – – – – 98.6 99.4 6 20.2 29.0 4.5 – 0.7 23.3 77.7 7 19.5 30.0 4.5 0.5 0.6 21.9 77.0 7 19.6 30.6 4.5 0.5 0.5 22.2 77.9 8 21.1 34.7 4.6 0.5 0.5 25.2 86.6 Figure 1. Backscattered-electron image of arsenic-bearing particles in the sample EV1-B. Numbers in the image refer to corresponding chemical analyses in the tables (in mass %, by EDX). Concentrations below the lower limit of the determination have been replaced with a dash (“–“). The column labelled “Total” contains the sum of the mass fractions. The ZnS and CuFeS2 analyses are outside the field of view.

APPENDIX II

The occurrence and health effects of lead

• Occurrence of lead Lead is a bluish-white, soft metal, which is highly malleable and ductile. It is also highly resistant to corrosion. Lead rarely occurs in its elemental state. The most common ores of lead are galena (lead sulphide), cerussite (lead carbonate) and anglesite (lead sulphate). Lead tends to accumulate in sediments and soils in the environment (DWAF, 1996).

• Health effects of lead Lead that is absorbed by vertebrate organisms is largely deposited in the body’s skeleton (DWAF, 1996). In humans lead is an element that has no known physiological function but has the potential to adversely affect a variety of fundamental biochemical processes. Children less than six years old are particularly susceptible to lead poisoning due to the fact that they absorb far more lead from the environment than adults do and their central nervous systems are still developing (Jin et al., 2005). Lead exposure in humans occurs predominantly through the lungs and the gastrointestinal tract (Glorennec, 2005).

Elevated Blood Lead Levels (BLL) in children have been associated with various health effects, including a reduction in intelligence quotient (IQ), behavioural effects such as hyperactivity, an inability to concentrate, poor school performance, anaemia and abnormal development of organs such as the heart, liver and kidneys. Studies have indicated that foetus development is highly sensitive to lead exposure during development (Harper et al., 2002). In young children lead can impair both the antibody and the cellular response to a variety of bacterial and viral infections. Lead poisoning can also aggravate certain communicable diseases and is, therefore, an increasing factor in the common endemic diseases in Africa (Nriagu et al., 1996).

There is a high prevalence of children in Africa with iron deficiencies thus increasing their ability to absorb lead and making them more susceptible to the neurological impact of plumbism (Nriagu et al., 1996). Plumbism is the medical term for lead poisoning. Childhood plumbism is present when the BLL are equal to or greater than 10 µg/dL, at which level cognitive deficits may start to develop. Depending on the degree of exposure to lead, plumbism may take a while to occur (Chua, 2003).

Chronic lead poisoning, which is far more common than acute poisoning, results from the intake of lead over a period of months or years rather than from episodic exposure (DWAF, 1996).

There are numerous symptoms of plumbism that affect many different body systems. Even chronic exposure to low levels of lead can be detrimental to mental development, especially in children. Other symptoms of lead poisoning may include hyperirritability, aggressive behaviour, decreased appetite and energy, poor sleeping habits, headaches, constipation and loss of recently acquired developmental skills (in young children). Anaemia and abdominal cramping are also common. At high levels lead exposure may cause acute encephalopathy (brain disease) with vomiting, staggering gait, muscle weakness, seizures or coma (American Accreditation HealthCare Commission, 2006). When the blood concentration of lead is greater than 50 and up to 100 µg/dL, the danger of symptomatic lead poisoning greatly increases (Chua, 2003). According to Meyer et at. (2005), at BLL of ≥70 µg/dL health effects can include seizures, coma and even death and there is no defined threshold for harmful effects of lead poisoning (Meyer, et at., 2005). If the level is 100 µg/dl or more, the risk of brain damage is greatly increased. The treatment for lead poisoning is called chelation therapy (Chua, 2003).

According to the Centre for Disease Control and Prevention a blood lead level of >10 µg/dL is the international standard and any level at or above this warrants further investigation and action (Harper et al., 2002). However, some studies have shown evidence of adverse health effects at levels lower than 10 µg/dL, especially in infants or fetuses (Harper et al., 2002). The health effects of lead exposure have been well documented and lead to the implementation of many policies limiting the use of lead in petrol, food and drink cans, pipes and paint (Meyer et at., 2005). Recommended Tolerable Daily Intake (TDI) of lead by Food and Agricultural Organisation of the United Nations (FAO) and the World health Organisation (WHO) is 25 µg/kg (Glorennec, 2005).

Lead concentrations within water are measured as micro grams per litre (µg/L) and at low values can be measured colorimetrically using the dithizone method, or alternatively by atomic absorption spectrophotometry and ICP-MS. Generally the concentration of lead in surface water is less than 0.010 mg/L. In sea water lead values are no greater than 0.003 mg/L, whereas in contaminated water the lead levels maybe several mg/L (DWAF, 1996).

The Target Water Quality Range (TWQR) according to the Water Quality Guidelines determined by DWAF (1996) is between 0-10 µg/L (Table 14) and it is recommended that the TWQR not be exceeded.

Table 14: Lead concentrations in water and associated human health effects (adapted from DWAF, 1996). Lead Range (µg/L) Health Effects Target Water Quality Range No danger of any adverse effects by exposure from water 0-10 It is recommended that the Target Water Quality Ranges (TWQR) not be exceeded due to the potentially acute and/or irreversible effects of lead on human health No danger of any adverse health effects except for a slight risk of behavioural 10-50 changes and the possibility of neurological impairment, where the exposure to lead from other sources, such as food, is not minimised Possible neurological damage where the nerve and brain tissues are 50-100 developing, that is, in fetuses and young children. Young children and pregnant women should avoid exposure Definite danger of neurological impairment in children. Alternative water supply 100-300 should be used by sensitive groups (children and pregnant women) > 300 Symptoms of chronic lead poisoning are possible with continuous exposure

• Studies of lead exposure in South Africa Although there is no current national blood lead surveillance program in South Africa various studies have shown that certain groups of children have unacceptably high BLL (Table 15). In the 1980s a study undertaken by von Schirnding and co-workers, which showed that children living in an inner-city area had a median BLL of 16 µg/dL, with coloured children having higher levels than their white counterparts (von Schirnding, 2003). A repeat survey in the same area in 1991 showed little change in the blood lead distribution of children. The study found a strong association between elevated BLL and the proximity of schools with respect to traffic density (Harper et al., 2002). Now with the stoppage of leaded petrol production these values should start to decrease.

A study in 1990 in Johannesburg/Soweto indicated a core BLL mean of 5.9 µg/dL, where these elevated levels were associated with socio-economic status, maternal age, marital work status, household crowding and some hematological factors. A study undertaken in Johannesburg in 1995 using 477 grade one school children showed a mean BLL of 11.9 µg/dL (Table 15), where 75 percent of children’s BLL exceeded 10 µg/dL, the current international action value. Various socio-economic aspects were associated with the elevated levels including, living standards (Harper et al., 2002).

Table 15: Average BLL in various countries/cities (adapted from Nriagu et al., 1996; Harper et al., 2002). Country/City Average Blood lead levels (µg/dL) Urban Australian and European children (1989) below 10 USA (1994) 3 Himalayas and Papua New Guinea (Nriagu et al., 3-5 1996) Cape Town inner city children (Nriagu et al., 1996) 18 Johannesburg (1995) 11.9

A study was carried out by von Schirnding and co-workers in the Northern Cape Province. This study showed that despite higher socio-economic status children in the mining village of Aggeneys had higher BLL, an average of 16 µg/dL, than in the village of Pella 40 kilometres away where BLL were lower, at an average of 13 µg/dL. Fathers working in the mines in Aggeneys were found to be a pathway for the lead exposure among their children (Harper et al., 2002). Therefore, despite the higher socio-economic and nutrition status in Aggeneys the population showed higher BLL than Pella, which has a lower socio-economic status and is more impoverished. This contradiction to the theory that a lower socio-economic status results in higher BLL can be contributed to the level of exposure of environmental lead. This study also indicated that BLL were not related to age or gender as there was no significant difference in the BLL of males and females in the study group (Von Schirnding et al., 2003).

• Possible mitigation actions for lead exposure Should contamination levels warrant it there are various actions that could be implemented to reduce environmental lead exposure, especially in children, including the establishment of national surveillance and screening programs; developing blood lead standards or action values; developing environmental lead standards or guidelines; removing lead from petrol, pigments and paints; as well as establishing soil abatement and personal and environmental hygiene programs.

Testing the level of lead in children is a key prevention strategy as many children with elevated BLL may not yet be displaying any symptoms allowing for preventative measures to be taken (Meyer et at., 2005). Programs need to be put into operation to identify and reduce the dangers to children from lead-based paint in old houses or on old toys. Comprehensive educational programs are required to improve public and health practitioners’ awareness of the dangers of lead exposure and possible sources and mechanisms of exposure of environmental lead.

These steps have been taken in many developed countries and have successfully resulted in the decrease of BLL in children in these countries (Harper et al., 2002).

The treatment for lead poisoning is called chelation therapy, which is most effective for metal poisoning, like plumbism (lead poisoning). This treatment is initiated only after the source of the lead exposure has been removed. The best way to prevent plumbism is to avoid exposure to lead (Chua, 2003).

Lead in water supplies can easily be removed through conventional water treatment method of coagulation with alum, ferric salts or lime followed by settlement and filtration, should levels rise above the TWQR. Careful monitoring to ensure removal is complete is required for the coagulation or flocculation process. Generated by the process is a watery sludge that contains lead (DWAF, 1996), this sludge should be correctly disposed of to ensure no environmental lead contamination.

APPENDIX III

Map coordinates of solid and water samples collected from the Edendale Lead Mime and surrounding areas

Solid sample Location coordinates Water sample Location coordinates Northern side of R513 25°41’01.9” S 25°41’01.4” S RS1_RS2 RW1 28°26’04.2” E 28°26’12.8” E 25°41’01.7” S 25°41’01.9” S RS3 NW1 28°26’07.0” E 28°26’07.4” E 25°41’02.0” S 25°40’56.7” S RS4_RS5 NW7 28°26’07.7” E 28°25’42.0” E 25°41’02.7” S RS6 28°26’07.9” E 25°41’3.3” S RS7 28°26’07.4” E 25°41’04.0” S RS8 28°26’12.6” E Southern side of the R513 25°41’04.3” S 25°41’25.9” S RS9 RW2_RW3_NW5 28°25’38.5” E 28°26’30.2” E 25°41’07.8” S 25°41’44.1” S RS10-RS16 RW4_NW4 28°25’41.2” E 28°26’49.3” E 25°41’19.3” S RW6_NW6 28°26’51.7” E 25°41’05.3” S RW7_NW2 28°25’36.0” E 25°41’07.5” S RW10_NW3 28°25’37.3” E 25°40’41.3” S RW8_NW8 28°24’04.9” E

APPENDIX IV

Element concentration ranges and their effects on human health, indicating the Target Water Quality Range (adapted from DWAF, 1996)

Element Conc. Range Effects TWQR No health effects or scaling evident. Possible corrosive effects < 16 mg/L Calcium 0-32 (mg/L) 32 - 80 No health effects. Increased scaling problems. Lathering of soap impaired > 80 No health effects. Severe scaling problems. Lathering of soap severely impaired Barium Not available TWQR No bitter taste. No scaling problems. No health effects 0 - 30 30 - 50 No bitter taste. Slight scaling problems may occur. No health effects 50 - 70 No bitter taste; No health effects or scaling problems Magnesium Slight bitter taste. Taste threshold for magnesium is 70 mg/L. Scaling problems. Diarrhoea in 70 - 100 (mg/L) sensitive users Water aesthetically unacceptable because of bitter taste. If sulphate present Increased scaling 100 - 200 problems. Diarrhoea in most new users 200 - 400 Severe scaling problems. Diarrhoea in all new users > 400 Severe scaling problems. Diarrhoea in all new users. Health problems may occur TWQR No observable health effect. Recommended that the TWQR not be exceeded because of 0 - 5 the potentially acute and/or irreversible effects of cadmium on human health No observable health effects, unless zinc nutritional status is suboptimal, or in smokers, where 5 - 10 Cadmium there is a slight risk of subclinical effects on long-term exposure (μg/L) Threshold for health damage with continuous exposure. Single incidence of exposure will not 10 - 20 have observable effects Danger of kidney damage with long-term exposure. Brief exposure, for less than one week 20 - 1 000 should not cause any noticeable damage. Exposure should not exceed one week > 1 000 Danger of acute cadmium poisoning, with the possibility offatalities TWQR No health or aesthetic effects 0 - 1 No health effects. Astringent taste and staining of laundry and plumbing fixtures start Copper 1 - 3 appearing (mg/L) 3 - 30 No health effects. Severe taste and staining problems 30 - 200 Gastrointestinal irritation, nausea and vomiting. Severe taste and staining problems > 200 Severe poisoning with possible fatalities. Severe taste and staining problems TWQR No aesthetic or health effects 0 - 100 100 - 200 Faintly salty taste. Threshold for taste. No health effects 200 - 400 Slightly salty taste. Undesirable for persons on a sodiumrestricted diet Distinctly salty taste. No health effects in healthy adults with short-term use. Undesirable for 400 - 600 Sodium infants or persons on a sodium-restricted diet (mg/L) Very salty taste. Health effects may be expected. Very undesirable for infants or persons on a 600 - 1 000 sodium-restricted diet 1 000 – Highly salty taste. Likelihood of nausea and vomiting. Highly undesirable for infants or persons 5 000 on a sodiumrestricted diet Extremely salty taste becoming bitter. Severe health effects with disturbance of electrolyte > 5 000 balance. Extremely undesirable for infants or persons on a sodium-restricted diet TWQR No aesthetic or human health effects 0 - 3 3 - 5 Slight opalescence or bitter taste. No health effects 5 - 10 Clearly discernable bitter taste and opalescence. No health effects Zinc 10 - 50 Bitter taste; strong opalescence. Some instances of chronic toxicity expected (mg/L) Bitter taste; milky appearance. Acute toxicity with gastrointestinal irritation, nausea and 50 - 700 vomiting Bitter taste; milky appearance. Severe, acute toxicity with electrolyte disturbances and > 700 possible renal damage

Element Conc. Range Effects TWQR No aesthetic (bitter taste) or health effects 0 - 50 No aesthetic effects. No health effects in healthy adults. Undesirable concentration for infants 50 - 100 or persons with renal disease Potassium Bitter taste may be noticeable. Electrolyte disturbances disease may occur in sensitive (mg/L) 100 - 400 individuals. Dangerous concentration for infants or persons with renal Pronounced bitter taste. Occurrence of electrolyte disturbances with nausea, vomiting and > 400 irritation of mucous membranes. Dangerous concentration for infants or persons with renal disease No danger of any adverse effects by exposure from water. Recommended that the TWQR TWQR not be exceeded due to the potentially acute and/or irreversible effects of lead 0 – 10 on human health No danger of any adverse health effects except for a slight risk of behavioural changes and 10 - 50 possibility of neurological impairment, where the exposure to lead from other sources, such as Lead food, is not minimised (µg/L) Possible neurological damage where the nerve and brain tissues are developing, that is, in 50 - 100 fetuses and young children. Young children and pregnant women should avoid exposure Definite danger of neurological impairment in children Alternative water supply should be used 100 - 300 by sensitive groups (children and pregnant women) > 300 Symptoms of chronic lead poisoning are possible with continuous exposure The concentration in water necessary to meet requirements for healthy tooth structure is a function of daily water intake and hence varies with annual maximum daily air TWQR temperature. A concentration of approximately 0.75 mg/L corresponds to a maximum 0 - 1.0 daily temperature of approximately 26 EC - 28 EC. No adverse health effects or tooth damage occurs Slight mottling of dental enamel may occur in sensitive individuals. No other health effects are 1.0 - 1.5 expected The threshold for marked dental mottling with associated tooth damage due to softening of 1.5 - 3.5 enamel is 1.5 mg/L Above this, mottling and tooth damage will probably be noticeable in most continuous users of the water. No other health effects occur Fluoride Severe tooth damage especially to infants' temporary and permanent teeth; softening of the (mg/L) enamel and dentine will occur on continuous use of water. Threshold for chronic effects of 3.5 - 4.0 fluoride exposure, manifested as skeletal effects. Effects at this concentration are detected mainly by radiological examination, rather than overt Severe tooth damage especially to the temporary and permanent teeth of infants; softening of 4.0 - 6.0 the enamel and dentine will occur on continuous use of water. Skeletal fluorosis occurs on long-term exposure 6.0 – 8.0 Severe tooth damage as above. Pronounced skeletal fluorosis occurs on long-term exposure Severe tooth damage as above. Crippling skeletal fluorosis is likely to appear on long-term > 8.0 exposure > 100 Threshold for onset of acute fluoride poisoning, marked by vomiting and diarrhoea > 2 000 The lethal concentration of fluoride is approximately 2 000 mg/L TWQR No aesthetic or health effects. The threshold for corrosion acceleration in domestic 0 - 100 appliances is at 50 mg/L 100 - 200 No aesthetic or health effects. Possible increase in the corrosion rate in domestic appliances Water has a distinctly salty taste, but no health effects. Likelihood of noticeable increase in Chloride 200 - 600 corrosion rates in domestic appliances (mg/L) Water has objectionable salty taste and will not slake thirst. Likelihood of rapid corrosion in 600 - 1 200 domestic appliances Water unacceptably salty. Nausea and disturbance of the electrolyte balance can occur, > 1 200 especially in infants, where fatalities due to dehydration may occur TWQR Quality No adverse health effects 0 – 6 Nitrate/Nitrite Rare instances of methaemoglobinaemia in infants; no effects in adults. Concentrations in this 6 - 10 (mg/L) range generally well tolerated 10 - 20 Methaemoglobinaemia may occur in infants. No effects in adults > 20 Methaemoglobinaemia occurs in infants. Occurrence of mucous membrane irritation in adults Bromimum Not available Phosphate Not available

Element Conc. Range Effects TWQR No health or aesthetic effects are experienced 0 - 200 Tendency to develop diarrhoea in sensitive and some non-adapted individuals. Slight taste Sulphate 200 - 400 noticeable (mg/L) 400 - 600 Diarrhoea in most non-adapted individuals. Definite salty or bitter taste 600 - 1 000 Diarrhoea in most individuals. Pronounced salty or bitter taste User-adaptation does not occur. > 1 000 Very strong salty and bitter taste Diarrhoea in all individuals. User-adaptation does not occur. TWQR No health effects expected, ideal concentration range 0 - 10 Tolerable concentration but low risk of skin cancer in highly sensitive individuals over long 100 - 200 term Human health is seriously at risk if 200 mg/L is exceeded in potable water. Increasing 200 - 300 possibility of mild skin lesions over long term, slight possibility of induction of skin cancer over Arsenic long term (µg/L) Possible adverse, chromic effects in sensitive individuals; brief exposure has no effect; skin 300 - 600 lesions, including hyperpigmentation, will begin to appear on long term exposure Symptoms of chronic poisoning such as skin lesions, including hyperpigmentation, will appear 600 – 1 000 on long-term exposure 1 000 – 10 000 Cancer or death will result from chronic poisoning > 10 000 Death will result from acute poisoning < 4.0 Severe danger of health effects due to dissolved toxic metal ions. Water tastes sour Toxic effects associated with dissolved metals, including lead, are likely to occur at a pH of 4.0-6.0 less than 6. Water tastes slightly sour No significant effects on health due to toxicity of dissolved metal ions and protonated species, or on taste are expected. Metal ions (except manganese) are unlikely to TWQR dissolve readily unless complexing ions or agents are present. Slight metal solubility pH Range 6.0-9.0 may occur at the extremes of this range. Aluminium solubility begins to increase at pH (pH unit) 6, and amphoteric oxides may begin to dissolve at a pH of greater than 8.5. Very slight effects on taste may be noticed on occasion Probability of toxic effects associated with deprotonated species (for example, ammonium 9.0-11.0 deprotonating to form ammonia) increases sharply. Water tastes bitter at a pH of greater than 9 Severe danger of health effects due to deprotonated species. Water tastes soapy at a pH of > 11.0 greater than 11

APPENDIX V

XRF data using Shale PPow program

SPECTRAU, University of Johannesburg 03/07/2006 13:02:17 PM Results quantitative - Shales PPow2 Shales Selected archive: PPow2 Number of results selected: 24

Sample Seq. Type Application Meas. date/time name or Instrument

monitor or Calibration

update

9 RS1 R Shales PPow2 30/06/2006 12:44 10 RS2 R Shales PPow2 30/06/2006 13:13 11 RS3 R Shales PPow2 30/06/2006 13:42 12 RS4 R Shales PPow2 30/06/2006 14:10 13 RS5 R Shales PPow2 30/06/2006 14:38 14 RS6 R Shales PPow2 30/06/2006 15:07 15 RS7 R Shales PPow2 30/06/2006 15:36 16 RS8 R Shales PPow2 30/06/2006 16:04 17 RS9 R Shales PPow2 30/06/2006 16:33 18 RS10 R Shales PPow2 30/06/2006 17:02 19 RS11 R Shales PPow2 30/06/2006 17:31 20 RS12 R Shales PPow2 30/06/2006 18:00 21 RS13 R Shales PPow2 30/06/2006 18:28 22 RS15 R Shales PPow2 30/06/2006 18:57 23 RS16 R Shales PPow2 30/06/2006 19:25

Sample name Initial Final Loss On Sum Weight (g) Weight (g) Ignition (%) of conc. (%) RS1 9.6 12 57.137 RS2 9.6 12 64.761 RS3 9.6 12 67.84 RS4 9.6 12 64.607 RS5 9.6 12 66.006 RS6 9.6 12 56.502 RS7 9.6 12 61.204 RS8 9.6 12 78.61 RS9 9.6 12 73.419 RS10 9.6 12 36.735 RS11 9.6 12 42.865 RS12 9.6 12 28.885 RS13 9.6 12 54.139 RS15 9.6 12 32.149 RS16 9.6 12 46.749 Sample Result type Ba Co Cr Cu Ga Nb name (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)

RS1 Concentration 86.9 6.6 149.8 21.8 -187.5 2.8 RS2 Concentration 65.6 15.1 127.3 74.1 -85.5 2.9 RS3 Concentration 129.9 31.4 133.6 54.8 -17.3 3.9 RS4 Concentration 170.7 23.5 149.9 93.7 -16.5 6.9 RS5 Concentration 137.4 30.6 81.2 101.6 -184.1 2.1 RS6 Concentration 62.2 18.5 52.8 163.3 -274 1.2 RS7 Concentration 116 16.8 314.5 93.9 -103.8 2.5 RS8 Concentration 100.8 6.4 238.4 3.9 5 6.4 RS9 Concentration 153.2 10.1 209.7 7.1 4.3 3.8 RS10 Concentration 8.2 29.6 40.2 2793.6 -351.9 0.5 RS11 Concentration 64.7 19.2 145.9 439.4 -297.6 1.7 RS12 Concentration 37.7 17.5 133.6 390.3 -409.5 1 RS13 Concentration 38.4 18.2 237 378.1 -280.9 1.6 RS15 Concentration 39.6 23.9 225.6 481.4 -393.4 1.2 RS16 Concentration 3.8 7.3 104.4 771.2 -306.5 1.5

Sample Ni Pb Rb Sr Th V Y name (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)

RS1 2.5 6165 58.7 -23.9 27.5 37.1 -1068.5 RS2 29.9 3468.5 91.1 -10.3 10.5 53.8 -592.6 RS3 45.7 1242.8 129 3.8 9.2 41.2 -208.6 RS4 22.4 1138.2 120.8 65 6.7 41.7 -183.3 RS5 28.9 6720.6 114 -23 31.7 65.4 -1176.5 RS6 18.6 9171.3 87.7 -39.9 40.6 58.1 -1564.6 RS7 43 3956.8 54.4 -11.2 13.8 108.9 -670.3 RS8 6.5 23.7 32.4 10.9 3.5 24.1 7.2 RS9 20.1 71.1 27 31.1 4 12.6 -1.9 RS10 7.7 9325.5 43.2 -37.1 27.6 3.2 -1545.7 RS11 19 9766.1 56.3 -24.5 20.7 17.2 -1631.7 RS12 15.4 13331.3 61.3 -48.7 62 43.2 -2130.6 RS13 24.8 9014.5 52.9 -36.5 30.9 25.3 -1571.1 RS15 35.8 12694.3 62.8 -53.4 52.9 89.3 -2100.2 RS16 26.5 10448.9 60.1 -40.3 22.2 19.5 -1822.1

Sample Zn Zr Sc U name (ppm) (ppm) (ppm) (ppm)

RS1 201.8 147.8 8.9 -1.4 RS2 5987.5 84.9 13.9 0.1

RS3 1230.7 97.5 17.7 0.7 RS4 1056 136.2 11.8 1.6 RS5 3371 112.3 15.8 0.8 RS6 4467.6 102.8 21.7 0.4 RS7 5289.3 104.4 6.9 1.3 RS8 45.3 188.9 7.7 0.7 RS9 103.4 93.8 9.6 0 RS10 31970.6 78.3 4.5 0.5 RS11 22556.2 110.7 5.1 0 RS12 23011 138.2 5.2 -1.4 RS13 12901.1 120.6 6.4 0.9 RS15 26996.5 128 6.8 0.9 RS16 25032 122.5 6.8 -1.2