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Potentially Harmful Trace Elements (PHTEs) in the groundwater of Greater Giyani, Limpopo Province, South Africa: possible health implications By LIVHUWANI PORTIA MUNYANGANE A dissertation submitted in fulfilment of the requirements for the Degree of Master in Geology (MSc Geology) in Medical Geology Department of Geology Faculty of Science UNIVERSITY OF JOHANNESBURG Supervisor: Prof. Hassina Mouri Co-Supervisor: Prof. Jan Kramers 2015 ABSTRACT Most rural communities in developing countries rely on borehole water as their only source of water. Since borehole water comes from underground, it is often considered pure and clean, but this is frequently not the case. Groundwater contains certain amounts of trace elements that may become deleterious to human health. The objectives of this investigation were to assess the concentration levels of Potential Harmful Trace Elements (PHTEs) and their spatial distribution patterns in borehole water in the Greater Giyani area of Limpopo, South Africa, and the potential human health risks associated with this. The method of research comprised two phases: (I) In the first phase, I assessed the occurrence and distribution patterns of PHTEs in the boreholes of the Giyani area. A total of 29 water samples were collected from boreholes (including 15 community boreholes and 14 primary school boreholes) in the Greater Giyani area during the dry season (July/August 2012), and for comparison another 27 samples (including 15 community boreholes and 12 schools boreholes) from the same localities during the wet season (March 2013). The samples were analysed for the trace elements arsenic (As), cadmium (Cd), chromium (Cr), selenium (Se) and lead (Pb) using the Inductively Coupled Plasma Mass-Spectrometry (ICPMS) technique. In order to assess the groundwater quality, PHTEs concentrations were compared with the South African National Standard of Drinking water (SANS 241-1:2011). (II) In the second phase, I evaluated the geographic variation between PHTEs and associated human health effects. This involved acquisition of data on a total of 100 cancer cases recorded during the period 2011-2014 at Nkhensani Hospital. ArcGIS Spatial analyst tool was used to create thematic maps illustrating spatial distribution of clinical data and arsenic concentrations in boreholes. The concentrations of As, Cd, Cr, Se and Pb varied from 4.0 to 112.3, 0.2 to 0.9, 10.5 to 69.5, 0.4 to 18.8 and 6.0 to 19.0 µg/l respectively. Cadmium displayed a low concentration in all sampled boreholes, whereas lead was found to be present at limits of detection in 96.6 % of sampled boreholes. Concentrations of As, Cr, and Se, however, exceed the SANS i permissible limits for drinking water in more than one borehole. Nearly 13 % of boreholes in the area had an arsenic concentration of more than two times the SANS permissible limit for drinking water with two samples containing five times more arsenic than the SANS acceptable limit. Two significant “hotspots” of cancer incidence rates were identified in the north-central part of the study area however; none of the As- contaminated boreholes coincide with the hotspots with highest cancer incidence rates. ii I dedicate this work to Mpho, the apple of my eye. iii ACKNOWLEDGEMENT I am indebted to my supervisor Prof Hassina Mouri and co-supervisor Prof Jan Kramers for their support and guidance, without them this dissertation would not have been possible. I cannot find words to express my deepest gratitude to Prof Davies who walk with me during the initial stages of this research. Many thanks. I wish to thank my Manager Mr Nick Baglow for his continuous support. I owe my deepest gratitude to my lovely sister for her endless love, support and encouragement. You are my rock. Tebogo Maja, Mr Philemon Mashao and Ponani Mthembi I greatly appreciate your excellent assistance during field work; you were amazing to work with. Hilde Cronwright, thank you for your technical assistance in the lab and assisting in writing up the laboratory analysis section, many sincere thanks. I would also want to express my gratitude and deepest appreciation to all who helped me to complete this work but not mentioned here. I am thankful to the Council for Geoscience for the financial support. Above all I would like to thank God the almighty for granting me the endurance to successfully complete this work. iv Table of Contents page no ABSTRACT ............................................................................................................................... i ACKNOWLEDGEMENT ...................................................................................................... iv LIST OF FIGURES ............................................................................................................. viii LIST OF TABLES ................................................................................................................... x CHAPTER 1: INTRODUCTION ........................................................................................... 1 1.1. Aims and objectives ................................................................................................... 2 1.2. Research methodology .............................................................................................. 3 1.2.1. Desktop study ..................................................................................................... 3 1.2.2. Field reconnaissance survey and findings ....................................................... 4 1.2.3. Borehole water sampling ................................................................................... 7 1.2.4. Laboratory analysis ........................................................................................... 9 1.2.5. Clinical health data acquisition ...................................................................... 12 1.2.6. Ethical consideration ....................................................................................... 13 1.2.7. Clinical data analysis ....................................................................................... 14 CHAPTER 2: LITERATURE REVIEW ........................................................................ 18 2.1. Introduction ................................................................................................................. 18 2.2. Trace elements ............................................................................................................. 18 2.2.1. Arsenic (As) .......................................................................................................... 18 2.2.1.1. Mechanism of control of arsenic concentrations and mobility in groundwater ................................................................................................................... 20 2.2.1.2. Arsenic health effects ........................................................................................ 22 2.2.2. Cadmium (Cd) ...................................................................................................... 23 2.2.2.1. Cadmium health effects .................................................................................... 25 2.2.3. Chromium (Cr) .................................................................................................... 25 2.2.3.1. Chromium health effects .................................................................................. 27 2.2.4. Lead (Pb)............................................................................................................... 27 2.2.4.1. Lead health effects ............................................................................................ 28 2.2.5. Selenium (Se) ........................................................................................................ 28 2.2.5.1. Selenium health effects ..................................................................................... 30 2.3. Previous studies on groundwater quality in Limpopo province ............................. 31 v 2.4. Conclusion ................................................................................................................... 33 CHAPTER 3: CASE STUDY: PHTES IN THE GREATER GIYANI AREA, POSSIBLE RELATION BETWEEN GEOLOGY AND HEALTH ................................. 34 3.1. Introduction ................................................................................................................. 34 3.1.1. Climate .................................................................................................................. 35 3.1.2. Population and water supply in the Greater Giyani area ................................ 35 3.2. The geology of the Greater Giyani area .................................................................... 37