Assessment of Polycyclic Aromatic Hydrocarbon (PAHs)

223 Pages·2013·3.28 MB·English

Assessment of Polycyclic Aromatic Hydrocarbon (PAHs) and Heavy
Metals in the Vicinity of Coal Power Plants in South Africa

By

OLUMUYIWA OLAKUNLE OKEDEYI

Submitted in accordance with the requirements
for the degree of
Doctor of Philosophy
In Chemistry
at the
UNIVERSITY OF SOUTH AFRICA

SUPERVISOR: PROFESSOR M.M. NINDI
CO-SUPERVISORS: PROFESSOR O.R. AWOFOLU
: DR S. DUBE

NOVEMBER 2012
I declare that ASSESSMENT OF POLYCYCLIC AROMATIC HYDROCARBON (PAHs)
AND HEAVY METALS IN THE VICINITY OF COAL POWER PLANTS IN SOUTH
AFRICA is my own work and that all the sources that I have used or quoted have been
indicated and acknowledge by means of complete references.

---------------------------------------------------------
SIGNATURE ----------------------------
(MR O O OKEDEYI, Student # 43287603) DATE

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The following papers are based on this thesis.

Okedeyi, O.O., Nindi, M.M., Dube, S. & Awofolu, O.R (2013). Distribution and
potential sources of polycyclic aromatic hydrocarbons in soils around coal-fired power
plants in South Africa. Environmental Monitoring and Assessment. 185: 2073 – 2082.
Published by Springer

Okedeyi, O.O., Dube, S., Awofolu. O.R. & Nindi, M. M. Assessing the enrichment of
heavy metals in surface soil and plants (Digitaria eriantha) around coal-fired power
plants in South Africa. In press in the Journal of Environmental Science and
Pollution,Research. Published by Springer

Okedeyi., O.O., Dube., S., Awofolu., O.R. & Nindi, M. M.. Determination of polycyclic
aromatic hydrocarbons (PAHs) in soil by ultrasonic extraction assisted with dispersive
liquid-liquid microextraction and gas chromatography-mass selective detection. Paper
under preparation for submission

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DEDICATION

This piece of work is dedicated to my jewels of inestimable value, Josephine, Bolu,
Femi and Teni.

To the Okedeyis, Osideles, Olorunfunmis, Jembis, and the Aigbes. And lastly to
Jehovah God with whom all things are possible, for letting me live to complete this work.

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ACKNOWLEDGEMENTS

My greatest thanks goes to Jehovah God, with whom all things are possible, for letting
me live to complete this work.

I wish to thank Professor Mathew Muzi Nindi for his supervision, guidance and
understanding throughout the work. My special thanks also go to Professor Omotayo
Awofolu and Dr Simiso Dube for their encouragement, constructive criticism and co-
supervision. would like to extend my appreciation to all members of staff of chemistry
department, UNISA, and especially the Analytical Chemistry Research group G26
(Dineo, Tebza, Cicilia, Vuyo, Vusa, Vimbai and Tshabalala) for their support as well.
My thanks will be incomplete if I fail to thank Professor and Dr (Mrs) Adeniyi for their
encouragement to pursue the programme. I would like to thank the VP research and
innovation, the former executive Dean of College of Engineering and Technology for
partial financial support that I received during my studies.

To my other colleagues and friends at UNISA (Olowoyos, Adegbites, Deolu, Eriwu, Moji,
Oyeyiola, Kenedy, Mathins, Ginet, Papo, Shadi and others) I say thank you. My special
thanks also go to the Lagos State Scholarship Board for its financial support. I say thank
you.

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TABLE OF CONTENTS
Front PageDeclaration ii
Publications based on the thesis iii
Dedication iv
Acknowledgments vi
CHAPTER ONE 1

1.0 Introduction and Literature Review 1
1.1 Background information 1
1.2. What are PAHs?
1.3 Human health 6
1.4 Chemistry of PAHs 6
1.5 Aromaticity 7
1.6 Physical and chemical characteristics of PAHs 9
1.7 Occurrence and pollution of PAHs 10
1.8 Environmental fate 12
1.9 Carcinogenicity 12
1.10 Sources and emission of PAHs 16
1.11 Stationary sources 16
1.11.1 Domestic sources 16
1.11.2 Industrial sources 17
1.12 Mobile sources 18
1.13. Agricultural sources 19
1.14 Natural sources 20
1.15 Coal in South Africa 20
1.16 Coal and electricity 24
1.17 Major domestic coal consumers in South Africa 25
1.17.1 Eskom’s coal-fired power stations 25
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1.17.2 Sasol 26
1.17.3 Industrial and residential coal consumption 27
1.18 Climate change concerns 27
1.19 Source identification of PAHs 28
1.20 PAH composition stability 29
1.21 PAH compound profiles in soil 32
1.22 Toxicokinetics 37
1.22.1 Absorption 37
1.22.2 Distribution PAHs within organism 38
1.22.3 Excretion 39
1.23 PAH formation and emission mechanisms 39
1.24 Routes of exposure for PAHs 40
1.25 Standards and regulations for exposure to PAHs 43
1.26 Toxicity equivalency factors of PAHs 44

CHAPTER TWO
2.0 Literature Review 46
2.1 Air sampling and methods of analysing PAHs 46
2.1.1 PAH sampling equipment 46
2.1.2 Pretreatment of air samples 48
2.1.3 Extraction, concentration and analysis of PAHs 48
2.2 Typical urban and rural concentrations of PAHs 49
2.3 Extraction techniques for PAHs in soil 51
2.3.1 Soxhlet extraction 52
2.3.2 Ultrasonication 54
2.3.3 Mechanical agitation 55
2.3.4 Supercritical and subcritical fluid extraction 56
2.3.5 Microwave-assisted extraction (MAE) 57
2.3.6 Dispersive liquid-liquid microextraction 58
2.3.7 Pressuried hot water extraction (PHWE) 59
2.4 Hazardous air pollution emission 60
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2.4.1 Toxicological effect of the emissions of coal power plants 61
2.5 Health and environmental impact of coal power plants 64
2.5.1 Dioxins 64
2.5.2 Radioisotopes 65
2.5.3 Mercury 65
2.5.4 Non-mercury metals 66
2.5.4.1 Cadmium 67
2.5.4.1a Cadmium in the environment 67
2.5.4.1b Exposure to cadmium 67
2.5.4.2 Lead 68
2.5.4.2a Lead in the environment 69
2.5.4.2b Exposure to lead 69
2.5.4.2c Health effects of lead 69
2.5.4.3 Chromium 70
2.5.4.3a Exposure to chromium 70
2.5.4.3b Health effects of chromium 70
2.5.4.4 Copper 71
2.5.4.4a Copper in the environment 71
2.5.4.4b Exposure to copper 71
2.5.4.4c Health effects of copper 72
2.5.4.5 Manganese 72
2.5.4.5a Manganese in the environment 73
2.5.4.5b Health effects of manganese 73
2.5.4.6 Zinc 74
2.5.4.6a Zinc in the environment 74
2.5.4.6b Health effects of zinc 74
2.5.4.7 Nickel 75
2.5.4.7a Nickel in the environment 76
2.5.4.7b Exposure to nickel 76
2.5.4.7c Health effects of nickel 76
2.6 Transport of hazardous materials from coal-fired plant 77
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CHAPTER THREE
RESEARCH METHODOLOGY 81
3.0 Materials and Method 81
3.1: Description of study area 81
3.2: Materials and reagent 82
3.3: Soil samples 83
3.4: Soxhlet extraction procedure 85
3.5: GC-MS of PAHs 85
3.6 Ultrasonic extraction procedure 87
3.7: Ultrasonic – DLLME extraction procedure 88
3.8: Metal analysis 92
3.9: Instrumentation 92
3.10: Reagent and quality assurance 93
3.11: Statistical analysis 94

CHAPTER FOUR
RESULTS
4.0 Results and Discussion 96
4.1 Results and discussion of PAH 96
4.1.1 Discussion on PAHs 96
4.1.2 Sources of PAHs 106
4.1.3 Correlation analyses 107
4.1.4 Estimation of carcinogenic potency 111
4.1.5 ANOVAs and Pearson correlation (r) of individual PAH in
Soil and in plant Digitaria eriantha in the three power plants 112
4.1.6 Seasonal variability of PAH concentration 115
4.2 Results and discussion on Metals 119
4.2.1 Soil PH and organic matter 119
4.2.2 Estimating impact of pollution by metals in soil 127
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4.2.2a Enrichment factor 127
4.2.2b Index of geo-accumulation 129
4.2.3 Metal pollution Index 133
4.2.4 Accumulation factor 133
4.3 Results and discussion on Ultrasonic DLLME 139
4.3.1 Selection of good dispersive solvent 139
4.3.2 Selection of good extraction solvent 141
4.3.3 Effect of ultrasonic-DLLME extraction time 142
4.3.4 Effect of extraction solvent in ultrasonic DLLME 144
4.3.5 Comparison of Soxhlet extraction with ultrasonic assisted
DLLME extraction 145
4.3.6 Real sample analysis using the AU-DLLME method 147

CHAPTER FIVE
CONCLUSIONS
5.0 Conclusions and Recommendations for Further Studies 156
5.1 Conclusions 156
5.2: Recommendations for further studies 158
References 159

APPENDICES
Appendix 1: 197
Appendix 2: 198
Appendix 3: 199
Appendix 4a: 200
Appendix 4b: 201
Appendix 5: 202

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