HEAVY METALS IN INDOOR SETTLED DUSTS IN TORONTO, CANADA by Ahmed Al Hejami MSc ...

64 Pages·2014·1.16 MB·English

HEAVY METALS IN INDOOR SETTLED DUSTS IN TORONTO, CANADA

by
Ahmed Al Hejami
MSc. in Chemistry, Al-Nahrain University, Baghdad, Iraq, 1995

A thesis
presented to Ryerson University
in partial fulfillment of the
requirements for the degree of
Master of Science
in the program of
Molecular Science

Toronto, Ontario, Canada, 2014
© Ahmed Al Hejami, 2014
AUTHOR’S DECLARATION

AUTHOR’S DECLARATION FOR ELECTRONIC SUBMISSION OF A THESIS
I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including
any required final revisions, as accepted by my examiners.
I authorize Ryerson University to lend this thesis to other institutions or individuals for the
purpose of scholarly research.
I further authorize Ryerson University to reproduce this thesis by photocopying or by other
means, in total or in part, at the request of other institutions or individuals for the purpose of
scholarly research.
I understand that my thesis may be made electronically available to the public.

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ABSTRACT
HEAVY METALS IN INDOOR SETTLED DUSTS IN TORONTO, CANADA
Ahmed Al Hejami
Master of Science, Molecular Science, Ryerson University, 2014

Total concentrations of nine potentially toxic heavy metals (Ba, Cd, Cr, Cu, Hg, Mn, Ni,
Pb, and Zn) in indoor settled dusts from houses, offices, classrooms, and laboratories in Greater
Toronto Area, Canada were determined. Mercury concentrations were determined using cold
vapor atomic fluorescence spectroscopy (CVAFS), whereas the concentrations of eight other
metals were determined using inductively coupled plasma atomic emission spectroscopy (ICP-
AES). The results showed that the highest level of heavy metals was in the laboratory dusts.
Metal concentrations (except those for Mn and Zn) in household, office, and classroom dusts
were comparable. Cd, Cr, Cu, Ni, and Zn concentrations in the laboratory dusts and Cu and Zn
concentrations in household, office, and classroom dusts exceeded the Canadian Soil Guideline.
Metal concentrations in the indoor dusts found in this study were, in general, consistent with
those reported in literature. Among the metals studied, Cd, Cu, Hg, Pb, and Zn showed the
greatest enrichment in the indoor environments relative to their crustal abundances.

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ACKNOWLEDGEMENT

I would like to express my sincere thanks and gratitude to my supervisor, Dr. Julia Lu,
for her valuable guidance, encouragement, and help throughout my research. I want to thank my
supervisory committee members, Dr. Darrick Heyd, Dr. Daniel Foucher, and Dr. Stephen Wylie,
for their feedback and suggestions. I extend my thanks to Dr. Russell Viirre for serving on my
examining committee and Dr. Andrew McWilliams for chairing my thesis defense. The help of
the previous graduate student in Dr. Lu’s lab, Muhammad Yousaf, is also gratefully
acknowledged. Furthermore I would like to thank the Molecular Science Graduate Program,
Ryerson University for allowing me to conduct my research and providing any assistance
requested. I also want to thank Natural Sciences and Engineering Research Council of Canada
(NSERC) and Canada Foundation for Innovation (CFI) for their financial support. At the end
special thanks go to my wife, Halla Majeed, for her constant love and support throughout my
study.

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DEDICATION

I would like to dedicate my thesis to my wife, Halla, my daughter, Sura, and my son, Hussain.

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TABLE OF CONTENTS

AUTHOR’S DECLARATION.......................................................................................................ii
ABSTRACT...................................................................................................................................iii
ACKNOWLEDGEMENT..............................................................................................................iv
DEDICATION................................................................................................................................v
LIST OF TABLES.......................................................................................................................viii
LIST OF FIGURES........................................................................................................................ix
LIST OF ABBREVIATIONS........................................................................................................xi
1. INTRODUCTION .......................................................................................................................1
1.1. Composition of indoor settled dusts ......................................................................................1
1.2. Sources of heavy metals in indoor settled dusts ...................................................................2
1.3. Heavy metal exposure pathways ...........................................................................................3
1.4. Health effects of heavy metals ..............................................................................................4
1.5. Literature survey of concentrations of heavy metals in indoor settled dusts ........................4
1.6. Study objectives ....................................................................................................................7
2. MATERIALS AND METHODS .................................................................................................8
2.1. Sample collection and preparation ........................................................................................8
2.2. Cleaning glassware ...............................................................................................................9
2.3. Sample analysis ..................................................................................................................10
2.3.1. Sample digestion .......................................................................................................10
2.3.2. Metal analysis using ICP-AES .................................................................................11
2.3.3. Hg analysis using CVAFS .......................................................................................14
2.3.3.1. Preparation of reagents .................................................................................14
2.3.3.2. Determination of total Hg ............................................................................14
2.4. Quality control (QC) ...........................................................................................................17
2.4.1. Blanks ........................................................................................................................17
2.4.2. Method detection limit ..............................................................................................18
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2.4.3. Method validation .....................................................................................................18
2.4.4. Calibration verification .............................................................................................20
2.5. Statistical analysis ...............................................................................................................21
3. RESULTS AND DISCUSSION ...............................................................................................22
3.1 Heavy metal concentrations in household dusts ..................................................................22
3.2 Heavy metal concentrations in office, classroom, and laboratory dusts ..............................29
3.3 Comparison of the results from different indoor environments..........................................31
3.4 Comparison of the results observed in this study with literature values ..............................33
3.5 Heavy metal correlations .....................................................................................................35
3.6 Enrichment of measured metals ...........................................................................................38
4. CONCLUSIONS........................................................................................................................40
5. FUTUR WORK .........................................................................................................................41
APPENDIX....................................................................................................................................42
REFERENCES ..............................................................................................................................48

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LIST OF TABLES

Table 1. Recovery and precision for the determination of metals in SRM 2584 (NIST, Trace
Element in Indoor Dust) using ICP-AES .............................................................................. 19
Table 2. Total metal concentrations (mg kg-1, dry weight) in the household dust samples
collected in GTA, Canada ..................................................................................................... 23
Table 3. Total metal concentrations (mg kg-1, dry weight) in dust samples collected from offices,
classrooms, and laboratories in CTA, Canada ....................................................................... 30
Table 4. Comparison of the arithmetic mean concentrations (mg kg-1) of heavy metals in indoor
dusts presented in this study with those reported in literature............................................... 34
Table 5. Inter-metal correlations for the household dusts............................................................. 36
Table 6. Inter-metal correlations for the office dusts .................................................................... 36
Table 7. Inter-metal correlations for the laboratory dusts............................................................. 37
Table 8. Inter-metal correlations for the classroom dusts ............................................................. 38
Table 9. Enrichment factors for heavy metals in the indoor dust samples ................................... 39

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LIST OF FIGURES

Fig. 1. Sampling locations: (A) residential within the Greater Toronto Area (GTA), Canada.
Green and red dots represent sampling locations in the winter of 2012 and 2013,
respectively; (B) non-residential in the downtown Toronto ................................................... 8
Fig. 2. Sample collection surfaces in the indoor environments ..................................................... 9
Fig. 3. Setup for acid evaporation using a hot plate...................................................................... 11
Fig. 4. Clibration curves for heavy metal analysis using ICP-AES ............................................. 13
Fig. 5. Bubbler setup for purging and trapping of the Hg0 ........................................................... 15
Fig. 6. Apparatus setup for CVAFS analysis of the THg ............................................................. 16
Fig. 7. Comparison of the arithmetic mean concentrations of metals in the household dusts
collected in the winter of 2012 and 2013 .............................................................................. 24
Fig. 8. Geographical distribution of Ba concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 25
Fig. 9. Geographical distribution of Cd concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 25
Fig. 10. Geographical distribution of Cr concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 26
Fig. 11. Geographical distribution of Cu concentrations in the household dusts collected in the
winter of 2012 and 2013 in the GTA, Canada ....................................................................... 26
Fig. 12. Geographical distribution of Hg concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 26
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Fig. 13. Geographical distribution of Mn concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 27
Fig. 14. Geographical distribution of Ni concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 27
Fig. 15. Geographical distribution of Pb concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 27
Fig. 16. Geographical distribution of Zn concentrations in the household dusts collected in the
winter of 2012 and 2013 in GTA, Canada ............................................................................. 28
Fig. 17. Comparison of the arithmetic mean concentrations of metals in the household dusts from
downtown Toronto and other regions of GTA, canada ........................................................ 28
Fig. 18. Comparison of the arithmetic mean concentrations of metals in indoor settled dusts
collected from different indoor environments: HT = House Total; HD = House Downtown;
L = Laboratory; O = Office; C = Classroom ......................................................................... 32

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