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Phytoremediation of heavy metal contaminated sites by mining in thai nguyen province vietnam

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Phytoremediation of Heavy Metal Contaminated Sites by
Mining in Thai Nguyen Province Vietnam

Ngoc Son Hai Nguyen
(B.Sc., M.Eng.)

A thesis submitted in fulfilment of the requirements for the degree of
Doctor of Philosophy

Global Centre for Environmental Remediation (GCER)
The Cooperative Research Centre for Contamination Assessment and
Remediation of the Environment (CRC CARE)
The University of Newcastle, Australia

February, 2020
This research was supported by an Australian Government Research Training
Program (RTP) Scholarship



DECLARATION
I hereby certify that the work embodied in the thesis is my own work, conducted under
normal supervision.
The thesis contains no material which has been accepted for the award of any other degree
or diploma in any university or other tertiary institution and, to the best of my knowledge
and belief, contains no material previously published or written by another person, except
where due reference has been made in the text. I give consent to the final version of my
thesis being made available worldwide when deposited in the University’s Digital
Repository**, subject to the provisions of the Copyright Act 1986.
**Unless an Embargo has been approved for a determined period.


Ngoc Son Hai Nguyen

Signed

Date

i

22/ 02 / 2020


ACKNOWLEDGEMENTS
Firstly, I would like to express my deepest appreciation to my primary supervisor Prof Ravi
Naidu, for his guidance, encouragement, excellent advice, and kindness support during my
research. Your assistance throughout the process of research conceptualisation and design,
as well as data collection and analyses has been invaluable, and has directly contributed to
the quality of the research. Your personal work ethic has instilled in me the desire to achieve
my own goals, particularly during long days involved in data collection when I often
wondered if my research would ever truly be finished! Most importantly though, I have
enjoyed building a professional and personal friendship with you, and some of my greatest
memories from this whole PhD experience involved sharing a few quiet beers with you to
unwind after a week’s work. Thank you for all you have done for me over these past few
years. I would like to extend a massive thanks to my co-supervisor Dr Peter Sanderson for
his guidance, helpful suggestions, and encouragement. He spent many hours providing me
guidance both in the lab as well as with data analyses, statistical support and revise thesis.
Many thanks must also go to other co-supervisors, Prof Nanthi Bolan, Dr Jianhua Du and Dr
Fangjie. Your knowledge regarding the implementation of research in the real world has been
invaluable in ensuring that my thesis generates far-reaching practical applications. I am
grateful for the assistance and support of Prof Nanthi Bolan for his valuable suggestions,
guidance and encouragement. Your assistance regarding my research was helpful, particularly

guidance during expriments in the lab, glasshouse and research proposal writing up. I express
my sincere thanks to Dr Jianhua Du for his patient guidance and support for soil mineral
analysis. My sincere appreciation to Dr. Fangjie for her kind support, mentorship, statistical
support and logistic help to carry out this research. I sincerely acknowledge all the staff
members and students of GCER, UON for their cooperation and friendship during the study.
I appreciate Dr. Mahmud Rahman for providing guidance and analysis technique support
for my PhD work.
I would like to express my love and special appreciation to my bride, Thi Hang Tran who
helped me in many aspects of my work. I was inspired by her endless love and patience.
Last but not least, my loving thanks and heartfelt gratitude go to my family, especially my
father, Ngoc Nong Nguyen, and my mother, Thi Bac Do and my younger sister, Ngoc Thi
Dung Nguyen, for always being by my side and consistently encouraging me to do my
best. Special thanks to my dad, my mum, relatives and friends in Vietnam and my sister’s
ii


family in New Zealand for trusting me and being such an excellent source of support. This
thesis is dedicated to my family and my wife. Without their support, it would not have
been possible for me to finish this thesis.
Finally, I would like to acknowledge the Electron Microscope & X-Ray Unit of University
of Newcastle, Australia for SEM-EDS and XRD analysis, Inorganic Lab, GCER of
University of Newcastle, Australia for characterisation analysis and ICP-MS/ICP-EOS
analysis. Also, I extend my gratitude to the Australia Awards (AAS) scholarship and the
Cooperative Research Centre for Contamination Assessment and Remediation of the
Environment (CRC CARE) for financial support.

iii


TABLE OF CONTENTS

DECLARATION--------------------------------------------------------------------------------------------I
ACKNOWLEDGEMENTS-----------------------------------------------------------------------------II
TABLE OF CONTENTS--------------------------------------------------------------------------------IV
LIST OF ABBREVIATIONS---------------------------------------------------------------------------X
LIST OF FIGURES---------------------------------------------------------------------------------------XI
LIST OF TABLES--------------------------------------------------------------------------------------XIV
LIST OF PUBLICATIONS--------------------------------------------------------------------------XVI
ABSTRACT--------------------------------------------------------------------------------------------------1
CHAPTER 1.INTRODUCTION--------------------------------------------------------------------4
1.1. Risks of contaminated sites and remediation technologies ---------------------------------- 4
1.2. Heavy metals and causes leading to environmental pollution ------------------------------ 6
1.3. Phytoremediation -------------------------------------------------------------------------------------- 6
1.4. Heavy metal pollution in Vietnam and mining in Thai Nguyen province --------------- 7
1.5. Research using plants for phytormediation ------------------------------------------------------ 8
1.6. Research gaps ------------------------------------------------------------------------------------------- 8
1.7. Research objectives ---------------------------------------------------------------------------------- 10
1.8. Layouts of chapters ----------------------------------------------------------------------------------- 10
CHAPTER 2. REVIEW OF THE LITERATURE----------------------------------------------12
2.1. Definition of heavy metal(loid)s -------------------------------------------------------------------- 12
2.2. Sources of heavy metal(loid)s ----------------------------------------------------------------------- 12
2.3. Dynamics of heavy metal(loid)s in soils ---------------------------------------------------------- 15
2.4. Sorption/desorption process -------------------------------------------------------------------------- 16
iv


2.5. Transformation of metal(loid)s in soil ------------------------------------------------------------- 17
2.6. Soil amendments for remediation ------------------------------------------------------------------- 18
2.7. Mechanisms of heavy metal uptake by hyperaccumulation plants ------------------------- 19
2.8. Techniques of phytoremediation -------------------------------------------------------------------- 20
2.8.1. Phytoextraction ------------------------------------------------------------------------- 21

2.8.2. Phytostabilisation ---------------------------------------------------------------------- 21
2.8.3. Phytofiltration --------------------------------------------------------------------------- 22
2.8.4. Phytovolatilisation --------------------------------------------------------------------- 22
2.8.5. Phytodegradation----------------------------------------------------------------------- 22
2.8.6. Rhizodegradation ----------------------------------------------------------------------- 23
2.8.7. Phytodesalination ---------------------------------------------------------------------- 23
2.9. Phytoextraction as a cost-effective plant-based technology ---------------------------------- 23
2.10. Species selection for phytoremediation ---------------------------------------------------------- 26
2.11. Properties of growth substratum in field scale ------------------------------------------------- 28
2.12. Factors affecting the uptake mechanisms ------------------------------------------------------- 28
2.12.1. The plant species ----------------------------------------------------------------------------- 29
2.12.2. Properties of medium ----------------------------------------------------------------------- 29
2.12.3. The root zone ---------------------------------------------------------------------------------- 30
2.12.4. Vegetative uptake ---------------------------------------------------------------------------- 30
2.12.5. Addition of chelating agents --------------------------------------------------------- 30
2.13. Phytoremediation- mine metal contaminated soils -------------------------------------------- 32
2.13.1. Phytoremediation --------------------------------------------------------------------- 32
2.13.2. Application of phytoremediation: global study ----------------------------------- 33
v


2.14. Mobilisation of soil contaminants ----------------------------------------------------------------- 34
2.15. The mechanisms of heavy metal uptake by hyperaccumulator plants -------------------- 35
2.16. Role of phytoexaction of HMs using chelates and native plants in contaminated soils ------- 36
2.17. Immobilisation of soil contaminants ------------------------------------------------------------- 37
2.18. Rehabilitation of metal mining sites in Vietnam ---------------------------------------------- 38
2.18.1. Thai Nguyen Province mining sites------------------------------------------------- 39
2.18.2. Trai Cau Iron mine site -------------------------------------------------------------- 39
2.18.3. Cay Cham titanium ore mine site --------------------------------------------------- 40
2.18.4. Cuoi Nac mine site -------------------------------------------------------------------- 41

2.18.5. Hich Village lead zinc mine site ---------------------------------------------------- 41
2.19. Situation of using local plants and exotic plants in Vietnam ------------------------------- 42
2.20. Heavy metal pollution in soil in mining sites in Thai Nguyen province ----------------- 43
2.21. Selected plants and theirs applications in rehabilitation in Thai Nguyen province ------------- 44
2.21.1. Reed plant (Phragmites australis) -------------------------------------------------- 45
2.21.2. Lau plant (Erianthus arundinaceus (Retz.)) --------------------------------------- 46
2.21.3. Ryegrass (Lolium multiflorum)------------------------------------------------------ 47
2.22. A risk-based remediation approach --------------------------------------------------------------- 47
CHAPTER 3: METHODOLOGY -------------------------------------------------------------------50
3.1. Overview of the research ----------------------------------------------------------------------------- 50
3.2. Methodologies ------------------------------------------------------------------------------------------- 50
3.2.1. Study areas ------------------------------------------------------------------------------ 50
3.2.2. Soil and plant sampling ---------------------------------------------------------------- 52
3.2.3. Characterisation soil and plants samples ------------------------------------------- 54
vi


3.2.4. Treatments ------------------------------------------------------------------------------- 55
3.2.5. First incubation experiments---------------------------------------------------------- 55
3.2.6. Preparation------------------------------------------------------------------------------ 56
3.2.7. Second incubation experiment -------------------------------------------------------- 56
3.2.8. Pot experiments in greenhouse ------------------------------------------------------- 56
3.2.9. Field sampling and analyses of plant biomass ------------------------------------ 57
3.2.10. Soil and plant analysis --------------------------------------------------------------- 57
3.2.11. Data processing methods ------------------------------------------------------------ 58
CHAPTER 4: MINE SITE SOIL AND PLANT CHARACTERISATION--------------59
4.1. Introduction ---------------------------------------------------------------------------------------------- 59
4.2. Materials and methods --------------------------------------------------------------------------------- 62
4.2.1. Study areas ------------------------------------------------------------------------------ 62
4.2.2. Sample design --------------------------------------------------------------------------- 63

4.2.3. Soil physicochemical properties ------------------------------------------------------ 64
4.2.4. Plant sample analyses ----------------------------------------------------------------- 64
4.2.5. The BCF, TF and EF ------------------------------------------------------------------- 65
4.2.6. Soil mineralogy ------------------------------------------------------------------------- 66
4.2.7. Statistical analysis ---------------------------------------------------------------------- 66
4.3. Results and discussion --------------------------------------------------------------------------------- 67
4.3.1. Physicochemical parameters of soils ------------------------------------------------ 67
4.3.2. Accumulation factors of HMs for PA and EA -------------------------------------- 70
4.3.3. Soil minerals ---------------------------------------------------------------------------- 74

vii


4.3.4. Correlation between HMs (As, Cd, Cu, Pb and Zn) contents in soil and soil
properties --------------------------------------------------------------------------------------- 76
4.3.5. The influence of soil properties on HMs content levels in EA and PA ---------- 79
4.4. Conclusion------------------------------------------------------------------------------------------------ 86
CHAPTER

5:

CHELATE-ASSISTED

ENHANCED

HEAVY

METAL

BIOAVAILABILITY IN MINED SOILS: A COMPARATIVE STUDY----------------90

5.1. Introduction ---------------------------------------------------------------------------------------------- 90
5.2. Materials and methods --------------------------------------------------------------------------------- 92
5.2.1 Sampling ---------------------------------------------------------------------------------- 92
5.2.2. Characterisation ------------------------------------------------------------------------ 92
5.2.3. SEM, FTIR and XRD analysis -------------------------------------------------------- 94
5.2.4. Chelate-assisted mobilisation of metals --------------------------------------------- 94
5.3. Results ----------------------------------------------------------------------------------------------------- 96
5.3.1. Soil properties -------------------------------------------------------------------------- 96
5.3.2. Mineralogical composition of mine soils using XRD ------------------------------ 98
5.3.3. SEM of minerals ------------------------------------------------------------------------ 99
5.3.4. Chelate metal extraction-------------------------------------------------------------- 101
5.4. Discussion ---------------------------------------------------------------------------------------------- 103
5.5. Conclusions -------------------------------------------------------------------------------------------- 104
CHAPTER 6: CHELATE-ASSISTED METAL PHYTOAVAILABILITY IN THE
PLANT STUDIES ---------------------------------------------------------------------------------------- 106
6.1. Introduction -------------------------------------------------------------------------------------------- 106
6.2. Hypothesis ---------------------------------------------------------------------------------------------- 108
6.3. Materials and methods ------------------------------------------------------------------------------- 109
viii


6.3.1. Soil characterisation ------------------------------------------------------------------ 109
6.3.2. Plant sample analyses ---------------------------------------------------------------- 110
6.3.3. Pore water analysis ------------------------------------------------------------------- 111
6.3.4. Soil incubation ------------------------------------------------------------------------- 111
6.3.5. Plant growth experiment using chelates-------------------------------------------- 111
6.3.6. Statistical analysis --------------------------------------------------------------------- 113
6.4. Results and Discussion ------------------------------------------------------------------------------ 114
6.4.1. Physicochemical parameters of soils ----------------------------------------------- 114
6.4.2. Effects of EDTA, EDDS and NTA in 2 selected doses on plant growth -------- 115

6.4.3. Effects of EDTA, EDDS and NTA on pore water metal concentration--------- 118
6.4.4. Effects of EDTA, EDDS and NTA on root and shoot metal concentrations and
phytoextraction -------------------------------------------------------------------------------- 120
6.4.5. Effects of EDTA, EDDS and NTA on the uptake of HMs by Ryegrass --------- 124
6.5. Conclusions -------------------------------------------------------------------------------------------- 128
CHAPTER 7: CONCLUSION INCLUDING FUTURE RESEARCH ------------------ 130
7.1. Conclusion---------------------------------------------------------------------------------------------- 130
7.2. Future research ---------------------------------------------------------------------------------------- 133
REFERENCES -------------------------------------------------------------------------------------------- 136
APPENDIX ------------------------------------------------------------------------------------------------- 163

ix


LIST OF ABBREVIATIONS

Aloxa, Mnoxa and Feoxa = Ammonium oxalate/oxalic acid extractable Al, Mn, Fe
CEC = Cation exchange capacity
DIC = Dissolved inorganic carbon
DOC = Dissolved organic carbon
EA= Erianthus arundinaceus (Retz.)
EC = Electrical conductivity
EDDS = S,S-ethylenediaminedi-succinic acid
EDS = Energy dispersive X-ray spectroscopy
EDTA = Ethylenediaminetetraacetic acid
FTIR = Fourier Transformed Infrared Spectroscopy
HMs = Heavy metal(loid)s
IC = Inorganic carbon
ICP-MS = Inductively coupled plasma mass spectrometry
MLR = Multiple linear regression

NTA= Nitrilotriacetate
OM = Organic matter
PA= Phragmites australis (Cav.)
PCA = Principal component analysis
SEM = Scanning Electron Microscope
TOC = Total organic carbon
WHC = Water Holding Capacity
XRD = X-ray diffraction

x


LIST OF FIGURES

Fig. 2.1. The interaction between adsorption reactions of metal(loid)s in soil and their
bioavailability (Naidu and Kim, 2008, Bolan et al., 2014).-----------------------15
Fig. 2.2. Transformation pathways of metalloids in soil---------------------------------------17
Fig. 2.3. The mechanisms of heavy metals uptake by plant through phytoremediation
technology (Tangahu et al., 2011)----------------------------------------------------20
Fig. 2.4. Schematic representation of phytoremediation strategies---------------------------20
Fig. 2.5. Schematic representation of phytoextraction of metals from soil (Favas et al.,
2014) --------------------------------------------------------------------------------------24
Fig. 2.6. Schematic representation of the processes of natural (A) and chelate-assisted
(B) phytoextraction (Favas et al., 2014).---------------------------------------------25
Fig. 2.7. Factors affecting the uptake mechanisms of heavy metals (Tangahu et al.,
2011)--------------------------------------------------------------------------------------29
Fig. 2.8. Uptake mechanisms on phytoremediation technology (ITRC, 2009)--------------33
Fig. 2.9. Mining locations in Thai Nguyen province, Vietnam (Anh et al., 2011)----------40
Fig. 2.10. Risk assessment methodology (CRC CARE, 2018)--------------------------------48
Fig. 3.1. Overview of research methodologies --------------------------------------------------50

Fig. 3.2. Locations of the research mining sites-------------------------------------------------51
Fig. 4.1. (a) Phytoremediation (Favas et al., 2014) (b) Factors affecting the uptake
mechanisms of heavy metals (Tangahu et al., 2011)-------------------------------60
Fig. 4.2. Mining soil sampling at the selected sites in Thai Nguyen province: (a) LH lead
zinc mine site, (b) HT tin mine site, and (c) TC iron mine site (d) PA (e) EA-------62
Fig. 4.3. The average contents of HMs in root, steam and leaf of PA and EA---------------72
Fig. 4.4. XRD results for HT tin mine soil, Ka = kaolinite, Q = quartz, Ar = arsenopyrite, Mu
= muscovite--------------------------------------------------------------------------------74
Fig. 4.5. EDS (a) (b) and SEM (c) results for HT tin mine soil-------------------------------74

xi


Fig. 4.6. XRD (a), EDS (b), SEM (c) results for LH Lead-Zinc mine soil, Q = quartz,
Ca= calcite, Fr = franklinite, Mu = muscovite, Sp = sphalerite, La =
lanarkite, Do = dolomite.---------------------------------------------------------------75
Fig. 4.7. XRD (a), EDS (b), SEM (c) results for TC iron mine soil, Ka = kaolinite , Go
= goethite, Q = quartz , A = anatase , He = hematite, Il = Iilite-------------------75
Fig. 4.8. Correlation among selected HMs (As, Cd, Cu, Pb, and Zn) and the soil pH in three mining
sites-----------------------------------------------------------------------------------------78
Fig. 4.9. Correlation between As and Fe content in HT mine soil----------------------------79
Fig. 4.10. PCA component plot--------------------------------------------------------------------85
Fig. 5.1. Mining soil and plant sampling sites at the selected sites, corresponding to Ha
Thuong tin mine (HT), Hich Village lead-zinc mine (LH), and Trai Cau iron
mine (TC mine)---------------------------------------------------------------------------93
Fig. 5.2. Microprobe images of minerals in HT sample using SEM--------------------------99
Fig. 5.3. EDS (a) and SEM (b) analysis of the topsoil sample from the HT tin mine----100
Fig. 5.4. EDS (a) and SEM (b) analysis of the topsoil sample from the LH lead-zinc
mine-------------------------------------------------------------------------------------100
Fig. 5.5. EDS (a) and SEM (b) analysis of the topsoil sample from the TC iron mine--101

Fig. 5.6. Lead extraction in the HT, LH and TC mines---------------------------------------102
Fig. 5.7. Zinc extraction in the HT, LH and TC mines---------------------------------------102
Fig. 5.8. Cadmium extraction in the HT, LH and TC mines---------------------------------103
Fig. 6.1. Plant experiments using chelates and plant toxicity symptoms-------------------115
Fig. 6.2. Effects of the application of chelates on the fresh weight of ryegrass (Lolium
multiflorum) in three selected mining sites (HT, LH, TC mine). Lower case
letters represent significant difference between treatments----------------------116
Fig. 6.3. Effects of EDTA, EDDS and NTA in dry biomass of shoot----------------------117
Fig. 6.4. Effects of EDTA, EDDS and NTA in dry biomass of root------------------------117
Fig. 6.5. Effects of the application of chelates on the uptake of Cu in the roots and
shoots of the ryegrass. Values are means ± SD (n = 3). Lower case letters
xii


represent significant difference between treatments for shoots and roots at
each site---------------------------------------------------------------------------------124
Fig. 6.6. Effects of the application of chelates on the uptake of Pb in the roots of the
ryegrass. Values are means ± SD (n = 3). Lower case letters represent
significant difference between treatments for shoots and roots at each site.--125
Fig. 6.7. Effects of the application of chelates on the uptake of Pb in the shoots of the
ryegrass. Values are means ± SD (n = 3). Different letters indicate
significant (p <0.05) difference with other treatments; values are in the
order: a > b > c)------------------------------------------------------------------------125
Fig. 6.8. Effects of the application of chelates on the uptake of As in the roots and
shoots of the ryegrass. Values are means ± SD (n = 3)--------------------------126
Fig. 6.9. Effects of the application of chelates on the uptake of Zn in the roots and
shoots of the ryegrass. Values are means ± SD (n = 3). Different letters
indicate significant (p <0.05) difference with other treatments; values are in
the order: a > b > c)-------------------------------------------------------------------127


xiii


LIST OF TABLES
Table 2.1. Heavy metal(loid)s contaminant source, toxicity and their expected ionic
species in soil solution ------------------------------------------------------------------ 14
Table 2.2. Summary of the different phytoremediation techniques(Ali et al., 2013) ------- 21
Table 2.3. Selected references on the potential plants and chelating agents in the
mobilisation of metal(loid)s in soils -------------------------------------------------- 34
Table 2.4. The physicochemical properties of soil in mining areas of Thai Nguyen
province ---------------------------------------------------------------------------------- 41
Table 2.5. Soil chemical properties in the Thai Nguyen mining sites (Pha et al., 2014) --- 44
Table 3.1. Location of the sampling sites for soil and plant in the study areas ---------------- 53
Table 4.1. Soil properties of contaminated soils (topsoil 0-20 cm) collected from the
three selected mining sites (mean ± SD, n=3) --------------------------------------- 69
Table 4.2. Contents ranges of HMs in the soils, roots, stems and leaves of PA and EA
samples from all 3 mine sites (mean ± SD, n=3) ------------------------------------ 71
Table 4.3. The Translocation factor (TF), Bioconcentration factor (BCF) and
Enrichment factor (EF) of Lau plant (EA) and Reed plant (PA) (mean ± SD,
n=3) ---------------------------------------------------------------------------------------- 73
Table 4.4. Pearson correlation between HMs contents and soil properties ------------------ 76
Table 4.5. Rotated component matrix of PCA analysis ----------------------------------------- 80
Table 4.6. Pearson correlation between contents of Zn in EA root and components of PC1 ---- 82
Table 4.7. Rotated component matrix of PCA analysis ----------------------------------------- 83
Table 4.8. Rotated component matrix of PCA analysis ----------------------------------------- 84
Table 4.9. Pearson correlation between contents of Cu in PA root and silt-sized and
clay-sized and CECB -------------------------------------------------------------------- 86
Table 5.1. Physicochemical properties of the three selected soil from selected mining
sites, SD = 3 ------------------------------------------------------------------------------ 97
Table 5.2. Soil pH and average metal concentrations (mg/kg), (mean ± SD, n=3) --------- 98


xiv


Table 5.3. Summary of XRD analysis of minerals in the mine site soils (level of
abundance) ------------------------------------------------------------------------------- 98
Table 6.1. Soil properties of the three selected soil collected from three selected mining
sites (mean ± SD, n=3)---------------------------------------------------------------- 114
Table 6.2. Effects of EDTA, EDDS and NTA on pore water metal concentration
at HT site (n=3) ----------------------------------------------------------------------- 118
Table 6.3. Effects of EDTA, EDDS and NTA on pore water metal concentration at LH
site (n=3) -------------------------------------------------------------------------------- 119
Table 6.4. Effects of EDTA, EDDS and NTA on pore water metal concentration at TC mine
site (n=3) -------------------------------------------------------------------------------- 119
Table 6.5. Effects of EDTA, EDDS and NTA on DOC by sites (n=3) --------------------- 120
Table 6.6. Dry biomass yields (g/pot) and concentrations of As, Cd, Cu, Pb, and Zn
(mg/kg DW) in the shoots of ryegrass 28 days after application of EDTA,
EDDS and NTA at HT ---------------------------------------------------------------- 121
Table 6.7. Dry biomass yields (g/pot) and concentrations of As, Cd, Cu, Pb, and Zn
(mg/kg DW) in the shoots of ryegrass 28 days after application of EDTA,
EDDS and NTA at LH ---------------------------------------------------------------- 122
Table 6.8. Dry biomass yields (g/pot) and concentrations of As, Cd, Cu, Pb, and Zn
(mg/kg DW) in the shoots of ryegrass 28 days after application of EDTA,
EDDS and NTA at TC mine --------------------------------------------------------- 122
Table 6.9. One-way ANOVA analysis of difference between chelate treatments in the shoot
of ryegrass 28 days after application of EDTA, EDDS and NTA in three mining
sites -------------------------------------------------------------------------------------- 123
Table 6.10. Pearson correlation between plant biomass and plant shoot uptake of metals ------- 124

xv



LIST OF PUBLICATIONS
1. Hai, N. N. S., Nong, N. N., Giang, N. K., Peter, S., Naidu, R. 2020. Evaluation of Heavy
Metals (As, Cd, Cu, Pb, Zn) Accumulation in Contaminated Soils in Thai Nguyen Mining
Sites. Journal of Vietnam Soil Science, 59, 16-24.
2. Hai, N. N. S., Peter, S., Fangjie, Q., Jianhua, D., Nong, N. N., Giang, N. K., Bolan, N.,
Naidu, R. (2020). Evaluation of Heavy Metals (As, Cd, Cu, Pb and Zn) Accumulation
and Their Impact Factors in Native Plants at Thai Nguyen Metals Mining Sites.
Manuscript in Reviewing in ETI journal.
3. Hai, N. N. S., Peter, S., Jianhua, D., Bolan, N.S. , Naidu, R. (2017). Accumulation of As,
Cd, Cu, Pb, and Zn in Native Plants Growing on Contaminated Thai Nguyen Sites.
CleanUp 2017, Melbourne.
Presentations on conferences
Oral presentation “Accumulation of As, Cd, Cu, Pb, And Zn in Native Plants Growing on
Contaminated Thai Nguyen Sites”, Clean-Up 2017, Melbourne, Australia.
Poster presentation “Accumulation of As, Cd, Cu, Pb, and Zn in Native Plants Growing on
Contaminated Thai Nguyen Sites, Vietnam”, Mined Land Rehabilitation Conference 2018
- Best Practice Ecological Rehabilitation of Mined Lands Conference, Newcastle, NSW. 12
April 2018.
Poster presentation “Evaluation of Heavy Metals (As, Cd, Cu, Pb, Zn) Uptake Factors of
Native Plants in Thai Nguyen Mining Sites – A Study for Phytoremediation”, Clean-Up
Conference 2019, Adelaide, Australia.
Oral presentation “Evaluation of Heavy Metals (As, Cd, Cu, Pb and Zn) Contents in
Contaminated Soils in Thai Nguyen Mining Sites”. International Conference of Sustainable
and Responsible Mining (ISRM 2020), Hanoi, 15 October 2020.
Oral presentation “Evaluation of Heavy Metals (As, Cd, Cu, Pb And Zn) Accumulation in
Contaminated Soils in Thai Nguyen Mining Sites”, Earth Sciences and Natural Resources
for Sustainable Development (ERSD2020). Hanoi, 12 November 2020.
Conference Proceedings

Hai, N. N. S., Peter, S., Fangjie, Q., Jianhua, D., Nong, N. N., Giang, N. K., Bolan, N.,
Naidu, R. (2020). Evaluation of Heavy Metals (As, Cd, Cu, Pb and Zn) Contents in
xvi


Contaminated Soils in Thai Nguyen Mining Sites. International Conference of Sustainable
and Responsible Mining (ISRM 2020), Hanoi, 15 October 2020.
Hai, N. N. S., Nong, N. N., Giang, N. K., Hai, N. T., Peter, S., Naidu, R. (2020). Evaluation
of Heavy Metals (As, Cd, Cu, Pb And Zn) Accumulation in Contaminated Soils in Thai
Nguyen Mining Sites, Earth Sciences and Natural Resources for Sustainable Development
(ERSD2020). Hanoi, 12 November 2020.
Statement: All published papers out of this PhD work reused in this thesis were
permitted by the publishers.

xvii


ABSTRACT
Phytoremediation is a green remediation technology providing a cost-effective, aesthetic
solution for remediation of contaminated soil. One of the phytoremediation strategies in the
metal-contaminated soil is phytoextraction, which involves the uptake and accumulation of
metals into harvestable biomass of plants (i.e. shoots). These can then be harvested and removed
from the site. Another application of phytoremediation is phytostabilisation, where certain plant
species are used to immobilise the metal in the contaminated soil. It is important to use native
plants for phytoremediation because these plants are often better in terms of survival, growth
and reproduction under local environmental conditions than plants introduced from other sites.
This study evaluated the phytoremediation potential of two native plant species, Lau plant
(EA) (Erianthus arundinaceus (Retz.) and Reed plant (PA), Phragmites australis (Cav.), for
three contaminated mining sites in Vietnam, specifically the following: Ha Thuong lead-zinc
mine, Trai Cau Iron mine, and Hich Village Lead-zinc mine in Thai Nguyen province. The

ability of EA and PA to accumulate heavy metal(loid)s (HMs), including As, Cd, Cu, Pb, Zn)
has been evaluated. Total metal(loid)s concentrations including As, Cd, Cu, Pb and Zn in the
plants and corresponding soils were determined. Soil samples were subsequently characterised
by XRD, SEM and EDS analysis.
The concentrations of HMs were high in stem, leaves and roots, demonstrating the plants’ high
metal bioaccumulation potential from the soils, which are also high in HM content. Total As,
Cd, Cu, Pb and Zn concentration in soils varied from 4 to 2605, 0 to 124, 6 to 603, 45 to 5008
and 64 to 31789 mg/kg, respectively, while the corresponding concentrations in the plants
ranged from 0.02 to 300, 0.1 to 33, 3 to 111, 1.19 to 982, 27 to 1346 mg/kg, respectively. There
was a positive correlation between HM content in the soil and those in the plants. The
accumulation factor for HMs in roots was higher than that in stems or leaves of the plants for all
soils. Only EA had the ability to naturally survive, grow and generate high biomass in the
presence of extremely high concentrations of multiple HMs in soils, especially As, Cd, Cu, Pb
and Zn, the concentrations of which were as high as 2605 mg/kg, 124 mg/kg, 603 mg/kg, 5008
mg/kg, 31788 mg/kg, respectively. Lau plant (EA) accumulated HMs more efficiently than PA
in the root, stem and leaves in all three mining sites. The phytoextraction capacity of PA and EA
is relatively low. However, their high biomass yield led to a relatively large accumulation of HMs.
Native EA species have high BCF (6.45) and low TF (0.74) in terms of Cd in the soils, thus

1


indicating the EA has the potential for phytostabilisation of Cd contaminated sites. EA and PA
growing on the sites have the potential for phytoremediation of the five metals, and consequently
repair to some extent the metal-contaminated sites. They can help to stabilise soil and
phytoremediate especially in extremely high concentrations of multiple HMs (As, Cd, Cu, Pb,
Zn), and thereby reduce offsite pollution in the mining areas.
Detailed mineral characterisation shows the presence of arsenopyrite (FeAsS) and franklinite
(ZnFe3+2O4) in HT soils with these minerals contributing to high As, Zn and Fe content,
especially in acid soil environment (pH <5). Dolomite CaMg(CO3)2 , calcite (CaCO3) and

calcium carbonate (CaCO3) minerals were found in LH, contributing to an alkaline soil
environment (pH 8.28) and high Pb, Zn. PA tolerates slightly acidic to strongly alkaline soil. In
contrast, EA was tolerant of extremely acidic environment (pH 4.12 - 5.95) to strongly alkaline
environment (pH (7.43 – 8.72) and high concentration of multiple HMs also.
The effects of different chelates were investigated using different doses and methods of
application to examine mobilisation of selected metals (loid)s (As, Cd, Cu, Pb and Zn) in
soil and the potential for enhancing phytoaccumulation of in plants. Factors affecting plant
metal uptake in mine sites, chelate mobilisation in soils and the applicability of enhanced
phytoextraction were investigated. The application of EDTA, EDDS and NTA to three
selected soils from the three sites significantly increased the concentrations of As, Cd, Cu,
Pb and Zn in the shoots of rye grass (Lolium multiflorum). EDTA 0.5:1+0.5:1 was more
effective at increasing the concentration of Pb in shoots than other chelates (NTA, EDDS)
and controls. With the application of chelate treatments EDTA (0.5:1+0.5:1), the
concentrations of Pb in the shoots of the ryegrass in LH reached 1,339 mg/kg DW which
were 269.5-fold larger than that of the controls. Moreover, the concentrations of Zn in the
shoots of ryegrass in LH significantly increased with the application of split dose
(0.5:1+0.5:1).
Additionally, Zn shoot concentration was significantly increased in chelate treatments
(EDTA 1:1, NTA 1:1 and NTA 0.5:1+0.5:1) in HT; while EDTA 0.5:1+0.5:1 resulted in
significant increased shoot Cd, Pb, Zn concentration at p<0.01 and NTA 0.5:1 +0.5:1
significantly increased shoot As, and EDDS 0.5:1 +0.5:1 significantly increased shoot Pb
concentration in LH.

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Plant growth was significantly affected in soils treated with chelates, particularly sequential
chelate treatment (EDTA 0.5:1+0.5:1; NTA 0.5:1+0.5:1; EDDS 0.5:1+0.5:1). The plants
displayed symptoms of toxicity including yellow and necrotic leaves at the end of the
experiment. The selected chelates (EDTA, EDDS and NTA) led to a significant decrease in

plant biomass (yield) 28 days after transfer with a maximum decrease in EDTA treatment
(0.5:1+0.5:1) soils. This decrease was 3.43-fold in HT, 3.00-fold in LH and 1.59–fold
respectively, relative to the control.
Fresh weight of shoot of the ryegrass (Lolium multiflorum) had a strong positive relationship
with dry biomass, and negative correlation with Pb and Zn concentration in the shoot. There
was strong positive correlation among As and Pb concentration with Zn concentration in the
shoot. Combined with HMs concentration and DOC results in pore water this provided an
explanation for why fresh weight was significantly reduced with application of chelates in
sequential dose (EDTA 0.5:1+0.5:1 and NTA 0.5:1 +0.5:1).
The different chelate treatments especially sequential addition are considered to have
potential for enhancing phytoextraction of specific metals depending on soil properties of
the contaminated soils. While a laboratory-based study demonstrates potential for
phytoremediation of the metal contaminated mined soils, further research is needed in the field
under controlled conditions. In particular, the extension of chelate-mobilised mining of metals
by plants needs detailed anlaysis both in the laboratory and in the field.
In conclusion, this research suggests more future work is required on phytoremediation of
HMs, especially phytoextraction by assisted chelate moblisation at mining sites. Chelateassisted mobilisation of HMs using the selected plants, namely native plant (EA and PA)
and exotic plants using the single or split application is quite promising for HMs
accumulation as well as phytoextraction of the HMs.

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CHAPTER 1. INTRODUCTION
1.1.

Risks of contaminated sites and remediation technologies

Contamination impacting land, water and air throughout the world represents an
increasingly serious problem in today’s fast-paced, technology-driven economies (Naidu et

al., 2015). Contaminated industrial sites are also another closely related issue that requires
resolution. According to Naidu et al. (2015), there is estimated to be more than three million
potentially contaminated sites worldwide, presenting a potentially huge economic loss and
great risks to the environment as well as human health.
High concentrations of HMs, such as As, Cd, Cu, Pb, and Zn in soils are reported around
the world, and these have been caused by anthropogenic activities. The concentration of
metal(loid)s accumulate and continue to persist for a long time after their introduction in soil
(Adriano et al., 2004). Mining is considered to be one of the major causes of environmental
pollution by HMs (Carvalho et al., 2013). Together with better social understanding as well
as awareness about the effects of contaminated soil on human health, the scientific community
is now focusing on the development of modern technologies to rehabilitate contaminated sites.
Remediation technologies in contaminated sites are divided into two principal approaches,
these being ex situ (treatment is done on the ground) and in situ (water and soil in the ground
to be treated). Ex situ remediation involves the excavation of contaminated soil or
abstraction of polluted water for treatment or landfill. The available techniques for ex situ
and in situ are often prohibitively expensive; therefore, they have a poor application and
outcome in many countries (Naidu et al., 2015). This is a major reason for introducing a
risk-based management strategy to remediate contaminated sites in the long-term. The
decision is linked to dangerous levels of risk based on reputable scientific estimates of the
level of risk (Naidu et al., 2015).
The assessments of risks of contaminated sites should consider two points: firstly,
introduction of risk-based data into the assessment; and secondly, the application of
remediation approaches to curtail the risk. Adopting a risk-based approach is preferable over
a total concentration reduction, considering the need for sustainable and cost-effective
solutions. This is reflected in management using the stimulation of biodegradation
application as well as solutions employing isolation and immobilisation of the contaminants.
Site-specific conditions of contaminated sites moderate contaminant mobility and

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availability, and furthermore they play an essential part in risk-based remediation
approaches (Duan et al., 2015b, Naidu et al., 2015). Bioavailability of contaminants relevant
to human activity or environmental influences is an essential part in description of risks and
it could be applied to an appropriate solution for contaminated sites. Risk-based remediation
of contaminated soil may be implemented by certain processes that manipulate metal(loid)s
bioavailability utilising a variety of immobilising and mobilising soil amendments (Bolan
et al., 2014). Phytoremediation is a green remediation technology that uses plants and
associated soil microbes, soil amendments and agronomic techniques to remove, contain or
reduce the concentrations or toxic effects of contaminants in the natural environment (Salt
et al., 1998, Cunningham and Ow, 1996, Vyslouzilova et al., 2003, Helmisaari et al., 2007).
The process of removing HMs can be done by the application of mobilising agents through
washing contaminated soil to enhance uptake by plants. On the other hand, reduction of
metal(loid) leaching and potential for transfer of metal(loid)s to the food chain may be
achieved by immobilising agents and/or phytostabilisation in the root zone. Both the
mobilising and immobilisation techniques have advantages and disadvantages. The major
challenging of the former is having to deal with susceptibility of leaching of the mobilised
HMs together with the absence of active plant uptake. The long-term stability of the
immobilised HMs is the main difficulty in the latter case.
Reduction of metal(loid)s concentrations via application of phytoextraction and rehabilitation
of mining site waste by using phytoremediation has been the subject of much (Robinson et al.,
2009). By contrast, in some contaminated sites where phytoextraction is not possible to
remove the metal(loid)s from the contaminated sites, other viable alternative options including
in situ immobilisation (e.g., phytostabilisation) could be considered as an integral part of risk
management (Bolan et al., 2014).
Revegetation of mine spoils is the most effective method of preventing wind and water
erosion and the consequent spread of contaminants to surrounding areas. Nevertheless, the
process of establishment and growth of plants in mines are subject to several limiting factors
of soil including low pH, low fertility, high concentration of HMs, and a small seed bank to
initiate plant establishment. Two indicators consisting of improving soil physical and

chemical properties are fundamental requirements for the success of (re)vegetation
programs. Carvalho et al. (2013) opine that soil amendments, either through the addition of
technosols, pH buffering or nutrient enrichment, are essential for promoting the revegetation
of mine areas.
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1.2.

Heavy metals and causes leading to environmental pollution

Heavy metals are the metals that have a density greater than 4 g/cm3. Some HMs may be
necessary for organisms, and they are considered to be trace elements.
As mentioned in section 1.1, a series of HMs, such as arsenic (As), cadmium (Cd),
chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), selenium (Se), and zinc (Zn)
(Adriano, 2001), have culminated in a dramatic increase of soil contamination by
indiscriminate waste disposal. The transfer into the food chain of traditional HMs depends
on the quantity and source of metal input, soil properties, the rate and intensity of plant
uptake, and animal absorption (Adriano, 2001). High concentrations of HMs in soils such
as As, Cd, Cu, Pb and Zn have also been recorded in several countries in recent years.
Metal(loid)s persist and continue to accumulate over a long period of time after their
introduction into the soil (Adriano et al., 2004). In addition to greater societal knowledge
and awareness of the impact of polluted soil on human health, the scientific community
has become increasingly attentive to the advancement of new technology that can
rehabilitate contaminated sites. Many investigations of metal(loid)s contaminated soil
have been done in urban environments, especially in mining sites that are rehabilitated
through the processes of metal(loid) mobilisation and removal from the soil by chemical
washing and phytoextraction (Bolan et al., 2014). Reduction of metal(loid)s
concentrations via application of phytoextraction and rehabilitation of mining site waste
by using phytoremediation are attracting potential research and commercial interest

(Robinson et al., 2009). In contrast, while phytoextraction could not eliminate the
metal(loid)s from the contaminated sites in some contaminated areas, some suitable
alternative solutions may be considered an important part of risk control, including in
situ immobilisation (e.g. phytostabilisation) (Bolan et al., 2014).

1.3.

Phytoremediation

Phytoremediation is a green remediation method used to eliminate, contain or decrease the
concentrations or harmful effects of contamination in the environment using plants and
associated soil microbes, soil amendments and agronomic techniques (Salt et al., 1998,
Cunningham and Ow, 1996, Vyslouzilova et al., 2003, Helmisaari et al., 2007). Due to its
ease of use and low cost, phytoremediation is an applicable and preferable technique for the
remediation of mine pollution in Vietnam.

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