radioactive residues associated with...
TRANSCRIPT
QUEENSLAND UNIVERSITY OF TECHNOLOGY
FACULTY OF SCIENCE AND TECHNOLOGY
PHYSICS DISCIPLINE
RADIOACTIVE RESIDUES ASSOCIATED WITH WATER
TREATMENT, USE AND DISPOSAL IN AUSTRALIA
Ross Kleinschmidt
AssocDipAppPhysics BAppSc MAppSc
A thesis submitted in partial fulfilment of the degree of Doctor of Philosophy
2011
1
KEYWORDS
NORM, TENORM, water, radioactivity, environment, radium, radon, iodine-131, wastewater,
disposal, water recycling, Australia
2
ABSTRACT
Water resources are known to contain radioactive materials, either from natural or anthropogenic
sources. Treatment, including wastewater treatment, of water for drinking, domestic, agricultural
and industrial purposes has the potential to concentrate radioactive materials. Inevitably
concentrated radioactive material is discharged to the environment as a waste product, reused for
soil conditioning, or perhaps recycled as a new potable water supply. This thesis, presented as a
collection of peer reviewed scientific papers, explores a number of water / wastewater treatment
applications, and the subsequent nature and potential impact of radioactive residues associated
with water exploitation processes. The thesis draws together research outcomes for sites
predominantly throughout Queensland, Australia, where it is recognised that there is a paucity of
published data on the subject. This thesis contributes to current knowledge on the monitoring,
assessment and potential for radiation exposure from radioactive residues associated with the
water industry.
3
LIST OF PUBLICATIONS
Naturally occurring radionuclides in materials derived from urban water treatment plants
in southeast Queensland, Australia
Journal of Environmental Radioactivity 99, 607-620. 2008
Mapping radioactivity in groundwater to identify elevated exposure in remote and rural
communities.
Journal of Environmental Radioactivity 102, 235-243. 2011
Uptake and depuration of 131
I by the macroalgae Catenella nipae - potential use as an
environmental monitor for radiopharmaceutical waste.
Marine Pollution Bulletin 58, 1539-1543. 2009
4
TABLE OF CONTENTS
CHAPTER 1 11
Introduction 11
1.1 Radioactivity and Water ………………..…………………………………………… 11
1.1.1 Naturally occurring radioactivity in water …………………………….. 12
1.1.2 Anthropogenic radiation sources in water ……………………...……... 14
1.1.3 Radiation protection and regulation of residues and wastes containing
radioactivity
16
1.2 Research Objectives ……………………………………………………………….. 16
1.3 Thesis ……………………………………………………………….……………… 18
1.4 References …………………………………………………………………………. 22
CHAPTER 2 25
Literature Review ……………………………………………………………………………. 25
2.1 Current State of Knowledge ………………………………………….……………. 25
2.2 References …………………………………………………………………………. 30
CHAPTER 3 37
Naturally occurring radionuclides in materials derived from urban water treatment
plants in southeast Queensland, Australia
Abstract ………………………………………………………………………….……………. 39
3.1 Introduction ………………………………………………………………………... 40
3.2 Water Supplies …………………………………………………………………….. 42
3.3 Sampling Details and Methods ……………………………………………………. 46
3.3.1 Sampling ……………………………………………….……………….. 46
3.3.2 Methods – Water ……………………………………….………………. 46
3.3.3 Methods - Solid wastes ……………………………………..………….. 48
3.3.4 Method validation ………………………………………….….……….. 48
3.3.5 Dose calculation ……………………………………………….……….. 49
5
3.4 Results and Discussion ……………………………………………………………. 51
3.4.1 Radiological water quality ……………………………………………… 51
3.4.2 Solid wastes …………………………………………………………….. 54
3.4.3 Liquid wastes …………………………………………………………… 56
3.4.4 Radioactive material inventory in WTP sludges and sediments .…..…… 56
3.4.5 Dose calculations ……………………………………………………….. 58
3.5 Conclusions ………………………………………………………………………... 59
3.6 Acknowledgements ………………………………………………………………... 62
3.7 References …………………………………………………………………………. 62
CHAPTER 4 67
Mapping radioactivity in groundwater to identify elevated exposure in remote and rural
communities.
Abstract ……………………………………………………………………………………….. 69
4.1 Introduction ………………………………………………………………………... 70
4.2 Method …………………………………………………………………………….. 71
4.2.1 Survey and sampling design ………………………………….………... 71
4.2.2 Radioanalytical methods ……………………………………………….. 72
4.2.3 Mapping ………………………………………………………………… 74
4.3 Results and Discussion …………………………………………………………….. 75
4.3.1 Radioanalytical method validation and sampling quality ………..…….. 75
4.3.2 Sampling program ……………………………………………………… 77
4.3.3 Radiological water quality and mapping ………………………..……… 78
4.3.4 Reference study area ……………………………………………..…….. 82
4.3.5 Investigation trigger level ………………………………………...……. 83
4.4 Conclusions ………………………………………………………………………... 86
4.5 Acknowledgements ………………………………………………………………... 87
4.6 References …………………………………………………………………………. 87
6
Chapter 4 Supplementary Material ........................................................................................... 92
Supp. 4.1 Groundwater Resources of Queensland, Australia ........................................... 93
Supp. 4.2 Detailed Reference Site Description ................................................................. 94
CHAPTER 5 97
Uptake and depuration of 131
I by the macroalgae Catenella nipae – potential use as an
environmental monitor for radiopharmaceutical waste.
Abstract ...................................................................................................................................... 99
5.1 Introduction .............................................................................................................. 100
5.2 Methods ..................................................................................................................... 101
5.3 Results and Discussion .............................................................................................. 105
5.3.1 Uptake ....................................................................................................... 105
5.3.2 Depuration ................................................................................................ 107
5.3.3 Environmental monitors ........................................................................... 109
5.4 Conclusions ............................................................................................................... 111
5.5 References ................................................................................................................. 112
CHAPTER 6 116
Concluding Statements 116
6.1 Summary and Conclusions ………………………………………………………… 116
6.2 Future Research …………………………………………………………….……… 118
7
LIST OF TABLES
Table 1.1 Primary decay schemes for 238
U and 232
Th ………………………………….
13
Table 3.1 Water supply and treatment data for selected cities and towns ……………..
42
Table 3.2 Waste produced from metropolitan water treatment plants …………………
52
Table 3.3 Radioactivity concentrations in water ………………………………………
53
Table 3.4 Radioactivity concentrations in solid waste material ……………………….
55
Table 3.5 Radioactivity concentrations in liquid wastes ……………………………....
57
Table 3.6 Annual radioactive inventory derived from WTP sludge associated with ….
urban surface water treatment
57
Table 3.7 RESRAD modelling parameters and results for critical population groups ... 60
Table 4.1 Aquifer lithology key ……..………………………………………….……..
75
Table 4.2 Summary of radioanalytical results for all water samples and aquifer …..…..
lithology types
78
Table 4.3 Summary of activity concentrations in water, scales, sludges and soils, and
associated potential exposure pathways identified at the reference site.
85
Table 4.4 Trigger values and water radioactivity concentration data for locations where
further assessment is recommended.
86
Table 5.1 Uptake experiment results …..……………………………………………….
106
Table 5.2 Depuration experiment results ………………………………………………
107
Table 5.3 Experiment 1 – Environmental monitoring results for estimating 131
I …...…
concentration in estuary water using C. nipae sampling devices
110
Table 5.4 Experiment 2 – Effluent monitoring results for estimating 131
I …………..…
concentration using C. nipae sampling devices
110
8
LIST OF FIGURES
Figure 1.1 The water cycle, including potential extraction and waste discharge routes 11
Figure 1.2 Transfer of radiopharmaceutical waste to the environment .......................... 15
Figure 1.3 Model for assessing the impact of radioactive residues associated with ….…
water treatment, use and disposal
20
Figure 1.4
Water resource utilisation cycle and relationship to key study areas …….....
21
Figure 3.1 a) Water statistics by application or end use for Australia, b) Water usage by
states and territories of Australia
41
Figure 3.2 Location of study areas in south-east Queensland, Australia ……………….
43
Figure 3.3 Water treatment processes: a) Typical for all surface water suppliers ……...
including Brisbane; b) Groundwater treatment plant – Toowoomba; c)
Groundwater treatment plant – Dalby.
45
Figure 3.4 Exposure pathway model for treatment residues ……………………………
50
Figure 4.1 Groundwater sampling kit including: 1 x 500 mL acid washed polyethylene
bottle, 2 x 20 mL Teflon coated polyethylene liquid scintillation vials,
sampling instructions and questionnaire, and reusable shipping container
with prepaid consignment note.
72
Figure 4.2 Predominant groundwater aquifer zones of Queensland, Australia.
76
Figure 4.3 Percentage variation in duplicate 222
Rn samples plotted against activity ...…
concentration magnitude.
77
Figure 4.4 Radioactivity concentration in groundwater, relative distribution of primary
investigation radionuclides.
79
Figure 4.5 Radioactivity in groundwater maps for primary radionuclides ……………..
80
Figure 4.6 Radioactivity in groundwater result distribution within main aquifer ……...
lithology types.
81
Figure 4.7 Location map of reference site and water supply / sewerage system ………
schematic.
82
Supp 4.1 Groundwater resources of Queensland, Australia ……………………….…. 93
9
Supp 4.2 Location maps of reference site and water supply / sewerage system ……....
schematic
96
Figure 5.1 Catenella nipae: a) attached to mangrove pneumatophore, and b) as an ….…
individual plant.
102
Figure 5.2 C. nipae sampling device used for estimating 131
I water concentration in an
estuary.
104
Figure 5.3 131
I uptake by C. nipae showing experimental results and modelled data for
three different water concentrations
108
Figure 5.4 131
I elimination from C. nipae showing normalised, mean experimental ……
results and modelled data.
108
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STATEMENT OF ORIGINAL AUTHORSHIP
The work contained in this thesis has not been previously submitted for a degree or diploma at any
other tertiary education institution. To the best of my knowledge and belief, the thesis contains no
material previously published or written by another person except where due reference is made.
Name: Ross Kleinschmidt
Signed:
Date: 30 September 2011
11
CHAPTER ONE
1 Introduction
1.1 Radioactivity and Water
Water is fundamental to life on Earth, and, therefore is one of our most valuable resources. The
supply of clean, abundant water sources is a major challenge facing modern civilisation, and as
such, the topic of many research endeavours. The challenges include the securing of water
supplies, especially in the face of climate change and population growth, and the mitigation of on-
going, detrimental effects of the modern world. The nature of the water cycle (Figure 1.1) itself
dictates the potential for impact from exploitation and pollution from the human extraction,
treatment, use and subsequent discharge of wastewater to the environment. Radioactivity may be
present in water sources as a result of natural processes, or from the mining, production, use or
disposal of radioactive materials.
FIGURE 1.1: The water cycle, including potential extraction and waste discharge
routes (adapted from Bluebison, 2010).
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1.1.1 Naturally occurring radioactivity in water
Naturally occurring sources of radiation are of both terrestrial and cosmogenic origin.
Cosmogenic radionuclides are produced when secondary cosmic radiation interacts with nuclei in
the atmosphere and Earth’s crust via either spallation processes, or more rarely through the capture
(activation) of neutrons or muons. Production of the cosmogenically produced radionuclides in
the atmosphere tends to follow elevational and latitudinal patterns following cosmic radiation
intensity patterns. Approximately 70% of the cosmogenically produced radionuclides are
produced in the stratosphere with the remainder being formed in the troposphere (NCRP, 1994).
The more prominent radionuclides produced include 3H,
7Be,
14C and
22Na (Eisenbud, 1987).
Cosmogenic radionuclides make their way into the terrestrial environment and waterways though
mechanisms including wet and dry deposition, the former being associated with rainfall events.
They then become part of the water cycle with the potential to be concentrated in water treatment
and use residues. A relevant example of these processes are the radioactive beryllium isotopes
(7Be and
10Be) produced in the atmosphere by spallation reactions of cosmogenic particles with
oxygen and nitrogen (Lal and Peters, 1962; Nagai et al., 2000). The beryllium isotopes attach to
aerosols and are then transported to the Earth’s surface by deposition processes. Deposited
beryllium may then be transferred to soils & sediments, and surface, marine & groundwaters
(Graham et al., 1998). 7Be is a commonly identified beryllium radioisotope present in water
treatment plant residues.
Terrestrial radionuclides also directly impact on the water cycle and become available in
extracted waters used by humans. Of the singly occurring radionuclides present in the terrestrial
environment, 40
K is the most commonly encountered in the assessment of radioactive residues
associated with water processes. Of more significant interest, due to their common presence in
groundwater and respective radiotoxicities, are those radionuclides associated with the uranium
and thorium primordial radionuclide series (Table 1.1), whose parent radionuclides are considered
to have been present during the formation of the Earth.
The presence of uranium and thorium nuclides, and their associated decay progeny, is
predominantly obvious in groundwater where geochemical process allow for the dissolution and
transport of radionuclides. An exception to this general situation relates to the atmospheric
13
distribution of gaseous radon radioisotopes and progeny, and their interaction with surface waters
and sediments (Walling et al., 2003). A detailed review of uranium and thorium processes in
geological formations and related geochemisty, including the environmental behaviour of radium
isotopes can be found in IAEA (1990).
Table 1.1: Primary decay schemes for 238
U and 232
Th.
Uranium 238 Thorium 232
Radionuclide Half-life
(years)
Radionuclide Half-life
(years)
238U 4.50E+09 232Th 1.40E+10
234Th 6.57E-02 228Ra 6.70E+00
234Pa 2.28E-06 228Ac 6.96E-04
234U 2.50E+05 228Th 1.90E+00
230Th 8.00E+04 224Ra 9.86E-03
226Ra 1.62E+03 220Rn 1.74E-06
222Rn 1.05E-02 216Po 5.07E-09
218Po 5.89E-06 212Pb 1.25E-03
214Pb 5.13E-05 212Bi 1.16E-04
214Bi 3.80E-05 212Po 9.50E-15
214Po 5.07E-12 209Pb Stable
210Pb 2.20E+01
210Bi 1.37E-02
210Po 3.78E-01
206Pb Stable
Radium isotopes and associated progeny (Table 1.1) are isotopes that are of significance
in determining radiation dose with the water cycle. 226
Ra can generally considered to be in
equilibrium with its parent, 238
U in most rock formations unless weathering, hydrological or
biological processes have impacted on the system. The same can be applied for 228
Ra, and 224
Ra
from the 232
Th series. The chemical nature of parent and radium isotopes is considered to be the
main reason dis-equilibria exists in any environmental system (IAEA, 1990). Radium
14
concentration in water varies dramatically between surface and groundwaters, with surface waters
generally displaying a narrow and typically low concentration range – the paucity of available data
is commented upon in IAEA (1990). Groundwater, however, displays widely ranging
concentrations of radium isotopes, the ratios of 226
Ra to 228
Ra changing over short physical
distances and assumed to be associated with varying geology and disjointed aquifers (IAEA,1990;
Shuktomova and Rachkova, 2011; Sidhu and Breithart, 1998). In some cases Naturally Occurring
Radioactive Materials (NORM) may be concentrated by the activities of humans, these materials
may also impact on water sources and waste streams that may ultimately be discharged to the
environment.
1.1.2 Anthropogenic radiation sources
Mankind has significantly contributed to the presence of radionuclides in our environment. From
the early days of the discovery of radioactivity, the development of nuclear fission for both war
and peace time applications to modern day uses in medicine, industry and research, anthropogenic
radiation sources contribute to radiation dose to the environment and humans (Hu et al., 2008).
While there is no developed nuclear weapon or power industry in Australia, uranium mining is a
significant contributor to environmental contaminants.
Of particular interest to this research work are wastes generated from the clinical
application of radionuclides. Many of these materials, developed as radiopharmaceuticals, are
administered to patients for either diagnostic purposes, as therapeutic procedures for treating
cancers, or for palliative care of patients. The radionuclides used are typically of high specific
activity and are of short to moderately short half-life (hours to days). As shown in Figure 1.2,
wastes from both hospitals, via patients held on-site for treatment either directly or indirectly, and
the general community (via out-patients) may result in radionuclides being present in wastewater
treatment plants where both water and waste residues may be further treated for reuse, or
discharged into the environment (Ippolito et al., 2011, Jimenez et al., 2011). Kleinschmidt (2000)
highlights the lack of available data on the subject, and targeted research required address the
issue.
15
administered
radiopharmaceuticals
in-patient
(isolation ward)
excreted radiopharmaceuticals
out-patient
excreted radiopharmaceuticals
out-patient
excreted radiopharmaceuticals
decay holding
tank/s
wastewater system (sewer)‘community’
blackwater reuse
system
environment
advanced wastewater
treatment plantwastewater
treatment plant
RECYCLED
WATER
effluentconcentrated waste
ultrafiltration / reverse osmosis
effluent
FIGURE 1.2: Transfer of radiopharmaceutical waste to the environment
16
1.1.3 Radiation protection and regulation of residues and wastes containing radioactivity
As our increasing population and industrial development exploits new or recycled water resources
(BCC, 2004), consideration needs to be given to determining the effects that increased water
usage, treatment and disposal will have on the concentration and redistribution of radiologically
enhanced materials and their impact on humans and the environment.
The International Commission on Radiation Protection, through ICRP Publication 103
(ICRP 2007), promotes a unified radiation protection system that is applicable to all exposure
situations and recommends that the system should be implemented to limit exposure to humans
and the environment. ICRP Publication 103 includes protection from waste materials, including
those derived from water treatment, use and process residues, and references an annual dose
constraint of 0.3 mSv per year. Australian regulatory authorities generally adopt ICRP
recommendations via the Australian Radiation Protection and Nuclear Safety Agency
(ARPANSA) Radiation Protection Standard RPS1 (ARPANSA, 2002). While the current
Standard is based on ICRP Publication 60 (ICRP 1991), a statement has been released by the
Australian Radiation Health Committee indicating that RPS1 is currently being reviewed with a
view to publication of a revised Standard incorporating the recommendations of ICRP Publication
103 (RHC, 2010). Australian regulation of NORM residues (and it is reasonable to assume that
similar regulatory issues may be applicable to water treatment related anthropogenic residues and
wastes) has been addressed by ARPANSA (ARPANSA, 2008, 2011), however, it must be noted
that individual States, Territories and the Commonwealth all have a their own regulatory
legislation that must be considered in dealing with these materials. Noting the above constraints, it
is reasonable to consider that the intent of ICRP Publication 103 will be generally adopted when
considering radioactive residues associated with water treatment, use and disposal in Australia.
1.2 Research Objectives
The purpose and scope of the research program is to develop an understanding of the nature,
monitoring and the potential for impact of residual radioactivity associated with the water supply
cycle. This is accomplished by identifying fundamental data and information gaps in the field of
interest, and formulating key study programs to address selected deficiencies. For the purposes of
17
this thesis, the radiological quality of three water resource systems are considered, not only from
the commonly examined ingestion aspect, that is ingestion of potable water, but more related to
the presence of radioactive residues that may be associated with exploitation of the resource. The
three sources examined are surface water, including rivers, lakes and impoundments that are used
to collect catchment runoff, groundwater that is extracted from beneath the surface of the Earth,
and recycled, or ‘manufactured’ water that may be used directly, or indirectly, to supplement
surface and / or groundwater supplies.
The literature review provided in Chapter 2 highlights the current state of knowledge
associated with water utilisation residues, identifies gaps in that knowledge, and supports the
observation that there also exists, at an elementary level, a paucity in evidence based reference
data, suitable radiometric methods and modelling parameters that may be utilised to assess the
impact, or potential for impact, of residual radioactive materials associated with the supply,
treatment, use and disposal of water and water treatment by-products. Addressing the research
objectives was accomplished by identifying the radiological constituents in urban and rural &
remote water sources (groundwater, surface water and recycled wastewater), characterising
technological processes, developing novel sampling, analysis and monitoring methods and
identifying radiation exposure pathways to critical groups.
Specifically, the objectives were to:
• establish locality specific data that could be used in determining and calculating
radiological impact of residues
• develop novel sampling and radioanalytical methods to provide source term data
• assess and characterise radionuclides in materials derived from urban water treatment
plants in southeast Queensland, Australia, to model radiation exposure to humans;
• map radiological properties of groundwater in Queensland, Australia, to establish areas
that may be impacted upon by radioactive residues associated with the exploitation of
groundwater, particularly atypical exposure pathways in remote communities reliant on
groundwater resources; and
18
• develop sensitive radioanalytical monitoring techniques that are required to characterise
radiation source terms that can be used for modelling the impact of radioactive
discharges from wastewater treatment plants. This includes a study of the uptake and
depuration of 131
I by the macroalgae Catenella nipae, and application of the results as a
sentinel monitor for radiopharmaceutical waste discharged to estuarine environments.
1.3 Thesis
The thesis is presented as a compendium of scientific papers which have been published in
international, peer reviewed journals. The common theme in the thesis is to study radioactive
residues and waste streams associated with supply, treatment and use of water. Any health impact
assessment process can be broken down into common components as shown in Figure 1.3. This
thesis addresses the ‘Hazard Identification’ and ‘Exposure Assessment’ components of the impact
assessment process with the work presented providing commonality and key elements in
identification of hazards, potential hazard locations, exposed populations, exposure pathways and
suitable measurement tools.
By breaking down the components of the water resource utilisation cycle given in
Figure 1.4, three specific areas were identified as target study areas where considerable knowledge
gaps exist. Large scale production of water for domestic and industrial use in the urban
environment was considered as an area of interest due to the large volumes of water treated, and
hence the potential for concentration of radioactive elements present in predominantly surface
water supplies supplemented by smaller volumes of groundwater. Chapter 3 explores the
generation of radioactive residual materials as derived from urban water treatment plants (Area #1,
Figure 1.4), and estimates the dose that could be received by community members as a result of
working at the treatment plant, or by use of waste materials generated by the treatment plant.
The second research area in this thesis is devoted to investigating and assessing residues
derived from radioactive elements present specifically in groundwater (Area #2, Figure 1.4). In
Australia, groundwater is a common water resource in rural or remote communities for domestic,
19
light industry, and agricultural purposes. Before an impact assessment of this resource can be
undertaken the source term, that is the groundwater itself, must be characterised. As there is a
significant lack of published information available quantifying the radiological water quality of
groundwater in Queensland, a screening and mapping project was initiated to identify areas where
water radioactivity concentrations were elevated, and an assessment tool developed to establish if
further radiological assessment is warranted. The assessment tool was developed using data
published by the author after undertaking a radiological impact study on a remote community that
utilises groundwater, know to contain elevated radionuclide concentrations of radium, as their sole
water supply source.
20
review & reality check
ISSUE IDENTIFICATION
‘Radioactive Residues Associated
with Water Treatment, Use and
Disposal in Australia’
HAZARD ASSESSMENT EXPOSURE ASSESSMENT
• Analysis of hazard locations
• Identifications of exposed populations
• Identification of exposure pathways
• Measurement of exposure
concentration for pathways
• Measurement of contamination intakes
for pathways
• Uncertainty analysis for exposure
assessment
Hazard Identification
• Collection & analysis of relevant data
• Uncertainty analysis of hazard
identification process
Dose –Response Assessment
• Collection & analysis of relevant data
• Uncertainty analysis of hazard
identification process
CHARACTERISATION
• Characterise potential for adverse health
effects to occur
• Evaluate uncertainty
• Summarise risk information
MANAGEMENT
• Define options and evaluate
environmental health, economic, social
& political aspects of the options
• Make informed decisions
• Take actions to implement the decisions
• Monitor and evaluate the effectiveness
of the action taken
review & reality check
FIGURE 1.3: Model for assessing the impact of radioactive residues associated
with water treatment, use and disposal (adapted from CDHAC, 2001).
21
Finally, the topic of 131
I anthropogenic radiation sources and their impact on
communities, via wastewater discharges, was considered after initial treatment of water and then
use in domestic, industrial and medical applications. Wastewater generated as a result of these
applications has the potential to reintroduce radioactive contaminants into the water cycle (Area
#3, Figure 1.4). Wastewater has been identified as a potential water resource to supplement
dwindling natural sources resulting in construction of advanced water treatment plants. These
plants utilise microfiltration and reverse osmosis processes to recycle urban wastewater effluent.
Assessment of the impact of radioactive contaminants generated as a result of recycling treatment
processes is warranted as a paucity of scientific information is available on the topic. Research
outcomes published in Chapter 5 establish a methodology for the measurement of low level
medical radiopharmaceutical wastes discharged to environmental systems. This is an initial step in
DOMESTIC / INDUSTRIAL & AGRICULTURAL USE
WASTEWATER TREATMENT
ENVIRONMENT
URBAN WATER TREATMENT & DISTRIBUTION
REMOTE / RURAL WATER TREATMENT & DISTRIBUTION
GROUND WATER
SURFACE WATER
GROUND WATER
SURFACE WATER
RECYCLED WATER
STUDY #1
STUDY #2
STUDY #3
FIGURE 1.4: Water resource utilisation cycle and relationship to key study areas.
22
developing monitoring systems that will be used in future projects to assess distribution, biota
accumulation and ultimately impact on humans and the environment.
The combination of publications presented in this thesis serves to contribute new
information and novel methods of gathering information in a cohesive research program
addressing the global topic of assessing radioactive residues associated with water treatment, use
and disposal in Australia.
It is expected that continuing research topics will be forthcoming as a result of this initial
study as the characterisation of radioactivity in water and associated waste streams is of particular
interest to water scientists and the general water industry in Australia at the present time as large
scale water infrastructure projects dominate government and industry investment.
1.4 References
ARPANSA, 2002. Recommendations for Limiting Exposure to Ionizing Radiation (1995) and
National Standard for Limiting Occupational Exposure to Ionizing Radiation (republished
2002). Radiation Protection Series No. 1. Australian Radiation Protection and Nuclear
Safety Agency, Canberra. Australia.
ARPANSA, 2008. Management of Naturally Occurring Radioactive Material (NORM). Radiation
Protection Series No. 15. Australian Radiation Protection and Nuclear Safety Agency,
Canberra. Australia.
ARPANSA, 2011. National Directory for Radiation Protection, republished July 2011, including
Amendments 1-5. Radiation Protection Series No. 6. Australian Radiation Protection and
Nuclear Safety Agency, Canberra. Australia.
BCC, 2004. Water for today and tomorrow – A proposed Integrated Water Strategy for Brisbane.
Brisbane City Council. Brisbane. Australia.
Bluebison, 2010. The water cycle. http://www.bluebison.net, accessed December 2010.
23
Eisenbud, M., 1987. Environmental Radioactivity from Natural, Industrial, and Military Sources.
Third Edition. Academic Press. London.
Graham, I.J., Ditchburn, R.G., Barry, B.J., 1998. 10
Be and 7Be concentrations in New Zealand rain
(September 1995 to August 1997). In proceedings of ‘Radioactivity and the
Environment’, South Pacific Environmental Radioactivity Association Conference
SPERA98. Christchurch, New Zealand. 16-20 February.
Hu, Q.-H., Weng, J.-Q., Wang, J.-S., 2008. Sources of anthropogenic radionuclides in the
environment: a review. Journal of Environmental Radioactivity.
doi:10.1016/j.jenvrad.2008.08.004.
IAEA, 1990. The Environmental Behaviour of Radium. Technical Report Series No. 310.
International Atomic Energy Agency. Vienna.
ICRP, 1991. 1990 Recommendations of the International Commission on Radiological Protection,
ICRP Publication 60. Annuals of the ICRP, 21(1-3).
ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological
Protection, ICRP Publication 103. Ed. J Valentin. Annals of the ICRP, 37(2-4). 1- 332.
Ippolito, J.A., Barbarick, K.A., Elliott, H.A., 2011. Drinking Water Treatment Residuals: A
Review of Recent Uses. Journal of Environmental Quality 40, 1-12.
Jimenez, F., Lopez, R., Pardo, R., Deban, L., Garcia-Talavera, M., 2011. The determination and
monitoring of 131
I activity in sewage treatment plants based on A2/O processes. Radiation
Measurements 46, 104-108.
Kleinschmidt, R., 2000. Radionuclides (Chapter 3.4), in Wastewater recycling health effects
scoping study. Queensland Health Scientific Services, National Centre for
Environmental Toxicology and Envirotest Pty Ltd. Queensland Department of Natural
Resources. State of Queensland. Brisbane.
24
Lal, D., Peters, B., 1962. Cosmic ray produced isotopes and their application to problems in
geophysics, in Wilson, J.G. (Ed.), Progress in Elementary and Cosmic Ray Physics 6.
North Holland, Amsterdam.
Nagai, H., Tada, W., Kobayashi, T., 2000. Production rates of 7Be and 10Be in the atmosphere.
Nuclear Instruments and Methods in Physics Research B 172, 796-801.
NCRP., 1994. Exposure of the Population in the Unites States and Canada from Natural
Background Radiation. National Counsel on Radiation Protection and Measurement,
Report Number 094. Bethesda. USA.
RHC, 2010. Statement on Proposed Changes to Australia’s Radiation Protection Standards
(January 2010). Radiation Health Committee.
http://www.arpansa.gov.au/pubs/rhc/RPS1_proposed_changes.pdf, accessed September
2011.
Shuktomova, I.I., Rachkova, N.G., 2011. Determination of 226
Ra and 228
Ra in slightly mineralised
natural waters. Journal of Environmental Radioactivity 102, 84-87.
Sidu, K.S., Breithart, M.S., 1998. Naturally Occurring Radium-226 and Radium-228 in Water
Supplies in Michigan. Bulletin of Environmental Contamination and Toxicology 61, 722-
729.
CDHAC., 2001. Health Impact Assessment Guidelines. Commonwealth Department of Health
and Aged Care. Canberra.
25
CHAPTER 2
2 Literature Review
2.1 Current State of Knowledge
Water streams associated with natural, industrial, agricultural, recreational and domestic supplies
contain radioactive material (Arogunjo et al., 2009; Campbell, 2009; Carvalho et al., 2008; Hu et
al., 2008). The radioactivity may be a naturally occurring radioactive material or introduced as an
anthropogenic source. The subject of radiation exposure in general (ICRP, 2007), and of the
effects of radioactive material present in drinking water may have on humans have been widely
researched and published (UNSCEAR, 2000). Much of the data has been used in the formulation
of water quality guidelines identifying allowable concentration of gross alpha and gross beta
radioactivity, and activity concentrations of individual radionuclides in water. Australian
radiological water quality guidelines are addressed at considerable length in documents including
ANZECC/ARMCANZ (2000) and NHMRC (2004), and globally by the European Union (EU,
1998), Kocher (2001), USEPA (2000) and WHO (2004).
Wastewater derived from domestic, medical, research and industrial processes is also
likely to contain radionuclides. The process of removal of contaminants from water supplies or
wastewater by treatment regimes, often not directly aimed at the removal of radioactive materials,
may concentrate radionuclides in treatment plants, process by-products and wastes. Radiation
exposure to treatment plant operators, by-product consumers, the public (via. landfill disposal or
effluent discharge) and the environment must be assessed to ensure that health protection and
regulatory obligations are met. Published information on the impact of contaminants removed
from water upon treatment, and discharge of wastewater and associated waste streams that may
have become radiologically contaminated, is limited.
The subject of generation of Technologically Enhanced Naturally Occurring Radioactive
Materials (TENORM) during water resource exploitation is a current topic both in Australia and
other countries (Bhattacharyya, 1998; Fisher et al., 1996; Gafvert et al., 2002; IAEA, 2003;
Palomo et al., 2010; USEPA 2005). Bhattacharyya (1998), Gafvert et al. (2002) and Palomo et al.
26
(2010) provide overviews of NORM type wastes associated with water treatment, their sources
and properties. Bhattacharyya (1998) focuses on mobility of the radionuclides in the environment
and compares the NORM waste disposal policies to that applied to nuclear fuel cycle wastes.
Fisher et al. (1996) conducted both short term and medium term studies on the impact of 222
Rn
outgassing from groundwater on water treatment plant operators. 222
Rn concentrations as high as
4 kBqm-3
were measured in the studies, indicating the need to monitor 222
Rn concentration in the
water treatment plant to assess worker dose. Ippolito et al. (2011) provide a general overview of
contaminants that may be present in drinking water treatment residues, but only superficially
covers NORM presence and impact. The Australian Radiation Health & Safety Advisory Council
(RHSAC, 2005) has released a discussion paper on TENORM generation in Australia, initial
findings highlighting that there is a lack of published data on the radionuclide content of materials
and / or solid wastes generated by industries such as water and wastewater treatment.
Cooper (2005) highlights that local information is extremely limited, stating that there have not
been any published Australian studies on radionuclide concentrations in sludges, used filter
elements, and ion exchange or reverse osmosis cartridges from treatment plants, which supports
the need for an investment in defining the magnitude of radiologically impacted waste generation
in Australia from these processes. Cooper’s report for the Australian Radiation Health Safety
Advisory Council uses data from international studies as a guide to potential radionuclide
inventories generated locally.
A guideline document detailing management practices for radioactive residuals derived
from drinking water technologies has been developed by the USEPA (2005). In addition to this
guideline document, a software program has been developed to calculate quantities of wastes,
including radioactive wastes, generated from a number of treatment processes (SPARRC, 2003).
While the software program simplifies the calculation of radionuclide inventories that may be
generated, local input parameters are required for raw water radionuclide concentrations and
radionuclide removal factors. While SPARRC does not evaluate the impact of generated wastes,
software codes such as RESRAD (ANL, 2010) are capable of calculating radiation dose to critical
groups, both occupationally exposed and as members of the public.
27
There is also the potential for accumulation of radionuclides in water distribution
systems, point-of-entry water treatment systems and point-of-use water treatment systems.
Radionuclide accumulation can also occur during industrial processes, and in wastewater
collection and treatment plants. Szabo et al. (2008) conducted an investigation into the fate of
radium removed from groundwater by ion-exchange treatment. The study examined the effect of
disposal of the ion-exchange regeneration brine to septic tanks, and exposure pathways associated
with maintenance of the tank and disposal of sludge. Szabo concluded that little impact was
evident, and that the radium concentration residing in the septic tank sludge was no greater than
that found at larger, local potable water treatment plants. Kleinschmidt (2006) investigated the
accumulation of radon (as 222
Rn) and progeny in domestic point-of-use water purifying cartridges
and identified that break-through of radioactive contaminants was observed in combined activated
carbon / particulate filters well before the stated cartridge replacement date. Ingestion of progeny
radionuclides, and hence dose due to ingestion, peaked in the first use of the potable water system.
NORM may also be evident in wastewater treatment systems, especially in small
community systems that rely on groundwater. The impact of groundwater derived NORM has
been studied in many countries (Avwiri et al., 2007; Fisher et al., 1996; Focazio et al., 1998;
Hopke et al., 2000; Martin, 1984; Mose et al., 2001; Orloff et al., 2004; Szabo et al., 2008), and to
a lesser degree in Australia (Cassels, 1990; Herczeg and Dighton, 1998; Kleinschmidt, 2007;
Koulouris et al., 1996; Lokan, 1998; Long et al., 2008). Assessments of the use, distribution, fate
and impact of groundwater derived radionuclides are scarce in Australia, the topic has been
identified as an area requiring research (Lokan, 1998; RHSAC, 2005). Review of the literature
also suggests that many of the radionuclide monitoring and screening methods promoted in
Australian water monitoring programs (e.g. use of gross activity screening programs as opposed to
radionuclide specific testing) are misused by water industry stakeholders and deficient in
identifying potential exposure pathways (Kleinschmidt, 2004; Ruberu et al., 2008; Sanchez et al.,
2009; Wisser et al., 2006; Zapata-Garcia et al., 2009) and that resources should be directed to
developing suitable methods. Lokan (1998) establishes that information on remote community
water supplies is extremely limited and that there is a need to improve the information base on
aspects of underground supplies and a further need to identify vulnerable regions.
28
Publications such as that authored by Titley et al. (2000) address the sources, fate and
impact of medical and industrial radioactive discharges to public sewers in the United Kingdom,
but are deficient in covering typical Australian scenarios including land spreading of biosolid
wastes as opposed to incineration, and lack in addressing dose to sewer workers in proximity to
source load points. Of particular interest is the fate of medical radionuclides discharged to
domestic sewers. The presence, and in some cases the impact, of these materials has been
documented internationally (Ault, 1989; EU, 1995; Fenner and Martin, 1997; Fischer et al., 2009;
Goddard, 1999; Ipek et al., 2004; Jimenez et al., 2011; Larsen et al., 1995; Larsen et al., 2001;
Martin and Fenner, 1997; Miller et al., 1996; Titley et al., 2000). Fischer et al. (2009) have
recently explored the distribution of medical radiopharmaceutical wastes including 123
I, 131
I, 99m
Tc
and 153
Sm in river systems downstream of Wastewater Treatment Plants (WWTP). By comparing
distribution data with 7Be and
137Cs results from samples, they were able to conclusively establish
the WWTP as the source of discharge. Only recently are Australian studies becoming available
(Carolan et al., 2009). Carolan et al. studied the impact of 131
I wastes discharged from WWTPs in
Sydney using the ERICA model (Brown et al., 2008) for biota. Macroalgae common to the
WWTP outfall (Ulva sp. and E. radiata) were also utilised as sentinels, utilising their
bioaccumulation characteristics to monitor distribution. The study found that doses to selected
biota were more than 100 times less than the ERICA screening level of 10µGyh-1
(marine biota).
All dose rates to humans were well below individual dose limits for public exposure (1 mSvy-1
),
and the dose constraint for public exposure for radioactive waste disposal of 0.3 mSvy-1
(ICRP,
2007).
Local radiation control regulations prescribe allowable disposal concentrations of
radiopharmaceuticals to the sewer (OQPC, 2004). In many cases the facility disposing of these
products will use the volume of water discharged from the wastewater treatment plant for dilution
calculations, justifying the practice on the basis that no-one will come in contact with the waste
until discharge to the environment. The possibility that re-concentration of these pharmaceutical
derived radionuclides occurs in wastewater collection infrastructure such as pipes and pumps, in
the wastewater treatment plant and in the environment cannot be ruled out. Such re-concentration
of radionuclides may become more prevalent with the recent trend in establishing wastewater
29
recycling schemes to produce high quality, potable water. Interestingly, studies of the emerging
contaminants in wastewater that may impact of water reuse schemes tend to neglect the presence
of radioactive materials and wastes (Bolong et al., 2009).
The measurement of low levels of radioactive wastes in the environment is paramount to
the success of assessing radiological impact. Bioaccumulators such as macroalgae have been
documented as being effective in monitoring for the presence of contaminants that would
otherwise be difficult to quantify (Costanzo, 1991; Cuvin-Aralar and Umaly, 1991;
Evans and Hammand, 1995; Solimabi, 1977). The use of macroalgae such as Catenella nipae for
monitoring stable isotope pollutants (Costanzo, 1991) and as an indicator of estuary health
(Melville and Pulkownik, 2006) has been reported.
Review of the available literature suggests that while studies have been conducted on the
radiological impact of radioactive wastes derived from water use, they are, however, based on
processes not typically employed within the Australian water industry, or do not relate to the
specific water supply situations .
It is important to focus on the point that this work assesses, or aims to provide novel
information and data required to conduct the overall assessment processes related to the presence
of radioactivity in water, not just that associated with ingestion through the potable water exposure
pathway. Justification for this work is highlighted by a lack of published, evidence based,
scientific data as conceded by peak Australian radiation scientific organisations including the
Australian Radiation Protection and Nuclear Safety Agency (Lokan, 1998), and professional
radiation protection advisory bodies including the Australian Radiation Health & Safety Advisory
Council (RHSAC, 2005). Of equal importance is the need to promote scientific studies for transfer
of evidence based data to water quality policy makers. This will ensure that transparent and
technically sound decision making processes are employed on publically important water quality
related policy issues (Mossman, 2009).
30
2.2 References
ANL, 2010. Developing the RESRAD Family of Computer Codes, Environmental Assessment
Division of the Argonne National Laboratory. www.ead.anl.gov, accessed 08 February
2010.
ANZECC/ARMCANZ, 2000. Australian and New Zealand Guidelines for Fresh and Marine
Water Quality. National Water Quality Management Strategy Paper No. 4. Australian
and New Zealand Environmental and Conservation Council & Agricultural and Resource
Management Council of Australia and New Zealand. Australian Government Publishing
Service. Canberra. Australia.
Arogunjo, A.M., Hollriegl, V., Giussani, A., Leopold, K., Gerstmann, U., Veronese, I., Oeh, U.,
2009. Uranium and thorium in soils, mineral sands, water and food samples in a tin
mining area in Nigeria with elevated activity. Journal of Environmental Radioactivity
doi: 10.1016/j.jenvrad.2008.12.004
Ault, M.R., 1989. Gamma emitting isotopes of medical origin detected in sanitary waste samples.
Radiation Protection Management 6, 48-52.
Avwiri, G.O., Tchokossa, P., Mokobia, C.E., 2007. Natural radionuclides in borehole water in
Port Harcourt, Rivers State, Nigeria. Radiation Protection Dosimetry 123(4), 509-514.
Bhattacharyya, D.K., 1998. Issues in the disposal of waste containing naturally occurring
radioactive material. Applied Radiation and Isotopes 49, 215-226.
Bolong, N., Ismail, A.F., Salim, M.R., Matsuura, T., 2009. A review of the effects of emerging
contaminants in wastewater and options for their removal. Desalination 239, 229-246.
Brown, J.E., Alfonso, B., Avila, R., Beresford, N.A., Copplestone, D., Prohl, G., Ulanovsky, A.,
2008. The ERICA Tool. Journal of Environmental Radioactivity 99(9), 1371-1383.
Campbell, K.M., 2009. Radionuclides in Surface Water and Groundwater, Chapter 10. Handbook
of Water Purity and Quality. Editor: Ahuja, S. IWA Publishing, London.
31
Carolan, D.V., Hughes, C.E., Hoffman, E.L., 2009. Dose assessment for marine biota and humans
from discharge of 131
I to the marine environment and uptake by algae in Sydney,
Australia. Journal of Environmental Radioactivity doi: 10.1016/j.jenrad.2009.10.002.
Carvalho, F.P., Madruga, M.J., Oliveira, J.M., Lopes, I., Ferrador, G., Sequeira, M.M., 2008.
Naturally-Occurring Radionuclides in Drinking Water from Surface and Groundwater
Reservoirs. The Natural Environment – 8th
International Symposium, edited by A.S.
Paschoa. American Institute of Physics. USA.
Cassels, B.M., 1990. Radium-226 in natural water supplies in Kakadu National Park. Radiation
Protection in Australia 8(2), 31-35.
Cooper, M.B., 2005. Naturally Occurring Radioactive Materials (NORM) in Australian Industries
– Review of Current Inventories and Future Generation. Report Number ERS-006
(Revision of September 2005) prepared for the Radiation Health & Safety Advisory
Council. EnviroRad Services Pty Ltd, Australia.
Costanzo, S.D., O’Donohue, M.J., Dennison, W.C., 1991. Assessing the seasonal influence of
sewage and agricultural nutrient inputs in a subtropical river estuary. Estuaries 26 (4A),
857-865.
Cuvin-Aralar, L.A., Umaly, R.C., 1991. Accumulation and tissue distribution of radioiodine
(I-131) from algal phytoplankton by the freshwater clam Corbicula manilensis. Bulletin
of Environmental Contamination and Toxicology 47, 896-903.
Evans, G.J., Hammad, K.A., 1995. Radioanalytical Studies of Iodine Behaviour in the
Environment. Journal of Radioanalytical and Nuclear Chemistry 192, 239-247.
EU, 1995. Methodology for assessing the radiological consequences of routine releases of
radionuclides to the environment. European Commission Report No. EUR 15760.
European Commission, Luxembourg.
EU, 1998. Drinking Water Directive. Council Directive 98/83/EC on the quality of water intended
for human consumption. European Commission, Luxembourg.
32
Fenner, F.D., Martin, J.E., 1997. Behaviour of Na131
I and meta(131
I) Iodobenzylguanidine (MIBG)
in municipal sewerage. Health Physics 73, 333-339.
Fischer, H.W., Ulbrich, S., Pittauerova, D., Hettwig, B., 2009. Medical radioisotopes in the
environment – following the pathway from patient to river sediment. Journal of
Environmental Radioactivity doi: 101016/j.jenvrad.2009.05.002.
Fisher, E.L., Fuortes, L.J., Field, R.W., 1996. Occupational exposure of water-plant operators to
high concentrations of radon-222 gas. Journal of Occupational & Environmental
Medicine 38, 759-764.
Focazio, B.J., Szabo, Z., Kraemer, T.F., Mullin, A.H., Barringer, T.H., DePaul, V.T., 1998.
Occurrence of selected radionuclides in ground water used for drinking water in the
United States: A reconnaissance survey. Water-Resources Investigations Report 00-
4273. U.S. Geological Survey.
Gafvert, T., Ellmark, C., Holm E., 2002. Removal of radionuclides at a waterworks. Journal of
Environmental Radioactivity 63, 105-115.
Goddard, C., 1999. The use of delay tanks in the management of radioactive waste from thyroid
therapy. Nuclear Medicine Communications 20, 85-94.
Herczeg, A.L., Dighton, J.C., 1998. Radon-222 concentrations in potable groundwater in
Australia. J. Australian Water & Wastewater Assn. (WATER) 25, 37.
Hopke, P.K., Borak, T.B., Doull, J., Cleaver, J.E., Eckerman, K.F., Gundersen, J.C.S., Harley,
N.H., Hess, C.T., Kinner, N.E., Kopecky, K.J., McKone, T.E., Sextro, R.G., Simon, S.L.,
2000. Health risks due to radon in drinking water. Environmental Science and
Technology 34, 921-926.
Hu, Q.-H., Weng, J.-Q., Wang, J.-S., 2008. Sources of anthropogenic radionuclides in the
environment: a review. Journal of Environmental Radioactivity
doi:10.1016/j.jenvrad.2008.08.004.
33
IAEA, 2003. Extent of Environmental Contamination by Naturally Occurring Radioactive
Material (NORM) and Technological Options for Mitigation. Technical Report Series
No. 419. International Atomic Energy Agency. Vienna.
ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological
Protection, ICRP Publication 103. Ed. J Valentin. Annals of the ICRP 37(2-4). 1- 332.
Ipek, U., Arslan, E.I., Aslan, S., Dogru, M., Baykara, O., 2004. Radioactivity in municipal
wastewater and its behaviour in biological treatment. Bulletin of Environmental
Contamination and Toxicology 72, 319-325.
Ippolito, J.A., Barbarick, K.A., Elliott, H.A., 2011. Drinking Water Treatment Residuals: A
Review of Recent Uses. Journal of Environmental Quality 40, 1-12.
Jimenez, F., Lopez, R., Pardo, R., Deban, L., Garcia-Talavera, M., 2011. The determination and
monitoring of 131
I activity in sewage treatment plants based on A2/O processes. Radiation
Measurements 46, 104-108.
Kleinschmidt, R.I., 2004. Gross alpha and beta activity analysis in water – a routine laboratory
method using liquid scintillation analysis. Applied Radiation and Isotopes 61, 333-338.
Kleinschmidt, R., 2006. Residual radioactivity from the treatment of water for urban domestic
applications. Environmental Health Risk III. WIT Transactions on Biomedicine and
Health. 9, 373-382. WIT Press, Wessex Institute of Technology, United Kingdom.
Kleinschmidt, R., 2007. Radiological impact of groundwater use – Kings Canyon. Northern
Territory, Australia. Report 06PQ229, Northern Territory Power and Water Corporation.
Queensland Health Forensic and Scientific Services, Brisbane. Australia.
Kocher, D.C., 2001. Drinking water standards for radionuclides: the dilemma and a possible
resolution. Health Physics 80, 486-490.
Koulouris, G., Dharmasiri, J., Akber, R.A., 1996. Radioactivity in Helidon Spa Waters. Radiation
Protection in Australia 14(4), 87-90.
34
Larsen, I.L., Stetar, E.A., Giles, B.G., Garrison, B., 2001. Concentrations of Iodine-131 released
from a hospital into a municipal sewer. RSO Magazine 6, 13-18.
Larsen, I.L., Stetar, E.A., Glass, K.D., 1995. In-house screening for radioactive sludge at a
municipal wastewater treatment plant. Radiation Protection Management 12, 29-38.
Lokan, K.H., 1998. Drinking water quality in areas dependent on groundwater. Radiation
Protection in Australasia 15, 11-14.
Long, S., Sdraulig, S., Hardege, L., McLeish, J., 2008. The radioactive content of some Australian
Drinking Waters. Technical Report No. 148. Australian Radiation Protection and
Nuclear Safety Agency, Australia.
Martin, J.E., Fenner, F.D., 1997. Radioactivity in municipal sewage and sludge. Public Health
Reports 112, 308-316.
Martin, P., 1984. On the Natural Radioactivity of Potable Waters in Saudi Arabia. Health Physics
- Notes 46, 947-949.
Melville, F. and Pulkownik, A., 2006. Investigation of mangrove macroalgae as bioindicators of
estuarine contamination. Marine Pollution Bulletin 52, 1260-1269.
Miller, W.H., Kunze, J.F., Banerji, S.K., Li, Y.C., Graham, C., Stretch, D., 1996. The
determination of radioisotope levels in municipal sewage sludge. Health Physics 71, 286-
289.
Mose, D.G., Munrush, G.W., Simoni, F.V., 2001. Variations of well water radon in Virginia and
Maryland. Journal of Environmental Science & Health Part A - Toxic/Hazardous
Substances & Environmental Engineering 36, 1647-1660.
Mossman, K., 2009. Policy decision-making under scientific uncertainty: Radiological risk
assessment and the role of expert advisory groups. Health Physics 97(2), 101-106.
35
NHMRC, 2004. Australian Drinking water Guidelines. National Water Quality Management
Strategy Paper No. 6, National Health and Medical Research Council, Australian
Government Publishing Service, Canberra.
Orloff, K.G., Mistry, K., Charp, P., Metcalf, S., Marino, R., Shelly, T., Melaro, E., Donohoe,
A.M., Jones, R.L., 2004. Human exposure to uranium in groundwater. Environmental
Research 94, 319-326.
OQPC, 2004. Radiation Safety Regulation 1999. Reprint No.2C. Office of the Queensland
Parliamentary Counsel, Brisbane. Australia.
Palomo, M., Penalver, A., Aguilar, C., Borrull, F., 2010. Presence of naturally Occurring
Radioactive materials in sludge samples from several Spanish water treatment plants.
Journal of Hazardous Materials 181, 716-721.
RHSAC, 2005. Naturally-Occurring Radioactive Material (NORM) in Australia: Issues for
Discussion. Radiation Health & Safety Advisory Council Report to the CEO, ARPANSA,
Australia.
Ruberu, S.R., Liu, Y.G., Perera, S.K., 2008. An improved liquid scintillation counting method for
the determination of gross alpha activity in groundwater wells. Health Physics 95(4),
397-406.
Sanchez, A.M., Saenz Garcia, G., Jurado Vargas, M., 2009. Study of self-attenuation for
determination of gross alpha and beta activities in water and soil samples. Applied
radiation and Isotopes 67(5), 817-820.
Solimabi, D.B., 1977. Distribution of iodine in marine algae of Goa Region. Indian Journal of
Marine Science 6, 180-181.
SPARRC, 2003. Software Program to Ascertain Residual Radionuclide Concentrations –
Version 1. United States Environmental Protection Agency, Washington. USA.
36
Szabo, Z., Jacobsen, E., Kraemer, T.F., Parsa, B., 2008. Concentrations and environmental fate of
Ra in cation-exchange regeneration brine waste disposed to septic tanks and accumulation
in sludge, New Jersey Costal Plain, USA. Journal of Environmental Radioactivity 99,
947-964.
Titley, J.G., Carey, A.D., Crockett, G.M., Ham, G.J., Harvey, M.P., Mobbs, S.F., Tournette, C.,
Penfold, J.S.S., Wilkins, B.T., 2000. Investigation of the sources and fate of radioactive
discharges to public sewers. R&D Tech Report No. P288. UK Environment Agency,
Bristol, UK.
UNSCEAR, 2000. Sources and effects of ionizing radiation. United Nations Scientific Committee
on the Effects of Atomic Radiation 2000. Report to the General Assembly, with scientific
annexes. United Nations, New York.
USEPA, 2000. National Primary Drinking Water Regulations; Radionuclides; Final Rule.
Environmental Protection Agency 40 CFR Parts 9, 141 and 142: Washington, USA.
USEPA, 2005. A Regulators’ Guide to the Management of Radioactive Residuals from Drinking
Water Treatment Technologies. United States Environmental Protection Agency. EPA
816-R-05-004, Washington, USA.
WHO, 2004. Guidelines for drinking-water quality, 3rd
Edition. World Health Organisation,
Geneva.
Wisser, S., Frenzel, E., Dittmer, M., 2006. Innovative procedure for the determination of gross
alpha / gross beta activities in drinking water. Applied Radiation and Isotopes 64(3) 368-
372.
Zapata-Garcia, D., Llaurado, M., Rauret, G., 2009. Establishment of a method for the rapid
measurement of gross alpha and gross beta activities in sea water. Applied Radiation and
Isotopes 67(5), 978-981.
37
CHAPTER 3
Naturally occurring radionuclides in materials derived from urban water
treatment plants in southeast Queensland, Australia
Ross Kleinschmidta,b
and Riaz Akbera
aQueensland University of Technology, School of Physical and Chemical Sciences, 2 George
Street, Brisbane, Queensland 4000, Australia.
bHealth Physics Group, Queensland Health Scientific Services, Queensland Department of Health,
PO Box 594 Archerfield 4108, Queensland, Australia.
Journal:
Journal of Environmental Radioactivity 99, 607-620. 2008
38
Statement of Joint Authorship
The authors listed below have certified* that:
1. they meet the criteria for authorship in that they have participated in the conception,
execution, or interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible
author who accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or
publisher of journals or other publications, and (c) the head of the responsible academic unit,
and
5. they agree to the use of the publication in the student’s thesis and its publication on the
Australasian Digital Thesis database consistent with any limitations set by publisher
requirements.
In the case of this chapter:
Naturally occurring radionuclides in materials derived from urban water treatment plants
in southeast Queensland, Australia
Contributor Statement of contribution*
Ross Kleinschmidt
Signature
Date
Original concept, conducted field work, provided laboratory facilities, conducted
radioanalytical testing, interpreted data, developed and utilised models, wrote
manuscript.
Riaz Akber Provided concept refinement and development, advice and editorial comments.
Principal Supervisor Confirmation
I have sighted email or other correspondence from all co-authors confirming their certifying
authorship.
AAPRO Riaz Akber
Name Signature Date
39
Abstract
An assessment of radiologically enhanced residual materials generated during treatment of
domestic water supplies in southeast Queensland, Australia, was conducted. Radioactivity
concentrations of 238
U, 232
Th, 226
Ra, 222
Rn, and 210
Po in water, sourced from both surface water
catchments and ground water resources were examined both pre- and post-treatment under typical
water treatment operations. Surface water treatment processes included sedimentation,
coagulation, flocculation and filtration, while the groundwater was treated using cation exchange,
reverse osmosis, activated charcoal or methods similar to surface water treatment. Waste products
generated as a result of treatment included sediments and sludges, filtration media, exhausted ion
exchange resin and wastewaters. Elevated residual concentrations of radionuclides were identified
in these waste products. Solid waste product activity concentrations were used to model the
radiological impact of the materials when either utilised for beneficial purposes, or upon disposal.
The results indicate that, under current water resource exploitation programs, reuse or disposal of
the treatment wastes from large scale urban water treatment plants in Australia do not pose a
significant radiological risk.
Keywords: water treatment, radioactivity, TENORM, waste, Queensland, Australia
40
3.1 Introduction
As the population of southeast Queensland, Australia, continues to increase, the need for adequate
water resources will also rise. Alternative supplies will be required to meet the demands for water
as traditional sources become stressed, and technology based intervention and treatment will
become more common as poorer quality alternative water supplies are exploited.
While radiological quality of water is addressed at considerable length by regional
guideline documents (ANZECC/ARMCANZ, 2000; NHMRC, 2004) and globally (WHO, 2006;
USEPA, 2000; EU, 1998; Kocher, 2001), information on the impact of contaminants removed
from water upon treatment, and discharge of wastewater that may have become radiologically
contaminated, is limited. The subject of generation of Technologically Enhanced Naturally
Occurring Radioactive Materials (TENORM) during water resource exploitation is a current topic
both locally (Cooper, 2005; RHSAC, 2005) and internationally (IAEA, 2003). Cooper (2005)
concedes that local information is extremely limited and recommends an investment in defining
the magnitude of TENORM generation in Australia. The USEPA have recently produced a
guideline document detailing management practices for radioactive residuals derived from
drinking water technologies (USEPA, 2005).
Australia extracts approximately 20 million megalitres (2x1013
L) of water per year from
surface and groundwater resources. Figure 3.1 shows that around 70% is used for agriculture,
12% for domestic purposes and the remainder for industry, loss by evaporation and transmission
(CRCWQT, 2006). It has been established that 64% of Australia’s population lives within the
boundaries of urban regions associated with capital cities and major towns (ABS, 2005), and
therefore represent the highest usage of domestic water. Of the 2.2 million megalitres of water
used for domestic applications, approximately 1.3 million megalitres (59%) is treated before
distribution, the remainder being used as extracted (ABS, 2007; CRCWQT, 2006). This value is
in general agreement with data supplied by Cooper (2005).
41
This study was conducted to quantify and assess the impact of TENORM associated with
the treatment of water destined for domestic purposes, specifically in urban areas of Queensland,
Australia. The radiological properties of residues and waste streams from three locations and one
mineral water bottling plant in south-east Queensland were included in the study. The subject
locations include Brisbane, the capital city of Queensland and two regional towns, Toowoomba
and Dalby (Figure 3.2).
The mineral water bottling plant was located at the base of the Great Dividing Range
between Brisbane and Toowoomba. The locations were chosen as they represent a typical range
of water supply and treatment processes utilised in urban Queensland. Table 3.1 provides a
summary of water supply data and Figure 3.3 describes the water treatment processes used in the
specified locations. In addition to the radiological TENORM assessment of the specified
Queensland locations, water supply and treatment data was collated from several other regional
areas in Queensland and major cities across Australia to allow estimation of national TENORM
inventories and the associated national radiological impact. The regional data in Table 3.1 was
collated from results of a survey of selected local and interstate water authorities, and represents
approximately 50% of domestic water consumers in Australia.
FIGURE 3.1: a) Water statistics by application or end use for Australia (CRCWQRT 2006),
& b) Water usage by states and territories of Australia (AWA 2006).
b) a)
42
3.2 Water Supplies
Brisbane’s treated water supply is currently extracted from a number of dams fed by surface water
catchment areas west of the city. Treatment is provided by three plants, using conventional
processes (Figure 3.3a) including coagulation using aluminium sulphate (alum), settling, filtration
and disinfection. Typical waste streams associated with the treatment processes include alum
concentrate sludges, post coagulation sediments and filter media. All solid wastes are currently
being stockpiled on site. Liquid wastes generated during treatment are fed back to the head of the
plant for reuse and further treatment.
TABLE 3.1: Water supply and treatment data for selected cities and towns.
Water source
(%)
Treatment type
(other than sterilisation)
Location Population
Serviced
30 June
2002
Annual Water
Consumption
per Capita
(ML/person)
Su
rfa
ce w
ate
r
Gro
un
dw
ate
r
No
ne
Co
nven
tio
na
l
Ion
-ex
cha
ng
e
Rev
erse
osm
osi
s
oth
er
Brisbane 1 689 100 0.148 100 0
•
Toowoomba 94 043 0.153 89 11
• •
Dalby 10 199 0.255 23 77
• •
Cairns 125 132 0.200 100 0
•
Mackay 79 824 0.165 91 9
• •
Mineral
Water plant
(Helidon,
Qld)
< 1000 - 0 100
•
Sydney
(NSW)
4 170 927 0.126 100 0
•
Perth area
(WA)
1 413 651 0.186 41 59 • • •
Darwin area
(NT)
107 373 0.357 90 10 •
43
Toowoomba is situated about 130km west of Brisbane and is located on the eastern rim of
the Australian Great Dividing Range. Toowoomba was chosen for the study as it is typical of
small cities in the region, undergoing continued growth (1.4% per annum, QDLGPSR, 2004) and
drawing its water supply from a combination of surface and groundwater, specifically three
surface water catchment and storage dams, and thirteen groundwater bores. Toowoomba’s surface
water treatment plant (WTP) is capable of operating as a conventional WTP (Figure 3.3a), but at
the time of this study was being operated in contact filtration mode only, bypassing the
coagulation and settling stages. The filtration system consists of a bed of anthracite filter coal over
graded sand and fine gravel. Backwash from the filter beds is recycled to the head of the plant for
reprocessing. Dried sludge generated from the plant is stockpiled on site and removed for
beneficial land-use applications, including use as a soil conditioner. The groundwater bores are
located throughout the city and tap into a number of disjointed aquifers. Only 2 bores were in use
for potable supply at the time of this study. In both cases the groundwater is passed through a
cation exchange resin prior to injection into the city water distribution system (Figure 3.3b).
Wastes generated by the system include exchange resin and regeneration backwash. Expired resin
is disposed of by controlled landfill while the regeneration backwash fluids are discharged to the
sewer.
FIGURE 3.2: Location of study areas in south-east Queensland,
Australia.
44
Dalby is the smallest of the areas studied and serves a population of around 10 000
people. It is located 215 km west of Brisbane. The water supply is predominantly drawn from 12
groundwater bores but may be supplemented by water extracted from the Condamine River. Water
from 9 alluvium groundwater bores adjacent to the Condamine River, after fluoridation and
disinfection, is fed into the distribution system as extracted. The remaining 3 bores are treated by
reverse osmosis (RO) at the town water treatment plant (Figure 3.3c). The surface water treatment
plant operates as a conventional WTP (Figure 3.3a) when in use. Sludges and backwash from the
plant are discharged to the Condamine River, downstream from the WTP inlet. Liquid wastes
generated by the RO plant are discharged to evaporation ponds. Solid wastes buried in landfill
include pre-filter media and up to 56 membrane cartridges per year.
The mineral water bottling plant is located at Helidon, approximately 110km from
Brisbane. Water for the plant is extracted from a single bore and passes through a reverse osmosis
plant prior to bottling. Liquid waste from the plant is dispersed to the environment after blending
with raw water. Expired RO membrane cartridges are removed by the plant maintenance service
provider, ultimate disposal being buried in landfill. The Helidon area has been the subject of
previous studies relating to radioactivity in water (Cooper et al., 1981; Kourlouris et al., 1996)
with bores in the area producing radium concentrations of up to 1.8 BqL-1
.
Queensland has no nuclear industries other than a limited use of sealed and unsealed
radioactive sources for medical and research applications, and the use of sealed industrial sources.
It is assumed that naturally occurring radionuclides are the predominant species likely to be found
in the environment. At the time of writing, no active wastewater recycling re-use programs
operated in conjunction with the potable water supplies under investigation. Credible solid waste
disposal options are considered in calculating the dose to members of critical population groups.
Dose associated with liquid wastes are not considered in this assessment and are the topic of a
separate study.
45
BORE
PLANT
ION EXCHANGE
DISINFECTION
REGEN WASTE
TO SEWER
SOLID WASTES
STORAGE /
DISTRIBUTION
BORE
PLANT
DISINFECTION
FLUORIDATION
LIQUID WASTE
TO EVAP. POND
SOLID WASTES
STORAGE /
DISTRIBUTION
RO PLANT
FIGURE 3.3: Water treatment processes: a) Typical for all surface water suppliers including Brisbane;
b) Groundwater treatment plant – Toowoomba; c) Groundwater treatment plant – Dalby.
c) b) STORAGE /
RIVER
PLANT
FLOCCULATION
SETTLING
FILTRATION
DISINFECTION
BACKWASH
RECYCLE
SOLID WASTES
STORAGE /
DISTRIBUTION
a)
45
46
3.3 Sampling Details and Methods
3.3.1 Sampling
Water samples were collected in 10 L acid washed polyethylene bottles for 210
Po, 226
Ra, uranium
and thorium radionuclide assay methods. Samples were acidified with concentrated nitric acid (to
pH 2) in the laboratory and sub-sampled as required. Samples were held for a minimum period of
16 hours post preservation to ensure radionuclides remain dissolved in the sample, and to prevent
adsorption to the sample container surfaces (Katzlberger et al., 2001).
Radon in water samples were collected in either 20 mL glass scintillation vials
(groundwater) or 1 L acid washed glass Erlenmeyer flasks (surface water). Surface water samples
were collected by gently submerging the 1 L flask beneath the water surface to a depth of 500 mm.
The cap was removed and the flask filled to capacity, the cap being replaced while still submerged
to eliminate any headspace. Sampling of water from treatment plants and distribution systems was
conducted using the procedure stated in ASTM (1998). Samples were then chilled on ice and
returned to the laboratory for analysis as soon as possible.
Sediment, sludge, ion exchange resin and filter bed samples were collected in either 1 L
detergent washed glass bottles or clean plastic bags.
3.3.2 Methods - Water
a. Radon (222
Rn) Two methods were used for 222
Rn analysis depending on the required
minimum detection level. For samples collected in 20 mL vials, direct counting (ASTM, 1998)
was conducted on 15mL aliquots of water after addition of 5 mL of a mineral oil based
scintillation cocktail (Perkin Elmer Mineral Oil
).
The 222
Rn samples collected in 1 L Erlenmeyer flasks were opened and 20 mL of water
removed and discarded. The void was replaced with 15 mL of mineral oil scintillator and the
flask recapped. The flask was then vigorously shaken for 15 minutes to allow for the preferential
transfer of dissolved radon into the scintillation cocktail. The mixture was allowed to rest for
47
24 hours to allow separation of aqueous and oil phases. The scintillator was then extracted for
counting. All samples were sealed and allowed to sit for a minimum of 3 hours to allow in-growth
of decay progeny.
Counting of samples from either method was conducted using a Packard TriCarb
3170TR/SL liquid scintillation analyser. Respective minimum detection levels of 80 mBqL-1
and
20 mBqL-1
were achieved for these methods using a count time of 200 minutes.
b. Radium (226
Ra) A 222
Rn emanation method was used for 226
Ra determinations. Samples
were prepared by pre-concentrating 1000 mL of water sample to 15 mL by evaporation. The
concentrated samples were transferred to Teflon coated poly vials and 5 mL of mineral oil
scintillator added to trap the radon gas. The vials were capped and stored for a minimum of 15
days to allow equilibration of 222
Rn. Analysis was conducted as for the 222
Rn method. A minimum
detection level of 2 mBqL-1
was obtained using this method for a 180 minute counting time.
c. Polonium (210
Po) 210
Po was determined using a method published by EML (1997).
Water samples of 1000 mL were pre-concentrated by evaporation to a volume of 200 mL before
210Po deposition on 20 mm diameter nickel foil discs. The foils were transferred to a 20 mL
polyethylene scintillation vial containing a translucent raised platform, cocktail added and then
counted with the LSA. Extraction and alpha counting efficiency were observed to be greater than
60% for the method with a minimum detection level of 8 mBqL-1
for a counting time of 180
minutes.
d. Uranium and Thorium analysis was conducted using direct measurement of 238
U and
232Th by ICPMS (Agilent 7500 ICPMS Chem Station) using in-house methods (QHSS, 2000).
48
3.3.3 Methods - Solid wastes
Radioactivity concentrations in solid wastes were determined using high resolution gamma-ray
spectrometry (EG&G Gamma-X germanium detector, ~40% rel. eff. + EG&G Dspec Plus
spectrometer). The gamma-ray spectrometer was calibrated using IAEA RGU-1 reference
material in a standard geometry. Samples were dried to constant mass and sealed in 100 mL
polyethylene jars for a minimum of 20 days (to allow radium series decay progeny to reach secular
equilibrium) before counting. Typical counting times were 100000 seconds.
3.3.4 Method validation
All methods used for analysis of water, sludges and other materials were conducted within a
quality system certified (ISO, 9001) laboratory environment where methods are developed,
validated and undergo routine quality assurance processes. Accuracy and precision of water
radioanalytical methods were determined by spiking three, one litre deionised water samples with
international standard traceable reference solutions. A total of five 226
Ra (Amersham, RAY44,
soln. R4/131/158) spiked samples ranging from 27 mBqL-1
to 1340 mBqL-1
were chosen for 222
Rn
and 226
Ra trials (the same solutions were used for both radionuclides as the 226
Ra method utilises
222Rn emanation).
222Rn and
226Ra spiked sample results were within 9% of the reference value in
all cases. Four spiking concentrations were used for 210
Po analysis, using a 210
Pb reference
solution (AEA Technology, soln. KE 791), known to be in equilibrium with 210
Po. Activity
concentrations ranged from 43 mBqL-1
to 2140 mBqL-1
. Results were within 12% of the reference
values. A gamma spectrometry validation reference sample was produced, of similar density and
geometry to that used for residue test samples, from a standardised pitchblende material with an
activity concentration of 101 Bqg-1
, and is known to be in equilibrium (Sill and Willis, 1965; Sill,
1977). The reference sample was counted five times and activity concentrations determined for
238U,
226Ra and
210Pb, all results were within 5% of the standard pitchblende material. Verification
of uranium and thorium results by ICPMS is achieved by running blanks and replicates of standard
49
solutions (Agilent Multielement Standard 2A, p/n 8500-6940). ICPMS reference samples were
within 13% of the expected values.
3.3.5 Dose calculation
The impact of radionuclides derived from water treatment processes can be assessed by
determining the avertable dose to critical population groups working with, in close proximity to, or
indirectly with radiologically enhanced materials. There are a number of pathways by which
radioactive materials may interact with humans, including external exposure, inhalation, and
ingestion (Figure 3.4). Dose calculation methodology is based on an analysis of a source term,
environmental transport processes, exposure assessment, and credible scenarios.
Determination of residual radioactivity from water treatment processes identifies and
characterises the source term for dose analysis, by way of sludge / soil activity concentration
measurement. The analysis of environmental transport, exposure and subsequent dose estimation
can be an extremely complex process that varies with location and critical population group, and is
best suited to computer modelling (O’Brien & Cooper, 1998). The RESRAD (ANL, 2007)
computer model was used to estimate the impact of residual radioactivity associated with water
treatment for credible critical population groups. RESRAD was initially developed to assist in the
generation of remediation criteria and to assess the dose associated with residual radioactive
contaminants. Radiation dose and health risks can be modelled over nominated time intervals as
the source term is adjusted to account for physical radioactive decay and ingrowth, leaching,
erosion and mixing. RESRAD has been extensively benchmarked and validated against a number
of radiation exposure pathway models (ANL, 2007; Faillace et al., 1994).
50
FIGURE 3.4: Exposure pathway model for treatment residues
TR
EA
TM
EN
T R
ES
IDU
ES
DIRECT EXPOSURE
RADON
RESUSPENDED DUST
DIRECT INGESTION
INDIRECT INGESTION
PLANT
LIVESTOCK
AQUATIC FOODS
EXTERNAL RADIATION
INHALATION
INGESTION TO
TA
L E
FF
EC
TIV
E D
OS
E T
O R
EC
EP
TO
R
SOURCE ENVIRONMENTAL PATHWAY EXPOSURE PATHWAY DOSE
SURFACE & GROUND WATER
50
51
3.4 Results and Discussion
Results from the water treatment plant survey allowed calculation of quantities of water
treated, and waste generated. Survey results and data are provided in Table 3.2. The data
suggests that local conditions play a significant role in determining raw water quality, how the
water is treated and the subsequent generation of waste. The solid waste derived from surface
water treatment processes was found to range from virtually none to 46 kgML-1
. The variation
in local sediment loads can be attributed to the nature of the land the waters drain from,
including soil types, slope, vegetation, land use and the rainfall patterns in the catchment area.
The data are used to calculate an average mean solid waste mass generated per megalitre of
surface water treated. Our estimate of 14 kgML-1
compares with that reported for some other
countries but it is five times lower than that used by Cooper (2005) to estimate national
inventories of radionuclides produced by water treatment industries in Australia.
3.4.1 Radiological water quality
The results indicate that the radiological properties of all potable water tested were within
Australian drinking water guideline values (NHMRC, 2004).
Table 3.3 provides a summary of results for water sampled from Queensland water
treatment plants targeted for this study and, additionally, provides comparison with published data
for other national and international locations.
In general, radionuclide concentration in bore waters is higher than surface waters, and
radionuclide concentration in treated bore water is less than that of raw water. The uranium
primordial series is in disequilibrium where: ActivityU-238 < ActivityRa-226 < ActivityPo-210. Excess
226Ra concentration in groundwater is due to interaction between the aquifer geology and
groundwater chemistry, and is commonly at a higher concentration than dissolved uranium.
Published data on disequilibria between radium isotopes in groundwater suggests that alpha recoil
mechanisms are a contributing factor, as well as sorption-desorption processes once in solution
52
(Dickson, 1990; Martin and Akber, 1999). Excess 210
Po is most likely ingrowth from dissolved
222Rn.
TABLE 3.2: Waste produced from metropolitan water treatment plants.
Solid Wastes Liquid Wastes Location Water
Consumption
ML/year
t/year kg/ML ML/year kL/ML
Brisbane (Qld) - coagulation 250 000 5700[1] 24 recycled -
Toowoomba (Qld) 14 400 330 23 recycled -
Dalby (Qld) 2 600 120 46 200 77
Cairns (Qld)[2] 25 000 0 0 - -
Mackay (Qld)[2] 13 200 200 15 recycled -
Sydney (NSW)[2] 600 000 3730 6 recycled -
Perth area (WA)[2] 263 000 6500 25 - -
Darwin area (NT)[2] 38 300 0 0 - -
Mean 1 206 500 16 580 14
Australia (Cooper, 2005) 1 400 000 100 000 71
Germany (Hoffman et al., 2000) 5 700 000 125 000 22
USA (IAEA, 2003) 15 000 000 260 000 17
Notes:
[1] dependant on rainfall / flooding events (Townsley R, 2006. Brisbane Water. Personal communication)
[2] survey results, Queensland Health Scientific Services unpublished data
53
TABLE 3.3: Radioactivity concentrations in water (total uncertainty quoted at 95%
confidence interval).
222Rn 226Ra 210Po 238U 232Th Location
BqL-1 mBqL-1 mBqL-1 mBqL-1 mBqL-1
Australia, Queensland (this study)
Brisbane (Mt Crosby) Raw < 0.08 < 1.2 < 6 < 12 < 10
Brisbane (Mt Crosby) Treated < 0.08 < 1.2 13.4 ± 6 < 12 < 10
Brisbane (Qld Health Laboratory) < 0.08 < 1.2 17.1 ± 7 0.3 ± 0.1 17 ± 5
Toowoomba (Mt Kynoch) Raw < 0.08 2 ± 1 7 ± 5 1.2 ± 0.2 < 10
Toowoomba (Mt Kynoch) Treated 0.03 ± 0.02 < 1 9 ± 5 1.8 ± 0.1 < 10
Toowoomba (Stephen St bore) Raw 13.0 ± 0.7 2 ± 1 250 ± 10 < 0.2 < 10
Toowoomba (Stephen St bore) Treated 10.6 ± 0.6 1 ± 1 24 ± 7 < 0.2 < 10
Toowoomba (Milne Bay bore) Raw 17.2 ± 0.9 3 ± 1 52 ± 9 0.8 ± 0.1 < 10
Toowoomba (Milne Bay bore) Treated 14.6 ± 0.8 < 1 2 ± 5 0.8 ± 0.1 < 10
Toowoomba (Harlaxton Park) 0.03 ± 0.02 3 ± 1 9 ± 6 1.1 ± 0.1 < 10
Toowoomba (Laurel Lane Park) 9 ± 1 - - 0.7 ± 0.1 -
Toowoomba (Bowen St Park) 0.2 ± 0.1 - - 1.3 ± 0.1 -
Dalby (Condamine River weir) Raw 0.6 ± 0.1 3 ± 1 23 ± 5 4.7 ± 0.4 < 10
Dalby (Condamine borefield) Raw 8.0 ± 0.6 14 ± 3 10 ± 4 3.6 ± 0.3 < 10
Dalby (WTP/RO bore) Raw 3.0 ± 0.3 6 ± 2 5 ± 4 18 ± 1 < 10
Dalby (WTP/RO bore) Treated 3.3 ± 0.3 < 1 9 ± 4 < 0.2 < 10
Dalby (Council depot) < 0.08 3 ± 1 10 ± 4 3.4 ± 0.3 < 10
Bottled water plant – R/O Raw 13 ± 1 6 ± 1 8 ± 5 < 0.2 < 10
Bottled water plant – R/O Treated 0.4 ± 0.2 4 ± 1 8 ± 4 < 0.2 < 10
Range
Raw water < 0.08 – 17.2 < 1.2 – 14 5 - 250 < 0.2 - 18 < 10 - 17
Treated water < 0.08 – 14.6 < 1.2 – 3 2 – 24 < 0.2 – 3.4 < 10
OTHER STUDIES
Australia, Western Australia
Perth [1] < 0.08 – 1.4 3.8 – 116
International
Spain (Jimenez A et al., 2002) 1.3 2.5
Sweden (Gaefvert et al., 2002) < 1 – 36000 4.3 1.6 1.2
USA (Focazio et al., 2001) 15 0.4
Canada (Health Canada, 2001) < 3 – 25 12 - 105
Reference value (UNSCEAR, 2000) - 0.5 10 1 0.05
Notes:
[1] survey results, Queensland Health Scientific Services unpublished data
54
An unusually high value of 250 ± 10 mBqL-1
of 210
Po in raw groundwater from the Stephen Street
bore, Toowoomba, is a reproducible, but intermittent result that may be associated with
dislodgement of particles or scale within the bore well. Radon concentrations in raw groundwater
supplies are less than the recommended value of 100 BqL-1
(NHMRC, 2004). Groundwater
softening (ion-exchange) did not appear to significantly reduce 222
Rn concentrations post
treatment.
3.4.2 Solid wastes
Radionuclide concentration in solid wastes generated by the water treatment plants is given in
Table 3.4. The predominant waste streams associated with the surface water treatment plant were
the production of sludge and sediments associated with flocculation and settling processes, and
bulk filter media including sand and filter coal. In addition to the coagulated sludge destined for
stockpiling on the WTP sites, Brisbane WTPs produce over 5000 t of alum concentrate per year,
the material being held in storage pending development of a suitable re-use application such as
incorporation into building / construction materials. The activity ranges for radionuclides
observed in this work are in agreement with published values from other studies provided in
Table 3.4.
The sediments in the Dalby evaporation ponds are not primarily generated within the
water treatment system, but are included to provide data on radionuclide concentrations in the
pond sediments as a result of the evaporation of reject water from the reverse osmosis plant.
Radionuclides in these sediments are not subject to radiologically determined control and access
restrictions in Queensland. This situation would need to be assessed should the land use
application of the evaporation ponds change in the future, for example, use of accumulated
sediments as a soil conditioner for agricultural land applications.
55
TABLE 3.4: Radioactivity concentrations in solid waste material (all values are in Bqkg-1
dry
weight, total uncertainty quoted at 95% confidence interval).
Location
238U
226Ra
210Pb
232Th
40K
7Be
Brisbane (Mt Crosby) sludge 1[1] 200 ± 50 60 ± 6 80 ± 20 77 ± 5 140 ± 30 260
Brisbane (Mt Crosby) sludge 2[2] 190 ± 50 74 ± 7 90 ± 20 68 ± 4 210 ± 40 480
Brisbane (Mt Crosby) alum concentrate 70 ± 30 120 ± 10 100 ± 40 78 ± 5 80 ± 30 < 20
Toowoomba (Mt Kynoch) sludge 1[3] 140 ± 50 37 ± 6 90 ± 30 46 ± 5 110 ± 30 170
Toowoomba (Mt Kynoch) sludge 2[4] 130 ± 30 39 ± 3 80 ± 20 50 ± 5 90 ± 20 20 ±
Toowoomba (Mt Kynoch) filter coal – new 60 ± 20 13 ± 3 10 ± 10 16 ± 4 60 ± 20 < 10
Toowoomba (Mt Kynoch) filter coal - used 30 ± 10 16 ± 2 20 ± 10 12 ± 2 < 20 < 10
Toowoomba (Stephen St bore) resin – new < 20 < 2 < 10 < 8 < 20 < 15
Toowoomba (Stephen St bore) resin – used < 20 6 ± 4 110 ± 20 < 8 60 ± 30 < 15
Dalby (WTP evaporation pond 2) sediment 230 ± 30 70 ± 5 80 ± 20 60 ± 7 330 ± 20 9 ± 4
Dalby (WTP evaporation pond 1) sediment 250 ± 50 85 ± 8 110 ± 30 56 ± 6 260 ± 40 < 10
Range
Sediment / sludges 130 – 250 37 – 85 80 - 110 46 - 77 90 – 260 < 10
Filter material / alum conc. 30 – 70 13 – 120 10 - 100 12 - 78 < 20 - 80 < 20
Ion exchange resin < 20 6 110 < 8 60 < 15
OTHER STUDIES
Australia (Cooper, 2005) 11 – 148 8 – 21 - - - -
Sweden (Gaefvert et al,. 2002) 63 - 230 - 370 4.5 - 280
USA (USEPA, 1993) 150 590 410 7.4 - -
Reference value (UNSCEAR, 2000) 68 42 - 46 405 -
Notes:
[1] sample collected from landfill
[2] sample collected from treatment plant conveyor belt prior to landfill
[3] sample from stockpile, less than 30 days post-treatment
[4] sample from stockpile, greater than 60 days post-treatment
56
The cosmogenic radionuclide beryllium 7 (7Be) is present in several sludge / sediment samples
(Table 3.4) as a result of atmospheric deposition and washout into surface water catchment and
storage systems.
The concentration of 7Be (53.3 day half-life, EU, 1999) in the sediments and sludge varies with
the atmospheric availability, water treatment process and the period of time elapsed since
production and removal from the water supply. The 7Be concentration data in Table 3.4
qualitatively confirms the reported ages (provided by the WTP operators) of the sampled
materials.
3.4.3 Liquid wastes
Liquid wastes generated by typical surface water treatment plants (Figure 3.3a) are generally
returned to the head of the water treatment plant, other than the Dalby WTP, and therefore are not
considered as a waste stream released to the environment. Table 3.5 shows radioactivity
concentrations in liquid waste streams generated by ground water treatment plants. Comparison
between values in Table 3.5 and corresponding values for raw and treated water for the same
locations (Table 3.3) suggests evidence of concentration of radionuclides within these
wastewaters. All concentrations measured are within disposal limits for discharge to the sewer
and the environment (OQPC, 2004), or Australian water quality guideline values for drinking,
livestock watering, irrigation and recreational uses (ANZECC/ARMCANZ, 2000).
3.4.4 Radioactive material inventory in WTP sludges and sediments
The total inventory of radionuclides generated from the Queensland water treatment plant sludge
was calculated using results from this study. Conservative radionuclide inventories for 238
U, 226
Ra,
210Pb and
232Th were calculated for each of the study locations using the maximum respective
sludge activity concentrations given in Table 3.4, and sludge production rates given in Table 3.2.
Application of the mean sludge production rate of 14 kg ML-1
(Table 3.2) to the total treated water
57
volume of 1300 GL per annum for Australia (ABS, 2007), assuming that surface water
radionuclide concentrations are similar for each of the major urban regions in Australia, allows
estimation of a national inventory (Table 3.6).
TABLE 3.5: Radioactivity concentrations in liquid wastes (total uncertainty quoted at 95%
confidence interval).
222Rn 226Ra 210Po 238U 232Th Sample
BqL-1 mBqL-1 mBqL-1 mBqL-1 mBqL-1
Toowoomba (Milne Bay bore) Regen. waste 4.2 ± 0.5 6 ± 2 4 ± 5 3.2 ± 0.3 < 10
Dalby (WTP/RO bore) Waste 4.6 ± 0.4 11 ± 2 3 ± 4 71 ± 6 < 10
Dalby (WTP/RO evaporation pond 1) Waste < 0.08 14 ± 2 7 ± 4 66 ± 5 < 10
Dalby (WTP/RO evaporation pond 2) Waste < 0.08 3 ± 1 7 ± 4 81 ± 7 < 10
Bottled water plant – R/O Waste 29 ± 2 32 ± 4 12 ± 6 1.9 ± 0.2 < 10
Range – waste water < 0.08 – 29 3 – 32 3 - 12 1.9 - 81 < 10
TABLE 3.6: Annual radioactive inventory derived from WTP sludge associated with urban
surface water treatment.
Water
consumption
Mean solid
waste[1]
Sludge
produced Total activity per annum (MBq) [2]
Sample
(ML.y-1) (kg ML-1) (t) 238U 226Ra 210Pb 232Th
Brisbane 250 000 5700 1140 340 460 440
Toowoomba 14 000 330 46 13 30 15
Dalby 2 600 120 30 10 13 7
Estimated value
for Australia
1300 000 14 18200 4550 1550 2000 1400
Notes:
[1] from Table 3.2
[2] using maximum sludge activity concentration from Table 3.4
58
3.4.5 Dose calculations
The RESRAD computer model was used to calculate the additional radiation dose to members of
three defined critical population groups. The critical population groups considered are WTP
workers responsible for overseeing sludge disposal operations including the stockpiling of sludge
produced from a WTP, landfill site operators undertaking controlled burial of expired ion-
exchange resin from the groundwater treatment plants as part of their routine duties, and suburban
residents that have acquired sludge from a WTP as a soil conditioner for home cultivation of
vegetables and fruit. In all cases the highest concentration of each radionuclide within the
measured range is used as the source term to provide a conservative estimate.
The WTP operator group result is based on the maximum sludge activity concentration
given in Table 3.4. Results are calculated assuming that a total annual inventory of 5700 t of
sludge is continuously applied in 0.10 m layers over 30 years, for a total depth of 3m, to the
surface of a 40000 m2 site. A dose of 58 µSv y
-1 was calculated for this critical group using the
RESRAD model. Over 94% of the dose can be attributed to gamma exposure, the remainder being
associated with inhalation and ingestion of dust, and inhalation of radon. The total dose modelled
under similar conditions, but using the UNSCEAR (2000) reference soil activity concentrations
(Table 3.4), is 30 µSvy-1
. The dose generated for the operator is approximately twice that for the
reference soil.
For landfill operators, the result is based on the maximum waste ion exchange resin
activity concentration given in Table 3.4. Results are calculated assuming that a total annual
inventory of 80 t of waste resin is buried under controlled landfill conditions, in a bed 20 m long, 2
meters wide and 2 m deep. The resin is covered by 1 m of clean, inactive fill. The calculated dose
to the worker is associated with operating earthmoving plant above the buried waste resin. A dose
of less than 1 µSv y-1
was determined for this critical group using the RESRAD model. Over 99%
of the dose can be attributed to gamma exposure, the remainder being associated with inhalation of
radon.
59
The member of the suburban resident critical group is considered to have acquired 40 m3
of WTP produced sludge for use as a soil conditioner in a residential vegetable garden. The source
term is based on the maximum sludge activity concentration given in Table 3.4, and additional
parameters given in Table 3.7. It is considered that 10% of leafy vegetables consumed by the
resident are produced from the garden. A dose of 205 µSv y-1
was calculated with 89% of the dose
being associated with external gamma dose, 9% with ingestion of food and the remainder by
inhalation of soil (as dust) and radon, and ingestion of soil. Assessment pathways, specific input
parameters for each population group, and model output results are provided in Table 3.7.
3.5 Conclusions
An assessment of radioactivity in raw and supplied water, and residual materials generated in the
treatment of water for urban communities in Queensland was conducted.
Water for domestic and industrial use in the urban locations described is drawn
predominantly from surface water supplies. This observation supports the need for a local
assessment of residual radioactivity derived from water treatment processes as published data are
typically sourced from Europe and the USA where ground water resources are predominantly
exploited.
All potable, treated waters tested in the study meet Australian drinking water guidelines
(NHMRC, 2004). In all but one case (210
Po in a Toowoomba groundwater bore) raw water supplies
also met radiological guideline requirements. All radioactive constituent concentrations that were
monitored fell within current Australian water quality guideline values (ANZECC/ARMCANZ,
2000) for livestock watering, irrigation and recreational purposes.
60
TABLE 3.7: RESRAD modelling parameters and results for critical population groups.
Critical Population Group
Worker
WTP
Worker
Landfill site
Suburban
Resident
Pathway [1]
External gamma exposure YES YES YES
Inhalation of dust YES YES YES
Radon inhalation YES YES YES
Ingestion of plant foods NO NO YES
Ingestion of soil YES YES YES
Ingestion of water NO NO NO
Specific parameters
Radionuclide soil concentrations (refer Table 3.4), Bqg-1
238U
226Ra
210Pb
232Th
40K
0.25
0.09
0.11
0.08
0.26
0.07
0.12
0.10
0.08
0.08
0.25
0.09
0.11
0.08
0.26
Area of contaminated zone, m2 40000 40 40
Thickness of contaminated zone, m 3.0 2.0 1.0
Cover depth, m 0.0 1.0 0.0
Transevaporation ratio [2] 0.6 1.0 0.6
Precipitation rate, m y-1 [2] 1.0 0.9 1.0
Wind speed, m s-1 [2] 3.0 3.0 3.0
Run off coefficient [1] 0.2 0.4 0.4
Exposure duration, years [1] 25 25 30
Breathing (Inhalation) rate, m3 y-1 [1] 11400 11400 8400
Indoor dust fraction 0.0 0.1 0.4
External gamma shielding factor 1.0 0.5 0.7
Fraction of time indoors 0 0 0.25
Fraction of time outdoors 0.09 0.09 0.25
Aust. Plant food consumption, kg y-1 [3] not used not used 225
Contaminated fraction of plant food not used not used 0.1
Soil ingestion, g y-1 36.5 36.5 36.5
Radon – foundation height below ground, m not used not used -0.3
Maximum Dose, mSv y-1 0.058 < 0.001 0.205
Dose % - External 94.37 99.36 89.02
Dose % - Inhalation 2.49 - 0.99
Dose % - Radon inhalation 0.70 0.64 0.50
Dose % - Soil ingestion 2.44 - 0.15
Dose % - Plant ingestion - - 9.34
Notes:
[1] User’s manual for RESRAD Version 6 (ANL, 2007 and Yu et al., 2001), should be read in conjunction with above data. All
unspecified parameters are default RESRAD parameters.
[2] BOM, 2007
[3] McLennan and Podger, 1999
61
Water treatment processes dictated the types and quantities of wastes generated, the quantities also
being dependant on the raw water quality and source. Sludge generated during surface water
treatment contained elevated concentrations of 238
U, 226
Ra and 210
Pb compared to reference
UNSCEAR soils (UNSCEAR, 2000).
Conventional WTP liquid wastes with enhanced concentrations of radioactivity are
generally recycled within the treatment plant and do not constitute a radiation exposure hazard to
the environment or the population. The results from this study show that reverse osmosis liquid
waste has the potential to concentrate radioactive constituents from source waters and the
radionuclide concentration in this waste stream is highly dependent on the nature of the water
supply. In this study the concentrate was transferred to engineered evaporation ponds where
enhanced soil and sediment activity concentrations were observed. Regeneration wastes derived
from the Toowoomba groundwater treatment plants are discharged to the domestic wastewater
system. Current radionuclide concentrations in the regeneration waste do not exceed Queensland
regulatory limits for discharge to the sewer (OQPC, 2005).
The 7Be observed in coagulation sludges derived from conventional WTPs is present due
to concentration of the naturally occurring radionuclide by surface water treatment processes. The
short half-life of 7Be precludes long-term dosimetric contribution to the critical group.
Dose modelling for members of three critical population groups indicates that the
disposal and use of water treatment sludges and residual by-products can contribute to dose. Using
water treatment residual activity concentration data from this study, it can be shown that external
gamma radiation exposure is the most significant dose contributor for the three critical population
groups examined. Members of the suburban resident population group received the highest dose
of the three modelled, with extended occupancy times and ingestion of food cultivated in WTP
sludge calculated to be the most significant exposure pathways.
62
3.6 Acknowledgements
The authors are indebted to the management and staff of Brisbane Water, Toowoomba City
Council and Dalby Shire Council for providing access to sampling locations, infrastructure and
information relevant to their water treatment plants and distribution systems. Acknowledgement is
also extended to Mackay, Cairns (Qld), Sydney Water (NSW) and Water Corporation (WA) for
completing water treatment surveys, and finally Mr Allan Burton, of Queensland Health Scientific
Services, for his assistance in sample preparation.
3.7 References
ABS, 2005. Regional Population Growth 2004 – 05. Australian Bureau of Statistics Report,
catalogue number 3218.0, Canberra.
ABS, 2007. 4610.0 - Water Account, Australia, 2004-05
http://www.abs.gov.au/AUSSTATS/[email protected]/productsbyCatalogue/9F319397D7A98,
accessed 15 May 2007.
ANL, 2007. RESRAD Version 6.3 Computer Model.
http://web.ead.anl.gov/resrad/home2/index.cfm, accessed 15 May 2007.
ANZECC/ARMCANZ, 2000. Australian and New Zealand Guidelines for Fresh and Marine
Water Quality. National Water Quality Management Strategy Paper No. 4. Australian
and New Zealand Environmental and Conservation Council & Agricultural and Resource
Management Council of Australia and New Zealand. Australian Government Publishing
Service, Canberra.
ASTM, 1998. Standard Test method for Radon in Drinking Water, ASTM D 5072-98. American
Society for Testing and Materials.
63
AWA, 2006. Australian Water Information: Statistics.
http://www.awa.asn.au/Content/NavigationMenu2/AboutWaterandtheWat...lianWaterStat
istics06.pdf, accessed 09 January 2006.
BOM, 2007. Climate Data Online. http://www.bom.gov.au/climate/averages, accessed
10 November 2006.
Cooper, M.B., Ralph, B.J., Wilks, M.J., 1981. Natural Radioactivity in Bottled Mineral Water
available in Australia. Technical Report ARL/TR 036, Australian Radiation Laboratory,
Victoria.
Cooper, M.B., 2005. Naturally Occurring Radioactive Materials (NORM) in Australian Industries
– Review of Current Inventories and Future Generation. Report prepared for the
Radiation Health & Safety Advisory Council, ERS-006 Revision of September 2005.
EnviroRad Services Pty Ltd, Australia.
CRCWQT, 2006. Cooperative Research Centre for Water Quality and Treatment Consumers
Guide to Drinking Water. http://www.waterquality.crc.org.au/AboutDW_Consumers.htm,
accessed 30 July 2006.
Dickson, B.L., 1990. Radium in Groundwater (Chapter 4.2). The Environmental Behaviour of
Radium. IAEA Technical Report Series No 310, Volume 1. International Atomic Energy
Agency, Vienna.
EML, 1997. Environmental Measurement Laboratory Procedures Manual, HASL-300, 28th
Edition. US Department of Energy, New York.
EU, 1998. Drinking Water Directive. Council Directive 98/83/EC on the quality of water intended
for human consumption, European Commission.
EU, 1999. Nuclides 2000: An Electronic Chart of the Nuclides. Version 1.10. European
Communities, Germany.
64
Faillace, E.R., Cheng, J.J., Yu, C., 1994. RESRAD Benchmarking Against Six Radiation
Exposure Pathway Models. Report No. ANL/EAD/TM-24. Environmental Assessment
Division, Argonne National Laboratory, USA.
Focazio, M.J., Szabo, Z., Kraemer, T.F., Mullin, A.H., Barringer, T.H., DePaul, V.T., 2001.
Occurrence of selected radionuclides in groundwater used for drinking water in the
United States: a reconnaissance survey, 1998. US Geological Society Report 2000-4271,
USA.
Gaefvert, T., Ellmark, C., Holm, E., 2002. Removal of radionuclides at a waterworks. Journal of
Environmental Radioactivity 63, 105-115.
Health Canada, 2001. Environmental Radioactivity in Canada 1989-1996. Radiological
Monitoring Report 01-HECS-252. Health Canada, Ontario .
Hoffman, J., Leicht, R., Wingender, H.J., Worner, J., 2000. Radiological Impact due to Wastes
containing Radionuclides from Use and Treatment of Water. Report EUR 19255.
European Commission, Brussels.
IAEA, 2003. Extent of Environmental Contamination by Naturally Occurring Radioactive
Material (NORM) and Technological Options for Mitigation. Technical Report Series
No. 419. International Atomic Energy Agency, Vienna.
Jimenez, A., de la Montaria Rufo, M., 2002. Effect of water purification on its radioactive content.
Water Research 36, 1715-1724.
Katzlberger, C., Wallner, G., Irlweck, K., 2001. Determination of 210Pb, 210Bi, and 210Po in
natural drinking water, J Radioanal Nucl Chem 249, 191-196.
Kocher, D.C., 2001. Drinking water standards for radionuclides: the dilemma and a possible
resolution. Health Physics 80, 486-490.
Kourlouris, G., Dharmasiri, J., Akber, R.A., 1996. Radioactivity in Helidon Spa Water. Radiation
Protection in Australia 14(4), 87-90.
65
Martin, P., Akber, R.A., 1999. Radium isotopes as indicators of adsorption-desorption interactions
and barite formation in groundwater. Journal of Environmental Radioacivity 46, 271-286.
McLennan, W., Podger, A., 1999. National Nutrition Survey, Foods Eaten Australia 1995.
Australian Bureau of Statistics, Canberra
NHMRC, 2004. Australian Drinking water Guidelines 2004. National Water Quality Management
Strategy. National Health and Medical Research Council, Australian Government
Publishing Service, Canberra.
O’Brien, R.S., Cooper, M.B., 1998. Technologically Enhanced Naturally Occurring Radioactive
Material (NORM): Pathway Analysis and Radiological Impact. Applied Radiation and
Isotopes 49 (3), 227-239.
OQPC, 2004. Radiation Safety Regulation 1999, Reprint No. 2H, April 2005. Office of the
Queensland Parliamentary Counsel, Brisbane.
QDLGPSR, 2004. Population and Housing Fact Sheet – Toowoomba City. Queensland
Government, Department of Local Government, Planning, Sport and Recreation,
Brisbane.
QHSS, 2000. Trace Elements in Clinical Samples, Waters and Digests by ICPMS, Method. QIS
Document No. 18229R2, Brisbane.
RHSAC, 2005. Naturally Occurring Radioactive Material (NORM) in Australia: Issues for
Discussion. Radiation Health & Safety Advisory Council Report to the CEO, ARPANSA,
Australia.
Sill, C.W., Willis, C.P., 1965. Radiochemical Determination of Lead-210 in Mill Products and
Biological Materials. Analytical Cemistry 37(13), 1661-1671.
Sill, C.W., 1977. Determination of Thorium and Uranium Isotopes in Ores and Mill Tailings by
Alpha Spectrometry. Analytical Chemistry 49(4), 618-621.
66
UNSCEAR, 2000. Sources and effects of ionizing radiation. United Nations Scientific Committee
on the Effects of Atomic Radiation 2000 Report to the General Assembly, with scientific
annexes. United Nations, New York.
USEPA, 1993. Diffuse NORM Wastes - Waste Characterization and Preliminary Risk
Assessment. Prepared by S. Cohen and Associates, Inc., and Rogers & Associates
Engineering Corp., for the U.S. Environmental Protection Agency Office of Radiation
and Indoor Air. Environmental Protection Agency, Washington.
USEPA, 2000. National Primary Drinking Water Regulations; Radionuclides; Final Rule.
Environmental Protection Agency 40 CFR Parts 9, 141 and 142. Washington.
USEPA, 2005. A Regulator’s Guide to the Management of Radioactive Residuals from Drinking
Water Treatment Technologies. Environmental Protection Agency, Washington. .
WHO, 2006. Guidelines for drinking-water quality, 1st Addendum to 3
rd Edition. World Health
Organisation, Geneva.
Yu, C., Zielen, A.J., Cheng, J.J., LePoire, D.J., Gnanapragasam, E., Kamboj, S., Arnish, J., Wallo
III, A., Williams, W.A., Peterson, H., 2001. User’s Manual for RESRAD Version 6.
ANL/EAD-4. Argonne National Laboratory, USA.
67
CHAPTER 4
Mapping radioactivity in groundwater to identify elevated exposure in
remote and rural communities.
Ross Kleinschmidta,b
, Jeffrey Blacka, Riaz Akber
b
a Health Physics Unit, Queensland Health Forensic and Scientific Services, PO Box 594
Archerfield, Queensland. Australia. 4108.
b Physics, Faculty of Science and Information Technology, Queensland University of Technology.
GPO Box 2434, Brisbane, Queensland. Australia. 4000.
Journal:
Journal of Environmental Radioactivity 102, 235-243. 2011
68
Statement of Joint Authorship
The authors listed below have certified* that:
1. they meet the criteria for authorship in that they have participated in the conception,
execution, or interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible
author who accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or
publisher of journals or other publications, and (c) the head of the responsible academic unit,
and
5. they agree to the use of the publication in the student’s thesis and its publication on the
Australasian Digital Thesis database consistent with any limitations set by publisher
requirements.
In the case of this chapter:
Mapping radioactivity in groundwater to identify elevated exposure in remote and rural
communities.
Contributor Statement of contribution*
Ross Kleinschmidt
Signature
Date
Original concept and project design, supervision of research assistant, provided
laboratory facilities, conducted radioanalytical testing, interpreted data, wrote &
reviewed manuscript.
Jeffrey Black Project support, sampling logistics, radioanalytical testing, reviewed manuscript.
Riaz Akber Assisted in concept development, provided advice and reviewed manuscript
Principal Supervisor Confirmation
I have sighted email or other correspondence from all co-authors confirming their certifying
authorship.
AAPRO Riaz Akber
Name Signature Date
69
Abstract
A survey of radioactivity in groundwater (110 sites) was conducted as a precursor to providing a
baseline of radiation exposure in rural and remote communities in Queensland, Australia, that may
be impacted upon by exposure pathways associated with the supply, treatment, use and wastewater
treatment of the resource. Radionuclides in groundwater, including 238
U, 226
Ra, 222
Rn, 228
Ra, 224
Ra
and 40
K were measured and found to contain activity concentration levels of up to 0.71 BqL-1
, 0.96
BqL-1
, 108 BqL-1
, 2.8 BqL-1
, 0.11 BqL-1
and 0.19 BqL-1
respectively. Activity concentration results
were classified by aquifer lithology, showing correlation between increased radium isotope
concentration and basic volcanic host rock. The groundwater survey and mapping results were
further assessed using an investigation assessment tool to identify seven remote or rural
communities that may require additional radiation dose assessment beyond that attributed to
ingestion of potable water.
Keywords: ground water, radioactivity, waste, dose, rural, remote, Australia
70
4.1 Introduction
Radiation exposure derived from Australian groundwater supplies is generally attributed only to
ingestion of potable water. Radiological water quality guidelines have been developed regionally
(ANZECC/ARMCANZ, 2000; NHMRC, 2004) and globally (WHO, 2008; USEPA, 2000; EU,
1998; Kocher, 2001) for potable, livestock, watering irrigation and recreational uses. These
documents provide guidance in management and optimisation of water supply with a view to
ensure that the total committed ingestion dose is maintained at less than 1 mSv in a year. While
ingestion of water may contribute significantly to the dose of a critical group member, other less
obvious exposure pathways need to be considered in assessing the full impact of radioactive
constituents in groundwater supplies. Generation of Technologically Enhanced Naturally
Occurring Radioactive Materials (TENORM) from water resource exploitation is a topic both
locally (Cooper, 2005; Kleinschmidt and Akber, 2008; RHSAC, 2005) and internationally (IAEA,
2003). The USEPA have produced a guideline document detailing management practices for
radioactive residuals derived from drinking water technologies (USEPA, 2005), however, these
and other assessments (Kleinschmidt and Akber, 2008) tend to focus on sludges produced from
conventional water treatment plants typical of large urban systems, large scale water conditioning,
reverse osmosis, and private point-of-entry treatment systems.
It has been recognised that the water supply systems of small, remote communities may
differ from those of urban centres, quite often based on economical and environmental factors
(DNRM, 2005). In many cases these communities rely on groundwater for their water supply.
Often a sole, local resident is responsible for maintenance of water supply and sewerage
infrastructure including head-works, reticulation and wastewater treatment. If the person resides
and works in a community relying on groundwater containing elevated levels of NORM, then
exposure pathways other than ingestion of water may need to be considered. Comprehensive
information is not available on dose estimation for situations such as that described. Reference to
studies on individual sources of exposure however, exist. For example those associated with
radium scale in water supply distribution systems (Valentine and Stearns, 1994), hot water tanks
(DeVol and Woodruff, 2004), exposure from radium and radon in water supplies and spring waters
71
(Abdulrahman and Maghrawy, 2010; Koulouris et al., 1996), and water treatment plants
(Toussaint and Burkett, 1996). Kleinschmidt (2007) identified a number of potential exposure
pathways for individuals working and residing in small communities, recommending the need for
a detailed exposure assessment to include not only potable water dose contributions, but also those
associated with recreational, workplace and waste disposal activities. The purpose of this study to
provide a means of identifying those communities that may be at increased risk of exposure to
radioactivity associated with groundwater.
Screening surveys have previously been used, particularity for 222
Rn maps, to facilitate
the radiological characterisation of an area of interest. Mapping radioactivity levels in air, water
and the terrestrial environment may be used as a precursor to carrying out more detailed surveys
that serve to validate, or extend, existing data and to identify areas of potential public harm, or to
provide baseline data prior to the commencement of a new radiation practice (Synnott, 2005;
WHO, 2009). Knowing the groundwater radioactivity characteristics for the reference site, in
conjunction with the identified exposure pathways, allows for implementation of a simple risk
based assessment of the potential impact of elevated groundwater radioactivity levels established
during the mapping process.
4.2 Method
4.2.1 Survey and sampling design
A groundwater screening program was developed to provide initial data on the extent and
magnitude of radiological properties of groundwater supply and use in the state of Queensland,
Australia. The sampling was designed to include as many aquifer systems as possible, particularly
those serving a community for potable, recreational or livestock water use. Sampling regions were
chosen to cover the range of aquifer lithology descriptors as provided by the Queensland Water
Resources Commission (QWRC, 1987). As a large physical land area was to be covered
(approximately 1.7 million square kilometres serving a population of 4 million), a ‘mail-out’ water
sampling kit was developed (Figure 4.1). Sampling kits comprising of prepared polyethylene
sample bottles, detailed sampling instructions, based on standard sampling collection methods
72
(AS/NZS, 1998) and a questionnaire were assembled with packaging and return freight
instructions. These kits were then forwarded to a number of regional shire councils and selected
sampling agents. The questionnaire included pre-assigned sampling location descriptions and
laboratory codes, fields for entering data on the physical location, latitude and longitude, water
treatment processes, physical characteristics of the bore including its depth and yield, and the
population served.
4.2.2 Radioanalytical methods
Radon (222
Rn) analysis via liquid scintillation spectrometry, and radium (224
Ra, 226
Ra and 228
Ra) &
uranium (235
U and 238
U) isotope analysis by high resolution gamma spectrometry were considered
suitable for the screening program. Potassium 40 (40
K) in water was determined from total
potassium (natural abundance of 0.0117%; IUPAC, 1998) analysis using atomic absorption
spectrometry, or inductively coupled mass spectrometry as dictated by laboratory instrumentation
availability.
FIGURE 4.1: Groundwater sampling kit including: 1 x 500 mL
acid washed polyethylene bottle, 2 x 20 mL Teflon coated
polyethylene liquid scintillation vials, sampling instructions and
questionnaire, and reusable shipping container with prepaid
consignment note.
73
Radon, as 222
Rn concentration in water was determined using the direct counting method described
by Kleinschmidt and Akber (2008). The sampling instructions included detailed information on
minimisation of delays in submitting samples for analysis, and additionally the radioanalytical
laboratory assessed all samples for time limitation compliance. To further monitor sampling
effectiveness and reproducibility, duplicate samples were collected at each sampling location.
Low diffusion Teflon® coated liquid scintillation vials (supplied by Perkin Elmer) were used.
Sample aliquots of 10 mL were prepared in similar Teflon coated vials, by introducing the sample
water under 5 mL of Mineral Oil
(Perkin Elmer) scintillation cocktail. Samples were shaken to
mix, and then held for at least 4 hours before counting so that equilibrium between 222
Rn and its
decay progeny was attained. Analysis was performed using TriCarb 3170TR/SL, TriCarb 3180
TR/SL and QUANTULUS 1220 (Perkin Elmer Pty Ltd) alpha / beta discriminating liquid
scintillation analysers depending on instrument availability. All 222
Rn concentration results were
corrected for decay back to the date and time of sampling. A minimum detection level of
20 mBqL-1
was achieved for the method using a count time of 120 minutes, this value considered
as being adequate for a screening program.
Uranium, thorium and radium screening analysis was conducted using high resolution
gamma spectrometry after sample preparation via barium and iron hydroxide co-precipitation
based on the method described by Parsa et al. (2005). A 1000 mL sample of water was acidified to
pH ~2 with 9M H2SO4, and 133
Ba tracer, of nominal activity 0.5 BqL-1
, added to determine
chemical recovery. The barium carrier solution was added and the sample heated to 50o
C for 30
minutes while stirring to allow co-precipitation of radium isotopes with barium sulphate. The iron
carrier is added and the sample neutralised by adding dilute NaOH until a brown precipitate forms.
The precipitate was progressively separated by settling, decanting, centrifuging and rinsing into a
90 mm x 14 mm diameter polyethylene tube. The resulting precipitate ‘plug’ was dried in a block
heater at 80o
C and then sealed in the tube pending counting. Counting was performed using a low
background, well type high resolution gamma-ray spectrometer (EG&G 150-15 well germanium
detector and EG&G DSpec Plus® spectrometer). The gamma-ray spectrometer was calibrated
using reference pitchblende material known to be in equilibrium (238
U of activity 101 Bqg-1
, Sill
and Hindman, 1974) in a geometry replicating that of the sample. Approximately 15% of the
74
samples were counted within 48 hours of preparation for 224
Ra determination, with all prepared
samples then stored for a minimum of 20 days to allow 226
Ra and 228
Ra decay progeny to attain
secular equilibrium before counting. The mean chemical yield, as measured using the 133
Ba tracer,
was measured to be 80 ± 8%, however all result sets were corrected by the sample specific
chemical yield factor. Uranium and thorium chemical yield was considered to be 100% for the
purposes of this screening method (Chou and Moffatt, 2000). For a counting time of 20 hours and
a 1000 mL sample volume, a minimum detection level of 50 mBqL-1
for 224
Ra, 226
Ra and 228
Ra can
be achieved, which is adequate for the purposes of the mapping program. 238
U and 232
Th were
determined using respective, immediate decay progeny, and 133
Ba (as chemical yield monitor) via
direct measurement individual characteristic photopeaks.
4.2.3 Mapping
Groundwater activity concentration results for the radionuclides of interest were geographically
mapped according to location and magnitude of activity. A map indicating the major groundwater
aquifer systems of Queensland is shown in Figure 4.2 (and in Figure Supp 4.1). Small disjointed
aquifers associated with both surface systems within the Great Artesian Basin, and localised
fractured rock systems are not well represented and the assignment of aquifer lithology was based
on either interpretation of printed hydrology maps (QWRC, 1987), or the bore strata log where
available. In all cases where a result for radioactivity concentration was below the calculated
minimum detection level, a value of one half the MDL was used for plotting purposes. A set of
generic lithology types was used for mapping purposes (Table 4.1).
75
TABLE 4.1: Aquifer lithology key (QWRC, 1987).
Code Aquifer Lithology Examples
AI Acid to Intermediate Volcanics andesite, rhyolite, tuff
BI Basic Intrusives gabbro, serpentine
BV Basic Volcanics Basalt
Ca Carbonates limestone, dolomite
DL Complex Alternation of Different Lithologies -
MR Metamorphic Rocks schist, quartzite
SS Sedimentary Strata sandstone, shale, conglomerate
US Unconsolidated Sediments sand, gravel
4.3 Results and Discussion
4.3.1 Radioanalytical method validation and sampling quality
A determination of consistency in sampling method was made for 222
Rn gas sample collection.
Greater than 85% of duplicate sample results were within 20% of each other, while only 2%
exceeded 50% variation (Figure 4.3). For all cases where the variation was greater than 50%,
results were at, or approaching, the measurement system MDL. While the sampling quality
indicator used in this study may provide information on the sampler’s ability to collect samples in
a consistent manner, it does not automatically ensure that it is truly representative of the 222
Rn
concentration in the water.
76
N
BRISBANE Highfields
Eumundi
Pittsworth
Jericho
Christmas Creek
CAIRNS
Charters Towers
FIGURE 4.2: Predominant groundwater aquifer zones of Queensland, Australia (adapted from
QWRC, 1987)
Great Artesian Basin
Sedimentary Aquifer
Fractured Rock Aquifer
Limestone / Dolomite
77
The radiochemical method for measuring radium isotopes and uranium was validated by
measurement of three replicates of samples spiked over the expected useful range of activity
concentration (up to 5 BqL-1
). The spiked samples were prepared using the described method and
analysed using the same measurement system as used for the project. Variation between measured
results and actual 226
Ra activity added to the samples was in all cases less than 10%. Separate
validation for uranium and thorium recovery was not undertaken as it is considered that radium
isotopes would have the more significant radiological impact.
4.3.2 Sampling program
A total of 185 sampling kits were provided to targeted authorities and individuals that had agreed
to participate in the survey. Of the 185 kits sent out, a total of 110 were returned, a total recovery
of 59%. Completion of the questionnaire to a standard considered suitable for the purposes of the
project was 8%. As a consequence of the poor response in completing the questionnaire, a manual
review of bore records was undertaken to establish basic information including position
co-ordinates, aquifer lithology and bore depth. 222
Rn data for this study was supplemented by a
0 10 20 30 40 50 60 70 80 90 100
222Rn CONCENTRATION IN WATER (BqL-1)
-100
-80
-60
-40
-20
0
20
40
60
80
100% VARIATION IN
DUPLICATE SAMPLE
S
FIGURE 4.3: Percentage variation in duplicate 222
Rn samples plotted against activity
concentration magnitude.
78
data set of 47 results from the state of Queensland that were generated through an earlier Australia
wide radon in groundwater scoping program by Herczeg and Dighton (1998).
4.3.3 Radiological water quality and mapping
Water radioactivity analysis for 226
Ra, 222
Rn, 228
Ra and 40
K was conducted for a total of 110
groundwater bores, representing all aquifer lithology types as listed in Table 4.1. Analysis of 238
U,
232Th and
224Ra was conducted for a limited (~ 15%) sample set. A summary of results, including
statistical analysis, is given in Table 4.2, and Figure 4.4 shows the relative frequency of
radioactivity concentration in water for the primary radionuclide set. Results for 222
Rn are
consistent with those published for Queensland by Herczeg and Dighton (1998), and radium and
uranium results, in general, are higher than those provided by Long et al. (2008) for Australia.
Correlation between results for radium isotopes, and 226
Ra and 222
Rn, was assessed to establish if
surrogate analysis techniques could be applied for future mapping or investigation purposes. The
coefficient of determination (R2) for
226Ra to
228Ra,
228Ra to
224Ra and
226Ra to
222Rn results were
0.79, 0.64, and 0.47 respectively, the poor correlation for 226
Ra to 222
Rn suggesting that simple
222Rn in water measurement as a surrogate to
226Ra analysis, is not reliable as a means for
screening for radioactivity in groundwater. Radioactivity in groundwater maps for the
radionuclides 226
Ra, 222
Rn, 228
Ra and 40
K are shown in Figure 4.5. Measurement locations coincide
with populated areas relying on groundwater as a significant component of their water supply
regime.
TABLE 4.2: Summary of radioanalytical results for all water samples and aquifer lithology
types.
Activity Concentration (BqL-1
)
238U
226Ra
222Rn
228Ra
224Ra
40K
Minimum 0.04 0.01 0.02 0.01 0.01 0.06
Maximum 0.71 0.96 108 2.8 0.34 0.89
Median 0.08 0.01 5.4 0.02 0.11 0.19
Mean 0.15 0.07 11 0.14 0.12 0.27
Standard Deviation 0.18 0.15 17 0.40 0.09 0.20
79
Aquifer Lithology was used to group water activity concentration results (Figure 4.6).
The highest concentration of 226
Ra, 228
Ra and 40
K were observed in the basic volcanic aquifers,
however, median radium isotope concentration values were generally similar across all aquifer
types and less than 0.2 BqL-1
. It was observed that complex lithology changes over short distances
(south east Queensland region in proximity to the city of Toowoomba) provide for large variations
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1226Ra CONCENTRATION (BqL-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
RELA
TIVE FREQUENCY
0.0 0.2 0.4 0.6 0.8 1.0 1.2 2.8 3.0228Ra CONCENTRATION (BqL-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
RELA
TIVE FREQUENCY
0 10 20 30 40 50 60 70 80 90 100 110 120222Rn CONCENTRATION (BqL-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
RELA
TIVE FREQUENCY
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.040K CONCENTRATION (BqL-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
RELA
TIVE FREQUENCY
228Ra 226Ra
222Rn 40K
FIGURE 4.4: Radioactivity concentration in groundwater, relative distribution of
primary investigation radionuclides
80
136 138 140 142 144 146 148 150 152 154
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
136 138 140 142 144 146 148 150 152 154
New Legend< 10
10 - 30
30 - 50
50 - 70
70 - 90
90 - 110
Radon 222 (BqL-1)
136 138 140 142 144 146 148 150 152 154
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
New Legend< 100
100 - 300
300 - 500
500 - 700
700 - 900
900 - 1100
1100 - 2000
2000 - 3000
Radium 228 (mBqL-1)
136 138 140 142 144 146 148 150 152 154
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
136 138 140 142 144 146 148 150 152 154
New Legend< 100
100 - 300
300 - 500
500 - 700
700 - 900
900 - 1100
1100 - 2000
2000 - 3000
Radium 226 (mBqL-1)
136 138 140 142 144 146 148 150 152 154
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
-30
-28
-26
-24
-22
-20
-18
-16
-14
-12
-10
New Legend< 100
100 - 300
300 - 500
500 - 700
700 - 900
900 - 1100
1100 - 2000
2000 - 3000
K 40 (mBqL-1)
40K 228Ra
222Rn 226Ra
FIGURE 4.5: Radioactivity in groundwater maps for primary radionuclides.
81
in radionuclide concentration, and that the ratio between 226
Ra and 228
Ra activities supports the
case for the presence of multiple aquifer systems.
It is emphasized that the prediction of areas requiring further investigation in these
regions is difficult, and confirms the need for detailed, local lithology information and a higher
density sampling program during any assessment, preferably including the bore installation log.
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
226 Ra CONCENTRATION (BqL
-1)
AI AI/MR AV BV Ca DL SS US
AQUIFER LITHOLOGY
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
228 Ra CONCENTRATION (BqL
-1)
AI AI/MR AV BV Ca DL SS US
AQUIFER LITHOLOGY
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
40K CONCENTRATION (BqL
-1)
AI AI/MR AV BV Ca DL SS US
AQUIFER LITHOLOGY
-10.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
222 Rn CONCENTRATION (BqL
-1)
AI AI/MR AV BV Ca DL SS US
AQUIFER LITHOLOGY
222Rn 40K
226Ra 228Ra
FIGURE 4.6: Radioactivity in groundwater result distribution within main aquifer lithology types.
Maximum Third Quartile
Median
First Quartile Minimum
+ Outlying result
KEY
82
4.3.4 Reference study area
An area located approximately 350 km south west of Alice Springs in the Northern Territory,
Australia, was chosen as the reference area for this study (Figure 4.7). The water supply in this
area is known to contain radioactivity concentrations of 1 BqL-1
226
Ra, 0.7 BqL-1 228
Ra and up to
60 BqL-1 222
Rn (Kleinschmidt, 2007). The conditions in the area are typical of an arid
environment, representing many of the rural and remote communities targeted in this Queensland
study. Rainfall, temperature and tourist visitation rates are critical parameters that dictate water
resource consumption patterns (NTPW, 2005).
Details of water supply infrastructure are described in Kleinschmidt (2007), and also in
the Supplementary Material (Supp 4.2). Operational data provided in NTPW (2005) notes that
approximately 60% of the total potable water produced from the borefields reaches the head-works
LOCATION MAP
WASTE
SUPPLY
H MC IIr
Ir
Ir D D
Ir
Ir
IrSTORAGE TANK #2
237kL
STORAGE TANK #1
237kL
CHLORINATION
HOT WATER
TANK
PRODUCTION
BORES
WWTP #1
WWTP #2
WWTP #3
WWTP #4
TREE FARM
SPRAY
WWTP OVERFLOW TO
ENVIRO.
TANK SLUDGE TO ENVIRO.
H
MC
Ir
I
D
HYDRANT
MEDICAL CENTRE
IRRIGATION SYSTEM
INDUSTRIAL USE
DOMESTIC USE
PRODUCTION BORE
W
S
WATER SAMPLING LOCATION
SOIL/SEDIMENT SAMPLING LOCATION
W W
W
W
W
W
W W W
W
W
S
S
S
S
S
S
S
S
S
FIGURE 4.7: Location map of reference site and water supply / sewerage system schematic
(Kleinschmidt, 2007).
83
of the wastewater treatment plant. As the supply and reticulation system is closed to the
environment until this point, loss of water to evaporation can be considered as negligible. This
suggests that approximately 40% of water produced is lost to leakage and / or consumed to meet
irrigation demand within the community. Table 4.3 shows the potential exposure pathways
associated with elevated radioactivity concentration in water for the reference site.
4.3.5 Investigation trigger level
It was considered that a ‘trigger’ point, or Investigation Trigger Level (ITL), was required to
justify further investigation of any location where radioactivity was present in the groundwater
supply at a level where exposure in addition to that from ingestion may occur. For the reference
site, Kleinschmidt (2007) identified that approximately 80% of the dose associated with
exploitation of the ground water supply in a small, rural / remote community could be attributed to
ingestion of potable water. Acknowledging that each assessment must be considered on a case-by-
case basis due to local conditions, the ITL for further investigation was set at a value where the
ingestion component alone could contribute 0.4 mSvy-1
. It is expected that a 0.4 mSvy-1
ITL will
allow for meeting the NHMRC (2004) recommendations (i.e. a water supply should be further
investigated when the ingestion dose contribution lies between 0.5 mSvy-1
and 1 mSvy-1
), but
considers the real possibility of contribution from both known and unknown additional exposure
pathways. In consideration of the cumulative contribution of all radionuclides that may be present,
a concentration factor based method was developed to test against the ITL. The concentration
factor is derived using a dose constraint of 0.4 mSvy-1
for ingestion (80% of the 0.5 mSvy-1
lower
investigation level provided in NHMRC, 2004), where further investigation is recommended when
the concentration factor is greater than unity.
The activity concentration factor (AF), for all radionuclides of interest, is calculated using:
∑=i i
i
FLC
CA … … … … [1]
84
where: C is the activity concentration of the radionuclide of interest, and the limiting
concentration, LC is given by:
vD
ELC
Cing
DL
.= … … … … [2]
where: EDL is the derived effective dose limit (0.4mSv.y-1
), DCing is the ingestion dose
conversion factor for the radionuclide of interest in Sv.Bq-1
(ICRP 72, 1996), and v is the
volume of water consumed per year (assumed to be 730 L.y-1
as per NHMRC, 2004).
If the value of AF is greater than 1, the ITL has been exceeded and further investigation of
the radiological impact of groundwater exploitation is recommended.
Calculation of the ITL values for each bore using equation [1] and equation [2] yields 7
of the 110 locations tested where the ITL value exceeds unity. The results are given in Table 4.4,
also including the primary radionuclide concentration results for comparison purposes. The
majority of these locations are associated with either acid intrusive, or basic volcanic lithology. It
is noteworthy that 228
Ra is the predominant radioisotope present in water samples where the ITL
value exceeds unity, and suggests that 232
Th mineralisation (as the parent radionuclide to 228
Ra) is
of significant impact to Queensland groundwater radiological water quality. The locations where
the ITL exceeded unity are geographically shown on Figure 4.2.
85
TABLE 4.3: Summary of activity concentrations in water, scales, sludges and soils, and associated potential exposure pathways identified at the reference site
(Kleinschmidt, 2007)
Mean activity concentration (BqL-1) WATER
238U 226Ra 222Rn 210Po 228Ra 224Ra 40K
Exposure Pathways & Potential Hazards
Bore head 0.03 1.0 60 0.03 0.7 -
Tank outlet 0.02 0.8 35 0.06 0.6 -
Tank waste 0.05 1.1 - 0.26 0.8 -
Reticulation 0.03 0.8 50 0.16 0.6 -
WWTP (effluent) < 0.01 0.2 5 0.08 0.2 -
water ingestion - drinking, potential dose
water ingestion – involuntary when swimming
radon inhalation – shower / bath / kitchen
external exposure – immersion in swimming pool, proximity to bulk storage tanks / WWT ponds
Mean activity concentration (Bqkg-1) SCALE
238U 226Ra 210Pb 228Ra 224Ra 40K
Exposure Pathways & Potential Hazards
Bulk hot water < 100 1100 < 200 350 280 < 400
Shower head < 100 3500 450 1500 1000 < 400
Inhalation – dust, maintenance duties & waste disposal
Ingestion – removable contamination – dust & maintenance duties
External exposure – maintenance activities & waste disposal Mean activity concentration (Bqkg-1) SLUDGES
238U 226Ra 210Pb 228Ra 224Ra 40K
Exposure Pathways & Potential Hazards
Tank waste 780 2830 200 2010 1230 300
WWTP - biosolid < 300 1300 < 200 700 440 < 200
Inhalation – dust resuspension via land spreading & waste disposal
External exposure – maintenance activities, land spreading & waste disposal
Mean activity concentration (Bqkg-1) SOILS
238U 226Ra 210Pb 228Ra 224Ra 40K
Exposure Pathways & Potential Hazards
Tree farm – centre < 40 500 50 180 120 220
Tree farm – b’gnd < 20 13 20 24 13 130
Ingestion – uptake by plants / animals, transfer to humans
Inhalation – dust resuspension
External exposure – maintenance activities
85
86
TABLE 4.4: Trigger values and water radioactivity concentration data for locations where
further assessment is recommended.
Water Activity Concentration (BqL-1) Location Lithology Trigger
Value 238U 226Ra 222Rn 228Ra
Charters Towers -Balfes
Creek PTB
AI 1.00 - 0.38 ± 0.05 43 ± 4 0.41 ± 0.07
Charters Towers -
Homestead PTB
AI 1.07 0.11 0.43 ± 0.05 34 ± 4 0.51 ± 0.08
Eumundi - Golden Rain
Lane
AI 1.39 0.09 0.29 ± 0.05 68 ± 8 0.64 ± 0.07
Highfields – Reushie
Road
BV 4.48 - 0.96 ± 0.08 71 ± 6 2.8 ± 0.1
Pitsworth – 6km W
Brookstead
BV 1.65 - 0.06 ± 0.04 6 ± 1 1.26 ± 0.06
Christmas Creek
(Far Nth Queensland)
Ca 1.29 0.10 0.50 ± 0.05 110 ± 15 0.28 ± 0.09
Jericho SS 1.21 0.04 ± 0.08 0.39 ± 0.05 8 ± 1 0.77 ± 0.09
Reference Site SS 1.76 0.02 ± 0.01 1.0 ± 0.2 60 ± 14 0.7 ± 0.1
4.4 Conclusions
A limited survey of groundwater bores was conducted across Queensland, Australia, to establish
the extent and magnitude of naturally occurring radioactivity present. A radioanalytical screening
method for determination of uranium and radium isotopes was developed and validated for use in
the survey, in conjunction with 222
Rn in water analysis methods. It was confirmed that
groundwater derived from fractured rock aquifers had higher radium concentrations than
sedimentary systems and it was established that aquifer lithology is useful as an initial indicator
for presence of predominantly radium isotopes, whereas little correlation is observed between
226Ra and its progeny radionuclide,
222Rn.
87
The results were used to establish a map of radioactivity concentrations for naturally
occurring radioactive materials, with the view that these locations could be revisited to assess the
potential radiation exposure of communities not only associated with ingestion of potable waters,
but also for residues and waste products associated with the treatment, use and eventual discharge
or disposal practices. Further research is required to validate and characterise the contribution of
additional exposure pathways (other than ingestion of potable water) to the critical group, or
population, based on the outcomes of the mapping survey. It is expected that as more data
becomes available it will be possible to confirm derivation parameters of the ITL values used for
this project.
4.5 Acknowledgements
The authors wish to thank all sampling participants in the groundwater survey, the Northern
Territory Power Water Corporation for providing access to the reference site, Rob Ellis,
Queensland Water Resources Department, and Kathy Coles, Health Physics Unit, Queensland
Health Forensic and Scientific Services, for her assistance in completing sample analyses.
This work was partially funded by Queensland Health Forensic and Scientific Services,
Cabinet Research Fund Project RSS08-006.
4.6 References
Alabdulahman, A.I. and Maghrawy, H.B., 2010. Radon emanation from radium specific
adsorbents. Water Research 44, 177-184.
ANZECC/ARMCANZ, 2000. Australian and New Zealand Guidelines for Fresh and Marine
Water Quality. National Water Quality Management Strategy Paper No. 4. Australian
and New Zealand Environmental and Conservation Council & Agricultural and Resource
Management Council of Australia and New Zealand. Australian Government Publishing
Service. Canberra, Australia.
88
AS/NZS, 1998. Australian / New Zealand Standard, Water Quality – Sampling. Part 1: Guidance
on the design of sampling programs, sampling techniques and the preservation and
handling of samples. AS/NZS 5667.1-1998. Standards Australia, Homebush, Australia,
and Standards New Zealand, Wellington, New Zealand.
Chou, C.L. and Moffatt, J.D., 2000. A simple co-precipitation inductively coupled plasma mass
spectrometric method for the determination of uranium in seawater. Fresenius Journal of
Analytical Chemistry 368, 59-61.
Cooper, M.B., 2005. Naturally Occurring Radioactive Materials (NORM) in Australian Industries
– Review of Current Inventories and Future Generation. Report prepared for the
Radiation Health & Safety Advisory Council, ERS-006 Revision of September 2005.
EnviroRad Services Pty Ltd, Australia.
DeVol, T.A. and Woodruff, Jnr R.L., 2004. Uranium in hot water tanks: A source of TENORM.
Health Physics 87(6), 659-663.
DNRM (Department of Natural Resources and Mining)., 2005. Planning Guidelines for Water
Supply & Sewerage. Department of Natural Resources & Mines. State of Queensland,
Brisbane.
EU (European Union), 1998. Drinking Water Directive. Council Directive 98/83/EC on the quality
of water intended for human consumption. European Commission.
Herczeg, A.L. and Dighton, J.C., 1998. Radon-222 concentrations in potable groundwater in
Australia. Water 34, 37.
IAEA (International Atomic Energy Agency), 2003. Extent of Environmental Contamination by
Naturally Occurring Radioactive Material (NORM) and Technological Options for
Mitigation. Technical Report Series No. 419. International Atomic Energy Agency,
Vienna.
89
ICRP (International Commission on Radiological Protection)., 1996. Age dependent doses to
members of the public from intake of radionuclides. Part 5: Compilation of ingestion and
inhalation dose coefficients. ICRP Publication 72, Pergamon Press. Oxford, United
Kingdom.
IUPAC (International Union of Pure and Applied Chemistry)., 1998. Naturally occurring isotope
abundances: Commission on Atomic Weights and Isotopic Abundances report for the
IUPAC in Isotopic Compositions of Elements. Pure and Applied Chemistry 70, 217-
235.
Kleinschmidt, R., 2007. Radiological impact of groundwater use – Kings Canyon, Northern
Territory, Australia. Report 06PQ229, Northern Territory Power and Water Corporation.
Queensland Health Forensic and Scientific Services, Australia.
Kleinschmidt, R. and Akber, R., 2008. Naturally occurring radionuclides in materials derived
from urban water treatment plants in southeast Queensland, Australia. Journal of
Environmental Radioactivity 99, 607-620.
Kocher, D.C., 2001. Drinking water standards for radionuclides: the dilemma and a possible
resolution. Health Physics 80, 486-490.
Koulouris, G., Dharmasiri, J. and Akber, R.A., 1996. Radioactivity in Helidon Spa Water.
Radiation Protection in Australia 14(4), 87-90.
Long, L., Sdraulig, S., Hardege, L. and McLeish, J., 2008. The radioactive content of some
Australian drinking waters. Technical report 148. Australian Radiation Protection and
Nuclear Safety Agency, Australia.
NHMRC (National Health and Medical Research Council)., 2004. Australian Drinking water
Guidelines 6. National Water Quality Management Strategy. Australian Government
Publishing Service, Canberra, Australia.
NTPW (Northern Territory Power and Water), 2005. Potable Water Supply System and Sewage
Services System Asset management Plan 2005. Darwin, Australia.
90
Parsa, B., Obed, R.N., Nemeth, W.K. and Suozzo, G.P., 2005. Determination of gross alpha,
224Ra, 226Ra, and 228Ra activities in drinking water using a single sample preparation
procedure. Health Physics 89(6), 660-666.
QWRC (Queensland Water Resources Commission), 1987. Groundwater Resources of
Queensland. Queensland Water Resources Commission, Map 4. Government Printer,
Queensland.
RHSAC (Radiation Health Safety & Advisory Committee), 2005. Naturally Occurring Radioactive
Material (NORM) in Australia: Issues for Discussion. Radiation Health & Safety
Advisory Council Report to the CEO, ARPANSA, Australia.
Sill, C.W. and Hindman, F.D., 1974. Preparation and testing of standard soils containing known
quantities of radionuclides. Analytical Chemistry 46(1).
Synnott, H. and Fenton, D., 2005. An Evaluation of Radon mapping Techniques in Europe.
Radiological Protection Institute of Ireland, Ireland.
Toussaint, L.F., Burkett, G., 1996. Radon Levels in Groundwater treatment Plants in Western
Australia. Radiation Protection in Australia 14(3), 51-54.
USEPA (United States Environmental Protection Agency), 2000. National Primary Drinking
Water Regulations; Radionuclides; Final Rule. Environmental Protection Agency 40 CFR
Parts 9, 141 and 142: Washington, United States of America.
USEPA (United States Environmental Protection Agency), 2005. A regulators’ guide to the
Management of Radioactive Residuals from Drinking Water Treatment Technologies.
EPA 816-R-05-004. Washington, United States of America.
Valentine, R.L. and Stearns, S.W., 1994. Radon release from water distribution systems deposits.
Environmental Science Technology 28, 534-537.
WHO (World Health Organisation), 2008. Guidelines for drinking-water quality, Third edition
incorporating the first and second agenda. World Health Organisation, Geneva.
91
WHO (World Health Organisation), 2009. WHO handbook on indoor radon – A Public Health
perspective. Ed. Zeeb H. and Shannoun F. World Health Organisation, Geneva.
92
Chapter 4 - Supplementary Material
93
FIGURE Supp 4.1: Groundwater resources of Queensland, Australia (State of
Queensland, Department of Natural Resources and Water. 2006)
94
Supplementary Material Supp 4.2: Detailed Reference Site Description
An area located approximately 350 km south west of Alice Springs in the Northern Territory,
Australia, was chosen as the reference area for this study (Figure Supp 4.2). The water supply in
this area is known to contain radioactivity concentrations of 1 BqL-1
226
Ra, 0.7 BqL-1 228
Ra and up
to 60 BqL-1 222
Rn (Kleinschmidt, 2007). The conditions in the area are typical of an arid
environment, representing many of the rural and remote communities targeted in this Queensland
study. Rainfall, temperature and tourist visitation rates are critical parameters that dictate water
resource consumption patterns (NTPW, 2005).
Details of water supply infrastructure are described in Kleinschmidt (2007), and are
comprised of water supply and treatment, reticulation and wastewater treatment systems
(Figure Supp 4.2). The water supply is drawn from a bore field 1.5 km west of the community.
The production bores, reaching depths of 200m, are located in the Pacoota sandstone formation of
the local predominant Amadeus geological formation. The aquifer is considered to contain a large
volume of stored water with little evidence of local or frequent recharge. The groundwater quality
has been described in a report produced by the Northern Territory Power and Water authority
(NTPW, 2005) and salinity of the stored water appears to increase with depth (McDonald et al.,
1986). Two fibreglass water storage tanks, each with a capacity of 0.24 ML, are located on the
scarp to the west of the community and their location allows gravity feed of water to the
reticulation system. Groundwater from the bore field is chemically disinfected, and then aerated
by utilisation of a top-filling tank system to maximise oxidation of iron and extend settling time.
The second tank is filled via the first to further enhance the treatment process. Sediment and
sludges generated during treatment can be purged from the bottom of the storage tanks. Purged
sludge is discharged to the environment in proximity to, but outside of the fenced storage tank
compound. Average daily water demand has been calculated at 0.35 ML per day, with a peak
demand of 0.63 ML per day (NTPW, 2005).
The reticulation system distributes water to domestic and commercial users, the
community power generation station, and a bulk ‘hot-water’ supply. The system is routinely
95
purged to minimise the impact of iron fouling. This is achieved by discharging of water to the
environment via fire hydrants at various locations across the community.
The wastewater system consists of a gravity fed collection system with a pump station
transferring collected sewage to the wastewater treatment plant. Wastewater is fed into a series of
four concrete lined ponds allowing for settling, polishing and evaporation of effluent. Water
balance is maintained in the ponds by drawing effluent from the final pond for irrigation of a
planted tree lot and additional open spray irrigation area. Overflow channels are provided between
the ponds, with the discharge being open to the environment within the fenced wastewater
treatment plant compound. Biosolid sludges are infrequently cleared from the ponds as
operational needs dictate, disposal being by air-drying and subsequent localised land spreading.
Operational data provided in NTPW (2005) mentions that approximately 60% of the total potable
water produced from the borefields reaches the head-works of the wastewater treatment plant. As
the supply and reticulation system is closed to the environment until this point, loss of water to
evaporation can be considered as negligible. This suggests that approximately 40% of water
produced is lost to leakage and / or consumed to meet irrigation demand within the community.
References
Kleinschmidt, R., 2007. Radiological impact of groundwater use – Kings Canyon, Northern
Territory, Australia. Report 06PQ229, Northern Territory Power and Water Corporation.
Queensland Health Forensic and Scientific Services, Australia.
McDonald, P.S., Stevens, B.G., Ritchie, T. and Bagas, L., 1986. Kings Canyon Regional
Groundwater Investigation 1985. Report 23/1986. Power and Water Authority Water
Directorate. Darwin, Australia.
NTPW (Northern Territory Power and Water), 2005. Potable Water Supply System and Sewage
Services System Asset management Plan 2005. Darwin, Australia.
96
LOCATION
MAP
WASTE
SUPPLY
H MC IIr
Ir
Ir D D
Ir
Ir
IrSTORAGE TANK #2
237kL
STORAGE TANK #1
237kL
CHLORINATION
HOT WATER
TANK
PRODUCTION
BORES
WWTP #1
WWTP #2
WWTP #3
WWTP #4
TREE FARM
SPRAY
WWTP OVERFLOW TO
ENVIRO.
TANK SLUDGE TO ENVIRO.
H
MC
Ir
I
D
HYDRANT
MEDICAL CENTRE
IRRIGATION SYSTEM
INDUSTRIAL USE
DOMESTIC USE
PRODUCTION BORE
W
S
WATER SAMPLING LOCATION
SOIL/SEDIMENT SAMPLING LOCATION
W W
W
W
W
W
W W W
W
W
S
S
S
S
S
S
S
S
S
FIGURE Supp 4.2: Location maps of reference site and water supply /
sewerage system schematic (Kleinschmidt, 2007).
97
CHAPTER 5
Uptake and depuration of 131
I by the macroalgae Catenella nipae - potential
use as an environmental monitor for radiopharmaceutical waste.
Ross Kleinschmidta,b
a Health Physics Unit, Queensland Health Forensic and Scientific Services, PO Box 594
Archerfield, Queensland. Australia. 4108.
b School of Physical and Chemical Sciences, Queensland University of Technology. GPO Box
2434, Brisbane, Queensland. Australia. 4000.
Journal:
Marine Pollution Bulletin 58, 1539-1543. 2009
98
Statement of Joint Authorship
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1. they meet the criteria for authorship in that they have participated in the conception,
execution, or interpretation, of at least that part of the publication in their field of expertise;
2. they take public responsibility for their part of the publication, except for the responsible
author who accepts overall responsibility for the publication;
3. there are no other authors of the publication according to these criteria;
4. potential conflicts of interest have been disclosed to (a) granting bodies, (b) the editor or
publisher of journals or other publications, and (c) the head of the responsible academic unit,
and
5. they agree to the use of the publication in the student’s thesis and its publication on the
Australasian Digital Thesis database consistent with any limitations set by publisher
requirements.
In the case of this chapter:
Uptake and depuration of 131
I by the macroalgae Catenella nipae - potential use as an
environmental monitor for radiopharmaceutical waste.
Contributor Statement of contribution*
Ross Kleinschmidt
Signature
Date
Original concept, conducted field work, provided laboratory facilities, conducted
radioanalytical testing, interpreted data, developed and utilised models, wrote &
reviewed manuscript.
Principal Supervisor Confirmation
I have sighted email or other correspondence from all co-authors confirming their certifying
authorship.
AAPRO Riaz Akber
Name Signature Date
99
Abstract
A study was initiated to establish the suitability of the macroalgae Catenella nipae as an
environmental surveillance monitor for radiopharmaceutical waste discharges to aquatic
environments. A series of experiments were conducted to establish the radioactive iodine (131
I)
concentration factor, and uptake & depuration characteristics of C. nipae. The steady state
concentration factor was estimated to be 630 ± 80 mLg-1
, with an uptake half-time of 160 ± 20
minutes. Elimination of 131
I was found to follow a two phase model, the first having a rapid
elimination rate with a half-time of less than one minute, followed by the second phase with a half-
time of 3.2 days. Greater than 96% of the 131
I activity was retained by the macroalgae within the
second compartment. Application of the Michaelis-Menton model allowed calculation of an
estimate for activity concentration of 131
I in environmental waters from deployed C. nipae
sampling devices in the Brisbane River estuary, Australia. Modelled data showed good correlation
with measured 131
I activity concentrations in water under varying environmental conditions. The
results suggest that C. nipae may be used as an environmental radioactive waste monitoring tool.
Keywords: Australia, radioactivity, iodine 131, macroalgae, monitoring, recycled water
100
5.1 Introduction
Radiopharmaceuticals discharged to domestic sewers, by way of excretion from patients
undergoing both diagnostic and therapy procedures, may become concentrated in wastewater
treatment plant (WWTP) waste streams. The radiopharmaceuticals are administered on either an
inpatient or outpatient basis, therefore providing a diffuse source load to the domestic wastewater
system. While local radiation control regulations prescribe allowable disposal concentrations to
the sewer (OQPC, 2004) for controlling inpatient discharges, outpatient discharge is generally not
controlled. The presence, and in some cases the impact, of these radioactive waste discharges has
been documented internationally (Ault, 1989; Barquero, 2008a, 2008b; EU, 1995; Fenner and
Martin, 1997; Ipek et al., 2004; Larsen et al., 1995, 2001; Martin and Fenner, 1997; Miller et al.,
1996; Sundell-Bergman et al., 2008; Titley et al., 2000), however, a limited number of studies
have been undertaken and published in Australia.
A review of the available literature indicates considerable variation in published
radionuclide partitioning values within WWTPs (Ham et al., 2003), and the fate of waste streams
(i.e. liquid effluent & biosolids) that may contain reconcentrated radioactive wastes. At a local
level, the assessment of the impact of reconcentrated radionuclides has become more prevalent
with the development of major infrastructure programs to establish wastewater recycling systems
for the production of high quality, potable water. The advanced water treatment plant (AWTP)
associated with this scheme in Brisbane, Australia, uses secondary and tertiary treated sewage
effluent as feed water to a series of microfiltration, reverse osmosis and oxidation processes prior
to release for indirect potable reuse. While the impact of any radiopharmaceutical wastes on the
indirect potable supply will be minimal due to the designed multi-barrier system, the reverse
osmosis concentrate (ROC) waste stream is discharged to local rivers and estuaries via outfalls and
submarine diffusers. Due to the presence of radiopharmaceuticals in the feed water, 131
I
concentrations of greater than 100 BqL-1
are not uncommon in the ROC waste stream
(Kleinschmidt, 2008). The measurement of radioactive wastes in the environment is required to
enable assessment and long term monitoring of the radiological impact of the ROC discharge to
the receiving estuary.
101
Bioaccumulators such as macroalgae and crustaceans have been documented as being
effective in monitoring for the presence of contaminants that would otherwise be difficult to
quantify (Costanzo, 2001, 2005; Evans and Hammand, 1995; Runcie et al., 2004; Solimabi and
Das, 1977; Sombrito et al., 1982; Vives i Batlle et al., 2005; Wilson et al., 2005). The macroalgae
Catenella nipae, already recognised for its use in monitoring stable isotope pollutants (Costanzo,
2001, 2005) and as a estuarine bioindicator (Melville and Pulkownik, 2006), is investigated for
suitability as a sentinel for measurement of radiopharmaceutical wastes, specifically 131
I, in the
aquatic environment. If the uptake and depuration characteristics of the macroalgae Catenella
nipae, already recognised for its use in monitoring stable isotope pollutants (Costanzo, 2001,
2005) and an estuarine bioindicator (Melville and Pulkownik, 2006), allow for reliable modelling,
then the macroalgae can be implemented for use as a sentinel for measurement of
radiopharmaceutical wastes in the aquatic environment.
5.2 Methods
Uptake and elimination studies were conducted using native C. nipae collected from mangrove
pneumatophores (Figure 5.1) along the foreshores of Moreton Bay in Queensland, Australia
(270S 28.543’, 153
0E 11.506’). The harvested C.nipae was transferred to a clean plastic container
holding 5 L of seawater and stored at a temperature of approximately 100C during shipping to the
laboratory. A further 20 L of seawater was collected from the same location to be used during the
uptake and depuration experiments, and was stored at 100C in a dark environment prior to use.
A solution of radiopharmaceutical-purity sodium iodide (131
I, half-life 8.04 days) mixed
with fresh seawater was used as the tracer for the uptake and depuration experiments. Five 10 g
portions of C. nipae were rinsed in seawater, weighed (wet) and transferred to separate glass tanks
holding 2000 mL of fresh seawater each. The tanks were exposed to normal laboratory lighting,
and to the controlled laboratory temperature of 22 ± 20C for the extent of the trials. Varying
concentrations of 131
I were introduced to three tanks (Tank A - 9.44 kBqg-1
, Tank B - 4.85 kBqg-1
and Tank C - 0.76 kBqg-1
respectively), with a fourth tank (Tank D) established as a duplicate to
102
FIGURE 5.1: Catenella nipae: a) attached to a mangrove pneumatophore, and b) as an
individual plant.
Tank A. A fifth tank, Tank E, was used as a control (9.32 BqmL-1) where no C. nipae was added
to the spiked seawater, to monitor iodine losses via pathways other than uptake or depuration.
Volatilisation of iodine to the atmosphere has been reported as being less than 0.1% under the test
conditions used (Evans et al. 1993), and therefore can be considered negligible compared to the
counting uncertainty. Activity concentration and counting times were selected to ensure that the
counting uncertainty was maintained at less than 2%, and yet maintain an activity working range
that could be encountered under environmental surveillance conditions. Uptake rate was derived
from measurements of a 10 g aliquot of water from each tank at selected time intervals and
counting on the described radiation measurement system. The aliquot was immediately returned
to the tank on the completion of counting. Measurement of the change
103
in water activity concentration, as opposed to direct measurement of C. nipae activity, was
adopted to allow for the rapid measurement of uptake and depuration in the initial stages of each
experiment as the algae did not require removal from the tank. Measurement aliquots were
immediately returned to the tank on the completion of counting.
The 131
I depuration, or elimination, rate was determined by placing C. nipae previously
immersed in Tank A and Tank D into 2 x 1000 mL glass tank respectively with fresh seawater
containing no radioactive tracer. The depuration rate was derived from measurements of a 10 g
aliquot of water from each tank at selected time intervals and counting on the radiation
measurement system. The aliquot was immediately returned to the tank on the completion of
counting. Counting times were selected to ensure that the counting uncertainty was maintained at
less than 5%.
Radioactivity measurement for uptake and elimination trials was performed using a
75mm NaI(Tl) scintillation well detector (Bicron Model 3MW3/3, 30 mm dia. x 50 mm deep blind
well) in a 100 mm thick lead environmental shield, connected to a multichannel analyser (EG&G
µNOMAD) with computer analysis software (EG&G ScintiVision). Water aliquots of 10 mL were
collected and counted in standard 20 mL polyethylene liquid scintillation vials, using a region of
interest centred on the predominant 364 keV 131
I photopeak. Energy calibration of the system was
conducted using a set of multi-nuclide reference sources (Amersham Gamma Reference Sources,
Model QCR.11). Measurement count times were chosen to meet the desired sensitivity
requirements of each experiment.
Field application of the method for surveillance monitoring was tested under two
scenarios. A sampling system was developed, based on that used by Costanza et al., (2001)
(Figure 5.2). In the first experiment three units were deployed in proximity to a WWTP effluent
outfall, near the mouth of the Brisbane River. The samplers, each containing approx. 50 g of C.
nipae, were submerged for a period of 6 hours. Two litre water samples were collected at the
initiation of sampling, after 3 hours, and on extraction of the samplers after 6 hours. The second
experiment was conducted by deploying 3 sampling units in the open effluent channel leading
from the wastewater treatment plant to the estuary discharge outfall. In this case the samplers
104
were deployed for varying lengths of time, periods being 100 min, 220 min and 280 min. Effluent
samples were collected at times representing half time periods, i.e. at 50 min, 110 min and 140
min.
Measurement of radioactivity in the C. nipae from the sampling devices, and
environmental waters & effluent was conducted using high resolution quantitative gamma
spectrometry (EG&G GAMMA-X detector, 20% relative efficiency) and computer analysis
software (EG&G GammaVision). System calibration for energy and efficiency was conducted
POLYSTYRENE
FLOAT
ANCHOR
VENTED HDPE
CONTAINER
HOLDING ~ 50 g
ALGAE
FIGURE 5.2: C. nipae sampling device used for
estimating 131
I water concentration in an estuary.
105
using a multinuclide reference source (Eckert & Ziegler Isotope Products 7503-7500 ML + 241
Am
+ 210
Pb), traceable to NIST, for waters, and a uranium reference standard (IAEA RGU-1 material)
for C. nipae. Environmental and effluent water samples were counted directly in 2000 mL
Marinelli beakers without pretreatment, for a live counting time of at least 250000 seconds.
C. nipae samples were weighed (wet weight) and compressed into a standard 100 mL jar geometry
prior to counting, with a minimum live count time of 10000 seconds. All measurements were
corrected for decay from time of exposure to completion of counting.
5.3 Results and Discussion
5.3.1 Uptake
Water activity concentrations measurements were initially taken at short intervals ranging from 1
minute to 10 minutes over the first 60 minutes of the experiment, with longer periods between
measurements as accumulation saturation was observed. Water activity concentration values were
converted to 131
I specific activity in C. nipae, corrected for mass and radioactive decay. The
specific activity results, in Bqg-1
, were plotted against exposure time (Figure 5.3). All sets of
uptake results gave a good statistical fit, with correlation coefficients for measured and modelled
data ranging from 0.983 to 0.998, to the Michaelis-Menton uptake model (Lopez et al., 2000):
at = Asat.t/(Km + t) [1]
where at is the activity concentration in Bqg-1
at a given time, Asat is the saturation activity
concentration, Km is the Michaelis-Menton curvature constant, and t is the time of exposure via
immersion. A correlation co-efficient of 0.988 was observed for Tank A and Tank D (duplicate)
results. Table 5.1 shows that observed values of 160 ± 20 minutes for the curvature constant, Km,
indicate that the uptake rate was similar over the range of initial water activity concentration
values used. The concentration factor was calculated for the
106
saturation activity concentrations using the formula:
CF = Asat /Aw [2]
where CF is the concentration factor with units of Lkg-1
, Asat is the C. nipae specific activity in
Bqg-1
, and Aw is the water activity concentration in BqmL-1
. Uptake and concentration factor
results are given in Table 5.1. A mean concentration factor of 630 ± 80 mLg-1
was determined
from all data sets. This figure is less than the published concentration factor of 10000 mLg-1
as
provided by IAEA (2004) for macrophytes, but within the range of published data for a number of
macroalgae species, ranging from 150 mLg-1
for Caulerpa racemosa (Sombrito et al., 1982), to
greater than 9400 mLg-1
for Chondrus crispus (Wilson et al., 2003).
TABLE 5.1: Uptake experiment results (uncertainty values are quoted as 2σσσσ (95%)).
Tank Description Initial solution
activity
(Bq.ml-1)
Saturation
Activity
(Bq.g-1)
Km Correlation
Co-efficient
CF
A ~ 10 g C. nipae 9.4 ± 0.3 760 ± 50 163 0.997 568
B ~ 10 g C. nipae 4.9 ± 0.1 380 ± 20 146 0.984 613
C ~ 10 g C. nipae 0.76 ± 0.04 63 ± 8 159 0.983 718
D Duplicate - Tank A 9.5 ± 0.3 730 ± 40 155 0.998 601
E Control 9.3 ± 0.3 < 1 - - -
- Mean results - - 160 ± 20 - 630 ± 80
107
5.3.2 Depuration
As for the uptake study, water activity concentrations measurements were taken initially at short
intervals ranging from 1 minute to 5 minutes over the first 10 minutes of the experiment, with
longer periods between measurements as the experiment progressed. Water activity concentration
values were converted to 131
I specific activity in C. nipae, and corrected for mass and radioactive
decay. The specific activity results, in Bqg-1
, were plotted against immersion time (Figure 5.4).
Both sets (Tank A and Tank D) of depuration results gave a good statistical fit to a biphasic
exponential loss model:
at = A1.e-k1.t
+ A2.e-k2.t
[3]
where at is the activity concentration in Bqg-1
at a given time, A1 and A2 are the activity distribution
concentrations for each of the two compartments, k1 and k2 are the respective excretion constants
(min-1
), and t is the immersion time in minutes. A correlation co-efficient of 0.951 was observed
for Tank A and Tank D (duplicate) results (Table 5.2). Analysis of A1 and A2 values indicates that
greater than 96% of the 131
I is retained in C. nipae after a fast initial depuration phase with a half
time estimated to be less than half a minute. The longer, second phase depuration half time is
approximately 3.2 days.
These results suggest that C. nipae would be suitable for use as a bioaccumulator based
sentinel monitoring system for radioiodine in estuarine waters due to the fast uptake rate and high
iodine retention characteristics.
TABLE 5.2: Depuration experiment results (uncertainty values are quoted as 2σσσσ (95%)).
Tank Description A1
(Bq.g-1)
k1 A2
Bq.g-1
k2
A ~ 10 g C. nipae 2.2E+01 1.7E+00 6.3E+02 7.4E-05
D Duplicate - Tank A 3.0E+01 1.3E+00 7.1E+02 6.9E-05
- Mean results (2.6 ± 0.8)E+01 (1.5 ± 0.5)E+00 (6.7 ± 0.8)E+02 (7.2 ± 0.4)E-05
108
FIGURE 5.4: 131
I elimination from C.nipae showing normalised, mean (Tank A and
Tank D) experimental results (solid symbols) and modelled data (broken line).
FIGURE 5.3: 131
I uptake by C.nipae showing experimental results (solid symbols) and
modelled data (open symbols) for three different water concentrations (uncertainty is
calculated at 2σσσσ (95%)).
109
5.3.3 Environmental monitors
For the first experiment, the wet weight 131
I activity concentration in the algae retrieved from the
deployed sampling devices in the river ranged from 0.28 ± 0.03 Bqg-1
to 0.37 ± 0.04 Bqg-1
after
approximately 6 hours immersion in tidal waters (Table 5.3). The average water activity, aw, over
an elapsed time, te, can be estimated using:
aw = at.(Km+te)/te /CF.1000 [4]
being derived from formula [1], where at is the wet weight activity concentration of the algae in
Bqg-1
, Km is the mean curvature constant of 160 (Table 5.1), te is the average immersion time of
363 minutes, CF is the concentration factor, with units of mLg-1
, as determined using formula [2],
and the factor of 1000 is used to convert the result to units of BqL-1
. Using this data, the mean
water activity concentration was calculated to be 0.7 ± 0.2 BqL-1
. Direct water 131
I water activity
concentration, as determined by quantitative gamma spectrometry, varied between 0.5 ± 0.1 BqL-1
and 1.1 ± 0.2 BqL-1
, with a mean value of 0.8 ± 0.6 BqL-1
. Variations in the activity concentration
can be attributed to the tidal nature of the sampling location, with water samples being taken on
the flood, peak and ebb tides.
For the second experiment, the wet weight 131
I activity concentrations in the algae
retrieved from the deployed sampling devices in the effluent channel were 2.47 ± 0.18 Bqg-1
,
6.70 ± 0.50 Bqg-1
and 6.30 ± 0.40 Bqg-1
after exposure times of 100 min, 220 min and 280 min
respectively (Table 5.4). The water activity, aw, was determined for each time period as for
experiment 1, using formula [4]. The effluent activity concentrations were calculated to be
10.2 ± 1.5 BqL-1
, 18.4 ± 2.2 BqL-1
and 15.7 ± 1.9 BqL-1
. Direct effluent 131
I activity
concentrations, as determined by quantitative gamma spectrometry, were 11.1 ± 0.8 BqL-1
,
16 ± 1 BqL-1
and 17 ± 1 BqL-1
for elapsed time periods of 50 min, 110 min and 140 mins
respectively.
Agreement between the modelled water and effluent 131
I concentrations and measured
activity concentration confirms that the monitoring method provides representative results under
110
the measurement conditions stated. Depuration was not considered to have a significant impact on
the monitor results under the deployment conditions.
TABLE 5.3: Experiment 1 - Environmental monitoring results for estimating 131
I
concentration in estuary water using C. nipae sampling devices (uncertainty values are 2σσσσ
(95%)).
Description Deployment
Time
Elapsed
Time
(min)
C. nipae
activity
(Bqg-1)
Modelled
water activity
(BqL-1)
Water
activity
(BqL-1)
Monitor 1 08:35 - 14:30 355 0.28 ± 0.03 0.64 ± 0.07 -
Monitor 2 08:40 - 14:45 365 0.30 ± 0.03 0.68 ± 0.07 -
Monitor 3 08:50 – 15:00 370 0.37 ± 0.04 0.84 ± 0.09 -
Water sample 11 08:15 - - - 0.7 ± 0.1
Water sample 22 12:05 - - - 1.1 ± 0.2
Water sample 33 14:25 - - - 0.5 ± 0.1
Mean - 363 - 0.7 ± 0.2 0.8 ± 0.6
NOTES:
1 flood tide; 2 high tide; 3 ebb tide
TABLE 5.4: Experiment 2 - Effluent monitoring results for estimating 131
I concentration
using C. nipae sampling devices (uncertainty values are 2σσσσ (95%)).
Description Deployment
Time
Elapsed
Time
(min)
C. nipae
activity
(Bqg-1)
Modelled
effluent activity
(BqL-1)
Effluent
activity
(BqL-1)
Monitor 1 09:05 - 10:45 100 2.47 ± 0.18 10.2 ± 1.5 -
Monitor 2 09:05 - 12:45 220 6.70 ± 0.50 18.4 ± 2.2 -
Monitor 3 09:05 – 14:25 280 6.30 ± 0.40 15.7 ± 1.9 -
Effluent sample 1 09:55 50 - - 11.1 ± 0.8
Effluent sample 2 10:55 110 - - 16 ± 1
Effluent sample 3 11:25 140 - - 17 ± 1
111
5.4 Conclusions
A series of radioactive iodine (131
I) uptake and depuration experiments were conducted using the
macroalgae C. nipae. The experiments were designed to establish 131
I uptake, concentration factor
and depuration characteristics of C. nipae, and establish if the macroalgae could be utilised as a
means of monitoring iodine based radioactive waste in an aquatic environment. The results
presented indicate that the Michaelis-Menton model adequately describes uptake of 131
I by
C. nipae, and that the uptake rate, as represented by the curvature constant, applies over the range
of 131
I water activity concentrations used in this study. The iodine concentration factor was
calculated to be 630 mLg-1
for C. nipae. This value falls within the wide range of published values
for iodine concentration in macrophytes, and more specifically macroalgae. Depuration results
were characterised by a biphasic model with a fast initial elimination component with a half time
of less than one minute, followed by a longer phase with a 3.2 day half-time. Greater than 96% of
the 131
I was retained after the initial phase. Uptake and depuration results were observed to be
reproducible under laboratory conditions.
Suitability for environmental monitoring applications was assessed by deploying C. nipae
based sampling devices in the Brisbane River estuary, Australia. The sampling devices were
submerged and anchored in aquatic environments known to contain iodine based
radiopharmaceutical wastes. Results from measurement of the 131
I activity concentration in the
macroalgae after an immersion, and application of the Michaelis-Menton model using parameters
determined in this study, compared favourably with direct water and effluent activity
concentration measurements with the advantages of shorter radioanalytical counting periods and
temporal averaging over the exposure.
It is acknowledged that physiological (e.g. reproduction stages) and environmental
parameters may affect C. nipae uptake & depuration characteristics (Ngan and Price, 1980; Hirano
et al., 1983), and therefore concentration factors as determined in this study. The model will be
applied to historical C. nipae activity datasets to estimate 131
I activity in water, and establish
baseline environmental data for comparison with future radioactivity concentrations in the estuary.
112
5.5 References
Ault, M.R., 1989. Gamma emitting isotopes of medical origin detected in sanitary waste samples.
Radiation Protection Management 6, 48-52.
Barquero, R., Basurto, F., Nunez, C. and Esteban, R., 2008. Liquid discharges from patients
undergoing I-131 treatments. Journal of Environmental Radioactivity 99(10), 1530-1534.
Barquero, R., Agulla, M.M. and Ruiz, A., 2008. Liquid discharges from the use of radionuclides in
medicine. Journal of Environmental Radioactivity 99(10), 1535-1538.
Costanzo, S.D., O’Donohue, M.J., Dennison, W.C., Loneragan, N.R. and Thomas, M., 2001. A
new approach for detecting and mapping sewage impacts. Marine Pollution Bulletin 42,
149-156.
Costanzo, S.D., Udy, J., Longstaff, B. and Jones, A., 2005. Using nitrogen stable isotope ratios
(δ15N) of macroalgae to determine the effectiveness of sewage upgrades: changes in the
extent of sewage plumes over four years in Moreton Bay, Australia. Marine Pollution
Bulletin 51, 212-217.
EU, 1995. Methodology for assessing the radiological consequences of routine releases of
radionuclides to the environment. European Commission Report No. EUR 15760.
European Commission, Luxembourg.
Evans, G.J., Mirbod, S.M. and Jervis, R.E., 1993. The volatilisation of iodine species over dilute
iodide solutions. The Canadian Journal of Chemical Engineering 71, 761-765.
Fenner, F.D. and Martin, J.E., 1997. Behaviour of Na131
I and meta(131
I) Iodobenzylguanidine
(MIBG) in municipal sewerage. Health Physics 73, 333-339.
113
Ham, G.J., Shaw, S., Crockett, G.M. and Wilkins, B.T., 2003. Partitioning of radionuclides with
sewer sludge and transfer along terrestrial food chain pathways from sludge-amended
land – A review of data. National Radiation Protection Board Report NRPB-W32.
Hirano, S., Matsuba, M. and Koyanagi, T., 1983. Influences of stable iodine upon the
concentration of radioactive iodine by marine organisms. Radioisotopes 32, 353-358.
Ipek, U., Arslan, E.I., Aslan, S., Dogru, M. and Baykara, O., 2004. Radioactivity in municipal
wastewater and its behaviour in biological treatment. Bulletin of Environmental
Contamination and Toxicology 72, 319-325.
IAEA, 2004. Sediment distribution coefficients and concentration factors for biota in the marine
environment. Technical Report Series No. 422. International Atomic Energy Agency,
Vienna.
Kleinschmidt, R., 2008. – personal observation. Queensland Health.
Larsen, I.L., Stetar, E.A., Giles, B.G. and Garrison, B., 2001. Concentrations of Iodine-131
released from a hospital into a municipal sewer. RSO Magazine 6, 13-18.
Larsen, I.L., Stetar, E.A. and Glass, K.D., 1995. In-house screening for radioactive sludge at a
municipal wastewater treatment plant. Radiation Protection Management 12, 29-38.
Lopez, S., France, J., Gerrits, W.J., Dhanoa, M.S., Humphries, D.J. and Dijkstra, J., 2000. A
generalised Michaelis-Menton equation for the analysis of growth. Journal of Animal
Science 78, 1816-1828.
Martin, J.E. and Fenner, F.D., 1997. Radioactivity in municipal sewage and sludge. Public Health
Reports 112, 308-316.
114
Melville, F. and Pulkownik, A., 2006. Investigation of mangrove macroalgae as bioindicators of
estuarine contamination. Marine Pollution Bulletin 52, 1260-1269.
Miller, W.H., Kunze, J.F., Banerji, S.K., Li, Y.C., Graham, C. and Stretch, D., 1996. The
determination of radioisotope levels in municipal sewage sludge. Health Physics 71, 286-
289.
Ngan, Y., Price, I.R., 1980. Seasonal growth and reproduction of intertidal algae in the Townsville
region (Queensland, Australia). Aquatic Botany 258, 117-134.
OQPC, 2004. Radiation Safety Regulation 1999, Reprint No. 2H, April 2005. Office of the
Queensland Parliamentary Counsel, Brisbane.
Runcie, John W., Ritchie Raymond J. and Larkum Anthony W.D., 2004. Uptake kinetics and
assimilation of phosphorus by Catenella nipae and Ulva lactuca can be used to indicate
ambient phosphate availability. Journal of Applied Phycology 16, 181-194.
Solimabi and Das, B., 1977. Distribution of iodine in marine algae of Goa region. Indian Journal
of Marine Science 6, 180-181.
Sombrito, E.Z., Banzon, R.B., dela Mines, A.S. and Bautista, R.B., 1982. Uptake of Iodine-131 in
Mussel (Mytilus Smaragdinus) and Algae (Caulerpa Racemosa). Journal of the
Radioisotope Society of the Phillippines 22(1), 83-89.
Sundell-Bergman, S., de la Cruz, I., Anla, R. and Hasselblad, S., 2008. A new approach to
assessment and management of the impact from medical liquid radioactive waste.
Journal of Environmental Radioactivity 99(10), 1572-1577.
115
Titley, J.G., Carey, A.D., Crockett, G.M., Ham, G.J., Harvey, M.P., Mobbs, S.F., Tournette, C.,
Penfold, J.S.S. and Wilkins, B.T., 2000. Investigation of the sources and fate of
radioactive discharges to public sewers. R&D Tech Report No. P288. UK Environment
Agency, Bristol. UK
Vives i Batlle, J., Wilson, R.C., McDonald, P. and Parker, T.G., 2005. Uptake and depuration of
131I by the edible periwinkle Littorina littorea: uptake from seawater. Journal of
Environmental Radioactivity 78, 52-67.
Wilson, R.C., Vives i Batlle, J., McDonald, P. and Parker, T.G., 2005. Uptake and depuration of
131I by the edible periwinkle Littorina littorea: uptake from labelled seaweed. Journal of
Environmental Radioactivity 80, 259-271.
116
CHAPTER 6
Concluding Statements
6.1 Summary and Conclusions
The nature and impact of residual radioactivity associated with the water supply cycle were
identified and investigated through the research program. The thesis addresses the research
objectives as described in Section 1.2, with results published in international, peer reviewed
journals.
An assessment of radioactivity in raw and supplied water was undertaken and the impact
of associated residual materials generated during water treatment was investigated. The water
supplies to urban Queensland communities are predominantly surface waters drawn from large
storage basins and impoundments. In the majority of cases they have contained low
concentrations of radioactive elements. In a small number of cases the surface water supply is
supplemented with groundwater, and this practice is becoming more widespread in times of
drought. Higher concentrations of radionuclides were identified originating from these
groundwater supplies. The water treatment process dictated the types of residues and wastes
generated. Urban potable water treatment plants generate considerable volumes of sludge. These
sludges contain the material that is originally suspended in water and then removed by processes
such as floccing and sedimentation. Concentration of radioactive elements in the sludge is higher
than that which is typical of natural soils. In addition to sludge, groundwater treatment plants may
also produce filter and chemical treatment wastes with elevated concentrations of radiological
contaminants.
Three scenarios were developed to assess the radiological impact on three critical groups.
It was identified that water treatment sludge, residual by-products and wastes can contribute to
dose. External gamma radiation exposure was observed to be the predominant pathway for the
cases modelled. The highest avertable dose calculated for the modelled exposure scenarios was
0.2 mSvy-1
for the case where a suburban resident was in regular, close proximity to potable water
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treatment plant sludge that was used as a soil conditioner in a garden where vegetables were grown
for local consumption.
The second study complements the first by examining radioactivity in the groundwater as
opposed to predominantly surface waters. Groundwater is used by many small rural and remote
communities in Australia. In many cases these supplies are not subject to scrutiny though water
quality testing regimes that are considered normal for urban supplies. Additionally, exposure via
residual activity is rarely studied in situations where removal of radionuclides such as radium may
give rise to external exposure and ingestion hazards. At the time of writing the thesis, there was
minimal data available on the distribution of radionuclides in Queensland groundwater, and a lack
of suitable radioanalytical screening methods for rapid measurement of constituents. After
development and validation of a suitable screening radiochemistry method, a survey of
radioactivity in groundwater (110 sites) was conducted as a means of identifying rural and remote
communities in Queensland, Australia, that have the potential to be impacted upon by exposure
pathways associated with the supply, treatment, use and wastewater treatment of the resource.
Radionuclides in groundwater were measured and found to contain 226
Ra, 222
Rn and 228
Ra activity
concentration levels of up to 0.96 BqL-1
, 108 BqL-1
, and 2.8 BqL-1
respectively. Activity
concentration results were classified by aquifer lithology, showing correlation between increased
radium isotope concentration and high pH (basic) volcanic host rock. The groundwater survey and
mapping results were further assessed using an investigation assessment tool developed to identify
remote or rural communities that may require additional radiation dose assessment beyond that
attributed to ingestion of potable water. This was done relative to a comparative reference site
previously investigated by the author.
The final study area covered in the thesis relates to the reuse of wastewater for either
industrial or indirect potable reuse through recycling. Wastewater may contain radioactive
material as a result of industrial processes, from research facilities or as radiophamaceutical waste
excreted by patients undergoing diagnostic and / or therapeutic clinical procedures. Operators of
advanced water treatment plants, water regulators and industry stakeholders have an interest in the
potential for impact of these wastes on the environment, and require access to sensitive monitoring
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systems to assess human and environmental interaction. A study was developed to establish the
suitability of the macroalgae Catenella nipae as an environmental surveillance monitor for
radiopharmaceutical waste discharges to aquatic environments. A series of experiments were
conducted to establish the uptake, concentration factor and depuration characteristics of C. nipae
for 131
I, the predominant waste radionuclide identified in the study. The Michaelis-Menton model
was used for estimating activity concentration of 131
I in environmental waters from deployed C.
nipae sampling devices in the Brisbane River estuary (Queensland) under varying environmental
conditions. Modelled data showed good correlation with measured 131
I activity concentrations in
water. The results suggest that C. nipae can be utilised as a sensitive environmental radioactive
waste monitoring tool.
6.2 Future Research
Based on the outcomes derived from this thesis, it is evident that ongoing research is required to
further identify, characterize and assess the impact of radioactive materials associated with the
supply, treatment, use and disposal of water.
Priority should be given to those areas identified as potentially being of elevated risk,
including further assessment of groundwater supplies in small rural and remote communities, and
the human and environmental impact of release of urban wastewater effluent containing
radiopharmaceutical wastes. At the time of writing, water industry stakeholders and regulators
have shown interest in the progress of this body of research, and agree that targeted research in the
identified areas is justifiable. Finally, the publications detailed in this thesis add to the existing,
but limited body of scientific knowledge in this field.