1.1. BACKGROUND
The mining and milling of uranium ores produce residues which must be managed safely, including wastewater, tailings and waste rock stockpiles. A number of other industries also produce residues which contain uranium or thorium series radionuclides or both. Examples include phosphogypsum from the phosphate industry and residues from mineral sands processing and from the oil, gas and coal industries. All of these residues are naturally occurring radioactive materials (NORM), for which radiological impact assessments have increasingly been conducted in recent years.
Radionuclides of concern found in NORM mainly include isotopes of U, Th, Ra, Rn, Pb and Po [1.1]. Of these, Ra is of particular importance owing to the presence of Ra isotopes in all three natural decay series, the relatively long half-lives and short lived progeny of two of the isotopes (226Ra and 228Ra), the high mobility of Ra in the environment under a number of common environmental conditions and the tendency of Ra to accumulate in bone following uptake into the body.
Radium was first identified as an important stressor for humans and the environment mobilized by uranium mining and processing industries in the early 1950s [1.2-1.8]. Significant Ra contamination has been identified in many places, arising mainly from uranium, phosphate and even gold mining and milling operations, and from coal ash. Radium isotopes are also important sources of exposure in the oil, gas and coal industry. Additionally, a number of historical industrial sites have been left contaminated with residues from activities involving Ra. Such sites include factories where Ra was used in luminescent paint and Th was used in Th coated gas mantles. Residual contamination is also present at many military establishments and scrapyards [1.9].
In response to the need of its Member States, the IAEA has long supported efforts to develop reports on the environmental fate of Ra. In 1990, it published the IAEA Technical Reports Series No. 310 (TRS 310), which compiled information for the estimation of the impact of Ra on humans and on terrestrial, freshwater and marine environments [1.10].
TRS 310 discussed natural and technologically enhanced sources of Ra, its properties and environmental behaviour as well as methods of analysis in environmental samples, control of releases and assessment of exposure to Ra. Although the main emphasis in the report was on environmental problems caused by uranium mining and milling, it also provided a basis for environmental impact assessments for many contamination scenarios.
It is essential that the information base used for radiological assessments and subsequent remediation planning is kept up to date and this, in itself, is a strong argument for regular revisions of reference documents such as TRS 310. Since its publication, a large number of publications on Ra transfer in the environment have been produced and merit consideration. In particular, in 2004, 2009 and 2010, the IAEA issued a set of basic reports on radionuclide transfers in terrestrial, freshwater and marine environments [1.8, 1.11-1.13]. These reports provided information on key transfer processes, concepts and models that are important in radiological assessments for all radionuclides, including Ra.
Additionally, throughout most of the period from 1991 to the present, the IAEA has run a series of projects aimed at improving environmental assessment and remediation. Through these projects, the environmental behaviour of Ra was considered in many other IAEA reports, mainly in the context of contaminated site characterization and environmental remediation. The topics of these reports include: the characterization of contaminated sites [1.14, 1.15], technical and non-technical factors relevant for the selection of the preferred remediation strategy and technology [1.6, 1.16], an overview of applicable technologies for environmental remediation [1.17], options for the cleanup of contaminated groundwater [1.7], and planning and management issues [1.18-1.21]. In addition, a number of other IAEA publications dealing with related aspects have been compiled as part of various IAEA projects. These include reports on the remediation of uranium mill tailings [1.22] and dispersed contamination [1.23], the decontamination of buildings and roads, the characterization of decommissioned sites and management of radioactive waste and radiation protection in the oil and gas industries [1.8].
Historically, interest in Ra has focused on three aspects, namely its: (a) impact on human health through radiation exposure, (b) application as a tracer of environmental processes and (c) use in various industrial, medical and other applications. This report addresses the environmental behaviour of Ra and so discusses the first two of these aspects but not industrial, medical or other applications. The primary intention of the present report is to support environmental assessments and remediation in areas contaminated by Ra by presenting state of the art concepts, models and parameters rather than providing a summary of all available information on the environmental behaviour of Ra.
There are four Ra isotopes naturally present in the environment: 226Ra of the uranium decay series, 228Ra and 224Ra of the thorium decay series and 223Ra of the actinium decay series. Of these, 226Ra and 228Ra have relatively long half-lives (1600 and 5.75 years, respectively), and the majority of the published literature on Ra relates to these two isotopes. However, both 223Ra and 224Ra, which have half-lives of some days, have several applications, particularly as environmental tracers. As all Ra isotopes exhibit similar behaviour in the environment, the study of one isotope may provide useful information on the behaviour of the other isotopes. Therefore, this report discusses the environmental behaviour of all four naturally occurring isotopes.
The radiological impact of Ra is due to exposure to the Ra isotopes themselves and also to exposure to their decay progeny. In particular, exhalation of the 226Ra decay product 222Rn and of the 224Ra decay product 220Rn from soil, building materials and NORM can result in a significant inhalation hazard. However, this report is focused exclusively on Ra, and does not discuss in detail Ra decay products (such as 222Rn and 220Rn) which may contribute to its total environmental impact.
1.2. OBJECTIVE
This report is primarily intended to provide IAEA Member States with information for use in the radiological assessment of accidental releases and routine discharges of Ra in the environment. The information will ideally also serve as a basis for remediation planning and identification of optimal remediation strategies in areas contaminated by Ra.
1.3. SCOPE
This report covers Ra behaviour in the terrestrial, freshwater and marine environments. The information presented is relevant to the transfer of radionuclides through food chains to both humans and other organisms. The corresponding remedial options and regulatory aspects are also within the scope of this report. Additionally, applications of Ra isotopes to environmental issues are discussed to alert readers to studies that use Ra isotopes as tracers of environmental processes. The report is also intended to be used in conjunction with IAEA reports related to the assessment of the radiological impact of radioactive discharges, as described in Safety Reports Series No. 19, Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment [1.24], IAEA Safety Standards Series No. WS-G-2.3, Regulatory Control of Radioactive Discharges to the Environment [1.18] and other related reports.
1.4. STRUCTURE
This report includes seven chapters. The physical, chemical and biological properties of Ra are discussed in Chapter 2. Chapter 3 addresses sources and presence of Ra in the environment whilst Chapter 4 considers environmental pathways specific to Ra and corresponding models. Dose assessment models related to the occurrence of Ra in the environment and remediation technologies for Ra are given in Chapter 5 and 6, respectively. Chapter 7 presents various case studies describing the main features of environmental impact assessments specific to different contamination scenarios.

A number of industrial activities produce residues containing either uranium or thorium series radionuclides or both. These include the mining and milling of uranium and of other metalliferous and non-metallic ores; the production of coal, oil and gas; the extraction and purification of water; and the production of industrial minerals such as phosphates. Residues from such activities have become of increasing interest from a radiological impact assessment point of view in recent years and isotopes of radium are often of particular interest in such assessments.
The IAEA attaches high importance to the dissemination of information that can assist Member States with the implementation and improvement of activities related to radiation safety standards, including management of radioactive residues containing natural radionuclides, such as radium isotopes.
In 1990, the IAEA published Technical Reports Series No. 310 (TRS 310), The Environmental Behaviour of Radium. Since the publication of TRS 310, a considerable number of publications related to the environmental behaviour of radium have appeared in the literature. It was therefore considered timely to produce a replacement report providing up to date information on key transfer processes, concepts and models that are important in radiological assessments and environmental applications of radium.
This report outlines radium behaviour in terrestrial, freshwater and marine environments. The primary objective of the report is to provide IAEA Member States with information for use in the radiological assessment of accidental releases and routine discharges of radium in the environment, and in remediation planning for areas contaminated by radium. Additionally, applications of radium isotopes as tracers of environmental processes are discussed.
The IAEA wishes to express its gratitude to P. Martin (Australia) for his assistance in editing this report, as well as to those experts who contributed to its development and completion.
The IAEA officers responsible for this report were S. Fesenko, H. Nies and M. Phaneuf of the IAEA Environment Laboratories, in collaboration with G. Proehl of the Division of Radiation, Transport and Waste Safety.

CHAPTER 1. INTRODUCTION 1

1.1. Background 1

1.2. Objective 3

1.3. Scope 3

1.4. Structure 4

CHAPTER 2. PROPERTIES OF RADIUM 6

2.1. A short history of radium 6

2.2. Physical properties 8

      2.2.1. Isotopes of Ra 8

      2.2.2. Decay series 9

2.3. Radium decay products 12

2.4. Chemical properties 15

      2.4.1. Basic characteristics 15

      2.4.2. Aqueous speciation 15

      2.4.3. Precipitation 16

      2.4.4. Adsorption and desorption 17

2.5. Determination of radium isotopes 21

CHAPTER 3. RADIUM IN THE ENVIRONMENT 33

3.1. Introduction 33

3.2. Radium in parent rocks and soils 36

      3.2.1. Parent rocks 36

      3.2.2. Soil 38

3.3. Radium in groundwater 44

3.4. Radium in freshwater 48

3.5. Radium in seawater 52

      3.5.1. Oceans 52

      3.5.2. Estuaries, lagoons and coastal waters 53

3.6. Radium in air 54

3.7. Radium in terrestrial plants 55

3.8. Radium in terrestrial animals 67

3.9. Radium in freshwater biota species 75

3.10. Radium in marine biota species 81

      3.10.1. Ra concentrations in marine biota 81

3.11. Radium in drinking water and food 87

CHAPTER 4. ENVIRONMENTAL PATHWAYS AND CORRESPONDING MODELS 106

4.1. Concepts 106

      4.1.1. General approach 107

      4.1.2. Reference plants and animals 109

      4.1.3. Reference dose levels 109

      4.1.4. Dosimetric models 110

      4.1.5. Model complexity 110

4.2. Terrestrial environment 111

      4.2.1. Soil-radium interactions 111

      4.2.2. Radium soil to plant transfer 118

      4.2.3. Radium transfer to animals 129

4.3. FRESHWATER 133

      4.3.1. Groundwater 133

      4.3.2. Surface Water 145

      4.3.3. Uptake by freshwater biota species 149

4.4. MARINE ENVIRONMENT 152

      4.4.1. Radium input to the ocean 153

      4.4.2. Sediment-radium interactions 155

      4.4.3. Ra isotopes and coastal mixing and estuary flushing rates 155

      4.4.4. Transfer to marine biota 157

CHAPTER 5. DOSE ASSESSMENT 173

5.1. Models and data for estimating internal exposures to humans 173

5.2. Dose conversion factors for estimating external and internal doses to biota 176

      5.2.1. Internal exposure 177

      5.2.2. External exposure 180

      5.2.3. Non-homogeneous distribution 186

CHAPTER 6. MITIGATION AND REMEDIATION ISSUES 188

6.1. Approach to identify mitigation and remediation measures 188

6.2. Removal of radium from drinking water 189

6.3. Removal of radium from mining and processing waters 192

6.4. Removal of radium from contaminated groundwater 194

6.5. Removal of Ra from soil 197

6.6. Control of radium in the building industry 198

6.7. Control of radium in biota 201

6.8. Remediation of contaminated areas 201

6.9. Management of special waste rock and residues from former mining and milling activities 204

6.10. Management of NORM with elevated radium concentrations 209

CHAPTER 7. CASE STUDIES 219

7.1. Rabbit Lake 219

      7.1.1. Study approach 220

      7.1.2. Receptor characterization 220

      7.1.3. Risk assessment 222

      7.1.4. Reference dose rates 223

      7.1.5. Transport and fate 225

      7.1.6. Exposure 226

      7.1.7. Ecological Risks 226

      7.1.8. Doses to humans 230

7.2. Radium extraction plant Olen 232

      7.2.1. Background 232

      7.2.2. Overview of the environmental contamination 233

      7.2.3. Overview of the legacy sites 237

      7.2.4. The UMTRAP facility 238

      7.2.5. The licensed Bankloop storage facility 241

      7.2.6. The D1 landfill 242

      7.2.7. The S1 landfill 245

      7.2.8. The IOK-UM disposal site 245

      7.2.9. Concluding remarks 246

7.3. Radium-228 as a basin scale integrator of SGD to the Atlantic Ocean 246

7.4. Wismut Environmental Rehabilitation Project 248

      7.4.1. Background 248

      7.4.2. Radium at Wismut sites 252

中国标准化研究院国家标准馆