ASSESSING THE IMPACT OF IONISING RADIATION IN TEMPERATE COASTAL SAND DUNE ECOSYSTEMS: MEASUREMENT AND MODELLING Thesis submitted in accordance with the requirements of the University of Liverpool for the degree of Doctor in Philosophy by Michael David Wood January 2010 ABSTRACT Assessing the impact of ionising radiation in temperate coastal sand dune ecosystems: measurement and modelling Michael D. Wood This thesis presents the results of a 6-year research project to investigate the radioecology of temperate coastal sand dunes. Samples (n = 617) of soil, water and biota were collected from the Drigg coastal sand dunes (West Cumbria, UK) between February 2005 and October 2007. Biota groups sampled included amphibians, birds, invertebrates, mammals, reptiles, plants (including lichens and mosses) and fungi. All samples were analysed for 40K, 137Cs and 241Am. A sub-set of samples (n = 26) was analysed for 90Sr, 99Tc, 238Pu and 239+240Pu. Additional soil analyses included soil moisture, bulk density, pH, organic matter content, carbonate content and cation concentrations (Ca2+, K+, Na+ & Mg2+). The application of three publicly-available environmental radiation protection models (ERICA, R&D128/Sp1a & RESRAD-BIOTA) to an assessment of ionising radiation impacts at the Drigg coastal sand dunes site was evaluated. Soil activity concentration data were used as input data and model results compared with measured activity concentrations in sand dune biota. Radionuclide concentration ratios (CRs) were identified as an important source of variation in model predictions. For sand dune small mammals, Am, Cs and Pu CRs were found to be 1 – 2 orders of magnitude lower than those for small mammals in other terrestrial ecosystems. For reptiles, the variability could be attributed to the paucity of data on transfer to this vertebrate group. Through literature review, mining of unpublished data sets and analysis of samples collected from the Drigg coastal sand dunes, CR databases were developed for reptiles (across a range of ecosystem types) and for sand dune biota. Analysis of sand dune soil data suggested that both sea-to-land transfer and the transport of sand grains in saltation influence the soil activity concentrations in coastal sand dunes. The low CRs for sand dune biota may be due to low bioavailability of particulate-bound radionuclides. University of Liverpool, UK; E-mail address: [email protected] i (This page is left blank intentionally) ii ACKNOWLEDGMENTS I wish to thank Dr David Copplestone (Environment Agency, UK), Dr Rick Leah and Professor Alan McCarthy (both from the University of Liverpool, UK) for their supervision and support during the development of this thesis. I am indebted to all three of them. Special thanks are expressed to David for his ongoing support and friendship and to Alan for taking on the role of primary supervisor following Rick‟s sudden death in February 2009. I would like to acknowledge the additional support of Dr Nicholas Beresford (Centre for Ecology and Hydrology (CEH), UK) for his comments and advice on various sections of the manuscript. I am also grateful to my internal assessors at the University of Liverpool (Professor Alan McCarthy and Professor Andrew Plater) for their feedback on the early design and development of my research programme. For their excellent technical support at the University of Liverpool, I am grateful to Mr Mike O‟Connor, Mr Leslie Connor and Mr Keith Hatton. Mike endured many weeks of fieldwork with me on the Drigg coastal sand dunes. Without his patience and willingness to work both long days and during night-time amphibian surveys, the sampling would have been significantly less productive. Mike also took some of the photographs that are presented in Chapter 2 of this thesis. Mike, Les and Keith provided technical support for the soil property determinations and gamma spectrometry analysis. In addition, Les provided technical support for the cation analyses. I am also grateful to Ms Phillipa Hall, Ms Jessica Smallcombe and Ms Sally Wittrick from the University of Liverpool for their assistance with sample preparation. I would like to acknowledge Ms Catherine Barnett (CEH) and Dr Richard Wilson (Westlakes Scientific Consulting, UK) for their support in analysing biota samples and water samples respectively. For their help in accessing international data sets to support the reptile transfer database development presented in Chapter 7 of this thesis, I wish to acknowledge Dr John Ferris, iii Dr Matthew Johansen and Dr John Twining (all from the Australian Nuclear Science and Technology Organisation (ANSTO)), Dr Dmitry Semanov (A.N. Severtsov Institute of Ecology and Evolution, Russia) and Dr Tamara Yankovich (AREVA Resources Canada Inc., Canada). In addition to the people already acknowledged, I am grateful to Dr Brenda Howard (CEH), Professor Steve Jones, Professor Paul McDonald and Dr Jordi Vives-i-Battle (all from Westlakes Scientific Consulting Ltd) for advice received during the preparation of peer-reviewed publications from this thesis. Although the research for this part-time Ph.D. was „self-funded‟, I would like to acknowledge the financial contributions from the EC 6th Framework Programme, the Environment Agency and English Nature (now Natural England, UK) for research project funding which has, in part, helped to cover some of the sampling and analysis costs associated with the development of this thesis. I also acknowledge the Hereptological Conservation Trust (for licensing and facilitating herptile sample collection), the British Association of Shooting and Conservation (BASC) and the Egremont and District Wildfowlers Association (for the provision of bird samples) and the Lake District National Parks Authority, the Muncaster Estate and Mr Ireland (for permitting site access and sampling). Finally I wish to thank my family for supporting me in undertaking this part-time Ph.D. research. In particular, I wish to thank my wife, Mrs Helen Wood, for her encouragement and patience throughout the many evenings, weekends and holidays that I have spent working on this thesis. iv This thesis is dedicated to Helen and Abigail with love v (This page is left blank intentionally) vi CONTENTS ABSTRACT ............................................................................................................... I ACKNOWLEDGMENTS .................................................................................... III CONTENTS .......................................................................................................... VII LIST OF FIGURES ............................................................................................ XIII LIST OF TABLES ............................................................................................ XVII LIST OF ABBREVIATIONS ............................................................................ XXI CHAPTER 1 - INTRODUCTION ......................................................................... 1 1.1. ENVIRONMENTAL RADIOACTIVITY .................................................... 1 1.1.1. REJUVENATION IN THE NUCLEAR INDUSTRY ................................................ 1 1.1.2. IMPACTS OF IONISING RADIATION ................................................................. 2 1.1.2.1. Ionising radiation and dose ................................................................. 2 1.1.2.1. Effects of ionising radiation on non-human biota ............................... 4 1.2. ENVIRONMENTAL RADIATION PROTECTION .................................. 6 1.2.1. RADIOECOLOGY AND THE DEVELOPMENT OF ENVIRONMENTAL RADIATION PROTECTION MODELS .............................................................................................. 8 1.2.2. MODELS AND MODEL TESTING...................................................................... 9 1.3. OBJECTIVES ................................................................................................. 11 1.3.1. MEASUREMENT ........................................................................................... 11 1.3.2. MODELLING ................................................................................................ 12 CHAPTER 2 – THE DRIGG COASTAL SAND DUNES ............................... 15 2.1. COASTAL SAND DUNES ............................................................................ 15 2.1.1. SAND TRANSPORT, DUNE GROWTH AND MORPHOLOGY .............................. 16 2.1.2. SOIL DEVELOPMENT .................................................................................... 20 2.1.3. ZONATION AND SUCCESSION ...................................................................... 22 2.1.4. HYDROLOGY ............................................................................................... 23 2.1.4.1. Precipitation ....................................................................................... 24 2.1.4.2. Groundwater ....................................................................................... 25 2.2. THE STUDY SITE ......................................................................................... 25 2.2.1. SITE LOCATION ........................................................................................... 25 2.2.2. SITE DESCRIPTION ....................................................................................... 26 2.2.3. SITE DISTURBANCE ..................................................................................... 32 2.3. JUSTIFICATION FOR SITE SELECTION .............................................. 34