Radioactivity and the Environment

LO-RISE PhD's

Controls on radionuclide distribution in the Sellafield near shore

Daisy Ray, Manchester University

The authorised discharge of radioactive effluent (Low Level waste) from Sellafield Ltd to the Eastern Irish Sea has taken place between place 1951-1992. An offshore mud-patch and the Ravenglass Saltmarsh have received significant radionuclide input as a result of subsequent deposition of this waste. Using a variety of techniques, the core sections from both sites will be characterised for U, Np, and Pu content, stable element composition, and mineralogy. Other radionuclides will be measured as part of this process (e.g., Tc). In addition, where applicable, select samples will be (i) chemically extracted, and (ii) characterised at the Diamond Light Source. The biogeochemical study of these radionuclides also has broad applicability for geological disposal (Pu, U, Np) and contaminated land scenarios (Pu, U, Np, Am, Cs).

Investigating the kinetic and thermodynamic interactions of key organic and inorganic ligands with uranium at three natural analogue sites in the UK

Jo Kulaszewska, Loughborough University

Long-lived radionuclides are of key concern due to their long half-lives and the fact they can provide a significant dose in some areas. In addition long-lived radionuclides are also present in waste which is currently planned to be buried in deep geological disposal in sites in the UK. There is the potential, over time, for some of this waste to migrate back to the surface. The purpose of this project is to investigate processes and paths by which uranium may potentially return to the surface. Natural analogue sites will be used in conjunction with more traditional lab experiments as they provide an environment in which it is possible to observe migratory processes over longer timeframes than is usually possible. The three natural analogue sites to be investigated in this project are:

  • Needle's Eye: Site of a natural pitchblende vein in Scotland from which uranium is leached into an organic sink.
  • The Esk Estuary: Located South of Sellafield, this site has historically received some of the waste legally released into the Irish Sea.
  • South Terras: An abandoned uranium mine in Cornwall; there is still active mine spoil at the site from which uranium is potentially leached.

At each site the key processes of uranium migration will be investigated with the use of batch and flow experiments. The interaction with uranium with key site-specific ligands such as organic and inorganic colloids will be considered, especially interactions and processes involving humic acid. The project is part of the Lo-RISE consortium and will help build up a comprehensive picture of the movement of key long-lived radionuclides in the surface environment.

Microbial Diversity and Function in Lo-RISE Radionuclide Impacted Soils and Sediments

Pete Leary, Newcastle University

The aim of this project, within the Lo-RISE consortium, is to take an ecological approach to discern the microbe-sediment/soil-radionuclide interactions, within the Lo-RISE radionuclide contaminated environments. Using molecular-based techniques in tandem with ecological statistical analysis, we will characterize the diversity and function of microbes in these environments, and discern their potential impacts on the transport and fate of radionuclides. We will characterize a broad view of the microbial metabolic repertoire and redox processes occurring at given points within a contamination gradient. We will combine our findings with the geochemical data garnered by other Lo-Rise partners to examine the impact of the abiotic characteristics and dynamics of the study sites upon the microbial community, and where possible, identify reciprocal interactions.

Plant and associated arbuscular mycorrhizal fungi bioaccumulation of uranium, radium and thorium from natural environments containing elevated concentrations of radionuclides

Helena Davis, Manchester University

The overall focus of the project is to elucidate the extent and mechanism of uranium, radium and thorium bioaccumulation into native plants via associated arbuscular mycorrhizal fungi (AMF) from Needle’s Eye (Scotland) and South Terras (Cornwall), two environments with elevated concentrations of naturally occurring- and technologically enhanced- naturally occurring radionuclides, respectively. AMF play an important role in plant nutrient uptake and can potentially limit U translocation from plant roots to above ground tissue. However, the biological and chemical mechanism of U, Ra and Th plant uptake via AMF is currently not understood. Previous research has suggested U binding to plant cell walls and complexion with polyphosphates however, experimental evidence for both hypotheses is currently lacking. Plus whether local flora has evolved tolerance to these environments is unknown.

Radium Migration Through the Surface Environment at Three Natural Analogue Sites in the UK

Dimitris Kosmidis, Loughborough University

Determination of the natural radioactivity with emphasis on radium has been carried out. Surface soil and sediment samples were collected form three natural analogue sites in the United Kingdom and analysed via gamma-ray spectrometry. The three sample sites currently being investigated are: South Terras, Ravenglass and Needle's Eye, characterised, either by naturally occurring uranium mineralization, or authorised discharges from nuclear sites. The average concentrations of radionuclides including 226Ra and other trace elements were correlated with other physico-chemical parameters of the soil samples techniques include: total organic carbon, organic matter, pH, EC and soil texture. The results from the total organic carbon analyses varied from 0,097% to 5,26% for South Terras samples, from 0,3% to 6,9% for Ravenglass samples and from 0,26% to 3,39% for Needle’s Eye, while the results for organic matter were from 0,18% to 9,07%, form 0,51% to 11,9% and from 0,68% to 4,54% respectively. Combined with experimental results, the geochemical status and the radiological imprint of the study areas are presented.

Transport processes controlling radionuclide uptake by plants

Jana Darmovzlova, Cranfield University

This doctoral research will contribute towards the overall aims of the Lo-Rise project by further enhancing current understanding of diffusion and solid-solution partitioning of U/Ra in the relevant proximity of plant root surfaces, and defining the transport rates through the soil and plant root membrane. Consideration will be given to changes in speciation (and hence bioavailability) of the U/Ra species in soil as a consequence of introduction of reactants commonly present in plant root-soil systems. Mathematical expression of these processes will support the model developed by the Cranfield University PDRA. All experiments will be carried out in vitro under well-controlled experimental conditions.Joanna Kulaszewska, Loughborough University:Investigating the kinetic and thermodynamic interactions of key organic and inorganic ligands with uranium at three natural analogue sites in the UK.

Long-lived radionuclides are of key concern due to their long half-lives and the fact they can provide a significant dose in some areas. In addition long-lived radionuclides are also present in waste which is currently planned to be buried in deep geological disposal in sites in the UK. There is the potential, over time, for some of this waste to migrate back to the surface. The purpose of this project is to investigate processes and paths by which uranium may potentially return to the surface. Natural analogue sites will be used in conjunction with more traditional lab experiments as they provide an environment in which it is possible to observe migratory processes over longer timeframes than is usually possible. The three natural analogue sites to be investigated in this project are:

Needle’s Eye: Site of a natural pitchblende vein in Scotland from which uranium is leached into an organic sink.

The Esk Estuary: Located South of Sellafield, this site has historically received some of the waste legally released into the Irish Sea.

South Terras: An abandoned uranium mine in Cornwall; there is still active mine spoil at the site from which uranium is potentially leached.

At each site the key processes of uranium migration will be investigated with the use of batch and flow experiments. The interaction with uranium with key site-specific ligands such as organic and inorganic colloids will be considered, especially interactions and processes involving humic acid. The project is part of the Lo-RISE consortium and will help build up a comprehensive picture of the movement of key long-lived radionuclides in the surface environment.

Transport and Ecosystem Uptake of Sellafield-Derived Radionuclides in the Marine Environment

Kieran Tierney, SUERC/SAMS

This project is investigating the biogeochemistry of Sellafield-derived 14C and 129I in the Irish Sea and the Scottish West Coast. To study the transport of these radionuclides, marine water from sites north of the Irish Sea will be analysed. Marine molluscs uptake 14C from the dissolved inorganic carbon pool during shell formation and subsequent shell erosion results in 14C being incorporated into sediments. The project will examine the accumulation of inorganic 14C in near-field and far-field intertidal sites to further explore the extent of 14C dispersion from Sellafield. In addition, integrated food web studies will be conducted, analysing materials such as benthic macrofauna, plankton, fish and marine mammal samples for 14C and the data used to parameterise Ecotracer models using existing Ecopath with Ecosim models. This project will focus on the west coast of Scotland and ties in with similar projects focussing on the Irish Sea, Graham Muir PDRA, and intertidal ecosystems, Helen Hastie PhD. This is a joint studentship between the Scottish Universities Environmental Research Centre (SUERC) and the Scottish Association for Marine Science (SAMS).