I work very closely with colleagues in other Schools of the University of Manchester, and also elsewhere. I work in several diverse areas, including-
Microbial transformations of radionuclides
Microorganisms can alter local geochemical conditions through redox processes, changes in pH or production of complexants. These can have major effects on trace element and radionuclide behaviour, and we focus our efforts on trying to understand the mechanisms by which these transformations occur.
Colonization and transformation of depleted U/Ti alloy (DU), used in anti-armour munitions, by the ericoid mycorrhizal fungus Hymenoscyphus ericae after three months. The cord-like aggregated hyphae interact with black DU decomposition products and the intensity of the yellow colouration of mycelial cords increased with exposure time. Data and images from Dr M. Fomina, University of Dundee.
Mineral surface reactions
The interaction of radionuclides in solution with mineral surfaces is an important control on their environmental mobility. Understanding the mechanisms of these reactions is essential if we are to make credible predictions of radionuclide mobility, but this requires the use of a wide range of imaging (e.g. electron microscopy, atomic force microscopy) and spectroscopic techniques (e.e. X-ray photoelectron and X-ray absorption spectroscopies) to gain as much information as possible.
Scanning electron microscope image of becquerelite, Ca[(UO2)3O2(OH)3]2.8H2O, crystallites formed by reaction of UO22+ in solution with the surface of plagioclase feldspar.
Radionuclides in the 'real' environment
The natural environment is very complex and heterogeneous, and radionuclides are typically present at concentrations below 10-12 g g-1. It is therefore very difficult even to measure concentrations in different components, and even more difficult to develop an understanding of the processes which are operating. These studies require the development of techniques for quantifying radionuclides in quantities as small as 1000 atoms, and the ability to measure a range of element and isotope ratios in order to fingerprint different sources.
The 241Pu distribution down the profile of an intertidal sediment from the NE Irish Sea (in red; bottom and left axes) mirrors the historical discharges from Sellafield (in blue; top and right axes).