The environmental behaviour of redox active radionuclides - a combined biogeochemical and geomicrobiological approach.

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences

Abstract

The UK has a substantial legacy of contaminated nuclear industry sites. Two of the principle sites are at Sellafield and and Dounreay, and the soils and groundwaters at these sites have been contaminated with radioactivity. Indeed, groundwater contamination with radionuclides is a global problem, and decommissioning of nuclear facilities will require control and removal of the contamination. However, little is currently understood of the way that sub-surface microorganisms affect the mobility and behaviour of radionuclides in contaminated land. We have identified four radionuclides that are of particular relevance to radionuclide contamination: technetium; uranium; neptunium; and plutonium. All of these radionuclides are long-lived, and U and Tc are currently priority pollutants at a number of sites throughout the world and are reported as contaminants at Sellafield, whilst Np and Pu will be significant medium term environmental contaminants in radioactive wastes and in contaminated land. Additionally, they are all redox active and are commonly more mobile in their oxidised states when compared to their reduced forms. This project focuses on understanding the interactions of these radionuclides with microorganisms and sediments from contaminated nuclear sites in the UK during 'redox cycling' as reducing conditions develop and as reduced systems are reoxidised. In sub-surface environments, microorganisms control redox chemistry, and many recent studies have highlighted the fact that microorganisms can interact with redox active radionuclides. In turn these interactions may affect the environmental behaviour of Tc, U, Np and Pu by altering their redox state (or speciation). The radionuclide-microbe interactions that occur can be split into two groups: 1. Direct interactions, where the microbe is enzymatically mediating changes in the radionuclide speciation and; 2. indirect interactions, where reduced products of microbial metabolism such as Fe(II), or sulfide can cause abiotic changes in speciation. Currently, there is a relatively poor understanding of both the direct and indirect mechanisms of microbial interactions with radionuclides, and how the balance between enzymatic and abiotic reactions controls radionuclide redox cycling in contaminated environments. Understanding the fundamental mechanisms of these radionuclide-microbe interactions is the focus of this proposal, and we will tackle this problem using three different approaches. As U and Tc are less radiologically hazardous than Np and Pu, we will focus the majority of our experiments on U and Tc, limiting our Np and Pu work to several key systems. We will use geomicrobiology techniques to examine the enzymatic transformations of Tc, U, Np and Pu with key microorganisms found in sub-surface environments and in reducing and reoxidising systems. In addition, we will take sediments from DY and SF, and use biogeochemistry techniques to examine the behaviour of the radionuclides in complex sedimentary environments as reducing conditions develop, and when we reoxidise the sediments. We will also use molecular ecology techniques to identify key microorganisms controlling the biogeochemistry of the sediments. In turn we will isolate pure cultures of key microbes involved in redox cycling in the sediments, and use these microorganisms to investigate radionuclide behaviour during reduction and reoxidation in model systems. These experiments will bridge between the pure culture systems designed to understand enzymatic transformations, and the complex sediment experiments designed to examine transformations in real sedimentary environments. These multidisciplinary approaches will allow substantial advances in understanding the redox cycling behaviour of the radionuclides technetium, uranium, neptunium and plutonium.

Publications

10 25 50
publication icon
Begg J (2011) Bioreduction Behavior of U(VI) Sorbed to Sediments in Geomicrobiology Journal

publication icon
Cherkouk A (2016) Influence of riboflavin on the reduction of radionuclides by Shewanella oneidenis MR-1. in Dalton transactions (Cambridge, England : 2003)

publication icon
Davis J (2006) Processes affecting transport of uranium in a suboxic aquifer in Physics and Chemistry of the Earth, Parts A/B/C

publication icon
Law G (2011) Uranium Redox Cycling in Sediment and Biomineral Systems in Geomicrobiology Journal

publication icon
Law GT (2010) Role of nitrate in conditioning aquifer sediments for technetium bioreduction. in Environmental science & technology

publication icon
Law GT (2010) Geomicrobiological redox cycling of the transuranic element neptunium. in Environmental science & technology

publication icon
Lubick N (2010) From hospital to lab: tracing technetium. in Environmental science & technology

publication icon
McBeth J (2007) Technetium Reduction and Reoxidation in Aquifer Sediments in Geomicrobiology Journal

publication icon
McBeth J (2018) Redox interactions of technetium with iron-bearing minerals in Mineralogical Magazine

 
Description Significant new insights into the biogeochemical evolution of the chemically disturbed zone outside an intermediate level radioactive waste repository and its impact on radionuclide behaviour.
Exploitation Route RWM have commissioned a report on "Summary of the BIGRAD project and its implications for the safety case of a geological disposal facility." This will act as a direct link to radioactive waste disposal policy.
Sectors Energy,Environment,Government, Democracy and Justice

 
Description Fundamental understanding of radionuclide biogeochemistry in natural and engineered environments. This has been applied in radioactive waste disposal (NE/H007768/1) in management of radioactively contaminated land (EPSRC KTA Secondments and Direct funding from Sellafield and NDA Bursary Students and in effluents clean up where radionuclide mineral interactions are of relevance and via a £1.2 M Sellafield Ltd. UoM PhD college.
First Year Of Impact 2006
Sector Energy,Environment
Impact Types Societal,Economic,Policy & public services

 
Description Advice to RWM Ltd on microbial aspects of radwaste disposal via invitation to a series of targeted workshops.
Geographic Reach National 
Policy Influence Type Participation in advisory committee
Impact I have advised RWM Ltd on microbial aspects of radwaste disposal via invitation to a series of targeted workshops (including those on gases, complexants, analogue sites) between 2010-present.
 
Description Citation in the NDA-RWMD Science and Technology Plan 2014
Geographic Reach National 
Policy Influence Type Citation in other policy documents
Impact BIGRAD features in NDA-RWMD Science and Technology Plan. "Application of Knowledge gained through BIGRAD." Task 760. Morris will lead a RWM report on the implications of BIGRAD science to UK policy on waste disposal.
URL http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCUQFjAA&url=ht...
 
Description Deputy Chair, UK Government Committee on Radioactive Waste Management (Nov 2007-present)
Geographic Reach National 
Policy Influence Type Membership of a guidance committee
 
Description External advisor, UK Government Decontamination Service
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Member, Cabinet Office Scientific Advisory Committee (2010-present)
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Member, NERC Expert Group on Radioactivity in the Environment (2011-2012)
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Member, UK Government Nuclear R&D Advisory Board (2012)
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Prfessor Francis livens- Member, UK Government panel 'Scientific Advice to Government in Emergencies'
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description RCUK Energy Programme Strategic Advisory Committee
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Biogeochemistry research funded by ANDRA
Amount £4,900 (GBP)
Organisation National Agency for Radioactive Waste Management (ANDRA) 
Sector Public
Country France
Start 03/2013 
End 04/2013
 
Description EPSRC KTA Secondment
Amount £128,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Department Knowledge Transfer Account (University of Manchester)
Sector Academic/University
Country United Kingdom
Start 11/2014 
End 12/2015
 
Description EPSRC KTA Sellafield Bioreduction
Amount £120,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Department Knowledge Transfer Account (University of Manchester)
Sector Academic/University
Country United Kingdom
Start 02/2012 
End 02/2013
 
Description EnvRadNet2
Amount £400,000 (GBP)
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 03/2016 
End 03/2019
 
Description NDA Studentship Quota
Amount £100,000 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 09/2011 
End 04/2015
 
Description NDA Studentship Quota
Amount £100,000 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 09/2014 
End 04/2018
 
Description NERC Particles
Amount £450,000 (GBP)
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 08/2015 
End 08/2018
 
Description NIMMI
Amount £500,000 (GBP)
Funding ID NE/J024732/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 01/2013 
End 01/2016
 
Description STFC Diamond Beamline Access
Amount £630,000 (GBP)
Funding ID SP10163, SP9621, SP9045, SP9841, SP8544, SI8115, SI8114, SP8070, sp8059, sp7593, sp7367, sp4985 
Organisation Diamond Light Source 
Sector Private
Country United Kingdom
Start 01/2010 
End 06/2015
 
Description STFC Funded PhD
Amount £80,000 (GBP)
Organisation Research Councils UK (RCUK) 
Sector Public
Country United Kingdom
Start 09/2013 
End 03/2017
 
Description STFC Network Extension
Amount £400,000 (GBP)
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 03/2016 
End 03/2018
 
Description STFC Network Grant - Env Rad Net
Amount £300,000 (GBP)
Organisation Research Councils UK (RCUK) 
Sector Public
Country United Kingdom
Start 09/2012 
End 09/2015