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Bioavailable actinide fluxes to the Irish Sea from Sellafield-labelled sediments

Bioavailable actinide fluxes to the Irish Sea from Sellafield-labelled sediments
Bioavailable actinide fluxes to the Irish Sea from Sellafield-labelled sediments

Nuclear discharges to the oceans have given rise to significant accumulations of radionuclides in sediments which can later remobilise back into the water column. A continuing supply of radionuclides to aquatic organisms and the human food chain can therefore exist, despite the absence of ongoing nuclear discharges. Radionuclide remobilisation from sediment is consequently a critical component of the modelled radiation dose to the public. However, radionuclide remobilisation fluxes from contaminated marine sediments have never been quantitatively determined in-situ to provide a valid assessment of the issue. Here, we combine recent advances in the Diffusive Gradients in Thin Films (DGT) sampling technique with ultrasensitive measurement by accelerator mass spectrometry (AMS) to calculate the remobilisation fluxes of plutonium, americium and uranium isotopes from the Esk Estuary sediments (UK), which have accumulated historic discharges from the Sellafield nuclear reprocessing facility. Isotopic evidence indicates the local biota are accumulating remobilised plutonium and demonstrates the DGT technique as a valid bioavailability proxy, which more accurately reflects the elemental fractionation of the actinides in the biota than traditional bulk water sampling. These results provide a fundamental evaluation of the re-incorporation of bioavailable actinides into the biosphere from sediment reservoirs. We therefore anticipate this work will provide a tool and point of reference to improve radiation dose modelling and contribute insight for other environmental projects, such as the near-surface and deep disposal of nuclear waste.

0043-1354
Chaplin, Joshua D
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Christl, Marcus
987c42b7-0376-40e0-a23d-7f74cd151c88
Cundy, Andrew B
994fdc96-2dce-40f4-b74b-dc638286eb08
Warwick, Phillip E
f2675d83-eee2-40c5-b53d-fbe437f401ef
Reading, David G
548dd432-5a6a-4bae-9859-c8a4a6232423
Bochud, François
eaec472c-9935-4338-a3c1-aba4038776e4
Froidevaux, Pascal
0de4e2c6-9158-43dc-9f6e-66dbf27e6641
Chaplin, Joshua D
2623b2e6-0c41-4252-ba6c-aa368d72ad28
Christl, Marcus
987c42b7-0376-40e0-a23d-7f74cd151c88
Cundy, Andrew B
994fdc96-2dce-40f4-b74b-dc638286eb08
Warwick, Phillip E
f2675d83-eee2-40c5-b53d-fbe437f401ef
Reading, David G
548dd432-5a6a-4bae-9859-c8a4a6232423
Bochud, François
eaec472c-9935-4338-a3c1-aba4038776e4
Froidevaux, Pascal
0de4e2c6-9158-43dc-9f6e-66dbf27e6641

Chaplin, Joshua D, Christl, Marcus, Cundy, Andrew B, Warwick, Phillip E, Reading, David G, Bochud, François and Froidevaux, Pascal (2022) Bioavailable actinide fluxes to the Irish Sea from Sellafield-labelled sediments. Water Research, 221, [118838]. (doi:10.1016/j.watres.2022.118838).

Record type: Article

Abstract

Nuclear discharges to the oceans have given rise to significant accumulations of radionuclides in sediments which can later remobilise back into the water column. A continuing supply of radionuclides to aquatic organisms and the human food chain can therefore exist, despite the absence of ongoing nuclear discharges. Radionuclide remobilisation from sediment is consequently a critical component of the modelled radiation dose to the public. However, radionuclide remobilisation fluxes from contaminated marine sediments have never been quantitatively determined in-situ to provide a valid assessment of the issue. Here, we combine recent advances in the Diffusive Gradients in Thin Films (DGT) sampling technique with ultrasensitive measurement by accelerator mass spectrometry (AMS) to calculate the remobilisation fluxes of plutonium, americium and uranium isotopes from the Esk Estuary sediments (UK), which have accumulated historic discharges from the Sellafield nuclear reprocessing facility. Isotopic evidence indicates the local biota are accumulating remobilised plutonium and demonstrates the DGT technique as a valid bioavailability proxy, which more accurately reflects the elemental fractionation of the actinides in the biota than traditional bulk water sampling. These results provide a fundamental evaluation of the re-incorporation of bioavailable actinides into the biosphere from sediment reservoirs. We therefore anticipate this work will provide a tool and point of reference to improve radiation dose modelling and contribute insight for other environmental projects, such as the near-surface and deep disposal of nuclear waste.

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e-pub ahead of print date: 8 July 2022
Published date: 1 August 2022
Additional Information: Funding Information: We gratefully acknowledge funding under the Swiss National Science Foundation Grant No. 175492 , which supported the PhD studentship associated with this project and the open access publishing of this work. We are also grateful to Jamie, Sam and Tamsin Cundy for their contributions to the on-site fieldwork and to Pawel Gaca for additional laboratory assistance. Publisher Copyright: © 2022 The Authors

Identifiers

Local EPrints ID: 468692
URI: http://eprints.soton.ac.uk/id/eprint/468692
ISSN: 0043-1354
PURE UUID: 6c2bfa4e-c6d6-46f6-a703-14dd18fc4655
ORCID for Andrew B Cundy: ORCID iD orcid.org/0000-0003-4368-2569
ORCID for Phillip E Warwick: ORCID iD orcid.org/0000-0001-8774-5125

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Date deposited: 23 Aug 2022 16:40
Last modified: 26 Nov 2022 02:48

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Contributors

Author: Joshua D Chaplin
Author: Marcus Christl
Author: Andrew B Cundy ORCID iD
Author: David G Reading
Author: François Bochud
Author: Pascal Froidevaux

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