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Controls on anthropogenic radionuclide distribution in the Sellafield-impacted Eastern Irish Sea

Lookup NU author(s): Dr Peter Leary, Professor Neil Gray, Andrew Fuller

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

Understanding anthropogenic radionuclide biogeochemistry and mobility in natural systems is key to improving the management of radioactively contaminated environments and radioactive wastes. Here, we describe the contemporary depth distribution and phase partitioning of 137Cs, Pu, and 241Am in two sediment cores taken from the Irish Sea (Site 1: the Irish Sea Mudpatch; Site 2: the Esk Estuary). Both sites are located ~10 km from the Sellafield Ltd. nuclear site. Sellafield Ltd. have disposed of low-level aqueous radioactive wastes into the Irish Sea for >50 y. We compare the depth distribution of the radionuclides at each site to trends in sediment and porewater redox chemistry, using trace element abundance, microbial ecology, and sequential extractions, to better understand the relative importance of sediment biogeochemistry vs. physical controls on radionuclide distribution/post-depositional mobility in the sediments. We highlight that the distribution of 137Cs, Pu, and 241Am at both sites is largely controlled by physical mixing of the sediments, physical transport processes, and sediment accumulation. Interestingly, at the Esk Estuary, microbially-mediated redox processes (considered for Pu) do not appear to offer significant controls on Pu distribution, even over decadal timescales. We also highlight that the Irish Sea Mudpatch likely still acts as a source of historical pollution to other areas in the Irish Sea, despite ever decreasing levels of waste output from the Sellafield Ltd. site.


Publication metadata

Author(s): Ray D, Leary P, Livens F, Gray N, Morris K, Law KA, Fuller AJ, Abrahamsen-Mills L, Howe J, Tierney K, Muir G, Law GTW

Publication type: Article

Publication status: Published

Journal: Science of The Total Environment

Year: 2020

Volume: 743

Print publication date: 15/11/2020

Online publication date: 06/07/2020

Acceptance date: 03/07/2020

Date deposited: 24/07/2020

ISSN (print): 0048-9697

ISSN (electronic): 1879-1026

Publisher: Elsevier

URL: https://doi.org/10.1016/j.scitotenv.2020.140765

DOI: 10.1016/j.scitotenv.2020.140765


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