Plutonium mobilization from contaminated estuarine sediments, Esk Estuary (UK).

Autor: Balboni E; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States. Electronic address: balboni1@llnl.gov., Merino N; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States., Begg JD; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Amphos 21, Barcelona, Spain., Samperton KM; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Trace Nuclear Measurement Technology Group, Savannah River National Laboratory, Aiken, SC, 29808, United States., Zengotita FE; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, United States., Law GTW; Radiochemistry Unit, Department of Chemistry, University of Helsinki, Finland., Kersting AB; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States., Zavarin M; Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States.
Jazyk: angličtina
Zdroj: Chemosphere [Chemosphere] 2022 Dec; Vol. 308 (Pt 1), pp. 136240. Date of Electronic Publication: 2022 Aug 31.
DOI: 10.1016/j.chemosphere.2022.136240
Abstrakt: Since 1952, liquid radioactive effluent containing 238-242 Pu, 241 Am, 237 Np, 137 Cs, and 99 Tc has been released with authorization from the Sellafield nuclear complex (UK) into the Irish Sea. This represents the largest source of plutonium (Pu) discharged in all western Europe, with 276 kg having been released. In the Eastern Irish Sea, the majority of the transuranic activity has settled into an area of sediments (Mudpatch) located off the Cumbrian coast. Radionuclides from the Mudpatch have been re-dispersed via particulate transport in fine-grained estuarine and intertidal sediments to the North-East Irish Sea, including the intertidal saltmarsh located at the mouth of the Esk Estuary. Saltmarshes are highly dynamic systems which are vulnerable to external agents (sea level change, erosion, sediment supply, and freshwater inputs), and their stability remains uncertain under current sea level rise projections and possible increases in storm activity. In this work, we examined factors affecting Pu mobility in contaminated sediments collected from the Esk Estuary by conducting leaching experiments under both anoxic and oxic conditions. Leaching experiments were conducted over a 9-month period and were periodically sampled to determine solution phase Pu via multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), and to measure redox indicators (Eh, pH and extractable Fe(II)). Microbial community composition was also characterized in the sediments, and at the beginning and end of the anoxic/oxic experiments. Results show that: 1) Pu leaching is about three times greater in solutions leached under anoxic conditions compared to oxic conditions, 2) the sediment slurry microbial communities shift as conditions change from anoxic to oxic, 3) Pu leaching is enhanced in the shallow sediments (0-10 cm depth), and 4) the magnitude of Pu leached from sediments is not correlated with total Pu, indicating that the biogeochemistry of sediment-associated Pu is spatially heterogeneous. These findings provide constraints on the stability of redox sensitive Pu in biogeochemically dynamic/transient environments on a timescale of months and suggests that anoxic conditions can enhance Pu mobility in estuarine systems.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Published by Elsevier Ltd.)
Databáze: MEDLINE
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