Reconstruction of the 236U input function for the Northeast Atlantic Ocean: Implications for 129I/236U and 236U/238U-based tracer ages
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Date
2015-11
Publication Type
Journal Article
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yes
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Abstract
A reconstruction of historical discharges of ²³⁶U into the Northeast Atlantic Ocean by nuclear installations is presented. The nuclear reprocessing facilities Sellafield (SF), Great Britain (GB) and La Hague (LH), France and potentially also the nuclear fuel processing installation Springfields (SP), GB represent the main contributors of ²³⁶U in the Northeast Atlantic Ocean. Because data on 236U releases is lacking, ²³⁶U discharges from SP and SF are estimated based on the U-isotopic systematics found in the discharges from LH. The resulting reconstruction of ²³⁶U releases indicates that, until 2013, a total of (95 ± 32) kg of ²³⁶U was discharged from SF, SP, and LH. In a second step, the reconstructed ²³⁶U releases are combined with ¹²⁹I data from literature and oceanic and atmospheric box models are used to derive the ¹²⁹I/²³⁶U and ²³⁶U/²³⁸U input functions that, for example, can be used to calculate tracer ages of Atlantic Waters in the Arctic Ocean. Our conceptual results show that the combination of ¹²⁹I/²³⁶U and ²³⁶U/²³⁸U generally allows the estimation of tracer ages over the past approximately 25 years if contributions of ²³⁶U from global fallout are considered. Finally, as a proof of concept, the new method is applied to calculate tracer ages of Arctic Ocean surface samples (collected in 2011/2012) and the results are in good agreement with literature data. We conclude that the combination of ¹²⁹I/²³⁶U with ²³⁶U/²³⁸U in a dual tracer approach provides a sensitive tool for the calculation of tracer ages and ventilation rates in the North Atlantic region.
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published
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Journal / series
Volume
120 (11)
Pages / Article No.
7282 - 7299
Publisher
American Geophysical Union
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Date collected
Date created
Subject
Uranium-236; Iodine-129; Arctic Ocean; tracer ages; nuclear reprocessing
Organisational unit
08619 - Labor für Ionenstrahlphysik (LIP) / Laboratory of Ion Beam Physics (LIP)