Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 125(4), (2020): e2019JC015544, doi:10.1029/2019JC015544.
Description:
The Radium Delayed Coincidence Counter (RaDeCC) is one of the most extensively used equipment for measuring 223Ra and 224Ra activities in water and sediment samples. Samples are placed in a closed He‐circulation system that carries the Rn produced by the decay of Ra to a scintillation cell. Each alpha decay recorded in the cell is routed to an electronic delayed coincidence system which enables the discrimination of 223Ra and 224Ra. In this study, the measurement and quantification methods using the RaDeCC system are assessed through analyses of registered data in different RaDeCC systems worldwide and a set of simulations. Results of this work indicate that the equations used to correct for 223Ra and 224Ra cross‐talk interferences are only valid for a given range of activities and ratios between isotopes. Above certain limits that are specified in this study, these corrections may significantly overestimate the quantification of 223Ra and 224Ra activities (up to ~40% and 30%, respectively), as well as the quantification of their parents 227Ac and 228Th. High activities of 226Ra may also produce an overestimation of 224Ra activities due to the buildup of 222Rn, especially when long measurements with low activities of 224Ra are performed. An improved method to quantify 226Ra activities from the buildup of 222Rn with the RaDeCC system is also developed in this study. Wethus provide a new set of guidelines for the appropriate quantification of 223Ra, 224Ra, 227Ac, 228Th, and 226Ra with the RaDeCC system.
Description:
The authors acknowledge the support from the Generalitat de Catalunya autonomous government through its funding schema to excellence research groups (grants 2017 SGR 1588 and 2014 SGR 1356) and the support from Spanish Government (projects CGL2013‐48869‐C2‐1‐R/2‐R and CGL2016‐77122‐C2‐1‐576 R/2‐R). We would like to thank all the people who contributed to this work sharing the data of their RaDeCC systems, including J. Scholten, C. Claude, M.A. Charette, J.K. Cochran, and R. Neuholz. We want to express our gratitude to our colleagues from the Laboratori de Radioactivitat Ambiental (Universitat Autònoma de Barcelona) and Dr. W. Geibert (AWI) for improving the quality of this work. A. Alorda‐Kleinglass acknowledges financial support from ICTA “Unit of Excellence” (MinECo, MDM2015‐0552‐17‐1)PhD fellowship, BES‐2017‐080740. Dr. V. Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya autonomous government (2017‐BP‐00334). P. van Beek thanks the support from ANR (MED‐SGD project, ANR‐15‐CE01‐0004). M. Diego‐Feliu acknowledges the economic support from the FI‐2017 fellowships of the Generalitat de Catalunya autonomous government (2017FI_B_00365). Compliance with AGU's DataPolicy: All the https://data.mendeley.com/datasets/jtct7mt8zr/2 codes and spreadsheets used in this article are provided online (supplementary material).
Description:
2020-09-27
Keywords:
RaDeCC
;
Ra isotopes
;
quantification
;
U/Th series
;
submarine groundwater discharge
Repository Name:
Woods Hole Open Access Server
Type:
Article
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