Variability of fallout radionuclides (FRNs) in river channels: implications for sediment tracing

Muñoz-Arcos, Enrique; Millward, Geoffrey E; Clason, Caroline C; Hartley, Richard; Bravo-Linares, Claudio; Blake, William H

Abstract

Purpose: The aims of this research were to assess the sources of variability of particulate FRNs (7 Be, 210 Pb ex and 137 Cs) in river channels, the influence of sediment properties such as particle size distribution (PSD) and organic matter (OM) on FRN distributions, and to discuss the implications for sediment tracing in rivers. Methods: Suspended and channel bed sediment samples were collected in the River Avon (Devon, UK) during five strategic surveys involving a wide variation of river flows, including flood conditions. Particulate matter was analysed for 7 Be, 210 Pb ex and 137 Cs by gamma spectrometry, PSD by laser diffraction, and organic constituents, total organic carbon (TOC) and total nitrogen (TN) by elemental analysis. Results: FRNs activity concentrations vary significantly both spatially, characterised by changes in activity concentrations within and between locations, and temporally, with changes during the storm hydrograph and between seasons. Variability was attributed to changes in sediment sources and, on some occasions, to significant correlation of activity concentrations with sediment properties. The results also highlighted the influence of changes in channel characteristics and the magnitude and frequency of floods on FRN distributions. Conclusion: In the context of sediment tracing, attention should be given to seasonal changes in riverine conditions that have the potential to affect 7 Be and 137 Cs conservativeness. Application of FRNs in sediment fingerprinting studies should be accompanied by appropriate temporal characterisation of potential sediment sources. Finally, potential contribution of 7 Be-depleted sediment from channel resuspension to the suspended load should also be considered.

Citation

Muñoz-Arcos, E., Millward, G. E., Clason, C. C., Hartley, R., Bravo-Linares, C., & Blake, W. H. (online). Variability of fallout radionuclides (FRNs) in river channels: implications for sediment tracing. Journal of Soils and Sediments, https://doi.org/10.1007/s11368-024-03881-z

• Journal Article Type: Article
• Acceptance Date: Jul 30, 2024
• Online Publication Date: Aug 7, 2024
• Deposit Date: Aug 7, 2024
• Publicly Available Date: Aug 8, 2024
• Journal: Journal of Soils and Sediments
• Print ISSN: 1439-0108
• Electronic ISSN: 1614-7480
• Publisher: Springer
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1007/s11368-024-03881-z
• Public URL: https://durham-repository.worktribe.com/output/2743917