Micro-analytical characterization of thorium-rich aggregates from Norwegian NORM sites (Fen Complex, Telemark). (August 2020)

• Record Type: Journal Article
• Authors: Cagno, Simone; Lind, Ole Christian; Popic, Jelena Mrdakovic; Skipperud, Lindis; De Nolf, Wout; Nuyts, Gert; Vanmeert, Frederik; Jaroszewicz, Jakub; Janssens, Koen; Salbu, Brit
• Is Part Of: Journal of environmental radioactivity. Volume 219(2020)
• Publication Date: 2020-08
• Subjects: Thorium -- NORM -- REE -- Radioactive particles -- Electron microscopy -- Synchrotron radiation -- μ-XRF -- μ-XRD -- μ-CT; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2020.106273
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: In this study we performed microscopic characterization of mineral particles that were collected in the thorium-rich Fen Complex in Norway and identified and isolated based on autoradiography in function of their radioactivity. For this we combined information obtained with X-ray absorption μ-CT, μ-XRF and μ-XRD, both in bi- and in three-dimensional (tomographic) mode. We demonstrate that radionuclides and metals are heterogeneously distributed both within soil samples and within individual Th-enriched aggregates, which are characterised as low-density mineral bulk particles with high density material inclusions, where Th as well as several metals are highly concentrated. For these sites, it is important to take into account how these inhomogeneous distributions could affect the overall environmental behaviour of Th and progeny upon weathering due to human or environmental factors. Moreover, the estimated size of the Th-containing inclusions as determined in this work represents information of importance for the characterization of radionuclides and toxic metals exposure, as well as for assessing the viability of mining for Th and rare-earth metals in the Fen Complex and the associated environmental impact. Highlights: Heterogeneous distribution of radionuclides and metals demonstrated with a combination of μ-XRF, μ-XRD and μ-CT. Th-aggregates are made of low-density mineral particles with high density Th-containing inclusions. Size and abundance of Th/REE-containing particles are important inputs for exposure studies and mining viability assessment. Presence of particles affects the environmental behaviour of Th and progeny upon human and environmental-driven weathering.