Abstract
There is a significant scarcity of environmental radiological data from the Spanish territories in the North Africa and along the southern Alboran Sea coast. This paper presents the results of environmental radioactivity campaigns conducted between 2010 and 2025 in Melilla to produce a terrestrial gamma radiation map and analyse the distribution of natural radioisotopes (226Ra, 232Th and 40K) and 137Cs in soils. Mean activity concentrations are 22 Bq kg⁻¹ for 226Ra, 24 Bq kg⁻¹ for 232Th, and 305 Bq kg⁻¹ for 40K, all below global medians and Spanish averages. Using these data, a dose model was applied to generate a dose map of the territory. The estimated annual effective dose of 0.23 mSv y⁻¹ is also below the global average, indicating no radiological concern for the population. Due to Melilla’s border location and proximity to the Strait of Gibraltar, a characterization of its beaches was performed to establish a baseline for potential external contamination. Several indices established by international regulatory agencies were calculated to quantify radiological risk in outdoor and indoor environments. Finally, a radon potential exposure map was developed to identify areas where buildings could exceed the 300 Bq m⁻³ reference level set by the Building Technical Code in accordance with Council Directive 2013/59/Euratom.
Data availability
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
Maps throughout this book were created using ArcGIS® software by Esri. ArcGIS® and ArcMap™ are the intellectual property of Esri. All rights reserved. The lithostratigraphic maps were obtained from Cartografía Digital del Mapa Geológico y Continuo de España (GEODE) supplied by Instituto Geológico y Minero de España (IGME).The authors are particularly grateful to Luis Romero, Jose Antonio Hernández, Mª Paz Ojeda, Vicente de Juan and Santiago Cobreros for their continuous strong support in the field sampling campaigns and Eduardo González for his valuable suggestions regarding the statistical analysis of the data.
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J.G. Rubiano conceived the study, wrote the main manuscript text, contributed to the discussion of results and conclusions, and participated in the sampling campaigns. F. Cámara was responsible for writing the geological section and discussing the results. N. Miquel-Armengol prepared the maps using ArcGIS and participated in data analysis. C. Briones developed the radon risk map section and revised the English language and bibliographic references. C. León-Navarro and M. Añino participated in the field sampling and in situ measurement campaigns. H. Alonso contributed to the discussion of the results. A. Tejera and P. Martel carried out the gamma spectrometry measurements of the soil samples, wrote the section on beaches, and contributed to the manuscript revision. J.G. Rubiano is the corresponding author.
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Rubiano, J., Cámara, F., Miquel-Armengol, N. et al. Assessment of environmental radioactivity in the City of Melilla. Sci Rep (2026). https://doi.org/10.1038/s41598-026-35980-x
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DOI: https://doi.org/10.1038/s41598-026-35980-x
