Activity concentrations of ²³⁸U and ²³²Th in soils and beach sands of Montenegro were analyzed to evaluate their correlations, as well as absorbed dose rates in air coming from these two natural radionuclides. The analysis was based on the data obtained in the previous period using in situ gamma spectrometry and standard laboratory HPGe spectrometry. This paper is focused on 20 sand points at the beaches along the Coast of Montenegro, 42 soil points at the territory of entire Montenegro, and additional 12 soil points at the territory of Nikšić – the second largest town in the country, having a complex geological base. Uranium-238 in soil was found to range from 7 to 166 Bq/kg with an average of 29.3 Bq/kg (Montenegro) and from 39.7 to 112 Bq/kg with an average 59.5 Bq/kg (Nikšić), as ²³²Th ranged from 9.3 to 74 Bq/kg with an average of 23.7 Bq/kg (Montenegro) and from 33.9 to 78.6 Bq/kg with an average of 54.4 Bq/kg (Nikšić). Normality of the radionuclide activity distributions is tested by the Q-Q plots and Kolmogorov-Smirnov and Shapiro-Wilk tests, whilst the linear regression analysis showed that 64.8% of the variation in ²³²Th activity concentration in soils of Montenegro could be explained by ²³⁸U as a predictor. The ²³²Th and ²³⁸U activity concentrations in soil at the entire Montenegro territory are found to be positively correlated (Pearson correlation coefficient: r = 0.805), but not in the Nikšić soil, where statistically significant correlation is found for ²³²Th and ²²⁶Ra (r = 0.856). Very strong positive correlation between ²³²Th and ⁴⁰K was observed for beach sands, where the ²³⁸U (and ²²⁶Ra), ²³²Th and ⁴⁰K activity ranged up to 16 Bq/kg, 16.6 Bq/kg and 305 Bq/kg, respectively. Absorbed dose rate in air coming from ²³⁸U in soil has average values 13.5 and 27.5 nGy/h for Montenegro and Nikšić, respectively, and that coming from ²³²Th – 14.3 and 32.9 nGy/h, respectively. The dose rates from ²³⁸U and ²³²Th in beach sands are lower, not exceeding 7.4 nGy/h (²³⁸U) and 10 nGy/h (²³²Th).

1. Sources and effects of ionizing radiation, Annex B, UNSCEAR 2000 Report to the General Assembly with Scientific Annexes, UNSCEAR, New York (NY), USA, 2000.
2. Sources and effects of ionizing radiation, Annex B, UNSCEAR 2008 Report to the General Assembly with Scientific Annexes, UNSCEAR, New York (NY), USA, 2010.
3. V. A. Pulhani, S. Dafauti, A. G. Hegde, R. M. Sharma, U. C. Mishra, “Uptake and distribution of natural radioactivity in wheat plants from soil,” J. Environ. Radioact., vol. 79, no. 3, pp. 331 – 346, Nov. 2005.
   DOI: 10.1016/j.jenvrad.2004.08.007
   PMid: 15607519
4. M. Brai et al., “Correlation of radioactivity measurements, air kerma rates and geological features of Sicily,” Radiat. Meas., vol. 41, no. 4, pp. 461 – 470, Apr. 2006.
   DOI: 10.1016/j.radmeas.2005.09.004
5. A. Navas, J. Soto, J. Machin, “238U, 226Ra, 210Pb, 232Th and 40K activities in soil profiles of the Flysch sector (Central Spanish Pyrenees),” Appl. Radiat. Isot., vol. 57, no. 4, pp. 579 – 589, Oct. 2002.
   DOI: 10.1016/S0969-8043(02)00131-8
   PMid: 12361338
6. П. Вукотић и др., Фон гама-зрачења у Црној Гори (1993-1995), Међународни научни центар за екологију и здравље човјека МЕНЕКО, Подгорица, Црна Гора, 1996.
   (P. Vukotić et al., Background gamma-radiation in Montenegro (1993-1995), International Scientific Center for Ecology and Human Health MENEKO, Podgorica, Montenegro, 1996.)
7. P. Vukotić et al., “Background gamma-radiation in Montenegro,” in Proc. IRPA Reg. Symp. Radat. Prot. in Neighbouring Countries of Central Europe, Prague, Czech Republic, Sep. 1997, pp. 477 – 479.
8. P. Vukotić et al., “Radioactivity on the Montenegrin coast, Yugoslavia,” J. Radioanal. Nucl. Chem., vol. 235, no. 1 – 2, pp. 151 – 157, Sep. 1998.
   DOI: 10.1007/BF02385954
9. N. A. Chieco, The Procedures Manual of the Environmental Measurements Laboratory, 28th ed., U.S. Department of Energy, New York (NY), USA, 1997.
10. N. M. Antovic, N. Svrkota, I. Antovic, “Measuring 226Ra and 232Th activity in soil and vegetation samples using a method of double γ-coincidences,” J. Radioanal. Nucl. Chem., vol. 283, no. 2, pp. 313 – 318, Feb. 2010.
    DOI: 10.1007/s10967-009-0376-0
11. N. M. Antovic, N. Svrkota, I. Antovic, V. Popovic, P. Vukotic, “Measuring 137Cs, 40K and decay products of 226Ra and 232Th in samples of different nature by a multidetector spectrometer,” J. Radioanal. Nucl. Chem., vol. 290, no. 1, pp. 81 – 88, Oct. 2011.
    DOI: 10.1007/s10967-011-1136-5
12. N. M. Antovic, N. Svrkota, I. Antovic, “Radiological impacts of natural radioactivity from soil in Montenegro,” Radiat. Prot. Dosim., vol. 148, no. 3, pp. 310 – 317, Feb. 2012.
    DOI: 10.1093/rpd/ncr087
    PMid: 21498861
13. N. M. Antović, N. R. Svrkota, D. S. Bošković, I. M. Antović, “Radioactivity in soil from Mojkovac, Montenegro, and assessment of radiological and cancer risk,” Nucl. Technol. Radiat., vol. 27, no. 1, pp. 57 – 63, Mar. 2012.
    DOI: 10.2298/NTRP1201057A
14. N. M. Antović et al., “Radioactivity impact assessment of Nikšić region in Montenegro,” J. Radioanal. Nucl. Chem., vol. 302, no. 2, pp. 831 – 836, Nov. 2014.
    DOI: 10.1007/s10967-014-3254-3
15. Н. Свркота, Н. Антоновић, Р. Жижић, Р. Зекић, “238U и тешки метали у земљишту Никшића, Црна Гора,” у Зборник XXVIII симпозијума Друштва за заштиту од зрачења Србије и Црне Горе, Вршац, Србија, 2015, стр. 148 – 154.
    (N. Svrkota, N. Antonovic, R. Zizic, R. Zekic, “238U and heavy metals in soils of Nikšić, Montenegro,” in Proc. XXVIII Symp. Soc. Radiat. Prot. Serbia and Montenegro, Vršac, Serbia, 2015, pp. 148 – 154.)
16. N. M. Antovic, P. Vukotic, N. Svrkota, S. K. Andrukhovich, “First measurements of 238Pu and 238Pu/137Cs activity ratio in Montenegro soil,” J. Radioanal. Nucl. Chem., vol. 293, no. 1, pp. 299 – 302, Jul. 2012.
    DOI: 10.1007/s10967-012-1661-x
17. N. M. Antovic, P. Vukotic, N. Svrkota, S. K. Andrukhovich, “Pu-239+240 and Cs-137 in Montenegro soil: their correlation and origin,” J. Environ. Radioact., vol. 110, pp. 90 – 97, Aug. 2012.
    DOI: 10.1016/j.jenvrad.2012.02.001
    PMid: 22445877
18. N. M. Antović, N. R. Svrkota, “Evaluation of radioactivity in Montenegro soil using a statistical approach,” in Proc. Int. Conf. Radiation Applications (RAP 2019), Belgrade, Serbia, Sept. 2019, pp. 90 – 95.
    DOI: 10.37392/RapProc.2019.18
19. Sources, effects and risks of ionizing radiation, Annex B, UNSCEAR 2024 Report to the General Assembly with Scientific Annexes, UNSCEAR, New York (NY), USA, 2025.
20. M. Krmar, E. Varga, J. Slivka, “Correlations of natural radionuclides in soil with those in sediment from the Danube and nearby irrigation channels,” J. Environ. Radioact., vol. 117, pp. 31 – 35, Mar. 2013.
    DOI: 10.1016/j.jenvrad.2011.12.023
    PMid: 22244685
21. S. Dragović et al., “Lithogenic radionuclides in surface soils of Serbia: Spatial distribution and relation to geological formations,” J. Geochem. Explor., vol. 142, pp. 4 – 10, Jul. 2014.
    DOI: 10.1016/j.gexplo.2013.07.015
22. T. Kovács et al., “Systematic survey of natural radioactivity of soil in Slovenia,” J. Environ. Radioact., vol. 122, pp. 70 – 78, Aug. 2013.
    DOI: 10.1016/j.jenvrad.2013.02.007
    PMid: 23558252
23. N. Antovic, P. Vukotic, R. Zekic, R. Ilic, “Indoor radon concentrations in the town of Niksic, Montenegro,” Radiat. Prot. Dosim., vol. 124, no. 4, pp. 385 – 391, May 2007.
    DOI: 10.1093/rpd/ncm225
    PMid: 17681959
24. N. M. Antovic, N. Svrkota, I. Antovic, R. Svrkota, D. Jancic, “Radioactivity in Montenegro beach sands and assessment of the corresponding environmental risk,” Isot. Environ. Health Stud., vol. 49, no. 2, pp. 153 – 162, Jun. 2013.
    DOI: 10.1080/10256016.2013.734303
    PMid: 23452289
25. Nuclear data/Tables of recommended data, Laboratoire National Henri Becquerel, Buc, France, 2025.
    Retrieved from: lnhb.fr
    Retrieved on: Feb. 9, 2025
26. Q. Wang et al., “Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity,” Ecotoxicol. Environ. Saf., vol. 263, 115210, Sep. 2023.
    DOI: 10.1016/j.ecoenv.2023.115210
    PMid: 37418943
27. M. SureshGandhi et al., “Measurements of natural gamma radiation in beach sediments of north east coast of Tamilnadu, India by gamma ray spectrometry with multivariate statistical approach,” J. Radiat. Res. Appl. Sci., vol. 7, no. 1, pp. 7 – 17, Jan. 2014.
    DOI: 10.1016/j.jrras.2013.11.001