Surface soil from 47 locations in Montenegro had been previously analyzed for radioactivity due to natural ²²⁶Ra, ²³²Th, ⁴⁰K and man-made ¹³⁷Cs, and showed mean activity concentrations around 41.1, 45.8, 500 and 95.2 Bq/kg, respectively. Discriminant Analysis used in the present study for the classification, with activity concentrations of radionuclides as independent variables and the Montenegro region (South, Center, North) as a grouping variable, showed 76.6% of original grouped cases as correctly classified. The radium equivalent activity, external and internal hazard index showed a mean of 142 Bq/kg, 0.39 and 0.5, respectively. An average external terrestrial gamma absorbed dose rate was found to be 67.5 nGy/h – for natural radionuclides only, and 79.3 nGy/h for natural radionuclides and ¹³⁷Cs. The corresponding annual effective dose showed a mean of 0.08 mSv and around 0.1 mSv, respectively. These hazard indices, together with radionuclide activities, are used in the factor analysis performed with Principal Component Analysis as the extraction method and Varimax with Kaiser Normalization as the rotation method. Two components were extracted. The first one loaded basically on ²³²Th and ²²⁶Ra activity explained ~80.6% of the total variance, while the second component explaining ~12.2% of the total variance is found to be strongly correlated with ¹³⁷Cs and ⁴⁰K activity.

1. Statistical Yearbook of Montenegro 2018, Statistical Office of Montenegro – MONSTAT, Podgorica, Montenegro, 2018.
   Retrieved from: http://monstat.org/userfiles/file/publikacije/godisnjak%202018/GODISNJAK%202018%20PRELOM.pdf
   Retrieved on: Sep. 26, 2019
2. 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
3. N. M. Antović, D. S. Bošković, N. R. Svrkota, I. M. Antović, “Radioactivity in soil from Mojkovac, Montenegro, and assessment of radiological and cancer risk,” Nucl. Technol. Radiat. Prot., vol. 27, no. 1, pp. 57 – 63, Mar. 2012.
   DOI: 10.2298/NTRP1201057A
4. N. M. Аntović et al., “Radioactivity impact assessment of Nikšić region in Montenegro,” J. Rаdioаnаl. Nucl. Chem., vol. 302, no. 2, pp. 831 – 836, Nov. 2014.
   DOI: 10.1007/s10967-014-3254-3
5. N. M. Аntovic, P. Vukotic, N. Svrkotа, S. K. Аndrukhovich, “Pu-239+240 аnd Cs-137 in Montenegro soil: their correlation and origin,” J. Environ. Rаdioаct., vol. 110, pp. 90 – 97, Aug. 2012.
   DOI: 10.1016/j.jenvrad.2012.02.001
   PMid: 22445877
6. Sources and Effects of Ionizing Radiation, Annex B, Rep. A/55/46, UNSCEAR, New York (NY), USA, 2000.
   Retrieved from: https://www.unscear.org/docs/publications/2000/UNSCEAR_2000_Annex-B.pdf
   Retrieved on: Jun. 25, 2016
7. Sources and Effects of Ionizing Radiation, Annex B, Rep. A/63/46, UNSCEAR, New York (NY), USA, 2010.
   Retrieved from: https://www.unscear.org/docs/publications/2008/UNSCEAR_2008_Annex-B-CORR.pdf
   Retrieved on: Feb. 10, 2019
8. Environmental Measurements Laboratory (EML) Procedures Manual, Rep. HASL-300, U.S. Department of Homeland Security, New York (NY), USA, 1997.
   Retrieved from: https://www.hsdl.org/?abstract&did=487142
   Retrieved on: Apr. 2, 2019
9. GammaVision-32 Software User’s Manual, 6th ed., AMETEK Inc. (ORTEC), Oak Ridge (TN), USA, 2003.
   Retrieved from: https://www.ortec-online.com/-/media/ametekortec/manuals/a66-mnl.pdf
   Retrieved on: Feb. 10, 2019
10. Recommended data, Laboratoire National Henri Becquerel, Gif-Sur-Yvette, France, 2017.
    Retrieved from: http://www.nucleide.org/DDEP_WG/DDEPdata.htm
    Retrieved on: Nov. 09, 2018
11. J. Beretka, P. J. Matthew, “Natural radioactivity of Australian building materials, industrial wastes and by-products,” Health Phys., vol. 48, no. 1, pp. 87 – 95, Jan. 1985.
    DOI: 10.1097/00004032-198501000-00007
    PMid: 3967976
12. The Council of European Union. (Dec. 5, 2013). Council Directive 2013/59/EURATOM. Laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom.
    Retrieved from: https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2014:013:0001:0073:EN:PDF
    Retrieved on: Jul. 11, 2019
13. SPSS Statistics version 20, IBM, Armonk (NY), USA, 2011.
    Retrieved from: https://www.ibm.com/support/pages/ibm-spss-statistics-200-release-notes#relnotes__description
    Retrieved on: Aug. 29, 2019
14. N. M. Antovic, N. Svrkota, I. Antovic, R. Svrkota, D. Jančić, “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
15. M. Mirković i dr., “Geološka karta Crne Gore, 1:200.000,”Zavod za geološka istraživanja Crne Gore, Podgorica, Crna Gora, 1985. (M. Mirković et al., “Geological Map of Montenegro, 1:200,000,”Geological Survey of Montenegro, Podgorica, Montenegro, 1985.)
    Retrieved from: https://geozavod.co.me/
    Retrieved on: Jun. 29, 2019