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The results of the gamma-spectrometric measurements in a 16500 ha large region of south-western Serbia, are presented. Activity concentrations of 40K, 137Cs, and 210Pb in different deciduous and evergreen trees in the region are investigated. For all the investigated isotopes, there is a tendency that, on average, the lowest activity concentrations were found in tree stems, then in leaves, while the highest ones were in the soil. Statistical analysis did not show any differences between activity concentrations of leaves and needles, showing that both leaves and needles could be equally well used as a biomonitors.

Various imported building materials commonly used in construction and industry in Serbia were analyzed using gamma spectrometry. Based on the activity concentrations of 226Ra, 232Th, and 40K in the investigated samples, radium equivalent activity, Raeq, absorbed dose rate, D, annual effective dose, DE, and the external hazard index, Hex, were calculated to assess the radiation hazard for people. The Raeq for most of the analyzed samples (416 in total) was lower than the maximum admissible value of 370 Bqkg-1 set in the UNSCEAR report. The absorbed gamma dose rate in air was found to vary from 0.030 mGyh-1 to 1.328 mGyh-1 which in some cases exceeded indoor dose rates in Europe. The obtained values for annual effective dose exceed the limits of 0.41 mSv given in literature for about 5 % of measured samples, while values of Hex were higher than unity for three samples of cement, eight samples of granite, and one sand sample. As a possible source of elevated effective dose, the radon exhalation from building materials was estimated using the parameters given in literature. The internal dose due to 222Rn exhaled from the building material was found to be up to nine times higher than external dose due to 226Ra content in some cases.

The primary aim of this research is the investigation of natural and artificial radioactivity in protected areas of Kopaonik, Vlasina, and Rila Mountains. Soil samples (including lake sediment), drinkable spring water and conifers at mentioned locations of Southeast Europe, are chosen as study objects due to their importance for people and the environment in global. Specific activities of Ra-226, Th-232, K-40, U-238, U-235, Cs-137, Pb-210, and Be-7 are determined using gamma spectrometry and the obtained values compared with literature and mean world values. Risk assessment parameters and the soil-plant transfer factor were determined for Ra-226, K-40, (CS)-C-137, and Pb-210. This is the first radioactivity study of high mountain areas of Vlasina and Kopaonik in Serbia and Rila in Bulgaria and as such a baseline measurement and foundation for future research.

The primary aim of this research is the investigation of natural and artificial radioactivity in protected areas of Kopaonik, Vlasina, and Rila Mountains. Soil samples (including lake sediment), drinkable spring water and conifers at mentioned locations of Southeast Europe, are chosen as study objects due to their importance for people and the environment in global. Specific activities of Ra-226, Th-232, K-40, U-238, U-235, Cs-137, Pb-210, and Be-7 are determined using gamma spectrometry and the obtained values compared with literature and mean world values. Risk assessment parameters and the soil-plant transfer factor were determined for Ra-226, K-40, (CS)-C-137, and Pb-210. This is the first radioactivity study of high mountain areas of Vlasina and Kopaonik in Serbia and Rila in Bulgaria and as such a baseline measurement and foundation for future research.

The aim of the paper was to estimate the values of transfer factors for natural radionuclides (K-40, Ra-226, Th-232, U-235, and U-238) and Cs-137 from soil to plants (cereals: wheat, corn and barley) as important parameters for the agricultures in the selection of the location and the sort of cereals to be planted on. The results presented in this paper refer to the ,,soil -cereals system in the region of Pcinja, Serbia. Total of 9 samples of soil and 7 samples of cereals were measured in the Department of Radiation and Environmental Protection, Irnica Institute of Nuclear Sciences, using three high -purity germanium detectors for gamma spectrometry measurements. In all the samples, transfer factors for Ra-226 are significantly lower than for K-40, but they are all in good agreement with the literature data. On the three investigated locations, the calculated values of transfer factors for K-40 were in the range of 0.144 to 0.392, while in the case of Ra-226, the transfer factors ranged from 0.008 to 0.074. Only one value (0.051) was obtained for transfer factor of Th-232. Specific activities of Cs-137, as well as uranium isotopes, in all the investigated cereal samples, were below minimal detectable activity concentrations. Also, the absorbed dose rate and the annual absorbed dose from the natural radionuclides in the soil, were calculated. The absorbed dose rate ranged from 49-86 nSv/h, while the annual absorbed dose ranged from 0.061-0.105 mSv. The measurements presented in this manuscript are the first to be conducted in the region of Pcinja, thus providing the results that can be used as a baseline for future measurements and monitoring.

Radon testing by using open-faced charcoal canisters is a cheap and fast screening method. Many laboratories perform the sampling and measurements according to the United States Environmental Protection Agency method - EPA 520. According to this method, no corrections for temperature are applied and corrections for humidity are based on canister mass gain. The EPA method is practiced in the Vinca Institute of Nuclear Sciences with recycled canisters. In the course of measurements, it was established that the mass gain of the recycled canisters differs from mass gain measured by Environmental Protection Agency in an active atmosphere. In order to quantify and correct these discrepancies, in the laboratory, canisters were exposed for periods of 3 and 4 days between February 2015 and December 2015. Temperature and humidity were monitored continuously and mass gain measured. No significant correlation between mass gain and temperature was found. Based on Environmental Protection Agency calibration data, functional-dependence of mass gain on humidity was determined, yielding Environmental Protection Agency mass gain curves. The results of mass gain measurements of recycled canisters were plotted against these curves and a discrepancy confirmed. After correcting the independent variable in the curve equation and calculating the corrected mass gain for recycled canisters, the agreement between measured mass gain and Environmental Protection Agency mass gain curves was attained.

This work presents the results of an investigation undertaken to determine the level of natural radioactivity in the traditional building materials used for medieval indoor vaulted constructions in the territory of the central Balkan region. Indoor radiation exposure varies appreciably if it comes from the earth building materials, hence the presence of natural radioisotopes of Ra-226, Th-232, and K-40 in masonry vaulted constructions was analyzed using gamma ray spectrometry. In addition, the internal health hazard index, the absorbed dose rates and the effective annual doses were calculated. The results were then compared both with the reported data from the previous studies concerning the territory of the Balkan Peninsula, as well as with the worldwide values for the materials of historic buildings. The results obtained from the materials examined in this paper all showed the radioactivity levels below the maximum permitted values.

Activities of 7Be and 210Pb were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The 7Be activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the 210Pb activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m3 and 1.3 mBq/m3 for 7Be and 210Pb, respectively. The obtained correlation of the 7Be activity with the number of sun-spots is not statistically significant. Relations of the radionuclides' activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the 7Be activity with temperature and sunshine hours, and the 210Pb activity with atmospheric pressure. The maximum 7Be and 210Pb activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days., Aktivnosti 7Be i 210Pb merene su tokom 2004-2012, u prizemnom sloju atmosfere na dve lokacije u Beogradu. Mesečne specifične aktivnosti određene su standardnom metodom spektrometrije gama zračenja na HPGe detektorima. Aktivnosti radionuklida pokazuju sezonski karakter: 7Be ima maksimum tokom proleća i leta, a minimum zimi, dok 210Pb ima dva maksimuma, tokom jeseni i kasne zime. Na obe lokacije, srednje mesečne aktivnosti 7Be su manje od 9 mBq/m3, dok su za 210Pb manje od 1.3 mBq/m3. Između aktivnosti 7Be i broja sunčevih pega nije nađena statistički značajna korelacija. Relacije između aktivnosti ovih radionuklida i klimatskih parametara (količina padavina, temperatura, relativna vlažnost, oblačnost, broj sunčanih sati i atmosferski pritisak) takođe su ispitane, ali su značajne korelacije dobijene samo za aktivnost 7Be sa temperaturom i brojem sunčanih sati, odnosno za aktivnost 210Pb sa atmosferskim pritiskom. Na osnovu veze između maksimalne aktivnosti po intervalima količine padavina, mogu se razlikovati tri režima spiranja radionuklida iz atmosfere. Tokom sušnih perioda, akumulacija radionuklida u atmosferi uzrokuje njihovu povišenu aktivnost, ali korelacija između aktivnosti i broja uzastopnih suvih dana nije dobijena.

Activities of Be-7 and Pb-210 were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The Be-7 activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the Pb-210 activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m(3) and 1.3 mBq/m(3) for Be-7 and Pb-210, respectively. The obtained correlation of the Be-7 activity with the number of sun-spots is not statistically significant. Relations of the radionuclides activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the Be-7 activity with temperature and sunshine hours, and the Pb-210 activity with atmospheric pressure. The maximum Be-7 and Pb-210 activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days.

A considerable number of primordial radioisotopes are present in almost all the samples extracted from the Earths crust, such as oil, rock, soil or other materials. Their concentrations are often determined by gamma spectrometry. Although the relative concentrations of isotopes often fluctuate within a narrow range, it is not always the case. Some natural materials (such as naturally occurring radioactive material) show unusual activity ratio between U-238 and Th-232, while technologically processed materials (technologically enhanced naturally occurring radioactive material) might also introduce significant disequilibrium hi radioactive chains. Knowing that primordial radioisotopes emit in total more than a thousand gamma and characteristic X-ray photons and that many of them interfere with each other, a question arises whether for some activity ratios commonly used photopeaks become useless for quantitative analysis, due to interferences with other photopeaks. A computer program was developed in order to calculate full energy photon interferences for any chosen photopeak. The calculations are based on the inputs in the form of isotope activities and detector calibration equations and its characteristics are presented in this paper.

To assess the validity of the moss bag monitoring technique in the radioactivity control of ground level urban air, a study on radionuclide contents in moss was performed in the city of Belgrade, Serbia. From May 2006 to May 2007, moss (Sphagnum girgensohni, Dubna, Russia) was exposed to the aero pollution in a location in the central area of the city. The activity of 40K, 210Pb, and 137Cs was measured on an HPGe detector (Canberra, relative efficiency 23%) by standard gamma spectrometry. The activities 245 ± 25 Bq/kg for 40K, 315 ± 34 Bq/kg for 210Pb, and 28 ± 4 Bq/kg for 137Cs are in the range of values reported for the region; the differences are due to the moss species, local climate and measuring technique. Taking into consideration the time of the exposure and appropriate calibration procedure, moss bag biomonitoring could be used as a complementary method for determination of radionuclides in urban air., U cilju utvrđivanja valjanosti tehnike aktivnog monitoringa pomoću mahovina u kontroli radioaktivnosti prizemnog sloja atmosfere, na teritoriji grada Beograda sprovedena je studija sadržaja radionuklida u mahovinama. Od maja 2006. do maja 2007. godine, mahovina (Sphagnum girgensohni, Dubna, Rusija) izlagana je vazdušnom zagađenju na lokaciji u centru grada. Koncentracija aktivnosti 40K, 210Pb i 137Cs merena je HPGe detektorom (Canberra, relativne efikasnosti 23%) metodom standardne gama spektrometrije. Koncentracije aktivnosti od 245 ± ± 25 Bq/kg za 40K, 315 ± 34 Bq/kg za 210Pb i 28 ± 4 Bq/kg za 137Cs spadaju u opseg vrednosti izmerenih u regionu; razlike u rezultatima potiču od vrste mahovine, lokalne klime i tehnike merenja. Uzimajući u obzir vreme izlaganja i pravilnu proceduru kalibracije, aktivni monitoring mahovinama može da se primeni kao komplementarni metod za određivanje koncentracije radionuklida u vazduhu u urbanom području.

Three sets of data covering the 2004-2007 period are examined: two beryllium-7 series and ozone measured in ground level air. The measuring sites are at three different locations in Belgrade, Serbia. The temporal evolution of beryllium-7 and ozone is presented, as well as their mutual correlations. Beryllium-7 data for Belgrade agree well with the results for other locations in the region. The correlation between two beryllium-7 data sets is 0.57. The results for ozone indicate that Belgrade is not a common continental site, as the maximum in ozone distribution is reached in springtime. The overall correlation between beryllium-7 and ozone is good, but varies over different seasons. A large correlation (0.67) is noted between beryllium-7 measured at the site in Vinca, Serbia, and the monthly maximum ozone in autumn. An analysis which assumes the transport of air masses from the stratosphere, along which the only process changing the air mass composition is radioactive decay of beryllium-7, does not conclusively confirm the high correlation between beryllium-7 and ozone in autumn.

Three sets of data covering the 2004-2007 period are examined: two beryllium-7 series and ozone measured in ground level air. The measuring sites are at three different locations in Belgrade, Serbia. The temporal evolution of beryllium-7 and ozone is presented, as well as their mutual correlations. Beryllium-7 data for Belgrade agree well with the results for other locations in the region. The correlation between two beryllium-7 data sets is 0.57. The results for ozone indicate that Belgrade is not a common continental site, as the maximum in ozone distribution is reached in springtime. The overall correlation between beryllium-7 and ozone is good, but varies over different seasons. A large correlation (0.67) is noted between beryllium-7 measured at the site in Vinča, Serbia, and the monthly maximum ozone in autumn. An analysis which assumes the transport of air masses from the stratosphere, along which the only process changing the air mass composition is radioactive decay of beryllium-7, does not conclusively confirm the high correlation between beryllium-7 and ozone in autumn., U periodu od 2004. do 2007. godine na tri lokacije u Beogradu mereni su berilijum-7 i ozon u prizemnom sloju atmosfere. Berilijum-7 meren je u Vinči i Karađorđevom parku, a ozon u Novom Beogradu. Analizirane su sezonske promene koncentracije berilijuma-7 i ozona u vazduhu i njihov međusobni odnos. Dobijene vrednosti za berilijum-7 u Beogradu ne odstupaju od rezultata dobijenih na drugim lokacijama u regionu. Korelacija između dve grupe podataka za berilijum-7 (lokacija Vinča i lokacija Karađorđev park) je 0,57. Dobijeni rezultati za ozon ukazuju da Beograd nije uobičajena kontinentalna lokacija, jer se maksimum distribucije ozona javlja u proleće. Korelacija između berilijuma-7 i ozona tokom čitavog mernog perioda je dobra, ali postoje razlike po godišnjim dobima. Visoka korelacija (0,67) dobijena je tokom jeseni za berilijum-7 (lokacija Vinča) i maksimalne mesečne koncentracije ozona. Visoka korelacija između dobijenih vrednosti za ozon i berilijum-7 u prizemnom sloju atmosfere tokom jesenjih meseci ne može se u potpunosti objasniti samo transportom vazdušnih masa iz stratosfere, pri čemu je jedini proces koji menja sastav vazdušnih masa radioaktivni raspad berilijuma-7.