Several important international scientific organizations have designated radon as a carcinogenic and serious health problem. As a chemically inert gas, it is easily released from soil, building materials, and water, to emanate to the atmosphere. Since 1992, Laboratory for Nuclear Physics of the Department of Physics, Faculty of Sciences in Novi Sad has been involved in measurements of radon concentration in air, using several different techniques. Last year, systematic radon measurements in drinking waters began, too. The work presented here gives a survey and discussion of the results of the both series of measurements.

The correlation between activity concentrations of some natural radionuclides ((238)U, (226)Ra, (232)Th, (40)K) measured in soil and in sediment taken from the Danube River and nearby irrigation channels was studied. The soil samples were collected from the northern part of Serbia and the sediment from the Serbian part of the Danube River and from the surrounding irrigation channels. The correlation between (238)U and other natural radionuclides in irrigation channel sediments was not as good as in the Danube. One of the possible explanations for this weak correlation can be the different chemical dynamics of (238)U in the irrigation channel sediment or changes of the (238)U activity concentration in irrigation channel sediment due to some human activities. The evaluation of ratios of activity concentrations of some natural radionuclides could be a more sensitive method for the determination of contaminant, rather than the straightforward analysis of activity concentrations.

The correlation between specific activities of some natural radionuclides (238U, 226Ra, 232Th, 40K) measured in sediment taken from river bottom was studied. The sediment was taken from the Serbian part of the Danube River. Good correlation between some of the isotopes is observed, so that their specific activity ratios are spread over a lower range than specific activities themselves. This suggests that evaluation of specific activity ratios of some natural radionuclides could be a more sensitive method for the determination of increased levels of some of them than the straightforward analysis of specific activities.

The results of indoor radon survey in the South-Pannonian Province Vojvodina (Serbia and Montenegro) are presented. The sampling strategy was oriented towards suburban and urban regions in the Province. For the dwellings typical for such regions the geometric mean annual radon activity concentration of 76.1 Bq m(-3) is measured (1000 measurements). This result leads to the annual dose estimate of 4.3 mSv y(-1), which is above the recommended action limit of ICRP. For urban dwellings in Novi Sad (the Province capital), the annual mean value of 54 Bq m(-3) (220 measurements) is obtained. By comparison of these two results it is concluded that radon surveys based on measurements in urban environment may seriously underestimate the radon-related health risk. The elevated radon levels could not be explained by elevated uranium levels of surface soil.

The features of the ground located gamma ray spectrometer shielded passively with 12 cm of lead and actively by five 0.5m x 0.5m x 0.05m plastic veto shields are described. The detector mass related background was 0.345 C/kg s. The 511 keV annihilation line was reduced by the factor of 7 by the anticoincidence gate. It is shown that the plastic shields increase the neutron capture gamma line intensities due to neutron thermalization.

Several important international scientific organizations have designated radon as a carcinogenic and serious health problem. As a chemically inert gas, it is easily released from soil, building materials, and water, to emanate to the atmosphere. Since 1992, Laboratory for Nuclear Physics of the Department of Physics, Faculty of Sciences in Novi Sad has been involved in measurements of radon concentration in air, using several different techniques. Last year, systematic radon measurements in drinking waters began, too. The work presented here gives a survey and discussion of the results of the both series of measurements.

Several important international scientific organizations have designated radon as a carcinogenic and serious health problem. As a chemically inert gas, it is easily released from soil, building materials, and water, to emanate to the atmosphere. Since 1992, Laboratory for Nuclear Physics of the Department of Physics, Faculty of Sciences in Novi Sad has been involved in measurements of radon concentration in air, using several different techniques. Last year, systematic radon measurements in drinking waters began, too. The work presented here gives a survey and discussion of the results of the both series of measurements.

The Bega canal is one among many heavily polluted canals in Vojvodina (the northern province of Serbia and Montenegro). In the framework of the revitalization of this canal, the radionuclide content of the sediment was investigated in order to support the safe deposition after excavation. It was found that, in comparison with the Danube sediment and Vojvodina soil, the Bega sediment is contaminated with (238)U and (137)Cs. The origin of this contamination is discussed. No traces of contamination by nuclear power plants in the region were found, while the presence of technologically enhanced, natural occurring radioactive materials (TENORM) was proved.

When the issue of depleted uranium (DU) presence in the environment emerged, methods for the analytical discrimination of DU against natural uranium had to be developed. We present here a simple gamma-spectrometric method, based on the U-238-Ra-226 activity (non) equilibrium. Preliminary calculations that are still under way lead to the result that the lower limit of detection of DU is about 10 Bq kg(-1) for a 50 ks measurement and thus the method is appropriate for the determination of small amounts (approximate to 100 Bq kg(-1)) of DU in environmental samples. The method is tested on about 90 soil samples. (c) 2005 Elsevier Ltd. All rights reserved.

Recent results on 238U/234Th disequilibria in marine studies seriously challenge the possibility of the prompt gamma-ray spectroscopic determination of 238U activity concentration in environmental samples from the gamma-ray lines of the first daughter of 238U, the nucleus 234Th. In this paper we present the results of the gamma-ray spectrometric measurements of 234Th, which were repeated using the same soil and sediment samples at least one year after the first measurement. We did not find any indication of Th activity variation due to 238U/234Th disequilibria. All the obtained results prove that the 238U and depleted uranium determination in soil and sediment samples using 234Th gamma-ray lines introduces at most a systematic error of 3% into the obtained results.

Radon is a naturally occurring radioactive gas. Radon is the alpha emitter and decays to short-lived daughters (Po, Pb, Bi and Po). Radon partially decays in material where it has been generated and partially moves rapidly by concentration-driven diffusion into the open air. The presence of determined radon activity concentration in the atmosphere is the natural contamination. Sources of radon in flats are: soil under and round the object, building’s material and water and gas used in household. Radon is entering the home by emanation from walls, floor and ceiling, through underlying soil and from things and materials that are in the room. Underlying soil is the main source of indoor radon. However, building’s materials also may contribute to elevated indoor radon concentration, especially in combination with low ventilation. In this paper the results of the first radon mapping in Vojvodina are presented Indoor radon activity concentration in air has been measured at the whole area of the province Vojvodina (on about 1000 locations) by plastic track detectors CR-39. On the base of the obtained results, the average indoor activity concentrations of Rn (AM) for individual municipalities and for the whole province of Vojvodina were estimated. Almost 20% of the measurements are over the 200 Bq/m and 4% of the measurements are significantly elevated indoor radon concentrations. The dependence of indoor radon on the location and type of the houses and flats is discussed. Indoor radon activity concentration in air has been measured in Novi Sad in about 200 houses and flats. By measuring gamma-activity of radon daughters, radon activity concentration was determined to be 50 Bq/m.

The widespread public belief that during the bombardment of Vojvodina (Yugoslavia) this region was contaminated by depleted uranium has recently raised public concern with respect to the potential contamination of agricultural products due to soil radioactivity. Based on the gamma-spectrometric analysis of 50 soil samples taken from the region of Vojvodina we concluded that there is no increase of radioactivity that could endanger the food production. Taking into account the transfer factors of 137Cs to plants, the measured activity concentrations of this isotope should not endanger the health safety of the produced food. No traces of depleted uranium have been found. The natural radioactivity levels are compared with the results form other countries.

When the issue of depleted uranium (DU) presence in the environment emerged, methods for analytical discrimination of DU against natural uranium should be developed. We present here a simple gamma-spectrometric method, based on the 238U–226Ra activity (non) equilibrium. The detection limit of the method for DU is of the order of magnitude of 10 Bq/kg (for about 50 ks counting), thus the method is appropriate for the determination of small amounts (≈100 Bq/kg) of DU in environmental samples. The method is tested on about 90 soil samples.

The soil of Vojvodina is subject to radioactive contamination from a number of sources, reactors of nuclear power plants in the South Europe region and use of phosphate fertilizers with high uranium concentration. The results of radiological control in agricultural soil in Vojvodina region are presented in this paper. Based on gamma-spectrometric analysis of 50 soil samples taken from the region of Vojvodina one can conclude that there is no increase of radioactivity that could endanger the food production. Introduction The results of measurements of radionuclides activity concentration in the agricultural soil in the Vojvodina region are presented in this paper. The soil of Vojvodina may contain to radioactive contaminants from a number of sources. First of all, these are the nuclear power plants in the South East Europe region that could contaminate this region through the release of radionuclides into air and water. The use of phosphate fertilizers with high uranium concentration may also cause a gradual increase of the uranium series activity concentration in soil (1). Generally, the all soil samples taken from all location do not show increasing radioactivity which will be endanger the food production. The measured values of Cs activity, using the transfer factor of this isotope into plants, should not endanger the health safety of food production. Methods The soil samples were dried at 105°C to constant mass and transferred to sample holders. Gammaspectrometric measurements were performed with an high-resolution HPGe gamma-spectrometer made by ORTEC. The nominal detector efficiency exceeds 36%, while the resolution is less than 1.9 keV. The detector has an increased energy range of measurement (GMX-type) such that it can detect also low-energy γand X-radiation. The metallic parts of the detector were made of materials tested for high radiopurity. The detector was placed in a special low background protection chamber with iron walls 25 cm thick. The chamber is made of pre WW II cast iron, so that it does not contain admixtures of man-made radioactivity thereby reducing the background radiation level for about 1000 times. The spectra were led through the preamplifier-amplifier chain (the latter of CANBERRA-type) to the CANBERRA Series 35+ multi channel analyzer with two analog-to-digital converters, and with a memory containing 8192 channels. The multi channel analyzer is directly connected to a personal computer where the spectra were processed and stored. A modified version of the SAMPO program was used to process the spectra, in such a way that, besides the identified gamma-lines, it always presented spectral intensities of 20 selected isotopes. The samples were measured in cylindrical geometry, placed in sample containers with 67 mm diameter and 62 mm height. The detection efficiency for this geometry was determined with primary calibration point sources made by AMERSHAM, with calibrated voluminous sources made by NBS and OMH, as well as with a phosphate-ore sample of known activity concentration. The consistency of the calibration results was checked with a modified version of the SOLANG computer program. Typical measurement time was 80 ks. The measurement uncertainties were presented at the 95% confidence level, what means that the probability for obtaining a result laying outside the presented limits in a repeated measurement of the same sample is less than 5%. Activity concentrations of fission and corrosion products (except Cs) were below the detection limits. Therefore in the final results only the activity concentrations of Cs, the natural radioactive series of U and Th, and the natural radionuclide K are presented. A special procedure developed in the Novi Sad laboratory enables the determination of U activity concentration from gamma-lines of the first progeny of this radionuclide, Th. Besides the U activity concentration determined in this way, the activity concentrations of the Ra member of the uranium series are also presented. The comparison of these two measurements provides indication on the presence of depleted uranium because in materials contaminated with depleted uranium the equilibrium ratio of uranium to radium is substantially disturbed (2). Results Activity concentrations of all measured radionuclides, except Cs, are below the detection limit. The radionuclide Cs is present in all soil samples. This radionuclide originates from the accident of the nuclear power plant ‘Lenin’ in Chernobyl in 1986. Due to the long half-life of this radionuclide of 30 y, it will be relocated, washed out and redistributed, but it will be present for a long time in the Vojvodina ecosystem. The large standard deviation and the large difference between the minimum and maximum Cs activity concentrations show typical features of a man-made contaminant (3). In Table 1 are present the measured activity concentration for radionuclides in soil under corn and wheat. Table 1. Activity concentration of radionuclides in soil under corn and wheat Radio nuclide Soil 1 Elan P1 Soil 2 Elan P2 Soil 3 Elan P3 Soil 4 ElanT4 Soil 5 Elan T939 Soil 6 Skorenovac P1 Soil 7 Skorenovac 13 Soil 8 Skorenovac 1a A[Bq/kg] Se <0.17 <0.6 <0.6 <0.4 <0.29 <0.23 <0.18 <0.24 Ce <1.7 <2.3 <2.1 <2.3 <2.0 <1.3 <1.6 <3.0 Ce <0.29 <0.8 <1.0 <0.7 <0.5 <0.10 <0.5 <0.6 Sb <0.9 <0.9 <1.0 <0.5 <1.6 <0.8 <0.6 <0.6 Be <2.3 <3 <3 <4 <4 3.0±2.5 <4.4 <2.5 Ru <0.3 <0.6 <0.4 <0.3 <0.6 <0.26 <0.3 <0.57 Cs <0.5 <0.5 <0.7 <0.17 <0.10 <0.21 <0.16 <0.25 Sb <0.27 <0.9 <0.4 <0.7 <0.6 <0.22 <0.25 <0.16 Ru <2.8 <3 <2.9 <9 <7 <5 <2.5 <2.3 Ag <0.43 <0.14 <0.16 <0.28 <0.02 <0.25 <0.06 <0.34 Cs 7.8±1.2 7.9±1.0 7.9±1.0 10.6±1.5 8.5±1.0 54±4 30.7±1.5 47.6±1.9 Zr <0.4 <0.9 <0.4 <0.5 <0.7 <0.27 <0.5 <0.6 Nb <0.5 <0.6 <0.5 <0.4 <0.7 <0.3 <0.6 <0.09 Co <0.4 <0.4 <0.6 <0.4 <0.4 <0.3 <0.26 <0.23 Tb <1.6 <1.9 <1.3 <2.2 <2.9 <1.2 <1.5 <1.5 Co <0.28 <0.4±0.4 <1.0 <0.29 <0.4 <0.29 <0.22 <0.21 U 37±17 50±26 84±28 70±40 40±30 40±20 80±29 45±17 Ra 40.4±1.7 41.5±1.9 39.2±2.2 49±3 46±3 30±3 31.9±1.6 28.5±1.1 Th 46.7±2.5 46.1±2.5 43.6±2.6 57±3 57±6 49±5 54.7±2.5 44.0±2.2 K 510±30 500±30 480±40 571±28 588±29 601±27 660±30 513±26 As can be conclude from Table 1., the activity concentration of all radionuclides, except from Cs are under detection limit. The average values (with standard deviations) and the minimum and maximum values of activity concentrations of detected radionuclide in soil under corn and wheat are presented in Table 1a. The highest values of Cs activity concentrations are in the location: Skorenovac P1, 13 and 1a. However, all measured activity concentrations are convenience for growing of corn and wheat. Measured values of acitvity concentration of radionuclides for soil under soya bean and sunflower are presented in Table 2. Tabele 1a. The average values (with standard deviations) and the minimum and maximum values of activity concentrations of detected radionuclides in soil under corn and wheat Radionuclide Ās [Bq/kg] σ Ās [Bq/kg] As (min) [Bq/kg] As(max) [Bq/kg] Cs 22 20 7.8 54 U 56 19 37 84 Ra 38 8 28.5 49 Th 50 6 43.6 57 K 553 62 480 601 Table 2. Activity concentration of radionuclides in soil under soya bean and sunflower Radio nuclide Soil 1 Karavuko vo P-1 Soil 2 Karavuko vo P-2 Soil 3 Bečej P1 Soil 4 Bečej P2 Soil 5 Karavukovo peskuša Soil 6 Karavukovo kanalčići Soil 7 Bečej T134 Soil 8 Bečej T-140 A[Bq/kg] Se <0.20 <0.18 <0.4 <0.5 <0.19 <0.33 <0.25 <0.21 Ce <1.8 <1.3 <2.3 <1.9 <1.6 <1.4 <1.5 <1.2 Ce <0.16 <0.3 <0.4 <0.7 <0.5 <10 <0.4 <0.50 Sb <0.8 <1.1 <0.9 <1.1 <1.31 <0.9 <0.6 <0.7 Be <3.0 <2.2 <3 <5 <5 <2.5 <3.6 <1.8 Ru <0.21 <0.37 <0.7 <0.3 <0.5 <0.47 <0.24 <0.19 Cs <0.4 <0.25 <0.4 <1.1 <0.4 <0.22 <0.07 <0.7 Sb <0.30 <2.5 <0.4 <0.5 <0.8 <0.4 <0.36 <0.4 Ru <2.1 <2.9 <3 <3 <3 <2.1 <2.6 <2.7 Ag <0.29 <0.05 <0.4 <0.34 <0.46 <0.16 <0.28 <0.43 Cs 4.2±0.5 5.0±1.2 8.8±1.0 11.1±1.4 5.3±0.6 5.1±1.4 10.9±0.9 10.9±1.0 Zr <0.7 <0.4 <1.1 <0.4 <0.4 <0.8 <0. <0.5 Nb <0.24 <0.08 <0.7 <0.08 <0.5 <0.37 <0.34 <0.27 Co <0.27 <0.4 <0.4 <0.4 <0.3 <0.23 <0.22 <0.22 Tb <0.7 <1.0 <2.1 <1.6 <1.2 <0.8 <0.7 <0.7 Co <0.20 <0.21 <0.3 <0.27 <0.25 <0.19 <0.20 <0.19 U 42±15 34±10 53±25 36±21 70±30 40±21 57±20 54±20 Ra 38.3±2.7 42±4 40.5±2.4 47±4 39.9±2.0 38±4 41.5±1.4 46.5±2.5 Th 40.8±2.2 47.3±2.9 46±3 48±4 38.5±2.0 41±3 44.1±2.1 53±5 K 577±29 581±24 520±40 560±40 560±40 576±25 511±27 586±23 As can conclude from Table 2., the activity concentration of all radionuclides are under detection limit. The average values (with standard deviations) and the minimum and maximum values of activity concentrations of detected radionuclide in soil with soya bean and sunflower are presented in Table 2a. Tabele 2a. The average values (with standard deviations) and the minimum and maximum values of activity concentrations of detected radionuclides in soil under soya bean and sunflower radionuclide Ās [Bq/kg] σ Ās [Bq/kg] As (min) [Bq/kg] As(max) [Bq/kg] Cs 7 3 4.2 11.1 U 48 12 34 70 Ra 42 3 38 46.5 Th 45 5 38.5 47.3 K 559 28 511 586 All location from Table 2, from the radioactivity wiev, are convenience for growing of soya bean and sunflower. Measured values of acitvity concentration of radionuclides for soil under vegetables are presented in Table 3. Table 3. Activity concentration in soil under vegetable Radio nuclid e Soil 1-BAG B. Gradište T21 Soil 2 BAG B. Gradište -T20 Soil 3-BAG B. GradišteT5/1 Soil 4-BAG B. Gradište T5/2 Soil 5-BAG B. Gradište T4 Soil 6-BAG B. Gradište T-6 Soil 7-BAG B. Gradište T-20 Soil 8BAG B. Gradište T-9 A[Bq/kg] Se <0.27 <0.23 <0.24 <0.13 <0.20 <0.4 <0.30 <0.21 Ce <1.5 <1.6 <1.3 <2.0 <2.0 <1.8 <1.5 <1.3 Ce <0.3 <0.20 <0.7 <0.5 <0.5 <0.9 <0.4 <0.5 Sb <0.7 <0.9 <0.7 <0.7 <1.8 <1.1 <1.0 <0.8 Be <2.9 <3.5 <3.4 <2.3 <5 <2.5 <2.4 <2.9 Ru <0.25 <0.32 <0.22 <0.29 <0.4 <0.3 <0.28 <0.24 Cs <0.16 <0.6 <0.3 <0.22 <0.6 <0.6 <0.22 <0.8 Sb <0.20 <0.4 <0.36 <0.49 <0.5 <1.2 <0.33 <0.6 Ru <2.0 <2.0 <2.1 <2.5 <4 <4 <2.3 <2.2 Ag <0.29 <0.3 <0.18 <0.06 <0.47 <0.3 <0.21 <0.13 Cs 8.9±0.8 12.6±1.