Dragana Popovic

Concentration measurements of 7Be and 137Cs in ground level air in the Belgrade City area

Abstract Concentrations of 7 Be and 137 Cs in ground level air in the city area (Belgrade, central Serbia) were determined in the period from 1991–1996. The average monthly concentrations of 7 Be in ground level air were in the range of 2–7 mBq/m 3 with pronounced one or two maxima in summer or early fall and a minimum in winter. The average air concentrations for 137 Cs were from 0.5–8.5 × 10−5 Bq/m 3 , with a spread maximum in the spring-summer period and a pronounced maximum during the winter. A general increase in 7 Be and 137 Cs concentrations during 1993 was recorded. The maximum seasonal indices were 1.3 for 7 Be (summers) and 2.7 (late springs and early summers) and 3.4 (winters) for 137 Cs. No correlation with the amount of precipitation and 137 Cs concentrations in air was determined, while the washout effect of rainfalls seems to be more closely related with variations in 7 Be concentrations.

Radioactivity monitoring in ground level air in Belgrade urban area

Concentrations of beryllium-7 ((7)Be), lead-210 ((210)Pb) and caesium-137 ((137)Cs) were measured at two sites in the city of Belgrade (Serbia). One monitoring site was located in the central city area with heavy traffic and the other within the Institute of Nuclear Sciences Vinca, in the suburbs. Presented data cover the period 2004-9. Activity of the radionuclides was determined on an HPGe detector (Canberra, relative efficiency 23 %) by standard gamma spectrometry. Activities of (7)Be and (210)Pb exhibit a similar seasonal pattern. The mean monthly concentrations of (7)Be did not exceed 7 mBq m(-3). The maxima are correlated with the seasonal increase in temperature, whereas the minima are linearly correlated with the amount of precipitation. The activity of (210)Pb was below 0.9 mBq m(-3). The activities of both radionuclides were very low in winters and were largely affected by precipitation and snow coverage. Concentrations of (137)Cs were mainly below the limit of detection.

Activity variations and concentration factors for natural radionuclides in a “soil-plant-honey” system

Abstract The activity of natural radionuclides (226Ra, 238U, 235U, 232Th, and 40K) was measured in soils, meadow flowers, and honey from a mountain region in West Serbia. No statistically significant differences in the contents of natural radionuclides in soil or meadow flora from different soils (shale or limestone) were obtained, although concentrations were generally higher in shale soils than in soils mainly composed of limestone rocks. Activity of 226Ra, 238U, and 235U in plants was below minimal detectable concentrations (0.4 - 0.1 Bq/kg). The content of 232Th was higher in meadow flora from shale soils. For 40K, there were no significant differences in its concentrations in plants from different soils. The activity of natural radionuclides in honey did not depend on the type of soil or meadow flora, but the variations for 238U and 235U concentrations were high. Concentration factors for “soil-honey” phase were in the range 0.01-0.07, while for “soil-plant” and “plant-honey” phase they could be calculated only for 232Th and 40K and were in the range 0.1–3.0 and 0.09-0.02, respectively.

Leaves of higher plants as biomonitors of radionuclides (137Cs, 40K, 210Pb and 7Be) in urban air

Leaves of linden (Tilia tomentosa L. and Tilia cordata Mill.) and horse chestnut (Aesculus hippocastanum L.) were analysed as biomonitors of radionuclides in urban air. Samples of soils, leaves and aerosols were collected in Belgrade, Serbia. Activities of 137Cs, 40K, 210Pb and 7Be in the samples were measured on an HPGe detector by standard gamma spectrometry. “Soil-to-leaves” transfer factors were calculated. Student’s t test and linear Pearson correlation coefficients were used for statistical analysis. Differences in local conditions at the sampling sites were not significant, and the mechanisms of the radionuclides’ accumulation in both plant species are similar. Ceasium-137 was detected in some of the leaf samples only. Transfer factors for 137Cs and 40K were (0.03–0.08) and 1.3, respectively. The concentrations of 210Pb and 7Be in leaves were higher in autumn than in spring, and there were some similarities in their seasonal patterns in leaves and in air. Weak to medium correlation was obtained for the 210Pb and 7Be activities in leaves and aerosols. Large positive correlation was obtained for the 210Pb activities in linden leaves and the mean activity in aerosols for the preceding months. Different primary modes of radionuclides accumulation in leaves were observed. Since large positive correlation was obtained for the 210Pb activity in linden leaves and the mean in aerosols for the preceding months, mature linden leaves could be used as biomonitors of recent 210Pb activity in air.

Trace Elements and Radionuclides in Urban Air Monitored by Moss and Tree Leaves

In urban areas, air quality is strongly influenced by numerous anthropogenic activities. High population density, heavy traffic and domestic heating in winters in the centre, and various industrial activities at the outskirts, influence atmospheric concentrations of trace elements and radionuclides. Consequently, large population is exposed to possible adverse effects arising from the altered urban air composition. Therefore, air quality monitoring has become one of the standard quality control procedures in urban areas.

Air Radioactivity Monitoring in Serbia

Today radioactivity monitoring in the environment is required not only around sites where the significant amounts of radioactive material are used or stored, but in a number of other processes as land remediation or decommissioning of nuclear plants. Since the end of the 20th century there has been an increasing awareness of the so-called technologically enhanced natural radioactivity and the need for its monitoring in a wide range of nonnuclear industries including oil and gas extraction, ceramic and glass industries, production of phosphoric acid, production of different phosphoric fertilizers and other chemical industries. Coal electric power plants as significant sources of ashes and other contaminants are included, too. Contrary to nuclear facilities or radioactive waste control these processes require measuring radionuclides at very low levels of radioactivity. This demands specific methodology and instrumentation and responding to the very real economic importance of classifying waste products from decommissioning and remediation processes. However, natural or man made, waste or industrial, environmental radioactivity monitoring requires adequate equipment calibrated in the full range of radionuclides likely to be encountered, as well as trained and experienced personnel. It is the task of national metrological institutions to provide radioactive reference materials and standards for calibration as pure isotopes, mixtures of isotopes or reference materials for particular applications and to supervise the processes of quality control and quality assurance. Besides primary standards and reference materials national metrological institutions should provide laboratory proficiency testing exercises to support radioactivity measurements within academic, industrial or research laboratories (Spasic, 1984; Spasic, 1985; Spasic, 1987a; Spasic et al. 1987).

Ground Level Air Radioactivity Monitoring in Belgrade Urban Area

The paper presents the preliminary results of determination of natural and anthropogenic radionuclides ( 7 Be, 210 Pb, 235 U, 238 U, 232 Th, 40 K, 137 Cs) in ground level air, soils and tree leaves in Belgrade urban area. Activities of the radionuclides were determined on an HPGe detector (ORTEC, relative efficiency 23%) by standard gamma spectrometry. The content of the radionuclides in soils were within the average values for the region and the 235 U/ 238 U ratio confirmed the natural origin of uranium. The average radionuclides concentrations in ground level air in the urban areas were within the range of the values obtained in the long-term study on the ground level air radioactivity in the city area, exhibiting in general the same seasonal variations pattern. The highest concentrations of 210 Pb in aerosols were measured in the very center of the city. There were no significant differences in the content of 7 Be and 40 K in leaves, whereas further investigations are needed to confirm the differences in the content of 137 Cs and 210 Pb due to the plant morphology (horse chestnut, linden) or seasonal variations. The study is in progress.

Actions to Improve Physics Education in Serbia and Montenegro and to Celebrate the World Year of Physics

Physicists in Serbia and Montenegro (SRM), both men and women, are not satisfied with the status of physics in SRM. The number of students who choose to study physics is decreasing. The percentage of physics graduates who are leaving the country is still very large (Figure 1). The presence and the role of physicists in industry, medicine, health care, economy, environmental protection, and the media is not satisfactory. Funding for research and especially for research infrastructure has increased since 2000; but, because of a long period of conflicts and isolation, many years will pass before we see significant results and effects. Women in SRM are concerned primarily with how to improve the overall status of physics in SRM. In SRM women physicists are not the minority. Many guests from European and other countries have noticed that the distribution of men and women physicists is inverse compared with Western countries, a fact that was recognized at the Fifth General Conference of the Balkan Physical Union, which took place in Serbia in 2003. Women physicists participate in the activities of the Belgrade Women’s Studies Center, such as conferences, international exchanges, and statistical and comparative analysis. An study of the status of women in science and media was done at this Center [1,2]. Here we present the work of women in SRM since the First IUPAP International Conference on Women in Physics to improve physics education and to participate in WYP2005.

Teaching Physics and Biophysics to Veterinary Students and Specialists

Both theory and lab work in physics and biophysics for veterinary students are aimed at giving them the basic scientific and technical knowledge needed in order to understand physiological processes within cells and organisms as a whole, and to acquaint them with the thermodynamic aspects of life and with the principles of physical therapeutic and diagnostic methods as applied to veterinary medicine (Djuric, 1992).