Zavisnost efikasnosti germanijumskih detektora od gustine uzoraka u spektrometriji gama zračenja

The effect of the density of environmental samples on the counting efficiency of Ge detectors used in gamma-spectrometry was studied. The dependence εff(ρ) was determined for two HPGe detectors (relative efficiencies 18% and 20%) using five radioactive standard reference materials (silicone resins, epoxy resin, milk powder, soil) with different matrix densities (0.45-1.22 g/cm3) in Marinelli beakers (V = 500 cm3). The dependence of efficiency vs. density was found to be linear and the regression parameters for energies in the range of 60-2000 keV were determined, too. The effect of variation in density on the counting efficiency of Ge detectors is dominant in the range of lower energies (60-600 keV) and de creases with energies in the higher energy range.Ispitivan je uticaj gustine uzoraka iz životne sredine na efikasnost brojanja germanijumskih detektora u spektrometriji gama zračenja. Zavisnost εff(ρ) određena je za dva HPGe detektora (relativnih efikasnosti 18% i 20%) za različite radioaktivne standardne referentne materijale (silikonske smole epoksi smolu, mleko u prahu, zemlju) različitih gustina (0,45-1,22 g/cm3) u Marineli posudama zapremine V = 500 cm3. Utvrđena je linearna zavisnost efikasnosti brojanja od gustine uzoraka pri čemu su određeni parametri linearne regresije za niz energija iz intervala od 60-2000 keV. Efekt promene gustina na efikasnost brojanja germanijumskih detektora dominantan je u intervalu nižih energija (60-600 keV) i smanjuje se sa porastom energije u intervalu viših energija

NATURALLY OCCURRING RADIONUCLIDES AND BASIC CHARACTERISTICS OF SOIL AND ASH SAMPLES NEARBY COAL–FIRED POWER PLANTS

Deposition of (fly and bottom) ash generated after coal combustion in the coal fired power plants (CFPP) in Serbia is carried out in active and passive lagoons. Ash waste mixed with water is directly transported to the lagoon currently active and the other one is passive in the stage of temporary inactivity for technical consolidation of ash and drainage and subjected to revegetation process using grass–legume mixtures with the purpose of creating plant cover. In order to obtain similarity, samples studied in this work were all taken from the area covered with grass which included: (1) soil close to CFPP (2 km) and (3) ash from the flat area of associated passive lagoon. Investigated sites were four power plants: TE “Kolubara” (TEK), TE “Morava” (TEM), TE “Nikola Tesla” A (Tent A) and B (Tent B). In order to analyse environmental implications of ash deposition in the surrounding area, basic characteristics such as texture, particle size distribution, pH value, organic matter and carbonate content were determined in the soil and ash samples. Simultaneously, 238U, 226Ra, 210Pb and 232Th activity concentrations were measured as it is known that after elimination of the organic component of the coal in the process of combustion naturally occurring radionuclides activity concentrations in the coal ash could be enhanced up to 10 times. Analyses of differences between soil and ash samples collected in this study showed that for one group of soils some changes of physical and chemical characteristics occurred compared to the rest of the soils. These changes were found to be related to the soil texture, percentages of clay size particles and 232Th/226Ra activity concentration ratios

Raspodela pristupačnih sadržaja mikroelemenata po dubini kultivisanog zemljišta

This paper presents a study of the profile distribution of available micronutrients Fe, Mn, Cu and Zn and radionuclide 137Cs in cultivated soil at the experimental field 'Radmilovac' (property of Agricultural Faculty, Belgrade University) in the vicinity of Vinča Institute of Nuclear Sciences. The soil belongs to the anthrosol class of anthropogenic soils according to FAO (2006). At first, the deep plowing was performed while preparing soil for planting peach trees followed by cultivation of soil for 12 years. All agricultural treatments at the experimental field ceased for three years. After that period, soil sampling was carried out. Contents of DTPA-extracted Fe, Mn, Cu and Zn were in the range of (mg kg-1): 5.8-41.6; 9.2-34.2; 1-7.6 and 0.2-1.3, respectively. Detected activity concentration (Bq kg-1) for 137Cs ranged from 1.8 to 35. It was noticed that distribution patterns of 137Cs radionuclide and available Cu and Zn along soil depth were very similar and they were analyzed by simple linear regression; mutual affinity for the soil organic matter might affect their distribution in soil. Contents of available Fe and Mn exhibited different, more constant distribution within a soil horizon.U ovom radu ispitivana je raspodela sadržaja pristupačnih mikroelemenata Fe, Mn, Cu i Zn i koncentracije aktivnosti proizvedenog radionuklida 137Cs u profilima zemljišta (dubine 080 cm) sakupljenih sa voćnjaka pod zasadom breskvi na oglednom školskom poljoprivrednom dobru 'Radmilovac' (Poljoprivredni fakultet, Univerzitet u Beogradu) u neposrednoj blizini Instituta za nuklearne nauke 'Vinča'. Zemljište pripada klasi antrosol antropogenih zemljišta prema međunarodnoj FAO (2006) klasifikaciji. Priprema zemljišta za sadnju bresaka izvršena je rigolovanjem, posle čega je usledila 12 godina duga nega voćnjaka. Uzorkovanje zemljišta izvršeno je tri godine nakon prestanka svih poljoprivrednih tretmana zemljišta na oglednom polju. Sadržaji pristupačnih mikroelemenata Fe, Mn, Cu i Zn (dobijeni ekstrakcijom sa rastvorom 0,005 M DTPA) nalazili su se u opsegu (mg kg-1): 5,841,6; 9,234,2; 17,6 odnosno 0,21,3. Detektovana koncentracija aktivnosti 137Cs u zemljištu (merena metodom gama-spektrometrije korišćenjem koaksijalnog HPGe-detektora) nalazila se u intervalu (Bq kg-1): 1,835. Uočeno je da su obrasci distribucije po dubini profila pristupačnih oblika Cu i Zn i radionuklida 137Cs bili veoma slični, a rezultati proste linearne regresione analize su pokazali da je uzajamni afinitet prema organskoj materiji zemljišta mogao da utiče na takvu njihovu distribuciju. Sadržaji pristupačnih mikroelemenata Fe i Mn, pokazali su da imaju drugačiju, uniformniju distribuciju po dubini ispitivanih profila zemljišta

Seasonal variations of naturally occurring radionuclides and 137cs in the leaves of deciduous tree species at sites of background radioactivity levels

Activity concentration of natural radionuclides and 137Cs were studied in leaves of the deciduous trees. In the spring and autumn season, leaves were collected in the area of normal background radiation levels represented by city parks in a multi-year period (2002-2012). Measurements by means of gamma-ray spectrometry showed 226Ra and 210Pb seasonal accumulation in leaves, while 238U and 235U could be detected only in autumn. Difference between seasons was not found significant for 40K and 137Cs. The study of radionuclides transfer factors was conducted by analyzing its relationships with basic soil properties at the beginning and the end of the vegetation period. © 2019, Editura Academiei Romane. All rights reserved

Seasonal variations of naturally occurring radionuclides and 137cs in the leaves of deciduous tree species at sites of background radioactivity levels

Activity concentration of natural radionuclides and 137Cs were studied in leaves of the deciduous trees. In the spring and autumn season, leaves were collected in the area of normal background radiation levels represented by city parks in a multi-year period (2002-2012). Measurements by means of gamma-ray spectrometry showed 226Ra and 210Pb seasonal accumulation in leaves, while 238U and 235U could be detected only in autumn. Difference between seasons was not found significant for 40K and 137Cs. The study of radionuclides transfer factors was conducted by analyzing its relationships with basic soil properties at the beginning and the end of the vegetation period. © 2019, Editura Academiei Romane. All rights reserved

238U, 226Ra, 232Th and 40K distribution with soil depth in agricultural soil rigosol type and its relation with main soil properties

Distributions of natural gamma emitting radionuclides 238U, 226Ra, 232Th and 40K were determined in two soil profiles rigosol type under the peach-tree field: one from and second out of the peach-tree root zone. Radioisotope activities (Bq/kg) lie in the range of normal terrestrial gamma-radiation in soil [1]. It is found that variation in natural radionuclides activities along a soil depth of 0-80 cm is due to differences in main soil properties: pH-reaction, carbonates, humus, clay and sand contents confirmed by high correlation between them.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Дистрибуција Cs137 у обрадивом земљишту

Usled padavina koje su usledile nakon Černobilskog akcidenta 1986. godine, proizvedeni radionuklid 137Cs je deponovan u zemljištu. S obzirom na njegovo dovoljno dugo vreme poluraspada (30,05 godina), posebno je važna radiološka zaštita kultivisanog (obradivog) zemljišta jer se postavlja pitanje da li se ovaj radionuklid zadržava u površinskim slojevima zemljišta, da li biva usvojen od strane biljaka ili se spušta u dublje slojeve zemljišta. U ovom radu prikazani su rezultati merenja specifične aktivnosti 137Cs metodom gama-spektrometrije u zemljištu 15 godina starog voćnjaka pod zasadom breskvi. Priprema zemljišta za sadnju bresaka izvršena je rigolovanjem, posle čega je usledila 12 godina duga nega voćnjaka, a zatim uzorkovanje zemljišta je izvršeno tri godine nakon prestanka svih poljoprivrednih tretmana. U radu je prikazan pregled rezultata analize uticaja dugogodišnje kultivacije (obrađivanja) zemljišta na preraspodelu 137Cs duž profila dubine 0-80 cm. Linearna i višestruka regresiona analiza primenjene su da bi se procenilo u kojoj meri su nivoi radioizotopa cezijuma povezani sa: nivoima izotopa kalijuma 40K detektovanim u zemljištu; zatim, osnovnim osobinama koje karakterišu zemljište (pH, sadržaj humusa, sadržaj karbonata, granulometrijski sastav, sadržaj higroskopske vlage); mineralnim sastavom glinovite frakcije zemljišta i dostupnim sadržajima mikroelemenata (Zn, Cu, Mn, Fe). Obrasci distribucije 137Cs sa dubinom ukazivali su da je cezijum bio mehanički prenesen iz površinskih ka nižim slojevima zemljišta tokom kultivacije. Rezultati analiza su pokazali da na zatečenu distribuciju izotopa cezijuma sa dubinom glavni uticaj imaju varijacije sadržaja humusa i minerala glinovite frakcije zemljišta, vermikulita, ilita i smektita.Due to the fallout followed by Chernobyl accident in 1986 anthropogenic radionuclide 137Cs was deposited in the soil. Given long half-life of 137Cs (30.05 years), cultivated soils in particular are subject of radiological protection because the question is whether this radionuclide would be retained in the surface layers of the soil, adopted by plants or transferred to the deeper soil layers. This paper presents an overview of the results of 137Cs specific activity measurements by gamma-spectrometry method in cultivated anthrosol soil of a 15-year old peach tree plantation at the experimental field “Radmilovac”. Preparing the land for planting peach trees deep ploughing was conducted followed by 12-year-long cultivation, and soil sampling was carried out three years after the termination of all agricultural treatments. Overview of the analyzes of the long-term cultivation impact on 137Cs redistribution in the soil along the 0-80 cm profile depth is presented. Linear and multiple regression analysis was applied to assess to what extent the levels of cesium radioisotopes are associated with a) levels of potassium isotope 40K detected in the soil; b) the basic features that characterize the soil (pH, humus content, carbonate content, grain size distribution, moisture content of hygroscopic); c) mineral composition of the clay fraction of soil and d) available DTPA-extracted microelements Zn, Cu, Mn and Fe. Patterns of 137Cs distribution with depth indicated that radiocesium was mechanically transferred from the surface to the lower layers of soil during the cultivation. The results of the statistical analysis showed that on radiocesium variations with depth a major impact had the contents of humus and the main minerals of the clay fraction of soil – vermiculite, illite, and smectite.Article is part of: [http://vinar.vin.bg.ac.rs/handle/123456789/8230

Дистрибуција Cs137 у обрадивом земљишту

Usled padavina koje su usledile nakon Černobilskog akcidenta 1986. godine, proizvedeni radionuklid 137Cs je deponovan u zemljištu. S obzirom na njegovo dovoljno dugo vreme poluraspada (30,05 godina), posebno je važna radiološka zaštita kultivisanog (obradivog) zemljišta jer se postavlja pitanje da li se ovaj radionuklid zadržava u površinskim slojevima zemljišta, da li biva usvojen od strane biljaka ili se spušta u dublje slojeve zemljišta. U ovom radu prikazani su rezultati merenja specifične aktivnosti 137Cs metodom gama-spektrometrije u zemljištu 15 godina starog voćnjaka pod zasadom breskvi. Priprema zemljišta za sadnju bresaka izvršena je rigolovanjem, posle čega je usledila 12 godina duga nega voćnjaka, a zatim uzorkovanje zemljišta je izvršeno tri godine nakon prestanka svih poljoprivrednih tretmana. U radu je prikazan pregled rezultata analize uticaja dugogodišnje kultivacije (obrađivanja) zemljišta na preraspodelu 137Cs duž profila dubine 0-80 cm. Linearna i višestruka regresiona analiza primenjene su da bi se procenilo u kojoj meri su nivoi radioizotopa cezijuma povezani sa: nivoima izotopa kalijuma 40K detektovanim u zemljištu; zatim, osnovnim osobinama koje karakterišu zemljište (pH, sadržaj humusa, sadržaj karbonata, granulometrijski sastav, sadržaj higroskopske vlage); mineralnim sastavom glinovite frakcije zemljišta i dostupnim sadržajima mikroelemenata (Zn, Cu, Mn, Fe). Obrasci distribucije 137Cs sa dubinom ukazivali su da je cezijum bio mehanički prenesen iz površinskih ka nižim slojevima zemljišta tokom kultivacije. Rezultati analiza su pokazali da na zatečenu distribuciju izotopa cezijuma sa dubinom glavni uticaj imaju varijacije sadržaja humusa i minerala glinovite frakcije zemljišta, vermikulita, ilita i smektita.Due to the fallout followed by Chernobyl accident in 1986 anthropogenic radionuclide 137Cs was deposited in the soil. Given long half-life of 137Cs (30.05 years), cultivated soils in particular are subject of radiological protection because the question is whether this radionuclide would be retained in the surface layers of the soil, adopted by plants or transferred to the deeper soil layers. This paper presents an overview of the results of 137Cs specific activity measurements by gamma-spectrometry method in cultivated anthrosol soil of a 15-year old peach tree plantation at the experimental field “Radmilovac”. Preparing the land for planting peach trees deep ploughing was conducted followed by 12-year-long cultivation, and soil sampling was carried out three years after the termination of all agricultural treatments. Overview of the analyzes of the long-term cultivation impact on 137Cs redistribution in the soil along the 0-80 cm profile depth is presented. Linear and multiple regression analysis was applied to assess to what extent the levels of cesium radioisotopes are associated with a) levels of potassium isotope 40K detected in the soil; b) the basic features that characterize the soil (pH, humus content, carbonate content, grain size distribution, moisture content of hygroscopic); c) mineral composition of the clay fraction of soil and d) available DTPA-extracted microelements Zn, Cu, Mn and Fe. Patterns of 137Cs distribution with depth indicated that radiocesium was mechanically transferred from the surface to the lower layers of soil during the cultivation. The results of the statistical analysis showed that on radiocesium variations with depth a major impact had the contents of humus and the main minerals of the clay fraction of soil – vermiculite, illite, and smectite.Article is part of: [http://vinar.vin.bg.ac.rs/handle/123456789/8230

Seasonal changes of naturally occurring radionuclides and fallout 137-Cs in the samples of leaves of deciduous trees

Specifična aktivnost prirodnih radionuklida 238U, 235U, 226Ra, 210Pb, 232Th i 40K i proizvedenog 137Cs je merena u uzorcima lišća dve vrste listopadnog drveća, kestena (Aesculus hippocastanum) i lipe (Tilia spp) koji potiču iz tri gradska parka na užem području Beograda. Uzorci su sakupljani u vreme prolećne (n=7), letnje (n=2) i jesenje (n=8) sezone u periodu od 2002-2012. godine. Iz svake pojedinačne sezone uzorci lišća su spojeni po vrstama pri čemu je dobijen jedan integralni (sezonski) uzorak za svaki ispitivani park čime je postignuta veća efikasnost detekcije niskog nivoa gama zračenja. Za određivanje aktivnosti primenjen je metod spektrometrije gama emitera. U svim pojedinačnim uzorcima suve materije lišća detekcija radionuklida 210Pb i 40K je bila moguća i njihova specifična aktivnost se nalazila intervalu 15-52 Bq/kg i 310-650 Bq/kg, respektivno. Iako je aktivnost 226Ra bila veoma niska, u intervalu 0,5-5,6 Bq/kg, ovaj radionuklid je bio izmeren u svim uzorcima (osim u dva) i svim sezonama. Aktivnost 210Pb i 226Ra se povećavala tokom godine, pri čemu su njihove najveće vrednosti izmerene u lišću kestena u letnjoj sezoni. Suprotno, aktivnost 40K u lišću lipe i kestena je opadala tokom godine. Za razliku od prethodno navedenih, radionuklidi 238U, 235U i 232Th su retko detektovani samo u letnjem i/ili jesenjem periodu i po četiri uzorka lišća su sadržali 238U (2,7-11,7 Bq/kg) i 235U (0,13-1,0 Bq/kg), a tri 232Th (1,8-3,3 Bq/kg). Proizvedeni radionuklid 137Cs detektovan je u svim uzorcima lišća (osim u dva), a bez jasnog trenda ponašanja po sezonama i nalazio se u intervalu 0,3-1,2 Bq/kg. Cilj rada bio je ispitivanje akumulacije prirodnih radionuklida i njihovog potencijalnog variranja tokom godine u lišću listopadnog drveća.The specific activity of naturally occurring radionuclides 238U, 235U, 226Ra, 210Pb, 232Th, and 40K and fallout 137Cs was measured in the samples of leaves of two deciduous tree species, chestnut (Aesculus hippocastanum) and linden (Tilia spp.) common for the Belgrade urban area. Samples were collected in the spring (n = 7), summer (n = 2) and autumn (n = 8) during the vegetation period from 2002 to 2012. From each season, samples of leaves were combined according to two species and one single integral (seasonal) sample was obtained in order to improve detection efficiency of low gamma radiation level. Specific activities were determined using the gamma-ray spectrometry method. 210Pb and 40K radionuclides were detected in all the samples of leaves and their specific activity was in the range (Bq/kg dry weight): 15 - 52 and 310 - 650, respectively. Although the 226Ra level was very low and in the range from 0.5 - 5.6 Bq/kg, this radionuclide has been measured in all samples (except in the two) and each season. 210Pb and 226Ra activity increased during the vegetation period and their highest values were found in the leaves of chestnut trees in the summer season. In contrast, the activity of 40K in the leaves of linden and chestnut has decreased. Detection 238U, 235U and 232Th radionuclides was scarce and only in the summer and/or autumn. Four samples of leaves contained 238U (2.7 - 11.7 Bq/kg dry wt) and 235U (0,13 - 1.0 Bq/kg dry wt) and three of them 232Th (1.8 - 3.3 Bq/kg dry wt). Man-made radionuclide 137Cs (0.3-1.2 Bq/kg dry wt) was detected in all samples of leaves (except in two) and no clear trend according to seasons was found. The aim was to investigate the accumulation of naturally occurring radionuclides and fallout 137Cs in the leaves of deciduous trees and their potential variations during the vegetation period