Search Results
Abstract
Activity concentrations using gamma-ray spectrometer and distributions of natural radionuclides in soil samples collected were investigated to assess the environmental radioactivity and characterization of radiological hazard. The average concentrations of 238U, 232Th series and 40K in the 5 cm depth soil were 22.53, 33.43 and 406.62 Bq kg−1, respectively, which was within world median ranges in the UNSCEAR 2000 report. The average absorbed dose rate estimated by soil activity and annual effective doses were 49.32 nGy h−1 and 60.48 μSv, respectively. Since the soil is an important building material, the mean radium equivalent activity (Ra eq), external (H ex) and internal (H in) hazard index using various models given in the literature for the study area were evaluated as 101.72 Bq kg−1, 0.27 and 0.34, respectively, which were below the recommended limits. The effects of pH value, conductivity, true density and textural properties of soil samples on the natural radionuclide levels were also studied. The application of cluster analysis (CA) and principal component analysis (PCA), coupled with Pearson correlation coefficient analysis, were utilized to analyze the data, identify and clarify the effects of physico-chemical properties on natural radioactivity levels. The CA and PCA results showed that the former method yielded three distinctive groups of the soil variables whereas the latter one yielded the number of variables into three factors with 87.5% variance explanation.
Abstract
Soil radon and the gamma-dose rate have been determined along the Guerrero coast of Mexico, using track detectors, LR 115 Type II and thermoluminescent CaSO4:Dy detectors. Mineralogical analyses were done and 236Ra and 40K specific activities were measured in the rock samples. The results indicate a good correlation between the response of average gamma-dose rate versus radon concentration in the soil. Differences in the radon levels, in the activity concentrations in the rocks and in the local seismicity defined two geographical zones where the number of seismic events, the average radon and the average gamma-dose rate were correlated.
Abstract
Uranium and thorium contents in different layers of stratigraphical sedimentary deposits have been evaluated by using LR-115 type II and CR-39 solid state nuclear track detectors (SSNTD). A method has been developed for determining the alpha-dose rates of the sedimentary travertine samples. Using the U/Th dating method, we succeeded in age dating carbonated level sampled in the sedimentary deposits. Correlation between the stratigraphy, alpha-dose rates and age has been investigated.
Abstract
Catalytic activity of gamma irradiated catalase from bovine liver was studied for hydrogen peroxide decomposition at constant temperature and pressure. The measurement was performed at temperatures 27, 32, 37, 42 and 47 °C. Solutions containing 1 and 0.01 g dm−3 of catalase in phosphate buffer were used for the study. Repeatability of both sample preparation and kinetics measurement was experimentally verified. Rate constants of the reaction were determined for all temperatures and the activation energy was evaluated from Arrhenius plot. Gamma irradiation was performed using 60Co radionuclide source Gammacell 220 at two different dose rates 5.5 and 70 Gy h−1, with doses ranging from 10 to 1000 Gy. The observed reaction of irradiated and non-irradiated catalase with hydrogen peroxide is of the first order. Irradiation significantly decreases catalytic activity of catalase, but the activation energy does not depend markedly on the dose. The effect of irradiation is more significant at higher dose rate.
Abstract
222Rn concentrations along the seismic active area (some distinct in East Anatolian Active Fault System (EAFS), Turkey) were determined by using passive and active (prompt) methods including CR-39 and Markus-10, respectively. It was observed that the changing of 222Rn concentration along the fault lines, crossing the main East Anatolian Fault Line, has shown similar characteristics for both methods. The mean 222Rn concentrations were found to be between 1.2 and 3.6 kBq·m−3 and, 2 and 70 kBq·m−3 by using passive and prompt methods, respectively. Nevertheless, some measured terrestrial gamma-radiation dose rate in the same area has weak positive correlation to 222Rn concentration. Terrestrial gamma-dose rate at 1 m above the ground in the same sampling point, as for 222Rn concentration measurement were made, varied from 8.5 to 10.6 μR·h−1.
Abstract
In the present paper the contribution to the external gamma dose rate due to 137Cs in soil as a function of time is presented. Sampling sites were selected along the Calabria and Basilicata Regions coastal beaches (southern part of Italy) to assess the external gamma dose rate in air, 1 m above the ground level. A convection-dispersion model, with constant parameters was used to approximate the radiocesium soil vertical migration. The model was calibrated using the initial 137Cs activity deposition in this region (Chernobyl fallout) and 137Cs activity concentration down the soil profile, measured 10 years later. The dispersion coefficient and the advection velocity values, were respectively: 2.17 cm2 y−1 and 0.32 cm y−1. The Radionuclide Software Package (RSP), which uses a Monte Carlo simulation code, was used to determine the primary 137Cs gamma dose contribution in air 1 m above the ground surface. The resulting 137Cs external dose rate ranged from 0.42 nGy h−1 in 1986, to 0.05 nGy h−1 in 2007.
Abstract
Uranium and thorium contents in different drinking water samples have been evaluated by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and calculating the probabilities for 
-particles to reach and be registered on the SSNTD films. A new method has been developed based on calculating the stopping powers of the studied material for the - and 
-particles emitted by the nuclei of the uranium and thorium series for evaluating - and -dose rates of the considered water samples. The influence of the soil nature of the aquifer on the alpha- and beta-doses in water samples has been investigated.
Abstract
Specific activity of natural radionuclides; 226Ra, 232Th and 40K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: 40K, (666 Bq/kg), 226Ra (51 Bq/kg), and 232Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.
Abstract
The distribution of the anthropogenic (134Cs and 137Cs) and natural (238U, 232Th and 40K) radionuclide concentrations were studied in soil, foodstuff and bioindicator samples collected from the near site of the Medzamor Nuclear Power Plant at the border of eastern Anatolia of Turkey. For some time, the gross-a and b-concentrations were also determined in the water samples of the region and the absorbed dose rates in air at 1 m above ground were measured. The results showed no additional artificial contamination from the Medzamor Nuclear Power Plant before June 1996.
Abstract
The surveys of natural gamma-emitting radionuclides in soils from three basins of West Anatolia intensively used for agricultural purposes were conducted during 1998–2003. In the present study, part of the survey, the activity concentrations of 238U, 232Th and 40K in the soil samples from 43 sites distributed all over the agricultural land known as Büyük Menderes basin were determined by scintillation gamma spectrometry. The average activity concentrations and ranges of the relevant radionuclides in the soils were as follows: 238U was 29 (7–84); 232Th, 22 (10–48) and 40K, 464 (100–864) Bq kg−1. The corresponding absorbed dose rates in air from all those radionuclides were in the range of 17–81 nGy h−1 with a mean value of 46 nGy h−1 and did not exceed the world-wide average values. All dosimetric calculations were performed based on the guidance of UNSCEAR 2000 report [<cite>1</cite>].
