Natural radioactivity in tap waters of Eastern Black Sea region of Turkey

In this study, the activity concentrations of some radionuclides in tap water samples of the Eastern Black Sea region of Turkey were measured. The activity concentrations of radionuclides (214)Pb, (214)Bi, (40)K, (226)Ra and (137)Cs were determined using high resolution gamma ray spectrometry. Furthermore, (222)Rn activity concentrations in tap water samples were measured using Liquid Scintillation Counting. The mean specific activities of (214)Pb, (214)Bi, (226)Ra, (40)K, (137)Cs and (222)Rn in tap water samples were 6.73, 6, 19.16, 168.57, 5.45 mBq l(-1) and 10.82 Bq l(-1), respectively. These values are comparable with concentrations reported for other countries. The effective doses were determined due to intake of these radionuclides as a consequence of direct consumption of tap water samples. The estimated effective doses were 6.878 x 10(-4) microSv y(-1) for (214)Pb, 4.800 x 10(-4) microSv y(-1) for (214)Bi, 3.916 microSv y(-1) for (226)Ra, 0.763 microSv y(-1) for (40)K, 0.052 microSv y(-1) for (137)Cs and 5.848 microSv y(-1) for (222)Rn.     

Natural and artificial radioactivity measurements in Eastern Black Sea region of Turkey

Sorption potential of waste short hemp fibers for Pb(2+), Cd(2+) and Zn(2+) ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the change in accessibility of the cell wall components to aqueous solutions due to the fiber modification. The effects of initial ion concentration, contact time and cosorption were studied in batch sorption experiments. The obtained results show that when the content of either lignin or hemicelluloses is progressively reduced by chemical treatment, the sorption properties of hemp fibers are improved. Short hemp fibers are capable of sorbing metal ions (Pb(2+), Cd(2+) and Zn(2+)) from single as well as from ternary metal ion solutions. The maximum total uptake capacities for Pb(2+), Cd(2+) and Zn(2+) ions from single solutions are the same, i.e. 0.078mmol/g, and from ternary mixture 0.074, 0.035 and 0.035mmol/g, respectively.     

Natural and artificial radioactivity measurements in Eastern Black Sea region of Turkey

In the present work, naturally occurring radionuclides of ²²⁶Ra, ²³²Th and ⁴⁰K were measured in soil samples collected from the Eastern Black Sea region of Turkey. It was found that the activity concentrations ranged from 12 to 120 Bq kg⁻¹ for ²²⁶Ra, from 13 to 121 Bq kg⁻¹ for ²³²Th and from 204 to 1295 Bq kg⁻¹ for ⁴⁰K. Besides naturally occurring radionuclides, ¹³⁷Cs activity concentration was measured in soil, lichen and moss samples and it was found that ¹³⁷Cs activity concentration ranged from 27 to 775 Bq kg⁻¹ with for soil, from 29 to 879 Bq kg⁻¹ for lichen and from 67 to 1396 Bq kg⁻¹ for moss samples. Annual effective doses due to the naturally occurring radionuclides and ¹³⁷Cs were estimated. Ecological half-lives of ¹³⁷Cs in lichen and moss species were estimated. The decrease of the activity concentrations in the present measurements (2007) relative to those in 1993 indicated ecological half-lives between 1.36 and 2.96 years for lichen and between 1.35 and 2.85 years for moss species.     

Assessment of natural radioactivity concentrations and gamma dose rate levels in Kayseri, Turkey

This study assesses the level of background radiation for Kayseri province of Turkey. Natural radionuclide activity concentrations in soil samples were determined using high-resolution gamma spectroscopy. Outdoor gamma dose measurements in air at 1 m above ground level were determined using a portable gamma scintillation detector. The obtained results of uranium and thorium series as well as potassium ((40)K) are discussed. The present data were compared with the data obtained from different areas in Turkey. From the measured gamma-ray spectra, the average activity concentrations were determined for (238)U (range from 3.91 to 794.25 Bq kg(-1)), (232)Th (range from 0.68 to 245.55 Bq kg(-1)) and (40)K (range from 23.68 to 2718.71 Bq kg(-1)). The average activity concentrations of (238)U, (232)Th and (40)K were found to be 35.51, 37.27 and 429.66 Bq kg(-1), respectively, and 11.53 Bq kg(-1) for the fission product (137)Cs. The highest values of (238)U, (232)Th and (40)K concentrations (794.25 Bq kg(-1), 245.55 Bq kg(-1), 2718.71 Bq kg(-1), respectively) were observed in abnormal samples at Hayriye village. The average outdoor gamma dose rate in air at 1 m above the ground was determined as 114.43 nGy h(-1). Using the data obtained in this study, the average annual effective dose for a person living in Kayseri was found to be about 140.34 μSv.     

A study of environmental radioactivity measurements for Cankiri, Turkey

This study is the first to assess the level of background radiation for the Cankiri province of Turkey. Indoor air radon concentrations were determined using Columbia Resin-39 nuclear track detectors and the average (222)Rn activity was found to be 44 Bq m(-3) (equivalent to an annual effective dose of 1.1 mSv). Measurements of gamma doses in outdoor air were performed using a portable plastic scintillation detector and the average gamma absorbed dose rate was found to be 8 μR h(-1) (corresponding to an annual effective dose of 87.7 μSv). Radionuclide activity concentrations in soil samples were measured through gamma-ray spectrometry and the average activities were determined as 17.7, 22.3, 357 and 4.1 Bq kg(-1) for the radionuclides (238)U, (232)Th, (40)K and (137)Cs, respectively. The average annual effective dose from the natural radioactivity sources ((238)U series, (232)Th series and (40)K) was calculated to be 44.4 μSv. Radioactivity levels of drinking water samples were carried out using a low-background proportional counter and the average gross alpha and beta activities were obtained as 0.25 and 0.26 Bq l(-1), respectively (equivalent to an annual effective dose of 184 μSv). The average radon concentrations in indoor air and the average radionuclide activities in soil were found to be lower than most Turkish cities while higher levels of outdoor gamma dose rate and water radioactivity were observed. The results of this study showed that the region's background radioactivity level differs considerably from the reported data for Turkish cities.     

Natural radioactivity levels of granites used in Turkey

Thirty granite samples commonly used in Turkey were surveyed for natural radioactivity. Concentrations of natural radionuclides in all samples were determined by gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured for (226)Ra and (232)Th ranged from 0.7±0.1 to 186±1 Bq kg(-1), and from 0.5±0.1 to 249±2 Bq kg(-1), respectively. The activity concentrations obtained for (40)K varied from minimum detectable activity (0.4 Bq kg(-1)) to 1935±11 Bq kg(-1). The radium equivalent activity (Ra(eq)), the absorbed dose rate (D), the external hazard index (H(ex)) and the annual effective dose equivalent were also calculated and compared with the international recommended values. Granite samples were also analysed mineralogically. It was observed that the presence of large amount orthoclase and radiogenic accessory minerals are the sources of high activity concentration levels.     

Natural radioactivity and evaluation of effective dose equivalent of granites in Turkey

Annual effective dose equivalent due to natural gamma radiation from (238)U, (232)Th and (40)K have been evaluated from granites in Turkey. Forty samples were taken for spectrometric analysis. Specific concentrations of (238)U, (232)Th and (40)K in granite samples were determined. Spectroscopy system was used with 1.8 keV (FWHM) coaxial high purity germanium (HPGe) detector. Average values of concentrations of (238)U, (232)Th and (40)K were detected at 15.85, 33.76 and 359 Bq kg(-1), respectively. The average value of radon varies from 0.073 to 0.185 Bq m(-2) h(-1) exhalation depends on the specific concentration of uranium. The dose rate due to this highest activity which have been evaluated by a Monte Carlo transport calculations does not exceed 0.4 mSv a(-1).     

Natural radioactivity measurements in soil samples of central Kutahya (Turkey)

Measurement of the natural radioactivity of surface soils at 20 locations in central Kutahya has been made using gamma ray spectroscopy. Natural gamma ray radioactivity of the terrestrial nuclides in soil samples and the absorbed gamma ray dose rates of these radionuclides in the air have been calculated throughout different areas of central Kutahya. The average annual effective dose equivalent for a person living in central Kutahya was found to be approximately 57 microSv.     

Assessment of natural radioactivity and the associated hazards in Iranian cement

This paper presents the finding of a study undertaken to determine natural radioactivity and associated hazards in local types of cement in Iran. A total of 42 samples were collected from various manufacturers and suppliers and analysed using a shielded HPGe gamma-ray spectrometer. The specific activities of 232Th, 226Ra and 40K were measured in samples and results ranged from minimum values of 8, 16, 101 Bq kg(-1) to maximum values of 17, 43 and 141 Bq kg(-1), respectively. On the basis of activity concentration index (I), it could be shown that, the radioactivity of local cement samples was not greater than the established standard values in other countries.     

一种强光背景下小目标图像的增强方法

针对强光背景下小目标图像特点,提出了一种图像增强算法。在分析了归一化不完全Beta函数取值特征后,找出了Tubbs用于拟合的α、β值在原图极亮、极暗情况下产生跳变的原因,给出了其服从连续变化规律的解释,并在采取模拟退火算法求取其最佳值时,给出了相应处理办法,从而确定了最佳变换曲线,实现原图像的自适应增强;然后采取基于三帧累加图像流处理的办法来累积小目标能量及平滑噪声。仿真实验结果表明,该方法能有效实现强光背景下小目标图像的增强。     

Statistical characterization of hyperspectral background clutter in the reflective spectral region

Hyperspectral imaging systems for daylight operation measure and analyze reflected and scattered radiation in p-spectral channels covering the reflective infrared region 0.4-2.5 microm. Consequently, the p-dimensional joint distribution of background clutter is required to design and evaluate optimum hyperspectral imaging processors. In this paper, we develop statistical models for the spectral variability of natural hyperspectral backgrounds using the class of elliptically contoured distributions. We demonstrate, using data from the NASA AVIRIS sensor, that models based on the multivariate t-elliptically contoured distribution capture with sufficient accuracy the statistical characteristics of natural hyperspectral backgrounds that are relevant to target detection applications.     

声呐图像背景区域灰度统计特性分析与拟合

利用声呐进行水下目标定位识别是当前水下目标识别与跟踪的重要手段之一,由于声呐图像受噪声影响严重、分辨率低,对声呐图像的背景建模有助于其目标分割与识别。首先,分析声呐图像背景区域灰度的统计特性,结合其特点采用高斯分布、Gamma分布、威布尔分布、瑞利分布模型对6类不同背景区域声呐图像统计特性进行拟合,构建声呐图像背景区域模型。最后,采用?2准则和Kolmogorov距离误差评价准则评估拟合效果。拟合结果表明,高斯分布、Gamma分布和威布尔分布均能较好地逼近声呐图像背景区灰度统计特性。为满足实时性的应用需求,选用高斯分布构建声呐图像背景灰度统计模型是可行、合理的方案,从而为声呐图像预处理和目标分割提供了背景模型建模的理论依据。     

Assessment of the natural radioactivity in the soils of Windhoek city, Namibia, Southern Africa

The radioactivity concentrations of (238)U, (232)Th and (40)K in 160 soil samples collected from 16 geographical areas across Windhoek city, Namibia, have been determined using an HPGe detector and found to vary from 15.0 +/- 1.3 to 37.8 +/- 2.1 Bq kg(-1) for (238)U, 17.5 +/- 2.7 to 62.1 +/- 3.3 Bq kg(-1) for (232)Th and 168.9 +/- 15.0 to 784.9 +/- 30.1 Bq kg(-1) for (40)K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose for the city. The value of 0.07 +/- 0.01 mSv y(-1) obtained for the mean effective dose is less than the maximum permissible dose of 1 mSv y(-1) recommended for the public by the International Commission on Radiological Protection.     

Fabrication of ultra-low radioactivity detector holders for Edelweiss-II

In its first stage, the EDELWEISS-II dark matter experiment will use 21×320 g ionization-heat bolometers with NTD thermal sensors. To improve the present sensitivity of EDELWEISS to WIMP interactions by a further factor 100, ultra-low radioactivity detector holders exclusively made of copper and Teflon have been designed. The new design is using the relative expansion coefficients of copper, Teflon and germanium to hopefully ensure a dissipation-free detector holding.

In order to validate this new holder, we need to compare the vibration behavior of the old holder and the new one. The amplitude of the bolometer vibrations is measured using the variation of capacitance between electrodes sputtered on the Ge crystal and reference electrodes fixed above the detector holders. We present noise measurements and compare them to the equivalent measurements using the detector holders of the Edelweiss-I experiment, which gave very satisfying results.     

Assessment of radioactivity and the associated hazards in local and imported cement types used in Sudan

Activity concentration of 232Th, 226Ra and 40K in local (Atbra and Rabak) and imported cement types (Jordanian, Indonesian and Seabulk) has been measured using high-resolution gamma-spectrometry. The average values obtained for 232Th, 226Ra and 40K activity concentrations in different cements are lower than the corresponding global values reported in UNSCEAR publications. The radium-equivalent activity (Raeq) of the samples was calculated and compared with similar data reported in the literature. The comparison has revealed that Raeq values obtained fall far below the criterion limit specified for building materials. The potential radiological hazard of the different samples was estimated using different approaches: representative level index and annual dose limit (dose due to gamma radiation inside the room and inhalation of radon). The estimated representative level index for all the samples is less than unity (the upper limit) indicating that the associated gamma radiation level is low. The annual dose limit falls within 0.19 to 0.30 mSv, which is an order of magnitude below the criterion limit specified for building materials in the literature.     

Occupational exposure to ionising radiation in the region of Anatolia, Turkey for the period 1995-1999

For this study, the individual annual dose information on classified workers who are occupationally exposed to extended radiation sources in Turkey, was assessed and analysed by the Ankara Nuclear Research and Training Centre dosimetry service at the Turkish Atomic Energy Authority for the years 1995-1999. The radiation workers monitored are divided into three main work sectors: conventional industry (8.24%), medicine (90.20%) and research-education (1.56%). The average annual dose for all workers in each particular sector was 0.14, 0.38 and 0.08 mSv, respectively, in 1995-1999. This paper contains the detailed analysis of occupational exposure. The statistical analysis provided includes the mean annual dose, the collective dose, the distributions of the dose over the different sectors and the number of workers who have exceeded any of the established dose levels.     

Assessment of radionuclide level in topsoil samples for partial areas of Tibet, China

By using high-purity germanium gamma spectroscopy, specific activities of naturally occurring and man-made radionuclides were determined in topsoil samples collected from Nyingch, Lhasa and Xigazê of Tibet Autonomous Region, China. The average activity concentrations of (226)Ra, (232)Th and (40)K were 25.1 ± 0.7, 67.1 ± 2.8 and 608.6 ± 12.9 Bq kg(-1), respectively. The activity concentration of (137)Cs was found to vary from <0.3 (minimum detection concentration) to 46.2 Bq kg(-1) with an average of 4.3 ± 0.5 Bq kg(-1). By using the results of (226)Ra, (232)Th and (40)K in the sampled soils, the average outdoor gamma dose rate in air was calculated as 77.5 ± 23.2 nGy h(-1). Furthermore, the average outdoor annual effective dose from terrestrial radiation was 0.10 mSv. The external hazard index in this work varied from 0.20 to 0.70 with an average of 0.40 ± 0.14. The external exposure from terrestrial radiation will not pose any significant radiological threat to the population resident in the studied areas.     

Assessment of trace element levels in Rhododendron honeys of Black Sea Region, Turkey

Rhododendron and multi-flower honeys obtained from Black Sea Region of Turkey (12 Rhododendron and 8 multi-flower honeys) were studied to determine the presence of the 14 trace elements such as Cu, Cd, Pb, Co, Cr, Ni, Al, Se, Zn, Mn, Fe, K, Ca and Mg. Trace element determination was performed by atomic absorption spectrometry (AAS) after microwave digestion. The results revealed that Rhododendron honeys exhibited higher concentrations of Cu, Co, Cr, Ni, Se, Zn, Ca and Mg but lower concentrations of Al, Mn, Fe and K than in the multi-flower honeys. Trace element levels in analyzed honey samples were generally lower than literature values.