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1.
Hany A. Shousha 《辐射效应与固体损伤》2013,168(10):615-627
Studies of the natural γ-emitting radionuclides in different types of cements manufactured by different companies in Egypt (e.g. Iron (HI), Karnak (HK), and Super fine (HSu) products from Helwan Ltd.) have been done to determine their natural levels of radioactivity using a high-purity germanium detector (HPGe). Knowledge of radioactivity present in cement materials enables one to assess any possible radiological risks to human health. The results show that the highest mean values of 226Ra and 232Th activity are 234.01±20.12 and 46.56±4.65 Bq kg?1, respectively, measured in cement sample ‘Iron’ from Helwan company (HI). The corresponding value of 40K is 333.53±26.68 Bq kg?1 measured in cement sample ‘Karnak’ from Helwan company (HK). For 137Cs, this value is 3.27±0.31 Bq kg?1 measured in cement sample (HI). The average concentrations of measured radionuclides in the different cement samples are 72.21±6.39, 24.98±2.24, 134.49±10.45, and 0.58±0.08 Bq kg?1 for 226Ra, 232Th, 40K, and 137Cs, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries. Radium equivalent (Raeq) activities and different hazard indices were calculated to assess the radiation hazard. Iron HI cement sample shows a higher Raeq activity of 311.91±31.10 Bq kg?1. Calculations of absorbed doses in nGy h?1 show that the Iron (HI), Karnak (HK), and Super fine (HSu) products from Helwan company have higher activities than the permissible level (80 nGy h?1). On the basis of the external hazard index (H ex), Raeq activities, and annual effective dose rates for organs (H organ), the natural radioactivity of cement samples is not greater than the recommended values in the established standards and hence safe for use in building constructions and therefore for inhabitants. 相似文献
2.
ABSTRACTThe specific activities of 226Ra, 232Th and 40K of 26 samples of granite produced in Xinjiang of China were measured by a high-purity germanium detector, and their radiological hazards of radium equivalent, external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index were evaluated. The results indicate that the overall average specific activities of 226Ra, 232Th and 40K obtained in the investigated samples are below the world’s average granite values. The average radium equivalent is within the recommended limit of 370?Bq?kg?1. The results obtained further show that the mean values of external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index are 0.65, 0.77, 111.7?nGy?h?1, 0.55 mSv?y?1, 0.89 and 0.23, respectively. These mean values established that radiological hazards are also found to be below the international recommended values. The results are compared with granite samples from other countries or China-Taiwan province. It can be noticed that the specific activity values of granite samples produced in China are lower or similar to that of other countries or China-Taiwan province, however there are higher specific activity values for 226Ra and 232Th in individual samples, which need to provide proper radiation monitoring before use considering the long term health effect. 相似文献
3.
Mineralogical,geochemical and radiological characterisation of Selmo Formation in Batman area,Turkey
Umit Isik Dicle Bal Akkoca Uǧur Cevik 《Isotopes in environmental and health studies》2013,49(2):302-312
This work deals with the mineralogical, geochemical and radiological characterisations of Selmo Formation in Batman neighbourhood. The upper Miocene–Pliocene Selmo Formation is common in the centre of Batman and composed of carbonated sandy claystones and silty–sandy stone lenses. The common whole minerals of the samples are quartz, feldspars, calcite and dolomite. The clay minerals are smectite, illite, chlorite and mixed-layer clay (chlorite–smectite). The geochemical mean values of the samples are 51.7% SiO2; 12.6% Al2O3; 6.2% Fe2O3; 3.6% MgO; 6.3% CaO; 1.1% Na2O; 1.7% K2O; 0.8% TiO2; 0.2% P2O5; 0.1% MnO; and 0.03% Cr2O3. In addition, baseline maps for the concentrations of each radionuclide, the radium equivalent activity and the outdoor gamma dose rate distributions have been plotted for the study area. The mean activity concentrations of 226Ra, 232Th, 40K and 137Cs were determined to be 32, 24, 210 and 9 Bq kg?1, respectively. The assessments of the radiological hazard indices, such as radium equivalent activity, absorbed dose rate in air, annual effective dose equivalent, excess lifetime cancer risk, external hazard index and internal hazard index, were calculated and compared with the internationally accepted reference values. This study shows that the concentrations of radioactivities in the measured samples were within the recommended safety limits and did not pose to be any significant source of radiation hazard. 相似文献
4.
Efficiency and resistance of the artificial oxalate protection treatment on marble against chemical weathering 总被引:1,自引:0,他引:1
The artificial oxalate protection method was analyzed in laboratory experiments in order to achieve an optimum treatment application and concentration giving rise to its most effective protective nature. Spectroscopic (Fourier transform infrared, Micro-Raman and UV-vis colorimetry), microscopic (scanning electron microscope) and contact-angle analyses were carried out to characterize Carrara marble samples before and after application of the treatment to validate its efficiency. The resistance effects against chemical weathering were subsequently observed in a lab-controlled weak acid rain experiment. An acid spray at pH 5.5, representative of normal rain was used to provoke degrade of natural marble, marble treated with the artificial oxalate protective at concentrations of 0.4 and 5% and marble treated with a commercial organic silicon product. Run-off solutions sampled at timely intervals were tested for any change in pH followed by ion chromatography measurements for the presence of calcium ions in solution. The chromatography results of the oxalate treatment applied at a 5% concentration are analogous to an organic commercial product indicating its validity as a method for the conservation of carbonate substrates conferring protection to stone materials against acid environments. 相似文献
5.
Abubakar Sadiq Aliyu Umar Ibrahim Chidozie Timothy Akpa Nuraddeen Nasiru Garba Ahmad Termizi Ramli 《Isotopes in environmental and health studies》2013,49(3):448-468
Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides (226Ra, 232Th and 40K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of 40K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67?% higher than the world average value for 40K, respectively. In all mines, the annual effective dose rates (mSv y?1) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y?1 is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h?1. These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining. 相似文献
6.
Khalid Khan Muhammad Rizwan Khalid Abdul Jabbar Perveen Akhter 《Isotopes in environmental and health studies》2013,49(2):286-294
Natural and anthropogenic radioactivity of sand and water samples collected from the four big rivers of Punjab province, Pakistan, was measured using a high-purity germanium detector coupled with a high resolution multichannel analyser. The average concentration of the naturally occurring radionuclides 226Ra, 232Th and 40K in all the sand samples from the rivers Jhelum, Chenab, Ravi and Indus was found to be 22±0.6, 36±1 and 287±10 Bq?kg ?1, respectively, while the concentration of the anthropogenic radionuclide 137Cs was found to be below the minimum detectable activity, i.e. ~ 1.2 Bq?kg ?1. All the sand samples have Raeq concentrations lower than the limit of 370 Bq?kg ?1. Indoor (H in) and outdoor (H out) radiation hazard indices were calculated for the samples to assess the radiation hazards arising due to the use of this sand in construction, and were found to be less than unity in the study area. Calculated values of the absorbed dose rate were less than the typical world average value of 59 nGy?h ?1, and the annual effective dose rate was also less than the typical world value of 70 μSv, except in the Indus river, in which it is slightly higher then the world average. Results show that the measured values are comparable with other global radioactivity measurements. None of the studied riverbeds was considered a radiological hazard, and their sand can be safely used in construction. 相似文献
7.
Enis Kapdan Nesrin Altinsoy Gursel Karahan Halim Taskin 《Isotopes in environmental and health studies》2013,49(1):93-100
Human body is exposed to ionising radiations both internally and externally by mainly high-energy cosmic ray particles incident on the earth's atmosphere and radioactive nuclides that originated in the earth's crust. The main objective of this study is to assess the health hazards due to environmental radiation sources in the city of Adapazari, one of the most important industrial cities of the country, Northwestern Turkey. For this purpose, natural radiation sources, external terrestrial radiations, cosmic radiations, and inhalation exposures have been investigated. The annual average external terrestrial radiation doses were determined as 0.08 and 0.35 mSv at outdoor and indoor atmospheres, respectively. The annual average cosmic radiation doses were found to be 0.08 and 0.05 mSv for directly ionising photon components and neutron components, respectively. The annual average inhalation exposure doses due to radon and thoron were obtained as 1.42 and 0.19 mSv, respectively, in the region. The annual average effective dose due to natural radiation sources was determined as a total of 2.35 mSv with the predetermined ingestion radiation dose. The lifetime cancer risk due to the background ionising radiations has been determined as 0.9×10?2 for the residents of the Adapazari city, with the average lifespan of 70 years. The results of the effective doses due to background radiation sources in the region and the worldwide averages were discussed. 相似文献
8.
E.O. Joshua J.A. Ademola M.A. Akpanowo O.A. Oyebanjo D.O. Olorode 《Radiation measurements》2009,44(4):401-404
Gamma radiation from natural radionuclides in thirty eight rock samples collected from Southeastern Nigeria was measured using gamma-ray spectrometry method. The activity concentrations varied from 13.1 ± 1.6 Bq kg−1 (ferrogeneisis shale) to 129 ± 38 Bq kg−1 (granite) for 226Ra, 42.4 ± 4.5 Bq kg−1 (siltstone) to 150 ± 23 Bq kg−1 (pegmatite) for 232Th and 64.5 ± 6.3 Bq kg−1 (ferrogeneisis shale) to 882 ± 298 Bq kg−1 (granite) for 40K. Hazard indices were used to determine the suitability of the rock samples for building in the context of radiological hazard. The results obtained for the radium equivalent activity and the external hazard index show that two of the samples, granite and pegmatite exceeded the recommended limits of 370 Bq kg−1 and 1, respectively. However the results of the gamma index were below the recommended limit. The dose rates and the annual effective dose calculated ranged from 0.012 to 0.042 μGy h−1 and 0.06–0.21 mSv, respectively. 相似文献
9.
Amira Kasumović Feriz Adrović Amela Kasić Ema Hankić 《Isotopes in environmental and health studies》2013,49(3):469-477
The results of activity concentration measurements of natural occurring radioactive nuclides 238U, 235U, 232Th, 226Ra, and 40K in surface soil samples collected in the area of cities Tuzla and Lukavac, northeast region of Bosnia and Herzegovina were presented. Soil sampling was conducted at the localities that are situated in the vicinity of industrial zones of these cities. The measured activity was in the range from (8?±?4) to (95?±?28) Bq kg–1 for 238U, from (0.41?±?0.06) to (4.6?±?0.7) Bq kg–1 for 235U, from (7?±?1) to (66?±?7) Bq kg–1 for 232Th, from (6?±?1) to (55?±?6) Bq kg–1 for 226Ra, and from (83?±?12) to (546?±?55) Bq kg–1 for 40K. In order to evaluate the radiological hazard of the natural radioactivity for people living near industrial zones, the absorbed dose rate, the annual effective dose and the radium equivalent activity have been calculated and compared with the internationally approved values. 相似文献
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The activity concentrations of 226Ra, 232Th and 40K have been determined by gamma-ray spectrometry. The measured activity in the selected building materials ranges from (3.2 to 151.7 Bq/kg), 14 to 63.7 Bq/kg and 24.3 to 121.5 Bq/kg for 226Ra, 232Th and 40K respectively. The activity concentration of 238U has been determined using fission track technique and the value ranges from 0.11 to 3.85 ppm. The concentrations for these natural radionuclides are compared with the reported data from other countries. Radium-equivalent activities (Raeq) are calculated for the measured samples to assess the radiation hazards arising due to the use of these materials in the construction of dwellings. All building materials have shown Raeq activities lower than the limit set in the Organization for Economic Cooperation and Development (OECD) report (370 Bq/kg), equivalent to external gamma dose of 1.5 mSvyr−1. A good correlation has been observed between 238U and 226Ra in these materials. 相似文献
12.
Ahmad Hussein Alomari Muneer Aziz Saleh Suhairul Hashim Amal Alsayaheen Ahmad Abukashabeh 《Isotopes in environmental and health studies》2019,55(2):211-226
An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides 226Ra, 232Th, 40K, and 137Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for 226Ra, 232Th, 40K, and 137Cs has mean values of 42?±?3, 23?±?3, 309?±?21, and 3.7?±?0.9 Bq kg–1, respectively. The highest mean activity concentration for 226Ra was found to be 138?±?4 Bq kg–1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35?±?3 Bq kg–1 for 232Th, and 14.2?±?1.9 Bq kg–1 for 137Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of 232Th, 40K, and 137Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to 226Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg–1, and 0.266, respectively. 相似文献
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Necati Celik Ugur Cevik Ahmet Celik Bahadir Koz 《Isotopes in environmental and health studies》2013,49(3):315-323
About 21 years after the Chernobyl accident, 137Cs and 40K activity concentration measurements using gamma-ray spectroscopy and elemental analysis using energy dispersive X-ray spectroscopy were performed in five different lichen species collected from the Giresun province of northeastern Turkey. Being a symbiosis of algae and fungi, lichens are mostly used for environmental measurements since the fungal partner is responsible for the uptake of necessary nutrients or harmful substances, such as heavy metals of radionuclides. The gamma activity results showed that 137Cs, an artificial radionuclide released from the Chernobyl power plant accident, is still eminent in the environment of the province. The mean activity concentrations of 137Cs and 40K ranged from 24 to 254 with the mean value of 102 Bq kg?1 and from 345 to 2103 with the mean value of 1143 Bq kg?1 in dry weight. The results of the elemental analyses showed potassium, calcium, titanium, iron, tin, and barium in different concentrations. 相似文献
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由于天然源超低频电磁探测仪器接收的是宽频段多源信号,如何进行信号的分解以将干扰信号滤除,是利用天然源超低频电磁探测技术进行实际探测应用的关键。北京大学自主研发的天然源超低频电磁探测仪器,以山西沁水盆地煤层气探测数据为研究对象,将曲波变换的方法应用在超低频电磁探测频谱的分解上。分解结果表明,曲波变换分解出的高频信息主要是探测仪器直接接收的大气层雷电产生的干扰信号,而低频信息层则主要包含了地下的探测目标信息。基于此,以低频信息为基础重构后的探测频谱曲线相对于原始探测曲线来说,更有利于探测目标的解释。但是对于由于人工工频所引起的干扰信号,该方法并不能有效去除,在实际应用中需要结合其他数据处理方法一同进行。 相似文献
17.
A nonlocal Euler–Bernoulli elastic beam model is developed for the vibration and instability of tubular micro- and nano-beams conveying fluid using the theory of nonlocal elasticity. Based on the Newtonian method, the equation of motion is derived, in which the effect of small length scale is incorporated. With this nonlocal beam model, the natural frequencies and critical flow velocities for the case of simply supported system and for the case of cantilevered system are obtained. The effect of small length scale (i.e., the nonlocal parameter) on the properties of vibrations is discussed. It is demonstrated that the natural frequencies are generally decreased with increasing values of nonlocal parameter, both for the supported and cantilevered systems. More significantly, the effect of small length scale on the critical flow velocities is visible for fluid-conveying beams with nano-scale length; however, this effect may be neglected for micro-beams conveying fluid. 相似文献
18.
We constructed an agent-based stock market model which concisely describe investors? heterogeneity and adaptability by introducing price sensitivity and feedback time. Under different parameters, the peak and fat-tail property of return distribution is produced and the obtained statistic values coincide with empirical results: the center peak exponents range from ?0.787 to ?0.661, and the tail exponents range from ?4.29 to ?2.37. Besides, long-term correlation in volatility is examined by DFA1 method, and the obtained exponent α is 0.803, which also coincides with the exponent of 0.78 found in real market. 相似文献
19.
汉语普通话教学已经在我国各少数民族地区的教育工作中占据越来越重要的地位,然而从这些地区的相关教育实践来看,汉语普通话正面临着语音素质和教学质量较低的严峻问题。该文采用实验语音学,对比分析、偏误分析的理论及方法,考察并分析了维吾尔族学生习得汉语单字调声调的情况。主要是对初级、中级和高级阶段的50名维吾尔族学生声调的五度值曲线和声调之间相似度与标准普通话者进行对比并分析,得出维吾尔族学生对汉语声调的偏误情况以及MHK成绩的关系。通过实验结果可以发现,三组的维吾尔人学习普通话的声调都有困难。两种语言的音系、语调和重音等特性影响了第二语言中的声调特性。这种声调系统的差异导致了维吾尔族人学习普通话声调产出的困难。通过这项实验揭示了目前维吾尔学生对汉语普通话中声调发音的掌握情况,同时有助于进一步了解维吾尔族普通话学习者汉语声调的偏误。 相似文献
20.
以天然矿物为原料,结合中国紫的分子式及多数考古样品的分析结果进行配料(如或多或少都含有铅),对配制并加工好的试样进行热重-差热及变温XRD分析,以探讨古代烧制中国紫颜料时的原料选用及烧制条件等问题,为揭示诸如中国紫产生在中国的原因等问题提供依据。结果表明利用毒重石(BaCO3)配料,能够较容易地烧制出中国紫,这意味着中国紫的出现可能与这种独特的含钡矿物资源有关。 相似文献