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为了准确掌握翡翠原石的放射性水平,消除公众对珠宝玉石存在放射性的疑虑,本文选取了3种翡翠原石的10件样品,利用高纯锗型(HPGe)低本底多道γ能谱仪测量了样品中天然放射性核素226Ra、232Th和40K的比活度值.结果表明,样品中有关核素的比活度值低于或仅略高于仪器检测限,样品的内照指数(IRa)和外照指数(Iγ)均远远低于国家对建筑材料中放射性核素的限量规定,说明翡翠原石的放射性水平很低,与环境的天然本底相当,不存在所谓的放射性危害. 相似文献
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青岛市天然放射性环境地质调查 总被引：2，自引：0，他引：2
对青岛地区进行了大规模的天然放射性环境地质调查和评价中发现,青岛地区陆地伽马辐射剂量率虽然略高于全国和山东省的平均水平,但仍属于天然辐射安全区域.测区的伽马辐射剂量率值总体上决定于岩性.伽马辐射剂量率都来自于238U、232Th、40K的贡献,但是与其他地区不同,40K和232Th对剂量率的贡献要大于238U.此外,一些公路、建筑等建造材料中的放射性核素的含量直接影响着这些工程的放射剂量,主要是在建造这些工程时所选用的石材、石料和水泥等,都会对当地的放射剂量有着重大的影响. 相似文献
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通过对青岛市1500km^2范围内大密度土壤放射性核素（^238U、^232Th和^40K）和地表γ辐射测量,系统深入地研究了其放射性特征、分布规律及其影响因素。结果表明,青岛市土壤中核素^232Th和咏的放射性比活度偏高,而^238U偏低。地表γ辐射吸收剂量率（平均值91．87nGy·h^-1）略高于全国和世界平均值,研究发现地表93．14％的γ辐射来自地面放射性核素^238U、^232Th和^40K）的．γ辐射,其中^232Th和^40K的贡献占81．21％,是主要的贡献者。地质背景是影响地面γ辐射吸收剂量率的主要因素,燕山期各类花岗岩是导致青岛市区-王哥庄-带γ辐射吸收剂量率偏高的主要原因;同时环境因素（路面材料、地貌景观）对地表γ辐射吸收剂量率也存在一定影响。虽然研究区的γ辐射吸收剂量率较高,但其年有效剂量（0．56 mSv）远低于公众照射年剂量当量限值1.0 mSv,人居环境基本不受影响。 相似文献
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对青岛市1 500 km 2范围内大密度土壤放射性核素和地表γ 辐射测量,系统深入研究了其放射性特征、分布规律及其影响因素。结果表明,青岛市土壤中核素232 Th 和40 K 的放射性比活度偏高,而238U 偏低。地表γ 辐射剂量率( 平均值91. 87 nGy /h) 略高于全国和世界平均值。研究发现,地表 93. 14%的γ 辐射来自地面放射性核素238U、232 Th 和40K 的γ 辐射,其中232 Th 和40K 的贡献占81. 21%,是主要的贡献者。地质背景决定地面γ 辐射剂量率值,燕山期各类花岗岩是导致青岛市区-王哥庄一带γ 辐射剂量率偏高的主要原因; 同时环境因素( 路面材料、地貌景观) 对其剂量率也存在一定影响。虽然研究区的γ 辐射剂量率较高,但其年有效剂量( 0. 56 mSv) 低于公众照射年剂量当量限值 ( 1. 0 mSv) ,人居环境基本不受影响。 相似文献
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利用ARD型γ能谱仪对辽宁省大连市区地表天然放射性核素238U、232Th、40K含量进行了现场测量.调查结果显示,大连市区238U、232Th、40K比活度平均值分别为23.09 Bq/kg（范围值1.24~151.91 Bq/kg）、18.99 Bq/kg（范围值0.41~92.57 Bq/kg）、386.39 Bq/kg（范围值31.30~1095.50 Bq/kg）,均显著低于全国和世界的平均值.在测得的238U、232Th、40K含量基础上,计算了距地面1 m高处空气中γ辐射吸收剂量率、外照射指数、内照射指数和年有效剂量等参数,并据此对大连市区天然放射性水平进行了评价.空气中γ辐射吸收剂量率（Dr）平均值为39.04 nGy/h,远低于全国（81.5 nGy/h）和世界（80 nGy/h）平均水平.外照射指数、内照射指数平均值分别为0.23、0.12,均远小于国家对建筑材料外照射指数的限值1.年有效剂量为0.048 mSv,远低于世界年平均有效剂量（0.46 mSv）以及公众外照射年有效剂量（1.0 mSv）的限值.评价结果表明,大连市区地表天然放射性辐射处于安全的水平. 相似文献
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对长约70 km引水工程洞线上进行的地面伽马能谱测量、陆地伽马剂量率测量、土壤氡浓度测量、岩石表面氡析出率测量以及钻孔岩芯样品的放射性元素U、Ra、Th、K含量分析的综合放射性地质调查,并对获得的测量数据进行分析研究。结果表明,测区引水沿线地质体放射性核素当量含量平均值为：U 1.56×10-6,Th 14.12×10-6,K 2.16×10-2;钻孔岩芯放射性元素分析含量平均值为：U 32.34 Bq/kg,Ra 35.68 Bq/kg,Th 35.29 Bq/kg,K 865.65 Bq/kg。陆地伽马剂量率为90.42 nGy/h;土壤氡浓度平均值为4 272.1 Bq/m3;岩石表面析出率平均值为4.01×10-2 Bq/m2·s。根据测量结果,利用内照射和外照射辐射剂量计算了对施工人员造成的辐照剂量为0.759 mSv,低于国家对公众的剂量限值1 mSv/a,表明引水工程输水隧洞的施工在安全辐射范围内。 相似文献
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以1∶25万化探数据为切入点,在分析全国各城市天然放射性水平特征的基础上,运用放射性填图评价技术研究了成都平原天然放射性水平分布特征。结果表明:研究区环境天然放射性核素238 U、232 Th、40 K含量频数均呈正态分布,数值均在正常本底范围内;238 U比活度总体上低于全国平均水平,232 Th和40 K比活度总体上高于全国平均水平;研究区天然放射性辐射水平、γ射线照射量率、吸收剂量率、年有效剂量当量均低于世界和全国的平均水平;研究区γ射线内、外照射指数均在国家限量标准控制范围之内。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level 相似文献
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正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7), 相似文献
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正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci- 相似文献
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正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli- 相似文献
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正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.) 相似文献
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正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861 相似文献