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1.
The activity concentration and the gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides (232Th, 226Ra and 40K) were determined in soil samples collected from ten different locations of Sirsa district of Haryana, using HPGe detector based on high-resolution gamma spectrometry system. The range of activity concentrations of 226Ra, 232Th and 40K in the soil samples from the studied areas varies from 19.18 Bq kg−1 (Moriwala) to 40.31 Bq kg−1 (Rori), 59.43 Bq kg−1 (Pipli) to 89.54 Bq kg−1 (Fatehpur) and 223.22 Bq kg−1 (Moriwala) to 313.32 Bq kg−1 (SamatKhera) with overall mean values of 27.94, 72.75 and 286.73 Bq kg−1 respectively. The absorbed dose rate calculated from activity concentration of 226Ra, 232Th and 40K ranges between 8.84 and 18.58, 37.02 and 55.78, and 9.24 and 12.97 nGy h−1, respectively. The total absorbed dose in the study area ranges from 60.40 to 82.15 nGy h−1 with an average value of 70.12 nGy h−1. The calculated values of external hazard index (H ex) for the soil samples of the study area range from 0.36 to 0.49 with an average value of 0.42.  相似文献   

2.
Alpha-spectrometric technique is described as an independent method for determining micro-contents of U238 and Th232. It is based on the comparison of alpha spectral activity of U238 and Th232 in geological samples with that contributed by the U232·Th228 spike of known concentration. The experiment procedure consists of dissolving fine powdered samples with acid and adding a given amount of U232-Th228 spike. Uranium and thorium are then separated by ion exchange. After purification, each aliquot is mounted onto a separate stainless steel disk for measurement by alpha spectrometer, which consists essentially of a silicon surface barrier detector and a low noise amplification system connected to a multi-channel analyzer. After corrections for the background, tail and other factors, the desired U232 and Th232 concentrations can be calculated. The data obtained by the alpha-spectrometric method using U232-Th228 spike are compared with colorimetric determinations. Excellent agreement is obtained between the two sets of results. The coefficients of correlation are about 0.98 for U238 and 0.97 for Th232. The accuracy of uranium and thorium analyses by this method depends primarily upon the counting statistics of U232, U238 and Th228 and, to a certain extent, upon the calibration of U232-Th228 spike. Errors in uranium and thorium concentrations obtained by this method are generally within 2 to 5%.  相似文献   

3.
《International Geology Review》2012,54(10):1548-1557
Thickness of consolidated crust, depth of the magmatic differentiation, and partial pressure of oxygen during the differentiation are found to be the principal factors on which the ultimate concentrations of U and Th depend, in the Siberian traprocks. Enrichments of both U and Th in late differentiates of the magma develop at about the same rate, if PO2 remains unchanged during the process, i.e. as long as U remains essentially tetravalent. The oxidation of U to hexavalent state at increasing PO2, and hence the increase in its mobility, leads to a dissipation of uranium and lowers its concentration in the late fractions of the magma, while the concentrations of thorium remain unaffected therein.  相似文献   

4.
The determination of rare earth elements (REEs), Th and U in seaweeds of various species and in ambient surface seawater were performed by inductively coupled plasma mass spectrometry. The seaweeds and the seawater samples were collected at 10 different coastal areas of Niigata Prefecture in Japan twice a year (spring and autumn) in 2004 and 2005. Results showed that concentration of REEs in seaweed species from Niigata Prefecture were about 103 times higher than those in seawater, and the enrichment factors of REEs were larger in heavy REE than light REE. A significant concentration difference of REEs, Th and U was found among species even in the same phylum. Undaria pinnatifida had the highest concentration of U. Considering that U. pinnatifida has low concentrations of REEs among typical brown algae, different REEs and U uptake mechanisms are suggested. The concentration of REEs, Th and U did not vary remarkably between sampling points and/or seasons.  相似文献   

5.
6.
Delayed neutron measurements of U and Th in three meteorites yield the following values:
  相似文献   

7.
石墨炉原子吸收光谱法测定土壤样品中镉   总被引:5,自引:0,他引:5  
卞莉  曹萍 《吉林地质》2005,24(2):115-117
采用磷酸氢二铵作基体改进剂塞曼扣背景石墨炉原子吸收光谱法测定土壤样品中镉,方法检出限DL=0.012μg/g,精密度RSD在3.55%~7.33%,满足了土壤样品中镉测定的镉质量要求。  相似文献   

8.
《Applied Geochemistry》2003,18(4):539-549
This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a “pseudo” isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapid analysis on a single digestion of sediment sample and the potential of adding other elements of interest if so desired. Application of this method to two piston cores collected near the mouth of the Patuxent River in Chesapeake Bay showed that the accumulation of authigenic Mo and Cd varied in response to the changing bottom water redox conditions, with anoxia showing consistent oscillations throughout both pre-industrial and industrial times. Accumulation of authigenic U shows consistent oscillations as well, without any apparent increase in productivity related to anoxic trends. Degrees of Mo and Cd enrichment also inversely correlate to halophilic microfaunal assemblages already established as paleoclimate proxies within the bay indicating that bottom water anoxia is driven in part by the amount of freshwater discharge that the area receives.  相似文献   

9.
目前,砂岩型铀矿成分的测定,一般主量元素采用常规化学法,铀、钍含量采用ICP-AES测定.本文采用熔融制样,用Axiox max型波长色散X射线荧光光谱仪一次性测定砂岩型铀矿中主量及铀、钍成分.利用玻璃熔片法可以有效地消除砂岩型铀矿样品的非均匀性及颗粒度等矿物效应.采用混合熔剂Li2B4O7-LiBO2-LiI(m/m/m=66.67/32.83/0.50)在1050℃熔融制样,用铀矿石、岩石、砂岩等国家一级标准物质制成标准样片绘制工作曲线,用理论α系数法校正基体效应.方法经与标准物质检验对照,结果与标样值符合,其准确度、精密度均达到地质行业标准的要求.  相似文献   

10.
为满足随钻方位伽马地质导向钻进需求,通过数值模拟研究围岩厚度和吸收系数不同情况下伽马射线强度响应值。模拟分析伽马探测器在含放射性地层条件下,伽马测量值API反映空间物理特征的差异性。在此基础上,建立八扇区随钻方位伽马钻进煤、泥、灰岩3层地质模型,模拟钻进煤层顶底板识别过程。模拟结果表明:当岩层吸收系数由0.08变为0.10时伽马射线强度减小一半,伽马幅度变化能够反映钻进地层岩性,而上下伽马变化顺序能够指示穿越煤层顶板或底板及分界面所在位置;当小角度穿层时,探测器到钻头的距离分别为1、3、7 m时,能够监测前方钻进8、6、2 m地层物性的变化。顺层钻进模拟可为地质导向工程提供技术指导,提高钻进效率减少无效进尺。   相似文献   

11.
王玉芬  张跃春 《吉林地质》2012,31(1):109-111
本文介绍了电感耦合等离子体发射光谱法测定生物样品中Fe、Ca、Mg、K、Na、P等元素的分析方法,参加了国家植物标准物质定值,结果令人满意。  相似文献   

12.
在可地浸砂岩型铀矿勘查中,地面伽马能谱测量因地表覆盖层等的影响,有效信息往往被掩盖.为有效提取铀矿化信息,对在松辽盆地开鲁坳陷大林铀矿产区采集的地面伽马能谱数据开展钍归一化法处理.获得的铀剩差异常范围与区内铀矿体及断裂的空间展布相吻合.经分析表明,钍归一化法能够有效反映断裂的存在.该区断裂对铀成矿控制明显,区内铀剩差异...  相似文献   

13.
土中矿物成分的类型与含量是软土物理力学性质研究的基础,可以使用微观试验进行研究。本次研究以上海软土为例,使用X射线荧光(XRF)分析得到土中不同元素的含量,使用X射线衍射(XRD)分析和XRF分析得到了晶质矿物的类型,根据元素含量和矿物类型得到不同矿物的含量,对不同土层中矿物含量的分布特征进行了分析。结果表明,上海软土主要矿物中的元素为O,Si,Al,Fe,C,K,Mg,Ca和Na;所有土层中,元素含量最多的是O,其次是Si,主要矿物成分为石英、钠长石、方解石、白云石、伊利石、鲕绿泥石和黑云母,石英的含量最高、含量为35.8%~50.8%,其它矿物的含量均不超过21%;黏性土中,元素Al要略多于砂性土或粉性土,伊利石和鲕绿泥石含量明显高于砂性土或粉性土,钠长石和方解石含量要明显小于砂性土或粉性土。研究结果对从微观上研究不同土的物理力学性质有一定的参考价值。  相似文献   

14.
岩石、土壤样品中210Po测定方法的研究   总被引:1,自引:0,他引:1  
王玉学 《铀矿地质》2005,21(4):248-256
研究了以铜箔为镀片时,自沉积总α计数法定量测定岩石、土壤样品中210Po的最佳制源环境、同位素的干扰和去除、共存元素的允许量以及适宜的溶(熔)矿方法,同时研究了银、铜两种镀片的区别。试验发现,当盐酸浓度为2.0mol/L,恒温80℃,振荡频率为180次/min、振程20mm时,制源2.0h,210Po自镀回收率在99.6%~100.4%之间,210Po加入量与α净计数率线性相关系数为0.9999。放置衰变法可以消除212Bi和218Po等短半衰期核素对210Po测量产生的影响,Vc存在时其它共存元素不干扰测定。方法配合HNO3HFHClO4溶矿(对复杂试样酸溶后的不溶渣,再进行碱熔),全程回收率为99.5%~100.4%。  相似文献   

15.
高云慧  郭子英  张茹 《吉林地质》2011,30(1):116-118
样品经酸溶后,加碘化钾,银以AgI方式存在,有机试剂萃取分离,用原子吸收分光光度计测定有机相中银的含量,测定范围(1~1 000)×10-9。  相似文献   

16.
岩土样本力学参数的模糊统计特征研究   总被引:7,自引:5,他引:7  
徐卫亚  蒋中明 《岩土力学》2004,25(3):342-346
岩土工程参数中的各种信息都存在模糊性。通过对岩土样本力学参数试验值的研究,提出当分析样本统计特征时,应该充分考虑模糊不确定性因素对参数特征值的影响。在确定的参数隶属函数基础上,推导了岩土样本力学参数模糊统计特征值的计算公式,并证明了公式的合理性。应用实例表明,由于文中提出的计算方法考虑了参数模糊性的影响,其计算结果比按常规统计方法得到的结果更具合理性。在任何情况下,模糊方差和模糊变异系数都比常规统计方法得到的方差和变异系数小。分析结果表明,该方法具有广泛的推广价值。  相似文献   

17.
This paper presents data on the age, composition, and origin of rare-metal granites and associated tin tungsten mineralization in the region of the Tigrin deposit, in the Central Sikhote-Alin' mountain range (Primor'ye). These granites were formed in two successive subphases. The porphyritic protolithionite granites constituting the upper stock belong to the first, and the zinnwaldite granites of the lower (Main) stock belong to the second. The age of the granites of the lower and upper stocks (67 and 73.2 Ma, respectively) was determined for the first time, by the Rb-Sr method. The rare-metal granites crystallized from a magma enriched in fluids, rare alkalies, and ore elements. The tin-tungsten ores of the Tigrin deposit, related to these granites, are classified as deposits of the cassiterite-quartz association, but they differ from such deposits in other regions in the extensive development of stannite, the presence of a substantial amount of varlamoffite in the zone of oxidation, and an insignificant amount of sulfides in the presence of extensive development of topaz and lithium-iron micas. Sc-W-Nb minerals were found for the first time-scandium minerals proper, scandian ixiolite, and scandian-tungsten ixiolite occurring in the form of inclusions in wolframite and cassiterite.

In the Tigrin deposit, tin mineralization of the greisen association is genetically related to the rare-metal granites, and extensive vein-veinlet ore zones in hornfels and granites are paragenetically related to them.  相似文献   

18.
文章建立了火焰原子吸收光谱法测定冰晶石中钾的分析方法。样品用高氯酸溶解后,在标准系列加入与待测试液等量的铝和钠来消除样品中大量铝和钠对钾的干扰,用空气-乙炔火焰测定了样品中的钾,测定结果与火焰光度法一致。检出限为:0.057m g/L,相对标准偏差(RSD)为:3.55%-4.14%,回收率为:98.67%-103.2%。  相似文献   

19.
黔中-黔东南地区广泛分布着非常规铀资源,其样品具有组成复杂、疑难程度高的黑色岩系矿床样品特点,利用MUA选择性好、灵敏度高的优越性,采用标准加入法,对黔中一黔东南地区非常规铀进行测量,其结果与ICP—MS测量结果一致。  相似文献   

20.
层析法提取土壤样品中活动态铀及其找矿意义   总被引:1,自引:0,他引:1  
葛玮  朱姝  张鑫 《铀矿地质》2009,25(1):45-49
阐述了层析法提取土壤中金属活动态元素的原理、层析法提取土壤活动态铀的测试结果以及该项技术在内蒙古赛汗塔拉地区、桂北沙子江矿床、粤北MHK矿床的试验效果。将层析法与元素活动态方法中的水溶态铀提取法作了比较,结果表明:两者找矿效果基本相同,但层析法的精密度较好。  相似文献   

BruderheimU (ppb)Th(ppb)
Bruderheim14.5 ± 1.0171 ± 65
Peace River11.8 ± 0.796 ± 46
Stannern220 ± 6563 ± 190
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