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1.
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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为了对江西某地区水中总α,总β放射性进行监测,对该地区的河水和井水进行采样,将样品分别进行浓缩、转移、洗涤、灼烧,经马弗炉高温灰化,采用BH1216低本底α、β测量仪测量水中总α、β放射性浓度。测量结果显示,井水水样总α、总β的平均比活度分别为0.045 9 Bq/L与0.110 2 Bq/L;河水水样总α、总β的平均比活度分别为0.079 9 Bq/L与0.146 8 Bq/L,平均值均符合国家标准,少数井水样品与河水样品的总α比活度超过了国家标准。 相似文献
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福建牛头山火山口岩石中的放射性核素 总被引：1，自引：0，他引：1
用 HPGe－γ谱方法测定了在福建省牛头山火山口采集的岩石中的放射性核素 238U、210Pb、228Th、228Ra和 40K，样品有玄武岩和花岗岩，结果给出6种核素的比活度为1.6～94.7、LD为30.5 Bq/kg、LD为26.6 Bq/kg、3.3～106 Bq/kg、4.9～113 Bq/kg 和28～1267 Bq/kg，平均为13.5 Bq/kg、5.5 Bq/kg、8.9 Bq/kg、13.0 Bq/kg、16.1 Bq/kg和293 Bq/kg。按放射性核素含量水平可以将玄武岩样品分为两个组。第1组样品中6种核素的含量平均为21.0 Bq/kg、14.8 Bq/kg、14.7 Bq/kg、26.0 Bq/kg、29.8 Bq/kg 和 749 Bq/kg；第2组样品中6个核素含量平均为7.0 Bq/kg、2.0 Bq/kg、6.0 Bq/kg、4.9 Bq/kg、7.7 Bq/kg和142 Bq/kg；花岗岩中6种核素的含量平均为57.7 Bq/kg、19.0 Bq/kg、21.7 Bq/kg、67.4 Bq/kg 和 894 Bq/kg。含量水平为：花岗岩大于第1组玄武岩第一组玄武岩大于第2组玄武岩。 相似文献
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为探讨放射性核素对沉积速率、沉积环境变化以及重大环境历史事件的指示作用,本文首次报道了用HPGeγ谱仪测定黄河口新生湿地柱状沉积物中6种放射性核素活度的结果,并根据137Cs的垂直分布估算了沉积速率,探讨了放射性核素与有机质的关系及其垂直变化与沉积过程变化的对应关系。结果表明,黄河口新生湿地柱状沉积物中6种放射性核素的平均比活度分别为40K(687.33±54.59)Bq/kg、137Cs(8.60±1.35)Bq/kg、226Ra(29.96±4.23)Bq/kg、228Ra(69.96±6.63)Bq/kg、228Th(45.35±4.58)Bq/kg和238U(60.52±15.37)Bq/kg,与其他区域相比,黄河口新生湿地137Cs、238U含量偏高。除137Cs外,其他5种核素均与TOC呈显著正相关,表明有机质有利于核素在沉积物中的保留。137Cs的垂直分布与黄河口净造陆速率的年际变化具有一致性,据此估算获得近20年该区域平均沉积速率为2.8cm/a,其中河口湿地形成初期沉积速率较高,而后逐渐减小并保持相对稳定。放射性核素比活度的垂直变化可反映沉积过程中黄河断流、黄河调沙以及大的洪水等重大环境事件,可以作为指示沉积变化特征的重要指标。 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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《地下水》2019,(6)
依据《生活饮用水标准检验方法放射性指标》(GB/T 5750.13-2006)对淄博部分地区地下水总α、总β放射性活度浓度进行了检测,并参考世界卫生组织《饮用水水质准则》(第四版)进行由饮水所致居民内照射剂量估算可知:15个地下水样品总α活度浓度范围为0.017～0.215 Bq/L,均值为0.079 Bq/L;总β活度浓度范围为0.043～0.424 Bq/L,均值为0.110 Bq/L,总放射性活度浓度均不超过《生活饮用水卫生标准》(GB 5749-2006)总放射性指导值。GW2、GW14和GW15年有效剂量估算值超过个人剂量标准0.1 mSv/a,应进一步确定放射性核素种类及浓度,对地下水开展持续有效的水质监测,掌握地下水水质动态变化,将居民饮水纳入城镇供水管网以保障饮水安全。 相似文献
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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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贵州省含煤渣建材的放射性污染调查 总被引：6，自引：0，他引：6
调查研究了贵州省主要煤田及贵阳地区部分小煤矿中天然放射性核素含量水平，叙述了利用煤渣作建筑材料所产生的巨大社会效益和经济效益。阐明了根据煤灰（渣）的天然放射性核素含量水平进行分类管理的重要性，分析煤灰（渣）作建筑材料存在的一些问题，对可能产生的放射性污染提出防治对策。 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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Radiometric measurements were carried out for the beach sands from East Rosetta estuary to determine the activity concentrations of 238 U, 226 Ra, 232 Th, and 40 K, using a Hyper Pure Germanium spectrometer, to estimate the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238 U; 646.89 Bq/kg for 226 Ra; 621.92 and 627.85 Bq/kg for the 222 Rn daughters 214 Pb and 214 Bi respectively. The average specific activity of 232 Th is 1510.25 Bq/kg, while the calculated specific activity for 40 K has an average of 8.41 Bq/kg. The average specific activity of 235 U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 times higher than the estimated average global primordial radiation of 60 nGy/h and 6 times higher than that of the world range (10-200 nGy/h). The radium equivalent (Ra eq ) values are from 6 to 9 times the recommended value. The internal and external hazard indices (H int , H ex ) indicate that their values are from 6 to 11 times the permissible values of these indices. These higher values may be due to the presence of economic heavy minerals containing radionuclides as zircon and monazite as well as some trace minerals, thorite and uranothorite. The mineralogical study indicates the beach sands contain heavy minerals, zircon, monazite, rutile, ilmenite, leucoxene, magnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from 0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from 0.001 wt% to 0.007 wt% for monazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilmenite; 1.084 wt% for magnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet. 相似文献
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《Chemie der Erde / Geochemistry》2014,74(4):749-764
One hundred and twenty one samples from every major plutonic body (mainly granitic) of Greece have been analyzed by γ-ray spectrometry to determine the specific activities of 238U, 232Th and 40K (Bq/kg). The range of the activity concentrations of these radionuclides was 2.3–266.4, 1.8–375.5 and 55.0–1632.0 Bq/kg and their average values were 79.2, 85.3 and 881.4 Bq/kg respectively. Any possible connection between the specific activities of 238U, 232Th and 40K and some characteristics of the studied samples (age, rock-type, colour, grain-size, occurrence and chemical composition) is investigated. Samples of particular colour, rock-type, occurrence and chemical composition have been identified for their distinctive levels of natural radioactivity, while age and grain-size do not affect the concentrations of 238U, 232Th and 40K. The range of the Th/U ratio was 0.7–12.69. This great variation in the Th/U ratios, especially when it is found among the samples of the same pluton, is also discussed and explained by alteration and tectonic–metamorphic processes. 相似文献
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利用 PRM-2100氡子体监测仪对重庆市丰都县雪玉洞氡子体平衡当量浓度进行连续12个月的监测。研究表明：（1）雪玉洞洞内氡子体平均平衡当量浓度为2135.7 Bq/m3;取平衡因子为0.5,则其平均氡浓度为4271.4 Bq/m3;（2）氡子体平衡当量浓度总体呈现出夏季高、冬季低及洞层越高,浓度越高的特点,而且氡子体平衡当量浓度变化与洞内温度变化相关性不明显,但与洞外的相关性则较强;（3）雪玉洞游客因吸入氡子体所致的年均有效剂量当量为0.02 mSv/a,只是联合国原子辐射效应科学委员会（UNSCEAR）估计的氡子体对公众产生危害的年有效剂量界限值（1.30 mSv/a）的1.54%,因此短时间游览对游客的健康不会产生影响。但是,由于洞穴讲解员、保安、拍照人员在洞内工作时间较长,接受氡子体照射的年均有效剂量当量分别为7.69 mSv/a、11.96 mSv/a、59.48 mSv/a,均高于UNSCEAR 的年有效剂量。因此,需要合理安排洞穴内工作人员工作时间和科学地制订出他们的年工作时间上限;加强氡危害相关知识的普及与洞穴工作人员的个人防护;在高氡浓度析出区域进行屏蔽防护或在适当位置安装空气净化器;与此同时,还要加强氡及其子体浓度的分析和监测等。 相似文献
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Relatively high activity concentrations of some radionuclides (226Ra, 238U, 232Th, and 40K) have been measured in surface and subsurface soils in areas (southern Iraq) where many warfare actions have taken place during the Iran–Iraq and Gulf wars. Such high activity concentrations might be related to the increase in cancerous injuries and birth defects recently reported. The study was aimed to estimate the activity concentrations of some nuclides and a comparison of results with international health hazard indices. In addition, the excess lifetime cancer risk (ELCR) was assessed. Soil samples were collected at three depths (0, 30, and 60 cm) in three locations in Abu Al Khasib and Ad Dayr in Basrah governorates. The average activity concentrations were estimated employing hyper-pure germanium HPGe gamma-ray detection technology. The values obtained in Abu Al Khasib were: 58.44 Bq/kg (226Ra), 43.56 Bq/kg (238U), 19.38 Bq/kg (232Th), and 321.76 Bq/kg (40K) whereas in Ad Dayr 45.71 Bq/kg (226Ra), 35.53 Bq/kg (238U), 20.33 Bq/kg (232Th), and 337.02 Bq/kg (40K). According to UNSCEAR (Sources and effects of ionizing radiations: a report on the effects of atomic radiation to the general assembly with scientific annexes, Annex B, United Nations, New York, 2000) report, higher levels of 226Ra, 238U concentrations than the world’s average values (35 Bq/kg) were observed in both locations. In addition, some radiation hazard indices were determined for both locations: average outdoor external dose (D out), average indoor external dose (D in), total average value of the external dose (D tot), average annual outdoor effective dose (E out), average annual indoor effective dose (E in), and averaged total annual effective dose (E tot). Values for D tot and E tot were higher than the worldwide median (143 nGy/h and 0.48 mSv/y, respectively) in both regions. The measured values of activity concentrations were also used to estimate the outdoor, indoor, and total ELCR. The ELCR values were higher than the worldwide averages. Further analyses and studies need to assess the real risks for human health and possible soil remediation. 相似文献
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Low reference inventories of the fallout radionuclide 137Cs in low latitudes may limit its present and future application for studies of soil erosion and sediment redistribution in Southeast Asia. 137Cs reference inventories and concentrations in surface materials measured in nine and five areas, respectively, across Southeast Asia are here reported and reviewed. The compiled reference inventories decrease from north to south. Three global estimates of 137Cs total fallout are also reviewed and compared to the measured data while taking into account factors that affect the fallout estimates and the reference inventory. The results are presented as a schematic regional distribution map of 137Cs reference inventories for the year 2012. A relationship between a reference inventory and topsoil concentration is also provided. The measured 137Cs concentrations suggest that a minimum detectable activity (MDA) less than 0.5 Bq/kg is required for detection of 137Cs activity in topsoils in the lowest reference inventory areas. This sensitivity should allow, at present, 137Cs to be a useful tool for analysis of soil erosion in Southeast Asia, should also be a useful chronometer, and will be a useful tracer at least where the reference inventory is more than 500–600 Bq/m2. This level of MDA has been demonstrated in previous studies to be achievable by gamma-ray spectrometry using non-destructive sample treatment. As the nuclide decays, sufficient will remain to be useful until the middle of this century in most areas in Peninsular Malaysia and southern maritime Southeast Asia, and a few decades more in the rest of the region. 相似文献
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Dissolved Rn was determined in 192 samples collected from cold shallow volcanic and sedimentary aquifers, deep thermal aquifers and from waters associated with bubbling gases in the western sector of the Sabatini Volcanic District and the Tolfa Mountains (central Italy). Shallow aquifers hosted in the Quaternary volcanic complexes show values ranging from 1.0 to 352 Bq/L (median value 55 and inter-quartile distance 62 Bq/L), while waters circulating within the permeable horizons of the sandy-to-clayey sediments of the Tolfa flysch have values from 1.0 to 44 Bq/L (median value 6.9 and inter-quartile distance 8.1 Bq/L). Thermal waters are hosted in the Mesozoic carbonate formations and move towards the surface along faults. Here, dissolved Rn values range from 0 to 37 Bq/L (median value 3.0 and inter-quartile distance 9.5 Bq/L). Waters associated with bubbling gases show dissolved Rn contents ranging from 2.0 to 48 Bq/L (median value 6.2 and inter-quartile distance 23 Bq/L). Those results suggest that lithology is the main factor affecting the Rn contents in shallow aquifers, due to the high levels of Rn progenitors U and Ra in the volcanic rocks relative to sedimentary units. The influence of other factors such as the presence of a fracture network, seasonal flow variations, type of discharge (from well or spring) was also investigated. Radon contents of thermal waters result from mixing with shallow waters (from both volcanic and sedimentary rock aquifers) and decrease of Rn solubility with temperature, while for bubbling pools the effects of strong degassing were also considered.In terms of health hazard from direct ingestion of Rn-rich waters, 20.8% of those circulating within the volcanic aquifer show values higher than the recommended value of 100 Bq/L, while none of those circulating within the sedimentary aquifers exceed the threshold value. Geostatistical techniques were used for the elaboration of contour maps by using variogram models and kriging estimation aimed at defining the areas where a potential health hazard due to the direct ingestion of Rn-rich waters and to inhalation of air following degassing of Rn from waters may be expected. 相似文献