中国高本底城市的土壤氡水平及分布

在广东珠海地区采用便携式半导体测氡仪进行了大比例尺土壤氡浓度调查,测点数469个,面积大于100km2。珠海地区地下0.6 m处的平均土壤氡浓度为55.94±58.54 kBq/m3,其中在珠海斗门的第四纪沉积物地区、沉积物和风化花岗岩混合地区,以及风化花岗岩地区的土壤氡浓度分别是7.14±8.75,37.64±25.92和151.25±196.23 kBq/m3。高氡潜势区主要分布在黑云母花岗岩、风化花岗岩地区和新的工业开发区,且表现出与当地岩性密切相关。城市化和工业化改变了原有的天然辐射背景。珠海市区的平均土壤氡浓度分别为广州、泉州和晋江市平均值的8.3倍和15倍。研究结果表明：珠海是一个氡潜势较高的区域,需要进一步开展辐射防护目的的氡测量。     

资源地区空气氡浓度调查与剂量估算

对广西资源地区大气中氡的调查结果显示，该区室内、外大气中平均氡浓度分别为101.0Bq/m^3和104.6Bq/m^3，是世界平均值的10倍和2.5倍；计算了氡子体所致的年有效剂量，由氡子体照射对成人和儿童所致年均有效剂量分别为6.2mSv/a和9.2mSv/a，是世界平均值的5倍。     

固体径迹探测技术在环境氡监测中的应用

对醋酸纤维素和CR-39探测器进行比较研究,在确定两种探测器的蚀刻条件和改进径迹计数方法的基础上,对CR-39探测器进行刻度,刻度系数为0.035 Tc/cm2/Bq.h/m3。应用固体径迹测氡方法对安阳地区和成都市室内外氡浓度进行测量,结果表明安阳地区室内外氡浓度范围在13.0 Bq/m3~54.2 Bq/m3之间,成都市室内外氡浓度范围14.1 Bq/m3~43.2 Bq/m3之间,低于GB/t16146-1995规定的氡浓度标准。监测过程发现,装饰地板材料是影响室内氡浓度的一个主要因素,水泥厂、钢铁厂等工业污染是影响室外氡浓度水平的重要因素。     

四川阿坝土壤与空气中氡气浓度及分布调查

采用IED-3000R轻便型测氡仪,对四川阿坝地区土壤、空气中的氡气浓度开展初步调查。结果表明：(1)测区空气中氡气浓度较高,均在平均值185 Bq/m3附近;(2)所测得土壤的氡气浓度范围为2 736～93 486 Bq/m3,平均值为26 021 Bq/m3,远远高于全国城市土壤中氡气浓度7 300 Bq/m3的平均值,同时在156个土壤氡气浓度被测点中共有91个测点氡气浓度值超过20 000 Bq/m3,而按照国家标准,对于民用建筑工程土壤中氡气浓度超过20 000 Bq/m3要进行不同程度的防氡工程;(3)地质环境、土壤松散度、岩土性质、土壤含水率为影响阿坝地区土壤氡气浓度的主要因素。     

奥西耶克室内氡剂量评价

经过10年对3个不同测点氡季节性变化的调查，以及幼儿园，学校，防空掩蔽所和地窖氡浓度的测量后，对奥西耶克（东克罗地亚，130000户居民）的住宅（住宅建筑）进行了系统的室内氡测量，用LR－115固态径迹探测器在城镇48个测点上测量了室内氡，给出了算术平均值为71．6Bq.m^-3,标准偏差为44．0Bq,m^-3,和几何平均值为60．1Bq.m6-3，其冬浓度范围从22．7到186．5Bq.m^-3,由Radhome硅探测器进行的氡测量差异并不大，氡浓度的经验频率分布（分组宽度20Bq.m^-3)与x^2检验示出的理论对数正态分布相一致，氡图指指出了由地质土壤构造造成的氡浓度较高的区域（该城镇的中部）。上述提及住宅中氡及其子体的平衡因子为0．44，有些氡模型的有效剂量当量估计数接近2mSv.a^-1.     

乌鲁木齐某实验楼室内氡浓度测量及影响因素分析

对乌鲁木齐某实验楼室内氡浓度的测量结果表明,该实验楼室内氡浓度在39～137 Bq/m3,平均76.1 Bq/m3,吸入氡及其子体对相关人员的年均有效剂量为0.51～0.68 mSV,平均值为0.57 mSV,高于乌鲁木齐平均水平,推测与研究区活动断层出露有关。分析数据显示,研究区地下土体扩散氡对一层室内氡浓度影响较大,导致一层室内氡浓度较高,且室内氡浓度在一定程度上受到房屋朝向影响。并结合影响因素,有针对性的提出了预防和降低室内氡浓度的措施。     

广州市民用建筑工程室内氡浓度水平与剂量估算

通过分析2003年广州市部分新建民用建筑工程室内氡浓度检测数据，评价了目前广州市新建民用建筑室内氡浓度的水平，并以此估算广州市居民的年平均有效剂量。结果表明，广州市民用建筑工程室内氡浓度算术平均值为60．5Bq／m^3。氡子体照射所致的人均年有效剂量，成人和儿童分别为1．67，2．34mSv，高于世界平均值(1．3mSv)。     

广东花岗岩类温泉水-汽转化过程中氡浓度的变化及其危害

广东省是我国温泉出露最多的省份之一。在温泉附近建立温泉宾馆,是利用温泉资源大力发展本地旅游业的有效途径之一。本文利用新型NR 667A连续测氡仪测量了广东省4处温泉宾馆室内外空气中氡浓度以及室内温泉水氡浓度。温泉水氡浓度变化范围为53 4～292 5Bq L,室外氡浓度范围是17～48Bq m3,而客房内平均氡浓度水平比没有用温泉水时高出10 9%～813%,浴室内氡浓度比没有用温泉水洗浴时高出13 8%～516%。在宾馆室内使用温泉水有较高的氡转换系数。某些宾馆室内氡浓度超标,可能对宾馆工作人员造成潜在健康危害,应采取一些管理措施或技术手段降低其暴露时间或程度。     

广东温泉水-汽转化过程对室内氡浓度的影响

研究了广东省四家温泉宾馆室内温泉水及其使用过程中对氡浓度的影响。利用RAD-7测氡仪和NR667A测氡义连续测量室内外氡浓度和水氡浓度,发现室内氡浓度受地基土壤、建筑物类型、利用方式(是否洗浴、洗浴时间长短等)、通风状况等诸多因素的影响。无人入住时宾馆室内氡浓度的变化说明土壤氡的渗入是底层房间室内氡的重要影响因素。当在浴室内使用温泉水洗浴时,浴室内平均氡浓度比没有用温泉水时高出1～8．3倍,客房内氡浓度比没有用温泉水洗浴时高出1．2～8．3倍。在使用温泉水时,某些宾馆室内氡浓度超标,可能对宾馆工作人员造成潜在的健康危害,应采取管理措施或技术手段降低其暴露水平。     

台山市某地块环境放射性水平研究

本主要测量了广东省台山市某地块的现场地面γ强度、空气氡浓度、土壤氡浓度、水中氡浓度，以及水中微量元素。结果表明，测区内大部分区域地面γ强度为256．1－522nGy/h，个别地段的地面γ强度大于522nGy/h；测区内水中氡浓度一般为0．28－5．31kBq/m^3，个别大于10kBq/m^3，测区内土壤中氡浓度较高，分析表明，测区内地面γ强度和氡浓度偏高的原因除了与地质因素有关外，还与地形等因素有关，最后对该地块放射性水平作出综合评价，提出相应的防护措施。     

Geochemistry of granites and metasediments of the urban area of Vila Real (northern Portugal) and correlative radon risk

Radon concentration was evaluated in dwellings of the urban area of Vila Real (Northern Portugal). The area is mainly composed of Hercynian granites and Cambrian metasediments, and CR-39 passive detectors (n = 112) were used for the purpose. The results obtained in winter conditions suggest that the most productive geological unit is the Hercynian granite G1 (geometric mean of 364 Bq/m³), while Cambrian metasediments of the Douro Group show the lowest average indoor radon concentration (236 Bq/m³). The geological, geochemical and radiological data obtained suggest that the most effective control on the radon concentrations of the area is related with the uranium content of the rocks; indeed, the highest contents were observed in granite G1 (21 ppm) and the lowest in the metasediments (3 ppm). This is also confirmed by the results obtained for groundwater, where granites present the highest concentrations of dissolved radon (up to 938 Bq/l), uranium (5–18 ppb) and gross α activities (0.47–0.92 Bq/l). No important radiometric anomalies were found in relation with geological structures such as faults, veins and contacts, but a moderate increase of the uranium content can occur locally in such structures. Petrographic observations and SEM studies show that uranium is mainly contained within the rock in heavy accessory minerals (apatite, zircon, monazite, xenotime), which reduces radon emanation. Notwithstanding, due to the high U contents granites show a significant potential to induce indoor radon concentrations in dwellings in excess of the recommended value of 400 Bq/m³. Overall, we can conclude that the region of Vila Real presents a moderate to high radon risk in dwellings and groundwater.     

Radon distributions in the Hail Region of Northern Saudi Arabia

Indoor radon measurements were carried out in a total of 420 dwellings and 17 schools in Hail region of Saudi Arabia, using NTDs based radon dosimeters. The duration of the measurements was one year, from April 2008 to April 2009. The indoor radon concentrations varied from 4 to 513 Bq/m³ with an overall average of 45 Bq/m³ for all surveyed dwellings. These passive measurements were confirmed by the active measurements. The anomalous concentrations above 200 Bq/m³ were observed in 13 dwellings, representing 3.1 % of the total surveyed dwellings. In Inbowan village alone, it was found that 7.6 % of the dwellings have indoor radon concentration above 200 Bq/m³. The highest average indoor radon concentration of 64 Bq/m³ was found in Inbowan village while the lowest average of 24 Bq/m³ was found in Majasah village. The city of Hail showed an average indoor radon concentration of 49 Bq/m³. The average indoor radon concentration in one area located at the edge of the Aja Mountain in Hail city was 111 Bq/m³. The elevated indoor radon concentrations in many dwellings in the Hail region, prompted us to measure outdoor ground radon in such locations using gas monitor. It was found that radon concentrations at a depth of 0.5 m varied significantly from place to place ranging from 1.2 to 177 kBq/m³. The outdoor radon concentrations are generally correlated with the indoor radon measurements. Radon exhalations from construction materials and soil samples from the Hail region were also measured. It was found that radon exhalations from soil samples are higher than that of construction materials by a factor of at least 3 and reaching up to 11. These results indicate that soil is the main source of indoor radon. Geological interpretations of the results are also given.     

Spatio-temporal variation in radon concentration in groundwater with respect to rock types: A case study from Chitradurga district,Karnataka

An attempt was made in the present study to delineate how the radon concentrations vary with respect to different geological formations and to evaluate annual effective dose exposure due to ingestion of radon. A total of 60 groundwater samples were collected from layered sequential aquifers in Chitradurga district having major rock types such as Bababudan Group, Charnockite, Chitradurga Group, Closepet granite, migmatites and granodiorite — tonalitic gneisses and Sargur Schist complex during pre-monsoon and post-season of the year 2011. Radon measurement was made using Durridge RAD-7 radon-in-air monitor, connected to RAD H₂O accessory with closed loop aeration concept. In the present study, the radon activity ranged from 0 to 186.6 Bq/L and 0 to 150.6 Bq/L during pre- and post-monsoon seasons of the year 2011, with 56.67 % (17 samples) of samples during both the seasons exceeding the EPA’s MCL value of 11.1 Bq/L. The annual mean radon activity in the groundwater was higher in the area having Chitradurga rock group formations (78.1 Bq/L) followed by Sargur-Satyamangalam schist complex group (56.8 bq/L), migmatites and granodiorite — tonalitic Gneisses group (56.3 Bq/L), Closepet granite (42.7 Bq/L), Charnonkite (29.1 Bq/L) and Bababudan Group (22.2 Bq/L). It is inferred that radon concentration found to depend on the tectonic structure, geology of the area and on the presence of uranium minerals in these rocks. The annual effective dose resulting from radon in groundwater in the Chitradurga district were significantly lower than UNSCEAR and WHO recommended limit of 1 mSv/y.     

Geological and geochemical factors affecting radon concentrations in dwellings located on permeable glacial sediments—a case study from Kinsarvik,Norway

In 1996–1997, indoor radon values of more than 40,000 Bq/m³ and large seasonal and geographical variations in indoor air radon were reported from a residential area located on a highly permeable ice-marginal deposit. Geochemical analyses of bedrock, groundwater and sediments and comparisons between indoor radon values and soil radon values indicate that the indoor radon concentrations in this area are strongly affected by subterranean airflows caused by temperature differences between soil air and atmospheric air. The airflows concentrate the radon-laden soil air towards the topographic highest part of the deposit in winter and towards the topographic lowest part in summer. In areas where subterranean airflows are likely to occur, radon measurements performed both in summer and in winter provide the best estimate of annual average indoor radon concentrations, and assessments of indoor radon concentrations based on single soil gas measurements are not recommended.     

The influence of geological factors on radon risk in groundwater and dwellings in the region of Amarante (Northern Portugal)

The region of Amarante (Northern Portugal) is composed of Hercynian tardi-tectonics granites and Paleozoic metasediments. Petrographic observations and SEM studies show that uranium is mainly contained within the rock in heavy accessory minerals such as apatite, zircon, monazite, uraninite, thorite and thorianite. The geological, geochemical and radiological data obtained suggest that the radon concentrations in dwellings of the studied area are mainly related with the uranium content of the rocks. Indeed, the highest contents were observed in granite AT2 of Padronelo (18.2 ppm) and the granite AT1 of Telões (10.3 ppm), with metasediments showing much lower uranium contents of 1.6 ppm; radon concentrations were evaluated in dwellings, using CR-39 passive detectors, and the results obtained in winter conditions suggest that the most productive geological units are the granites AT2 and AT1, with geometric means of 430 and 220 Bq/m³, respectively, while the metasediments show the lowest value of 85 Bq/m³. Some moderate radiometric anomalies, where uranium contents can double typical background values, were found in relation with specific fault systems of the region affecting granitic rocks, thus increasing radon risk; this is an indication of uranium mobility, likely resulting from the leaching of primary mineral supports as uraninite. Groundwater radionuclide contents show a wide range of results, with the highest activities related with granitic lithologies: 2,295 Bq/l for radon, 0.83 Bq/l for gross α and 0.71 Bq/l for gross β, presenting metasediments much lower values, in good agreement with other results obtained. Absorbed dose measured with gamma spectrometers in direct contact with the rocks is directly related with the uranium contents of the rocks, and thus works as a fast proxy for radon risk. It is concluded that radon risk is moderate to high in the granitic areas of the Amarante region and low in the metasediments of the same region.     

Geochemistry and ground permeability as determinants of indoor radon concentrations in southernmost Sweden

A study of the indoor radon gas levels was performed in 935 homes in Scania, southernmost Sweden, located on geologically different ground with regard to uranium (U) content. In one of these two areas the bedrock consists of alum shale with U contents exceeding 200 ppm. In the other area there is no U-rich bedrock. Indoor radon levels are influenced by U content and permeability as shown below.For maam nancy for table, please place here. Thanx!The results show that the indoor radon levels were highest in homes located on bedrock with medium to high U content combined with a highly permeable drift covering the bedrock. The difference was statistically significant(P < 0.0001). Other results of the investigation are: 14 homes built from aerated concrete made from U-rich alum shale had higher levels than 767 homes with walls from other material (312 vs 106 Bq/m³;P = 0.0011); 242 homes with a cellar had lower radon levels than 563 without (62 vs 138 Bq/m³;P <0.0001); further, 418 homes with private well had higher levels than 360 with public water supply (140 vs 82 Bq/m³;P <0.0001). The results of the investigation show a profound effect of a combination of high bedrock U content and high cover permeability. The effect of the uraniferous drift on the indoor radon levels is evident. Thus, the geological conditions should be carefully considered when screening for high-risk buildings, as well as when planning for new ones. Also, the construction of the building and its water supply have some influence.     

氡地质潜势规律研究方法探讨

氡的地质潜势是环境氡研究的重要内容,也是从地质背景出发快速评价氡浓度水平的有效方法,氡析出率是反映氡地质潜势的最好参数,根据放射性元素分布规律,地质背景及放射性元素衰变等,建立了计算氡析出率的理论公式。理论计算结果表明,北京市区氡的地质潜势分为四个不同的区,不同潜势区中室内氡浓度水平发生相应变化。说明通过氡地质潜势规律研究,可以确定室内氡浓度水平潜在高值区。