化学简讯

瑞士Land大学放射物理系的C.Samuelsson建议,窗、门及镜框玻璃可作为氡的一种记录介质。由于氡的核蜕变产物可能在空气中被捕捉,并认为对人类的肺癌致病有关。Samuelsson发现从室内玻璃取样有助于帮助对氡的辐照积累做出估计。例如半衰期为     

室内空气测量不确定度评定进展

介绍了测量不确定度的研究进展及《民用建筑工程室内环境污染控制规范》(GB 50325-2001)中规定的室内5种空气污染物氡、甲醛、氨、苯、TVOC检测不确定度的评定概况,室内空气污染物测量不确定度的评定还处于较低水平,有待系统研究。     

室内装修材料中的有害物质

本文对室内装修材料中的有害物质———甲醛、苯、氨气、放射性物质氡,从它们的来源、性质、对人体的危害作用、中毒机理等方面做了论述,提出了在室内装修中创造“绿色环境”的具体措施。     

吉林矿泉水放射性水平的调查分析

为了解吉林省矿泉水的放射性水平及分布特点,依据《饮用天然矿泉水标准》,采用FD- 125型室内氡钍测定仪及FH 463A型自动定标器和BH 1217型弱α,β测量仪对5个行政区域矿泉水中226 Ra和总α、总β放射性核素水平进行了测定.结果表明,矿泉水中226Ra、总α、总β的放射性活度范围为5.5～11.4 mBq/...     

痕量氡气测量仪器自动标定装置的研制

研究了空气中痕量氡的动态稳定技术和氡及其子体浓度的准确测量方法.研制了具有氡浓度自动控制、温湿度调控、气溶胶发生/采集等功能的标准氡室,并建立了主氡室标称体积达4 m3的氡测量仪器检定/校准装置和氡子体放射性气溶胶检测与实验研究平台.研究表明,本装置测氡浓度范围为370～20000 Bq/m3;检测精确度达3％;单点校...     

成都市三环地区地基土壤氡含量测量

对成都市三环地区地基土壤中氡含量进行了检测,掌握了区域性氡含量的分布状况,探讨了整个成都市待建地坪基础中的放射性水平,并佐以对成都市地质构造的浅析,为今后城市化进程中的新建、扩建建筑的地下防氡设计提供依据,以最终提升市民的生活环境质量。     

稀土厂废水及其中氡的放射性比活度测量

以直接法和蒸干法制样后用液闪仪测量了稀土厂废水的总(α+β)放射性比活度(Bq.L-1,下称比活度),以萃取法制样后测量了废水中氡的比活度。测量结果表明,在本实验条件下,以直接法和蒸干法制样测得结果有较大差异,废水的总比活均高于排放标准(GB8978-1996),由直接法所得结果远高于标准;三种废水中的氡均具有较高的比活度和放射性比重(80%)。指出了常规方法制样测量结果偏低的原因是忽略了废水中氡的放射性"贡献";讨论了废水中氡的来源、迁移和危害性。为综合评估稀土厂"三废"的放射性及其危害性提供了依据。     

土壤氡浓度随气象因素变化规律及其应用

论述气象因素对土壤中氡气浓度的影响规律。一年的定点观测结果表明,土壤氡浓度在一年四季内变化明显,其变化的总规律是:春、夏浓度低,夏季最低;秋、冬浓度高,冬季最高。降雨、降雪常引起浓度值的骤然升高;而0℃附近,特别是低于0℃的条件下,浓度值大幅度地降低。除有季节性的变化外,尚有日变,其变化规律是:中午浓度低,早晚浓度高。在垂向分布上,存在一个最佳观测深度,在该深度上,氡浓度值最大,且日变化小。这一深度为65—75cm。最后提出了减小和消除气象影响的几项措施。     

几种建筑材料的氡射气系数研究

通过天然γ能谱测量方法测定建材样品中的镭含量,计算理论上衰变产生的氡密度,以及用硫化锌闪烁法测定由样品释放到空气中的氡密度的方法来计算氡的射气系数。通过改变样品的颗粒度大小,以及改变样品的灼烧温度等条件,来研究氡射气系数的变化规律。结果表明,土坯砖射气系数在8.5%~29.4%,红砖射气系数在0.031%~3.5%之间,瓷砖射气系数在0.74%~4.5%之间;建筑材料的氡射气系数随着其自身颗粒度的增大而减小,随加工(灼烧)温度升高而减小。     

主动式活性炭盒法测氡影响因素研究

阐述了主动式活性炭盒法测量环境空气中氡浓度时活性炭吸附效率的影响因素,采用该法对民用建筑工程验收环境空气中氡浓度的大面积多点快速测量提供可靠数据保障。     

Investigations on the presence and distribution of radon in the Cacica salt mine,Romania

An important parameter for evaluating the possibilities of use of enclosed spaces (mines, caves, spas, etc.) for therapeutic purposes is the concentration of radon in different conditions of ventilation. The aim of this paper is to present the results of continuous radon gas measurement that were performed for ten days, at 20 min time intervals in different locations from Cacica salt mine (Romania) using a portable radon monitor. The average radon concentration was found to be between 96.5 ± 4.76 Bq/m³ and 20.5 ± 1.30 Bq/m³. These values are suitable for therapeutic applications and are useful for future experiments regarding the development of the radon therapy and speleotherapy in this salt mine.     

Measurement of radon exhalation rate from soil samples of Garhwal Himalaya, India

Laboratory experiment was performed for the measurement of radon exhalation rate from the soil samples collected from Garhwal Himalayas. This study is accompanied by the measurement of soil-gas radon concentration in the same area. Both results were compared with the geological formation and structure of the area. No correlation was observed between soil-gas radon concentration and radon exhalation rate. However, it was found to be controlled by the lithology, geological structure and uranium mineralization in the area. The relationship between radon emanation, geological formation and occurrence of high indoor radon concentration is discussed.     

Annual average radon concentration in the show caves of Hungary

Radon can accumulate in underground areas such as show caves. Repairmen and tourist guides working in such caves may thus be exposed to significant radiation doses. Therefore, it is necessary to measure the radon concentration to estimate the exact radiation dose caused by radon. Considering that the radon concentration in caves usually shows significant seasonal fluctuations, the monthly change of radon concentration was studied for 1 year in nine show caves opened to the public in Hungary. Despite the fact that all of the caves were formed in karst rocks, the annual average radon concentration levels were rather different between each other (541–8287 Bq m⁻³). The significant monthly fluctuation of the radon concentration indicates that the annual average radon concentration in caves can only be accurately obtained by year-long measurements.     

龙门山山前断裂带中氡活度浓度的检测

对龙门山山前断裂带两侧表土中氡活度浓度进行了检测.结果表明,不同地层中,由于铀、钍等放射性元素含量的不同,其土壤中氡浓度也存在着明显的差异;在第四纪地层中,氡活度浓度的变化视表土的干湿程度、空隙度等而论,其变化范围存在很大差异.     

Modeling of the radon exhalation from water to air by a hybrid electrical circuit

A new model based on electric circuit theory has been introduced for modeling the radon exhalation from water to air in a sample bottle. Comparing the differential equations for radon exhalation from water to air and a hybrid electrical circuit shown that the volume of water or air, radon concentration, radon flux and solubility coefficient (dependent on temperature of water) are equivalent with capacitance, voltage across of capacitor, current and voltage gain, respectively. Then by using a hybrid electrical model total radon transfer velocity from water to air and time variation of water radon concentration in our experimental setup has been obtained. Also the variations of air radon concentration with temperature, volume of water and volume of air is obtained. The results show a good agreement with those in literatures.     

The effect of meteorological parameters on radon concentration in borehole air and water

Seasonal and short term variations of ²²²Rn activity concentration in borehole air and water of the borehole drilled in cracked quartzite were studied and possible response on meteorological parameters was examined. Seasonal change of radon concentration in borehole air due to atmospheric temperature was confirmed. Short term variation of radon concentration in borehole air coincided with the atmospheric pressure changes. The strong impact of rainfall on radon concentration values was observed both in air and water environments. The decrease of radon content in borehole air and water followed radioactive decay law exclusively in spring and summer month. Contrary to borehole water, rainfall increased radon concentration in borehole air during spring and summer months only. In this paper the results from two and half years of investigation are presented.     

A new approach for radon monitoring in soil as an earthquake precursor using optical fiber

Temporal variations of radon concentration in soil before the earthquake are known as an earthquake precursor. For using of radon as an earthquake precursor, it is necessary to constantly monitor radon concentration variations in a relatively wide range in the vicinity of a fault which is virtually impossible for radon detectors that already exist. This paper proposes a new method for continuous measurement of radon concentration variations in a wide range, using optical fiber as radon detector. For this purpose, an experimental system consisting of radon source, optical-fiber holding chamber, radon gas detector, optical laser source, and optical power meter have been arranged to with the aim to create different concentrations of radon gas in the vicinity of the optical fiber; the attenuation which creates on optical fiber is subsequently measured. As a result, the average of the attenuation is 0.004 μw per each meter per Bq/l since the fault’s length is more than ten kilometers; sensitivity of the measurement can be improved many times over.     

Radon emanation coefficient and its exhalation rate of wasted petroleum samples associated with petroleum industry in Egypt

Wasted petroleum, scale and sludge, samples associated with petroleum industries have elevated level of radionuclides concentrations which increase the radiation dose received to the workers. Radon concentration, emanation coefficient and exhalation rate give good information about the radioactivity levels. Twelve samples of scale, sludge and sand, collected from different oil fields in the Red Sea Refineries company for petroleum services in the eastern desert of Egypt, were selected for this study. Radon concentration released from selected samples was measured using AlphaGUARD radon monitor. Radon emanation coefficient and its exhalation rate were calculated based on the measured value of radon concentration. Correlation among radon exhalation rate with radium content and “emanated radon concentration” (radium concentration × emanation coefficient) as well were found to be of 0.94 and 0.99, respectively. Therefore, radon exhalation rate could be useful index for both radium concentration and emanated radon. Radon emanation coefficient was increased more than twice due to water content within material of less than of 10 %.     

Time variation of radon daughters concentration in snowfall

Time variation of radon daughters concentration in snowfall was measured continuously. The relations of radon daughters concentration in snowfall to the precipitation and to atmospheric radon daughters concentration were investigated. It has become clear that when precipitation is small, radon daughters concentration in snowfall is distributed in a wide range, and that the quantity of radon daughters brought to ground surface by snowfall is proportional to precipitation. Washout effect of the snowfall on atmospheric radon daughters was also investigated.     

Study of radon exhalation from the soil

The influence of meteorological parameters on radon exhalation rate was analyzed. The analyses show a significant influence of precipitation on radon exhalation rate. The highest exhalation rate was found during dry periods and the lowest during the periods of strong precipitation. We also tested two different types of detectors for the measurement of radon exhalation rate—the ionization chamber (AlphaGUARD) and the scintillation chamber of Lucas type. The exhalation rates measured by these detectors were in a good agreement. Likewise, there was an agreement in radon exhalation rates determined from short term and long term increases in radon activity concentration.