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1.
In this paper deposition rate coefficients for unattached and attached radon progeny were estimated according to a particle deposition model for turbulent indoor airflow described by Zhao and Wu [2006. Modeling particle deposition from fully developed turbulent flow in ventilation duct. Atmos. Environ. 40, 457–466]. The parameter which characterizes turbulent indoor airflow in this model is friction velocity, u*. Indoor ventilation changes indoor airflow and friction velocity and influences deposition rate coefficients. Correlation between deposition and ventilation rate coefficients in the room was determined. It was shown that deposition rate coefficient increases with ventilation rate coefficient and that these parameters of the Jacobi room model cannot be assumed to be independent. The values of deposition rate coefficients were presented as functions of friction velocity and ventilation rate coefficient. If ventilation rate coefficient varies from 0.1 up to 1 h−1, deposition rate coefficients for unattached and attached fractions were estimated to be in the range 3–110 h−1 and 0.015–0.35 h−1, respectively. 相似文献
2.
Over the last several years, the inhalation of decay products coming from radon-222 has become a national health concern.
It is estimated that somewhere between 16,000 and 20,000 people die annually in the United States from lung cancer due to
exposure to these decay products. Nationwide, 95% of all homes have not been tested for radon, and so it would seem that any
methodology that could give a general idea of indoor radon concentrations (without actually testing the house itself) might
be useful. While not intended to replace a radon test, which is both simple and inexpensive, our project attempts to predict
indoor radon concentrations based on easily obtainable information from Soil Conservation Service county soil surveys and
US Geological Survey surficial geology maps. We have chosen four parameters: soil permeability, surficial geology, soil shrink-swell
potential, and distance to the nearest geologic fault. Of these four variables, surficial geology and distance to fault correlated
well to winter indoor radon concentrations as measured by short-term (48-h) tests. While it is understood that there are limits
to this methodology, primarily because of map scale problems, the correlations mentioned above were very strong and suggest
further study would be useful. 相似文献
3.
放射性同位素氡222是来源于地层中铀衰变生成的惰性元素.由于其半衰期只有3.82d,且其活度在地下水和地表水中差异显著,近年来氡在水文学中的应用日渐兴起.但222Rn在岩溶环境中的分布和行为特征少有研究.以广西三个典型岩溶水系统为例,研究222Rn在包气带、非饱和带和饱水带中的浓度分布和指示意义.发现222Rn在上部包气带中的活度不足500Bq/m3,但在非饱和带中有局部异常高区,与局部小地质构造的分布有关.在饱水带中,地下水的滞留时间、不同地下水组分的混合和氡运移的距离等是导致222Rn活度差异的原因.管道介质的222Rn活度比裂隙介质的高;含水介质土壤覆盖层大的比土壤浅薄的普遍高.在大型岩溶水系统的排泄区,地下水补给河流,河流也可能短暂反补地下水,由于地下水和河流222Rn的差异显著,222Rn可能成为地下水-地表水相互作用研究的理想示踪剂. 相似文献
4.
Radon exhalation from building materials for decorative use 总被引:2,自引:0,他引:2
Jing Chen Naureen M. Rahman Ibrahim Abu Atiya 《Journal of environmental radioactivity》2010,101(4):317-322
Long-term exposure to radon increases the risk of developing lung cancer. There is considerable public concern about radon exhalation from building materials and the contribution to indoor radon levels. To address this concern, radon exhalation rates were determined for 53 different samples of drywall, tile and granite available on the Canadian market for interior home decoration. The radon exhalation rates ranged from non-detectable to 312 Bq m−2 d−1. Slate tiles and granite slabs had relatively higher radon exhalation rates than other decorative materials, such as ceramic or porcelain tiles. The average radon exhalation rates were 30 Bq m−2 d−1 for slate tiles and 42 Bq m−2 d−1 for granite slabs of various types and origins. Analysis showed that even if an entire floor was covered with a material having a radon exhalation rate of 300 Bq m−2 d−1, it would contribute only 18 Bq m−3 to a tightly sealed house with an air exchange rate of 0.3 per hour. Generally speaking, building materials used in home decoration make no significant contribution to indoor radon for a house with adequate air exchange. 相似文献
5.
Seasonal variations of Rn concentrations in the air of a tunnel located in Nagano city 总被引:2,自引:0,他引:2
H. Muramatsu Y. Tashiro N. Hasegawa C. Misawa M. Minami 《Journal of environmental radioactivity》2002,60(3):1070-274
The seasonal variation of 222Rn concentrations in the air of tunnels constructed during World War II at Nagano City has been investigated. The determination of 222Rn concentrations in tunnel air was performed using a solid-state nuclear track detector technique. The monthly radon concentrations changed smoothly, decreasing towards winter and increasing towards summer, and it was found that the concentrations strongly correlate with the temperature difference between the inside and the outside of the tunnel. In the innermost areas of the tunnel, the maximum concentration was observed in July, its value being about 6500 Bq m (-3). The concentrations of radon in the tunnel air decrease exponentially towards the openings of the tunnel, which indicates that the radon concentration in the tunnel is basically governed by diffusion and mixing of radon gas with air. These observations lead to the conclusion that the seasonal variation of the radon concentration in the tunnel air is mainly caused by a convection current due to a stack effect induced by the temperature difference between the tunnel air and the outside air. 相似文献
6.
7.
洞穴空气CO_2和~(222)Rn是岩溶洞穴中重要的小气候参数,理解影响洞穴空气CO_2和~(222)Rn浓度的时空变化特征及控制因素,对合理开发洞穴旅游资源有一定现实意义。本文通过2011年12月至2019年4月对我国南北气候过渡带附近河南省栾川县鸡冠洞空气CO_2和~(222)Rn浓度的多时空尺度的变化特征进行监测研究,主要得到以下结论:(1)在空间变化上,洞穴空气中的CO_2和~(222)Rn浓度主要受洞穴结构和通风效应的影响。越往洞内,CO_2和~(222)Rn浓度越大。(2)洞穴空气中的CO_2和~(222)Rn浓度季节变化特征明显,雨季上升,旱季下降,都受洞外水热环境的影响。鸡冠洞CO_2浓度变化范围为307~4 678 mg/L,受游客旅游活动的影响较为显著,空气~(222)Rn浓度变化范围为33. 0~2 421. 2 Bq/m~3,主要受洞穴结构和通风作用的影响。(3)在昼夜尺度的变化上,洞穴空气CO_2白天上升,夜间下降,主要受旅游活动的影响。空气中的~(222)Rn浓度与旅游活动的关系不明显。(4)鸡冠洞內吸入氡子体所导致的內照射人均年有效剂量为29. 6 mSv/a,虽然氡子体对一般游客产生危害较小,但年累积量需考虑,尤其是鸡冠洞内一线导游的核辐射安全防护。 相似文献
8.
Metin Mihci Attila Aydemir Nilgun Celebi 《Journal of environmental radioactivity》2010,101(11):952-957
Indoor and soil gas Radon (222Rn) concentration measurements were accomplished in two stages in Sivas, a central eastern city in Turkey. In the first stage, CR-39 passive nuclear track detectors supplied by the Turkish Atomic Energy Authority (TAEA) were placed in the selected houses throughout Sivas centrum in two seasons; summer and winter. Before the setup of detectors, a detailed questionnaire form was distributed to the inhabitants of selected houses to investigate construction parameters and properties of the houses, and living conditions of inhabitants. Detectors were collected back two months later and analysed at TAEA laboratories to obtain indoor 222Rn gas concentration values. In the second stage, soil gas 222Rn measurements were performed using an alphameter near the selected houses for the indoor measurements. Although 222Rn concentrations in Sivas were quite low in relation with the allowable limits, they are higher than the average of Turkey. Indoor and soil gas 222Rn concentration distribution maps were prepared seperately and these maps were applied onto the surface geological map. In this way, both surveys were correlated with the each other and they were interpreted in comparison with the answers of questionnaire and the geological setting of the Sivas centrum and the vicinity. 相似文献
9.
Anjos RM Juri Ayub J Cid AS Cardoso R Lacerda T 《Journal of environmental radioactivity》2011,102(11):1055-1061
Health hazard from natural radioactivity in Brazilian granites, covering the walls and floor in a typical dwelling room, was assessed by indirect methods to predict external gamma-ray dose rates and radon concentrations. The gamma-ray dose rate was estimated by a Monte Carlo simulation method and validated by in-situ measurements with a NaI spectrometer. Activity concentrations of 232Th, 226Ra, and 40K in an extensive selection of Brazilian commercial granite samples measured by using gamma-ray spectrometry were found to be 4.5-450 Bq kg−1, 4.9-160 Bq kg−1 and 190-2029 Bq kg−1, respectively. The maximum external gamma-ray dose rate from floor and walls covered with the Brazilian granites in the typical dwelling room (5.0 m × 4.0 m area, 2.8 m height) was found to be 120 nGy h−1, which is comparable with the average worldwide exposure to external terrestrial radiation of 80 nGy h−1 due to natural sources, proposed by United Nations Scientific Committee on the Effects of Atomic Radiation. Radon concentrations in the room were also estimated by a simple mass balance equation and exhalation rates calculated from the measured values of 226Ra concentrations and the material properties. The results showed that the radon concentration in the room ventilated adequately (0.5 h−1) will be lower than 100 Bq m−3, value recommended as a reference level by the World Health Organization. 相似文献
10.
对酸性红壤施用石灰和N2O生成之间的关系进行了探讨。结果表明,在好气条件下,石灰的施用与NH4+氧化过程中N2O的产生量之间的关系不明显。但随着石灰施用量的增加,厌气条件下NO3-还原过程中N2O的积累量明显增加了,这与施用石灰后土壤pH升高而提高了硝酸还原酶活性有关。试验还表明,尽管在厌气条件下土壤pH较高有利于NO3-还原成NO2-,但当缺乏有效碳源时,NO2-向N2O的进一步还原受到限制,易发生NO2-的积累。 相似文献