Radon and air ion balance

In connection with the study of equilibrium among radon and its conversion products attention has been paid to air ionisation or, more precisely, to light atmospheric ions. Air ionisation variability and relationship between positive and negative ions concentration in the presence of ionizing radiation, local and microclimatic conditions have been observed. A very good correlation between light atmospheric ions concentration and radon volume activity or equilibrium equivalent of radon decay products has been found. Concrete measurements were conducted in karst caves and mine galleries without any meteorological influences. It was discovered that in most cases negative ions concentration predominated over positive ions concentration. This non-equilibrium was caused by a number of factors. In this work we have concentrated our attention to microclimatic and regime conditions of the individual locations.     

Monitoring of natural factors in Czech speleotherapeutic centres

The work deals with the problems of volume activity of radon and its daughter products, of the concentration of positive and negative atmospheric ions and microclimatic conditions in speleotherapeutic centres Zlaté Hory (ore gallery) and Javo?í?ko (cave).     

Radon in well waters in the Kraków area

The method and the results of radon concentration measurements in water samples are presented. Since May 2000, measurements of radon concentration in well waters in the Kraków area have been carried out--both in urban wells (depth above 50 meters) and in other private wells (depth of several meters). The ionisation chamber AlphaGUARD PQ 2000PRO along with the additional special equipment AquaKIT were used for determination of radon concentration in water samples. A total of 45 wells were examined for radon concentration in water--19 urban wells, 21 private ones (from Nowa Huta, Ojcowska, Wola Justowska area--parts of Kraków) and 5 mineral water sources. Wola Justowska is a region where tectonics faults occur and radon can easily migrate from deep basement structure. All the obtained values of radon concentration are below 12 Bq/l. These preliminary results do not show a direct correlation between geological structure and radon concentration in water samples. However, further investigation is needed and is planned to be undertaken.     

Influence of an acetylene impurity on the properties of a radio-frequency gas discharge in argon

The influence of an acetylene fraction in a mixture with argon on the parameters of a radio-frequency gas discharge has been investigated using the kinetic simulation by the particle-in-cell Monte Carlo collision method. Special attention has been focused on analyzing the formation of ions and radicals that are precursors for growth of nanoparticles in the gas discharge volume. It has been shown that the concentrations of electrons, positive ions, and negative ions are nonmonotonic functions of the acetylene amount in the mixture. The presence of negative ions with a concentration comparable to the electron concentration changes the parameters of the radio-frequency gas discharge only insignificantly.     

Complex Burgers’ Equation: Evolution of Shock Waves with a Pair of Non-isothermal Ions in an Arbitrarily Charged Dusty Plasma

The evolution characteristics of dust-acoustic shock wave phenomenon in an arbitrarily charged dusty plasma in presence of pair-ion are investigated by deriving modified Complex Burgers’ equation. In this work, the effect of state of both the ions on the shock wave potential is analysed and discussed in detail. It has been observed that the variation of the non-linear coefficient is more consistent with the non-isothermal positive ions moving toward thermal equilibrium than with non-isothermal negative ions. A significant effect on the amplitude of the shock wave potential is observed as the distribution of the non-isothermal positive and negative ions changes from a hump shape through the flat-topped to Boltzmann type. A weighty effect on the height of the shock wave is observed as and when the Mach number of positive and negative ions changes. The shock wave potential shows a greater (lesser) value with negative (positive) ions moving ahead for thermal equilibrium.     

Study of the response of silicon detectors for alpha particles

Numerous radon measurements are carried out using silicon detectors directly in the environment. This new kind of alpha radiation measurement has been developed because the reduced cost makes it possible to replace the usual plastic track detectors. At our laboratory, an alpha particle detector has been designed from a commercial silicon photodiode. This type of detector can determine the device response perfectly in any kind of environment. Different spectrum analyses have been conducted in the laboratory and field to define the exact origin of counted alpha particles. We studied the response for different radon and thoron concentration levels and observed the energy of the detected alpha particles. We carried out some of these experiments with gas flux, and some without, to show the effects of interactions with surfaces to obtain thermodynamic equilibrium in the detection chamber. Finally, the silicon diodes that we tested measure the alpha particles of the decay products (polonium) from the radon and the thoron, but very weakly from the gases themselves. Thus, it is possible to make mistakes when measuring the radon if the count of alpha particles is performed without spectrum analysis. One reason for this is that the decay progenies of the radon are solid radio-elements with thermodynamic proprieties different from gases.     

Relationships between radon anomalies and seismic parameters in N-W Himalaya, India

Radon data accumulated during 1992–1999 in the grid (30–34°N, 74–78°E) in N-W Himalaya have been anlaysed vis a vis seismic data recorded in the same area, supplied by Indian Meteorological Department (IMD) network. In general, there is a positive correlation between the total radon emission and the microseismicity in the area under investigation. The earthquake magnitude has moderate positive correlation with epicentral distance and low positive correlation with amplitude of radon precursory signal, whereas both show low negative correlation between them.

Empirical scaling relations are proposed using the best fit straight line from the log-linear graphs between magnitude of the events and log of the product of amplitude of radon anomaly and epicentral distance. The error between the recorded and calculated magnitude is also taken into account. The error range is higher at lower epicentral distances and magnitudes, showing that the local geology and tectonics have predominant influence on radon signals.     

Preliminary measurements of natural radioactivity at Madurai district of Tamilnadu, India

In dwellings, the radon and their daughter products contribute the largest fraction to the doses received from natural background radiation. In the present study, the radon levels at Madurai district of Tamilnadu have been measured initially for 15 dwellings using cellulose nitrate (C₆H₈O₉N₂) LR-115 type II (non-pelliculable) films and the dose assessment due to radon and its daughter product concentrations is calculated. These results were intercompared with other terrains viz. Jodhpur district of Rajasthan which is considered as semi-desert terrain and Jammu district of Jammu & Kashmir which is the hilly area. Also the natural radioactivity in soil samples of Madurai have been measured using NaI(Tl) detector based gamma spectrometry. From these radioactivity levels, the radium equivalent activity is calculated and a correlation between this and radon concentration has been tried out.     

Seasonal variation on radon emission from soil and water

Radon is being measured continuously in spring water and soil-gas at Badshahi Thaul Campus, Tehri Garhwal in Himalayan region by using radon Emanometer since December 2002. An effort was made to correlate the variance of radon concentrations in spring water and soil-gas with meteorological parameters at the same location. The main meteorological parameters that affect the radon emanation from host material is surrounding temperature, barometric pressure, wind velocity, rain fall and water level of the spring. The correlation coefficient between radon concentration in spring water and different atmospheric parameters was computed. The correlation coefficient between radon concentration in spring water and the maximum atmospheric temperature was 0.3, while it was 0.4 for minimum atmospheric temperature at the monitoring site. The correlation coefficient for radon concentration in spring water with minimum and maximum relative humidity was 0.4. Spring water radon concentration was found positively correlated (0.6) with water discharge rate of the spring. A weak correlation (0.09) was observed between the radon concentration in spring water and rain fall during the measurement period. As temperature of near surface soil increases, the radon emanation coefficient from the soil surface also increases. The possible effects due to global warming and other climatic changes on environment radiation level were also discussed in detail.      

Radon daughters' concentration in air and exposure of joggers at the university campus of Bangalore, India

The concentration of radon daughters in outdoor air was measured continuously from January 2006 to December 2006 near the Department of Physics, Bangalore University campus, Bangalore. The concentration was measured by collecting air samples at a height of 1 m above the ground level on a glass micro fibre filter paper with a known air flow rate. The results show that the radon progeny concentration exhibits distinct seasonal and diurnal variations that are predominantly caused by changes in the temperature gradient at the soil-atmosphere interface. The concentration was found to be high from 20.00 to 8.00 hrs, when the turbulence mixing was minimum and low during the rest of the time. In terms of the monthly concentration, January was found to be the highest with September/August being the lowest. The diurnal variations in the concentrations of radon progeny were found to exhibit positive correlation with the relative humidity and anti-correlation with the atmospheric temperature. From the measured concentration, an attempt was made to establish the annual effective dose to the general public of the region and was found to be 0.085 mSv/a. In addition, an attempt was also made for the first time to study the variation of inhalation dose with respect to the physical activity levels. Results show that in the light of both the effect of chemical pollutants and radiation dose due to inhalation of radon daughters, evening jogging is advisable.     

Radon daughters’ concentration in air and exposure of joggers at the university campus of Bangalore,India

The concentration of radon daughters in outdoor air was measured continuously from January 2006 to December 2006 near the Department of Physics, Bangalore University campus, Bangalore. The concentration was measured by collecting air samples at a height of 1 m above the ground level on a glass micro fibre filter paper with a known air flow rate. The results show that the radon progeny concentration exhibits distinct seasonal and diurnal variations that are predominantly caused by changes in the temperature gradient at the soil–atmosphere interface. The concentration was found to be high from 20.00 to 8.00 hrs, when the turbulence mixing was minimum and low during the rest of the time. In terms of the monthly concentration, January was found to be the highest with September/August being the lowest. The diurnal variations in the concentrations of radon progeny were found to exhibit positive correlation with the relative humidity and anti-correlation with the atmospheric temperature. From the measured concentration, an attempt was made to establish the annual effective dose to the general public of the region and was found to be 0.085 mSv/a. In addition, an attempt was also made for the first time to study the variation of inhalation dose with respect to the physical activity levels. Results show that in the light of both the effect of chemical pollutants and radiation dose due to inhalation of radon daughters, evening jogging is advisable.     

Radioactivity measurements in the environment of the Udhampur area,Jammu and Kashmir Himalayas,India

LR-115 plastic track detectors have been used for the measurement of radon exhalation rate and radium concentration in soil samples collected from some villages of the Udhampur district, Jammu and Kashmir, India. Uranium concentration has also been determined in these soil samples using the fission track registration technique. Radium concentration in soil samples varies from 5.46 to 19.17 Bqkg^?1, whereas uranium concentration varies from 2.53 to 3.65 ppm. The radon exhalation rate in these samples has been found to vary from 6.42 to 22.47 mB kg^?1 hr^?1. The work is undertaken for health risk assessments due to uranium and radium in the study area. A positive correlation has been observed between uranium and radium, as well as uranium and radon exhalation rate in soil samples.     

Spatial and temporal variations of radon concentration in soil air

The spatial and temporal variability of the soil gas radon concentration in typical soils is studied. The results obtained will be further used to predict indoor radon levels. To this end, 50 measuring points along geologic sections with known physicogeological parameters of soils were chosen. The soil gas radon concentration was measured with SSNTDs (Type III-b) at a depth of 70 cm from June to October, 2000. The radon exposure time was 72–96 h. The average radon concentration in the soil pore air for an urban area was 11 kBqm⁻³ (1.7–24 kBqm⁻³). Small-scale spatial variations in the concentration were found to lie within a narrower range. The effect of meteorological conditions on the soil gas radon concentration was investigated by performing 8 series of measurements at 5 closely spaced points in September–October, 2000. A significant correlation was found between the soil radon concentration and atmospheric pressure (K=−0.86), ambient temperature (K=0.75), and soil temperature (K=0.75).     

Indoor radon and lung cancer: a case-control study

Lung-cancer risk to the general population from indoor radon remains controversial, although studies of radon exposure have established that radon decay products have been a cause of lung cancer among miners.

For the case group of patients, suffering from lung cancer, and the control group distributions of the number of homes with high indoor levels of radon were compared with the log-normal distribution, the empirical frequency distribution of the control group obeyed the theoretical log-normal distribution.

Using the ratio of frequencies of the case group to the control groups, or the relative frequencies, an association between the relative frequencies and indoor radon concentrations was found, and a positive correlation coefficient was obtained, thus enabling the rate of lung cancer to be estimated for certain indoor radon concentrations.

The significant difference between the mean radon levels for the case sample and the control led to the conclusion that patients with lung cancer lived in homes with radon concentrations which were significantly higher than those of Osijek’s inhabitants for the control sample.     

Indoor radon and lung cancer: a case-control study

Lung-cancer risk to the general population from indoor radon remains controversial, although studies of radon exposure have established that radon decay products have been a cause of lung cancer among miners. For the case group of patients, suffering from lung cancer, and the control group distributions of the number of homes with high indoor levels of radon were compared with the log-normal distribution, the empirical frequency distribution of the control group obeyed the theoretical log-normal distribution. Using the ratio of frequencies of the case group to the control groups, or the relative frequencies, an association between the relative frequencies and indoor radon concentrations was found, and a positive correlation coefficient was obtained, thus enabling the rate of lung cancer to be estimated for certain indoor radon concentrations. The significant difference between the mean radon levels for the case sample and the control led to the conclusion that patients with lung cancer lived in homes with radon concentrations which were significantly higher than those of Osijek's inhabitants for the control sample.     

Experimental and theoretical study of radon levels and entry mechanisms in a mediterranean climate house

An experimental study has been carried out in an inhabited single-family house. Radon concentration in the different rooms of the house and in its garden soil has been measured with Nuclear Track Detectors. No high differences of radon concentration have been observed between the different rooms of the house, so that the proximity of the room level to the soil seems not to affect the radon concentration. The annual radon concentration obtained indoors and in the soil has been respectively 35 Bq m⁻³ and 24 kBq m⁻³. Since radon generation in the source, entry into indoor air and accumulation indoors depend on several parameters, the effect of a specific parameter on indoor radon concentration is difficult to explain from the radon measurements only. The RAGENA (RAdon Generation, ENtry and Accumulation indoors) model has been adapted to the room in the basement of the house. The mean radon concentration values obtained with the model are compared to experimental results derived from measurements using Nuclear Track Detectors. The use of the model, together with the experimental study, has allowed characterising radon sources, levels and entry mechanisms in the house. The concrete walls have been found to be the most relevant radon source, while the contribution of the soil is negligible in this case. The indoor radon level is given by the balance of the permanent exhalation from concrete and the removal due to ventilation. The indoor radon levels are close to the average value for the Barcelona area which, in turn, is close to the world averaged value.     

Dissociation of Cyclotrimethylenetrinitramine Under 1064-nm Laser Irradiation Investigated by Time-of-Flight Mass Spectrometer

Laser-induced dissociation pathways of cyclotrimethylenetrinitramine have been investigated with a focused laser of 1064 nm by use of a time-of-flight mass spectrometer. The ions produced from the cyclotrimethylenetrinitramine surface were detected and the mass spectra of both positive and negative ions were obtained. According to the possible distribution of the decomposition products, possible dissociation paths of cyclotrimethylenetrinitramine were proposed. The influence of the intensity and the delay time of the laser beam to the decomposition have also been studied. The results may possibly throw some light on our understanding of the reactions taking place in laser ignition.     

Observation and removal of daily quasi-periodic components in soil radon data

We report (quasi) periodic oscillations observed in soil radon emanation data especially during summer period. Soil radon has been continuously monitored in the Marmara region of Turkey over the past nine years to reveal possible relationships between soil radon and seismic activities. This long term monitoring has clearly demonstrated that soil radon concentrations are affected by various parameters such as seasonal and daily changes in atmospheric parameters (temperature, pressure, precipitation). Sometimes, soil temperature variations as well as barometric pressure and precipitation may dominantly influence the soil radon concentration; leading to seemingly complex radon time series. One may need to remove such components for better analysis of the possible relationships between soil radon emanation and seismic activities. Here, we suggest using an algorithm to detect and remove daily-oscillations from the raw data. The detection and separation (extraction) algorithm is based on Empirical Mode Decomposition method which is a signal-adaptive method that automatically decompose the signal into its characteristic modes. The algorithm is applied to the data collected from three different soil radon monitoring stations (Bal?kesir, Gönen, and Armutlu) in Marmara region of Turkey and the results are provided.     

确定大气颗粒物平均滞留时间的新方法

从低层大气的基本属性出发,利用大气颗粒物中放射性核素的衰变特性与转移速率等相关信息, 建立了单位体积大气颗粒物中被吸附的放射性粒子数、衰变粒子数和转移粒子数的数学模型, 获得了确定低层大气颗粒物平均滞留时间的新方法.该方法解决了当前相关研究中出现的困惑, 说明了大气具有有限的自净功能,给出了大气颗粒物中同一衰变链上各核素达到活度平衡的条件 及降低平均滞留时间的途径,为大气环境的监测与治理提供了科学依据. 关键词： 大气颗粒物 平均滞留时间 氡子体 监测     

A preliminary study of post-seismic effects of radon following the Ms 8.0 Wenchuan earthquake

The observation data for radon from national geochemical observation points have been collected and analyzed following the Ms 8.0 Wenchuan earthquake on 12th May, 2008 and a post-seismic effect of radon was observed. It has provided the most abundant record since the radon observation network had been set up in china. In this paper, the behaviour of the post-seismic effects of radon gas and water radon is reported. The results were obtained that observation points recording post-seismic effects of radon release were distributed mainly along the extended line of Longmenshan faults, and located on the boundary faults of regional tectonic blocks (Category II) and inside some tectonic blocks (Category II). The pattern of variation in radon emission observed was largely in the form of rising steps. A comparison was made with the variation of water level and flow observed simultaneously with radon measurement, to investigate a dynamic link with post-seismic radon with underground water conditions. This study confirmed a response of radon concentration to the seismic wave, and also raised other scientific issues, such as the dynamic association between geochemical composition of underground water and medium parameter variation of aquifers under dynamic loading, which may support the study of the mechanism of earthquake precursors of radon.