Влияние турбулентности и восходящих потоков воздуха на дочерние продукты распада радона

In this paper, a simulation of the distribution of radon progeny over the height of the atmosphere, depending on the amount of turbulent mixing and the vertical air velocity, is presented. The obtained results are compared with the change in the activity ratio of Bi-214/Pb-214 isotopes recorded in rainwater during 3-year observations in Prague. It is found that the reasons for the most common values of Bi-214/Pb-214 can be the height of the lower edge of the cloud of 0.2-1.4 km and the vertical air velocity of 0.1 – 0.2 m / s. The ratio changes slightly from changes in the turbulent mixing, the value of the vertical air movement makes the main contribution. It is found that with the increase in the intensity of rain, a shift in the radioactive equilibrium should occur due to an increase in the velocity of vertical air. Atmospheric inversion is able to balance the volumetric activities of the descendants of atmospheric radon, atmospheric inversion can be identified by the equality between the activities of the radon progeny in the atmosphere at different altitudes or in rainwater. It is shown that the search for the relationship between precipitation intensity and gamma radiation is expose to error, without taking into account the influence of the АBi−214/АPb−214 ratio, due to the unequal activities of the atmospheric isotopes Bi-214 and Pb-214. This error of 7-14% when using gamma radiometry, and of 5-9% when using dosimeters is estimated. олучены результаты моделирования распределения дочерних продуктов радона в атмосферном столбе по высоте, объясняющие изменение концентраций радионуклидов в дождевой воде в зависимости от высоты нижней кромки облаков. Значения соотношений активностей АBi−214/АPb−214 радионуклидов дождевой воды от 0.6 до 0.8, могут возникать при высоте нижней кромки облаков от 0.2 до 1.4 км и адвекции от 0.1 до 0.2 м/с соответственно. Произведена оценка шибки от 7 до 14%, возникающая при использовании гамма радиометров, и от 5 до 9% — дозиметров, во время осадков с целью поиска корреляции роста гамма-фона и интенсивности жидких ливневых осадков.

Upgrade of a Highly Sensitive Monitor for Atmospheric Radon Measurement

Atmospheric radon is an ideal tracer that is widely used in atmospheric science. To meet the need fora continuous online measurement of atmospheric radon concentration, an upgraded radon monitor based on an electrostatic collection method was developed following Iida’s measurement system. Two major improvements have been realized. First, an 18 mm × 18 mm Si-PIN detector and a multi-channel analysis system were used to distinguish different alpha particles. Second, the P2O5 desiccant was replaced by a new membrane drying system, and the influence of humidity was corrected by a humidity correction coefficient. Calibration and comparison experiments were carried out in detail, and a one-year continuous measurement was also performed. Results showed that the measurement sensitivity was evaluated to be 24.3 cph/(Bq·m−3), and the lower level detection limit was 0.2 Bq·m−3 for a 1-h cycle at the absolute humidity of 0.34 g·m−3. The annual average radon concentration of Beijing was 11.1 ± 4.0 Bq·m−3, which changed from 2.8 Bq·m−3 to 30.3 Bq·m−3 between 15 October 2018 and 1 October 2019. The upgraded monitor’s high data acquisition rate and good performance indicate that it is suitable for long-term observation on atmospheric radon.

Preseismic atmospheric radon anomaly associated with 2018 Northern Osaka earthquake

Despite the challenges in identifying earthquake precursors in intraplate (inland) earthquakes, various hydrological and geochemical measurements have been conducted to establish a possible link to seismic activities. Anomalous increases in radon (222Rn) concentration in soil, groundwater, and atmosphere have been reported prior to large earthquakes. Although the radon concentration in the atmosphere is lower than that in groundwater and soils, a recent statistical analysis has suggested that the average atmospheric concentration over a relatively wide area reflects crustal deformation. However, no study has sought to determine the underlying physico-chemical relationships between crustal deformation and anomalous atmospheric radon concentrations. Here, we show a significant decrease in the atmospheric radon concentration temporally linked to the seismic quiescence before the 2018 Northern Osaka earthquake occurring at a hidden fault with complex rupture dynamics. During seismic quiescence, deep-seated sedimentary layers in Osaka Basin, which might be the main sources of radon, become less damaged and fractured. The reduction in damage leads to a decrease in radon exhalation to the atmosphere near the fault, causing the preseismic radon decrease in the atmosphere. Herein, we highlight the necessity of continuous monitoring of the atmospheric radon concentration, combined with statistical anomaly detection method, to evaluate future seismic risks.

High efficiency and portable monitor of atmospheric radon concentration activity for environmental applications

<p>The natural radioactive noble gas radon (<sup>222</sup>Rn) is originated from the decay of radium into the soil and then continuously exhaled to the lower atmosphere. Its diffusion and exhalation rate depend both on the physical and environmental conditions of the soil layers and on the meteorological conditions. With a half-life of 3.8 days and a very limited chemical activity, the <sup>222</sup>Rn is nowadays being used as an atmospheric tracer for: i) the improvement of atmospheric transport models used, among others, to identify greenhouse gas (GHG) emission sources; ii) for the indirect estimation of GHG fluxes by the Radon Tracer Method (RTM). These previous applications need high sensitivity and precision at low radon concentrations range (< 100 Bq m<sup>-3</sup>).</p><p>A new monitor, based on alpha spectrometry of <sup>218</sup>Po electrostatically collected on a PIPs detector, has been designed and developed at the Institute of Energy Technologies (INTE) of the Universitat Politecnica de Catlunya (UPC)  in the mark of the project ‘High efficiency monitor of atmospheric radon concentration for radiation protection and environmental applications (MARE<sup>2</sup>EA), reference: 2019-LLAV-00035, funded by the Catalan Agency for Management of University and Research Grants. The aim is building an instrument able to measure atmospheric radon concentration activities with high precision in order to be running at GHG atmospheric networks for the RTM applications.</p><p>The monitor is an improved version of a previous prototype instrument (Grossi et al., 2012, 2020). The new instrument will allow a higher efficiency, robustness and portability. In addition, it will have a GUI interface to be user friendly. Finally, in order to reduce the air sample humidity within the detection volume of the instrument which affects the <sup>218</sup>Po collection, a portable drying system has also been built to keep the instrument ongoing without maintenance during several weeks.</p><p> </p><p><strong>References</strong></p><p>Grossi, C., Arnold, D., Adame, J. A., López-Coto, I., Bolívar, J. P., De La Morena, B. A., & Vargas, A. (2012). Atmospheric 222Rn concentration and source term at El Arenosillo 100 m meteorological tower in southwest Spain. Radiation Measurements, 47(2), 149–162. https://doi.org/10.1016/j.radmeas.2011.11.006</p><p>Grossi, C., Chambers, S. D., Llido, O., Vogel, F. R., Kazan, V., Capuana, A., Werczynski, S., Curcoll, R., Delmotte, M., Vargas, A., Morguí, J.-A., Levin, I., & Ramonet, M. (2020). Intercomparison study of atmospheric <sup>222</sup>Rn and <sup>222</sup>Rn progeny monitors. Atmospheric Measurement Techniques, 13(5). https://doi.org/10.5194/amt-13-2241-2020</p>

Radon metrology for use in climate change observation and radiation protection at the environmental level

<p>Radon gas is the largest source of public exposure to naturally occurring radioactivity, and concentration maps based on atmospheric measurements aid developers to comply with EU Safety Standard Regulations. Atmospheric radon can also be used as a tracer to evaluate transport models important for supporting successful greenhouse gas (GHG) mitigation strategies. One of the most common techniques currently applied for this propose is the Radon Tracer Method (RTM). To increase the accuracy of both radiation protection measurements and those used for GHG modelling, traceability to SI units for radon exhalation rates from soil, its concentration in the atmosphere and validated models for its dispersal are needed. Thus, atmospheric networks such as the Integrated Carbon Observation System (ICOS) are interested in integrating atmospheric radon concentration measurements. The EMPIR project 19ENV01 traceRadon[1] started to provide the necessary measurement infrastructure for atmospheric radon activity concentration and radon flux measurements, with benefits for both large scientific communities. This is particularly important for GHG emission estimates that support national reporting under the Paris Agreement on climate change.</p><p>Compared to the large spatiotemporal heterogeneity of GHG fluxes, radon is emitted almost homogeneously over ice-free land and has a negligible flux from oceans. Atmospheric measurements of radon activity concentrations can be used for the assessment and improvement of atmospheric mixing and transport models.</p><p>Similarly, for radiological data, all European countries have installed networks of automatic gamma dose rate and atmospheric concentration level monitoring stations and report the information gathered to the European Radiological Data Exchange Platform (EURDEP). Currently, EURDEP exchanges real-time monitoring information from 39 countries collected from more than 5500 automatic surveillance systems. Therefore, improving contamination detection requires greater accuracy in determining environmental radon concentrations and their movement in the atmosphere.</p><p>An overlapping need exists between the climate research and radiation protection communities for improved traceable low-level outdoor radon measurements, combining the challenges of collating and modelling large datasets, with setting up new radiation protection services. The project traceRadon works on this aspect for the benefit of two large scientific communities. An overview will be presented, and first results with respect to radionuclide metrology will be discussed.</p><div><br><div> <p>[1] This project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. 19ENV01 traceRadon denotes the EMPIR project reference.</p> <p> </p> </div> </div>

Radon degassing triggered by tidal loading before an earthquake

The presence of anomalous geochemical changes related to earthquakes has been controversial despite widespread, long time challenges for earthquake prediction. Establishing a quantitative relationship among geochemical changes and geodetical and seismological changes can clarify their hidden connection. Here we determined the response of atmospheric radon (222Rn) to diurnal tidal (K1 constituent) loading in the reported 11-year-long variation in the atmospheric radon concentration, including its anomalous evolution for 2 months before the devastating 1995 Kobe earthquake in Japan. The response to the tidal loading had been identified for 5 years before the occurrence of the earthquake. Comparison between these radon responses relative to crustal strain revealed that the response efficiency for the diurnal K1 tide was larger than that for the earthquake by a factor of 21–33, implying the involvement of crustal fluid movement. The radon responses occurred when compressional crustal stress decreased or changed to extension. These findings suggest that changes in radon exhaled from the ground were induced by ascent flow of soil gas acting as a radon carrier and degassed from mantle-derived crustal fluid upwelling due to modulation of the crustal stress regime.

The determination of highly time-resolved and source-separated black carbon emission rates using radon as a tracer of atmospheric dynamics

We present a new method for the determination of the source-specific black carbon emission rates. The methodology was applied in two different environments: an urban location in Ljubljana and a rural one in the Vipava valley (Slovenia, Europe), which differ in pollution sources and topography. The atmospheric dynamics was quantified using the atmospheric radon (222Rn) concentration to determine the mixing layer height for periods of thermally driven planetary boundary layer evolution. The black carbon emission rate was determined using an improved box model taking into account boundary layer depth and a horizontal advection term, describing the temporal and spatial exponential decay of black carbon concentration. The rural Vipava valley is impacted by a significantly higher contribution to black carbon concentration from biomass burning during winter (60 %) in comparison to Ljubljana (27 %). Daily averaged black carbon emission rates in Ljubljana were 210 ± 110 and 260 ± 110 µgm-2h-1 in spring and winter, respectively. Overall black carbon emission rates in Vipava valley were only slightly lower compared to Ljubljana: 150 ± 60 and 250 ± 160 µgm-2h-1 in spring and winter, respectively. Different daily dynamics of biomass burning and traffic emissions was responsible for slightly higher contribution of biomass burning to measured black carbon concentration, compared to the fraction of its emission rate. Coupling the high-time-resolution measurements of black carbon concentration with atmospheric radon concentration measurements can provide a useful tool for direct, highly time-resolved measurements of the intensity of emission sources. Source-specific emission rates can be used to assess the efficiency of pollution mitigation measures over longer time periods, thereby avoiding the influence of variable meteorology.