Variation of atmospheric radon concentration with bimodal seasonality

Omori, Yasutaka; Tohbo, Izumi; Nagahama, Hiroyuki; Ishikawa, Yoichi; Takahashi, Man-emon; Sato, H.; Sekine, Tsutomu

doi:10.1016/j.radmeas.2009.10.077

Cited by 23 publications

(18 citation statements)

References 27 publications

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“…Simulation results are consistent with seasonal wind patterns, clearly established for this region: in winter, northwest prevailing winds convey continental air masses, where are some of the major identified sources (Russia, Europe, and North America); in summer, southeast prevailing winds convey oceanic air masses, with no major sources upwind (similar to the example shown for CN20‐Beijing, in Figure ). Besides, the seasonal cycle of atmospheric radon has clearly been established in the region and is consistent with the wind seasonal variations (e.g., Kobayashi et al, ; Omori et al, ) and similar to the simulation results obtained for Xe‐133 in the present study. However, no obvious seasonal variations are observed in measurements.…”

Section: Resultssupporting

confidence: 92%

Seasonal Variability of Xe‐133 Global Atmospheric Background: Characterization and Implications for the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty

et al. 2018

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Global simulations of the atmospheric dispersion of worldwide industrial Xe‐133 releases have revealed a large spatial and day‐to‐day variability of the resulting so‐called Xe‐133 atmospheric background. Most stations of the International Monitoring System (IMS) of the Comprehensive nuclear‐Test‐Ban Treaty Organization actually detect Xe‐133 regularly. Measured levels are explained by a varying combination of local and distant industrial sources and can interfere with discrimination of nuclear test signatures. Therefore, a better understanding of the Xe‐133 atmospheric background is needed. In this study, a validated 2 year simulation data set and a 4 year measurement data set of Xe‐133 activity concentrations have been analyzed in order to characterize possible seasonal variations of the Xe‐133 atmospheric background due to atmospheric circulation, with a focus on (i) global distributions, (ii) occurrences of detections by the IMS network, and (iii) time series of monthly averages at IMS stations. Results show a larger spatial extent of the atmospheric background during winter months, which translates into a larger number of detections on the IMS network during winter months for both hemispheres. Some IMS stations present a significant seasonal variability in terms of levels, or both in terms of levels and origins. However, not all IMS stations are subject to seasonal variations, given their location with respect to sources and large‐scale atmospheric circulation. In addition, a first set of predicted information about expected levels of atmospheric background at IMS stations not yet operational is provided, given the current knowledge of sources.

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Section: Resultssupporting

confidence: 92%

Seasonal Variability of Xe‐133 Global Atmospheric Background: Characterization and Implications for the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty

et al. 2018

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“…That is, radon concentration was overestimated by a factor of up to two when radon and thoron concentrations were the same as each other. Ishikawa [17] carried out a different experiment, in which he investigated a pulse-ionization chamber monitor, the AlphaGUARD PQ2000Pro (Genitron Instruments, GmbH (Frankfurt, Germany)-now Bertin Technologies (Montigny-le-Bretonneux, France)); this monitor is widely used in environmental studies (see, for example, [22][23][24]). In Ishikawa's study [17], the chamber monitor was exposed to radon-bearing and thoron-bearing air in a calibration chamber constructed at the Environmental Measurements Laboratory in New York, and a thoron infiltration rate of about 10% was seen.…”

Section: Introductionmentioning

confidence: 99%

Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air

Omori

Shimo

Janik

et al. 2020

IJERPH

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Thoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron interference. Rates of thoron infiltration (as thoron interference) into the diffusion chamber of the monitor were evaluated. The temporal variation was obtained based on measurements of the underfloor space of a Japanese wooden dwelling using a diffusion-type radon monitor, a reference radon monitor which was not affected by thoron interference, and a thoron monitor. The thoron infiltration rate for the diffusion-type monitor varied from 0% to 20%. In particular, it appeared to increase when ventilation of the underfloor space air was forced. The variable thoron infiltration rate, with respect to ventilation strength, implied that not only a diffusive process, but also an advective process, played a major role in air exchange between the diffusion chamber of the monitor and the outer air. When an exposure room is characterized by the frequent variation in air ventilation, a variable thoron response is considered to occur in radon–thoron discriminative detectors, in which only diffusive entry is employed as a mechanism for the discrimination of radon and thoron.

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“…Radon concentration in atmosphere is about one-hundredth and one-thousandth of concentration in soil air 13 and in ground water 3 , respectively. Radon concentration in the atmosphere usually varies throughout the year because of seasonal factors 14 . Subsurface structural changes can involve exhalation of radon from the ground surface, and the atmospheric radon concentration reflects the averaged value of this exhalation over a wide area.…”

Section: Introductionmentioning

confidence: 99%

Non-parametric detection of atmospheric radon concentration anomalies related to earthquakes

Iwata

Nagahama

Muto

et al. 2018

Sci Rep

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Anomalous phenomena related to earthquakes have been studied to aid in the forecasting of large earthquakes. Radon (222Rn) concentration changes are known to be one of those phenomena. Many studies have quantified radon anomalies to identify physical aspects of radon emanations related to earthquakes. Here, we apply singular spectrum transformation, non-parametric analysis to estimate change points in time series, to atmospheric radon concentration. From 10 years of data from continuous observation of the atmospheric radon concentration over northeastern Japan and Hokkaido, we identify anomalies in the atmospheric radon concentration related to the moment releases of large earthquakes. Compared with a conventional model-based method, the singular spectrum transformation method identifies more anomalies. Moreover, we also find that change points in the atmospheric radon concentration prior to the 2011 Tohoku-Oki earthquake (Mw 9.0; 11 Mar. 2011, N38.1°, E142.9°) coincided with periods of other anomalous precursory phenomena. Our results indicate that singular spectrum transformation can be used to detect anomalies in atmospheric radon concentration related to the occurrences of large earthquakes.

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Variation of atmospheric radon concentration with bimodal seasonality

Cited by 23 publications

References 27 publications

Seasonal Variability of Xe‐133 Global Atmospheric Background: Characterization and Implications for the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty

Seasonal Variability of Xe‐133 Global Atmospheric Background: Characterization and Implications for the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty

Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air

Non-parametric detection of atmospheric radon concentration anomalies related to earthquakes

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