One year of 222 Rn concentration in the atmospheric surface layer
TL;DR: In this article, a one-year time series of radon measured in a rural area in the North of Italy in 1997 has been analyzed, where wavelet analysis is used as one of the investigation tools of the time series.
Abstract: A one-year time series of 222 Rn measured in a rural area in the North of Italy in 1997 is analyzed. The scope of the investigation is to better understand the behavior of this common atmospheric tracer in relation to the meteorological conditions at the release site. Wavelet analysis is used as one of the investigation tools of the time series. The measurements and scalograms of 222 Rn are compared to those of wind-speed, pressure, relative humidity, temperature and NO x . The use of wavelet analysis allows the identification of the various scales controlling the influence of the meteorological variables on 222 Rn dispersion in the surface layer that are not visible through classical Fourier analysis or direct time series inspection. The analysis of the time series has identified specific periods during which the usual diurnal variation of radon is superimposed to a linear growth thus indicating the build up of concentration at the measurement level. From these specific cases an estimate of the surface flux of 222 Rn is made. By means of a simple model these special cases are reproduced.
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TL;DR: In this paper, the authors synthesize the published literature on subsurface airflow driven by natural forcings such as atmospheric pressure fluctuations, topographic effect, water table fluctuations, and water infiltration.
Abstract: [1] Subsurface airflow in unsaturated zones induced by natural forcings is of importance in many environmental and engineering fields, such as environmental remediation, water infiltration and groundwater recharge, coastal soil aeration, mine and tunnel ventilation, and gas exchange between soil and atmosphere. This review synthesizes the published literature on subsurface airflow driven by natural forcings such as atmospheric pressure fluctuations, topographic effect, water table fluctuations, and water infiltration. The present state of knowledge concerning the mechanisms, analytical and numerical models, and environmental and engineering applications related to the naturally occurring airflow is discussed. Airflow induced by atmospheric pressure fluctuations is studied the most because of the applications to environmental remediation and transport of trace gases from soil to atmosphere, which are very important in understanding biogeochemical cycling and global change. Airflow induced by infiltration is also an extensively investigated topic because of its implications in rainfall infiltration and groundwater recharge. Airflow induced by water table fluctuations is important in coastal areas because it plays an important role in coastal environmental remediation and ecological systems. Airflow induced by topographic effect is studied the least. However, it has important applications in unsaturated zone gas transport and natural ventilation of mines and tunnels. Finally, the similarities and differences in the characteristics of the air pressure and airflow are compared and future research efforts are recommended.
88 citations
Cites background from "One year of 222 Rn concentration in..."
...In addition, both positive [Galmarini, 2006] and negative [Klusman and Jaacks, 1987; Schery et al., 1989; Hutter, 1996; Iakovleva and Ryzhakova, 2003; Smetanov a et al., 2010] correlations between radon concentration and atmospheric pressure were found....
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...Some researchers stated that only sudden drops or increases of atmospheric pressure (of the order of 1.0–1.5 kPa) can affect the radon exhalation [Kataoka et al., 2003; Galmarini, 2006]....
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TL;DR: In this article, the authors argue that single-height radon observations should not be used quantitatively as an indicator of atmospheric stability without prior conditioning of the time series to remove contributions from larger-scale "non-local" processes.
Abstract: . Radon is increasingly being used as a tool for quantifying stability influences on urban pollutant concentrations. Bulk radon gradients are ideal for this purpose, since the vertical differencing substantially removes contributions from processes on timescales greater than diurnal and (assuming a constant radon source) gradients are directly related to the intensity of nocturnal mixing. More commonly, however, radon measurements are available only at a single height. In this study we argue that single-height radon observations should not be used quantitatively as an indicator of atmospheric stability without prior conditioning of the time series to remove contributions from larger-scale "non-local" processes. We outline a simple technique to obtain an approximation of the diurnal radon gradient signal from a single-height measurement time series, and use it to derive a four category classification scheme for atmospheric stability on a "whole night" basis. A selection of climatological and pollution observations in the Sydney region are then subdivided according to the radon-based scheme on an annual and seasonal basis. We compare the radon-based scheme against a commonly used Pasquill–Gifford (P–G) type stability classification and reveal that the most stable category in the P–G scheme is less selective of the strongly stable nights than the radon-based scheme; this lead to significant underestimation of pollutant concentrations on the most stable nights by the P–G scheme. Lastly, we applied the radon-based classification scheme to mixing height estimates calculated from the diurnal radon accumulation time series, which provided insight to the range of nocturnal mixing depths expected at the site for each of the stability classes.
77 citations
TL;DR: The seasonality of indoor Rn concentration measured in Austria is investigated as a function of other factors that influence indoors Rn, with higher Rn levels in winter.
63 citations
TL;DR: In this paper, a technique recently developed for stability classification using a research-quality dual-flow-loop two-filter radon detector is adapted for use with a commercially available radon-based stability monitor.
57 citations
TL;DR: One year of radon, benzene and carbon monoxide (CO) concentrations were analyzed to characterise the combined influences of variations in traffic density and meteorological conditions on urban air quality in Bern, Switzerland as mentioned in this paper.
Abstract: One year of radon, benzene and carbon monoxide (CO) concentrations were analysed to characterise the combined influences of variations in traffic density and meteorological conditions on urban air quality in Bern, Switzerland. A recently developed radon-based stability categorisation technique was adapted to account for seasonal changes in day length and reduction in the local radon flux due to snow/ice cover and high soil moisture. Diurnal pollutant cycles were shown to result from an interplay between variations in surface emissions (traffic density), the depth of the nocturnal atmospheric mixing layer (dilution) and local horizontal advection of cleaner air from outside the central urban/industrial area of this small compact inland city. Substantial seasonal differences in the timing and duration of peak pollutant concentrations in the diurnal cycle were attributable to changes in day length and the switching to/from daylight-savings time in relation to traffic patterns. In summer, average peak benzene concentrations (0.62 ppb) occurred in the morning and remained above 0.5 ppb for 2 hours, whereas in winter average peak concentrations (0.85 ppb) occurred in the evening and remained above 0.5 ppb for 9 hours. Under stable conditions in winter, average peak benzene concentrations (1.1 ppb) were 120% higher than for well-mixed conditions (0.5 ppb). By comparison, summertime peak benzene concentrations increased by 53% from well-mixed (0.45 ppb) to stable nocturnal conditions (0.7 ppb). An idealised box model incorporating a simple advection term was used to derive a nocturnal mixing length scale based on radon, and then inverted to simulate diurnal benzene and CO emission variations at the city centre. This method effectively removes the influences of local horizontal advection and stability-related vertical dilution from the emissions signal, enabling a direct comparison with hourly traffic density. With the advection term calibrated appropriately, excellent results were obtained, with high regression coefficients in spring and summer for both benzene (r 2 ~0.90–0.96) and CO (r 2 ~0.88–0.98) in the two highest stability categories. Weaker regressions in winter likely indicate additional contributions from combustion sources unrelated to vehicular emissions. Average vehicular emissions during daylight hours were estimated to be around 0.503 (542) kg km −2 h −1 for benzene (CO) in the Bern city centre. Keywords: radon, air quality, urban, atmospheric stability, traffic density, vehicle emissions (Published: 6 September 2016) Citation: Tellus B 2016, 68, 30967, http://dx.doi.org/10.3402/tellusb.v68.30967
42 citations
Cites background from "One year of 222 Rn concentration in..."
...…of the ubiquitous surface-emitted passive tracer radon (e.g. Allegrini et al., 1994; Duenas et al., 1996; Perrino, 2001, 2012; Avino et al., 2003; Galmarini, 2006; Sesana et al., 2006; Chambers et al., 2011, 2015a, 2015b, 2016; Wang et al., 2013; Williams et al., 2013; Kondo et al., 2014; Pitari…...
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TL;DR: In this article, a method of obtaining the quantitative intensity of vertical diffusion during periods of atmospheric stability is presented, which associates the continuous measurement of radon concentration at ground level and the use of a monostatic sodar.
Abstract: This study presents a method of obtaining the quantitative intensity of vertical diffusion during periods of atmospheric stability. This method associates the continuous measurement of radon concentration at ground level and the use of a monostatic sodar. The value of “equivalent mixing height” he is calculated using the radon variation which can be related to the global exchange coefficient of the inversion layer. The sodar detects the thickness of the nocturnal inversion layer. Both systems operated simultaneously over several months at two sites (urban and suburban). In most cases the nocturnal layer was indicated both by sodar echoes and by a large decrease of the he value. In other cases the use of sodar alone can lead to a lack of detection of stable periods which, nevertheless, are shown clearly by radon. The comparison of measurement at two sites shows a modification of nocturnal stability above the urban site. The equivalent exchange coefficients are ∼0.3 m2 s−1 (at the urban site) and 0...
47 citations
"One year of 222 Rn concentration in..." refers background in this paper
...For the sake of completeness it should be mentioned that the detailed studies of Guedalia et al. (1970),10 Clements and Wilkening (1974), Guedalia et al. (1980), Ishimori et al. (1998) and Katoaka et al. (2003), indicate that only sudden drops or increases of pressure (of the order of 10 to 15 hPa)…...
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01 Jan 1971
TL;DR: The rate of radon and thoron exhalation from the ground was measured in the yard of a laboratory to investigate the effects of soil conditions on the exhalations as mentioned in this paper.
Abstract: The rate of radon (222Rn) and thoron (220Rn) exhalation from the ground was measured in the yard of our laboratory to investigate effects of soil conditions on the exhalation; radon and thoron gases released from the ground were directly adsorbed on granular-activated charcoal, and the charcoal was subjected to γ ray spectrometry to estimate the activity of adsorbed radon and thoron gases. Although the rate of radon exhalation was not appreciably changed by a light rainfall, it apparently decreased after a heavy rainfall and remained low for several days. No appreciable seasonal difference was found in the radon exhalation. On the other hand, the thoron exhalation decreased more or less after every rainfall and depended strongly on the moisture of a thin surface soil layer. The rate of thoron exhalation in summer was about twice its value in winter.
45 citations
TL;DR: The rate of radon and thoron exhalation from the ground was measured in the yard of a laboratory to investigate the effects of soil conditions on the exhalations as discussed by the authors.
Abstract: The rate of radon (222Rn) and thoron (220Rn) exhalation from the ground was measured in the yard of our laboratory to investigate effects of soil conditions on the exhalation; radon and thoron gases released from the ground were directly adsorbed on granular-activated charcoal, and the charcoal was subjected to γ ray spectrometry to estimate the activity of adsorbed radon and thoron gases. Although the rate of radon exhalation was not appreciably changed by a light rainfall, it apparently decreased after a heavy rainfall and remained low for several days. No appreciable seasonal difference was found in the radon exhalation. On the other hand, the thoron exhalation decreased more or less after every rainfall and depended strongly on the moisture of a thin surface soil layer. The rate of thoron exhalation in summer was about twice its value in winter.
44 citations
TL;DR: In this article, a measurement method of Rn220 soil emanation is presented, in which some measurements are made by means of an experimental model in the laboratory in order to determine the influence of certain parameters on the emanation rate.
Abstract: A measurement method of Rn220 soil emanation is presented. Some measurements are made by means of an experimental model in the laboratory in order to determine the influence of certain parameters on the emanation rate. The seasonal and daily variations of the Rn220 flux are also studied. It is shown that the seasonal variations are related to soil moisture variations, whereas some daily variations are due to the temperature difference between the air and the soil.
43 citations
"One year of 222 Rn concentration in..." refers background in this paper
...…24 ∗ 3600 ) Bq sm2 , (12) which reduces to: F ≈ (0.0022) Bq sm2 (13) 15 The order of magnitude of F is well within the ranges directly measured in several other locations with characteristics similar to the EMEP station at JRC (e.g. Guedalia et al., 1970; Kataoka et al., 2001; Levin et al., 2002)....
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...For the sake of completeness it should be mentioned that the detailed studies of Guedalia et al. (1970),10 Clements and Wilkening (1974), Guedalia et al. (1980), Ishimori et al. (1998) and Katoaka et al. (2003), indicate that only sudden drops or increases of pressure (of the order of 10 to 15 hPa)…...
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TL;DR: In this paper, a model was developed to simulate the one-dimensional time-dependent vertical diffusion of 222Rn and its decay products in the atmosphere and the simulations indicated that near the air-ground interface a quasi steady state is reached within a few hours after establishment of a particular atmospheric mixing regime.
Abstract: A model has been developed to simulate the one-dimensional time-dependent vertical diffusion of 222Rn and its decay products in the atmosphere. Computed activities and activity ratios as a function of height above the ground are in excellent agreement with experimental data. The simulations indicate that near the air-ground interface a quasi steady state is reached within a few hours after establishment of a particular atmospheric mixing regime. Radioactive equilibrium between radon and its short-lived daughters is approached at all heights except for very close to the ground during weak mixing conditions.
43 citations