Atmospheric stability effects on potential radiological releases at a nuclear research facility in Romania: Characterising the atmospheric mixing state

Chambers, Scott D.; Galeriu, D.; Williams, Alastair G.; Melintescu, A.; Griffiths, Alan D.; Crawford, Jagoda; Dyer, Leisa; Duma, Marin; Zorilă, Bogdan

doi:10.1016/j.jenvrad.2016.01.010

Cited by 24 publications

(38 citation statements)

References 25 publications

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“…As radon fluxes are, across daily timescales, constant to first-order approximation, nocturnal build-up of radon is indicative of atmospheric stability, with highest radon values indicating the most stable atmospheres. This follows the radon-based stability categorisation method described by Chambers et al (2016a) and . In the dry season (left), it can clearly be seen that the magnitude of nocturnal GEM depletion increases with increasing stability and, conversely, little to no depletion occurs under well-mixed boundary layers.…”

Section: Diurnal Variationmentioning

confidence: 99%

Atmospheric mercury in the Southern Hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

et al. 2017

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Abstract. Mercury is a toxic element of serious concern for human and environmental health. Understanding its natural cycling in the environment is an important goal towards assessing its impacts and the effectiveness of mitigation strategies. Due to the unique chemical and physical properties of mercury, the atmosphere is the dominant transport pathway for this heavy metal, with the consequence that regions far removed from sources can be impacted. However, there exists a dearth of long-term monitoring of atmospheric mercury, particularly in the tropics and Southern Hemisphere. This paper presents the first 2 years of gaseous elemental mercury (GEM) measurements taken at the Australian Tropical Atmospheric Research Station (ATARS) in northern Australia, as part of the Global Mercury Observation System (GMOS). Annual mean GEM concentrations determined at ATARS (0.95 ± 0.12 ng m −3 ) are consistent with recent observations at other sites in the Southern Hemisphere. Comparison with GEM data from other Australian monitoring sites suggests a concentration gradient that decreases with increasing latitude. Seasonal analysis shows that GEM concentrations at ATARS are significantly lower in the distinct wet monsoon season than in the dry season. This result provides insight into alterations of natural mercury cycling processes as a result of changes in atmospheric humidity, oceanic/terrestrial fetch, and convective mixing, and invites future investigation using wet mercury deposition measurements. Due to its location relative to the atmospheric equator, ATARS intermittently samples air originating from the Northern Hemisphere, allowing an opportunity to gain greater understanding of inter-hemispheric transport of mercury and other atmospheric species. Diurnal cycles of GEM at ATARS show distinct nocturnal depletion events that are attributed to dry deposition under stable boundary layer conditions. These cycles provide strong further evidence supportive of a "multihop" model of GEM cycling, characterised by multiple surface depositions and re-emissions, in addition to long-range transport through the atmosphere.

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Section: Diurnal Variationmentioning

confidence: 99%

Atmospheric mercury in the Southern Hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

et al. 2017

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“…Finally, the studies by Chambers et al (2015aChambers et al ( , 2015bChambers et al ( , 2016 conclusively demonstrate the superiority of the radon-based stability classification over the commonly used measures of Pasquill-Gifford 'turbulence' or 'radiation' schemes. Radon-based techniques are suited to nocturnal pollution studies because atmospheric radon concentrations near the surface are directly and unambiguously related to the integrated outcome of the turbulent mixing process over a relatively large local footprint, and are comparatively unaffected by site-specific variations in surface flow (roughness) and heating patterns (Williams et al, 2013;Chambers et al, 2015aChambers et al, , 2016. Furthermore, the radon-based stability measures used here can be easily adjusted to suit the regional climatology .…”

Section: Radon-based Atmospheric Stability Classificationmentioning

confidence: 82%

“…concentrations of the ubiquitous surface-emitted passive tracer radon (e.g. Allegrini et al, 1994;Duenas et al, 1996;Perrino, 2001Perrino, , 2012Avino et al, 2003;Galmarini, 2006;Sesana et al, 2006;Chambers et al, 2011Chambers et al, , 2015aChambers et al, , 2015bChambers et al, , 2016Wang et al, 2013;Williams et al, 2013;Kondo et al, 2014;Pitari et al, 2014;Omori and Nagahama, 2016). Radon-derived measures of atmospheric stability, based on accumulation/dilution patterns of radon near the surface, are rapidly gaining acceptance because they are better suited to the analysis of mixing-related changes in nocturnal urban air pollution concentrations than the more traditional techniques based on climatological or turbulence measurements.…”

Section: Radon-based Atmospheric Stability Classificationmentioning

confidence: 99%

Radon as a tracer of atmospheric influences on traffic-related air pollution in a small inland city

Williams¹,

Chambers²,

Conen³

et al. 2016

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T 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 Â0.90Á0.96) and CO (r 2 Â0.88Á0.98) 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.

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“…This investigation is a companion study to Chambers, Galeriu, et al (). The specific objectives of this study are (i) to improve upon the existing radon‐based nocturnal stability classification technique developed by Chambers, Galeriu, et al () and thereby develop an atmospheric class typing technique for urban observations by extending the nocturnal stability classification to whole 24‐hr periods; (ii) to show how to quantify radon‐based atmospheric stability classes at a given site according to conventional stability classification approaches; (iii) to demonstrate the superiority of the radon‐based class typing approach; and (iv) to build upon the findings of Chambers, Galeriu, et al () by showing how effective objective classification of the atmospheric mixing state is regarding the interpretation and understanding of surface‐atmosphere radiation and energy exchange processes in the urban environment.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the State of the Urban Surface Layer Using Radon‐222

et al. 2019

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Four years of summertime paired urban‐rural meteorological and radon observations in central Poland are used to assess the relationship between atmospheric stability and urban‐induced changes to the radiation balance and surface energy budget. An existing radon‐based technique for nocturnal stability classification is improved and extended to also infer daytime mixing conditions. The radon‐based scheme is shown to provide a simple, effective, objective means of investigating urban energy budget closure over a range of meteorological conditions, which promises to improve estimates of energy storage and loss terms associated with urban canopies. Special attention is paid to quantifying atmospheric characteristics associated with the arbitrarily assigned radon‐derived stability categories in terms of the more conventional measures: bulk Richardson number and the Monin‐Obukhov stability parameter (z/L). The bulk Richardson number approach is demonstrated to be less effective at grouping periods of similar mean stability, and less selective of extremely stable conditions, than the radon‐based technique. A simple box model is used in conjunction with radon observations and an assumed source function of 15 mBq·m−2·s−1, to show that nocturnal effective mixing heights were deeper and less variable over the urban region. On stable nights hourly median effective mixing heights were 15–20 m over the rural region compared to 40–45 m over the urban region.

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Atmospheric stability effects on potential radiological releases at a nuclear research facility in Romania: Characterising the atmospheric mixing state

Cited by 24 publications

References 25 publications

Atmospheric mercury in the Southern Hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

Atmospheric mercury in the Southern Hemisphere tropics: seasonal and diurnal variations and influence of inter-hemispheric transport

Radon as a tracer of atmospheric influences on traffic-related air pollution in a small inland city

Characterizing the State of the Urban Surface Layer Using Radon‐222

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