Radon-based atmospheric stability classification in contrasting sub-Alpine and sub-Mediterranean environments

A prediction index of the volatile organic compounds pollution conditions in a chemical industrial park based on atmospheric stability

Volatile organic compounds (VOCs), as common precursors of ozone (O3) and fine particulate matter (PM2.5), are a focus of air pollution prevention and control. Furthermore, with the rapid development of industry, industrial sources have become the largest source of anthropogenic VOCs emissions, leading to economic development while causing great harm to the environment. It is becoming meaningful to efficiently predict the future total volatile organic compounds (TVOC) pollution conditions in chemical industrial parks (CIPs), which can assist managers in carrying out corporate emission management in advance. In this study, TVOC monitoring data and meteorological data from January 1, 2022, to December 31, 2022, were used to innovatively construct the TVOC pollution index. This index comprehensively considers the atmospheric stability and localized horizontal diffusion conditions and can quickly and accurately predict the variations in the TVOC in a CIP in the next 7 days. In addition, we used synoptic weather patterns and backward trajectory analysis to explore the mechanism of VOCs pollution formation in a CIP. The results show that the combined influences of a westerly wind pattern, temperatures above 30 °C, a subtropical high pressure system, more upwind pollutants, and the horizontal and vertical diffusion conditions in the CIP were unfavorable, leading to VOCs pollution.

Investigating the vertical and spatial extent of radon-based classification of the atmospheric mixing state and impacts on seasonal urban air quality

A recently-developed radon-based method for combined classification of both diurnal and synoptic timescale changes in the atmospheric mixing state is applied to 1-year of observations in Ljubljana (capital of Slovenia). Five diurnal-timescale mixing classes (#1 to #5) were defined for each season along with an additional mixing class (#6) in non-summer months, representative of synoptic-timescale changes of the atmospheric mixing state associated with "persistent temperature inversion" (PTI) events. Seasonal composite radiosonde profiles and mean sea level pressure charts within each mixing class are used to demonstrate the link between prevailing synoptic conditions and the local mixing state, which drives changes in urban air quality. Diurnal cycles of selected pollutants (BC, NO₂, CO, PM₁₀, SO₂ and O₃) exhibited substantial seasonality as a result of changing mixing conditions, source types and strengths. For the more well-mixed conditions (classes #2 to #3), surface wind speeds were 3 times higher than during class #6 (PTI) conditions, resulting in a 3-fold reduction of primary pollutant accumulation. Daily-mean PM₁₀ concentrations only exceeded EU and WHO guideline values in winter and autumn for two of the radon-defined mixing classes: (i) class #5 (strongly stable near-surface conditions associated with passing synoptic anti-cyclone systems), and (ii) class #6 (PTI conditions driven by regional subsidence in the presence of the "Siberian High"). Both mixing states were associated with low mean wind speeds (∼0-0.7 m s^-1) and strong thermal stratification, as indicated both by pseudo-vertical temperature gradients (∆T/∆z) and radiosonde profiles. Diurnal ∆T/∆z values indicated limited opportunity for convective mixing of pollutants from the basin atmosphere under these conditions. The demonstrated consistency in atmospheric mixing conditions (vertically and spatially) across the diurnal cycle within each of the defined mixing classes suggests the radon-based classification scheme used in conjunction with 3-D urban sensor networks could be well suited to evaluate mitigation schemes for urban pollution and urban climate.

Outdoor Radon as a Tool to Estimate Radon Priority Areas-A Literature Overview

Doses from the exposure to outdoor radon are typically an order of magnitude smaller than those from indoor radon, causing a greater interest on investigation of the latter for radiation protection issues. As a consequence, assessment of radon priority areas (RPA) is mainly based on indoor radon measurements. Outdoor radon measurements might be needed to guarantee a complete estimation of radiological risk and may help to improve the estimation of RPA. Therefore, authors have analysed the available literature on outdoor radon to give an overview of outdoor radon surveys and potential correlation with indoor radon and estimation of RPA. The review has shown that outdoor radon surveys were performed at much smaller scale compared to indoor radon. Only a few outdoor radon maps were produced, with a much smaller density, covering a larger area, and therefore putting doubt on the representativeness of this data. Due to a large variety of techniques used for outdoor radon measurements and requirement to have detectors with a high sensitivity and resistance to harsh environmental conditions, a standardised measurement protocol should be derived. This is no simple endeavour since there are more applications in different scientific disciplines for outdoor radon measurements compared to indoor radon.

Online monitoring of lead-214 (214Pb) on atmospheric aerosols by low-resolution gamma-ray spectrometry

This paper provides a new approach that simplifies the monitoring of ²¹⁴Pb activity concentration on aerosols in the atmospheric surface layer. The approach allows obtaining data on ²¹⁴Pb activity concentration with the discreteness of 2 h. The experimental setup described in the paper made it possible to achieve a minimum detectable activity level of 0.4 Bq m^-3. Using this approach, the data on the diurnal variability of ²¹⁴Pb activity concentration in the atmosphere of Sevastopol city for a period of 18 months were obtained. The ²¹⁴Pb activity concentration varied from < 0.4 (less than 1% of the data series) to 8.9 Bq m^-3, mean value 2.0 ± 1.0 Bq m^-3. The analysis of the temporal variability of ²¹⁴Pb activity concentration on different time scales (diurnal, seasonal) was carried out. Annually averaged diurnal variation curve of ²¹⁴Pb activity concentration showed a peak at 6:00 local time and a minimum at 18:00. The maximum variability in the seasonal averaged diurnal cycle of ²¹⁴Pb activity concentration is observed in summer (± 30% of the daily average value) and the minimum in winter (± 13%). The maximum seasonal average value of ²¹⁴Pb activity concentration is observed in winter (2.5 Bq m^-3) and the minimum in summer (1.4 Bq m^-3). A quantitative estimate of the annual effective dose due to exposure to outdoor radon was obtained by using ²¹⁴Pb data, and it was 0.03 mSv a^-1.

EFFECTIVE DOSES DUE TO OUTDOOR AND INDOOR RADON AT A MEDITERRANEAN SITE

A year-long continuous measurement of the radon activity concentration in the outdoor air at a Mediterranean site has shown a range of 2-144 Bq m-3 and annual mean of 18 ± 14 Bq m-3. Seasonal means were: 15 ± 10 Bq m-3 in winter, 15 ± 12 Bq m-3 in spring, 22 ± 19 Bq m-3 in summer and 17 ± 12 Bq m-3 in autumn. In summer, the average radon activity concentration in the daytime (6-22 h) was 15.2 Bq m-3 and in the night-time (22-6 h) 33.4 Bq m-3. The annual effective dose was 1.83 mSv, with 1.66 mSv from indoor and 0.17 mSv (9%) from outdoor radon. The related doses for the summertime were (mSv): 0.29, 0.24 and 0.05 (18%).