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Povzetek: The study presents 8-years long dataset (2017–2025) of high-resolution radon concentration measurements in Županova Jama and 2-years long dataset (2022–2024) in Postojnska Jama. Radon concentrations from two show caves were compared with outside and cave air temperature as well as atmospheric pressure to assess diurnal and seasonal variability. Županova Jama showed consistently higher radon levels with a 2023 mean of 4030 Bq/m³, compared to 2278 Bq/m³ in Postojnska Jama. Diurnal variations occurred in both caves, with night values typically higher in Županova Jama, while Postojnska Jama displayed day and night concentrations more balanced depending on ventilation regimes. In Postojnska Jama, summer radon maxima followed outside air temperature peaks with a 12–18 h lag. Seasonally, both caves showed higher radon concentrations in summer and lower in winter. Long-term monitoring near Županova Jama revealed an increase in mean outside air temperature (+0.86 °C from 2018 to 2024) and a parallel rise in radon, particularly in 2023–2024. The influence of atmospheric pressure was found to be seasonally dependent at both sites, with higher radon concentrations during periods of stable summer pressure and lower values during higher winter oscillations. Exposure limits indicate safe annual times of 512 h for Postojnska Jama and 284–289 h for Županova Jama, values not hazardous for visitors but important for cave guides. The findings underline the importance of continuous monitoring and cave-specific ventilation management to mitigate long-term health risks.
Ključne besede: radon concentration, air temperature, atmospheric pressure, radiation exposure levels, Postojnska jama, Županova Jama, Slovenia
Objavljeno v DiRROS: 24.05.2026; Ogledov: 119; Prenosov: 104
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Povzetek: This review highlights a significant gap in the multi-pollutant characterisation of ultrafine particulate matter (PM <0.1 µm), focusing on metal(oid)s and polycyclic aromatic hydrocarbons (PAHs). Fractionation mechanisms, sampling protocols and analytical methods are examined with an emphasis on integrating quality assurance measures to ensure high-quality data and facilitate cross-study comparability. Based on studies published between 2010 and 2025, research has largely focused on the analysis of pollutants bound to PM2.5 or PM10. Only 5% of the studies addressed ultrafine particles (UFPs), which have the greatest toxicological impacts. The measurement of both pollutant groups within a single sampling campaign was rare (14% of the studies). The reliability of analytical data was rarely evaluated. Only 33% of the studies employed certified reference materials for quality control and method validation. Microwave-assisted digestion and ultrasound-assisted extraction were commonly used for sample preparation prior to the determination of metal(oid)s and PAHs, by inductively coupled plasma mass spectrometry and gas chromatography–mass spectrometry, respectively. Both pollutant groups exhibited strong seasonal variability, with elevated concentrations observed during heating periods in cold seasons, as well as associated with fine PM and UFPs, fractions that exhibit high bioaccessibility. Smaller PM fractions were associated with anthropogenic sources, including fossil fuel and biomass combustion, traffic and industrial emissions, while coarse PM reflected naturally-derived crustal material. Overall, these findings highlight the importance of uniform and comprehensive protocols for sampling UFPs and quantifying associated pollutants, which are essential for reliable data and effective urban air quality control strategies aimed at mitigating emissions.
Ključne besede: particulate matter, urban air quality, sampling protocols, analytical methods, metal(oid)s, polycyclic aromatic hydrocarbons
Objavljeno v DiRROS: 15.05.2026; Ogledov: 148; Prenosov: 174
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Povzetek: Frost hollows are areas where cold air pools frequently form due to relief, resulting in specific microclimatic conditions. The different microclimate also manifests itself in specific ecological conditions where only adapted plant communities develop. These unique areas are of high conservation impor-tance as they can provide suitable habitats for cold-adapted plant species that are not found in the surrounding landscape. Such microrefugia are known to maintain relict populations of some endemic species. It can be concluded that frost hollows are special areas in terms of both geodiversity and biodiversity. The chapter discusses the climatological and vege-tation characteristics of frost hollows from the Slovenian alpine areas.
Ključne besede: Mountain climate, topoclimate, temperature inversion, vegetation inversion, cold air pools, mountain species adaptation
Objavljeno v DiRROS: 05.03.2026; Ogledov: 284; Prenosov: 184
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Povzetek: Preventing the spread of airborne diseases in crowded indoor spaces is a global challenge. Infected individuals release virus-laden respiratory droplets (RDs) that can remain suspended in air and infectious for hours. Current monitoring methods cannot distinguish these droplets from airborne particulate matter (PM) in a real time. Here, we present a capacitive sensor that selectively detects and counts the individual droplets in indoor spaces, regardless the presence of PM. The device exploits the dielectric constant (ε) of water (78.2) to differentiate the droplets from solid PM particles (ε < 15). In a nonventilated conference-room study, RDs concentrations (40–330 RDs/L) were found to be correlated with human occupancy, but not with PM2.5 levels. The developed technology enables a real-time monitoring of number concentration of RDs, which represent a potential health risk when they carry viral or bacterial infections. The detected increase in RD concentration can serve as a trigger for data-driven ventilation and infection-prevention measures, providing an effective tool for mitigating the spread of respiratory diseases in hospitals, schools and other public spaces.
Ključne besede: respiratory droplets, capacitive sensing, indor air monitoring, infection control
Objavljeno v DiRROS: 09.01.2026; Ogledov: 677; Prenosov: 268
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Povzetek: Air lubrication can reduce the frictional resistance of ships, leading to significant fuel cost savings. However, the performance of air lubrication systems varies considerably, depending on the operating conditions. Complex gas morphologies play a crucial role here but are difficult to predict. Such a variety of morphologies (bubbly flow, air layers, or mixed regimes) requires morphology-adaptive methods, such as MultiMorph. This method allows for multiple morphologies of a given phase, including the transfer between them. The injection of gas can result in air bubbles, air layers, or a mixed regime, based on local transfer mechanisms. The ability to predict these morphologies is a distinctive feature of this method. Alternative methods prescribe a specific regime a priori, and do not allow a transition. To assess the suitability of MultiMorph for air lubrication problems, two geometries with different complexities are considered. The first test validates the method against flat plate experiments. Various water velocity and gas flow rate combinations were considered to investigate their influence on gas morphology and the associated drag reduction. The second case features a three-dimensional ship hull geometry with two bubble injectors to test the applicability of the method to a more complex scenario, including a curved geometry. The method performs well in both test cases and qualifies as a useful tool for numerical investigations of air lubrication phenomena.
Ključne besede: air lubrication, air layer, gas injection, bubbly flow, drag reduction, numerical modelling
Objavljeno v DiRROS: 12.12.2025; Ogledov: 567; Prenosov: 260
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