National Repository of Grey Literature 20 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Organic compounds and markers from wood combustion in boilers used for household heating
Křůmal, Kamil ; Mikuška, Pavel ; Horák, J. ; Jaroch, M. ; Hopan, F. ; Kuboňová, L.
Organic compounds (polycyclic aromatic hydrocarbons) and organic markers (monosaccharide anhydrides, diterpenoids) used for the identification of aerosol emission sources were measured in the emissions from the combustion of hard and soft wood. Wood was combusted in different boilers used for the residential heating in the Czech Republic, i.e., overfire boiler, boiler with down-draft combustion, gasification boiler and automatic boiler. Emission factors of particles and all measured organic compounds were the highest from the combustion of fuels in the oldest (overfire) boiler.
Parallel Determination of Particulate Ammonium by Using a Continuous Aerosol Sampler and Cascade Impactor
Alexa, Lukáš ; Hlaváčková, H. ; Cigánková, Hana ; Mikuška, Pavel
Ammonia is a significant gaseous pollutant present in the atmosphere. As a neutralizing agent of acidic species ammonia forms particle-phase ammonium (NH4+) salts and contributes thus to formation of secondary atmospheric aerosols (Harrison and Jones, 1995). Aerosols (particulate matter, PM) are responsible for many negative effects on environments and health risks to human. The diameter of PM has significant impact on their environmental exposure, where the decreasing particle size increases the adverse health effects. The ultrafine particles hence play a major role in adverse impact on human health (Ryer-Powder, 1991). Presented paper describes the use of the novel continuous aerosol sampler for online, and a commercial cascade impactor for offline, determination of NH4+ in ambient air.
Oxidative Potential of PM1 and PM2.5 Urban Aerosol and Associated Elements in Three Simulated Lung Fluids
Cigánková, Hana ; Mikuška, Pavel ; Hegrová, J.
Mass concentration of particulate matter (PM) has been used in several epidemiologic studies as an indicatior conenecting PM concentrations with human health effects (Ostro, 1993). However, mass concentration of PM doesn´t consider the different compositions and toxicological effects of its components. Majority of PM mass constitutes low-toxicity components, while minority of trace components may have high toxicological activity (Tonne, 2012). Oxidative potential (OP), defined as the ability of PM to induce oxidative stress, is in recent years recognized as one of the main biological mechanisms considered to be contributing to negative impacts from air pollution exposure. Oxidative stress is caused through the capability of PM to generate reactive oxygen species (ROS) within the lung, which leads to pro-inflammatory responses that can ultimately results in cell apoptosis (Borlaza, 2021).
Change in Size-Resolved Filtration Efficiency of Respirators after Decontamination/Disinfection Treatments
Ondráček, Jakub ; Ondráčková, Lucie ; Dřevínek, M. ; Otáhal, P. ; Vošáhlík, J.
Furthermore, during COVID pandemic many people were using the PPEs for longer time than it was suggested by the manufacturer or tried to use home-made or web \ncommunity recommended decontamination/disinfection/antiviral treatments. Such treatments may severely destroy the structure of the filtration material and alter the \nfiltration properties as compared to the original piece of the PPE and thus not protect the wearer properly against harmful particles. This work aims to estimate the change in the \nsize-resolved filtration efficiency of different respirators after application of selected decontamination/disinfection treatments.
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Three Years of Experience with Measurement of Cloud Condensation Nuclei Concentrations Using Cloud Condensation Nuclei Counter CCN-200
Moravec, Pavel ; Lhotka, Radek ; Ždímal, Vladimír
Aerosol particles in the atmosphere that allow water vapor to condense and form cloud droplets are called Cloud Condensation Nuclei (CCN). Elevated concentrations of \nCCN tend to increase the concentration and decrease the size of droplets. This can lead to suppression of precipitation in shallow and short-lived clouds and to greater convective \noverturning and more precipitation in deep convective clouds. The response of cloud properties and precipitation processes to increasing anthropogenic aerosol concentrations represents one of the largest uncertainties in the current understanding of climate change. One of the fundamental challenges is to determine the ability of aerosol particles to act as CCN under relevant atmospheric conditions. Knowledge of the spatial and temporal distribution in the atmosphere is essential to incorporate the effects of CCN into meteorological models of all scales, Huang et al. (2007). Long-term CCN measurements are performed at aerosol monitoring sites such as those forming ACTRIS (Aerosols, Clouds and Trace Gases Research Infrastructure) network. In this paper, we present the three-year experience of measuring CCN concentrations over the National Atmospheric Observatory Košetice (NAOK), a rural background site in the Czech Republic. The first results of these measurements were presented by Mishra et al. (2022)
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The impact of covid-19 restrictions on carbonaceous aerosols at rural background site: importance of vertical distribution
Mbengue, Saliou ; Vodička, Petr ; Komínková, Kateřina ; Schwarz, Jaroslav ; Zíková, Naděžda ; Prokeš, Roman ; Suchánková, Lenka ; Julaha, Kajal ; Ondráček, Jakub ; Holoubek, Ivan ; Ždímal, Vladimír
In this study, EC and OC at 4 m elevation and EC at 230 m elevation showed a similar \nseasonal pattern with higher values in winter and lower values in summer. OC, measured \nat 230 m height showed an opposite behavior with slightly higher values in spring and \nsummer, probably related to the increased contribution of secondary organic carbon \n(SOC). Concentrations were generally higher at 4 m, where there was also a better \ncorrelation between EC and OC, suggesting a greater influence of local sources near the \nsurface.
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An Improved Method for Calculation of the Wet Particle Diameter and tha Kappa Parameters from the CCN Data
Wagner, Zdeněk ; Mishra, Gaurav ; Moravec, Pavel ; Zíková, Naděžda
The study of particle size distribution and hygroscopic growth is important for several reasons. Particle diameter is available experimentally, but the relationship of \nhygroscopic growth to cloud condensation nuclei (CCN) and AMS data can be modeled mathematically. In this paper, we present an improved algorithm for calculating the wet \nparticle diameter and the κ parameter that is faster, more accurate, and more reliable than the algorithm used by other authors.\n
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Dependence of aerosol activation on meteorological conditions
Zíková, Naděžda ; Pokorná, Petra ; Sedlák, Pavel ; Ždímal, Vladimír
Four intensive in-situ campaigns focused on aerosol-cloud interactions were performed in the autumn and spring months from Nov 2018 to Apr 2020 at Milešovka Mountain in Czechia to bring more insight into size-dependent aerosol activation and dependence on its origin for a wide variety of meteorological parameters. Most activated particles were larger than 100 nm, with a mode over 200 nm. For the description of the changes in the activation, no effect of photochemistry was found, in contrast, some dependence on relative humidity, temperature, wind speed, and liquid water content (LWC) proved to be useful. The strongest connection was found between activation and LWC. For LWC below 0.1 g/m3, in the LWC-limited regime, the LWC values and variables effecting the LWC were the main factors influencing the activation, while different parameters could have played a role at LWCs over 0.1 g/m3, in the LWC-independent regime.
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NMR Aerosolomics Study of Water-Soluble Organic Compounds in Size-Resolved Particulate Matter
Horník, Štěpán ; Vodička, Petr ; Pokorná, Petra ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
Organic aerosols (OA) account for a significant fraction (10 – 90%) of atmospheric particulate matter (Hallquist et al., 2009). The composition of organic aerosols is very complex and is usually characterized by their water solubility. Water-soluble organic compounds (WSOC) constitute a large fraction of OA (10 – 80%) and consist of chemical species containing oxygenated functional groups such as hydroxyl, carboxyl, or carbonyl groups. NMR spectroscopy represents an alternative to commonly used techniques (gas chromatography-mass spectrometry, liquid chromatography-based techniques) for WSOC analysis. Our recently introduced method, called NMR aerosolomics, allows quantitative analysis of dozens of individual compounds from different aerosol samples. An important part of the characterization of aerosols is their classification by particle size. The analysis of individual compounds in the size-resolved fractions of the WSOC class has been performed only in a few studies that focus mainly on a particular subclass of compounds or use multiple analytical techniques.
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10-year monitoring of oxidative stress in people professionally exposed to nanoparticles using non-invasive methods
Pelclová, D. ; Ždímal, Vladimír
Elemental contents were analyzed by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM /EDS). The total particle number concentration \nranged from 1.98x104 to 5.4x105/cm3 and the nanoparticle fraction was 40-95%. Panels of oxidative stress biomarkers in the form of lipids, nucleic acids and protein damage were analyzed in exhaled breath condensate (EBC), plasma and urine pre-shift and post-shift using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS /MS). Markers for oxidation of lipids, nucleic acids, and proteins in EBC and plasma were already elevated in pre-shift samples (p < 0.05) of workers compared to controls and showed additional post-shift elevation. The best time to collect all samples is post-shift at the end of the work week. Then, markers of oxidative stress in all three \nbiological fluids, including urine, reflect both acute (cross-shift) and chronic effects of exposure.
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