National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.03 seconds. 
The origin of air pollution on the basis of one year measurements of PM2.5 and PM10 at two urban background stations in Prague
Schwarz, Jaroslav ; Pokorná, Petra ; Rychlík, Š. ; Škáchová, H. ; Smolík, Jiří ; Ždímal, Vladimír ; Vlček, O. ; Hůnová, I.
The particulate matter (PM) mass concentration in cities corresponds to the sum of the concentrations measured at the background stations and the difference between the city and background stations. For this reason, at high background concentrations of PM, the result of emission reduction measures is low. Most of the reported episodes of increased PM concentrations in winter in central European cities are caused by sources of local or regional origin from the combustion of coal and / or biomass for heating purposes. Improvement of air quality in cities is possible provided that causality is understood, especially when it comes to atmospheric aerosol and its concentration, sources and origin.\nThe aim of the work was to determine the origin of air pollution in Prague on the basis of one year parallel measurements of atmospheric aerosol at two urban background stations.\n\n
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ACTRIS IMP – participation of the Czech republic in the national research infrastructures and ACTRIS Central facilities.
Ondráček, Jakub ; Váňa, M. ; Klánová, J. ; Holoubek, Ivan ; Ždímal, Vladimír
ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure) is pan-european research infrastructure, having the main goals in provision of high quality scientific data and provision of information about short-lived atmospheric components and processes leading to changes in these components in natural and controlled laboratory environment. ACTRIS is a logical continuation of 15-years development of large research infrastructures being funded by member states and European Commission through the Research Infrastructure Programme (including e.g. EARLINET, EUSAAR, CREATE and CLOUDNET).
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NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosol Samples.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
In the recent study, the summer and winter aerosol samples were analyzed using NMR aerosolomics approach. The samples were collected in Prague-Suchdol during summer 2008 and winter 2009 in two different particle size fractions - PM2.5 and PM 10. Around 50 compounds were identified in each aerosol spectrum owing to the comprehensive library. The profile of 86 identified compounds, which were identified in the samples altogether, served as an input data for statistical analysis. Multivariate statistical analysis clearly discriminates the two groups studied. Furthermore, it is possible to determine the most significant compounds.
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Thermodynamic Study of Water Activity in Atmospheric Aerosol Particles.
Asadzadeh, Behnaz ; Bendová, Magdalena ; Ždímal, Vladimír
Atmospheric aerosols are complex mixtures of various inorganic−organic compounds and play significant roles in atmospheric chemistry, earth’s climate, and global radiation budget as well as in human health. Hygroscopicity is the ability of the particle to uptake water from surrounding environment. Hygroscopicity can directly control the size distribution, chemical reactivity, and phase state of aerosol particles and thus contribute to radiative forcing on the climate system, including both the direct forcing by absorbing or scattering light and indirect forcing through activation of cloud condensation nuclei (CCN). Interactions between inorganic−organic may have a crucial impact on the hygroscopic behaviour of aerosol droplets and lead to discrepancies from ideal thermodynamic behavior. The non-ideality of mixtures in aerosol particles influences the gas-particle partitioning and affects the physical state of the condensed phase, potentially leading to liquid-liquid phase separation. Thermodynamic models are key tools to gain insight into the non-ideal behavior of organic-inorganic mixtures. By means of activity coefficients, non-ideal behaviour can be taken into account. In this study we developed a thermodynamic segment-based local composition model named NRTL (Non Random Two Liquid) to describe the aktivity coefficients of organic and inorganic aerosol particles.\n
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Measurement of Cloud Condensation Nuclei Concentrations at National Atmospheric Observatory Košetice.
Moravec, Pavel ; Ondráček, Jakub ; Pokorná, Petra ; Ždímal, Vladimír
In this presentation, we report first experience and results of CCN measurements using Dual Column Cloud Condensation Nuclei Counter at the National Atmospheric Observatory Košetice (NAOK), a rural background site in the Czech Republic.
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NMR Aerosolomics as a Tool to Distinguish Various Types of Aerosols.
Horník, Štěpán ; Schwarz, Jaroslav ; Ždímal, Vladimír ; Sýkora, Jan
Water-soluble organic compounds represent up to 80% of all organic compounds present in atmospheric aerosols. Unlike composition of inorganic compounds or volatile organic compounds, which seems to be well explored, the knowledge about WSOC composition is still rather limited. The most frequently used method for WSOC analysis is GC-MS, which is a very sensitive technique. However, the analysis of polar compounds via GC-MS requires derivatization and the quantification is extremely time consuming. The second widely used technique is ion chromatography (IC). Nowadays, IC is routinely used for analysis of specific groups of organic compounds such as carboxylic acids, amines or carbohydrates. On the other hand, there is NMR spectroscopy as a fully quantitative but rather insensitive method. NMR spectroscopy was for the purpose of aerosol chemistry employed only recently as this technique has undergone rapid development and sensitivity gain of late. So far, the use of NMR spectroscopy is mainly restricted to socalled Functional Group Analysis, of which main interest lies elsewhere than in identification of individual compounds.
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Origin of Atmospheric Aerosol Based on Data with Different Time Resolution at the National Atmospheric Observatory Košetice.
Pokorná, Petra ; Zíková, Naděžda ; Lhotka, Radek ; Vodička, Petr ; Makeš, Otakar ; Mbengue, Saliou ; Holubová Šmejkalová, Adéla ; Schwarz, Jaroslav ; Ondráček, Jakub ; Ždímal, Vladimír
To improve the air quality the underlying causalities must be well understood,particularly when it comes to aspects such as PM concentration, sources and their origin. The aim of this work was to determine air pollution origin at NAOK based on atmospheric aerosol (AA) data of different time resolution measured during intensive summer campaing.
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Identification of Sources of Polycyclic Aromatic Hydrocarbons in Central Europe.
Lhotka, Radek ; Pokorná, Petra ; Zíková, Naděžda
This study evaluates the trends and sources of polycyclic aromatic hydrocarbons (PAH) monitored at National atmospheric observatory Košetice (NAOK), a rural background site. In total, 14 PAH concentrations in particulate matter (PM10) between 2006 and 2016 were evaluated. The highest concentrations of all PAH were measured at the beginning of the study period, in 2006. The positive matrix factorization (EPA PMF 5.0) was used to determine the sources of PAH at NAOK, with three factors resolved. The probable origin areas of PMF factors were identified by Conditional Bivariate Probability Function method (CBPF) and Potential Source Contribution Function method (PSCF) methods. NAOK is affected by local sources of PAH, as well as by regional and long-range transport.
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Five Years of Aerosol Particles Growth Rate Measurements at Four Background Stations in the Czech Republic.
Holubová Šmejkalová, Adéla
In this work we used data on aerosol particle number size distribution to investigate if there are any differences or similarities in the growth rate at four background stations located in different types of environment (urban, industrial, agricultural and suburban).
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