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Study of chemical composition of atmospheric aerosols
Gazdošová, Lucie ; Čáslavský, Josef (referee) ; RNDr. P. Mikuška, CSc. (advisor)
Atmospheric aerosols play an important role in various atmospheric issues (effect to the radiation budget of the atmosphere, visibility reduction, smog production, destruction of stratospheric ozone, …). Epidemiological studies proved a correlation between increased mortality and high concentration of ambient particulate matter. Over the past decade, a growing attention has been focused on the organic compounds that are constituents of aerosol particles. Although organic compounds comprise often up to 60% of the total aerosol mass, their composition, concentration and formation mechanisms are not well understood. Diploma thesis will deal with the study of chemical composition of organic compounds bound to atmospheric aerosols with focus on polyaromatic hydrocarbons and sugars. Atmospheric aerosols will be sampled on filters and filter extracts will be analysed for content of studied organic compounds by means of GC, GC-MS or LC, respectively. Development and optimalization of extraction methods (PSE, …) and detection of compounds of interest. Concentration of studied organic compounds in aerosol size fractions PM 10, PM 2.5 and PM 1 will be compared.
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ON OUR RECENT WORK IN STUDYING NEW PARTICLE FORMATION (NPF)
Kovářík, Jiří ; Špalová, Anna ; Roztočil, Petr ; Zíková, Naděžda ; Schwarz, Jaroslav ; Ždímal, Vladimír
New particle formation (NPF) is increasingly gaining attention since it emerged roughly twenty years ago as a field of interest within the aerosol science. It studies the transition process between gas phase molecules, forming clusters and eventually becoming aerosol particles. Thus, this field is a multidisciplinary one, ranging from meteorology, atmospheric chemistry and physics, all the way through physical chemistry towards chemistry and physics of aerosols. \nRecent development of instrumentation techniques allows measuring of sub-5 nm particles and molecule clusters, neutral and also charged ones. Therefore, modern analytical methods based on these measurements are often used for NPF studies.
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PROCESSING OF THE DATA MEASURED WITH CLOUD CONDENSATION NUCLEI COUNTER IN YEAR 2020 FOR SUBMISSION TO EBAS DATABASE
Moravec, Pavel ; Jindra, Tomáš ; Wagner, Zdeněk ; 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 CCN tend to increase the concentration and decrease the size of cloud droplets. This can lead to suppression of precipitation in shallow and short-lived clouds and to greater convective overturning and more precipitation in deep convective clouds, Rose et al.(2010). 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. Measured data are then submitted to the EBAS database, where they are available for the other ACTRIS researchers. In this paper, we present our experience with the processing of the data measured with CCNC for submission to the EBAS database. The data prepared for submission to EBAS from year 2020 are also presented.
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(IN)DEPENDENCE OF AEROSOL ACTIVATION ON CLOUD POSITION
Zíková, Naděžda ; Pokorná, Petra ; Sedlák, Pavel ; Sokol, Zbyněk ; Ždímal, Vladimír
Five in situ campaigns focused on aerosol-cloud interactions were conducted at Mount Milešovka in the Czech Republic to gain more insight into aerosol activation and its dependence on meteorological parameters, mainly vertical air velocity and position within the cloud. The activated fraction was calculated from the difference of concentrations measured behind the whole air inlet and the PM2.5 inlet. The liquid water content (LWC) was calculated from visibility, cloud base position was estimated from ceilometer data. Vertical air velocity was estimated from cloud radar. No strong dependence was found between visibility and vertical velocity, suggesting that the clouds at the station are mostly of advection or inversion origin. Both visibility and LWC depend on the position within the cloud, with the highest LWC values found when the station was between 100 and 400 m above the cloud base, independently of the actual value.
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Methodology for identification of pollution sources using PMF for strategic decision making in air protection - update 2023
Horník, Štěpán ; Sýkora, Jan ; Pokorná, Petra
The presented methodology proposes utilizatíon of the spectroscopy of nuclear magnetic resonance (NMR) as another analytical technique for the identification of compounds in atmospheric aerosols. This technique makes significantly increases the number of deterined substances and thus a number of possible markers, which can be subsequently used together with other methods to identify sources of air pollution using advanced statistical\nanalysis. Among the markers determined by NMR spectroscopy there are several organic and sulfonic acids or carbohydrates, wich are characteristic for relevant sources of air pollution. The updated methodology also shows the identification of a biogenic source that previous methodologies were not able to determine.
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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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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 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.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22019041212342 - PDF
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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
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22019110512053 - PDF
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