The development of industry, transport, agriculture and power engineering inevitably create problems related to the impact of generated waste on the environment as well as other undesirable processes. The atmosphere is the main component of the Earth’s climate system because changes occurring due to the human economic activity result in serious environmental impacts in all components of the ecosystem as well as the Earth’s climate self-regulation system is disturbed. The objective of this work was to investigate the origin, sources and formation of organic compounds and black carbon in atmospheric aerosol particles and to develop new research methods. To attain this objective the following tasks have been formulated: Development of the identification method for the aerosol origin and source by investigating the carbon isotope mass ratios, illustration of possibilities of the carbon isotope ratio method by identifying the aerosol particle origin during the air mass long-range transport at the Preila Environmental pollution research station, investigation of variation of the black carbon amount in aerosol particles in the diesel engine exhaust depending on the engine working parameters and fuel composition, investigation of the carbon isotope ratio variation in natural aerosol depending on the aerosol particle size distribution, determination of the partial contribution of natural and anthropogenic particles in aerosol by investigation of stable carbon and radiocarbon isotope... [to full text] / Žemės atmosfera yra svarbiausia klimato sferos dalis ir jautriausias antropogeninei taršai aplinkos sandas. Atmosferoje vykstantys procesai pakeičia ekosistemose per šimtmečius nusistovėjusius procesus – stebime įvairias globalinės klimato kaitos sukeltas pasekmes. Mokslinė šio darbo idėja nukreipta į įvairiapusį atmosferos aerozolio dalelių savybių ir prigimties tyrimą bei tyrimo metodų plėtrą, pasiremiant naujausiomis aplinkotyros mokslo žiniomis, akcentuojant pastarojo dešimtmečio masių spektrometrijos pasiekimus. Šio darbo tikslas yra organinių medžiagų ir juodosios anglies atmosferos aerozolio dalelėse kilmės, aerozolio sudėties ir formavimosi tyrimai bei naujų tyrimo metodų plėtra. Darbe eksperimentiškai įrodyta, kad anglies izotopų santykis antropogeninės kilmės aerozolio dalelėse atitinka deginamo kuro izotopų santykį ir šis parametras tinka, identifikuojant aerozolio dalelių šaltinį. Šis izotopų santykis, kaip metodinė priemonė, buvo panaudotas tiriant įvairios prigimties aerozolio sudėtį, savybes ir kilmę. Tiriant aerozolio daleles tolimojoje oro pernašoje stebėjome elementinės anglies δ13C verčių kaitą akumuliacinėje modoje nuo -22,9 ‰ iki -26,3 ‰, organinės anglies δ13C = -28 ‰. Iš δ13C verčių nustatyta, jog elementinės anglies pirmtakai aerozolio dalelėse buvo degimo produktai, organinės anglies šaltinis – lakūs organiniai junginiai iš augalų. Vietinės kilmės dalelių, didesnių už 1 μm, stebėta karbonatinė komponentė. Apjungus masių ir izotopų santykių masių... [toliau žr. visą tekstą]

Žemės atmosfera yra svarbiausia klimato sferos dalis ir jautriausias antropogeninei taršai aplinkos sandas. Atmosferoje vykstantys procesai pakeičia ekosistemose per šimtmečius nusistovėjusius procesus – stebime įvairias globalinės klimato kaitos sukeltas pasekmes. Mokslinė šio darbo idėja nukreipta į įvairiapusį atmosferos aerozolio dalelių savybių ir prigimties tyrimą bei tyrimo metodų plėtrą, pasiremiant naujausiomis aplinkotyros mokslo žiniomis, akcentuojant pastarojo dešimtmečio masių spektrometrijos pasiekimus. Šio darbo tikslas yra organinių medžiagų ir juodosios anglies atmosferos aerozolio dalelėse kilmės, aerozolio sudėties ir formavimosi tyrimai bei naujų tyrimo metodų plėtra. Darbe eksperimentiškai įrodyta, kad anglies izotopų santykis antropogeninės kilmės aerozolio dalelėse atitinka deginamo kuro izotopų santykį ir šis parametras tinka, identifikuojant aerozolio dalelių šaltinį. Šis izotopų santykis, kaip metodinė priemonė, buvo panaudotas tiriant įvairios prigimties aerozolio sudėtį, savybes ir kilmę. Tiriant aerozolio daleles tolimojoje oro pernašoje stebėjome elementinės anglies δ13C verčių kaitą akumuliacinėje modoje nuo -22,9 ‰ iki -26,3 ‰, organinės anglies δ13C = -28 ‰. Iš δ13C verčių nustatyta, jog elementinės anglies pirmtakai aerozolio dalelėse buvo degimo produktai, organinės anglies šaltinis – lakūs organiniai junginiai iš augalų. Vietinės kilmės dalelių, didesnių už 1 μm, stebėta karbonatinė komponentė. Apjungus masių ir izotopų santykių masių... [toliau žr. visą tekstą] / The development of industry, transport, agriculture and power engineering inevitably create problems related to the impact of generated waste on the environment as well as other undesirable processes. The atmosphere is the main component of the Earth’s climate system because changes occurring due to the human economic activity result in serious environmental impacts in all components of the ecosystem as well as the Earth’s climate self-regulation system is disturbed. The objective of this work was to investigate the origin, sources and formation of organic compounds and black carbon in atmospheric aerosol particles and to develop new research methods. To attain this objective the following tasks have been formulated: Development of the identification method for the aerosol origin and source by investigating the carbon isotope mass ratios, illustration of possibilities of the carbon isotope ratio method by identifying the aerosol particle origin during the air mass long-range transport at the Preila Environmental pollution research station, investigation of variation of the black carbon amount in aerosol particles in the diesel engine exhaust depending on the engine working parameters and fuel composition, investigation of the carbon isotope ratio variation in natural aerosol depending on the aerosol particle size distribution, determination of the partial contribution of natural and anthropogenic particles in aerosol by investigation of stable carbon and radiocarbon isotope... [to full text]

Epoxides have been recently identified as one of the intermediate species in the gas phase oxidation of alkenes. This study investigates the reaction of isoprene oxide and alpha-pinene oxide with sulfuric acid to identify the potential of epoxides as important secondary organic aerosol (SOA) precursors. The reaction was explored using different methods to understand the factors governing the reaction rate and the types of products formed under different conditions. Uptake experiments of epoxides on sulfuric acid using Ion drift-Chemical Ionization Mass Spectrometry (ID-CIMS) showed an irreversible uptake of epoxides at room temperature resulting in the formation of less volatile products like diols, organosulfates and acetals. However, at lower temperatures, dehydration of diols and some rearrangement was the preferred reaction pathway resulting in the formation of higher volatility compounds like hydroxy-alkenes and aldehydes. The uptake coefficients of isoprene oxide and alpha-pinene oxide at room temperature using 96% wt acid were found to be 4x10^-2 and 0.8x10^-2, respectively. Spectroscopic study using Attenuated total reflection-Fourier transform infrared technique (ATR-FTIR) revealed that for both the epoxides, diols were the major identifiable products at low acid concentrations. At higher acid concentrations, acetal formation was observed in case of isoprene oxide, while organosulfate formation was seen for alpha-pinene oxide. No products were identified under neutral conditions due to slow reaction. Bulk studies using Nuclear Magnetic Resonance (NMR) spectroscopy conducted at low acid concentrations showed the presence of 1,2- and 1,4-diols as the major products for isoprene oxide, similar to the results from the ATR-FTIR experiments. Additionally, aldehyde formation was also observed. For alpha-pinene oxide, organosulfate formation was observed in all NMR experiments, unlike ATR-FTIR results, where organosulfate formation was observed only at high acid concentrations. These observations can be attributed to the kinetic isotope effect (KIE) due to use of D2SO4/D2O in NMR experiments rather than H2SO4/H2O. The percent yield of organosulfate products was proportional to the amount of available acidic sulfate. The results from this study suggest that acid hydrolysis of epoxides can result in the formation of a wide range of products under different conditions, that can contribute to SOA growth. It proves that epoxides can be efficient SOA precursors for ambient conditions prevailing in an urban atmosphere.

We have developed novel experiments aimed at understanding whether and how quickly organic aerosols (OA) mix using single-particle mass spectrometry, as different treatments of mixing in regional models significantly affect predicted mass and composition. First, we designed experiments that separate OA formation chemistry from thermodynamics to test whether two populations of particles equilibrate with eachother through the gas phase on experimental timescales. Single-particle mass spectrometry measurements from the aerosol mass spectrometer (AMS) allowed us to quantify the extent of mixing that had occurred. We calibrated this technique using pure-component aerosols with known vapor pressure and phase state, the results of which agreed with a condensation-evaporation model. We then applied these techniques to three atmospherically-relevant situations to determine that: 1) anthropogenic secondary OA (aSOA) does not mix with a surrogate for hydrophobic primary OA (POA), 2) biogenic SOA (bSOA) does not mix with hydophobic POA, and 3) bSOA shows significant mixing with aSOA. The sum of these experiments show that these complex interactions can be measured for atmospherically important systems, a first step towards quantifying activity coefficients for complex OA mixtures. We also investigated mixing within individual particles, using mixed-particles of squalane (a surrogate for hydrophobic POA) and SOA from ↵+pinene + O3 that we determined to contain two separate phases. In these experiments, after formation of the mixed-particles, we perturbed smog chamber with a heat ramp. These data revealed that squalane is able to quickly evaporate from the mixed-particles, and that almost all of the SOA is comprised of material lower in volatility than squalane (a low-volatility constituent of pump oil). For this latter “comparative volatility analysis,” we had to correct for the highly variable collection efficiency (CE) of the mixed particles to correctly calculate the mass fraction of SOA remaining. One of the larger implications of this work is highly dependent on the particle morphology, which we were not able to determine definitively: if indeed the particles are coreshell with squalane inside a thick layer of SOA, our results show that diffusivity within SOA is not ultra-low. Lastly, we present work that furthers our understanding of single-particle CE in the AMS, a quantity especially important for experiments where particle phase is dynamic or there are two separate populations of particles. We report the particle CE of SOA, ammonium sulfate, ammonium nitrate, and squalane. We also determine that half of SOA particles that give meaningful signal, do so at a time later than would be predicted based on their optically-measured flight time through the instrument. We present convincing evidence that the nature of this delay is due to particles ricocheting around the ionization region of the instrument before vaporizing on an auxillary surface near the the vaporizer. This process affects how much mass signal comes from a particle, the particle mass spectrum, and the bulk mass distribution derived from particle time-of-flight mode. Our results also show that while there is no size dependence to CE for SOA, particles that have passed through a thermodenuder have lower CE, implicating oxidation state and/or volatility as a controller of particle bounce.

The indirect effect of aerosols expresses how changes in aerosols would influence clouds and cause impacts on Earth's climate and hydrological cycle. The current assessment of the interactions between aerosols and clouds is uncertain and parameterizations used to represent cloud processes are not well constrained. This thesis first evaluates a cloud activation parameterization by investigating cloud droplet number concentration closure for stratocumulus clouds sampled during the 2005 MArine Stratus Experiment (MASE). Further analysis of the droplet size distribution characteristics using the extended parameterization is performed by comparing the predicted droplet spectra with the observed ones. The effect of dynamical variability on the droplet size distribution evolution is also investigated by considering a probability density function for updraft velocity. The cumulus and stratocumulus cloud datasets from in-situ field measurements of NASA's Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) and Coastal STRatocumulus Imposed Perturbation Experiment (CSTRIPE) campaigns are used for this task. Using the same datasets, the autoconversion rate is calculated based on direct integration of kinematic collection equation (KCE). Six autoconversion parameterizations are evaluated and the effect of turbulence on magnifying collection process is also considered. Finally, a general circulation model (GCM) is used for studying the effect of different autoconversion parameterizations on indirect forcing estimates. The autoconversion rate given by direct KCE integration is also included by implementing a look-up table for collection kernels. Although these studies add more variability to the current estimate of aerosol indirect forcing, they also provide direction towards a more accurate assessment for climate prediction.

Heidelberg, Univ., Diss., 2007. / Online publiziert: 2008.

Zugl.: Karlsruhe, Universiẗat, Diss., 2008.

Thesis (Ph. D.)--University of Sydney, 2007. / Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Pharmacy, Faculty of Pharmacy. Includes bibliographical references. Also issued in print.

Zugl.: Duisburg, Essen, Univ., Diss., 2008

University, Diss., 2003--Würzburg.