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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Origin, chemical composition and formation of submicron aerosol particles in the atmosphere / Atmosferos aerozolio submikroninės frakcijos dalelių kilmė, cheminė sudėtis bei formavimasis

Garbarienė, Inga 20 May 2014 (has links)
The objective of the work was to investigate physical and chemical properties and sources of the atmospheric aerosol particles in the submicron fraction by combining different analytical techniques. The dependence of concentrations of organic and elemental carbon in different air masses was determined and the contribution of regional and local sources to the net aerosol particle pollution was estimated. Analysis of the size distribution of carbonaceous aerosol particles in background and urban areas was performed. Biogenic organic aerosol made up 15 % of the organic aerosol mass at the Preila atmospheric pollution research station, but in the North Atlantic air masses this factor was up to 50 %. Aerosol and stable isotope ratio mass spectrometry has revealed that traffic is the primary source of aerosol particles in the city, while biomass burning is the primary source at the Rūgšteliškis background station. It was determined that secondary anthropogenic organic compounds were dominating (76 %) in Vilnius, while in Rūgšteliškis secondary biogenic organic compounds made up 50 % of the total organic aerosol mass. The influence of the long-range air mass transport on the local origin aerosol particle formation and transformation has been evaluated and it has been shown that volcanic aerosol particles can significantly change the concentration, chemical composition and size distribution of local aerosol particles in the submicron range. / Disertacija skirta smulkiosios aerozolio dalelių frakcijos šaltinių, fizikinių ir cheminių savybių įvertinimui kompleksiškai apjungiant įvairius tyrimo metodus. Darbe susieti elementinės ir organinės anglies koncentracijų pokyčiai su tolimąja oro masių pernaša, įvertinta regiono bei vietinių šaltinių įtaka bendrai aerozolio dalelių taršai. Aprašyti anglies turinčių aerozolio dalelių pasiskirstymai pagal dydį foninėse vietovėse ir miesto aplinkoje. Naudojant aerozolio masių spektrometrą Preilos atmosferos užterštumo tyrimų stotyje buvo identifikuotas biogeninis organinių medžiagų šaltinis, kuris vidutiniškai sudaro 15 % nuo organinių medžiagų masės, tačiau Šiaurės Atlanto oro masėje biogeninių medžiagų indėlis siekia net 50 %. Atlikus kompleksinę aerozolio ir stabiliųjų anglies izotopų masių spektrometrinę analizę buvo nustatyta, kad pirminis anglies turinčio aerozolio dalelių šaltinis mieste yra autotransportas, o Rūgšteliškio foninėje vietovėje – biomasės deginimas. Taip pat buvo nustatyta, kad Vilniuje dominavo antropogeninės antrinės organinės medžiagos (76 %), o Rūgšteliškyje vyravo biogeninės antrinės organinės medžiagos (apie 50%). Vertinant tolimosios oro masių pernašos įtaką vietinės kilmės aerozolio dalelių formavimuisi ir kaitai, buvo nustatyta, kad vulkaninės kilmės aerozolio dalelės turi įtakos submikroninės aerozolio dalelių frakcijos koncentracijai, cheminei sudėčiai ir pasiskirstymui pagal dydį.
12

Environmentální a zdravotní zátěž z dopravy a možnosti jejich snižování v konkrétních podmínkách / The Environmental and Health Burden of Transport and the Possibility of its Reduction in Particular Conditions

Dvořáková, Dita January 2018 (has links)
Air quality is affected by many factors, one of the most important is transport, especially road transport. In this thesis, the transport intensity is compared with number/concentrations of particulate matter in the air. The evaluation is carried out for days, weeks and months, analyses are focused mainly on Brno. In addition, the particulate matter concentrations are analysed depending on meteorological conditions (temperature). The conclusion is focused on the possible measures which can reduce the impact of transport on air pollution.
13

Cloud Condensation Nuclei and Ice-Nucleating Particles over the Southern Ocean: Abundance and Properties during the Antarctic Circum-navigation Expedition

Tatzelt, Christian 12 June 2023 (has links)
Aerosol particles acting as cloud condensation nuclei (CCN) or ice nucleating parti- cles (INP) play a major role in the formation and glaciation of clouds. Thereby they exert a strong impact on the radiation budget of the Earth. Data on abundance and properties of both particle types are sparse, especially for remote areas of the world, such as the Southern Ocean (SO). In this work, unique results from ship-borne aerosol-particle-related in situ measurements and filter sampling in the summertime SO region are presented. An overview of CCN and INP number concentrations on the Southern Ocean is provided and, using additional analyses on particle chemical composition and air-mass origin, insights regarding possible CCN and INP sources and origins are presented, with the help of a correlation analysis. CCN number concentrations spanned 2 orders of magnitude, e.g. for a supersaturation of 0.3 % values ranged roughly from 3 to 590 cm⁻³. CCN showed variable contributions of organic and inorganic material. No distinct size-dependence of the CCN hygroscopicity parameter was apparent, indicating homogeneous composition across sizes (critical dry diameter on average between 30 nm and 110 nm). The relative contribution of sea spray aerosol (SSA) to the CCN number concentration was on average small (below 35 %). Ambient INP number concentrations were measured in the temperature range from −4 to −27 °C using an immersion freezing method. Concentrations spanned up to 3 orders of magnitude, e.g. at −16 °C from 0.2 to 100 m⁻³. Elevated values (above 10 m⁻³ at −16 °C) were measured when the research vessel was in the vicinity of land (excluding Antarctica). Lower, more constant concentrations were measured on the open ocean. This, along with results of backward-trajectory analyses, hints towards terrestrial and/or coastal INP sources being dominant close to ice-free (non-Antarctic) land. In pristine marine areas INP may originate from both oceanic sources and/or long range transport. A correlation analysis yielded strong correlations between sodium mass concentration and particle number concentration in the coarse mode (larger 1 µm), unsurprisingly indicating a significant contribution of SSA to that mode. CCN number concentration was highly correlated with the number concentrations of Aitken (10 to 100 nm) and accumulation mode particles (100 to 1000 nm). This, together with a lack of correlation between sodium mass and Aitken and accumulation mode number concentrations, underlines the important contribution of non-SSA, probably secondarily formed particles, to the CCN population.:1 Introduction 2 Fundamentals 2.1 Aerosol particle activation 2.1.1 Köhler theory 2.1.2 κ-Köhler theory 2.2 Ice nucleation 2.2.1 Homogeneous Freezing 2.2.2 Heterogeneous Freezing 3 Campaign, instrumentation, and data handling 3.1 Antarctic Circum-navigation Expedition 3.2 In situ aerosol measurements 3.2.1 Aerosol number size distribution 3.2.2 Cloud condensation nuclei 3.3 Off-line aerosol characterisation 3.3.1 High-volume sampling 3.3.2 Low-volume sampling 3.3.3 Ice nucleation droplet array (INDA) 3.3.4 Analysis of chemical composition 3.4 Further resources 3.4.1 In-water organic compound measurements 3.4.2 Wind measurements 3.4.3 Air-mass origin analysis 3.4.4 Fluorescent particles 3.4.5 Correlation analysis 4 Results and Discussion 4.1 Aerosol particles and cloud condensation nuclei 4.1.1 Particle number size distributions 4.1.2 CCN number concentrations 4.1.3 CCN hygroscopicity 4.1.4 Air-mass origin for aerosol particle and CCN measurements 4.2 Ice nucleating particles 4.2.1 INP abundance 4.2.2 Air-mass origin for INP measurements 4.3 Chemical composition of sampled aerosol particles 4.4 Correlation analysis 5 Summary and Conclusions / Aerosolpartikel, die als Wolkennukleations- oder Eiskeime fungieren, spielen eine Schlüsselrolle in den Entstehungs- und Vereisungsprozessen von Wolken. Mit ihren wolkenrelevanten Eigenschaften haben diese beiden Arten von Aerosolpartikeln einen starken Einfluss auf den Strahlungshaushalt der Erde. Messungen ihrer Häufigkeit und Eigenschaften sind selten, inbesondere in den entlegenen Regionen der Erde wie beispielsweise dem Südlichen Ozean. In dieser Arbeit werden die Ergebnisse von in situ und filterbasierten Partikelmessungen einer Forschungsfahrt auf dem Südlichen Ozean in den Sommermonaten der Südhalbkugel gezeigt. Ein erstmaliger Überblick über die Anzahlkonzentrationen der Wolkennukleations- und Eiskeime über dem Südlichen Ozean wird gegeben. Unter Berücksichtigung weiterer Messergebnisse zur chemischen Zusammensetzung der Partikel und Betrachtungen zur Herkunft der Luftmassen werden Rückschlüsse auf die Herkunft und Quellen der gesammelten, wolkenrelevanten Aerosolpartikel gezogen, auch mit Hilfe einer Korrelationsanalyse. Die Anzahlkonzentration der Wolkennukleationskeime schwankte innerhalb von zwei Größenordnungen, beispielsweise zwischen 3 und 590 cm⁻³ bei 0.3 % Übersättigung. Die chemische Zusammensetzung der Wolkennukleationskeime variierte dabei stark, zwischen organischem und inorganischem Material. Der Hygroskopizitätsparameter zeigte keine Größenabhängigkeit, was für eine intern gemischte Population von Wolkennukleationskeimen spricht (kritische Partikeldurchmesser lagen im Mittel zwischen 30 und 110 nm). Der prozentuale Anteil von Seesalzpartikeln zur Anzahlkonzentration der Wolkennukleationskeime war im Mittel gering (kleiner 35 %). Die Anzahlkonzentration der Eiskeime wurden im Temperaturbereich −4 bis −27 °C mittels einer filterbasierten Immersionsgefriermethode bestimmt. Die Anzahlkonzentrationen schwankten dabei im Bereich von bis zu drei Größenordnungen, beispielsweise zwischen 0.2 und 100 m⁻³ bei einer Temperatur von −16 °C. In Küstennähe, mit Ausnahme von Antarktika, wurden erhöhte Anzahlkonzen- trationen (über 10 m⁻³ bei −16 °C) gemessen. Niedrigere, weniger variable Anzahlkonzentrationen wurden hingegen auf offener See gemessen. Diese Beobachtungen, zusammen mit den Ergebnissen zur Luftmassenherkunft, sprechen für eine Dominanz von terrestrischen und/oder küstennahen Quellen der Eiskeime in der Nähe von eisfreiem (nicht-Antarktischem) Festland. Dabei können in den unbe- rührten, marinen Regionen die Eiskeime aus dem Meer selbst und/oder Ferntransport stammen. Eine Korrelationsanalyse zeigte einen starken Zusammenhang zwischen der Massenkonzentration von Natrium und der Anzahlkonzentration an groben Aerosolpartikeln (größer 1 µm). Daraus folgt ein signifikanter Anteil an Seesalzpartikeln in dieser Partikelgröße. Die Anzahlkonzentration der Wolkennukleationskeime korrelierte stark mit den Anzahlkonzentrationen der Aitken- (10 bis 100 nm) bzw. Akkumulationskerne (100 bis 1000 nm). Diese Beobachtung, zusammen mit dem Fehlen einer Korrelation zwischen Natriummasse und Aitken- oder Akkumulationskernanzahl, unterstreicht die Relevanz von Partikeln die nicht Seesalz sind (vermutlich sekundär geformten Aerosolpartikel) für die Population der Wolkennukleationskeime.:1 Introduction 2 Fundamentals 2.1 Aerosol particle activation 2.1.1 Köhler theory 2.1.2 κ-Köhler theory 2.2 Ice nucleation 2.2.1 Homogeneous Freezing 2.2.2 Heterogeneous Freezing 3 Campaign, instrumentation, and data handling 3.1 Antarctic Circum-navigation Expedition 3.2 In situ aerosol measurements 3.2.1 Aerosol number size distribution 3.2.2 Cloud condensation nuclei 3.3 Off-line aerosol characterisation 3.3.1 High-volume sampling 3.3.2 Low-volume sampling 3.3.3 Ice nucleation droplet array (INDA) 3.3.4 Analysis of chemical composition 3.4 Further resources 3.4.1 In-water organic compound measurements 3.4.2 Wind measurements 3.4.3 Air-mass origin analysis 3.4.4 Fluorescent particles 3.4.5 Correlation analysis 4 Results and Discussion 4.1 Aerosol particles and cloud condensation nuclei 4.1.1 Particle number size distributions 4.1.2 CCN number concentrations 4.1.3 CCN hygroscopicity 4.1.4 Air-mass origin for aerosol particle and CCN measurements 4.2 Ice nucleating particles 4.2.1 INP abundance 4.2.2 Air-mass origin for INP measurements 4.3 Chemical composition of sampled aerosol particles 4.4 Correlation analysis 5 Summary and Conclusions
14

Artificial radionuclides and their interaction with aerosol particles in the Ignalina NPP and its environment / Dirbtiniai radionuklidai ir jų sąveika su aerozolio dalelėmis Ignalinos AE ir jos aplinkoje

Rožkov, Andrej 28 December 2009 (has links)
Investigations on the determination of 137Cs sources in the Ignalina NPP environment air and the evaluation of changes of the long-term trend of 137Cs activity concentrations in the Ignalina NPP ground-level air were carried out in this dissertation. Radionuclide activity concentrations in the air and deposition were measured in the Ignalina NPP impact zone in 2004-2009. Results show, that in recent years annual 137Cs activity concentrations in the ground-level air in the Ignalina NPP region change with the half-time of 30 years. Observed episodic increases in 137Cs activity concentrations in the air correlate well with air mass transport trajectories that intersect territories, polluted with 137Cs after the accident at the Chernobyl NPP. The growth of radioactive aerosol particles in the oversaturated water vapour of the operating RBMK reactor has been investigated. In the one contour nuclear power plant coolant water steam, noble gas radionuclides decay into alkaline and earth-alkali metals, which become condensation nuclei and due to the absorption of water molecules in several minutes grow into radioactive aerosol particles. The classical method of the radionuclide activity determination in aerosol particle samples, collected on filters, was supplemented with experiments on the leaching of aerosol particles using the distilled water and measurements of radionuclide activities in samples before and after the experiment. Results show that the quantity of 137Cs and 60Сo in... [to full text] / Disertacijoje nustatyti 137Cs patekimo į Ignalinos AE aplinkos orą šaltiniai ir įvertinti ilgamečiai 137Cs aktyvumo koncentracijų ore pokyčiai. Radionuklidų aktyvumo koncentracijos ore ir iškritose matuotos nuo 2004 iki 2009 metų Ignalinos AE poveikio zonoje. Gauta, kad metinės 137Cs aktyvumo koncentracijos pažemio ore pastaraisiais metais kinta su 30 metų mažėjimo pusiau trukme. Stebėta, kad šuoliški 137Cs aktyvumo koncentracijų pažemio ore padidėjimai koreliuoja su oro masių pernašos trajektorijomis, kertančiomis teritorijas, užterštas po avarijos Černobylio AE. Nustatytas radioaktyvių aerozolio dalelių augimas prisotintuose vandens garuose veikiančio RBMK reaktoriaus kondensatoriuje. Vieno kontūro atominės elektrinės aušinamame vandens gare inertinių dujų radionuklidai, skildami virsta šarminių ir žemės šarminių metalų elementais, tampa aerozolio gamybos centrais, absorbuoja vandens molekules ir per keliolika minučių ant jų, kaip kondensacijos branduolių, išauga radioaktyvios aerozolio dalelės. Klasikinis radionuklidų aktyvumo aerozolio dalelių, surinktų filtrais, bandiniuose nustatymas papildytas išplovimo distiliuotu vandeniu eksperimentais, matuojant radionuklidų aktyvumą bandiniuose iki ir po eksperimento. Gauta, kad 137Cs ir 60Сo dalis aerozolio dalelių, surinktų veikiančio reaktoriaus ventiliaciniame ore, tirpioje frakcijoje buvo 74 17 %, atitinkamai, o neveikiančio reaktoriaus ventiliaciniame ore 22 % ir 67  5 %. 60Co aktyvumo koncentracijos AE fakele... [toliau žr. visą tekstą]
15

Dirbtiniai radionuklidai ir jų sąveika su aerozolio dalelėmis Ignalinos AE ir jos aplinkoje / Artificial radionuclides and their interaction with aerosol particles in the Ignalina NPP and its environment

Rožkov, Andrej 28 December 2009 (has links)
Disertacijoje nustatyti 137Cs patekimo į Ignalinos AE aplinkos orą šaltiniai ir įvertinti ilgamečiai 137Cs aktyvumo koncentracijų ore pokyčiai. Radionuklidų aktyvumo koncentracijos ore ir iškritose matuotos nuo 2004 iki 2009 metų Ignalinos AE poveikio zonoje. Gauta, kad metinės 137Cs aktyvumo koncentracijos pažemio ore pastaraisiais metais kinta su 30 metų mažėjimo pusiau trukme. Stebėta, kad šuoliški 137Cs aktyvumo koncentracijų pažemio ore padidėjimai koreliuoja su oro masių pernašos trajektorijomis, kertančiomis teritorijas, užterštas po avarijos Černobylio AE. Nustatytas radioaktyvių aerozolio dalelių augimas prisotintuose vandens garuose veikiančio RBMK reaktoriaus kondensatoriuje. Vieno kontūro atominės elektrinės aušinamame vandens gare inertinių dujų radionuklidai, skildami virsta šarminių ir žemės šarminių metalų elementais, tampa aerozolio gamybos centrais, absorbuoja vandens molekules ir per keliolika minučių ant jų, kaip kondensacijos branduolių, išauga radioaktyvios aerozolio dalelės. Klasikinis radionuklidų aktyvumo aerozolio dalelių, surinktų filtrais, bandiniuose nustatymas papildytas išplovimo distiliuotu vandeniu eksperimentais, matuojant radionuklidų aktyvumą bandiniuose iki ir po eksperimento. Gauta, kad 137Cs ir 60Сo dalis aerozolio dalelių, surinktų veikiančio reaktoriaus ventiliaciniame ore, tirpioje frakcijoje buvo 74  22 % ir 67  17 %, atitinkamai, o neveikiančio reaktoriaus ventiliaciniame ore – 24  5 % ir 20  5 %. 60Co aktyvumo koncentracijos AE... [toliau žr. visą tekstą] / Investigations on the determination of 137Cs sources in the Ignalina NPP environment air and the evaluation of changes of the long-term trend of 137Cs activity concentrations in the Ignalina NPP ground-level air were carried out in this dissertation. Radionuclide activity concentrations in the air and deposition were measured in the Ignalina NPP impact zone in 2004-2009. Results show, that in recent years annual 137Cs activity concentrations in the ground-level air in the Ignalina NPP region change with the half-time of 30 years. Observed episodic increases in 137Cs activity concentrations in the air correlate well with air mass transport trajectories that intersect territories, polluted with 137Cs after the accident at the Chernobyl NPP. The growth of radioactive aerosol particles in the oversaturated water vapour of the operating RBMK reactor has been investigated. In the one contour nuclear power plant coolant water steam, noble gas radionuclides decay into alkaline and earth-alkali metals, which become condensation nuclei and due to the absorption of water molecules in several minutes grow into radioactive aerosol particles. The classical method of the radionuclide activity determination in aerosol particle samples, collected on filters, was supplemented with experiments on the leaching of aerosol particles using the distilled water and measurements of radionuclide activities in samples before and after the experiment. Results show that the quantity of 137Cs and 60Сo in... [to full text]
16

Air contamination by particulate matter from processes of building refurbishment and operation / Oro tarša aerozolio dalelėmis pastatų atnaujinimo ir eksploatacijos metu

Prasauskas, Tadas 02 January 2015 (has links)
People spend major part of their life indoors – at home or in other public or private indoor environments. Clean air in the living environment is very important for the public health. Indoor air quality (IAQ) is largely dependent on the outdoor air quality, due to the continuous indoor air mixing with the ambient air. However, air pollutants in buildings are strongly linked to building indoor factors as well (emissions from building structure, fabrics, coating, furnishing, ventilation system, food preparation, occupant activities etc.). Building renovation is mostly based on economic aspects – performing cost-effective refurbishment actions assuming further savings in energy costs, without taking into account possible changes in air quality conditions. Therefore, a natural question arises whether it will be possible to ensure a comfortable and healthy living for occupants. There is a lack of methodologically robust intervention studies that support the improvement of energy efficiency measures by means of improved IAQ. It is also important to improve the knowledgebase in order to support the implementation of the related policies in Europe. In this context, overview of the results from before and after intervention measurements and emissions from building materials were presented, and the implications on IAQ were discussed. The results of the research provide data for the technical and administrative measures for the improvement of IAQ in residential buildings. / Žmonės įprastai praleidžia didžiąją dalį savo laiko patalpose - namuose ar kitų valstybinių ir privačių patalpų aplinkoje. Švaraus oro užtikrinimas gyvenamojoje aplinkoje yra labai svarbus visuomenės sveikatai. Oro teršalai patalpose yra glaudžiai susiję su pastato viduje vykstančiais procesais (emisijos iš pastato konstrukcijos, apdailos medžiagų, buitinių cheminių priemonių, ventiliacijos sistemos, maisto ruošos, gyventojų aktyvumo ir t.t.). Dėl nuolatinio vidaus oro maišymosi su išorės aplinkos oru, patalpų oro kokybė yra taip pat smarkiai įtakojama išorės oro kokybės. Pastatų renovacija daugiausia yra grindžiama ekonominiu aspektu. Atliekant ekonominius pastatų atnaujinimo veiksmus, paremtus didesniu energijos sąnaudų taupymu, neatsižvelgiama į galimus oro kokybės pokyčius. Todėl kyla natūralus klausimas ar po šių procesų pavyks užtikrinti patogią ir sveiką gyvenseną. Šiuo metu yra stygius metodologiškai stiprių mokslinių tyrimų, kurie nagrinėja energijos efektyvumo priemonių didinimo įtaką patalpų oro kokybei. Atsižvelgiant į tai, šiame darbe yra aptariami gauti rezultatai iš oro kokybės tyrimų daugiabučiuose pastatuose jų eksploatacijos metu bei aerozolio dalelių emisijos iš statybinių medžiagų pastato statybos ir atnaujinimo metu. Taip pat parengtos rekomendacijos daugiabučių pastatų atnaujinimui ir eksploatacijai, užtikrinant sveiką patalpų oro kokybę. Tyrimo rezultatai suteikia svarbios informacijos tiek techninėms, tiek ir administracinėms priemonėms, skirtoms... [toliau žr. visą tekstą]
17

Corona ions from high voltage powerlines : production, effect on ambient particles, DC electric field and implications on human exposure studies

Fatokun, Folasade Okedoyin January 2008 (has links)
Powerlines are important in the process of electricity transmission and distribution (T & D) and their essential role in transmitting electricity from the large generating stations to the final consumers cannot be over emphasized. Over the years, an increase in the demand for electrical energy (electricity) has led to the construction and inevitable use of high transmission voltage, sub-transmission voltage and distribution voltage power conducting lines, for the electricity T & D process. Along with this essential role, electricity conductors can also give rise to some electrically related effects such as interference with telecommunication circuits, electric shocks, electromagnetic fields, audible noise, corona ion discharges, etc. The presence of powerline generated corona ions in any ambient air environment can be associated with the local modification of the earth’s natural dc electric field (e-field), while the interactions between these ions and other airborne aerosol particles can be associated with the presence of charged aerosol particles in the environment of the corona ion emitting lines. When considering all the studies conducted to date on the possible direct and indirect effects of high voltage powerlines (HVPLs), of significant interest are those suggesting links between powerlines and some adverse human health effects – with such health effects alleged to be strongest amongst populations directly exposed to HVPLs. However, despite the numerous studies conducted on HVPLs, to date a lack of proper scientific understanding still exist in terms of the physical characterization of the electrical environment surrounding real-world HVPLs - mostly in terms of the entire dynamics of ions and charged particles, as well as the possible links/associations between the different parameters that characterize these electrical environments. Yet, gaining a sound understanding about the electrical environment surrounding energized real-world HVPLs is imperative for the accurate assessment of any possible human exposure or health effects that may be associated with powerlines. The research work presented in this thesis was motivated by the existing gaps in scientific understanding of the possible association between corona ions generated by real-world HVPLs and the production of ambient charged aerosol particles. The aim of this study was to supply some much needed scientific knowledge about the characteristics of the electrical environment surrounding real-world energized HVPLs. This was achieved by investigating the possible effects of corona ions generated by real-world overhead HVPLs on ambient aerosol particle number concentration level, ambient aerosol particle charge concentration level, ambient ion concentration level and the magnitude of the local vertical dc e-field; while also taking into consideration the possible effect of complex meteorological factors (such as temperature, pressure, wind speed wind direction, solar radiation and humidity) on the instantaneous value of these measured parameters, at different powerline sites. The existence of possible associations or links between these various parameters measured in the proximity of the powerlines was statistically investigated using simple linear regression, correlation and multivariate (principal component, factor, classification and regression tree-CART) analysis. The strength of the regression was tested with coefficient of determinations R2, while statistical significance was asserted at the 95 % confidence level. For the powerline sites investigated in this study, both positive and negative polarities of ions were found to be present in the ambient air environment. The presence of these ions was associated with perturbations in the local vertical dc e-field, increased net ambient ion concentrations and net particle charge concentration levels. The mean net ion concentration levels (with a range of 4922 ions cm-3 to -300 ions cm-3) in the ambient environment of these powerlines, were in excess of what was measured in a typical outdoor air (i.e -400 ions cm-3). The mean net particle charge concentration levels (1469 ions cm-3 to -1100 ions cm-3) near the powerlines were also found to be statistically significantly higher than what was obtained for a mechanically ventilated indoor room (-84 ± 49 ions cm-3) and a typical urban outdoor air (-486 ± 34 ions cm-3). In spite of all these measured differences however, the study also indicated that ambient ion concentration as well as its associated effects on ambient particle charge concentration and e-field perturbations gradually decreased with increase in distance from the powerlines. This observed trend provided the physical evidence of the localized effect of real-world HVPL generated corona ions. Particle number concentration levels remained constant (in the order of 103 particles cm-3) irrespective of the powerline site or the sampling distance from the lines. A close observation of the output signals of the sampling instruments used in this study consistently revealed large fluctuations in the instantaneous value of all the measured electrical parameters (i.e. non-periodic extremely high and low negative and positive polarities of ions/charged particles and e-field perturbations was recorded). Although the reason for these observed fluctuations is not particularly known at this stage, and hence in need of further investigations, it is however being hypothesized that, since these fluctuations appear to be characteristic of the highly charged environment surrounding corona ion emitting electrical infrastructures, they may be suggestive of the possibility that the release of corona ions by ac lines are not necessarily in the form of a continuous flow of ions. The results also showed that statistically significant correlations (R2 = 74 %, P < 0.05) exists between the instantaneous values of the ground-level ambient ion and the ground-level ambient particle charge concentration. This correlation is an indication of the strong relationship/association that exists between these two parameters. Lower correlations (R2 = 3.4 % to 9 %, P < 0.05) were however found to exist between the instantaneous values of the vertical dc e-field and the ground-level ambient particle charge concentration. These suggest that e-field measurements alone may not necessarily be a true indication of the ground-level ambient ion and particle charge concentration levels. Similarly, low statistical correlations (R2 = 0.2 % to 1.0 %, P < 0.05) were also found to exist between the instantaneous values of ambient aerosol particle charge concentration and ambient ultrafine (0.02 to 1 μm sized) aerosol particle number concentration. This low level of correlations suggests that the source contribution of aerosol particle charge and aerosol particle number concentration into the ambient air environment of the HVPLs were different. In terms of the implication of human exposure to charged aerosol particles, the results obtained from this study suggests that amongst other factors, exposure to the dynamic mixture of ions and charged particles is a function of : (a) distance from the powerlines; (b) concentration of ions generated by the powerlines; and (c) meteorology - wind turbulence and dispersal rate. In addition to all its significant findings, during this research, a novel measurement approach that can be used in future studies for the simultaneous monitoring of the various parameters characterizing the physical environment of different ion/charged particle emission sources (such as high voltage powerlines, electricity substations, industrial chimney stack, motor vehicle exhaust, etc.) was developed and validated. However, in spite of these significant findings, there is still a need for other future and more comprehensive studies to be carried out on this topic in order to extend the scientific contributions of in this research work.
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A study of aerodynamic deaggregation mechanisms and the size control of NanoActive™ aerosol particles

Hubbard, Joshua A. January 1900 (has links)
Master of Science / Department of Mechanical and Nuclear Engineering / Steven J. Eckels / Christopher M. Sorensen / Large specific surface areas and high concentrations of reactive edge and defect sites make NanoActive™ metal oxide powders ideal chemical adsorbents. These powders are dispersed in aerosol form to remediate toxic wastes and neutralize chemical and biological warfare agents. In the destructive adsorption of toxic chemicals, effective application requires particles be as small as possible, thus, maximizing surface area and number of edge and defect sites. Other applications, e.g. smoke clearing, require particles be large so they will settle in a timely manner. Ideally, particle size control could be engineered into powder dispersion devices. The purpose of this study was to explore particle cohesion and aerodynamic deaggregation mechanisms to enhance the design of powder dispersion devices. An aerosol generator and four experimental nozzles were designed to explore the most commonly referenced deaggregation mechanisms: particle acceleration, particles in shear and turbulent flows, and particle impaction. The powders were then dispersed through the nozzles with increasing flow rates. A small angle light scattering device was used to make in situ particle size measurements. The nozzle designed for impaction deaggregated the NanoActive™ MgO particles to a lesser degree than the other three nozzles, which deaggregated the particles to a similar degree. Flows in three of the four nozzles were simulated in a commercial computational fluid dynamics package. Theoretical particle and aggregate stresses from the literature were calculated using simulated data. These calculations suggest particle acceleration causes internal stresses roughly three orders of magnitude larger than shear and turbulent flows. These calculations, coupled with experimental data, lead to the conclusion that acceleration was the most significant cause of particle deaggregation in these experiments. Experimental data also identified the dependence of deaggregation on primary particle size and agglomerate structure. NanoActive™ powders with smaller primary particles exhibited higher resistance to deaggregation. Small primary particle size was thought to increase the magnitude of van der Waals interactions. These interactions were modeled and compared to theoretical deaggregation stresses previously mentioned. In conclusion, deaggregation is possible. However, the ideas of particle size control and a universal dispersion device seem elusive considering the material dependent nature of deaggregation.
19

Separace aerosolových částic na polymerních membránách / Separation of aerosol particles using polymeric membranes

Morcinek, Tomáš January 2021 (has links)
This diploma thesis deals with the separation of aerosol particles on membranes from polypropylene hollow fibers. As a source of particles, a desktop 3D printer using polymer filaments was used. Filtration efficiency and a pressure drop on a hollow polypropylene fiber membrane and a high efficiency particulate filter (HEPA filter) were monitored during filtration of particles from 3D print using filaments of acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, polylactic acid and polyethylene terephthalate glycol at nearly the same air flow. The results achieved by both filer media are then compared and discussed. The results show that the hollow fiber membrane achieves better filtration efficiency at higher particle concentrations, while using the less emitting materials, the efficiency of the HEPA filter was higher or the same. The total filtration efficiency calculated from all experiments with all filaments was higher for the hollow fiber membrane with higher pressure drop at the same time.
20

Carbohydrates in the Arctic and the Southern Ocean – Chemical Analysis, Transfer from the Sea to the Atmosphere and Potential Relevance for Cloud Formation

Zeppenfeld, Sebastian 05 October 2022 (has links)
Primär emittierte marine Aerosolpartikel haben einen wichtigen Einfluss auf den Strahlungshaushalt der Erde, indem sie unter anderem als Kondensations (CCN)- oder Eiskeime (INP) für die Bildung von Wolken wirken. In den ozeanisch geprägten Polarregionen dominieren diese marinen Aerosolpartikel in der Luft und können dort eine bedeutende bzw. sich noch verändernde Rolle im Rahmen des Klimawandels einnehmen. Sie entspringen vordergründig aus dem ozeanische Oberflächenwasser und dem hauchdünnen Oberflächenfilm, dem sogenannte sea surface microlayer (SML), und werden durch das Platzen von durch Wind eingetragene Luftblasen freigesetzt. Primär emittierte marine Aerosolpartikel bestehen aus anorganischem Meersalz und organischen Kohlenstoffverbindungen, deren relative Anteile sich stark in Abhängigkeit vom Aerosoldurchmessers unterscheiden. In diesem Zusammenhang stellen die marinen Kohlenhydrate eine wichtige organische Stoffgruppe dar, deren ozeanische Quellen, Übergang vom Ozean in die Atmosphäre, Veränderungen in der Atmosphäre als auch deren Beitrag bei der Kondensation und Eiskeimbildung noch nicht ausreichend verstanden sind. Dieser begrenzte Kenntnisstand ist unter anderem auf das mangelnde Vorhandensein analytischer Methoden zurückzuführen, die eine zuverlässige Bestimmung von Kohlenhydraten in den stark salzhaltigen Matrices bei sehr niedrigen Massekonzentrationen mit hohen Wiederfindungsraten gewährleisten. Im Rahmen dieser Doktorarbeit wurde durch Kombination der Hochleistungs-Anionenaustauschchromatographie mit gepulster amperometrischer Detektion (HPAEC-PAD) und einer Entsalzung durch Elektrodialyse eine analytische Methode entwickelt, welche die Bestimmung eines breiten Spektrums an gelösten Kohlenhydraten in freier (als Monosaccharide) und gebundener (als Oligo- oder Polysaccharide) Form in Meerwasser und anderen salzhaltigen Matrices ermöglicht. Mithilfe dieser neuen Methode wurde ein biogeochemischer Zusammenhang zwischen dem Vorkommen von freier Glucose und der eiskeimbildenden Aktivität im arktischen SML beobachtet. Außerdem wurde im meereisfreien Teil des Südlichen Ozeans der primäre Transfer von Kohlenhydraten vom Ozean über den SML in die Atmosphäre und deren sekundäre atmosphärische Veränderungen erforscht. Die umfangreichen Untersuchungen mariner Kohlenhydrate in polarem Meerwasser und Aerosolpartikeln zeigen Indizien einer bisher noch unterschätzten atmosphärischen Bedeutung mikrobiologischer Prozesse auf.:1. Introduction ............................................................................................................................................... 1 1.1 The Polar Oceans ................................................................................................................................. 3 1.1.1 Geographical Definitions and Characteristics.......................................................................... 3 1.1.2 Role in Earth’s Climate System ................................................................................................ 5 1.1.3 Changing Climate and Consequences ...................................................................................... 6 1.2 Sea Spray Aerosol over the Polar Oceans ........................................................................................... 9 1.2.1 Production Mechanisms of Sea Spray Aerosol ........................................................................ 9 1.2.2 Chemo-Selective Sea-Air Transfer and Atmospheric Aging ................................................... 10 1.2.3 Impact on Earth’s Radiation Budget ...................................................................................... 12 1.3 The Surface of the Polar Oceans ....................................................................................................... 15 1.3.1 The Sea Surface Microlayer ................................................................................................... 15 1.3.2 Selective Enrichment of Chemical Compounds ..................................................................... 15 1.3.3 Atmospheric Relevance for Atmospheric Chemistry and Cloud Microphysics ..................... 24 1.4 Marine Carbohydrates....................................................................................................................... 26 1.4.1 Chemical Structures ............................................................................................................... 26 1.4.2 Microbial Role ........................................................................................................................ 28 1.4.3 Marine Carbohydrates in the Atmosphere ............................................................................ 30 1.4.4 Chemical Analysis and Sea Salt Interference ......................................................................... 31 2. Results and Discussions ........................................................................................................................... 35 2.1 First Publication ................................................................................................................................. 35 2.1.1 Glucose as a Potential Chemical Marker for Ice Nucleating Activity in Arctic Seawater and Melt Pond Samples ......................................................................................................................... 35 2.1.2 Supporting Information ......................................................................................................... 47 2.2 Second Publication ............................................................................................................................ 55 A protocol for quantifying mono-and polysaccharides in seawater and related saline matrices by electro-dialysis (ED) – combined with HPAEC-PAD ........................................................................ 55 2.3 Third Publication ............................................................................................................................... 70 2.3.1 Aerosol Marine Primary Carbohydrates and Atmospheric Transformation in the Western Antarctic Peninsula ......................................................................................................................... 70 2.3.2 Supporting Information ......................................................................................................... 88 3. Atmospheric Implications ........................................................................................................................ 95 4. Summary ................................................................................................................................................ 98 5. References ............................................................................................................................................. 101 List of Abbreviations .................................................................................................................................. 121 List of Figures ............................................................................................................................................. 123 List of Tables .............................................................................................................................................. 124 Curriculum Vitae ........................................................................................................................................ 125 / Primary marine aerosol particles impact Earth’s radiation budget by acting, among other things, as cloud condensation nuclei (CCN) or ice nucleating particles (INP) for the formation of clouds. Over the polar oceans, primary marine aerosol emissions dominate the atmospheric particles and can play a significant and changing role there in the context of climate change. These particles are primarily emitted from the oceanic surface water and a thin surface film, the so-called sea surface microlayer (SML), by the bursting of air bubbles entrained by the wind. They consist of inorganic sea salt and organic matter (OM), whose relative proportions differ greatly depending on the aerosol diameter. In this context, the marine carbohydrates represent an important group of OM, whose oceanic sources, their transition from the sea to the atmosphere, atmospheric aging and contribution to the condensation of water droplets and ice nucleation are not well understood. This limited level of knowledge is due, among other things, to the lack of analytical methods that enable a reliable determination of carbohydrates at very low mass concentrations with high recovery rates in the salty matrices. Within the framework of this PhD thesis, an analytical method was developed by combining high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and a prior desalination by electro-dialysis (ED), which enables the determination of a wide range of dissolved carbohydrates in their free (as monosaccharides) and combined (as oligo- or polysaccharides) forms in seawater and other saline matrices. With this new method, a biogeochemical connection between the presence of free glucose and the ice nucleating activity in the Arctic SML could be observed. In addition, the primary transfer of carbohydrates from the ocean via the SML into the atmosphere and subsequent secondary atmospheric transformations were investigated in the sea ice-free part of the Southern Ocean. Consequently, the extensive investigations of marine carbohydrates in seawater and aerosol particles indicate an atmospheric importance of microbiological processes that has been underestimated until now.:1. Introduction ............................................................................................................................................... 1 1.1 The Polar Oceans ................................................................................................................................. 3 1.1.1 Geographical Definitions and Characteristics.......................................................................... 3 1.1.2 Role in Earth’s Climate System ................................................................................................ 5 1.1.3 Changing Climate and Consequences ...................................................................................... 6 1.2 Sea Spray Aerosol over the Polar Oceans ........................................................................................... 9 1.2.1 Production Mechanisms of Sea Spray Aerosol ........................................................................ 9 1.2.2 Chemo-Selective Sea-Air Transfer and Atmospheric Aging ................................................... 10 1.2.3 Impact on Earth’s Radiation Budget ...................................................................................... 12 1.3 The Surface of the Polar Oceans ....................................................................................................... 15 1.3.1 The Sea Surface Microlayer ................................................................................................... 15 1.3.2 Selective Enrichment of Chemical Compounds ..................................................................... 15 1.3.3 Atmospheric Relevance for Atmospheric Chemistry and Cloud Microphysics ..................... 24 1.4 Marine Carbohydrates....................................................................................................................... 26 1.4.1 Chemical Structures ............................................................................................................... 26 1.4.2 Microbial Role ........................................................................................................................ 28 1.4.3 Marine Carbohydrates in the Atmosphere ............................................................................ 30 1.4.4 Chemical Analysis and Sea Salt Interference ......................................................................... 31 2. Results and Discussions ........................................................................................................................... 35 2.1 First Publication ................................................................................................................................. 35 2.1.1 Glucose as a Potential Chemical Marker for Ice Nucleating Activity in Arctic Seawater and Melt Pond Samples ......................................................................................................................... 35 2.1.2 Supporting Information ......................................................................................................... 47 2.2 Second Publication ............................................................................................................................ 55 A protocol for quantifying mono-and polysaccharides in seawater and related saline matrices by electro-dialysis (ED) – combined with HPAEC-PAD ........................................................................ 55 2.3 Third Publication ............................................................................................................................... 70 2.3.1 Aerosol Marine Primary Carbohydrates and Atmospheric Transformation in the Western Antarctic Peninsula ......................................................................................................................... 70 2.3.2 Supporting Information ......................................................................................................... 88 3. Atmospheric Implications ........................................................................................................................ 95 4. Summary ................................................................................................................................................ 98 5. References ............................................................................................................................................. 101 List of Abbreviations .................................................................................................................................. 121 List of Figures ............................................................................................................................................. 123 List of Tables .............................................................................................................................................. 124 Curriculum Vitae ........................................................................................................................................ 125

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