This dissertation consists of three separate research projects. Each paper uses a different applied econometric technique to investigate problems related to air quality economics. The first chapter is a general introduction to all three studies. The second chapter explores adopting an environmentally-friendly public transportation system in Europe. The Bayesian econometric methods show that willingness to pay for a new public transportation system is primarily driven by improvements to public goods, such as air quality and greenhouse gas emission reduction. The third chapter uses the red tide-related stated experience and satellite imagery of chlorophyll-a concentration as well as field data of respiratory irritation. This chapter illustrates that ancillary scientific information can be efficiently combined with choice experimental data. The fourth chapter uses panel fixed-effect models to investigate the short-term effect of air pollution on students' cognitive performance in China. It is shown that PM2.5 has a significantly negative impact on students' exam performance. / Doctor of Philosophy / This dissertation consists of three separate research projects. The first chapter is a general introduction to all three chapters. The second chapter assesses residents' support for environmentally-friendly public transportation (EFPT) upgrades across Europe. We develop a novel Bayesian logit model to investigate residents' willingness to pay for local EFPT upgrades. We find evidence that WTP is primarily driven by expected improvements to public goods, such as air quality and greenhouse gas abatement, as opposed to private ridership benefits. WTP distributions are strongly positive in all nations suggesting implicit public support for EFPT in Europe. The third chapter presents a unique opportunity to validate stated experiences by Florida Gulf coast residents with red tide-related air toxins with satellite imagery of chlorophyll-a concentration, as well as field data on respiratory irritation at local beaches. We find that respondents are more likely to choose our proposed new harmful algal blooms forecast system when the chlorophyll-a concentration or respiratory irritation is higher at nearby coastal locations. Moreover, we illustrate that this ancillary scientific information can be efficiently combined with choice experimental data and consider this research a first step in a broader effort to directly link scientific data on environmental conditions with nonmarket economic outcomes. The fourth chapter investigates short-term exposure of air pollution on students' cognitive performance in a high-stakes exam: China's College English Test (CET). We use student fixed effects in the panel-data model to estimate the effect of air pollution on students' test scores. Our findings indicate a statistically significant negative effect of PM2.5 on exam performance and also show PM2.5 is equally harmful to listening and reading section, and maybe even more for writing section. We also find that short-term exposure causes negative cognitive effects, suggesting that temporary preventative measures could be effective in avoiding the negative effects of PM2.5.

Trace element concentrations vary substantially during snowmelt runoff, with changes in the dissolved versus particulate fractions potentially impacting their movement at the catchment scale. To investigate trace element behavior in a snowmelt dominated stream, we measured concentrations in different size fractions in the Provo River (northern Utah, USA). We sampled the river at three locations during water years 2016-2018 and 2021-2023 for trace metal and major ion concentrations. During the final year, we collected three fractions (unfiltered, <0.45 µm filtered, and <0.22 µm filtered) for trace metal chemistry and calculated the particulate concentration as the difference between the unfiltered and 0.45 µm fraction. Stream measurements included pH, discharge, turbidity, and fluorescent dissolved organic matter (fDOM). We also sampled water sources (soil water, ephemeral streams, and snowpack) to compare trace metal concentrations across the watershed with the stream. Trace metal (Al, Be, Fe, Pb) and rare earth element (REE +Y) concentrations had the highest particulate and dissolved concentrations during snowmelt runoff. In contrast, major cations were primarily found in the dissolved fraction with lowest concentrations during snowmelt runoff. Major cation and particulate metal concentrations increased from upstream to downstream. The increased trace metal and REE + Y concentrations during snowmelt relative to baseflow may be explained by increased discharge and associated increased turbidity and fDOM. A comparison with water sources suggests that dissolved and particulate trace metals in the stream are sourced from flushed soil water, as trace metal transport through the watershed is facilitated by suspended sediment and dissolved organic matter. For most of the trace metals and REE +Y, concentrations were similar in the <0.45 µm and <0.22 µm fractions. Yet Al tended to have higher concentrations in the <0.45 µm fraction, suggesting a colloidal form of Al between 0.22 µm and 0.45 µm may exist. Differences from upstream to downstream may be related to changes in pH, from ~7 at the upper site to ~8 at the lower sites, which would change sorption capacity, saturation indices, or speciation. Our study demonstrates that trace metal concentrations are variable during snowmelt as the metals interact with suspended particles or dissolved organic matter and are influenced by changing water chemistry, with implications for understanding water quality impairments in snowmelt-dominated streams.

Growing concern over adverse health effects from low level lead exposure motivated reassessment of lead occurrence in drinking water, from the perspective of 1) possibly eliminating lead from new brass materials, and 2) performance testing of existing products. During the course of this thesis work, it was discovered that several cases of childhood lead poisoning in North Carolina, South Carolina and Washington D.C. occurred from contaminated potable water. That disconcerting finding prompted additional work into 3) deficiencies in existing lead testing of drinking water samples, and 4) impacts of water treatment steps on lead leaching. Meters, components, and fittings manufactured from non-leaded brass (< 0.25 percent lead content) are increasingly specified for use in water distribution systems and premise plumbing, in response to California's Proposition 65 and the proposed Lead Free Drinking Water Act. An in-depth review of the available literature revealed that non-leaded brass releases minimal amounts of lead and other contaminants of concern to drinking water. There is legitimate concern about the corrosion resistance and longevity of these non-leaded alloys in the range of waters that will be encountered in practice. Nonetheless, when the potential impacts to manufacturers, utilities and consumers are considered, non-leaded brasses appear to be attractive albeit at slightly higher cost. For existing leaded brass products, concerns have been raised over potential limitations of performance standards used to certify the products as "safe" in the marketplace. The ANSI/NSF 61 Section 9 test is the industry standard, and its protocol is critically evaluated from the perspective of the leaching solution chemistry. Testing indicated that the protocol water is reasonably representative of a typical water supply. However, some lower pH and lower alkalinity waters can be much more aggressive than the existing section 9 water, and for potable water with these characteristics, problems with higher than desired lead leaching may occur. It may be desirable to tighten the standard's pass/fail lead criterion in order to account for this problem in practice. Several cases of childhood lead poisoning from water have been recently encountered, which prompted environmental assessments. It was visually obvious that some of the lead particles ingested by these children, present in water from the tap, were not completely dissolving in the standard method with weak acid recommended by the US EPA. A laboratory investigation proved that up to 80% particulate lead in water samples could be "missed" by the standard protocol. Unfortunately, tests with simulated gastric fluid revealed that much of this particulate lead would be bioavailable in the presence of chloride, warmer temperatures and lower pH inside the human stomach. It is recommended that water utilities be alert to this possible problem and that environmental assessments of lead poisoned children use stronger digestions to detect lead in water. Several of the lead poisoning instances occurred after the utility changed both disinfectant chemicals (from chlorine to chloramine) and coagulant types. Although authorities initially thought chloramine was the cause based on experiences in Washington D.C., bench scale studies in this work proved that a change in coagulant from aluminum sulfate to either ferric chloride or polyaluminum chloride was in fact the main reason of the lead spikes. The reduction in sulfate and increase in chloride increased the chloride to sulfate mass ratio of the water supply. A higher chloride to sulfate mass ratio triggered much higher (2.3-40 times more) lead leaching from solder connected to copper pipe. The adverse effects of the increase in the ratio could not be eliminated by adding a corrosion inhibitor. / Master of Science

A pneumatic particulate collection system harnesses the energy associated with the release of a compressed gas to transport particulate to a collection chamber. In an effort to improve the efficiency of a previously designed collection system, high speed imaging in conjunction with computational fluid dynamics (CFD) was utilized to highlight design deficiencies. Areas of recirculation within the collection device as well as impingement of the sampling surface were observed through the testing and CFD analysis. The basis of the improved collection system was conceived through research of pneumatic transport and the deficiencies found through testing and simulation. An improved rectangular-duct-styled system was designed in three main stages. A variety of filters used to contain the desired particulate were characterized through testing for use in simulations as well as fluids calculations. The improved system was then analyzed utilizing compressible and incompressible flow calculations and design iterations were conducted with CFD to determine the final parameters. The final design was simulated with a multiphase flow model to examine the particulate entrainment performance. The improved collection system efficiently expanded and developed the gas flow prior to the collection area to employ the particulate entrainment process. The final design was constructed with an additive manufacturing process and experimentally tested to validate the simulations and flow calculations. The testing proved that the final design operated purely on particulate entrainment and collected only the top layer of particles as simulated. The improved collection system eliminated all areas of flow recirculation and impingement of the particle bed to provide a more efficient sampling device. / Master of Science

Yes / An experimental study is presented here to understand the stress transmission characteristics under different geometrical arrangements of particulates inside a narrow chamber subjected to axial compression loading. The multi-grain systems considered here are face-centred, simple cubic and poly-dispersed structures, as well as inclusions embedded inside seeded, unseeded and cohesive powder bed of Durcal (calcium carbonate). The distribution of the maximum shear stress, direction of the major principal stress and shear stress concentration factor were obtained using photo stress analysis tomography (PSAT). The results show that the maximum shear stress distribution in the simple cubic structure is chain-like and self-repetitive, i.e., a single grain behaviour is representative of the whole system. This is not the case in the case of other granular packing. In the case of the inclusion surrounded by powder media, the maximum shear stress distribution in the inclusion occurs through ring-like structures, which are different from those observed in the structured granular packing. This tendency increases for an increase in the cohesivity of the surrounding particulates. In the granular systems, the direction of the major principal stress is mostly orthogonal to the direction of loading except in some particles in the random granular packing. In the case of inclusion surrounded by Durcal particulates, the directional of the major principal stress acts along the direction of the axial loading except in the ring region where this tends to be oblique to the direction of axial loading. Estimates of the shear stress concentration factor (k) show that, k tends to be independent of the structural arrangement of granular packing at higher load levels. In the case of inclusion surrounded by powder bed, k for the seeded granulated particulate bed is mostly independent of the external load levels. In the case of unseeded particulate (granulated) bed, a fluctuation in k is observed with the loading level. This suggests that the seeded granules could distribute stresses in a stable manner without much change in the nature of shear stress-transmitting fabric of the particulate contacts under external loading. An increase in the cohesion of particulate bed results in more plastic deformation as shown by the differential shear stress concentration factor. The results reported in this study show the usefulness of optical stress analysis to shed some scientific lights on unravelling some of the complexities of particulate systems under different structural arrangements of grains and surrounding conditions of the inclusions in particulate media.

In the past several decades there has been an increased interest in sand, dust, and ash particulates ingestion study for gas turbine engine applications. Recently, there has been an increase in commercial and military fleets operating in medium to highly dusty environments, such as areas in Africa, the Middle East, and Asia. Dusty environments can cause blockage in turbine cooling circuits which can lead to early engine maintenance or removals. Ingested debris can melt, forming glassy or molten deposits on various hot section components in gas turbine engines. This thesis evaluates the onset of deposit formation using an experimental rig to perform testing in high temperature environment. In general, deposits on turbine components can affect the operating capacity and the overall operating efficiency of gas turbine engines. Particulate ingestion events can be catastrophic and cost millions of dollars in maintenance and repairs. The experimental work in this thesis focused only on quantifying the initial deposit formation in high temperature environment to aid in the development of resilient engine design and operational diagnostics. Testing was performed using HASTELLOY® X coupons and Arizona Road Dust with main gas flow temperatures between 1050°C and 1100°C. Arizona Road Dust sample with sizing between 2µm and 40µm were used for experimental testing. The sensitivity of the initial deposit formation on cooled HASTELLOY® X coupon surface was investigated by using an inline air heater. Three cooling test conditions: no cooling, 500°C cooling, and 250°C cooling, were used to alter the surface temperature of the coupon during testing. Results from testing indicated cooling test conditions used have a small impact on deposit formation. / Master of Science / In the past several decades there has been an increased interest in sand, dust, and ash particulates ingestion study for gas turbine engine applications. Recently, there has been an increase in commercial and military fleets operating in medium to highly dusty environments, such as areas in Africa, the Middle East, and Asia. Dusty environments can cause blockage in turbine cooling circuits which can lead to early engine maintenance or removals. Ingested debris can melt, forming glassy or molten deposits on various hot section components in gas turbine engines. This thesis evaluates the onset of deposit formation using an experimental rig to perform testing in high temperature environment. In general, deposits on turbine components can affect the operating capacity and the overall operating efficiency of gas turbine engines. Particulate ingestion events can be catastrophic and cost millions of dollars in maintenance and repairs. The experimental work in this thesis focused only on quantifying the initial deposit formation in high temperature environment to aid in the development of resilient engine design and operational diagnostics. Testing was performed using HASTELLOY® X coupons and Arizona Road Dust with main gas flow temperatures between 1050°C and 1100°C. Arizona Road Dust sample with sizing between 2µm and 40µm were used for experimental testing. The sensitivity of the initial deposit formation on cooled HASTELLOY® X coupon surface was investigated by using an inline air heater. Three cooling test conditions: no cooling, 500°C cooling, and 250°C cooling, were used to alter the surface temperature of the coupon during testing. Results from testing indicated cooling test conditions used have a small impact on deposit formation.

Este estudo avalia os efeitos adversos na saúde causados pelas variações na composição do material particulado em curtos períodos de tempo. Para tanto, foram determinados Black Carbon (BC), massa e composição elementar do PM2.5 coletado em dois diferentes períodos, Dia e Noite, na cidade de São Paulo. Além das análises químicas, gravimetria, análise de reflectância e espectrometria por fluorescência de Raios-X, foram realizados testes toxicológicos de contagem de micronúcleos utilizando ressuspensão do PM2,5 em raízes de Allium cepa (cebola). O PM2.5 foi amostrado na saída do Concentrador de Partículas Finas Ambientais de Harvard (CPFAH) e as amostras foram coletadas diariamente por quinze dias, entre Maio e Junho (Experimento 1) e entre Outubro e Novembro (Experimento 2) de 2009, durante o Dia (8:00h - 11:00h e 14:00h - 17:00h) e a Noite (20:00h - 23:00h). A variabilidade na composição do PM2.5 foi analizada utilizando o método de componentes principais, por meio da qual foram identificados três fatores significantes: Fator 1, onde encontramos BC e os elementos Ca, Fe, K, Si, Zn e Ti que podem ser característicos da emissão do tráfego veicular em geral; Fator 2 onde encontramos Ni e Cr que podem ser interpretados como resultado das emissões industriais; e o Fator 3 é formado pelos elementos V e S que podem ser característicos das emissões das queimas de diesel e óleo combustível. A análise univariada da contagem dos três fatores mostrou uma diferença significativa somente para o Fator 3 (p=0,022) entre os dois períodos, fazendo-se mais presente no período noturno. A frequência do número de micronúcleos das células de raízes de cebola foi maior para período noturno. Os resultados indicam que existem diferenças na composição e toxicidade do PM2,5 coletado em diferentes períodos na cidade de São Paulo. Os dados sugerem que a toxicidade do PM2,5 pode ser influenciada pelas mudanças nos padrões de tráfego e processos fotoquímicos da atmosfera. / The objective of this study was to evaluate the adverse health effects of shortterm variations in particle composition. For this purpose, black carbon, particle mass and elemental composition of PM2.5 collected along the two different periods in São Paulo city were determined. In addition to the chemical measurements, toxicological evaluation was performed using the Allium cepa micronuclei assay test and particle suspensions of PM2.5 as test substrate. PM2.5 was sampled at the output of the Harvard Ambient Fine Particle Concentrator (HAFPC). The samples were collected daily from May 19th to June 4th (period 1) of 2009, during the morning (from 8 AM to 11 AM), afternoon (from 2 PM to 5 PM), and evening (from 8 PM to 11 PM), and from November 11th (period 2) of 2009, during the morning (from 8 AM to 11 AM), and evening (from 8 PM to 11 PM). Samples collected during the morning and afternoon were called Day and those collected during the evening, EVENING. Concentrations of PM2.5 mass (gravimetric method), black carbon (reflectance analysis) and trace elementals (X-ray fluorescence spectrometry) were determined. Variability in PM2.5 composition measured was analyzed using Principal Components Analysis in which 3 significant factors were identified. Results of black carbon (BC) and of elements Ca, Fe, K, Si, Zn and Ti were grouped in Factor 1, that can be characteristic of general traffic emission; In Factor 2, Ni and Cr were included and it can be interpreted as a result of industry emissions; and Factor 3 is formed by V and S what characterizes diesel/oil combustion emissions. Univariate Analysis of factor scores indicated a significant difference between the periods scores of factor 3 (p=0.022). The frequency of number of micronuclei obtained was also higher in samples collected at the EVENING than those of DAY. In conclusion, our results indicate that there are differences in the composition and toxicity of PM2.5 collected in different periods of the day. These findings suggest that particle toxicity may be influenced by changes in traffic patterns and photochemical processes.

Made available in DSpace on 2017-07-25T19:29:43Z (GMT). No. of bitstreams: 1 Ademir Oliveira Ferreira.pdf: 1294842 bytes, checksum: 8d7036f6aefa0cf3c549b0c63029e109 (MD5) Previous issue date: 2009-07-13 / Decrease in soil organic carbon (SOC) content of the surface layer into deeper layers indicates the occurrence of the stratification in the profile due to continuous C addition of crop residues enriching the soil surface layer. The objective of this study was: in Chapter 3 the relationship of stratification (RE) of C of the soil organic matter (SOM) pools can be an indicator of C sequestration in no-tillage soils? In the chapter 4 the tensile strength of aggregates is affected by the C content of Pedosequence of Latosol with medium and clay texture? in Chapter 5 which is the C balance and the amount of crop residue needed to maintain a stable C balance in a Latosol with a medium and clay texture? The experimental design was a completely randomized 2x2x2 factorial with 12 treatments. Treatments consisted of: a) an Oxisol (Red Latosol) with medium and clayey texture, b) two soil sampling periods (T1 and T2) with one year interval between them, and c) two soil sampling depths (0-5 and 5-20 cm). The soil attributes assessed were: the separation of water stable aggregates classes (19-8, 8-4, 4-2, 2-1, 1-0,5 and 05-0,25 mm), particulate organic carbon (POC), total particulate nitrogen (TPN) in the aggregate classes. Also was determined total organic carbon (TOC) and total nitrogen (NT) in the whole sample and in the aggregates sizes classes and tensile strength of aggregates. The relationship of stratification was calculated by dividing the TOC and TN values of 0-5 cm layer by the values of the same attributes of 5-20 cm layer. The C sequestration rate and the stratification ratio changes were calculated by the difference between the T2 values minus T1. The tensile strength was measured in soil aggregates and assessed in 1920 aggregates for each sampling time. Also TOC and NT content were measured in aggregates. The aggregates greater than 8 mm represented more than 70 of the total mass in both the clay and in sandy soil. The relationship of stratification ratio (0-5:5-20 cm) of SOC, TN, POC and TPN soil indicated the improvement of the surface layer. A significant linear relationship between the SR and C sequestration rate in both textural classes showed an increase in C sequestration and was more evident in LV with medium texture. The increase in TOC content resulted in decreased tensile strength (TS) of the aggregates and was more evident in the 0-5 cm layer. The TS showed inverse relationship with the soil density and was higher in the LV medium texture. The rate of sequestration of C was 0.86 for the LV with medium texture and 0.76 Mg ha-1 for the clay texture and to maintain the stable balance of C is required an input of 8.6 Mg ha-1 of crop residues. The results presented confirm the hypothesis of SR to be a sensitive indicator for the rate of carbon sequestration in no-tillage soil. Key-words: Carbon stock, Carbon balance, Carbon sequestration, Soil management systems, particulate organic carbon, particulate nitrogen. / A redução no conteúdo de carbono (C) da camada superficial em direção as camadas mais profundas do solo indica a formação da estratificação no perfil devido à adição contínua de C pelos resíduos orgânicos resultando no enriquecendo a camada superficial do solo. O objetivo deste trabalho foi avaliar os seguintes assuntos: a) a relação de estratificação (RE) de C dos compartimentos da matéria orgânica do solo (MOS) pode ser um indicador do seqüestro de C no sistema plantio direto. b) a resistência tênsil dos gregados pode ser afetada pelo conteúdo de C em Pedossequencia de Latossolo com textura média e argilosa. c) o balanço de C e a quantidade de resíduos culturais necessária para manter o equilíbrio estável de C em um Latossolo com textura média e argilosa. O delineamento experimental foi um fatorial 2x2x2 inteiramente casualizado com 12 tratamentos. Os tratamentos constituíram-se de: a) um Latossolo Vermelho com textura média e argilosa, duas épocas de amostragem do solo (E1 e E2) com um ano de intervalo entre si e duas profundidades de amostragem (0-5 e 5-20 cm). Os atributos avaliados foram: a separação das classes de agregados do tamisamento úmido (19-8, 8-4, 4-2, 2-1, 1-0,5 e 05-0,25 mm), o carbono orgânico particulado (COP), o nitrogênio total particulado (NTP) nas classes de agregado, o C orgânico total (COT) e o nitrogênio total (NT) na amostra integral e nas classes de agregados e a resistência tênsil dos agregados. A relação de estratificação (RE) foi calculada dividindo-se o valor de COT e NT da camada de 0-5 cm pelo valor na camada 5-20 cm. A taxa de seqüestro de C e a variação da relação de estratificação foram calculadas através da diferença (D) entre os valores da E2 menos o da E1. A resistência tênsil (RT) do solo foi avaliada em 1920 agregados de cada época de coleta, determinando-se, também o conteúdo de COT e NT. A classe de agregado > 8 mm representou mais de 70% da massa dos agregados tanto na textura argilosa como na arenosa. Da mesma forma, o conteúdo de COT e NT foram maiores na classe de agregado > do que 4 mm comparado as demais classes nas duas classes texturais. A relação de estratificação 5:5-20 cm) de COT, NT, COP e NTP do solo indicou a melhoria da qualidade do solo da camada superficial. A relação linear e significativa entre o DRE com a taxa de seqüestro de carbono nas duas classes texturais mostrou o aumento no seqüestro de C e foi mais evidente no LV com textura média. O incremento do conteúdo de COT resultou na diminuição da resistência tênsil (RT) dos agregados e foi mais evidente na camada de 0-5 cm. A RT apresentou relação inversa com a densidade do solo e foi superior no LV textura média. A taxa de seqüestro de C foi de 0,86 para o LV textura média e 0,76 Mg ha-1 para o textura argilosa e para manter o equilíbrio estável de C é necessário o aporte de 8,6 Mg ha-1 de resíduos culturais. Os resultados apresentados confirmaram a hipótese da RE ser um indicador sensível para a taxa de seqüestro de carbono no solo em um sistema sob plantio direto consolidado.

Este estudo avalia os efeitos adversos na saúde causados pelas variações na composição do material particulado em curtos períodos de tempo. Para tanto, foram determinados Black Carbon (BC), massa e composição elementar do PM2.5 coletado em dois diferentes períodos, Dia e Noite, na cidade de São Paulo. Além das análises químicas, gravimetria, análise de reflectância e espectrometria por fluorescência de Raios-X, foram realizados testes toxicológicos de contagem de micronúcleos utilizando ressuspensão do PM2,5 em raízes de Allium cepa (cebola). O PM2.5 foi amostrado na saída do Concentrador de Partículas Finas Ambientais de Harvard (CPFAH) e as amostras foram coletadas diariamente por quinze dias, entre Maio e Junho (Experimento 1) e entre Outubro e Novembro (Experimento 2) de 2009, durante o Dia (8:00h - 11:00h e 14:00h - 17:00h) e a Noite (20:00h - 23:00h). A variabilidade na composição do PM2.5 foi analizada utilizando o método de componentes principais, por meio da qual foram identificados três fatores significantes: Fator 1, onde encontramos BC e os elementos Ca, Fe, K, Si, Zn e Ti que podem ser característicos da emissão do tráfego veicular em geral; Fator 2 onde encontramos Ni e Cr que podem ser interpretados como resultado das emissões industriais; e o Fator 3 é formado pelos elementos V e S que podem ser característicos das emissões das queimas de diesel e óleo combustível. A análise univariada da contagem dos três fatores mostrou uma diferença significativa somente para o Fator 3 (p=0,022) entre os dois períodos, fazendo-se mais presente no período noturno. A frequência do número de micronúcleos das células de raízes de cebola foi maior para período noturno. Os resultados indicam que existem diferenças na composição e toxicidade do PM2,5 coletado em diferentes períodos na cidade de São Paulo. Os dados sugerem que a toxicidade do PM2,5 pode ser influenciada pelas mudanças nos padrões de tráfego e processos fotoquímicos da atmosfera. / The objective of this study was to evaluate the adverse health effects of shortterm variations in particle composition. For this purpose, black carbon, particle mass and elemental composition of PM2.5 collected along the two different periods in São Paulo city were determined. In addition to the chemical measurements, toxicological evaluation was performed using the Allium cepa micronuclei assay test and particle suspensions of PM2.5 as test substrate. PM2.5 was sampled at the output of the Harvard Ambient Fine Particle Concentrator (HAFPC). The samples were collected daily from May 19th to June 4th (period 1) of 2009, during the morning (from 8 AM to 11 AM), afternoon (from 2 PM to 5 PM), and evening (from 8 PM to 11 PM), and from November 11th (period 2) of 2009, during the morning (from 8 AM to 11 AM), and evening (from 8 PM to 11 PM). Samples collected during the morning and afternoon were called Day and those collected during the evening, EVENING. Concentrations of PM2.5 mass (gravimetric method), black carbon (reflectance analysis) and trace elementals (X-ray fluorescence spectrometry) were determined. Variability in PM2.5 composition measured was analyzed using Principal Components Analysis in which 3 significant factors were identified. Results of black carbon (BC) and of elements Ca, Fe, K, Si, Zn and Ti were grouped in Factor 1, that can be characteristic of general traffic emission; In Factor 2, Ni and Cr were included and it can be interpreted as a result of industry emissions; and Factor 3 is formed by V and S what characterizes diesel/oil combustion emissions. Univariate Analysis of factor scores indicated a significant difference between the periods scores of factor 3 (p=0.022). The frequency of number of micronuclei obtained was also higher in samples collected at the EVENING than those of DAY. In conclusion, our results indicate that there are differences in the composition and toxicity of PM2.5 collected in different periods of the day. These findings suggest that particle toxicity may be influenced by changes in traffic patterns and photochemical processes.

The problems of particulate matter air pollution were analyzed, statistical data about particulate matter pollution in the world and in Lithuania were presented, necessity of particulate matter concentration assessment in the air of Žirmūnai and Žvėrynas districts of Vilnius were described, the main aims and tasks of work were described in the final master work. The data of Lithuanian air quality stations were analyzed too, and it was assessed that Vilnius is one of the most particulate matter polluted Lithuanian cities. The biggest concentrations of this pollutant during analyzed period were fixed in the Žirmūnai and Žvėrynas air quality stations. The methodology of investigation of particulate matter concentration in the air of Žirmūnai and Žvėrynas districts was described; places of measurement points, operation of a real time monitor „Microdust pro“ were characterized and the results of recording were presented, too. The model of particulate matter carry in Žvėrynas district with the help of „Phoenics“ modelling programme was made. The data of investigation (results of recording particulate matter concentration) and calculated results were compared, conclusions and suggestions given. The work has 6 chapters: introduction, the ambient air pollution with particulate matter; investigation of particulate matter concentration in the air of Vilnius districts, mathematical modelling of particulate matter concentration in the air of Žvėrynas district, general conclusions and... [to full text]