The diploma thesis deals with multivariate statistical methods and their environmental applications. The theoretical part is devoted to selected methods of linear regression analysis, method of principal components and the model of classical and robust factor analysis is also described. In the practical part of thesis, the main emission sources of PM1 aerosols in summer and winter period in Brno and Šlapanice are determined by using the classical factor analysis. The main aerosol emission sources in summer and winter in Šlapanice are also identified by using the robust factor analysis. Furthermore, the prediction of concentrations of PM1 aerosols in summer and winter period in Brno and Šlapanice is performed by using the linear regression model.

This master thesis was tasked to find out how the parameter of interior atmosphere changes at student's club "Mrtvá Ryba", that means atmospheric aerosols sized from 0,524 to 20 micrometers. This work tries to show indoor aerosols before and after the smoking ban and its comparison. This work describes concentrations PM1 and PM10, and their behavior per day. Concentrations was measured by APS (Aerodynamic particle sizer). The measurement was the first step in the non-smoking club, then processing with retrieved informations in CoPlot, CoStat and Excel, where the statistical method has done, and comparison with previous values. T-tests was used for statistics and linear regresion. The result confirms, what was it supposed to, so concentracion values are significantly different. The average concentration of all measured days (six) of smoking campaign was at PM1 13,28 µg.m-3 and at PM10 23,38 µg.m-3. The average concentration of all measured days (thirty six) of non-smoking campaign was at PM1 4,88 µg.m-3 and at PM10 24,61 µg.m-3. Resulting concentration of aerosol particles was explicity lower at non-smoking period than at smoking period. Contamination of interior enviroment is influenced by many factors. The most important factor is presence of persons and their number, concentration of outdoor...

Os nitro-hidrocarbonetos policíclicos aromáticos (NPAHs – nitro-polycyclic aromatic hydrocarbons) são compostos orgânicos constituídos de dois ou mais anéis benzênicos ligados ao grupo nitro (NO2). Tais compostos são amplamente distribuídos no meio ambiente e associados a partículas atmosféricas. O objetivo do presente estudo foi identificar os grupos funcionais dos NPAHs associados ao PM1.0 por espectroscopia de infravermelho termal com transformada de Fourier (FTIR – Fourier Transform Infrared Spectroscopy), determinar a concentração de tais compostos e avaliar a sazonalidade em uma área de influência veicular na região Metropolitana de Porto Alegre (MAPA – Metropolitan Area of Porto Alegre). Além disso, estudaram-se variáveis meteorológicas e outros poluentes (NO, NO2, NOx, O3) com a finalidade de relacioná-los com os NPAHs. Partículas atmosféricas (PM1.0) foram coletadas usando filtros de PTFE (polytetrafluorethylene) no amostrador automático PM162M. Após, o espectrorradiômetro FTIR portátil, da Designs & Prototypes, modelo 102, foi utilizado para realizar medidas espectrais de transmitância e emissividade dos padrões sólidos dos NPAHs: 1-NP e 2-NF e das amostras de partículas atmosféricas. As análises por cromatografia gasosa com detecção por captura de elétrons (GC-ECD - gas chromatography with electron capture detector) foram precedidas por isolamento/derivação, sendo essas as técnicas de determinação e extração, respectivamente, de NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP e 6-NChr) associados a PM1.0. Para validar o método analítico foi usado o Material de Referência Padrão – SRM 1649b – do National Institute of Standards and Technology (NIST, USA). As análises espectrais resultantes de transmitância e emissividade apresentaram bons resultados, possibilitando identificar as ligações C-N e grupo NO2, assim como alguns grupos funcionais orgânicos característicos dos padrões 1-NP e 2-NF, indicando que este método pode ser aplicado no material particulado atmosférico. Com o método empregado foi possível identificar o 1-NP em todas as amostras, enquanto que 2-NF foi identificado apenas em Canoas 1 e Sapucaia do Sul 1 e 2. As concentrações de NPAHs foram mais elevadas no inverno e Sapucaia do Sul foi o local que apresentou maiores níveis destes compostos, exceto o 6-NChr. Os NPAHs associados a PM1.0 mostraram correlações com os poluentes óxidos de nitrogênio (NO e NOx), assim como NPAHs com as variáveis meteorológicas: temperatura e velocidade do vento. Os resultados indicaram a contribuição dos veículos com motores a diesel. Isto foi confirmado pelo estudo das razões NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr. / The nitro-polycyclic aromatic hydrocarbons (NPAHs) are organic compounds that consisting of two or more benzene rings linked by a nitro group (NO2). These compounds are widely distributed in the environment and are mainly found associated with atmospheric particles. The objective of this study was to identify the functional groups of NPAHs associated with PM1.0 by Fourier Transform Infrared Spectroscopy (FTIR), determine the concentration of these compounds and evaluate the seasonality in an area of vehicular influence in the Metropolitan area of Porto Alegre (MAPA). Summed to that, meteorological variables and other pollutants (NO, NO2, NOx, O3) were studied in order to relate them with the NPAHs. Atmospheric particles (PM1.0) were collected using PTFE (polytetrafluorethylene) filters in autosampler PM162M. After that, the portable spectroradiometer FTIR, model 102 of Designs & Prototypes, was used for spectral measurements of transmittance and emissivity of solid standards of NPAHs: 1-NP and 2-NF and the atmospheric particles samples. Analyses by gas chromatography with electron capture detector (GC-ECD) were preceded by isolation / derivation, those being the determination and extraction techniques, respectively, of NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP and 6-NChr) associated with PM1.0. To validate the analytical method it was used the Standard Reference Material - SRM 1649b - of National Institute of Standards and Technology (NIST, USA). The spectral analysis resulting of transmittance and emissivity showed good results, allowing to identify the CN bands and NO2 group, as well as some characteristic organic functional groups of 1-NP and 2-NF standards, indicating that this method can be applied in atmospheric particulate matter. With the employed method it was possible to identify the 1-NP in all samples, while the 2-NF was identified only in Canoas 1 and Sapucaia do Sul 1 and 2. The NPAHs concentrations were higher in winter and Sapucaia do Sul was the place that had the highest levels of these compounds, except to 6-NChr. The NPAHs associated with the PM1.0 showed correlations with the nitrogen oxides (NO and NOx) pollutants, as the NPAHs with the meteorological variables: temperature and wind speed. The results indicated the contribution of vehicles with diesel engines. It was confirmed by the reasons study of NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr.

Os nitro-hidrocarbonetos policíclicos aromáticos (NPAHs – nitro-polycyclic aromatic hydrocarbons) são compostos orgânicos constituídos de dois ou mais anéis benzênicos ligados ao grupo nitro (NO2). Tais compostos são amplamente distribuídos no meio ambiente e associados a partículas atmosféricas. O objetivo do presente estudo foi identificar os grupos funcionais dos NPAHs associados ao PM1.0 por espectroscopia de infravermelho termal com transformada de Fourier (FTIR – Fourier Transform Infrared Spectroscopy), determinar a concentração de tais compostos e avaliar a sazonalidade em uma área de influência veicular na região Metropolitana de Porto Alegre (MAPA – Metropolitan Area of Porto Alegre). Além disso, estudaram-se variáveis meteorológicas e outros poluentes (NO, NO2, NOx, O3) com a finalidade de relacioná-los com os NPAHs. Partículas atmosféricas (PM1.0) foram coletadas usando filtros de PTFE (polytetrafluorethylene) no amostrador automático PM162M. Após, o espectrorradiômetro FTIR portátil, da Designs & Prototypes, modelo 102, foi utilizado para realizar medidas espectrais de transmitância e emissividade dos padrões sólidos dos NPAHs: 1-NP e 2-NF e das amostras de partículas atmosféricas. As análises por cromatografia gasosa com detecção por captura de elétrons (GC-ECD - gas chromatography with electron capture detector) foram precedidas por isolamento/derivação, sendo essas as técnicas de determinação e extração, respectivamente, de NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP e 6-NChr) associados a PM1.0. Para validar o método analítico foi usado o Material de Referência Padrão – SRM 1649b – do National Institute of Standards and Technology (NIST, USA). As análises espectrais resultantes de transmitância e emissividade apresentaram bons resultados, possibilitando identificar as ligações C-N e grupo NO2, assim como alguns grupos funcionais orgânicos característicos dos padrões 1-NP e 2-NF, indicando que este método pode ser aplicado no material particulado atmosférico. Com o método empregado foi possível identificar o 1-NP em todas as amostras, enquanto que 2-NF foi identificado apenas em Canoas 1 e Sapucaia do Sul 1 e 2. As concentrações de NPAHs foram mais elevadas no inverno e Sapucaia do Sul foi o local que apresentou maiores níveis destes compostos, exceto o 6-NChr. Os NPAHs associados a PM1.0 mostraram correlações com os poluentes óxidos de nitrogênio (NO e NOx), assim como NPAHs com as variáveis meteorológicas: temperatura e velocidade do vento. Os resultados indicaram a contribuição dos veículos com motores a diesel. Isto foi confirmado pelo estudo das razões NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr. / The nitro-polycyclic aromatic hydrocarbons (NPAHs) are organic compounds that consisting of two or more benzene rings linked by a nitro group (NO2). These compounds are widely distributed in the environment and are mainly found associated with atmospheric particles. The objective of this study was to identify the functional groups of NPAHs associated with PM1.0 by Fourier Transform Infrared Spectroscopy (FTIR), determine the concentration of these compounds and evaluate the seasonality in an area of vehicular influence in the Metropolitan area of Porto Alegre (MAPA). Summed to that, meteorological variables and other pollutants (NO, NO2, NOx, O3) were studied in order to relate them with the NPAHs. Atmospheric particles (PM1.0) were collected using PTFE (polytetrafluorethylene) filters in autosampler PM162M. After that, the portable spectroradiometer FTIR, model 102 of Designs & Prototypes, was used for spectral measurements of transmittance and emissivity of solid standards of NPAHs: 1-NP and 2-NF and the atmospheric particles samples. Analyses by gas chromatography with electron capture detector (GC-ECD) were preceded by isolation / derivation, those being the determination and extraction techniques, respectively, of NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP and 6-NChr) associated with PM1.0. To validate the analytical method it was used the Standard Reference Material - SRM 1649b - of National Institute of Standards and Technology (NIST, USA). The spectral analysis resulting of transmittance and emissivity showed good results, allowing to identify the CN bands and NO2 group, as well as some characteristic organic functional groups of 1-NP and 2-NF standards, indicating that this method can be applied in atmospheric particulate matter. With the employed method it was possible to identify the 1-NP in all samples, while the 2-NF was identified only in Canoas 1 and Sapucaia do Sul 1 and 2. The NPAHs concentrations were higher in winter and Sapucaia do Sul was the place that had the highest levels of these compounds, except to 6-NChr. The NPAHs associated with the PM1.0 showed correlations with the nitrogen oxides (NO and NOx) pollutants, as the NPAHs with the meteorological variables: temperature and wind speed. The results indicated the contribution of vehicles with diesel engines. It was confirmed by the reasons study of NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr.

Os nitro-hidrocarbonetos policíclicos aromáticos (NPAHs – nitro-polycyclic aromatic hydrocarbons) são compostos orgânicos constituídos de dois ou mais anéis benzênicos ligados ao grupo nitro (NO2). Tais compostos são amplamente distribuídos no meio ambiente e associados a partículas atmosféricas. O objetivo do presente estudo foi identificar os grupos funcionais dos NPAHs associados ao PM1.0 por espectroscopia de infravermelho termal com transformada de Fourier (FTIR – Fourier Transform Infrared Spectroscopy), determinar a concentração de tais compostos e avaliar a sazonalidade em uma área de influência veicular na região Metropolitana de Porto Alegre (MAPA – Metropolitan Area of Porto Alegre). Além disso, estudaram-se variáveis meteorológicas e outros poluentes (NO, NO2, NOx, O3) com a finalidade de relacioná-los com os NPAHs. Partículas atmosféricas (PM1.0) foram coletadas usando filtros de PTFE (polytetrafluorethylene) no amostrador automático PM162M. Após, o espectrorradiômetro FTIR portátil, da Designs & Prototypes, modelo 102, foi utilizado para realizar medidas espectrais de transmitância e emissividade dos padrões sólidos dos NPAHs: 1-NP e 2-NF e das amostras de partículas atmosféricas. As análises por cromatografia gasosa com detecção por captura de elétrons (GC-ECD - gas chromatography with electron capture detector) foram precedidas por isolamento/derivação, sendo essas as técnicas de determinação e extração, respectivamente, de NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP e 6-NChr) associados a PM1.0. Para validar o método analítico foi usado o Material de Referência Padrão – SRM 1649b – do National Institute of Standards and Technology (NIST, USA). As análises espectrais resultantes de transmitância e emissividade apresentaram bons resultados, possibilitando identificar as ligações C-N e grupo NO2, assim como alguns grupos funcionais orgânicos característicos dos padrões 1-NP e 2-NF, indicando que este método pode ser aplicado no material particulado atmosférico. Com o método empregado foi possível identificar o 1-NP em todas as amostras, enquanto que 2-NF foi identificado apenas em Canoas 1 e Sapucaia do Sul 1 e 2. As concentrações de NPAHs foram mais elevadas no inverno e Sapucaia do Sul foi o local que apresentou maiores níveis destes compostos, exceto o 6-NChr. Os NPAHs associados a PM1.0 mostraram correlações com os poluentes óxidos de nitrogênio (NO e NOx), assim como NPAHs com as variáveis meteorológicas: temperatura e velocidade do vento. Os resultados indicaram a contribuição dos veículos com motores a diesel. Isto foi confirmado pelo estudo das razões NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr. / The nitro-polycyclic aromatic hydrocarbons (NPAHs) are organic compounds that consisting of two or more benzene rings linked by a nitro group (NO2). These compounds are widely distributed in the environment and are mainly found associated with atmospheric particles. The objective of this study was to identify the functional groups of NPAHs associated with PM1.0 by Fourier Transform Infrared Spectroscopy (FTIR), determine the concentration of these compounds and evaluate the seasonality in an area of vehicular influence in the Metropolitan area of Porto Alegre (MAPA). Summed to that, meteorological variables and other pollutants (NO, NO2, NOx, O3) were studied in order to relate them with the NPAHs. Atmospheric particles (PM1.0) were collected using PTFE (polytetrafluorethylene) filters in autosampler PM162M. After that, the portable spectroradiometer FTIR, model 102 of Designs & Prototypes, was used for spectral measurements of transmittance and emissivity of solid standards of NPAHs: 1-NP and 2-NF and the atmospheric particles samples. Analyses by gas chromatography with electron capture detector (GC-ECD) were preceded by isolation / derivation, those being the determination and extraction techniques, respectively, of NHPAs (1-NNa, 2-NF, 3-NFl, 1-NP and 6-NChr) associated with PM1.0. To validate the analytical method it was used the Standard Reference Material - SRM 1649b - of National Institute of Standards and Technology (NIST, USA). The spectral analysis resulting of transmittance and emissivity showed good results, allowing to identify the CN bands and NO2 group, as well as some characteristic organic functional groups of 1-NP and 2-NF standards, indicating that this method can be applied in atmospheric particulate matter. With the employed method it was possible to identify the 1-NP in all samples, while the 2-NF was identified only in Canoas 1 and Sapucaia do Sul 1 and 2. The NPAHs concentrations were higher in winter and Sapucaia do Sul was the place that had the highest levels of these compounds, except to 6-NChr. The NPAHs associated with the PM1.0 showed correlations with the nitrogen oxides (NO and NOx) pollutants, as the NPAHs with the meteorological variables: temperature and wind speed. The results indicated the contribution of vehicles with diesel engines. It was confirmed by the reasons study of NPAHs/PAHs, 1-NP/Py, 6-NChr/Chr.

In this work the organic markers that serve for identification of sources of aerosols are monitored. Theoretic part deals with detailed survey of organic markers emitted from the most significant sources of atmospheric aerosols (biomass combustion, combustion of fossil fuels and traffic) as well as with sampling of aerosols and analysis of organic markers by analytical techniques. Monosaccharide anhydrides (emissions from biomass combustion) and polyaromatic hydrocarbons (emissions from traffic and incomplete combustion) were observed especially. Hopanes and steranes (traffic, coal combustion) and fatty acids (cooking) were next groups of monitored organic markers. Markers were studied mainly in size fraction PM1 because this fraction of aerosols is the most harmful to human health. Aerosols were sampled in two seasons (winter and summer) in two towns in 2009. Higher concentrations of aerosols and organic compounds were found in winter season, which resulted from increased combustion of biomass, coal and other organic material while traffic was the most significant source of aerosols in summer.

The content of analytical part of this thesis is the study of airborne dust samples collected in places with its higher concentration: by the Prague Ring (D0 motorway) and near the Ostrava's iron-mills. In both places, automobile transportation or industrial production are the primary sources of particulate matter emissions in the air. Received samples of PM1, PM2, PM10 a TSP filters were obtained by a standard air pollution monitoring procedure. This study examines the relationship between the magnetic parameters of the samples, their level of concentration of metals frequently present in emissions from these sources, the total mass of the dust fraction in the samples and the meteorological parameters (for Ostrava samples). The magnetic properties of the filters were investigated by magnetometric analyzes using a vibration sampling magnetometer. The concentrations of the metals were monitored by X-ray fluorescence spectrometer, the weight of parts of dust filtres was measured on laboratory scales.

Motor vehicles are a major source of gaseous and particulate matter pollution in urban areas, particularly of ultrafine sized particles (diameters < 0.1 µm). Exposure to particulate matter has been found to be associated with serious health effects, including respiratory and cardiovascular disease, and mortality. Particle emissions generated by motor vehicles span a very broad size range (from around 0.003-10 µm) and are measured as different subsets of particle mass concentrations or particle number count. However, there exist scientific challenges in analysing and interpreting the large data sets on motor vehicle emission factors, and no understanding is available of the application of different particle metrics as a basis for air quality regulation. To date a comprehensive inventory covering the broad size range of particles emitted by motor vehicles, and which includes particle number, does not exist anywhere in the world. This thesis covers research related to four important and interrelated aspects pertaining to particulate matter generated by motor vehicle fleets. These include the derivation of suitable particle emission factors for use in transport modelling and health impact assessments; quantification of motor vehicle particle emission inventories; investigation of the particle characteristic modality within particle size distributions as a potential for developing air quality regulation; and review and synthesis of current knowledge on ultrafine particles as it relates to motor vehicles; and the application of these aspects to the quantification, control and management of motor vehicle particle emissions. In order to quantify emissions in terms of a comprehensive inventory, which covers the full size range of particles emitted by motor vehicle fleets, it was necessary to derive a suitable set of particle emission factors for different vehicle and road type combinations for particle number, particle volume, PM1, PM2.5 and PM1 (mass concentration of particles with aerodynamic diameters < 1 µm, < 2.5 µm and < 10 µm respectively). The very large data set of emission factors analysed in this study were sourced from measurement studies conducted in developed countries, and hence the derived set of emission factors are suitable for preparing inventories in other urban regions of the developed world. These emission factors are particularly useful for regions with a lack of measurement data to derive emission factors, or where experimental data are available but are of insufficient scope. The comprehensive particle emissions inventory presented in this thesis is the first published inventory of tailpipe particle emissions prepared for a motor vehicle fleet, and included the quantification of particle emissions covering the full size range of particles emitted by vehicles, based on measurement data. The inventory quantified particle emissions measured in terms of particle number and different particle mass size fractions. It was developed for the urban South-East Queensland fleet in Australia, and included testing the particle emission implications of future scenarios for different passenger and freight travel demand. The thesis also presents evidence of the usefulness of examining modality within particle size distributions as a basis for developing air quality regulations; and finds evidence to support the relevance of introducing a new PM1 mass ambient air quality standard for the majority of environments worldwide. The study found that a combination of PM1 and PM10 standards are likely to be a more discerning and suitable set of ambient air quality standards for controlling particles emitted from combustion and mechanically-generated sources, such as motor vehicles, than the current mass standards of PM2.5 and PM10. The study also reviewed and synthesized existing knowledge on ultrafine particles, with a specific focus on those originating from motor vehicles. It found that motor vehicles are significant contributors to both air pollution and ultrafine particles in urban areas, and that a standardized measurement procedure is not currently available for ultrafine particles. The review found discrepancies exist between outcomes of instrumentation used to measure ultrafine particles; that few data is available on ultrafine particle chemistry and composition, long term monitoring; characterization of their spatial and temporal distribution in urban areas; and that no inventories for particle number are available for motor vehicle fleets. This knowledge is critical for epidemiological studies and exposure-response assessment. Conclusions from this review included the recommendation that ultrafine particles in populated urban areas be considered a likely target for future air quality regulation based on particle number, due to their potential impacts on the environment. The research in this PhD thesis successfully integrated the elements needed to quantify and manage motor vehicle fleet emissions, and its novelty relates to the combining of expertise from two distinctly separate disciplines - from aerosol science and transport modelling. The new knowledge and concepts developed in this PhD research provide never before available data and methods which can be used to develop comprehensive, size-resolved inventories of motor vehicle particle emissions, and air quality regulations to control particle emissions to protect the health and well-being of current and future generations.

Atmospheric fine particulate matter (PM2.5), which is mostly formed in the atmosphere from precursor gases, contributes to numerous environmental and health concerns. Quantifying the ambient concentrations of PM2.5 and precursor gases can be challenging. Hence, many scientific questions about the formation, chemical composition, and gas/particle partitioning of PM2.5 remain unanswered. Ambient Ion Monitor - Ion Chromatography (AIM-IC) was characterized and utilized to measure the water-soluble composition of PM2.5 (dominated by pNH4+, pSO42-, and pNO3-) and associated precursor gases (dominated by NH3(g), SO2(g), and HNO3(g)) during two field campaigns. The AIM-IC detection limits for hourly sampling were determined to be 3 - 45 ng m-3. The response time for “sticky” gases was significantly improved with a nylon denuder membrane. A novel inlet configuration for the AIM-IC, which minimizes sampling inlet losses and carryover in sample analyses, was implemented. Measurements from the BAQS-Met 2007 campaign were utilized to assess the accuracy of the AURAMS model and investigate gas/particle partitioning in SW Ontario. Due to high sulphate levels, NH3(g) was the limiting chemical factor in the formation and gas/particle partitioning of PM2.5. The errors in the predictions of relative humidity and free ammonia were responsible for the poor agreement iii between modelled and measured pNO3- values. The AIM-IC measurements from the CalNex 2010 study were compared to the CMAQ model and utilized to investigate the gas/particle partitioning in Bakersfield, CA. Very high NH3(g) concentrations were observed, and the formation and partitioning of PM2.5 was limited by HNO3(g) and H2SO4. Evidence of rapid removal of HNO3(g) by interactions with super-micron dust particles, and possibly with the alkaline surface was found. CMAQ exhibited significant biases in the predicted concentrations of pSO42-, NH3(g) and HNO3(g).

Atmospheric fine particulate matter (PM2.5), which is mostly formed in the atmosphere from precursor gases, contributes to numerous environmental and health concerns. Quantifying the ambient concentrations of PM2.5 and precursor gases can be challenging. Hence, many scientific questions about the formation, chemical composition, and gas/particle partitioning of PM2.5 remain unanswered. Ambient Ion Monitor - Ion Chromatography (AIM-IC) was characterized and utilized to measure the water-soluble composition of PM2.5 (dominated by pNH4+, pSO42-, and pNO3-) and associated precursor gases (dominated by NH3(g), SO2(g), and HNO3(g)) during two field campaigns. The AIM-IC detection limits for hourly sampling were determined to be 3 - 45 ng m-3. The response time for “sticky” gases was significantly improved with a nylon denuder membrane. A novel inlet configuration for the AIM-IC, which minimizes sampling inlet losses and carryover in sample analyses, was implemented. Measurements from the BAQS-Met 2007 campaign were utilized to assess the accuracy of the AURAMS model and investigate gas/particle partitioning in SW Ontario. Due to high sulphate levels, NH3(g) was the limiting chemical factor in the formation and gas/particle partitioning of PM2.5. The errors in the predictions of relative humidity and free ammonia were responsible for the poor agreement iii between modelled and measured pNO3- values. The AIM-IC measurements from the CalNex 2010 study were compared to the CMAQ model and utilized to investigate the gas/particle partitioning in Bakersfield, CA. Very high NH3(g) concentrations were observed, and the formation and partitioning of PM2.5 was limited by HNO3(g) and H2SO4. Evidence of rapid removal of HNO3(g) by interactions with super-micron dust particles, and possibly with the alkaline surface was found. CMAQ exhibited significant biases in the predicted concentrations of pSO42-, NH3(g) and HNO3(g).