Tropospheric oxidation modulates pollution chemistry and greenhouse gas lifetimes. The hydroxyl radical (OH) is the primary oxidant and the main sink for methane, the second-most influential anthropogenic contributor to climate change. OH is produced following the photolysis of ozone, an oxidant, respiratory irritant and greenhouse gas. Trends in methane or ozone are frequently attributed to their sources, but sink-driven variability is less often considered. I investigate the influence of fluctuations in turbulent loss to the Earth’s surface, also known as deposition, on tropospheric ozone concentrations and chemistry over the relatively polluted eastern United States. I use idealized sensitivity simulations with the global chemistry-climate model AM3 to demonstrate that coherent shifts in deposition, on the order recently observed at a long-term measurement site, affect surface ozone concentrations as much as decreases in its precursor emissions have over the past decade. I conclude that a sub-regional deposition measurement network is needed to confidently attribute trends in tropospheric ozone. Next, I turn to the remote marine troposphere to evaluate two theoretical proxies for variability in the methane sink, OH, with observations from the NASA Atmospheric Tomography (ATom) aircraft campaign. The low concentration and short lifetime of OH preclude the development of a representative measurement network to track its fluctuations in space and time. This dearth of constraints has led to discrepancies in the methane lifetime across models that project atmospheric composition and climate. Observational and modeling studies suggest that few processes control OH fluctuations in relatively clean air masses, and the short OH lifetime implies that it is at steady-state (total production is equal to loss). I leverage this chemistry by evaluating a convolution of OH drivers, OH production scaled by the lifetime of OH against its sink with carbon monoxide, as a potential “steady-state” proxy. I also assess the predictive skill of formaldehyde (HCHO), an intermediate product of the methane and OH reaction. I find that both proxies broadly reflect OH on sub-hemispheric scales (2 km altitude by 20° zonal bins) relative to existing, well-mixed proxies that capture, at best, hemispheric OH variability. HCHO is produced following methane loss by reaction with OH and reflects the insolation influence on OH, while the steady-state proxy demonstrates a stronger relationship with OH and offers insight into its sensitivity to a wider array of drivers. Few components—water vapor, nitric oxide, and the photolysis rate of ozone to singlet-d atomic oxygen—dominate steady-state proxy variance in most regions of the remote troposphere, with water vapor controlling the largest spatial extent. Current satellite instruments measure water vapor directly, and other retrievals like nitrogen dioxide columns or aerosol optical depth or could be used to infer nitric acid or the rate of ozone photolysis. Thus satellite observations may be used to derive a steady-state proxy product to infer OH variability and sensitivity in the near-term. HCHO is also retrieved from satellite instruments, and an OH product using satellite-observed HCHO columns is already in development. The relatively high fluctuation frequency of HCHO or the steady-state proxy advances our insight into the connection between OH and its drivers. The observed steady-state proxy demonstrates a widespread sensitivity to water vapor along the ATom flight tracks, and I conclude that an improved and consistent representation of the water vapor distribution is a necessary step in constraining the methane lifetime across global chemistry-climate models.

<p>Swimming is the second most common form of recreational activity in the U.S. Swimming pool water and air quality should be maintained to allow swimmers, pool employees, and spectators to use the pool facility safely. One of the major concerns regarding the health of swimmers and other pool users is the formation of disinfection by-products (DBPs) in swimming pools. Previous research has shown that volatile DBPs can adversely affect the human respiratory system. DBPs are formed by reactions between chlorine and other compounds that are present in water, most of which are introduced by swimmers, including many that contain reduced nitrogen. Some of the DBPs formed in pools are volatile, and their transfer to the gas phase in pool facilities is promoted by mixing near the air/water interface, caused by swimming and pool features.</p> <p><a>Swimming pool water treatment processes can play significant roles in governing water and air quality.</a> Thus, it is reasonable to hypothesize that water and air quality in a swimming pool facility can be improved by renewing or enhancing one or more components of water treatment.</p> <p>The first phase of the study was designed to identify and quantify changes in water and air quality that are associated with changes in water treatment at a chlorinated indoor pool facility. Reductions of aqueous NCl₃concentration were observed following the use of secondary oxidizer with its activator. This inclusion also resulted in significant decreases in the concentrations of cyanogen chloride (CNCl) and dichloroacetonitrile (CNCHCl₂) in pool water. The concentration of urea, a compound that is common in swimming pools and that functions as an important precursor to NCl₃ formation, as well as a marker compound for introduction of contaminants by swimmers, was also reduced after the addition of activator.</p> <p>The second phase of this study involved field measurements to characterize and quantify the dynamic behavior of indoor air quality (IAQ) in indoor swimming pool facilities, particularly as related to volatile compounds that are transferred from swimming pool water to air. Measurements of water and air quality were conducted before, during, and after periods of heavy use at several indoor pool facilities. The results of a series of measurements at different swimming pool facilities allowed for examination of the effects of swimmers on liquid-phase DBPs and gas-phase NCl₃. Liquid-phase NCl₃ concentrations were observed to gradually increase during periods of high swimmer numbers (<i>e.g.</i>, swimming meets), while liquid-phase CHCl₃ concentration was nearly constant in the same period. Concentrations of urea displayed a steady increase each day during these periods of intensive use. In general, the highest urea concentrations were measured near the end of each swimming meet. </p> <p>Measurements of IAQ dynamics during phase 2 of the study demonstrated the effects of swimmers on the concentrations of gas-phase NCl₃and CO₂, especially during swimming meets. The measured gas-phase NCl₃ concentration often exceeded the suggested upper limits of 300 µg/m³ or 500 µg/m³during swimming meets, especially during and immediately after warm-up periods, when the largest numbers of swimmers were in the pool. Peak gas-phase NCl₃ concentrations were observed when large numbers of swimmers were present in the pools; measured gas-phase concentrations were as high as 1400 µg/m³.Concentrations of gas-phase NCl₃ rarely reached above 300 µg/m³ during regular hours of operation. Furthermore, the types of swimmers were shown to affect the transfer of volatile compounds, such as NCl₃, from water to airin pool facilities. In general, adult competition swimmers promoted more rapid transfer of these compounds than youth competition swimmers or adult recreational swimmers. The measured gas-phase CO₂ concentration often exceeded 1000 ppm_v during swimming meets, whereas the gas-phase CO₂ concentration during periods of non-use of the pool tended to be close to the background (ambient) CO₂ concentration or slightly more than 400 ppm_v. This phenomenon was largely attributed to the activity of swimmers (mixing of water and respiratory activity) and the normal respiratory activity of spectators. </p> <p>IAQ models for gas-phase NCl₃ and CO₂ were developed to relate the characteristics of the indoor pool environment to measurements of IAQ dynamics. Several assumptions were made to develop these models. Specifically, pool water and indoor air were assumed to be well-mixed. The reactions that were responsible for the formation and decay of the target compounds were neglected. Two-film theory was used to simulate the net mass-transfer rate of volatile compounds from the liquid phase to the gas phase. Advective transport into and out of the air space of the pool were accounted for. The IAQ model was able to simulate the dynamic behavior of gas-phase NCl₃ during regular operating hours. Predictions of gas-phase NCl₃ dynamics were generally less accurate during periods of intensive pool use; however, the model did yield predictions of behavior that were qualitatively correct. Strengths of the model include that it accounts for the factors that are believed to have the greatest influence on IAQ dynamics and is simple to use. Model weaknesses include that the model did not account liquid-phase reactions that are responsible for formation and decay of the target compounds. The IAQ model for NCl₃ dynamics could still be a useful tool to form the basis for recommendations regarding the design and operation of indoor pool facilities so as to optimize IAQ.</p><p>Measurements of CO₂ dynamics indicated qualitatively similar dynamic behavior as NCl₃. Because of this, it was hypothesized that CO₂ may represent a surrogate for NCl₃ for monitoring and control of IAQ dynamics. To examine this issue in more detail, a conceptually similar model of CO₂dynamics was developed and applied. The model was developed to allow for an assessment of the relative contributions of liquid®gas transfer and respiration by swimmers and spectators to CO₂ dynamics. The results of this modeling effort indicated that the similarity of CO₂ transfer behavior to NCl₃ may allow use of CO₂ as a surrogate during periods with few to no spectators in the pool; however, when large numbers of spectators are present, the behavior of CO₂ dynamics may not be representative of NCl₃ dynamics because of spectator respiration.</p><p></p> <br>

Atmospheric particulate matter is known to have significant effects on human health, visibility, and global climate. The magnitudes of these effects, however, depend in complex ways on chemical composition, relative humidity, temperature, phase state, and other parameters. Current regional air quality models such as CMAQ (Community Multiscale Air Quality model) ignore many of these considerations, and consider that the formation of secondary organic aerosol (SOA) can be calculated by assuming thermodynamic ideality in the organic particulate matter (OPM) phase as well as negligible uptake of water into the OPM phase. Theoretical predictions and model simulations considering non-ideality and water uptake show that the standard model assumptions can lead to large errors in predicted SOA mass, and that the magnitude of these errors is sensitive to the composition of the OPM phase. The SOA module in CMAQ v4.7.1 has been revised in this work to allow consideration of the effects of both non-ideality and water uptake. First, a reasonable specific surrogate structure was assigned to each of the lumped products assumed to be produced by reaction of the different precursor hydrocarbons considered in CMAQ (e.g., isoprene, benzene, and toluene). Second, the CMAQ code was modified to allow iterative calculation (at each point in space and time) of the gas/particle partitioning coefficient for each of the SOA-forming products and for water. Third, model simulations were performed for the Eastern US at a resolution of 36-km x 36-km for late summer 2006, under a range of relative humidity conditions. When compared with an appropriate base case, the modified code produced increases in SOA ranging from 0.17 to 0.51 micrograms per cubic meter. The average change was 0.30 micrograms per cubic meter, corresponding to a 37% increase in SOA formation. Incorporation of phase separation effects would likely lead to further increases in predicted SOA levels.

The aim of this thesis is to investigate the effects of change in the chain length and chlorine group position on C-Cl bond photodissociation dynamics of chloroalkanes using the velocity map imaging (VMI) method. Three different chloroalkanes are studied (1-chloropropane, 2-chloropropane, 1-chloropentane) and compared with previously investigated chloromethane. Regardless of the parent chloroalkane, measured kinetic energy distributions (KEDs) of chlorine photofragments exhibit a single peak at energy around 0.8 eV. Photodissociation of higher chloroalkanes involves a recoil of a semi-rigid alkyl fragment, whose internal energy absorbs 40-60% of the total available energy. For chloromethane, however, only less than 10% of the available energy goes into the alkyl fragment excitation. Measured results of the energy partitioning are compared with cal- culations based on classical impulsive models. VMI experiment in combination with theory also yields information about the nature of electronic transition and probability of the intersystem crossing. Analysis indicates that the direct absorp- tion into the triplet state is more probable for the chloroalkanes with longer chain length, especially for the branched one. 1

No description available.

No description available.

Le changement climatique est relié à l’évolution de la composition chimique de l’atmosphère et de sa capacité oxydante, impliquant le système COV-NOy-HOx-O3. La troposphère tropicale, de l’Afrique de l’Ouest en particulier, joue un rôle critique sur la composition atmosphérique globale pour trois raisons majeures : (1) l’existence d’importantes sources de précurseurs d’espèces photooxydantes, (2) une photochimie active, (3) une activité convective intense en période de mousson. Pour évaluer son rôle, il est nécessaire de bien caractériser ces différents processus et leur interaction. Cette question est au coeur du programme international AMMA (Analyse Multidisciplinaire de la Mousson Africaine) dans lequel s’inscrit cette thèse. Ce travail a pour objectif de caractériser et d’évaluer l’impact de la convection nuageuse profonde sur la chimie photooxydante de la troposphère libre en Afrique de l’Ouest, en particulier pour les composés organiques volatils (COV), qui sont d’importants précurseurs d’ozone. Ce travail s’appuie sur les données physico-chimiques recueillies sur les deux avions de recherche français au cours de la campagne d’observation intensive de l’été 2006 de AMMA. Afin de compléter le dispositif instrumental embarqué, une nouvelle instrumentation de mesure indirecte des COV a été d’abord développée. Puis, l’utilisation de traceurs physico-chimiques et la mise en place d’outils diagnostiques appliqués aux COV (profils verticaux de concentrations, rapport de concentration de COV ad hoc, horloge photochimique, réactivité totale vis-à-vis de OH) ont montré que la convection profonde assure un transport vertical rapide et efficace des espèces gazeuses réactives émises près de la surface vers la haute troposphère. Enfin, un modèle photochimique de boîte 0D a permis de renseigner l’évolution de la composition chimique des masses d’air post-convectives. Les simulations montrent que les espèces transportées par la convection participent activement à la chimie et conduisent à une production nette et significative d’ozone dans la haute troposphère. La sensibilité de la production d’ozone aux précurseurs gazeux (COV et NOx) a été également évaluée. / Recent climatic change is tightly linked to the evolution of the chemical composition of the atmosphere and its oxidizing capacity through VOC-NOy-HOx-O3 system. The tropical troposphere, in particular of West Africa, plays a major role in the global atmospheric composition for three major reasons: (1) the existence of important ozone precursor sources, (2) an active photochemistry, (3) an intense convective activity during the monsoon period. To evaluate its role, it is necessary to characterize these processes and their interactions. This is one of the main objectives of the AMMA (African Monsoon Multidisciplinary Analyzes) international program. The present work goes through the frame of AMMA. Its main objective is to characterize and evaluate deep convection impact on the upper troposphere chemistry of West Africa, in particular for volatile organic compounds (VOC). This work is based on the data collected on the two French research aircrafts during the special observation period of AMMA in summer 2006. In order to enhance the instrumental device deployed onboard, a new offline instrumentation for non-methane hydrocarbons (NMHC) measurement was developed. Then, various physical and chemical tracers and several diagnostic tools applied to VOC data (vertical profiles, concentration ratios, photochemical clock, OH reactivity) showed that deep convection provides a fast and effective vertical transfer of reactive species emitted near the surface to the upper troposphere. At last, a photochemical box model 0D was used to simulate the chemical evolution of the composition of postconvective air masses. Simulations showed that reactive species transported by deep convection participate actively to the upper troposphere chemistry and lead to a significant and net ozone production. Ozone production sensitivity to VOC and NOx was also evaluated in the model.

A região metropolitana de São Paulo apresenta um intenso e desordenado processo de urbanização e industrialização. Devido a estes processos, a região sofre grandes problemas de poluição atmosférica, agravados em certos meses devido às dificuldades de dispersão dos poluentes. Estes poluentes causam efeitos indesejáveis ao meio ambiente e à saúde humana. A caracterização química e a avaliação da atividade mutagênica desses compostos presentes no material particulado atmosférico (MPA) é um grande desafio analítico e, é de extrema importância para o conhecimento das possíveis correlações entre os poluentes, os efeitos deletérios à saude e as fontes de emissão. Os objetivos deste trabalho foram caracterizar quimicamente os extratos orgânicos polares e semi-polares do material particulado atmosférico da cidade de São Paulo e avaliar sua atividade mutagênica. O MPA é uma mistura complexa de compostos orgânicos e inorgânicos presentes em diferentes faixas de concentrações. Devido a esta complexidade, o fracionamento químico do extrato orgânico deste material é necessário para isolar classes de compostos ou compostos individuais, permitindo a identificação e quantificação dos mesmos. Os resultados obtidos pelas diversas técnicas analíticas empregadas mostraram que os extratos em diclorometano e acetona contém inúmeros compostos orgânicos pertencentes a diferentes classes, tais como hidrocarbonetos policíclicos aromáticos, quinolinas, cetonas, piridinas, furanos, aldeídos, amidas e aminas, sendo que alguns destes compostos são considerados agentes genotóxicos. O extrato em DCM contem a maior massa e sua composição é quase exclusivamente orgânica. Já o extrato em ACE contem além dos orgânicos, espécies inorgânicas. Testes de mutagenicidade indicaram que o MPA coletado na cidade de São Paulo apresenta uma atividade mutagênica relativamente alta quando comparada a outros centros urbanos. / São Paulo metropolitan area presents an intense and chaotic process of urbanization and industrialization. Due to this processes, this region has big atmospheric pollution problem. In certain months of the year, this problem gets worse due to the unfavorable dispersion conditions. The pollutants cause undesirable effects to the environment and to the human health. The chemical characterization and the mutagenic activity evaluation of the compounds present on the atmospheric particulate matter APM) represents an analytical challenge and it is very important for understanding of the correlation among pollutants, health hazards and emission sources. The goal of this work was chemically characterize the polar and moderately polar organic extracts from the APM collected in São Paulo city and to evaluate their mutagenic activity. The APM is a complex mixture of organic and inorganic compounds present in large range of concentration. Due to this complexity, the chemical fractionation of these organic extracts is necessary to isolate classes or individual compounds, to allow their identification and quantification. The results obtained using different analytical techniques demonstrated that the dichlorometane and acetone extracts has several organic compounds belonging to different classes, such as, polycyclic aromatic hydrocarbons, quinolines, ketones, pyridines, furanes, aldehydes, amides and amines. Some of these compoundsa are considered carcinogens and/or mutagens. The dichloromethane extract presented the highest mass yield and its composition is almost exclusively organic. The acetone extract has organic and inorganic species. Mutagenicity tests revealed that the APM from São Paulo city presented a have relatively high mutagenic activity when compared to other urban regions.

O presente estudo teve como objetivo avaliar os compostos carbonílicos na atmosfera da cidade de São Paulo. Para tal medidas de carbonílicos foram feitas empregando metodologia analítica já existente. A influência do ozônio na geração de artefatos durante a amostragem de compostos carbonílicos empregando sorventes sólidos, como C18 e sílica, observada em amostragens diurnas e noturnas ( ausência de O3) permitiu estabelecer um protocolo de amostragem que recomenda a utilização de um coletor de O3 na entrada do cartucho de sílica impregnado com 2,4-dinitro-fenil-hidrazina (DNPH) para evitar possíveis artefatos de amostragem. Os compostos carbonílicos presentes na fase gasosa da atmosfera da cidade de São Paulo foram medidos durante o inverno de 1999, em dois sítios distintos, Cidade Universitária (CID) e Água Funda (AF). Semelhante a outras regiões urbanas do mundo, os carbonílicos majoritários foram formaldeído (0,6-46,7 ppbv) e acetaldeído (1,2-75,3 ppbv). Os carbonílicos de peso molecular maior (>C2) tiveram abundância relativa de 20-40%, sendo acetona (0,3-13,0 ppbv), acroleína (0,1-5,2 ppbv), propionaldeído (0,5-8,5 ppbv), isômeros C4 (0,1-2,4 ppbv), benzaldeído (0,1-5,4 ppbv), valeraldeído (0,1-3,5 ppbv), m-tolualdeído (0,1-2,4 ppbv) e hexaldeído (0,1-4,5 ppbv). As razões de concentração para acetaldeído/formaldeído > l em julho sugerem que a contribuição das emissões diretas é predominante. Já no mês de agosto, foi observada uma diminuição das razões médias, 1,1-1,3 (manhã), 0,7-0,8 (meio-dia) e 0,6 (tarde), indicando que há contribuição de emissões diretas na manhã e nos outros períodos prevalece a formação fotoquímica in situ. Neste trabalho, a influência de parâmetros meteorológicos nos níveis dos compostos carbonílicos foi verificada em alguns eventos. Foram propostas fontes de emissão através de correlações com CO e O3. As correlações no sítio CID em agosto mostraram que a contribuição das emissões veiculares é muito importante pela manhã, mas a influência dos processos fotoquímicos foi observada nos períodos seguintes. Finalmente, considera-se que este trabalho contribuiu para uma compreensão atual sobre o panorama dos carbonílicos na cidade e para o estudo em grande escala que permitirá diagnosticar e prever os episódios de poluição na cidade de São Paulo. / The goals of this study were to evaluate the carbonylic compounds in the atmosphere of São Paulo City. To accomplish this, measures were carried out using the pre-existent analytical methodology. The ozone influence in artifacts generation during carbonyls sampling using solid sorbents such as C18 and silica, observed through day and night samples, allowed to establish a sampling protocol which recommends the utilization of an ozone scrubber at the upstream end of the DNPH-impregnated silica cartridge to avoid eventual sarnpling artifacts. Carbonyl compounds present in the gaseous phase of São Paulo atmosphere were measured during winter, 1999, at two different sites, Cidade Universitária (CID) and Água Funda (AF). As observed in other urban regions of the world, the major carbonyls were formaldehyde (0,6-46, 7 ppbv) e acetaldehyde (1,2-75,3 ppbv). Toe higher molecular weight carbonyls (>C2) showed relative abundances of 20-40%, being acetone (0,3-13,0 ppbv), acrolein (0,1-5,2 ppbv), propionaldehyde (0,5-8,5 ppbv), isomers C4 (0,1-2,4 ppbv), benzaldehyde (0,1-5,4 ppbv), valeraldehyde (0,1-3,5 ppbv), m-tolualdehyde (0,1-2,4 ppbv) and hexaldehyde (0,1-4,5 ppbv). The acetaldehyde/formaldehyde (A/F) ratio >1 in July suggests that direct emissions influence is predominant. In August, a decrease in average concentration was observed, 1,1-1,3 (morning), 0,7-0,8 (midday) and 0,6 (evening), indicating the direct emissions contribution in the morning, while for the other periods the in situ photochemical formation prevails. At the present work, the influence of meteorological parameters in carbonyls levels was also pointed out for some events. The emission sources are proposed by calculating the correlations between carbonyls and CO and O3. The correlations found for the CID site in August showed that the vehicular emissions are very important in the morning, but the influence of photochemical processes was observed in the subsequent periods. Finally, this work contributed to a current comprehension of the carbonyls panorama in the city and for the large scale study that will allow the diagnosis and mimic of the urban chemical environment in São Paulo City.

O presente estudo teve como objetivo avaliar os compostos carbonílicos na atmosfera da cidade de São Paulo. Para tal medidas de carbonílicos foram feitas empregando metodologia analítica já existente. A influência do ozônio na geração de artefatos durante a amostragem de compostos carbonílicos empregando sorventes sólidos, como C18 e sílica, observada em amostragens diurnas e noturnas ( ausência de O3) permitiu estabelecer um protocolo de amostragem que recomenda a utilização de um coletor de O3 na entrada do cartucho de sílica impregnado com 2,4-dinitro-fenil-hidrazina (DNPH) para evitar possíveis artefatos de amostragem. Os compostos carbonílicos presentes na fase gasosa da atmosfera da cidade de São Paulo foram medidos durante o inverno de 1999, em dois sítios distintos, Cidade Universitária (CID) e Água Funda (AF). Semelhante a outras regiões urbanas do mundo, os carbonílicos majoritários foram formaldeído (0,6-46,7 ppbv) e acetaldeído (1,2-75,3 ppbv). Os carbonílicos de peso molecular maior (>C2) tiveram abundância relativa de 20-40%, sendo acetona (0,3-13,0 ppbv), acroleína (0,1-5,2 ppbv), propionaldeído (0,5-8,5 ppbv), isômeros C4 (0,1-2,4 ppbv), benzaldeído (0,1-5,4 ppbv), valeraldeído (0,1-3,5 ppbv), m-tolualdeído (0,1-2,4 ppbv) e hexaldeído (0,1-4,5 ppbv). As razões de concentração para acetaldeído/formaldeído > l em julho sugerem que a contribuição das emissões diretas é predominante. Já no mês de agosto, foi observada uma diminuição das razões médias, 1,1-1,3 (manhã), 0,7-0,8 (meio-dia) e 0,6 (tarde), indicando que há contribuição de emissões diretas na manhã e nos outros períodos prevalece a formação fotoquímica in situ. Neste trabalho, a influência de parâmetros meteorológicos nos níveis dos compostos carbonílicos foi verificada em alguns eventos. Foram propostas fontes de emissão através de correlações com CO e O3. As correlações no sítio CID em agosto mostraram que a contribuição das emissões veiculares é muito importante pela manhã, mas a influência dos processos fotoquímicos foi observada nos períodos seguintes. Finalmente, considera-se que este trabalho contribuiu para uma compreensão atual sobre o panorama dos carbonílicos na cidade e para o estudo em grande escala que permitirá diagnosticar e prever os episódios de poluição na cidade de São Paulo. / The goals of this study were to evaluate the carbonylic compounds in the atmosphere of São Paulo City. To accomplish this, measures were carried out using the pre-existent analytical methodology. The ozone influence in artifacts generation during carbonyls sampling using solid sorbents such as C18 and silica, observed through day and night samples, allowed to establish a sampling protocol which recommends the utilization of an ozone scrubber at the upstream end of the DNPH-impregnated silica cartridge to avoid eventual sarnpling artifacts. Carbonyl compounds present in the gaseous phase of São Paulo atmosphere were measured during winter, 1999, at two different sites, Cidade Universitária (CID) and Água Funda (AF). As observed in other urban regions of the world, the major carbonyls were formaldehyde (0,6-46, 7 ppbv) e acetaldehyde (1,2-75,3 ppbv). Toe higher molecular weight carbonyls (>C2) showed relative abundances of 20-40%, being acetone (0,3-13,0 ppbv), acrolein (0,1-5,2 ppbv), propionaldehyde (0,5-8,5 ppbv), isomers C4 (0,1-2,4 ppbv), benzaldehyde (0,1-5,4 ppbv), valeraldehyde (0,1-3,5 ppbv), m-tolualdehyde (0,1-2,4 ppbv) and hexaldehyde (0,1-4,5 ppbv). The acetaldehyde/formaldehyde (A/F) ratio >1 in July suggests that direct emissions influence is predominant. In August, a decrease in average concentration was observed, 1,1-1,3 (morning), 0,7-0,8 (midday) and 0,6 (evening), indicating the direct emissions contribution in the morning, while for the other periods the in situ photochemical formation prevails. At the present work, the influence of meteorological parameters in carbonyls levels was also pointed out for some events. The emission sources are proposed by calculating the correlations between carbonyls and CO and O3. The correlations found for the CID site in August showed that the vehicular emissions are very important in the morning, but the influence of photochemical processes was observed in the subsequent periods. Finally, this work contributed to a current comprehension of the carbonyls panorama in the city and for the large scale study that will allow the diagnosis and mimic of the urban chemical environment in São Paulo City.