• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 148
  • 67
  • 41
  • 20
  • 19
  • 7
  • 5
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 390
  • 390
  • 390
  • 92
  • 64
  • 58
  • 58
  • 49
  • 49
  • 48
  • 46
  • 46
  • 45
  • 42
  • 38
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Compostos orgânicos voláteis em tintas imobiliárias: caracterização e efeitos sobre a qualidade do ar em ambientes internos construídos / Volatile organic compound in paints: characterization and effects on air quality in indoor environments built

Patiño Guío, Lyda Milena 28 November 2013 (has links)
Materiais de construção como: adesivos, selantes, aglomerados, compensados, carpetes, revestimentos de parede, isolamentos, forros acústicos etc., emitem compostos orgânicos volateis (COVs) em ambientes internos (Niu e Burnett, 2001). No caso da tinta no Brasil, Salasar (2006) indica que \"as tintas à base de solventes emitem 520 vezes mais COVs em relação às tintas à base de água\". Consequentemente aumentos significativos na concentração de poluentes químicos e biológicos do ar em ambientes internos são provocados pelas baixas taxas de troca de ar em conjunto com a emissão de COVs originados pelos materiais de construção dos ambientes internos (Gioda & Neto, 2003). O objetivo nesta pesquisa é identificar compostos orgânicos volateis nas emissões de tintas imobiliárias usadas em ambientes internos na cidade de São Carlos. O laboratório foi realizado com o equipamento de cromatografia gasosa acoplado a espectrometria de massas, com siglas GC/MS, junto com o aparelho para extração da amostra chamado de micro extração de fase sólida (SPME), para duas amostras de cada tinta sendo uma fresca (úmida) e outra seca. O laboratório GC/MS quando é utilizado com micro extração de fase sólida (SPME) é o método mais aproximado do ideal, já que permite qualificar os COVs contidos nas amostras de tinta com maior eficiência que qualquer outro método (Koziel & Pawliszym, 2001). A escolha das tintas, esmaltes e o verniz foram determinadas como aquelas de maior uso e venda entre os pintores e lojas de tintas, respectivamente, na cidade de São Carlos. Os resultados mostraram que as tintas podem chegar a emitir juntas mais de 61 compostos orgânicos voláteis, a maior parte deles causa irritação respiratória e cinco desses compostos são suspeitos de desenvolver câncer, a concentração de cada composto não foi determinada. Uma suposição é que a saúde dos pintores pode estar sendo afetada, pois eles têm contato constante com as emissões das tintas, neste sentido é preocupante que esses trabalhadores da construção civil sejam informais, pois nesta condição o risco à sua saúde pode ser agravado devido à falta de capacitação necessária sobre a utilização do material que estão manipulando. Parte do resultado da pesquisa mostra também por meio de um questionário, as marcas de tintas imobiliárias comumente usadas na cidade de São Carlos, assim como uma noção sobre as doenças que as tintas produzem. O questionário foi elaborado para 40 pessoas entre pintores e vendedores de lojas de tinta na cidade de São Carlos. As fichas de segurança de produtos químicos FISPQ correspondentes para cada tinta omitem informações sobre alguns ingredientes considerados de risco encontrados nas amostras de tintas, como por exemplo, compostos suspeitos de desenvolver câncer. É importante para o Brasil a criação com urgência de um selo ambiental confiável que garanta a baixa concentração de emissão de COVs nas tintas como produto, mediante valores quantificáveis. Se similar ao selo \"Green Seal\", o mesmo daria não só uma forma de controle sobre a emissão de COVs nos prédios senão confiabilidade e garantia. O selo será um parâmetro de exigência nas certificações ambientais para confirmar as baixas emissões de COVs nos materiais das edificações sustentáveis, que até agora são inexistentes. / Building materials such as: Adhesives, sealants, plywood, carpeting, wall coverings, insulation, acoustic ceilings etc., emit volatiles organic compounds (VOCs) in indoor environments (Niu e Burnett, 2001). In the case of the paint in Brazil, Salasar (2006) indicates that \"solvent-based paints emit VOCs 520 times as compared to water-based paint.\". Consequently significant concentration of chemical and biological pollutants from indoor air, are caused by low rates of air exchange in conjunction with the emission of VOCs originating from the construction of the indoor materials (Gioda & Neto, 2003). The objective of this research is to identify volatile organic compounds (VOC) emissions from architectural coatings used indoors in São Carlos. The laboratory was performed with gas chromatography equipment coupled to mass spectrometry with acronyms GC/MS, with the instrument for sample extraction called solid phase micro extraction (SPME) for two samples of each paint: a fresh (wet) and a dry. The GC/MS laboratory when used with solid phase micro extraction (SPME) is the closest to the ideal method, allows to qualify the VOCs contained in the paint samples more efficiently than any other method (Pawliszym & Koziel, 2001). The choice of paints, enamels and varnish were determined as those of greater use and sale among painters and paint stores, respectively, in the city of São Carlos. The results showed that the paint can issue more than 61 volatile organic compounds, most of them cause respiratory irritation and five of these compounds are suspected of developing cancer, the concentration of each compound was not determined. One of the hypotheses is that the health of painters may be being affected, as they have constant contact with emissions from paints,in this respect it is wrong that these workers of the construction are informal, because in this condition the risk to your health can be aggravated due to lack of necessary training on the use of the material. Part of the search result also shows by means of a questionnaire , the marks of paints commonly used in the city of São Carlos, as well as a notion about the diseases that produce the paints. The questionnaire was designed in 40 people between painters and sellers of paint shops in the city of São Carlos. Safety data sheets for chemicals corresponding MSDS for each paint omit some information about ingredients considered risk in samples of paints, such as examples, compounds suspected of developing cancer. It is important for Brazil to urgently create a reliable environmental seal that ensures low emission concentration of VOCs in paints and product through quantifiable values . If the seal is similar to the seal \"Green Seal\", it would not only a form of control over the emission of VOCs in buildings too reliability and warranty The stamp will be a requirement parameter in environmental certifications to confirm low emissions of VOCs in materials of sustainable buildings , which until now are nonexistent.
272

Evaluation et traitement des polluants émis par un moteur thermique fonctionnant avec des biocarburants / Evaluation and treatment of polluants emitted by an engine fed with biofuels

Cosseron, Anne-Flore 29 October 2012 (has links)
Les biocarburants présentent une alternative prometteuse à l’utilisation de carburants fossiles. Cependant, l’augmentation de la quantité de biocarburants introduite dans les carburants nécessite de connaître leur impact sur les émissions de polluants. Le travail réalisé lors de cette thèse peut être décrit en deux parties : La première traite de l’évaluation des émissions de polluants réglementés et non réglementés émis par la combustion de biocarburants dans un moteur diesel. Différents biocarburants ont été testés : des esters méthyliques d’huile de soja et de colza, des esters éthyliques d’huile usagée et un carburant de référence exempt de tout biocarburant. Les résultats montrent que la nature des biocarburants ainsi que leur teneur ont un impact sur les polluants émis. Par exemple, une diminution de la taille des particules émises a été observée avec l’utilisation des esters méthyliques d’huile de soja. Le deuxième objectif de cette thèse concerne le piégeage des polluants Diesel, notamment des composés organiques volatils par des zéolithes. Plusieurs zéolithes ont été synthétisées puis caractérisées. Des tests d’adsorption par thermogravimétrie ont ensuite été réalisés au laboratoire avec différentes molécules sondes représentatives des polluants émis par les moteurs Diesel (le n-hexane, le p-xylène et l’acétone). Certaines zéolithes comme les zéolithes faujasite présentent des capacités d’adsorption intéressantes. Toutefois, la plupart des résultats montrent une diminution de la capacité d’adsorption avec l’augmentation de la température. Ces zéolithes ont ensuite été placées en sortie d’échappement d’un moteur diesel afin d’étudier leur capacité d’adsorption. / Nowadays, biofuels are a promising alternative to the use of fossil fuels. However, increasing the amount of biofuels introduced in fuels requires to know their impact on emissions pollutants.The work done in this thesis can be described in two parts: The first one deals with the evaluation of emissions of regulated pollutants (NOx, CO, CO2, O2, THC) and unregulated pollutants (volatile organic compounds, carbonyl compounds and fine particles (between 30 nm and 10 microns)) emitted by the combustion of biofuels in a diesel engine. Different biofuels have been tested: methyl esters of soybean oil and rapeseed oil, ethyl esters of used oil and a reference fuel free of biofuel. The results show that the nature of biofuels and their content have an impact on the pollutants emitted. For example, a decrease in the size of the particles emitted was observed with the use of methyl esters of soybean oil. The second objective of this thesis was to trap pollutants, like volatile organic compounds (VOCs) with zeolites. Several hydrophilic and hydrophobic zeolites have been synthesized and characterized. Adsorption tests were then carried by thermogravimetry with different probe molecules representative of pollutants from diesel engines (n-hexane, p-xylene and acetone). Some zeolites such as faujasite zeolites have interesting adsorption capacities. However, most of the results show a decrease in the adsorption capacity with the increase of the temperature. Then, these zeolites have been placed in the exhaust outlet of a diesel engine in order to study their adsorption capacity.
273

Bicyclists' Uptake of Traffic-Related Air Pollution: Effects of the Urban Transportation System

Bigazzi, Alexander Y. 27 October 2014 (has links)
While bicyclists and other active travelers obtain health benefits from increased physical activity, they also risk uptake of traffic-related air pollution. But pollution uptake by urban bicyclists is not well understood due to a lack of direct measurements and insufficient analysis of the determinants of exposure and ventilation (breathing). This knowledge gap impedes pollution-conscious transportation planning, design, and health impact assessment. The research presented in this dissertation generates new connections between transportation system characteristics and pollution uptake by bicyclists. The primary research questions are: 1) how do urban bicyclists' intake and uptake of air pollution vary with roadway and travel characteristics and 2) to what extent can transportation-related strategies reduce uptake. Breath biomarkers are used to measure absorbed doses of volatile organic compounds (VOCs). This research is the first application of breath biomarkers to travelers and the first uptake measurements of any pollutant to include roadway-level covariates. Novel methods to collect and integrate bicycle, rider, traffic, and environmental data are also introduced. Bicyclist exposure concentrations, exhaled breath concentrations, respiratory physiology, and travel characteristics were collected on a wide range of facilities in Portland, Oregon. High-resolution trajectory and pollution data were then integrated with roadway and traffic data. Models of exposure, ventilation, and uptake of VOCs were estimated from the on-road data. Important new quantifications in the models include the effects of average daily traffic (ADT) on multi-pollutant exposure, the lagged effect of on-road workload on ventilation, and the effects of exposure and ventilation on absorbed VOCs. Estimated models are applied to situations of interest to travelers and transportation professionals. Sample applications include the inhalation dose effects of road grade, cruising speed choice, stops, and detouring to parallel low-traffic facilities. In addition, dose-minimizing routing behavior is compared with revealed routing preferences in the literature. Finally, findings from this research and the literature are distilled so that they can be incorporated into bicycle network design guidelines.
274

Etude Expérimentale de la décharge couronne pour le traitement de l'air intérieur : COV et particules / Experimental study of the corona discharge for indoor air treatment : VOC and particles

Chen, Longwen 13 December 2018 (has links)
La qualité de l'air intérieur est devenue une préoccupation de santé publique du fait notamment de l'augmentation du temps passé dans les environnements intérieurs et les espaces clos. L'objectif de ce travail est de développer des procédés mettant en œuvre la décharge couronne afin de traiter les polluants gazeux chimiques et particulaires dans l'air intérieur. Le premier volet du travail concerne la dégradation des polluants gazeux chimiques présents en très faibles concentrations dans l’air intérieur. Le couplage d’une décharge couronne et d’un catalyseur est mis en œuvre pour dégrader du toluène dans des conditions représentatives de l’air intérieur. Cette étude démontre la très bonne efficacité de la décharge couronne vis-à-vis du toluène avec de faibles densités d’énergie. Elle identifie les conditions opératoires optimales et propose des mécanismes réactionnels suite à l’identification des principaux produits de réaction. Cependant, le plasma génère des espèces indésirables comme l'ozone et les oxydes d'azote qui doivent impérativement être détruits. Nous avons choisi d'adjoindre à la décharge couronne un catalyseur à base d'oxydes de métaux de transition (MnOx/Al2O3). Différents catalyseurs sont synthétisés puis modifiés par greffage d’agents modifiants. Leur efficacité vis-à-vis de l’ozone et des NOx est quantifiée en présence de différentes teneurs en vapeur d’eau. Le deuxième volet concerne la collecte des particules par filtration électrostatique. Trois procédés sont étudiés ; ils associent un étage d’ionisation et un étage de collecte. L’ionisation est assurée soit par un électrofiltre fil-plaque soit par des aiguilles portées à un potentiel de quelques kilovolts. L’efficacité de collecte est mesurée dans la gamme de 10 nm à 20 µm en fonction de différents paramètres opératoires (tension, polarité, vitesse, paramètres géométriques, concentration en particules, humidité, etc.). Les aiguilles ont une efficacité légèrement inférieure à celle de l’électrofiltre mais présentent une très faible production de l'ozone et une consommation énergétique moindre. L’étude paramétrique permet de dimensionner, d'optimiser la géométrie du procédé et de définir les meilleures conditions de fonctionnement / Indoor air quality has become a public health issue because of the increased time spent in indoor environments and confined spaces. The goal of this work is to develop processes using corona discharge to treat chemical gaseous and particulate pollutants in indoor air. The first part of the work concerns the degradation of chemical gaseous pollutants present in very low concentrations in indoor air. The coupling of a corona discharge and a catalyst is implemented to degrade toluene under conditions representative of the indoor air. Tests were carried out under a range of operating and environmental conditions. This study demonstrates the very good efficiency of the corona discharge for toluene with very low specific density. Optimal operating conditions are identified and reaction mechanisms are proposed following the identification of the main reaction products. However, the generations of by-products, ozone and NOx, which can be hazardous compounds, have to be taken into account. The combination of corona discharge with catalysis seems as a promising way to ensure the suitability and the safety of non-thermal plasma as an indoor air cleaner. Different catalysts based on transition metal oxides (MnOx/Al2O3) are synthesized and then modified by grafting modifying agents. Their efficiency for ozone and NOx elimination is quantified in the presence of different water vapor contents. The second part concerns the particle collection by electrostatic precipitation. Three processes are studied; they combine an ionization stage and a collection stage. The ionization is ensured either by a wire-plate electrostatic precipitator (ESP) or by needles brought to a potential of a few kilovolts. The collection efficiency is measured in the range of 10 nm to 20 μm according to different operating parameters (voltage, polarity, velocity, geometrical parameters, particle concentration, humidity, etc.). The needles have a slightly lower efficiency than the ESP but present a very low production of ozone and a lower energy consumption. The parametric study makes it possible to dimension, to optimize the geometry of the process and to define the best operating conditions
275

Simulating and explaining passive air sampling rates and analyte air concentrations for semi-volatile compounds on polyurethane foam disks

Petrich, Nicholas Thomas 01 December 2012 (has links)
No description available.
276

Identification and characterisation of physicochemical processes controlling indoor concentrations of submicron aerosols and volatile organic compounds / Identification et caractérisation des processus physicochimiques contrôlant les concentrations en particules submicroniques et composés organiques volatils en air intérieur

Stratigou, Evdokia 04 June 2019 (has links)
Cette thèse développe les connaissances scientifiques sur l’origine et le comportement des polluants intérieurs en phases gazeuse et particulaire. Une description complète des processus physiques contrôlant les concentrations de polluants en air intérieur dans une pièce inoccupée et non meublée a été réalisée. En utilisant des paramètres bien quantifiés (taux de renouvellement d’air, facteur de pénétration et vitesse de dépôt), nous avons pu appliquer un modèle de bilan massique aux particules. Les résultats ont montré que, en l’absence significative de sources intérieures, une caractérisation fine des paramètres ci-dessus permettait de décrire de manière satisfaisante les concentrations intérieures en PM2.5 et PM10 à partir des données extérieures, tandis que les PM1 montrent une variabilité significativement plus marquée due aux transformations physicochimiques. Par la suite, les composés organiques volatils (COV) et la composition chimique des particules submicroniques ont été mesurés en temps réel lors d’une campagne intensive. Un enrichissement important des concentrations en COV a été observé lorsque l’air ambiant pénètre à l’intérieur du bâtiment, en particulier pour les COV oxygénés qui présentent une dépendance significative avec l’humidité relative, tandis que pour les particules les changements observés dépendent de leur composition chimique et de leur diamètre, montrant une diminution de 20% pour les PM1 à 86% pour les plus grosses particules (>5 μm). L’excès d’ammonium observé dans les deux environnements a permis de déconvoluer les nitrates organiques des inorganiques, ceux-ci présentant une dépendance plus forte avec la température, révélant une décomposition thermique plus importante en air intérieur. En résumé, l’environnement intérieur agit principalement comme une source d’émissions continues de COV, alors qu’une tendance inverse est observé pour les particules, du fait de transformations possibles pouvant se produire même dans les conditions les plus simples, sans occupant ni mobilier. / This thesis improves the scientific knowledge on the origin, behavior and fate of gas and particle-phase pollutants indoors under unoccupied unfurnished conditions. A first campaign provided a complete description of the physical processes controlling the indoor concentrations. Using well quantified parameters (air exchange rate, penetration factor and deposition rate), a mass balance model provided insights for the particle budget closure. The results showed that when indoor sources are not significant, a careful characterization of the abovementioned parameters allows to estimate PM2.5 and PM10 in a satisfying manner from outdoor data. However the PM1 fraction shows a significantly higher variability due to physicochemical transformations. Subsequently, a second intensive campaign was performed to investigate volatile organic compounds (VOC) and PM1 chemical composition in real time. A strong increase in VOC concentrations was observed when outdoor air penetrates indoors, especially oxygenated VOC which exhibited a significant dependence on relative humidity, while the changes observed for particles once indoors depend on their chemical composition and diameter, showing a decrease from 20% for submicron particles up to, 86% for large ones (>5. µm). The investigation of ammonium neutralization revealed an excess of ammonium indoors and outdoors, which is attributed to organic- in addition to inorganic-bonded ammonium nitrate. The latter showed a stronger dependency on temperature gradient from outdoors to indoors, revealing stronger thermal decomposition once indoors. In summary, the indoor environment acts mainly as a continuous emission source of VOCs, while the opposite trend is observed the particles due to possible transformations that can occur even under the simplest conditions, with no occupants and no furnishing.
277

Indoor Environment in Dwellings and Sick Building Syndrome (SBS) : Longitudinal Studies

Sahlberg, Bo January 2012 (has links)
People spend most of their time indoors and mostly in the dwelling. It is therefore important to investigate associations between indoor exposure in dwellings and health. Symptoms that may be related to the indoor environment are sometimes referred to as the "sick building syndrome" (SBS). SBS involves symptoms such as eye, skin and upper airway irritation, headache and fatigue. Three longitudinal studies and one prevalence study on personal and environmental risk factors for SBS in adults were performed. The prevalence study included measurements of indoor exposures in the dwellings. The longitudinal studies, with 8-10 years follow-up time, showed that smoking and indoor paint emissions were risk factors for SBS. Moreover, building dampness and moulds in dwellings were risk factors for onset (incidence) of general symptoms, skin symptoms and mucosal symptoms. In addition subjects living in damp dwellings have a lower remission of general symptoms and skin symptoms. Hay fever was a risk factor for onset of skin symptoms and mucosal symptoms, and asthma was a risk factor for onset of general and mucosal symptoms. Biomarkers of allergy and inflammation (bronchial reactivity, total IgE, ECP and eosinophil count) were predictors of onset of SBS symptoms, in particular mucosal symptoms. In the prevalence study, any SBS-symptom was associated with some individual volatile organic compounds of possible microbial origin (MVOC) e.g. 2-pentanol, 2-hexanon, 2-pentylfuran and 1-octen-3ol. Moreover, there were associations between indoor levels of formaldehyde and the plasticizer Texanol and any SBS. The result from the study indicates that individual MVOC are better indicators of SBS than the total value of MVOC. A final conclusion is that smoking, dampness and moulds and emissions from indoor painting may increase the onset of SBS. The indoor environment in dwellings over time has improved, but there is still a need for further improvements of the indoor environment in dwellings. More longitudinal SBS studies are needed.
278

Part I. From the Lab to the Field - Recent Developments in Polymer Coated ATR Sensing for the Determination of Volatile Organic Compounds ; Part II. From the Field to the Lab - Investigating IR Signatures for Remote Sensing Applications

Karlowatz, Manfred 22 June 2004 (has links)
Part I: Successful transition of polymer coated, ATR-FTIR sensor devices from a laboratory environment to real world field applications for detecting and quantifying VOCs in water is shown. Simultaneous, quantitative detection of BTX mixtures in water during enrichment into polymer coated ZnSe ATR elements has been performed. The obtained results showed accurate detection and quantification to the low ppb concentration region. Fiber-optic evanescent field measurement campaigns have been conducted at simulated field conditions during which concentration gradients of various VOCs in the mg/L range have been monitored successfully. The first test of an ATR based, polymer coated sensor system under real world field conditions, the chlorobenzene concentration in groundwater at mg/L levels was determined. An interesting aspect of these measurements was the experimental proof for the dependence of analyte extraction dynamics on the flow conditions of the sample matrix surrounding the extractive polymer membrane. The obtained results demonstrate that MIR evanescent field sensors are suitable for in-situ analysis at real world field conditions for environmental monitoring applications. PART II: Recently, measurements of disturbed soils have shown different spectral contrast in comparison to undisturbed soils. In this work first measurements at controlled laboratory conditions have been performed to investigate individual minerals of the soil matrix and their spectral characteristics under various environmental conditions. ATR spectroscopy has been applied to investigate multi-disperse quartz sand and mono-disperse soda lime glass spheres samples. For the investigation of spectral differences between pristine and disturbed quartz sand, a wetting/drying procedure with subsequent sample aerating has been developed. In addition to established differences in spectral contrast of disturbed and undisturbed soil, a strong spectral shift of absorption features was observed. When probed with s- or p-polarized light, both samples showed strong LO-TO mode splitting. The studies also reveal that the main reason for spectral differences of pristine and disturbed soils is caused by water facilitated changes of the particle size distribution in the probed volume. The presented results advance the variety of spectral characteristics useful for the detection of disturbed soils (i.e. possible landmine sites) with MIR imaging systems.
279

Constraining global biogenic emissions and exploring source contributions to tropospheric ozone: modeling applications.

Shim, Changsub 26 June 2006 (has links)
Biogenic isoprene plays an important role in tropospheric chemistry. We use HCHO column measurements by the Global Ozone Monitoring Experiment (GOME) to constrain isoprene emissions. Using the global Goddrad Earth Observing SystemChemistry (GEOS-Chem) as the forward model, a Bayesian inversion of GOME HCHO observations from September 1996 to August 1997 is conducted. Column contributions to HCHO from 12 sources including 10 terrestrial ecosystem groups, biomass burning, and industry are considered and inverted for 8 geographical regions globally. The a posteriori solution reduces the model biases for all regions, and estimates the annual global isoprene emissions of 566 Tg C yr-1, ~50% larger than the a priori estimate. Compared to the Global Emissions Inventory Activity (GEIA) inventory (~500 Tg C yr-1), the a posteriori isoprene emissions are generally higher at mid latitudes and lower in the tropics. This increase of global isoprene emissions significantly affects tropospheric chemistry, decreasing the global mean OH concentration by 10.8% to 0.95106 molecules/cm3. The atmospheric lifetime of CH3CCl3 increases from 5.2 to 5.7 years. Positive matrix factorization (PMF), an advanced method for source apportionment, is applied to TRAnsport of Chemical Evolution over the Pacific (TRACE-P) measurements and it is found that cyanogenesis in plants over Asia is likely an important emission process for CH3COCH3 and HCN. This approach also is applied to estimate source contributions to the tropospheric ozone (O3) with Tropospheric Ozone Production about the Spring Equinox (TOPSE) and TRACE-P measurements. The corresponding GEOS-Chem simulations are applied to the same factor-projected space in order to evaluate the model simulations. Intercontinental transport of pollutants is most responsible for increasing trend of springtime O3, while stratospheric influence is the largest contributions to troposperic O3 variability at northern middle and high latitudes. On the other hand, the overall tropospheric contributions to O3 variability are more important at northern low latitudes by long-range transport, biomass burning, and industry/urban emissions. In general, the simulated O3 variabilities are comparable with those of observations. However, the model underestimates the trends of and the contributions to O3 variability by long-range transport of O3 and its precursors at northern middle and high latitudes.
280

Seasonal Variation of Ambient Volatile Organic Compounds and Sulfur-containing Odors Correlated to the Emission Sources of Petrochemical Complexes

Liu, Chih-chung 21 August 2012 (has links)
Neighboring northern Kaohsiung with a dense population of petrochemical and petroleum industrial complexes included China Petroleum Company (CPC) refinery plant, Renwu and Dazher petrochemical industrial plants. In recent years, although many scholars have conducted regional studies, but are still limited by the lack of relevant information evidences (such as odorous matters identification and VOCs fingerprint database), while unable to clearly identify the causes of poor ambient air quality. By sampling and analyzing VOCs, we will be able to understand the major sources of VOCs in northern Kaohsiung and their contribution, and to provide the air quality management and control countermeasures for local environmental protection administration. In this study, we sampled and analyzed the speciation of VOCs and sulfur-containing odorous matters (SOMs) in the CPC refinery plants, Renwu and Dazher petrochemical complexes simultaneously with stack sampling. The sampling of VOCs and SOMs were conducted on January 7th, 14th, and 19th, 2011 (dry season) and May 6th, 13rd, and 23rd, 2011 (wet season). We established the emission source database, investigated the characteristics of VOC fingerprints, and estimate the emission factor of each stack. It helps us understand the temporal and spatial distribution of VOCs and ascertain major sources and their contribution of VOCs. Major VOCs emitted from the stacks of the CPC refinery plant were toluene and acetone. It showed that petroleum refinery processes had similar VOCs characteristics and fingerprints. The fingerprints of stack emissions at Renwu and Dashe industrial complexes varied with their processes. Hydrogen sulfide was the major sulfur-containing odorous matter in all petrochemical plants. Compared to other petrochemical complexes, Renwu industrial complex emitted a variety of SOMs species as well as relatively high concentrations of sulfur-containing odorous matters. The petrochemical industrial complexes in the industrial ambient of VOCs analysis results showed that isobutane, butane, isopentane, pentane, propane of alkanes, propene of alkenes, toluene, ethylbenzene, xylene, styrene of aromatics, 2-Butanone (MEK), acetone, of carbonyls are major species of VOCs. In addition, ethene+acetylene+ethane (C2), 1,2-dichloroethane, chloromethane, dichloromethane, MTBE were also occasionally found. Sulfur-containing odorous matter (SOMs) analytical results showed that major odorous matters included hydrogen sulfide, methanethiol, dimethyl sulfide, and carbon disulfide. The highest hydrogen sulfide concentration went up to 5.5 ppbv. In this study, the species of VOCs were divided into alkanes, alkenes, aromatics, carbonyls, and others. The temporal and spatial distribution of various types of VOCs strongly correlated with near-surface wind direction. The most obvious contaminants were alkanes, aromatics, and carbonyls of the dispersion to the downwind. Generally, the ambient air surrounding the petrochemical industrial complexes was influenced by various pollutants in the case of high wind speeds. It showed that stack emission and fugitive sources had an important contribution to ambient air quality. TSOMs and hydrogen sulfide emitting mainly from local sources resulted in high concentration of TSOMs and hydrogen sulfide surrounding the petrochemical industrial complex. Principal component analysis (PCA) results showed that the surrounding areas of petrochemical industrial complexes, regardless of dry or wet seasons, were mainly influenced by the process emissions and solvent evaporation. The impact of traffic emission sources ranked the second. Chemical mass balance receptor modeling showed that stack emissions from the CPC refinery plants contributed about 48 %, while fugitive emission sources and mobile sources contributed about 30 % and 11%, respectively. The stack emissions from Renwu industrial complex contributed about 75 %, while fugitive emission sources and mobile sources contributed about 17 % and 5 %, respectively. The stack emissions from Dazher industrial complex contributed about 68 %, while fugitive emission sources and mobile sources contributed about 21 % and 2 %, respectively.

Page generated in 0.0918 seconds