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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Environmental and health impacts when replacing kerosene lamps with solar lanterns : A study on global warming potential and household air pollution

Stenemo, Erik, Olsson, Emma January 2018 (has links)
In regions with low energy access kerosene lamps are commonly used, and these emit carbon dioxide (CO2) as well as household air pollutants (HAP). This bachelor thesis examines the possible reduction of carbon dioxide equivalents (CO2eq) emissions and HAP from kerosene lamps by replacing them with off-grid solar powered lanterns. Life cycle assessment, or LCA, is used as a method to assess CO2eq emissions from the solar lanterns. Data on emissions from the different stages in the solar lantern lifecycle, as well as for the kerosene lamps, is gathered through literature studies. Furthermore, possible improvements of health and social aspects as result of replacing kerosene lamps are studied and discussed. The results show that CO2eq emissions could be significantly lower if solar lanterns were used. During a lifetime of 30 years, a simple kerosene lamp emits a total of 15 500 kg CO2eq, a hurricane lantern 7 900 kg CO2eq, whereas a solar lantern emits 66.1 kg CO2eq. However, it is found that the possible harmful effects of HAP are much larger than those of CO2. Finally, possibilities and challenges regarding implementation and usage of off-grid solar powered lanterns are identified and discussed.
32

[en] GEOCHRONOLOGICAL VARIATIONS OF CARBON BLACK AND PAHS IN GUANABARA BAY AS INDICATORS OF COMBUSTION SOURCES / [pt] VARIAÇÕES GEOCRONOLÓGICAS DE CARBONO NEGRO E HPA NA BAÍA DE GUANABARA COMO INDICADORES DE FONTES DE COMBUSTÃO

CRISTIANE RIBEIRO MAUAD 26 November 2010 (has links)
[pt] As pesquisas sobre carbono negro (BC) vêm ganhando grande importância nos últimos anos, não somente devido a sua capacidade de atuar como traçador histórico de processos de combustão em uma determinada região, mas também devido a sua capacidade de sorver contaminantes hidrofóbicos de ambientes aquosos. Buscou-se estudar a geocronologia de dois subprodutos provenientes de processos de combustão (BC e HPAs - hidrocarbonetos policíclicos aromáticos), que podem ter origem tanto de queima de biomassa quanto de combustíveis fósseis em um testemunho sedimentar coletado da região noroeste da Baía de Guanabara. Foram avaliadas suas possíveis relações, entre si e com o teor de carbono orgânico presente no sedimento. Avaliaram-se também as possíveis fontes dos HPAs presentes nas amostras, traçando um histórico de queima da região, caracterizada por um acentuado trafego veicular e poluição crônica por diversos compostos. O testemunho foi seccionados em intervalos de 2 cm, onde foram utilizados os segmentos entre 0-72 cm somando totalizando 30 amostras. A metodologia analítica utilizada para a determinação do BC foi a CTO-375, baseada na retirada da matéria orgânica (não-BC) por combustão na presença de oxigênio em excesso, restando somente a fração mais refratária composta pelo BC. Embora a variação percentual de BC tenha apresentado uma média de 0,36 (+-) 0,08 % p.s. ao longo do testemunho, foi observado que o mesmo compõe uma fração significativa do carbono orgânico total (TOC) desta região chegando a representar até 18% p.s. do TOC. A razão C/N possibilitou mostrar que grande parte de matéria orgânica presente neste local é proveniente de origem marinha. O método utilizado para a determinação da concentração dos HPAs foi o EPA 3540C, baseado na extração dos analitos da matriz, a purificação dos extratos através da remoção de interferentes. Através das razões diagnósticas e da análise de componentes principais (PCA) foi possível traçar uma transição das principais fontes de HPAs neste ambiente, mostrando a predominância de HPAs pirogênicos nas amostras mais antigas, para uma maior contaminação petrogênica nas amostras mais recentes. Ainda foi possível comprovar a afinidade de HPAs pirogênicos à presença de BC. Análises de microscopia eletrônica de varredura (SEM) contribuíram para uma maior compreensão das características morfológicas do sedimento, mostrando este ser rico em material amorfo e diatomáceas cêntricas. Esta análise também possibilitou a identificação visual da partícula de BC, porém, a falta de um pré-tratamento nas amostras dificultou o seu reconhecimento. Foram realizadas análises de ressonância magnética nuclear (CP/MAS (13)C NMR) visando possibilidades futuras de determinação de BC por esta técnica. As análises de NMR mostraram que o elevado teor de carbono aromático presente na amostra ambiental, relacionado principalmente a presença de lignina, interfere no sinal de NMR para a determinação de BC, sendo necessária a sua oxidação. Análises de CP/MAS-NQS (13)C NMR possibilitaram a separação das frações de BC, mostrando um teor acentuado de carbonos não-substituídos, sugerindo maior aporte de BC proveniente de queima ao longo do testemunho. Na amostra mais superficial, percebeu-se maior presença de carbonos quaternários, indicando o aumento no aporte de BC oriundo de combustão de combustíveis fósseis. / [en] Researches about black carbon (BC) have been gaining importance in recent years, not only because of its ability to act as a tracer of historical combustion processes in a given region, but also for its ability to adsorb hydrophobic contaminants in aqueous environments. In a sediment core collected from the northwestern region of Guanabara Bay, was attempted to study the geochronology of two combustion sub-products processes (BC and PAHs - polycyclic aromatic hydrocarbons), which may originate both biomass burning and fossil fuels. Was evaluated their possible relationships between themselves and with the content of organic carbon in the sediment. Also was evaluated the possible PAHs sources in the samples, tracing a burning history in the region, characterized by a marked vehicular traffic pollution and chronic individual compounds. The core was sectioned at intervals of 2 cm, which were used from 0 to 72 cm segments, in a total of 30 samples. The BC analytical determination methodology was the CTO-375, based on organic matter (non-BC) removal by combustion in presence of excess oxygen, leaving only a fraction composed by most refractory BC. Although the BC percentage had an average of 0.36 (+-) 0.08% dry weight over the core, was observed that is a significant fraction of total organic carbon (TOC) in this place representing up to 18% d.w. of TOC. The C/N ratio permitted evaluate that much of organic matter on this site comes from sea sources. The method used for determining the concentration of PAHs was the EPA 3540C, based on the analytes extraction from the matrix, and the extracts purification through the interferences removal. Through diagnostic reasons and principal component analysis (PCA), were possible to evaluate a PAHs transition of the main sources in this environment, showing the PAHs predominance in older pirogenics samples to an increase of petrogenic contamination in the most recent samples. It was also possible to relate an affinity of PAHs pyrogens in the BC presence. Analysis of scanning electron microscopy (SEM) contributed to a better understanding about the sediment morphological characteristics, showing to be rich in amorphous material and centric diatoms. This analysis also allowed the visual identification of the BC particles, however, the lack of a pre-treatment in the samples made it difficult to recognize. Nuclear magnetic resonance (CP/MAS (13)C NMR) analysis were performed in order to future possibilities of BC determination by this technique. The NMR analysis showed that the high aromatic carbon content in the environment sample, is mainly related to the presence of lignin interferes with the signal of NMR for the determination of BC, which requires its oxidation. Analysis of CP/MAS-NQS (13)C NMR allowed the separation of fractions of BC, showing a strong level of carbon non-replaced, suggesting a greater contribution of BC from burning during the core. In the most superficial sample, it was observed the large presence of quaternary carbons, indicating an increase in the input of BC come from combustion of fossil fuels.
33

Elementární půdní areál starých milířišť / ESA of the old charcoal kiln

Macounová, Kristina January 2017 (has links)
The topic of this dissertation is the assessment of the black carbon in the soil. The soil samples were collected in the Brdy area. Relics of charcoal kilns from the 17th - 18th centuries occur there in some places. A part and parcel of this paper is the literature search of the black carbon in the soil, of the history of burning charcoal and of the general characterization of the site where the terrain measurements were in progress. The measuring specification is a part of this paper, too. The results showed changes of physical and chemical characteristics between original forest soils and soils enriched by the black carbon. These soils in the beech forest showed approximately pH 4,7, while soils in the spruce forest showed pH 3,7 on the average. Original soils in the beech forest were more acid by 1 pH unit, and the original soils in the spruce forest were by 0,3 pH more acid. The bulk density of the original soils was 1,28 g/cm3 on the average, and the soils enriched by black carbon decreased to 0,68 g/cm3 on the average. Key words: coal kiln, Brdy, Black carbon, Elementary soil area
34

Human Health Risk Characterization of Petroleum Coke Calcining Facility Emissions

Singh, Davinderjit 05 April 2016 (has links)
Calcined coke is a high quality carbon material produced by calcining green petroleum coke. Calcining is the process of heating green petroleum coke in a kiln to remove excess moisture, extract all remaining hydrocarbons, and modify the crystalline structure of the coke into a denser, electrically conductive product. The final product, calcined coke, is primarily used to make carbon anodes for the aluminum industry and recarburizing agent for industries such as the steel industry. If not appropriately controlled, the calcining process could lead to excess production of particulate emissions from either handling or storing of raw coke, or from the stack emissions during the production of calcined coke. Though calcined coke has shown low hazard potential in human populations due to low volatile content, there remains some public health concern regarding the emissions from these facilities. This study is designed to evaluate the emissions of petroleum coke calcining facility and assess the public health concern from the processes engaged in the handling and storage of green coke as well as from the calcining process. The ambient air levels were measured from a calcining facility and compared with the standards promulgated by USEPA. The results showed that pollutant contribution from the facility, measured by monitoring carbon fraction of the emissions, was de-minimis. The current research also studied whether the exposure levels and health risks specified in various epidemiological studies correlate with the standards promulgated by USEPA to protect public health from petrochemical emissions.
35

Single-particle characterisation of black carbon in urban and biomass burning plumes and impacts on optical properties

Taylor, Jonathan William January 2013 (has links)
Black carbon (BC) is the light-absorbing component of soot, a combustion-generated aerosol that warms the climate by absorbing solar radiation. Its impacts on climate depend on its microphysical properties, which are modified by atmospheric processes including condensation, coagulation and wet removal. State of the art climate models consider soot in a concentric core/shell configuration, with a BC core coated by nonrefractory material such as organics or sulphate. Within this model, thicker coatings enhance visible light absorption, but also wet removal efficiency, and these have opposing effects on the total amount of light absorbed over BC’s lifetime. How well the core/shell model can calculate Mass Absorption Coefficient (MAC, the ratio of absorption to BC mass) is uncertain, as real soot forms more complex (often fractal) shapes, and detailed optical models using these morphologies predict the core/shell model may under- or over-estimate MAC depending on the precise properties of the particles. Few reliable measurements of variations in ambient MAC are available, as most older measurement techniques suffer from systematic uncertainties. In this work, a Single Particle Soot Photometer (SP2) and PhotoAcoustic Soot Spectrometer (PASS) were used to measure BC mass concentration and absorption, and these instruments do not suffer from such uncertainties. The SP2 was also used to report core size and coating thickness distributions that are required to test state of the art climate models. Firstly, a method was developed to minimise bias in the measured coating thicknesses related to the limited detection range of the SP2. The sensitivity of this technique to the assumed density and refractive index of the BC core was also explored, and the most appropriate parameters to use with ambient measurements were determined. Core and shell distributions were measured in Pasadena, California under a range of different photochemical ages. These were then used to calculate MAC, which was compared to that measured using the SP2 and PASS. The measured and modelled MAC agreed within 10% at 532 nm, though this was dependent on the assumed refractive index of the BC core. Overall MAC increased by 15 –25% in around one third of a day of photochemical ageing. This is quite modest compared to some climate models, but not compared to the previous best estimate, which predicted MAC may increase by a factor of ~1.5 over BC’s lifetime. Core and coating distributions were also measured in Canadian boreal biomass burning plumes. A case study was presented comparing the properties of BC in three plumes, one of which had passed through a precipitating cloud. It was demonstrated that larger and more coated BC-containing particles were removed more efficiently, in agreement with previous thermodynamic theory. By calculating MAC using the measured core/shell distributions and comparing to measured scattering, it was demonstrated that the MAC and single-scattering albedo in the plumes were likely not significantly affected by the wet removal, as greater differences were observed between the two plumes not affected by precipitation.
36

Black Carbon Aerosol in the Arctic: Ageing, Transport and Radiative Effects

Schacht, Jacob 15 September 2021 (has links)
Der anthropogene Klimaeinfluss hat zu global steigenden Temperaturen geführt. In der sich verändernden Arktis ist diese Erwärmung im Vergleich zum globalen Mittel verstärkt. Schwarzer Kohlenstoff (Black Carbon, BC) ist ein Aerosoltyp, der von besonderem Interesse ist, da er die Sonnenstrahlung besonders effizient absorbiert und dadurch zur Erwärmung der Atmosphäre beiträgt. BC entsteht bei unvollständiger Verbrennung fossiler Brennstoffe und bei Vegetationsbränden. Dies beinhaltet fossile Brennstoffe und Biomasse, etwa bei Vegetationsbränden. Ziel dieser Arbeit ist die Untersuchung der Quellen und des Transports von BC in die Arktis mittels globaler Modellierung und eine aktuelle Abschätzung dessen Wirkung auf den Strahlungshaushalt der Arktis. Hierzu wird das globale Aerosol-Klimamodell ECHAM-HAM verwendet. Eine umfassende Evaluierung des Models unter Verwendung von Beobachtungen der BC-Konzentrationen in der Arktis zeigt, dass BC vom Modell im allgemeinen realistisch reproduziert, in der oberen Troposphäre der Arktis jedoch überschätzt wird. Die häufigsten Unsicherheiten globaler Aerosol-Klimamodelle werden mit Sensitivitätsstudien angegangen: Der Unsicherheitsbereich der aus Annahmen über die BC-Quellen resultiert, wird durch eine Gegenüberstellung verschiedener Emmisionskonfigurationen quantifiziert. Zusätzlich werden die Unsicherheiten aufgrund der Parametrisierung der Nassdeposition abgeschätzt. Tagesaktuelle, satellitengestützte Emissionen von Vegetationsbränden sind entscheidend um die vertikale Verteilung von arktischem BC zu reproduzieren. Außerdem ermöglichen diese Emissionsdaten bessere zeitliche Korrelationen zwischen Beobachtungen und Modell. Eine neue Modellkonfiguration mit langsamerer Alterung und effizienterer Auswaschung von Aerosolen in Wolken führt zu einer realistischeren BC-Verteilung in der oberen arktischen Troposphäre. Der direkte Strahlungseffekt (DRE) des atmosphärischen BC in der Arktis >60°N beläuft sich auf einen Nettoenergiegewinn (solar und thermisch) am Oberrand der Atmosphäre (TOA) von +0,31 Watt pro Quadratmeter im Mittel der Jahre 2007 bis 2018, der des Schnee-Albedo-Effekts von BC auf einen Gewinn von +0,12 Watt pro Quadratmeter. Der effektive Strahlungseinfluss von BC auf die Arktis am TOA (der direkte Effekte und Aerosol-Wolken-Wechselwirkungen einschließt) wird im langjährigen Mittel auf -0,2 Watt pro Quadratmeter geschätzt. Diese Wechselwirkungen sind jedoch höchst unsicher. Verbesserte Emissionsannahmen erhöhen die modellierte arktische BC-Belastung um 25%, während sie durch die optimierte Aerosolmikrophysik und Nassdeposition um 10% verringert wird. Allerdings wirken sich beide Unsicherheitsfaktoren auf den DRE mit 22% bis 24% etwa gleichermaßen stark aus, dies zeigt die Wichtigkeit einer genauen Beschreibung der vertikalen Verteilung von BC im Modell. Diese Arbeit ermöglicht somit eine vollständigere Bewertung des DRE von BC in der Arktis. Neu entwickelte Modellerweiterungen und die angewandten Methoden bilden eine Grundlage für weitere Aerosol-Klima-Forschung auch außerhalb der Arktis. / The anthropogenic impact on climate has led to rising global temperatures. This warming is enhanced in the changing Arctic compared to the global mean. Black carbon (BC) is an aerosol type of particular interest, because it efficiently absorbs solar radiation and thus contributes to the atmospheric warming. BC is released into the atmosphere through incomplete combustion of fossil fuels and biomass including wildfires. The objective of this work is to investigate the sources and transport of BC to the Arctic using global modelling and to provide an up-to-date estimate of its effect on the radiation budget of the Arctic. For this purpose the global aerosol-climate model ECHAM-HAM is used. A comprehensive evaluation of the model using ground-based and airborne observations of BC concentrations in the Arctic shows that it is mostly able to realistically reproduce the observations, but produces an overestimation in the upper Arctic troposphere. The typical uncertainties of current aerosol-climate models are addressed with sensitivity studies: The range of uncertainty in the distribution and radiative effects of BC aerosol due to the assumptions on BC sources is quantified by comparing different emission setups. In addition, the uncertainties related to the wet deposition parametrisation are estimated. It is found that daily, satellite-based biomass combustion emissions are crucial for the reproduction of the vertical distribution of Arctic BC mass concentrations. Moreover, these emission data allow better temporal correlation between observations at Arctic stations and model. A new model configuration, developed in this study, with slower ageing and more efficient scavenging of aerosol in clouds leads to a more realistic BC distribution in the upper Arctic troposphere. The DRE of atmospheric BC in the Arctic (>60°N) amounts to a net energy gain (solar and thermal) at the TOA of +0.31 watt per square meter on average over the years 2007 to 2018, that of the BC-in-snow albedo effect to a gain of +0.12 watt per square meter. The effective radiative impact (direct effects plus rapid adjustments and aerosol-cloud interactions) of BC on the Arctic at top of the atmosphere (TOA) is estimated at -0.2 watt per square meter on the multi-year average. However, the aerosol-cloud radiation interactions are highly uncertain. Improved emission assumptions increase the modelled Arctic BC burden by 25%, while the optimised aerosol microphysics and wet deposition decrease it by 10%. However, both uncertainty factors affect the direct radiative effect (DRE) with 22% to 24% approximately equally, which shows the importance of an accurate description of the vertical distribution of BC in the model. This work thus allows a more complete assessment of the DRE of BC in the Arctic. The newly developed model extensions and methods applied provide a basis for further aerosol-climate research in the Arctic and elsewhere.
37

Evaluation and Improvement of Particle Number/Mass Size Distribution Modelling in WRF-Chem over Europe

CHEN, YING 19 July 2017 (has links)
Atmospheric aerosol particles play an important role in global climate change, via direct and indirect radiative forcing. Elemental carbon (EC) and nitrate are important contributors to anthropogenic aerosol radiative forcing over Europe, since they strongly absorb and/or scatter solar radiation, respectively. However, the evaluation of their climate effects remains highly uncertain. Improvements on the simulation of particle number/mass size distribution (PSD) in modelling will help us to refine model assessments of climate change. The simulations were performed over Europe with a fully online-coupled regional air quality model (WRF-Chem) for the time period of September 10-20th, 2013. Measurements in the HOPE-Melpitz campaign and other datasets in Europe were adopted to evaluate the model uncertainties. The meteorological conditions were well reproduced by the simulations. However, a remarkable overestimation of coarse mode PSD was found in the simulations. The overestimation was mainly contributed by EC, sodium nitrate and sea salt (SSA), stemming from the inadequate emission of EC and SSA. The EC inventory overestimates EC point sources in Germany and the fractions of coarse mode EC emissions in Eastern Europe and Russia. Allocating too much EC emission into the coarse mode could shorten EC lifetime and reduce its long-range transport, thus partly (~20-40%) explaining the underestimation of EC in Germany, when air masses came from eastern direction in previous studies. Furthermore, WRF-Chem overestimated coarse mode SSA mass concentrations by factors of about 8-20 over northwestern and central Europe in this study, due to the shortcoming of its emission scheme. This could facilitate the coarse mode sodium nitrate formation and lead to ~140% overestimation of coarse mode nitrate. Under such circumstances, nitric acid was exhausted, and fine mode ammonium nitrate formation was inhibited. The overestimated SSA shaped the PSD of nitrate towards larger sizes, which might influence the optical properties, lifetime and climate effect of nitrate accordingly. A transport mechanism would broaden the influence of SSA on nitrate PSD to central Europe, where a considerable amount of nitrate precursors and ammonium nitrate is present.:Table of Contents List of Figures List of Tables Abbreviations 1. Introduction 1.1 Particle size distribution 1.2 Elemental carbon particle size distribution simulation 1.3 Chemical pathways for particulate nitrate 1.4 Influence of sea salt on nitrate particle mass size distribution 1.5 Objectives 2. Methodology 2.1. WRF-Chem model 2.1.1. General description 2.1.2. Model configuration 2.1.3 Anthropogenic source emissions 2.1.4 Natural source emissions 2.2 HOPE-Melpitz campaign 2.3 GUAN network over Germany 2.4 Other datasets 3. Results and Discussion 3.1 First publication 3.1.1 Evaluation of the size segregation of elemental carbon (EC) emission in Europe: influence on the simulation of EC long-range transportation 3.1.2 Supporting information 3.2 Second publication 3.2.1 Sea salt emission, transport and influence on size-segregated nitrate simulation: a case study in northwestern Europe by WRF-Chem 3.2.2 Supporting information 4. Summary and Conclusions 5. Outlook Appendix A Bibliography Acknowledgements
38

Ein erster Vergleich der optischen Eigenschaften von Partikeln aus Laborfeuern und Modellrechnungen

Hungershöfer, Katja, Trautmann, Thomas, Trentmann, Jörg 27 January 2017 (has links)
Durch die Verbrennung von Biomasse werden Partikel freigesetzt, die u.a. schwarzen Kohlenstoff enthalten. Dieser ist wesentlich für die Absorption der solaren Strahlung in der Atmosphäre verantwortlich. Um den Effekt der emmitierten Partikel auf den Strahlungshaushalt quantifizieren zu können, ist die Kenntnis der physikalischen und chemischen Eigenschaften dieser Partikel nötig. Diese sind aber nur zum Teil bekannt. Dieser Bericht beschreibt eine Methode, die optischen Eigenschaften solcher Partikel unter Verwendung bestimmter Annahmen zu berechnen. Auÿerdem wird ein erster Vergleich zwischen berechneten Größen und Messungen aus Laborfeuern durchgeführt. / Biomass burning is an important source for particles containing black carbon, which is known as a strong light absorbing substance. To quantify the effect of such emitted particles on the radiation budget, the knowledge of their physical and chemical properties is necessary. Until now these properties are only partly known. In the following we describe a possibility of calculating the optical properties of such particles using certain simplifications. Also a first comparison between the calculated values and measurements from lab experiments is shown.
39

Traffic-Related Air Pollutants: Measurement, Modeling and Respiratory Health Effects

Isiugo, Kelechi I. 18 October 2018 (has links)
No description available.
40

Quantitative Analysis of Major Factors Affecting Black Carbon Transport and Concentrations in the Unique Atmospheric Structures of Urban Environment

Liang, Marissa Shuang 18 September 2014 (has links)
No description available.

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