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Author: Bryan Edward Cummings Publisher: ISBN: Category : Aerosols Languages : en Pages : 310
Book Description
Within residential buildings, organic aerosols (OA) often constitute the majority of particulate matter (PM) pollution, which is known to cause adverse cardiovascular and respiratory conditions. OA is composed of thousands of unique organic compounds, many of which are susceptible to partitioning between the aerosol and the gas phase. Until relatively recently, indoor air pollution models have largely neglected OA thermodynamic considerations, although certain organic thermodynamics modeling tools have been used with narrow applications to indoor PM studies over the past decade. Most of these cases have investigated particular processes, such as secondary organic aerosol (SOA) formation indoors or the repartitioning of outdoor OA. The need for the development of a comprehensive indoor OA thermodynamic model motivated the work done for this dissertation. Organic aerosol thermodynamics was modeled by the Indoor Model of Aerosols, Gases, Emissions, and Surfaces (IMAGES) using the volatility basis set (VBS). Explicitly representing indoor OA volatility allowed for errors associated with baseline, traditional particle models to be quantified across various model types and domains. For instance, traditional estimates of indoor particle emission rates for activities such as cooking may yield erroneous concentration predictions when used in other models. In such cases, error is driven by differences between model and experimental building conditions. Such errors were found to reach up to ~80% for typical stir-fry activities, associated with a magnitude of ~15-20 (microgram)/m3 depending on the particular emission strength. Epidemiological models that seek to predict indoor exposure to ambient pollution also have traditionally neglected volatility considerations. Such models fail to account for repartitioning driven by temperature and mass-loading gradients between the indoors and outdoors, leading to errors up to ~60% for total ambient PM, or about 3 (microgram)/m3 in the urban U.S. simulation domain that was considered. The two-dimensional volatility basis set (2D-VBS) was also incorporated into the underlying IMAGES model framework, representing its first known application to indoor air studies. Using the 2D-VBS to account for oxidation state in addition to volatility allowed OA aging transformations and water uptake to be modeled in addition to gas-to-particle partitioning. Simulation results showed that aging reactions are not likely to affect indoor OA composition and character from a day-averaged perspective, but may enhance peak OA concentrations under certain SOA-forming conditions on the order of ~10 (microgram)/m3. Also predicting the indoor humidity and aerosol water content in typical U.S. residences demonstrated that OA likely exists in a semisolid phase state indoors. Slow molecular diffusion within such particles challenges the implicit assumption often held by tradition indoor OA studies: that equilibrium thermodynamics holds, and that particles are typically liquid and well-mixed. A kinetic partitioning model of indoor organics was developed to more accurately represent the partitioning of material into and out of semisolid or glassy aerosols. This model was applied to a simulation of ambient aerosols that are transported into buildings and experience a temperature gradient that affects its effective volatility. Simulation results suggested that low diffusion inhibits repartitioning to at least some extent in the majority of simulated cases, representing residences in each of the 16 U.S. climate zones. Condensation may occur at equilibrium mostly in the southeastern U.S. in the summertime, where a hot and humid climate leads to a high indoor RH and therefore an indoor OA population in a liquid phase state. More northern locations along the east coast are typically associated with a drier indoor environment as the outdoor climate cools. In these cases, evaporation is often partially prohibited or fully prohibited. Dry climate zones from Arizona to Montana are more likely to experience limited or prohibited partitioning on hot outdoor days. And west coast marine climate zones are more likely to experience partial or equilibrium partitioning even in cooler regions.
Author: Bryan Edward Cummings Publisher: ISBN: Category : Aerosols Languages : en Pages : 310
Book Description
Within residential buildings, organic aerosols (OA) often constitute the majority of particulate matter (PM) pollution, which is known to cause adverse cardiovascular and respiratory conditions. OA is composed of thousands of unique organic compounds, many of which are susceptible to partitioning between the aerosol and the gas phase. Until relatively recently, indoor air pollution models have largely neglected OA thermodynamic considerations, although certain organic thermodynamics modeling tools have been used with narrow applications to indoor PM studies over the past decade. Most of these cases have investigated particular processes, such as secondary organic aerosol (SOA) formation indoors or the repartitioning of outdoor OA. The need for the development of a comprehensive indoor OA thermodynamic model motivated the work done for this dissertation. Organic aerosol thermodynamics was modeled by the Indoor Model of Aerosols, Gases, Emissions, and Surfaces (IMAGES) using the volatility basis set (VBS). Explicitly representing indoor OA volatility allowed for errors associated with baseline, traditional particle models to be quantified across various model types and domains. For instance, traditional estimates of indoor particle emission rates for activities such as cooking may yield erroneous concentration predictions when used in other models. In such cases, error is driven by differences between model and experimental building conditions. Such errors were found to reach up to ~80% for typical stir-fry activities, associated with a magnitude of ~15-20 (microgram)/m3 depending on the particular emission strength. Epidemiological models that seek to predict indoor exposure to ambient pollution also have traditionally neglected volatility considerations. Such models fail to account for repartitioning driven by temperature and mass-loading gradients between the indoors and outdoors, leading to errors up to ~60% for total ambient PM, or about 3 (microgram)/m3 in the urban U.S. simulation domain that was considered. The two-dimensional volatility basis set (2D-VBS) was also incorporated into the underlying IMAGES model framework, representing its first known application to indoor air studies. Using the 2D-VBS to account for oxidation state in addition to volatility allowed OA aging transformations and water uptake to be modeled in addition to gas-to-particle partitioning. Simulation results showed that aging reactions are not likely to affect indoor OA composition and character from a day-averaged perspective, but may enhance peak OA concentrations under certain SOA-forming conditions on the order of ~10 (microgram)/m3. Also predicting the indoor humidity and aerosol water content in typical U.S. residences demonstrated that OA likely exists in a semisolid phase state indoors. Slow molecular diffusion within such particles challenges the implicit assumption often held by tradition indoor OA studies: that equilibrium thermodynamics holds, and that particles are typically liquid and well-mixed. A kinetic partitioning model of indoor organics was developed to more accurately represent the partitioning of material into and out of semisolid or glassy aerosols. This model was applied to a simulation of ambient aerosols that are transported into buildings and experience a temperature gradient that affects its effective volatility. Simulation results suggested that low diffusion inhibits repartitioning to at least some extent in the majority of simulated cases, representing residences in each of the 16 U.S. climate zones. Condensation may occur at equilibrium mostly in the southeastern U.S. in the summertime, where a hot and humid climate leads to a high indoor RH and therefore an indoor OA population in a liquid phase state. More northern locations along the east coast are typically associated with a drier indoor environment as the outdoor climate cools. In these cases, evaporation is often partially prohibited or fully prohibited. Dry climate zones from Arizona to Montana are more likely to experience limited or prohibited partitioning on hot outdoor days. And west coast marine climate zones are more likely to experience partial or equilibrium partitioning even in cooler regions.
Author: Chunyi Wang Publisher: ISBN: Category : Aerosols Languages : en Pages : 372
Book Description
People in developed countries spend about 90% of their time indoors, so controlling in-door air quality (IAQ) is of primary importance for not harming public health. Airborne particu-late matter (PM) is one of the most problematic pollutants indoors, since exposure to particles with aerodynamic diameters smaller than 2.5 Îơm (i.e, PM2.5) is associated with respiratory dis-eases, as well as morbidity and mortality outcomes. Organic aerosol components, so called organic aerosol (OA), generally comprise the ma-jor portion of indoor PM, owing to its large indoor emission. One important component of OA indoors is secondary organic aerosol (SOA), which are condensed phase particles composed of semi- and low-volatility compounds. Most research has focused on SOA generated by terpene ozonolysis occurring in the gas phase. This work, however, explores a lesser researched for-mation mechanism, which is the possibility of airborne SOA generated by ozone surface reac-tions with sorbed squalene (C30H50), which is a nonvolatile constituent of skin oil. As such, thirteen steady state chamber experiments were performed to measure the SOA formation en-tirely initiated by ozone reactions with squalene sorbed to glass at two RH conditions of 21% and 51%, in the absence of seed particles. SOA was initiated from these surface reactions, and all experiments but one exhibited nucleation and mass formation. Mass formation increased with ozone concentration at RH = 51% while nucleation was more obvious at RH = 21%. Additionally, most indoor OA, either emitted or generated (i.e., not only SOA), is at composed of semivolatile compounds (SVOCs) in a state of dynamic equilibrium between gas and particle phases. Filters might have a reduced efficiency on removing these kinds of particles since they coexist in gas and condensed aerosol phases. The preferential filtration of particle phase material of the OA system could disrupt the equilibrium, and the removed aerosols might be enhanced by desorption from surfaces and repartitioning from gas phase. To explore this phenomenon, three types of particles, including non-volatile ammonium sulfate ((NH4)2SO4) aerosol, incense aerosol (which might be partly semi-volatile), and SOA derived from ozone + d-limonene reactions (the majority of which are SVOCs), were characterized and compared in terms of their effective removal by a portable air cleaner. For this comparison, the metric of the Clean Air Delivery Rate, CADR (m3/h), was used, which is the volumetric flow of pollutant-free air produced by an air cleaner. Results demonstrated that the lowest effective CADR was for SOA, followed by the incense, and then the ammonium sulfate particles, indicating a repar-titioning processes reduced the filter efficiency. Then a model based on the principles of desorp-tion and repartition process was developed, to quantify the reduced CADR as a function of par-ticle concentration and distribution, in terms of parameter ATSP, which is the ratio of particle surface area to mass. Finally, the influence of the above two parameters on amount of CADR reduction was discussed. Using some details gleaned from the above two experimental studies, a thermodynamic equilibrium model was developed using the volatile basis set (VBS), to predict indoor organic aerosol concentrations and behavior. The model outcomes are the total organic mass indoors (gas + condensed phase), and the fraction of it that partitions to the aerosol phase, including that existing as SOA formed by ozone + d-limonene reactions. With this model, the total OA concentration was simulated at key locations in an indoor environment, such as in the occupied space and different positions in a building mechanical system. The impacts of different condi-tions were compared, including commercial against residential buildings, surface against gas reactions, and winter against summer, within a Monte Carlo framework. Indoor OA concentra-tion indoors were higher when reactions were involved, and gas phase reactions had much more influence on SOA than surface reactions. Finally, the result dataset was used to evaluate the influence of key factors on the indoor OA concentrations, using multiple linear regression sen-sitivity methods. The most important factor that enhanced indoor particles was d-limonene emission rate with average SRC of 0.73, while the negative related factors were filtration effi-ciency with SRC of -0.33 for commercial and surface deposition rate with SRC of -0.22 for resi-dential buildings. Beyond the three SOA studies discussed above, humidifiers used indoors might be strong PM emitters. So, as a supplementary piece, this work also investigated the influence of three humidifier types (ultrasonic, evaporative, and steam humidifiers), and water type used (tap water, de-ionized (DI) water or distilled water), on indoor aerosol number/mass concentra-tions by performing 16 experiments. Particle size distribution during emission periods and size-resolved emission rates were explored to compare the emission ability of humidifiers. Two lung deposition models were also applied to simulate the deposition percentage of particles breathed in on three lung regions (HA, TB, and AL), and total percentage on varying age groups. Results showed that two year-old group was most vulnerable, with number deposition fractions of 0.36, compared with 0.25 for adults. Furthermore, roughly 70% of the total emitted particles pene-trates into the AL region of the lung.
Author: Ottmar Edenhofer Publisher: Cambridge University Press ISBN: 9781107607101 Category : Science Languages : en Pages : 1088
Book Description
This Intergovernmental Panel on Climate Change Special Report (IPCC-SRREN) assesses the potential role of renewable energy in the mitigation of climate change. It covers the six most important renewable energy sources - bioenergy, solar, geothermal, hydropower, ocean and wind energy - as well as their integration into present and future energy systems. It considers the environmental and social consequences associated with the deployment of these technologies, and presents strategies to overcome technical as well as non-technical obstacles to their application and diffusion. SRREN brings a broad spectrum of technology-specific experts together with scientists studying energy systems as a whole. Prepared following strict IPCC procedures, it presents an impartial assessment of the current state of knowledge: it is policy relevant but not policy prescriptive. SRREN is an invaluable assessment of the potential role of renewable energy for the mitigation of climate change for policymakers, the private sector, and academic researchers.
Author: Constantin Andronache Publisher: Elsevier ISBN: 012810550X Category : Science Languages : en Pages : 302
Book Description
Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling
Author: Daniel J. Jacob Publisher: Princeton University Press ISBN: 0691001855 Category : Nature Languages : en Pages : 280
Book Description
Atmospheric chemistry is one of the fastest growing fields in the earth sciences. Until now, however, there has been no book designed to help students capture the essence of the subject in a brief course of study. Daniel Jacob, a leading researcher and teacher in the field, addresses that problem by presenting the first textbook on atmospheric chemistry for a one-semester course. Based on the approach he developed in his class at Harvard, Jacob introduces students in clear and concise chapters to the fundamentals as well as the latest ideas and findings in the field. Jacob's aim is to show students how to use basic principles of physics and chemistry to describe a complex system such as the atmosphere. He also seeks to give students an overview of the current state of research and the work that led to this point. Jacob begins with atmospheric structure, design of simple models, atmospheric transport, and the continuity equation, and continues with geochemical cycles, the greenhouse effect, aerosols, stratospheric ozone, the oxidizing power of the atmosphere, smog, and acid rain. Each chapter concludes with a problem set based on recent scientific literature. This is a novel approach to problem-set writing, and one that successfully introduces students to the prevailing issues. This is a major contribution to a growing area of study and will be welcomed enthusiastically by students and teachers alike.
Author: David S. Ensor Publisher: RTI Press ISBN: 1934831018 Category : Science Languages : en Pages : 584
Book Description
Aerosol Science and Technology: History and Reviews captures an exciting slice of history in the evolution of aerosol science. It presents in-depth biographies of four leading international aerosol researchers and highlights pivotal research institutions in New York, Minnesota, and Austria. One collection of chapters reflects on the legacy of the Pasadena smog experiment, while another presents a fascinating overview of military applications and nuclear aerosols. Finally, prominent researchers offer detailed reviews of aerosol measurement, processes, experiments, and technology that changed the face of aerosol science. This volume is the third in a series and is supported by the American Association for Aerosol Research (AAAR) History Working Group, whose goal is to produce archival books from its symposiums on the history of aerosol science to ensure a lasting record. It is based on papers presented at the Third Aerosol History Symposium on September 8 and 9, 2006, in St. Paul, Minnesota, USA.
Author: Publisher: ISBN: Category : Languages : en Pages : 64
Book Description
The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.
Author: Olivier Boucher Publisher: Springer ISBN: 9401796491 Category : Science Languages : en Pages : 322
Book Description
This textbook aims to be a one stop shop for those interested in aerosols and their impact on the climate system. It starts with some fundamentals on atmospheric aerosols, atmospheric radiation and cloud physics, then goes into techniques used for in-situ and remote sensing measurements of aerosols, data assimilation, and discusses aerosol-radiation interactions, aerosol-cloud interactions and the multiple impacts of aerosols on the climate system. The book aims to engage those interested in aerosols and their impacts on the climate system: graduate and PhD students, but also post-doctorate fellows who are new to the field or would like to broaden their knowledge. The book includes exercises at the end of most chapters. Atmospheric aerosols are small (microscopic) particles in suspension in the atmosphere, which play multiple roles in the climate system. They interact with the energy budget through scattering and absorption of solar and terrestrial radiation. They also serve as cloud condensation and ice nuclei with impacts on the formation, evolution and properties of clouds. Finally aerosols also interact with some biogeochemical cycles. Anthropogenic emissions of aerosols are responsible for a cooling effect that has masked part of the warming due to the increased greenhouse effect since pre-industrial time. Natural aerosols also respond to climate changes as shown by observations of past climates and modelling of the future climate.
Author: Bryan Edward Cummings
Author: Bryan Edward Cummings
Author: Chinghang Tong
Author: Chunyi Wang
Author: Ottmar Edenhofer
Author: Constantin Andronache
Author: Daniel J. Jacob
Author: David S. Ensor
Author: 
Author: John Monteith
Author: Olivier Boucher