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Atmospheric Impact of Biogenic Volatile Organic Compounds: Improving Measurement and Modeling Capabilities

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dc.contributor.authorPanji, Namrata Shanmukhen
dc.contributor.committeechairIsaacman-VanWertz, Gabrielen
dc.contributor.committeememberLittle, John C.en
dc.contributor.committeememberMarr, Linsey C.en
dc.contributor.committeememberForoutan, Hoseinen
dc.contributor.departmentCivil and Environmental Engineeringen
dc.date.accessioned2024-08-24T08:00:14Zen
dc.date.available2024-08-24T08:00:14Zen
dc.date.issued2024-08-23en
dc.description.abstractBiogenic volatile organic compounds (BVOCs) are naturally occurring organic compounds emitted by plants, trees, and ecosystems, exerting a profound influence on the Earth's atmosphere, air quality, climate, and ecosystem dynamics. This research project aims to advance our understanding of BVOC emissions and their implications through a comprehensive and multi-faceted investigation. We investigate the dynamics of BVOCs in the atmosphere through three key objectives. First, we introduce a novel enriching inlet that uses selective permeation to preconcentrate reactive organic gases in small sample flows for atmospheric gas sampling, enhancing the sensitivity and detection limits of analytical instruments. Enrichments between 4640% and 111% were measured for major reactive atmospheric gases at ultra low flow rates and roughly several hundred percent for ambient samples at moderately low flow rates. Second, we constrain light-dependency in BVOC emissions models by comparing modeled and long-term observed BVOC concentrations measured at a mid-canopy monitoring site in a southeastern US forest. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the Framework for 0-D Atmospheric Modeling (F0AM) were utilized to simulate emissions and chemical transformations, respectively to disentangle the time- and species-specificity of light dependency for various BVOC (α-pinene, camphene, and α-fenchene are completely light-independent and limonene, β-thujene, sabinene, and γ-terpinene are seasonally light-dependent). Finally, we examine these models deeper to investigate uncertainties and highlight current limitations due to variability in planetary boundary layer height (PBLH) datasets. We highlight the significance of simultaneous PBLH and BVOC measurements for improving the accuracy of BVOC concentration models. We show that a lack of co-located measurements is a large source of uncertainty in modeling BVOC concentrations. The successful completion of these objectives contributes to a better understanding of the complex interactions between BVOC emissions and atmospheric chemistry.en
dc.description.abstractgeneralBiogenic volatile organic compounds (BVOCs) are natural chemicals released by plants, trees, and ecosystems. They interact with combustion emissions such as those from vehicles (nitrous oxides or NOX species) in the presence of light to produce secondary pollutants such as ozone and particulate matter which significantly affect human health, Earth's atmosphere, air quality, climate, and ecosystems. This research aims to deepen our understanding of BVOC emissions and their effects through a detailed study of measurement and modeling techniques used to study BVOC. We accomplish this via three main goals. First, we introduce a new method to enhance the detection of reactive gases in small air samples, improving the sensitivity of currently available analytical instruments. This method showed significant improvements in detecting key atmospheric gases. Second, we examine how BVOC emissions depend on light by comparing models with long-term observations from a forest in the southeastern US. We used two models, Model of Emissions of Gases and Aerosols from Nature (MEGAN) and Framework for 0-D Atmospheric Modeling (F0AM), to simulate emissions and chemical changes, revealing that some BVOC emissions are completely light-independent processes, while others depend on the season. Finally, we examine these models deeper to investigate the uncertainties due to variability in planetary boundary layer height (PBLH) datasets (the layer of air closest to the Earth's surface where pollutants are concentrated). We show that a lack of BVOC and PBLH measurements made at the same location is a large source of uncertainty in modeling BVOC concentrations. Achieving these goals will enhance our understanding of the complex interactions between BVOC emissions and atmospheric chemistry.en
dc.description.degreeDoctor of Philosophyen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:41293en
dc.identifier.urihttps://hdl.handle.net/10919/121003en
dc.language.isoenen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectbiogenic volatile organic compoundsen
dc.subjectpreconcentrating inleten
dc.subjectemissions modelingen
dc.subjectlight dependent fractionen
dc.subjectplanetary boundary layer heighten
dc.titleAtmospheric Impact of Biogenic Volatile Organic Compounds: Improving Measurement and Modeling Capabilitiesen
dc.typeDissertationen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.nameDoctor of Philosophyen

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