Interactions Between Dust and Ecosystem, and Landscape at Multiple Scales

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dc.contributor.authorHuang, Xinyueen
dc.contributor.committeechairForoutan, Hoseinen
dc.contributor.committeememberSridhar, Venkataramana Raoen
dc.contributor.committeememberMarr, Linsey C.en
dc.contributor.committeememberIsaacman-VanWertz, Gabrielen
dc.contributor.departmentCivil and Environmental Engineeringen
dc.date.accessioned2024-09-06T08:00:28Zen
dc.date.available2024-09-06T08:00:28Zen
dc.date.issued2024-09-05en
dc.description.abstractAtmospheric dust is the largest contributor to global aerosols from land. Dust emissions rate and properties are influenced by meteorological conditions, parent soil, and landscape, and in turn, it affects impacts on climate, ecosystems, and human societies through various pathways. This dissertation aims to explore the coupled dynamics of dust particle emissions and their essential properties in relation to topography, ecosystem, and atmospheric conditions by integrating information across multiple scales. Specifically, three research projects are pursued. First, the modulation of dust emissions by non-photosynthetic vegetation (NPV) is evaluated by implementing a satellite-based total vegetation dataset, which includes NPV, into a regional atmospheric chemistry model. Simulations of the entire year 2016 over the conterminous United States demonstrate that NPV reduces dust emissions by 10-70% from most dust sources in the southwest, particularly in spring. Second, the relationship between topographic wind conditions (i.e., speed and direction with respect to surface slope) and dust particle size distribution is investigated using a decade's worth of dust reanalysis data covering North Africa. Findings indicate that the fraction of coarse dust in emissions increases with wind speed and slope, particularly under uphill winds, the latter highlighting the role of topography in enhancing vertical transport for larger particles. These positive correlations weaken during the afternoon and summer events, suggesting that turbulence associated with haboob events suspends coarse particles. Finally, a series of air samples collected in Tenerife, Spain is revisited for a detailed study on the associated dust plume characteristics, which would facilitate the understanding of how environmental factors during transport influence airborne microbial assemblages. Using back trajectory analysis and dust optical depth reanalysis data, air samples impacted by African dust are identified. Seasonal variations in trajectories and associated environmental conditions reveal highly variable trans-Atlantic airflows. Elevated altitudes, higher temperatures, and lower relative humidity (RH) along summer trajectories implied the presence of Saharan Air Layer, whereas the frequent occurrence of higher RH (> 40%) and light precipitation in spring indicate more deposition of dust and associated microbes during transport. Overall, this work highlights the importance of accurately representing of various environmental elements that interact with the dust cycle, such as vegetation and topographic winds, which improves our ability to predict and manage the impacts of dust as well as other components of the Earth system.en
dc.description.abstractgeneralDust particles can be lifted by strong winds from dry lands, and they are a major contributor to the amount of particles in the air. Suspended dust particles can alter temperatures and weather patterns, reduce visibility, and cause health problems. When settling back to land or oceans, they can carry nutrients and microbes that influence the growth of plants and animals. The movement and properties of dust are subject to various elements of the environment, spanning from microscopic scale to global scale. This dissertation aims to explore the interactions between dust and a few of these environmental elements that are not well understood. Specifically, we first provide information about brown vegetation, which was previously lacking, to a dust model, and find that the dust emissions in the southwestern United States is reduced by 10-70%, particularly in spring. Second, we examine how the changes of wind over slopes influence the size of dust particles in the air by analyzing data for 10 years that combine information from models and satellite observations. We find that faster winds and uphill slopes lead to more large dust particles in the atmosphere. The third study analyzes the pathways of air samples from Africa to Tenerife, Spain, to understand how the transport of dust might affect the types of bacteria that travel with it across the ocean. We find that the airflows from Africa to Tenerife vary greatly from case to case, and the environmental conditions, such as precipitation and relative humidity, varying significantly across seasons and during the dust travel. Overall, this dissertation provides a deeper understanding of the complex ways dust interacts with our world, offering insights that can help us manage its impacts on climate, ecosystems, and human society more effectively.en
dc.description.degreeDoctor of Philosophyen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:41341en
dc.identifier.urihttps://hdl.handle.net/10919/121083en
dc.language.isoenen
dc.publisherVirginia Techen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectdusten
dc.subjectemissionsen
dc.subjectsize distributionen
dc.subjectvegetationen
dc.subjecttopographyen
dc.subjectmicrobesen
dc.titleInteractions Between Dust and Ecosystem, and Landscape at Multiple Scalesen
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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