Fine Bioaerosols in Outdoor Air - Characterization, Influence of Seasonal Variation and Chemical Co-pollutants in Urban and Rural Airsheds

bioaerosols;Public Health;Health Sciences;Environmental Health Sciences

Nathan, PearlXi, Chuanwu ;

University of Michigan

关键词: bioaerosols;    Public Health;    Health Sciences;    Environmental Health Sciences;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/145892/pnathan_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Particulate matter (PM) pollution has been studied in great depth with respect to its chemical composition. Outdoor air is made up of chemical as well as biological components. However, bioaerosols in PM2.5 (particles equal to or less than 2.5 micro-meters in aerodynamic diameter) have not been fully explored to understand their composition and interactions in different airsheds. This dissertation describes the findings of three studies investigating sampling methods, characterization and impact of environmental and chemical variables on fine bacterial bioaerosols in outdoor air. The first study developed and evaluated a sampling methodology to collect fine bioaerosols in outdoor air using gelatin membrane and black polycarbonate filters, to collect total fine bioaerosols present, both culturable and non-culturable. The analysis involved a thorough characterization of fine bioaerosols using culture based assays, pyrosequencing and epifluorescent microscopy techniques to characterize the species present and also to understand both the viable and non-viable components. Gelatin membrane filters were found to be better than polycarbonate filters at maintaining the viability of bacterial cells over the sampling and transportation times. GM filters were also found to be better than PC filters at collecting a larger number of total bacterial bioaerosols as well as a truer representation of the given ambient bacterial microbiome and better suited for quantitative characterization.The second study investigated the fine bacterial bioaerosols composition in urban (Dearborn, MI) and rural (Dexter, MI) airsheds in Michigan. The urban site is located downwind of several steel processing plants, meat-processing facilities and near a large municipal wastewater treatment facility. The rural site is located significantly upwind of any large anthropogenic point sources. Both airsheds were found to have similar overall bacterial concentrations. However, a significant difference was observed in the bacterial community composition within the urban airshed as compared to the rural airshed with greater bacterial diversity observed at the urban site. Bacterial families identified in both airsheds appear to be influenced by the possible emission sources within each local vicinity. The third study examined the role of seasonal variability, meteorological parameters and chemical co-pollutants on fine bacterial bioaerosol composition. Samples were collected in 25-min intervals each day over a two-week period each season from Summer 2013 until Summer 2014 to account for seasonal variability. Results indicate that bacterial compositions were influenced by changes in seasons. The differences due to changes in season were greater between the urban and rural airsheds in the winter, spring and summer seasons. Relative humidity, temperature, wind speed and ozone all appeared to have an influence on fine bacterial bioaerosol composition in outdoor air.Particulate air pollution is a critically important public health concern, not only the total mass concentration but the particle composition as well, including bioaerosols. With an increasing number of residential communities downwind of facilities that are potential sources of microbial loading, the findings of this research will be informative to public health at large.