The CCRUSH Study: Characterization of Coarse and Fine Particulate Matter in Northeastern Colorado

Clements, Nicholas Steven

Graduate Thesis Or Dissertation

The CCRUSH Study: Characterization of Coarse and Fine Particulate Matter in Northeastern Colorado Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/gq67jr366

Abstract

Particulate matter in the troposphere adversely impacts human health when inhaled and alters climate through cloud formation processes and by absorbing/scattering light. Particles smaller than 2.5 μm in diameter (fine particulate matter; PM_10-2.5), are typically emitted from combustion-related sources and can form and grow through secondary processing in the atmosphere. Coarse particles (PM_10-2.5), ranging 2.5 to 10 μm, are typically generated through abrasive processes, such as erosion of road surfaces, entrained via resuspension, and settle quickly out of the atmosphere due to their large size. After deciding against regulating PM_10-2.5 in 2006 citing, among other reasons, mixed results from epidemiological studies of the pollutant and lack of knowledge on health impacts in rural areas, the United States Environmental Protection Agency (US EPA) funded a series of studies that investigated the ambient composition, toxicology, and epidemiology of PM_10-2.5. One such study, The Colorado Coarse Rural-Urban Sources and Health (CCRUSH) study, aimed to characterize the composition, sources, and health effects of PM_10-2.5 in semi-arid northeastern Colorado and consisted of two field campaigns and an epidemiological study. Summarized here are the results from the two field campaigns, the first of which included over three years of continuous PM_10-2.5 and PM_2.5 mass concentration monitoring at multiple sites in urban-Denver and rural-Greeley, Colorado. This data set was used to characterize the spatiotemporal variability of PM_10-2.5 and PM_2.5. During the second year of continuous monitoring, PM_10-2.5 and PM_2.5 filter samples were collected for compositional analyses that included: elemental composition, bulk elemental and organic carbon concentrations, water-soluble organic carbon concentrations, UV-vis absorbance, fluorescence spectroscopy, and endotoxin content. Elemental composition was used to understand enrichment of trace elements in atmospheric particles and to identify sources via positive matrix factorization (PMF). The organic fraction of both particulate size ranges was explored with a variety of bulk characterization techniques commonly utilized in analysis of soil and aquatic natural organic matter. To date, the CCRUSH study is one of the largest research efforts devoted to understanding PM_10-2.5 and provides the US EPA with vital information that will be used in future policy making decisions regarding the regulation of this pollutant.

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