Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Particle size and time of the day influences on the morphology distributions of atmospheric fine particles at the Baltimore supersite
AbstractThe morphology of size-classified ambient particulate matter less than 2.5μm in aerodynamic diameter (PM2.5) was studied in samples collected at the USEPA supersite located in Baltimore, MD. Size classification was accomplished through the use of a low pressure impactor to produce samples with cut-off diameters of 0.10, 0.15, 0.55, and 2.0μm. Sampling was conducted in two campaigns during the fall of 2002, with separate sampling occurring during early morning, mid-day, late afternoon, and evening periods. Particles with cut-off diameters of 2μm were generally round in shape, with a border fractal dimension close to 1 based on the analysis of transmission electron microscope (TEM) images of collected samples. Particles with a cut-off diameter of 0.15μm had on average higher fractal dimensions than the other size classes considered, regardless of time of day associated with the sample. As expected, the time of the day influenced the shape of particle populations sampled. Particles collected during early morning were found to have higher fractal dimension than those collected at other sampling times. At night, particles presented mostly round shapes. This difference was particularly pronounced in particles with cut-off diameters of 0.15μm.
Particle size and time of the day influences on the morphology distributions of atmospheric fine particles at the Baltimore supersite
AbstractThe morphology of size-classified ambient particulate matter less than 2.5μm in aerodynamic diameter (PM2.5) was studied in samples collected at the USEPA supersite located in Baltimore, MD. Size classification was accomplished through the use of a low pressure impactor to produce samples with cut-off diameters of 0.10, 0.15, 0.55, and 2.0μm. Sampling was conducted in two campaigns during the fall of 2002, with separate sampling occurring during early morning, mid-day, late afternoon, and evening periods. Particles with cut-off diameters of 2μm were generally round in shape, with a border fractal dimension close to 1 based on the analysis of transmission electron microscope (TEM) images of collected samples. Particles with a cut-off diameter of 0.15μm had on average higher fractal dimensions than the other size classes considered, regardless of time of day associated with the sample. As expected, the time of the day influenced the shape of particle populations sampled. Particles collected during early morning were found to have higher fractal dimension than those collected at other sampling times. At night, particles presented mostly round shapes. This difference was particularly pronounced in particles with cut-off diameters of 0.15μm.
Particle size and time of the day influences on the morphology distributions of atmospheric fine particles at the Baltimore supersite
Mamani-Paco, Ruben M. (Autor:in) / Helble, Joseph J. (Autor:in)
Atmospheric Environment ; 41 ; 8021-8029
03.07.2007
9 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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