AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Ultrafine Particles Size Distribution, Single Aerosol Particle Morphology and Chemical Composition in Urban Air
CECILIA LEONI, Jan Hovorka, Miroslav Klán, Jan Bendl, Sona Marvanova, Charles University in Prague
Abstract Number: 295 Working Group: Single Aerosol Particle Studies - Techniques and Instrumentation
Abstract Atmospheric ultrafine aerosol particles (UFP) were collected in Kladno, Czech Republic, in February 2016, using copper grids for transmission electron microscopy (TEM) placed on the back-up filter of a 3DRUM impactor. Concurrently, five-minute integration time data of particle number size distributions, concentration (PNC), gaseous pollutants and meteorological parameters were also registered. The vertical profile of temperature and humidity up to 300 m was measured with a tethered balloon.
The measurements of the mixing layer height revealed frequent formation of temperature inversion layer up to 50 m. With inversion conditions and calm air (wind speed <1m.s$^(-1)) PNC rose to 2∙10$^4 #cm $^(-3), with a maximum of 4∙10$^4 #cm$^(-3), with a peak in the ultrafine size range, at 100 nm. UFP peaks occurred simultaneously with peaks of CO and SO$_2 and PM$_(10) indicating wood and coal burning for home heating. New particles formation events with peaks at 15 nm were observed in two clear days (06 and 14.02), in the early afternoon, but not remarkable particle growth was recognized.
Several types of individual particles were observed using TEM: soot-like agglomerates and aggregates with complex morphology, composed by nanospheres with diameter between 5 and 50 nm; fly ash particles; presumably individual tar-ball particles with perfect spherical shape and diameter around 100-500 nm; and ammonium sulphate particles.
No significant shape difference was observed between the aggregates sampled during nucleation events and during air pollution events.
The next steps are: the chemical analysis of the single particles with electron probe microanalyzer with field emission gun (FEG-EPMA); PAHs analysis in the UFP.
The project is supported by the Czech Grant Agency (P503/12/G147).