The size distribution of particulate matter in the aerosol of the Moravian-Silesian Region, Czech Republic

Abstract

The particle size distribution in the fraction PM10 was determined by the electric low-pressure impactor ELPI+. Particles were divided into 14 classes in the range from 17 nm to 10 mu m. The particle distribution was analysed during summer, autumn and winter periods of 2014 at the 10 sampling sites in the Moravian-Silesian Region, the Czech Republic. The highest particle concentrations were determined in the interval from 156 to 383 nm as well as in the wider interval up to 614 nm for all three seasons. More than 50% of the total particle amount occur in this interval except the locality Ostrava Radvanice, Ostrava Marianske Hory, Ostrava Poruba and Ostravice during the summer and Ostrava Marianske Hory during the transitional and winter season. During the summer, the distribution of the mass concentration of particles was very variable (bimodal for three localities, no significant peak for two localities, multimodal for four localities and unimodal for one locality). Seven in ten sampling sites has the bimodal distribution character of particle concentrations during transitional season, except for Ostrava-Poruba, Ostrava Marianske Hory and Trinec Oldrichovice. It was related to a resuspension of particles from soil or dust particles from transport. A second maximum is less distinctive and it occurs in the coarse fraction 2.39-4.0 mu m. Entirely different character of particle distribution was determined in winter season when sampling sites had unimodal character of particle distribution. The bimodal distribution character was found for the locality Frydek Mistek and atypical character of particle distribution was confirmed for the locality Ostrava Marianske Hory (without trend). The unimodal character of particle distribution with maximum in the range from 156 to 263 nm is related to the prevailing chemical character of particles belonging to secondary aerosols (mascagnite, sal ammoniac, boussingaultite etc.).