Urban Aerosols Of PM 2.5 And PM10 Variability Within A Middles Scale Of 5 Localities

Abstract:

This study evaluates the middle scale spatial/seasonal variability of PM2.5 and PM10 at five sampling localities. Statistical significant differences in PM values could be crucial for a representative placement of a measuring station at the locality.A set of 8 portable laser nephelometers DustTrak - DT (8520, TSI) was used to record 5 minute integrates of PM2.5 and PM10 consecutively for each size for 3 days at 5 localities. The localities were rural, urban, background and freeway and contrasted as far as the main aerosol sources are concerned. At each locality, inter-DT distances ranged from 30 - 500m, 80 – 220m, 70 – 150m, and 30m and total area covered 380 000 m$^2, in rural, urban, background and freeway locality, respectively. As expected, PM2.5 did not vary statistically significantly (alpha=0.05) among DT’s at all localities in both winter and summer with the exception of freeway, where high PM2.5 differences were recorded regardless season due to the proximity to highway as the strong source of fine aerosol fraction. Contrary to PM2.5, inter-DT PM10 values varied significantly at rural and freeway localities probably due to nearby fugitive aerosol sources. At urban and background localities inter-DT PM10 differences were not significant in both seasons. Winter PM concentrations were generally higher than summer ones at all the localities with exception of PM10 at freeway due to low air humidity during summer. Wilcoxon signed-ranks test for 2 dependent samples, together with meteorological data were used to evaluate a dynamic of PM2.5 and PM10 at each locality with respect to season.

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