Elemental analysis of high time resolution PM2.5 samples collected in an urban background site (Metadata RADIATE TA Proposal 21002673-ST)

Proposal title "Elemental analysis of high time resolution PM2.5 samples collected in an urban background site". Measurements carried out at the external beam set-up for atmospheric aerosol analysis  of the INFN LABEC accelerator laboratory, from 15 till 19 May 2023. Hands-on mode.

Source apportionment (SA) studies are applied to quantify the effect of individual sources of air pollutant on the ambient concentration through receptor modelling. The classical approach in these studies is based upon the collections and chemical characterization of 24h samples. Even though this methodology has proven to be very effective, it cannot provide information on the diurnal patterns of source contributions due to its low time resolution. In addition, the database on city source apportionment is not well documented in numerous Eastern European cities.

The main objective of the experiment was to determine the elemental composition of particulate matter (PM) samples collected with high time resolution (2 hours) to characterize and identify the local and regional sources, and to compare their contribution to the local ambient pollution level in different seasons in Debrecen, Hungary. The city of Debrecen, with approximately 220,000 inhabitants, is situated in the eastern part of Hungary. It has a mixed-fired power plant, an airport and it is surrounded by agricultural areas. Based on previous studies, the main sources of pollution were identified in the city.<br>
Sixteen sampling campaigns including a COVID-19 lockdown period have been carried out since August, 2018. The sampling location in ATOMKI is an urban background site close to the downtown of Debrecen. For the sampling campaigns, a two-stage sequential Streaker sampler was used to study the quasi-hourly evolution of atmospheric aerosol concentration. The sampling device collected two different size fractions, the fine fraction (PM2.5) and the coarse fraction (PM10-2.5), separately with a time resolution of 2 h.

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The quantity of collected particulate matter in each sample is small and as a result very difficult to analyse using traditional chemical techniques. The PIXE technique is suitable for measuring this kind of filters. Siixteen PM2.5 streaker filters (each one composed by 74 aerosol “spots”), were analysed with an extracted proton beam of 2.7 MeV (energy on target), for a total of about 1200 aerosol 2h-samples. A set of elemental standards and an aerosol reference standard (NIST 2783) were analyzed as well for quality assurance purposes and to check the accuracy of quantitative results.