The study presents the analysis of measurement results for the ambient mass concentrations of fine particulate matter (PM2.5), PM2.5-bound carbonaceous matter (OC, EC) and water-soluble ions (Cl–, NO3–, SO42–, Na+, NH4+, K+, Ca2+, Mg2+). The 24-h PM2.5 samples were collected in the heating and non-heating seasons at two regional background sites in Southern Poland in 2011–2013. The percentage of the secondary organic and inorganic matter in PM2.5 was calculated.
Over the whole measurement period, the mean PM2.5 concentration was 31.56 µg m–3 and 24.92 µg m–3 in Racibórz and Złoty Potok, respectively. Regardless of the season, the total carbon percentage in PM2.5 was comparable at both sites and amounted ~40%. There were no visible seasonal variations in the secondary organic carbon (SOC) share in PM2.5. The mean percentage of the primary organic carbon (POC) in PM2.5 was higher than the SOC percentage at both locations. The mean contribution of the water-soluble ions in the PM2.5 mass was lower than the TC percentage, with values 20.35% (Złoty Potok) and 33.56% (Racibórz). The total share of the secondary ions (SO42–, NO3– and NH4+) in PM2.5 was comparable in both measurement periods.
It was shown that PM2.5 at regional background sites in Southern Poland is significantly different than at similar stations across Europe. It is reflected by higher concentrations of PM2.5 and its main components and lower percentage of the secondary ions in the PM2.5 mass. The carbonaceous matter percentage in PM2.5 is higher than in other parts of Europe.