Chemical Compositions of PM2.5 at Two Non-Urban Sites from the Polluted Region in Europe

The study presents the analysis of measurement results for the ambient mass concentrations of fine particulate matter (PM_(2.5)), PM_(2.5)-bound carbonaceous matter (OC, EC) and water-soluble ions (Cl^-, NO3^-, SO_4^(2-), Na^+, NH_4^+, K^+, Ca^(2+), Mg^(2+)). The 24-h PM_(2.5) 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 PM_(2.5) was calculated. Over the whole measurement period, the mean PM_(2.5) concentration was 31.56 μg m^(-3) and 24.92 μg m^(-3) in Raciborz and Zloty Potok, respectively. Regardless of the season, the total carbon percentage in PM_(2.5) was comparable at both sites and amounted ~40%. There were no visible seasonal variations in the secondary organic carbon (SOC) share in PM_(2.5). The mean percentage of the primary organic carbon (POC) in PM_(2.5) was higher than the SOC percentage at both locations. The mean contribution of the water-soluble ions in the PM_(2.5) mass was lower than the TC percentage, with values 20.35% (Zloty Potok) and 33.56% (Raciborz). The total share of the secondary ions (SO_4^(2-), NO_3^- and NH_4^+) in PM_(2.5) was comparable in both measurement periods. It was shown that PM_(2.5) at regional background sites in Southern Poland is significantly different than at similar stations across Europe. It is reflected by higher concentrations of PM_(2.5) and its main components and lower percentage of the secondary ions in the PM_(2.5) mass. The carbonaceous matter percentage in PM_(2.5) is higher than in other parts of Europe.