Long-term study of chemical characteristics of aerosol compositions in the rural environment of Rugsteliskis (Lithuania)

Aerosol particles play a significant role in shaping the atmosphere and affecting environmental conditions due to their variability in concentration, size, sources, and chemical composition. Therefore, there is a crucial need to enhance our understanding of the chemical composition and formation of aerosols. This study investigated the main chemical constituents of aerosols within the rural environment of Rugsteliskis, Lithuania, across three seasons (spring, summer, and autumn) spanning five years (2013, 2014, 2016, 2018, and 2019). The measurements were carried out using the Aerosol Chemical Speciation Monitor (ACSM). Organic aerosols (OA) made a higher contribution (60-80%) to total submicron particulate matter than inorganic aerosols (IA) (20-40%) during the measurement period. The contribution of NO(3Org)- and NO(3Inorg)- to the total NO3- was analysed separately, which indicated that NO(3Inorg)- was dominant and contributed up to 52.8% of the total. The diurnal trend of OA showed a higher mass concentration (6.37 mu g/m(3)) in the morning hours (5am-7am) and a lower mass concentration (5.50 mu g/m(3)) during the afternoon (12pm-15pm) for all three seasons. According to the results of the pollution wind rose analysis, the increase in SO42- and NH4+ was primarily linked to the long-range transport of air masses associated with the dominant wind directions and higher wind speeds from the north, east, and south. Furthermore, an analysis of long-range air mass transport showed that the prevailing directions resulted in higher mean OA concentrations from the northeast, east, and southeast which is illustrated in detail by concentration weighted trajectory graphs. The predominant directions of the lowest OA concentration were northwest and west.