Trajectory-based analysis on the source areas and transportation pathways of atmospheric particulate matter over Eastern Finland

Abstract In this study, we utilize aerosol mass spectrometer (AMS) and multi-angle absorption photometer (MAAP) measurements to assess the most predominant source regions of various atmospheric aerosol constituents transported to Eastern Finland. The non-refractory composition data from the AMS were measured during three intensive measurements campaigns in autumn 2012, 2014 and 2016, whereas the continuous long-term measurements on equivalent black carbon were conducted in 2012–2017. According to observations, the highest concentrations of particulate organics, sulphate, ammonium and black carbon originated from western parts of Russia and Eastern Europe, whereas Central Europe showed lesser contribution. In addition, exceptionally high concentrations of sulphate and ammonium were associated with the Timan-Pechora basin located in north-western Russia. Assumingly, this phenomenon could be linked to intensive gas flaring activities taking place in the area. We also performed positive matrix factorization analysis of organic fraction measured by the AMS. The trajectory analysis revealed increased concentration fields (CF) for low-volatility oxygenated organic aerosol (LVOOA) and hydrocarbon-like organic aerosol (HOA) in the same areas as for sulphate and ammonium. Meanwhile, the CF of semi-volatile oxygenated organic aerosol (SVOOA) suggested a local origin. To summarize, our results suggest that Western Russia and Eastern Europe are the most important source regions of several long-range transported aerosol constituents for Eastern Finland. Besides influencing the air quality and aerosol chemical composition on a local scale, these regions may also play a crucial role as the pollutants are transported further north, towards the vulnerable Arctic region.