An integrated approach for interpreting PM2.5 composition and potential source characteristics in urban Tirana, Albania

Abstract

Fine particulate matter (PM 2.5 ) is a complex atmospheric pollutant originating from multiple natural and anthropogenic sources. This pilot study investigates the chemical composition and potential source characteristics of PM 2.5 in urban Tirana, Albania, during two monitoring campaigns conducted in March–April 2024 and April–May 2025. Elemental composition was determined by energy-dispersive X-ray fluorescence (ED-XRF), while water-soluble non-purgeable organic carbon (NPOC) and total nitrogen (TN) were analyzed using a TOC-L analyzer. Pearson correlation analysis was applied to investigate relationships among PM 2.5 constituents, whereas MERRA-2 dust reanalysis, HYSPLIT backward trajectories, MODIS aerosol optical depth (AOD) and meteorological observations were used as complementary atmospheric information. The 2024 campaign was characterized by higher concentrations of crustal-associated elements and atmospheric conditions consistent with a relatively stronger mineral dust influence, whereas the 2025 campaign exhibited lower elemental concentrations and lower variability in crustal-associated elements. Moderate positive but statistically non-significant correlations between TN and NPOC were observed during both campaigns, consisting of partially shared atmospheric behavior. The combined interpretation of elemental composition, Pearson correlation analysis and complementary atmospheric datasets suggest that PM 2.5 composition reflects multiple potential source influence s and atmospheric processing rather than a single dominant source. This integrated approach provides a practical qualitative framework for interpreting PM 2.5 composition in preliminary source assessment when quantitative receptor models are not available.