Cross-regional characteristics, chemical composition, and source contributions of atmospheric particulate matter in...

Atmospheric particulate matter (PM) influences air quality, visibility, and the radiation budget, yet inter-regional differences in sources and chemical characteristics remain poorly understood. In this study, PM samples from Karlsruhe, Germany and Ajmer, India were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM). Elemental analysis revealed high concentrations of Na and Al were high in both locations. Elemental ratios (Fe/Al, Ti/Al, Cu/Zn, and V/Pb) reveal strong traffic- and industrial-related influences in Karlsruhe and combined dust, combustion, and industrial impacts in Ajmer. 3D-EEM analysis shows that highly oxygenated humic-like substance (HULIS) (C1 and C2) dominated in Karlsruhe (62%) during the sampling period, while less‑oxygenated HULIS (C3) from biomass burning was most abundant in winter season (41%). In Ajmer, less‑oxygenated HULIS remained dominant throughout the sampling period (C1, 57%), while highly oxygenated HULIS (C2) and mixed-source components (C4) contributed 19% and 2%, respectively. PMF highlighted complex source profiles, including industrial, crustal, and mixed anthropogenic contributions in both locations. These findings improve understanding of inter-regional PM composition and sources, providing insights for targeted air quality management and climate impact assessment.