| 10 Aug 2026
Measurement report: Sources of carbonaceous aerosol in a South-East European metropolis
Abstract. Carbonaceous aerosol measurements are scarce in the Western Balkans. We present year-round observations (2023 to 2025) from the urban-background site Ada Marina, Belgrade (44.790166° N, 20.4169° E; 71 m a.s.l.), combining three source apportionment (SA) approaches (organic tracers, the aethalometer model, and a novel application of non-negative matrix factorization, NNMF, to aethalometer data) with FLEXPART modelling and gridded emissions to identify source regions and transport pathways.
The annual mean equivalent black carbon (eBC) concentration was 1.42 ± 1.40 µg m⁻³, indicating a moderate eBC burden, while PM₁₀ (27.7 µg m⁻³) remained below current EU and Serbian limits but above WHO guidelines and upcoming EU limits. All SA methods consistently show strong winter to summer seasonality driven by residential wood combustion (RWC). The aethalometer model attributes 64 % of eBC to solid fuel (eBCSF) in winter versus 18 % in summer, NNMF yields 51 % versus 6 %, and offline analysis of tracers show elemental carbon from biomass burning (ECBB) contributions of 48 % versus 3 %.
Organic carbon (OC) shows similar seasonality, with biomass burning contributing 59 % in winter and 4 % in summer. A substantial wintertime secondary OC component linked to RWC is evident, with secondary OC (SOC) strongly correlated with ECBB and eBCSF (R² = 0.78 to 0.86), alongside enhanced brown carbon absorption (29 % annually; 44 % in winter).
FLEXPART indicates pollution episodes are dominated by regional transport within Serbia and the Pannonian Basin, while correlations between modelled residential emissions and observations demonstrate strong model skill.
