Geochemical fingerprinting and source apportionment of deposited African dust in southwestern Europe using elemental ratios and receptor modelling

African dust deposition is a major driver of atmospheric inputs to Mediterranean and southwestern European ecosystems, yet high-resolution source apportionment able to discriminate sub-regional North African origins across contrasting environments remains limited. Here we provide a comprehensive assessment of African dust deposition in southwestern Europe using 114 bulk-deposition samples collected at 15 monitoring sites spanning urban, remote, agricultural, and industrial settings across the Iberian Peninsula and the Balearic Islands. Total bulk aerosol deposition fluxes ranged from 10 to 55 g m −2 year −1 , and African dust accounted for up to 75% of the insoluble fraction at hotspots such as the southern Pyrenees and the southern Iberian coast. To capture meteorological controls and spatial heterogeneity, we analyzed four case studies representative of distinct synoptic scenarios along a seasonal gradient. Seasonal shifts in deposition fluxes and geochemical composition were observed, and elemental ratios (Fe/Ti, Ca/Al, Fe/Al, and (Ca + Mg)/Fe) enabled discrimination of three North African source regions (Western Sahara-Morocco, southern Algeria-northern Mali, and northern Algeria-Tunisia), addressing previous challenges in attributing deposition to sub-regional origins. Positive Matrix Factorization (PMF v5.0) yielded a ten-factor solution including three African dust factors alongside regional resuspension, marine input, traffic, regional pollution, combustion-related sources, and two industrial profiles; the African dust factors were separated by distinct chemical signatures, with the northern Algeria-Tunisia source enriched in carbonates. Source contributions varied markedly in space and time across the case studies, underscoring the need for event and region-specific source information to improve impact assessment and deposition modelling in southwestern Europe.