Iida Kostamo, Outi Meinander, Anu Kaakinen, Sari Lukkari, Johanna Salminen
North African dust is frequently transported over thousands of kilometers and deposited across Europe, including high-latitude regions. Although mineralogical differences between Saharan and Sahelian dust are well documented in source regions, the extent to which these signatures are preserved during long-range transport remains unclear. Here we investigate the environmental magnetic properties of dust deposited in Finland during a major North African dust event in February 2021. Magnetic parameters reflecting composition, concentration, and grain-size distribution, together with scanning electron microscopy observations, reveal that the dust is dominated by magnetite, accompanied by variable contributions of maghemite and goethite. Two magnetically distinct groups are identified, differing in the degree of magnetite oxidation and the abundance of high-coercivity goethite. These differences reflect variable mixing of Saharan and Sahelian dust sources, demonstrating that source-dependent magnetic signatures can be preserved during transport over several thousand kilometers. Samples with a stronger Sahelian signature contain more oxidized magnetite and enhanced goethite contents, reflecting more intense chemical weathering in Sahelian source regions. Evidence for aggregated magnetite particles and anthropogenic iron oxides is also observed, indicating an additional contribution from anthropogenic sources that influences the magnetic properties of the transported dust. The magnetic properties closely resemble those reported for North African dust deposited elsewhere in Europe, demonstrating the robustness of its mineral magnetic signature across diverse depositional environments. These findings show that environmental magnetic methods provide a sensitive tool for tracing the provenance of long-range transported dust and demonstrate that Saharan and Sahelian source contributions remain detectable even at high northern latitudes.