Fig. 1

Saharan dust event in the Dolomite Alps on February 19th 2014. a Back trajectories computed at different height levels and expressed in pressure values (color scale: <100 and >900 hPa).The starting point is located at Long 11.81° and Lat 46.86°, on 19th of Feb 2014 12:00 UTC. Solid circles represent locations every 6 h and numbers refer to date (day of February). b Map (made with Natural Earth) showing collection sites in the Dolomite Alps. c Snow samples were collected wearing protective suits, facemasks, and vinyl gloves. d Snowpit (2 m depth) consisting of layer A: snow that fell after the Saharan dust event; layer B: Saharan sand-containing snow, clearly distinguishable by its light brown color. and layer C: snow that fell before the Saharan dust event. e Relative abundances of the most abundant bacterial (16S rRNA gene) and fungal (ITS) classes present in the three snow layers and the soil layer (not shown). Saharan sand-containing snow is characterized by a higher relative abundance of Actinobacteria and Dothideomycetes