This work aims to identify the geochemical and mineralogical markers of Icelandic dust and to differentiate it from the dust of local origin deposited at the Ny-Ålesund station. We characterized representative sediment samples from Iceland and Svalbard and compared them to a set of aerosol samples collected in Ny-Ålesund to check the existence and type of the mineralogical markers. The sediment samples were analyzed by X-ray diffraction (XRD) to detect the mineralogical constrain of the geochemical markers. Both aerosol and sediment samples were examined by scanning electron microscopy coupled with EDS microanalysis (SEM-EDS) and image analysis to detect and to provide a morpho-chemical characterization of the mineralogical markers of dust provenance. Comparison between local and Icelandic sediments reveals the metal oxide particles as the most representative and distinguishing mineralogical/phase markers for Iceland dust sources. In particular, we have considered the magnetite-chromite and the magnetite-ülvospinel associations as marker facies of the tholeiitic magmatic series and the presence of volcanic glass as a further indicator of provenance from Iceland. The morphochemical characteristics of the metal oxide particles in the aerosol samples compared to those of the sediment samples have proved to be a powerful tool to separate Icelandic dust from other sources for dust. In particular, the small size, higher grain boundary complexity and lower Fe/Cr ratios suggest the influence of anthropogenic sources, well in accordance with the results of air mass backward trajectories which reveal a main contribution from industrialized areas in Eurasia. This study shows the reliability of the geochemical characterization of the metal oxide particles for the identification of the source regions of dust. In addition it provides an evidence that Icelandic dust can be transported long range to Svalbard confirming the importance of High Latitude Dust sources.

Size-segregated particle samples were collected in the Arctic (Ny-Ålesund, Svalbard) in April 2011 both at ground level and in the free atmosphere exploiting a tethered balloon equipped also with an optical particle counter (OPC) and meteorological sensors. Individual particle properties were investigated by scanning electron microscopy coupled with energy dispersive microanalysis (SEM-EDS). Results of the SEM-EDS were integrated with particle size and optical measurements of the aerosols properties at ground level and along the vertical profiles. Detailed analysis of two case studies reveals significant differences in composition despite the similar structure (layering) and the comparable texture (grain size distribution) of particles in the air column. Differences in the mineral chemistry of samples point at both local (plutonic/metamorphic complexes in Svalbard) and remote (basic/ultrabasic magmatic complexes in Greenland and/or Iceland) geological source regions for dust. Differences in the particle size and shape are put into relationship with the mechanism of particle formation, that is, primary (well sorted, small) or secondary (idiomorphic, fine to coarse grained) origin for chloride and sulfate crystals and transport/settling for soil (silicate, carbonate and metal oxide) particles. The influence of size, shape, and mixing state of particles on ice nucleation and radiative properties is also discussed.

This paper reports an exceptional biomass burning (BB) advection event from Alaska registered at Ny‐Ålesund from 10 to 17 July 2015 with particular interest on the influence of the airborne particle characteristics on the optical properties of the aerosol during the event. To this purpose we considered two DEKATI 12‐stage aerosol samples spanning the entire advection and analyzed them by scanning electron microscopy techniques. Aerosol chemical data and microphysical properties were also evaluated in order to correlate any change of individual particle characteristics with the bulk properties of the aerosol. The results of individual particle analysis depict a complex event characterized by a first phase (P1) of massive input of BB carbonaceous particles (i.e., tar balls, popcorn refractory particles, and organic particles), and by a second phase (P2) dominated by inorganic salts. The peculiar feature of this BB event is the exceptionally large grain size of the subspherical organic particles at the beginning of the event with respect to the background. At these conditions a significant increase of the scattering efficiency may occur even for a small increase of the size parameter. Results of the simulation of the complex refractive indices (n‐ik) confirm this evaluation. Aerosol evolution during the event resulted from the combination of three distinct occurrences: (a) progressive rotation of air mass circulation toward non‐BB source areas, (b) development of a thick fog layer in the planetary boundary layer, and (c) sea salt spray direct advection of local/regional provenance.