## 3 Results
### Raman Micro-Spectroscopy  
Raman micro-spectroscopy was applied in this study for the characterization of small micromaterials (1-20 \(\upmu\)m). The use of a 633 nm laser allowed for obtaining good-quality spectra: in only some cases, the 785 nm laser source was more effective in reducing the fluorescence background. The majority of microparticles identified in the melted snow samples were minerals, carbonaceous particles, and small microplastics. According to the results obtained by TEM analyses of NPs, in all the samples located near the research base (A, B, C, E), small microparticles of carbonaceous origin were  
Figure 5: TEM/EDX analysis of soot observed in the samples closest to Mario Zucchelli Station. (**a**,**b**) HAADF-STEM and TEM images of chain-like clusters of soot nanoparticles, respectively; (**c**) a high-resolution TEM image of the red-line-boxed area in (**b**); (**d**) HAADF-STEM/EDX analysis of soot aggregate containing Pb; (**e**) EDX spectrum of soot aggregate. Figure 6: A HAADF-STEM image with the corresponding EDX maps of metal oxide nanoparticles observed in sample A containing (**a**) Fe and Ti; (**b**) Cd. In the EDX spectrum, the L-lines profile of Cd (brown) is superimposed on the collected spectrum (yellow). identified. As reported in Figure 6, the Raman spectra of these particles showed the presence of two characteristic broad overlapping bands at 1585 cm\({}^{-1}\) and 1360 cm\({}^{-1}\), corresponding to the so-called G and D bands, respectively. The identification of such carbonaceous particles is still a debated issue, since different shapes and intensities of the bands could be related to the nature of carbon. It is known that the G peak is associated with the E2g mode of bulk crystalline graphite, whereas the D peak appears when the graphite breaks down near the crystal edges. Finally, the presence of both peaks suggests that the particles were formed by amorphous carbon, i.e., a combination of crystalline graphite and non-graphite elements [39]. The Raman response of the carbon particles was not different for most of the analyzed samples, with the intensity of the D band being higher than that of the G band (Figure 7a,b). Some exceptions were found in sample A, where a few particles were characterized by an inversion of the band intensities (Figure 7c). As stated in previous studies [40,41], these findings could suggest the existence of different sources of carbonaceous particles. Minerals, including sulfates, carbonates, and nitrates, were present as the most abundant species in all the samples. Figure 6 shows some examples related to burkeite--Na\({}_{6}\)(CO\({}_{3}\))(SO\({}_{4}\))\({}_{2}\) (RRUFF ID spectra R060112) (Figure 8a) [42,43]; sodium nitrate--NaNO\({}_{3}\) (Figure 8b) [28]; and glauberite--Na\({}_{2}\)Ca(SO\({}_{4}\))\({}_{2}\) (RRUFF ID R050350) (Figure 8c) [43,44]. Many inorganic species have already been identified in previous studies. As in the case of carbonaceous particles, their origins are still debated. In particular, a study dealing with the characterization of Antarctic aerosol samples collected during austral summer and winter revealed the increased presence of nitrates and sulfates in the samples collected during summer as a consequence of high phytoplankton activity [28]. In a different study, the origin of sulfate in Antarctic dry-valley soils was ascribed not only to wind-blown sea salt but also to the atmospheric oxidation of reduced gaseous sulfur compounds [45]. Small microplastics were the other class of identified particles. In this study, attention was paid to particles \(<20\)\(\upmu\)m. They were identified in all samples with diameters in  
Figure 8: Raman spectra of (**a**) burkeite, (**b**) sodium nitrate, and (**c**) glauberite. Figure 7: Raman spectra of different small carbonaceous microparticles present in sample A: (**a,b**) carbon particles characterized by the D band being higher than the G band; (**c**) a particle with inverted band intensities. the 2-20 \(\upmu\)m range, but differences in their composition were observed.