## 1 Introduction  
The effects of the presence of humans in Antarctica is a debated issue; although this polar region is considered relatively isolated from anthropogenic influence, it is affected by the presence of pollutants deriving from both long-range atmospheric transport (LRAT) and local sources. A variety of pollutants have been detected, including personal care products [1, 2], pharmaceuticals [3], polycyclic aromatic hydrocarbons [4, 5], and heavy metals [6, 7], both near research bases and in wider geographical areas. Beyond direct contamination episodes, the study of the LRAT of pollutants toward polar areas is an interesting research field, since contaminants characterized by reduced environmental mobility can also be atmospherically transported over long distances [1]. Recent studies tracked the same pollutants in the treated discharges of research bases in nearby areas, according to the wind pattern, and in seawater, observing a significant increase in the concentration levels during the seasonal melt of the sea ice and of its snow cover [2]. In this context, an emerging area of research is the determination of micro- and nanomaterials [8, 9], including nanoparticles (NPs); quantum dots; and organic nanomaterials, such as carbon-based materials and mixed organic-inorganic nanomaterials. These substances can derive from a variety of sources, being intentionally produced or deriving from contamination by anthropic activities [10]. In particular, due to their small size, NPs, having both organic and inorganic composition, can exert a large effect on atmospheric chemistry, together with increased environmental reactivity and toxicity. Their determination is an important issue for understanding the mechanisms of transferring pollutants through the environment. In this context, polar regions are an interesting sink for environmental contaminants; precipitation is recognized as an effective scavenger of aerodispersed matter, leading to its accumulation in the snowpack, where it can be preserved for long periods due to the low temperatures and reduced sunlight exposure [4; 11]. NPs are materials with a size in the 1-100 nm range and can be either artificially engineered or produced via natural processes or human activities [12; 13]. The analysis of NPs requires the use of different analytical approaches, among which electron microscopy (EM) techniques, including transmission electron microscopy (TEM) [14; 15], environmental scanning electron microscopy (ESEM) [16; 17], scanning probe microscopy, and atomic force microscopy (AFM) [18; 19], are particularly suitable for the imaging and characterization of individual NPs due to their intrinsic sub-nanometer-scale resolution. These techniques represent a valuable tool for nanomaterial characterization in terms of morphology, size, and structure. In addition, TEM equipped with energy-dispersive X-ray spectroscopy (EDX) provides qualitative and/or semi-quantitative elemental composition information of the investigated particles using 2D chemical spatial mapping, also at the nanoscale level. These unique features are crucial for effective particle classification. Moreover, unlike bulk methods, TEM/EDX can also reveal the mixing state of particles, showing the coexistence of different chemical and physical phases within a particle. This significantly contributes to a comprehensive understanding of their sources and their impacts on the environment [20]. When applied to the study of carbonaceous particles, TEM enables a focused examination that characterizes and discriminates between various particle types, including nanoplastics, black carbon, and organic matter [21]. This advanced analysis provides valuable insights into the probable sources of emission, allowing for differentiation between natural and anthropogenic origins.