Size distribution and seasonal evolution of airborne metals in Antarctic atmospheric particulate matter

Introduction: Aerosols play a crucial role in Earth's climate system, influencing the balance of radiation and cloud formation. Antarctica, despite its remoteness, provides an ideal environment in which to study background aerosol composition and the long-range transport of pollutants. This study investigates size-segregated elemental composition, seasonal variations, and potential sources of atmospheric aerosols in Antarctica. Methods: Seven size-segregated aerosol samples were collected at Faraglione Camp (~3 km from Mario Zucchelli Station) between November 2019 and January 2020 using a high-volume cascade impactor. Samples were analyzed for major (Na, Ca, K, Mg), minor (Al, Fe, Mn), and trace elements (Cd, Cr, Cu, Hg, Ni, V) using ICP-OES, GF-AAS, and DMA after acid microwave digestion. Results: The elemental concentrations of PM10 followed the order K > Na > Al Ca > Mg Fe > Mn > Cr > Ni > Cu V > Cd Hg. Seasonal trends were element-specific, influenced by katabatic winds and pack ice melting. Notably, Mg, Cu, Cr, and Hg peaked in late November/mid-December, likely due to sea spray emissions, while Fe, V, and Mn showed a decreasing trend. The size distribution analysis identified three modes of particle dispersion: accumulation (0.1–1 µm) and two coarse fractions (~2.5–3 µm and ~9.5 µm). Crustal enrichment factors (EFs) indicated geogenic origins for Mn and Fe (EF < 1), while Cu, Ni, K, Ca, and V enrichment was linked to soil resuspension. Mg and Na showed moderate enrichment (EF ~10), associated with sea spray, while Cd, Cr, and Hg exhibited high EFs (10 < EF < 100), suggesting an anthropogenic influence. Conclusions: These findings underscore the importance of continuous monitoring in assessing the contributions of aerosols to polar environments and their potential climatic and ecological impacts.