Trace metal contamination in Antarctic atmospheric deposition: insights from elemental and isotopic analysis of a snow pit at McCarthy Ridge, Victoria Land

The study of chemical contamination in polar environments is fundamental for assessing recent and past atmospheric pollution on a global scale. To provide information on the occurrence, potential sources and temporal trends of trace metals in Antarctica, the concentration of Cd, Co, Cr, Cu, Pb, V, and Zn, along with Pb isotope ratios, were determined in 50 snow pit samples collected at McCarthy Ridge (Victoria Land, Antarctica), covering the period 2019-2021. The results highlighted an enrichment over the background levels by one order of magnitude (two orders for Zn), which was ascribed to the influence of both anthropogenic and natural sources. Pb isotopic data indicated that only 26 ± 13% of this contaminant in Victoria Land may be of anthropogenic origin, with a decreasing trend from 67 ± 16% during 1986–1994 and 38 ± 22% during the 2012–2015 period (computed from literature data). Finally, no regular seasonal pattern was identified, underscoring a high degree of complexity in the processes governing the atmospheric transport and deposition of trace metals in Antarctica at short temporal scales.