Tracing long-range transport of anthropogenic lead (Pb) to coastal East Antarctica using Pb isotopes and geochemical fingerprinting.

Lead (Pb) concentrations and isotopic ratios (206Pb/207Pb and 208Pb/207Pb) in Antarctic snow serve as unique tracers of atmospheric pollution transport into the Southern Hemisphere. We investigated Pb sources and transport pathways to coastal Dronning Maud Land (cDML), East Antarctica, through the analysis of nine surface snow cores collected from three different ice rises. To isolate the atmospherically derived fractions, snow samples were subjected to 60-day weak-acid leaching prior to trace-element and Pb isotope analyses. The Pb concentrations range from 9.97 to 29.8 pg g-1 (mean = 18.7 ± 6.4 pg g-1). Enrichment factors for Pb in the operationally defined labile fraction (EFPb = 70-110; mean = 93) calculated relative to upper continental crust values (Pb/Ba ≈0.03), indicate substantial non-crustal enrichment, consistent with anthropogenic Pb input. The 206Pb/207Pb ratios range from 1.13 to 1.16, and 208Pb/207Pb ratios from 2.41 to 2.43 are consistent with dominant contributions from South American emission sources. A five source Bayesian isotope mixing model (MixSIAR) was employed to quantify the relative contributions of major Pb sources to the cDML region. Model estimates that Argentina (∼40%) and Brazil (∼36%) together account for 72-84% of Pb deposition across the three ice rises, with smaller contributions from Chile (∼15%), Australia (∼5%), and local Antarctic sources (Skarvsnes; ∼4%). These results demonstrate that cDML snow archives hemispheric-scale industrial emissions, with South America as the primary contributor. The findings provide a regionally constrained modern baseline for monitoring global pollution transport and highlight Antarctica's sensitivity to anthropogenic atmospheric contamination in the Southern Hemisphere.