Aerosol trace element transport and deposition in the warming Arctic
Aerosol trace element (TE) transport serves as a critical driver of marine TE biogeochemical cycles and climate feedback systems. In the rapidly warming Arctic Ocean (AO), however, the contemporary distribution patterns and decadal variability of aerosol TE deposition remain poorly constrained, representing a critical gap in our understanding of current and future Arctic environmental changes. Here, we present extensive shipboard observations of 13 aerosol TEs across the AO during summer 2024. TE concentrations and the enrichment levels of these anthropogenic TEs rank among the lowest globally observed in the AO. The comparable or even elevated mineral-dominated TE concentrations and deposition fluxes (Al, Fe) in the Central AO than Peripheral AO challenge current dust models, potential influenced by sea ice/snow resuspension. Coal combustion (As, Se), non-exhaust vehicular emissions (Ni, Cr), and metallurgical activities (Zn) emerged as primary anthropogenic sources, with detectable anthropogenic imprint even in mineral-dominated TEs (e.g., Fe, Mn). Decadal comparisons with historical records revealed a near ten-fold reduction in Pb and Cd enrichment, contrasting with a near-doubling of V enrichment driven by intensified Arctic shipping. Moreover, the distinct aerosol Fe/Al fractionation between this study and historical observations likely arises from mixing inputs of anthropogenic Fe-rich particles and permafrost-derived Fe-depleted weathering products, which amplify uncertainties in Fe flux estimations derived from dust proxy approaches. This study provides advance understanding of aerosol TE dynamics in the warming Arctic and provide critical constraints for polar biogeochemical cycles.