Spatial Variability and Source Identification of Trace Elements in Aerosols From Northwest Pacific Marginal Sea, Indian Ocean and South Pacific to Antarctica

Aerosols continuously transport trace elements (TEs) across long distances to the ocean, fueling marine primary production and affecting global carbon cycles. Given the multiple sources and complex transport mechanisms, field investigations of aerosol TEs on a global scale are significant for understanding their role in marine biogeochemical cycles. Here, aerosol samples were collected along a 50,000-km route covering subtropical Northwest Pacific (NWP) marginal seas, Indian Ocean, Southern Ocean, Drake Passage, and South Pacific. Samples were analyzed for the concentrations of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Tl, and Pb. Aerosol TEs were distributed heterogeneously, with significantly lower concentrations over remote oceans compared to coastal seas. Meanwhile, TE concentrations were generally high in the Indian Ocean, moderate in the Southern Ocean, and low in the South Pacific. Cr, Ni, Cu, Zn, Cd, As, and Pb were widely enriched, primarily originating from anthropogenic sources, while Al, Ti, V, Mn, Fe, and Co were mainly from crustal sources in remote oceans. Moreover, specific sources of TEs were clarified, for example, Cr and Ni were mainly from vehicle emissions. The estimated bulk TE deposition fluxes also varied spatially. For instance, the greatest deposition of Fe occurs in the NWP marginal sea, followed by the Drake Passage, Indian Ocean Sector of Southern Ocean, Pacific Sector of Southern Ocean, and South Pacific. This study contributes to a deeper understanding of the complex dynamics of aerosol TEs in the global ocean, providing valuable information for future studies and policy making regarding climate change. Trace Elements serving as essential micronutrients (e.g., Fe and Mn), harmful pollutants (e.g., As and Pb), or reliable tracers (e.g., Ti and Al) are crucial for understanding marine biogeochemical processes. Aerosols continuously transport TEs over long-distances to the ocean, providing a significant source to the surface layer. Their complex sources and transport mechanisms cause substantial spatial variability in distribution and deposition. Limited observations and challenges of uncontaminated sampling further constrain our understanding of the role of aerosol TEs in the ocean. During a 180-day cruise, aerosol TEs were observed across a large spatial scale, providing an opportunity to better explore differences in aerosol TEs across multiple ocean basins due to consistent sampling and analysis. Results showed that TE concentrations were generally high in the Indian Ocean, moderate in the Southern Ocean, and low in the South Pacific. We identified TEs from crustal and anthropogenic sources, and further elucidated the specific origins of the anthropogenic elements. Furthermore, the bulk deposition fluxes of 14 TEs and dust as well as the contributions of dry and wet deposition. These findings help elucidate the aerosol TE depositions and their influence on marine TE cycles. Field observations of aerosol trace elements are conducted in the NW Pacific marginal sea, Indian Ocean, Southern Ocean, and South Pacific The degree of enrichment and the specific sources of trace elements are presented Bulk fluxes of dust and trace element as well as contribution ratios of dry and wet deposition are estimated across multiple basins