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

Abstract

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.