Spatial Distribution, Sources, and Deposition Fluxes of Trace Elements in Aerosols Across the Indian Ocean

Abstract

Abstract Aerosols are integral in supplying bio‐essential trace elements (TEs) to the upper ocean. Given rapid environmental change, a comprehensive understanding of the current status and historical trends of TEs in marine aerosols is essential. This study conducted a 90‐day investigation of aerosol TEs extending from the South China Sea (SCS) to the Indian Ocean (IO). The results show a decline in aerosol TE concentrations from the SCS to the Equatorial IO (EIO) and further to the Southern IO (SIO), with significant enrichment of most TEs observed throughout the regions. Historical comparisons indicate that present‐day aerosol TE concentrations and enrichment factors generally exceed 1980s levels but remain substantially below their early‐21st‐century peak. This trend reflects dynamic shifts in aerosol sources over the IO, attributable to regional industrialization followed by the adoption of emission controls. Source apportionment indicated a predominantly mineral origin for Fe, Ti, and Mn, a mixed mineral‐anthropogenic source for Ba and Co, and a dominantly anthropogenic origin for V, Cr, Cu, Zn, Ni, As, Se, Cd, Sn, and Pb. Statistical analysis identified potential sources for anthropogenic TEs, such as Zn, As, Se, Sn, and Pb, which were likely influenced by coal combustion. The evaluated bulk deposition fluxes of the TEs generally showed the following spatial distribution: SCS > EIO > SIO. Notably, wet deposition is dominant, except in the SIO. These findings provide valuable insights into the spatial variability, sources, fluxes, and historical trends of aerosol TEs over the IO.