The chemical processes occurring in aerosols are complex, but most of the previous studies have speculated such processes based on the relative abundances of various chemical components in the aerosols. In this study, XAFS has been applied to the speciation of calcium, sulfur, zinc, and iron that are related to the neutralization of acid depositions, the cooling effect of the Earth, and nutrients to phytoplankton in the open ocean. Study 1: Neutralization of Acidic Species in the Atmosphere by Asian Dust Calcite, CaCO 3 , is abundant in Asian dust (around 10 wt.%), which is a compound reactive toward acidic species such as sulfuric and nitric acids. We employed X-ray absorption near-edge structure (XANES; XAFS consists of XANES and EXAFS (extended X-ray absorption fine structure) depending on the energy region within the XAFS spectrum) to determine calcium and sulfur species in aerosols (i) to obtain the ratio of calcite and gypsum (CaSO 4 •2H 2 O), the main calcium species

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