Comment on egusphere-2025-5822

Abstract. The dissolution behavior of atmospheric calcium (Ca) mineral dust released from arid regions and their climate impacts via buffering effects are highly dependent on their size-resolved mineralogical composition. Due to the inherent complexity of mineral dust, tracing the chemical forms and mixing states of Ca minerals at single-particle level remains challenging. In this study, an automated microanalysis technique was employed to characterize the physicochemical properties of 43,990 individual mineral dust particles generated by saltation-sandblasting processes in two typical Asian dust source regions, along with their residual 42,306 particles after water dialysis. Both the total dust and the Ca-containing particles exhibited a modal peak in the submicron size range, before and after dialysis. After dialysis, 56.9 % to 88.2 % (by number) of the calcium-containing dust particles lost their soluble calcium components. These water-soluble constituents accounted for 19.6–41.9 % of the mass of calcium-containing particles in both the Taklimakan and Gobi deserts. In addition, more than 73.0 % of Ca-O-rich and Ca-S-containing particles occurred as surface coatings on other minerals and were effectively removed by water dialysis. The abundance and mixing state of water-soluble calcium-containing particles in mineral dust emitted from Asian dust source regions provide realistic constraints for assessing their role in enhancing atmospheric acid neutralization and mitigating ocean acidification.