Iron (Fe) from dust deposition significantly impacts ocean ecosystems by increasing bioavailable Fe. It has long been demonstrated that acids formed on the surfaces of aging dust particles dissolve Fe under highly acidic conditions (pH < 3). However, Fe solubility remains unclear in dust particles due to a higher pH (pH > 3) during the dust storm from the buffering capacity of carbonate minerals. Our study revealed that Fe solubility at the downwind site after the long-distance transport (T4, 2.56 ± 1.15%) was 9 times higher than them at the near dust sources (T1, 0.29 ± 0.23%). Single-particle analysis found that minor dissolved Fe disperses in Ca-rich coatings because of the heterogenous reactions between acidic gases and dust particles. The study demonstrates that the Fe acid dissolution occurs along with the dust storm transport under the weak acidic conditions (pH > 3). Fe acid dissolution occurred during dust transport from T1 (0.19%) to downwind T2 (1.07%) under the Ca solubility < 45 ± 5% and significantly increased to 2.24-2.56% at further downwind places (T3, T4) under the Ca solubility > 45 ± 5%. Therefore, the Fe acid dissolution exhibits the synergistic interactions with Ca-rich coatings formation due to the mixture of Fe-containing aluminosilicate and carbonate mineral. The Fe acid dissolution from the heterogeneous reactions during dust storm should be incorporated the alkaline minerals and the other diversity mineralogy and mixing state of singe dust particles into the atmospheric biogeochemical cycle models.
 

iron acid dissolution,Fe solubility,aged dust particles,atmospheric chemistry,carbonate minerals,secondary acid aerosol