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Download fileMechanistic Study on Iron Solubility in Atmospheric Mineral Dust Aerosol: Roles of Titanium, Dissolved Oxygen, and Solar Flux in Solutions Containing Different Acid Anions
journal contribution
posted on 17.12.2019, 16:04 authored by Eshani Hettiarachchi, Gayan RubasinghegeAtmospheric processing of mineral dust aerosols has been
identified
as a major contributor to bioavailable Fe in the marine environment.
While numerous studies have focused on single-component Fe-bearing
minerals, the impact of non-Fe-bearing minerals, emitted via natural
and anthropogenic processes, on Fe dissolution remains largely unknown.
The current study investigates reaction mechanisms that govern the
dissolution of hematite mineral (α-Fe2O3) in the presence of a relatively common semiconductor oxide in mineral
dust aerosol, that is, titania (TiO2), in three different
atmospheric mineral acids, HNO3, HCl, and H2SO4. Our studies suggest that Fe dissolution in the daytime
increases when mixed with TiO2 because of HO•-mediated mechanisms. These effects are further enhanced by the dissolved
oxygen due to additional radical pathways arising from reactive oxygen
species. The presence of oxygen increases dissolved Fe(II) under irradiated
conditions for HNO3 and HCl, whereas it decreases for H2SO4, suggesting reactivity differences of the anionic
radicals. In the dark, the presence of TiO2 and nitrate
increases Fe dissolution due to redox coupling with nitrate under
reduced conditions. The current study thus reveals vital mechanistic
information on mineralogy-controlled iron dissolution in dust aerosols
by anthropogenic non-Fe-bearing minerals, oxygen and solar flux with
implications for global iron mobilization.
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Keywords
nitrate increases Fe dissolutionHOHNO 3H 2reactive oxygen speciesFe dissolutionpresencemineralogy-controlled iron dissolutionanthropogenic non-Fe-bearing mineralsmineral dust aerosolsTiO 2single-component Fe-bearing mineralsAcid Anions Atmospheric processingAtmospheric Mineral Dust Aerosolmineral dust aerosol