The recent increase in cardiovascular and metabolic disease in the Navajo population residing close to the Grants Mining District (GMD) in New Mexico is suggested to be due to exposure to environmental contaminants, in particular uranium in respirable dusts. However, the chemistry of uranium-containing-dust dissolution in lung fluids and the role of mineralogy are poorly understood, as is their impact on toxic effects. The current study is focused on the dissolution of xcontaining-dust, collected from several sites near Jackpile and St. Anthony mines in the GMD, in two simulated lung fluids (SLFs): Gamble's solution (GS) and Artificial Lysosomal Fluid (ALF). We observe that the respirable dust includes uranium minerals that yield the uranyl cation, UO 2 2+ , as the primary dissolved species in these fluids. Dust rich in uraninite and carnotite is more soluble in GS, which mimics interstitial conditions of the lungs. In contrast, dust with low uraninite and high kaolinite is more soluble in ALF, which simulates the alveolar macrophage environment during phagocytosis. Moreover, geochemical modeling, performed using PHREEQC, is in good agreement with our experimental results. Thus, the current study highlights the importance of site-*

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Over the last several decades, iron has been identified as a limiting nutrient in about half of the world's oceans. Its most significant source is identified as deposited iron-containing mineral dust that has been processed during atmospheric transportation. The current work focuses on chemical and photochemical processing of iron-containing mineral dust particles in the presence of nitric acid, and an organic pollutant dimethyl sulfide under atmospherically relevant conditions. More importantly, ilmenite (FeTiO) is evaluated as a proxy for the iron-containing mineral dust. The presence of titanium in its lattice structure provides higher complexity to mimic mineral dust, yet it is simple enough to study reaction pathways and mechanisms. Here, spectroscopic methods are combined with dissolution measurements to investigate atmospheric processing of iron in mineral dust, with specific focus on particle mineralogy, particle size, and their environmental conditions (i.e., pH and solar flux). Our results indicate that the presence of titanium elemental composition enhances iron dissolution from mineral dust, at least by 2-fold comparison with its nontitanium-containing counterparts. The extent of iron dissolution and speciation is further influenced by the above factors. Thus, our work highlights these important, yet unconsidered, factors in the atmospheric processing of iron-containing mineral dust aerosol.

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Atmospheric 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-Fe 2 O 3 ) in the presence of a relatively common semiconductor oxide in mineral dust aerosol, that is, titania (TiO 2 ), in three different atmospheric mineral acids, HNO 3 , HCl, and H 2 SO 4 . Our studies suggest that Fe dissolution in the daytime increases when mixed with TiO 2 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 HNO 3 and HCl, whereas it decreases for H 2 SO 4 , suggesting reactivity differences of the anionic radicals. In the dark, the presence of TiO 2 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.