Enhanced Oxidation of Cr(III)–Fe(III) Hydroxides by Oxygen in Dark and Alkaline Environments: Roles of Fe/Cr Ratio and Siderophore

Variable Valence State of Trace Elements Regulating Toxic Potencies of Inorganic Particulate Matter

“…The valence state of TEs is closely related to geochemical behavior in the environment and the toxic effect of PM. ,, One element possibly exhibits various toxicities with their different valence states, such as that Cr­(VI) and V­(V) are more toxic than those in their lower valency state of Cr­(III) , and V­(VI) or V­(III), respectively, while some elements (including Fe and As) in their lower valence states possibly display greater toxicities. , The toxicology of TEs depends on the redox property, which determines the ability to generate reactive oxygen species (ROS). − Excessive ROS generation from TEs with distinct valence can cause toxic potencies when exposed to ambient PM. − The valence compositions of some TEs in PM could be determined via various methods, including Fe, Cr, and V. − Due to that, the valence state is commonly unstable and varies with emission sources , and atmospheric conditions, including acidic property, , relative humidity, and concentration oxidants . TEs bonded in PM are likely to undergo a reorganization of their valence states during their aging processes in the atmosphere.…”

“…25−27 The valence compositions of some TEs in PM could be determined via various methods, including Fe, Cr, and V. 28−30 Due to that, the valence state is commonly unstable and varies with emission sources 29,31 and atmospheric conditions, including acidic property, 32,34 relative humidity, 33 and concentration oxidants. 34 TEs bonded in PM are likely to undergo a reorganization of their valence states during their aging processes in the atmosphere. However, a knowledge gap persists regarding the valence states of TEs and their toxic potencies, resulting in inaccurate assessment of PM toxicities and health impacts.…”