Fang, T.Guo, H.Zeng, L.Verma, V.Nenes, AthanasiosWeber, R. J.2018-10-152018-10-152018-10-15201710.1021/acs.est.6b06151https://infoscience.epfl.ch/handle/20.500.14299/148884Soluble transition metals in particulate matter (PM) can generate reactive oxygen species in vivo by redox cycling, leading to oxidative stress and adverse health effects. Most metals, such as those from roadway traffic, are emitted in an insoluble form, but must be soluble for redox cycling. Here we present the mechanism of metals dissolution by highly acidic sulfate aerosol and the effect on particle oxidative potential (OP) through analysis of size distributions. Size-segregated ambient PM were collected from a road-side and representative urban site in Atlanta, GA. Elemental and organic carbon, ions, total and water-soluble metals, and water-soluble OP were measured. Particle pH was determined with a thermodynamic model using measured ionic species. Sulfate was spatially uniform and found mainly in the fine mode, whereas total metals and mineral dust cations were highest at the road-side site and in the coarse mode, resulting in a fine mode pH < 2 and near neutral coarse mode. Soluble metals and OP peaked at the intersection of these modes demonstrating that sulfate plays a key role in producing highly acidic fine aerosols capable of dissolving primary transition metals that contribute to aerosol OP. Sulfate-driven metals dissolution may account for sulfate-health associations reported in past studies. © 2017 American Chemical Society.AerosolsCarbonDissolutionOrganic carbonParticle size analysisRoads and streetsSulfur compoundsTransition metalsUrban growthAdverse health effectsAmbient particlesElemental and organic carbonsMetals dissolutionOxidative potentialParticulate MatterReactive oxygen speciesThermodynamic modelMetalsascorbic acidcopperhydronium ionironmanganeseorganic carbonsulfatetransition elementwateraerosolair pollutantmetalparticulate mattersulfateaerosoldissolutionorganic carbonoxidative stressparticulate matterreactive oxygen speciessulfatethermodynamicstoxicityurban siteacidityaerosolair monitoringambient airaqueous solutionArticlecomparative studycontrolled studydissolutionecotoxicitymineral dustoxidation reduction potentialparticle sizeparticulate matterpHthermodynamicsurban areaair pollutantenvironmental monitoringparticulate matterAtlantaGeorgiaUnited StatesAerosolsAir PollutantsEnvironmental MonitoringMetalsParticle SizeParticulate MatterSulfatestext::journal::journal article::research article