title: Highly Acidic Ambient Particles, Soluble Metals, and Oxidative Potential: A Link between Sulfate and Aerosol Toxicity.
abstract: Soluble 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.
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Ting
authors.identifier: 0000-0002-4845-2749
authors.initials: T
authors.lastname: Fang
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Guo
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Linghan
authors.initials: L
authors.lastname: Zeng
authors.affiliation: Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign , Champaign, Illinois 61801, United States.
authors.forename: Vishal
authors.initials: V
authors.lastname: Verma
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|School of Chemical and Biomolecular Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.|Institute of Chemical Engineering Sciences, Foundation for Research and Technology , GR-26504, Patras, Greece.|Institute for Environmental Research and Sustainable Development, National Observatory of Athens , GR-15236, Palea Penteli, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Nenes
authors.affiliation: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Weber
mesh_terms: D000336:Aerosols; D000393:Air Pollutants; D004784:Environmental Monitoring; D008670:Metals; D010316:Particle Size; D052638:Particulate Matter; D013431:Sulfates
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter; D013431:Sulfates