TY - JOUR
T1 - Highly Acidic Ambient Particles, Soluble Metals, and Oxidative Potential
T2 - A Link between Sulfate and Aerosol Toxicity
AU - Fang, Ting
AU - Guo, Hongyu
AU - Zeng, Linghan
AU - Verma, Vishal
AU - Nenes, Athanasios
AU - Weber, Rodney J.
N1 - Funding Information:
This work was supported by the U.S. National Science Foundation under grant number 1360730 and the U.S. Environmental Protection Agency under grant number RD834799. Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the U.S. EPA. Further, the U.S. EPA does not endorse the purchase of any commercial products or services mentioned in the publication. We thank Emily M. Saad for helping in running ICP-MS for the MOUDI samples. T.F. acknowledges the support from the Oversea Study Program of Guangzhou Elite Project.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/3/7
Y1 - 2017/3/7
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.est.6b06151
DO - 10.1021/acs.est.6b06151
M3 - Article
C2 - 28141928
AN - SCOPUS:85018877752
VL - 51
SP - 2611
EP - 2620
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 5
ER -