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| Titel |
PM2.5 water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies |
| VerfasserIn |
T. Fang, H. Guo, V. Verma, R. E. Peltier, R. J. Weber |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 20 ; Nr. 15, no. 20 (2015-10-21), S.11667-11682 |
| Datensatznummer |
250120110
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| Publikation (Nr.) |
 copernicus.org/acp-15-11667-2015.pdf |
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| Zusammenfassung |
| Water-soluble redox-active metals are potentially toxic due to its ability
to catalytically generate reactive oxygen species (ROS) in vivo, leading to
oxidative stress. As part of the Southeastern Center for Air Pollution and
Epidemiology (SCAPE), we developed a method to quantify water-soluble
elements, including redox-active metals, from a large number of filter
samples (N = 530) in support of the center's health studies. PM2.5
samples were collected during 2012–2013 at various sites (three urban, two
rural, a near-road site, and a road-side site) in the southeastern United States,
using high-volume samplers. Water-soluble elements (S, K, Ca, Ti, Mn, Fe,
Cu, Zn, As, Se, Br, Sr, Ba, and Pb) were determined by extracting filters in
deionized water and re-aerosolized for analyses by X-ray fluorescence (XRF)
using an online aerosol element analyzer (Xact, Cooper Environmental).
Concentrations ranged from detection limits (nominally 0.1 to 30 ng m−3)
to 1.2 μg m−3, with S as the most abundant element, followed by
Ca, K, Fe, Cu, Zn, and Ba. Positive matrix factorization (PMF) identified
four factors that were associated with specific sources based on relative
loadings of various tracers. These include brake/tire wear (with tracers Ba
and Cu), biomass burning (K), secondary formation (S, Se, and WSOC), and
mineral dust (Ca). Of the four potentially toxic and relatively abundant
metals (redox-active Cu, Mn, Fe, and redox-inactive Zn), 51 % of Cu,
32 % of Fe, 17 % of Mn, and 45 % of Zn were associated with the
brake/tire factor. Mn was mostly associated with the mineral dust factor
(45 %). Zn was found in a mixture of factors, with 26 % associated with
mineral dust, 14 % biomass burning, and 13 % secondary formation.
Roughly 50 % of Fe and 40 % of Cu were apportioned to the secondary
formation factor, likely through increases in the soluble fraction of these
elements by sulfur-driven aerosol water and acidity. Linkages between
sulfate and water-soluble Fe and Cu may account for some of the past
observed associations between sulfate/sulfur oxide and health outcomes. For
Cu, Mn, Fe, and Zn, only Fe was correlated with PM2.5 mass (r =
0.73–0.80). Overall, mobile source emissions generated through mechanical
processes (re-entrained road dust, tire and break wear) and processing by
secondary sulfate were major contributors to water-soluble metals known to
be capable of generating ROS. |
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