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| Titel |
Oxidant production from source-oriented particulate matter – Part 1: Oxidative potential using the dithiothreitol (DTT) assay |
| VerfasserIn |
J. G. Charrier, N. K. Richards-Henderson, K. J. Bein, A. S. McFall, A. S. Wexler, C. Anastasio |
| 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. 5 ; Nr. 15, no. 5 (2015-03-04), S.2327-2340 |
| Datensatznummer |
250119486
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| Publikation (Nr.) |
 copernicus.org/acp-15-2327-2015.pdf |
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| Zusammenfassung |
| Recent epidemiological evidence supports the hypothesis that health effects
from inhalation of ambient particulate matter (PM) are governed by more than
just the mass of PM inhaled. Both specific chemical components and sources
have been identified as important contributors to mortality and hospital
admissions, even when these end points are unrelated to PM mass. Sources may
cause adverse health effects via their ability to produce reactive oxygen
species in the body, possibly due to the transition metal content of the PM.
Our goal is to quantify the oxidative potential of ambient particle sources
collected during two seasons in Fresno, CA, using the dithiothreitol (DTT)
assay. We collected PM from different sources or source combinations into
different ChemVol (CV) samplers in real time using a novel source-oriented
sampling technique based on single-particle mass spectrometry. We segregated
the particles from each source-oriented mixture into two size fractions –
ultrafine Dp ≤ 0.17 μm) and submicron fine
(0.17 μm ≤ Dp ≤ 1.0 μm) – and measured
metals and the rate of DTT loss in each PM extract. We find that the
mass-normalized oxidative potential of different sources varies by up to a
factor of 8 and that submicron fine PM typically has a larger mass-normalized
oxidative potential than ultrafine PM from the same source. Vehicular
emissions, regional source mix, commute hours, daytime mixed layer, and
nighttime inversion sources exhibit the highest mass-normalized oxidative
potential. When we apportion DTT activity for total PM sampled to specific
chemical compounds, soluble copper accounts for roughly 50% of total
air-volume-normalized oxidative potential, soluble manganese accounts for
20%, and other unknown species, likely including quinones and other
organics, account for 30%. During nighttime, soluble copper and
manganese largely explain the oxidative potential of PM, while daytime has a
larger contribution from unknown (likely organic) species. |
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