posted on 2024-02-10, 16:03authored byYuhan Yang, Michael A. Battaglia, Magesh Kumaran Mohan, Ellis S. Robinson, Peter F. DeCarlo, Kasey C. Edwards, Ting Fang, Sukriti Kapur, Manabu Shiraiwa, Meeta Cesler-Maloney, William R. Simpson, James R. Campbell, Athanasios Nenes, Jingqiu Mao, Rodney J. Weber
The oxidative potential
(OP) of outdoor PM2.5 in wintertime
Fairbanks, Alaska, is investigated and compared to those in wintertime
Atlanta and Los Angeles. Approximately 40 filter samples collected
in January–February 2022 at a Fairbanks residential site were
analyzed for OP utilizing dithiothreitol-depletion (OPDTT) and hydroxyl-generation (OPOH) assays. The study-average
PM2.5 mass concentration was 12.8 μg/m3, with a 1 h average maximum of 89.0 μg/m3. Regression
analysis, correlations with source tracers, and contrast between cold
and warmer events indicated that OPDTT was mainly sensitive
to copper, elemental carbon, and organic aerosol from residential
wood burning, and OPOH to iron and organic aerosol from
vehicles. Despite low photochemically-driven oxidation rates, the
water-soluble fraction of OPDTT was unusually high at 77%,
mainly from wood burning emissions. In contrast to other locations,
the Fairbanks average PM2.5 mass concentration was higher
than Atlanta and Los Angeles, whereas OPDTT in Fairbanks
and Atlanta were similar, and Los Angeles had the highest OPDTT and OPOH. Site differences were observed in OP when normalized
by both the volume of air sampled and the particle mass concentration,
corresponding to exposure and the intrinsic health-related properties
of PM2.5, respectively. The sensitivity of OP assays to
specific aerosol components and sources can provide insights beyond
the PM2.5 mass concentration when assessing air quality.