posted on 2021-10-05, 12:06authored byTaekyu Joo, Yunle Chen, Weiqi Xu, Philip Croteau, Manjula R. Canagaratna, Dong Gao, Hongyu Guo, Gabriela Saavedra, Seong Shik Kim, Yele Sun, Rodney Weber, John Jayne, Nga Lee Ng
Aerosol
mass spectrometers (AMSs) and aerosol chemical speciation
monitors (ACSMs) have been deployed at numerous locations to quantify
nonrefractory aerosol composition. Recent instrumentation advancement
includes the development of a new capture vaporizer (CV) to improve
collection efficiency and a PM2.5 aerodynamic lens to measure
aerosol up to 2.5 μm in diameter. To validate these new instrument
capabilities and investigate differences in composition of atmospheric
PM1 and PM2.5, a PM1-SV-AMS, and
a PM2.5-CV-ACSM were deployed in urban Atlanta, GA in winter
2018 with other instruments. Nonrefractory species measured by the
two instruments agree well and are dominated by organic aerosol (OA).
About 85% of the nonrefractory species in PM2.5 are in
the PM1. Positive matrix factorization (PMF) analysis was
performed and the same number and OA subtypes were resolved for both
instruments. While the relative contribution of each factor to OA
was different, more-oxidized oxygenated organic aerosol (MO-OOA) is
determined to be the major type of OA in both instruments. The biomass
burning organic aerosol (BBOA) resolved from CV-ACSM significantly
contributes to signals at m/z 26,
42, 68, and 96. Cross-comparison with other instruments demonstrates
that ∼80% of PM1 and ∼90% of PM2.5 is nonrefractory species. The mass concentrations of PM1 and PM2.5 are comparable in general. During time periods
when PM2.5/PM1 is enhanced, the PM1–2.5 composition is dominated by OA and corresponds to higher less-oxidized-OOA
(LO-OOA)/OA and organic nitrate/total nitrate ratios. Results from
this study demonstrate the capability of PM2.5-CV-ACSM
and provide new insights into PM2.5 composition and sources
in the southeastern US.