posted on 2024-01-22, 15:38authored byTori Hass-Mitchell, Taekyu Joo, Mitchell Rogers, Benjamin A. Nault, Catelynn Soong, Mia Tran, Minguk Seo, Jo Ellen Machesky, Manjula Canagaratna, Joseph Roscioli, Megan S. Claflin, Brian M. Lerner, Daniel C. Blomdahl, Pawel K. Misztal, Nga L. Ng, Ann M. Dillner, Roya Bahreini, Armistead Russell, Jordan E. Krechmer, Andrew Lambe, Drew R. Gentner
As
part of the summer 2022 NYC-METS (New York City metropolitan
Measurements of Emissions and TransformationS) campaign and the ASCENT
(Atmospheric Science and Chemistry mEasurement NeTwork) observational
network, speciated particulate matter was measured in real time in
Manhattan and Queens, NY, with additional gas-phase measurements.
Largely due to observed reductions in inorganic sulfate aerosol components
over the 21st century, summertime aerosol composition in NYC has become
predominantly organic (80–83%). Organic aerosol source apportionment
via positive matrix factorization showed that this is dominated by
secondary production as oxygenated organic aerosol (OOA) source factors
comprised 73–76% of OA. Primary factors, including cooking-related
organic aerosol (COA) and hydrocarbon-like organic aerosol (HOA) comprised
minor fractions of OA, only 13–15% and 10–11%, respectively.
The two sites presented considerable spatiotemporal variations in
OA source factor concentrations despite similar average PM2.5 concentrations. The less- and more-oxidized OOA factors exhibited
clear temperature dependences at both sites with increased concentrations
and greater degrees of oxidation at higher temperatures, including
during a heatwave. With strong temperature sensitivity and minimal
changes in summertime concentrations since 2001, secondary OA poses
a particular challenge for air quality policy in NYC that will very
likely be exacerbated by continued climate change and extreme heat
events.