Title: Diel cycle impacts on the chemical and light absorption properties of organic carbon aerosol from wildfires in the western United States

Abstract

Organic aerosol (OA) emissions from biomass burning have been the subject of intense research in recent years, involving a combination of field campaigns and laboratory studies. These efforts have aimed at improving our limited understanding of the diverse processes and pathways involved in the atmospheric processing and evolution of OA properties, culminating in their accurate parameterizations in climate and chemical transport models. To bring closure between laboratory and field studies, wildfire plumes in the western United States were sampled and characterized for their chemical and optical properties during the ground-based segment of the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign. Using a custom-developed multiwavelength integrated photoacoustic-nephelometer spectrometer in conjunction with a suite of instruments, including an oxidation flow reactor equipped to generate hydroxyl (OH•) or nitrate (NO₃•) radicals to mimic daytime or nighttime oxidative aging processes, we investigated the effects of multiple equivalent hours of OH• or NO3• exposure on the chemical composition and mass absorption cross-sections (MAC(λ)) at 488 and 561 nm of OA emitted from wildfires in Arizona and Oregon. We found that OH• exposure induced a slight initial increase in absorption corresponding to short timescales; however, at longer timescales, themore » wavelength-dependent MAC(λ) decreased by a factor of 0.72 ± 0.08, consistent with previous laboratory studies and reports of photobleaching. On the other hand, NO₃• exposure increased MAC(λ) by a factor of up to 1.69 ± 0.38. We also noted some sensitivity of aerosol aging to different fire conditions between Arizona and Oregon. The MAC(λ) enhancement following NO₃• exposure was found to correlate with an enhancement in CHO₁N and CHO_gt1N ion families measured by an Aerodyne aerosol mass spectrometer.« less

Authors:

Sumlin, Benjamin ;

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• Search DOE PAGES for ORCID "0000-0003-2909-7494"

Fortner, Edward; Lambe, Andrew; Shetty, Nishit J.; Daube, Conner ;

• Search DOE PAGES for author "Daube, Conner"
• Search DOE PAGES for ORCID "0000-0001-8296-0272"

Liu, Pai; Majluf, Francesca; Herndon, Scott ;

• Search DOE PAGES for author "Herndon, Scott"
• Search DOE PAGES for ORCID "0000-0002-7348-8225"

Chakrabarty, Rajan K.

Publication Date:

Mon Aug 09 00:00:00 EDT 2021

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); National Aeronautics and Space Administration (NASA); National Science Foundation (NSF)

OSTI Identifier:

1812411

Alternate Identifier(s):

OSTI ID: 1814455

Grant/Contract Number:  

SC0021011; 80NSSC18K1414; NNH20ZDA001N-ACCDAM; AGS-1455215; AGS-1926817

Resource Type:

Published Article

Journal Name:

Atmospheric Chemistry and Physics (Online)

Additional Journal Information:

Journal Name: Atmospheric Chemistry and Physics (Online) Journal Volume: 21 Journal Issue: 15; Journal ID: ISSN 1680-7324

Publisher:

Copernicus GmbH

Country of Publication:

Germany

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES