Abstract
Yearlong, one-in-three-day, source apportionment results were applied to literature values of source specific BrC, BC, and dust mass absorption cross-sections (MAC) to estimate the source contribution to 370 nm near-UV light absorption at Fresno and Bakersfield, San Joquin Valley (SJV), California. The reconstructed light absorption agreed well (r2 of 0.94 Fresno and 0.90 Bakersfield) with co-located AE33 aethalometer measurements. Near-UV absorption was attributed to total mobile, vegetative detritus, wood combustion, meat cooking, SOA, and dust sources. Winter BrC absorption was dominated by wood combustion, accounting for 67% (Fresno) and 53% (Bakersfield) of light absorption at the sites. In summer, wood combustion only accounted for approximately 7% of the near-UV absorption in the SJV. Summer absorption, while significantly lower than winter values, was dominated by SOA and vehicle emissions. In Fresno, summer absorption was comprised of 35% SOA, 39% vehicle BC and 15% vehicle BrC. Bakersfield’s summer absorption was 27% SOA, 44% vehicle BC, and 14% vehicle BrC. Total BrC absorption correlated well with OC concentrations, when segregated out by season, while the total BrC absorption was highly variable when compared to WSOC concentrations. The results indicate using source specific MAC values is an effective way to model near-UV light absorption associated with BrC sources and mitigation approaches that prioritize wood combustion in winter and vehicle emissions in summer would have the greatest effect in reducing near-UV light absorption in the SJV.
Original language | English |
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Article number | 230292 |
Journal | Aerosol and Air Quality Research |
Volume | 24 |
Issue number | 4 |
DOIs | |
Publication status | Published - Apr 2024 |
Bibliographical note
This study was conducted with support from the California Air Resources Board (Contract Number 14-754). The authors would like to specifically acknowledge Patrick Seames at CARB for the Fresno site support; Debbie Henson and David Cardiel at CARB for the Bakersfield site support; Kasia Turkiewicz in the CARB Air Quality Planning and Science Division; and Dr. Katharine Hammond at UC-Berkeley for collection of AE33 data.Publisher Copyright:
© The Author(s).
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Pollution