Seasonal and Annual Source Appointment of Carbonaceous Ultrafine Particulate Matter (PM0.1) in Polluted California Cities

• Published in: Environmental science & technology Vol. 53; no. 1; pp. 39 - 49
• Main Authors: Xue, Jian, Xue, Wei, Sowlat, Mohammad H, Sioutas, Constantinos, Lolinco, Annabelle, Hasson, Alam, Kleeman, Michael J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.01.2019
• Subjects: Aerosols; Air pollution; Airborne particulates; Burning; Carbon; Carbon fiber reinforcement; Carbon fibers; Combustion; Cooking; Diesel; Diesel fuels; Fuel combustion; Gasoline; Markers; Mathematical analysis; Meat; Organic carbon; Particulate emissions; Particulate matter; Silicon carbide fiber; Smoke; Ultrafines; Volatility; Wood; Los Angeles California; United States > US; California
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.8b04404

Samples of ultrafine particle matter mass (PM0.1) were collected over 12 months at three cities in California: Los Angeles, East Oakland, San Pablo, and over six months at Fresno. Molecular markers adjusted for volatility and reactivity were used to calculate PM0.1 source contributions. Wood burning was a significant source of PM0.1 organic carbon (OC) during the winter months in northern California (17–47%) but made smaller contributions in other months (0–8%) and was minor in all seasons in Los Angeles (0–5%), except December (17%) during holiday celebrations. Meat cooking was the largest source of PM0.1 OC across all sites (13–29%), followed by gasoline combustion (7–21%). Motor oil and diesel fuel combustion made smaller contributions to PM0.1 OC (3–10% and 3–7%, respectively). Unresolved sources accounted for 22–56% of the PM0.1 OC. The lack of a clear seasonal profile for this unresolved OC suggests that it may be a primary source rather than secondary organic aerosol (SOA). PM0.1 elemental carbon (EC) was dominated by diesel fuel combustion with less than 15% contribution from other sources. All sources besides wood smoke exhibited relatively constant seasonal source contributions to PM0.1 OC reflecting approximately constant emissions over the annual cycle. Annual-average source contributions to PM0.1 OC calculated with traditional molecular markers were similar to the source contributions calculated with the modified molecular markers that account for volatility and reactivity.