Larger Submicron Particles for Emissions With Residential Burning in Wintertime San Joaquin Valley (Fresno) than for Vehicle Combustion in Summertime South Coast Air Basin (Fontana)

Abstract

Size‐resolved composition of atmospheric aerosol particles during winter (19 December 2014 to 13 January 2015) in the San Joaquin Valley at Fresno and during summer (4 to 28 July 2015) in the Southern California Air Basin at Fontana were measured by aerosol mass spectrometer, Fourier transform infrared spectrometer, single particle soot photometer, and scanning electrical mobility sizer. The Fresno study had low‐fog and high‐fog winter conditions, and residential burning was a frequent contributor to evening emissions. Fireworks during Fourth of July celebrations characterized the start of the Fontana study; the remaining days were categorized as nonfirework days and were mostly affected by traffic emissions. Fresno had particle distributions with number mode diameters of 70–150 nm, and Fontana had 30–50‐nm diameters. The nonrefractory organic mass mode diameters were also larger at Fresno (250–380 nm in dry mobility diameter) than at Fontana (130–150 nm, 280 nm in dry mobility diameter) as were refractory black carbon particles (Fresno: 80–180 nm; Fontana: 80–100 nm in dry volume equivalent diameter). The size dependence of organic contributions to particle mass indicated that condensation or other surface‐limited processes contributed oxidized organic fractions to aerosol mass in Fontana but that volume‐limited aqueous reactions produced organic mass on both low‐fog and high‐fog days in Fresno. Linear regression analysis of organic aerosol sources with size‐resolved particle volume at different times of day also showed that residential burning‐related particles increased from 70–160 nm in the evening (18:00 to 23:59) to 150–260 nm at night (00:00 to 05:59) on low‐fog days.

Organic Aerosol Particle Chemical Properties Associated With Residential Burning and Fog in Wintertime San Joaquin Valley (Fresno) and With Vehicle and Firework Emissions in Summertime South Coast Air Basin (Fontana)

“…The average AMS nonrefractory PM 1 concentration was 7.2 ± 5.8 μg/m 3 at Fontana, with much higher concentrations on firework (14.7 ± 8.5 μg/m 3 ) days than on nonfirework (5.9 ± 2.6 μg/m 3 ) days (Figure and Table ). OM concentrations and functional group fractions in PM 1 are similar to those in PM 2.5 for Fontana (Betha et al, ), showing that most of the OM is submicron. The alkane group constituted the majority of the PM 1 OM (49%), followed by alcohol (29%), carboxylic acid (15%), amine (7%), and nonacid carbonyl (1%) groups.…”

Light Absorption by Ambient Black and Brown Carbon and its Dependence on Black Carbon Coating State for Two California, USA, Cities in Winter and Summer

“…Refractory black carbon (rBC; Lack et al, ) concentrations and BC‐specific particle size distributions were measured using the SP2 instrument at both the Fresno and Fontana sites. While the operation of the SP2 has been previously discussed for these studies (Betha et al, ), further details are provided here and in Appendix . The SP2 measures the concentration of rBC within individual rBC‐containing particles.…”

Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

“…The whole sampling period can be divided into four categories as previously reported Betha et al, 2018). In brief, fireworks had strong impacts on aerosol compositions from 5 to 8 July, and significant enhancements of inorganic aerosol components were observed in rBC-containing particles (Fig.…”

“…Hourly average ozone data was obtained from the co-located SCAQM air monitoring station. Measurements were performed from 5 to 28 July 2015 with ambient temperature varying from 14.9 to 35.9 • C. Companion studies have shown that aerosol compositions were strongly influenced by fireworks from 4 to 8 July 2015 Betha et al, 2018). There were few clouds and little precipitation with the exception of a short storm with high rainfall and winds on 18-19 July (2-day precipitation = 3.6 cm and maximum wind speed = 10 ms −1 ).…”

“…2.2 and 2.3 for the descriptions of the SP-AMS and the calibration approach, respectively). The details of other particle instruments, including a HR-ToF-AMS (Aerodyne Research), a single-particle soot photometer (SP2, Droplet Measurement Technologies), and a scanning electrical mobility spectrometer (SEMS, Brechtel), have been reported in Chen et al (2018) and Betha et al (2018). Two nitrogen oxide analyzers (model 42i and 42i NO y , Thermo Fisher Scientific) were used to measure mixing ratios of NO x and NO y for determining photochemical age (PCA) of air masses.…”