Radiocarbon Concentration of California Aerosols

Abstract

In this study the origin of the carbonaceous fraction of total suspended particles (TSP) in air was analyzed. While the summer data show increasing carbon concentrations in the Los Angeles air basin from west to east, in the winter high levels of carbon particles can be found over the coast. The smallest and most dangerous particle fraction is principally composed of fossil carbon.

Relative contributions of fossil and contemporary carbon sources to PM 2.5 aerosols at nine Interagency Monitoring for Protection of Visual Environments (IMPROVE) network sites

“…The 14 C data reveal that the two urban network sites: Puget Sound and Phoenix had the highest average total and fossil carbon mass loadings of the nine sites with fossil carbon loadings typically comprising around half of the total PM 2.5 aerosol carbon mass loading. These fractional loading values are consistent with other 14 C analyses of aerosols collected at urban sampling locations in Nashville, TN [ Lewis et al , 2004], Zurich, Switzerland [ Szidat et al , 2004], Houston, TX [ Lemire et al , 2002] and Downtown Los Angeles, CA [ Berger et al , 1986] where fossil carbon typically comprised one third to two thirds of the total aerosol carbon. At both urban sites, the total and contemporary aerosol carbon loadings were significantly higher for the winter than for the summer sampling season while the fossil carbon loading was significantly higher in winter only at Phoenix.…”

“…[30] The data presented here as well as that from many prior studies have shown a sizable contribution to the total aerosol carbon loading from contemporary carbon [Dzubay et al, 1982;Currie et al, 1983;Berger et al, 1986;Kaplan and Gordon, 1994;Hildemann et al, 1994;Lemire et al, 2002;Bench and Herckes, 2004;Lewis et al, 2004;Szidat et al, 2004;Tanner et al, 2004;Lewis and Stiles, 2006]. Consequently, it is worthy to examine sources of uncertainty that might cause the measured contemporary carbon contents to be artificially high.…”

Fine particulate matter source attribution for Southeast Texas using 14C/13C ratios

“…The measured biogenic carbon fraction varied from 18% to 62% with a mean value of 40% ± 15% [standard uncertainty (deviation) u ]. This was the first experimental indication that biogenic sources may contribute significantly to fine aerosol in Houston, and is consistent with later 14 C results from Los Angeles that also showed a surprisingly high biogenic contribution to fine aerosol [ Currie et al , 1983; Berger et al , 1986; Kaplan and Gordon , 1994; Hildemann et al , 1996]. …”

Biogenic contributions to atmospheric volatile organic compounds in Azusa, California

“…[63] The biogenic VOC results reported here are the first ever in the Los Angeles region using a radiocarbon methodology. However, several previous studies have applied radiocarbon measurements to Los Angeles ambient aerosol [Currie et al, 1983;Berger et al, 1986;Kaplan and Gordon, 1994;Hildemann et al, 1996]. The surprisingly high biogenic fractions found in some of those studies for aerosol, which potentially includes secondary aerosol formed from biogenic VOC precursors, may provide indirect support for the plausibility of the nonnegligible levels of biogenic VOC measured in the present study.…”