title: Size-resolved organic speciation of wintertime aerosols in California's Central Valley.
abstract: Size-resolved aerosol samples, including the entire ultrafine fraction, were simultaneously collected along a transect in California's Central Valley during the winter of 2009. The samples were analyzed for PAHs, alkanes, organic acids, and sugars. The results showed that the organic constituents of aerosols did not follow the same pattern as PM(10), thus indicating that simple PM measurements are not good indicators of trace toxic organic chemicals. Levoglucosan, a tracer of wood smoke, was the most abundant organic chemical detected, thus demonstrating the predominance of wood smoke in the valley. The size profile of levoglucosan showed a maximum in the 0.34-0.56 microm size mode, which is larger than published emission profiles. This suggests that wood smoke aerosols increased in size as they aged in the environment. Some chemicals, such as benzo[a]pyrene, had similar aerosol size profiles as levoglucosan and likely arose from the same source. Other chemicals, such as coronene and sugars, had very different size profiles, indicating that they have different sources. One unexpected result was the relatively large fraction of certain chemicals present in the ultrafine fraction, which highlights the importance of collecting the entire ultrafine fraction.
authors.affiliation: Division of Mathematical and Natural Sciences, Arizona State University at the West Campus, Phoenix, Arizona 85069, USA. tmcahill@asu.edu
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Cahill
mesh_terms: D000336:Aerosols / Q000032:analysis* / Q000737:chemistry*; D000473:Alkanes / Q000032:analysis; D002140:California; D002241:Carbohydrates / Q000032:analysis; D002264:Carboxylic Acids / Q000032:analysis; D017753:Ecosystem; D005843:Geography; D008970:Molecular Weight; D009930:Organic Chemicals / Q000032:analysis*; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis / Q000737:chemistry; D011084:Polycyclic Aromatic Hydrocarbons; D012621:Seasons
chemical_list: D000336:Aerosols; D000473:Alkanes; D002241:Carbohydrates; D002264:Carboxylic Acids; D009930:Organic Chemicals; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons