title: Organic matter in central California radiation fogs.
abstract: Organic matter was studied in radiation fogs in the San Joaquin Valley of California during the California Regional Particulate Air Quality Study (CRPAQS). Total organic carbon (TOC) concentrations ranged from 2 to 40 ppm of C. While most organic carbon was found in solution as dissolved organic carbon (DOC), 23% on average was not dissolved inside the fog drops. We observe a clear variation of organic matter concentration with droplet size. TOC concentrations in small fog drops (<17 microm) were a factor of 3, on average, higher than TOC concentrations in larger drops. As much as half of the dissolved organic matter was determined to have a molecular weight higher than 500 Da. Deposition fluxes of organic matter in fog drops were high (0.5-4.3 microg of C m(-2) min(-1)), indicating the importance of fog processing as a vector for removal of organic matter from the atmosphere. Deposition velocities of organic matter, however, were usually found to be lower than deposition velocities for fogwater, consistent with the enrichment of the organic matter in smaller fog drops with lower terminal settling velocities.
authors.affiliation: Atmospheric Science Department, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Herckes
authors.forename: Taehyoung
authors.initials: T
authors.lastname: Lee
authors.forename: Laurie
authors.initials: L
authors.lastname: Trenary
authors.forename: Gongunn
authors.initials: G
authors.lastname: Kang
authors.forename: Hui
authors.initials: H
authors.lastname: Chang
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Collett
mesh_terms: D000392:Air Movements; D000396:Air Pollutants, Radioactive / Q000032:analysis*; D002140:California; D008970:Molecular Weight; D009930:Organic Chemicals / Q000032:analysis*; D014887:Weather
chemical_list: D000396:Air Pollutants, Radioactive; D009930:Organic Chemicals