Processing of atmospheric organic matter by California radiation fogs

Jeffrey L. Collett, Pierre Herckes, Sarah Youngster, Taehyoung Lee

Research output: Contribution to journalArticle

84 Citations (Scopus)

Abstract

Considerable effort has been put into characterizing the ionic composition of fogs and clouds over the past twenty-five years. Recently it has become evident that clouds and fogs often contain large concentrations of organic material as well. Here we report findings from a series of studies examining the organic composition of radiation fogs in central California. Organic compounds in these fogs comprise a major fraction of total solute mass, with total organic carbon sometimes reaching levels of several tens of mg/L. This organic matter is comprised of a wide variety of compounds, ranging from low molecular weight organic acids to high molecular weight compounds with molecular masses approaching several hundred to a thousand g/mole. The most abundant individual compounds are typically formic acid, acetic acid, and formaldehyde. High concentrations are also observed of some dicarboxylic acids (e.g., oxalate) and dicarbonyls (e.g., glyoxal and methylglyoxal) and of levoglucosan, an anhydrosugar characteristically emitted by biomass combustion. Many other compounds have been identified in fog water by GC/MS, including long chain n-alkanoic acids, n-alkanes, PAH, and others, although these compounds typically comprise a total of only a few percent of fog TOC. Measurements of fog scavenging of organic and elemental carbon reveal preferential scavenging of organic carbon. Tracking of individual organic compounds utilized as source type markers suggests the fogs differentially scavenge carbonaceous particles from different source types, with more active processing of wood smoke than vehicle exhaust. Observations of high deposition velocities of fog-borne organic carbon, in excess of 1 cm/s, indicate that fogs in the region represent an important mechanism for cleansing the atmosphere of pollution.

Original languageEnglish (US)
Pages (from-to)232-241
Number of pages10
JournalAtmospheric Research
Volume87
Issue number3-4
DOIs
StatePublished - Mar 2008

Fingerprint

fog
organic matter
organic compound
organic carbon
radiation
ionic composition
deposition velocity
formic acid
acid
oxalate
organic acid
formaldehyde
smoke
alkane
acetic acid
total organic carbon
solute
PAH
combustion
pollution

Keywords

  • Aerosol
  • Air pollution
  • Fog
  • Organic carbon
  • Source marker

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Processing of atmospheric organic matter by California radiation fogs. / Collett, Jeffrey L.; Herckes, Pierre; Youngster, Sarah; Lee, Taehyoung.

In: Atmospheric Research, Vol. 87, No. 3-4, 03.2008, p. 232-241.

Research output: Contribution to journalArticle

Collett, Jeffrey L. ; Herckes, Pierre ; Youngster, Sarah ; Lee, Taehyoung. / Processing of atmospheric organic matter by California radiation fogs. In: Atmospheric Research. 2008 ; Vol. 87, No. 3-4. pp. 232-241.
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