Abstract. A large number of oxygenated organic chemicals (peroxyacyl nitrates, alkyl nitrates, acetone, formaldehyde, methanol, methylhydroperoxide, acetic acid and formic acid) were measured during the 1997 Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) airborne field campaign over the Atlantic. In this paper, we present a first picture of the distribution of these oxygenated organic chemicals (Ox-organic) in the troposphere and the lower stratosphere, and assess their source and sink relationships. In both the troposphere and the lower stratosphere, the total atmospheric abundance of these oxygenated species (ZOx-organic) nearly equals that of total nonmethane hydrocarbons (ZNMHC), which have been traditionally measured.

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Profiles of the sources of nonmethane organic compounds (NMOCs) were developed for emissions from vehicles, petroleum fuels (gasoline, liquefied petroleum gas [LPG], and natural gas), a petroleum refinery, a smelter, and a cast iron factory in Cairo, Egypt. More than 100 hydrocarbons and oxygenated hydrocarbons were tentatively identified and quantified. Gasoline-vapor and whole-gasoline profiles could be distinguished from the other profiles by high concentrations of the C 5 and C 6 saturated hydrocarbons. The vehicle emission profile was similar to the whole-gasoline profile, with the exception of the unsaturated and aromatic hydrocarbons, which were present at higher concentrations in the vehicle emission profile. High levels of the C 2 -C 4 saturated hydrocarbons, particularly n-butane, were characteristic features of the petroleum refinery emissions. The smelter and cast iron factory emissions were similar to the refinery emissions; however, the levels of benzene and toluene were greater in the former two sources. The LPG and natural gas emissions contained high

A static chamber technique for measuring emissions of nonmethane organic compounds (NMOCs) from soil surfaces and herbaceous vegetation in a natural setting has been developed. The technique involves the insertion of a polymethyl methacrylate frame into the ground. A polycarbonate chamber is placed in a water‐containing trough on the frame to seal the chamber to the surface. The soil surface and vegetation are covered for various lengths of time, and samples of the chamber air are passively collected in preevacuated stainless steel canisters. The samples are analyzed in the laboratory by a whole‐air cryogenic‐preconcentration/high‐resolution gas chromatographic technique with flame ionization detection. Changes in the concentrations of the NMOCs with time in the chamber are used to derive emission rates. The technique is sensitive and precise, but the occasional observation of nonlinear changes in NMOC concentrations in the chamber with the length of the covering period limits the accuracy of emission rates derived by this technique. Despite this limitation, the method is effective for identifying NMOC emissions and investigating seasonal variations of emission rates.

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