| Abstract
| - Measurements of C1−C15 alkyl nitrates, perchloroethylene,and bromoform at two different sampling sites nearSanta Cruz, CA, were conducted in 1995. The halocarbonswere used as marker molecules to differentiate the airparcels collected into marine and continental groups. Theaverage concentration of ∑n/i-C3−C12 alkyl nitrates atthe California Coast (19.3 pptv) was lower than the levelsobtained in the coastal mountains (53.9 pptv). Thisdifference was shown to be most significant for the longchain n/i-C6−C12 alkyl nitrates. It is concluded that the ≥C6alkyl nitrates in continental air can contribute 1−2% tothe total NOy. The results are summarized together withearlier data sets to give a picture of contemporary levels andof the global occurrence of C3−C12 alkyl nitrates. Incomparison with South Atlantic air (3.5 pptv), patternanalysis of n-alkyl nitrates suggests a marine source ofprimary n-alkyl nitrates. It is also shown that liquidchromatographic preseparation of the air sample extractsleads to a fraction that contains more polar organicnitrates. Several alkyl dinitrates and benzyl nitrate aredetected in air samples from California, the South Atlanticregion, and Europe. The vicinal alkyl dinitrates showincreased abundance in a nighttime sample. The relativeabundance of benzyl nitrate compared to alkyl (mono)nitrates is used as a tool for global air mass characterization.
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