C1-C15 alkyl nitrates, benzyl nitrate, and bifunctional nitrates:: Measurements in California and South Atlantic air and global comparison using C2Cl4 and CHBr3 as marker molecules

Measurements of C-1-C-15 alkyl nitrates, perchloroethylene, and bromoform at two different sampling sites near Santa Cruz, CA, were conducted in 1995. The halocarbons were used as marker molecules to differentiate the air parcels collected into marine and continental groups. The average concentration of Sigma n/i-C-3-C-12 alkyl nitrates at the California Coast (19.3 pptv) was lower than the levels obtained in the coastal mountains (53.9 pptv). This difference was shown to be most significant for the long chain n/i-C-6-C-12 alkyl nitrates. It is concluded that the greater than or equal to C-6 alkyl nitrates in continental: air can contribute 1-2% to the total NO, The results are summarized together with earlier data sets to give a picture of contemporary levels and of the global occurrence of C-3-C-12 alkyl nitrates. In comparison with South Atlantic air (3.5 pptv), pattern analysis of n-alkyl nitrates suggests a marine source of primary n-alkyl nitrates. It is also shown that liquid chromatographic preseparation of the air sample extracts leads to a fraction that contains more polar organic nitrates. Several alkyl dinitrates and benzyl nitrate are detected in air samples from California, the South Atlantic region, and Europe. The vicinal alkyl dinitrate's show increased abundance in a nighttime sample.;The relative abundance of benzyl nitrate compared to alkyl(mono) nitrates is used as a tool for global air mass characterization.