Measurements of Volatile Organic Compounds (VOC) During POPCORN 1994: Applying a New On-Line GC–MS-Technique

摘要: Atmospheric concentrations of ca. 250 C6–C15 hydrocarb on and C4–C12 oxygenated volatile organic compounds (VOC) including alkanes, benzene alkyl benzenes, monoterpenes aldehydes were measured in August 1994 during the POPCORN campaign (POPCORN = Photo-Oxidant formation by Plant emitted Compounds OH Radicals North-Eastern Germany). About 80 substances together contributed 90% atmospheric carbon this range molecular weight. During field VOC-emissions from several crop tree species ambient CO, C2–C7 non-methane hydrocarbons (NMHC), C1 C2 aldehydes, nitrogen oxides, ozone hydroxyl-radicals (OH) also measured. These data used to interpret VOC measurements presented here. The on-line GC–MS for combines adsorptive sampling with thermal desorption analysis an automated system. Internal standards quantify measurements. Ozone was destroyed prior sample preconcentration through gas phase reaction NO. Aromatic like benzene, toluene xylenes most abundant compound class among substances, α-pinene Δ3-carene, probably originating pineforests 1 km away measuring site, monoterpenes. highest mixing ratios nights strong inversion situations. then reached 630 pptv; went up 430 pptv. median all 125 pptv or 22 pptv, respectively. values are lower end reported continental sites. In samples n-pentanal, n-hexananl, n-nonanal n-undecanal present. Median 9, 16, 14 8 Emission studies indicate that these highly reactive maize. It is shown a simple first order approach potential roughly equal anthropogenic biogenic VOC. From ozone, OH-radicals, methane, C2–C15 nonmethane (NMHC) C5–C11 photochemical production 3.5 ppb/h can be estimated. Apart formaldehyde acetaldehyde, which at least partly products oxidation, substance group largest contribution turnover They contribute 30%. However, mechanism terpene oxidation very complex presently only understood. Thus actual uncertain. Other classes such as light alkenes, aromatics, each between 10% 15% formation. site not influenced directly sources, results obtained regarded typical picture remote rural central European environment.