Deployment of a ground-based CIMS apparatus for the detection of organic gases in the boreal forest during the QUEST campaign

[摘要] Measurements of atmospheric volatile organic compounds were performed in theFinnish Boreal forest atmosphere during spring 2003, as part of the projectQUEST (Quantification of Aerosol Nucleation in the European Boundary Layer),using a ground-based Chemical Ionization Mass Spectrometer (CIMS)instrument. Based on the study of their hydrate distribution, methanol,acetonitrile, acetaldehyde, dimethyl amine (DMA), ethanol/formic acid,acetone, trimethyl amine (TMA), propanol/acetic acid, isoprene, methyl vinylketone (MVK) and metacrolein (MaCR), monoterpenes and monoterpene oxidationproduct (MTOP) are proposed as candidates for masses 32, 41, 44, 45, 46, 58,59, 60, 68, 70, 136, and 168amu, respectively. It would be, to ourknowledge, the first time DMA, TMA and MTOP are measured with this method.Most compounds show a clear diurnal variation with a maximum in the earlynight, corresponding to the onset of the noctural inversion and in agreementwith independant measurements of CO. Biogenic compounds are highlycorrelated with each other and the ratio monoterpene/oxidation product showsa typical daily pattern of nightime maxima. However, because isoprene mixingratios are also maximum during the early night, it is likely that it suffersof the interference from another unidentified biogenic compound. Hence mass68amu is identified as isoprene+compound X.

[学科分类] 大气科学