Measurements of organic gases during aerosol formation events in the boreal forest atmosphere during QUEST

Abstract

Abstract. Biogenic VOCs are important in the growth and possibly also in the early stages of formation of atmospheric aerosol particles. In this work, we present 10 min-time resolution measurements of organic trace gases at Hyytiälä, Finland during March 2002. The measurements were part of the project QUEST (Quantification of Aerosol Nucleation in the European Boundary Layer) and took place during a twoweek period when nucleation events occurred with various intensities nearly every day. Using a ground-based Chemical Ionization Mass Spectrometer (CIMS) instrument, the following trace gases were detected: acetone, TMA, DMA, mass 68 amu (candidate=isoprene), monoterpenes, methyl vinyl ketone (MVK) and methacrolein (MaCR) and monoterpene oxidation products (MTOP). For all of them except for the amines, we present daily variations during different classes of nucleation events, and non-event days. BVOC oxidation products (MVK, MaCR and MTOP) show a higher ratio to the CS on event days compared to non-event days, indicating that their abundance relative to the surface of aerosol available is higher on nucleation days. Moreover, BVOC oxidation products are found to show significant correlations with the condensational sink (CS) on nucleation event days, which indicates that they are representative of less volatile organic compounds that contribute to the growth of the nucleated particles and generally secondary organic aerosol formation. Behaviors of BVOC on event and non event days are compared to the behavior of CO.

Ozonolysis of Trimethylamine Exchanged with Typical Ammonium Salts in the Particle Phase

“…This means that ammonium is replaced by TMA. The reaction is similar to a previous work where NH 3 has been identified as a gas-phase product of the reaction between methylamine and ammonium. 51 In Figure 1, the negative peak at 1080 cm −1 due to v s (SO 4 2− ) 50 can be explained by a part of the sulfate transforming into bisulfate due to TMA or NH 3 evaporation from TMAH sulfate or (NH 4 ) 2 SO 4 particles, which is similar to the transformation of TEAH sulfate to TEAH bisulfate observed using Raman spectroscopy.…”

“…The results further rationalized the assignment for the peaks identified in the IR spectra (Figures 3 and S3). In particular, the band at 3756 cm −1 was assigned to the v s (OH) of CH 3 N(OH)CHO or CH 3 NHOH, which is close to the calculated value at 3677 cm −1 (3771 cm −1 with unscaled frequency) for CH 3 N(OH)-CHO and 3730 cm −1 for CH 3 NHOH, and the other IR bands Table S2. This means that CH 3 N(OH)CHO or CH 3 NHOH may be formed during ozonolysis of particulate TMA.…”

“…Based on the products observed in this work, the oxidation paths of particulate TMA by O 3 can be summarized in Figure 6. As shown in Figure S6, the symmetry of the highest occupied molecular orbital (HOMO) of TMA matches with that of the lowest unoccupied molecular orbital (LUMO) of O 3 , while it does not between the HOMO of TMAH + and the LUMO of O 3 . This means molecular TMA rather than TMAH + can be oxidized by O 3 .…”

“…The reaction chamber consisted of a ZnSe crystal and a sealed Teflon cover with entry and exit ports. The surface-tovolume ratio was 2 cm −1 with a volume of 44 cm 3 . More details about the reactor was shown in the Supporting Information ( Figure S1).…”

Bisulfate – cluster based atmospheric pressure chemical ionization mass spectrometer for high-sensitivity (< 100 ppqV) detection of atmospheric dimethyl amine: proof-of-concept and first ambient data from boreal forest

“…For example, from the SMEAR II field station (Hyytiälä, southern Finland; Hari and Kulmala, 2005), where the nucleation process has been seriously investigated for two decades, there are no reliable data for amine concentrations. First attempts to quantify concentrations of dimethyl or ethyl amine (DMA/EA) and trimethyl or propyl amine (TMA/PA) were performed by Sellegri et al (2005), who applied an ambient pressure protonated water cluster-based chemical ionization mass spectrometer. Sellegri et al (2005) reported observations of TMA with the concentration exceeding 10 pptV.…”