| Autor: |
Kostenidou, Evangelia, Karnezi, Eleni, Hite Jr., James R., Bougiatioti, Aikaterini, Cerully, Kate, Lu Xu, Ng, Nga L., Nenes, Athanasios, Pandis, Spyros N. |
| Zdroj: |
Atmospheric Chemistry & Physics Discussions; 2017, p1-38, 38p |
| Abstrakt: |
The volatility distribution of the organic aerosol (OA) and its sources during the Southern Oxidant and Aerosol Study (SOAS; Centerville, Alabama) was constrained using measurements from an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a thermodenuder. Positive Matrix Factorization (PMF) analysis was applied on both the ambient and thermodenuded high resolution mass spectra, leading to four factors: more oxidized oxygenated OA (MO-OOA), less oxidized oxygenated OA (LO-OOA), an isoprene epoxydiols (IEPOX) related factor (Isoprene-OA) and biomass burning OA (BBOA). BBOA had the highest mass fraction remaining (MFR) at 100 °C, followed by the isoprene-OA, and the LO-OOA. Surprisingly the MO-OOA evaporated the most in the TD. The estimated effective vaporization enthalpies assuming an evaporation coefficient equal to unity were 58 ± 13 kJ mol-1 for the LO-OOA, 89 ± 10 kJ mol-1 for the MO-OOA, 55 ± 11 kJ mol-1 for the BBOA, and 63 ± 15 kJ mol-1 for the Isoprene-OA. The estimated volatility distribution of all factors covered a wide range including both semi-volatile and low-volatility components. BBOA had the lowest average volatility of all factors, even though it had the lowest O : C ratio among all factors. LO-OOA was the more volatile factor and its high MFR was due according to the model to its low enthalpy of vaporization. The Isoprene-OA factor had intermediate volatility, quite higher than suggested by a few other studies. The analysis suggests that deducing the volatility of a factor only from its MFR could lead to erroneous conclusions. The oxygen content of the factors can be combined with their estimated volatility and hygroscopicity to provide a better view of their physical properties. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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