Speakers
Description
Aldehydes are very important trace gases for the physical chemistry of the troposphere mainly because they are directly emitted into the atmosphere or formed in situ from the photooxidation of organic compounds. In particular, the unsaturated aldehyde trans-2-methyl-2-pentenal (T2M2P) is emitted into the low atmosphere from several sources such as wildland fires, vegetation, and from some foods. Once in the troposphere, T2M2P can be degraded through gas-phase reactions initiated by diurnal oxidants such as hydroxyl radicals (OH) or chlorine atoms (Cl), important globally or locally in marine atmospheres, respectively. Therefore, it is important to understand these reactions kinetically and to identify the products that are formed. The rate coefficient for the OH-reaction of T2M2P (k$_O$$_H$) has been previously estimated [1], but neither kinetic measurements of the Cl-reaction nor detection of the reaction products have been reported in the literature up to date. Then, the aim of this work is, first, to evaluate the gas-phase reactivity of Cl atoms towards T2M2P at 298 K and 1 atm, by determining the rate coefficient (k$_C$$_l$) has been determined by the relative method in a smog chamber coupled to a Fourier Transform Infrared spectrometer to monitor the loss of T2M2P and a reference compound [2]. Secondly, the chemical characterization and quantification of the gas-phase reaction products have been performed in a smog chamber coupled to a Proton Transfer Reaction – Time of Flight – Mass Spectrometer [3] and a Fast Mobility Particle Sizer spectrometer has been used to monitor the formation of Secondary Organic Aerosols (SOAs) and to determine the SOA yield in the Cl+T2M2P reaction [4].
Finally, the atmospheric implications of the T2M2P reactivity will be discussed in terms of its lifetime due to the homogeneous reaction with Cl estimated from the determined k$_C$$_l$ and the literature k$_O$$_H$ and in terms of the potential impact of the products generated on our health.
References
[1] Grosjean, D.; Williams, ED. Atmospheric Environment, 1992, 1395-1405.
[2] Ballesteros, B.; Jiménez, E.; Moreno, A.; Soto, A.; Antiñolo, M.; Albaladejo, J. Chemosphere, 2017, 167, 330-343.
[3] Asensio, M.; Antiñolo, M.; Blázquez, S.; Albaladejo, J.; Jiménez, E. Atmospheric Chemistry and Physics, 2022, 22, 2689-2701.
[4] Antiñolo, M.; Asensio, M.; Albaladejo, J.; Jiménez, E. Atmosphere, 2020, 11, 715 (17).
