Photodegradation of secondary organic aerosol generated from limonene oxidation by ozone studied with chemical ionization mass spectrometry

Abstract

Abstract. Photodegradation of secondary organic aerosol (SOA) prepared by ozone-initiated oxidation of D-limonene is studied with an action spectroscopy approach, which relies on detection of volatile photoproducts with chemical ionization mass-spectrometry as a function of the UV irradiation wavelength. Efficient photodegradation is observed for a broad range of ozone (0.1-300 ppm) and D-limonene (0.02-3 ppm) concentrations used in the preparation of SOA. The observed photoproducts are dominated by oxygenated C1-C3 compounds such as methanol, formic acid, acetaldehyde, acetic acid, and acetone. The irradiation wavelength dependence of the combined yield of the photoproducts closely tracks the absorption spectrum of the SOA material suggesting that photodegradation is not limited to the UV wavelengths. Kinetic simulations suggest that RO 2 +HO 2 /RO 2 reactions represent the dominant route to photochemically active carbonyl and peroxide species in the limonene SOA prepared in these experiments. Similar photodegradation processes are likely to occur in realistic SOA produced by OHor O 3 -initiated oxidation of biogenic volatile organic compounds in clean air.

Biogenic oxidized organic functional groups in aerosol particles from a mountain forest site and their similarities to laboratory chamber products

“…The correlation between the product of crustal elements and BVOCs with the biogenic factor (r > 0.9) provides some support for this speculation. Strong correlations between the biogenic factor and the product of OM and BVOCs (r > 0.8) are consistent with the two-product model of SOA formation, indicating that SOA condensation onto pre-existing organic particles may play a limiting role (Pankow, 1994;Odum et al, 1996).…”

“…We apply Positive Matrix Factorization (PMF, using PMF2 software purchased from P. Paatero, Helsinki University, based on Paatero and Tapper, 1994) to separate the fraction of the OFG that is most closely associated with the same sources as the BVOC emissions. This method has been used previously on FTIR spectra to identify and separate combustion, wood burning, marine, and other sources (Russell et al, 2009aLiu et al, 2009;.…”

“…While the differences between atmospheric SOA and laboratory chamber SOA are expected given the lower levels of both oxidants and BVOCs at Whistler during the study period, the similarities provide an indication of which products are more common and more stable in the atmosphere. The absence of aldehyde groups in the ambient SOA could also result from the sampling methods, or it may indicate that aldehydes are too volatile or reactive to persist in atmospheric particles (Pan et al, 2009;Jang and Kamens, 2001). …”

Photoelectron spectroscopy of terpenoids and prediction of their rate constants in atmospheric oxidation reactions

“…These SOAs adversely affect visibility [8], the climate [9] and human health [10]. Recently, the role of terpenoids in the formation of SOAs has *Corresponding author (email: gemaofa@iccas.ac.cn) attracted considerable attention [11][12][13].…”

Where do herbivore-induced plant volatiles go?

“…The secondary organic aerosol particles formed from the same HIPV may have different chemical composition and different biological functions depending on the time of day during SOA formation. The size of SOA particles in the atmosphere may also grow by adsorption of other organic vapors to their surface (Kroll and Seinfeld, 2008) or the particles could be influenced by solar UV irradiation leading to the photolysis and formation of several oxygenated C1–C3 compounds (Pan et al, 2009). The reactions could also be reversible and low molecular mass carbon compounds may react again to form larger carbon-based molecules.…”