Formation of Polycyclic Aromatic Hydrocarbon Oxidation Products in α-Pinene Secondary Organic Aerosol Particles Formed through Ozonolysis

Abstract

Accurate long-range atmospheric transport (LRAT) modeling of polycyclic aromatic hydrocarbons (PAHs) and PAH oxidation products (PAH-OPs) in secondary organic aerosol (SOA) particles relies on the known chemical composition of the particles. Four PAHs, phenanthrene (PHE), dibenzothiophene (DBT), pyrene (PYR), and benz(a)anthracene (BaA), were studied individually to identify and quantify PAH-OPs produced and incorporated into SOA particles formed by ozonolysis of α-pinene in the presence of PAH vapor. SOA particles were characterized using realtime in-situ instrumentation, HR-ToF-AMS, and collected on quartz fiber filters for offline analysis of PAHs and PAH-OPs. PAH-OPs were measured in all PAH experiments at equal or greater concentrations than the individual PAHs they were produced from. The total mass of PAH and PAH-OPs, relative to the total SOA mass, varied for different experiments on individual parent PAHs: PHE and 6 quantified PHE-OPs (3.0%), DBT and dibenzothiophene sulfone (4.9%), PYR and 3 quantified PYR-OPs (3.1%), and BaA and benz(a)anthracene-7,12-dione (0.26%). Further exposure of PAH-SOA to ozone generally increased the concentration ratio of PAH-OPs to PAH, suggesting longer atmospheric lifetimes for PAH-OPs, relative to PAHs. These data indicate that PAH-OPs are formed during SOA particle formation and growth.

Effect of Biomass Burning on PM2.5 Composition and Secondary Aerosol Formation During Post‐Monsoon and Winter Haze Episodes in Delhi

“…The primary BBOA‐1 (O/C of 0.26 and 0.21 at HK and PF, respectively) contained abundant signals associated with PAH compounds at m/z 115, 128, 152, 165, 189, 202, 239 and 252 (Figure S9 in Supporting Information ), which are mostly associated with incomplete combustion of fuels containing organic material such as coal (Chen et al., 2005), wood (Simoneit, 2002), crop‐residue (Lu et al., 2009), fossil fuels (Fujita et al., 2007) and animal dung (Gadi et al., 2012). The PAH signals decreased both in intensity and number of m/z 's present (115, 152 and 165) in the partially oxidized BBOA‐2 (O/C of 0.28 and 0.34), and almost negligible in the most oxidized BBOA‐3 (O/C of 0.71 and 0.46) which could be because of its incorporation and assistance in the SOA formation processes as has been previously observed (Kramer et al., 2019; Zelenyuk et al., 2017). This was also supported by the presence of small amounts of PAH signals in the highly oxidized low‐volatile OOA (at m/z 115, 128, 152, 165 and 178) with an O/C of 0.77 and 1.03 at HK and PF, respectively, NO 3 ‐OA (at m/z 115, 152, 165 and 202) with an O/C of 0.9 and 1.0, and SO 4 ‐OA (at m/z 115 and 165) with an O/C of 1.2 and 1.1 (Figure S9 in Supporting Information ).…”

“…(2021) where dark oxidation of fresh BB emissions in the presence of NO x and O 3 resulted in high yields of NO 3 and NO 3 ‐related OA, and field studies related to the nighttime transformation of BB plumes (Decker et al., 2019). Further, the presence of high levels of VOCs (equivalent to the AGB period) related to BB (toluene and furan; Figure S15 in Supporting Information ) and PAH signals in NO 3 ‐OA mass spectra (Figure S9 in Supporting Information ), which could be due to adsorption onto SOA particles during their formation (Kramer et al., 2019; Zelenyuk et al., 2017), points toward BB as the major source of SOA. High levels of furans and phenols have been previously observed in Delhi during the late winter season in earlier studies (Wang et al., 2020).…”

The Parallel Transformations of Polycyclic Aromatic Hydrocarbons in the Body and in the Atmosphere

“…In the years since, a number of other classes of mutagenic metabolites ( Figure 1 ), such as quinones and diols, have since been detected in PM 80 , 81 , 92 and in controlled laboratory studies involving the oxidation of PAHs. 44 , 79 , 82 Recently, it was even shown that B[a]P-diol-epoxides (a class of compounds that includes BDPE, a potent carcinogen) were formed by the atmospheric oxidation of B[a]P. 40 Such studies affirm that atmospheric oxidation ( Figure 2 ) can form species that are the same as (or regioisomers of) those generated throughout the metabolic activation chain ( Figure 1 ).…”

“… 99 have recently shown that the position of OH groups on naphthalene derivatives determined bioactivity and, in some cases, which tissue was targeted. Therefore, comprehensive studies of PAH oxidation products 79 , 80 paired with toxicity studies of these products 99 and product mixtures 100 are needed to provide information on the toxicity of the full distribution of oxidized PAHs formed in the atmosphere.…”

“… 83 , 84 The formation of these general product classes are not specific to B[a]P: Heterogeneous oxidation also leads to the formation of similar oxidized products from other PAHs, such as phenanthrene, pyrene, and benz[a]anthracene. 79 Similarly, the oxidation of PAHs within ambient aerosol particles with and the OH radical 42 , 81 , 85 and radical 81 , 86 also results in the formation of catechols/quinones and nitro products.…”