Efficient Formation\nof Secondary Organic Aerosols\nfrom the Aqueous Oxidation of Terpenoic 1,2-Diols by OH

Aqueous oxidation of pinanediol (PND) and camphanediol\n(CND) by\nhydroxyl radical (OH) was investigated using gas and liquid chromatography\ncoupled with mass spectrometry. The yields of the products formed\nwere measured with authentic and surrogate standards. This approach\nquantified >97% of the products for both reactions under investigation.\nFor the first time, the formation of 3-methyl-1,2,3-butanetricarboxylic\nacid (MBTCA) and other terpenoic acids (TAs) from the aqueous OH reaction\nwith PND was confirmed with authentic standards. Based on the data\nacquired, mechanisms of OH oxidation of PND and CND were proposed.\nThe yields of <sub>aq</sub>SOAs were evaluated by combining kinetic\nand air–water partitioning models developed for the the precursors,\nPND and CND, and for the first-generation products: <i>cis</i>-pinonic and camphoric acids. Modeled yields of <sub>aq</sub>SOAs\nranged from 0.05 to 2.5. At liquid water content (LWC) from 1 ×\n10<sup>–4</sup> to 4 × 10<sup>–3</sup> (g ×\nm<sup>–3</sup>, haze, and fogs), oxidized TAs were the major\ncomponents of <sub>aq</sub>SOAs. In clouds with LWC > 0.06 (g ×\nm<sup>–3</sup>), the contribution of nonacidic products to\nthe mass of <sub>aq</sub>SOAs became dominant. Aqueous OH reaction\nwith PND can produce up to 0.3 (Tg × yr<sup>–1</sup>)\nof <sub>aq</sub>SOA, assuming the average flux of the precursor at\n0.5 (Tg × yr<sup>–1</sup>).