title: Aqueous benzene-diols react with an organic triplet excited state and hydroxyl radical to form secondary organic aerosol.
abstract: Chemical processing in atmospheric aqueous phases, such as cloud and fog drops, can play a significant role in the production and evolution of secondary organic aerosol (SOA). In this work we examine aqueous SOA production via the oxidation of benzene-diols (dihydroxy-benzenes) by the triplet excited state of 3,4-dimethoxybenzaldehyde, (3)DMB*, and by hydroxyl radical, ˙OH. Reactions of the three benzene-diols (catechol (CAT), resorcinol (RES) and hydroquinone (HQ)) with (3)DMB* or ˙OH proceed rapidly, with rate constants near diffusion-controlled values. The two oxidants exhibit different behaviors with pH, with rate constants for (3)DMB* increasing as pH decreases from pH 5 to 2, while rate constants with ˙OH decrease in more acidic solutions. Mass yields of SOA were near 100% for all three benzene-diols with both oxidants. We also examined the reactivity of atmospherically relevant mixtures of phenols and benzene-diols in the presence of (3)DMB*. We find that the kinetics of phenol and benzene-diol loss, and the production of SOA mass, in mixtures are generally consistent with rate constants determined in experiments containing a single phenol or benzene-diol. Combining our aqueous kinetic and SOA mass yield data with previously published gas-phase data, we estimate a total SOA production rate from benzene-diol oxidation in a foggy area with significant wood combustion to be nearly 0.6 μg mair(-3) h(-1), with approximately half from the aqueous oxidation of resorcinol and hydroquinone, and half from the gas-phase oxidation of catechol.
authors: Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave., Davis, CA 95616, USA. canastasio@ucdavis.edu.
authors: Jeremy D
authors: JD
authors: Smith
authors: Haley
authors: H
authors: Kinney
authors: Cort
authors: C
authors: Anastasio
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D002396:Catechols / Q000737:chemistry; D006873:Hydroquinones / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D012118:Resorcinols / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000336:Aerosols; D002396:Catechols; D006873:Hydroquinones; D009930:Organic Chemicals; D012118:Resorcinols; D014867:Water; D017665:Hydroxyl Radical; D001554:Benzene; C034221:catechol; C031927:hydroquinone; C031389:resorcinol