Volatility and lifetime against OH heterogeneous reaction of ambient isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA)

Details

• Journal Title:
  Atmospheric Chemistry and Physics
• Personal Author:
  Hu, Weiwei ; Palm, Brett B. ; Day, Douglas A. ; Campuzano-Jost, Pedro ; Krechmer, Jordan E. ; Peng, Zhe ; de Sá, Suzane S. ; Martin, Scot T. ; Alexander, M. Lizabeth ; Baumann, Karsten ; Hacker, Lina ; Kiendler-Scharr, Astrid ; Koss, Abigail R. ; de Gouw, Joost A. ; Goldstein, Allen H. ; Seco, Roger ; Sjostedt, Steven J. ; Park, Jeong-Hoo ; Guenther, Alex B. ; Kim, Saewung ; Canonaco, Francesco ; Prévôt, André S. H. ; Brune, William H. ; Jimenez, Jose L.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CPO (Climate Program Office) ; ESRL (Earth System Research Laboratory) ; CIRES (Cooperative Institute for Research in Environmental Sciences)
• Description:
  Isoprene-epoxydiols-derived secondary organic aerosol (IEPOX-SOA) can contribute substantially to organic aerosol (OA) concentrations in forested areas under low NO conditions, hence significantly influencing the regional and global OA budgets, accounting, for example, for 16-36% of the submicron OA in the southeastern United States (SE US) summer. Particle evaporation measurements from a thermodenuder show that the volatility of ambient IEPOX-SOA is lower than that of bulk OA and also much lower than that of known monomer IEPOX-SOA tracer species, indicating that IEPOX-SOA likely exists mostly as oligomers in the aerosol phase. The OH aging process of ambient IEPOXSOA was investigated with an oxidation flow reactor (OFR). New IEPOX-SOA formation in the reactor was negligible, as the OFR does not accelerate processes such as aerosol up-take and reactions that do not scale with OH. Simulation results indicate that adding similar to 100 mu g m(-3) of pure H2SO4 to the ambient air allows IEPOX-SOA to be efficiently formed in the reactor. The heterogeneous reaction rate coefficient of ambient IEPOX-SOA with OH radical (k(OH) /was estimated as 4.0 +/- 2.0 x 10(-13) cm(3) molec(-1) s(-1), which is equivalent to more than a 2-week lifetime. A similar k(OH) was found for measurements of OH oxidation of ambient Amazon forest air in an OFR. At higher OH exposures in the reactor (> 1 x 10(12) molec cm(-3) s), the mass loss of IEPOX-SOA due to heterogeneous reaction was mainly due to revolatilization of fragmented reaction products. We report, for the first time, OH reactive uptake coefficients (gamma(OH) = 0.59 +/- 0.33 in SE US and gamma(OH) = 0.68 +/- 0.38 in Amazon) for SOA under ambient conditions. A relative humidity dependence of k(OH) and gamma(OH) was observed, consistent with surface-area-limited OH uptake. No decrease of k(OH) was observed as OH concentrations increased. These observations of physicochemical properties of IEPOX-SOA can help to constrain OA impact on air quality and climate.
• Source:
  Atmospheric Chemistry and Physics, 16(18), 11563-11580.
• DOI:
  https://doi.org/10.5194/acp-16-11563-2016
• Document Type:
  Journal Article
• Funding:
  Grant no. NA13OAR4310063
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:0cfeabb34869f940c49010b24e18d1e823c297614e162c2fde8da0c8850f5e69
• Download URL:
  https://repository.library.noaa.gov/view/noaa/21630/noaa_21630_DS1.pdf
• File Type:
  [PDF - 1.61 MB ]