Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.668 IF 5.668
  • IF 5-year value: 6.201 IF 5-year
    6.201
  • CiteScore value: 6.13 CiteScore
    6.13
  • SNIP value: 1.633 SNIP 1.633
  • IPP value: 5.91 IPP 5.91
  • SJR value: 2.938 SJR 2.938
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 174 Scimago H
    index 174
  • h5-index value: 87 h5-index 87
Volume 14, issue 13
Atmos. Chem. Phys., 14, 6941-6952, 2014
https://doi.org/10.5194/acp-14-6941-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 14, 6941-6952, 2014
https://doi.org/10.5194/acp-14-6941-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 04 Jul 2014

Research article | 04 Jul 2014

Atmospheric photochemistry of aromatic hydrocarbons: OH budgets during SAPHIR chamber experiments

S. Nehr1,*, B. Bohn1, H.-P. Dorn1, H. Fuchs1, R. Häseler1, A. Hofzumahaus1, X. Li1, F. Rohrer1, R. Tillmann1, and A. Wahner1 S. Nehr et al.
  • 1Institut für Energie- und Klimaforschung, IEK-8: Troposphäre, Forschungszentrum Jülich GmbH, Jülich, Germany
  • *now at: Verein Deutscher Ingenieure e.V., Kommission Reinhaltung der Luft, Düsseldorf, Germany

Abstract. Current photochemical models developed to simulate the atmospheric degradation of aromatic hydrocarbons tend to underestimate OH radical concentrations. In order to analyse OH budgets, we performed experiments with benzene, toluene, p-xylene and 1,3,5-trimethylbenzene in the atmosphere simulation chamber SAPHIR. Experiments were conducted under low-NO conditions (typically 0.1–0.2 ppb) and high-NO conditions (typically 7–8 ppb), and starting concentrations of 6–250 ppb of aromatics, dependent on OH rate constants. For the OH budget analysis a steady-state approach was applied in which OH production and destruction rates (POH and DOH) have to be equal. The POH were determined from measurements of HO2, NO, HONO, and O3 concentrations, considering OH formation by photolysis and recycling from HO2. The DOH were calculated from measurements of the OH concentrations and total OH reactivities. The OH budgets were determined from DOH/POH ratios. The accuracy and reproducibility of the approach were assessed in several experiments using CO as a reference compound where an average ratio DOH/POH = 1.13 ± 0.19 was obtained. In experiments with aromatics, these ratios ranged within 1.1–1.6 under low-NO conditions and 0.9–1.2 under high-NO conditions. The results indicate that OH budgets during photo-oxidation experiments with aromatics are balanced within experimental accuracies. Inclusion of a further, recently proposed OH production via HO2 + RO2 reactions led to improvements under low-NO conditions but the differences were small and insignificant within the experimental errors.

Publications Copernicus
Download
Citation
Share