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| Titel |
Photo-induced formation of nitrous acid (HONO) on protein surfaces |
| VerfasserIn |
Hannah Meusel, Yasin Elshorbany, Thorsten Bartels-Rausch, Kathrin Selzle, Jos Lelieveld  , Markus Ammann, Ulrich Pöschl, Hang Su, Yafang Cheng |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088099
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| Publikation (Nr.) |
 EGU/EGU2014-2174.pdf |
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| Zusammenfassung |
| The study of nitrous acid (HONO) is of great interest, as the photolysis of HONO leads to the
OH radical, which is the most important oxidant in the troposphere. HONO is directly
emitted by combustion of fossil fuel and from soil biogenic nitrite (Su et al., 2011), and can
also be formed by gas phase reactions of NO and OH and heterogeneous reactions of NO2.
Previous atmospheric measurements have shown unexpectedly high HONO concentrations
during daytime. Measured mixing ratios were about one order of magnitude higher than
model simulations (Kleffmann et al. 2005, Vogel et al. 2003). The additional daytime
source of HONO might be attributed to the photolysis of adsorbed nitric acid or
heterogeneous photochemistry of NO2 on organic substrates, such as humic acids or
polyphenolic compounds (Stemmler et al., 2006), or indirectly through nitration of
phenols and subsequent photolysis of nitrophenols (Sosedova et al., 2011, Bejan et al.,
2006).
An important reactive surface for the heterogeneous formation of HONO could
involve proteins, which are ubiquitous in the environment. They are part of coarse
biological aerosol particles like pollen grains, fine particles (fragments of pollen,
microorganism, plant debris) and dissolved in rainwater, soil and road dust (Miguel et al.
1999).
In this project a thin film of bovine serum albumin (BSA), a model protein with 67 kDa
and 21 tyrosine residues per molecule, is irradiated and exposed to nitrogen dioxide in
humidified nitrogen. The formation of HONO is measured with long path absorption
photometry (LOPAP). The generated HONO is in the range of 100 to 1100 ppt depending
on light intensity, NO2 concentration and film thickness. Light induced HONO
formation on protein surfaces is stable over the 20-hours experiment of irradiation and
exposure. On the other hand, light activated proteins reacting with NO2 form nitrated
proteins, as detected by liquid chromatography (LC-DAD). Our experiments on
tetranitromethane (TNM) nitrated ovalbumin (OVA) also show a clear light induced
decomposition of nitrated proteins with HONO identified as one of the major products.
This suggests a shortening of the lifetime of nitrated proteins during daytime. Our
results indicate an important role of light to the fate of proteins, and through HONO,
important OH precursors. Proteins and nitrated proteins on aerosol and ground surfaces
may therefore influence the atmospheric chemistry and contribute to the oxidation
capacity.
References
Bejan, I. et al., Physical Chemistry Chemical Physics 2006, 8 (17), 2028-2035.
Kleffmann, J. et al., Geophysical Research Letters 2005, 32 (5).
Miguel, A. G. et al., Environmental Science & Technology 1999, 33 (23), 4159-4168.
Sosedova, Y., et al., Photochemical and Photobiological Sciences 2011, 10,
1680-1690.
Stemmler, K. et al., Nature 2006, 440 (7081), 195-198.
Su et al., Science 2010, 333, 1616-1618.
Vogel, B. et al., Atmospheric Environment 2003, 37 (21), 2957-2966. |
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