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| Titel |
Near surface profiles of HONO: The vegetated surface as source and sink |
| VerfasserIn |
M. Sörgel, A. Held |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068929
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| Zusammenfassung |
| The photolysis of HONO is an important primary OH radical source. The OH radical is the
most important oxidizing agent, the so called “detergent” of the atmosphere. HONO
formation pathways are still unclear (e.g. Sörgel et al., 2011). Nevertheless, the main
pathways are believed to be heterogeneous. Thus, the surface is proposed to be a major
source. Furthermore, soil emissions of HONO due to microbiological activity in soil (Su et
al., 2011) have been proposed. Therefore, we measured gradients of HONO, NO, NO2 and
O3 close to the surface (0.1 to 1.6 m above ground).
We used an automated, programmable moving inlet to measure at 3 or 5 heights between
0.1 m and 1.6 m above the ground. HONO, O3, NO and NO2 were measured simultaneously.
HONO was measured with a long path absorption photometer (LOPAP), O3 by UV
absorption and NO and NO2 by chemiluminescence with photolytic conversion of NO2. The
time resolution of an individual LOPAP measurement was 3 min, and a full profile was
measured within 30 min. Additionally, profiles of temperature and relative humidity as well
as leaf wetness and j(NO2) were measured. Measurements were conducted above a clearing
at the Waldstein field site of the University of Bayreuth in the Fichtelgebirge Mountains in
south-east Germany.
Preliminary results are presented. For example, during the day the highest values were
often measured close to the ground, indicating emission of HONO at the surface. This also
indicates that the daytime formation of HONO is heterogeneous or the emissions are due to
microbiological activity (Su et al., 2011). During the night, the lowest values were
often measured at the surface indicating deposition. Thus, HONO emissions as
well as HONO deposition have been observed. The profile data will be analyzed
with respect to light intensity, NO2 availability, atmospheric stability and surface
wetness in order to elucidate the driving forces behind emission and deposition,
respectively.
Sörgel, M; Regelin, E; Bozem, H; Diesch, J-M; Drewnick, F; Fischer, H; Harder, H; Held,
A; Hosaynali-Beygi, Z; Martinez-Harder, M; Zetzsch, C: Quantification of the unknown
HONO daytime source and its relation to NO2, Atmos. Chem. Phys., 11, 10433-10447,
2011.
Su, H., Cheng,Y., Oswald, R., Behrendt, T., Trebs, I., Meixner, F.-X., Andreae, M. O.,
Cheng, P., Zhang, Y., and Pöschl, U.: Soil Nitrite as a Source of Atmospheric HONO and OH
Radicals, Science, 333, 1616–1618, 2011. |
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