Messungen von Wasserstoffperoxid - Ein Beitrag zur Charakterisierung der limitierenden Faktoren bei der Ozonproduktion : Umweltforschung im Hochgebirge - Ergebnisse von GAW-DACH und verwandten Projekten

1999

S. 57-64

5 Lit. Ang.

Unselbständiges Werk

200086911

Continuous measurements of H2O2 and organic hydroperoxides were performed at the field station Schauinsland (1220 m a.s.l., Black Forest, Germany) between January 1989 and June 1991 using an ezyme catalysed fluorescence instrument. From this long-term data set periods were selected, where production exeeds chemical losses, because the measured concentrations of photochemically produced species then should approximately reflect their production rates. This is the case when air masses at Schauinsland have been transported from the nearby city of Freiburg and Rhine valley during daytime in summer. A comparison of results of smog chamber experiments performed by Hess et al. (1992 a,b,c) with chemical box model calculations using the EURORADM mechanism (Stockwell and Kley, 1994) showed, that a positive slope in the H2O2/Ox ratio with increasing photochemical age is an indication of NOx limitation of photochemical ozone production. Analysis of the observed concentration ratios of H2O2 and Ox versus the photochemical age of the air masses gave the result, that a large fraction of these measurements already fall into the category where the ozone production is NOx - limited. For this analysis only data from a wind sector were used, where the air masses were exposed to anthropogenic emissions less than four hours before arrival at the site. Since advected air from other wind sectors is photochemically further processed, because anthropogenic sources are more distant, it can be concluded that at Schauinsland the photochemical ozone production in most cases is limited by the availibility of NOx. Since Schauinsland is relatively close to a large anthropogenic pollution source, this conclusion should be also valid for most rural areas in Europe.