Untersuchung der Photooxidantien Wasserstoffperoxid, Methylhydroperoxid und Formaldehyd in der Troposphäre der Antarktis = Investigation of the photooxidants hydrogen peroxide, methylhydroperoxide and formaldehyde in the troposphere of Antarctica

摘要: Photooxidants play an important role for the oxidation capacity of troposphere. The presented work deals with seasonal changes atmospheric photooxidants like hydrogen peroxide (H2O2), methylhydroperoxide (MHP) and formaldehyde (HCHO). principal purpose was to follow quantify mixing-ratios these photochemical species first time over a complete annual cycle in Antarctica. These investigations contribute better understanding photochemistry trace gases clean polar During two field campaigns at German Antarctic station Neumayer (overwintering campaign from January 1997 until March 1998 shorter 1999) continuous measurements were performed. Two commercially available analysers modified withstand conditions integrated into air-chemistry observatory. A wetchemical technique used peroxides sampling analysis. Species quantified by fluorescence detection. In order compare results well-known reaction mechanisms box model applied. obtained series show pronounced variation. summer average values 0.197 ppbv H2O2, 0.191 MHP 0.360 HCHO observed. For concentrations documented during night winter. At this 0.054 0.089 0.150 detected. are significantly higher than expected due missing actinic radiation essential production. Trajectory analyses calculations three-dimensional showed that winter mainly affected long-range transport free An phenomenon spring is stratospheric ozone depletion which cause increased UV-B as show. consequence enhanced radiation, increase activity expected. However, lower time, whereas shows compared autumn when sunshine duration similar. Apparently, “ozone hole period” does not any significant impact on photooxidants. From year-round periods could be extracted, diurnal contrast recent publications maximum occurred highest early afternoon. Model provide evidence alone can explain observed cycles. Interactions snow surface, adsorption crystals or incorporation co-condensation may probably responsible findings investigated troposphere Antarctica useful data record further modeling.