Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Ground-based measurements of ozone and related precursors at 47 deg N 11 deg E
    ( 1997)
    Scheel, H.E.
    ;
    Sladkovic, R.
    ;
    Seiler, W.
  • Publication
    Ozone formation, destruction and exposure in Europe and the United States
    ( 1997)
    Stockwell, W.R.
    ;
    Kramm, G.
    ;
    Scheel, H.E.
    ;
    Mohnen, V.A.
    ;
    Seiler, W.
  • Publication
    Ground-based measurements of ozone and related precursors at 47 deg N 11 deg E
    ( 1992)
    Scheel, H.E.
    ;
    Sladkovic, R.
    ;
    Seiler, W.
  • Publication
    Atmosphärisches Quecksilber - Verteilung, Zusammensetzung und Kreislauf
    ( 1987)
    Slemr, F.
    ;
    Schuster, G.
    ;
    Seiler, W.
    Zwischen 1977 und 1981 wurde das atmosphaerische Quecksilber wiederholt ueber dem Atlantik sowie ueber Mitteleuropa gemessen. Alle Nord-Sued-Profile der Gesamtquecksilberkonzentration ueber dem Atlantik zeigen eine ausgepraegte interhemisphaerische Differenz mit mittleren Werten von 1,96 ng/cbm in der Nordhemisphaere und 1,33 ng/cbm in der Suedhemisphaere. Ausserhalb der planetarischen Grenzschicht ist das Quecksilber vertikal homogen verteilt. In reiner Atmosphaere besteht das atmosphaerische Quecksilber ueberwiegend aus elementarem gasfoermigem Quecksilber, das in den kontinentalen Luftmassen mindestens 83% und in den maritimen mindestens 92% des Gesamtquecksilbergehalts der Luft ausmacht. Die Messungen deuten auf einen globalen Anstieg der Hg-Konzentration in der Luft hin, mit einer jaehrlichen Rate von 10 +- 8% in der noerdlichen und 8 +- 3% in der suedlichen Hemisphaere. Bei einer mittleren Konzentration von 1,65 ng/cbm enthaelt die Atmosphaere etwa 6.10 E9g Hg. Diese Menge wird j edes Jahr etwa einmal umgesetzt, so dass die Quell- und Senkenstaerken mit 6.10 E9g/Jahr anzusetzen sind. Gleiche Flussstaerken werden aus der Variabilitaet des atmosphaerischen Quecksilbers sowie aus der Nord-Sued-Differenz errechnet. Das Quecksilber wird hauptsaechlich auf den Kontinenten emittiert, wobei die anthropogen bedingten Emissionen ca. 30% der gesamten Emissionen ausmachen. (IFU)
  • Publication
    Spurenstoffe und Klima
    ( 1987)
    Müller, H.
    ;
    Seiler, W.
    ;
    Meixner, F.X.
  • Publication
    Destruction and production rates of carbon monoxide in arid soils under field conditions
    ( 1985)
    Conrad, R.
    ;
    Seiler, W.
    Carbon monoxide destruction and production processes take place simultaneously in soils (Seiler, 1978; Conrad and Seiler. 1980, 1982). The resulting net effect of both processes is usually the destruction of atmospheric CO (Inman, Ingersoll, and Levy, 1971; Heichel, 1973; Ingersoll, Inman, and Fisher, 1974; Liebl and Seiler, 1976; Seiler, 1978). Under arid soil conditions, however, soils may act as a net source for atmospheric CO. Desert and semidesert soils in southern Africa have been found to act permanently as a source for atmospheric CO (Conrad and Seiler, 1982). On the other hand, German soils under arid conditions showed a net emission of CO during daytime, but a net deposition of atmospheric CO at night (Seiler, 1978; Conrad and Seiler, 1982). The observed change of soil activity is caused by the changing rates of the individual CO destruction, or by production processes in the upper soil layers, or both. However, the parameters influencing the production and destruction proces ses of CO in the soil under field conditions are unknown. Field measurements were carried out on arid soils in Andalusia, Spain. The results indicate that the net flux of CO at the soil-air interface is determined mainly by changing CO production rates. These rates were found to be strongly dependent on the soil surface temperature. (IFU)
  • Publication
    Increase of atmospheric methane - causes and impact on the environment
    ( 1985)
    Seiler, W.
    In-situ measurements and analysis of air trapped in ice cores clearly indicate that the atmospheric CH4 abundance has changed with time during the last 2 centuries from about 0.6-0.7ppmv to the present level of 1.7ppmv. The increase in atmospheric CH4 is most likely due to the change of emission rates of several biogenic and non-biogenic sources such as fermentation by ruminants, anaerobic mineralisation of organic matter in rice paddies, biomass burning and emission of natural gas due to leakages. The annual total CH4 source strength is estimated to be 237 Tg for 1950 and 348 Tg for 1975 corresponding to an average rate of increase of 1.5% per year which agrees well with the observed increase of atmospheric CH4 of 1.5-1.7% per year. The CH4 production is mainly balanced by the photochemical oxidation of CH4 by OH assuming tropospheric mixing ratios of 1.1ppmv for 1950, 1.2ppmv for 1960 and 1.5ppmv for 1970. Because of the physical and chemical properties, the increase of atmospheric C H4 has considerable impact on the chemistry of the troposphere and stratosphere. (IFU)