Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Temporal variations of formaldehyde in continental air masses
    ( 1990)
    Slemr, J.
    ;
    Teuber, R.
    ;
    Rumpel, K.J.
    ;
    Seiler, W.
    Concentrations of formaldehyde were determined in ambient air during 10 short measuring periods between January and September 1981 at the measuring site of the Umweltbundesamt at Deuselbach, FRG (480 m elevation, 49.8 degree N, 1.2 degree E). HCHO levels were measured using the DNPH-method. Concurrent mixing ratios of SO2, CO2, CO, and O3 were measured and compared with the temporal variations of the HCHO mixing ratio. Solar radiation, wind direction and speed, temperature, precipitation etc. were also obtained routinely at the station. The HCHO mixing ratios ranged between 0.09 and 4.13 ppbv. The highest HCHO mixing ratios were observed in polluted atmospheres, e.g. in January and February, indicating the influence of direct HCHO emissions by anthropogenic sources. Extremely low HCHO values below 0.10 ppbv were observed in clean marine air during winter conditions. During late spring and summer, the HCHO concentrations showed distinct diurnal variations which correlated well with 03, thus indicating photochemical HCHO production. Under winter conditions, anticorrelations between HCHO and O3 were observed.
  • Publication
    Emission of carbon monoxide from submerged rice fields into the atmosphere
    ( 1988)
    Conrad, R.
    ;
    Schütz, H.
    ;
    Seiler, W.
    The emission of carbon monoxide was studied in Italian paddy fields using the static box technique. The results indicate that CO is produced in the submerged anoxic paddy soil. CO is released into the atmosphere predominantly by plant-mediated transport and to a lesser extent by ebullition. The total amount of CO released from the submerged soil is estimated to be approximately 0.2 Tg a E-1 which is three orders of magnitude lower than the release of CH4. CO was also produced by a light-dependent reaction in the phyllosphere of the rice plants. The corresponding CO emission rate was approximately twice that due to the release from the paddy soil and thus may be of the order of 0.5 Tg a E-1. (IFU)
  • Publication
    Tropospheric chemical composition measurements in Brazil during the dry season
    ( 1985)
    Crutzen, P.J.
    ;
    Delany, A.C.
    ;
    Greenberg, J.
    ;
    Haagenson, P.
    ;
    Heidt, L.
    ;
    Lueb, R.
    ;
    Pollock, W.
    ;
    Seiler, W.
    ;
    Wartburg, A.
    ;
    Zimmermann, P.
    Field measurement programs in Brazil during the dry seasons in August and September 1979 and 1980 have demonstrated the large importance of the continental tropics in global air chemistry. Many important trace gases are produced in large amounts over the continents. During the dry season, much biomass burning takes place, especially in the cerrado regions, leading to a substantial emission of air pollutants, such as CO, NOx, N2O, CH4 and other hydrocarbons. Ozone concentrations are enhanced due to photochemical reactions. The large biogenic organic emissions from tropical forests play an important role in the photochemistry of the atmosphere and explain why CO is present in such high concentrations in the boundary layer of the tropical forest. Carbon monoxide production may represent more than 3% of the net primary productivity of the tropical forests. Ozone concentrations in the boundary layer of the tropical forests indicate strong removal processes. Due to atmospheric supply of NOx by lightning, there is probably a large production of O3 in the free troposphere over the Amazon tropical forests. This is transported to the marine-free troposphere and to the forest boundary layer. (IFU)
  • Publication
    The latitudinal distribution of carbon monoxide across the Pacific from California to Antarctica
    ( 1984)
    Seiler, W.
    ;
    Robinson, E.
    ;
    Clark, D.
    The results of a research study of the carbon monoxide concentration from California to 90 degrees S, Antarctica are presented. The data both extend and support other research studies of the latitudinal distribution of carbon monoxide in that higher concentrations are evident over the Northern Hemisphere than over the Southern Hemisphere. Carbon monoxide concentrations range between 50 to 60 ppb with a few peaks into the 60s in the latitudinal area south of the ITCZ and values of 80 ppb or higher at latitudes north of Hawaii. A comparison is also made of carbon monoxide and ozone concentrations along the flight tract between California and Antarctica, over the Ellsworth Mountains of Antarctica, and between 78 degrees S and the South Pole. These ozone-carbon monoxide data show statistically significant negative correlations in the upper troposphere and lower stratosphere over Antarctica. It is believed that this is a good indication of mixing across the tropopause. (IFU)
  • Publication
    Utilization of traces of carbon monoxide by aerobic oligotrophic microorganisms in ocean, lake and soil
    ( 1982)
    Seiler, W.
    ;
    Conrad, R.
    Carbon monoxide at trace concentrations (equal or smaller than 1 nM) was utilized in ocean water, lake water and soil. By boiling or by poisoning the water with HgCl2, NaCN or NaN3 must read CO consumption was switched off; this demonstrated that CO utilization was due to metabolic processes. Since CO consumption activity was removed by filtration through 0.2 mym filters, but not by filtration through 3.0 mym filters, CO consumption was most probably due to single bacterial cells. CO consumption followed Michaelis-Menten kinetics with K sub m-values of 7-9 nM CO. Enrichment experiments were carried out by gassing lake water and soil suspensions with ambient pressurized air containing 0.5-1.0 ppmv CO. After a total supply of approximately 2 ml CO, utilization of CO became detectable. Then, the CO consumption rates of the suspensions increased steadily with incubation time indicating the growth of a specific CO-utilizing microbial population. No CO consumption activity was detectable in control suspensions, which were gassed with CO-free air. The high affinity of soil and water for CO as well as the increase of CO consumption activity upon incubation under ambient atmospheric CO is indicative for the oligotrophic nature of a specific CO-utilizing microflora. (IFU)