Entstehung, Verhalten und Ablagerung von gas-, partikel- und tropfenfoermigen Reaktionsprodukten. T. 2

In the Nationalpark 'Bavarian Forest' various studies were performed at a spruce/beech forest-site to determine the fluxes of N- and S-compounds by dry and wet deposition. The minimum deposition is determined for nitrate (9 kg Nha"-"1 y"-"1), for ammonium (NH_4"++NH_4) (16 kgN ha"-"1 y"-"1), for H"+(2.0 kgH"+ha"-"1 y"-"1), and for sulfate (66 kgha"-"1 y"-"1). If the dry deposition of NO_2 is considered to contribute to the nitrate-deposition, the total 'nitrate' deposition increases up to about 18 kg Nha"-"1 y"-"1. It is important to mention that the processes of co-deposition (e.g. reactive deposition of SO_2 with O_3 or/and H_2O_2) at the needles/leaves and at the soil surface considerable contribute to the total deposition of H"+ and sulfate. All studies show that dry deposition of SO_2, HNO_3, NH_3, NO_3"-, and NH_4"+ is controlled by the hydrological, micro-meteorological and chemical situation at this site. As the current modeling of these processes by 'inferential'-methods (e.g. Hicks et al., 1987; Wesely, 1989) mostly neglect the effects of co-deposition and of reactions in the gas-phase (e.g. NO-NO_2-O_3; NH_3-HNO_3-NH_4NO_3) fluxes calculated without any consideration of the gas-phase reactions are larger than the corrected fluxes. Even in regions with H_2O_2-production rates of 0.1 ppb h"-"1 (Dlugi, 1992) a minimum flux of sulfate of 0.07 #mu#gm"-"2 s"-"1 can be produced by the process of codeposition, e.g. the reduction of surface resistance of SO_2 by the surface reaction SO_2+H_2O_2. This is a sulfate flux of about 10 kg ha"-"1 y"-"1. Also fluxes of NH_3 from the forest to the atmosphere are observed which show a contribution of direct emission from the trees below 10-15%. (orig./KW)SIGLEAvailable from TIB Hannover: F94B0771+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBayerisches Staatsministerium fuer Landesentwicklung und Umweltfragen, Muenchen (Germany)DEGerman