Massenspektrometrische Spurengasmessungen in Abgasfahnen von Duesentriebwerken zur Untersuchung des Einflusses des Luftverkehrs auf die Atmosphaere Abschlussbericht

Abstract

To estimate the influence of airtraffic on the atmosphere and climate, detailed knowledge is required about the composition, distribution, and the chemical and physical evolution of jet engine exhaust at cruise altitude, i.e., in the region of the upper troposphere, tropopause, and lower stratosphere. For this purpose we performed mass spectrometric measurements of trace gases (SO_2, H_2SO_4, HNO_3, HNO_2, HCN, (CH_3)_2CO, CH_3CN), ions, and aerosol particles directly behind aircraft at cruise altitude or at ground, as well as inside the North Atlantic flight corridor. The presence of sulfuric acid, in major part as an aerosol component, in the exhaust plume of an aircraft at cruise altitude could be demonstrated for the first time. The conversion efficiency of fuel sulfur to H_2SO_4 amounts to at least 0.4%. Increased concentrations of HNO_3, HNO_2, and SO_2 were also found in young exhaust plumes. The data indicate the conversion of about 1.3% of the NO_2 and NO formed by combustion to the respective acid by reaction with OH radicals. The total number of positive ions probably exceeds 10"9 cm"-"3 at the engine exit and steeply decreases with increasing plume age due to ion-ion recombination. Massive ions with masses up to above 8500 amu were detected already in the very young plume, i.e., at a distance of a few m behind the engine. The mass distributions of positive and negative ions differ markedly. The abundance of negative ions above 450 amu about 100 m behind an aircraft at cruise altitude is about 1000 times higher than in the background atmosphere. Large-scale measurements in the North Atlantic flight corridor did not reval significantly enhanced concentrations of trace gases. Polluted air masses, probably originating from the planetary boundary layer, were detected above the Atlantic. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(72,40) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman