Description: Das Projekt "Auswirkungen der Oxidation auf aromatische Verbindungen in der Troposphaere - EXACT" wird vom Umweltbundesamt gefördert und von Universität Wuppertal, Physikalische Chemie durchgeführt. Objective: Problems to be solved: Aromatic compounds are emitted to the atmosphere from transport and industrial sources and oxidised in the troposphere. This process has a substantial impact on the formation of ozone and of photochemical smog on a European scale, and on the oxidising capacity of the atmosphere and hence on global warming. The oxidation of aromatic compounds also leads to the formation of secondary aerosols, with impacts on health and on climate. A quantitative understanding of the chemical mechanisms for oxidation of the major aromatic compounds is needed for the construction of models for both predictive and legislative applications and for the assessment of environmental impact. Recent laboratory studies have demonstrated considerable uncertainties in our present understanding of the atmospheric oxidation of aromatics and have seriously questioned our ability to assess the atmospheric impact of aromatic compounds. The major aim of the project is a detailed laboratory investigation of the mechanism and the construction and application of a model, based on the experimental results, to assess the atmospheric impact of aromatic emissions on European and global scales. Scientific objectives and approach. The project consists of four main components: In the laboratory experiments, laser flash photolysis is used to probe the chemistry of the early stages of the oxidation process, using absorption spectroscopy. A key element is the behaviour of adducts formed by the addition of the hydroxyl radical to the aromatic compounds. The subsequent chemistry is probed using photochemical reactor studies, coupled with a range of analytical techniques, such as Fourier transform infra red spectroscopy and gas chromatography. A key component of the strategy is the synthesis of important intermediates to test the hypotheses that are developed. The overall description of the oxidation of the major volatile organic compounds emitted to the atmosphere is contained in a master chemical mechanisms (MCM). The experimental results allow revision of the aromatic component of the MCM, which is then used to design experiments to test the proposed mechanisms. These experiments are conducted in the European Photochemical Reactor (EUPHORE) at Valencia in Spain. The EUPHORE experiments are conducted under conditions close to those pertaining in the atmosphere and provide a credible test of the MCM and hence of the laboratory experiments. Crucial experiments include the yield of ozone in aromatic oxidation, but the extensive instrumentation in EUPHORE permits a wide range of detailed experimental checks on the MCM. In addition, other experiments allow investigation of the formation of secondary organic aerosol. Prime Contractor: University of Leeds, School of Chemistry; Leeds.
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Hirsch ? Main ? Wuppertal ? Ozon ? Aromatischer Kohlenwasserstoff ? Photochemischer Smog ? Blitz ? VOC ? Laser ? Laserspektroskopie ? Meteorologie ? Photochemie ? Physikalische Chemie ? Umweltauswirkung ? Smog ? Gesundheitliche Auswirkungen ? Absorption ? Aerosol ? Gaschromatografie ? Industrieemission ? Photolyse ? Spektralanalyse ? Globale Erwärmung ? Luftschadstoff ? Troposphäre ? Emission ? Schule ? Laborversuch ? Wirkungsmodell ? Oxidation ? Modellierung ? Ozonbildung ? Chemikalien ? Europa ? Reaktor ? Gesetzgebung ? Studie ? Umweltschutz ? Laboruntersuchung ? Globale Aspekte ? Schadstoffbildung ? Atmosphäre ? Klimawandel ? Chemische Reaktion ? Fischerei ? Hydroxylradikal ? Temperaturerhöhung ? Analytik ? forecasting ? reources of the sea ? Laseranwendung ?
Region: Nordrhein-Westfalen
Bounding boxes: 6.76339° .. 6.76339° x 51.21895° .. 51.21895°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 2000-01-02 - 2003-01-31
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