Description: Das Projekt "Aufnahme und Nitrierung von Aromaten in der waessrigen Phase der Troposphaere" wird vom Umweltbundesamt gefördert und von Fraunhofer-Institut für Toxikologie und Aerosolforschung durchgeführt. General Information: The overall aim of the proposed project UNARO is to study tropospheric multiphase formation processes of nitroaromatic compounds which have been identified in field measurements of cloud and rain water and some of which are known to be toxic. To reach this aim within UNARO laboratory experiments on uptake and aqueous phase transformation mechanisms will be performed and combined with toxicologic studies in order to evaluate risk to human health. The project in detail focusses on the investigation of: - The uptake of polar aromatic hydrocarbons by aqueous solutions - Nitration reactions with NO3 radicals and nitronium ions in the aqueous phase and their products - Effectiveness of nitroaromatic formation pathways by including results into a two-box model - Toxicology and mutagenic activity of reaction products The chemical processing of organic molecules in aqueous atmospheric droplets is necessarily prefaced by transfer of the organic species from the gas to the aqueous phase. The rate of this transfer is controlled by five processes: 1) gas-phase diffusion to the droplet; 2) transfer across the gas/liquid interface described by the mass accommodation coefficient alpha; 3) liquid phase diffusion away from the interface; 4) reaction in the droplet; 5) gas-liquid phase equilibrium controlled by the Henry's Law coefficient, H. Diffusion is well understood and is readily calculated. Phase transfer, reactions in the droplets and gas-liquid phase equilibrium are of concern in this project. Alpha will be measured for phenol, 4-nitrophenol, p-cresol, 2-nitro-4-methylphenol and benzoic acid. The measurements will be made as a function of temperature and pH and ionic strength effects will also be checked. Experiments will be conducted with scavengers present to determine alpha directly. In order to better understand different pathways where nitration processes may occur within the tropospheric aqueous phase, experimental investigations are planned. - To study nitration reactions by the nitrate radical in aqueous solution. - To study nitration reactions by NO2+ in aqueous solution. - To perform product studies for the development of complete reaction pathways. Relevant nitration reactions to be studies (at various temperatures and ionic strengths) are: 1) Phenol to give nitration products: p-nitrophenol and 2,4-dinitrophenol. 2) p-Cresol to give nitration products: 2-nitro-4-methylphenol and 2,6-dinitro4-methylphenol. 3) Benzoic acid to give the nitration product 3-nitrobenzoic acid. 4) 4-methylbenzoic acid to give the nitration product 3-nitro-4-methylbenzoic acid. Atmospheric efficiency of nitroaromatic formation pathways will be assessed by directly including the measured parameters into a newly developed two-box model, where the gas phase chemistry is described by the RADM2 mechanism and coupled to a complex aqueous phase chemical mechanism. Prime Contractor:Univ. degli Studi di Milano, Dipartimento di Scienze dell'Ambientee del Ter
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Dinitrophenol ? Bewölkung ? Kresol ? Nitrophenol ? Phenol ? Benzoesäure ? Gesundheitsgefährdung ? Aromatischer Kohlenwasserstoff ? Nitrat ? Meteorologie ? Stickstoffdioxid ? Regenwasser ? Temperaturmessung ? Gasförmiger Stoff ? Laborversuch ? Mensch ? Reaktionsgleichgewicht ? Reaktionstemperatur ? Ionen ? Studie ? Chemikalien ? Toxikologie ? Troposphäre ? Nitrierung ? Komplexbildung ? Modellierung ? pH-Wert ? Menschliche Gesundheit ? REACH ? Risiko ? Sicherheit ? Diffusion ? Atmosphärenchemie ? Umweltschutz ? Physikalische Größe ? Physikalischer Vorgang ?
Region: Lower Saxony
Bounding box: 9.16667° .. 9.16667° x 52.83333° .. 52.83333°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1997-10-01 - 1999-09-30
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