Das Projekt "Halogene in der marinen Umwelt - Laboruntersuchungen der heterogenen Chemie" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Chemie (Otto-Hahn-Institut) durchgeführt. The project HAMLET is devoted to laboratory studies of the heterogeneous chemistry taking place in or at the surface of sea-salt aerosols and also ice. The experiments are designed to give insight into the mechanism of the liberation of reactive halogen from sea-salt aerosol, and into the catalytic chemical cycling schemes that sustain the concentrations of reactive halogens that have been observed in the field. The objectives of the project are therefore to gather highest quality experimental data that will allow the rate and mechanism of reactive halogen generation in the remote, polluted and polar marine boundary layer to be quantified, to assess the role of halogens in affecting the oxidizing capacity of the troposphere and to explain episodal, halogen mediated ozone destruction in the polar troposphere. Using a combination of the presently most advanced (and complementary) techniques in atmospheric heterogeneous chemistry we will investigate reactions on bulk solutions, ice surfaces, deliquescent and humidified aerosols, dry and humidified bulk surfaces and droplets. The heterogeneous techniques to be employed are: wetted-wall flow tube reactor, droplet-train reactor, Knudsen reactor, coated-wall flow tube reactor, aerosol smog chamber and aerosol-flow tube reactor. The project will: 1) Obtain data for halogen oxyacids reactions with halide ions as cycling reactions for bromine and chlorine, 2) Determine the influence of sulphate on activation and cycling of halogens from sea-salt, 3) Quantify the halogen activation potential of some NOx species, 4) Assess the role of iodine in ozone depletion and modification of liquid-phase halogen chemistry, 5) Examine the role of efficiency of uptake of several radicals species as direct and indirect oxidizing agents of bromide, 6) Involve a variety of surfaces to ensure closure on a physico-chemical description of the reactions, and to mimic the situation in the atmosphere
Das Projekt "Der Beitrag reaktiver Halogenarten auf die Oxidationsfaehigkeit der reaktiven Halogenarten in der Troposphaere: Zyklen - Mechanismen - und Feldbeobachtungen - HALOTROP-CYMFO" wird vom Umweltbundesamt gefördert und von Universität Heidelberg, Institut für Umweltphysik durchgeführt. This study is a contribution to the part of the programme dealing with the Oxidation Capacity of the Troposphere. It will be achieved by coordinated field-, laboratory- and modelling investigations of reactive halogen species, their precursor and storage species, and the reaction mechanisms involved. Field measurements will include direct determination of halogen oxides by Differential Optical Absorption Spectroscopy (DOAS) at sub-ppt levels. The laboratory studies will close many gaps in our knowledge of RHS related homogeneous and surface-catalyzed reactions including iodine chemistry. The latest data from field and laboratory studies will be assembled in trajectory- and limited area 3D models, which will help to understand the results of the field campaigns as well as to assess the regional impact of RHS chemistry. A further important part of this study will be the assessment of a possibly anthropogenic influence on RHS sources and the transformation mechanisms within the RHS reservoir. Thus possible mechanisms changing the tropospheric oxidation capacity due to human activities can be investigated. While a central question concerns the importance of release of RHS from sea salt aerosol, for instance due to reaction of anthropogenic NOy species (like N205, NO2) with sea salt aerosol, the detailed investigation of those processes is the aim of a parallel study with the sub-title 'Sea Salt Aerosols: Laboratory Investigation of Heterogeneous Halogen Activation in the Troposphere (HALOTROP-SALT). Areas where enhanced levels of RHS are to be expected (like polluted coastlines or polar regions) will be identified. Regional processes involving RHS will be set into a global perspective.
Das Projekt "Marines Salzspray und schadstoffbelastete Atmosphaere als Ursachen von Schaeden an Natursteinbauwerken im Mittelmeerraum" wird vom Umweltbundesamt gefördert und von RWTH Aachen University, Geologisches Institut, Lehrstuhl für Geologie und Paläontologie, Arbeitsgruppe Natursteine und Verwitterung durchgeführt. Ziel dieses internationalen Forschungsprojektes war die wissenschaftl. Untersuchung und Erklaerung von Verwitterungsvorgaengen an Natursteinbauwerken, insbesondere bezogen auf Bauwerke im Kuestenbereich des Mittelmeeres. Fuer die Untersuchungen wurden Pilotbauwerke in der Kuestenregion Griechenlands, Maltas, Italiens und Spaniens ausgewaehlt. Die mineralogischen, physikalischen und chemischen Eigenschaften der verwendeten Gesteine (i.W. Kalkstein) und deren verwitterungsbedingte Veraenderungen wurden untersucht. An den Bauwerken wurde eine systematische Schadenserfassung durchgefuehrt. Umwelteinfluesse konnten auf der Grundlage von Langzeit-Monitoring charakterisiert und bewertet werden (Klima, Mikroklima, Aerosole, Depositionen). Grundlegende ebenso wie bauwerksspezifische Zusammenhaenge zwischen Gesteinseigenschaften, Umwelteinfluessen und Verwitterungsverhalten der Gesteine konnten als Ergebnis des Projektes aufgezeigt werden.