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Radicals and radical anions such as OH, NO(3) and SO(4)(-) can act as important oxidants in aqueous solutions, e.g. as a part of the tropospheric multiphase system. In the present study the aqueous phase kinetics of OH, NO(3) and SO(4)(-) radical reactions with the following ten aliphatic poly-alcohols 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2,3-propanetriol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, (2R,3S)-butane-1,2,3,4-tetraol (meso-erythritol), (2R,4R)-pentane-1,2,3,4,5-pentol (arabitol) and (2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol (mannitol) were investigated. These alcohols are both of anthropogenic and of biogenic origin and all are highly water soluble. All rate constants throughout this study were determined as a function of the temperature between 278 < or = T [K] < or = 328. OH radical reactions with poly-alcohols (k(2nd) = 1.6-4.7 x 10(9) L mol(-1) s(-1)) are the fastest among the three investigated radicals. The corresponding NO(3) radical (k(2nd) = 0.66-1.5 x 10(7) L mol(-1) s(-1)) and SO(4)(-) radical (k(2nd) = 2.7-5.3 x 10(7) L mol(-1) s(-1)) reactions are on average two orders of magnitude slower. All three radicals react by an H-abstraction mechanism preferably at the alpha-carbon atom of the investigated alcohols. Kinetic measurements were performed using laser flash photolysis-long path absorption (LFP-LPA). Rate constants were measured either directly following the NO(3) and SO(4)(-) concentration-time profile or by a competition kinetics method using a well characterized reference reaction (SCN(-)) for OH radicals. Furthermore, obtained kinetic data are used to extend existing reactivity correlations for H-abstraction reactions with bond dissociation energies in aqueous solution and to calculate the tropospheric lifetimes of the alcohols.

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An overview of the two FEBUKO aerosol-cloud interaction field experiments in the Thu¨ringer Wald (Germany) in October 2001 and 2002 and the corresponding modelling project MODMEP is given. Experimentally, a variety of measurement methods were deployed to probe the gas phase, particles and cloud droplets at three sites upwind, downwind and within an orographic cloud with special emphasis on the budgets and interconversions of organic gas and particle phase constituents. Out of a total of 14 sampling periods within 30 cloud events three events (EI, EII and EIII) are selected for detailed analysis. At various occasions an impact of the cloud process on particle chemical composition such as on the organic compounds content, sulphate and nitrate and also on particle size distributions and particle mass is observed. Moreover, direct phase transfer of polar organic compound from the gas phase is found to be very important for the understanding of cloudwater composition.For the modelling side, a main result of the MODMEP project is the development of a cloud model, which combines a complex multiphase chemistry with detailed microphysics. Both components are described in a fine-resolved particle/ drop spectrum. New numerical methods are developed for an efficient solution of the entire complex model. A further development of the CAPRAM mechanism has lead to a more detailed description of tropospheric aqueous phase organic chemistry. In parallel, effective tools for the reduction of highly complex reaction schemes are provided. Techniques are provided and tested which allow the description of complex multiphase chemistry and of detailed microphysics in multidimensional chemistry-transport models. r

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