FEBUKO and MODMEP: Field measurements and modelling of aerosol and cloud multiphase processes

An overview of the two FEBUKO aerosol–cloud interaction field experiments in the Thüringer 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

Global fate and distribution of polycyclic aromatic hydrocarbons emitted from Europe and Russia, Atmos. Environ. 41 (2007) 8301-8315

The long-range atmospheric transport (LRT) of polycyclic aromatic hydrocarbons (PAHs) is not fully understood and has hardly been addressed by model studies. By model experiments the LRT of PAH emissions into air from Europe and Russia is studied testing several scenarios of gas–particle partitioning and degradability by reaction with ozone and the hydroxyl and nitrate radicals for two PAHs, benzo[a]pyrene (BAP) and fluoranthene (FLT). The model used is the atmosphere general circulation model ECHAM5 with a dynamic modal aerosol sub-model, HAM, ozone and sulfur species chemistry and bidirectional mass exchange on 2D marine (ocean surface mixed layer) and terrestrial surfaces (top soil layer and vegetation surfaces). After 5 years the substances are found to be mostly distributed to the soil compartment (64–97% as the global mean, varying with substance and season), which after 10 years is still filling; 1–5% are found in air and 2–33% in ocean. It is found that the lifetime and vertical distribution of the substances in the atmosphere and the LRT potential are all significantly influenced by the partitioning and degradation scenario. The total environmental burden is higher when sorption to organic matter and black carbon are considered to determine gas–particle partitioning rather than adsorption to the surface of particulate matter. The effect is þ20% for BAP but sevenfold for FLT. Concentrations in Arctic air are mostly underestimated by the model, which is partly explained by emissions not considered in the simulation. The comparison shows, however, that degradation of the sorbed BAP and FLT molecules should be significantly slower than the respective gaseous molecules and that absorptive partitioning is necessary to explain the LRT potential of FLT

HIF-2a, but not HIF-1a, is essential for hypoxic induction of class IIIb-tubulin expression in human glioblastoma cells

CERVOXYInternational audienc

Use of natural iron oxide as heterogeneous catalyst in photo-Fenton-like oxidation of chlorophenylurea herbicide in aqueous solution: Reaction monitoring and degradation pathways

SSCI-VIDE+CARE+HME:SRS:CGOInternational audienceThe photocatalytic degradation of 3-[3,4-(dichlorophenyl)-1-methoxy-1-methylurea] (Linuron), which is oneof phenylurea herbicides, has been studied using natural iron oxide(NIO) as a heterogeneous catalyst in the presence of H2O2 under variousconditions. The characterization of this catalyst revealed that NIO has amixed elemental composition and consists mainly of iron oxide(alpha-Fe2O3). This powder contains hematite as iron source and itsdissolution provides Fe3+ cations for the Fenton-like reaction insolution. The degradation rate was strongly influenced by pH, initialconcentrations of H2O2, amount of NIO particles and type of irradiation(artificial or natural sunlight). An initial Linuron concentration of4.0 x 10(-5) mol L-1 was completely degraded after 45 min under theoptimum conditions. The decrease of chemical oxygen demand (COD) as aresult of mineralization of the herbicide was observed i.e., 99.99% ofthe initial concentration of Linuron and over 80% of COD were removedafter 6 h under our experimental conditions. The degradation of Linuronis mainly due to the formation of hydroxyl radicals as confirmation bythe use of 2.0% of isopropanol as an HO center dot scavenger. Thedecomposition of Linuron gave eight main intermediate products, and adegradation mechanism is suggested on the basis of these identifiedintermediates. The use of NIO is interesting; because in addition to itscatalytic effect, its high density enables an easy solid-liquidseparation, making it a versatile material for environmentalapplications. (C) 2015 Elsevier B.V. All rights reserved