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Fine (<2.6 μm) and size-segregated aerosol samples collected at a tropical pasture site (Rondoˆnia, Brazil) under various conditions have been analysed by thermally assisted hydrolysis and alkylation, coupled to GC/MS. Fatty acids, alkadioic acids, hydroxybenzoic acids, levoglucosan, and other compounds of polysaccharide origin have been identified as their methyl ester and ether derivatives among the products of thermally assisted methylation. The identity of the characteristic hydrolysed fragments and soluble components has been confirmed by butylation and silylation as well. To improve available chemical information, this analytical method has also been combined with a thermal pre-treatment. Seasonal variation of size-resolved distribution of the characteristic fragments of thermally assisted hydrolysis and methylation (THM) in the atmospheric aerosol is shown. Although the results presented in this paper are preliminary and based on a limited number of aerosol samples, they clearly demonstrate the sensitivity and potential of thermally assisted alkylation-GC/MS to provide unique chemical information on the bulk of organic matter in tropospheric aerosol to facilitate their source apportionment. [Copyright &y& Elsevier]

Abstract: Atmospheric particulate matter with aerodynamic diameter less than 10μm (PM10) and 2.5μm (PM2.5) is now identified as one of the most dangerous pollutants on human health by the EU new directive on air quality (2008/50/CE). Although these primary pollutants are monitored in cities, little information is available on their ecotoxicity. In this paper a ‘whole-aerosol’ testing protocol is suggested based on the kinetic version of the Vibrio fischeri bioluminescence inhibition test. [Copyright &y& Elsevier]

Aerosols produced over forests impair visibility and may affect climate by scattering and absorbing solar radiation and by serving as cloud condensation nuclei. Here, we introduce, to our knowledge, a new route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, methacrolein and methacrylic acid, namely, multiphase acid-catalysed oxidation with hydrogen peroxide, a perfect analogue to atmospheric sulphate formation. We demonstrate that the formation of major secondary organic aerosol components that are present in natural forest aerosols collected at K-puszta, Hungary, during the summer of 2003, namely, 2-methyltetrols and 2,3-dihydroxymethacrylic acid, can be explained by this mechanism. [Copyright &y& Elsevier]