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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2006.12.022 Byline: Estelle Roth (a), Damaris Kehrli (b), Karine Bonnot (b), GwenaA'lle Trouve (b) Keywords: Aerosols; PM1; PM0.1; NO.sub.x ; SO.sub.2; ELPI Abstract: An Electrical Low Pressure Impactor (ELPI) was used during spring and autumn 2003 in the centre of Strasbourg for the measurement of atmospheric aerosols size distribution. The concentration of NO.sub.x and SO.sub.2 in air was simultaneously measured with specific analysers. Samples were collected in the range 0.007-10[mu]m in equivalent aerodynamic diameter size. Number distributions are representative of a pollution originating from urban traffic with a particle size distribution exhibiting a nucleation mode below 29nm and an accumulation mode around 80nm in size. A mean particle density equal to 39000[+ or -]35000 total particles per cm.sup.3 with a size ranging from 7 to 10[mu]m was obtained after a sampling period of 2 weeks in spring. About 86.9% of the number of particles have an aerodynamic diameter below 0.1[mu]m and 13.1% between 0.1 and 1[mu]m. Correlation coefficients between the number of particles impacted on each ELPI plate and gas concentrations (SO.sub.2 and NO.sub.x) showed that the numbers of particles with diameter between 0.10 and 0.62[mu]m are highly related to the NO.sub.x concentration. This result indicates that particles are traffic induced since NO.sub.x is mainly emitted by cars as shown by measurements on various sites. Particles are less clearly correlated to the SO.sub.2 concentration. Particle analysis on different ELPI plates for a sampling period of 2 weeks in autumn showed high level of soluble NO.sub.3.sup.-, SO.sub.4.sup.2- and NH.sub.4.sup.+ ions. Indeed, up to 90% b.w. of these three species were found in the particle range 0.1-1[mu]m. The formation of particulate NH.sub.4NO.sub.3 is favoured by high NO.sub.x concentration, which induces the formation of gaseous HNO.sub.3. Author Affiliation: (a) Groupe de Spectrometrie Moleculaire Atmospherique (GSMA), Moulin de la Housse, BP 1039, 51687 REIMS Cedex 2, France (b) Laboratoire Gestion des Risques et Environnement, Universite de Haute Alsace, 25 rue de Chemnitz, 68200 MULHOUSE, France Article History: Received 26 September 2005; Revised 13 November 2006; Accepted 7 December 2006

An Electrical Low Pressure Impactor (ELPI) was used during spring and autumn 2003 in the centre of Strasbourg for the measurement of atmospheric aerosols size distribution. The concentration of NO x and SO2 in air was simultaneously measured with specific analysers. Samples were collected in the range 0.007–10μm in equivalent aerodynamic diameter size. Number distributions are representative of a pollution originating from urban traffic with a particle size distribution exhibiting a nucleation mode below 29nm and an accumulation mode around 80nm in size. A mean particle density equal to 39000±35000 total particles per cm3 with a size ranging from 7 to 10μm was obtained after a sampling period of 2 weeks in spring. About 86.9% of the number of particles have an aerodynamic diameter below 0.1μm and 13.1% between 0.1 and 1μm. Correlation coefficients between the number of particles impacted on each ELPI plate and gas concentrations (SO2 and NO x ) showed that the numbers of particles with diameter between 0.10 and 0.62μm are highly related to the NO x concentration. This result indicates that particles are traffic induced since NO x is mainly emitted by cars as shown by measurements on various sites. Particles are less clearly correlated to the SO2 concentration. Particle analysis on different ELPI plates for a sampling period of 2 weeks in autumn showed high level of soluble NO3 −, SO4 2− and NH4 + ions. Indeed, up to 90% b.w. of these three species were found in the particle range 0.1–1μm. The formation of particulate NH4NO3 is favoured by high NO x concentration, which induces the formation of gaseous HNO3. [Copyright &y& Elsevier]

In this work, we report the gas phase UV absorption spectra and the kinetics of the OH-oxidation of 1 H -1,2,3-triazole and pyrazole. UV spectra were determined between 200 and 250 nm, at 350 ± 2 K and at pressures between 0.09 and 0.3 Torr. The reported maximal UV absorption cross sections are (cm 2 per molecule): σ 206 nm, 1 H -1 H -1,2,3-triazole = 2.04 × 10 -18 and σ 203 nm, pyrazole = 5.44 × 10 -18 . The very low absorption capacity of these compounds beyond 240 nm indicates that their atmospheric photodissociation is negligible. The OH-oxidation of these species was performed in an atmospheric simulation chamber coupled to an FTIR spectrometer and to a GC/MS over the temperature range 298-357 K and at atmospheric pressure. Experiments were conducted in relative mode using benzaldehyde, trans -2-hexenal and heptane as references. The obtained rate constants at 298 K were (×10 -11 cm 3 per molecule per s): k (OH + 1 H -1,2,3-triazole) = 2.16 ± 0.41; k (OH + pyrazole) = 2.94 ± 0.42. These results were compared to those available in the literature and discussed in terms of structure-reactivity and temperature dependency. Their tropospheric lifetimes with respect to reaction with OH radicals were then estimated., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)