Publications (5)9.76 Total impact
Article: Field comparison of particulate PAH measurements using a low-flow denuder device and conventional sampling systems.[show abstract] [hide abstract]
ABSTRACT: Polyaromatic hydrocarbons (PAHs) are complex carbonaceous compounds emitted to the atmosphere by various combustion processes. Because the toxicity of many of them is now well recognized and documented, the determination of their atmospheric concentrations is of great interest to better understand and develop future atmospheric pollution control strategies. Hence, a common sampling protocol has to be defined to homogenize the results. With this goal in mind, field studies were carried out under different environmental conditions (74 samples) by simultaneously operating both a conventional sampler and a sampler equipped with a denuder tube upstream from the filter. The experimental results presented in this work show that the atmospheric particulate PAH concentrations are underestimated at least by a factor of 2 using a conventional sampler. The discrepancy between the two kinds of samplers used varied a lot from one compound to another and from one field campaign to another. This discrepancy may be explained by a simple degradation of particulate PAH in the natural atmosphere and on the filter. This is particularly worrisome because, based on the results presented in this work, the atmospheric PAH concentrations measured using conventional samplers not equipped with an ozone trap can underestimate the PAH concentration by more than 200%. This is especially true when the samples are collected in the vicinity of the point source of particulate PAHs and for highly reactive compounds such as benzo[a]pyrene.Environmental Science and Technology 11/2006; 40(20):6398-404. · 5.23 Impact Factor
Article: Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography-mass spectrometry with negative ion chemical ionisation.[show abstract] [hide abstract]
ABSTRACT: This study deals with the development of a routine analytical method using gas chromatography-mass spectrometry with negative ion chemical ionisation (GC/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of this analytical procedure has been performed on standard reference material (SRM 1649a: urban dust), giving results in good agreement with the few data available in the literature. The analytical method was also applied on ambient air samples (on both gas and particulate phases) from the French POVA program (POllution des Vallées Alpines). NPAHs concentrations observed for a rural site during the Winter period are about 0.2-100.0pgm(-3) in the particulate phase and about 0.0-20.0pgm(-3) in the gas phase. OPAHs present concentrations 10-100 times higher (0.1-2.0ngm(-3) and 0.0-1.4ngm(-3) for the particulate and the gas phases, respectively). These preliminary results show a good correlation between the characteristics of the sampling site and the compound origins (primary or secondary).Journal of Chromatography 08/2006; 1121(1):106-13. · 4.53 Impact Factor
Article: Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys: Part 1: Concentrations, sources and gas/particle partitioning[show abstract] [hide abstract]
ABSTRACT: Ambient measurements (gas+particle phases) of 16 polycyclic aromatic hydrocarbons, 17 nitrated PAHs (NPAHs) and eight oxygenated PAHs (OPAHs) were carried out during the winter 2002–2003 and the summer 2003 in two French alpine valleys on various types of sites (traffic, sub-urban, altitude and rural). Atmospheric concentrations of these classes of compounds are of interest because they include potential mutagens and carcinogens. During both summer and winter campaigns, OPAH concentration levels were of the same order of magnitude as PAH ones while NPAH concentrations were one to two orders of magnitude lower. Total particulate PAH, OPAH and NPAH concentrations were higher in the Chamonix valley than in the Maurienne valley. A heavier pollutant accumulation process in the Chamonix valley and geomorphology promoting their dispersion seem to explain such differences. Despite reaching lower atmospheric concentrations, NPAHs seemed to account up to 20% of carcinogenic potency of particulates collected at the sites away from pollution sources. The formation of secondary compounds such as NPAHs increases significantly the carcinogenic risk at the sites away from pollution sources. Study with 2-nitrofluoranthene/1-nitropyrene ratio showed that NPAH gas phase formation was hindered in winter, and when relative contribution from primary sources was higher. Nevertheless, in winter under specific conditions, evidence of secondary NPAH formations was observed at sub-urban and traffic sites (snowfalls) and rural site (accumulation of pollutants and snowfalls). For all sampling sites, the daytime OH initiated reaction seemed to be the dominant gas phase formation pathway over the NO3 initiated reaction. The fraction of PAHs, OPAHs and NPAHs associated with the particle phase was strongly depending on their vapour pressure and the ambient conditions.Atmospheric Environment.
Article: Sampling precautions for the measurement of nitrated polycyclic aromatic hydrocarbons in ambient air[show abstract] [hide abstract]
ABSTRACT: Because of the toxicity of polycyclic aromatic hydrocarbons (PAHs) and of their oxidation products, such as nitrated and oxygenated PAHs (NPAHs and OPAHs), the determination of their concentrations is of great interest in terms of atmospheric pollution control. Then, normalisation of sampling procedures appears essential. In this context, this paper presents a comparison of particulate PAH, OPAH and NPAH concentrations determined with two different samplers (cascade impactor and conventional high volume sampler) installed in parallel during several field sampling campaigns carried out under different environmental conditions. For winter and summer periods, the PAH and OPAH concentrations determined with both sampling systems were considered as equivalent. In the summer period, NPAH concentrations quantified with both sampling devices were similar whereas in the winter period, the conventional high volume sampler underestimated their concentrations by a factor of 3–4. This underestimation was observed in the same proportion for all the 17 quantified NPAHs. Analytical error, NPAH formation during the sampling and NPAH degradation by reaction with gaseous oxidants associated to sampling methodology were unable to explain such differences between both samplers used in parallel. A probable hypothesis is that the heating of the PM10 head of the high volume sampler in the winter period generates an increase of the internal sampler temperature that could intensify the chemical degradation of the NPAHs inducing the underestimation of their concentrations in the atmosphere. Further investigations will be necessary to confirm the importance of the temperature on the chemical degradation of these compounds and to understand the different behaviour of PAHs and OPAHs. Consequently, we suggest using oxidant scrubber to prevent chemical degradation of PAHs and derivatives during their sampling. Moreover, we advise against the heating of the sampling head which could induce an increase of these reactions of degradation especially for NPAHs.Atmospheric Environment.
Article: Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys Part 2: Particle size distribution[show abstract] [hide abstract]
ABSTRACT: The size distribution of polycyclic aromatic hydrocarbons (PAHs) and PAH derivatives was determined during the intensive sampling campaigns of the POVA (Pollution des Vallées Alpines) research programme, in two French alpine valleys, in winter and summer. The size distributions of PAHs, oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) present large variations with year time and site type (traffic; suburban and rural). In general, these compounds were mainly associated (60–90%) with fine particles (Dp<1.3 μm) in agreement with their release from sources (primary and/or secondary). The pollutant distributions with particle size were unimodal and centred at 0.85 μm both in the Chamonix and Maurienne valleys. The summer size distribution of NPAHs was centred at Dp=2.75 μm. PAH, OPAH and NPAH super micrometre fractions were significantly larger in summer for most sites suggesting the existence of a second mode in that particle size range. A possible reason to explain this phenomenon is that aerosol was locally polluted and characterised by fine particles in winter whereas in summer, aerosol was more mixed and older with possibilities of adsorption of gaseous organic compounds at the surface of the pre-exiting particles. In summer, NPAHs were associated to a greater degree with the super micrometre fraction of the aerosol than the other categories of compounds.Atmospheric Environment.