This study aimed to characterise aerosols sampled in the vicinity of a major industrialised area, i.e. the Vaal Triangle. It included thedetermination of oxidative potential as a predictive indicator ...of particle toxicity. Aerosol samples were collated through the cascadefiltering during an eight-month period (12 h over three days in one week). Three size fractions were analysed for organic carbon(OC), black carbon (BC) and oxidative potential (OP), while ionic content was presented as monthly and seasonal concentrations. Thecontinuous measurement of black carbon by an optical attenuation instrument was collated concurrently with cascade filtering. Thecarbonaceous content was low compared to the ionic one. Within the carbonaceous concentrations, the organic carbon was higherthan concentrations of black carbon in both seasons in the ultra-fine fraction; the opposite was the case for the fine fraction, whilethe coarse fraction concentrations of organic carbon in the dry season had higher concentrations than black carbon in the wet seasonand organic carbon in the wet season. The OP tended to increase as the size was decreasing for wet season aerosols, whereas, forthe dry season, the highest OP was exerted by the fine fraction. The ultrafine fraction was the one showing the most contrasting OPbetween the two seasons. Continuous monitoring indicated that the higher BC concentrations were recorded in the dry/winter partof the year, with the daily pattern of concentrations being typically bimodal, having both the morning and evening peaks in bothseasons. Within the ionic content, the dominance of sulphate, nitrate and ammonium was evident. Multiple linear correlations wereperformed between all determined compounds. Strong correlations of carboxylic acids with other organic compounds were revealed.These acids point to emissions of VOC, both anthropogenic and biogenic. Since they were equally present in both seasons, a mixtureof sources was responsible, both present in the wider area and throughout the year.
This study aimed to characterise aerosols sampled in the vicinity of a major industrialised area, i.e. the Vaal Triangle. It included the determination of oxidative potential as a predictive ...indicator of particle toxicity. Aerosol samples were collated through the cascade filtering during an eight-month period (12 h over three days in one week). Three size fractions were analysed for organic carbon (OC), black carbon (BC) and oxidative potential (OP), while ionic content was presented as monthly and seasonal concentrations. The continuous measurement of black carbon by an optical attenuation instrument was collated concurrently with cascade filtering. The carbonaceous content was low compared to the ionic one. Within the carbonaceous concentrations, the organic carbon was higher than concentrations of black carbon in both seasons in the ultra-fine fraction; the opposite was the case for the fine fraction, while the coarse fraction concentrations of organic carbon in the dry season had higher concentrations than black carbon in the wet season and organic carbon in the wet season. The OP tended to increase as the size was decreasing for wet season aerosols, whereas, for the dry season, the highest OP was exerted by the fine fraction. The ultrafine fraction was the one showing the most contrasting OP between the two seasons. Continuous monitoring indicated that the higher BC concentrations were recorded in the dry/winter part of the year, with the daily pattern of concentrations being typically bimodal, having both the morning and evening peaks in both seasons. Within the ionic content, the dominance of sulphate, nitrate and ammonium was evident. Multiple linear correlations were performed between all determined compounds. Strong correlations of carboxylic acids with other organic compounds were revealed. These acids point to emissions of VOC, both anthropogenic and biogenic. Since they were equally present in both seasons, a mixture of sources was responsible, both present in the wider area and throughout the year.
Health Impact Assessment (HIA) associated to air pollution requires a quantified knowledge of population exposure. This exposure may be measured or estimated, individually or collectively. From a ...collective point of view, several approaches allow a spatial estimation of population exposure: 1) a so called “deterministic” approach which transforms emissions derived from inventories into atmospheric concentrations, 2) a so called “probabilistic” approach which consists in spatializing concentrations obtained from an air quality monitoring network, with geostatistical techniques. Despite their respective uncertainties, the relevance of both approaches depends on the objective of the HIA. To predict health benefits attributable to regulatory norms limitating traffic emissions, these approaches have to be combined. Geostatistics allow this integration and give access to an estimate of the uncertainty associated to the spatial estimation of the pollutant. The goal of the present work is to evaluate the feasibility of such a combination of approaches for the spatial estimation of population exposure to PM10 annual means in France in 2000. It is coming from a study about health impact assessment of air pollution attributable to road traffic in urban areas in 2000 and 2010, with a focus on children. This study has been realized in the framework of the UNECE-WHO Pan European Program for Transport, Health and Environment (THE PEP Project): “Transport-related health impacts and their costs and benefits with a particular focus on children“.Advantages and drawbacks of the existing methodologies for air pollution mapping dedicated to population exposure are first discussed. Then, the case study and the main steps of a geostatistical approach are presented, together with the results obtained in terms of PM10 mapping and population exposure in 2000.
L’évaluation des impacts sanitaires liés à la pollution atmosphérique requiert la connaissance quantifiée de l’exposition des populations. Cette exposition peut être mesurée ou estimée, individuellement ou collectivement. Au plan collectif, plusieurs approches permettent d’estimer la répartition spatiale des expositions : 1) l’approche dite « déterministe » part de l’inventaire des sources et de leurs flux d’émission et calcule les concentrations atmosphériques résultantes, 2) l’approche dite « probabiliste » spatialise des résultats de mesures issues du réseau de surveillance de la qualité de l’air par interpolation géostatistique. Outre leurs incertitudes propres, la pertinence de ces deux approches dépend des objectifs de l’étude des impacts sanitaires. Concernant la prévision des bénéfices sanitaires attribuables aux normes limitant les émissions des véhicules routiers, une combinaison des deux approches s’avère nécessaire. Cette combinaison est possible par l’intermédiaire des méthodes géostatistiques, qui présentent en outre l’avantage de fournir une estimation des incertitudes liées à la cartographie du polluant. L’objectif de cette étude est donc de tester la faisabilité d’une approche combinée déterministe/probabiliste pour la détermination de la répartition spatiale de l’exposition moyenne annuelle aux PM 10 en France métropolitaine en 2000. Elle fait partie d’une étude portant sur l’évaluation des impacts sanitaires de la pollution atmosphérique liée au trafic routier dans les zones urbaines, en se focalisant en particulier sur les enfants et en comparant les situations en 2000 et en 2010. Cette étude s’inscrit dans le cadre du programme UNECE-WHO Pan European Program for Transport, Health and Environment (THE PEP Project) : « Transport-related health impacts and their costs and benefits with a particular focus on children ». Les avantages et inconvénients des méthodes permettant d’évaluer l’exposition des populations à la pollution atmosphérique sont tout d’abord discutés. Le cas d’étude et les principales étapes d’une combinaison géostatistique sont ensuite présentés, ainsi que les résultats obtenus pour l’évaluation des populations exposées aux PM 10 en France en 2000.
Nous proposons une démonstration originale et élémentaire de l'existence de points fixes attractifs s'accumulant à l'origine pour les sous-groupes non résolubles de Aut(
C
,
0). C'est une nouvelle ...application du théorème de Nakai.
We give an original and elementary proof of the existence of attractive fixed points accumulating at the origine for
Aut(
C
,
0)
non solvable subgroups. This is a new application of Nakai's theorem.
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