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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Identification of the main sources and geographical origins of PM10 in the northern part of France / Identification des principales sources et origines géographiques de PM10 dans le nord de la France

Barros de Oliveira, Diogo Miguel 27 January 2017 (has links)
Les particules atmosphériques ont des impacts économiques, sanitaires et environnementaux importants à l'échelle mondiale. La réduction de leurs émissions afin d’améliorer la qualité de l'air ambiant exige une connaissance approfondie de leurs sources, qui peut être apportée par l'étude de leur composition chimique. La présente thèse vise à identifier les principales sources et origines géographiques des PM10 sur 5 sites d'échantillonnage (3 urbains, 1 trafic et 1 distant) représentatifs du Nord de la France, fréquemment soumis à des dépassements des valeurs réglementaires. La méthodologie a consisté en : (i) une caractérisation chimique complète des PM10 sur les 5 sites ; (ii) l’identification et la quantification des sources primaires et des processus secondaires pour chaque site par factorisation par matrice positive (PMF) ; (iii) l’estimation des champs de concentration (CF) des sources lointaines identifiées par PMF par combinaison avec les rétrotrajectoires de masses d’air, afin de localiser les zones d’émissions.La matière organique et le nitrate d'ammonium prédominent, avec quelques différences selon le type de site. De fortes contributions en aérosols secondaires (riches en nitrate, sulfate et oxalate) ont été observées, ainsi qu’un impact significatif du trafic et de la combustion de biomasse. Les zones d’émission identifiées pour les particules naturelles sels marins frais et vieillis (principalement de l'océan Atlantique) et biogéniques marins (principalement de la mer du Nord), et les contributions continentales anthropiques de particules secondaires riches en nitrate et sulfate, valident l’approche utilisée. / Airborne particles have significant economical, health and environmental impacts at a global scale. Mitigating their emissions to improve ambient air quality demands a deep knowledge on their sources, which can be determined by investigating their chemical composition. The present thesis aims at identifying major PM10 sources and geographical origins at 5 sampling sites (3 urban background, 1 traffic and 1 remote) representative of Northern France, which is frequently submitted to exceedances of limit values as defined by European Directives. The first step of this study included a comprehensive chemical characterization of PM10 filter samples collected every third day at the 5 sites. Organic matter and ammonium nitrate were confirmed as the main PM10 species in the investigated area with some differences according to the site type. Positive Matrix Factorization (PMF) was used to identify and quantify the contributions of primary sources as well as secondary processes impacting each sampling site. Large contributions of secondary aerosols (mainly grouped as nitrate-, sulfate- and oxalate-rich aerosols) were obtained at all sites, as well as significant traffic and biomass burning. The use of specific tracers like MSA and polyols also proved to be useful to identify marine and continental biogenic aerosols, respectively. Statistical trajectory-based model was applied to PMF outputs to calculate Concentration Field maps and locate emission sources of marine particles, namely fresh and aged sea salts (primarily from the Atlantic Ocean) and marine biogenic aerosols (mainly from the North Sea), as well as continental contributions of nitrate-and sulfate-rich secondary particles.

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