Authors: Kerr S.C.; Schauer J.J.; Rodger B.

Source: Journal of Environmental Engineering and Science, Volume 3, Number 3, May 2004 , pp. 213-222(10)

Publisher: NRC Research Press

Abstract:

The atmospheric fine particulate matter (PM_2.5) chemical composition and the light scattering coefficient were measured at a rural air monitoring site in Wisconsin between September 2001 and August 2002 to understand the source of regional haze in the area. The average fine particle mass concentration, was 10.8 µg/m³ over this time period and was 27.2% organic material, 2.4% elemental carbon, 34.2% ammonium sulfate, 31.6% ammonium nitrate, 3.7% soil, and 1.8% non-soil trace elements. Ammonium sulfate, organic matter, and soil were highest during the summer period while ammonium nitrate was highest during the winter. Elemental carbon peaked in the fall while the trace elements did not vary significantly. These trends were also observed at an urban Milwaukee site. A comparison of spring 2002 data between sites distributed across Wisconsin revealed a similar relative chemical composition, though absolute concentrations varied significantly. The average measured light scattering coefficient (b_sp) at the rural sampling site was 53 ± 1 Mm^–1. The PM_2.5 mass and the measured b_sp showed good correlation with an R² of 0.84. The average chemical composition of the particulate matter was used to calculate b_sp and the resulting values agree well with the measured b_sp, though not as well as the PM_2.5 mass, giving a regression slope of 1.06 and an R² of 0.72. Key words: PM_2.5 chemical speciation, light scattering coefficient, visibility.

La composition chimique des particules en suspension dans l'air (PM_2.5) et le coefficient de diffusion de la lumière ont été mesurés à un site rural de suivi de l'air au Wisconsin entre septembre 2001 et mai 2002 afin de comprendre la source de la brume régionale. La concentration massique moyenne des particules en suspension durant cette période, était de 10,8 µg/m³; ces particules étaient composées de 27,2 % de matières organiques, 2,4 % de carbone élémentaire, 34,2 % de sulfate d'ammonium, 31,6 % de nitrate d'ammonium, de 3,7 % de sol et 1,8 % d'éléments traces non pédologiques. Le sulfate d'ammonium n'a pas varié de manière significative durant la période d'échantillonnage, mais le nitrate d'ammonium était à son plus élevé durant la périodehivernale, alors que les carbones organique et élémentaire étaient plus élevés à l'automne. Ces tendances ont également été observées dans un site urbain de Milwaukee. Une comparaison des données du printemps 2002 entre les sites répartis dans le Wisconsin a révélé une composition chimique similaire, bien que les concentrations absolues variaient significativement. Le coefficient moyen de diffusion de la lumière (b_sp) au site rural d'échantillonnage était de 53 ± 1 Mm^–1. La masse de PM_2.5 et le b_sp mesuré montrent une bonne corrélation, avec un R² de 0,83. La composition chimique moyenne des matières organiques a été utilisée pour calculer le b_sp et les valeurs en découlant correspondent bien au b_sp mesuré, mais pas aussi bien que les corrélations empiriques entre la masse de PM_2.5 et la diffusion de la lumière. Mots clés : spéciation chimique des particules en suspension PM_2.5, coefficient de diffusion de la lumière, visibilité.[Traduit par la rédaction]

Keywords: PM2.5 chemical speciation, light scattering coefficient, visibility, spéciation chimique des particules en suspension PM2.5, coefficient de diffusion de la lumière, visibilité

Document Type: Research article

Publication date: 2004-05-01

More about this publication?

• Since January 2002, NRC Research Press has published the Journal of Environmental Engineering and Science. During the seven-year history of the journal, the co-editors, Dr. Donald S. Mavinic and Dr. Daniel W. Smith, built a high-quality journal that was well respected by its community of researchers in Canada and around the world. The last issues of the Journal of Environmental Engineering and Science was published in November 2008 together with a supplement.

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