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Titre du document / Document title

Size distribution and diurnal and seasonal trends of ultrafine particles in source and receptor sites of the Los Angeles basin

Auteur(s) / Author(s)

KIM Seongheon (1) ; SHEN Si (1) ; SIOUTAS Constantinos (1) ; YIFANG ZHU (2) ; HINDS William C. (2) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Civil and Environmental Engineering, University of Southern California, Los Angeles, California, ETATS-UNIS
(2) School of Public Health, University of California, Los Angeles, California, ETATS-UNIS

Résumé / Abstract

This paper presents results from a study conducted in two urban areas of southern California, Downey and Riverside, to examine the effect of different sources and formation mechanisms on the size distribution and temporal trends of ultrafine particles. Near-continuous data were collected for 5 months at each location. The data clearly identified Downey as a source site, primarily affected by vehicular emissions from nearby freeways, and Riverside as a receptor site, where photochemical secondary reactions form a substantial fraction of particles, along with local vehicular emissions. In Downey, the diurnal trends of total particle number concentration and elemental carbon (EC) appear to be almost identical throughout the day and irrespective of season, thereby corroborating the role of primary emissions in the formation of these particles. This agreement between EC and particle number was not observed in Riverside during the warmer months of the year, while very similar trends to Downey were observed during the winter months in that area. Similarly, the size distribution of ultrafine particles in Downey was generally unimodal with a mode diameter of 30-40 nm and without significant monthly variations. The number-based particle size distributions obtained in Riverside were bimodal, with a significant increase in accumulation mode as the season progressed from winter to summer. During the warmer months, there was also an increase in sub-100-nm particles in the afternoon hours, between 2:00 p.m. and 4:00 p.m., that also increased with the temperature. The differences observed in the ultrafine particle distribution and temporal trends clearly demonstrated that mechanisms other than direct emissions play an important role in the formation of ultrafine particles in receptor sites of the Los Angeles Basin.

Revue / Journal Title

Journal of the Air & Waste Management Association    ISSN  1096-2247   CODEN JAWAFC 

Source / Source

2002, vol. 52, no3, pp. 297-307 (25 ref.)

Langue / Language

Anglais

Editeur / Publisher

Air & Waste Management Association, Pittsburgh, PA, ETATS-UNIS  (1995) (Revue)

Mots-clés anglais / English Keywords

America

;

North America

;

United States

;

Ambient air measurement

;

Surveillance

;

Formation mechanism

;

Atmospheric chemistry

;

Pollutant formation

;

Pollutant emission

;

Pollution source

;

Seasonal variation

;

Diurnal variation

;

Time variation

;

Particle size distribution

;

Chemical composition

;

Particle number

;

Ambient air concentration

;

Ultrafine particle

;

Aerosols

;

Suspended particle

;

Air quality

;

Air pollution

;

Rural area

;

Urban area

;

California

;

Mots-clés français / French Keywords

Amérique

;

Amérique du Nord

;

Etats Unis

;

Mesure air ambiant

;

Surveillance

;

Mécanisme formation

;

Chimie atmosphérique

;

Formation polluant

;

Emission polluant

;

Source pollution

;

Variation saisonnière

;

Variation diurne

;

Variation temporelle

;

Distribution dimension particule

;

Composition chimique

;

Nombre particule

;

Teneur air ambiant

;

Particule ultrafine

;

Aérosol

;

Particule en suspension

;

Qualité air

;

Pollution air

;

Zone rurale

;

Zone urbaine

;

Riverside

;

Downey

;

Californie

;

Mots-clés espagnols / Spanish Keywords

America

;

America del norte

;

Estados Unidos

;

Medida aire ambiental

;

Vigilancia

;

Mecanismo formacion

;

Formación contaminante

;

Emisión contaminante

;

Fuente polución

;

Variación estacional

;

Variación diurna

;

Variación temporal

;

Distribución dimensión partícula

;

Composición química

;

Número partícula

;

Contenido aire ambiental

;

Partícula ultrafina

;

Aerosol

;

Partícula en suspensión

;

Calidad aire

;

Contaminación aire

;

Zona rural

;

Zona urbana

;

California

;

Localisation / Location

INIST-CNRS, Cote INIST : 11485, 35400010036292.0050

Nº notice refdoc (ud4) : 13534542



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