TY - JOUR
T1 - A methodology for measuring size-dependent chemical composition of ultrafine particles
AU - Geller, Michael D.
AU - Kim, Seongheon
AU - Misra, Chandan
AU - Sioutas, Constantinos
AU - Olson, Bernard A.
AU - Marple, Virgil A.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2002
Y1 - 2002
N2 - Ultrafine particulate matter (PM) consists of particles mostly emitted by combustion sources but also formed during gas-to-particle formation processes in the atmosphere. Various studies have shown these particles to be toxic. The very small mass of these particles has posed a great challenge in determining their size-dependent chemical composition using conventional aerosol sampling technologies. Implementing 2 technologies in series has made it possible to overcome these 2 problems. The first technology is the USC Ultrafine Concentrator, which concentrates ultrafine particles (i.e., 10-180 nm) by a factor of 20-22. Ultrafine particles are subsequently size fractionated and collected on suitable substrates using the NanoMOUDI, a recently developed cascade impactor that classifies particles in 5 size ranges from 10 to 180 nm. The entire system (concentrator + NanoMOUDI) was employed in the field at 2 different locations in the Los Angeles Basin in order to collect ultrafine particles in 3 consecutive 3 h time intervals (i.e., morning, midday, and afternoon). The results indicate a distinct mode in the 32-56 nm size range that is most pronounced in the morning and decreases throughout the day at Downey, CA (a "source" site), affected primarily by vehicular PM emissions. While the mass concentrations at the source site decrease with time, the levels measured at Riverside, CA (a "receptor" site), are highest in the afternoon with a minimum at midday. In Riverside, ultrafine EC (elemental carbon) and OC (organic carbon) concentrations were highly correlated only during the morning period, whereas these correlations collapsed later in the day. These results indicate that in this area, ultrafine PM is generated by primary emissions during the morning hours, whereas secondary aerosol formation processes become more important as the day progresses.
AB - Ultrafine particulate matter (PM) consists of particles mostly emitted by combustion sources but also formed during gas-to-particle formation processes in the atmosphere. Various studies have shown these particles to be toxic. The very small mass of these particles has posed a great challenge in determining their size-dependent chemical composition using conventional aerosol sampling technologies. Implementing 2 technologies in series has made it possible to overcome these 2 problems. The first technology is the USC Ultrafine Concentrator, which concentrates ultrafine particles (i.e., 10-180 nm) by a factor of 20-22. Ultrafine particles are subsequently size fractionated and collected on suitable substrates using the NanoMOUDI, a recently developed cascade impactor that classifies particles in 5 size ranges from 10 to 180 nm. The entire system (concentrator + NanoMOUDI) was employed in the field at 2 different locations in the Los Angeles Basin in order to collect ultrafine particles in 3 consecutive 3 h time intervals (i.e., morning, midday, and afternoon). The results indicate a distinct mode in the 32-56 nm size range that is most pronounced in the morning and decreases throughout the day at Downey, CA (a "source" site), affected primarily by vehicular PM emissions. While the mass concentrations at the source site decrease with time, the levels measured at Riverside, CA (a "receptor" site), are highest in the afternoon with a minimum at midday. In Riverside, ultrafine EC (elemental carbon) and OC (organic carbon) concentrations were highly correlated only during the morning period, whereas these correlations collapsed later in the day. These results indicate that in this area, ultrafine PM is generated by primary emissions during the morning hours, whereas secondary aerosol formation processes become more important as the day progresses.
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U2 - 10.1080/02786820290038447
DO - 10.1080/02786820290038447
M3 - Article
AN - SCOPUS:0036261421
SN - 0278-6826
VL - 36
SP - 748
EP - 762
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
IS - 6
ER -