HR: 0800h
AN: A11A-0854    [Abstracts]
TI: Wood Smoke Contribution to Ambient Aerosol in Fresno During Winter 2003-2004
AU: * Gorin, C A
EM: cgorin@lamar.colostate.edu
AF: Atmospheric Science Dept., Colorado State University, Bulding 1371, Fort Collins, CO 80523-1371
AU: Collett, J
EM: collett@lamar.colostate.edu
AF: Atmospheric Science Dept., Colorado State University, Bulding 1371, Fort Collins, CO 80523-1371
AU: Herckes, P
EM: pierre.herckes@asu.edu
AF: Chemistry Dept., Arizona State University, PO Box 872803, Tempe, AZ 85287-2803
AB: The city of Fresno, located in the San Joaquin Valley in central California, experiences elevated levels of particulate matter (PM) during the winter season. In an effort to better quantify winter-time PM and the contribution of wood smoke to pollution events in Fresno, a field campaign was conducted between December 24th, 2003 and January 15th, 2004 collecting daily samples at five sites in the city with high volume aerosol collectors. Subsequent analyses of collected samples were performed to examine the spatial variability in wood smoke concentrations in the city of Fresno, CA and to estimate the contribution of residential wood combustion to PM2.5 concentrations. The estimation of residential wood combustion contribution to ambient PM is based on the quantification of levoglucosan, a compound emitted exclusively from biomass burning. Levoglucosan was measured for all collected samples by high performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD). The use of this approach for quantification of levoglucosan has many advantages and results compare well with concentrations estimated from Gas Chromatography/Mass Spectrometry (GC/MS). Fine particle mass and carbonaceous composition were also measured for all samples. Concentrations of particulate organic tracers for meat cooking and motor vehicle exhaust were quantified by GC/MS for a subset of samples to estimate the these major sources' contributions to PM. The daily mass concentrations of PM2.5, total carbon (TC), and levoglucosan vary with meteorological conditions such as precipitation, wind, and fog events. Daily PM2.5 concentrations measured during this study did not exceed the federal 24-hour standard and the study average of 30 mircograms/m3 is two-thirds lower than a previous Fresno winter average. Lower concentrations appear to be due in part to frequent precipitation during the study period. Inter-site variability of PM2.5, TC, and levoglucosan throughout the city was generally small (typically 15% or less). During the first portion of the study levoglucosan has a strong relationship to the concentration of PM2.5. In the later portion of the study there is a significant reduction in levoglucosan relative to PM2.5 suggesting a decrease in the amount of residential wood burning or differences in removal processes (e.g., due to fog events). The largest 3-day average carbon ratio of levoglucosan to OC in this study is 4.8%, almost 30% less than previous studies. Combined the emissions from wood smoke, meat cooking, and motor vehicles appear to contribute approximately 70-80% of OC with wood smoke, on average, accounting for approximately 45% of OC and 20% of PM2.5.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005