HR: 1340h
AN: A33B-0898    [Abstracts]
TI: The dry Deposition and Resusepnsion of Particle-Associated Trace Metals Near a Freeway in Los Angeles
AU: * LIM, J
EM: jhlim@ucla.edu
AF: UCLA, 420 Westwood Plz. University of California, Los Angeles Civil & Environmental Engineering Dept., Los Angles, CA 90095
AU: SABIN, L D
EM: lisas@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683
AU: VENEZIA, M T
EM: teresav@ucla.edu
AF: UCLA, 420 Westwood Plz. University of California, Los Angeles Civil & Environmental Engineering Dept., Los Angles, CA 90095
AU: STOLZENBACH, K D
EM: stolzenb@ucla.edu
AF: UCLA, 420 Westwood Plz. University of California, Los Angeles Civil & Environmental Engineering Dept., Los Angles, CA 90095
AU: SCHIFF, K C
EM: kens@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683
AB: Dry atmospheric deposition represents a potentially large source of trace metal contamination in urban stormwater runoff, yet there is a limited amount of research on the relationship between atmospheric emissions and water quality problems in urban areas. In Los Angeles, which has among the worst air quality in the nation, significant quantities of toxic materials are released into the atmosphere every day, and paved road dust represents the largest source of particle-associated trace metal emissions to the atmosphere. In order to better understand the role of roadways as a source of localized trace metal deposition, we characterized the horizontal dry deposition pattern of chromium, copper, nickel, lead and zinc upwind and at increasing distances downwind of the I-405 Freeway in coastal Los Angeles. Dry deposition fluxes and atmospheric concentrations of these metals were highest at the site closest to the freeway, and reduced to approximately urban background concentrations within 450 m or less downwind of the freeway. Compared with urban background, atmospheric particle size distributions indicated the freeway was a significant source of trace metals on large particles > 6 æm in diameter, which deposit close to their source and account for the increased dry deposition flux rates observed near the freeway. The spatial pattern of measured deposition flux is well-predicted by a relatively simple line-source Gaussian plume model modified to include particle deposition and resuspension. The model results indicate that dilution by vertical dispersion of the plume is the most important mechanism regulating downwind concentrations and deposition.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005