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Dry deposition flux of sulfate and nitrate in Chicago

Conference ·
OSTI ID:353488
; ;  [1]
  1. Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical and Environmental Engineering
Atmospheric size distributions for total mass, sulfate and nitrate were measured in Chicago, Illinois during the Spring, Summer, and Fall of 1994 and 1995. Nineteen samples were collected over two or three day time periods using a Wide Range Aerosol Classifier (WRAC) system Noll Rotary Impactor (NRI) and Cascade Impactor. The Atmospheric Aerosol was divided into 10 size range between 0.1--100 {micro}m. Dry deposition fluxes were simultaneously measured with a knife edged surrogate surface containing greased mylar films. Data show that sulfate and nitrate existed in both the fine (<2.5 {micro}m) and coarse (>2.5{micro}m) particles. The atmospheric concentration of sulfate in the fine and coarse particles varied between 1.0--7.0 {micro}g/m{sup 3} and 0.3--1.0 {micro}g/m{sup 3} respectively. The nitrate concentrations were 0.3--5.3 {micro}g/m{sup 3} in the fine and 0.3--2.9 {micro}g/m{sup 3} in the coarse fraction. The measured dry deposition fluxes of sulfate and nitrate were between 1.0--4.0 and 0.5--3.9 mg/(m{sup 2}/day) respectively. A multistep method was used to calculate total and cumulative deposition flux with the Sehmel-Hodgson deposition velocity model and atmospheric particulate concentration. The results indicate that calculated flux compares well with measured flux, and greater than 99% of the total flux was due to particles larger than 5 {micro}m diameter for both sulfate and nitrate. The average ratios of calculated/measured fluxes are 0.93 for sulfate and 0.91 for nitrate.
OSTI ID:
353488
Report Number(s):
CONF-970677--
Country of Publication:
United States
Language:
English