HR: 15:10h
AN: A33C-07    [Abstracts]
TI: Characterization of Particulate Inorganic Ions At Selected IMPROVE Sites
AU: Lee, T
EM: thlee@lamar.colostate.edu
AF: Dept. of Atmospheric Science, Colorado State University 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: * Yu, X
EM: xiaoying@lamar.colostate.edu
AF: Dept. of Atmospheric Science, Colorado State University 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: Ayres, B
EM: bayres@lamar.colostate.edu
AF: Dept. of Atmospheric Science, Colorado State University 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: Kreidenweis, S
EM: sonia@atmos.colostate.edu
AF: Dept. of Atmospheric Science, Colorado State University 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AU: Collett, J L
EM: collett@lamar.colostate.edu
AF: Dept. of Atmospheric Science, Colorado State University 1371 Campus Delivery, Fort Collins, CO 80523-1371 United States
AB: Aerosol nitrate is a major contributor to fine particle mass and regional haze at many locations. In order to evaluate the quality of regional particulate nitrate measurements, six field experiments were carried out at selected IMPROVE (Interagency Monitoring of Protected Visual Environment) sites. Issues examined include recovery of nitrate from nylon collection filters, loss of particulate ammonium and nitrate from the nylon collection filters, and the chemical form and size distribution of aerosol nitrate. Five sites were included in the study: Bondville, IL, San Gorgonio Wilderness Area, CA, Grand Canyon National Park, AZ, Brigantine National Seashore, NJ, and Great Smoky Mountains National Park, TN. Field campaigns at each site were approximately one month in duration. Multiple configurations of annular denuder/filter pack systems were utilized to evaluate nylon filter extraction efficiencies (by water and by a basic sodium carbonate/bicarbonate solution) and ammonium nitrate loss daily. A Micro-Orifice Uniform Deposit Impactor (MOUDI) was used to measure ion size distributions in 48 hr samples. A Particle-Into-Liquid-Sampler coupled with two Ion Chromatographs (PILS-IC) was operated continuously with 15 minute time resolution to capture temporal variations in aerosol anion and cation concentrations. The nylon filters were found to exhibit 100% efficiency for retention of collected particulate nitrate. Deionized water was found to be as efficient as the basic solution for extracting particulate nitrate from nylon filters, even in cases where significant ammonium nitrate volatilization occurred leading to recapture of nitric acid by the filter. The deionized water filter extracts are superior for analysis of aerosol cations. Significant losses of ammonium from the nylon filters were observed, however, when ammonium nitrate was collected. Analysis of MOUDI and PILS-IC data reveal that particulate nitrate at some locations was predominantly in the form of submicron ammonium nitrate. In several studies, however, nitrate was present predominantly in coarse mode particles associated with sea salt or soil dust. Findings from this study will help investigators better understand observations of aerosol nitrate made by IMPROVE and other regional measurement networks.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting