title: Aerosol chemical and optical properties during the Mt. Zirkel Visibility Study.
abstract: Aerosol chemical and optical properties were measured near the Mt. Zirkel Wilderness Area in northwestern Colorado. Six-hour PM2.5 (particles with aerodynamic diameters less than 2.5 microm) mass concentrations and PM2.5 dry particle light scattering at 550 nm averaged 4.6 microg m(-3) and 8.6 Mm(-1), respectively. Sulfates, organic carbon, and geological material were the principle components of particle mass and light scattering. Hygroscopic growth was consistent with that expected for ammonium sulfate aerosols. Size distributions derived from three-wavelength (i.e., 450, 550, and 700 nm) nephelometer data were similar to those measured in other remote areas of the western USA. Quasi-dry chemical light scattering efficiencies derived using Mie theory were 3.6 m2 g(-1) for organic carbon, 2.5 m2 g(-1) for sulfates (ammonium sulfate and ammonium bisulfate), 2.6 m2 g(-1) for ammonium nitrate, and 1.76 m2 g(-1) for geological material. These values are lower than but consistent with previously reported results. Realistic efficiencies could not be derived using the multiple linear regression (MLR) approach.
authors.affiliation: Desert Research Institute, Reno, NV 89512, USA. johnw@dri.edu
authors.forename: J G
authors.initials: JG
authors.lastname: Watson
authors.forename: J C
authors.initials: JC
authors.lastname: Chow
authors.forename: D H
authors.initials: DH
authors.lastname: Lowenthal
authors.forename: C F
authors.initials: CF
authors.lastname: Cahill
authors.forename: D L
authors.initials: DL
authors.lastname: Blumenthal
authors.forename: L W
authors.initials: LW
authors.lastname: Richards
authors.forename: H
authors.initials: H
authors.lastname: González Jorge
mesh_terms: D000336:Aerosols / Q000032:analysis; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D003120:Colorado; D004784:Environmental Monitoring; D055095:Optics and Photonics; D010316:Particle Size; D012016:Reference Values; D012044:Regression Analysis
chemical_list: D000336:Aerosols; D000393:Air Pollutants