title: Characterization of selenium in ambient aerosols and primary emission sources.
abstract: Atmospheric selenium (Se) in aerosols was investigated using X-ray absorption near-edge structure (XANES) spectroscopy and X-ray fluorescence (XRF) microscopy. These techniques were used to determine the oxidation state and elemental associations of Se in common primary emission sources and ambient aerosols collected from the greater Atlanta area. In the majority of ambient aerosol and primary emission source samples, the spectroscopic patterns as well as the absence of elemental correlations suggest Se is in an elemental, organic, or oxide form. XRF microscopy revealed numerous Se-rich particles, or hotspots, accounting on average for ∼16% of the total Se in ambient aerosols. Hotspots contained primarily Se(0)/Se(-II). However, larger, bulk spectroscopic characterizations revealed Se(IV) as the dominant oxidation state in ambient aerosol, followed by Se(0)/Se(-II) and Se(VI). Se(IV) was the only observed oxidation state in gasoline, diesel, and coal fly ash, while biomass burning contained a combination of Se(0)/Se(-II) and Se(IV). Although the majority of Se in aerosols was in the most toxic form, the Se concentration is well below the California Environmental Protection Agency chronic exposure limit (∼20000 ng/m(3)).
authors: School of Earth and Atmospheric Sciences, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332-0340, United States.
authors: Arlette
authors: A
authors: De Santiago
authors: Amelia F
authors: AF
authors: Longo
authors: Ellery D
authors: ED
authors: Ingall
authors: Julia M
authors: JM
authors: Diaz
authors: Laura E
authors: LE
authors: King
authors: Barry
authors: B
authors: Lai
authors: Rodney J
authors: RJ
authors: Weber
authors: Armistead G
authors: AG
authors: Russell
authors: Michelle
authors: M
authors: Oakes
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D005845:Georgia; D008856:Microscopy, Fluorescence; D010084:Oxidation-Reduction; D012643:Selenium / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity; D013052:Spectrometry, X-Ray Emission; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D012643:Selenium