Applications of optical spectroscopy and stable isotope analyses to organic aerosol source discrimination in an urban area

• Published in: Atmospheric environment (1994) Vol. 45; no. 11; pp. 1960 - 1969
• Main Authors: Mladenov, N., Alados-Arboledas, L., Olmo, F.J., Lyamani, H., Delgado, A., Molina, A., Reche, I.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2011; Elsevier
• Subjects: Absorbance; aerosols; African dust; Applied sciences; atmospheric chemistry; Atmospheric pollution; carbon; climate; data collection; Diesel; Exact sciences and technology; factor analysis; Fluorescence; fluorescence emission spectroscopy; fossil fuels; humans; humification; naphthalene; organic matter; PARAFAC; particulates; Pollution; stable isotopes; Sun photometry; urban areas; Sierra Nevada (California); Spain; United States; North America; Europe; America; Nevada; Africa, Sahara Desert; Spain, Granada; Fluorescence; Absorbance; Diesel; Sun photometry; African dust; PARAFAC; Isotopic analysis; Organic matter; Diesel fuel; Humification; Motor vehicle; Urban area; Modeling; Fluorescence spectrometry; Coarse particle; Health and environment; Fine particle; Fossil fuel; Exhaust gas; Photometry; Public health; Organic compounds; Optical spectrometry; Factor analysis; Light scattering; Diesel engine; Dust; Ultraviolet radiation; Aerosols; Air pollution; Road traffic
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2011.01.029

Understanding the chemical character of organic aerosols is extremely important for evaluating their role in climate forcing and human respiratory health. Aerosol columnar properties retrieved by sun photometry represent a large dataset of information about the physical and light absorbing and scattering properties of the total aerosol, but lack more detailed chemical information about the organic fraction of atmospheric particulate matter. To obtain additional information about relationships between organic aerosol sources and columnar properties, we simultaneously examined stable isotope properties of PM 10 aerosols from urban (Granada, Spain) and remote (Sierra Nevada, Spain) sites and diesel exhaust, spectroscopic properties of water soluble organic carbon (WSOC) of PM 10 aerosols, and sun photometry measurements. We demonstrated that C and N stable isotopes and parameters from UV–vis and fluorescence spectroscopy are able to discriminate between aerosols receiving substantial fossil fuel pollution and those influenced by Saharan dust in an urban area. More depleted δ 13C was associated with low asymmetry parameter, g λ, and high values of the spectral slope ratio, S R, were associated with high effective radius, typical of pollution situations. The humification index (HIX), used predominantly to evaluate the degree of organic matter humification, was significantly related to g λ and the radius of fine mode particles, r f, and may reflect aging of the Saharan dust-influenced aerosols. Parallel factor analysis (PARAFAC) modeling identified a fluorescent component (C3) with a spectrum similar to that of naphthalene, which was significantly related to g λ and r f. The diesel exhaust sample represented a pollution end-member, with the lightest δ 13C value (−26.4‰), lowest S R (0.95), lowest HIX (2.77) and highest %C3 (20%) of all samples. ► Optical spectroscopy, stable isotopes differentiate dust and urban organic aerosols. ► A fluorescent component was identified that may be used to track diesel pollution. ► Optical spectroscopy reflects aerosol aging and high molecular weight compounds. ► Optical spectroscopy characterization supports columnar aerosol physical properties.