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Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis
Citation:
KHAN, BERNIE, M. D. HAYS, C. D. GERON, AND J. J. JETTER. Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis. AEROSOL SCIENCE AND TECHNOLOGY. Taylor & Francis, Inc., Philadelphia, PA, 46(2):127-137, (2011).
Impact/Purpose:
journal article
Description:
Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of optics and temperature-programming on these ratios. Aerosols from atmospheric (rural and urban) and source (residential cook stoves and diesel exhaust) emissions were examined using three TOA methods. The effects of temperature among the three TOT methods showed significantly lower OC/EC ratios for the diesel and urban aerosols (p<0.05). Similar OC/EC findings were observed for the three TOR methods. The optical effects were examined by taking the ratio of TOT/TOR for the OC/EC ratio. Aerosols containing components susceptible to charring (such as water-soluble organic compounds typical of rural and cook stove aerosols) showed higher OC/EC variability among the methods when compared to diesel-impacted aerosols, which showed little to no detectable pyrolyzed carbon (PyC). Thermal effects on the EC/TC ratios were similar to those observed for the OC/EC ratios. However, differences due to the optics were most evident for the cook stove NIST-EPA (TOT and TOR), diesel IMPROVE (TOT and TOR), urban IMPROVE (TOT and TOR), and all the rural aerosols (TOT and TOR) (p<0.05).
URLs/Downloads:
Differences in the OC/EC Ratios that Characterize Ambient and
Website
1107 HAYS.PDF (PDF, NA pp, 558 KB, about PDF)