Qualitative evaluation of m/z 85, 87, and 133 signals in organic aerosol mass spectra of fly ash produced by coal combustion

Abstract

Quantitative estimation of particulate matter (PM) pollution from coal combustion, which is one of the major anthropogenic emission sources in China, is urgently needed to better understand transboundary pollution in the East Asian region. As a first step, we conducted laboratory experiments for the mass spectrometric characterization of fly ash from coal combustion using a fluidized bed reactor. Here, we report detection of notable signals at m/z 85, 87, and 133 in mass spectra for organic species obtained by an Aerodyne quadrupole aerosol mass spectrometer (AMS). Nine different coals, six of which were mined in north-east Asian region, were tested with three different combustion temperatures. The results showed that signals at m/z 85, 87, and 133 were significantly larger than those at the adjacent m/z, with similar observations having been made in different field studies carried out in western Japan. The m/z 85 to m/z 87 ratios were reproducible over the coals tested, suggesting the potential usefulness of these for fingerprinting coal combustion PM. The average ratio with the standard error of the mean was 2.8 ± 0.1. While the m/z 133 to m/z 87 ratios varied more, the mean ratio with the standard error of the mean was 1.5 ± 0.2, and the results were still reproducible. A comparison of the m/z 85 and 133 to m/z 87 ratios from other studies that also used AMS suggests that the ratios obtained in the current work are distinctive from those for vehicular emissions, plastic burning, and cooking emissions, but close to those for biomass burning. Despite this similarity, the results here still offer useful information for source identification of PM with the use of AMS measurements. © Taiwan Association for Aerosol Research.