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Combustion experiments were carried out on four different residual fuel oils in a 732 kW boiler. Particulate matter (PM) emission samples were separated aerodynamically by a cyclone into fractions that were nominally less than and greater than 2.5 microns in diameter. However, examination of several of the samples by computer-controlled scanning electron microscopy (CCSEM) revealed that part of the &lt;2.5 micron fraction (PM{sub 2.5}) in fact consists of carbonaceous cenospheres and vesicular particles that range up to 10 microns in diameter. X-ray absorption fine structure (XAFS) spectroscopy data were obtained at the S, V, Ni, Fe, Cu, Zn, and As Kedges, and at the Pb L-edge. Deconvolution of the x-ray absorption near edge structure (XANES) region of the S spectra established that the dominant molecular forms of S present were sulfate (26-84% of total S) and thiophene (13-39% of total S). Sulfate was greater in the PM{sub 2.5} samples than in the &gt;2.5 micron samples (PM{sub 2.5+}). Inorganic sulfides and elemental sulfur were present in lower percentages. The Ni XANES spectra from all of the samples agree fairly well with that of NiSO4, while most of the V spectra closely resemble that of vanadyl sulfate (VO{center_dot}SO{sub 4}{center_dot}xH{sub 2}O). The other metals investigated (Fe, Cu, Zn, and Pb) were also present predominantly as sulfates. Arsenic is present as an arsenate (As{sup +5}). X-ray diffraction patterns of the PM{sub 2.5} fraction exhibit sharp lines due to sulfate compounds (Zn, V, Ni, Ca, etc.) superimposed on broad peaks due to amorphous carbons. All of the samples contain a significant organic component, with the LOI ranging from 64 to 87 % for the PM{sub 2.5} fraction and from 88 to 97% for the PM{sub 2.5+} fraction. {sup 13}C nuclear magnetic resonance (NMR) analysis indicates that the carbon is predominantly condensed in graphitic structures. Aliphatic structure was detected in only one of seven samples examined

Source Signatures of Fine Particulate Matter from Petroleum Refining and Fuel Use