Molecular marker analysis has been applied to organic matter in vehicular exhaust and various source materials. Vehicular exhaust can be distinguished from the natural background (mainly plant wax and resin residues in ambient aerosols) by the presence of petroleum residues in the form of characteristic homologous compounds and geologically mature molecular markers (steranes, triterpanes, PAH). Incomplete combustion products such as oxy-PAH compounds, ketones, aldehydes and carboxylic acids are also present in vehicular exhausts. These compound suites can be distinguished from emissions of biomass burning, which contain specific thermally-altered biomarker compounds. The characteristic molecular marker signatures of vehicular emissions and smoke can thus be quantified and distinguished from the natural background of vegetative emissions to ambient aerosols.
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