Asphalt dust influence on the distribution of polycyclic aromatic hydrocarbon in crankcase oil stains of a concrete, covered parking structure.

Used crankcase oil is an important source of environmental polycyclic aromatic hydrocarbons (PAHs). Here, we use gas chromatography-mass spectrometry (GC-MS) to measure and compare the concentration of PAHs, including alkylated PAHs, in used oil against new and old oil stains and parking dust collected from a concrete, covered, open parking structure to understand the distribution of PAH in crankcase oil stains. PAH concentration in used oils ranges from 606 ng/mg to 1,592 ng/mg. The PAH distribution in used oil does not match that observed in parking oils stains, parking background, or parking dust. A comparison with PAH distributions in traffic related dusts extracted from the literature and dust collected from a neighboring open asphalt-paved parking suggests that covered parking dust includes substantial contributions from asphalt-paved parking dust, road dust, and/or coal tar dust. The parking dust is the most concentrated source of PAHs in the covered parking structure (PAHs up to 4,371 ng/mg), a small contribution of which can alter the distribution of PAHs in oil stains. Even with this contribution, we were able to observe a significant decrease of the ratio of low molecular weight PAHs to high molecular weight PAHs, and a significant increase in values of the phenanthrene/anthracene and fluoranthene/(fluoranthene + pyrene) ratios when oil stains age, suggesting biodegradation is an active attenuation process in covered, open parking structures.