Presence and Distribution of Polycyclic Aromatic Hydrocarbons in Sediment Contaminated with Tar Sands Crude Oil

摘要

Contamination of sediment with polycyclic aromatic hydrocarbons (PAHs) derived from heavy crude oils (ex. tar sands oil) pose significant threats to human health as well as to the natural ecosystem. These compounds may persist in the environment for long periods of time following a crude oil spill. As such, this study sought to evaluate the persistence of PAHs in sediment and possible correlation between PAH distribution and grain size. This was accomplished through the collection of sediment samples from a portion of river bank along the Kalamazoo River near Ceresco, MI. Five years previously, a pipeline break spilled an estimated 843,000 gallons of diluted bitumen being transported from Alberta, Canada’s Athabasca oil field. Samples were collected from two areas: 1) an area of the river bank that was reworked following the spill and 2) an area in the floodplain thought to have been inundated with oil at the time of the spill but has since remained relatively undisturbed. The samples were analyzed using gas chromatography-flame ionization detection (GC-FID) for 17 PAHs known to have potentially harmful human and ecosystem health effects. Results indicate the presence of PAHs in all samples, including individual compounds which can be used as biomarkers for the Athabasca oil field. In addition, a detailed analysis of grain size was carried out on each sediment sample. There is some variability in the presence of specific PAHs between sample location and sediment grain size fraction, though identifying a clear correlation is complex. Since production and transportation of tar sands oil is projected to increase in the coming years, understanding the fate of PAHs in the environment is crucial to remediation preparedness. By relating the persistence of PAH compounds to grain size in a dynamic natural environment, it may be possible to better predict areas where PAHs may concentrate in future spills of tar sands oil, thus better informing future remediation efforts in similar environments.