Assessment Of The Biodegradation Potential Of Diluted Bitumen In Seawater

Diluted bitumen (dilbit) is a mixture of heavily weathered crude oil derived from oil sands and a lighter petroleum product diluent. Diluted bitumen is starting to comprise a greater proportion of oil imports to the U.S., and is the primary oil being transported by the Keystone XL Pipeline. Another common way to transport dilbit is by shipping tankers. Thus, it is critical to assess the extent of which it degrades in water. To test this, two different microcosm setups were prepared, one with autoclaved sand spiked with oil, and one with a water-accommodated fraction of oil. Three separate conditions for the water were prepared for the sand microcosm: water that has been autoclaved to kill microbes present (control), water with the natural flora present (alive), and water with natural flora and added nitrogen and phosphorus (N&P). The water-accommodated fraction microcosms utilized autoclaved water and natural seawater. At several time points, the remaining crude oil in the samples was extracted and analyzed by gas chromatography and time-of-flight mass spectrometry (GC-TOF-MS). Results from these microcosm experiments serve a stepping-off point for future biodegradation studies.