Comprehensive Study of a Heavy Fuel Oil Spill: Modeling and Analytical Approaches to Understanding Environmental Weathering

Karin Lemkau, Ph.D., 2012
Christopher Reddy, Advisor

Samples collected after the 2007 M/V Cosco Busan heavy fuel oil spill (San Francisco, CA) were analyzed using one- and two-dimensional gas chromatography (GC and GC×GC), numerical modeling and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to examine natural weathering of the oil over a one and a half year period. Varying degrees of evaporation/ dissolution, biodegradation and photodegradation were observed across sampling sites. GC×GC was used to further examine the processes of evaporation and dissolution, and a physiochemical model was developed to approximate quantitative apportionment of compounds lost to the atmosphere and water. Model results suggest temperature is the primary control on evaporation. FT-ICR MS was used to examine the non-GC amenable component of the oil. Losses of higher molecular weight species and the formation of stable core structures were observed with time. Research findings indicate that environmental weathering results in removal or alteration of larger alkylated compounds as well as loss of lower molecular weight species through weathering processes, with a resultant fraction of stable compounds likely to remain in the environment years after the spill. This research demonstrates the advantages of combining multiple analytical and modeling approaches for a fuller understanding of oil spill chemistry.