New Carissa Oil Spill: Challenges to Oil Spill Source Identification

ABSTRACT High resolution gas chromatography (GC) and gas chromatography in conjunction with mass spectrometry (GCMS) were used as fingerprinting techniques in this study to link oil spilled from the New Carissa to oil taken from oil impacted locations. Analyses included normal and isoprenoid alkanes, hopanes, and steranes, as well as a range of polynuclear aromatic hydrocarbons (PAHS). The oil spilled from the New Carissa was initially thought to be limited to bunker oils. Therefore, chromatograms of these samples and selected ion monitoring (SIM) chromatograms of the components and their combinations were compared, and obvious mismatches were rejected. Initial comparisons seemed simple; however, as with the spill response itself, factors that most often are insignificant began to affect the chemical analyses. Complications and technical challenges using conventional fingerprinting methods arose for several reasons. Likely reasons are (1) the spilled oil weathered on continued exposure to environmental conditions; (2) burning could cause changes to the chemical fingerprint; and (3) potential inhomogeneity of the spill because of multiple fuel sources in five fuel tanks at the bottom of the vessel. The PAH fingerprint had limited resistance to weathering. Therefore, the hopane fingerprint was selected for its resistance to weathering and potential screening power. Preburn and postburn New Carissa oil was characterized using principal component analysis (PCA) to determine if new and seemingly unrelated tarballs could be derived from the New Carissa spill. Response personnel will benefit from the lessons learned about potential complications of oil identification and subsequent determination of origin.