Identification of source of a marine oil-spill using geochemical and chemometric techniques

The current work aimed to identify the source of an oil spill off the coast of Maranhão, Brazil, in September 2005 and effect a preliminary geochemical survey of this environment. A combination of bulk analytical parameters, such as carbon isotope (δ13C) and Ni/V ratios, and conventional fingerprinting methods (High Resolution Gas Chromatography and Mass Spectrometry) were used. The use of bulk methods greatly speeded source identification for this relatively unaltered spill: identification of the likely source was possible at this stage. Subsequent fingerprinting of biomarker distributions supported source assignment, pointing to a non-Brazilian oil. Steranes proved the most useful biomarkers for sample correlation in this work. Distribution patterns of environmentally more resilient compound types, such as certain aromatic structures, proved inconclusive for correlation, probably in view of their presence in the background.

Research highlights► San Marcos bay (Maranhao, Brazil) contains small levels of petroleum hydrocarbons. ► Oil pollution in San Marcos bay is low-level but chronic. ► Aliphatic biomarkers were more useful for spill-oil source correlation in the area.