A Bottled High-Sulfur Fuel Oil Stranded with the Mysterious Oil Spill on the Brazilian Coast in Early 2022: Geochemical Correlation and Ocean Dumping Evidence

This study conducted a comprehensive forensic geochemical and chemical assessment of bottled oil labeled with a foreign marine bunker company stranded on a Ceará beach, Northeast Brazil, in January 2022, and compared it to the mysterious oil spill that affected ∼342 km of the Ceará coast at that time. The saturated and aromatic composition was assessed by conventional gas chromatography (GC-FID and GC-MS) and comprehensive two-dimensional gas chromatography (GC × GC-FID). In addition, the bottled oil was also assessed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), CHNS elemental analyses, and microscopic imaging. The bimodal unresolved complex mixture (UCM) in the GC-FID chromatogram; the considerable abundance of anthracene, 2-methylanthracene, and other polycyclic aromatic hydrocarbons (PAHs) with four, five, and six rings; and the high abundance in carbon 40 observed for the N1 class for the bottled oil are consistent with heavy fuel oil (HFO), probably an IFO 380. It has a high sulfur content (2.5%) outside the 2020 International Maritime Organization (IMO) specifications (%S < 0.5) unless the vessels are equipped with exhaust gas cleaning systems (EGCS or scrubbers). The fuel oil also has a high amount of catalytic fines, rich in Al and Si, which are known to damage marine engines and pose a potential threat to the environment. Resistant biomarkers (e.g., terpanes, steranes, C30 tetracyclic polyprenoids, and triaromatic steranes) and the GC-FID profile showed that this fuel oil geochemically correlates with the early 2022 oil spill, disclosing the spilled oil source from fuel dumping by an international tanker on the South Atlantic Ocean route. Fingerprint dissimilarities of the more volatile compounds indicate intense weathering or two different vessel fuel tanks. The high sulfur content and the presence of catalytic fines may explain the oil being disposed of into the sea.