Fingerprinting an oil spill event (August of 2021) in the oceanic Fernando de Noronha archipelago using biomarkers and stable carbon isotopes

Abstract

After the most catastrophic oil spill event on the Brazilian coast (2019/2020), a new incident of unknown causes sent, in August of 2021, approximately 1.3 tons of plastics and oil to the Fernando de Noronha Archipelago (Brazil). The material was restricted to the area known as the windward coast, which receives the influence of the South Equatorial Current. On 18 August 2021, our research team collected samples from different oiled shoreline sites (Caieiras and Sueste beaches) to provide the chemical fingerprint of the spilled oil and to compare that with previous oil spill events and exploited oils. We combined δ13C data from whole oil, saturated and aromatic fractions with the chromatographic signature revealing the first fingerprint of the spilled oil. The biomarker signature in association with the isotopic composition of the oils (~−26.5 ‰) undoubtedly excludes the correlation with the most extensive oil spill registered in Brazil (2019/2020). Fingerprints from the spilled oil in Fernando de Noronha suggest a potential correlation with source rocks deposited in a lacustrine setting (e.g., the east coast of Brazil and the west coast of Africa). Regardless, the chromatographic signature coupled with the isotopic data excludes a direct correlation with any specific Brazilian or African oil. In the case of a new oil spill event, the reported fingerprint will be critical to verify whether the oil is coming from the same source or a different source.