Synergy of Analytical Approaches Enables a Robust Assessment of the Brazil Mystery Oil Spill

Abstract

viscous oil residues appeared along the Brazilian coast spanning 11 states and more than 3,000 km of tropical shoreline. Forensic results published to date indicate that the majority of oil samples collected share a common origin, yet the exact source of the mystery oil has yet to be conclusively determined. The proposed sources include illegal discharges from vessels traversing near, within, or downstream of Brazilian waters, leaking offshore platforms, natural seeps, and historic shipwrecks. To constrain the potential sources of oil and provide additional insights into the composition of the oil, we analyzed samples collected from the Cearástate coastal zone in 2019 with a broad suite of geochemical tools and approaches. These approaches included bulk elemental analyses and state-ofthe-art analytical platforms including comprehensive two-dimensional gas chromatography (GC × GC), gas chromatography with triple-quadrupole mass spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry. Based on bulk and molecular features, field samples collected from northeast Brazil share the same source as other 2019 mystery oil samples collected over ∼2400 km to the south. A shared source across the Brazilian coast points to an input location east of Brazil within the southern branch of the South Equatorial Current, allowing transport both north and south of the bifurcation. The relative abundance and composition of diagnostic markers were consistent with the published analyses of Venezuelan petroleum. The composition of the field samples is consistent with the blending of, at least, two different petroleum products, a common practice to produce an "on spec" product such as a fuel oil used to power an underway vessel. The two components appear to be the residuum from atmospheric distillation and a thermally altered, aromatics-rich, nondistilled material. To the best of our knowledge, no samples from potential sources are available for a direct comparison to field samples. Hence, these results play a supporting role in determining the source, and benefit efforts to understand short-and long-term weathering and recovery.

Geochemical Assessment of Tar Balls That Arrived in 2022 along the Northeast Coast of Brazil and Their Relationship with the 2019 Oil Spill Disaster

“…As reported by Reddy et al, 3 the distribution of methyl phenanthrenes/anthracenes in several samples from the 2019 oil spill, obtained by GC−MS monitoring at m/z 192, presented a higher abundance of the doublet peaks of 2-and 3-MP compared to the doublet peaks of 9-/4-MP and 1-MP as well as the presence of methyl anthracene (MA), which reflected characteristics of cracked products of crude oils rather than virgin oil. As shown in Figure 3, a similar GC−MS profile were found for 2019 samples, as described by Reddy et al 3 However, an inverse relationship between the doublet peaks for phenanthrenes was obtained for 2022 samples, together with the absence (or presence in trace amounts) of MA, classifying them as virgin crude oil without preprocessing. Determination of basic polar compounds by ESI(+) FT−MS revealed differences in the mass distributions when the mass spectra for the two samples were compared (Figure 4).…”

“…The most recent hypothesis suggests a shipwreck from World War II (WWII) as the origin of the 2019 spill. 3 If this hypothesis is true, then the source of the 2022 spill could indeed be the same shipwreck that had transported both the mystery processed oil (2019) and the crude oil from storage tanks (2022). Alternatively, it is also possible that they originated from different sources altogether.…”

“…1,2 The oil was described as a dark and viscous material that first appeared along the coastline of northeast Brazil in 2019, reappearing intermittently in 2020 and 2021 after periods of strong winds, high waves, and spring tides. 3 Among several hypotheses about the cause of the spill, Soares et al 4 pointed out that the main ongoing debate concerning the spilled oil is whether the source was release from ships in transit off of the Brazilian coast (intentionally or not) or from shipwrecks (recent or old).…”

“…In August 2019, a mysterious oil spill reached the northeast coast of Brazil, entering history as the greatest environmental disaster related to oil spills to have occurred in the country, causing extensive coastal contamination, damage to ecosystems, and socioeconomic impacts. , The oil was described as a dark and viscous material that first appeared along the coastline of northeast Brazil in 2019, reappearing intermittently in 2020 and 2021 after periods of strong winds, high waves, and spring tides . Among several hypotheses about the cause of the spill, Soares et al pointed out that the main ongoing debate concerning the spilled oil is whether the source was release from ships in transit off of the Brazilian coast (intentionally or not) or from shipwrecks (recent or old).…”

“…Figure 1. Map of the coastline of Brazil, showing the oil spills that occurred in 2019 (blue line) and 2022 (orange line), the oil collection locations in the most recent studies, and the samples collected on the coast of Pernambuco in the present work and the work by Reddy et al,3 Carregosa et al,5 de Oliveira et al,12 and Lourenco et al13 This figure was adapted with permission from ref 3. Copyright 2022 American Chemical Society.…”