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

Abstract

In August 2019, Brazil experienced the country’s greatest environmental disaster involving an oil spill appearing on the beaches. After 3 years, high volumes of tar balls appeared, raising questions regarding their possible relationship with the oil spill of 2019. Herein, an organic geochemistry investigation was performed using gas chromatography–mass spectrometry (GC–MS) and electrospray ionization coupled with Fourier transform mass spectrometry (ESI FT–MS), with the aim of characterizing the chemical components of spilled oils collected in 2019 and comparing them to tar balls from 2022. The contents of n-alkanes, isoprenoids, alkyl cyclohexanes, steranes, terpanes, and phenanthrenes/anthracenes, together with biomarker ratios, suggested that the tar balls originated from a virgin/unprocessed oil with the profile of paraffinic deposits in oil storage tanks, unlike the oils from 2019, which had the characteristics of a processed oil. An interesting difference in polar compound distribution was identified by ESI FT–MS analysis, with lower molecular weight polar components found in the samples from 2022.

Forensic Geochemistry Reveals International Ship Dumping as a Source of New Oil Spill in Brazil’s Coastline (Bahia) in Late 2023

“…However, they are quite distinct from the GC profiles of the previous samples (Figure a). In particular, while the 2022.2 samples are bimodal in shape, with a low UCM (Figure S1e,f), , the n -alkanes of the 2022.1 samples are depleted significantly, with a very high UCM (Figure S1g,h), and the 2019 samples are unimodal, with a high UCM (Figure S1i,j). These findings were the initial evidence that the different sets of samples have distinct sources and that the 2023 oil spill represents a novel event off the Brazilian coast.…”

“…The 2023 samples have some physical similarities with the previous beached oily materials in 2019, 2022.1, and 2022.2, presenting a dark color, strong odor, and tar characteristics (Figure ). However, while the spilled oil in 2019 was a viscous liquid, , the 2022.1 spilled oil was small fragments and viscous liquid oils, , and the 2022.2 spill consisted of small to thick tarballs. , …”

“…In January 2022, a novel oil spill unrelated to the 2019 event was recorded on the coast of Ceará, which affected 400 km of the shore with more than 8000 L of oil. , In late 2022, tarballs were washed up all along the coast of northeastern Brazil. − In most cases, the oil has not been produced in Brazil but has apparently been dumped in international waters by passing ships before being carried ashore by ocean currents, representing a worldwide issue. , …”

“…However, while the spilled oil in 2019 was a viscous liquid, 27,28 the 2022.1 spilled oil was small fragments and viscous liquid oils, 13,14 and the 2022.2 spill consisted of small to thick tarballs. 16,17 Oil Extraction and Separation. Approximately 1−2 g of each tarball mixed with sediments was extracted with a solution of dichloromethane or dichromethane/methanol.…”

“…The analytical techniques employed here, in particular, conventional gas chromatography (GC), can be used to identify molecular biomarkers and, in turn, define the chemical fingerprint of the contaminants. , The methodology typically involves the assessment of the most significant factors that determine the chemical fingerprint of the oil spill, including its origin, genesis, refinement, weathering processes, and environmental mixing . This approach has been employed amply to examine and diagnose the oil spills that have affected the coast of northeastern Brazil in recent years. − ,,,− …”