Geochemical Investigation of Tar Balls Collected in a Brazilian Beach Using Biomarkers, Ni/V, δ13C Ratios and Ultra-High Resolution FT‑ICR Mass Spectrometry

Bárbara Lima,Georgiana Da Cruz,Marcos Pudenzi,Lívia Santos,Heliara Nascimento,Eliane De Souza,Laercio Martins,Marcos Eberlin

doi:10.21577/0103-5053.20190231

Bárbara Lima, Georgiana Da Cruz + Show 6 more

Open Access

https://doi.org/10.21577/0103-5053.20190231

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Abstract

Representative tar balls collected in two distinct years (2012 and 2014) in a beach along the State of Bahia, northeastern Brazil, were geochemically characterized in order to identify correlations between them and investigate potential sources. Terpanes and steranes biomarkers (detected by gas chromatography coupled to mass spectrometry, GC-MS), carbon stable isotope ratio (δ13C), Ni and V ratios and polar compounds by Fourier transform ion cyclotron resonance mass spectrometry using electrospray ionization in negative mode (ESI(-) FT-ICR MS) were evaluated. Three Brazilian oil samples from distinct sources were assessed as possible spill sources, comparing their results with the tar ball samples. Using chemometric techniques, it was verified correlation between the two set of tar ball samples, suggesting same source. However, no correlation with the oil samples was observed, with different geochemical profile among them. The heteroatom class distribution displayed severe degradation levels for tar balls and its seems that photo-oxidation and biodegradation processes were further relevant. Tar ball samples show multiple classes, most oxygenated, and with one sample showing considerable relative abundance of N1 class, suggesting it is from a more recent oil spill. In brief, our results suggest that the region, with very sensitive ecosystem, is possibly subjected to frequent spills from the same source.

Highlights

An examination of reports from several sources, including industry, government and academic, indicates that, the diversified sources of petroleum input to the sea, they can be arranged into four main groups: petroleum transportation, natural seeps, petroleum production and petroleum consumption.[1]
Biomarkers are widely used in geochemical studies since they are normally resistant to microbial alteration and weathering, being frequently used in oil spill investigations for petroleum contaminated environmental complex samples, such as tar balls.[26,36,37,38,39]
The comprehensive analysis of seven tar balls collected at the same area in a northeastern Brazilian beach but at different times with two years interval (2012 and 2014) indicated that these samples have the same spill origin

Summary

Introduction

An examination of reports from several sources, including industry, government and academic, indicates that, the diversified sources of petroleum input to the sea, they can be arranged into four main groups: petroleum transportation, natural seeps, petroleum production and petroleum consumption.[1]. These diagnostic ratios show great weathering resistance and so have been used in several studies to characterize oil spills, their levels of degradation and their sources.[42,43,44,45,46,47] The great similarity on terpanes composition and δ13C observed for tar ball samples can suggest that they are probably originated from the same spill source.

Results

Conclusion