Fingerprinting cromatográfico de hidrocarbonetos alifáticos da zona estuarina do rio cocó: indícios do derramamento de óleo no nordeste brasileiro

Abstract

Coastal environments are areas that constantly suffer environmental impacts by receiving waste from both the continent and the marine environment. These regions are subject to environmental disasters such as crude oil spills. In 2019, the northeast coast suffered the greatest national impact from an oil spill, affecting its coastal ecosystems. In these regions are estuarine zones that are ecologically important due to their unique characteristics and extensive biodiversity, being considered the nursery of marine fauna. The estuarine zone of the Cocó River, which is located in an environmental protection area (EPA), and covers the Sabiaguaba beach, one of the places most impacted by the spill. This work aims to characterize the chromatographic fingerprinting of sediment and crude oil extracts (sand pattie) collected in the estuarine zone of the Cocó River and the Sabaguaba beach strip in 2021, evaluating the distribution of n-alkanes and isoprenoids (pristane and phytane), as well as estimating natural and/or anthropogenic sources through diagnostic reasons. Aliphatic hydrocarbons were obtained through ultrasound-assisted extraction, followed by a clean up step and quantified by gas chromatography coupled to a flame ionization detector (GC-FID). The sum of the concentrations of n-alkanes and isoprenoids in the range from n-C9 to n-C34 was 0.468 and 2.547 μg.g-1 for sediment samples and 16.657 μg.g-1 for oil samples. For source estimation, the diagnostic ratios Pri/Fit, Pri/n-17, Fit/n-C18, IPC and RTA were used. The carbon preference index (CPI) indicated biogenic and petrogenic contribution in the sediment samples. The Pri/Fit, Pri/n-17 and Fit/n-C18 ratios pointed to levels of degradation of both sediment and oil samples. Furthermore, the oil presented an unresolved complex mixture (UCM), indicating the occurrence of weathering processes. The results indicate a chromatographic similarity profile between the sediment samples. The analyzed oil was compared with samples analyzed in 2019, showing a similar chromatographic profile.