Banca de QUALIFICAÇÃO: MARILIA GABRIELA ARAÚJO PEREIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARILIA GABRIELA ARAÚJO PEREIRA
DATE: 27/02/2025
TIME: 14:00
LOCAL: Auditório do Depto. de Química
TITLE:

APPLICATION OF HIGH-RESOLUTION ANALYTICAL TECHNIQUES FOR ADVANCED CHEMICAL CHARACTERIZATION OF OIL SPILL SAMPLES

KEY WORDS:

Petroleomics; Oil Spill; Spill Simulation; Diagnostic Ratio; Biomarkers.

PAGES: 76
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Análise de Traços e Química Ambiental
SUMMARY:

The studies conducted in this doctoral thesis are focused on the field of environmental forensic geochemistry applied to oil spills, a branch of science that investigates oil spills at the molecular level by employing sampling protocols, sample preparation, and analytical techniques to identify sources and understand the weathering processes of petroleum organic compounds in terrestrial and/or aquatic environments. The first chapter aims to perform a geochemical comparison between the oil from the mysterious 2019 spill, which occurred along the northeastern coast of Brazil, and samples from another spill event in 2022 to determine whether there is a geochemical correlation. To achieve this, GC-MS was applied for the analysis of classical apolar biomarkers, while FT-MS was employed to characterize the polar composition of the spilled oil samples. GC-MS analysis revealed a bimodal distribution of linear n-alkanes in the 2022 samples, with a high abundance of high-molecular-weight compounds. In contrast, n-alkanes were absent in the 2019 samples, indicating intense biodegradation. FT-MS analysis showed that the distribution of polar compounds differed between the two events, with the most abundant ions centered in the lower molecular mass range (300–500 Da) for the 2022 samples, compared to a higher mass range (400–700 Da) for the 2019 oil. These findings indicate that the oil residues from the 2022 spill event correspond to virgin/unprocessed oil, whereas the 2019 spill involved processed/refined oil. The second chapter, which is still in progress, aims to investigate the temporal evolution of oil spills in marine environments through a laboratory-scale simulation using real samples from the 2019 event. The study evaluates chemical modifications over different time intervals (0 h, 1 h, 6 h, 24 h, 120 h, and 120 h control). Preliminary results obtained via GC-MS have demonstrated that biodegradation and photooxidation processes persist throughout the entire simulation period, leading to the formation of unresolved complex mixtures (UCM) and a reduction in the areas of linear n-alkanes, while maintaining the chromatographic profiles of sterane and terpane biomarker classes. The findings obtained thus far reinforce the significance of environmental forensic geochemistry in the study of oil spills, providing effective tools and approaches for distinguishing between different spill events and assessing the chemical weathering processes affecting spilled oil.

COMMITTEE MEMBERS:
Presidente - JANDYSON MACHADO SANTOS
Interno - RAMOM RACHIDE NUNES
Externo à Instituição - LAERCIO LOPES MARTINS
Externa à Instituição - SAMIA TÁSSIA ANDRADE MACIEL