Investigação das modificações químicas de biomarcadores de petróleo submetidos a derrames simulados em ambientes aquáticos

Abstract

The oil industry characterizes a source of risks to the environment. Studies that aim to understand the chemical modification in oil spill situations are gaining greater attention due to recurrent environmental disasters, such as the one that occurred on the coast of Brazil in 2019. The purpose of this study was to apply a laboratory simulation of oil spills in aquatic environments, to evaluate the chemical changes in composition of oils using the technique of gas chromatography coupled to mass spectrometry (GC/MS) and infrared spectroscopy (IR). For the simulations, a homemade system was used that were a chamber with white, blue and ultraviolet lamps, referring to wavelengths like those emitted by solar radiation, where inside was allocated a mixture of oil and seawater 1:80 (m/v), and the oil spill simulation was performed to obtain aliquots of oil at different times of exposure. The oil aliquots were analyzed by GC/MS, in order to obtain a comparative analysis of the initial crude oil (control) and the same oil after the spill exposures, which was possible to evaluate the chemical changes of oil biomarkers and their diagnostic reasons. The chromatograms showed a decrease in the peak areas of the n-alkanes with lower molecular weight in the first hours of exposure to the simulated spill, however, no significant changes were observed in the diagnostic ratios for biomarkers of the sterane and terpane classes, showing that they are classes that do not change chemically. The IR was performed in the spectral range of 600-4000 cm-1, using attenuated total reflectance (ATR). The IR data showed peaks related to the majority chemical composition of crude oils, referring to aliphatic hydrocarbon compounds. It was also possible to identify peaks related to the appearance of new stretching linked to chemical changes associated with the photo-oxidation process that occurred in the spill simulation, referring to peaks for oxygenated compounds, in the region of 1233 cm-1. Thus, the study was able to identify some changes in the chemical composition of crude oils after simulated spills in aquatic environments, as well as to show that the consolidated diagnostic ratios involving terpanes and steranes do not change, and in both cases can be used in studies to track oil spills in environments and/or as data for remediation of environments impacted by spills involving the oil industry.