Molecular behavior assessment on initial stages of oil spill in terrestrial environments

The contamination of terrestrial environments by oil spills creates biological risks to humans and affects the ecosystem's health. The studies that aim to evaluate the toxicity and changes in the environments are a field of potential interest to the scientific community. The objective of this study was to evaluate the changes in the chemical composition of crude oil fractions after the simulation of a spill in soil and sand, with emphasis on an immediate temporal investigation. Samples of intermediate (°API = 27.0) and heavy (°API = 20.9) oils from Sergipe-Alagoas basin were used. The evaporation process in the soil was highlighted; while the GC-FID chromatographic profiles demonstrated (1) the disappearance from n-C₁₂ until n-C₁₄ compounds, besides a decrease of more than 50% in n-C₁₅ and n-C₁₆ n-alkanes and (2) no changes in n-C₁₇/Pr and n-C₁₈/Ph ratios for both oils. Analysis of resins fraction performed by Orbitrap-MS has shown changes in the mass spectra profile and compound distribution during the soil and sand exposure process, with N₁, O₁, and O₂ species showing changes in the relative abundance in ESI(+) mode, and O₂, N₁, and O₁ for ESI(-). Changes in polar compounds of oil will depend on the extent of the time of interaction with soil and sand, taking into account intrinsic aspects, such as the nature of the soil and components in it as the organic matter.