Abstract

TOMAS, Germán Javier  and  ACUNA, Adrián Javier. Study of petroleum biomarkers from the weathering of a crude oil in seawater. Rev. Int. Contam. Ambient [online]. 2023, vol.39, 54799.  Epub June 05, 2023. ISSN 0188-4999.  https://doi.org/10.20937/rica.54799.

When an oil spill occurs in aquatic systems, different weathering processes take place on this resource that modify its composition. As a result, it is difficult to assign responsibility for pollution caused by this resource. However, in crude oil there are molecules known as biomarkers with the potential to resist weathering processes depending on the exposure time, alteration kinetics and alteration phenomena that this resource undergoes when exposed to the environment. In the present work, the stability of biomarkers was analyzed for a crude oil spilled in seawater under laboratory conditions for a period of one year, with the objective of testing their usefulness in litigation related to oil spills and/or oil theft. To this end, biomarker profiles were analyzed by gas chromatography coupled to mass spectrometry from the crude fractions. Specific parameters such as Pr/n-C17 (pristane/heptadecane), 4-MeDBT/1-MeDBT (methyldibenzothiofene) y stigmastane C29 αS/hopane C30 known as diagnostic ratios changed around values less than 5 % with respect to their relative standard deviation over the course of one year. Notably, the Pr/Ph ratios, (n-C13 + n-C14)/(n-C25 + n-C26) and (N0 + N1)/N2 (N = naphthalenes) were the only ones with percentages above 5 % and these results were associated with an evaporation process on the crude oil. On the other hand, the analysis of the chromatograms obtained indicated that biodegradation was also involved in the weathering of hydrocarbons. However, most of the biomarkers remained unaltered under the test conditions throughout the study time, which demonstrates their potential to solve the problems mentioned above.

Keywords : pristane; phytane; terpanes; steranes.