The study of oxygenated compounds for oil fingerprinting application

Abstract

Oil spills have a large impact on the marine and coastal environments. The characterization of petroleum or its products spilled in the environment to its source rocks is an important tool to assist in the resolution of issues of environmental impact and legal responsibility. The composition and physical properties of spilled oils have changed during the weathering process. Petroleum biomarkers is a tool for defining the origin of each oil, which is unique for each type of oil. In general, petroleum biomarkers (i.e., hopane group) are widely used for oil fingerprinting by following the NORDTEST methodology. Besides the hopane group, heteroatomcontaining (N, S, and O) components can be considered for oil fingerprinting applications to provide supporting information in order to find oil spill origin. Oxygenated compounds in crude oil are up to 2% by weight. They are in various forms; alcohol, phenol, ether, carboxylic acid, and ketones. Carboxylic acidcontaining compounds, naphthenic acids, are responsible for crude oil acidity and stay long in the aquatic environment. In this study, oxygenated compounds distribution is studied to provide supporting information to identify the oil spill origin using GC-TOFMS. However, the concentration of the oxygenated compound decreased significantly after 60 days of weathering due to biodegradation, photooxidation, evaporation, and dissolution. This study proposes the ratio of acyclic aliphatic and cyclic naphthenic acid to differentiate crude oil and fuel oil. The acyclic to cyclic (A/C) ratios of weathered crude oil samples are range from 0.67 to 2.59. In contrast, the A/C ratio of weathered fuel oil is less than 0.65. Although, biomarker analysis and correlation plots are still required to confirm the source of the oil samples.