Evaluation of the diagnostic ratios for the identification of spilled oils after biodegradation

Abstract

Biodegradation, one of the most important weathering processes, alters the composition of spilled oil, making it difficult to identify the source of the release and to monitor its fate in the environment. A laboratory experiment was conducted to simulate oil spill weathering process of microbial degradation to investigate compositional changes in a range of source-and weatheringdependent molecular parameters in oil residues, and the conventional diagnostic ratios for oil spill identification were also evaluated. The conventional diagnostic ratios of n-alkane displayed obvious changes after biodegradation, especially for Pr/n-C 17 and Ph/n-C 18 with relative standard deviation more than 118.84 %, which suggests they are invalid for oil source identification of the middle-serious spill. Many polycyclic aromatic hydrocarbons (PAHs) are more resistant to biodegradation process than their saturated hydrocarbon counterparts, thus making PAHs to be one of the most valuable fingerprinting classes of hydrocarbons for oil identification. Biomarker ratios of hopanes and steranes were also useful for source identification even after moderate biodegradation, and the diagnostic ratios from them could be used in tracking origin and sources of hydrocarbon pollution. Finally, the carbon isotopic type curve may provide another diagnostic means for correlation and differentiation of spilled oils, and be particularly valuable for lighter refined products or severely biodegraded oils, the source of which may be difficult to identify by routine biomarker techniques.

The culturable mycobiota of a Mediterranean marine site after an oil spill: isolation, identification and potential application in bioremediation

“…Nevertheless some factors could affect their efficiency as nutrient scarcity (i.e. C:N:P ratio) (Crisafi et al, 2016;Hassanshahian and Cappello 2013;Jimenez et al, 2007) and crude oil composition, being saturated hydrocarbons most biodegraded than aromatic ones (Wang et al, 2013).…”

Study on weathering characteristic of aromatic hydrocarbons specific to unconditional oil based on concentration-resolved-fluorescence spectroscopy

“…溢油泄漏到环境中, 随即发生扩散、挥发、油水 乳化、溶解、光化学氧化、微生物降解 [23,24] 等多种风 化过程, 特别是重度风化过程, 会强烈改变溢油的化学 组成和物理性质, 导致油样固有的特征信息受到不同 程度的干扰和破坏, 给溢油鉴别造成了诸多困难 [25,26] .…”

Study of weathering effects on the distribution of aromatic steroid hydrocarbons in crude oils and oil residues

“…21,22 The oil and residue were liquid-liquid extracted three times with 50 mL of dichloromethane in a separatory funnel. Aer drying with anhydrous sodium sulfate, the organic extracts were concentrated by rotary evaporation, and the solvent was exchanged to 1 mL of hexane.…”

“…The procedure used here has been described elsewhere. 21 Briey, the oileld water from Shengli oileld was added in enrichment medium, and the enrichment medium was put in the incubator at 50 C for 30 min. To mimic the natural living conditions of bacteria, aerobic bacteria and a low inorganic salt concentration of aqueous medium were chosen in this study.…”