Oxygenated weathering products of Deepwater Horizon oil come from surprising precursors

Biodegradation of crude oil and dispersants in deep seawater from the Gulf of Mexico: Insights from ultra-high resolution mass spectrometry

“…i The relative decrease of the molecular size of compounds with advancing degradation is consistent with earlier reports about oildegradation (Lemkau et al, 2014). However, previous studies of oil-weathering reported a relative increase of oxygenated organic compounds (Aeppli et al, 2012;Hall et al, 2013;Lemkau et al, 2014), whereas we observed only small changes in O/C ratios of DOM (Table 1). A reason for this difference may be that the previous studies reported the weathering of solid oil residues that were exposed to combined photo-and biodegradation, whereas the incubations of the present study involved biodegradation in the absence of light.…”

Sunlight creates oxygenated species in water-soluble fractions of Deepwater horizon oil

“…Dark compounds correspond to O/C ratios < 0.2 and H/C ratio > 1 (higher degree of saturation), while irradiated compounds convert to higher O/C and lower H/C ratio (more aromatic). Oxidation occurred over a wide range of saturation and O/C ratio, and irradiation increased the O/C ratio to create highly oxygenated compounds, in agreement with previous reports [10].…”

“…Advanced analytical techniques for the characterization of polar and nonvolatile compounds can identify photochemical transformations that occur to petrogenic molecules at the molecular level. Comprehensive two dimensional gas chromatography (GC × GC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) have recently been applied to study oil spills [9,10]. Here, we combined FT-ICR MS with electrospray ionization (ESI) to target polar chemical functionalities and catalog molecular changes through photochemical transformation.…”

“…Since the spill, numerous studies have addressed the fate of the Macondo oil [1,[12][13][14][15][16][17][18] and origin and characterization of oxygenated species as a result of weathering [10,[19][20][21]. However, these studies provided a limited ability to differentiate between biodegradation and photodegradation.…”

Solvent effects in the extraction and detection of polycyclic aromatic hydrocarbons from complex oils in complex environments

“…These toxicants include n-alkanes, isoprenoids, and polycyclic aromatic hydrocarbons (PAHs) [2], as well as a variety of polar metabolites of these non-polar compounds, formed via facile oxidation of the original pollutants in the affected environments [3,4].…”