Investigation of crude oil degradation using metal oxide anode-based microbial fuel cell

Oil industries generate large amount of oil wastewater worldwide and it is challenging to develop a sustainable technique to treat them due to the potential risk of contamination and recalcitrance. In this study, we employed microbial fuel cell to investigate biodegradation of crude oil with concomitant power generation. MnO2 coated anode was used to facilitate anoxic oil degradation due to better biofilm attachment, and fuel cell performance was compared with the uncoated carbon anode. Our study revealed that MFC with coated anode produced comparatively higher power density (47 mW m−2) than uncoated carbon anode (38 mW m−2), suggesting better removal of hydrocarbon components, also confirmed by oil-biodegradation studies (36% compared to 25.5% removal of total alkanes). The performance of the two cells was additionally evaluated by electrochemical, morphological, elemental and microbial community analysis. The prevalence of communities associated with hydrocarbon degradation and electrogenesis signify crude oil degradation with power generation.</p

Composition of the Dissolved Organic Matter Produced during In Situ Burning of Spilled Oil

In situ burning is often used as a response method for oil slicks in the marine environment. This process however forms viscous tar-like residues that either float on the surface or sink through the water column, introducing organic species into the water phase. The interaction of this burn residue with the water phase also introduces dissolved organics into the water column. In this study, we conducted laboratory-scale experiments to characterize and compare the organic species entering the water phase from the petrogenic (fresh oil) and pyrogenic (burnt oil) input during oil spills. The oil and water-soluble organics were characterized using ultra-high-resolution mass spectrometry (FTICR-MS). The results show that burning strongly increases concentrations of oil-related constituents entering the water phase, due to transformation reactions producing oxidized organic species with higher water solubility. The pyrogenic water-soluble organics also showed a higher percentage of unsaturated compounds relative to the petrogenic fraction. The effect of these highly unsaturated and oxygenated organic species on oil spill fate and their ecosystem impacts is currently unknown

Rapid Screening of Glycerol Ether Lipid Biomarkers in Recent Marine Sediment Using Atmospheric Pressure Photoionization in Positive Mode Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Many of the molecular proxies commonly used for paleoenvironmental reconstruction are focused on a limited set of glycerol ether lipids, mainly due to the lack of more comprehensive analytical methods and instrumentation able to deal with a more diverse range of species. In this study, we describe an FTICR-MS-based method for rapid, nontargeted screening of ether lipid biomarkers in recent marine sediments. This method involves simplified sample preparation and enables rapid identification of known and novel ether lipid species. Using this method, we were able to identify complete series of core glycerol dialkyl glycerol tetraethers (GDGTs with 0 to 8 alicyclic rings), including the complete resolution of GDGT-4 and the unexpected detection of GDGTs with more than 5 rings, in sediments from mesophilic marine environments (sea surface temperature, SST, of 24-25 °C). Additionally, mono- and dihydroxy-GDGT analogs (including novel species with \u3e 2 rings), as well as glycerol dialkanol diethers, GDDs (including novel species with \u3e 5 rings) were detected. Finally, we putatively identified other, previously unreported groups of glycerol ether lipid species. Adequacy of the APPI-P FTICR-MS data for the determination of commonly used GDGT-based proxy indices was demonstrated. The results of this study show great potential for the use of FTICR-MS as both a rapid method for determining existing proxy indices and, perhaps more importantly, as a tool for the early detection of possible new biomarkers and proxies that may establish novel geochemical relationships between archaeal ether lipids and key environmental-, energy-, and climate-related system variables

Machine Learning in Complex Organic Mixtures: Applying Domain Knowledge Allows for Meaningful Performance with Small Datasets.

The ability to quantify individual components of complex mixtures is a challenge found throughout the life and physical sciences. An improved capacity to generate large datasets along with the uptake of machine-learning (ML) based analysis tools has allowed for various ‘omics’ disciplines to realize exceptional advances. Other areas of chemistry that deal with complex mixtures often cannot leverage these advances. Environmental samples, for example, can be more difficult to access and the resulting small datasets are less appropriate for unconstrained ML approaches. Herein, we present an approach to address this latter issue. Using a very small environmental dataset—35 high-resolution mass spectra gathered from various solvent extractions of Canadian petroleum fractions—we show that the application of specific domain knowledge can lead to ML models with notable performance

Experimental Simulation of Crude Oil-Water Partitioning Behavior of BTEX Compounds during a Deep Submarine Oil Spill

The conventional shake flask technique for determining oil-water partition ratios of benzene, toluene, ethylbenzene and xylene (BTEX) cannot accurately assess the extremes of high pressure and low water temperatures found in submarine oil spill conditions. An oil-water partitioning device has been constructed to experimentally simulate the partition behavior of BTEX compounds under submarine oil spill conditions, using simulated live oil (methane-charged), with saline waters over a range of pressure (2–15 MPa) and temperature (4–20 °C). Within the investigated ranges, the partition ratios of BTEX compounds increase proportionally with an increase in methane charging pressure (oil saturation pressure) and the degree of BTEX alkylation, and decrease with increase in temperature. The variation of the partition ratio values due to changes in system pressure and increasing oil methane concentration, is much more significant than those seen due to change in the temperature over the range studied. This data may be used in near-field and far-field distribution modeling of the environmental fate of highly toxic BTEX compounds, derived from submarine oil spills and their impact on the ecosystem. The parameters will also aid in the prediction of oil migration and dispersion away from the spill thus helping to improve response strategies

Resolution and Quantification of Complex Mixtures of Polycyclic Aromatic Hydrocarbons in Heavy Fuel Oil Sample by Means of GC × GC-TOFMS Combined to Multivariate Curve Resolution

Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) combined to multivariate curve resolution-alternating least-squares (MCR-ALS) is proposed for the resolution and quantification of very complex mixtures of compounds such as polycyclic aromatic hydrocarbons (PAHs) in heavy fuel oil (HFO). Different GC × GC-TOFMS data slices acquired during the analysis of HFO samples and PAH standards were simultaneously analyzed using the MCR-ALS method to resolve the pure component elution profiles in the two chromatographic dimensions as well as their pure mass spectra. Outstandingly, retention time shifts within and between GC × GC runs were not affecting the results obtained using the proposed strategy and proper resolution of strongly coeluted compounds, baseline and background contributions was achieved. Calibration curves built up with standard samples of PAHs allowed the quantification of ten of them in HFO aromatic fractions. Relative errors in their estimated concentrations were in all cases below 6%. The obtained results were compared to those obtained by commercial software provided with GC × GC-TOFMS instruments and to Parallel Factor Analysis (PARAFAC). Inspection of these results showed improvement in terms of data fitting, elution process description, concentration relative errors and relative standard deviations.Financial support was obtained from MCINN (Projects ref. . CTQ2009-11572, CTM2008-02718-E, RAMOCS, and CTM2008-02721-E/MAR, TOXPROF) and the project “European concerted action to foster prevention and best response to accidental marine pollution-AMPERA” (ERAC-CT2005-016165) within the framework of the EU ERA-Net Initiative (sixth Framework Program). J.R.R. kindly acknowledges a predoctoral fellowship (JAE Predoc) from the Spanish National Council of Research (CSIC).Peer reviewe

Chemical Composition of Macondo and Other Crude Oils and Compositional Alterations During Oil Spills

Crude oils are some of the most complex and diverse organic mixtures found in nature. They contain thousands of different compounds belonging to several compound classes, with the main ones being hydrocarbons and their heteroatom (N, S, and O)-containing analogs, called non-hydrocarbons. In general, all crude oils contain the same types of chemical structures, but these compounds can be in highly variable proportions in crude oils drawn from different reservoir conditions and locations. Both the types of compounds and their respective quantities change rapidly once the crude oil is spilled into the environment, making the circumstances associated with every spill unique. In general, smaller and lower molecular weight oil compounds are more susceptible to processes such as evaporation, dissolution, and biodegradation, while the heavier, more hydrophobic compounds tend to adhere to living organisms or particulates and persist. The presence of certain compounds, such as PAHs (polycyclic aromatic hydrocarbons), also determines the acute and chronic toxicity of the spilled oil. Natural processes can degrade virtually all compounds in crude oils, with aerobic oxidation proceeding much faster than anaerobic degradation, although not all crude oil components are degraded with the same speed. The environmental fate and effects of crude oil degraded by biodegradation and photooxidation are yet to be fully determined. Due to the submarine and offshore setting of the Macondo well blowout, components of the spilled oil were distributed throughout the marine environment—water column, sediments, surface waters, and the coast. The light and nonviscous nature of Macondo crude oil favored its removal through natural degradation, evaporation, dissolution, and dispersal processes. In spite of the unprecedented quantities of oil that spilled, the final fate and effects of the oil, the more recalcitrant fractions of Macondo oil, and the oil weathering products have not been totally elucidated. Responders with knowledge of the physical properties of the Macondo oil executed their preplanned response efforts and kept a majority of the oil from reaching the more sensitive coastal areas

Chemical Composition of Macondo and Other Crude Oils and Compositional Alterations During Oil Spills

Crude oils are some of the most complex and diverse organic mixtures found in nature. They contain thousands of different compounds belonging to several compound classes, with the main ones being hydrocarbons and their heteroatom (N, S, and O)-containing analogs, called non-hydrocarbons. In general, all crude oils contain the same types of chemical structures, but these compounds can be in highly variable proportions in crude oils drawn from different reservoir conditions and locations. Both the types of compounds and their respective quantities change rapidly once the crude oil is spilled into the environment, making the circumstances associated with every spill unique. In general, smaller and lower molecular weight oil compounds are more susceptible to processes such as evaporation, dissolution, and biodegradation, while the heavier, more hydrophobic compounds tend to adhere to living organisms or particulates and persist. The presence of certain compounds, such as PAHs (polycyclic aromatic hydrocarbons), also determines the acute and chronic toxicity of the spilled oil. Natural processes can degrade virtually all compounds in crude oils, with aerobic oxidation proceeding much faster than anaerobic degradation, although not all crude oil components are degraded with the same speed. The environmental fate and effects of crude oil degraded by biodegradation and photooxidation are yet to be fully determined. Due to the submarine and offshore setting of the Macondo well blowout, components of the spilled oil were distributed throughout the marine environment—water column, sediments, surface waters, and the coast. The light and nonviscous nature of Macondo crude oil favored its removal through natural degradation, evaporation, dissolution, and dispersal processes. In spite of the unprecedented quantities of oil that spilled, the final fate and effects of the oil, the more recalcitrant fractions of Macondo oil, and the oil weathering products have not been totally elucidated. Responders with knowledge of the physical properties of the Macondo oil executed their preplanned response efforts and kept a majority of the oil from reaching the more sensitive coastal areas

Exploring the Complexity of Two Iconic Crude Oil Spills in the Gulf of Mexico (Ixtoc I and Deepwater Horizon) Using Comprehensive Two-Dimensional Gas Chromatography (GC × GC)

Comprehensive two-dimensional gas chromatography (GC × GC) was used to explore and compare the chemical complexity of oil released from the Deepwater Horizon (DWH) disaster in 2010 and the Ixtoc I spill in 1979-1980, both in the Gulf of Mexico (GoM). To provide the most complete inventory of the compounds present in the DWH and Ixtoc I crude oils, we utilized GC × GC systems coupled to a flame ionization detector and a high-resolution time-of-flight mass spectrometric detector. The results of this study demonstrate the significance of valuable environmental forensics information obtained using GC × GC fingerprinting methods. In particular, the high-resolution mass spectrometer enabled an in-depth characterization of the types and families of GC-amenable compounds present in these crude oils including the detection of highly alkylated sulfur-containing species, alkylated carbazoles and benzocarbazoles, and a suite of unusual de-A-sterane biomarkers in the Ixtoc I oil. This type of specificity is essential for differentiating spill sources of similar origin/type, for example, within northern and southern GoM petroleum families and of the molecular transformations that occur during oil-spill weathering processes