Weathered Crude Oil Research Articles

Differentiation of weathered chemically dispersed oil from weathered crude oil.

Oil fingerprinting is a crucial technology to trace the sources and behaviors of spilled oil. The use of dispersants enhances the stay of dispersed oil in a water column and changes the important properties of spilled oil. In case of fingerprinting of dispersed oil driven by dispersants, the fate and behaviors of biomarkers may be affected by the application of dispersants. Limited studies have investigated the statistical difference between fingerprinting of dispersed oil and non-dispersed oil using biomarkers, and the possible influence of the differences, if present. This study applied several principal component analyses (PCA) to differentiate weathered chemically dispersed oil from weathered crude (non-dispersed) oil using 103 diagnostic ratios of the same type of biomarkers and those of two types of biomarkers as input data. It showed that weathered chemically dispersed oil (CDO) can be differentiated from weathered crude oil (WCO) using specific diagnostic ratios that are affected by weathering. PCA analyses indicated the effects of the application of dispersants and weathering duration on weathering of biomarkers in CDO and WCO.

Polar Solvent-Induced Unprecedented Supergelation of (Un)Weathered Crude Oils at Room Temperature.

Use of carrier solvents to assist dissolution of phase-selective organogelators (PSOGs) before application in oil gelation is a common approach for solution-based gelators. Because of the competition in H-bonds by the polar carrier solvent, decreased gelling ability of PSOGs was often observed. That is, while data are available, the previously documented biphasic minimum gelling concentrations (BMGCs) are much larger than the MGCs determined using heating-cooling cycle for the same PSOG against the same oil. In this study, we show that, by minimizing amount of polar carrier solvent used, the gelling ability of PSOGs actually can be enhanced very substantially, rather than being weakened. More specifically, we demonstrate that use of a minute amount of polar carrier solvents of different types (e.g., ethyl acetate, acetone, acetonitrile, and tetrahydrofuran) significantly enhances the gelling ability of seven structurally different organogelators in hydrophobic oil. In particular, with the use of 5 vol % essentially nontoxic ethyl acetate, application of this previously unexplored strategy onto four monopeptide-based PSOGs produces up to 11-fold improvement in biphasic gelling ability toward seven (un)weathered crude oils of widely ranging viscosities. While collectively overcoming many problematic issues (slow gelling action, low gelling ability, or a need to use hot or toxic solvent for dissolution of gelator) associated with PSOGs, this surprisingly simple yet powerful and reliable method produces unprecedented rapid supergelation of crude oil at room temperature, with BMGCs of as low as 0.38 w/v % (e.g., 3.8 g per liter of crude oil) and an averaged reduction in material cost of gelators by 85-97%.

Evaluation of the effects of inorganic and organic fertilizers and activated carbon on bioremediation of soil contaminated with weathered crude oil

The objective of this study was designed to evaluate the effects of nutrients (inorganic NPK fertilizer and organic fertilizer) and adsorptive amendment agents (activated carbon) as well as their interactions on bioremediation of soil contaminated with Weathered Crude Oil (WECO). The organic fertilizer was made up of cattle dungs, pig dungs and poultry droppings mixtures. Box Behnken Design (BBD) of Response Surface Methodology (RSM) with three levels and three factors was used having inorganic NPK fertilizer (3 - 5 g), activated carbon (20 - 40g) and organic fertilizer (30 - 50 g) as independent variables and percentage WECO degradation as dependent variable (response) in a four weeks remediation period. Results of the study showed that WECO removal rate in soil is invariably dependent on the amount of nutrient and adsorptive agents. The optimum amount of nutrient and adsorptive amendment agents obtained to achieve a predicted maximum WECO removal of 66.24% are: inorganic NPK fertilizer, 4.19 g; activated carbon, 35.42 g and organic fertilizer, 48.94 g. At this predicted optimum amount, validation experiment revealed that 65.55% of WECO removal was achieved. Statistical analyses revealed the closeness of the experimental results to model predictions which thus show the reliability of the quadratic regression model. Therefore, organic and inorganic nutrients as well as adsorptive amendment alone and/or in combination enhances soil indigenous microbial density and activity which thereby accentuates petroleum hydrocarbons biodegradation and subsequently reduces the period of bioremediation and remediation cost. Keywords: Activated carbon; Box-Behnken design; Crude oil; Nutrients; Regression model

Photoenhanced Toxicity of Weathered Crude Oil in Sediment and Water to Larval Zebrafish.

Solar radiation exposure can increase the toxicity of bioaccumulated oil compounds in a diversity of aquatic species. We investigated the photoenhanced toxicity of weathered South Louisiana crude oil in sediment and water accommodated fractions (WAF) to larval zebrafish. Larvae were first exposed for 24h to one of six treatments: no oil (sediment or water), 7.5g oil/kg sediment, oil-only WAF, oil WAF plus the dispersant Corexit 9500A, or dispersant alone. Larvae were then exposed to high or low levels of sunlight in control water for 3 or 3.5h. Hydrocarbon concentrations were measured in exposure media, including alkanes, polycyclic aromatic compounds and total petroleum hydrocarbons. Significant phototoxicity was observed in larvae exposed to oiled sediment, oil-only WAF, and oil plus dispersant WAF. The results indicated that petroleum from the northern Gulf of Mexico can be phototoxic to larval fish exposed to oil in either the water column or sediment.

Sensitivity and Identification Indexes for Fuel Oils and Crude Oils Based on the Hydrocarbon Components and Diagnostic Ratios Using Principal Component Analysis (PCA) Biplots

In total, 164 oil samples, including 56 crude oils (OILs), 12 light fuel oils (LFOs), 66 heavy fuel oils (HFOs), 12 weathered fuel oils (WHFOs), and 18 weathered crude oil (WOILs) samples, were used to screen the sensitivity and identification indexes using principal component analysis (PCA) biplots. Also, 31 oil samples, including 1 LFO, 15 HFOs and 15 OILs, were used for validation by PCA biplots. The sensitivity indexes were determined from PCA biplots based on 143 components; light n-alkanes exhibited good positive correlation with LFOs, aromatic hydrocarbons displayed positive correlations with HFOs, and terpanes and steranes were indicative of OIL characteristics. Among 43 diagnostic ratios, the sensitive diagnostic ratios were screened for LFOs, HFOs, and OILs, using PCA biplots. Thirty-eight (38) diagnostic ratios that could discriminate three types of oils were chosen: 21 diagnostic ratios were chosen for the classification of OILs and HFOs, 19 diagnostic ratios could identify OILs and fuel oils (FOs) (including LFOs and HFOs), and 6 diagnostic ratios could discriminate between LFOs and the other two types of oils (OILs and HFOs). In addition, all of the ratios could resist weathering, which means that all of the results included weathered oil samples. All of the identification indexes, including 143 hydrocarbon components, and 43, 38, 21, 19, and 6 diagnostic ratios, were validated by PCA biplots based on 31 oil samples.

Characterization of Highly Oxygenated and Environmentally Weathered Crude Oils by Liquid Chromatography Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS)

Heavy and biodegraded oils exhibit an ever increasing oxygen complexity. Electrospray ionization (ESI) coupled to FT-ICR MS highlights the most acidic and basic oxygen species; however, quantitative and qualitative information about less polar oxygenated compounds is essential to understand both the source and, potentially, the modification pathways for oxygenated crude oils. Liquid chromatography (LC) is complementary to FT-ICR MS to deconvolve crude oils according to oxygen functionality, thereby enriching oxygen species that are not easily ionized or are present in low abundance. Ketones and carboxylic acids dominate most environmentally modified crude oils; however, phenols and polyphenols are also important intermediates in both biotic and abiotic modifications. Moreover, due to the nature of the refinement process, oxygen-containing species and their intermediates can serve as chemical tracers in produced water streams and areas of rapid thermal changes that lead to gum or deposit formation. Here, we describe an analytical separation scheme for an environmentally weathered (highly oxygenated) crude oil designed to highlight carboxylic acid isolation and ketone enrichment, as well as the separation of other oxygen compounds by polarity. Experimental A weathered beach extract collected from the coast of Florida was fractionated by LC and analyzed by FT-ICR MS. LC techniques are designed to target specific oxygen functionalities (e.g., ketones, alcohols, phenols, and carboxylic acids). The mass spectra of the LC fractions were acquired with a custom-built 9.4 T FT-ICR Instrument. Positive and negative electrospray ionization serve to highlight basic and acidic oxygen species. Preliminary DataLC fractionation was performed with a silicic acid stationary phase. Four fractions correspond to aromatics, neutral nitrogen, basic nitrogen, and polar compounds. Positive ESI FT-ICR MS indicated a relative abundance for the O1 heteroatom class ranging from 2% in the whole beach extract to 12 % in the neutral nitrogen fraction. The increased relative abundance of O1 compounds suggests the enrichment of ketones from the original sample. Carboxylic acids are isolated by retention on an amine stationary phase and subsequent elution with a mixture of dichloromethane, methanol, and formic acid. Oxygen species will be further probed with new separation schemes to focus on analysis of phenols.

Tropical Endogeic Earthworm Population in a Pollution Gradient with Weathered Crude Oil

Tropical Endogeic Earthworm Population in a Pollution Gradient with Weathered Crude Oil

The Importance of Weathered Crude Oil as a Source of Hydrocarbonoclastic Microorganisms in Contaminated Seawater

This study investigated the hydrocarbonoclastic microbial community present on weathered crude oil and their ability to degrade weathered oil in seawater obtained from the Gulf St. Vincent (SA, Australia). Examination of the native seawater communities capable of utilizing hydrocarbon as the sole carbon source identified a maximum recovery of just 6.6 × 10(1) CFU/ml, with these values dramatically increased in the weathered oil, reaching 4.1 × 10(4) CFU/ml. The weathered oil (dominated by >C30 fractions; 750,000 +/- 150,000 mg/l) was subject to an 8 week laboratory-based degradation microcosm study. By day 56, the natural inoculums degraded the soluble hydrocarbons (initial concentrations 3,400 +/- 700 mg/l and 1,700 +/- 340 mg/l for the control and seawater, respectively) to below detectable levels, and biodegradation of the residual oil reached 62% (254,000 +/- 40,000 mg/l) and 66% (285,000 +/- 45,000 mg/l) in the control and seawater sources, respectively. In addition, the residual oil gas chromatogram profiles changed with the presence of short and intermediate hydrocarbon chains. 16S rDNA DGGE sequence analysis revealed species affiliated with the genera Roseobacter, Alteromonas, Yeosuana aromativorans, and Pseudomonas, renowned oil-degrading organisms previously thought to be associated with the environment where the oil contaminated rather than also being present in the contaminating oil. This study highlights the importance of microbiological techniques for isolation and characterisation, coupled with molecular techniques for identification, in understanding the role and function of native oil communities.

Mineralisation of Weathered Crude Oil by a Hydrocarbonoclastic Consortia in Marine Mesocosms

Marine waters are most vulnerable to crude oil pollution due to increased sea-based oil-related activities. Successful remediation of such polluted environments is normally carried out in a laboratory with suitable physical and environmental alterations. However, it is challenging to alter the physical and environmental conditions in crude oil-contaminated natural environments. In a previous study, six hydrocarbonoclastic bacteria were isolated from an oil-contaminated site. Here we report on their ability to mineralise weathered crude oil as a carbon source in seawater mesocosms, in order to construct a hydrocarbonoclastic consortia for the effective mineralisation of hydrocarbons present in the weathered crude oil at seawater-based environment. This was completed without altering the physical and environmental parameters (salinity, pH and temperature) and followed by the detection of microbial community changes. The total amount of oil mineralised by these six isolates individually over 28-day incubation ranged from 4.7 to 10 %. The bacterial consortia composed of these six strains showed a greater mineralisation rate (18.5 %). Temperature gradient gel electrophoresis revealed that the functionally dominant species were present after the first week (week 2 to week 4) following the addition of the consortia, which were represented in dendrogram by cluster 2 and also these weeks representing a distinct point on the Pareto–Lorenz curve; no community could be identified in controls in which no consortia were added. This shows that the addition of consortia potentially dealt with changing environmental conditions and preserved its functionality followed by effective mineralisation of weathered crude oil.

Ex-situ Bioremediation of Crude Oil in Soil, a Comparative Kinetic Analysis

Weathered crude oil (WCO) removals in shoreline sediment samples were monitored for 60 days in bioremediation experimentation. Experimental modeling was carried out using statistical design of experiments. At optimum conditions maximum of 83.13, 78.06 and 69.92% WCO removals were observed for 2, 16 and 30 g/kg initial oil concentrations, respectively. Significant variations in the crude oil degradation pattern were observed with respect to oil, nutrient and microorganism contents. Crude oil bioremediation were successfully described by a first-order kinetic model. The study indicated that the rate of hydrocarbon biodegradation increased with decrease of crude oil concentrations.

A statistical experiment design approach for optimizing biodegradation of weathered crude oil in coastal sediments

This work studied the bioremediation of weathered crude oil (WCO) in coastal sediment samples using central composite face centered design (CCFD) under response surface methodology (RSM). Initial oil concentration, biomass, nitrogen and phosphorus concentrations were used as independent variables (factors) and oil removal as dependent variable (response) in a 60 days trial. A statistically significant model for WCO removal was obtained. The coefficient of determination ( R 2 = 0.9732) and probability value ( P < 0.0001) demonstrated significance for the regression model. Numerical optimization based on desirability function were carried out for initial oil concentration of 2, 16 and 30 g per kg sediment and 83.13, 78.06 and 69.92 per cent removal were observed respectively, compare to 77.13, 74.17 and 69.87 per cent removal for un-optimized results.

Aryl Hydrocarbon Receptor–Independent Toxicity of Weathered Crude Oil during Fish Development

Polycyclic aromatic hydrocarbons (PAHs), derived largely from fossil fuels and their combustion, are pervasive contaminants in rivers, lakes, and nearshore marine habitats. Studies after the Exxon Valdez oil spill demonstrated that fish embryos exposed to low levels of PAHs in weathered crude oil develop a syndrome of edema and craniofacial and body axis defects. Although mechanisms leading to these defects are poorly understood, it is widely held that PAH toxicity is linked to aryl hydrocarbon receptor (AhR) binding and cytochrome P450 1A (CYP1A) induction. Using zebrafish embryos, we show that the weathered crude oil syndrome is distinct from the well-characterized AhR-dependent effects of dioxin toxicity. Blockade of AhR pathway components with antisense morpholino oligonucleotides demonstrated that the key developmental defects induced by weathered crude oil exposure are mediated by low-molecular-weight tricyclic PAHs through AhR-independent disruption of cardiovascular function and morphogenesis. These findings have multiple implications for the assessment of PAH impacts on coastal habitats.

Effects of Potassium Permanganate and Hydrogen Peroxide on the Biodegradation of Weathered Crude Oil in Sediments from Indiana Harbor Canal

Effects of Potassium Permanganate and Hydrogen Peroxide on the Biodegradation of Weathered Crude Oil in Sediments from Indiana Harbor Canal

HEAVY METALS AND PETROLEUM HYDROCARBONS CONTAMINATION OF BOTTOM SEDIMENTS OF EL SUKHNA AREA, GULF OF SUEZ, EGYPT

The concentrations of total petroleum hydrocarbons (TPH), total organic carbon (%TOC) and petroleum related heavy metals beside the grain size distribution of El Sukhna area, Egypt were determined in the bottom sediment. Copper, zinc and nickel concentrations were found within the lowest effect, while lead and cadmium levels were close to and high to the lowest effect, respectively. The contaminations level were found due to petrogenic origin and their sources are either weathered or highly weathered crude oils and or used lubricating oil. Their detection gives an indication of recent and continuous petroleum inputs.

Response of river otters to experimental exposure of weathered crude oil: fecal porphyrin profiles.

Profiles of porphyrins were characterized in fecal samples from river otters (Lontra canadensis) experimentally exposed to weathered crude oil to determine effects on heme synthesis. Fifteen male river otters were randomly assigned to three groups of five individuals each representing a control group, a low-dosage group that received 5 mg/kg body mass of oil per day, and a high-dosage group that received 50 mg/kg body mass of oil per day. Mean levels of coproporphyrin III (CoproIII) and protoporphyrin IX (ProtoIX) in fecal samples collected from all experimental river otters were higher throughout the experimental period than levels of CoproIII and ProtoIX in fecal samples collected previously at two field sites. No statistically significant differences in levels of CoproIII and ProtoIX were observed between treatment groups, although a trend of reduction in variability in CoproIII was observed in the low- and high-dose groups. We found no relation between levels of CoproIII and ProtoIX, suggesting that the process of disruption that leads to oxidation of the precursors of porphyrins is probably nonlinear. Our results also indicate that the interaction between oiled induced reduction in hemoglobin levels and induction of CYP1A1 corresponded with significantly lower levels of ProtoIX in the fecal samples, possibly representing high demand for ProtoIX. Therefore, while this experiment does not support the use of porphyrin profiles as an individual biomarker, it does suggest that the latter may be valuable when a weight of evidence is used in an ecotoxicological risk assessment in which the interactions between several biomarkers are explored.

Relationships Between Sediment Morphology and Oil Pollution Along the Suez Canal Beaches, Egypt

In this study, marine surface sediments are collected from nine locations along the Suez Canal in order to investigate the relationship between the morphology of sands in the studied beaches and pollution by oil. Basically, the studied samples were analyzed by three techniques: grain-size analysis, microscopic examination, and gas chromatographic (GC) analysis. This study concluded that “medium sand” is the major class represented in the studied marine sediments. Pollution in these sand grains increases in the irregular grains more so than in the more rounded grains. Also, deep surface points, pitting, and fissures are considered to be good sites to precipitate oil contamination. Also, the presence of iron oxides may be taken as evidence for tanker ballast washings. The heavy fraction (zircon) shows more contamination than the light fraction (quartz) in these samples. Finally, GC profiles have shown two types of samples: one typical of weathered or highly weathered crude oil patterns and the other for sam...

Improvement of the quality of heavily weathered crude oils

Ways to improve the quality of highly weathered crude oils formed as a result of uncontrolled flow and seepage from damaged Kuwaiti oil wells were developed. Seven such oils collected from various lakes in different Kuwaiti oilfields had high contents of salts (up to 15 wt%) and water (up to 50 vol.%), high kinematic viscosity (815 mm 2 s −1 at 50°C) and low API gravity (8.2° API). Washing with fresh water removed the salt and water by up to 29 and 12 vol.%, respectively. Further washing increased the oil-water emulsion owing to the flocculant precipitation of waxy materials and high-molecular-weight compounds. The application of demulsifier, fresh water and heat broke the emulsion and allowed the water to settle out. The clean, water-free crude oil was similar in quality to a typical medium-API crude residue boiling > 300°C. This demonstrates that the oil had lost most of its light hydrocarbons.

The Treatment of Weathered Crude Oil in Kuwait

During the Gulf War about 740 oil wells were blown up by the Iraqi forces, and the unburnt oil flooded from these wells to form oil lakes. This resulted in one of the largest oil slicks in the world, causing serious damage to the marine life in the Gulf region. The oil which is exposed to atmospheric weather over a period is called ‘weathered crude oil feed stock’, and it is important to treat this oil not only from the economical point of view but also to consider the environmental pollution which is created. The Government of Kuwait, represented by Kuwait Oil Company (KOC) has made its best attempts to treat this oil, and most of the oil lakes have now been cleared. The objective of this study is to report and evaluate different treatment methods and measures to control and manage these oil lakes.

Enhancement of Biodegradation of Alaskan Weathered Crude Oil Components by Indigenous Microbiota with the use of Fertilizers and Nutrients

ABSTRACT Bench-scale biodegradability studies of the Alaskan weathered crude oil were undertaken as part of the bioremediation project for the shorelines of Prince William Sound Alaska, contaminated by the Exxon Valdez oil spill. The purpose of the studies was to evaluate the ability of the indigenous microbial consortium of the seawater and island beach areas to biodegrade the weathered crude oil's alkane hydrocarbon and polynuclear aromatic (PAH) constituents in batch-type respirometric reactors and shaker flask systems. Biodegradation studies used Inipol EAP22 and water-soluble nitrogen and phosphorus-containing solution (OECD) as the fertilizer nutrient source. In the respirometric studies, the unpolluted beach material in seawater was spiked with 1,000, 300, and 100 mg/L of weathered crude oil and with Inipol at 5 percent of oil weight or with OECD stock solution concentrates. The contents were brought up to 1,000 mL with seawter. Unpolluted beach material spiked with 10,000, 3,000, and 1,000 mg/L of weathered crude oil and with either Inipol at 5 percent of oil weight or with OECD inorganic salts in 1,000 mL of seawater were used in shaker flask microcosm studies. Temperature of incubation in both studies was 15° C, and culture systems were incubated in darkness. Cumulative oxygen uptake data, growth data, and gas chromatography/mass spectrometry analysis data demonstrate almost complete utilization of the alkane hydrocarbon constituents in the presence of Inipol fertilizer and OECD synthetic medium, and significant biodegradation of the PAH constituents after six weeks of incubation. Control experiments without Inipol or OECD nutrients demonstrated absence of biodegradative activity.

The Effects of Weathered Crude Oil from the M/T Alvenus Spill on Eggs and Yolk-Sac Larvae of Red Drum (Sciaenops ocellatus)

The Biitish tanker M/T ALVENUS ran aground 16.1 km south of Cameron, Louisiana, on 30 July 1984. An estimated 10,157 MT of Venezuelan crude oil were spilled into the Gulf of Mexico. Approximately 2,700 MT of the heavy viscous oil impacted beaches and an additional 1,360 MT remained in the subtidal areas of west Galveston Island, about 160 km southwest of the accident site. Red drum, which spawn in the Gulf of Mexico in the fall, could have been seriously impacted by oil concentrations potentially lethal to eggs or larvae. The impact of weathered crude oil on the survival, growth, and morphological development of red drum eggs and larvae was assessed in the laboratory. Equal numbers of eggs were randomly assigned to one of six treatments of weathered crude oil (control, 50, 100, 500, 1,000 and 2,000 mg/l) and observed through the yolk-sac stage. There were no differences in mean survival, length of surviving larvae, and frequency of morphological abnormalities among treatments (01 4 0.05). In addition, the frequency of spinal deformity and abnormal mouth development was low in all treatments. The initial chemical composition of the fresh crude oil and the seasonally warm weather contributed to the natural degradation of the soluble toxic components.