Crude Oil Hydrocarbons Research Articles

Alkaliphilic and halophilic hydrocarbon-utilizing bacteria from Kuwaiti coasts of the Arabian Gulf

Green animate materials from the intertidal zone of the Arabian Gulf coast accommodated more alkaliphilic and halophilic bacteria than inanimate materials. The alkaliphilic oil-utilizing bacteria, as identified by their 16S ribonucleic acid sequences, belonged to the following genera arranged in decreasing frequences: Marinobacter, Micrococcus, Dietzia, Bacillus, Oceanobacillus, and Citricoccus. The halophilic oil-utilizing bacteria belonged to the genera: Marinobacter, Georgenia, Microbacterium, Stappia, Bacillus, Isoptericola, and Cellulomonas. Most isolates could grow on a wide range of pure n-alkanes and aromatic compounds, as sole sources of carbon and energy. Quantitative gas liquid chromatographic analysis showed that individual isolates attenuated crude oil and representative pure hydrocarbons in culture. The optimum pH for most of the alkaliphilic genera was pH 10, and the optimum salinity for the halophiles ranged between 2.5 and 5% NaCl (w/v). It was concluded that as far as their microbial makeup is concerned, oily alkaline and saline intertidal areas of the Kuwaiti coasts have a self-cleaning potential.

Biomarkers of polycyclic aromatic hydrocarbon (PAH)-associated hemolytic anemia in oiled wildlife

Polycyclic aromatic hydrocarbons (PAHs) in crude oil cause a range of adverse effects in oiled seabirds, one of the most common being hemolytic anemia via oxidative attack of erythrocytes by PAH metabolites resulting in hemoglobin leakage and formation of Heinz bodies. In such cases, haptoglobin and ferritin are up-regulated to sequester free Hb and iron in the circulation. We investigated these plasma proteins as biomarkers of PAH-induced Heinz body hemolytic anemia in oiled seabirds. Concentration ranges of PAHs, HAP and FT in plasma samples were 10–184 ng/ml, 0–2.6 mg/ml and 0–7.6 ng/ml, respectively. Dose–response relationships between plasma PAH exposure and haptoglobin and ferritin (FT) were investigated, and evidence of erythrocyte Heinz body formation studied in 50 oiled common guillemots stranded on the Norfolk Wash coast (East England). Haptoglobin was negatively correlated, and FT was positively correlated with PAH exposure. Heinz bodies were also observed confirming the toxic mechanism causing hemolytic anemia and counts were positively correlated with exposure. Our results support the application of these complementary biomarkers to assess hemolytic effects of oiling in wildlife biomonitoring, which also discriminate the influence of hemolytic versus inflammatory effects in oiled guillemots.

Changes in the chemical components of light crude oil during simulated short term weathering

To unambiguously identify spilled oils and to link them to the known sources are extremely important in settling questions of environmental impact and legal liability. The fate and behavior of spilled oils in the environment depend on a number of physicochemical and biological factors. This paper presents the results regarding changes in chemical composition of light crude oil during simulated short-term weathering based on natural environmental conditions. The results show that the saturated hydrocarbons of the light crude oil mainly distribute between n-C8 and n-C23 and the most abundant n-alkanes are found in the n-C10 to n-C16. The main chemical components of the light crude oil are n-alkanes and isoprenoids. The aromatic compounds are subordinate chemical components. Under the conditions of the weathering simulation experiment, n-alkanes less than n-C12, toluene and 1,3-dimethyl benzene are lost after 1 d weathering, the n-C13, n-C14, naphthalene and 2-methyl-naphthalene are lost on the fifth day of weathering, and n-C15 alkane components show certain weatherproof capability. The ratios n-C17/pristane and n-C18/phytane are unaltered and can be used to identify the source of the light crude oil during the first 8 d of weathering. After 21 d, the ratio pristine/phytane can not provide much information on the source of the spilled light crude oil. Triterpanes (m/z 191) as biomarker compounds of light crude oil are more valuable.

Enhanced bioremediation of crude oil utilizing lipophilic fertilizers

Bioremediation is being increasingly seen as an affective, environmentally friendly treatment for contaminated shorelines from marine oil spills. Oil bioremediation is limited by the availability of nitrogen and phosphorous, which are needed by the bacteria and are not present in sufficient amounts for the biodegradation of the spilled hydrocarbons. The supply of these two essential elements as water-soluble salts presents several problems. These include the rapid dilution of the salts in the large volumes of polluted sea water as well as their utilization by other bacteria that do not degrade oil. In addition, by increasing the concentration of mobile nitrogen further environmental problems could potentially be created. As an alternative, hydrophobic sources of nitrogen and phosphorous have been used that have a low solubility in water and hence, they can overcome these problems, however, many of these bioremediation agents have proven to be somewhat toxic. The aim of this study was to examine the effects of lipophilic fertilizers of natural origin (uric acid and lecithin) on the degradation of crude oil hydrocarbons in comparison with the degradation that is achieved by commercial bioremediation agents. Biodegradation was quantified by GC/MS analysis of selected components. Petroleum degraders were measured by MPN analysis. From a series of 18 days long experiments it was found that the saturated fraction of the residual oil was degraded more readily and extensively than the aromatic fraction and the bacterial growth of the biostimulated solutions is much greater compared to the control. The results showed that the treatment of oil spills with uric acid and lecithin is very effective in a period of almost 7 days. Uric acid and lecithin can stimulate microbial growth from 3.65 to 1.9×10 4 MPN/mL within 7 days and thus lead to extensive degradation of oil hydrocarbons in comparison to the control and S200 solutions. Uric acid and lecithin proved to be excellent biostimulant agents in combating oil spills.

Improving the Effectiveness of Crude-Oil Hydrocarbon Biodegradation Employing Azotobacter chroococcum as Co-Inoculant

Azotobacter chroococcum has a great potential as biosurfactant producing bacteria and was used as co-inoculant to promote the rate of hydrocarbon biodegradation. The rate of hydrocarbon biodegradation were 0.01212, 0.01582, and 0.01766 per day for Acinetobacter sp., Bacillus cereus and the consorsium culture respectively. On the other hand, the rates of biodegradation using Azotobacter as co-inoculant were 0.1472, 0.01612, and 0.02709 g per day. Azotobacter chroococcum co-inoculant has the capability of increasing biodegradation efficiency of crude oilhydrocarbon. The biodegradation efficiency of petroleum hidrocarbon was increated by 13.4, 14.6, and 14.4% within the Petrobacter cultures.

Alterations in the Concentrations of Liver Mitochondrial DNA, Cytoplasmic Total Hydrocarbon and Calcium in Guinea Pigs after Treatment with Nigerian Light Crude Oil

The alteration of cellular calcium sequestration has been postulated to be a primary mechanism in the initiation of irreversible cell damage. Crude oil has been shown to cause concentration- dependent inhibition of calcium influx and mitochondrial swelling which may relate to its toxicity. Nigerian 'Bonny' Light Crude Oil (BLCO) is produced in the Niger-Delta region of Nigeria where oil spills are frequent and can endanger human-health, yet BLCO has not been studied in this regard. We have studied the effects of two doses of BLCO on mitochondrial DNA (mt.DNA), cytoplasmic total hydrocarbon concentrations (cyt.THC) and cytoplasmic Ca2+ (cyt.Ca2+) concentrations in livers of adult male guinea pigs exposed by intraperitoneal injection. The results showed that at 2.5 and 5.0 (ml/kg bw), BLCO caused dose-related increases in mt.DNA concentrations (128% and 485%) respectively over the controls, and cyt.THC (47.5% and 100%) respectively; while it caused near-100% decrease in cyt.Ca2+ concentrations (94% and 96.8%) respectively lower than the controls. These results suggest that BLCO caused the increased availability of crude oil hydrocarbons in the liver cells, and subsequent induction of unscheduled mt.DNA synthesis, and alteration of mitochondrial/endoplasmic reticulum Ca2+ sequestration or ca2+ - concentration gradient, leading to the inhibition of Ca2+ influx into the cytosol. These events may explain the probable hepatotoxicity of BLCO.

The effect of source and maturity on the stable isotopic compositions of individual hydrocarbons in sediments and crude oils from the Vulcan Sub-basin, Timor Sea, Northern Australia

Recent work has demonstrated the effect of maturation on the stable hydrogen isotopic compositions (δD) of individual sedimentary hydrocarbons ( n-alkanes, pristane and phytane) in a series of marine source rocks from the Perth Basin (Western Australia). There was an enrichment in deuterium (D) in the hydrocarbons with increasing maturity, attributed to isotopic exchange associated with thermal maturation. An initial, large (≈115‰) biologically derived difference between the δD values of n-alkanes and isoprenoids gradually decreased as pristane and phytane became enriched in D, while the n-alkanes generally remained at constant isotopic composition. This work has now been extended to include a series of Late Jurassic sediments from the lower Vulcan Formation of the Vulcan Sub-basin (Timor Sea, Northern Australia), where the δD values of n-alkanes and isoprenoids show similar trends to those observed for the Perth Basin. The enrichment in D in isoprenoids correlates strongly with traditional maturity parameters and is shown to be related to the epimerisation of pristane and phytane. Pristane and phytane extracted from a post-mature Paqualin-1 sediment are significantly enriched in D relative to the n-alkanes, indicating that D enrichment persists at very high maturity, more so for regular isoprenoids than n-alkanes. This supports the notion that hydrogen (H/D) exchange causes the observed shift in δD values, and not free radical hydrogen transfer. A mechanism is proposed which can account for both H/D exchange and epimerisation of pristane and phytane in the sedimentary environment. Pristane is enriched in D relative to phytane throughout the Vulcan Sub-basin sequences, attributed to a lower relative algal input to the isoprenoids, and indicating that they exchange hydrogen at similar rates during maturation. Crude oils and condensates from the sub-basin were also analysed to evaluate their source and thermal maturity and the results complement previous molecular and stable carbon isotopic analysis. The δD values of n-alkanes and regular isoprenoids largely support the previous classification of Vulcan Sub–basin crude oils and condensates into two groups: Group A, having a marine source affinity and Group B, a terrigenous source affinity. Some oils and condensates are suggested to be a mixture of sources A and B, or A and other as yet unknown sources. Tenacious-1 crude oil (formerly a Group A oil) contains n-alkanes with more positive δD values than other Group A oils and is suggested to have been mixed with another source of more mature hydrocarbons. The Group A crude oils and condensates show an upward inflection in the n-alkane δD profile from n-C 11 to n-C 15, which is suggested to represent an addition of D-enriched lower molecular weight n-alkanes from a more mature wet gas/condensate to an initial oil charge. The small differences between the δD values of the n-alkanes and regular isoprenoids in the crude oils and condensates indicate that significant H/D exchange has taken place, implying that the samples were generated from mature source rocks.

Identification of Water-Soluble Heavy Crude Oil Organic-Acids, Bases, and Neutrals by Electrospray Ionization and Field Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

We identify water-soluble (23 degrees C) crude oil NSO nonvolatile acidic, basic, and neutral crude oil hydrocarbons by negative-ion ESI and continuous flow FD FT-ICR MS at an average mass resolving power, m/deltam50% = 550,000. Of the 7000+ singly charged acidic species identified in South American crude oil, surprisingly, many are water-soluble, and much more so in pure water than in seawater. The truncated m/z distributions for water-soluble components exhibit preferential molecular weight, size, and heteroatom class influences on hydrocarbon solubility. Acidic water-soluble heteroatomic classes detected at >1% relative abundance include O, O2, O3, O4, OS, O2S, O3S, O4S, NO2, NO3, and NO4. Parent oil class abundance does not directly relate to abundance in the water-soluble fraction. Acidic oxygen-containing classes are most prevalent in the water-solubles, whereas acidic nitrogen-containing species are least soluble. In contrast to acidic nitrogen-containing heteroatomic classes, basic nitrogen classes are water-soluble. Water-soluble heteroatomic basic classes detected at >1% relative abundance include N, NO, NO2, NS, NS2, NOS, NO2S, N2, N2O, N2O2, OS, O2S, and O2S2.

Monitoring Soil Ecosystem Recovery Following Bioremediation of a Terrestrial Crude Oil Spill With and Without a Fertilizer Amendment

The effect of fertilizer as an amendment in the bioremediation of a terrestrial crude oil spill has been investigated in terms of the subsequent recovery of the soil ecosystem following bioremediation. Two different spills in the same area with different initial hydrocarbon concentrations (33,500 mg kg-1 and 4,800 mg kg-1) were compared. At the higher initial hydrocarbon concentration fertilizer addition increased the rate of bioremediation (first-order rate constant of 0.0033 days-1 with fertilizer amendment vs. 0.0020 days-1 without) and resulted in more rapid recovery of soil bacteria (numbers, community structure, diversity) and nematodes (trophic diversity and community structure). The effect of the fertilizer amendment was more significant at the higher initial concentration of crude oil hydrocarbons, presumably due to greater depletion of soil nutrient pools in the absence of the amendment. A second objective of this work was to identify sensitive and cost-effective ecological indicators useful for monitoring the recovery of soil ecosystems impacted by crude oil. Ecological indicators used included: microbial numbers, community structure, and activity as revealed by biomarker analysis (phospholipid fatty acids); nitrogen availability; nematode numbers and community structure (trophic groups and colonizer-persister classes); and ultimately, plant cover and diversity. All ecological indicators investigated were sensitive to disturbances in the soil food web in a hydrocarbon-impacted site. However, nematode community structure analysis offered the greatest sensitivity coupled with low cost and readily available sources for the analysis.

Resistance of toxic alkylcyclohexyltetralins to biodegradation by aerobic bacteria

A series of alkylcyclohexyltetralins (ATEs) and an alkylcyclohexylnaphthalene were exposed to the common aerobic bacterium, Pseudomonas fluorescens and separately to a consortium of aerobic bacteria previously shown to rapidly and extensively degrade crude oil hydrocarbons. The ATEs and naphthalene were resistant to biodegradation in laboratory experiments at room temperature for up to 119 days under conditions that led to the rapid oxidation of n-alkanes and the other major resolved components of North Sea crude oil. The higher molecular-weight ATEs, particularly those with branched chain substituents, were resistant to aerobic degradation even under biodegradation conditions defined as ‘heavy’.

Using electrospray‐assisted pyrolysis ionization/mass spectrometry for the rapid characterization of trace polar components in crude oil, amber, humic substances, and rubber samples

We describe the use of electrospray-assisted pyrolysis ionization/mass spectrometry (ESA-Py/MS) to selectively ionize trace polar compounds that coexist with large amounts of nonpolar hydrocarbons in crude oil, amber, humic substances, and rubber samples. Samples of different origins are distinguished rapidly by their positive ion ESA-Py mass spectra without prior separation or chemical pretreatment. During ESA-Py analysis, the samples in their solid or liquid states were pyrolyzed at 590, 630 or 940 degrees C using a commercial Curie-point pyrolysis probe. The gaseous pyrolysates were transferred into a glass reaction cell. The polar compounds (M) in the pyrolysates were then ionized by electrospray ionization (ESI), yielding protonated molecules (MH+). Although the major components of the pyrolysates are nonpolar hydrocarbons, their lack of functional groups that can receive a proton in the ESA-Py source results in no hydrocarbon ion signals being produced; thus, the positive ions detected in ESA-Py mass spectra all result from trace polar components in the pyrolysates.

Hydrocarbon Uptake by Roots of Vicia faba (Fabaceae)

Vicia faba was grown in crude oil polluted soil and its roots were extracted for the detection and estimation of hydrocarbons. Saturated and unsaturated Aliphatic Hydrocarbons (AHs) ranging from C(22) to C(36) were identified in AHs fraction. However, PAHs were not present in the same extract. This could be due to the fact that PAHs being toxic compounds are not accumulated in the plant root extracts of V. faba grown in crude oil polluted soil. Three phytoalexins were identified and estimated by mass spectrometric analysis in the root extracts of V. faba. These three compounds are 2-t-butyl-4-(dimethyl benzyl) phenol, 2, 4-bis (dimethyl benzyl) phenol and 2,4-bis (dimethyl benzyl)-6-butyl phenol. These phenolics in V. faba are being reported for the first time. These compounds are presumably elicited as a direct stress on crude oil hydrocarbons on the roots of this plant.

Differentiation of Romashkino crude oils according to biomarker hydrocarbon parameters

The trends in composition of higher biomarker hydrocarbons (steranes and tri-, tetra-, and pentacyclic terpanes) in crude oils from diachronous producing complexes of deposits of the Romashkino oil field, which occurs in the central part of the South Tatarian arch, were studied. On the basis of variations in molecular biomarker parameters that reflect the type of source organic matter and the facies conditions of its accumulation and early diagenesis, the oils are classified with three groups.

Causation for Variable n-Alkylcyclohexane Distributions in Distillate Nonaqueous Phase Liquids from Mandan, North Dakota

N-alkylcyclohexanes (CHs) occur as a homologous series of relatively degradation-resistant hydrocarbons in crude oil and certain petroleum fuels. The distribution of these in distillate fuels is largely a function of the distillation and blending practices of these fuels. Research previously published in this journal (Hostettler and Kvenvolden, 2002) reported that the distribution of CHs in subsurface distillate-dominant nonaqueous liquids phase (NAPLs) from Mandan, ND, had been altered by anaerobic biodegradation that resulted in a shortening of the CHs' alkyl side-chains by a novel, terminal carbon cleavage mechanism. This article presents evidence that supports a more plausible interpretation. These authors contend the available data, which includes soil data unavailable to Hostettler and Kvenvolden (2002) at the time their work was completed, demonstrate that the variable CHs distribution in the Mandan NAPLs is attributable to the mixing of different types of distillate fuels (e.g., kerosene and diesel fuels) that contained CH in various proportions, resulting in variable signatures of CHs in the NAPLs.

Deciphering biodegradation effects on light hydrocarbons in crude oils using their stable carbon isotopic composition: A case study from the Gullfaks oil field, offshore Norway

Compound-specific isotope analysis has become an important tool in environmental studies and is an especially powerful way to evaluate biodegradation of hydrocarbons. Here, carbon isotope ratios of light hydrocarbons were used to characterise in-reservoir biodegradation in the Gullfaks oil field, offshore Norway. Increasing biodegradation, as characterised, for example, by increasing concentration ratios of Pr/ n-C 17 and Ph/ n-C 18, and decreasing concentrations of individual light hydrocarbons were correlated to 13C-enrichment of the light hydrocarbons. The δ 13C values of C 4 to C 9 n-alkanes increase by 7–3‰ within the six oil samples from the Brent Group of the Gullfaks oil field, slight changes (1–3‰) being observed for several branched alkanes and benzene, whereas no change (<1‰) in δ 13C occurs for cyclohexane, methylcyclohexane, and toluene. Application of the Rayleigh equation demonstrated high to fair correlation of concentration and isotope data of i- and n-pentane, n-hexane, and n-heptane, documenting that biodegradation in reservoirs can be described by the Rayleigh model. Using the appropriate isotope fractionation factor of n-hexane, derived from laboratory experiments, quantification of the loss of this petroleum constituent due to biodegradation is possible. Toluene, which is known to be highly susceptible to biodegradation, is not degraded within the Gullfaks oil field, implying that the local microbial community exhibits rather pronounced substrate specificities. The evaluation of combined molecular and isotopic data expands our understanding of the anaerobic degradation processes within this oil field and provides insight into the degradative capabilities of the microorganisms. Additionally, isotope analysis of unbiodegraded to slightly biodegraded crude oils from several oil fields surrounding Gullfaks illustrates the heterogeneity in isotopic composition of the light hydrocarbons due to source effects. This indicates that both source and also maturity effects have to be well constrained when using compound-specific isotope analysis for the assessment of biodegradation.

Distribution and properties of high molecular weight hydrocarbons in crude oils and oil reservoir of Shengli oil field, China

With the development of high temperature gas chromatography (HTGC), it is possible to examine high molecular weight hydrocarbons (HMWHCs) up to about C 120. Utilizing the difference in solubility between HMWHCs and middle-low molecular weight ones, HMWHCs were separated from other components and concentrated. In order to keep the comparability of indies between conventional methods and HTGC, all samples from Shengli oil field of China were analyzed by several kinds of instruments. The contents and distribution characteristics of HMWHCs in various types of oils and the ability of anti-biodegradation of HMWHCs were summarized. The ubiquitous occurrence of HMWHCs was found. The ability of anti-biodegradation of HMWHCs is approximately equivalent to that of regular steranes. Dense sampling and analyses with HTGC and conventional instruments revealed the low mobility and heterogeneity of HMWHCs in oil reservoir of Gaoxie 73 well. The contents of HMWHCs in oil layers were obviously more than that in oils produced.

Comparisons between Open Column Chromatography and HPLC SARA Fractionations in Petroleum

Two chromatographic methods for the SAR (saturates, aromatics, and resins) separation of crude oil samples are compared. Open column chromatography (OPC) using silica and subsequent elution with heptane, toluene, and toluene/methanol is contrasted with flow reversal (back-flushing) high-performance liquid chromatography (HPLC) using an amino-modified silica column with heptane, dichloromethane, and chloroform as elution solvents. The fractions obtained in both methods have been characterized with gel permeation chromatography−THF and FTIR. It is demonstrated that the OPC system is unable to effectively separate the aromatic nonpolar hydrocarbons in crude oil from the resin fraction. The OPC toluene mobile fraction corresponds mostly to resin-type material, but some nonpolar aromatics are present. The toluene/methanol mobile fraction from OPC corresponds only to the most polar part of the resin fraction. Different sample:silica mass ratios from 1:4 to 1:20 were tested for the OPC system. Similar separation...

05/01438 Effect of maturation on the indigenous δD signatures of individual hydrocarbons in sediments and crude oils from the Perth Basin (Western Australia): Dawson, D. et al. Organic Geochemistry, 2005, 36, (1), 95–104

05/01438 Effect of maturation on the indigenous δD signatures of individual hydrocarbons in sediments and crude oils from the Perth Basin (Western Australia): Dawson, D. et al. Organic Geochemistry, 2005, 36, (1), 95–104

Selectivity of a Model Zeolite Ring over Hydrocarbons with Different Symmetry, Travelling with Different Orientations and Speeds

We explore the selectivity of a model zeolite ring over representative hydrocarbons of crude oil. The model ring consists of 7 silicon tetrahedral units and one chemically active aluminum site through which hydrocarbons with symmetries varying from almost spherically symmetric to linear chains (1D), planar (2D), and pyramidal (3D) structures diffuse. The selectivity is further investigated when the hydrocarbons travel with different orientations and speeds. The semiclassical Born-Oppenheimer molecular dynamics approximation is used to characterize the chemical dynamics, as well as to determine the energetics and reaction products. The simulations reveal noticeable differences in energy profiles and charge populations. Our results are important to understand aspects of mass transport and some of the factors that control the catalytic activity in zeolites.

Effect of maturation on the indigenous δD signatures of individual hydrocarbons in sediments and crude oils from the Perth Basin (Western Australia)

We measured the stable hydrogen isotopic composition ( δD) of selected aliphatic hydrocarbons in nine sediments of various maturity and two crude oils, all from the northern Perth Basin (on-shore, Western Australia). The sediments and crude oils are from the Lower Triassic Hovea Member (Sapropelic Interval) of the Kockatea Shale. The n-alkanes, pristane and phytane from two immature sediments have δD values that represent the expected isotopic compositions of their precursors. Phytane is enriched in deuterium (D) relative to pristane in all sediment extracts and crude oils; this is attributed to either different sources, or to different isotopic effects during their derivation from phytol. With increasing maturity, pristane and phytane become enriched in D while the n-alkanes generally remain at a constant isotopic composition. A more rapid enrichment of D in isoprenoids relative to n-alkanes with increasing maturity suggests that hydrogen isotopic exchange is occurring via a carbocation mechanism. The phytane diastereomer ratio for each of the sediments correlates linearly with the progressive enrichment of D in phytane and therefore maturity, suggesting that significant hydrogen exchange occurs at the chiral carbons of phytane. The δD values of pristane and phytane from the crude oils are similar or more positive relative to the δD values of the n-alkanes. The average δD values of pristane and phytane for the sediments correlate well with equivalent vitrinite reflectance values, as does the conventional biomarker maturity parameter T s/ T m, indicating that δD values may be useful for establishing maturity over a wider range than conventional biomarker parameters. The results provide further evidence that care must be taken not to over-interpret δD values of sedimentary hydrocarbons in samples of high thermal maturity.